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Sample records for supragingivally complicated crown

  1. Rehabilitation of complicated crown-root fracture by invisible approach.

    Science.gov (United States)

    Rani, V Leela; Rajalingam, S; Hemalatha, R; Jananee, J

    2016-10-01

    Dental trauma is one of the most common and significant problems met in all dental offices almost every day. In particular, injury to the anterior teeth is more vulnerable as it may affect the psychosocial behavior, severe emotional complications can occur leading to disturbances in their mental attitude. Cosmetic (lingual) orthodontics is the recent development in the field of dentistry in the last few decades. Patients are more concerned about their appearance during the treatment and are affected by psychosocial issues because of labially placed brackets, thus leading to the evolution of lingual orthodontic appliances. In this article, we are sharing our clinical experience treating a complicated crown-root fracture using the lingual orthodontic technique.

  2. Rehabilitation of complicated crown-root fracture by invisible approach

    Directory of Open Access Journals (Sweden)

    V Leela Rani

    2016-01-01

    Full Text Available Dental trauma is one of the most common and significant problems met in all dental offices almost every day. In particular, injury to the anterior teeth is more vulnerable as it may affect the psychosocial behavior, severe emotional complications can occur leading to disturbances in their mental attitude. Cosmetic (lingual orthodontics is the recent development in the field of dentistry in the last few decades. Patients are more concerned about their appearance during the treatment and are affected by psychosocial issues because of labially placed brackets, thus leading to the evolution of lingual orthodontic appliances. In this article, we are sharing our clinical experience treating a complicated crown-root fracture using the lingual orthodontic technique.

  3. Autologous reattachment of complicated crown fractures using intra canal anchorage: Report of two cases

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    Kashetty Panchakshari Bharath; Raju Umaji Patil; Haalaswamy Vishwanath Kambalimath; Ashokan Alexander

    2015-01-01

    Crown fractures are most common form of dental trauma sustained by children and adolescents. Major portion of these crown fractures are uncomplicated. Complicated crown fractures though infrequent and account only 4-16%, is an enigma to any clinician. Autologus reattachment of the tooth fragment is a simple and conservative procedure in managing such crown fractures. The present article intends to report the successful clinical management of Autologus tooth fragment reattachment in two compli...

  4. Modern supragingival plaque control.

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    Iacono, V J; Aldredge, W A; Lucks, H; Schwartzstein, S

    1998-06-01

    Supragingival plaque control is essential for the maintenance of oral health. Despite the many chemotherapeutic agents available as mouthrinses and toothpastes, mechanical plaque removal is still the best method to achieve effective plaque control. This is due, in part, to the lack of development of oral antimicrobials with the effectiveness and substantivity of chlorhexidine gluconate but without its adverse effects of dental staining and calculus formation. The use of the numerous mechanical (manual and electric) oral hygiene devices extant and their effectiveness, however, are dependent upon patient dexterity and compliance and concomitant active professional treatment for the monitoring of home care, oral hygiene instruction and patient motivation. This paper evaluates the current methods available to reduce plaque and gingivitis with emphasis on their effectiveness at both supragingival plaque control and disease prevention. In addition, recent studies on the newer oscillating/rotating electric plaque removers and interdental cleaning devices will be discussed as related to their efficacy and compliance.

  5. Early complications and short-term failures of zirconia single crowns and partial fixed dental prostheses.

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    Pihlaja, Juha; Näpänkangas, Ritva; Raustia, Aune

    2014-10-01

    Ceramic single crowns fabricated from newer materials, especially zirconia, have shown relatively high survival rates. However, early reversible complications may increase the risk of an irreversible failure later. The purpose of the study was to evaluate the early complications and short-term failures of zirconia single crowns and partial fixed dental prostheses (FDPs) made by predoctoral dental students. Data were collected from the patient records. Altogether, 264 zirconia single crowns and 120 FDPs (342 abutments and 190 pontics) were fabricated for 173 patients between 2007 and 2010. Early complications were recorded during the prosthetic treatment phase, and short-term failures were recorded during the first year in use. The most frequent early complications were localized gingival irritation (1.9% of single crowns and 2.5% of FDP) and postoperative tooth sensitivity (0.4% of single crowns and 3.3% of FDPs). Pulp exposure during preparation was recorded in 3 abutment teeth of the FDPs. The most frequent short-term failure was chipping of the veneering porcelain (0.8% for single crowns, 0.8% for FDPs). One crown lost cementation because of poor retention (0.4%), and 2 FDPs failed because of framework fractures (1.7%). The most frequent early complications were localized gingival irritation and postoperative tooth sensitivity, and the most frequent short-term failure was chipping of the veneering porcelain. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  6. Complication rate of molar crowns: a practice-based clinical evaluation.

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    Rinke, S; Schäfer, S; Roediger, M

    2011-01-01

    This practice-based study evaluates the initial clinical performance of conventionally luted metal-ceramic and zirconia molar crowns fabricated with a prolonged cooling period of the veneering porcelain. Forty-nine patients were treated (group A: high precious alloy + low fusing porcelain; group B: zirconia crowns). All zirconia crowns were veneered with a modified porcelain firing cycle including a 6-minute cooling period. Ninety-two restorations (74 vital abutments/18 nonvital abutments) were evaluated after a mean observation period of 18.2 +/- 4.6 months. No complete failures or loss of vitality were recorded in either group. Two events were recorded in group A (1 loss of retention/1 minor ceramic chipping zirconia crowns fabricated with a modified porcelain firing. The modified firing of the zirconia porcelain seems to decrease the risk for early ceramic chipping in the molar area, leading to a technical complication rate comparable to that of metal-ceramic crowns.

  7. Risk factors for technical and biological complications with zirconia single crowns.

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    Rinke, Sven; Lange, Katharina; Roediger, Matthias; Gersdorff, Nikolaus

    2015-11-01

    This practice-based study evaluated the clinical performance and risk factors for biological and technical complications with conventionally luted zirconia crowns. Sixty-eight patients (39 female) with a total of 323 restorations placed on 219 vital teeth, 69 endodontically treated teeth (ETT), and 41 implants (incisors, 96; premolars, 89; molars, 138; observational period, 79.7 ± 14.2 months) underwent a clinical follow-up examination and were included in the study. Time-dependent survival (in situ), success (event free), and veneering ceramic fracture (VCF) rates were calculated and analyzed relative to the following risk factors: smoking status, location of the crown, and type of abutment. Fifty-three complete failures were recorded. A significant influence of the abutment type on survival could be detected (p = 0.033): ETT demonstrated a significantly (p = 0.029) lower 7-year survival rate (73.8%, 95% confidence interval [95% CI] 0.600-0.876) than crowns placed on implants (90.0%, 95% CI 0.814-0.990). The success rate of the crowns was significantly influenced by the location of the restoration (p = 0.0058). A total of 75.6% (95% CI 0.648-0.864) of the anterior crowns remained event free, compared to 50.4% (95% CI 0.388-0.621) of the molar crowns. Furthermore, the location of the crowns affected the VCF rate (p = 0.018, event-free anterior teeth 95.2% (95% CI 0.880-1), event-free molars 80.9% (95% CI 0.706-0.913)). Survival and success rates were significantly influenced by the type of abutment and the location of the restoration. More complete failures should be expected for crowns placed on ETT, while crowns on molars demonstrated more biological and technical complications than anterior zirconia crowns.

  8. Management of complicated crown-root fracture in central incisors using intentional replantation with 180° rotation: A case report

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    Reyhaneh Faghihian

    2017-01-01

    Full Text Available Introduction: Complicated crown-root fractures are rare and their treatment is complex. Numerous methods such as crown lengthening and orthodontic or surgical extrusion have been described for the treatment of crown-root fracture. The aim of this study was to report managing complicated crown-root fracture using intentional replantation with 180° rotation. Case report: This case report demonstrates successful management of complicated crown-root fracture in central incisor of a 10-year-old boy using intentional replantation with 180° rotation. Discussion: At 18-month follow-up, the replanted tooth revealed normal function with no obvious resorption.

  9. Rehabilitation of complicated crown-root fracture by invisible approach

    OpenAIRE

    Rani, V. Leela; Rajalingam, S.; Hemalatha, R.; Jananee, J.

    2016-01-01

    Dental trauma is one of the most common and significant problems met in all dental offices almost every day. In particular, injury to the anterior teeth is more vulnerable as it may affect the psychosocial behavior, severe emotional complications can occur leading to disturbances in their mental attitude. Cosmetic (lingual) orthodontics is the recent development in the field of dentistry in the last few decades. Patients are more concerned about their appearance during the treatment and are a...

  10. Management of Complicated Crown Fracture by Reattachment Using Fiber Post: Minimal Intervention Approach

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    Raut, Ambar W.; Mantri, Vijay; Shambharkar, Vaibhao I.; Mishra, Mitul

    2018-01-01

    Anterior crown fractures are a common form of traumatic dental injuries that mainly affect the maxillary incisors, especially in children and adolescents. Complicated crown fractures although less common, pose a challenge to the clinician. The main objective while treating such cases is successful pain management and immediate restoration of function, esthetics and phonetics. Since the development of the adhesive dentistry, the patient's own fragment can be used to restore the fractured tooth. Reattachment of fractured tooth fragments offers a viable restorative alternative. The procedure provides good and long-lasting esthetics, because the original morphology, color, and surface texture are preserved. This article reports management of complicated crown fracture in a young adult and a middle-aged adult that were successfully treated by reattachment technique. The teeth were endodontically treated followed by esthetic reattachment of the fractured fragment using the glass fiber post. To improve the adhesion between fractured and remaining fragment, circumferential beveling and internal groove placement were done. PMID:29456401

  11. Implant-supported single crowns predictably survive to five years with limited complications.

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    Salinas, Thomas; Eckert, Steven

    2012-09-01

    An electronic MEDLINE search was conducted to identify cohort studies, prospective or retrospective, describing clinical performance of implant-supported single crowns. Manual searches of bibliographies from full-text articles and related reviews were conducted using numerous scientific journals. Studies were included if the mean follow-up time was at least 5 years, if articles were published in the English or German language, if patients were physically examined, and if study details were sufficient for data extraction. Of the initial 3601 studies identified, only 26 were selected. No randomized control trials were identified. The 5-year survival and complications of implant-supported single crowns. The primary outcome measure in this study was survival of endosseous implants when used to support single crowns. In addition, the clinical performance of soft tissue (peri-implantitis) and hard tissue (bone level) was documented. Clinical complications of a biomechanical nature were recorded relative to fracture of restorative materials. Poisson's regression models were used to estimate failure and complication rates at 5 years. A systematic review of the scientific literature identified 26 studies from which data were extracted (1558 placed implants). Meta-analysis identified survival of implants used to support and retain single crowns at 96.8% (95% confidence interval [CI]: 95.9%-97.6% after 5 years). The survival rate of the single crown restorations documented in 13 studies was 94.5% (95% 92.5%-95.9%) with a significantly higher survival rate when metal ceramic crowns were used in comparison with all ceramic crowns (95.4% 93.6%-96.7%; 91.2% CI: 86.8%-94.2%). Soft tissue complications, including peri-implantitis, were observed in 9.7% of the single crowns, whereas bone loss exceeding 2 mm was identified on 6.3% of the implants over the 5-year study. Prosthetic or abutment screw loosening was observed in 12.7% of the restoration and screw fracture occurred in 0

  12. Complicated Crown-Root Fracture Treated Using Reattachment Procedure: A Single Visit Technique

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    Akhil Rajput

    2011-01-01

    Full Text Available Complicated crown-root fracture of maxillary central and lateral incisors is common in case of severe trauma or sports-related injury. It happens because of their anterior positioning in oral cavity and protrusive eruptive pattern. On their first dental visit, these patients are in pain and need emergency care. Because of impaired function, esthetics, and phonetics, such patients are quite apprehensive during their emergency visit. Successful pain management with immediate restoration of function, esthetics and phonetics should be the prime objective while handling such cases. This paper describes immediate treatment of oblique crown root fracture of maxillary right lateral incisor with reattachment procedure using light transmitting fiber post. After two and half years, the reattached fragment still has satisfying esthetics and excellent function.

  13. Autogenous tooth fragment reattachment: A multidisciplinary management for complicated crown-root fracture with biologic width violation

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    Vinaya Kumar Kulkarni

    2014-01-01

    Full Text Available Fractures of multiple permanent anterior teeth can be a traumatic experience for children, with functional, esthetic and psychological aspects. The treatment of complicated crown-root fractures (CRFs is more challenging when the biologic width is violated. This paper presents a case of 12-year boy with complicated CRF of teeth #12 and #21, and horizontal crown fracture of tooth #11. It was managed by endodontic treatment, mucoperiosteal surgery with osteotomy to visualize the fracture line for fragment reattachment, followed by fiber-post placement and restoration with polycarbonate crowns. Clinical and radiographic evaluation after 6 months was satisfactory with adequate functional and esthetic results.

  14. Technical and biological complications related to crown to implant ratio: a systematic review.

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    Quaranta, Alessandro; Piemontese, Matteo; Rappelli, Giorgio; Sammartino, Gilberto; Procaccini, Maurizio

    2014-04-01

    To review the occurrence of prosthetic failure and biological complications with respect to the crown to implant (C/I) ratio. Accurate search was made on the subject C/I ratio with the following criteria: (1) studies on humans with data on prosthetic failure and/or biological complications related to C/I ratio; (2) partial edentulous patients; (3) randomized clinical trials, prospective, longitudinal, retrospective, and multicenter studies with a minimum of 48 months mean follow-up; (4) language: English; (5) radiographic measurements by peri-apical x-ray; (6) implant material: titanium; and (7) no implant type selection was applied. Six articles were considered eligible for full-text analysis. Unfavorable C/I ratio can be considered a potential risk factor for single crown and abutment loosening (C/I ratio ≥ 1.46) and abutment fractures in posterior areas (C/I ratio ≥ 2.01). Despite the limited data, high C/I ratio may be related to some prosthetic failures. Unfavorable C/I ratio does not affect biological complications and implant failure.

  15. Twenty-year follow-up of metal-ceramic single crowns: a retrospective study.

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    Näpänkangas, Ritva; Raustia, Aune

    2008-01-01

    The aim of this clinical retrospective study was to evaluate the survival and success of single metal-ceramic crowns after 20 years. The biologic and technical complications as well as patient satisfaction were recorded. Fifty patients treated with 100 single metal-ceramic crowns attended the clinical 20-year follow-up examination. The mean follow-up time was 18.8 years (17.5 to 20.5 years). Twenty-one teeth with single crowns were extracted because of root fractures or esthetic or periodontal reasons. Ninety-seven percent of the subjects had no complaints about the esthetics of the crowns. The most common clinical findings were supragingival crown margins caused by gingival recessions, gingival bleeding on probing, and occlusal wear in opposing teeth. The success of the crowns after 20 years was 75%, and the survival was 78%. In the 20-year follow-up of single metal-ceramic crowns, there were few biologic and technical complications, and patients were satisfied with the crowns. Crown removal was in most cases the result of root fractures in single crowns with endodontic posts.

  16. Crown reattachment with complicated chisel-type fracture using fiber-reinforced post.

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    Stojanac, Igor; Ramic, Bojana; Premovic, Milica; Drobac, Milan; Petrovic, Ljubomir

    2013-12-01

    Maxillary incisors and specifically their crowns are the most common teeth involved in dental trauma because of their exposed position in the dental arch. Traumatized anterior teeth require quick functional and esthetic repair. In the case of a complex crown fracture, with the necessity of endodontic treatment, fiber-reinforced posts (FRC) were used to create a central support stump to restore the dental morphology. A 24-year-old male patient came to the dental clinic with dental injury to the maxillary left central incisor with a chisel-type fracture that extended subgingivally with a widely open pulp chamber. The patient reported a sports injury had occurred 1 day before. Provisional reposition of the crown was completed using a composite splint and after that endodontic treatment has been performed. Two days later, a fiber-reinforced composite resin post was placed into the canal and adhesive reattachment of the fragment also completed. The tooth was prepared for a composite resin veneer in the gingival third of the vestibular surface because of a visible fracture line. The combined use of a fiber-reinforced composite resin post and the original crown fragment is a simple and efficient procedure for the treatment of traumatized anterior teeth that appears to offer pleasing esthetic and functional results that is less invasive than conventional prosthodontic treatment. © 2012 John Wiley & Sons A/S.

  17. Management of Complicated Crown Fracture and Associated Impacted Mesiodens- Case Report with 3yrs Follow-up.

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    Samuel A, Victor; R, Mahesh; Gupta Y, Mohit

    2014-09-01

    Mesiodens being the most common type of supernumerary tooth, usually results in malocclusion, poor aesthetics and cyst formation if it is not corrected. The management protocol involves surgical removal. The situation can be complicated in young permanent dentition where there are a lot of chances of damage to the permanent dentition during surgical removal of impacted teeth. This article reports a case of impacted mesiodens which was diagnosed during management of complicated crown fracture. The case was followed up to 3years which showed a good bone formation. The article highlights the need for regular follow-up after surgical removal of impacted teeth in young children, to see any changes or damage in the developing permanent teeth.

  18. Crown lengthening procedures

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    AA. Khoshkhonejad

    1994-06-01

    Full Text Available Nowadays, due to recent developments and researches in dental science, it is possible to preserve and restore previously extracted cases such as teeth with extensive caries, fractured or less appropriate cases for crown coverage as well as teeth with external perforation caused by restorative pins. In order to restore the teeth with preservation of periodontium, we should know thoroughly physiological aspects of periodontium and protection of Biologic Width which is formed by epithelial and supracrestal connective tissue connections. Considering biologic width is one of the principal rules of teeth restoration, otherwise we may destruct periodontal tissues. Several factors are involved in placing a restoration and one of the most important ones is where the restoration margin is terminated. Many studies have been conducted on the possible effects of restoration margin on the gingiva and due to the results of these studies it was concluded that restoration margin should be finished supragingivally. However, when we have to end the restoration under Gingival Crest, First a healthy gingival sulcus is required. Also, we should not invade the biological width. Since a normal biologic with is reported 2 mm and sound tooth tissue should be placed at least 2 mm coronal to the epithelial tissue, the distance between sound tooth tissue and crown margin should be at least 4mm. Thus, performing crown lengthening is essential to increase the clinical crown length. Basically, two objectives are considered: 1 restorative 2 esthetic (gummy smile Surgical procedure includes gingivectomy and flap procedure. Orthodontic procedure involves orthodontic extrusion or force eruption technique which is controlled vertical movements of teeth into occlusion. Besides, this procedure can also used to extrude teeth defects from the gingival tissue. By crown lengthening, tooth extraction is not required and furthermore, adjacent teeth preparation for placing a fixed

  19. Impact of Oral Hygiene Discontinuation on Supragingival and Salivary Microbiomes

    DEFF Research Database (Denmark)

    Belstrøm, D; Sembler-Møller, M L; Grande, M A

    2018-01-01

    The purpose of the present study was to characterize and compare supragingival and salivary microbiotas during a 10-d period of oral hygiene discontinuation. We tested the hypothesis that the composition of the salivary microbiota will reflect local microbial changes associated with accumulated b...... from this study highlight the necessity of regular oral hygiene in the maintenance of oral homeostasis....

  20. Dental crowns

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    ... than metal crowns Match the color of other teeth May be a good choice if you have a metal allergy Porcelain fused to metal crowns: Are made from porcelain covering a metal crown Metal makes the crown stronger Porcelain part is more prone to fracture than crowns made of all porcelain After the ...

  1. All-ceramic or metal-ceramic tooth-supported fixed dental prostheses (FDPs)? A systematic review of the survival and complication rates. Part I: Single crowns (SCs).

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    Sailer, Irena; Makarov, Nikolay Alexandrovich; Thoma, Daniel Stefan; Zwahlen, Marcel; Pjetursson, Bjarni Elvar

    2015-06-01

    To assess the 5-year survival of metal-ceramic and all-ceramic tooth-supported single crowns (SCs) and to describe the incidence of biological, technical and esthetic complications. Medline (PubMed), Embase, Cochrane Central Register of Controlled Trials (CENTRAL) searches (2006-2013) were performed for clinical studies focusing on tooth-supported fixed dental prostheses (FDPs) with a mean follow-up of at least 3 years. This was complimented by an additional hand search and the inclusion of 34 studies from a previous systematic review [1,2]. Survival and complication rates were analyzed using robust Poisson's regression models to obtain summary estimates of 5-year proportions. Sixty-seven studies reporting on 4663 metal-ceramic and 9434 all-ceramic SCs fulfilled the inclusion criteria. Seventeen studies reported on metal-ceramic crowns, and 54 studies reported on all-ceramic crowns. Meta-analysis of the included studies indicated an estimated survival rate of metal-ceramic SCs of 94.7% (95% CI: 94.1-96.9%) after 5 years. This was similar to the estimated 5-year survival rate of leucit or lithium-disilicate reinforced glass ceramic SCs (96.6%; 95% CI: 94.9-96.7%), of glass infiltrated alumina SCs (94.6%; 95% CI: 92.7-96%) and densely sintered alumina and zirconia SCs (96%; 95% CI: 93.8-97.5%; 92.1%; 95% CI: 82.8-95.6%). In contrast, the 5-year survival rates of feldspathic/silica-based ceramic crowns were lower (pcrowns exhibited significantly lower survival rates in the posterior region (pcrown types performed similarly. Densely sintered zirconia SCs were more frequently lost due to veneering ceramic fractures than metal-ceramic SCs (p<0.001), and had significantly more loss of retention (p<0.001). In total higher 5 year rates of framework fracture were reported for the all-ceramic SCs than for metal-ceramic SCs. Survival rates of most types of all-ceramic SCs were similar to those reported for metal-ceramic SCs, both in anterior and posterior regions. Weaker

  2. Aesthetic Rehabilitation of a Complicated Crown-Root Fracture of the Maxillary Incisor: Combination of Orthodontic and Implant Treatment

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    Érica Dorigatti de Avila

    2014-01-01

    Full Text Available The aim of this paper is to present a complex rehabilitation, of fractured tooth, with implants in anterior region considering the orthodontics extrusion to clinical success. At 7 years old, the patient fractured the maxillary left central incisor and the dentist did a crown with the fragment. Twenty years later, the patient was referred to a dental clinic for orthodontic treatment, with the chief complaint related to an accentuated deep bite, and a professional started an orthodontic treatment. After sixteen months of orthodontic treatment, tooth 21 fractured. The treatment plan included an orthodontic extrusion of tooth 21 and implant placement. This case has been followed up and the clinical and radiographic examinations show excellence esthetic results and satisfaction of patient. The forced extrusion can be a viable treatment option in the management of crown root fracture of an anterior tooth to gain bone in a vertical direction. This case emphasizes that to achieve the esthetic result a multidisciplinary approach is necessary.

  3. Femoral neuropathy due to retroperitoneal bleeding. A red herring in medicine complicates anticoagulant therapy and influences the Russian Communist Revolution (Crown Prince Alexis, Rasputin).

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    Willbanks, O L; Willbanks, S E

    1983-02-01

    Femoral neuropathy occurs when occult retroperitoneal bleeding impinges on the appropriate nerve roots. The syndrome involves the acute onset of groin and thigh pain with characteristic flexion and external rotation of the hip. It may mimic other conditions such as acute arterial occlusion. Thorough knowledge of the anatomy of the femoral nerve explains the clinical features and leads the clinician to suspect the occurrence of this syndrome. Three cases have been reviewed that exhibited this condition as a result of retroperitoneal bleeding, a complication of systemic heparin therapy. The hemophilia that afflicted Alexis, the Crown Prince of Russia and son of Tsar Nicholas and Tsarina Alexandra, resulted in this clinical syndrome. The consequences enabled the sinister starets, Gregory Rasputin, to become intimately involved with the royal family, influencing the response of the Tsar to the political events in Russia, thereby playing an important role in setting the stage for the 1917 Russian communist revolution.

  4. The Up-to-14-Year Survival and Complication Burden of 256 TiUnite Implants Supporting One-Piece Cast Abutment/Metal-Ceramic Implant-Supported Single Crowns.

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    Walton, Terry R

    To assess the estimated cumulative survival (ECS) and explore the technical and biologic complications of 256 TiUnite implants (Nobel Biocare) supporting one-piece cast abutment/metal-ceramic implant-supported single crowns (ISCs) in situ for up to 14 years. A prospective sequentially recruited cohort of 207 patients received 256 metal-ceramic ISCs on TiUnite implants between 2001 and 2014. All but 24 patients with 27 crowns were clinically evaluated between January 2014 and April 2015 in conjunction with or in addition to their tailored maintenance program. Radiographs were obtained, and any previously recorded treatments associated with the crowns were tabulated. The ECS and standard errors were calculated with the life table actuarial method and Greenwood's formula, respectively. The log rank test was applied to assess differences between anterior and posterior crowns. Complication incidence, severity, and economic burden, measured in time/cost accounting units (TAUs), were tallied and compared descriptively. Independent groups were compared with the Mann-Whitney U test and related groups with the Wilcoxon Signed Rank Test. The mean clinical service time of the crowns was 5.61 years (44 ≥ 10 years). The 14-year ECS was 95.95% ± 3.20% with no significant difference between anterior and posterior prostheses. Only seven implants lost marginal bone ≥ one thread from the time of crown insertion. There were 30 nonterminal complications (16 biologic, 14 mechanical). The associated economic burden was low (n = 35 TAUs). High gold-alloy one-piece cast abutment/metal-ceramic ISCs on TiUnite implants exhibited excellent longevity and few complications over 14 years.

  5. Clinical Results and Technical Complications of Posterior Implant-Supported Modified Monolithic Zirconia Single Crowns and Short-Span Fixed Dental Prostheses: A 2-Year Pilot Study.

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    Cheng, Chih-Wen; Chien, Chia-Hui; Chen, Chun-Jung; Papaspyridakos, Panos

    2018-02-01

    The purpose of this clinical trial was to investigate the clinical outcomes of implant-supported modified monolithic zirconia single crowns (SCs) and short-span fixed dental prostheses (FDPs) after a follow-up of 2 years. Twenty-seven patients in need of implant-supported SCs or 3-unit FDPs in the posterior maxilla or mandible were consecutively selected for this study. A total of 56 modified monolithic zirconia prostheses including 44 SCs (8 screw-retained, 36 cement-retained) and twelve 3-unit FDPs (5 screw-retained, 7 cement-retained) were included in this study. All patients were followed at 6 months, 12 months, 18 months, and 2 years after placement of the modified monolithic zirconia prostheses. During the follow-up period, all prostheses were evaluated with clinical and radiographic examinations. The following technical parameters were assessed: framework fracture, fracture of veneering porcelain, screw loosening, loss of retention because of prosthesis de-cementation and opposing tooth fracture. No implant was lost during the follow-up period, yielding a 2-year implant survival of 100%. One FDP failed because of framework fracture. The overall prosthesis survival rate was 98.2% after 2 years of clinical service. During the study, 5 complication events were observed in 3 SCs and one FDP, including one fracture of veneering porcelain and 2 screw loosenings in 3 SCs, and loss of retention and opposing tooth fracture in the same FDP. Therefore, the complication-free rate of prostheses was 91.1%. According to the results of this study, the modified monolithic zirconia design used in this study resulted in a favorable short-term outcome for posterior implant-supported SCs and 3-unit FDPs. © 2017 by the American College of Prosthodontists.

  6. Ecological Shifts of Supragingival Microbiota in Association with Pregnancy

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    Wenzhen Lin

    2018-02-01

    Full Text Available Pregnancy is a physiological process with pronounced hormonal fluctuations in females, and relatively little is known regarding how pregnancy influences the ecological shifts of supragingival microbiota. In this study, supragingival plaques and salivary hormones were collected from 11 pregnant women during pregnancy (P1, ≤14 weeks; P2, 20–25 weeks; P3, 33–37 weeks and the postpartum period (P4, 6 weeks after childbirth. Seven non-pregnant volunteers were sampled at the same time intervals. The microbial genetic repertoire was obtained by 16S rDNA sequencing. Our results indicated that the Shannon diversity in P3 was significantly higher than in the non-pregnant group. The principal coordinates analysis showed distinct clustering according to gestational status, and the partial least squares discriminant analysis identified 33 genera that may contribute to this difference. There were differentially distributed genera, among which Neisseria, Porphyromonas, and Treponema were over-represented in the pregnant group, while Streptococcus and Veillonella were more abundant in the non-pregnant group. In addition, 53 operational taxonomic units were observed to have positive correlations with sex hormones in a redundancy analysis, with Prevotella spp. and Treponema spp. being most abundant. The ecological events suggest that pregnancy has a role in shaping an at-risk-for-harm microbiota and provide a basis for etiological studies of pregnancy-associated oral dysbiosis.

  7. Supragingival plaque microbial analysis in reflection to caries experience

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    Mannaa Alaa

    2013-01-01

    Full Text Available Abstract Background Dental caries develops as a result of the metabolism of carbohydrates by cariogenic bacteria present in a complex biofilm. The present study aimed to examine if bacteria in pooled supragingival plaque samples quantified using a “checkerboard DNA-DNA hybridization” based panel of caries-related bacteria, could reflect the caries experience in a manner similar to saliva samples analysed using a chair-side method in a previous investigation. Methods A total of 86 mothers and their children aged 4–6 years and 12–16 years old participated. Caries experience (DMFT/dmft; Decayed, Missing and Filled Teeth for permanent and primary teeth was registered clinically and radiographically. Caries was recorded at the D3 level (caries into dentine. The D/d component was divided into three categories. A pooled supragingival plaque sample per participant was obtained from posterior approximal sites. Analyses of 15 bacterial species were performed using the checkerboard DNA-DNA hybridisation technique. Results No significant relationships were found between the bacterial scores and DMFT/dmft nor D/d groups. Conclusions Unlike the saliva samples and the chair-side method, interproximal pooled plaque samples analysed using the “checkerboard DNA-DNA hybridization technique” did not reveal any significant relations between the bacterial counts and the caries experience.

  8. A Conservative Bioadhesive Approach to the Reattachment of Complicated Crown Fractures in Permanent First Molars: A Case Report with a 2-Year Followup

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    Pragati Mirikar

    2012-01-01

    Full Text Available This paper presents a clinical report demonstrating combined restorative bioadhesive treatment and prosthetic rehabilitation of uncommon type of dental injury in an eighteen-year-old female involving crown fracture of all the permanent first molars and left upper premolars due to a bicycle riding accident. To restore the coronal fracture with invasion of biologic width, flap surgery with osteotomy and osteoplasty localized on the fractured teeth was performed, and the tooth remnant was reattached to the crown with a self-etch adhesive system. Frank pulp exposure was treated by self-etch dentin adhesive after surface disinfection prior to sealing of the wound site. At 2-year recall, the teeth continue to be aesthetically and functionally stable with a favourable pulpal and periapical environment.

  9. Compositional stability of a salivary bacterial population against supragingival microbiota shift following periodontal therapy.

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    Wataru Yamanaka

    Full Text Available Supragingival plaque is permanently in contact with saliva. However, the extent to which the microbiota contributes to the salivary bacterial population remains unclear. We compared the compositional shift in the salivary bacterial population with that in supragingival plaque following periodontal therapy. Samples were collected from 19 patients with periodontitis before and after periodontal therapy (mean sample collection interval, 25.8 ± 2.6 months, and their bacterial composition was investigated using barcoded pyrosequencing analysis of the 16S rRNA gene. Phylogenetic community analysis using the UniFrac distance metric revealed that the overall bacterial community composition of saliva is distinct from that of supragingival plaque, both pre- and post-therapy. Temporal variation following therapy in the salivary bacterial population was significantly smaller than in the plaque microbiota, and the post-therapy saliva sample was significantly more similar to that pre-therapy from the same individual than to those from other subjects. Following periodontal therapy, microbial richness and biodiversity were significantly decreased in the plaque microbiota, but not in the salivary bacterial population. The operational taxonomic units whose relative abundances changed significantly after therapy were not common to the two microbiotae. These results reveal the compositional stability of salivary bacterial populations against shifts in the supragingival microbiota, suggesting that the effect of the supragingival plaque microbiota on salivary bacterial population composition is limited.

  10. Medición de cambios cuantitativos de la microbiota subgingival posterior a la remoción de placa bacteriana supragingival Measurement of quantitative changes of the microbiota subgingival after to removal of bacterial plaque supragingival

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    C Godoy

    2010-04-01

    Full Text Available Uno de los campos de interés en el estudio de la microbiología periodontal para muchos investigadores ha sido identificar si es posible que los microorganismos responsables del origen y progresión de la enfermedad periodontal que habitan sobre el margen gingival (supragingival y bajo este (subgingival tengan una relación directa que permita mantener interacciones influyentes en el crecimiento y desarrollo de las diferentes especies bacterianas que habitan en los tejidos periodontales. Por lo tanto, al remover los microorganismos que se ubican supragingivalmente sería posible encontrar cambios en el medio subgingival al no existir un intercambio entre los ambientes aerobios (supragingival y anaerobios (subgingival una vez desorganizada la placa bacteriana supragingival. Para demostrar esta relación se seleccionaron 7 individuos con diagnóstico de periodontitis crónica moderada y severa a los cuales se les realizó un destartraje supragingival de boca completa para lograr desorganizar la placa bacteriana supragingival. A su vez se tomaron muestras microbiológicas de los sacos periodontales más profundos de cada cuadrante de estos individuos, siendo la primera muestra tomada previo al destartraje supragingival considerada como muestra basal (día 0, luego se tomaron a las 24 horas, a los 7 y 21 días de removida la placa bacteriana supragingival. De los resultados del presente estudio pudimos concluir que al desorganizar el biofilm supragingival se observa una disminución en la cantidad total de microorganismos subgingivales, así como también disminuye de manera considerable la proporción de Porphyoromona gingivalis presente en el medio subgingival. Lo cual permitiría establecer la existencia de una relación directa y dependiente entre los microorganismos que habitan el medio supragingival y subgingival.One of the fields of interest in the study of the microbiology periodontal for many investigators has been to identify if it is

  11. Supragingival biofilm control and systemic inflammation in patients with type 2 diabetes mellitus

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    Hilana Paula Carillo ARTESE

    2015-01-01

    Full Text Available The objective of this study was to evaluate the effect of strict supragingival biofilm control on serum inflammatory markers and on periodontal clinical parameters in type 2 diabetes mellitus (T2DM patients with chronic severe periodontitis. Twenty-four individuals with T2DM and periodontitis were randomly allocated to two treatment groups. The supragingival therapy group (ST, n = 12 received supragingival scaling, whereas the intensive therapy group (IT, n = 12 underwent supra- and subgingival scaling, as well as root planing. Patients from both groups received professional oral hygiene instructions every month. Data regarding visible plaque index (VPI, gingival bleeding index (GBI, bleeding on probing (BOP, probing pocket depth (PPD, clinical attachment level (CAL, serum levels of interleukin (IL-6, IL-17A, IL-8, tumor necrosis factor α (TNF-α, monocyte chemoattractant protein (MCP-1 enzyme-linked immunosorbent assay (ELISA, and glycated hemoglobin (HbA1c levels were obtained at baseline and at 6 months post-therapy. Both therapies resulted in the improvement of almost all clinical periodontal parameters (p 0.05, between the two periods. However, MCP-1 levels were significantly reduced in both the ST (p = 0.034 and the IT (p = 0.016 groups, whereas the serum IL-6 levels were significantly reduced only in the IT group (p = 0.001. Strict control of supragingival biofilm has a limited effect on systemic inflammatory markers, and a moderate effect on periodontal clinical parameters.

  12. Dinar-crown banknotes

    OpenAIRE

    Pantelić Svetlana

    2017-01-01

    Dinar-crown banknotes were: ½ dinars (i.e. 2 crowns), 1 dinar (i.e. 4 crowns), 5 dinars (i.e. 20 crowns), 10 dinars (i.e. 40 crowns), 20 dinars (i.e. 80 crowns), 100 dinars (i.e. 400 crowns), and 1000 dinars (i.e. 4000 crowns). The ½- and 1-dinar banknotes are assumed to have been issued in 1919, whereas the other five banknotes, according to one source, were released into circulation on 21.02.1920. Pursuant to the regulations, the replacement of the nostrified crown banknotes by the new crow...

  13. An Up-to-15-Year Comparison of the Survival and Complication Burden of Three-Unit Tooth-Supported Fixed Dental Prostheses and Implant-Supported Single Crowns.

    Science.gov (United States)

    Walton, Terry R

    2015-01-01

    To assess and compare the outcomes and economic complication burden of three-unit tooth-supported fixed dental prostheses (TFDPs) and implant-supported single crowns (ISCs) provided to a sequential cohort in a specialist prosthodontic practice over a 15-year period. Sequential patients requiring replacement of a single missing tooth between 1996 and 2010 with a metal-ceramic three-unit TFDP (n = 145 patients, n = 174 prostheses) or ISC (n = 174 patients, n = 220 prostheses) were included. Prostheses subjectively judged at insertion to have an unfavorable 10-year prognosis (17 TFDPs, 0 ISCs) were removed from statistical analyses. The estimated cumulative survival (ECS) was calculated with the life table actuarial method and standard errors calculated with the Greenwood formula. Differences in outcomes between all prostheses and those replacing only anterior or only posterior teeth were assessed with the log rank test. Complication incidence, severity, and economic burden, measured in time/cost accounting units (TAUs), were tallied and compared descriptively. The 15-year ECS did not differ for 112 TFDPs (92.75% ± 3.28%) and 81 ISCs (95.95% ± 2.92%) replacing posterior teeth. However, the 15-year ECS was significantly greater for 139 ISCs (93.33% ± 6.44%) than for 45 TFDPs (82.82% ± 6.50%) replacing anterior teeth. The economic burden of nonterminal complications for both prostheses was low (mean = 0.3 and 0.2 TAUs per prosthesis for TFDPs and ISCs, respectively). This equated to 3 TAUs/100 years in clinical service and 4 TAUs/100 years in clinical service for the TFDPs and ISCs, respectively. The survival of three-unit TFDPs and ISCs over 15 years was not statistically different when replacing posterior teeth, but ISCs survived significantly better when replacing anterior teeth. The complication rates of the TFDPs and ISCs were similar, but the economic burden for the TFDPs was greater.

  14. Impacts of supragingival and subgingival periodontal treatments on oral health-related quality of life.

    Science.gov (United States)

    Mendez, M; Melchiors Angst, P D; Stadler, A F; Oppermann, R V; Gomes, S

    2017-05-01

    The aim of this study was to evaluate the impact of distinct phases of a non-surgical periodontal treatment protocol on oral health-related quality of life (OHRQoL). Fifty-five participants (51.4 ± 9.4 years), diagnosed with both gingivitis and moderate-to-severe periodontitis, were included. Periodontal and OHRQoL (OHIP-14) data were collected before (Day 0) and after the supragingival (Day 30) and subgingival (Day 90) treatments. A linear mixed model was used. OHIP-14 scores, effect size, and ceiling and floor effects were calculated. The total OHIP-14 score was significantly higher at Day 0 (17.3 ± 10.5) compared to Day 30 (9.7 ± 8.3) and Day 90 (9.5 ± 7.4). Scores of all domains decreased significantly after the supragingival treatment. This response was maintained after the subgingival therapy, except in the physical pain and physical disability domains. Clinical variables were not associated with the change in OHIP scores. The effect size was 0.72 at Day 30 and 0.74 at Day 90. No ceiling and floor effect were observed. Perceptions on OHRQoL improved along periodontal therapy, particularly after the supragingival treatment, suggesting that this intervention might be considered important to reduce the negative impacts in oral health-related quality of life. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. Response of molars and non-molars to a strict supragingival control in periodontal patients

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    Patrícia Daniela Melchiors Angst

    2013-02-01

    Full Text Available The posterior position in the arches is one of the factors that underlies the poor prognosis of molar teeth (M. It is speculated that M do not benefit from the oral hygiene routine as well as non-molars (NM do. This study evaluated the response of M and NM to supragingival control during a 6-month period in 25 smokers (S and 25 never-smokers (NS with moderate-to-severe periodontitis. One calibrated examiner assessed visible plaque (VPI and gingival bleeding (GBI indexes, periodontal probing depth (PPD, bleeding on probing (BOP, and clinical attachment loss (CAL at days 0 (baseline, 30 and 180. At baseline, M showed significantly higher mean values of VPI (p = 0.017 and PPD (p < 0.001 compared with NM; CAL was also greater in M (p < 0.001 and was affected by smoking (p = 0.007. The reductions obtained for periodontal indicators at day 180 showed similar responses between M and NM. For CAL, M (NS 0.57 ± 0.50; S 0.67 ± 0.64 and NM (NS 0.38 ± 0.23; S 0.50 ± 0.33 reached an almost significant difference (p = 0.05. Smoking did not influence the response to treatment. Multilevel analysis revealed that, only for PDD reductions, the interaction between sites, teeth and patient was significant (p < 0.001. It was concluded that M benefit from an adequate regimen of supragingival biofilm control; therefore, supragingival condition should be considered in the prognosis of molar teeth.

  16. Saliva, supragingival biofilm and root canals can harbor gene associated with resistance to lactamic agents

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    Ludmila Coutinho MORAES

    2015-01-01

    Full Text Available This study aimed to determine the presence of Prevotella strains and genes associated with resistance to lactamics in different oral niches from patients with/without primary endodontic infections. Saliva (S and supragingival biofilm (SB were collected from three patient groups: Group I – no endodontic infection (n = 15; Group II – acute endodontic infection (n = 12; and Group III – chronic endodontic infection (n = 15. Root canal (RC samples were collected from Groups II and III. The presence of P. intermedia, P nigrescens, P. tannerae and cfxA/cfxA2 gene was assessed by PCR. The cfxA/cfxA2 gene was not detected in all environments within the same patient. The cfxA/cfxA2 gene was present in 23.81% of S samples, 28.57% of SB samples, and 7.41% of RC samples. Prevotella species were detected in 53.97%, 47.62% and 34.56% of the S, SB, and RC samples, respectively. P. intermedia had a high frequency in saliva samples from Group 3. Saliva samples from Group 1 had higher detection rates of P. nigrescens than did Groups 2 and 3. Patients without endodontic disease had high frequencies of P. nigrescens in the SB samples. The presence or absence of spontaneous symptoms was not related to the detection rates for resistance genes in the RC samples. Saliva, supragingival biofilm and root canals can harbor resistant bacteria. The presence of symptomatology did not increase the presence of the cfxA/cfxA2 gene in the supragingival biofilm and inside root canals.

  17. Distinguishing the Signals of Gingivitis and Periodontitis in Supragingival Plaque: a Cross-Sectional Cohort Study in Malawi

    Science.gov (United States)

    Harjunmaa, Ulla; Doyle, Ronan; Mulewa, Simeon; Charlie, Davie; Maleta, Ken; Callard, Robin; Walker, A. Sarah; Balloux, Francois; Ashorn, Per; Klein, Nigel

    2016-01-01

    ABSTRACT Periodontal disease ranges from gingival inflammation (gingivitis) to the inflammation and loss of tooth-supporting tissues (periodontitis). Previous research has focused mainly on subgingival plaque, but supragingival plaque composition is also known to be associated with disease. Quantitative modeling of bacterial abundances across the natural range of periodontal severities can distinguish which features of disease are associated with particular changes in composition. We assessed a cross-sectional cohort of 962 Malawian women for periodontal disease and used 16S rRNA gene amplicon sequencing (V5 to V7 region) to characterize the bacterial compositions of supragingival plaque samples. Associations between bacterial relative abundances and gingivitis/periodontitis were investigated by using negative binomial models, adjusting for epidemiological factors. We also examined bacterial cooccurrence networks to assess community structure. The main differences in supragingival plaque compositions were associated more with gingivitis than periodontitis, including higher bacterial diversity and a greater abundance of particular species. However, even after controlling for gingivitis, the presence of subgingival periodontitis was associated with an altered supragingival plaque. A small number of species were associated with periodontitis but not gingivitis, including members of Prevotella, Treponema, and Selenomonas, supporting a more complex disease model than a linear progression following gingivitis. Cooccurrence networks of periodontitis-associated taxa clustered according to periodontitis across all gingivitis severities. Species including Filifactor alocis and Fusobacterium nucleatum were central to this network, which supports their role in the coaggregation of periodontal biofilms during disease progression. Our findings confirm that periodontitis cannot be considered simply an advanced stage of gingivitis even when only considering supragingival plaque

  18. Distinguishing the Signals of Gingivitis and Periodontitis in Supragingival Plaque: a Cross-Sectional Cohort Study in Malawi.

    Science.gov (United States)

    Shaw, Liam; Harjunmaa, Ulla; Doyle, Ronan; Mulewa, Simeon; Charlie, Davie; Maleta, Ken; Callard, Robin; Walker, A Sarah; Balloux, Francois; Ashorn, Per; Klein, Nigel

    2016-10-01

    Periodontal disease ranges from gingival inflammation (gingivitis) to the inflammation and loss of tooth-supporting tissues (periodontitis). Previous research has focused mainly on subgingival plaque, but supragingival plaque composition is also known to be associated with disease. Quantitative modeling of bacterial abundances across the natural range of periodontal severities can distinguish which features of disease are associated with particular changes in composition. We assessed a cross-sectional cohort of 962 Malawian women for periodontal disease and used 16S rRNA gene amplicon sequencing (V5 to V7 region) to characterize the bacterial compositions of supragingival plaque samples. Associations between bacterial relative abundances and gingivitis/periodontitis were investigated by using negative binomial models, adjusting for epidemiological factors. We also examined bacterial cooccurrence networks to assess community structure. The main differences in supragingival plaque compositions were associated more with gingivitis than periodontitis, including higher bacterial diversity and a greater abundance of particular species. However, even after controlling for gingivitis, the presence of subgingival periodontitis was associated with an altered supragingival plaque. A small number of species were associated with periodontitis but not gingivitis, including members of Prevotella, Treponema, and Selenomonas, supporting a more complex disease model than a linear progression following gingivitis. Cooccurrence networks of periodontitis-associated taxa clustered according to periodontitis across all gingivitis severities. Species including Filifactor alocis and Fusobacterium nucleatum were central to this network, which supports their role in the coaggregation of periodontal biofilms during disease progression. Our findings confirm that periodontitis cannot be considered simply an advanced stage of gingivitis even when only considering supragingival plaque

  19. Bactericidal effects of hematoporphyrin monomethyl ether-mediated photosensitization against pathogenic communities from supragingival plaque.

    Science.gov (United States)

    Sun, Yi; Xing, Defeng; Shen, Lanhua; Sun, Miao; Fang, Ming; Bi, Liangjia; Sui, Yanjiao; Zhang, Zhiguo; Cao, Wenwu

    2013-06-01

    Photodynamic antimicrobial chemotherapy (PACT) is proposed as a potential candidate to inactivate pathogens in localized infections due to the rapid evolution of bacterial resistance. The treatment modality utilizes nontoxic agents called photosensitizers and harmless visible light to generate reactive oxygen species which result in microbial cells' killing. Hematoporphyrin monomethyl ether (HMME) as a novel and affordable photosensitizer has been used in treating various clinical diseases for years, but few applications in infection. In this report, we studied the bactericidal effects of the HMME-mediated photodynamic reaction on the pathogenic microbes in supragingival plaque which can lead to many oral infectious diseases such as caries, gingivitis, and so on. Our findings demonstrated that HMME promoted an effective action in bacterial reduction with the application of laser energy. Moreover, the antimicrobial activities were dramatically enhanced as the HMME concentration and exposure time were increased, but reached a plateau when matched the appropriate agent concentration and illumination. It was found that the survival fraction of microorganisms is exponentially dependent on the product of HMME concentration and irradiation time. These promising results suggest the HMME may be an excellently cost-effective photosensitizing agent for mediating PACT in the treatment of supragingival plaque-related diseases. An optimized HMME concentration and irradiation time has been found to achieve the best results under our experimental conditions. The high HMME concentration matching short curative time, or vice versa, can achieve the similar therapeutic effect, which may provide more flexible treatment plans according to specific conditions.

  20. Efficacy of dental floss impregnated with chlorhexidine on reduction of supragingival biofilm: a randomized controlled trial.

    Science.gov (United States)

    Muniz, F W M G; Sena, K S; de Oliveira, C C; Veríssimo, D M; Carvalho, R S; Martins, R S

    2015-05-01

    The use of a toothbrush has a limited ability to control the dental biofilm in interproximal areas. Therefore, specialized devices, such as dental floss, may be useful for these specific areas. This study aimed to investigate the efficacy of dental floss impregnated with 5% chlorhexidine gluconate on the reduction of the supragingival biofilm. This research was parallel, single-blind, controlled and randomized, and contained a sample of thirty dental students from the Faculty of Pharmacy, Dentistry and Nursing of the Federal University of Ceará, Brazil, who were divided equally into three groups. The negative control group (NC) did not utilize any kind of interproximal cleaning; the positive control group (PC) used waxed floss without impregnation twice a day; and the test group (T) used the same dental floss, which was impregnated with 5% chlorhexidine gluconate, twice a day. For all groups, this study lasted for 15 days. The presence of a biofilm was evaluated on four surfaces (mesiobuccal, distobuccal, mesiolingual and distolingual) by the Quigley-Hein Index, resulting in four scores for each tooth. Group T had the lowest plaque scores, showing a significant difference compared to group NC (P dental floss impregnated with 5% chlorhexidine gluconate resulted in additional reductions in the supragingival biofilm relative to the results achieved with conventional waxed floss on the anterior teeth of a well-motivated and well-instructed population. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Influence of supragingival biofilm control and smoking habit on Interleukin-1β concentration

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    Sabrina Carvalho GOMES

    2015-01-01

    Full Text Available This investigation compared gingival crevicular fluid (GCF interleukin-1β (IL-1β concentrations in periodontitis patients subjected to a strict supragingival biofilm control (Supra for 6 months. Never-smokers (23 and smokers (n = 20; 19.6 ± 11.8 cigarettes/day moderate-to-severe chronic periodontitis patients underwent a 6 months period of supragingival control with weekly recall visits. Periodontal probing depth (PPD, bleeding on probing (BOP and GCF samples (from different PPD category sites: 3-5 mm and 6–10 mm were obtained at the baseline, 30, and 180 days. IL-1β was assessed by enzyme-linked immunosorbent assay. Generalized estimating equations were used to fit prediction models of IL-1β changes, considering the dependence between the examinations, and using only data from experimental sites. Overall IL-1β concentrations decreased from 3.2 pg/µL to 1.9 pg/µL. Higher baseline IL-1β concentrations were associated with higher baseline PPD values in both groups. There were no differences in IL-1β concentrations between never-smokers and smokers over time for any PPD category. Higher baseline PPD values and the presence of BOP on day 180 were significantly associated with higher IL-1β concentrations. A strict Supra regimen reduced IL-1β concentrations over time in periodontitis patients. The benefits observed for smokers underline the importance of oral hygiene measures, even considering the presence of this important risk factor.

  2. Dinar-crown banknotes

    Directory of Open Access Journals (Sweden)

    Pantelić Svetlana

    2017-01-01

    Full Text Available Dinar-crown banknotes were: ½ dinars (i.e. 2 crowns, 1 dinar (i.e. 4 crowns, 5 dinars (i.e. 20 crowns, 10 dinars (i.e. 40 crowns, 20 dinars (i.e. 80 crowns, 100 dinars (i.e. 400 crowns, and 1000 dinars (i.e. 4000 crowns. The ½- and 1-dinar banknotes are assumed to have been issued in 1919, whereas the other five banknotes, according to one source, were released into circulation on 21.02.1920. Pursuant to the regulations, the replacement of the nostrified crown banknotes by the new crown- dinar banknotes started on 3 February 1920 in Serbia and Montenegro and on 16 February 1920 in other parts of the country. All seven denominations of the dinar-crown banknotes were being withdrawn from circulation throughout a lengthy period of time from 21 February 1921 until May 1934. The first to be withdrawn were the 20-dinar banknotes, from 1 February to 30 April 1921, then the 5-dinar banknotes, from 20 July to 20 November 1922, and the 10-dinar banknotes, from 10 February to 10 June 1924. The 100-dinar (400-crown and 1000-dinar (4000-crown banknotes remained in circulation the longest. The withdrawal of the 100- and 1000-dinar banknotes started in 1929 and lasted until 25 May 1934. The 1924 rulebook on minting coins of ½, 1 and 2 dinars precisely defines their withdrawal from circulation and replacement by minted coins within one year after the last batch of minted coins gets released into circulation. However, in 1927 the decree of the Minister of Finance prescribed that the remaining paper banknotes be withdrawn from circulation on 30 September 1927 by being replaced by the metal coins of the same denominations.

  3. The relationship of Prevotella intermedia, Prevotella nigrescens and Prevotella melaninogenica in the supragingival plaque of children, caries and oral malodor.

    Science.gov (United States)

    Tanaka, Shoji; Yoshida, Mikako; Murakami, Yukio; Ogiwara, Takako; Shoji, Masao; Kobayashi, Satoko; Watanabe, Sigeru; Machino, Mamoru; Fujisawa, Seiichiro

    2008-01-01

    A relationship between the distribution of periodontal bacteria species and malodor in children has not been sufficiently investigated. The present study was undertaken to determine the presence of 3 periodontopathic bacteria (Prevotella spp. P. intermedia, P. nigrescens, P. melaninogenica) in the supragingival plaques of 3 to 16-year-old children with different oral health conditions and oral malodor. The number of decayed and filled primary teeth (df) and Decayed, Missing and Filled permanent teeth (DMF), Papillary Marginal and Attached gingivitis (PMA) index, Oral Hygiene Index (OHI), and oral malodor of each subject were determined prior to the collection of supragingival plaques. Three periodontopathic bacteria (P. intermedia, P. nigrescens, P. melaninogenica) in supragingival plaques were detected by using an immunoslot blot assay with monoclonal antibodies specific for each microorganism. The frequencies of periodontopathic bacteria in children with and without caries were not significantly different from each other. Positivity for P. intermedia, but not for P. nigrescens or P. melaninogenica was correlated with oral malodor. Oral malodor was also correlated with the debris index, a component of OHI. The group with the higher OHI showed a higher prevalence of periodontopathic bacteria. For the 3 periodontopathic bacteria in the subjects tested, plaques positive for any of them were not age related. However the frequencies of all 3 periodontopathic bacteria were the highest in the 3-6-year olds. The supragingival plaques in children can harbor 3 species of periodontopathic bacteria, P. intermedia, P. nigrescens, and P. melaninogenica.

  4. The effect of supragingival glycine air polishing on periodontitis during maintenance therapy: a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Hongye Lu

    2018-02-01

    Full Text Available Background Glycine air polishing has been proved to be safe, comfortable and time-saving. Whether it could substitute ultrasonic scaling to remove dental plaque biofilm during periodontal maintenance remains unclear. The purposes of this study were to evaluate the effect of supragingival glycine air polishing (SGAP on the subgingival periodontal pathogens during maintenance therapy and to check the association of periodontal pathogens and clinical parameters. Methods Twenty-three chronic periodontitis patients during their maintenance therapy were enrolled in the 12-week study. According to randomized split-mouth design, the test side was treated with SGAP (65 μm, while the control side was treated with supragingival ultrasonic scaling and polishing (SUSP with rubber cup. Clinical examination including plaque index (PLI, probing depth (PD, bleeding index (BI were performed at baseline and 12 weeks post-treatment. Sampling of the subgingival plaque at each investigational site (mesiobuccal site of the mandibular first molar was performed at baseline and 2, 4, 8, 12 weeks after maintenance treatment. Four periodontal pathogens including Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola and Fusobacterium nucleatum were detected by 16S rDNA polymerase chain reaction. Results Clinical status generally improved after treatment in both groups. PLI in both groups, PD in SGAP group and bleeding on probing (% in SUSP group significantly decreased after treatment (p < 0.05. There was no significant difference of clinical parameters between two groups before and after treatment. The detection rates of P. gingivalis, T. denticola in both groups, T. forsythia in SUSP group and F. nucleatum in SGAP group decreased after maintenance treatment in both groups, although no significant difference was found, and it rebound to baseline level at 12 weeks after maintenance treatment. There was no significant difference between SGAP group and SUSP

  5. Microbial Profile of Supragingival and Subgingival Plaque of Patients With Glycogen Storage Disease

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    Chealsea E. Garcia DDS, MS

    2016-12-01

    Full Text Available Patients with glycogen storage disease (GSD are either orally fed (ORF or gastronomy-tube fed (GTF with cornstarch to maintain normal glucose levels. It is not known whether the use of cornstarch affects the microbiological oral profile of patients with GSD. Thus, the purpose of this study was to compare supragingival and subgingival plaque samples collected from 53 participants with GSD (2-56 years—29 ORF and 24 GTF. The 16S sequence bacterial profiles of plaque DNA were obtained and a total of 768 probes were detected across the plaque groups. Orally fed patients showed higher means of cariogenic species and periodontal health-associated species, whereas GTF patients showed higher means of periopathogenic species ( P < .05. Orally fed patients exhibited high levels of caries pathogens and lower levels of periodontal pathogens possibly due to the acidic environment created by their cornstarch diet, when compared to GTF patients.

  6. Comparison of modified Bass technique with normal toothbrushing practices for efficacy in supragingival plaque removal.

    Science.gov (United States)

    Poyato-Ferrera, M; Segura-Egea, J J; Bullón-Fernández, P

    2003-05-01

    This study was designed to compare the efficacy in supragingival plaque removal of normal toothbrushing practices and a particular toothbrushing technique, the modified Bass method. The research consisted of two identical experiments with two toothbrushing methods: the normal toothbrushing practices and the modified Bass technique. Forty-six secondary, non-dental students (10 males and 36 females) with ages ranging from 18 to 30 years were selected. Dental plaque was assessed according to the Turesky modification of Quigley-Hein Index. Subjects were requested not to brush their teeth 48 h prior to the baseline record of plaque index. Participants were instructed to brush twice daily during 3 min for the duration of the 3-week trial using their usual toothpaste. Plaque index was recorded at 2, 7 and 21 days. The modified Bass (Mod-Bass) technique was significantly (P 0.05), but did so with the modified Bass technique (P important improvement in the oral hygiene of the patients.

  7. Crowns and Crypts

    Indian Academy of Sciences (India)

    The product was isolated to be dibenzo-. 18-Crown-6. Many other crowns were ... fashion with their lone pairs pointing inward towards the metal atom. The bonding M-O is largely ... Macrocycles, though extremely effective as polydentate ligands, are not essential for the production of stable alkali complexes; additional ...

  8. Supragingival Microbial Profiles of Permanent and Deciduous Teeth in Children with Mixed Dentition.

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    Weihua Shi

    Full Text Available The present study was designed to investigate the microbial profiles of teeth in different locations in mixed-dentition-stage children, and to compare the microbiomes of permanent and deciduous teeth in the same healthy oral cavity.Supragingival plaque samples of teeth in various locations-the first permanent molars, deciduous molars, deciduous canines and incisors and permanent incisors-were collected from 20 healthy mixed-dentition-stage children with 10-12 permanent teeth erupted. Plaque DNA was extracted, and the V3-V4 hypervariable region of the bacterial 16S rRNA gene was amplified and subjected to sequencing.On average, 18,051 high-quality sequences per sample were generated. Permanent tooth sites tended to host more diverse bacterial communities than those of deciduous tooth sites. A total of 12 phyla, 21 classes, 38 orders, 66 families, 74 genera were detected ultimately. Five predominant phyla (Proteobacteria, Firmicutes, Bacteroidetes, Fusobacteria and Actinobacteria were highly variable among sites. Of 26 genera with a mean relative abundance of >0.1%, 16 showed significant differences in relative abundance among the groups. More than 20% of the total operational taxonomical units were detected only in permanent or deciduous teeth. The variation in the microbial community composition was due mainly to permanent teeth being enriched in Actinomyces and deciduous teeth in Treponema. The core microbiome of supragingival plaque in mixed dentition comprised 19 genera with complex correlationships.Our results suggest differences in microbial diversity and composition between permanent and deciduous teeth sites in mixed dentition. Moreover, the core microbiome of these sites was determined. These findings enhance our understanding of the development of the native oral microbiota with age.

  9. Dental calculus: recent insights into occurrence, formation, prevention, removal and oral health effects of supragingival and subgingival deposits.

    Science.gov (United States)

    White, D J

    1997-10-01

    Dental calculus, both supra- and subgingival occurs in the majority of adults worldwide. Dental calculus is calcified dental plaque, composed primarily of calcium phosphate mineral salts deposited between and within remnants of formerly viable microorganisms. A viable dental plaque covers mineralized calculus deposits. Levels of calculus and location of formation are population specific and are affected by oral hygiene habits, access to professional care, diet, age, ethnic origin, time since last dental cleaning, systemic disease and the use of prescription medications. In populations that practice regular oral hygiene and with access to regular professional care, supragingival dental calculus formation is restricted to tooth surfaces adjacent to the salivary ducts. Levels of supragingival calculus in these populations is minor and the calculus has little if any impact on oral-health. Subgingival calculus formation in these populations occurs coincident with periodontal disease (although the calculus itself appears to have little impact on attachment loss), the latter being correlated with dental plaque. In populations that do not practice regular hygiene and that do not have access to professional care, supragingival calculus occurs throughout the dentition and the extent of calculus formation can be extreme. In these populations, supragingival calculus is associated with the promotion of gingival recession. Subgingival calculus, in "low hygiene" populations, is extensive and is directly correlated with enhanced periodontal attachment loss. Despite extensive research, a complete understanding of the etiologic significance of subgingival calculus to periodontal disease remains elusive, due to inability to clearly differentiate effects of calculus versus "plaque on calculus". As a result, we are not entirely sure whether subgingival calculus is the cause or result of periodontal inflammation. Research suggests that subgingival calculus, at a minimum, may expand the

  10. Crown Fire Potential

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — Crown fire potential was modeled using FlamMap, an interagency fire behavior mapping and analysis program that computes potential fire behavior characteristics. The...

  11. Effect of supragingival oral irrigation as an adjunct to toothbrushing on plaque accumulation in chronic generalized gingivitis patients

    OpenAIRE

    Manish Khatri; Aamir Shams Malik; Mansi Bansal; Komal Puri; Geeti Gupta; Ashish Kumar

    2017-01-01

    Aim: The aim of this study was to evaluate the efficacy of supragingival oral irrigation either with water or different concentrations of chlorhexidine (CHX) digluconate as an adjunct to toothbrushing on plaque accumulation in chronic generalized gingivitis patients. Materials and Methods: Fifty patients were randomly allocated into five groups. Group 1: toothbrushing alone, Group 2: toothbrushing with mouthwash, Group 3: toothbrushing with water irrigation, Group 4: toothbrushing with 0.0075...

  12. Caries-related factors and bacterial composition of supragingival plaques in caries free and caries active Algerian adults

    OpenAIRE

    Amina Hoceini; Nihel Klouche Khelil; Ilhem Ben-Yelles; Amine Mesli; Sara Ziouani; Lotfi Ghellai; Nadia Aissaoui; Fatima Nas; Mounia Arab

    2016-01-01

    Objective: To compare oral hygiene practices, education and social background, food intake and oral malodor of Algerian adults suffering from dental caries with normal controls, and to determine and compare the bacterial composition of the supragingival plaques from the above-mentioned groups. Methods: Participants completed a questionnaire and were clinically examined for dental caries using decayed, missing and filled teeth index according to the criteria laid down by the World Health Or...

  13. Adhesively luted, metal-free composite crowns after five years.

    Science.gov (United States)

    Lehmann, Franziska; Spiegl, Katrin; Eickemeyer, Grit; Rammelsberg, Peter

    2009-12-01

    The effect of location and preparation design of abutment teeth and of preparation design on the survival and complication rate of metal-free, adhesively luted composite crowns (Artglass, Heraeus Kulzer) and their clinical performance was investigated in this controlled, randomized, prospective clinical study. After randomization, 114 single crowns (68 posterior, 46 anterior) were prepared either with a 0.5 mm chamfer finishing line or with a 0.5 mm shoulder combined with occlusal reduction of at least 1.5 mm. Buildups were made with a composite material, using the corresponding dentin adhesive. Crowns were manufactured on stone dies and intraorally adhesively luted with resin cement. Follow-up examinations were conducted after 1 month and 1, 2, 3, and 5 years. Documentation included failures and complications, occlusal contacts, plaque accumulation and patients' rating of esthetics and functionality. After 5 years, data for 83 single crowns had been obtained. Within an observation period of 5 years, 18 complications occurred, including 13 major failures which resulted in replacement of the crowns, and 5 minor complications which could be repaired. All loosened crowns (n = 2) were successfully re-cemented. The Cox Regression did not reveal any effect of location or preparation design on complication rate. Calculation of the Kaplan-Meier survival curve on the basis of major failures indicated a probability of survival of 96% after 3 years and 88.5% after 5 years. Four Artglass crowns had no contact in static occlusion after 5 years and plaque accumulation was significantly higher than for control teeth. esthetic and functional evaluation by patients revealed that acceptance was high. Metal-free composite crowns may be recommended for long-term temporary use. However, the complication rate and the increased plaque accumulation restrict the indication for permanent restorations.

  14. Effect of supragingival oral irrigation as an adjunct to toothbrushing on plaque accumulation in chronic generalized gingivitis patients.

    Science.gov (United States)

    Khatri, Manish; Malik, Aamir Shams; Bansal, Mansi; Puri, Komal; Gupta, Geeti; Kumar, Ashish

    2017-01-01

    The aim of this study was to evaluate the efficacy of supragingival oral irrigation either with water or different concentrations of chlorhexidine (CHX) digluconate as an adjunct to toothbrushing on plaque accumulation in chronic generalized gingivitis patients. Fifty patients were randomly allocated into five groups. Group 1: toothbrushing alone, Group 2: toothbrushing with mouthwash, Group 3: toothbrushing with water irrigation, Group 4: toothbrushing with 0.0075% CHX digluconate (36 mg) supragingival irrigation, and Group 5: toothbrushing with 0.02% CHX digluconate (96 mg) supragingival irrigation. The collected data were subjected to statistical analysis. Descriptive data were obtained for all outcome variables and reported as mean ± standard deviation. The Student's t-test, Chi-square test, and one-way analysis of variance (ANOVA) were applied for the statistical evaluation of means and comparisons of proportions, and post hoc Bonferroni test was used for multiple comparisons after the application of the ANOVA test for comparison within the groups. When intergroup difference of the mean differences was compared for individuals using toothbrushing along with 0.0075% CHX digluconate irrigation and those using toothbrushing along with 0.02% CHX digluconate irrigation from BL-14, BL-28, and between 14 and 28 days, it was found to be statistically nonsignificant. In our study, the CHX digluconate concentration for mouthwash and oral irrigation in addition with toothbrushing was found to be same, i.e., <50 mg for improving the gingival health by reducing gingival inflammation.

  15. Effects of hydrophilicity and microtopography of titanium implant surfaces on initial supragingival plaque biofilm formation. A pilot study.

    Science.gov (United States)

    Schwarz, F; Sculean, A; Wieland, M; Horn, N; Nuesry, E; Bube, C; Becker, J

    2007-12-01

    The aim of the present pilot study is to investigate the effects of hydrophilicity and microtopography of titanium implant surfaces on initial supragingival plaque biofilm formation. Test specimens were manufactured from commercially pure grade 2 titanium according to one of the following procedures: polished (P), acid-etched (A), chemically modified (mod) A (modA), sand-blasted large grit and A (SLA), and modSLA. Intraoral splints were used to collect an in vivo supragingival plaque biofilm in each group at 12, 24, and 48 h. Stained plaque biofilm (PB) areas (%) were morphometrically assessed. All groups exhibited significant increases of mean PB areas over time (p P > A =modA (p modSLA = P > A = modA (p A = modA (p < 0.001; respectively). Within the limits of a pilot study, it could be concluded that hydrophilicity had no apparent effect, while microtopography had a highly uneven and unpredictable influence on supragingival plaque biofilm formation.

  16. Extensive Description and Comparison of Human Supra-Gingival Microbiome in Root Caries and Health

    Science.gov (United States)

    Chen, Lin; Qin, Bingcai; Du, Minquan; Zhong, Huanzi; Xu, Qingan; Li, Yuhong; Zhang, Ping; Fan, Mingwen

    2015-01-01

    Knowledge of the polymicrobial etiology of root caries is limited. To conduct a comprehensive research study on root caries, we utilized 454-pyrosequencing of 16S rRNA gene libraries and quantitative PCR to compare supra-gingival bacterial communities from healthy sites and carious sites of 21 patients with root caries (Patient-controls and Patient-cases) and the sites of 21 healthy individuals (Healthy-controls) from two nursing homes. Healthy-controls and Patient-cases showed no significant differences in terms of biomass, species richness, and species diversity. However, as for beta diversity based on either community membership metric (unweighted UniFrac) or community structure metric (weighted UniFrac), Healthy-controls and Patient-cases were clearly distinguished from each other, appearing more variable in the community membership and structure in root caries microbiome but relatively conserved in the health microbiome. The Patient-controls group was at an intermediate stage between Healthy-controls and Patient-cases, but was more inclined to the former. Demonstrated in both relative abundance and prevalence of species in health and root caries, Propionibacterium acidifaciens, Streptococcus mutans, Olsenella profusa, Prevotella multisaccharivorax, and Lactobacillus crispatus were found to be most associated with root caries, whereas Delftia acidovorans, Bacteroidetes[G-2] sp., Lachnospiraceae[G-3] sp., and Prevotella intermedia are most associated with health. Our study provides a basis for further elucidating the microbial etiology of root caries in the elderly. PMID:25658087

  17. Removal of supragingival plaque in an intraoral model by use of the Sonicare toothbrush.

    Science.gov (United States)

    Stanford, C M; Srikantha, R; Kirchner, H L; Wu, C D

    2000-10-01

    This study was performed to evaluate plaque removal efficacy of a mechanical toothbrush in a controlled in vivo trial. The study used enamel sections, obtained from extracted human teeth, to evaluate the efficacy of supragingival plaque removal by a mechanical powered toothbrush in various modes of use. Enamel sections were positioned in milled depressions on metal extensions of a maxillary partial denture that bilaterally extended along the buccal corridors. Four sections were used per side, positioned zero, 2 or 3mm from the surface of the metal extension. The prosthesis was worn for 16 hours, whereupon four enamel sections (two per side) were removed. Intra-oral brushing was then performed for 5 or 15 seconds on the remaining four sections. The total of adherent bacteria was then assayed from all enamel sections. Ten to twenty trials were performed (n=4 pairs/trial) for each set of variables. When the electric toothbrush was used as a manual brush ('off'), it was equivalent in plaque removal to a conventional toothbrush (Oral-B 35; P = 0.49). However, when the powered brush was in its active mode ('on'), it removed more bacteria (P < 0.0001); this efficacy was observed even when the bristle tips were at a distance from the plaque surface.

  18. Extensive description and comparison of human supra-gingival microbiome in root caries and health.

    Directory of Open Access Journals (Sweden)

    Lin Chen

    Full Text Available Knowledge of the polymicrobial etiology of root caries is limited. To conduct a comprehensive research study on root caries, we utilized 454-pyrosequencing of 16S rRNA gene libraries and quantitative PCR to compare supra-gingival bacterial communities from healthy sites and carious sites of 21 patients with root caries (Patient-controls and Patient-cases and the sites of 21 healthy individuals (Healthy-controls from two nursing homes. Healthy-controls and Patient-cases showed no significant differences in terms of biomass, species richness, and species diversity. However, as for beta diversity based on either community membership metric (unweighted UniFrac or community structure metric (weighted UniFrac, Healthy-controls and Patient-cases were clearly distinguished from each other, appearing more variable in the community membership and structure in root caries microbiome but relatively conserved in the health microbiome. The Patient-controls group was at an intermediate stage between Healthy-controls and Patient-cases, but was more inclined to the former. Demonstrated in both relative abundance and prevalence of species in health and root caries, Propionibacterium acidifaciens, Streptococcus mutans, Olsenella profusa, Prevotella multisaccharivorax, and Lactobacillus crispatus were found to be most associated with root caries, whereas Delftia acidovorans, Bacteroidetes[G-2] sp., Lachnospiraceae[G-3] sp., and Prevotella intermedia are most associated with health. Our study provides a basis for further elucidating the microbial etiology of root caries in the elderly.

  19. Short-term consumption of probiotic lactobacilli has no effect on acid production of supragingival plaque

    DEFF Research Database (Denmark)

    Marttinen, Aino; Haukioja, Anna; Karjalainen, Sára

    2011-01-01

    . reuteri SD2112 and PTA 5289 for 2 weeks. At baseline and at the end of each tablet period, all available supragingival plaque was collected. Lactic acid production was determined from a fixed volume (8 µl) of fresh plaque and the rest of the plaque was used for culturing MS and lactobacilli. The retention...... of probiotics to the plaque was assessed using PCR techniques. No probiotic-induced changes were found in the acidogenicity of plaque. Also, MS counts remained at the original level. The number of subjects with lactobacilli in plaque increased in the L. reuteri group (p¿=¿0.011) but not in the LGG group. PCR...... analysis of plaque revealed the presence of LGG in four and L. reuteri in six subjects after the use of the probiotic. The use of the lactobacilli did not affect the acidogenicity or MS levels of plaque. Short-term consumption of LGG and L. reuteri appeared not to influence the acidogenicity of plaque....

  20. Comparative fracture strength analysis of Lava and Digident CAD/CAM zirconia ceramic crowns

    OpenAIRE

    Kwon, Taek-Ka; Pak, Hyun-Soon; Yang, Jae-Ho; Han, Jung-Suk; Lee, Jai-Bong; Kim, Sung-Hun; Yeo, In-Sung

    2013-01-01

    PURPOSE All-ceramic crowns are subject to fracture during function. To minimize this common clinical complication, zirconium oxide has been used as the framework for all-ceramic crowns. The aim of this study was to compare the fracture strengths of two computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia crown systems: Lava and Digident. MATERIALS AND METHODS Twenty Lava CAD/CAM zirconia crowns and twenty Digident CAD/CAM zirconia crowns were fabricated. A metal die was also ...

  1. Short clinical crowns (SCC) – treatment considerations and techniques

    Science.gov (United States)

    Rahul, G. R.; Poduval, Soorya T.; Shetty, Karunakar

    2012-01-01

    When the clinical crowns of teeth are dimensionally inadequate, esthetically and biologically acceptable restoration of these dental units is difficult. Often an acceptable restoration cannot be accomplished without first surgically increasing the length of the existing clinical crowns; therefore, successful management requires an understanding of both the dental and periodontal parameters of treatment. The complications presented by teeth with short clinical crowns demand a comprehensive treatment plan and proper sequencing of therapy to ensure a satisfactory result. Visualization of the desired result is a prerequisite of successful therapy. This review examines the periodontal and restorative factors related to restoring teeth with short clinical crowns. Modes of therapy are usually combined to meet the biologic, restorative, and esthetic requirements imposed by short clinical crowns. In this study various methods for treating short clinical crowns are reviewed, the role that restoration margin location play in the maintenance of periodontal and dental symbiosis and the effects of violation of the supracrestal gingivae by improper full-coverage restorations has also been discussed. Key words:Short clinical crown, surgical crown lengthening, forced eruption, diagnostic wax up, alveoloplasty, gingivectomy. PMID:24558561

  2. Short clinical crowns (SCC) - treatment considerations and techniques.

    Science.gov (United States)

    Sharma, Ashu; Rahul, G R; Poduval, Soorya T; Shetty, Karunakar

    2012-10-01

    When the clinical crowns of teeth are dimensionally inadequate, esthetically and biologically acceptable restoration of these dental units is difficult. Often an acceptable restoration cannot be accomplished without first surgically increasing the length of the existing clinical crowns; therefore, successful management requires an understanding of both the dental and periodontal parameters of treatment. The complications presented by teeth with short clinical crowns demand a comprehensive treatment plan and proper sequencing of therapy to ensure a satisfactory result. Visualization of the desired result is a prerequisite of successful therapy. This review examines the periodontal and restorative factors related to restoring teeth with short clinical crowns. Modes of therapy are usually combined to meet the biologic, restorative, and esthetic requirements imposed by short clinical crowns. In this study various methods for treating short clinical crowns are reviewed, the role that restoration margin location play in the maintenance of periodontal and dental symbiosis and the effects of violation of the supracrestal gingivae by improper full-coverage restorations has also been discussed. Key words:Short clinical crown, surgical crown lengthening, forced eruption, diagnostic wax up, alveoloplasty, gingivectomy.

  3. Medición de cambios cuantitativos de la microbiota subgingival posterior a la remoción de placa bacteriana supragingival Measurement of quantitative changes of the microbiota subgingival after to removal of bacterial plaque supragingival

    OpenAIRE

    C Godoy; C Melej; N Silva

    2010-01-01

    Uno de los campos de interés en el estudio de la microbiología periodontal para muchos investigadores ha sido identificar si es posible que los microorganismos responsables del origen y progresión de la enfermedad periodontal que habitan sobre el margen gingival (supragingival) y bajo este (subgingival) tengan una relación directa que permita mantener interacciones influyentes en el crecimiento y desarrollo de las diferentes especies bacterianas que habitan en los tejidos periodontales. Por l...

  4. Crowns and Crypts

    Indian Academy of Sciences (India)

    biologically occurring natural compounds they are expected to provide insight into the biological phenomena occurring in living systems. For example, the mechanism of the sodium pump occurring across a cell membrane could be understood using the formation of the alkali metal-crown complex mecha- nism as a model.

  5. Crowns and Crypts

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 6. Crowns and Crypts - A Fascinating Group of Multidentate Macrocyclic Ligands. Debasis Bandyopadhyay. General Article Volume 6 Issue 6 June 2001 pp 71-79. Fulltext. Click here to view fulltext PDF. Permanent link:

  6. Supragingival treatment as an aid to reduce subgingival needs: a 450-day investigation

    Directory of Open Access Journals (Sweden)

    Sabrina Carvalho Gomes

    2014-01-01

    Full Text Available This study investigated the clinical effects of using a supragingival biofilm control regimen (SUPRA as a step prior to scaling and root planing (SRP. A split-mouth clinical trial was performed in which 25 subjects with periodontitis (47.2 ± 6.5 years underwent treatment (days 0-60 and monitoring (days 90-450 phases. At Day 0 (baseline treatments were randomly assigned per quadrant: SUPRA, SRP and S30SRP (SUPRA 30 days before SRP. The full-mouth visible plaque index (VPI, gingival bleeding index (GBI, periodontal probing depth (PPD, bleeding on probing (BOP, and clinical attachment loss (CAL were examined on days 0, 30, 60, 90, 120, 270, and 450. Baseline data were similar among all groups. From days 0 to 60, the groups showed similar significant decreases in VPI and GBI. Reductions in PPD for the SRP (3.39 ± 0.17 to 2.42 ± 0.16 mm and S30SRP (3.31 ± 0.11 to 2.40 ± 0.07 mm groups were greater (p < 0.05 than those for the SUPRA group. This pattern was also observed for BOP. Attachment gain was similar and greater for the SRP (3.34 ± 0.28 to 2.58 ± 0.26 mm and S30SRP (3.25 ± 0.21 to 2.54 ± 0.19 mm groups compared to the SUPRA group. Results were maintained from day 90 forward. Overall, the S30SRP treatment reduced the subgingival treatment needs in 48.16%. Performance of a SUPRA step before SRP decreased subgingival treatment needs and maintained the periodontal stability over time.

  7. Comparative fracture strength analysis of Lava and Digident CAD/CAM zirconia ceramic crowns

    Science.gov (United States)

    Kwon, Taek-Ka; Pak, Hyun-Soon; Han, Jung-Suk; Lee, Jai-Bong; Kim, Sung-Hun

    2013-01-01

    PURPOSE All-ceramic crowns are subject to fracture during function. To minimize this common clinical complication, zirconium oxide has been used as the framework for all-ceramic crowns. The aim of this study was to compare the fracture strengths of two computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia crown systems: Lava and Digident. MATERIALS AND METHODS Twenty Lava CAD/CAM zirconia crowns and twenty Digident CAD/CAM zirconia crowns were fabricated. A metal die was also duplicated from the original prepared tooth for fracture testing. A universal testing machine was used to determine the fracture strength of the crowns. RESULTS The mean fracture strengths were as follows: 54.9 ± 15.6 N for the Lava CAD/CAM zirconia crowns and 87.0 ± 16.0 N for the Digident CAD/CAM zirconia crowns. The difference between the mean fracture strengths of the Lava and Digident crowns was statistically significant (Pzirconia crowns showed a complete fracture of both the veneering porcelain and the core whereas the Digident CAD/CAM zirconia crowns showed fracture only of the veneering porcelain. CONCLUSION The fracture strengths of CAD/CAM zirconia crowns differ depending on the compatibility of the core material and the veneering porcelain. PMID:23755332

  8. Successful Restoration of Severely Mutilated Primary Incisors Using a Novel Method to Retain Zirconia Crowns - Two Year Results.

    Science.gov (United States)

    El Shahawy, Osama Ibrahim; O'Connell, Anne C

    This manuscript describes a simple reliable technique for restoring severely mutilated primary anterior teeth. A rigid glass ionomer post is created over which zirconia crowns can be fitted to achieve a long-term stable esthetic restoration for primary anterior teeth. Children aged 2-5 years with two up to six extensively decayed upper primary incisors were included. Fuji IX was condensed into an intracanal space created to a depth of 3mm, to provide a core which also extended 3mm supragingivally. Crown preparations were completed upon these cores. Zirconia crowns (Nusmile, Houston Texas USA) were fitted and cemented over the prepared cores. All patients were recalled at regular intervals. Twenty-three healthy children with 86 restorations participated in the study. The overall survival of the restorations was 95.3% after 12 months and 80.2% after 24 months. According to Kaplan-Meier survival analysis, the median survival time was not reached while the estimated mean survival time was 22.9 months. This newly described clinical technique is simple and reliable to use for restoration of extensively decayed primary incisors. Use of zirconia crowns retained using this technique offers superior esthetic, durable restorations with remarkable gingival response up to 24 months.

  9. A 3-year retrospective and clinical follow-up study of zirconia single crowns performed in a private practice.

    Science.gov (United States)

    Ortorp, Anders; Kihl, Maria Lind; Carlsson, Gunnar E

    2009-09-01

    All-ceramic crowns have become increasingly used also in the posterior regions, but there are only few studies documenting the clinical outcome of these restorations. The aim was therefore to present the 3-year outcome of zirconia (NobelProcera) single crowns. All patients treated with porcelain-veneered zirconia single crowns in a private practice during the period October 2004 to November 2005 were included. The patient records were scrutinized for data on the restorations and the supporting teeth. Information was available for 161 patients and 204 crowns. At the 3-year recall appointments, a sample of 18 patients with 25 crowns was clinically examined and interviewed regarding patient satisfaction. Most crowns (78%) were placed on premolars and molars. The clinical outcome of the crowns was favourable. No zirconia core fractured and no caries was observed on the abutment teeth. Some types of complication were recorded for 32 (16%) crowns or abutment teeth. The most severe complications, in total 12 restorations (6%), were recorded as failures: abutment tooth was extracted (5), remake of crown due to lost retention (4), veneer fracture (2) and persistent pain (1). The CDA criteria for 25 crowns were rated favourably, and patient satisfaction with the zirconia crowns was in general high. The porcelain-veneered zirconia crowns (NobelProcera) showed good clinical results, were well accepted by the patients, and only few complications were reported over the 3-year follow-up period.

  10. Mouthwashes for the control of supragingival biofilm and gingivitis in orthodontic patients: evidence-based recommendations for clinicians

    Directory of Open Access Journals (Sweden)

    Alex Nogueira HAAS

    2014-01-01

    Full Text Available Properly performed daily mechanical biofilm control is the most important prevention strategy for periodontal diseases. However, proper mechanical biofilm control is not performed effectively by the majority of the population, mainly due to lack of motivation and of manual dexterity. Local biofilm retention factors may aggravate home oral hygiene quality. For this reason, patients wearing fixed orthodontic appliances comprise a group that may benefit from the daily use of mouthwashes. The purpose of this review was to perform a systematic search in the literature on antiseptics used to control supragingival biofilm and gingivitis in orthodontic patients. Six studies investigating the effect of chlorhexidine and 5 studies evaluating the effect of the daily use of antiseptics were found. Chlorhexidine showed better results in reducing plaque and gingivitis. However, because of its adverse effects after continuous use, it should not be indicated for long-term periods. Among the agents considered for daily use, the fixed combination of essential oils was the only one evaluated in a clinical trial, in which a comparative group presented a statistically significant clinical impact. There is no direct evidence supporting the indication of antiseptic agents for orthodontic patients other than chlorhexidine and essential oils. It can be concluded that, for patients undergoing orthodontic treatment, chlorhexidine should be considered for treating acute gingival inflammation, whereas essential oils should be indicated for long-term daily use in controlling supragingival biofilm.

  11. Clinical evaluation of zirconia-based all-ceramic single crowns: an up to 12-year retrospective cohort study.

    Science.gov (United States)

    Miura, Shoko; Kasahara, Shin; Yamauchi, Shinobu; Okuyama, Yayoi; Izumida, Akio; Aida, Jun; Egusa, Hiroshi

    2018-03-01

    This study aims to investigate the incidence of clinical complications with tooth-supported zirconia-based all-ceramic single crowns and identify pertinent risk parameters. A retrospective cohort study (May 2004 to April 2016) utilizing clinical records of patients receiving yttrium-oxide-partially stabilized zirconia (Y-TZP)-based all-ceramic crowns placed at Tohoku University Hospital was performed. The length of time of treatment success (complication event-free) and restoration survival (including minor complication events and remaining clinically functional) were estimated using Kaplan-Meier analysis. Multilevel survival analysis was used to identify risk factors. One hundred thirty-seven crowns were evaluated (mean follow-up time, 7.0 years). A total of 21 crowns experienced at least one complication with fracture of veneering ceramic being the most common (16 crowns). Estimated success and survival rates at 5 years (96.9 and 98.5%, respectively) decreased at 10 years to 62.1 and 67.2%, respectively. The risk of complications was significantly higher for molar crowns compared to anterior crowns (p crowns placed on anterior teeth demonstrated encouraging clinical results over a period of up to 10 years. However, there is a substantial risk of complications with posterior teeth within 10 years of restoration placement. Treatment with zirconia-based all-ceramic crowns for molar teeth with metal antagonist occlusion should be undertaken with caution.

  12. Crowned dens syndrome

    Directory of Open Access Journals (Sweden)

    Norma Belfiore

    2012-10-01

    Full Text Available Introduction Microcrystalline deposition in peri-odontoid articular structures is mainly responsible for acute or chronic cervical pain and is known as “crowned dens syndrome”.Materials and methods We described two cases of acute cervical pain associated with onset of fever and peripheral acute monoarthritis. Cervical computed tomography (CT scan showed linear calcification of the retrodens ligament and calcium pyrophosphate dehydrate (CPPD crystals were found in synovial fluid of inflamed joints. Both patients were treated with anti-inflammatory drugs and colchicine.Discussion Calcium depositions around the odontoid process of the axis can be occasionally detected by radiological studies. They are frequently asymptomatic but sometimes can be associated with severe neurological abnormalities, fever and acute neck pain. CPPD crystals are usually deposited in joints and bursae but occasionally can disrupt these anatomical confines and deposit in periarticular tissues, sometimes forming large masses confused with tumours.Conclusions Acute onset of cervical neck pain associated with elevation of inflammatory indicators and/or signs of cervical myelopathy should suggest CT scans searching for microcrystal depositions in the peryodonthoid tissue. Differential diagnosis of fever of unknown origin (FUO should include crowned dens syndrome specially in the elderly after exclusion of several endocrine or metabolic disorders, infection diseases (meningitis, arthritis (psoriatic arthritis and ankylosing spondylitis and tumours (chordoma, meningioma, osteoblastoma.

  13. Ready to crown

    LENUS (Irish Health Repository)

    McReynolds, David

    2017-04-01

    When multiple teeth or localised segments of the mouth require crowns, the restorative interventions involved can be psychologically and physically demanding for the operator, patient and dental technician alike.1,2 It is important that all parties involved in restorations of this nature hold a shared understanding of the expected outcome of treatment, with a realistic, common end goal in mind right from the very beginning. Such clarity of thought and communication is key to avoiding biological, mechanical and aesthetic failures in the planning and execution of advanced restorative treatments. Biomechanically stable and aesthetically pleasing provisional restorations are an essential aspect of treatment, which allow teeth to be prepared and provisionalised over multiple appointments within the comfort zone of the operator and patient.3

  14. Clinical performance of two different CAD/CAM-fabricated ceramic crowns: 2-Year results.

    Science.gov (United States)

    Seydler, Bodo; Schmitter, Marc

    2015-08-01

    Recently, technical problems, especially chipping, have been reported for ceramic restorations; as a result, ceramic crowns produced entirely by computer-aided design and computer-aided manufacture (CAD/CAM) have become popular because the incidence of chipping is less. The purpose of this study was to report on 2-year results for 2 different types of CAD/CAM ceramic crowns placed in adult patients in a dental practice. Sixty participants who required a crown for a first or second molar were randomly assigned to 1 of 2 groups. Crowns in the veneered zirconia (VZ) group were made of zirconia frameworks veneered with CAD/CAM-produced lithium disilicate ceramic; the other group's crowns were made of monolithic lithium disilicate (MLD) ceramic. Each crown was reviewed after 2 weeks, 1 year, and 2 years by using modified the US Public Health Service (USPHS) criteria. Statistical analysis was performed by using the log-rank test, nonparametric tests, and Kaplan-Meier survival analysis. All 60 participants were recalled after 1 and 2 years. In the VZ group, 2 endodontic complications occurred, and deterioration of periodontal health was observed for 3 participants. In the MLD group, 2 endodontic complications occurred within 2 years. In both of the groups, no caries or marginal discoloration was observed. No technical complications, for example, cracks, chipping, or fractures, were detected after 2 years. The shape and appearance of all crowns were assessed positively by the examining dentist. The log-rank test showed no significant differences in respect to technical or biologic complications (P=.324). For both types of single-crown restoration, no technical failures occurred. The number of biological complications did not differ significantly between the types of crowns. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  15. Overdenture dengan Pegangan Telescopic Crown

    Directory of Open Access Journals (Sweden)

    Pambudi Santoso

    2014-06-01

    Full Text Available Kaitan presisi merupakan alat retensi mekanis yang menghubungkan antara satu atau lebih pegangan gigi tiruan, yang bertujuan untuk menambah retensi dan/atau stabilisasi. Kaitan presisi dapat digunakan secara luas pada gigi tiruan cekat, gigi tiruan sebagian lepasan, overdenture, implant untuk retensi overdenture, dan protesa maksilo fasial. Overdenture dengan kaitan presisi dapat membantu dalam pembagian beban kunyah, meminimalkan trauma pada gigi pegangan dan jaringan lunak, meminimalkan resorbsi tulang, dan meningkatkan estetik dan pengucapan suara. Salah satu jenis dari kaitan presisi adalah telescopic crown, terdiri dari 2 macam mahkota, yaitu mahkota primer yang melekat secara permanen pada gigi penyangga, dan mahkota sekunder yang melekat pada gigi tiruan. Tujuan pemaparan kasus ini adalah untuk memberikan informasi tentang rehabilitasi pasien edentulous sebagian rahang atas dengan telescopic crown..  Pasien wanita berusia 45 tahun datang ke klinik prostodonsia RSGM Prof.Soedomo dengan keluhan ingin dibuatkan gigi tiruan. Pasien kehilangan gigi 11 12 15 16 17 21 22 24 25 26 dan 27 yang diindikasikan untuk pembuatan overdenture gigi tiruan sebagian lepasan (GTS kerangka logam dengan pegangan telescopic crown pada gigi 13 dan 14 dengan sistem parallel-sided crown. Tahap-tahap pembuatan telescopic crown yaitu mencetak model study dengan catatan gigit pendahuluan. Perawatan saluran dilakukan pada akar gigi 13, dilanjutkan pemasangan pasak fiber serta rewalling dinding bukal. Gigi 13 dan 14 dilakukan preparasi mahkota penuh, dilanjutkan dengan pencetakan model kerja untuk coping primer dan kerangka logam dengan metode double impression. Coping primer disementasi pada gigi penyangga, dilanjutkan pasang coba coping sekunder beserta kerangka logam. Selanjutnya dilakukan pencatatan gigit, pencetakan model kerja, penyusunan gigi dan pasang coba penyusunan gigi pada pasien. Prosedur dilanjutkan dengan proses di laboratorium, serta insersi pada

  16. Effectiveness of a mouthrinse containing active ingredients in addition to chlorhexidine and triclosan compared with chlorhexidine and triclosan rinses on plaque, gingivitis, supragingival calculus and extrinsic staining.

    Science.gov (United States)

    Kumar, S; Patel, S; Tadakamadla, J; Tibdewal, H; Duraiswamy, P; Kulkarni, S

    2013-02-01

    To assess the effectiveness of three different mouthrinses--chlorhexidine, triclosan + sodium fluoride and chlorhexidine + triclosan + sodium fluoride + zinc chloride--on plaque, calculus, gingivitis and stains and to evaluate the occurrence of adverse effects with these three treatments. Forty-eight healthy subjects participated in a double-blind, randomized, parallel experiment and were randomly allocated to any one of the three experimental mouthrinses: group A (0.2% chlorhexidine (CHX) gluconate), group B (0.03% triclosan + 0.025% sodium fluoride (NaF) + 12% ethyl alcohol) or group C (0.2% CHX + 0.3% triclosan + 0.3% NaF + 0.09% Zn chloride (ZnCl(2)). All the subjects were assessed for gingivitis, plaque, supragingival calculus and extrinsic stains at baseline and at the end of the 21-day experimental period. There was a significant difference (P = 0.046) in the effectiveness for the prevention of gingivitis and plaque, with subjects of group A and group C presenting least and highest gingival and plaque scores, respectively. Significant differences (P = 0.03) were observed for the accumulation of supragingival calculus where the deposition of calculus in group A was nearly double that of the group B, and group B was most effective in the prevention of supragingival calculus. Highest deposition of extrinsic stains was in the group A followed by group C and group B. There was no significant difference between the three treatments for adverse events' occurrence. CHX mouthrinse was most effective in controlling plaque and gingivitis but caused greatest deposition of extrinsic stains. Supragingival calculus deposition was least in triclosan + NaF group followed by CHX + triclosan + NaF + ZnCl(2) and CHX. More than half of the subjects reported adverse events during the experimental phase. © 2012 John Wiley & Sons A/S.

  17. Crown rust control on oats

    International Nuclear Information System (INIS)

    Frey, K.J.; Browning, J.A.; Simons, M.D.

    1976-01-01

    Attempts have been made to test the relative effectiveness of EMS treatment for inducing tolerance to crown rust among oat strains Clintland-60 of different ploidy levels. One strain of diploid and one of tetraploid oats were treated with EMS. These two strains are as susceptible to damage from crown rust as are cultivars of hexaploid oats. Multiline cultivars of oats have been shown to provide adequate protection from economic loss due to crown-rust disease in Iowa. Since 1968, eleven multiline cultivars of oats have been released from the Iowa station for use in commercial production in the midwestern USA. During the past two winter seasons, the effectiveness of multiline oat cultivars against crown-rust disease has been researched in Texas, USA, which has a ''long rust season'' of about four months, not an Iowa ''short rust season''. The protection against crown rust afforded by the multiline cultivars appeared equally good in Texas and Iowa. The seasonal productions of crown-rust spores relative to completely resistant and susceptible checks were nearly identical in both environments. Fifteen new isolines of oats have been developed for use in multiline varieties, with seed supplies sufficiently large for immediate use

  18. Electroplated telescopic retainers with zirconia primary crowns: 3-year results from a randomized clinical trial.

    Science.gov (United States)

    Schwindling, Franz Sebastian; Lehmann, Franziska; Terebesi, Sophia; Corcodel, Nicoleta; Zenthöfer, Andreas; Rammelsberg, Peter; Stober, Thomas

    2017-12-01

    The objective of the study was to investigate the clinical outcome for electroplated telescopic removable dental prostheses (E-RDPs) with zirconia primary crowns. Sixty E-RDPs, with primary crowns manufactured from either cobalt-chromium alloy or zirconia, were fabricated for 56 participants. Electroplating was used to produce gold copings directly on the telescopic primary crowns. These copings were bonded intra-orally to the prosthesis framework. After 36 months, prosthesis survival and number of complications were assessed. Statistical analysis was performed by the use of Kaplan-Meier modeling and the log-rank test. Survival of the E-RDPs, 96.4% after 3 years, was identical in both groups. The need for aftercare was high but not significantly different: technical complications were observed for 37% and 42.9% of the prostheses for the zirconia and cobalt-chromium alloy primary crowns, respectively. Fracture of composite veneer was the most frequent complication (59.1%). The incidence of fractured abutment teeth, decementation, and endodontic problems was 7.9% in the zirconia group and 14% in the control group. The majority of abutment-level complications were treated restoratively. A significant difference was found for maximum probing depth at the abutment teeth: In the zirconia group, it decreased by 0.2 mm, whereas it increased by 0.8 mm in the control group (p = 0.04). After 3 years of observation, survival of zirconia E-RDPs was favorable and comparable with that of established double-crown-retained prostheses. Further studies must clarify whether there are benefits of zirconia primary crowns for periodontal health. Although these results encourage the use of zirconia primary crowns, more research is necessary to reduce the number of complications observed for secondary telescopic crowns, for example, failure of the veneer.

  19. Efficacy of an unwaxed dental floss impregnated with 2% chlorhexidine on control of supragingival biofilm: A randomized, clinical trial.

    Science.gov (United States)

    Muniz, Francisco Wilker Mustafa Gomes; da Silva Lima, Heitor; Rösing, Cassiano Kuchenbecker; Martins, Ricardo Souza; Moreira, Maria Mônica Studart Mendes; Carvalho, Rosimary de Sousa

    2018-02-01

    In the present study, we evaluated the antiplaque and antigingivitis efficacy of a dental floss impregnated with 2% chlorhexidine digluconate. Thirty dental students were randomly divided into three groups (n=10): (a) negative control (NC) group, in which no interproximal cleaning was performed; (b) the positive control (PC) group, which used a standard unwaxed dental floss twice daily; and (c) and the test group, which used a unwaxed dental floss impregnated with 2% chlorhexidine twice daily. Six surfaces per tooth were evaluated by the Quigley-Hein plaque index (Turesky modification) at the last appointment (day 15), and testing for the presence of marginal bleeding was performed using the marginal bleeding index (MBI) at both the baseline and last appointments. At day 15, the test group had the lowest mean plaque index (1.04±0.67), showing a statistically-significant difference compared to the NC group (1.40±0.65, Pdental floss impregnated with 2% chlorhexidine showed additional reductions in supragingival interproximal biofilm compared with a conventional unwaxed dental floss, without additional improvement in marginal bleeding. © 2017 John Wiley & Sons Australia, Ltd.

  20. Monolithic zirconia crowns in the aesthetic zone in heavy grinders with severe tooth wear - An observational case-series.

    Science.gov (United States)

    Hansen, Torbjørn Leif; Schriwer, Christian; Øilo, Marit; Gjengedal, Harald

    2018-02-13

    The aim of this study was to assess the clinical outcomes and patient satisfaction with monolithic zirconia crowns in patients with severe tooth wear (≥1/3 of the tooth crown) in the aesthetic zone. The historical prospective study sample consisted of 13 patients previously treated with a total of 84 monolithic zirconia crowns. The patients had been treated in a private clinic in Bergen, Norway, in the period 2012 to 2014. All patients were men, aged 35-67 years (mean age 56.3 years) and had been in need of prosthetic rehabilitation because of severe tooth wear in the aesthetic zone. Technical complications as well as biologic findings were registered when the crowns had been in function one to three years (mean 20 months). The patients completed a self-administered questionnaire regarding satisfaction with aesthetic and function. No biological complications were registered in 79 of the crowns (94%), and technical complications were registered in only two patients. All patients were satisfied with the aesthetic and function of the monolithic zirconia crowns and would choose the same treatment modality if they were to be treated again. Within the limitations of this study, we conclude that the rate of clinical complications was low and that the patients were satisfied with the aesthetic as well as the function of the monolithic zirconia crowns. Monolithic zirconia crowns may provide a valid treatment modality in the aesthetic zone in patients with severe tooth wear. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. Chair-side generated posterior monolithic lithium disilicate crowns: clinical survival after 6 years.

    Science.gov (United States)

    Rauch, Angelika; Reich, Sven; Schierz, Oliver

    2017-07-01

    The objective of this prospective clinical study was to evaluate the clinical performance of chair-side generated monolithic lithium disilicate crowns after 72 months. Forty-one posterior full contour crowns made of lithium disilicate ceramic were inserted in 34 patients with a chair-side CAD/CAM technique. One crown per patient was randomly selected for evaluation at baseline, 6, 12, 24, 36, 48, 60 and 72 months according to the modified US Public Health Service criteria. After a mean examination time of 73.2 months (SD ± 1.7 months), 25 crowns were available for re-examination. Within the observation period, three failures occurred due to one crown fracture after 2.9 years, an abutment fracture after 6.0 years, and one severe endodontic problem after 6.1 years. One lithium disilicate crown showed a loss of retention after 2 years but could be reinserted. There were two events of caries below the crown margin, one after 24 and another one after 48 months. Both teeth received cervical adhesive composite fillings. Two abutment teeth changed their sensibility perception from positive to negative within the first 13 months. The failure-free rate was 87.6%, and the complication-free rate was 70.1% after 6 years according to the Kaplan-Meier analysis. Due to the fact that there was only one severe technical complication and the severe biological complications were in a normal range, the clinical performance of monolithic lithium disilicate crowns in the posterior region was completely satisfying. The chair-side application of monolithic lithium disilicate crowns can be recommended.

  2. Wave Forces on Crown Walls

    DEFF Research Database (Denmark)

    Pedersen, Jan; Burcharth, H. F.

    1993-01-01

    This paper presents some of the results from a large parametric laboratory study including more than 200 long-duration model tests. The study addresses both the wave forces imposed on the breakwater crown wall as well as the performance of the structure in reducing the wave overtopping. The testing...... programme includes variations of the sea state parameters and of the geometrical configuration of the breakwater and crown wall. Basic relations between forces/overtopping and the varied parameters are examined and preliminary design guidelines for structures within the tested range of variations...

  3. Displacement of screw-retained single crowns into implants with conical internal connections.

    Science.gov (United States)

    Yilmaz, Burak; Seidt, Jeremy D; McGlumphy, Edwin A; Clelland, Nancy L

    2013-01-01

    Internal conical implant-abutment connections without platforms may lead to axial displacement of crowns during screw tightening. This displacement may affect proximal contacts, incisal edge position, or occlusion. This study aimed to measure the displacement of screw-retained single crowns into an implant in three dimensions during screw tightening by hand or via torque driver. A stereolithic acrylic resin cast was created using computed tomography data from a patient missing the maxillary right central incisor. A 4.0- × 11-mm implant was placed in the edentulous site. Five porcelain-fused-to-metal single crowns were made using "cast-to" abutments. Crowns were tried on the stereolithic model, representing the patient, and hand tightened. The spatial relationship of crowns to the model after hand tightening was determined using three-dimensional digital image correlation (3D DIC), an optical measurement technique. The crowns were then tightened using a torque driver to 20 Ncm and the relative crown positions were again recorded. Testing was repeated three times for each crown, and displacement of the crowns was compared between the hand-tightened and torqued states. Commercial image correlation software was used to analyze the data. Mean vertical and horizontal crown displacement values were calculated after torqueing. The interproximal contacts were evaluated before and after torquing using an 8-μm aluminum foil shim. There were vertical and horizontal differences in crown positions between hand tightening and torqueing. Although these were small in magnitude, detectable displacements occurred in both apical and facial directions. After hand tightening, the 8-μm shim could be dragged without tearing. However, after torque tightening, the interproximal contacts were too tight and the 8-μm shim could not be dragged without tearing. Differences between hand tightening and torque tightening should be taken into consideration during laboratory and clinical

  4. An esthetic technique for veneering anterior stainless steel crowns with composite resin.

    Science.gov (United States)

    Wiedenfeld, K R; Draughn, R A; Welford, J B

    1994-01-01

    The restoration of primary anterior teeth presents complicated esthetic and retention problems to the clinician. A technique is described for the chairside veneering of composite resin to stainless steel crowns, which results in well contoured restorations with superior durability and esthetics. A trimmed and fitted stainless steel crown can be veneered in three to five minutes. This provides the adaptability and gingival contour benefits of the stainless steel crown in conjunction with the cosmetics of the composite facings. The technique described produced composite veneers with a mean sheer bond strength of 3520 PSI (24.4 Mpa).

  5. Tooth preparations for complete crowns: an art form based on scientific principles.

    Science.gov (United States)

    Goodacre, C J; Campagni, W V; Aquilino, S A

    2001-04-01

    No recent literature has reviewed the current scientific knowledge on complete coverage tooth preparations. This article traces the historic evolution of complete coverage tooth preparations and identifies guidelines for scientific tooth preparations. Literature covering 250 years of clinical practice was reviewed with emphasis on scientific data acquired during the last 50 years. Both a MEDLINE search and an extensive manual search were used to locate relevant articles written in English in the last 50 years. Teeth should be prepared so that they exhibit the following characteristics: 10 to 20 degrees of total occlusal convergence, a minimal occlusocervical dimension of 4 mm for molars and 3 mm for other teeth, and an occlusocervical-to-faciolingual dimension ratio of 0.4 or greater. Facioproximal and linguoproximal line angles should be preserved whenever possible. When the above features are missing, the teeth should be modified with auxiliary resistance features such as axial grooves or boxes, preferably on proximal surfaces. Finish line selection should be based on the type of crown/retainer, esthetic requirements, ease of formation, and personal experience. Expectations of enhanced marginal fit with certain finish lines could not be validated by recent research. Esthetic requirements and tooth conditions determine finish line locations relative to the gingiva, with a supragingival location being more acceptable. Line angles should be rounded, and a reasonable degree of surface smoothness is desired. Nine scientific principles have been developed that ensure mechanical, biologic, and esthetic success for tooth preparation of complete coverage restorations.

  6. A 5-year retrospective study of survival of zirconia single crowns fitted in a private clinical setting.

    Science.gov (United States)

    Ortorp, Anders; Kihl, Maria Lind; Carlsson, Gunnar E

    2012-06-01

    The aim of this report was to evaluate the 5-year clinical performance and survival of zirconia (NobelProcera™) single crowns. All patients treated with porcelain-veneered zirconia single crowns in a private practice during the period October 2004 to November 2005 were included. The records were scrutinized for clinical data. Information was available for 162 patients and 205 crowns. Most crowns (78%) were placed on premolars and molars. Out of the 143 crowns that were followed for 5 years, 126 (88%) did not have any complications. Of those with complications, the most common were: extraction of abutment tooth (7; 3%), loss of retention (15; 7%), need of endodontic treatment (9; 4%) and porcelain veneer fracture (6; 3%). No zirconia cores fractured. In total 19 restorations (9%) were recorded as failures: abutment tooth extraction (7), remake of crown due to lost retention (6), veneer fracture (4), persistent pain (1) and caries (1). The 5-year cumulative survival rate (CSR) was 88.8%. According to the present 5-year results zirconia crowns (NobelProcera™) are a promising prosthodontic alternative also in the premolar and molar regions. Out of the 143 crowns followed for 5 years, 126 (88%) did not have any complications. However, 9% of the restorations were judged as failures. Further studies are necessary to evaluate the long-term success. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Earth Pressure on Tunnel Crown

    DEFF Research Database (Denmark)

    Andersen, Lars

    Two different analyses have been carried out in order to find the vertical earth pressure, or overburden pressure, at the crown of a tunnel going through a dike. Firstly, a hand calculation is performed using a simple dispersion of the stresses over depth. Secondly, the finite‐element program...

  8. Impact of supragingival therapy on subgingival microbial profile in smokers versus non-smokers with severe chronic periodontitis

    Directory of Open Access Journals (Sweden)

    Tatiana Meulman

    2012-01-01

    Full Text Available The aim of this study was to assess subgingival microbiological changes in smokers versus non-smokers presenting severe chronic periodontitis after supragingival periodontal therapy (ST.Non-smokers (n=10 and smokers (n=10 presenting at least nine teeth with probing pocket depth (PPD (≥5 mm, bleeding on probing (BoP, and no history of periodontal treatment in the last 6 months were selected. Clinical parameters assessed were plaque index (PI, BoP, PPD, relative gingival margin position (rGMP and relative clinical attachment level (rCAL. Subgingival biofilm was collected before and 21 days after ST. DNA was extracted and the 16S rRNA gene was amplified with the universal primer pair, 27F and 1492R. Amplified genes were cloned, sequenced, and identified by comparison with known 16S rRNA sequences. Statistical analysis was performed by Student's t and Chi-Square tests (α=5%.Clinically, ST promoted a significant reduction in PI and PPD, and gain of rCAL for both groups, with no significant intergroup difference. Microbiologically, at baseline, data analysis demonstrated that smokers harbored a higher proportion of Porphyromonas endodontalis, Bacteroidetes sp., Fusobacterium sp. and Tannerella forsythia and a lower number of cultivated phylotypes (p<0.05. Furthermore, non-smokers featured significant reductions in key phylotypes associated with periodontitis, whereas smokers presented more modest changes.Within the limits of the present study, ST promoted comparable clinical improvements in smokers and non-smokers with severe chronic periodontitis. However, in smokers, ST only slightly affected the subgingival biofilm biodiversity, as compared with non-smokers.

  9. Removal of failed crown and bridge

    OpenAIRE

    Sharma, Ashu; Rahul, G.R.; Poduval, Soorya T.; Shetty, Karunakar

    2012-01-01

    Crown and bridge have life span of many years but they fail for a number of reasons. Over the years, many devices have been designed to remove crowns and bridges from abutment teeth. While the removal of temporary crowns and bridges is usually very straightforward, the removal of a definitive cast crown with unknown cement is more challenging. Removal is often by destructive means. There are a number of circumstances, however, in which conservative disassembly would aid the practitioner in co...

  10. Prospective observation of CAD/CAM titanium ceramic single crowns: a three-year follow up.

    Science.gov (United States)

    Boeckler, Arne F; Lee, Heeje; Stadler, Anke; Setz, Jürgen M

    2009-11-01

    Computer-aided design/computer-aided manufacturing (CAD/CAM) titanium ceramic restorations were developed with the potential for replacing expensive, high noble metal ceramic restorations. However, there is a lack of information about the clinical performance of CAD/CAM titanium ceramic single crowns. The purpose of this study was to evaluate CAD/CAM titanium ceramic single crowns after 3 years in function. A total of 41 crowns were fabricated for 21 patients. The titanium copings were CAD/CAM milled (Everest CAD/CAM system) with an even thickness of 0.5 mm, and low-fusing veneering porcelain (Vita Titanium Porcelain) was added incrementally. The crowns were cemented using zinc phosphate cement after confirming that there were no mechanical and biological complications. The patients were recalled at 12, 24, and 36 months after cementation to examine the presence of any complications and measure periodontal parameters such as probing depth (PD), bleeding on probing (BOP), and plaque index (PI). The success and survival rates were estimated using the Kaplan-Meier analysis. The success rate of CAD/CAM titanium ceramic crowns with regard to mechanical complications was 82.3% (95% confidence interval: 71.2% to 95.1%). The cumulative survival rate of the crowns was 94.9% (95% confidence interval: 88.3% to 100%) after 3 years. No biological complications were observed. At the end of the follow up, PD was 2.93 mm, percentile of surface with BOP was 29.2, and PI was 0.31. The clinical performances of the CAD/CAM titanium ceramic crowns for 3 years were acceptable, with no biologic complications and a high cumulative survival rate.

  11. Equations to convert compacted crown ratio to uncompacted crown ratio for trees in the Interior West

    Science.gov (United States)

    Chris Toney; Matthew C. Reeves

    2009-01-01

    Crown ratio is the proportion of total tree length supporting live foliage. Inventory programs of the US Forest Service generally define crown ratio in terms of compacted or uncompacted measurements. Measurement of compacted crown ratio (CCR) involves envisioning the transfer of lower branches of trees with asymmetric crowns to fill holes in the upper portion of the...

  12. Extended-spectrum beta-lactamase-producing bacteria are not detected in supragingival plaque samples from human fecal carriers of ESBL-producing Enterobacteriaceae

    Directory of Open Access Journals (Sweden)

    Arne Søraas

    2014-08-01

    Full Text Available Background: The prevalence of infections caused by Cefotaximase-Munich (CTX-M-type extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E has rapidly increased during the past 15 years. Enterobacteriaceae are commonly found in the gastrointestinal tract and long-term intestinal carriage is considered important for the spread of ESBL and as a source of clinical infections. Oral biofilm such as supragingival plaque is known to contain numerous antibiotic resistance determinants and may also represent a poorly investigated site for ESBL carriage and further spread. Objective: To investigate possible carriage of ESBL-producing bacteria in supragingival plaque of known fecal carriers of these bacteria. Design: We screened for the presence of aerobic and anaerobic ESBL-producing bacteria and blaCTX-M in supragingival plaque samples from healthy human adults with culture-verified fecal carriage of CTX-M-producing Escherichia coli. The presence or absence of Enterobacteriaceae and ESBL-producing bacteria in plaque samples was evaluated using culture-based methods and consensus CTX-M PCR. Results: Oral samples were obtained from 17 participants with known previous carriage of ESBL-producing E. coli. No ESBL-producing bacteria or ESBL genes were detected using culture-based and molecular methods. One colony of Rahnella aquatilis harboring the class A ESBL gene bla RAHN-1/2 was identified in an oral sample from one of the participants. Conclusion: This pilot study supports the notion that the presence of CTX-M-producing bacteria is uncommon in oral plaque of healthy human adult fecal carriers. Due to the limited number of persons tested, a low prevalence of oral ESBL-carriage in healthy adults or carriage in selected groups of patients cannot be excluded. To our knowledge, this is the first description of an R. aquatilis with the RAHN-1/2 gene in the oral cavity.

  13. CAD/CAM technology for implant abutments, crowns, and superstructures.

    Science.gov (United States)

    Kapos, Theodoros; Evans, Christopher

    2014-01-01

    The aim of this systematic review was to compare implant prostheses fabricated by computer-assisted design and computer-assisted manufacturing (CAD/CAM) with conventionally fabricated implant prostheses when assessing esthetics, complications (biologic and mechanical), patient satisfaction, and economic factors. Electronic searches for clinical studies focusing on long-term follow-up were performed using the PubMed and Ovid search engines. Concentrating on the restorative aspect of the CAD/CAM technology applicable to implant dentistry, pertinent literature was divided into articles related to implant abutments, crowns, and frameworks. A total of 18 articles satisfied the inclusion criteria. Two articles reported on CAD/CAM crowns, six on abutments, and 10 on implant-supported CAD/CAM frameworks. The mean survival rate for CAD/CAM crowns was 98.85% and for CAD/CAM abutments 100%. The mean survival rate for CAD/CAM frameworks was 95.98%. Based on the current literature, CAD/CAM fabricated crowns, abutments, and frameworks demonstrate survival rates comparable to conventionally fabricated prostheses. Implant survival appears unaffected by fabrication technique. Since this technology encompasses several manufacturing variations, a new definition might be necessary to accurately define the processes under which the CAD/CAM restorations are fabricated. "Complete CAD/CAM product" where no or minimal manual intervention is employed could be a possible term.

  14. Comparative efficacy on supragingival plaque and gingivitis of a manual toothbrush (Colgate Plus) and a battery-powered toothbrush (Colgate Actibrush) over a 30-day period.

    Science.gov (United States)

    Sharma, N; Galustians, H J; Qaqish, J G; Rustogi, K N; Petrone, M E; Volpe, A R

    2000-01-01

    This clinical study compared the effect of Colgate Actibrush, a battery-powered toothbrush, and Colgate Plus Diamond Head, a full-head, soft-bristled manual toothbrush, on established supragingival plaque and gingivitis over a 30-day period. Sixty-two healthy adult men and women were entered in the study. The subjects were stratified into two balanced groups according to their mean baseline plaque and gingivitis scores. Each group was randomly assigned to the use of one of the two toothbrushes. Subjects were instructed to brush their teeth at home twice daily (morning and evening) for 1 minute with their assigned toothbrush and a commercially available tooth-paste for the 30-day duration of the study. Gingivitis and plaque examinations, as well as a soft-tissue evaluation, were conducted by the same dental examiner at baseline and after 15 and 30 days of toothbrush use. Plaque and gingivitis scores were reduced significantly from baseline after the use of both toothbrushes for 30 days. However, improvement in both supragingival plaque and gingivitis scores was significantly greater in the group using Colgate Actibrush. In conclusion, although both toothbrushes provided a significant plaque and gingivitis benefit when used as part of a normal oral hygiene regimen, the efficacy of the Colgate Actibrush was demonstrated to be superior to that of the Colgate Plus Toothbrush after 30 days of use.

  15. The general properties of water - nitrobenzene - crown - bis-1,2-dicarbollylcobaltate extraction systems

    International Nuclear Information System (INIS)

    Vanura, P.

    2003-01-01

    The extraction and stability constants in the system water - nitrobenzene have been collected and general rules valid for water - nitrobenzene - crown - bis-1,2-dicarbollylcobaltate extraction system have been found. The main principles are size compatibility of ion diameter and crown cavity diameters, the flexibility of crown, the basicity of crown and the steric factor of both the ligand and the extracted ion. The extraction in the system water - mineral acid or salt polyoxyethylene compound - bis-1,2-dicarbollylcobaltate - nitrobenzene is more complicated than can be expected from usually used ion diameter - crown cavity diameter compatibility principle. The other important factors are the basicity and the deformability of crown, steric aspect and the angles of bonds of extracted ion. The binuclear 'sandwich' complexes with H + ion and Sr 2+ or Ba 2+ ions have been proved for dibenzo-18-crown-6 (DB18C6). On the other hand, only SrL 2 and BaL 2 (L = 15C5) complexes are formed in nitrobenzene saturated with water. The addition of polyoxyethylene compound usually increases the distribution ratio of alkali earth metal ions and the selectivity of its mutual separation. (authors)

  16. Crown structure of Picea omorika trees in the plantation

    OpenAIRE

    Krstić M.; Stavretović N.; Isajev V.; Bjelanović I.

    2012-01-01

    The study was carried out in Serbian spruce (Picea omorika Panč/Purkynĕ) plantations in the western Serbia. The paper presents results of the analysis of crown development. The following elements were analyzed: total tree height, height of the crown base, absolute and relative crown length, maximal crown diameter, coefficient of crown spreading and degree of crown girth. We discuss approaches to the modeling of tree crown growth and development, growing under favorable environmental and...

  17. Impact of Crown-Implant Ratio of Single Restorations Supported by 6-mm Implants : A Short-Term Case Series Study

    NARCIS (Netherlands)

    Gulje, Felix L.; Raghoebar, Gerry M.; Erkens, Ward A. L.; Meijer, Henny J. A.

    PURPOSE: High crown-implant ratios might affect the biologic and technical performance of a reconstruction. The aim of this study was to assess whether a higher crown-implant ratio of single restorations on 6-mm implants resulted in more peri-implant bone loss and more prosthetic complications

  18. Pericoronal radiolucency associated with incomplete crown

    International Nuclear Information System (INIS)

    Nah, Kyung Soo

    2013-01-01

    The author experienced 8 cases of pericoronal radiolucency involving an incomplete tooth crown that had not developed to form the cemento-enamel junction, and the underdeveloped crown sometimes appeared to be floating within the radiolucency radiographically. The first impression was that these cystic lesions had odontogenic keratocysts, but half of them turned out to be dentigerous cysts histopathologically. There has been no report concerning odontogenic cysts involving an incompletely developed crown. The purpose of this paper is to report that dentigerous cysts may develop before the completion of the cemento-enamel junction of a developing crown.

  19. Pericoronal radiolucency associated with incomplete crown

    Energy Technology Data Exchange (ETDEWEB)

    Nah, Kyung Soo [Dept. of Oral and Maxillofacial Radiology, School of Dentistry, Pusan National University, Yangsan (Korea, Republic of)

    2013-12-15

    The author experienced 8 cases of pericoronal radiolucency involving an incomplete tooth crown that had not developed to form the cemento-enamel junction, and the underdeveloped crown sometimes appeared to be floating within the radiolucency radiographically. The first impression was that these cystic lesions had odontogenic keratocysts, but half of them turned out to be dentigerous cysts histopathologically. There has been no report concerning odontogenic cysts involving an incompletely developed crown. The purpose of this paper is to report that dentigerous cysts may develop before the completion of the cemento-enamel junction of a developing crown.

  20. Fracture resistance of various temporary crown materials.

    Science.gov (United States)

    Yilmaz, Asude; Baydaş, Seyfettin

    2007-01-01

    The aim of this study was to evaluate the fracture resistance of various provisional crown materials using an in vitro model test system. In the present study polycarbonate crowns, prefabricated by the manufacturer (3M Polycarbonate Crown), and the temporary crowns, fabricated in the dental laboratory environment, were fabricated using bis-acryl composite (Protemp II), autopolymerizing PMMA resin (BISICO Temp S), and heat-polymerized PMMA resin (Major C&B-V Dentine). All temporary crowns were stored in distilled water for 24 hours at room temperature prior to testing. The crowns were seated on metal dies, fabricated from Cr-Co alloy (AZ Dental, Konstanz, Germany), and then tested using the indenter of a Hounsfield testing machine (Hounsfield Tensometer, Hounsfield Test Equipment, Raydon, England). The tip of the indenter was located at a position one-third of the way down the inciso-palatine surface at 135 masculine. The data were statistically analyzed for differences using one-way analysis of variance (ANOVA) and the Tukey HSD test (P crowns were significantly different from the BISICO Temp S, Protemp II, and Major C&B-V Dentine (P crowns may be preferable to the other types of temporary crowns used in this study.

  1. All-ceramic crowns: bonding or cementing?

    Science.gov (United States)

    Pospiech, Peter

    2002-12-01

    Despite the wide variety of all-ceramic systems available today, the majority of dental practitioners hesitate to recommend and insert all-ceramic crowns. This article regards the nature of the ceramic materials, the principles of bonding and adhesion, and the clinical problems of the acid-etch technique for crowns. Advantages and disadvantages are discussed, and the influences of different factors on the strength of all-ceramic crowns are presented. Finally, the conclusion is drawn that conventional cementing of all-ceramic crowns is possible when the specific properties of the ceramics are taken into consideration.

  2. The clinical success of zirconia-based crowns: a systematic review.

    Science.gov (United States)

    Larsson, Christel; Wennerberg, Ann

    2014-01-01

    This review aimed to evaluate the documented clinical success of zirconia based crowns in clinical trials. Electronic databases were searched for original studies reporting on the clinical performance of tooth- or implant-supported zirconia-based crowns, including PubMed, Cochrane Library, and Science Direct. The electronic search was complemented by manual searches of the bibliographies of all retrieved full-text articles and reviews as well as a hand search of the following journals: International Journal of Prosthodontics, Journal of Oral Rehabilitation, International Journal of Oral & Maxillofacial Implants, and Clinical Oral Implants Research. The search yielded 3,216 titles. Based on preestablished criteria, 42 full-text articles were obtained. While 16 studies fulfilled the inclusion criteria, only 3 randomized controlled trials were reported. Seven studies reported on tooth-supported and 4 on implant-supported crowns, and 5 studies reported on both types of support. Ten studies on tooth-supported and 7 on implant supported crowns provided sufficient material for statistical analysis. Life table analysis revealed cumulative 5-year survival rates of 95.9% for tooth-supported and 97.1% for implant-supported crowns. For implant-supported crowns, the most common reasons for failure were technical (veneering material fractures). For tooth-supported crowns, technical (veneering material fractures, loss of retention) and biologic (endodontic/ periodontic) reasons for failure were equally common. The most common complications for implant-supported crowns were veneering material fractures and bleeding on probing. For tooth-supported crowns, the most common complications were loss of retention, endodontic treatment, veneering material fractures, and bleeding on probing. The results suggest that the success rate of tooth-supported and implant-supported zirconia-based crowns is adequate, similar, and comparable to that of conventional porcelain-fused-to-metal crowns

  3. Incorporating crown dimensions into stem height and basal area for ...

    African Journals Online (AJOL)

    Four crown dimensions (crown diameter, crown projection area, crown length and crown ratio) were each incorporated into nonlinear individual tree total height and basal area increment models for African white wood (Triplochiton scleroxylon K. Schum). The basic height/basal area growth model was formulated as a ...

  4. Equations for predicting uncompacted crown ratio based on compacted crown ratio and tree attributes.

    Science.gov (United States)

    Vicente J. Monleon; David Azuma; Donald. Gedney

    2004-01-01

    Equations to predict uncompacted crown ratio as a function of compacted crown ratio, tree diameter, and tree height are developed for the main tree species in Oregon, Washington, and California using data from the Forest Health Monitoring Program, USDA Forest Service. The uncompacted crown ratio was modeled with a logistic function and fitted using weighted, nonlinear...

  5. Immediate maxillary lateral incisor implants with nonocclusal loading provisional crowns.

    Science.gov (United States)

    Peñarrocha, Miguel; Lamas, Joana; Peñarrocha, Maria; Garcia, Berta

    2008-01-01

    This clinical report series describes a treatment modality involving immediately placed dental implants in maxillary lateral incisor sites using noncemented immediate provisional crowns retained with calcinable copings (prosthetic complement used in preparing the metal for the definitive prosthesis). Ten implants were placed in eight patients for the replacement of maxillary lateral incisors: two immediate and eight corresponding to cases of agenesis. All were subjected to immediate rehabilitation with provisional acrylic resin crowns in nonocclusal loading. One implant failed 3 weeks after placement due to acute local trauma. The other nine remained functional within the mouth, with normal clinical and radiological characteristics after a minimum of 12-month follow-up. Immediate placement of implant fixed provisional restorations retained by friction in maxillary lateral incisors offers an esthetic solution, eliminates the need for a removable provisional restoration, and avoids implant failures associated with excess cement or screw loosening. Moreover, in the case of extractions, immediate placement and provisionalization of implants in maxillary lateral incisors can effectively optimize the peri-implant esthetic results by maintaining the existing hard and soft tissue architecture of the replaced tooth. As no cement or screws are required, and the provisional crowns are placed in nonocclusal loading, the risk of complications is minimized.

  6. Postpartum complications

    International Nuclear Information System (INIS)

    Kronthal, A.J.; Kuhlman, J.E.; Fishman, E.K.

    1990-01-01

    This paper reports the CT findings of major postpartum complications and determine what role CT plays in their evaluation. The CT scans of nine patients with major postpartum complications were retrospectively reviewed. Patients had been referred to CT for evaluation of postpartum fever, abdominal pain, and elevated results of liver function tests. Complications identified at CT included hepatic infarctions (n = 2), endometritis (n = 2), postoperative wound abscess (n = 1), massive abdominal hemorrhage (n = 1), septic thrombophlebitis (n = 1), and renal vein thrombosis (n = 1). CT findings of hepatic infarction included wedge-shaped areas of decreased enhancement conforming to a vascular distribution

  7. Implant survival and crestal bone loss around extra-short implants supporting a fixed denture: the effect of crown height space, crown-to-implant ratio, and offset placement of the prosthesis.

    Science.gov (United States)

    Anitua, Eduardo; Alkhraist, Mohammad Hamdan; Piñas, Laura; Begoña, Leire; Orive, Gorka

    2014-01-01

    To determine the effect of crown height space, crown-to-implant ratio, and offset placement of a prosthesis on implant survival, crestal bone loss, and prosthetic complications; and to determine whether detrimental values for crown height space and crown-to-implant ratio exist for implant-supported restorations. Extra-short implants (length ≤6.5 mm) supporting a fixed denture in the posterior mandible and followed for at least 12 months were analyzed. Radiographic and clinical examinations were conducted to retrieve data about patients' dental and medical history, prosthetic complications, antagonist type, crown height space, crown-to-implant ratio, offset placement of the prosthesis, crestal bone loss, and implant failure. Thirty-four patients (mean age, 60 ± 10 years) with 45 extra-short implants participated in this study. Patients were followed for up to 4 years (mean, 2 years) and no implants were lost. The mean crown-to-implant ratio was 2.4 (range, 1.5 to 3.69). Mean crown height space was 17.05 ± 3.05 mm, and 65.4% of the implants had a crown height space in the range of 15 to 20 mm. About 90% of the implants had a distal or mesial offset placement greater than 1 mm. The type of antagonist significantly affected marginal bone loss around extra-short implants: bone loss was greatest for implants opposing a partial denture (mean, 1.28 ± 1.09 mm) and was lower for implants opposing a natural dentition (mean, 0.73 ± 0.60 mm) or a complete denture (mean, 0.89 ± 0.60 mm). Analysis of marginal bone loss and the factors crown-to-implant ratio, crown height space, and offset placement according to antagonist dentition indicated a significant positive correlation only between bone loss and crown height space. When an increased crown-to-implant ratio is present, crown height space may influence crestal bone loss more significantly.

  8. Prospective assessment of CAD/CAM zirconia abutment and lithium disilicate crown restorations: 2.4 year results.

    Science.gov (United States)

    Cooper, Lyndon F; Stanford, Clark; Feine, Jocelyne; McGuire, Michael

    2016-07-01

    Single-tooth implant restorations are commonly used to replace anterior maxillary teeth. The esthetic, functional, and biologic outcomes are, in part, a function of the abutment and crown. The purpose of this clinical study was to describe the implant, abutment, and crown survival and complication rates for CAD/CAM zirconia abutment and lithium disilicate crown restorations for single-tooth implants. As part of a broader prospective investigation that enrolled and treated 141 participants comparing tissue responses at the conical interface (CI; AstraTech OsseoSpeed), flat-to-flat interface (FI; NobelSpeedy), and platform-switch interface (PS; NanoTite Certain Prevail) of single-tooth implants, computer-aided design and computer-aided manufacturing (CAD/CAM) zirconia abutments (ATLANTIS Abutment) and cemented lithium disilicate (e.max) crowns were used in the restoration of all implants. After 2.4 years in function (3 years after implant placement), the implant, abutment, and crown of 110 participants were evaluated. Technical and biologic complications were recorded. Demographic results were tabulated as percentages with mean values and standard deviations. Abutment survival was calculated with the Kaplan-Meier method. After 2.4 years, no abutments or crowns had been lost. Abutment complications (screw loosening, screw fracture, fracture) were absent for all 3 implant groups. Crown complications were limited to 2 crowns debonding and 1 with excess cement (2.5%). Five biological complications (4.0%) were recorded. The overall complication rate was 6.5%. CAD/CAM zirconia abutments restored with cemented lithium disilicate crowns demonstrated high survival on 3 different implant-abutment interface designs. No abutment or abutment screw fracture occurred. The technical complications observed after 2.4 years were minor and reversible. The use of CAD/CAM zirconia abutments with cemented lithium disilicate crowns is associated with high technical and biologic success at 2

  9. Diphtheria Complications

    Science.gov (United States)

    ... Search Form Controls Cancel Submit Search The CDC Diphtheria Note: Javascript is disabled or is not supported ... message, please visit this page: About CDC.gov . Diphtheria Home About Diphtheria Causes and Transmission Symptoms Complications ...

  10. Complicated Pancreatitis

    NARCIS (Netherlands)

    Bakker, O.J.

    2015-01-01

    Research questions addressed in this thesis: What is the accuracy of serum blood urea nitrogen as early predictor of complicated pancreatitis? ; What is difference in clinical outcome between patients with pancreatic parenchymal necrosis and patients with extrapancreatic necrosis without necrosis

  11. FRACTURE-RESISTANT MONOLITHIC DENTAL CROWNS

    Science.gov (United States)

    Zhang, Yu; Mai, Zhisong; Barani, Amir; Bush, Mark; Lawn, Brian

    2016-01-01

    Objective To quantify the splitting resistance of monolithic zirconia, lithium disilicate and nanoparticle-composite dental crowns. Methods Fracture experiments were conducted on anatomically-correct monolithic crown structures cemented to standard dental composite dies, by axial loading of a hard sphere placed between the cusps. The structures were observed in situ during fracture testing, and critical loads to split the structures were measured. Extended finite element modeling (XFEM), with provision for step-by-step extension of embedded cracks, was employed to simulate full failure evolution. Results Experimental measurements and XFEM predictions were self consistent within data scatter. In conjunction with a fracture mechanics equation for critical splitting load, the data were used to predict load-sustaining capacity for crowns on actual dentin substrates and for loading with a sphere of different size. Stages of crack propagation within the crown and support substrate were quantified. Zirconia crowns showed the highest fracture loads, lithium disilicate intermediate, and dental nanocomposite lowest. Dental nanocomposite crowns have comparable fracture resistance to natural enamel. Significance The results confirm that monolithic crowns are able to sustain high bite forces. The analysis indicates what material and geometrical properties are important in optimizing crown performance and longevity. PMID:26792623

  12. Fracture-resistant monolithic dental crowns.

    Science.gov (United States)

    Zhang, Yu; Mai, Zhisong; Barani, Amir; Bush, Mark; Lawn, Brian

    2016-03-01

    To quantify the splitting resistance of monolithic zirconia, lithium disilicate and nanoparticle-composite dental crowns. Fracture experiments were conducted on anatomically-correct monolithic crown structures cemented to standard dental composite dies, by axial loading of a hard sphere placed between the cusps. The structures were observed in situ during fracture testing, and critical loads to split the structures were measured. Extended finite element modeling (XFEM), with provision for step-by-step extension of embedded cracks, was employed to simulate full failure evolution. Experimental measurements and XFEM predictions were self-consistent within data scatter. In conjunction with a fracture mechanics equation for critical splitting load, the data were used to predict load-sustaining capacity for crowns on actual dentin substrates and for loading with a sphere of different size. Stages of crack propagation within the crown and support substrate were quantified. Zirconia crowns showed the highest fracture loads, lithium disilicate intermediate, and dental nanocomposite lowest. Dental nanocomposite crowns have comparable fracture resistance to natural enamel. The results confirm that monolithic crowns are able to sustain high bite forces. The analysis indicates what material and geometrical properties are important in optimizing crown performance and longevity. Copyright © 2015 Academy of Dental Materials. All rights reserved.

  13. Fracture resistance of zirconia-composite veneered crowns in comparison with zirconia-porcelain crowns.

    Science.gov (United States)

    Alsadon, Omar; Patrick, David; Johnson, Anthony; Pollington, Sarah; Wood, Duncan

    2017-05-31

    The objectives were to evaluate the fracture resistance and stress concentration in zirconia/composite veneered crowns in comparison to zirconia/porcelain crowns using occlusal fracture resistance and by stress analysis using finite element analysis method. Zirconia substructures were divided into two groups based on the veneering material. A static load was applied occlusally using a ball indenter and the load to fracture was recorded in Newtons (N). The same crown design was used to create 3D crown models and evaluated using FEA. The zirconia/composite crowns subjected to static occlusal load showed comparable results to the zirconia/porcelain crowns. Zirconia/composite crowns showed higher stress on the zirconia substructure at 63.6 and 50.9 MPa on the zirconia substructure veneered with porcelain. In conclusion, zirconia/composite crowns withstood high occlusal loads similar to zirconia/porcelain crowns with no significant difference. However, the zirconia/composite crowns showed higher stress values than the zirconia/porcelain crowns at the zirconia substructure.

  14. Comparison of internal fit between implant abutments and cast metal crowns vs laser-sintered crowns.

    Science.gov (United States)

    Kiliçarslan, Mehmet Ali; Özkan, Pelin; Uludag, Bülent; Mumcu, Emre

    2014-07-01

    A common problem related to cemented single crowns is the internal misfit, which may cause inadequate retention, especially when seated on the implant abutment. The aim of this study was to compare the internal fit of Co-Cr crowns using a traditional lost-wax casting technique from laser-sintered Co-Cr alloy crowns. Twelve metallic crowns per each technique were fabricated. The effect of the thickness of cement, originated internal gap was evaluated. Crowns were cemented on the implant abutments with resin cement, and the internal fit of crowns was measured at five areas with an optical microscope. The data were analyzed, and the means were compared with a t-test (pcrowns obtained through the lost wax method (min. 65.50 ± 9.54 μm and max. 313.46 ± 48.12 μm). The fit of the metal crown likely varies with the fabrication technique. The use of techniques that enable the adjustment of crown parameters, such as the laser sintering technique, maintains the desired fit between casting and implant abutments. This study investigated which technique affects the internal fit of cemented implant-supported crowns, comparing the use of lost wax casting and laser-sintered metal dental alloys. The results of this study indicate that the use of laser-sintered crowns can improve for crown accuracy.

  15. Lava zirconia crowns and bridges.

    Science.gov (United States)

    Suttor, D

    2004-01-01

    Ceramic restorations--suitable for the anterior as well as the posterior region, simultaneously satisfying the demand for high strength, longevity, and esthetics--are an increasingly important field for the dental professional. Because of its outstanding mechanical properties and esthetics with a proven track record in other industrial areas, zirconium oxide (zirconia) is emerging in the dental industry. As the manufacturing method of choice, CAD/CAM is important for the dental laboratory; however, in the final analysis, the primary focus will be on the material properties and the clinical performance of the result of the CAD/CAM process--in this case, zirconia crowns and bridges. This is especially true since some concepts do not require the acquisition of a CAD/CAM system at all.

  16. Fracture resistance of different primary anterior esthetic crowns

    OpenAIRE

    Al Shobber, Manar Zaki; Alkhadra, Thamer A.

    2017-01-01

    Purpose: Investigate and compare fracture resistance of four commercially available esthetic crowns. Methods: Sixty-four anterior crowns were used: NuSmile Primary crowns (NuSmile, Houston, Tex. USA) (16); Preveneered Cheng Crowns, (Orthodontic Technologies Inc., Houston, TX) (16); NuSmile ZR (NuSmile, Houston, Tex. USA); and Cheng Crowns zirconia (Orthodontic Technologies Inc., Houston, TX). Crowns were mounted and cemented on a negative replica and placed under servo hydraulic mechanical...

  17. A 2-year Retrospective Clinical study of Enamic Crowns Performed in a Private Practice Setting.

    Science.gov (United States)

    Chirumamilla, Geetika; Goldstein, Cary E; Lawson, Nathaniel C

    2016-07-01

    To evaluate the clinical performance and survival of Enamic crowns placed in a prosthodontic dental practice. Thirty-five patients and 45 crowns were included in the study. At 1-year recall appointments, the restorations were examined for survival. At the 2-year recall appointment, all restorations were clinically evaluated by an independent evaluator for CDA clinical criteria. Kaplan-Meier method and a log-rank test were used to compare the survival of the restorations placed with resin and resin-modified glass ionomer (RMGI) cements. Out of the 45 crowns that were followed, 2 were lost to follow-up by 1 year and 7 were lost to follow-up by 2 years. Severe complications were observed in 2 teeth by the 2-year follow-up and were recorded as failures due to recurrent decay, and an internal crack in the abutment tooth. There was no difference between the survival probability for crowns cemented with resin cement (96.8%) and with RMGI cements (92.9%) (p = 0.42), however, 1 out of the 14 crowns cemented with RMGI cement debonded. The crowns were evaluated according the CDA criteria with over 90% alfa scores for all categories aside from surface texture (86% alfa). The estimated 2-year survival of Enamic crowns is >90%. Based on the preliminary 2-year results achieved in a clinical practice, Enamic is a suitable material for full-coverage single-unit crowns. Further studies are necessary to evaluate the long term success. (J Esthet Restor Dent 28:231-237, 2016). © 2016 Wiley Periodicals, Inc.

  18. [Long-term treatment outcome and influencing factors of teeth receiving modified crown lengthening].

    Science.gov (United States)

    Wang, C; Jia, X T; Hu, W J; Zhen, M; Zhang, H

    2017-03-09

    Objective: To observe the long-term clinical treatment outcome and the influencing factors of the outcome for the teeth receiving modified crown lengthening surgery combined with root canal treatment and post-core crown restoration. To summarize the clinical guidelines of modified crown lengthening surgery in selection of indications and for mulation of treatment planning. Methods: Fifty-seven patients with a total of 67 teeth receiving modified crown lengthening surgery combined with root canal treatment and post-core crown restoration for at least a 6 months' follow-up period between July 2004 and July 2013 were recruited in this retrospective study by phone call interviews. The patients' clinical outcomes were evaluated by the combination of clinical examination, radiograph and questionnaire regarding patient-reported outcome of the last follow up (≥9 months post modified crown lengthening surgery and ≥6 months after definite crown restorations). All of the treated teeth were classified into two groups, group A (teeth with good clinical treatment outcome) and group B (teeth with poor clinical treatment outcome), based on the defined criteria including patients' satisfaction with the function and esthetics of the teeth and absence of periodontal, endodontic and prosthodontic complications. The potential influencing factors of clinical treatment outcome were also determined by Logistic regression analysis. Results: Vertical root fracture in 1 tooth was found on its periapical film and the tooth was deemed hopeless. Thus, the survival rate is 99% (66/67) for the multidisciplinary treatment approach. Seventy-two percent (48/67) of the teeth achieved good clinical treatment outcome and 28% (19/67) of the teeth developed one or several complications. In group B (teeth with poor clinical treatment), 16 out of teeth exhibited periodontal complications with bleeding on probing (BOP) positive mostly found. Logistic regression analysis demonstrated that plaque control

  19. Single crowns with CAD/CAM-fabricated copings from titanium: 6-year clinical results.

    Science.gov (United States)

    Hey, Jeremias; Beuer, Florian; Bensel, Tobias; Boeckler, Arne F

    2014-08-01

    Computer-aided design/computer-aided manufacturing (CAD/CAM) titanium ceramic restorations were developed with the potential for replacing expensive, high noble metal ceramic restorations. However, little information exists about the clinical performance of CAD/CAM titanium ceramic single crowns. The purpose of this study was to evaluate CAD/CAM titanium ceramic single crowns after 6 years in function. A total of 41 crowns were fabricated for 21 patients. The titanium copings were CAD/CAM milled (Everest CAD/CAM system), with an even thickness of 0.5 mm and veneered with low-fusing porcelain (Vita Titanium Porcelain) in the powder-build-up technique. All the crowns were cemented with zinc phosphate. The participants were recalled at 12, 24, 36, 48, 60, and 72 months after cementation to document any mechanical and biologic complications and to measure the periodontal parameters, such as probing depth, bleeding on probing, and the plaque index. The success and survival rates were calculated according to the Kaplan-Meier analysis. After 6 years of clinical service, 12 mechanical complications and 1 biologic complication were found, which resulted in a success rate of 67.8%. The cumulative survival rate of the crowns was 91.3% after 6 years. At the end of the follow-up period, the probing depth was 3.21 mm, the percentile of surface with bleeding on probing was 25, and the plaque index was 0.37. No secondary caries or decementation was detected during the 6-year observation period. The clinical performance of the CAD/CAM titanium-ceramic crowns after 6 years was poor because of veneering porcelain problems. Recent CAD software with tools to design proper copings might improve the clinical success. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  20. Marginal Strength of Collarless Metal Ceramic Crown

    Directory of Open Access Journals (Sweden)

    Sikka Swati

    2010-01-01

    fracture strength at margins of metal ceramic crowns cemented to metal tooth analogs. Crowns evaluated with different marginal configurations, shoulder and shoulder bevel with 0 mm, 0.5 mm, 1 mm, and 1.5 mm, were selected. Methods. Maxillary right canine typhodont tooth was prepared to receive a metal ceramic crown with shoulder margin. This was duplicated to get 20 metal teeth analogs. Then the same tooth was reprepared to get shoulder bevel configuration. These crowns were then cemented onmetal teeth analogs and tested for fracture strength atmargin on an Instron testing machine. A progressive compressive load was applied using 6.3 mm diameter rod with crosshead speed of 2.5 mm per minute. Statisticaly analysis was performed with ANOVA, Student's “t” test and “f” test. Results. The fracture strength of collarless metal ceramic crowns under study exceeded the normal biting force. Therefore it can be suggested that collarless metal ceramic crowns with shoulder or shoulder bevel margins up to 1.5 mm framework reduction may be indicated for anteriormetal ceramic restorations. Significance. k Collarless metal ceramic crowns have proved to be successful for anterior fixed restorations. Hence, it may be subjected to more clinical trials.

  1. Colorimetric values of esthetic stainless steel crowns.

    Science.gov (United States)

    Hosoya, Yumiko; Omachi, Koichi; Staninec, Michal

    2002-01-01

    The colorimetric values of two different kinds of esthetic stainless steel crowns were measured and compared with the colorimetric values of primary anterior teeth in Japanese children. The colorimetric values of resin composite-faced stainless steel crowns (Kinder Krown) and epoxy-coated stainless steel crowns (White Steel Crown) were measured with a color difference meter. The Commission Internationale de Eclairage L*, a*, b*, and delta E*ab values and Munsell value, chroma, and hue were calculated. The data were compared with previously reported colorimetric values of Japanese primary anterior teeth measured with the same color difference meter used in this study. Compared to Japanese primary anterior teeth, Kinder Krown Pedo I and Pedo II showed much higher L* values and lower hue; on the other hand, White Steel Crown showed much higher L*, a*, b* values, much higher value and chroma, and much lower hue. Color analysis revealed that the colors of the White Steel Crown and Kinder Krown Pedo I were substantially different from the color of Japanese primary anterior teeth. The color difference between Pedo II crowns and Japanese primary anterior teeth was relatively high, but the color of Pedo II might be acceptable for clinical use.

  2. Retention and surface changes of zirconia primary crowns with secondary crowns of different materials.

    Science.gov (United States)

    Turp, Işıl; Bozdağ, Ergün; Sünbüloğlu, Emin; Kahruman, Cem; Yusufoğlu, Ibrahim; Bayraktar, Gülsen

    2014-11-01

    To evaluate zirconia as a substitute for gold alloy in primary crowns facing secondary crowns manufactured with different materials, in terms of long-term retention force changes, wear, and phase transformation was aimed. A total of 12 groups, each containing six samples, consisting of gold alloy primary crown-electroformed gold secondary crowns (AA), zirconia primary crown-electroformed gold secondary crowns (ZA) and zirconia primary crown-casted non-precious alloy secondary crowns (ZC) with conus angles of 0°, 2°, 4°, and 6° were evaluated. Samples were subjected to 10,000 insertion-separation cycles in artificial saliva and retention force was measured. X-ray diffraction and scanning electron microscope analysis were performed on the sample surfaces. The highest retention forces were obtained from ZC-0° group (72.09-71.26 N) and the lowest were obtained from ZA-4° (12.73-19.44 N) and ZA-6° (5.36-19.73 N) groups in the beginning and after 10,000 cycles, respectively. Retention force increased as the conus angle decreased. The monoclinic phase ratio of the zirconia primary crowns decreased after the experiments. No wear was observed in zirconia primary crowns except for the ZC-0° and ZC-2° groups. The use of zirconia primary crowns resulted in a less excursive retention force. A more predictable and less excursive retention force can be obtained using a hard and rigid primary crown material like zirconia. Despite a lack of knowledge about the aging of zirconia without a veneer layer in the oral environment, zirconia primary crowns are more advantageous in terms of retention force development and wear.

  3. Veneered zirconia crowns as abutment teeth for partial removable dental prostheses: a clinical 4-year retrospective study.

    Science.gov (United States)

    Pihlaja, Juha; Näpänkangas, Ritva; Kuoppala, Ritva; Raustia, Aune

    2015-11-01

    The mechanical properties of zirconia suggest that it might serve as a material for abutment crowns for partial removable dental prostheses (RDPs). Only limited clinical evidence is available for the use of ceramics as abutment crowns. The purpose of this retrospective clinical study was to evaluate the outcome of veneered zirconia single crowns in abutment teeth for RPDs in participants treated by predoctoral students. Thirty-seven veneered zirconia single crowns in 17 participants (9 men and 8 women; mean age 62.5 years) were prepared as abutment teeth for a clasp-retained RDP with a metal framework: 22 crowns with an occlusal rest seat and 15 crowns with both an occlusal rest seat and retentive clasps. The mean follow-up time was 4.2 years (2.9 to 5.4 years). In a clinical examination, the anatomic form of the crown, marginal fidelity (the border between the crown and the tooth was felt with an explorer), wear of the ceramic surface in the rest seat, and fracture of the veneering porcelain were examined and assessed as good, acceptable, or unacceptable. The retention and stability of the RDPs were recorded as good, moderate, or poor. The complications found were fracture of the veneering porcelain (11%) and fracture of the occlusal rest seat (3%). Wear of porcelain at the occlusal contact point was found in 24% of the zirconia single crowns. Wear of the ceramic surfaces of the rest seats for the RDPs was not found. The retention was good in all RDPs. The stability was good in 73% and moderate in 23% of the RDPs. Veneered zirconia single crowns are suitable in abutment teeth for RDPs with a metal framework. Fracture in the veneering porcelain remains a problem with veneered zirconia, although the zirconia surface in the rest seats for RDPs showed no wear. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  4. Aesthetic treatment on anterior teeth crown fracture caused by dental trauma

    Directory of Open Access Journals (Sweden)

    Nanik Zubaidah

    2012-12-01

    Full Text Available Background: Complicated crown fracture is a tooth fracture that involve enamel, dentine and pulp. The incidence of complicated crown fracture ranges from 2% to 13% of all dental injuries and the most commonly involved teeth are the maxillary central incisors. Various treatment modalities are available depending on the clinical, physiological and radiographic examination of the involved teeth. Purpose: The aim of this case report is to present the management of crown fractures with pulpal exposure caused by traumatic injury, through endorestoration approach to reconstruct the shape and function of the teeth. Case: A 17 years old male with complicated crown fractures of anterior teeth #11 #21 and #22. The patient wish for aesthetic dental treatment in both of its form and function. Case management: Crown fractures of anterior teeth with exposed pulp caused by traumatic injury were reconstructed by endorestoration approach. The endodontic treatment with post and core insertion in the root canal which will increase its retention and porcelain fused to metal crown which will aesthetically recover its original form and function. After restoration the patient feel very glad and confident with the result. Conclusion: Endorestoration treatment on anterior teeth with complicated crown fractures and exposed pulp is able to recover the normal form, function and dental aesthetic in accordance with stomatognatic system and self confidence.Latar belakang: Fraktur mahkota kompleks (complicated adalah fraktur pada mahkota gigi yang melibatkan enamel, dentin dan pulpa. Kejadian dari fraktur mahkota kompleks bervariasi antara 2-13% dari semua trauma gigi dan sebagian besar gigi yang terkena adalah gigi insisif pertama rahang atas. Berbagai macam cara perawatan yang dilakukan tergantung pada hasil pemeriksaan klinis, psikologis dan radiografis dari gigi yang terkena. Tujuan: Laporan kasus ini menjelaskan penatalaksanaan fraktur mahkota gigi dengan pulpa terbuka

  5. Internal fit evaluation of crowns prepared using a new dental crown fabrication technique: laser-sintered Co-Cr crowns.

    Science.gov (United States)

    Ucar, Yurdanur; Akova, Tolga; Akyil, Musa S; Brantley, William A

    2009-10-01

    Difficulties encountered during casting of base metal dental alloys limit their use. Application of these alloys might be enhanced if new techniques are used. The purpose of this study was to compare the internal fit of laser-sintered Co-Cr alloy crowns with base metal restorations prepared from another Co-Cr alloy and a Ni-Cr alloy using conventional casting techniques. Internal fit of laser-sintered Co-Cr crowns was compared with the fit of conventionally cast Ni-Cr and Co-Cr alloy crowns. Twelve crown-shaped specimens were prepared on a stainless steel die representing a prepared maxillary right central incisor for each group. Fit of crowns was evaluated using 2 different techniques: (1) weighing the light-body addition silicone that simulated a cement material, and (2) measuring the internal gap width on a die for longitudinally sectioned specimens. One-way ANOVA followed by Tukey multiple comparison test was used for statistical analysis (alpha=.05). Significantly higher mean (SD) light-body silicone weights (Pcrowns. However, no significant difference was found among the 3 alloy groups evaluated for the internal gap width of sectioned crown specimens.

  6. Unusual Bilateral Paramolars Associated with Clinical Complications

    Directory of Open Access Journals (Sweden)

    A. N. Sulabha

    2015-01-01

    Full Text Available Paramolars are rare supernumerary structures of maxillofacial complex that occur buccally or lingually near the molar row. Predominantly these occur singly; bilateral presentation is very rare. This paper reports two unusual bilateral presentations of paramolars with clinical complication and its management. One of the cases in the present paper also documents the cooccurrence of bilateral paramolars and microdontia of single tooth and one of its paramolars presented with multilobed crown with an anomalous buccal tubercle.

  7. Unusual Bilateral Paramolars Associated with Clinical Complications

    Science.gov (United States)

    Sulabha, A. N.; Sameer, C.

    2015-01-01

    Paramolars are rare supernumerary structures of maxillofacial complex that occur buccally or lingually near the molar row. Predominantly these occur singly; bilateral presentation is very rare. This paper reports two unusual bilateral presentations of paramolars with clinical complication and its management. One of the cases in the present paper also documents the cooccurrence of bilateral paramolars and microdontia of single tooth and one of its paramolars presented with multilobed crown with an anomalous buccal tubercle. PMID:26078890

  8. Fracture resistance of zirconia-composite veneered crowns in comparison with zirconia-porcelain crowns.

    OpenAIRE

    Alsadon, O.; Patrick, D.; Johnson, A.; Pollington, S.; Wood, D.

    2017-01-01

    The objectives were to evaluate the fracture resistance and stress concentration in zirconia/composite veneered crowns in comparison to zirconia/porcelain crowns using occlusal fracture resistance and by stress analysis using finite element analysis method. Zirconia substructures were divided into two groups based on the veneering material. A static load was applied occlusally using a ball indenter and the load to fracture was recorded in Newtons (N). The same crown design was used to create ...

  9. Activity relationships for aromatic crown ethers

    CERN Document Server

    Wilson, M J

    1998-01-01

    This thesis involves an investigation of aromatic crown ethers and a study of their binding constants for alkali metals. The study was motivated by the current needs of the semiconductor industry to improve the scavenging of mobile ions from fabricated circuits. A number of aromatic crown ethers have been sulphonated in an attempt to improve their water solubility and cation binding activity. These materials have been extensively studied and their binding activity determined. In collaboration with a molecular modelling study, the effect of ionisable sulphonate groups on the macrocycles' behaviour has been investigated. The broader issue of the effect of substituents in aromatic crown ethers has also been studied with the preparation of a wide range of substituted crown ethers. The cation binding activity of these materials has been found to bear a simple relationship to the electron withdrawing nature of the aromatic substituents. This relationship can be accurately monitored using electronic charge densities...

  10. Multidisciplinary management of subgingival crown-root fracture of an immature permanent maxillary central incisor

    Directory of Open Access Journals (Sweden)

    Samir Zahedpasha

    2012-01-01

    Full Text Available This case report describes the multidisciplinary management of subgingival horizontal crown-root fracture of an immature permanent maxillary central incisor in a 10-year-old boy. After removal of the fractured fragment, pulpotomy was performed within 48 h from the injury to promote apexogenesis. The tooth was orthodontically extruded until the fracture line was located above the alveolar bone level. Frenectomy, supracrestal fiberotomy, and crown lengthening were performed after adequate stabilization of the extruded tooth for 5 months. Finally, the tooth was restored with composite resin by using the acid etch technique. This report highlights that a multidisciplinary treatment approach with strict cooperation among specialists to manage a complicated crown-root fracture can save and restore a traumatized immature permanent tooth.

  11. Methods for evaluating crown area profiles of forest stands

    Science.gov (United States)

    Dubrasich, Michael E.; Hann, D.W.; Tappeiner, J. C.

    1997-01-01

    Canopy architectures of five structurally complex forest stands and three structurally simple forest stands in southwest Oregon and the Willamette Valley, Oregon, were evaluated and quantified through crown area profiles. Mixed conifer and mixed conifer hardwood stands across a range of sites were sampled for crown widths and heights. Crown width and shape equations were derived and used to quantify the stand crown area at incremental heights above the forest floor. Crown area profiles describe the spatial arrangement of aboveground forest vegetation and the total pore spaces between crowns. Plot by plot profiles were combined to produce vertical and horizontal displays of the stand crown area distribution. In complex stands, the forest space was moderately occupied by crowns from the forest floor up to heights over 30 m, producing uniform distributions of between-crown porosity. The structurally complex stands had between-crown porosity values of 70% to 90% for more than 23 vertical metres of canopy, and they had total between-crown porosities of 86% to 91%. The structurally simple stands had between-crown porosity values of 70% to 90% for less than 8 vertical metres of canopy, and they had total between-crown porosities of 69% to 85%. Variances in crown area indicate that variation in horizontal crown area (within heights) was larger in complex stands than in simple stands, but vertical crown areas (between heights) varied less in complex stands. The study provides a basis for discriminating between canopy architectures and for quantifying the porosity of forest canopies.

  12. Experimental and numerical modeling of shrub crown fire initiation

    Science.gov (United States)

    Watcharapong Tachajapong; Jesse Lozano; Shakar Mahalingam; Xiangyang Zhou; David Weise

    2009-01-01

    The transition of fire from dry surface fuels to wet shrub crown fuels was studied using laboratory experiments and a simple physical model to gain a better understanding of the transition process. In the experiments, we investigated the effects of varying vertical distances between surface and crown fuels (crown base height), and of the wind speed on crown fire...

  13. Retrievability of implant-supported crowns when using three different cements: a controlled clinical trial.

    Science.gov (United States)

    Worni, Andreas; Gholami, Hadi; Marchand, Laurent; Katsoulis, Joannis; Mericske-Stern, Regina; Enkling, Norbert

    2015-01-01

    The purpose of this study was to analyze the removal of implant-supported crowns retained by three different cements using an air-accelerated crown remover and to evaluate the patients' response to the procedure. This controlled clinical trial was conducted with 21 patients (10 women, 11 men; mean age: 51 ± 10.2 years) who had received a total of 74 implants (all placed in the posterior zone of the mandible). Four months after implant surgery, the crowns were cemented on standard titanium abutments of different heights. Three different cements (two temporary: Harvard TEMP and Improv; and one definitive: Durelon) were used and randomly assigned to the patients. Eight months later, one blinded investigator removed all crowns. The number of activations of the instrument (CORONAflex, KaVo) required for crown removal was recorded. The patients completed a questionnaire retrospectively to determine the impact of the procedure and to gauge their subjective perception. A linear regression model and descriptive statistics were used for data analysis. All crowns could be retrieved without any technical complications or damage. Both abutment height (P = .019) and cement type (P = .004) had a significant effect on the number of activations, but the type of cement was more important. An increased total number of activations had no or only a weak correlation to the patients' perception of concussion, noise, pain, and unwillingness to use the device. Cemented implant crowns can be removed, and the application of an air-accelerated device is a practicable method. A type of cement with appropriate retention force has to be selected. The impact on the patients' subjective perception should be taken into account.

  14. Long-term clinical performance of esthetic primary molar crowns.

    Science.gov (United States)

    Ram, Diana; Fuks, Anna B; Eidelman, Eliecer

    2003-01-01

    The aim of the study was to report the long-term clinical performance of esthetic primary molar crowns and compare them to that of stainless steel crowns (SSC). Twenty crowns (10 conventional and 10 esthetic) placed in 10 children who had participated in a previously reported study, were assessed again after 4 years. The crowns were evaluated clinically and radiographically according to the following parameters: gingival health, marginal extension, crown adequacy, proper occlusion, proximal contact, chipping of the facing (for esthetic crowns only), and cement removal. At the 4 year evaluation, all the esthetic crowns showed chipping of the facing. No difference was found for marginal extension, occlusion, crown adequacy and periodontal health between SSCs and the esthetic crowns. After 4 years, all the esthetic crowns presented chipping of the facing and, consequently, a very poor esthetic appearance.

  15. Comparative Efficacy of a Soft Toothbrush with Tapered-tip Bristles and an ADA Reference Toothbrush on Established Gingivitis and Supragingival Plaque over a 12-Week Period.

    Science.gov (United States)

    Gallob, John; Petrone, Dolores M; Mateo, Luis R; Chaknis, Patricia; Morrison, Boyce M; Williams, Malcolm; Panagakos, Foti

    2016-06-01

    Evaluation of the efficacy of a soft toothbrush with tapered-tip bristles (Test Toothbrush) and an ADA reference soft toothbrush (ADA Toothbrush) on established gingivitis and supragingival plaque over a 12-week period. This randomized, single-center, examiner-blind, two-cell, parallel clinical research study assessed plaque removal by the comparison of pre- to- post-brushing after a single use, and again after six- and 12-weeks' use, using the Quigley-Hein Plaque Index, Turesky Modification. The study also assessed gingivitis after six weeks and 12 weeks using the Löe & Silness Gingival Index. Adult male and female subjects from the Central New Jersey, USA area refrained from all oral hygiene procedures for 24 hours. They reported to the study site after refraining from eating, drinking, and smoking for four hours. Subjects had the study procedure explained to them both orally and by written instructions. Subjects then gave written consent to participate before entry into the study. Following an examination for plaque (pre-brushing) and gingivitis (baseline), the subjects were randomized into two balanced groups, each group assigned to one of the two study toothbrushes. Subjects were instructed to brush their teeth for one minute under supervision with their assigned toothbrush and a commercially available fluoride toothpaste (Colgate© Cavity Protection Toothpaste), after which they were again evaluated for plaque (post-brushing). Subjects were dismissed from the study site with their assigned toothbrush and toothpaste, and instructed to brush twice daily at home for the next 12 weeks. The subjects were instructed to brush for one minute during each tooth brushing. The subjects reported to the study site after six weeks and 12 weeks of product use, at which time they were evaluated for plaque and gingivitis. Seventy-one (71) subjects complied with the protocol and completed the clinical study. Compared to the ADA Toothbrush, the Test Toothbrush provided

  16. An investigation of crown fuel bulk density effects on the dynamics of crown fire initiation in shrublands

    Science.gov (United States)

    Watcharapong Tachajapong; Jesse Lozano; Shankar Mahalingam; Xiangyang Zhou; David R. Weise

    2008-01-01

    Crown fire initiation is studied by using a simple experimental and detailed physical modeling based on Large Eddy Simulation (LES). Experiments conducted thus far reveal that crown fuel ignition via surface fire occurs when the crown base is within the continuous flame region and does not occur when the crown base is located in the hot plume gas region of the surface...

  17. Clinical evaluation of 209 all-ceramic single crowns cemented on natural and implant-supported abutments with different luting agents: a 6-year retrospective study.

    Science.gov (United States)

    Sorrentino, Roberto; Galasso, Luigi; Tetè, Stefano; De Simone, Giorgio; Zarone, Fernando

    2012-04-01

    The Procera AllCeram™ system (Nobel Biocare AB, Göteborg, Sweden) is a valid alternative to metal-ceramic restorations. However, limited long-term data of its use for single crowns on natural and implant-supported abutments are available. The present study aimed at evaluating the clinical performances of Procera AllCeram single crowns in both anterior and posterior regions of the oral cavity either on natural tooth or implant abutments over a period of 6 years. Two hundred nine single crowns were fabricated and used in 112 patients. Zinc phosphate and resin luting agents were used to cement the restorations. The crowns were evaluated according to the California Dental Association's quality assessment system. Three crowns were lost at follow-up. Of the 206 restorations, which completed the 6-year follow-up, 9 crowns were affected by mechanical complications and 7 crowns failed. All surviving crowns were ranked as either excellent or acceptable. Cumulative survival and success rates of 95.2 and 90.9%, respectively, were recorded. Within the limitations of the present study, Procera AllCeram crowns proved to be a reliable clinical option to restore both anterior and posterior missing teeth either on natural or implant abutments. The resin cement used in the present study performed better than the zinc phosphate luting agent. © 2009 Wiley Periodicals, Inc.

  18. Controlling the conformation and interplay of p-sulfonatocalix[6]arene as lanthanide crown ether complexes.

    Science.gov (United States)

    Dalgarno, Scott J; Hardie, Michaele J; Makha, Mohamed; Raston, Colin L

    2003-06-16

    Control over the conformational flexibility of p-sulfonatocalix[6]arene in the solid state is possible in the presence of varied stoichiometric amounts of [18]crown-6 and selected lanthanide(III) chlorides. Complexes 1 and 2 have the calixarene in the elusive up-up double cone conformation, whilst complex 3 has the calixarene in the centrosymmetric up-down double partial cone conformation, whereby it acts as a divergent receptor. Complex 1 has a double molecular capsule arrangement which is composed of two p-sulfonatocalix[6]arenes shrouding two [18]crown-6 molecules, also with both coordinated and homoleptic aquated lanthanide ions around the hydrophilic sulfonate rims of the calixarenes. Complex 2 has a ferris wheel arrangement with one lanthanide metal centre coordinated to a sulfonate group and another coordinated to the crown ether whilst tethered to a sulfonate group of the calixarene. Complex 3 forms from a solution with large excess of [18]crown-6, and possesses a crown ether molecule in each of the partial cones and has homoleptic aquated lanthanide ions involved in a complicated hydrogen-bonding regime within the extended structure.

  19. The use of definitive implant abutments for the fabrication of provisional crowns: a case series.

    Science.gov (United States)

    Bilhan, Hakan; Geckili, Onur; Mumcu, Emre

    2011-10-01

    The anterior region is a challenge for most clinicians to achieve optimal esthetics with dental implants. The provisional crown is a key factor in the success of obtaining pink esthetics around restorations with single implants, by soft tissue and inter-proximal papilla shaping. Provisional abutments bring additional costs and make the treatment more expensive. Since one of the aims of the clinician is to reduce costs and find more economic ways to raise patient satisfaction, this paper describes a practical method for chair-side fabrication of non-occlusal loaded provisional crowns used by the authors for several years successfully. Twenty two patients (9 males, 13 females; mean age, 36,72 years) with one missing anterior tooth were treated by using the presented method. Metal definitive abutments instead of provisional abutments were used and provisional crowns were fabricated on the definitive abutments for all of the patients. The marginal fit was finished on a laboratory analogue and temporarily cemented to the abutments. The marginal adaptation of the crowns was evaluated radiographically. The patients were all satisfied with the final appearance and no complications occurred until the implants were loaded with permanent restorations. The use of the definitive abutments for provisional crowns instead of provisional abutments reduces the costs and the same results can be obtained.

  20. Extraction separation of lithium isotopes with crown-ethers

    International Nuclear Information System (INIS)

    Tsivadze, A.Yu.; Demin, S.V.; Levkin, A.V.; Zhilov, V.I.; Nikol'skij, S.F.; Knyazev, D.A.

    1990-01-01

    By the method of extraction chromatography lithium isotope separation coefficients are measured during chemical isotope exchange between lithium aquocomplex and its complex in chloroform with crown-ethers: benzo-15-crown-5, 15crown-5, dicyclohexano-18-crown-6 and dibenzo-18-crown-6. Lithium perchlorate and trichloroacetate are the salts extracted. Values of 6 Li/ 7 Li isotope separation are 1.0032-1.020

  1. Comparison of the fracture strengths of metal-ceramic crowns and three ceromer crowns.

    Science.gov (United States)

    Ku, Chul-Whoi; Park, Sang-Won; Yang, Hong-So

    2002-08-01

    The fracture strength of a number of new ceromer systems for the fabrication of anterior fixed partial dentures is unknown. The purpose of this study was to compare the fracture strengths of metal-ceramic crowns and 3 types of ceromer crowns in a simulated anterior tooth preparation. A resin maxillary central incisor analog was prepared with a 5-degree convergence angle and a 90-degree, 1-mm shoulder. The incisal edge was reduced by 2 mm, and the axiogingival and axioincisal line angles were rounded. A mold of this tooth was made with vinyl polysiloxane impression material. Ten wax patterns were made from the mold and cast in a nickel-chromium alloy for the fabrication of metal dies, from which 10 metal-ceramic crowns were fabricated. Ten crowns for each of 3 ceromer systems (Artglass, Sculpture, and Targis) were fabricated from the same metal die. Each crown group was prepared, polymerized, air-particle abraded, and finished in accordance with the specific manufacturer's instructions. All 4 types of finished crowns were luted to the dies and embedded in polymethyl methacrylate resin blocks. Their fracture resistance was tested in a universal testing machine. The load was directed at the incisolingual line angle, at 130 degrees to the long axis of each specimen, until catastrophic failure occurred. A 7-mm-diameter rod was used to load the artificial crowns, with the center of the rod in contact with the crown surfaces. Analysis of variance and Tukey's multiple comparisons test (Pceromer crowns (1317 vs 602 N, respectively) (Pceromer crowns tested, although significantly lower than the values for metal-ceramic crowns, still exceeded normal occlusal forces.

  2. Urban Crowns: crown analysis software to assist in quantifying urban tree benefits

    Science.gov (United States)

    Matthew F. Winn; Sang-Mook Lee Bradley; Philip A. Araman

    2010-01-01

    UrbanCrowns is a Microsoft® Windows®-based computer program developed by the U.S. Forest Service Southern Research Station. The software assists urban forestry professionals, arborists, and community volunteers in assessing and monitoring the crown characteristics of urban trees (both deciduous and coniferous) using a single side-view digital photograph. Program output...

  3. Restoring crown fractures by direct composite layering using transparent strip crowns.

    Science.gov (United States)

    Eden, Ece; Taviloğlu, Engin

    2016-04-01

    Traumatic dental injuries are mostly seen at childhood and adolescence. The most common fracture in permanent anterior teeth is crown fracture. Esthetic and easy rehabilitation of these anterior teeth is possible using layering techniques and direct composite resin restorations. Shape, color and surface texture are the most important factors in restoring crown fractures esthetically. This article illustrates how to perform an esthetic composite resin restoration of crown fractures using strip crowns. The technique suggests using a strip crown as a mold for direct resin composite restoration. This provides a cost-effective treatment with operator friendly approach where most outstanding advantage is the minimum chair-side time with a single visit that is very important for young trauma patients. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Indications & predisposing factors of crown lengthening surgery

    Directory of Open Access Journals (Sweden)

    Arghavan Amini-Behbahani

    2014-09-01

    Full Text Available Introduction: Since crown lengthening surgery could be accompanied by stress, pain and discomfort, knowledge about its predisposing factors could reduce the demands for such surgery.The aim of this study was to identify the most important indications of crown lengthening surgery in order to present new ideas to clinicians on how to reduce the need for this surgery. Methods: This cross-sectional study was done on 470 patients (aged 12-89 years referred for crown lengthening surgery. The patients' demographic data and their reasons for surgery, the teeth restoration condition and its type, condition of the opposite tooth, type of fractured cusp (posterior teeth, root canal therapy condition and quality, and size of existing intracanal posts were recorded in a data sheet. Data were analyzed by using SPSS software.The chi-square and fisher exact test were used for statistical analysis. The significant difference was p<0.05. Results: The most frequent indication in men and women was dental caries followed by tooth fracture.The second upper premolars and first lower molars needed crown lengthening surgery more often, respectively. Conclusions: Since dental caries and fracture are the most important factors that predispose teeth to crown lengthening surgery, controlling caries with a regular recall sequence can reduce the need for such surgery, especially in the elderly.

  5. PATTERNS OF SEVEN AND COMPLICATED MALARIA IN CHILDREN

    African Journals Online (AJOL)

    GB

    2017-09-01

    Sep 1, 2017 ... Direct composite resin restoration was applied to 11. A year later, a second color measurement was ... two complicated crown-root fractures of maxillary central and lateral incisors after fight sport. In addition, the ... the material was removed using a cutting instrument from the sides and was light cured for.

  6. Crown ether derivatives of EDTA: Pt. 6

    International Nuclear Information System (INIS)

    Liu Zhongqun; Qin Shengying; Chen Shaojin; Tan Lin

    1988-01-01

    EDTA-diaminodibenzo-18-crown-6 (cis- and trans-) condensation polymer is a new compound of crown ether derivatives of EDTA. In this paper the adsorption behaviors of U(IV) and U(VI) on this polymer from chloride solutions and effects of hydrochloric acid concentrations, salting-out agents and organic solvents on distribution coefficient (K d ) of uranium are investigated. Adsorption mechanism of uranyl ion (UO 2 2+ ) on this polymer was studied with IR spectra and by means of the adsorption behaviors of compounds of similar structure. Experimental results show that both polyether section and carboxyl groups in EDTA-diaminodibenzo-18-crown-6 take part in complexation with uranyl ion and synergistic effect appeared

  7. Trauma to an implant-supported crown that was saved by the fixation screw : A case report

    NARCIS (Netherlands)

    den Hartog, Laurens; Meijer, Henny J. A.; Stellingsma, Kees; Santing, Hendrik J.; Raghoebar, Gerry M.

    A traumatic impact to an implant-supported crown might damage the implant, restoration and peri-implant tissues. Ideally, only a small prosthetic retreatment is needed for restoration, as complicated prosthetic retreatments or surgical retreatments in particular, could be very inconvenient for the

  8. Clinical Evaluation and Parental Satisfaction with Pediatric Zirconia Anterior Crowns.

    Science.gov (United States)

    Holsinger, Daniel M; Wells, Martha H; Scarbecz, Mark; Donaldson, Martin

    2016-01-01

    The purpose of this study was to evaluate the clinical success of and parental satisfaction with anterior pediatric zirconia crowns. A retrospective analysis of maxillary anterior pediatric zirconia crowns was performed. Crowns were evaluated for retention, gingival health, color match, contour, marginal integrity, and opposing tooth wear. Parental satisfaction regarding the esthetics of the crowns and parental perception of the impact of treatment on the child's appearance and oral health were evaluated by questionnaire. Fifty-seven crowns were evaluated in 18 children. Eight teeth were lost to exfoliation, three were extracted due to pathology, and two crowns debonded, leaving 44 available for examination. The average crown age at time of examination was 20.8 months. Sixteen crowns (36 percent) displayed gingival inflammation and color mismatch. No recurrent caries or opposing tooth wear was noted. Parents reported high satisfaction with the color, size, and shape of the crowns. The majority of parents reported that crowns improved the appearance and oral health of their child (78 percent and 83 percent, respectively). Eight-nine percent of parents reported that they would highly recommend these crowns. Zirconia crowns are clinically acceptable restorations in the primary maxillary anterior dentition. Parental satisfaction with zirconia crowns is high.

  9. Clinical performance of screw-retained and cemented implant-supported zirconia single crowns: 36-month results.

    Science.gov (United States)

    Cacaci, Claudio; Cantner, Friederike; Mücke, Thomas; Randelzhofer, Peter; Hajtó, Jan; Beuer, Florian

    2017-07-01

    The objective of this clinical study was to evaluate the clinical performance of implant-supported zirconia crowns with a sintered veneering cap. Furthermore, the influence of the type of retention (screw-retained vs cemented single crowns) was analysed. Fifty-eight patients were accommodated with 114 implants, inserted in the molar and premolar regions. Zirconia-based crowns with a sintered veneering cap were either screw-retained (n = 53) or cemented (n = 61) on the implant. Recalls were performed every 6 months. The state of soft tissue was documented by the modified plaque and gingiva index (mPI) and sulcus bleeding index (mSBI). The restorations were evaluated for technical failures like veneering porcelain fractures, surface qualities and marginal fitting. Neither implant loss nor crown fractures occurred. After a mean clinical service time of 36.9 months, fractures of the veneering porcelain were registered in 1.8 % of the cases. The Kaplan-Meier survival probability regarding eventless restorations was 98.2 %. Chipping of the veneering porcelain was registered in two cemented crowns without statistical influence of the type of retention. The indices showed healthy soft periimplant tissues in both groups. Implant-supported zirconia crowns with a sintered veneering cap demonstrated good clinical performance. The type of retention had no influence on technical complications.

  10. Outcome of zirconia single crowns made by predoctoral dental students: a clinical retrospective study after 2 to 6 years of clinical service.

    Science.gov (United States)

    Näpänkangas, Ritva; Pihlaja, Juha; Raustia, Aune

    2015-04-01

    Zirconia has established its role as a reliable ceramic material for fixed prostheses. The purpose of this retrospective study was to evaluate the outcome of zirconia single crowns made by predoctoral students after 2 to 6 years of clinical service. A cohort of 88 patients treated with zirconia single crowns (mean 3 crowns per patient, range 1 to 12 crowns) from 2007 to 2010 by predoctoral dental students was identified. The patients were invited to attend a clinical examination. Sixty-six participants (75%) took part in the clinical follow-up (30 women and 36 men; mean age 60.4 years, range 19 to 81 years). Altogether, 190 teeth with single crowns were examined, and the mean follow-up time was 3.88 years (1.85 to 6.04 years). The most common complications were chipping of veneering porcelain (4%) and loss of cementation (4%). The success rate of the zirconia single crowns after 2 to 6 years was 80% and the survival rate 89%. Zirconia crowns can be successfully used in predoctoral dental education. The success rate of zirconia single crowns after 2 to 6 years was 80% and the survival rate was 89%, in accordance with previous studies. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  11. Comparison of implant versus tooth-supported zirconia-based single crowns in a split-mouth design: a 4-year clinical follow-up study.

    Science.gov (United States)

    Güncü, Mustafa Barış; Cakan, Umut; Aktas, Guliz; Güncü, Güliz Nigar; Canay, Şenay

    2016-12-01

    This study aims to evaluate the 4-year clinical performance of tooth versus implant-supported single-unit zirconia crowns (LAVA™) placed on posterior region. Twenty-four patients (10 men and 14 women) who had received 48 single crowns (24 implant-supported and 24 tooth-supported) from January 2007 to December 2009, were included. California Dental Association (CDA) quality assessment system, plaque and gingival index scores were used to evaluate the performance of the crowns at baseline and at all follow-up examinations. During the follow-up period, no fracture of zirconia coping has occurred. Major complication was chipping in three patients that required a new crown fabrication. Except for the failure ones, all crowns in both groups were rated as satisfactory at the follow-up examinations based on the CDA quality assessment criteria. There were no statistically significant differences between tooth and implant-supported crowns in terms of periodontal parameters. The present 4-year follow-up clinical study demonstrates that single-unit tooth- and implant-supported zirconia crowns have similar prosthetic and periodontal outcomes. Single-unit implant or tooth-supported zirconia crowns may be considered acceptable treatment modalities for restoration of either missing or compromised posterior teeth.

  12. 21 CFR 872.3770 - Temporary crown and bridge resin.

    Science.gov (United States)

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3770 Temporary crown and bridge resin. (a... polymethylmethacrylate, intended to make a temporary prosthesis, such as a crown or bridge, for use until a permanent...

  13. Relative Clinical Success of Bis-Acryl Composite Provisional Crowns.

    Science.gov (United States)

    Kozmacs, Carla; Baumann, Vanessa; Bunz, Oskar; Piwowarczyk, Andree

    2018-01-01

    The high demands on the clinical performance of a single-tooth provisional restoration necessitate that said performance be examined. The authors evaluated 24 teeth evaluated. Two test groups received bis-acrylic composite for provisional crowns (n = 12) and a single-unit, self-supporting, malleable, light-curing composite crown (n = 12). Final crowns (n = 24) served as paired controls. Evaluation of clinical success was measured using previously selected subcategories of FDI criteria. Statistical analysis was performed using McNemar's Test (α = 0.05). The null hypothesis of no improvement of the definitive crown relative to the provisionals was rejected at the 5% significance level (McNemar's P value provisional crowns, 75% received a clinically insufficient valuation, while only 8% of the definitive crowns did. The authors concluded that, independent of the manufacturing process, a bis-acrylic composite provisional crown cannot serve as a replacement for a conventionally manufactured definitive crown.

  14. Screw Access Mark for Cemented Implant Crowns: A Universal Technique to Simplify Retrievability.

    Science.gov (United States)

    Schoenbaum, Todd R; Chang, Yi-Yuan; Stevenson, Richard G

    2018-02-01

    The use of cemented implant prostheses for partially edentulous patients continues to increase in clinical practice. One of the primary complications of the cemented implant crown is difficulty in retrieval, should the need arise. Drilling through most prosthetic materials is of little difficulty for most clinicians, but the complication lies in determining where exactly the access hole needs to be drilled. During fabrication, the location of the screw access channel is marked with a strong contrasting color stain on the surface of the prosthesis. The technique proposed here marks the location of the screw access directly on the prosthesis, thus improving the ease and predictability of future retrieval.

  15. Clinical Evaluation and Patient Satisfaction of Single Zirconia-Based and High-Noble Alloy Porcelain-Fused-to-Metal Crowns in the Esthetic Area: A Retrospective Cohort Study.

    Science.gov (United States)

    Shi, Jun-Yu; Li, Xin; Ni, Jie; Zhu, Zi-Yuan

    2016-10-01

    The aim of this study was to assess clinical survival, complications, and patient satisfaction with single zirconia-based crowns (ZC) or high-noble alloy PFM crowns (HC) in esthetic areas. The study was a retrospective cohort study with up to 3.8 years follow-up (mean 2.5 years). Patients who met the inclusion criteria were reviewed. Survival rates, complications, satisfaction rates (color and form), and overall satisfaction (visual analogue scale, VAS) were evaluated by follow-up examination. Chi-square test (survival, complication, and satisfaction rate) and unpaired t-test (overall satisfaction: VAS) were used to test the difference between the ZC and HC groups. Survival rates and complications were assessed both at subject-level (patient as statistical unit) and at tooth-level (tooth as statistical unit). One hundred and thirteen patients met the inclusion criteria; 95 patients (ZC: 45, HC: 50) with 132 crowns (ZC: 61, HC: 71) were enrolled in the study. The overall survival rate was 93.3% for ZC crowns and 96.0% for HC crowns at subject-level and 93.4% for ZC crowns and 97.2% for HC crowns at tooth-level (p = 0.56 and 0.30, respectively). Veneer chipping was the most frequently seen complication. One HC crown lost retention because of poor cementation. One patient in the ZC group showed progression of periodontal disease. No significant difference of complications was found between the two groups at subject-level and tooth-level (p = 0.37 and 0.34, respectively). The overall satisfaction (VAS) was 8.18 for ZC crowns and 8.46 for HC crowns (p = 0.34). The results of the study showed that a high survival rate could be achieved in both ZC and HC groups. Chipping of the veneering porcelain was the most frequently seen event that led to short-term (less than 3 years) failure and complications. The patients' rating of ZC crowns was not superior to HC crowns. Well-designed studies with high evidence level and large sample size are still needed to further explore the

  16. The molecular genetics of crown gall tumorigenesis

    International Nuclear Information System (INIS)

    Hooykaas, P.J.J.; Schilperoort, R.A.

    1984-01-01

    The phytopathogenic bacteria Agrobacterium tumefaciens and A. rhizogenes are the causative agents of the widespread plant diseases ''crown gall'' and ''hairy root'' respectively. It is now well established that virulent strains of these bacterial species transfer a piece of bacterial DNA into plant cells, thereby transforming these into tumor cells. In research much attention has been paid to the agrobacteria for several reasons. First is the desire to develop a system for the genetic engineering of plant cells based on the natural system for gene transfer between Agrobacterium species and plant cells. Second, there is a striking resemblance between the etiology of animal cancers and the plant cancer crown gall that was recognized as early as in 1927. This led to basic studies on the process of plant tumor induction and on the recovery of plant cells from the tumorous state. A third important interest lies in crown gall as a disease that is the cause of economically important losses in agriculture an horticulture in Europe, North America, and Austrailia. Research has been aimed at finding means to prevent crown gall and to cure plants of this disease

  17. 21 CFR 872.3330 - Preformed crown.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Preformed crown. 872.3330 Section 872.3330 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... device also may be intended for use as a functional restoration for a badly decayed deciduous (baby...

  18. Internal adaptation of cast titanium crowns

    Directory of Open Access Journals (Sweden)

    Sicknan Soares da Rocha

    2007-08-01

    Full Text Available As the adaptation of titanium crowns obtained by Rematitan Plus investment, specific for titanium, is not recognized to be suitable, this study evaluated the effect of the concentration of the specific liquid and the temperature of the mold of investments on the internal misfit of crowns cast on commercially pure titanium. Individual dies of epoxy resin were obtained, representing teeth prepared for full-crown restoration with a 6-degree axial surface convergence angle and shoulder (1.0 mm. For the waxing of each crown, a ring-shaped stainless steel matrix (8.0mm internal diameter; 7.5 mm height was adapted above the individual dies of epoxy resin. The Rematian Plus investment was mixed according to the manufacturer's instructions using two different concentrations of the specific liquid: 100%, 75%. Casting was performed in a Discovery Plasma Ar-arc vacuum-pressure casting machine with molds at temperatures of 430ºC, 515ºC and 600ºC. The crowns were cleaned individually in a solution (1% HF + 13% HNO3 for 10 min using a ultrasonic cleaner, with no internal adaptations, and luted with zinc phosphate cement under a 5 kg static load. The crown and die assemblies were embedded in resin and sectioned longitudinally. The area occupied by cement was observed using stereoscopic lens (10X and measured by the Leica Qwin image analysis system (mm². The data for each experimental condition (n=8 were analyzed by Kruskal-Wallis non-parametric test (á=0.05. The results showed that liquid dilution and the increase in mold temperature did not significantly influence the levels of internal fit of the cast titanium crowns. The lowest means (±SD of internal misfit were obtained for the 430ºC/100%: (7.25 mm² ±1.59 and 600ºC/100% (8.8 mm² ±2.25 groups, which presented statistically similar levels of internal misfit.

  19. Selective crystallization of cations with crown ethers

    International Nuclear Information System (INIS)

    Heffels, Dennis Egidius

    2014-01-01

    The aim of this work was to study the selectivity and preferences of the incorporation of differently sized cations in the cavities of various crown ethers and the characterization of the resulting compounds. The coordination preferences of crown ethers with different cavities have long been known, and the impact of other effects on the structure formation have increasingly become the focus of attention. In this work a comparative overview of the coordination preferences depending on various factors was undertaken. The focus was mainly on the variation of the cavity of the crown ether in the presence of differently sized cations. In addition, the effects of the solvent and differently coordinating anions have been investigated. Within the framework of this work, basic coordination preferences could be detected with rare earth nitrates, which are affected particularly by the choice of the solvent. The formation of different types of structures could be controlled by varying the conditions such that the incorporation of the cation in the cavity of the crown ether was influenced and the formation of a particular type of structure can be influenced partly by the choice of solvent. In this case no direct preferences for the incorporation into the cavity of the crown ether in relation to the cation size were observed for rare earth cations. However, the coordination of the crown ether leads in each case - for lanthanides - to rather high coordination numbers. A total of five new rare earth complexes and two structural variants could be observed with crown ethers. In the study of the selectivity of the incorporation into the cavity, known structures were also reproduced and further structures were characterized but the crystal structures not entirely solved. With the use of monovalent cations such as potassium, lithium or silver a total of nine new compounds could be synthesized, while no clear preferences for the incorporation of certain cations were detected. The

  20. Two-body wear comparison of zirconia crown, gold crown, and enamel against zirconia.

    Science.gov (United States)

    Kwon, Min-Seok; Oh, Sang-Yeob; Cho, Sung-Am

    2015-07-01

    Full zirconia crowns have recently been used for dental restorations because of their mechanical properties. However, there is little information about their wear characteristics against enamel, gold, and full zirconia crowns. The purpose of this study was to compare the wear rate of enamel, gold crowns, and zirconia crowns against zirconia blocks using an in vitro wear test. Upper specimens were divided into three groups: 10 enamels (group 1), 10 gold crowns (group 2, Type III gold), and 10 zirconia crowns (group 3, Prettau(®)Zirkon 9H, Zirkonzahn, Italy). Each of these specimens was wear tested against a zirconia block (40×30×3mm(3)) as a lower specimen (30 total zirconia blocks). Each specimen of the groups was abraded against the zirconia block for 600 cycles at 1Hz with 15mm front-to-back movement on an abrading machine. Moreover, the load applied during the abrading test was 50N, and the test was performed in a normal saline emulsion for 10min. Three-dimensional images were taken before and after the test, and the statistical analysis was performed using the Krushal-Wallis test and Mann-Whitney test (p=0.05). The mean volume loss of group 1 was 0.47mm(3), while that of group 2 and group 3 was 0.01mm(3). The wear volume loss of enamels against zirconia was higher than that of gold and zirconia crowns. Moreover, according to this result, zirconia crowns are not recommended for heavy bruxers. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Fatigue resistance of CAD/CAM resin composite molar crowns.

    NARCIS (Netherlands)

    Shembish, F.A.; Tong, H.; Kaizer, M.; Janal, M.N.; Thompson, V.P.; Opdam, N.J.M.; Zhang, Y.

    2016-01-01

    OBJECTIVE: To demonstrate the fatigue behavior of CAD/CAM resin composite molar crowns using a mouth-motion step-stress fatigue test. Monolithic leucite-reinforced glass-ceramic crowns were used as a reference. METHODS: Fully anatomically shaped monolithic resin composite molar crowns (Lava

  2. Digital photography for urban street tree crown conditions

    Science.gov (United States)

    Neil A. Clark; Sang-Mook Lee; William A. Bechtold; Gregory A. Reams

    2006-01-01

    Crown variables such as height, diameter, live crown ratio, dieback, transparency, and density are all collected as part of the overall crown assessment (USDA 2004). Transparency and density are related to the amount of foliage and thus the photosynthetic potential of the tree. These measurements are both currently based on visual estimates and have been shown to be...

  3. Evaluation of sampling strategies to estimate crown biomass

    Science.gov (United States)

    Krishna P Poudel; Hailemariam Temesgen; Andrew N Gray

    2015-01-01

    Depending on tree and site characteristics crown biomass accounts for a significant portion of the total aboveground biomass in the tree. Crown biomass estimation is useful for different purposes including evaluating the economic feasibility of crown utilization for energy production or forest products, fuel load assessments and fire management strategies, and wildfire...

  4. Crown dilacerations - Two case reports | Rao | Nigerian Dental Journal

    African Journals Online (AJOL)

    Crown dilaceration is a relatively abnormal clinical finding when compared to root dilacerations. The incidence of crown dilacerations is stated to be as low as 3%. This report presents two cases of crown dilacerations in two different locations. A brief review of the literature pertinent to the condition, and the clinical and ...

  5. Complications of Measles (Rubeola)

    Science.gov (United States)

    ... of Measles Signs and Symptoms Transmission Photos of Measles Complications Frequently Asked Questions Top Things Parents Need to ... of age are more likely to suffer from measles complications. Infographic Common Complications Common measles complications include ear ...

  6. Short-Term Prospective Clinical Evaluation of Monolithic and Partially Veneered Zirconia Single Crowns.

    Science.gov (United States)

    Bömicke, Wolfgang; Rammelsberg, Peter; Stober, Thomas; Schmitter, Marc

    2017-02-01

    The purpose of this study was to prospectively evaluate the short-term clinical performance and esthetics of monolithic and partially (i.e., facially) veneered zirconia single crowns (MZC and PZC, respectively). Between September 2011 and June 2013, 68 participants received 90 MZCs and 72 PZCs. Clinical study documentation was performed at crown cementation (baseline), at the 6-month follow-up, and then yearly thereafter using standardized report forms. Eight participants with 14 single crowns (eight MZCs and six PZCs) dropped out during clinical follow-up. Thus, 60 participants (28 male, mean age 62.5 ± 13.1 years) fitted with 82 MZCs and 66 PZCs were analyzed in February 2016 (Kaplan-Meier survival; mean observation time for the restorations 35.1 ± 6.3 months). Descriptive statistics were calculated for participants' and dentists' esthetic ratings on a numerical rating scale from 0 to 10 (0 = unacceptable color and shape; 10 = excellent color and shape). Complications were predominantly biological in nature. One PZC was affected by minor chipping. Cumulative 3-year failure-free survival was 98.5% (standard error (SE), 1.5%) for both MZCs and PZCs. Three-year cumulative complication-free survival (success) was 93.6% (SE 2.8%) for MZCs and 95.5% (SE 2.6%) for PZCs. Three-year cumulative fracture-free survival was 100% for MZCs and 98.5% (SE 1.5%) for PZCs. Crowns of both types were awarded high esthetic scores by participants and dentists. Monolithic and partially veneered zirconia crowns can be used clinically with excellent short-term survival and success and without compromising esthetic appearance. Longer-term follow-up is, however, desirable. During the observation time, both monolithic and partially veneered zirconia crowns showed an outstanding low technical complication rate: only one minor chipping and three losses of retention were observed. Additionally, esthetics was excellent. Based on these results the clinical use of this kind of

  7. Proton-Ionizable Crown Ethers. A Short Review

    Science.gov (United States)

    1989-05-30

    Triazole’Subcyclic Unit 14. Proton-Ionizable Crown Ethers Containing Sulfonamide Groups 15. Miscellaneous Proton-Ionizable Crown Ethers 1. INTRODUCTION. ""Since...the diaza dinitrile crown. Subsequent hydrolysis produced the diacid 33 (Procedure E). 27 Monoaza-crowns 35-38 (Figure V, Table 5) were obtained by the...followed by hydrolysis of the cetidi to f the acid.3o Complextion by th~eam crownsJ hasJ boon extensively castudieon and transportat es of thos ecaions have

  8. Dentin-bonded all-ceramic crowns: current status.

    Science.gov (United States)

    Burke, F J; Qualtrough, A J; Hale, R W

    1998-04-01

    Dentin-bonded all-ceramic crowns employ contemporary techniques to lute the crown to the tooth using a resin luting material and dentin-bonding system. The advantages of these crowns are that they provide good esthetics and fracture resistance and can be used in cases of substantial tooth loss. Their principal disadvantages are that the luting procedure is more time-consuming and that these crowns should not be used where margins are subgingival. Dentin-bonded all-ceramic crowns may be a useful addition to the dentist's armamentarium, but long-term clinical studies are needed to fully assess their performance.

  9. Fracture resistance of monolithic zirconia molar crowns with reduced thickness.

    Science.gov (United States)

    Nakamura, Keisuke; Harada, Akio; Inagaki, Ryoichi; Kanno, Taro; Niwano, Yoshimi; Milleding, Percy; Örtengren, Ulf

    2015-01-01

    The purpose of the present study was to analyze the relationship between fracture load of monolithic zirconia crowns and axial/occlusal thickness and to evaluate the fracture resistance of monolithic zirconia crowns with reduced thickness in comparison with that of monolithic lithium disilicate crowns with regular thickness. Monolithic zirconia crowns (Lava Plus Zirconia, 3M/ESPE) with specified axial/occlusal thicknesses and lithium disilicate crowns (IPS e.max press, Ivoclar/Vivadent) with regular thickness were fabricated using a dental CAD/CAM system and a press technique, respectively. The crowns cemented onto dies were loaded until fracture. Based on measurements of the crown thickness made by micro-CT and the fracture load, multiple regression analysis was performed. It was revealed that the occlusal thickness significantly affected the fracture load (p zirconia crowns, the fracture load of the zirconia crowns with the occlusal thickness of 0.5 mm (5558 ± 522 N) was significantly higher than that of lithium disilicate crowns with an occlusal thickness of 1.5 mm (3147 ± 409 N). Within the limitations of the present study, it is suggested that monolithic zirconia crown with chamfer width of 0.5 mm and occlusal thickness of 0.5 mm can be used in the molar region in terms of fracture resistance.

  10. Cerec anterior crowns: restorative options with monolithic ceramic materials.

    Science.gov (United States)

    Reich, Sven; Fiedlar, Kurt

    2013-01-01

    The aim of this article is to discuss the different types of monolithic ceramic crowns that can be placed on anterior teeth with existing shoulder preparations. Anterior crowns were indicated for the teeth 12 to 22 in the present case. The patient, a 65-year-old male, had received all-ceramic crowns 20 years earlier, which had started to develop cracks and palatal fractures over the last few years. The patient's teeth were prepared and four sets of crowns were fabricated using different monolithic ceramic materials: IPS e.max CAD, Cerec Blocs C In, VITABLOCS Real Life, and ENAMIC. Both shade characterization and crystallization firing were performed on the monolithic lithium disilicate glass ceramic crowns. The silicate ceramic crowns received glaze firing alone. The crowns made of hybrid ceramic (ENAMIC) were treated with a polymer sealant.

  11. Crown structure of Picea omorika trees in the plantation

    Directory of Open Access Journals (Sweden)

    Krstić M.

    2012-01-01

    Full Text Available The study was carried out in Serbian spruce (Picea omorika Panč/Purkynĕ plantations in the western Serbia. The paper presents results of the analysis of crown development. The following elements were analyzed: total tree height, height of the crown base, absolute and relative crown length, maximal crown diameter, coefficient of crown spreading and degree of crown girth. We discuss approaches to the modeling of tree crown growth and development, growing under favorable environmental and stand conditions, without anomalies in development. In order to establish the relationship between analyzed factors, regression analyses were applied. Data fitting was by the analytic method, by the implementation of Prodan’s functions of growth, linear and parabolic function. Received models can be used for the simulation of various growth and developing processes in forest.

  12. TRANSFORMATIONS OF BENZO-15-CROWN-5, [3.3]DIBENZO-18-CROWN-6 AND [4.4]DIBENZO-24-CROWN-8 IN AQUEOUS SOLUTIONS OF NITRIC ACID

    Directory of Open Access Journals (Sweden)

    S. M. Pluzhnik-Gladyr

    2015-02-01

    Full Text Available Peculiarities of benzo-15-crown-5 (I, [3.3]dibenzo-18-crown-6 (II, and [4.4]diben zo-24-crown-8 (III nitration by the dilute nitric acid and the mixture HCl-HNO3(4:1, «aqua regia» at room temperature are discussed. It was revealed that the «reactivity» of studied crown ethers (symbatically/antisymbatic to their hydrophili ci ty/lipophilicity is variated as follows: I>> III> II.

  13. Antagonist wear by polished zirconia crowns.

    Science.gov (United States)

    Hartkamp, Oliver; Lohbauer, Ulrich; Reich, Sven

    The aim of this in vivo study was to measure antagonist wear caused by polished monolithic posterior zirconia crowns over a 24-month period using the intraoral digital impression (IDI) technique. Thirteen zirconia crowns were placed in nine patients. The crowns and adjacent teeth were captured using an intraoral scanner (Lava C.O.S.). The corresponding antagonist teeth and the respective neighboring teeth were also scanned. Scanning was performed immediately after the restoration (baseline) as well as 12 and 24 months after crown placement. Geomagic Qualify software was used to superimpose the follow-up data sets onto the corresponding baseline data set, identify wear sites, and measure maximum vertical height loss in each individual wear site. Overall antagonist wear was then determined as the mean of wear rates measured in all of the individual antagonist units. In addition, wear rates in enamel and ceramic antagonists were analyzed as part of the scope of this study. The maximum mean wear with standard deviation (SD) in the overall sample with a total of nine patients, 13 antagonist units, and 98 evaluable wear sites was 86 ± 23 µm at 12 months, and 103 ± 39 µm at 24 months. The maximum mean wear in the enamel antagonist subgroup was 87 ± 41 µm at 12 months, and 115 ± 71 µm at 24 months; and in the ceramic antagonist subgroup 107 ± 22 µm at 12 months, and 120 ± 27 µm at 24 months. The wear rates determined in this study are comparable to those of existing studies. The IDI technique of wear analysis can be carried out in a practical manner and produces useful results.

  14. Individual lithium disilicate crowns in a full-arch, implant-supported rehabilitation: a clinical report.

    Science.gov (United States)

    Maló, Paulo; de Sousa, Sérgio Tavares; De Araújo Nobre, Miguel; Moura Guedes, Carlos; Almeida, Ricardo; Roma Torres, António; Legatheaux, João; Silva, António

    2014-08-01

    This clinical report presents the clinical outcome of a maxillary full-arch implant-supported fixed rehabilitation with lithium disilicate reinforced glass ceramic monolithic crowns opposing a mandibular metal-acrylic implant-supported fixed rehabilitation in a 62-year-old woman. Eight implants were successfully placed (four maxillary, four mandibular), and no complications occurred in the postoperative or maintenance periods. Six months after delivery, the maxillary and mandibular prostheses were found to be clinically, biologically, and mechanically stable, and the patient was satisfied with the esthetics and her ability to function. Although the present indications for the use of lithium disilicate are still restricted to tooth-borne restorations, it is possible to successfully rehabilitate edentulous patients through implant-supported fixed prostheses using lithium disilicate reinforced glass ceramic monolithic crowns. © 2014 by the American College of Prosthodontists.

  15. An Investigation Into the Integrity of Fit of Provisional Crowns Using Current Proprietary Temporary Crown Materials.

    Science.gov (United States)

    Taylor, Philip D; Georgakis, Georgios; Niggli, Jason

    2016-06-01

    Three methods of direct provisional crown construction were investigated for accuracy of marginal fit. A modified proprietary crown coping was compared to Bis GMA and isobutyl methacrylate resin provisional crowns with margins modified by using a flowable composite and 'bead on' isobutyl methacrylate respectively. Measurement was at 50x magnification at seven sites over the fit surface. Data was analyzed using SPSS version 13.0.1 and measurement compared using the Mann Whitney test set at a significance level of 0.05. Reliability was checked using the Bland Altman test. Statistical significant differences were found between the three groups. The order of best fit was Bis-GMA and flowable composite > isobutyl methacrylate with 'bead on' margins > Bis-GMA modified implant temporary coping. The clinical significance is that the Bis GMA and flowable composite combination can be used with equal confidence to traditional methods of temporarisation.

  16. Retention behavior of double-crown attachments with zirconia primary and secondary crowns.

    Science.gov (United States)

    Schwindling, Franz Sebastian; Stober, Thomas; Rustemeier, Rainer; Schmitter, Marc; Rues, Stefan

    2016-05-01

    To investigate whether adequate retention of zirconia conical crown (CC) attachments can be achieved, and to investigate their long-term retention. Sixteen individual zirconia primary crowns were produced with convergence angles of 1° or 2° (eight of each). After determination of the convergence angles of the primary crowns, monolithic zirconia secondary crowns were manufactured. To evaluate the retention behavior of all-zirconia CC, the crowns were fitted with forces from F=12.5-100 N. Force magnitudes during the loosening process (L) were then measured. L/F ratios were recorded and the coefficient of friction (μ0) was calculated. Long-term retention was tested with up to 50,000 cycles of denture integration at a speed of 30 mms(-1) and a fitting force magnitude of 53 N. Even when primary crowns were manufactured with the utmost care, the real convergence angles were greater than the nominal angles of the standardized burs (1° and 2°) by 0.28° (SD 0.11°). Without mechanical aging, mean L/F was 0.632 (SD 0.038) for 1° samples and 0.526 (SD 0.022) for 2° samples, indicative of high retentive forces of up to 63.2% of the fitting forces. When all the test results were used, best-fitting curves gave μ0=0.117 for new samples and μ0=0.126 for samples after 50,000 integration cycles. When the correct milling and sintering parameters are chosen, the retention behavior of zirconia CCs is adequate and stable. This innovative type of attachment is appealing because of the beneficial properties of zirconia and the efficient CAD/CAM-based manufacture. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  17. [Comparison of the clinical effects of selective laser melting deposition basal crowns and cobalt chromium alloy base crowns].

    Science.gov (United States)

    Li, Jing-min; Wang, Wei-qian; Ma, Jing-yuan

    2014-06-01

    To evaluate the clinical effects of selective laser melting (SLM) deposition basal crowns and cobalt chromium alloy casting base crowns. One hundred and sixty eight patients treated with either SLM deposition basal crowns (110 teeth) or cobalt chromium alloy casting basal crowns (110 teeth) were followed-up for 1 month, 6 months, 12 months and 24 months. The revised standard of American Public Health Association was used to evaluate the clinical effect of restoration, including the color of porcelain crowns, gingival inflammation, gingival margin discoloration, and crack or fracture. Data analysis was conducted with SPSS 20 software package for Student's t test and Chi-square test. Six cases were lost to follow-up. The patients who were treated with SLM deposition basal crowns (104 teeth) and cobalt chromium alloy casting base crowns (101 teeth) completed the study. Patients were more satisfied with SLM deposition cobalt chromium alloy porcelain crowns. There was 1 prosthesis with poor marginal fit after 24 months of restoration in SLM crowns. There were 6 prostheses with edge coloring and 8 with poor marginal fit in cobalt chromium alloy casting base crowns, which was significantly different between the 2 groups(P<0.05). The SLM deposition copings results in smaller edge coloring and better marginal fit than those of cobalt-chrome copings. Patients are pleased with short-term clinical results.

  18. Fracture resistance of implant- supported monolithic crowns cemented to zirconia hybrid-abutments: zirconia-based crowns vs. lithium disilicate crowns.

    Science.gov (United States)

    Elshiyab, Shareen H; Nawafleh, Noor; Öchsner, Andreas; George, Roy

    2018-02-01

    The aim of this in vitro study was to investigate the fracture resistance under chewing simulation of implant-supported posterior restorations (crowns cemented to hybrid-abutments) made of different all-ceramic materials. Monolithic zirconia (MZr) and monolithic lithium disilicate (MLD) crowns for mandibular first molar were fabricated using computer-aided design/computer-aided manufacturing technology and then cemented to zirconia hybrid-abutments (Ti-based). Each group was divided into two subgroups (n=10): (A) control group, crowns were subjected to single load to fracture; (B) test group, crowns underwent chewing simulation using multiple loads for 1.2 million cycles at 1.2 Hz with simultaneous thermocycling between 5℃ and 55℃. Data was statistically analyzed with one-way ANOVA and a Post-Hoc test. All tested crowns survived chewing simulation resulting in 100% survival rate. However, wear facets were observed on all the crowns at the occlusal contact point. Fracture load of monolithic lithium disilicate crowns was statistically significantly lower than that of monolithic zirconia crowns. Also, fracture load was significantly reduced in both of the all-ceramic materials after exposure to chewing simulation and thermocycling. Crowns of all test groups exhibited cohesive fracture within the monolithic crown structure only, and no abutment fractures or screw loosening were observed. When supported by implants, monolithic zirconia restorations cemented to hybrid abutments withstand masticatory forces. Also, fatigue loading accompanied by simultaneous thermocycling significantly reduces the strength of both of the all-ceramic materials. Moreover, further research is needed to define potentials, limits, and long-term serviceability of the materials and hybrid abutments.

  19. Zirconia-based crowns up to 5 years in function: a retrospective clinical study and evaluation of prosthetic restorations and failures.

    Science.gov (United States)

    Güncü, M Barιş; Cakan, Umut; Muhtarogullari, Mehmet; Canay, Senay

    2015-01-01

    The purpose of this retrospective study was to evaluate the 5-year clinical performance and failure rate of single- or multiple-unit zirconia-based crowns. A total of 148 patients (39 men and 109 women, mean age: 46.9 ± 10.6 years) treated in university and private practices with 618 single- or multiple-unit zirconia-based (Lava) crowns made on natural teeth from January 2007 to December 2008 were included. Two hundred fifty-nine anterior and 359 posterior crowns were examined. A core and/or veneer fracture that required replacement of the restoration was considered to be a failure. The cumulative survival rate (CSR) was described with Kaplan-Meier survival functions. The crowns replaced for other reasons were deemed lost to follow-up, and esthetic, functional, and biologic complications were rated. At the 5-year follow-up, no zirconia core fractures were observed. Twelve veneer fractures that required crown replacement were detected. The CSR was 98.1%. There was a statistically significant difference between survival of the anterior and posterior restorations (P crowns experienced biologic and technical complications. The most common complications were smooth veneer fracture (4, 0.6%), loss of retention (7, 1%), staining because of smoking (24, 4%), and gingival recession (48, 8%). According to the 5-year CSR (98.1%) observed in this study, zirconia-based single or multiple crowns may be considered an acceptable treatment modality for the replacement of anterior and posterior teeth. RESULTS from the current study should be supported by additional randomized clinical trials.

  20. A retrospective survey on long-term survival of posterior zirconia and porcelain-fused-to-metal crowns in private practice.

    Science.gov (United States)

    Ozer, Fusun; Mante, Francis K; Chiche, Gerard; Saleh, Najeed; Takeichi, Takuro; Blatz, Markus B

    2014-01-01

    This retrospective survey assessed the clinical survival of zirconia-based crowns (PFZ) and conventional porcelain- fused-to-metal (PFM) crowns on posterior teeth in private practice. A print survey of 13 private practitioners was conducted to assess the long-term survival of previously placed full-coverage crowns. The practitioners reported a total of 2,182 premolar (n = 881) and molar (n = 1,301) full-coverage single crowns, 1,102 PFZ and 1,080 PFM, fabricated by one dental laboratory (Cusp, Boston) and followed over 7.4 years. All post-cementation complications (eg, porcelain fractures and chippings) were recorded as failures. In the PFZ group, one veneering porcelain (CZR, Kuraray Noritake) was used in combination with three coping systems (Lava, 3M ESPE; Procera, Nobelbiocare; Katana, Kuraray Noritake). Kaplan-Meier survival analysis was used for statistical analyses. The probability of survival of posterior crowns investigated over the period of study (7.4 years) was 99.3% for PFM and 99.2% for PFZ restorations. There was no statistically significant difference (P = .614) between PFZ and PFM groups. In the PFZ group, probability of survival was 97.7% for Lava, 100% for Procera, and 99.5% for Katana. There were no statistically significant differences (P = .34) between the three PFZ systems or the location of the crowns (premolar or molar; P = .454). PFZ crowns fabricated with CZR and three commercial zirconia coping systems revealed excellent long-term success rates. Survival times and survival probabilities of posterior PFZ crowns did not differ from PFM crowns and were independent of type of coping system and location (molar or premolar teeth).

  1. Eleven-Year Follow-Up of a Prospective Study of Zirconia Implant Abutments Supporting Single All-Ceramic Crowns in Anterior and Premolar Regions.

    Science.gov (United States)

    Zembic, Anja; Philipp, Alexander Otto Hermann; Hämmerle, Christoph Hans Franz; Wohlwend, Arnold; Sailer, Irena

    2015-10-01

    Clinical studies on zirconia abutments report very good survival rates and biological and technical results, but few have an observation period of more than 5 years. The aim of this study was to assess the long-term performance of customized zirconia implant abutments supporting all-ceramic crowns. Twenty-seven patients receiving 54 single implants were included (25 incisors, 14 canines, 15 premolars in both jaws). Yttria-stabilized zirconia abutments were screwed to the implants with a defined torque. All-ceramic crowns were adhesively cemented onto the abutments. The implants, abutments, and crowns were clinically and radiographically examined after 11 years of use. Modified United States Public Health Service (USPHS) criteria were used to assess technical outcomes: fracture of abutment/crown framework/veneering ceramic, loosening of abutment screw/crown, marginal adaptation, anatomical form, occlusal wear, and abutment fit. The biological parameters were pocket probing depth, plaque control record, bleeding on probing, papilla index, and gingival/mucosal recession at implants and neighboring natural teeth. The cumulative success rate of abutments and crowns was calculated by the Kaplan-Meier method. The results of the USPHS criteria were analyzed descriptively. Sixteen patients with 31 zirconia abutments were examined at 11.3 (±0.9) years after implantation. No abutment or crown was lost. The cumulative success rate was 96.3% for abutments and 90.7% for crowns. Two abutment screws loosened, and three crowns exhibited minor chipping. There were no biological complications. Customized zirconia single implant abutments exhibited excellent long-term outcomes in anterior and premolar regions. © 2014 Wiley Periodicals, Inc.

  2. Basal ganglia - thalamus and the crowning enigma

    Directory of Open Access Journals (Sweden)

    Marianela eGarcia-Munoz

    2015-11-01

    Full Text Available When Hubel (1982 referred to layer 1 of primary visual cortex as …a ‘crowning mystery’ to keep area-17 physiologists busy for years to come... he could have been talking about any cortical area. In the 80’s and 90’s there were no methods to examine this neuropile on the surface of the cortex: a tangled web of axons and dendrites from a variety of different places with unknown specificities and doubtful connections to the cortical output neurons some hundreds of microns below. Recently, three changes have made the crowning enigma less of an impossible mission: the clear presence of neurons in layer 1 (L1, the active conduction of voltage along apical dendrites and optogenetic methods that might allow us to look at one source of input at a time. For all of those reasons alone, it seems it is time to take seriously the function of L1. The functional properties of this layer will need to wait for more experiments but already L1 cells are GAD67 positive, i.e., inhibitory! They could reverse the sign of the thalamic glutamate (GLU input for the entire cortex. It is at least possible that in the near future normal activity of individual sources of L1 could be detected using genetic tools. We are at the outset of important times in the exploration of thalamic functions and perhaps the solution to the crowning enigma is within sight. Our review looks forward to that solution from the solid basis of the anatomy of the basal ganglia output to motor thalamus. We will focus on L1, its afferents, intrinsic neurons and its influence on responses of pyramidal neurons in layers 2/3 and 5. Since L1 is present in the whole cortex we will provide a general overview considering evidence mainly from the somatosensory cortex before focusing on motor cortex.

  3. Characterization of Microsolvated Crown Ethers from Broadband Rotational Spectroscopy

    Science.gov (United States)

    Perez, Cristobal; Schnell, Melanie; Blanco, Susana; Lopez, Juan Carlos

    2016-06-01

    Since they were first synthetized, crown ethers have been extensively used in organometallic chemistry due to their unparalleled binding selectivity with alkali metal cations. From a structural point of view, crown ethers are heterocycles containing oxygen and/or other heteroatoms, although the most common ones are formed from ethylene oxide unit. Crown ethers are conventionally seen as being hydrophilic inside and hydrophobic outside when the structures found for the metal cation complexes are considered. However, crown ethers are extremely flexible and in isolation may present a variety of stable conformations so that their structure may be easily adapted in presence of a strong ligand as an alkali metal cation minimize the energy of the resulting complex. Water can be considered a soft ligand which interacts with crown ethers through moderate hydrogen bonds. It is thus interesting to investigate which conformers are selected by water to form complexes, the preferred interaction sites and the possible conformational changes due to the presence of one or more water molecules. Previous studies identified microsolvated crown ethers but in all cases with a chromophore group attached to the structure. Here we present a broadband rotational spectroscopy study of microsolvated crown ethers produced in a pulsed molecular jet expansion. Several 1:1 and 1:2 crown ether:water aggregates are presented for 12-crown-4, 15-crown-5 and 18-crown-6. Unambiguous identification of the structures has been achieved using isotopic substitution within the water unit. The subtle changes induced in the structures of the crown ether monomer upon complexation and the hydrogen-bonding network that hold them together will be also discussed. F. Gámez, B. Martínez-Haya, S. Blanco,J. C. López and J. L. Alonso, Phys. Chem. Chem. Phys. 2014, 14 12912-12918 V. A. Shubert, C.W. Müller and T. Zwier, J. Phys. Chem. A 2009, 113 8067-8079

  4. Zirconia crowns - the new standard for single-visit dentistry?

    Science.gov (United States)

    Wiedhahn, Klaus; Fritzsche, Günter; Wiedhahn, Claudine; Schenk, Olaf

    2016-01-01

    Zirconia crowns combine the advantages of metal restorations, such as minimally invasive tooth preparation and ease of cementation, with those of full ceramic crowns, such as low thermal conductivity and tooth color. With the introduction of a high-speed sintering procedure, it is possible to produce and cement zirconia crowns and small monolithic bridges in a Cerec Single Visit procedure. This new procedure is compared to established chairside methods.

  5. Fracture resistance of monolithic zirconia molar crowns with reduced thickness

    OpenAIRE

    Nakamura, Keisuke; Harada, A.; Inagaki, R.; Kanno, Taro; Niwano, Y.; Milleding, Percy; Ørtengren, Ulf Thore

    2015-01-01

    This is the accepted manuscript version. Published version is available at Acta Odontologica Scandinavica Objectives. The purpose of the present study was to analyze the relationship between fracture load of monolithic zirconia crowns and axial/occlusal thickness, and to evaluate the fracture resistance of monolithic zirconia crowns with reduced thickness in comparison with that of monolithic lithium disilicate crowns with regular thickness. Materials and methods. Monolithic zi...

  6. Fatigue resistance of CAD/CAM resin composite molar crowns.

    Science.gov (United States)

    Shembish, Fatma A; Tong, Hui; Kaizer, Marina; Janal, Malvin N; Thompson, Van P; Opdam, Niek J; Zhang, Yu

    2016-04-01

    To demonstrate the fatigue behavior of CAD/CAM resin composite molar crowns using a mouth-motion step-stress fatigue test. Monolithic leucite-reinforced glass-ceramic crowns were used as a reference. Fully anatomically shaped monolithic resin composite molar crowns (Lava Ultimate, n=24) and leucite reinforced glass-ceramic crowns (IPS Empress CAD, n=24) were fabricated using CAD/CAM systems. Crowns were cemented on aged dentin-like resin composite tooth replicas (Filtek Z100) with resin-based cements (RelyX Ultimate for Lava Ultimate or Multilink Automix for IPS Empress). Three step-stress profiles (aggressive, moderate and mild) were employed for the accelerated sliding-contact mouth-motion fatigue test. Twenty one crowns from each group were randomly distributed among these three profiles (1:2:4). Failure was designated as chip-off or bulk fracture. Optical and electron microscopes were used to examine the occlusal surface and subsurface damages, as well as the material microstructures. The resin composite crowns showed only minor occlusal damage during mouth-motion step-stress fatigue loading up to 1700N. Cross-sectional views revealed contact-induced cone cracks in all specimens, and flexural radial cracks in 2 crowns. Both cone and radial cracks were relatively small compared to the crown thickness. Extending these cracks to the threshold for catastrophic failure would require much higher indentation loads or more loading cycles. In contrast, all of the glass-ceramic crowns fractured, starting at loads of approximately 450N. Monolithic CAD/CAM resin composite crowns endure, with only superficial damage, fatigue loads 3-4 times higher than those causing catastrophic failure in glass-ceramic CAD crowns. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Clinically relevant fracture testing of all-ceramic crowns.

    Science.gov (United States)

    Øilo, Marit; Kvam, Ketil; Tibballs, John E; Gjerdet, Nils Roar

    2013-08-01

    Fracture strength measured in vitro indicates that most all-ceramic crowns should be able to withstand mastication forces. Nevertheless, fractures are one of the major clinical problems with all-ceramic restorations. Furthermore, the fracture mode of all-ceramic crowns observed in clinical use differs from that found in conventional fracture strength tests. The aim of the present study was to develop and investigate a method that simulates clinical fracture behavior in vitro. 30 crowns with alumina cores were made to fit a cylindrical model with a molar-like preparation design. These crowns were randomly allocated to 3 tests groups (n=10). The crowns in group 1 were cemented to abutment models of epoxy and subsequently fractured by occlusal loading without contact damage. The crowns in group 2 were fractured by cementation with expanding cement. The crowns in group 3 were cemented on an abutment model of epoxy split almost in two and fractured by increasing the diameter of the model in the bucco-lingual direction. The fractured crowns were analyzed by fractographic methods and compared to a reference group of 10 crowns fractured in clinical use. The fracture modes of all the in vitro crowns were similar to clinical fracture modes. The fracture modes in group 1 were most closely matched to the clinical fractures. These crowns also fractured at clinically relevant loads. Laboratory tests that induce a distortion of the abutment model during occlusal loading without occlusal contact damage can simulate clinical fractures of all-ceramic crowns. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  8. Fatigue Resistance of CAD/CAM Resin Composite Molar Crowns

    Science.gov (United States)

    Shembish, Fatma A.; Tong, Hui; Kaizer, Marina; Janal, Malvin N.; Thompson, Van P.; Opdam, Niek J.; Zhang, Yu

    2016-01-01

    Objective To demonstrate the fatigue behavior of CAD/CAM resin composite molar crowns using a mouth-motion step-stress fatigue test. Monolithic leucite-reinforced glass-ceramic crowns were used as a reference. Methods Fully anatomically shaped monolithic resin composite molar crowns (Lava Ultimate, n = 24) and leucite reinforced glass-ceramic crowns (IPS Empress CAD, n = 24) were fabricated using CAD/CAM systems. Crowns were cemented on aged dentin-like resin composite tooth replicas (Filtek Z100) with resin-based cements (RelyX Ultimate for Lava Ultimate or Multilink Automix for IPS Empress). Three step-stress profiles (aggressive, moderate and mild) were employed for the accelerated sliding-contact mouth-motion fatigue test. Twenty one crowns from each group were randomly distributed among these three profiles (1:2:4). Failure was designated as chip-off or bulk fracture. Optical and electronic microscopes were used to examine the occlusal surface and subsurface damages, as well as the material microstructures. Results The resin composite crowns showed only minor occlusal damage during mouth-motion step-stress fatigue loading up to 1700 N. Cross-sectional views revealed contact-induced cone cracks in all specimens, and flexural radial cracks in 2 crowns. Both cone and radial cracks were relatively small compared to the crown thickness. Extending these cracks to the threshold for catastrophic failure would require much higher indentation loads or more loading cycles. In contrast, all of the glass-ceramic crowns fractured, starting at loads of approximately 450 N. Significance Monolithic CAD/CAM resin composite crowns endure, with only superficial damage, fatigue loads 3 – 4 times higher than those causing catastrophic failure in glass-ceramic CAD crowns. PMID:26777092

  9. Pediatric Preformed Metal Crowns - An Update

    Directory of Open Access Journals (Sweden)

    Sangameshwar Sajjanshetty

    2013-01-01

    Full Text Available Stainless Steel crowns (SSC were introduced in 1947 by the Rocky Mountain Company and popularized by Humphrey in 1950. Prefabricated SSC can be adapted to individual primary teeth and cemented in place to provide a definitive restoration. The SSC is extremely durable, relatively inexpensive, subject to minimal technique sensitivity during placement, and offers the advantage of full coronal coverage. SSC are often used to restore primary and permanent teeth in children and adolescents where intracoronal restorations would otherwise fail. This article brings the update of this definitive restoration.

  10. Crown and bridge cements: clinical applications.

    Science.gov (United States)

    Bunek, Sabiha S; Powers, John M

    2012-12-01

    Cement selection can be confusing because factors such as substrate, the type of restoration, and patient needs must be considered. Some substrates require additional treatment before cementation. This article describes the most commonly used traditional crown and bridge cements (GI and RMGI) used for metal and metal-ceramic restorations, and resin cements used for all-ceramic restorations. Advantages, disadvantages, indications, and contraindications of cements have been reviewed. Recommended uses of cements for metal, ceramic, and laboratory composite restorations have been presented. General guidelines for surface treatment ot silica- and zirconia-based restorations when using resin cements have been discussed.

  11. Posterior preveneered stainless steel crowns: clinical performance after three years.

    Science.gov (United States)

    O'Connell, Anne C; Kratunova, Evelina; Leith, Rona

    2014-01-01

    The purpose of this study was to evaluate the clinical performance of posterior preveneered stainless steel crowns after three years. NuSmile crowns and Kinder Krowns were randomly allocated on paired molars using a split-mouth design. Variables such as fracture, wear, gingival health, and esthetics were recorded. (Pcrowns in 14 children. After three years, 53 percent of crowns were fracture free compared to 81 percent at one year. There was minimal esthetic impact for most fractures due to the location of the veneer fracture, but five crowns had extensive fracture. No difference was reported in the clinical performance between the two crown types. Fracture was more likely to occur where the adjacent tooth was missing. Parents reported a satisfaction rating of 8.3 out of 10. Clinical performance of both crown types was similar and successful for three years. Facing fracture occurred in 47 percent of crowns but had minimal impact on the esthetic value or parental satisfaction in the majority of cases. These crowns offer an esthetic alternative to the traditional stainless steel crown, but parents should be alerted to the possibility of veneer loss over time.

  12. Adhesive Cementation Promotes Higher Fatigue Resistance to Zirconia Crowns.

    Science.gov (United States)

    Campos, F; Valandro, L F; Feitosa, S A; Kleverlaan, C J; Feilzer, A J; de Jager, N; Bottino, M A

    The aim of this study was to investigate the influence of the cementation strategy on the fatigue resistance of zirconia crowns. The null hypothesis was that the cementation strategy would not affect the fatigue resistance of the crowns. Seventy-five simplified molar tooth crown preparations were machined in glass fiber-filled epoxy resin. Zirconia crowns were designed (thickness=0.7 mm), milled by computer-aided design/computer-aided manufacturing, and sintered, as recommended. Crowns were cemented onto the resin preparations using five cementation strategies (n=15): ZP, luting with zinc phosphate cement; PN, luting with Panavia F resin cement; AL, air particle abrasion with alumina particles (125 μm) as the crown inner surface pretreatment + Panavia F; CJ, tribochemical silica coating as crown inner surface pretreatment + Panavia F; and GL, application of a thin layer of porcelain glaze followed by etching with hydrofluoric acid and silanization as crown inner surface pretreatment + Panavia F. Resin cement was activated for 30 seconds for each surface. Specimens were tested until fracture in a stepwise stress fatigue test (10,000 cycles in each step, 600 to 1400 N, frequency of 1.4 Hz). The mode of failure was analyzed by stereomicroscopy and scanning electron microscopy. Data were analyzed by Kaplan-Meier and Mantel-Cox (log rank) tests and a pairwise comparison (pzirconia layer. Finite element analysis showed the different stress distribution for the two models. Adhesive cementation of zirconia crowns improves fatigue resistance.

  13. Relation of Crown Width to Tree Diameter In Some Upland Hardwood Stands of Southern Illinois

    Science.gov (United States)

    Leon S. Minckler; Samuel F. Gingrich

    1970-01-01

    Crown width-d.b.h. relationships in well stocked, uneven-aged stands of oak and hickory were similar to those for open-grown trees and were independent of site, crown class, and species. The irregular crowns of forest grown trees interface and overlap, however, and measuring crown extensions to the branch tips tended to overestimate effective crown area

  14. Crowns cemented on crown preparations lacking geometric resistance form. Part II: effect of cement.

    Science.gov (United States)

    Proussaefs, Periklis

    2004-03-01

    This study evaluated the effect of different cements on resistance to dislodgment of crowns cemented on preparations lacking geometric resistance form. A preparation that offered no geometric resistance form, with 20 degrees total occlusal convergence (TOC), 0.9 mm wide shoulder finish line, and a 2.5 mm axial wall height was created on an ivorine tooth using a milling machine. Ten metal test specimen die replicas and 10 standardized metal crowns with recipient sites for the application of external forces through a universal testing machine were fabricated. The crowns were cemented on the dies under 5 and 10 kg external loads, the marginal openings measured, loaded to dislodgment, and cleaned of cement. The process was repeated using zinc oxide and eugenol (ZOE), zinc phosphate (ZPh), resin modified glass ionomer (RMGI), and composite resin (CR) cements. Marginal openings under 5 kg cementation loads were 74.63 (+/-15.04) for ZOE, 75.98 (+/-18.20) microm for ZPh, 98.58 (+/-22.62) microm for RMGI, and 105.82 (+/-20.07) microm for CR cements respectively; under 10 kg cementation loads they were 57.62 (+/-15.86) microm, 59.55 (+/-15.41) microm, 95.00 (+/-19.52) microm, 101.30 (+/-12.52) microm respectively. Oblique dislodgment forces, measured with a Universal testing machine, were 40.18 (+/- 6.76) N for ZOE, 215.65 (+/-45.79) N for ZPh, 165.43 (+/-19.53) N for RMGI, and 181.54 (+/-30.75) N for CR respectively when crowns were cemented under 5 kg loads. The corresponding values for 10 kg loads were 38.62 (+/-4.19), 274.86 (+/-54.22), 139.70 (+/-21.71), and 160.40 (+/-21.21) respectively. Only zinc phosphate cement produced statistically enhanced resistance when crowns were cemented under 10 kg force (p value = 0.035). Under the conditions of the present study only crowns cemented with zinc phosphate displayed increased resistance to dislodgment on preparations lacking resistance form.

  15. Usurpation of a Crowned Lapwing Vanellus coronatus nest by ...

    African Journals Online (AJOL)

    I report an instance of usurpation of a Crowned Lapwing Vanellus coronatus nest by a pair of African Wattled Lapwings Vanellus senegalensis. The nest, which originally contained a single Crowned Lapwing egg, eventually contained an additional three Wattled Lapwing eggs, before it was predated. Although parents of ...

  16. Evaluation of wild Juglans species for crown gall resistance

    Science.gov (United States)

    Paradox, the most widely used rootstock in CA walnut production, is highly susceptible to the causal agent of crown gall (CG) Agrobacterium tumefaciens. The bacterial pathogen induces the formation of large tumors around the crown of the tree resulting in a reduction in both vigor and yield. If left...

  17. Gloss and Surface Roughness of Anterior Pediatric Zirconia Crowns.

    Science.gov (United States)

    Theriot, Adrien L; Frey, Gary N; Ontiveros, Joe C; Badger, Gary

    2017-09-15

    The purpose of this study was to determine gloss and surface roughness (Ra) of pediatric anterior zirconia crowns. Gloss of labial and lingual surfaces of pediatric anterior zirconia crowns from three manufacturers was measured on 20 specimens using a small area gloss meter on each. Ra (μm) was measured using a contact-type surface profilometer. Data were evaluated by analysis of variance and pair-wise comparison at the 0.05 level of significance. There were statistically significant interactions between surface location and crown type for both gloss and Ra scores. NuSmile had higher mean gloss scores and lower mean Ra scores than both Kinder Krowns and EZCrowns. Kinder Krowns showed lower mean gloss scores and higher Ra scores than other crown groups. Among all crowns, there was a trend of higher mean gloss paired with lower mean surface roughness, and lower mean gloss paired with higher mean Ra. Hand smoothed followed by mechanically polished zirconia crowns (NuSmile) displayed the highest mean gloss and lowest mean Ra compared to hybrid polishedglazed zirconia crowns (Kinder Krowns, EZCrowns). Of the hybrid polished-glazed zirconia crowns, Kinder Krowns displayed the lowest mean gloss and highest mean Ra.

  18. Re/crowning the Jowo Śākyamuni

    DEFF Research Database (Denmark)

    Warner, Cameron

    2011-01-01

    of ritual observance and visions received.  In 1409, Tsongkhapa Lozang Drakpa  (1357-1419) crowned the Jowo, changing his doctrinal and iconographic representations.  I connect the controversy surrounding Tsongkhapa's decision to re/crown the Jowo in 1409 to the significance placed on authenticity...

  19. Relationships among alfalfa resistance to Sclerotinia crown and ...

    African Journals Online (AJOL)

    Sclerotinia crown and stem rot (SCSR) of alfalfa caused by Sclerotinia trifoliorum is one of the main constraints for efficient alfalfa cultivation in temperate climate all over the world. The resistance of 200 alfalfa accessions to Sclerotinia crown and stem rot was evaluated during 2010 to 2011 in the field nursery established in ...

  20. Evaluation of Vertical Marginal Adaptation of Provisional Crowns by ...

    African Journals Online (AJOL)

    Objective: To investigate and compare the degree of vertical marginal discrepancy of four provisional crown materials by digital microscope. Materials and Methods: A total of 100 provisional crowns were fabricated on standardized resin dies by direct technique of provisional fabrication, using four different provisional ...

  1. Spectrophotometric evaluation of crown fragment a year after ...

    African Journals Online (AJOL)

    Background: Crown fracture is the most common type of fracture and frequently affects the anterior teeth. Crown fractures have been treated in several ways depending on the location and kind of fracture. This case emphasizes reattachment of fractured fragments using fiber-reinforced post. Also this case report underlines ...

  2. Crown ratio models for tropical rainforests species in Oban division ...

    African Journals Online (AJOL)

    Crown ratio (CR) is a characteristic used to describe the crown size, which is an important element of forest growth and yield. It is often used as an important predictor variable for tree-level growth equations. It indicates tree vigour and is an important habitat variable. It is often estimated using allometry. Modified versions of ...

  3. Load bearing capacity, fracture mode, and wear performance of digitally veneered full-ceramic single crowns.

    Science.gov (United States)

    Schubert, Oliver; Nold, Ephraim; Obermeier, Matthias; Erdelt, Kurt; Stimmelmayr, Michael; Beuer, Florian

    Computer-aided technologies can help to minimize clinical complications of zirconia-based restorations such as veneering porcelain fractures. The aim of this study was to evaluate different veneering approaches for zirconia single crowns regarding contact wear, fracture strength, and failure mode. Six different types of computer-aided design (CAD) crowns were manufactured and conventionally cemented on 10 metal dies each: three groups with a zirconia framework and a CAD/CAM-fabricated veneering cap ("digital veneering system": DVS, CAD-on, Infix CAD), zirconia-based crowns with pressed veneering caps (Infix Press), zirconia framework containing the dentin layer with only the incisal enamel material added (dentin-core), and conventional substructure with powder buildup veneering porcelain (layering technique). All specimens were submitted to artificial aging (120,000 mechanical cycles, 50 N load, 0.7-mm sliding movement, 320 thermocycles). After contact wear was measured with a laser scanning system, fracture resistance and failure mode were examined using a universal testing machine and a scanning electron microscope. Statistical analysis was performed at a significance level of 5%. No statistical difference was revealed regarding the contact wear of the restorations (P = 0.171; ANOVA). No significant difference was found regarding the fracture resistance of the crowns (P = 0.112; ANOVA). Failure analysis revealed three different failure patterns: cohesive veneering fracture, adhesive delamination, and total fracture, with a characteristic distribution between the groups. All tested specimens survived artificial aging and exhibited clinically acceptable wear resistance and fracture resistance. Digital veneering techniques offer a promising, time- and cost-effective manufacturing process for all-ceramic restorations and may usefully complement the digital workflow.

  4. Double crown-retained maxillary overdentures: 5-year follow-up.

    Science.gov (United States)

    Frisch, Eberhard; Ziebolz, Dirk; Ratka-Krüger, Petra; Rinke, Sven

    2015-02-01

    There is a lack of data concerning implant-supported overdentures (IODs) retained by double crowns in the edentulous maxilla. To perform a retrospective evaluation of clinical outcomes (survival/success rates) of maxillary overdentures retained on four implants via double crowns. Between 1993 and 2011, 28 patients with edentulous maxillae were restored with overdentures supported by four implants with a Morse taper connection (Ankylos, Dentsply Friadent, Mannheim, Germany) and double crowns according to the Marburg Double Crown (MDC) technique in a private practice. For retrospective evaluation of implant and prosthetic survival (in situ criterion) and success (event-free observational period), only patients attending a professional maintenance program were included (n = 20). Twenty patients (13 female/ seven male, mean age: 63.45 ± 7.18 years) with 80 implants met the inclusion criteria. The mean follow-up period was 5.64 ± 3.50 years. One implant was lost (cumulative survival rate: 98.75%). Eight implants (10.1%) in two patients (10%) showed peri-implantitis; both patients were active smokers (cumulative success rate: 88.75%). All dentures were still functional (prosthetic survival rate 100%) at the time of investigation. Technical maintenance procedures (e.g., abutment loosening, screw loosening, acrylic fracture or relining) were required at a rate of 0.222/patient-year. Within the limitations of this study, we conclude that MDC-IODs are a promising treatment alternative for edentulous maxillae offering high implant and prosthesis survival rates > 98% and a limited incidence of biological and technical complications after a mean observational period of >5 years. © 2013 Wiley Periodicals, Inc.

  5. Dosimetric distribution of the surroundings of different dental crowns and implants during LINAC photon irradiation

    International Nuclear Information System (INIS)

    Chang, Kwo-Ping; Lin, Wei-Ting; Shiau, An-Cheng; Chie, Yu-Huang

    2014-01-01

    In radiotherapy of the head and neck, metal dentures or implants will increase the risk of complications such as mucositis and osteoradionecrosis. The aim of this study is to explore the back scatter effect of commercially available dental metal alloys on the mucosa and bone under 6 MV LINAC irradiation. The Monte Carlo method has been employed to calculate the dose distribution in the heterogeneous media of the designed oral phantom based on the oral cavity geometry. Backscatter dose increases up to a maximum of 53%, and is primarily dependent on the physical density and electron density of the metal crown alloy. Ceramic metal crowns have been quantified to increase backscatter dose up to 10% on mucosa. Ceramic serves as an inherent shield of mucosa. The backscatter dose will be greater for a small field size if the tumor is located at a deeper region. Titanium implants will increase the backscatter dose by 13% to bone but will not affect the mucosa. QC-20 (polystyrene resin) is recommended as a shield material (3 mm) to eliminate the backscatter dose on mucosa due to the high density metals. - Highlights: • A phantom with metal crown and implant was designed based on the human oral cavity. • Backscatter dose increment on mucosa depends mainly on physical density and electron density of the metal crown. • The titanium implant will affect dose increment to bone but not to the mucosa. • The backscatter dose will be larger for small field size if the tumor is located at a deeper region. • QC-20 (polystyrene resin) is recommended as a shield material

  6. Calorimetric study of binding of some disaccharides with crown ethers

    International Nuclear Information System (INIS)

    Davydova, Olga I.; Lebedeva, Nataliya Sh.; Parfenyuk, Elena V.

    2004-01-01

    Isothermal titration calorimetry has been applied to the determination of the thermodynamic parameters of binding of β-lactose, α,α-trehalose and sucrose with 15-crown-5 and 18-crown-6 in water at 298.15 K. The formation of 1:1 molecular associates has been found for the systems studied except 18-crown-6 and β-lactose. The associates are preferentially or completely entropy stabilized. The most stable associate is formed between α,α-trehalose and 18-crown-6. The obtained values of thermodynamic parameters of binding are discussed from the point of view of solute-solvent interactions as well as conformational and structural peculiarities of the disaccharides (DS) and crown ethers (CE)

  7. [Clinical evaluation of zirconia crowns for single posterior teeth].

    Science.gov (United States)

    Chen, Yuanhua; Meng, Xiangfeng; Yu, Qing

    2014-06-01

    To observe and evaluate the clinical performance of zirconia crowns made by CEREC inLab computer aided design/computer aided manufacturing(CAD/CAM) for posterior teeth. A total of 242 patients were implanted with zirconia crowns fabricated by CEREC inLab CAD/CAM. The crowns were evaluated by Modified US Public Health Service criteria at baseline, 6, 12, 24, and 36 months. The chi-square test was used to analyze the survival rate. All but five crowns were evaluated by an independent evaluator at baseline, 6, 12, 24, and 36 months. The survival rate declined with time. The A score percentage was above 85% at 36 months. The single zirconia crowns fabricated by CEREC inLab CAD/CAM demonstrate satisfactory clinical performance during a short period.

  8. Structural Study of Mismatched Disila-Crown Ether Complexes

    Directory of Open Access Journals (Sweden)

    Kirsten Reuter

    2017-02-01

    Full Text Available Mismatched complexes of the alkali metals cations Li+ and Na+ were synthesized from 1,2-disila[18]crown-6 (1 and 2 and of K+ from 1,2,4,5-tetrasila[18]crown-6 (4. In these alkali metal complexes, not all crown ether O atoms participate in the coordination, which depicts the coordination ability of the C-, Si/C-, and Si-bonded O atoms. Furthermore, the inverse case—the coordination of the large Ba2+ ion by the relatively small ligand 1,2-disila[15]crown-5—was investigated, yielding the dinuclear complex 5. This structure represents a first outlook on sandwich complexes based on hybrid crown ethers.

  9. Triaquachlorido(18-crown-6barium chloride

    Directory of Open Access Journals (Sweden)

    Min-Min Zhao

    2012-03-01

    Full Text Available In the title compound, [BaCl(C12H24O6(H2O3]Cl, the BaII atom, the coordinating and free Cl− anions, one coordinating water molecule and two O atoms of an 18-crown-6 molecule lie on a mirror plane. The environment of the ten-coordinate Ba2+ ion is defined by one Cl atom, three water molecules and six O atoms from the macrocyclic ether. The macrocycle adopts a conformation with an approximate D3d symmetry. In the crystal, O—H...Cl hydrogen bonds link the complex cations and Cl− anions into a two-dimensional network parallel to (010. An intramolecular O—H...Cl hydrogen bond is also present.

  10. Gingival pigmentation beneath a metallic crown

    International Nuclear Information System (INIS)

    Sakai, T.; Hirayasu, R.; Sakai, H.; Hashimoto, N.

    1988-01-01

    Light and electron microscopic studies and energy dispersive X-ray analysis disclosed that the essential cause of gingival discoloration following the placement of a metallic crown, was marked deposition of melanin pigment. Deposition of melanin pigment was observed in epithelial cells, on basement membranes, and in fibroblasts, macrophages and among intercellular ground substance of the proprial layer. Brown or dark brown colored granules were observed in the deep portion of the proprial layer. Some metallic elements as silver and sulfur were detected. It was presumed that these materials were dental metals accidentally implanted in gingival tissues during the therapeutic procedure. The deposition of melanin pigment closely corresponded with mucosal tissue where these materials were present in the deep portion of the proprial layer. These findings suggested that these materials influenced the physiological metabolism of melanin and induced its pathological deposition in the proprial tissue. (author)

  11. EL CROWN HALL. CONTEXTO Y PROYECTO / The Crown Hall. Context and project

    Directory of Open Access Journals (Sweden)

    José Santatecla Fayós

    2010-05-01

    Full Text Available RESUMEN El artículo enmarca el edificio del Crown Hall en el contexto docente y arquitectónico de Mies van der Rohe. Revisa sus inicios en la Bauhaus con su primera intervención en un espacio docente para la Bauhaus de Berlín en 1932, así como su marcha a Estados Unidos, los planteamientos arquitectónicos del campus del IIT y el proyecto del Crown Hall. El texto incide en el estudio del proceso proyectual del Crown Hall analizando la evolución de su concepción arquitectónica a través de las diferentes versiones del proyecto. Se constata la transición desde los primeros planteamientos arquitectónicos de los edificios del campus del IIT proyectados por Mies hacia el planteamiento del gran espacio unitario del Crown Hall. Este proyecto se puede entender desde la creciente importancia de la estructura, la claridad constructiva y el manejo del acero y vidrio como únicos materiales de la imagen del edificio y el carácter flexible y unitario del espacio. Finalmente se hace referencia al concepto del “espacio universal” en la arquitectura de Mies, como un concepto abstracto que supera los de flexibilidad de uso o unidad espacial, insinuando, a modo de reflexión, las principales variables que definirían el espacio universal miesiano. SUMMARY The article showcases the Crown Hall building in the educational and architectural context of Mies van der Rohe. It reviews his beginnings in the Bauhaus with his first intervention in an educational space for the Bauhaus of Berlin in 1932, as well as his sojourn to the United States, and the architectural approaches to the IIT campus and the Crown Hall project. The text touches on the study of the planning process for the Crown Hall, analysing the evolution of its architectural conception, through the different versions of the project. The article covers the transition from the first architectural approaches for the IIT campus buildings, planned by Mies, to the approach of the large unitary space

  12. Complications and Deaths - State

    Data.gov (United States)

    U.S. Department of Health & Human Services — Complications and deaths - state data. This data set includes state-level data for the hip/knee complication measure, the Agency for Healthcare Research and Quality...

  13. Complications and Deaths - National

    Data.gov (United States)

    U.S. Department of Health & Human Services — Complications and deaths - national data. This data set includes national-level data for the hip/knee complication measure, the Agency for Healthcare Research and...

  14. Complications and Treatments

    Science.gov (United States)

    ... Possible Complications Links to Other Websites People with sickle cell disease (SCD) start to have signs of the disease during the first year of life, usually around 5 months of age. Symptoms and complications of SCD are different for each ...

  15. Pregnancy Complications: Shoulder Dystocia

    Science.gov (United States)

    ... X Home > Complications & Loss > Pregnancy complications > Shoulder dystocia Shoulder dystocia Now playing: E-mail to a friend Please ... some women more likely than others to have shoulder dystocia? A pregnant woman may be at risk for ...

  16. Complications and Deaths - Hospital

    Data.gov (United States)

    U.S. Department of Health & Human Services — Complications and deaths - provider data. This data set includes provider data for the hip/knee complication measure, the Agency for Healthcare Research and Quality...

  17. Pregnancy Complications: Anemia

    Science.gov (United States)

    ... online community Home > Complications & Loss > Pregnancy complications > Anemia Anemia E-mail to a friend Please fill in ... anemia at a prenatal care visit . What causes anemia? Usually, a woman becomes anemic (has anemia) because ...

  18. [Comparison of adaptation of crowns of different lithium disilicate glass-ceramic].

    Science.gov (United States)

    Li, Kemeng; Ai, Hongjun; Yi, Zhe

    2016-05-01

    To evaluate the adaptation of different lithium disilicate glass-ceramic crown and whether different fabrication processes affect the adaptation of crowns. Thirty epoxy dies crowns were divided into 3 groups. They were cemented to domestic lithium disilicate glass-ceramic crowns in Group A, to IPS e.max CAD crowns in Group B and to IPS e.max Press crowns in Group C respectively. All crowns were cut by cutting machine. A confocal laser scanning microscope was used to measure the gap between crown tissue surface and die. There were significant differences in the three groups of measurement points(Pcrowns appeared to have clinically acceptable fit.

  19. Fracture strength of lithium disilicate crowns compared to polymer-infiltrated ceramic-network and zirconia reinforced lithium silicate crowns.

    Science.gov (United States)

    Sieper, Kim; Wille, Sebastian; Kern, Matthias

    2017-10-01

    The aim of this study was to evaluate the fracture strength of crowns made from current CAD/CAM materials. In addition the influence of crown thickness and chewing simulation on the fracture strength was evaluated. Crowns were fabricated from lithium disilicate, zirconia reinforced lithium silicate (ZLS-ceramic) and a polymer-infiltrated ceramic-network (PICN) with an occlusal thickness of 1.0mm or 1.5mm, respectively (n=16). Crowns were cemented on composite dies. Subgroups of eight specimens were loaded with 5kg in a chewing simulator for 1,200,000 cycles with thermal cycling. Finally, all specimens were loaded until fracture in a universal testing machine. Three-way ANOVA was used to detect statistical interaction. Differences regarding the materials were tested with two-way ANOVA, following one-way ANOVA and a post-hoc Tukey's-Test. All crowns survived the chewing simulation. The material had a significant influence on the fracture resistance (p≤0.05). Lithium disilicate achieved the highest values of fracture strength in almost all groups followed by ZLS-ceramic. PICN achieved the lowest values of fracture strength. Chewing simulation increased the fracture strength of thick lithium disilicate crown significantly. Greater occlusal thickness of all crown materials resulted in higher crown fracture strength before chewing simulation. After chewing simulation occlusal thickness of lithium disilicate and PICN crowns had no significant influence on the fracture strength. All crowns revealed fracture strength above the clinically expected loading forces. Therefore the durability of the tested CAD/CAM materials seems promising also in an occlusal thickness of 1.0mm. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Seven-year prospective clinical study on zirconia-based single crowns and fixed dental prostheses.

    Science.gov (United States)

    Tartaglia, Gianluca M; Sidoti, Ernesto; Sforza, Chiarella

    2015-06-01

    Zirconia-based prostheses are used for esthetic crown and fixed restorations, but follow-ups are still limited. The authors evaluated the 7-year clinical results of 303 zirconia core restorations, performed in a general dental private practice. Clinical events (fracture and loss of retention, gingivitis, tenderness, excess cement, and temporary pain) were recorded in 303 zirconia core restorations positioned in 88 patients. Kaplan-Meier survival probability estimates were computed for failures (needed the replacement or removal of the prosthesis) and complications (resolved without replacing the prosthesis). One hundred and fifty single crowns (130 tooth-supported, 20 implant-supported) and 153 multiple units up to 6 elements (49 tooth-supported, 104 implant-supported) were followed-up for 7 years in 88 patients (40 men, 48 women), aged 35-89 years (mean 57). During the follow-up period, there were no complications for 287 (95 %) of the restorations. Sixteen restorations/abutment teeth (5 %) had some complication: extraction of abutment tooth (7, 2 %); caries (2, 1 %), porcelain veneer fracture (3, 1 %), loss of retention (4, 1 %). Nine (3 %) restorations were recorded as failures. The overall 7-year survival probability estimate for failures was 0.966 (95 % confidence limits, 0.932 and 0.983), for complications was 0.976 (95 % confidence limits 0.947 and 0.989), with a cumulative survival rate of 94.7 %. Within the analyzed follow-up, zirconia core restorations appear a good clinical solution, with favorable functional properties. All ceramic restorations can be successfully used for both single-and multiple-unit prostheses, either teeth or implants supported.

  1. Two-piece zirconia implants supporting all-ceramic crowns: a prospective clinical study.

    Science.gov (United States)

    Cionca, Norbert; Müller, Nada; Mombelli, Andrea

    2015-04-01

    The aim of this prospective clinical study is to evaluate the safety and efficacy of a new all-ceramic implant system to replace missing teeth in partially edentulous patients. Thirty-two partially edentulous, systemically healthy patients were treated with 49 two-piece zirconia implants (ZERAMEX(®) T Implant System). Zirconia abutments were connected with adhesive resin cement. Single-unit full-ceramic crowns were cemented. The cases have been followed for 588 ± 174 days after loading (range 369-889 days). All patients have been re-evaluated 1 year after loading. The cumulative survival rate 1 year after loading was 87% implants. All failures were the result of aseptic loosening, and no implants were lost after the first year. The results of the other cases were good, and the patients were very satisfied. The cumulative soft tissue complication rate was 0%, the cumulative technical complication rate was 4% implants, the cumulative complication rate for bone loss >2 mm was 0%, and the cumulative esthetic complication rate was 0%. Including the data from 20 patients treated with an earlier version of the system, an over-all 2-year cumulative survival rate of 86% was calculated for a total of 76 two-piece zirconia implants supporting all-ceramic crowns in 52 patients. Replacement of single teeth in the posterior area was possible with this new full-ceramic implant system. Failures were due to aseptic loosening. © 2014 The Authors. Clinical Oral Implants Research Published by John Wiley & Sons Ltd.

  2. Two-piece zirconia implants supporting all-ceramic crowns: A prospective clinical study

    Science.gov (United States)

    Cionca, Norbert; Müller, Nada; Mombelli, Andrea

    2015-01-01

    Objectives The aim of this prospective clinical study is to evaluate the safety and efficacy of a new all-ceramic implant system to replace missing teeth in partially edentulous patients. Material and methods Thirty-two partially edentulous, systemically healthy patients were treated with 49 two-piece zirconia implants (ZERAMEX® T Implant System). Zirconia abutments were connected with adhesive resin cement. Single-unit full-ceramic crowns were cemented. The cases have been followed for 588±174 days after loading (range 369–889 days). All patients have been re-evaluated 1 year after loading. Results The cumulative survival rate 1 year after loading was 87% implants. All failures were the result of aseptic loosening, and no implants were lost after the first year. The results of the other cases were good, and the patients were very satisfied. The cumulative soft tissue complication rate was 0%, the cumulative technical complication rate was 4% implants, the cumulative complication rate for bone loss >2 mm was 0%, and the cumulative esthetic complication rate was 0%. Including the data from 20 patients treated with an earlier version of the system, an over-all 2-year cumulative survival rate of 86% was calculated for a total of 76 two-piece zirconia implants supporting all-ceramic crowns in 52 patients. Conclusions Replacement of single teeth in the posterior area was possible with this new full-ceramic implant system. Failures were due to aseptic loosening. PMID:24666352

  3. Guided tooth preparation for a pediatric zirconia crown.

    Science.gov (United States)

    Lee, Ju-Hyoung

    2018-03-01

    Unesthetic primary incisors can produce negative self-perceptions in preschool-aged children. In recent years, because of increased esthetic demands, prefabricated zirconia crowns have become increasingly popular. However, zirconia crowns cannot be crimped, and the clinician must prepare the teeth to fit the zirconia crowns. Therefore, extended preparation and fitting times are necessary, especially for inexperienced practitioners. A 1- to 2-millimeter subgingival feather margin also is required. Gingival hemorrhage after subgingival preparation compromises the retention of zirconia crowns. In this clinical report, the author presents a step-by-step description of the clinical and laboratory procedures for restoring a discolored traumatized incisor with a zirconia crown. The author used a polyvinyl siloxane occlusal registration material as an impression material and made 2 identical casts. The author fabricated 3 reduction guides after prospective tooth preparation on the casts. The author rapidly prepared the discolored incisor with the reduction guides and ultrasonic burs. A zirconia crown provided an optimal esthetic result and gingival health. Because the reduction guides provided a visibility intraorally, fast tooth reduction, less trial placement, and passive adaptation of the crown were successful. Because the ultrasonic burs prevented gingival injuries, hemorrhage control was not necessary. The presented technique reduced the patient's discomfort and total chair time. Therefore, this alternative technique is helpful for inexperienced practitioners. Copyright © 2018 American Dental Association. Published by Elsevier Inc. All rights reserved.

  4. Review of Alberta Crown Crude Oil Marketing Program

    International Nuclear Information System (INIS)

    Crandall, G. R.; Kromm, R. B.

    1999-01-01

    This report contains an independent evaluation of the operations of the private marketing agents that are currently marketing the Alberta Crown's share of royalty crude oil. The evaluation includes a review of pricing performance, working relationship, current issues and the overall performance of the marketing arrangements during the fiscal years of 1997 and 1998. Overall, the outsourcing of sales of Crown production to agents is judged to be successful. For example, it has been noted that agents are becoming more aggressive in maintaining and increasing their margins. On the other hand, the increased level of aggressiveness in marketing, while tending to maximize Crown revenues, is also creating a potential conflict on how margins should be shared between the Crown and its agents. Also, there has been evidence of some management issues between the agents and the Crown concerning the extent to which the Crown should share in any increased value which the agent generates by increased third party marketing activities. These differences need to be addressed in order to maintain the strong performance of the marketing program. The consultants also recommend additional guidelines on risk management issues that more clearly define the Crown's risk tolerance. 2 tabs., 4 figs

  5. Marginal Assessment of Crowns by the Aid of Parallel Radiography

    Directory of Open Access Journals (Sweden)

    Farnaz Fattahi

    2015-03-01

    Full Text Available Introduction: Marginal adaptation is the most critical item in long-term prognosis of single crowns. This study aimed to assess the marginal quality as well asthe discrepancies in marginal integrity of some PFM single crowns of posterior teeth by employing parallel radiography in Shiraz Dental School, Shiraz, Iran. Methods: In this descriptive study, parallel radiographies were taken from 200 fabricated PFM single crowns of posterior teeth after cementation and before discharging the patient. To calculate the magnification of the images, a metallic sphere with the thickness of 4 mm was placed in the direction of the crown margin on the occlusal surface. Thereafter, the horizontal and vertical space between the crown margins, the margin of preparations and also the vertical space between the crown margin and the bone crest were measured by using digital radiological software. Results: Analysis of data by descriptive statistics revealed that 75.5% and 60% of the cases had more than the acceptable space (50µm in the vertical (130±20µm and horizontal (90±15µm dimensions, respectively. Moreover, 85% of patients were found to have either horizontal or vertical gap. In 77% of cases, the margins of crowns invaded the biologic width in the mesial and 70% in distal surfaces. Conclusion: Parallel radiography can be expedient in the stage of framework try-in to yield some important information that cannot be obtained by routine clinical evaluations and may improve the treatment prognosis

  6. The repair of preveneered posterior stainless steel crowns.

    Science.gov (United States)

    Yilmaz, Yucel; Gurbuz, Taskin; Eyuboglu, Ozge; Belduz, Nihal

    2008-01-01

    This study's purposes were to determine the shear bond strength (SBS) for and to perform dye penetration (microleakage) and scanning electron microscopy (SEM) evaluations of preveneered posterior stainless steel crowns (SSCs) that were repaired using 2 different materials. Twenty-two crowns were used. They were stored in artificial saliva for 30 days and then thermocycled. A force was applied on the crowns' occlusal surfaces until the original veneer material appeared to be fractured. The fracture types and S8S values were recorded. The crowns were then repaired using Panavia opaque cement and Tetric Flow or Monoopaque and Tetric Flow. Twenty of the repaired crowns were subjected to dye penetration and SBS tests, and the remaining 2 were evaluated using SEM. Statistical analysis revealed no statistically significant differences in the results of either the S8S or the dye penetration test (P = .58 and P = 38, respectively). A statistically significant difference was found between original and repaired crowns regarding fracture extent (P = .02), but not failure type (P = .08). SEM evaluation showed that there was no observable gap at the interface of the original or repaired materials and the stainless steel base. Preveneered posterior stainless steel crowns may be repaired using either repair material types tested here.

  7. The risk of healing complications in primary teeth with intrusive luxation

    DEFF Research Database (Denmark)

    Lauridsen, Eva; Blanche, Paul; Yousaf, Nadia

    2017-01-01

    .5). Most teeth (83.7%) spontaneously re-erupted within the first year. Most complications were diagnosed within the first year. The risk of PN was lowest in patients less than 2 years of age. The degree of intrusion or a concomitant crown fracture did not affect the risk of PN or PTL. CONCLUSIONS: Over 80...

  8. Clinical assessment of enamel wear caused by monolithic zirconia crowns.

    Science.gov (United States)

    Stober, T; Bermejo, J L; Schwindling, F S; Schmitter, M

    2016-08-01

    The purpose of this study was to measure enamel wear caused by antagonistic monolithic zirconia crowns and to compare this with enamel wear caused by contralateral natural antagonists. Twenty monolithic zirconia full molar crowns were placed in 20 patients. Patients with high activity of the masseter muscle at night (bruxism) were excluded. For analysis of wear, vinylpolysiloxane impressions were prepared after crown incorporation and at 6-, 12-, and 24-month follow-up. Wear of the occlusal contact areas of the crowns, of their natural antagonists, and of two contralateral natural antagonists (control teeth) was measured by use of plaster replicas and a 3D laser-scanning device. Differences of wear between the zirconia crown antagonists and the control teeth were investigated by means of two-sided paired Student's t-tests and linear regression analysis. After 2 years, mean vertical loss was 46 μm for enamel opposed to zirconia, 19-26 μm for contralateral control teeth and 14 μm for zirconia crowns. Maximum vertical loss was 151 μm for enamel opposed to zirconia, 75-115 μm for control teeth and 60 μm for zirconia crowns. Statistical analysis revealed significant differences between wear of enamel by zirconia-opposed teeth and by control teeth. Gender, which significantly affected wear, was identified as a possible confounder. Monolithic zirconia crowns generated more wear of opposed enamel than did natural teeth. Because of the greater wear caused by other dental ceramics, the use of monolithic zirconia crowns may be justified. © 2016 John Wiley & Sons Ltd.

  9. Retention of cast crown copings cemented to implant abutments.

    Science.gov (United States)

    Dudley, J E; Richards, L C; Abbott, J R

    2008-12-01

    The cementation of crowns to dental implant abutments is an accepted form of crown retention that requires consideration of the properties of available cements within the applied clinical context. Dental luting agents are exposed to a number of stressors that may reduce crown retention in vivo, not the least of which is occlusal loading. This study investigated the influence of compressive cyclic loading on the physical retention of cast crown copings cemented to implant abutments. Cast crown copings were cemented to Straumann synOcta titanium implant abutments with three different readily used and available cements. Specimens were placed in a humidifier, thermocycled and subjected to one of four quantities of compressive cyclic loading. The uniaxial tensile force required to remove the cast crown copings was then recorded. The mean retention values for crown copings cemented with Panavia-F cement were statistically significantly greater than both KetacCem and TempBond non-eugenol cements at each compressive cyclic loading quantity. KetacCem and TempBond non-eugenol cements produced relatively low mean retention values that were not statistically significantly different at each quantity of compressive cyclic loading. Compressive cyclic loading had a statistically significant effect on Panavia-F specimens alone, but increased loading quantities produced no further statistically significant difference in mean retention. Within the limitations of the current in vitro conditions employed in this study, the retention of cast crown copings cemented to Straumann synOcta implant abutments with a resin, glass ionomer and temporary cement was significantly affected by cement type but not compressive cyclic loading. Resin cement is the cement of choice for the definitive non-retrievable cementation of cast crown copings to Straumann synOcta implant abutments out of the three cements tested.

  10. Survival Predictions of Ceramic Crowns Using Statistical Fracture Mechanics.

    Science.gov (United States)

    Nasrin, S; Katsube, N; Seghi, R R; Rokhlin, S I

    2017-05-01

    This work establishes a survival probability methodology for interface-initiated fatigue failures of monolithic ceramic crowns under simulated masticatory loading. A complete 3-dimensional (3D) finite element analysis model of a minimally reduced molar crown was developed using commercially available hardware and software. Estimates of material surface flaw distributions and fatigue parameters for 3 reinforced glass-ceramics (fluormica [FM], leucite [LR], and lithium disilicate [LD]) and a dense sintered yttrium-stabilized zirconia (YZ) were obtained from the literature and incorporated into the model. Utilizing the proposed fracture mechanics-based model, crown survival probability as a function of loading cycles was obtained from simulations performed on the 4 ceramic materials utilizing identical crown geometries and loading conditions. The weaker ceramic materials (FM and LR) resulted in lower survival rates than the more recently developed higher-strength ceramic materials (LD and YZ). The simulated 10-y survival rate of crowns fabricated from YZ was only slightly better than those fabricated from LD. In addition, 2 of the model crown systems (FM and LD) were expanded to determine regional-dependent failure probabilities. This analysis predicted that the LD-based crowns were more likely to fail from fractures initiating from margin areas, whereas the FM-based crowns showed a slightly higher probability of failure from fractures initiating from the occlusal table below the contact areas. These 2 predicted fracture initiation locations have some agreement with reported fractographic analyses of failed crowns. In this model, we considered the maximum tensile stress tangential to the interfacial surface, as opposed to the more universally reported maximum principal stress, because it more directly impacts crack propagation. While the accuracy of these predictions needs to be experimentally verified, the model can provide a fundamental understanding of the

  11. Preventive and conservative prosthodontic treatment using overdenture and Richmond crown

    Directory of Open Access Journals (Sweden)

    Jevin Stivie Cialy

    2016-12-01

    Full Text Available Prosthodontic treatment aims to restore the chewing function (rehabilitation and to prevent tooth decay and bone resorption (preventive and conservative. As an example, treatment by overdenture and Richmond crown. Overdenture is a partial or complete removable denture covered and supported by one or more teeth, the tooth roots and/or dental implants. Richmond crown is fixed denture by post and crown system, in which the post part goes into the root canal and its crown covers the entire of original tooth crown surface. By retaining the original teeth and/or roots, it could improve the stability and retention of the denture, and defend proprioseptic of teeth and vertical dimensions. To provide information about preventive prosthodontic treatment and prevention by using overdenture and Richmond crown. Case Report: A 50 year old woman only has 44 teeth on the mandible which is indicated for the overdenture construction and loss teeth 13, 14, 17 and 27 on the maxilla with deep caries in teeth 22 which is indicated for a removable partial denture (RPDs construction by Richmond crown gear 22. On an early stage study, printing models is done. Then treatment of the root canal on teeth 22 and 44, followed by root canal preparation, core construction (cast post and Richmond crown on tooth 22 and bareroot preparation on tooth 44 for overdenture construction. The procedure followed by printing, recording bite to insertion. Choosing treatment either overdenture or Richmond crown is very important because it could mantain remain original teeth, thus it can help to improve the retention and stabilization.

  12. Lanthanide crown ether complexes of p-sulfonatocalix[5]arene.

    Science.gov (United States)

    Dalgarno, Scott J; Hardie, Michaele J; Warren, John E; Raston, Colin L

    2004-08-21

    Two types of arrays are formed in water involving aza-crown ethers, p-sulfonatocalix[5]arene and europium(III) ions. One is a co-ordination polymer connecting calixarenes, sodium ions and lanthanide ions based on "ferris wheel" moieties incorporating aza-18-crown-6 and sodium ions. The second structure is a host-guest arrangement with di-protonated diaza-18-crown-6 in the cavity of the calixarenes as part of secondary coordination spheres of aquated europium(iii) ions.

  13. Unique case of a geminated supernumerary tooth with trifid crown

    Energy Technology Data Exchange (ETDEWEB)

    Ather, Amber; Ather, Hunaiza; Sheth, Sanket Milan; Muliya, Vidya Saraswathi [Manipal College of Dental Sciences, Manipal (Korea, Republic of)

    2012-09-15

    Gemination, a relatively uncommon dental anomaly, is characterized by its peculiar representation as a tooth with a bifid crown and a common root and root canal. It usually occurs in primary dentition. To come across gemination in a supernumerary tooth is a rare phenomenon. The purpose of this paper is to present a unique case of hyperdontia wherein gemination in an impacted supernumerary tooth resulted in a trifid crown unlike the usual bifid crown. The role of conventional radiographs as well as computed tomography, to accurately determine the morphology and spatial location, and to arrive at a diagnosis, is also emphasized in this paper.

  14. Reduction of HCCI combustion noise through piston crown design

    DEFF Research Database (Denmark)

    Pedersen, Troels Dyhr; Schramm, Jesper

    2010-01-01

    Seven shapes of piston crowns have been evaluated for their ability to reduce HCCI knock and transmission of combustion noise to the engine. The performance of each piston crown was evaluated with measurements of cylinder pressure, engine vibration and acoustic sound pressure measured one meter....... The largest and most consistent reduction in noise level was however achieved with a diesel bowl type piston. The increased surface area as well as the larger crevice volumes of the experimental piston crowns generally resulted in lower IMEP than the flat piston. While the crevice volumes can be reduced...... reduction as well as heat losses....

  15. Retention force of secondary crowns to copings after temporary cementation: the effect of crown material and luting agent.

    Science.gov (United States)

    Mundt, Torsten; Heinemann, Friedhelm; Golecki, Gudrun; Schwahn, Christian; Biffar, Reiner

    2010-12-01

    Tooth-implant supported restorations can be temporarily cemented if the natural abutments are protected by permanently cemented copings. This in vitro study investigated the retention forces of pure titanium crowns to milled titanium alloy copings and of cobalt-chromium crowns to copings made of electroplated gold after cementation with different luting agents. Five specimens per group were cemented with acrylic-urethane cement (inner crown surface preisolated with petroleum jelly) and provisional zinc oxide cement. The retention was measured using a universal testing machine and a dental device for crown removal. The differences between groups were compared using analysis of variance. The pull-off forces for the cobalt-chromium secondary crowns cemented on gold copings using zinc oxide cement were significantly higher (mean=144.5 N) than the other crown-cement combinations (32.2-54.4 N), which showed no significant differences in the retention force. The impulse number and magnitude of the dental device was usually low and showed no substantial differences between the crown-cement combinations. It can be concluded that the results of the clinical removal method for prostheses differ from the results of the pull-off test. The question which luting agent is the better choice for retrievable restorations remains unanswered without further clinical and laboratory studies.

  16. Extended complications of urethroplasty

    Directory of Open Access Journals (Sweden)

    Hosam S. Al-Qudah

    2005-08-01

    Full Text Available INTRODUCTION: An extensive study of complications following urethroplasty has never been published. We present 60 urethroplasty patients who were specifically questioned to determine every possible early and late complication. MATERIALS AND METHODS: Retrospective chart review of urethroplasty patients between August 2000 and March 2004. An "open format" questioning style allowed maximal patient reporting of all complications, no matter how minor. RESULTS: 60 patients underwent 62 urethroplasties (24 anterior anastomotic, 19 buccal mucosal and 10 fasciocutaneous, 9 posterior anastomotic with mean follow-up of 29 months. Early complications occurred in 40%, but only 3% were major (rectal injury and urosepsis. Early minor complications included scrotal swelling, scrotal ecchymosis and urinary urgency. Late complications occurred in 48%, but only 18% were significant (erectile dysfunction, chordee and fistula. Late minor complications included a feeling of wound tightness, scrotal numbness and urine spraying. Fasciocutaneous urethroplasty caused the most significant complications, and buccal mucus urethroplasty the least, while also resulting in the lowest recurrence rate (0%. CONCLUSIONS: Serious complications after urethroplasty (3% early and 18% late appear similar to those reported elsewhere, but minor bothersome complications appear to occur in much higher numbers than previously published (39% early and 40% late. While all the early complications were resolved and most (97% were minor, less than half of the late complications were resolved, although most (82% were minor. These complication rates should be considered when counseling urethroplasty patients, and generally tend to support the use of buccal mucosal onlay urethroplasty as it had the lowest rate of serious side effects.

  17. The energetic characterization of pineapple crown leaves.

    Science.gov (United States)

    Braga, R M; Queiroga, T S; Calixto, G Q; Almeida, H N; Melo, D M A; Melo, M A F; Freitas, J C O; Curbelo, F D S

    2015-12-01

    Energetic characterization of biomass allows for assessing its energy potential for application in different conversion processes into energy. The objective of this study is to physicochemically characterize pineapple crown leaves (PC) for their application in energy conversion processes. PC was characterized according to ASTM E871-82, E1755-01, and E873-82 for determination of moisture, ash, and volatile matter, respectively; the fixed carbon was calculated by difference. Higher heating value was determined by ASTM E711-87 and ash chemical composition was determined by XRF. The thermogravimetric and FTIR analyses were performed to evaluate the thermal decomposition and identify the main functional groups of biomass. PC has potential for application in thermochemical processes, showing high volatile matter (89.5%), bulk density (420.8 kg/m(3)), and higher heating value (18.9 MJ/kg). The results show its energy potential justifying application of this agricultural waste into energy conversion processes, implementing sustainability in the production, and reducing the environmental liabilities caused by its disposal.

  18. [Esthetic evaluation of Cerec 3D anterior crowns].

    Science.gov (United States)

    Yang, Jian; Feng, Hai-lan; Wei, Xiu-xia; Xing, Yan-xi; Jia, Lu; Zhou, Yong-sheng

    2012-03-27

    To observe the short-term effect of clinical application of Cerec 3D anterior crowns. A total of 16 patients were restored with 31 Cerec 3D anterior crowns. All restorations were stained before cementation. The evaluation started 1 week after luting. The restorations were examined in accordance with the modified US Public Health Service (USPHS) criteria at baseline and every 6 - 12 months. The observation period of 31 Cerec 3D anterior crowns varied from 8 to 33 months. The mean observation period was 22 months. All restorations scored A or B by modified USPHS standard. And 22 out of 31 restorations scored A for all criteria while 8 restorations scored B in color matching. Slight differences of translucency and chroma could be observed. Between baseline and follow-up examinations, insignificant shift from A-to B-rating occurred. Cerec 3D anterior crowns may achieve favorable short-term esthetic effects.

  19. Synthesis of Crown Ethers Containing a Rubicene Moiety

    Directory of Open Access Journals (Sweden)

    Mario Smet

    2000-03-01

    Full Text Available A symmetrically disubstituted derivative of the highly fluorescing and photostable rubicene was incorporated in a macrocycle using high dilution conditions and a hydroxyrubicene was functionalized with a modified aminobenzo-15-crown-5.

  20. Probing supramolecular complexation of cetylpyridinium chloride with crown ethers

    Science.gov (United States)

    Saha, Subhadeep; Roy, Mahendra Nath

    2017-11-01

    Supramolecular complexations of cetylpyridinium chloride with three comparable cavity dimension based crown ethers, namely, dibenzo-18-crown-6, 18-crown-6 and dicyclohexano-18-crown-6 have been explored and adequately compared in acetonitrile with the help of conductivity in a series of temperatures to reveal the stoichiometry of the three host-guest complexes. Programme based mathematical treatment of the conductivity data affords association constants for complexations from which the thermodynamic parameters were derived for better comprehension about the process. The interactions at molecular level have been explained and decisively discussed by means of FT-IR and 1H NMR spectroscopic studies that demonstrate H-bond type interactions as the primarily force of attraction for the investigated supramolecular complexations.

  1. Luminescent Lariat Aza-Crown Ether Carboxylic Acid

    Directory of Open Access Journals (Sweden)

    Burkhard König

    2010-03-01

    Full Text Available Lariat ethers are interesting recognition motifs in supramolecular chemistry. The synthesis of a luminescent lariat aza-crown ether with a carboxyl group appended by azide-alkyne (Huisgen cycloaddition is presented.

  2. Sentencing dangerous offenders: policy and practice in the Crown Court

    OpenAIRE

    Henham, R

    2001-01-01

    Analysis of Crown Courts' use of protective sentencing powers under s.80(2)(b), s.85, and s.109 of 2000 Act and whether preference for s.85 reflects fundamental flaw in leaving determination of "dangerousness" to judiciary.

  3. Fractal approach to computer-analytical modelling of tree crown

    International Nuclear Information System (INIS)

    Berezovskaya, F.S.; Karev, G.P.; Kisliuk, O.F.; Khlebopros, R.G.; Tcelniker, Yu.L.

    1993-09-01

    In this paper we discuss three approaches to the modeling of a tree crown development. These approaches are experimental (i.e. regressive), theoretical (i.e. analytical) and simulation (i.e. computer) modeling. The common assumption of these is that a tree can be regarded as one of the fractal objects which is the collection of semi-similar objects and combines the properties of two- and three-dimensional bodies. We show that a fractal measure of crown can be used as the link between the mathematical models of crown growth and light propagation through canopy. The computer approach gives the possibility to visualize a crown development and to calibrate the model on experimental data. In the paper different stages of the above-mentioned approaches are described. The experimental data for spruce, the description of computer system for modeling and the variant of computer model are presented. (author). 9 refs, 4 figs

  4. Development of post-fire crown damage mortality thresholds in ponderosa pine

    Science.gov (United States)

    James F. Fowler; Carolyn Hull Sieg; Joel McMillin; Kurt K. Allen; Jose F. Negron; Linda L. Wadleigh; John A. Anhold; Ken E. Gibson

    2010-01-01

    Previous research has shown that crown scorch volume and crown consumption volume are the major predictors of post-fire mortality in ponderosa pine. In this study, we use piecewise logistic regression models of crown scorch data from 6633 trees in five wildfires from the Intermountain West to locate a mortality threshold at 88% scorch by volume for trees with no crown...

  5. Crown profile equations for stand-grown western hemlock trees in northwestern Oregon.

    Science.gov (United States)

    David D. Marshall; Gregory P. Johnson; David W. Hann

    2003-01-01

    Crown profile equations were developed for stand-grown western hemlock(Tsuga heterophylla (Raf.) Sarg.) in northwest Oregon. The profile model uses a segmented approach, dividing the crown into an upper and lower portion at the point of the largest crown width (LCW). The model explains about 86% of the variation in crown width when LCW is known but...

  6. Root-Crown Relations of Young Sugar Maple and Yellow Birch

    Science.gov (United States)

    Carl H. Tubbs

    1977-01-01

    Young forest-grown sugar maple and yellow birch (1 to 6 inches d.b.h.) crowns were mapped and roots excavated. Crown dimensions were compared. Sugar maple roots usually terminated within a few feet of the crown perimeter. Yellow birch roots frequently terminated well outside crown perimeters and roots of birch were more irregularly distributed than those of maple....

  7. Radiolucency below the crown of mandibular horizontal incompletely impacted third molars and acute inflammation in men with diabetes

    Directory of Open Access Journals (Sweden)

    Minoru Yamaoka

    2009-05-01

    Full Text Available Minoru Yamaoka, Yusuke Ono, Masahide Ishizuka, Kouichi Yasuda, Takashi Uematsu, Kiyofumi FurusawaOral and Maxillofacial Surgery, Matsumoto Dental University, Shiojiri, Nagano 399-0781, JapanAbstract: Although mandibular third molar has a high risk of infection extending any complications, the influence of diabetes on radiolucency and acute inflammation in pericoronitis remains unclear. The present study was to evaluate whether radiolucency below the crown is related to acute inflammation in mandibular horizontal incompletely impacted third molars and to review the records of 140 men more than 45 years with and without diabetes. The odds ratio of exhibiting acute inflammation was 3.38 (95% CI: 1.13–10.16, p < 0.05 and that of exhibiting severe acute inflammation was 15.38 (95% CI: 3.56–66.49, p < 0.0001, indicating an association of acute pericoronitis in diabetes. The frequency of radiolucency below the crown and below the root in diabetics was similar to that in nondiabetics. However, the odds ratio of exhibiting both radiolucency below the crown and acute inflammation under the diabetic condition was 4.85 (95% CI: 1.60–14.73, p < 0.01, whereas that of diabetics showing both radiolucency below the root and acute inflammation was 0.46 (95% CI: 0.06–3.74, p = 0.74. Radiolucency below the crown and acute inflammation were associated with diabetes, but that below root and acute inflammation were not associated with diabetes, indicating that the region below the crown carries susceptibility to acute pericoronitis, whereas the periodontium shows a protective effect against acute pericoronitis.Keywords: radiolucency, acute inflammation, mandible, third molar, diabetes, periodontium

  8. Failure Probability of Three Designs of Zirconia Crowns.

    Science.gov (United States)

    Ramos, Gabriela Freitas; Monteiro, Evelyn Barbosa; Bottino, Marco Antonio; Zhang, Yu; Marques de Melo, Renata

    2015-01-01

    This study used a two-parameter Weibull analysis for evaluation of the lifespan of fully or partially porcelain-/glaze-veneered zirconia crowns after fatigue test. A sample of 60 first molars were selected and prepared for full-coverage crowns with three different designs (n = 20): traditional (crowns with zirconia framework covered with feldspathic porcelain), modified (crowns partially covered with veneering porcelain), and monolithic (full-contour zirconia crowns). All specimens were treated with a glaze layer. Specimens were subjected to mechanical cycling (100 N, 3 Hz) with a piston with a hemispherical tip (Ø = 6 mm) until the specimens failed or up to 2 × 10⁶ cycles. Every 500,000 cycles, the fatigue tests were interrupted and stereomicroscopy (10×) was used to inspect the specimens for damage. The authors performed Weibull analysis of interval data to calculate the number of failures in each interval. The types and numbers of failures according to the groups were: cracking (13 traditional, 6 modified) and chipping (4 traditional) of the feldspathic porcelain, followed by delamination (1 traditional) at the veneer/core interface and debonding (2 monolithic) at the cementation interface. Weibull parameters (β, scale; η, shape), with a two-sided confidence interval of 95%, were: traditional-1.25 and 0.9 × 10⁶ cycles; modified-0.58 and 11.7 × 10⁶ cycles; and monolithic-1.05 and 16.5 × 10⁶ cycles. Traditional crowns showed greater susceptibility to fatigue, the modified group presented higher propensity to early failures, and the monolithic group showed no susceptibility to fatigue. The modified and monolithic groups presented the highest number of crowns with no failures after the fatigue test. The three crown designs presented significantly different behaviors under fatigue. The modified and monolithic groups presented less probability of failure after 2 × 10⁶ cycles.

  9. Slow cooling protocol improves fatigue life of zirconia crowns.

    Science.gov (United States)

    Paula, Vitor G; Lorenzoni, Fabio C; Bonfante, Estevam A; Silva, Nelson R F A; Thompson, Van P; Bonfante, Gerson

    2015-02-01

    To compare the fatigue life and damage modes of zirconia crowns fabricated with and without framework design modification when porcelain veneered using a fast or slow cooling protocol. Composite resin replicas of a first molar full crown preparation were fabricated. Zirconia copings were milled as conventional (0.5mm even thickness, Zr-C, n=20,) or modified (lingual margin of 1.0mm thickness, 2.0mm height connected to two proximal struts of 3.5mm height, Zr-M, n=20). These groups were subdivided (n=10 each) according to the veneer cooling protocol employed: fast cooling (Zr-CFast and Zr-MFast) and slow cooling (Zr-CSlow and Zr-MSlow). Crowns were cemented and fatigued for 10(6) cycles in water. The number of cycles to failure was recorded and used to determine the interval databased 2-parameter probability Weibull distribution parameter Beta (β) and characteristic life value Eta (η). 2-parameter Weibull calculation presented β=5.53 and β=4.38 for Zr-MFast and Zr-CFast, respectively. Slow cooled crowns did not fail by completion of 10(6) cycles, thereby Weibayes calculation was applied. Increased fatigue life was observed for slow cooled crowns compared to fast cooled ones. Groups Zr-MFast and Zr-MSlow presented no statistical difference. Porcelain cohesive fractures were mainly observed in fast cooled groups. Slow cooled crowns presented in some instances inner cone cracks not reaching the zirconia/veneer interface. Improved fatigue life in tandem with the absence of porcelain fractures were observed in slow cooled crowns, regardless of framework design. Crowns fast cooled chiefly failed by porcelain cohesive fractures. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. Surgical crown lengthening: a periodontal and restorative interdisciplinary approach.

    Science.gov (United States)

    Parwani, Simran R; Parwani, Rajkumar N

    2014-01-01

    Surgical crown lengthening helps to provide an adequate retention form for proper tooth preparation, thus enabling dentists to create esthetically pleasing and healthy restorations. Long-term stability requires accurate diagnosis and development of a comprehensive treatment plan in each case. This sequence of events stresses the importance of communication between the restorative dentist and the periodontist. This article presents 2 cases that involve surgical crown lengthening (including mucoperiosteal flap and ostectomy) for the restoration of teeth.

  11. Mechanical performance of implant-supported posterior crowns.

    Science.gov (United States)

    de Kok, Paul; Kleverlaan, Cornelis J; de Jager, Niek; Kuijs, Ruud; Feilzer, Albert J

    2015-07-01

    The fracture of implant-supported restorations, especially of the veneering layer, is a common problem in dentistry. Monolithic ceramic or resin restorations might help solve this problem. The purpose of this in vitro study was to obtain additional insight into the risk of fracture of implant-supported restorations. Identical crowns (n=10) of 10 different ceramic and composite resin materials were cemented on conventional abutments on implant replicas embedded in polymethyl methacrylate blocks. The specimens were subjected to compressive load in a universal testing machine to record initial load to failure (ILF). Additionally, the flexural strength (FS), compressive strength (CS), and elastic modulus (E) of the investigated materials were determined. These results were used in a finite element analysis model of a composite resin and a lithium disilicate crown. Anatomic contour zirconia (Lava Plus) crowns had the highest ILF (6065 N), followed by lithium disilicate (IPS e.max) (2788 N) and the composite resin materials (Protemp 4, Majesty Flow, Telio CAD, Estenia C&B, Lava Ultimate, VITA Enamic) (2386 to 1935 N). Veneered zirconia (Lava) crowns showed the lowest ILF (1477 N). The highest FS, CS, and E were found for Lava Plus and IPS e.max. No direct relationship was found between ILF and the FS, CS, or E. The finite element analysis showed stresses that did not exceed the FS or CS of IPS e.max. The surface roughness of these crowns might have caused initial failure at relatively low stresses. In this laboratory study, monolithic implant-supported crowns showed a higher ILF than conventional veneered ceramic crowns. Monolithic ceramic restorations might perform better than composite resin crowns. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  12. Failure probability of three designs of zirconia crowns

    Science.gov (United States)

    Ramos, G. Freitas; Monteiro, E. Barbosa Carmona; Bottino, M.A.; Zhang, Y.; de Melo, R. Marques

    2015-01-01

    Objectives This study utilized a 2-parameter Weibull analysis for evaluation of lifetime of fully or partially porcelain-/glaze-veneered zirconia crowns after fatigue test. Methods Sixty first molars were selected and prepared for full-coverage crowns with three different designs(n = 20): Traditional –crowns with zirconia framework covered with feldspathic porcelain; Modified– crowns partially covered with veneering porcelain; and Monolithic–full-contour zirconia crowns. All specimens were treated with a glaze layer. Specimens were subjected to mechanical cycling (100N, 3Hz) with a piston with hemispherical tip (Ø=6 mm) until the specimens failed or up to 2×106 cycles. Every 500,000 cycles intervals, the fatigue tests were interrupted, and stereomicroscopy (10 X) was used to inspect the specimens for damage. We performed Weibull analysis of interval data to calculate the number of failures in each interval. Results The types and number of failures according to the groups were: cracking (Traditional-13, Modified-6) and chipping (Traditional-4) of the feldspathic porcelain, followed by delamination (Traditional-1) at the veneer/core interface and debonding (Monollithic-2) at the cementation interface. Weibull parameters (beta, scale; and eta, shape), with a two-sided confidence interval of 95%, were: Traditional – 1.25 and 0.9 × 106cycles; Modified– 0.58 and 11.7 × 106 cycles; and Monolithic – 1.05 and 16.5 × 106 cycles. Traditional crowns showed greater susceptibility to fatigue, the Modified group presented higher propensity to early failures, and the Monolithic group showed no susceptibility to fatigue. The Modified and Monolithic groups presented the highest number of crowns with no failures after the fatigue test. Conclusions The three crown designs presented significantly different behaviors under fatigue. The Modified and the Monolithic groups presented less probability to failure after 2×106cycles. PMID:26509988

  13. Variation in crown light utilization characteristics among tropical canopy trees.

    Science.gov (United States)

    Kitajima, Kaoru; Mulkey, Stephen S; Wright, S Joseph

    2005-02-01

    Light extinction through crowns of canopy trees determines light availability at lower levels within forests. The goal of this paper is the exploration of foliage distribution and light extinction in crowns of five canopy tree species in relation to their shoot architecture, leaf traits (mean leaf angle, life span, photosynthetic characteristics) and successional status (from pioneers to persistent). Light extinction was examined at three hierarchical levels of foliage organization, the whole crown, the outermost canopy and the individual shoots, in a tropical moist forest with direct canopy access with a tower crane. Photon flux density and cumulative leaf area index (LAI) were measured at intervals of 0.25-1 m along multiple vertical transects through three to five mature tree crowns of each species to estimate light extinction coefficients (K). Cecropia longipes, a pioneer species with the shortest leaf life span, had crown LAI <0.5. Among the remaining four species, crown LAI ranged from 2 to 8, and species with orthotropic terminal shoots exhibited lower light extinction coefficients (0.35) than those with plagiotropic shoots (0.53-0.80). Within each type, later successional species exhibited greater maximum LAI and total light extinction. A dense layer of leaves at the outermost crown of a late successional species resulted in an average light extinction of 61% within 0.5 m from the surface. In late successional species, leaf position within individual shoots does not predict the light availability at the individual leaf surface, which may explain their slow decline of photosynthetic capacity with leaf age and weak differentiation of sun and shade leaves. Later-successional tree crowns, especially those with orthotropic branches, exhibit lower light extinction coefficients, but greater total LAI and total light extinction, which contribute to their efficient use of light and competitive dominance.

  14. A clinical study comparing the supragingival plaque and gingivitis efficacy of a specially engineered sonic powered toothbrush with unique sensing and control technologies to a commercially available manual flat-trim toothbrush.

    Science.gov (United States)

    Nathoo, Salim; Mankodi, Suru; Mateo, Luis R; Chaknis, Patricia; Panagakos, Foti

    2012-01-01

    This study was designed to evaluate the efficacy of a new specially engineered sonic powered toothbrush with unique sensing and control technologies, as compared to a manual flat-trim toothbrush on supragingival plaque and established gingivitis. This examiner-blind, two-treatment, parallel clinical research study assessed plaque removal via the comparison of pre- to post-brushing after a single use, and again after four- and 12-weeks' use using the Rustogi Modification of the Modified Navy Plaque Index. This study also assessed gingivitis at four and 12 weeks using the Löe and Silness Gingival Index. Qualifying adult male and female subjects from the southern Florida area reported to the study site after refraining from any oral hygiene procedures for 24 hours, and from eating, drinking, and smoking for four hours. Following an examination for plaque (pre-brushing) and gingivitis, they were randomized (for both plaque and gingivitis) into two balanced groups, each group using one of the two study toothbrushes. Subjects were instructed to brush their teeth for two minutes under supervision with their assigned toothbrush according to the manufacturer's instructions, and commercially available toothpaste (Colgate Cavity Protection Toothpaste), after which they were again evaluated for plaque (post-brushing). Subjects were then dismissed from the study site with the toothpaste and their assigned toothbrush to use at home twice daily for the next 12 weeks. They again reported to the study site after four and 12 weeks of product use, at which time they were evaluated for plaque and gingivitis. Seventy-six out of 82 enrolled subjects complied with the protocol and completed the clinical study. The new specially engineered sonic powered toothbrush with unique sensing and control technologies provided statistically significant reductions in gingival and gingivitis severity index scores after four and 12 weeks of product use. The manual toothbrush provided a statistically

  15. Complications of nephrotic syndrome

    Directory of Open Access Journals (Sweden)

    Se Jin Park

    2011-08-01

    Full Text Available Nephrotic syndrome (NS is one of the most common glomerular diseases that affect children. Renal histology reveals the presence of minimal change nephrotic syndrome (MCNS in more than 80% of these patients. Most patients with MCNS have favorable outcomes without complications. However, a few of these children have lesions of focal segmental glomerulosclerosis, suffer from severe and prolonged proteinuria, and are at high risk for complications. Complications of NS are divided into two categories: disease-associated and drug-related complications. Disease-associated complications include infections (e.g., peritonitis, sepsis, cellulitis, and chicken pox, thromboembolism (e.g., venous thromboembolism and pulmonary embolism, hypovolemic crisis (e.g., abdominal pain, tachycardia, and hypotension, cardiovascular problems (e.g., hyperlipidemia, acute renal failure, anemia, and others (e.g., hypothyroidism, hypocalcemia, bone disease, and intussusception. The main pathomechanism of disease-associated complications originates from the large loss of plasma proteins in the urine of nephrotic children. The majority of children with MCNS who respond to treatment with corticosteroids or cytotoxic agents have smaller and milder complications than those with steroid-resistant NS. Corticosteroids, alkylating agents, cyclosporin A, and mycophenolate mofetil have often been used to treat NS, and these drugs have treatment-related complications. Early detection and appropriate treatment of these complications will improve outcomes for patients with NS.

  16. Cardiovascular complications of cirrhosis

    DEFF Research Database (Denmark)

    Møller, S; Henriksen, Jens Henrik Sahl

    2008-01-01

    Cardiovascular complications of cirrhosis include cardiac dysfunction and abnormalities in the central, splanchnic and peripheral circulation, and haemodynamic changes caused by humoral and nervous dysregulation. Cirrhotic cardiomyopathy implies systolic and diastolic dysfunction and electrophysi......Cardiovascular complications of cirrhosis include cardiac dysfunction and abnormalities in the central, splanchnic and peripheral circulation, and haemodynamic changes caused by humoral and nervous dysregulation. Cirrhotic cardiomyopathy implies systolic and diastolic dysfunction....... The clinical significance of cardiovascular complications and cirrhotic cardiomyopathy is an important topic for future research, and the initiation of new randomised studies of potential treatments for these complications is needed....

  17. Fracture load of different crown systems on zirconia implant abutments.

    Science.gov (United States)

    Albrecht, T; Kirsten, A; Kappert, H F; Fischer, H

    2011-03-01

    The purpose of this study was to evaluate the fracture load of single zirconia abutment restorations using different veneering techniques and materials. The abutment restorations were divided into 6 groups with 20 samples each: test abutments (control group A), lithium disilicate ceramic crowns bonded on incisor abutments (group B), leucite ceramic crowns bonded on incisor abutments (group C), premolar abutments directly veneered with a fluor apatite ceramic (group D (layered) and group E (pressed)) and premolar abutments bonded with lithium disilicate ceramic crowns (group F). The fracture load of the restorations was evaluated using a universal testing machine. Half of each group was artificially aged (chewing simulation and thermocycling) before evaluating the fracture load with the exception of the test abutments. The fracture load of the test abutments was 705 ± 43N. Incisor abutments bonded with lithium disilicate or leucite ceramic crowns (groups B and C) showed fracture loads of about 580N. Premolar restorations directly veneered with fluor apatite ceramic (groups D and E) showed fracture loads of about 850N. Premolar restorations bonded with lithium disilicate ceramic crowns (group F) showed fracture loads of about 1850N. The artificial ageing showed no significant influence on the strength of the examined restorations. All ceramic crowns made of lithium disilicate glass-ceramic, adhesively bonded to premolar abutments showed the highest fracture loads in this study. However, all tested groups can withstand physiological bite forces. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Consequences of crown shortening canine teeth in Greenland sled dogs.

    Science.gov (United States)

    Kortegaard, H E; Anthony Knudsen, T; Dahl, S; Agger, J F G; Eriksen, T

    2015-04-01

    To evaluate the consequences of crown shortening, focusing on the prevalence of pulp exposure and periapical pathology in Greenland sled dogs that had had their canine crowns shortened at an early age. Five cadaver heads and 54 sled dogs underwent an oral examination for dental fractures and pulp exposure of canines. All canines were radiographed and evaluated for periapical pathology. The prevalence of canine pulp exposure in 12 (5 heads and 7 dogs) crown shortened dogs was 91 · 7%, and 21 · 3% in 47 not-crown shortened dogs. A significant (P canines in the crown shortened group compared to the not-crown shortened group was seen with a relative risk of 4 · 3 on a dog basis and a relative risk of 12 · 2 on a tooth basis. In dogs with pulp exposure of canines (n = 51) the prevalence of periapical pathology was 82 · 4%, but only 0 · 8% in dogs without pulp exposure (n = 133) resulting in a significant (relative risk, 109 · 5; P < 0 · 001) risk of periapical pathology in teeth with pulp exposure compared to teeth without pulp exposure. The high risk of periapical pathology observed in teeth with pulp exposure confirms that these teeth should not be neglected in affected dogs. © 2015 British Small Animal Veterinary Association.

  19. Antimicrobial efficacy of chemical disinfectants on contaminated full metal crowns.

    Science.gov (United States)

    Orsi, Iara Augusta; Villabona, Camilo Andrés; Kameoka, Eliana; Ferreira, Marly Christiènne C G; Ito, Izabel Yoko; Saravia, Marta Estela

    2010-01-01

    Prosthetic restorations that have been tried in the patient's mouth are potential sources of infection. In order to avoid cross-infection, protocols for infection control should be established in dental office and laboratory. This study evaluated the antimicrobial efficacy of disinfectants on full metal crowns contaminated with microorganisms. Full crowns cast in a Ni-Cr alloy were assigned to one control group (n=6) and 5 experimental groups (n=18). The crowns were placed in flat-bottom glass balloons and were autoclaved. A microbial suspension of each type of strain - S. aureus, P. aeruginosa, S. mutans, E. faecalis and C. albicans- was aseptically added to each experimental group, the crowns being allowed for contamination during 30 min. The contaminated specimens were placed into recipients with the chemical disinfectants (1% and 2% sodium hypochlorite and 2% glutaraldehyde) for 5, 10 and 15 min. Thereafter, the crowns were placed into tubes containing different broths and incubated at 35ºC. The control specimens were contaminated, immersed in distilled water for 20 min and cultured in Thioglycollate broth at 35ºC. Microbial growth assay was performed by qualitative visual examination after 48 h, 7 and 12 days. Microbial growth was noticed only in the control group. In the experimental groups, turbidity of the broths was not observed, regardless of the strains and immersion intervals, thus indicating absence of microbial growth. In conclusion, all chemical disinfectants were effective in preventing microbial growth onto full metal crowns.

  20. Consequences of crown shortening canine teeth in Greenland sled dogs

    DEFF Research Database (Denmark)

    Kortegaard, H E; Anthony Knudsen, T; Dahl, S

    2015-01-01

    OBJECTIVES: To evaluate the consequences of crown shortening, focusing on the prevalence of pulp exposure and periapical pathology in Greenland sled dogs that had had their canine crowns shortened at an early age. METHODS: Five cadaver heads and 54 sled dogs underwent an oral examination for dental...... fractures and pulp exposure of canines. All canines were radiographed and evaluated for periapical pathology. RESULTS: The prevalence of canine pulp exposure in 12 (5 heads and 7 dogs) crown shortened dogs was 91 · 7%, and 21 · 3% in 47 not-crown shortened dogs. A significant (P ... exposure of the canines in the crown shortened group compared to the not-crown shortened group was seen with a relative risk of 4 · 3 on a dog basis and a relative risk of 12 · 2 on a tooth basis. In dogs with pulp exposure of canines (n = 51) the prevalence of periapical pathology was 82 · 4%, but only 0...

  1. Prospective cohort clinical study assessing the 5-year survival and success of anterior maxillary zirconia-based crowns with customized zirconia copings.

    Science.gov (United States)

    Dogan, Sami; Raigrodski, Ariel J; Zhang, Hai; Mancl, Lloyd A

    2017-02-01

    Studies evaluating anterior zirconia-based crowns are limited. The purpose of this prospective cohort clinical study was to assess the efficacy of zirconia-based anterior maxillary crowns with 0.3-mm customized copings at the cervical third and anatomical design elsewhere for up to 5 years of service. Eighteen participants who required an anterior maxillary crown (n=20) and who had signed a consent form approved by the University of Washington Health Sciences Center Human Subjects Division were enrolled. All preparations were standardized and prepared with an occlusal reduction of 1.5 to 2 mm and an axial reduction of 1 to 1.5 mm with 10 degrees of convergence angle. All finish lines were located on the sound tooth structure. Zirconia copings (Lava; 3M ESPE) were custom designed and milled to a 0.3-mm thickness at the cervical third and with selective thickness elsewhere to support the veneering porcelain. All restorations were luted with self-etching self-adhesive composite resin cement. Recall appointments were at 2 weeks, 6 months, and 12 months, and annually thereafter for 5 years. Modified Ryge criteria were used to assess the clinical fracture measurements, esthetics, marginal discoloration, marginal adaptation, radiographic proximal recurrent caries, and periapical pathoses. Descriptive statistics and 95% confidence intervals were used to describe the number and rate of complications and self-reported satisfaction with the crowns. Twenty crowns with a mean follow-up of 58.7 months were evaluated. All crowns were rated as Alfa for fracture measurements (smooth surface, no fracture/chipping). Twelve crowns were rated esthetically as Romeo (no mismatch in color and shade) and 8 as Sierra (mismatch in color and shade within normal range). Twelve crowns were rated as Alfa (no visible evidence of crevice) and 8 as Bravo (visible evidence of crevice, no penetration of explorer) for marginal integrity. Nineteen were rated as Alfa (no discoloration) and 1 as Bravo

  2. Fracture resistance and failure modes of CEREC endo-crowns and conventional post and core-supported CEREC crowns

    Directory of Open Access Journals (Sweden)

    Chia-Yu Chang

    2009-09-01

    Conclusion: The bonded ceramic endo-crowns showed a significantly higher fracture resistance than the classic reinforced and designed group and, therefore, offer a feasible alternative for severely damaged teeth.

  3. Suitability of Secondary PEEK Telescopic Crowns on Zirconia Primary Crowns: The Influence of Fabrication Method and Taper

    Directory of Open Access Journals (Sweden)

    Susanne Merk

    2016-11-01

    Full Text Available This study investigates the retention load (RL between ZrO2 primary crowns and secondary polyetheretherketone (PEEK crowns made by different fabrication methods with three different tapers. Standardized primary ZrO2 crowns were fabricated with three different tapers: 0°, 1°, and 2° (n = 10/group. Ten secondary crowns were fabricated (i milled from breCam BioHPP blanks (PM; (ii pressed from industrially fabricated PEEK pellets (PP (BioHPP Pellet; or (iii pressed from granular PEEK (PG (BioHPP Granulat. One calibrated operator adjusted all crowns. In total, the RL of 90 secondary crowns were measured in pull-off tests at 50 mm/min, and each specimen was tested 20 times. Two- and one-way ANOVAs followed by a Scheffé’s post-hoc test were used for data analysis (p < 0.05. Within crowns with a 0° taper, the PP group showed significantly higher retention load values compared with the other groups. Among the 1° taper, the PM group presented significantly lower retention loads than the PP group. However, the pressing type had no impact on the results. Within the 2° taper, the fabrication method had no influence on the RL. Within the PM group, the 2° taper showed significantly higher retention load compared with the 1° taper. The taper with 0° was in the same range value as the 1° and 2° tapers. No impact of the taper on the retention value was observed between the PP groups. Within the PG groups, the 0° taper presented significantly lower RL than the 1° taper, whereas the 2° taper showed no differences. The fabrication method of the secondary PEEK crowns and taper angles showed no consistent effect within all tested groups.

  4. complications des otites moyennes chroniques complications of ...

    African Journals Online (AJOL)

    Ann Otolaryngol Chir Cervico Fac. 1995;112 :317-23. 15- Cabral D.A, Flodmark O, Farell K, Speert D.P. Prospective study of computed tomograph in acute bacterial meningitis. J Pediatr 1987;. 111: 201-5. 16- Geyik M.F, Kologlu O.F, Hosoglu S, Ayaz C. Acute bacterial menin- gitidis as a complication of otitis media and ...

  5. Cryptococcal meningitis complicating sarcoidosis

    NARCIS (Netherlands)

    Leonhard, Sonja E.; Fritz, Daan; van de Beek, Diederik; Brouwer, Matthijs C.

    2016-01-01

    Cryptococcal meningitis is an uncommon but severe complication of sarcoidosis. We present 2 patients with cryptococcal meningitis complicating sarcoidosis and compared findings with 38 cases reported in the literature. When analyzing our patients and 38 cases reported in the literature, we found

  6. Fracture load of monolithic CAD/CAM lithium disilicate ceramic crowns and veneered zirconia crowns as a posterior implant restoration.

    Science.gov (United States)

    Kim, Jee Hwan; Lee, Su-Jeong; Park, Jun Sub; Ryu, Jae Jun

    2013-02-01

    To compare the fracture load and failure mode of the monolithic lithium disilicate crown (e.max group) and 2 types of veneered zirconia crowns, hand layer (ZV group) and heat pressed (ZP group), as a posterior implant-supported restoration. A total of 24 all-ceramic crowns for molar tooth were fabricated using the computer-aided design/computer-assisted manufacture (CAD/CAM) system. The e.max group crowns and zirconia copings for ZV and ZP groups were fabricated using a Cerec milling unit. The ZV group was fabricated using a hand-layer veneering method, and the ZP group using a heat-pressing method. All crowns were luted to the abutments, which were connected to implant fixtures, using resin cement. Fracture load was measured using the universal testing machine, and the fracture surface was evaluated by scanning electron microscopy. The ZP group showed significantly higher fracture load (5229.3 N) compared with the e.max group (3852.1 N) and ZV group (3100.3 N). All fractures in the ZV group occurred in the veneered layer. Monolithic CAD/CAM lithium disilicate crowns are applicable to posterior implant-supported restorations because the fracture load was higher than the average occlusal force.

  7. Crown fracture: Failure load, stress distribution, and fractographic analysis.

    Science.gov (United States)

    Campos, Roberto E; Soares, Paulo V; Versluis, Antheunis; de O Júnior, Osmir Batista; Ambrosano, Gláucia M B; Nunes, Isabella Ferola

    2015-09-01

    The outcomes from load-to-failure tests may not be applicable to clinical situations. The purpose of this study was to critically evaluate the efficacy of load-to-failure tests in the investigation of the fracture load and pattern of metal-free crowns. Four groups were formed from 128 bovine roots restored with metal posts, resin cores, and feldspathic, leucite, or lithium disilicate ceramic systems or polymer crowns. Each group was divided into 4 (n=8) according to the cement: zinc phosphate, self-adhesive resin, autopolymerizing resin, and glass ionomer. Mean fracture loads from compressive tests were submitted to ANOVA and Tukey HSD test. Finite element and fractographic analyses were performed and associated with the fracture load and pattern. Significantly higher fracture load values were obtained for the lithium disilicate ceramic, but finite element and fractographic analyses showed that the cement effect could not be determined. The finite element analysis showed the cement likely affected the fracture pattern, confirmed that stresses in the cements were little affected by the crown materials, and found that the stressed conditions were lowest in the lithium disilicate compared with other crowns for all cement combinations. The stressed conditions in the crowns depended more on the adhesive properties than on the elastic modulus of the cement materials. The level of the stressed condition in the crowns at the occlusal surface was about the same or higher than along their cement interface, consistent with the fractography, which indicated fractures starting at the load point. Higher stress levels in the crowns corresponded with a lower number of catastrophic fractures, and higher stresses in the cements seemed to reduce the number of catastrophic fracture patterns. The highest stressed conditions occurred along the occlusal surface for crown materials with a low elastic modulus or in combination with adhesive cements. The method used was not appropriate

  8. Clinical Performance of One-Piece, Screw-Retained Implant Crowns Based on Hand-Veneered CAD/CAM Zirconia Abutments After a Mean Follow-up Period of 2.3 Years.

    Science.gov (United States)

    Schnider, Nicole; Forrer, Fiona Alena; Brägger, Urs; Hicklin, Stefan Paul

    The aim of this study was to evaluate the clinical performance of one-piece, screw-retained implant crowns based on hand-veneered computer-aided design/computer-aided manufacture (CAD/CAM) zirconium dioxide abutments with a crossfit connection at least 1 year after insertion of the crown. Consecutive patients who had received at least one Straumann bone level implant and one-piece, screw-retained implant crowns fabricated with CARES zirconium dioxide abutments were reexamined. Patient satisfaction, occlusal and peri-implant parameters, mechanical and biologic complications, radiologic parameters, and esthetics were recorded. A total of 50 implant crowns in the anterior and premolar region were examined in 41 patients. The follow-up period of the definitive reconstructions ranged from 1.1 to 3.8 years. No technical and no biologic complications had occurred. At the reexamination, 100% of the implants and reconstructions were in situ. Radiographic evaluation revealed a mean distance from the implant shoulder to the first visible bone-to-implant contact of 0.06 mm at the follow-up examination. Screw-retained crowns based on veneered CAD/CAM zirconium dioxide abutments with a crossfit connection seem to be a promising way to replace missing teeth in the anterior and premolar region. In the short term, neither failures of components nor complications were noted, and the clinical and radiographic data revealed stable hard and soft tissue conditions.

  9. Clinical evaluation of 1,132 zirconia-based single crowns: a retrospective cohort study from the AIOP clinical research group.

    Science.gov (United States)

    Monaco, Carlo; Caldari, Mauro; Scotti, Roberto

    2013-01-01

    The aim of this retrospective cohort study was to gather the outcomes of zirconia single crowns made by 16 members of the Italian Academy of Prosthetic Dentistry (AIOP) over a time period of up to 5 years. A total of 398 patients treated in private practices with 1,132 zirconia-based single-crown restorations made on natural teeth from January 2005 to July 2010 were included. Three hundred forty-three anterior restorations (30.3%) and 789 posterior crowns (69.7%) were made with 16 types of zirconia, using primarily chamfer or knife-edge tooth preparation, and examined according to the esthetic, functional, and biologic criteria. To evaluate the relationship of parafunction with mechanical failure, patients with clenching or bruxism were not excluded from the study group. The cumulative survival rate of all restorations was 98.1%, while the cumulative success rate was 94.3%. Functional criteria had the highest number of failures. The odds ratio (OR) for all restorations was calculated to clarify the relationship between patients who were subject/not subject to parafunctions and technical complications; the OR was 2.60. An association between parafunction and mechanical failure was found in patients with severe parafunction. Porcelain-veneered zirconia single crowns with chamfer and knife-edge preparations showed good clinical results over a period of up to 5 years. Technical complications were few and were limited primarily to patients with parafunction.

  10. Crown Group Lejeuneaceae and Pleurocarpous Mosses in Early Eocene (Ypresian Indian Amber.

    Directory of Open Access Journals (Sweden)

    Jochen Heinrichs

    Full Text Available Cambay amber originates from the warmest period of the Eocene, which is also well known for the appearance of early angiosperm-dominated megathermal forests. The humid climate of these forests may have triggered the evolution of epiphytic lineages of bryophytes; however, early Eocene fossils of bryophytes are rare. Here, we present evidence for lejeuneoid liverworts and pleurocarpous mosses in Cambay amber. The preserved morphology of the moss fossil is inconclusive for a detailed taxonomic treatment. The liverwort fossil is, however, distinctive; its zig-zagged stems, suberect complicate-bilobed leaves, large leaf lobules, and small, deeply bifid underleaves suggest a member of Lejeuneaceae subtribe Lejeuneinae (Harpalejeunea, Lejeunea, Microlejeunea. We tested alternative classification possibilities by conducting divergence time estimates based on DNA sequence variation of Lejeuneinae using the age of the fossil for corresponding age constraints. Consideration of the fossil as a stem group member of Microlejeunea or Lejeunea resulted in an Eocene to Late Cretaceous age of the Lejeuneinae crown group. This reconstruction is in good accordance with published divergence time estimates generated without the newly presented fossil evidence. Balancing available evidence, we describe the liverwort fossil as the extinct species Microlejeunea nyiahae, representing the oldest crown group fossil of Lejeuneaceae.

  11. Dosimetric distribution of the surroundings of different dental crowns and implants during LINAC photon irradiation

    Science.gov (United States)

    Chang, Kwo-Ping; Lin, Wei-Ting; Shiau, An-Cheng; Chie, Yu-Huang

    2014-11-01

    In radiotherapy of the head and neck, metal dentures or implants will increase the risk of complications such as mucositis and osteoradionecrosis. The aim of this study is to explore the back scatter effect of commercially available dental metal alloys on the mucosa and bone under 6 MV LINAC irradiation. The Monte Carlo method has been employed to calculate the dose distribution in the heterogeneous media of the designed oral phantom based on the oral cavity geometry. Backscatter dose increases up to a maximum of 53%, and is primarily dependent on the physical density and electron density of the metal crown alloy. Ceramic metal crowns have been quantified to increase backscatter dose up to 10% on mucosa. Ceramic serves as an inherent shield of mucosa. The backscatter dose will be greater for a small field size if the tumor is located at a deeper region. Titanium implants will increase the backscatter dose by 13% to bone but will not affect the mucosa. QC-20 (polystyrene resin) is recommended as a shield material (3 mm) to eliminate the backscatter dose on mucosa due to the high density metals.

  12. Ceramometal crowns and bridges. Focus on failures.

    Science.gov (United States)

    Bell, A M; Kurzeja, R; Gamberg, M G

    1985-10-01

    There are numerous factors that can have an adverse or beneficial effect upon the esthetic appearance of a ceramometal restoration. Some of these factors are beyond the influence of the dentist unless he or she is aware of them. As knowledgable practicing dentists, they have the ability to prescribe for their patients in such a manner as to achieve greater success and, in turn, greater patient acceptance and recognition. These are the rewards of a successful crown and bridge practice, and the ceramometal restoration is the basic state of the art prosthesis in present use. Knowing how to take a shade under the proper lighting conditions is generally well taught as part of the dental school curriculum, but the knowledge that shade guides are manufactured with built in idiosyncrasies of color variations from guide to guide is an enlightening experience. O'Brien of the Department of Dental Materials at the University of Michigan School of Dentistry clearly demonstrated the variabilities of color intensities between porcelain manufacturers. Laboratory technicians have been frustrated by the inconsistency of shades of porcelains from one lot number to another. It is now more fully understood that fluorescence is an important factor in patient satisfaction, as patients observe and have their restorations seen under differing lighting conditions. The type of alloy used in the ceramometal combination can have an effect upon the esthetic result. The wider use of silver-palladium alloys requires that the porcelain employed be of a nongreening nature, or else the final glazed prosthesis will give off a greenish cast. The ability of the opaque to block out the metal substructure while blending with the gingival and incisal shades eliminates the graying out, which can be esthetically objectionable to the patient. However, one of the most important considerations in aesthetic ceramometal restorations is the correct anatomy, placement, and harmonious blending with the oral and

  13. Complications of Rhinitis.

    Science.gov (United States)

    Keswani, Anjeni; Peters, Anju T

    2016-05-01

    Chronic rhinitis involves inflammation of the upper airways. An association with comorbid conditions, such as rhinosinusitis, asthma, and chronic obstructive pulmonary disease, has been commonly observed in epidemiologic studies. The underlying pathogenesis of these disorders may be similar. Complications of rhinitis include sleep disturbances, learning impairment, and decreased quality of life. It is vital to recognize the complications of rhinitis so that treatment strategies can address rhinitis as well as its comorbidities and complications in a coordinated manner. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Imaging of osteochondroma complications

    International Nuclear Information System (INIS)

    Gomes, Fernando Santos Emerich; Lewin, Fabio; Mariotti, Guilherme Cayres; Capasso Filho, Mauro; Yamaguchi, Claudia Kazue; Cruz, Rafael O.; Baptista, Pedro Pericles Ribeiro; Yonamine, Eduardo Sadao; Prospero, Jose Donato

    2007-01-01

    Osteochondroma is the most common entity beyond all the known osseous tumors. It is a lesion with a high enlargement capacity and a continuous growing in some cases, and it may determine complications, mainly due to mass effect. It may be present in a solitary or multiple forms, and the last one is related with a higher tendency to sarcomatous transformation, which is the most frightening complication. The purpose of the present study is to demonstrate, through an iconographic assay, the most common complications caused by the osteochondromas, making the correlation of its clinical and radiological aspects. (author)

  15. Management of tetanus complication

    Science.gov (United States)

    Somia, I. K. A.

    2018-03-01

    The mortality rate of tetanus is still high; it is because of various complications due to muscle spasms, autonomic dysfunction, as well as due to prolonged critical care. Management of tetanus with its complications is in intensive care facilities. Management goals include stopping toxin production, neutralization of unbound toxin, management of the airway, muscle spasm control, treatment of autonomic dysfunction and general supportive management. Currently, diazepam is still an effective medication to control of muscle spasm and rigidity. Therapy for autonomic dysfunction that supported by evidence is MgSO4. Also, general supportive management for long-term care remains necessary to prevent other complications such as thromboembolism, infection, malnutrition, and others.

  16. Direct composite restoration of permanent anterior teeth uncomplicated crown fractures

    Directory of Open Access Journals (Sweden)

    Ashley Evans Nicholas

    2018-01-01

    Full Text Available An uncomplicated crown fracture is a fracture that involves only the tooth enamel or the dentin and tooth enamel without any damage or exposure to the pulp. Crown fracture of the anterior teeth usually caused by traumatic forces such as falls, accidents, violence, or sports activities. Traumatic injuries of the oral region frequently involve the anterior teeth, especially maxillary incisors due to the anatomic factors which may affect the functional and aesthetical values of the teeth. The objective of this literature study was to know more about uncomplicated crown fracture of the anterior teeth and its restoration. This research was a literature study performed by researching, highlighting various interesting facts and compiling the relevant published journals. The most common and ideal direct restoration of the anterior teeth was the composite resin restoration. The anterior teeth restoration was considered to be a complex and challenging case to solves due to the fact that besides reconstructing the tooth and regaining the function, the aesthetical aspect was also becoming the main objectives. The permanent anterior teeth uncomplicated crown fracture was the most common case of tooth fractures which was mainly caused by traumatic injuries such as falls, accidents, excessive forces, violence, and also sports activities. Dental injuries of the anterior teeth also affected the aesthetical properties and the function of the tooth. Composite resin restoration was able to performed directly on the permanent anterior teeth uncomplicated crown fracture.

  17. The use of stainless steel crowns: a systematic literature review.

    Science.gov (United States)

    Seale, N Sue; Randall, Ros

    2015-01-01

    The purpose was to review the published literature on stainless steel crowns (SSCs) from 2002 to the present as an update to an earlier review published in 2002. Included were published papers on clinical studies, case series, and laboratory testing on SSCs (including esthetic SSCs and the Hall technique) in peer-reviewed journals. Study quality and strength of evidence presented were assessed for papers reporting clinical results for SSCs as a primary study outcome using a list of weighting criteria. Sixty-one papers fulfilled the inclusion criteria (24 papers on 22 clinical studies, three case reports, 21 reviews and surveys, and 13 laboratory testing reports on SSCs and esthetic preformed metal crowns for primary and permanent molar teeth). Ten clinical studies achieved weighting scores ranging from 68 percent to 26 percent, with the two highest scoring studies (68 percent and 63 percent) considered good quality. Within the confines of the studies reviewed, primary molar esthetic crowns and SSCs had superior clinical performance as restoratives for posterior primary teeth, and the Hall technique was shown to have validity. No clinical studies were available on zirconia crowns. Further well-designed prospective studies on primary molar esthetic crowns and the Hall technique are needed.

  18. Crown sealing and buckling instability during water entry of spheres

    KAUST Repository

    Marston, J. O.

    2016-04-05

    We present new observations from an experimental investigation of the classical problem of the crown splash and sealing phenomena observed during the impact of spheres onto quiescent liquid pools. In the experiments, a 6 m tall vacuum chamber was used to provide the required ambient conditions from atmospheric pressure down to of an atmosphere, whilst high-speed videography was exploited to focus primarily on the above-surface crown formation and ensuing dynamics, paying particular attention to the moments just prior to the surface seal. In doing so, we have observed a buckling-type azimuthal instability of the crown. This instability is characterised by vertical striations along the crown, between which thin films form that are more susceptible to the air flow and thus are drawn into the closing cavity, where they atomize to form a fine spray within the cavity. To elucidate to the primary mechanisms and forces at play, we varied the sphere diameter, liquid properties and ambient pressure. Furthermore, a comparison between the entry of room-temperature spheres, where the contact line pins around the equator, and Leidenfrost spheres (i.e. an immersed superheated sphere encompassed by a vapour layer), where there is no contact line, indicates that the buckling instability appears in all crown sealing events, but is intensified by the presence of a pinned contact line. © 2016 Cambridge University Press.

  19. Effect of cements on fracture resistance of monolithic zirconia crowns

    Science.gov (United States)

    Nakamura, Keisuke; Mouhat, Mathieu; Nergård, John Magnus; Lægreid, Solveig Jenssen; Kanno, Taro; Milleding, Percy; Örtengren, Ulf

    2016-01-01

    Abstract Objectives The present study investigated the effect of cements on fracture resistance of monolithic zirconia crowns in relation to their compressive strength. Materials and methods Four different cements were tested: zinc phosphate cement (ZPC), glass-ionomer cement (GIC), self-adhesive resin-based cement (SRC) and resin-based cement (RC). RC was used in both dual cure mode (RC-D) and chemical cure mode (RC-C). First, the compressive strength of each cement was tested according to a standard (ISO 9917-1:2004). Second, load-to-failure test was performed to analyze the crown fracture resistance. CAD/CAM-produced monolithic zirconia crowns with a minimal thickness of 0.5 mm were prepared and cemented to dies with each cement. The crown–die samples were loaded until fracture. Results The compressive strength of SRC, RC-D and RC-C was significantly higher than those of ZPC and GIC (p crown between the groups. Conclusion The values achieved in the load-to-failure test suggest that monolithic zirconia crowns with a minimal thickness of 0.5 mm may have good resistance against fracture regardless of types of cements. PMID:27335900

  20. Museum security and the Thomas Crown Affair.

    Energy Technology Data Exchange (ETDEWEB)

    Michaud, E. C. (Nuclear Engineering Division)

    2010-01-01

    Over the years, I've daydreamed about stealing a Vermeer, a Picasso, or Rembrandt. It tickles me, as much as watching the reboot of The Thomas Crown Affair. Why is it, do you suppose, so much fun to think about stealing a world renowned piece off the wall of a major metropolitan museum? Is it the romantic thoughts of getting away with it, walking past infrared detectors, and pressure sensors ala Indiana Jones with the sack of sand to remove the idol without triggering the security system? Is it the idea of snatching items with such fantastic prices, where the romance of possessing an item of such value is less intoxicating than selling it to a private collector for it to never be seen again? I suspect others share my daydreams as they watch theater or hear of a brazen daylight heist at museums around the world, or from private collections. Though when reality sets in, the mind of the security professional kicks in. How could one do it, why would one do it, what should you do once it's done? The main issue a thief confronts when acquiring unique goods is how to process or fence them. They become very difficult to sell because they are one-of-a-kind, easy to identify, and could lead to the people involved with the theft. The whole issue of museum security takes up an ironic twist when one considers the secretive British street artist 'Banksy'. Banksy has made a name for himself by brazenly putting up interesting pieces of art in broad daylight (though many critics don't consider his work to be art) on building walls, rooftops, or even museums. I bring him up for a interesting take on what may become a trend in museum security. In March of 2005, Banksy snuck a piece of his called 'Vandalized Oil Painting' into the Brooklyn Museum's Great Historical Painting Wing, plus 3 other pieces into major museums in New York. Within several days, 2 paintings had been torn down, but 2 stayed up much longer. In his home country of the UK, a

  1. Fracture Strength After Fatigue Loading of Lithium Disilicate Pressed Zirconia Crowns.

    Science.gov (United States)

    Kim, So-Yeun; Choi, Jae-Won; Ju, Sung-Won; Ahn, Jin-Soo; Yoon, Mi-Jung; Huh, Jung-Bo

    2016-01-01

    The aim of this study was to evaluate the fracture resistance of fatigued lithium disilicate pressed zirconia crowns versus other ceramic crowns. Lithium disilicate pressed zirconia, fluorapatite pressed zirconia, monolithic lithium disilicate, and monolithic zirconia crowns were fabricated. Cyclic and static loadings were applied to the mesiobuccal cusp tip after thermocycling and fracture strengths were recorded. Fatigued lithium disilicate pressed zirconia crowns were found to have a fracture resistance of 9,117.81 ± 727.04 N, compared with 9,240.61 ± 887.21 N for monolithic zirconia crowns, 3,030.18 ± 1,505.83 N for fluorapatite pressed zirconia crowns, and 4,173.94 ± 877.46 N for monolithic lithium disilicate crowns (P = .001). This in vitro study shows that fatigued lithium disilicate pressed zirconia and monolithic zirconia crowns have better fracture resistance than fluorapatite pressed zirconia and monolithic lithium disilicate crowns.

  2. Cardiovascular complications of cirrhosis

    DEFF Research Database (Denmark)

    Møller, S; Henriksen, Jens Henrik Sahl

    2008-01-01

    Cardiovascular complications of cirrhosis include cardiac dysfunction and abnormalities in the central, splanchnic and peripheral circulation, and haemodynamic changes caused by humoral and nervous dysregulation. Cirrhotic cardiomyopathy implies systolic and diastolic dysfunction and electrophysi......Cardiovascular complications of cirrhosis include cardiac dysfunction and abnormalities in the central, splanchnic and peripheral circulation, and haemodynamic changes caused by humoral and nervous dysregulation. Cirrhotic cardiomyopathy implies systolic and diastolic dysfunction...... and electrophysiological abnormalities, an entity that is different from alcoholic heart muscle disease. Being clinically latent, cirrhotic cardiomyopathy can be unmasked by physical or pharmacological strain. Consequently, caution should be exercised in the case of stressful procedures, such as large volume paracentesis....... The clinical significance of cardiovascular complications and cirrhotic cardiomyopathy is an important topic for future research, and the initiation of new randomised studies of potential treatments for these complications is needed....

  3. [Complications of cocaine addiction].

    Science.gov (United States)

    Karila, Laurent; Lowenstein, William; Coscas, Sarah; Benyamina, Amine; Reynaud, Michel

    2009-06-20

    Addiction is a chronic relapsing disorder characterized by repetitive and compulsive drug-seeking behavior and drug abuse despite negative health or social consequences. Cocaine addiction is a significant worldwide public health problem, which has somatic, psychological, psychiatric, socio-economic and judicial complications. Some of the most frequent complications are cardiovascular effects (acute coronary syndrome, cardiac arrhythmias, increased blood pressure); respiratory effects (fibrosis, interstitial pneumonitis, pulmonary hypertension, alveolar haemorrhage, asthma exacerbation; emphysema), neurological effects (strokes, aneurysms, seizures, headaches); risk for contracting HIV/AIDS, hepatitis B and C, sexual transmitted disease and otolaryngologic effects. Other complications are not discussed here. The vast majority of studies indicate that there are cognitive deficits induced by cocaine addiction. Attention, visual and working memories, executive functioning are affected in cocaine users. Psychiatric complications found in clinical practice are major depressive disorders, cocaine-induced paranoia, cocaine-induced compulsive foraging and panic attacks.

  4. Postoperative rectal anastomotic complications

    Czech Academy of Sciences Publication Activity Database

    Polanecký, O.; Adámek, S.; Šedý, Jiří; Skořepa, J.; Hladík, P.; Šmejkal, M.; Pafko, P.; Lischke, R.

    2014-01-01

    Roč. 115, č. 12 (2014), s. 781-785 ISSN 0006-9248 Institutional support: RVO:67985823 Keywords : human * complication * anastomosis * rectum Subject RIV: FJ - Surgery incl. Transplants Impact factor: 0.439, year: 2014

  5. Complications of Sinusitis

    Science.gov (United States)

    ... Anatomy Virtual Anatomy Disclosure Statement CONDITIONS Adult Sinusitis Pediatric Sinusitis Fungal Sinusitis Sinusitis & Asthma Empty Nose Syndrome Cystic Fibrosis Sinusitis Q&A Complications of Sinusitis Epistaxis (Nosebleeds) Allergic Rhinitis (Hay Fever) Headaches and Sinus Disease Disorders of ...

  6. Complications of Sinus Surgery

    Science.gov (United States)

    ... Anatomy Virtual Anatomy Disclosure Statement CONDITIONS Adult Sinusitis Pediatric Sinusitis Fungal Sinusitis Sinusitis & Asthma Empty Nose Syndrome Cystic Fibrosis Sinusitis Q&A Complications of Sinusitis Epistaxis (Nosebleeds) Allergic Rhinitis (Hay Fever) Headaches and Sinus Disease Disorders of ...

  7. Pertussis (Whooping Cough) Complications

    Science.gov (United States)

    ... of Search Controls Search Form Controls Cancel Submit Pertussis (Whooping Cough) Note: Javascript is disabled or is not supported ... message, please visit this page: About CDC.gov . Pertussis Home About Pertussis Causes & Transmission Signs & Symptoms Complications ...

  8. Complications of Circumcision

    Directory of Open Access Journals (Sweden)

    Aaron J. Krill

    2011-01-01

    Full Text Available In the United States, circumcision is a commonly performed procedure. It is a relatively safe procedure with a low overall complication rate. Most complications are minor and can be managed easily. Though uncommon, complications of circumcision do represent a significant percentage of cases seen by pediatric urologists. Often they require surgical correction that results in a significant cost to the health care system. Severe complications are quite rare, but death has been reported as a result in some cases. A thorough and complete preoperative evaluation, focusing on bleeding history and birth history, is imperative. Proper selection of patients based on age and anatomic considerations as well as proper sterile surgical technique are critical to prevent future circumcision-related adverse events.

  9. Complications of shoulder dystocia.

    Science.gov (United States)

    Dajani, Nafisa K; Magann, Everett F

    2014-06-01

    Complications of shoulder dystocia are divided into fetal and maternal. Fetal brachial plexus injury (BPI) is the most common fetal complication occurring in 4-40% of cases. BPI has also been reported in abdominal deliveries and in deliveries not complicated by shoulder dystocia. Fractures of the fetal humerus and clavicle occur in about 10.6% of cases of shoulder dystocia and usually heal with no sequel. Hypoxic ischemic brain injury is reported in 0.5-23% of cases of shoulder dystocia. The risk correlates with the duration of head-to-body delivery and is especially increased when the duration is >5 min. Fetal death is rare and is reported in 0.4% of cases. Maternal complications of shoulder dystocia include post-partum hemorrhage, vaginal lacerations, anal tears, and uterine rupture. The psychological stress impact of shoulder dystocia is under-recognized and deserves counseling prior to home discharge. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Cryptococcal meningitis complicating sarcoidosis

    OpenAIRE

    Leonhard, Sonja E.; Fritz, Daan; van de Beek, Diederik; Brouwer, Matthijs C.

    2016-01-01

    Abstract Background: Cryptococcal meningitis is an uncommon but severe complication of sarcoidosis. Methods: We present 2 patients with cryptococcal meningitis complicating sarcoidosis and compared findings with 38 cases reported in the literature. Results: When analyzing our patients and 38 cases reported in the literature, we found that median age of sarcoidosis patients with cryptococcal meningitis was 39 years (range 30?48); 27 of 33 reported cases (82%) had a history of sarcoidosis. Only...

  11. On complicity theory.

    Science.gov (United States)

    Kline, A David

    2006-04-01

    The received account of whistleblowing, developed over the last quarter century, is identified with the work of Norman Bowie and Richard DeGeorge. Michael Davis has detailed three anomalies for the received view: the paradoxes of burden, missing harm and failure. In addition, he has proposed an alternative account of whistleblowing, viz., the Complicity Theory. This paper examines the Complicity Theory. The supposed anomalies rest on misunderstandings of the received view or misreadings of model cases of whistleblowing, for example, the Challenger disaster and the Ford Pinto. Nevertheless, the Complicity Theory is important for as in science the contrast with alternative competing accounts often helps us better understand the received view. Several aspects of the received view are reviewed and strengthened through comparison with Complicity Theory, including why whistleblowing needs moral justification. Complicity Theory is also critiqued. The fundamental failure of Complicity Theory is its failure to explain why government and the public encourage and protect whistleblowers despite the possibility of considerable harm to the relevant company in reputation, lost jobs, and lost shareholder value.

  12. Complications in Hip Arthroscopy

    Science.gov (United States)

    Nakano, Naoki; Khanduja, Vikas

    2016-01-01

    Summary Background Recent developments in hip arthroscopic techniques and technology have made it possible in many cases to avoid open surgical dislocation for treating a variety of pathology in the hip. Although early reports suggest favourable results’ using hip arthroscopy and it has been shown to be a relatively safe procedure, complications do exist and can sometimes lead to significant morbidity. Methods This is a review article. The aim of this manuscript is to present the most frequent and/or serious complications that could occur at or following hip arthroscopy and some guidelines to avoid these complications. Conclusion Most complications of hip arthroscopy are minor or transient but serious complications can occur as well. A lot of complication e.g. acetabular labral puncture go unreported. Appropriate education and training, precise and meticulous surgical technique with correct instrumentation, the right indication in the right patient and adherence to advice from mentors and experienced colleagues are all essential factors for a successful outcome. Level of evidence: V. PMID:28066747

  13. Modeling the spatial distribution of forest crown biomass and effects on fire behavior with FUEL3D and WFDS

    Science.gov (United States)

    Russell A. Parsons; William Mell; Peter McCauley

    2010-01-01

    Crown fire poses challenges to fire managers and can endanger fire fighters. Understanding of how fire interacts with tree crowns is essential to informed decisions about crown fire. Current operational crown fire predictions in the United States assume homogeneous crown fuels. While a new class of research fire models, which model fire behavior with computational...

  14. Chipping Resistance of Graded Zirconia Ceramics for Dental Crowns

    Science.gov (United States)

    Zhang, Y.; Chai, H.; Lee, J.J.-W.; Lawn, B.R.

    2012-01-01

    A serious drawback of veneering porcelains is a pronounced susceptibility to chipping. Glass-infiltrated dense zirconia structures can now be produced with esthetic quality, making them an attractive alternative. In this study, we examined the hypothesis that such infiltrated structures are much more chip-resistant than conventional porcelains, and at least as chip-resistant as non-infiltrated zirconia. A sharp indenter was used to produce chips in flat and anatomically correct glass-infiltrated zirconia crown materials, and critical loads were measured as a function of distance from the specimen edge (flat) or side wall (crown). Control data were obtained on zirconia specimens without infiltration and on crowns veneered with porcelains. The results confirmed that the resistance to chipping in graded zirconia is more than 4 times higher than that of porcelain-veneered zirconia and is at least as high as that of non-veneered zirconia. PMID:22232142

  15. Microleakage of core materials for complete cast gold crowns.

    Science.gov (United States)

    Tjan, A H; Chiu, J

    1989-06-01

    This study evaluated the microleakage patterns of complete cast-gold crowns cemented onto teeth rebuilt with pin-retained cores made from cast gold, amalgam, composite resin, and silver-reinforced glass ionomer by using three different cements (zinc phosphate, glass ionomer, and resin cement). Crowns cemented onto unrebuilt tooth preparations with zinc phosphate cement served as controls. The cemented specimens were thermocycled between 4 degrees and 50 degrees C in waterbaths. They were then embedded in epoxy resin and sectioned. The extent of marginal microleakage was evaluated with a stereomicroscope and scored. The findings indicated that the type of luting agent used appeared to affect microleakage more than the core material. No significant differences in the degree of microleakage were found under crowns cemented onto teeth rebuilt with the four core materials when cemented with the same luting cement.

  16. A zirconia implant-crown system: a case report.

    Science.gov (United States)

    Kohal, Ralf J; Klaus, Gerold

    2004-04-01

    Exposed metal crown margins in the porcelain-fused-to-metal technique might be an esthetic problem. Therefore, all-ceramic crown systems are used for restoring teeth and dental implants. In addition, the gray color of a titanium implant might hamper the esthetic appearance of the entire reconstruction in cases of thin peri-implant soft tissue or tissue retraction. To further improve the esthetic aspect of dental implants, efforts are undertaken to develop implant systems fabricated out of tooth-colored materials that are biocompatible and able to withstand masticatory forces. One such material may be zirconia. The present article presents a case in which an all-ceramic custom-made zirconia implant-crown system was used for the replacement of a single tooth.

  17. Retention of crowns cemented on implant abutments with temporary cements.

    Science.gov (United States)

    Nagasawa, Yuko; Hibino, Yasushi; Nakajima, Hiroshi

    2014-01-01

    This study was to examine the retentive force of crowns to implant abutments with commercial temporary cements. Six different temporary cements were investigated. Cast crowns were cemented to the abutments using each cement and their retentive forces to abutments were determined 7 or 28 days after cementing (n=10). The retentive force of the cements to abutments varied widely among the products [27-109 N (7-day), 18-80 N (28-days)]. The retentive force of all the cements was not reduced as the time elapsed, except for two products tested. The polycarboxylate cements and paste-mixing type eugenol-free cements revealed comparable retentive force after 28 days of storage. The powder-liquid type cements showed a positive correlation (pcement between the retentive force and compressive strength. Mechanical strength of temporary cements could not be a prominent predicting factor for retention of the crowns on the abutments.

  18. AB INITIO INVESTIGATION OF 12-CROWN-4 AND BENZO-12-CROWN-4 COMPLEXES WITH Li+, Na+, K+, Zn2+, Cd2+, AND Hg2+

    Directory of Open Access Journals (Sweden)

    Yahmin Yahmin

    2010-06-01

    Full Text Available The structure and binding energies of 12-crown-4 and benzo-12-crown-4 complexes with Li+, Na+, K+, Zn2+, Cd2+, and Hg2+were investigated with ab initio calculations using Hartree-Fock approximation and second-order perturbation theory. The basis set used in this study is lanl2mb. The structure optimization of cation-crown ether complexes was evaluated at HF/lanl2mb level of theory and interaction energy of the corresponding complexes was calculated at MP2/lanl2mb level of theory (MP2/lanl2mb//HF/lanl2mb. Interactions of the crown ethers and the cations were discussed in term of the structure parameter of crown ether. The binding energies of the complexes show that all complex formed from transition metal cations is more stable than the complexes formed from alkali metal cations.   Keywords: 12-crown-4, benzo-12-crown-4, alkali metals, transition metals

  19. Long-term outcomes of short dental implants supporting single crowns in posterior region: a clinical retrospective study of 5-10 years.

    Science.gov (United States)

    Lai, Hong-Chang; Si, Mi-Si; Zhuang, Long-Fei; Shen, Hui; Liu, Yue-Lian; Wismeijer, Daniel

    2013-02-01

    Aimed to evaluate the long-term clinical and radiographic outcomes of short implants supporting single crowns in the posterior regions. A retrospective study design was adopted. The clinical and radiographic data of 231 short implants (intra-bony length ≤8 mm) supporting single crowns in 168 patients, were collected after 5-10 (mean 7.22) years' follow-up. Implant and prosthesis failures, peri-implant marginal bone loss, biological and technical complications were evaluated. The influence factors on implant failure were studied. In total 4 implants and 11 prostheses failed. The 10-year (5-year) cumulative survival rate was 98.3% (98.7%) for implant-based analysis and 97.6% (98.2%) for patient-based analysis. The short implants placed in type IV bone yielded more failures than in type I-III and presented a survival rate of 94.0%. The 10-year survival rate of the prostheses was 95.2%. The mean marginal bone loss between implant installation and the 10 years' follow-up visit was 0.63 ± 0.68 mm. The marginal bone loss between the first and 5th year was minimal (0.05 ± 0.10mm and not statistically significant). 18 (7.8%) implants were exposed to biological complications, whereas 29 (12.6%) implants were involved in technical complications. High survival rates for both the implants and the prostheses could be achieved after 5-10 years for short implants supporting single crowns, without severe marginal bone loss and complications. One may conclude that a single crown supported by a short implant is a predictable treatment modality. However, short implants in type IV bone sites should be applied with caution. © 2012 John Wiley & Sons A/S.

  20. Uniform versus asymmetric shading mediates crown recession in conifers.

    Directory of Open Access Journals (Sweden)

    Amanda L Schoonmaker

    Full Text Available In this study we explore the impact of asymmetrical vs. uniform crown shading on the mortality and growth of upper and lower branches within tree crowns, for two conifer species: shade intolerant lodgepole pine (Pinus contorta and shade tolerant white spruce (Picea glauca. We also explore xylem hydraulics, foliar nutrition, and carbohydrate status as drivers for growth and expansion of the lower and upper branches in various types of shading. This study was conducted over a two-year period across 10 regenerating forest sites dominated by lodgepole pine and white spruce, in the lower foothills of Alberta, Canada. Trees were assigned to one of four shading treatments: (1, complete uniform shading of the entire tree, (2 light asymmetric shading where the lower 1/4-1/3 of the tree crown was shaded, (3 heavy asymmetric shading as in (2 except with greater light reduction and (4 control in which no artificial shading occurred and most of the entire crown was exposed to full light. Asymmetrical shading of only the lower crown had a larger negative impact on the bud expansion and growth than did uniform shading, and the effect was stronger in pine relative to spruce. In addition, lower branches in pine also had lower carbon reserves, and reduced xylem-area specific conductivity compared to spruce. For both species, but particularly the pine, the needles of lower branches tended to store less C than upper branches in the asymmetric shade, which could suggest a movement of reserves away from the lower branches. The implications of these findings correspond with the inherent shade tolerance and self-pruning behavior of these conifers and supports a carbon based mechanism for branch mortality--mediated by an asymmetry in light exposure of the crown.

  1. Provisional crown failures in dental school predoctoral clinics.

    Science.gov (United States)

    Hyde, Jeffrey D; Bader, James A; Shugars, Daniel A

    2007-11-01

    Following a preliminary study indicating that at least 10 percent of single-unit crown temporary restorations failed in patients who received treatment by predoctoral students, a comprehensive examination of provisional crown failure was initiated to identify strategies to reduce the failure rate. For all provisionalized, natural tooth, single-unit crown preparations in University of North Carolina School of Dentistry predoctoral clinics for one year (N=1008), we noted tooth type, type of crown, student level, faculty coverage experience, treatment clinic, temporary material and luting agent, and retreatment (failure) of the provisional restoration. For failures, we also noted the stage of crown preparation at failure and the time since initial placement of the temporary. We analyzed these data using simple cross-tabs and logistic regression on need for retreatment (alpha =0.05). The failure rate was 18.75 percent (N=189). The median time to failure was twelve days; the 25(th) and 75(th) percentiles were six and twenty-six days. Significant risk factors, in order of odds ratio estimates, were molar tooth, second- or third-year student, and inexperienced faculty. Most provisional failures occurred during the final preparation phase of treatment. Provisional restoration failure is more frequent than was initially suspected from preliminary studies. Strategies for institutional intervention to reduce provisional restoration failure include greater attention to evaluating provisional crowns placed by inexperienced students (sophomores and juniors) and placing more emphasis on the retentiveness of provisional restorations reused following the final impression. Review of provisional evaluation procedures is also indicated for faculty who do not routinely supervise these procedures.

  2. Immediate esthetic crown with a facet of the extracted element.

    Science.gov (United States)

    Di Giacomo, Giovanni de Almeida Prado; Magalhães, Amanda; Ajzen, Sergio

    2014-07-01

    The present report describes a case of implant loading with an immediate temporary crown. The buccal crown surface was removed from the extracted tooth to obtain an aesthetically satisfactory result. After periodontal treatment, tooth 21 appeared proclined and showed Grade 3 mobility, indicating the need for its extraction. The remaining bone was imaged using computed tomography, and virtual surgical planning was performed using these results. The implant was immediately loaded postextraction into the fresh alveolus without a graft and flap procedure. The temporary tooth, which was manufactured using the extracted buccal surface, was a simple, fast, and low cost procedure that produced an excellent esthetic outcome.

  3. Displacement of Monolithic Rubble-Mound Breakwater Crown-Walls

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Lars Vabbersgaard; Andersen, Thomas Lykke

    2012-01-01

    of the accumulated sliding distance of crown-wall superstructures, which is in contrast to findings from previous similar studies on caisson breakwaters. The calculated sliding distance is approximately three times larger than the measured one when using the original one-dimensional model suggested in previous...... studies on caisson breakwaters, but correction terms are suggested in the present paper to obtain almost equal measured and estimated displacements. This is of great practical importance since many existing rubble-mound crown-walls are subjected to increasing wave loads due to rising sea water level from...

  4. Evaluation of retention of cemented laser-sintered crowns on unmodified straight narrow implant abutments.

    Science.gov (United States)

    Kilicarslan, Mehmet Ali; Ozkan, Pelin

    2013-01-01

    A common problem with cemented crowns is inadequate retention at the crown-abutment interface. The aim of this study was to compare the retention of new laser-sintered cobalt-chromium alloy crowns to the retention of cobalt-chromium alloy crowns fabricated with a traditional casting technique with and without an alloy primer. Twenty-four metallic crowns per casting technique were fabricated, and surface roughness values were recorded with a profilometer. Alloy primer was applied to half the specimens, and all crowns were luted with resin cement. After 24 hours, specimens were subjected to tensile force application with a universal testing machine. The effect of the cement amount was evaluated with an analytic balance. The results were compared using the Kruskal-Wallis multiple-comparison test. The Spearman correlation was used to determine correlations between crown retention and cement weight. The laser-sintered crowns (2.72 μm) were rougher than conventionally cast crowns. The mean load to failure values were as follows: 455.10 ± 192.69 Ncm for conventional crowns, 565.52 ± 112.87 Ncm for conventional crowns with alloy primer, 534.78 ± 130.15 Ncm for laser-sintered crowns, and 678.60 ± 212.83 Ncm for laser-sintered crowns with alloy primer. Laser-sintered crowns (10.10 ± 2.15 mg) showed a significant difference in terms of cement weight compared with cast crowns. In addition, negative correlations were found for retention and cement weight between all groups, except for the laser-sintered group without alloy primer. Retentive forces were significantly higher for laser-sintered crowns than for conventionally cast crowns. An increase in the surface roughness and the application of alloy primers led to an increase in the adhesive bonding of resin cements to metal alloys. It was concluded that a reduction in cement weight improved retention.

  5. In vitro fracture resistance of three commercially available zirconia crowns for primary molars.

    Science.gov (United States)

    Townsend, Janice A; Knoell, Patrick; Yu, Qingzhao; Zhang, Jian-Feng; Wang, Yapin; Zhu, Han; Beattie, Sean; Xu, Xiaoming

    2014-01-01

    The purpose of this study was to measure the fracture resistance of primary mandibular first molar zirconia crowns from three different manufacturers-EZ Pedo (EZP), NuSmile (NSZ), and Kinder Krowns (KK)-and compare it with the thickness of the zirconia crowns and the measured fracture resistance of preveneered stainless steel crowns (SSCs). The thickness of 20 zirconia crowns from three manufacturers were measured. The mean force required to fracture the crowns was determined. Preveneered NuSmile (NSW) SSCs were tested as a control. EZP crowns were significantly thicker in three of the six measured locations. The force required to fracture the EZP crown was significantly higher than that required for NSZ and KK. There was a positive correlation between fracture resistance and crown thickness in the mesial, distal, mesioocclusal, and distoocclusal dimensions. None of the zirconia crowns proved to be as resistant to fracture as the preveneered SSCs. Statistically significant differences were found among the forces required to fracture zirconia crowns by three different manufacturers. The increase in force correlated with crown thickness. The forces required to fracture the preveneered stainless steel crowns were greater than the forces required to fracture all manufacturers' zirconia crowns.

  6. Changes in retention force with electroplated copings on conical crowns: a comparison of gold and zirconia primary crowns.

    Science.gov (United States)

    Bayer, Stefan; Kraus, Dominik; Keilig, Ludger; Gölz, Lina; Stark, Helmut; Enkling, Norbert

    2012-01-01

    The aim of this study was to examine the wear behavior of conical crowns with electroplated gold copings that are used to connect implants and teeth to a removable denture. Gold alloy and zirconium dioxide ceramic crowns were compared. Fifteen crowns each were milled for two groups: gold alloy and zirconium dioxide. Each specimen had a 2-degree taper. The electroplated coping was established by direct electroforming. The retentive forces and the correlating distance during insertion and separation were measured after 10,000 wear cycles were applied. The wear testing was separated into a start phase, an initial wear phase, and the long-term wear period. The retention force value and the force-distance integral of the first 0.3 mm of each cycle were calculated. The changes in retention force and integral did not differ significantly between both groups in the start and the initial wear phase. No differences were seen in force development during the long-term wear period. Only the force-distance integral showed a significant difference: the median values of the gold crowns increased slightly, and they decreased slightly for the zirconia crowns. The median force values never fell below 6 N for gold and 4 N for zirconia. Within the limitations of this study, the tested conical crowns showed clinically acceptable retentive properties. As with other retentive elements for dentures, the specimens tested showed the greatest amount of change in retentive forces during the first 2,000 cycles. The development of retention force in both groups was not significantly different. However, the zirconia specimens showed reduced variability, which is preferable in clinical practice.

  7. Complications of ERCP.

    Science.gov (United States)

    Talukdar, Rupjyoti

    2016-10-01

    Even though considered safe, endoscopic retrograde cholangiopancreatography (ERCP) is among the endoscopic procedures associated with the highest rate of complications. Post ERCP pancreatitis (PEP) is the most common complication of ERCP. Several independent risk factors have been associated with PEP. Prophylactic PD stenting has been shown to be highly effective in preventing PEP. More recent studies have suggested that NSAIDs, especially rectal indomethacin, could by itself be effective in preventing PEP. However, head to head RCTs comparing PD stents with NSAIDs would be required to confirm this. Other complications include ERCP induced bleeding, perforation, and cholangitis. Bleeding is related to morphological, procedural, and patient related factors. Early identification and correction of the risk factors are of paramount importance in preventing bleeding. Risk of infection is particularly high during ERCP. It is important to ensure complete drainage of obstructed biliary system in order to reduce the risk of post-ERCP cholangitis. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Tattoo complaints and complications

    DEFF Research Database (Denmark)

    Serup, Jørgen; Carlsen, Katrina Hutton; Sepehri, Mitra

    2015-01-01

    Tattoos cause a broad range of clinical problems. Mild complaints, especially sensitivity to sun, are very common and seen in 1/5 of cases. Medical complications are dominated by allergy to tattoo pigment haptens or haptens generated in the skin, especially in red tattoos but also in blue and green...... tattoos. Symptoms are major and can be compared to cumbersome pruritic skin diseases. Tattoo allergies and local reactions show distinct clinical manifestations, with plaque-like, excessive hyperkeratotic, ulcero-necrotic, lymphopathic, neuro-sensory, and scar patterns. Reactions in black tattoos...... are papulo-nodular and non-allergic and associated with the agglomeration of nanoparticulate carbon black. Tattoo complications include effects on general health conditions and complications in the psycho-social sphere. Tattoo infections with bacteria, especially staphylococci, which may be resistant...

  9. Post dengue neurological complication

    Directory of Open Access Journals (Sweden)

    Hizlinda Tohid

    2015-12-01

    Full Text Available Dengue infection is highly endemic in many tropical countries including Malaysia. However, neurological complications arising from dengue infection is not common; Gullain–Barre syndrome (GBS is one of these infrequent complications. In this paper, we have reported a case in which a 39-year-old woman presented with a neurological complication of dengue infection without typical symptoms and signs of dengue fever. She had a history of acute gastroenteritis (AGE followed by an upper respiratory tract infection (URTI weeks prior to her presentation rendering GBS secondary to the post viral URTI and AGE as the most likely diagnosis. Presence of thrombocytopenia was the only clue for dengue in this case.

  10. Complications of cosmetic tattoos.

    Science.gov (United States)

    De Cuyper, Christa

    2015-01-01

    Cosmetic tattoos, which are better known as permanent make-up, have become popular in the last decades. This same procedure can be used to camouflage pathological skin conditions, to mask scars and to complete the aesthetic results of plastic and reconstructive surgeries. The risks and complications of tattooing procedures include infections and allergic reactions. Scarring can occur. Fanning and fading of the colorants and dissatisfaction with colour and shape are not unusual. Different lasers can offer solutions for the removal of unwanted cosmetic tattoos, but complications due to the laser treatment, such as paradoxical darkening and scarring, can arise. © 2015 S. Karger AG, Basel.

  11. Sinogenic intracranial complications

    DEFF Research Database (Denmark)

    Kofoed, Mikkel Seremet; Fisker, Niels; Christensen, Anne Estmann

    2018-01-01

    We present two 11-year-old girls with chronic recurrent multifocal osteomyelitis, treated with adalimumab. Both developed severe intracranial complications to sinusitis. Patient 1 had been treated with adalimumab for 15 months when she developed acute sinusitis complicated by an orbital abscess...... and subcortical abscesses in combination with sinusitis. She was treated with endoscopic sinus surgery and intravenous antibiotics. Both patients had developed psoriasis and episodes of infection during treatment. They were non-septic and had low fever on presentation. None of the patients suffered any long...

  12. Fluorescence Sensing Properties of Thiazolobenzo-crown Ether Incorporating Coumarin

    International Nuclear Information System (INIS)

    Lee, Sang Hoon; Helal, Aasif; Kim, Hong Seok

    2010-01-01

    A new coumarin-thiazolobenzo-crown ether based fluorogenic chemosensor BTC (1) was reported. The ion-selective binding properties of 1 with different alkali, alkaline earth metals and transitional metals were investigated in an ethanol- DMSO system. BTC (1) showed the highest binding constant toward Hg 2+ over Ag + , Pb 2+ and Cu 2+

  13. Fracture Resistance Force of Primary Molar Crowns Milled from ...

    African Journals Online (AJOL)

    2018-04-04

    Apr 4, 2018 ... and porcelain‑based ceramic blocks, metal alloy blocks, and various composite ... Mete, et al.: Primary molar CAD/CAM crowns brittleness, tendency to fracturing, and attrition on the enamel of the antagonist tooth.[9‑13] To overcome its ..... Yilmaz A, Ozdemir CE, Yilmaz Y. A delayed hypersensitivity reaction ...

  14. Effect of detachment time of pineapple ( Ananas comosus L .) crown ...

    African Journals Online (AJOL)

    A limiting factor to large scale production of pineapple is the scarcity of planting materials. The use of pineapple crown as a propagation material is common, but with no regard to length of time after detachment. A study was conducted in the late seasons of 2007 and 2008 at the Teaching and Research Farm Ekiti State ...

  15. Fracture Resistance Force of Primary Molar Crowns Milled from ...

    African Journals Online (AJOL)

    2018-04-04

    Apr 4, 2018 ... are used.[8]. Glass‑ceramic material that is widely used with. CAD/CAM technologies has both advantages such as the esthetic appearance, color stability, biocompatibility, and life‑long durability and disadvantages such as. Original Article. Introduction. Stainless steel crowns (SSCs) were introduced by.

  16. Evaluaton of Wild Juglans Species for Crown Gall Resistance

    Science.gov (United States)

    Crown Gall disease of walnut is caused by the ubiquitous soil-borne bacterium, Agrobacterium tumefaciens, which is able to transfer a specific piece of its own DNA into the genome of the plant host cell. The result of this genetic transformation is the autonomous undifferentiated massive growth of ...

  17. Loading capacity of zirconia implant supported hybrid ceramic crowns.

    Science.gov (United States)

    Rohr, Nadja; Coldea, Andrea; Zitzmann, Nicola U; Fischer, Jens

    2015-12-01

    Recently a polymer infiltrated hybrid ceramic was developed, which is characterized by a low elastic modulus and therefore may be considered as potential material for implant supported single crowns. The purpose of the study was to evaluate the loading capacity of hybrid ceramic single crowns on one-piece zirconia implants with respect to the cement type. Fracture load tests were performed on standardized molar crowns milled from hybrid ceramic or feldspar ceramic, cemented to zirconia implants with either machined or etched intaglio surface using four different resin composite cements. Flexure strength, elastic modulus, indirect tensile strength and compressive strength of the cements were measured. Statistical analysis was performed using two-way ANOVA (p=0.05). The hybrid ceramic exhibited statistically significant higher fracture load values than the feldspar ceramic. Fracture load values and compressive strength values of the respective cements were correlated. Highest fracture load values were achieved with an adhesive cement (1253±148N). Etching of the intaglio surface did not improve the fracture load. Loading capacity of hybrid ceramic single crowns on one-piece zirconia implants is superior to that of feldspar ceramic. To achieve maximal loading capacity for permanent cementation of full-ceramic restorations on zirconia implants, self-adhesive or adhesive cements with a high compressive strength should be used. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Why do crown ethers activate enzymes in organic solvents?

    NARCIS (Netherlands)

    van Unen, D.J.; Engbersen, Johannes F.J.; Reinhoudt, David

    2002-01-01

    One of the major drawbacks of enzymes in nonaqueous solvents is that their activity is often dramatically low compared to that in water. This limitation can be largely overcome by crown ether treatment of enzymes. In this paper, we describe a number of carefully designed new experiments that have

  19. Mandibular molar crown-topography, a biological predisposing ...

    African Journals Online (AJOL)

    Mandibular molar crown-topography, a biological predisposing factor to development of caries – a post-mortem analysis of 2500 extracted lower permanent molars at ... (12.57%), distol surface attack 1,528 (12.22%) buccal surface attack 926 (7.40%), lingual surface attack 59 (0.47%) occlusal surface attack 6540 (52.32%).

  20. Bio-inspired ion selective crown-ether polymer membranes

    NARCIS (Netherlands)

    Tas, Sinem

    2016-01-01

    Development of unctional membranes that are capable of selectively recognizing and transporting ions have key importance for the recovery and separation of specific icons (e.d. K+, Li+, Na+) from multicomponent mixtures. In this thesis, new membrane materials based on crown ether-metal ion

  1. Management of crown-of-thorns sea star (

    NARCIS (Netherlands)

    Bos, A.R.; Gumanao, G.S.; Mueller, B.; Saceda-Cardoza, M.M.E.

    2013-01-01

    Removals of crown-of-thorns sea stars (Acanthaster planci L) are crucial initiatives in limiting the damage to coral reefs during outbreaks, but have often been unable to control the populations. We hypothesized that reef topography and exact timing of removals (before reproduction) determine their

  2. Novel Ordered Crown Ether-Containing Polyimides for Ion Conduction

    Science.gov (United States)

    Irvin, Jennifer A.; Stasko, Daniel; Fallis, Stephen; Guenthner, Andrew J.; Webber, Cynthia; Blackwell, John; Chvalun, Sergei N.

    2003-01-01

    We report the synthesis and characterization of thermally-stable polyimides for use as battery and fuel cell electrolyte membranes. Dianhydrides used were 1,4,5,8- naphthalenetetracarboxylic dianhydride and/or 4,4'-(hexafluoroisopropylidene)diphthalic anhydride. Diamines used were anti-4,4-diaminodibenzo-l8-crown-6, 4,4'- diaminodibenzo-24-crown-8, 2,2-bis(4-aminophenyl)hexafluoropropane, and/or 2,5- diaminobenzenesulfonic acid. The polymers were characterized using electrochemical impedance spectroscopy (EIS), thermal analysis and X-ray diffraction. Polymers containing the hexafluoroisopropylidene (HFIP) group were soluble in common organic solvents, while polymers without the HFIP group were very poorly soluble. Sulfonation yields polymers that are sparingly soluble in aqueous base and/or methanol. Degree of sulfonation, determined by titration, was between one and three sulfonate groups per repeat unit. Proton conductivity was determined as a function of water content, with a maximum conductivity of l x 10(exp -2) per centimeter when fully hydrated. Crown ether-containing polymers exhibit a high degree of order that may be indicative of crown ether channel formation, which may facilitate Li(+) transport for use in battery membranes.

  3. Chemical constituent analysis of the crown-of-thorns starfish ...

    African Journals Online (AJOL)

    The crown-of-thorns starfish Acanthaster planci is a major management issue on coral reefs and the exploring of effective control methods to the starfish is an interesting goal. In this study, the chemical constituent of the starfish were analyzed and the toxicity of the starfish was tested when it was used as mice diet.

  4. Towards an optimized method of olive tree crown volume measurement.

    Science.gov (United States)

    Miranda-Fuentes, Antonio; Llorens, Jordi; Gamarra-Diezma, Juan L; Gil-Ribes, Jesús A; Gil, Emilio

    2015-02-04

    Accurate crown characterization of large isolated olive trees is vital for adjusting spray doses in three-dimensional crop agriculture. Among the many methodologies available, laser sensors have proved to be the most reliable and accurate. However, their operation is time consuming and requires specialist knowledge and so a simpler crown characterization method is required. To this end, three methods were evaluated and compared with LiDAR measurements to determine their accuracy: Vertical Crown Projected Area method (VCPA), Ellipsoid Volume method (VE) and Tree Silhouette Volume method (VTS). Trials were performed in three different kinds of olive tree plantations: intensive, adapted one-trunked traditional and traditional. In total, 55 trees were characterized. Results show that all three methods are appropriate to estimate the crown volume, reaching high coefficients of determination: R2 = 0.783, 0.843 and 0.824 for VCPA, VE and VTS, respectively. However, discrepancies arise when evaluating tree plantations separately, especially for traditional trees. Here, correlations between LiDAR volume and other parameters showed that the Mean Vector calculated for VCPA method showed the highest correlation for traditional trees, thus its use in traditional plantations is highly recommended.

  5. Calix salophen crown ethers as receptors for neutral molecules

    NARCIS (Netherlands)

    Reichwein, A.M.; Reichwein, Arjen M.; Verboom, Willem; Harkema, Sybolt; Spek, Anthony L.; Reinhoudt, David

    1994-01-01

    The calix[4]arene based salophen crown ethers 7 and 8 were synthesized as lipophilic carriers for neutral molecules. The X-ray structures of the H2O, CH3OH and (CH3)2SO complexes of 8a have been determined.

  6. Diet of nesting African Crowned Eagles Stephanoaetus coronatus in ...

    African Journals Online (AJOL)

    The aim of this study was to investigate the species composition of prey caught in the forest, savanna and emerging habitats in which African Crowned Eagles Stephanoaetus coronatus breed in KwaZulu-Natal province, South Africa. At the 17 nest sites, the remains of 195 prey individuals were collected. The five dominant ...

  7. Notes on African Crowned Eagle Stephanoaetus coronatus diet in ...

    African Journals Online (AJOL)

    Our study reports on contrasts in prey items from African Crowned Eagle Stephanoaetus coronatus nesting in forest (n = 1) and savanna (n = 2) biomes in KwaZulu-Natal, South Africa. At least 12 taxa were identified at a forest nest, of which 92.1% were neonate/juvenile. Bovids and procaviids represented 73.7% and 19.6% ...

  8. Towards an Optimized Method of Olive Tree Crown Volume Measurement

    Science.gov (United States)

    Miranda-Fuentes, Antonio; Llorens, Jordi; Gamarra-Diezma, Juan L.; Gil-Ribes, Jesús A.; Gil, Emilio

    2015-01-01

    Accurate crown characterization of large isolated olive trees is vital for adjusting spray doses in three-dimensional crop agriculture. Among the many methodologies available, laser sensors have proved to be the most reliable and accurate. However, their operation is time consuming and requires specialist knowledge and so a simpler crown characterization method is required. To this end, three methods were evaluated and compared with LiDAR measurements to determine their accuracy: Vertical Crown Projected Area method (VCPA), Ellipsoid Volume method (VE) and Tree Silhouette Volume method (VTS). Trials were performed in three different kinds of olive tree plantations: intensive, adapted one-trunked traditional and traditional. In total, 55 trees were characterized. Results show that all three methods are appropriate to estimate the crown volume, reaching high coefficients of determination: R2 = 0.783, 0.843 and 0.824 for VCPA, VE and VTS, respectively. However, discrepancies arise when evaluating tree plantations separately, especially for traditional trees. Here, correlations between LiDAR volume and other parameters showed that the Mean Vector calculated for VCPA method showed the highest correlation for traditional trees, thus its use in traditional plantations is highly recommended. PMID:25658396

  9. Towards an Optimized Method of Olive Tree Crown Volume Measurement

    Directory of Open Access Journals (Sweden)

    Antonio Miranda-Fuentes

    2015-02-01

    Full Text Available Accurate crown characterization of large isolated olive trees is vital for adjusting spray doses in three-dimensional crop agriculture. Among the many methodologies available, laser sensors have proved to be the most reliable and accurate. However, their operation is time consuming and requires specialist knowledge and so a simpler crown characterization method is required. To this end, three methods were evaluated and compared with LiDAR measurements to determine their accuracy: Vertical Crown Projected Area method (VCPA, Ellipsoid Volume method (VE and Tree Silhouette Volume method (VTS. Trials were performed in three different kinds of olive tree plantations: intensive, adapted one-trunked traditional and traditional. In total, 55 trees were characterized. Results show that all three methods are appropriate to estimate the crown volume, reaching high coefficients of determination: R2 = 0.783, 0.843 and 0.824 for VCPA, VE and VTS, respectively. However, discrepancies arise when evaluating tree plantations separately, especially for traditional trees. Here, correlations between LiDAR volume and other parameters showed that the Mean Vector calculated for VCPA method showed the highest correlation for traditional trees, thus its use in traditional plantations is highly recommended.

  10. Protonation of benzo-18-crown-6: Extraction and DFT study

    Czech Academy of Sciences Publication Activity Database

    Toman, Petr; Makrlík, E.; Vaňura, P.; Kašička, Václav

    2011-01-01

    Roč. 225, č. 2 (2011), s. 265-270 ISSN 0942-9352 R&D Projects: GA ČR(CZ) GAP205/10/2280 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z40550506 Keywords : protonation * nitrobenzene * benzo-18-crown-6 Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.568, year: 2011

  11. Evaluating host resistance to Macrophomina crown rot in strawberry

    Science.gov (United States)

    Macrophomina crown rot, caused by the soilborne fungus Macrophomina phaseolina, is an emerging pathogen in California strawberry production. When established, the pathogen can cause extensive plant decline and mortality. Host resistance will be a critical tool for managing this disease and guiding ...

  12. Evolution of the mandibular third premolar crown in early Australopithecus.

    Science.gov (United States)

    Delezene, Lucas K; Kimbel, William H

    2011-06-01

    The Pliocene hominins Australopithecus anamensis and Australopithecus afarensis likely represent ancestor-descendent taxa--possibly an anagenetic lineage--and capture significant change in the morphology of the canine and mandibular third premolar (P(3)) crowns, dental elements that form the canine honing complex in nonhuman catarrhines. This study focuses on the P(3) crown, highlighting plesiomorphic features in A. anamensis. The A. afarensis P(3) crown, in contrast, is variable in its expression of apomorphic features that are characteristic of geologically younger hominins. Temporal variation characterizes each taxon as well. The A. anamensis P(3) from Allia Bay, Kenya expresses apomorphic character states, shared with A. afarensis, which are not seen in the older sample of A. anamensis P(3)s from Kanapoi, Kenya, while spatiotemporal differences in shape exist within the A. afarensis hypodigm. The accumulation of derived features in A. afarensis results in an increased level of P(3) molarisation. P(3) molarisation did not evolve concurrent with postcanine megadontia and neither did the appearance of derived aspects of P(3) occlusal form coincide with the loss of canine honing in hominins, which is apparent prior to the origin of the genus Australopithecus. A. afarensis P(3) variation reveals the independence of shape, size, and occlusal form. The evolution of the P(3) crown in early Australopithecus bridges the wide morphological gap that exists between geologically younger hominins on the one hand and extant apes and Ardipithecus on the other. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. New die design for dimensional accuracy assessment of crown castings.

    Science.gov (United States)

    Low, Danny

    2003-01-01

    The aim of this study was to introduce a newly designed die for ceramometal restoration, and to compare the dimensional accuracy with the traditional complete-crown design. Two methods of dimensional accuracy assessment, vertical axial discrepancy and transverse diametral percentage, were compared. Patterns were prepared from two different die designs--complete crown and ceramometal. Two investments available for titanium crown casting were used, Titavest CB and T-invest C & B. Titanium castings were made from each investment with a high-pressure casting machine. Vertical axial discrepancy of casting was determined by measuring the discrepancy for each set of wax patterns and their castings on the same die under a traveling microscope. Dimensional accuracy was expressed as vertical axial discrepancy and by transforming the vertical axial discrepancy into transverse diametral percentage. Both dies produced undersized castings with T-invest C & B and oversized castings with Titavest CB. Dimensional accuracy assessment of the two different types of crown casting design showed no significant difference in vertical axial discrepancy. Compared to the traditional transverse diametral percentage calculation, the vertical axial discrepancy assessment is independent of the die's dimensions. The two types of investment materials studied resulted in castings with different dimensional accuracies.

  14. Evaluation of Vertical Marginal Adaptation of Provisional Crowns by ...

    African Journals Online (AJOL)

    2018-01-30

    Jan 30, 2018 ... Department of Prosthetic Dental Sciences, College of Dentistry,. King Saud University, Riyadh, Kingdom of Saudi Arabia. E‑mail: malrifaiy@hotmail.com. How to cite this article: Al Rifaiy MQ. Evaluation of vertical marginal adaptation of provisional crowns by digital microscope. Niger J Clin Pract. 2017 ...

  15. Grey Crowned Cranes Balearica regulorum in urban areas of Uganda

    African Journals Online (AJOL)

    The greatest threat to birds in tropical Africa is habitat change; often a result of unsus- tainable agricultural practices (BirdLife International 2013a) and this certainly applies to Grey Crowned Cranes Balearica regulorum, whose primary breeding habitat — sea- sonal swamps — is increasingly being converted into cultivation ...

  16. Long-term survival of extensive amalgams and posterior crowns.

    Science.gov (United States)

    Smales, R J; Hawthorne, W S

    1997-01-01

    There is very little information available from private dental practices on the comparative survivals of extensive posterior amalgam restorations and posterior crowns placed in the same patient population. Therefore, the present retrospective study examined the performance of such restorations at three long-established Adelaide city practices. Life-table survival estimates were generated for 160 extensive amalgams, 96 cast gold crowns and 174 ceramometal crowns. The restorations were placed by 20 dentists at various times in 100 patients who attended the practices on a regular basis for around 25 years on average. There were no significant differences found in the survival times for both types of crowns, with around 70% still being present at 20 years. However, the median survival time for the extensive amalgams was much lower, at 14.6 years. Despite these differences in survival times, the extensive amalgam restorations survived for longer than is usually expected. In this present study, the survival findings have implications for the most cost-effective dental treatments of large lesions in posterior teeth.

  17. The impact of capture, domestication and trade on Black Crowned ...

    African Journals Online (AJOL)

    The inland delta of the Niger, a vast floodplain, is the only refuge of Black Crowned Cranes in Mali. This study, centred on the regions of Mopti, Tenenkou and Youwarou, aimed to: (1) census the number of cranes in the delta and in captivity in the towns of Mopti and Bamako; (2) examine exploitation at different levels (local ...

  18. Evaluation of sampling strategies to estimate crown biomass

    Directory of Open Access Journals (Sweden)

    Krishna P Poudel

    2015-01-01

    Full Text Available Background Depending on tree and site characteristics crown biomass accounts for a significant portion of the total aboveground biomass in the tree. Crown biomass estimation is useful for different purposes including evaluating the economic feasibility of crown utilization for energy production or forest products, fuel load assessments and fire management strategies, and wildfire modeling. However, crown biomass is difficult to predict because of the variability within and among species and sites. Thus the allometric equations used for predicting crown biomass should be based on data collected with precise and unbiased sampling strategies. In this study, we evaluate the performance different sampling strategies to estimate crown biomass and to evaluate the effect of sample size in estimating crown biomass. Methods Using data collected from 20 destructively sampled trees, we evaluated 11 different sampling strategies using six evaluation statistics: bias, relative bias, root mean square error (RMSE, relative RMSE, amount of biomass sampled, and relative biomass sampled. We also evaluated the performance of the selected sampling strategies when different numbers of branches (3, 6, 9, and 12 are selected from each tree. Tree specific log linear model with branch diameter and branch length as covariates was used to obtain individual branch biomass. Results Compared to all other methods stratified sampling with probability proportional to size estimation technique produced better results when three or six branches per tree were sampled. However, the systematic sampling with ratio estimation technique was the best when at least nine branches per tree were sampled. Under the stratified sampling strategy, selecting unequal number of branches per stratum produced approximately similar results to simple random sampling, but it further decreased RMSE when information on branch diameter is used in the design and estimation phases. Conclusions Use of

  19. Asymptomatic ''crowned dens'' calcification in CT images for the craniovertebral junction

    International Nuclear Information System (INIS)

    Kubota, Gen; Mori, Masataka; Fukushima, Tatsuro

    2007-01-01

    Calcification around the odontoid process suggests 'crowned dens' syndrome, when accompanied with acute occipital headache or neck pain and with inflammatory signs. We retrospectively searched for calcification around the odontoid process in routine CT images of 282 patients emcompassing the craniovertebral junction, and found 13 (4.6%) had 'crowned dens' calcifications with neither characteristic symptoms nor signs suggestive for crowned dens' syndrome. Females of older ages frequently showed asymptomatic crowned dens' calcifications. (author)

  20. Anticoagulation in pregnancy complications

    NARCIS (Netherlands)

    Middeldorp, Saskia

    2014-01-01

    Women with acquired and inherited thrombophilia are thought to be at increased risk for pregnancy complications, including recurrent pregnancy loss and, depending on the type of thrombophilia, severe preeclampsia. This review discusses the associations between the types of thrombophilia and types of

  1. Cardiovascular Complications of Pregnancy

    Science.gov (United States)

    Gongora, Maria Carolina; Wenger, Nanette K.

    2015-01-01

    Pregnancy causes significant metabolic and hemodynamic changes in a woman’s physiology to allow for fetal growth. The inability to adapt to these changes might result in the development of hypertensive disorders of pregnancy (hypertension, preeclampsia or eclampsia), gestational diabetes and preterm birth. Contrary to previous beliefs these complications are not limited to the pregnancy period and may leave permanent vascular and metabolic damage. There is in addition, a direct association between these disorders and increased risk of future cardiovascular disease (CVD, including hypertension, ischemic heart disease, heart failure and stroke) and diabetes mellitus. Despite abundant evidence of this association, women who present with these complications of pregnancy do not receive adequate postpartum follow up and counseling regarding their increased risk of future CVD. The postpartum period in these women represents a unique opportunity to intervene with lifestyle modifications designed to reduce the development of premature cardiovascular complications. In some cases it allows early diagnosis and treatment of chronic hypertension or diabetes mellitus. The awareness of this relationship is growing in the medical community, especially among obstetricians and primary care physicians, who play a pivotal role in detecting these complications and assuring appropriate follow up. PMID:26473833

  2. Atrial Fibrillation: Complications

    Science.gov (United States)

    ... of this page please turn JavaScript on. Feature: Atrial Fibrillation Atrial Fibrillation: Complications Past Issues / Winter 2015 Table of Contents ... has two major complications—stroke and heart failure. Atrial Fibrillation and Stroke Click to enlarge image This illustration ...

  3. Measles and its Complications

    African Journals Online (AJOL)

    1974-05-15

    May 15, 1974 ... Abnormal intensity of lung markings (Fig. I) is a classical feature of even the mildest case. ... The bacterial invaders were studied by means of lung puncture.' Coagulase-positive staphylococci ... Spontaneous mediastinal emphysema is a rarely recorded complication of measles (Fig. 3). A recent review of ...

  4. Complicating Visual Culture

    Science.gov (United States)

    Daiello, Vicki; Hathaway, Kevin; Rhoades, Mindi; Walker, Sydney

    2006-01-01

    Arguing for complicating the study of visual culture, as advocated by James Elkins, this article explicates and explores Lacanian psychoanalytic theory and pedagogy in view of its implications for art education practice. Subjectivity, a concept of import for addressing student identity and the visual, steers the discussion informed by pedagogical…

  5. Treatment of complicated grief

    Directory of Open Access Journals (Sweden)

    Rita Rosner

    2011-11-01

    Full Text Available Following the death of a loved one, a small group of grievers develop an abnormal grieving style, termed complicated or prolonged grief. In the effort to establish complicated grief as a disorder in DSM and ICD, several attempts have been made over the past two decades to establish symptom criteria for this form of grieving. Complicated grief is different from depression and PTSD yet often comorbid with other psychological disorders. Meta-analyses of grief interventions show small to medium effect sizes, with only few studies yielding large effect sizes. In this article, an integrative cognitive behavioral treatment manual for complicated grief disorder (CG-CBT of 25 individual sessions is described. Three treatment phases, each entailing several treatment strategies, allow patients to stabilize, explore, and confront the most painful aspects of the loss, and finally to integrate and transform their grief. Core aspects are cognitive restructuring and confrontation. Special attention is given to practical exercises. This article includes the case report of a woman whose daughter committed suicide.

  6. Complication with intraosseous access

    DEFF Research Database (Denmark)

    Hallas, Peter; Brabrand, Mikkel; Folkestad, Lars

    2013-01-01

    .5%), and extravasation (3.7%). Compartment syndrome and osteomyelitis occurred in 0.6% and 0.4% of cases respectively. CONCLUSION: In users' recollection of real-life IO use, perceived complications were more frequent than usually reported from model studies. The perceived difficulties with using IO could affect...

  7. Medical complications following splenectomy.

    Science.gov (United States)

    Buzelé, R; Barbier, L; Sauvanet, A; Fantin, B

    2016-08-01

    Splenectomy is attended by medical complications, principally infectious and thromboembolic; the frequency of complications varies with the conditions that led to splenectomy (hematologic splenectomy, trauma, presence of portal hypertension). Most infectious complications are caused by encapsulated bacteria (Meningococcus, Pneumococcus, Hemophilus). These occur mainly in children and somewhat less commonly in adults within the first two years following splenectomy. Post-splenectomy infections are potentially severe with overwhelming post-splenectomy infection (OPSI) and this justifies preventive measures (prophylactic antibiotics, appropriate immunizations, patient education) and demands prompt antibiotic management with third-generation cephalosporins for any post-splenectomy fever. Thromboembolic complications can involve both the caval system (deep-vein thrombophlebitis, pulmonary embolism) and the portal system. Portal vein thrombosis occurs more commonly in patients with myeloproliferative disease and cirrhosis. No thromboembolic prophylaxis is recommended apart from perioperative low molecular weight heparin. However, some authors choose to prescribe a short course of anti-platelet medication if the post-splenectomy patient develops significant thrombocytosis. Thrombosis of the portal or caval venous system requires prolonged warfarin anticoagulation for 3 to 6 months. Finally, some studies have suggested an increase in the long-term incidence of cancer in splenectomized patients. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  8. Renal posttransplant's vascular complications

    Directory of Open Access Journals (Sweden)

    Bašić Dragoslav

    2003-01-01

    Full Text Available INTRODUCTION Despite high graft and recipient survival figures worldwide today, a variety of technical complications can threaten the transplant in the postoperative period. Vascular complications are commonly related to technical problems in establishing vascular continuity or to damage that occurs during donor nephrectomy or preservation [13]. AIM The aim of the presenting study is to evaluate counts and rates of vascular complications after renal transplantation and to compare the outcome by donor type. MATERIAL AND METHODS A total of 463 kidneys (319 from living related donor LD and 144 from cadaveric donor - CD were transplanted during the period between June 1975 and December 1998 at the Urology & Nephrology Institute of Clinical Centre of Serbia in Belgrade. Average recipients' age was 33.7 years (15-54 in LD group and 39.8 (19-62 in CD group. Retrospectively, we analyzed medical records of all recipients. Statistical analysis is estimated using Hi-squared test and Fischer's test of exact probability. RESULTS Major vascular complications including vascular anastomosis thrombosis, internal iliac artery stenosis, internal iliac artery rupture obliterant vasculitis and external iliac vein rupture were analyzed. In 25 recipients (5.4% some of major vascular complications were detected. Among these cases, 22 of them were from CD group vs. three from LD group. Relative rate of these complications was higher in CD group vs. LD group (p<0.0001. Among these complications dominant one was vascular anastomosis thrombosis which occurred in 18 recipients (17 from CD vs. one from LD. Of these recipients 16 from CD lost the graft, while the rest of two (one from each group had lethal outcome. DISCUSSION Thrombosis of renal allograft vascular anastomosis site is the most severe complication following renal transplantation. In the literature, renal allograft thrombosis is reported with different incidence rates, from 0.5-4% [14, 15, 16]. Data from the

  9. In vitro performance of full-contour zirconia single crowns.

    Science.gov (United States)

    Beuer, Florian; Stimmelmayr, Michael; Gueth, Jan-Frederik; Edelhoff, Daniel; Naumann, Michael

    2012-04-01

    Zirconia based restorations exhibited high failure rates due to veneering-porcelain fractures. Milling to full-contour might be an alternative approach for zirconia restorations. The aim of this study was to evaluate full-contour zirconia crowns in terms of light-transmission, contact wear (restoration and antagonist) and load-bearing capacity. Powder build-up veneered zirconia substructures and CAD/CAM-veneered zirconia substructures served as controls. Four different kinds of crowns were fabricated on 12 metal dies: zirconia substructure with powder build-up porcelain (veneering technique), zirconia substructure with CAD/CAM generated veneering (sintering technique), full-contour zirconia glazed (glazed full-contour) and full-contour zirconia polished (polished full-contour). All crowns had the same dimensions. After light-transmission was measured the crowns were cemented on the corresponding metal dies. The specimens were loaded according to a special wear method in the chewing simulator (120,000 mechanical cycles, 5 kg load, 0.7 mm sliding movement, 320 thermocycles). Wear of the restoration and the antagonist were measured. All specimens were loaded until failure. One-way ANOVA and a LSD post-hoc test were used to compare data at a level of 5%. Polished full-contour showed significantly higher light transmission than the other groups (p=0.003; ANOVA). Polished full-contour exhibited significantly less contact wear at the restoration (p=0.01; ANOVA) and higher contact wear at the antagonist (p=0.016; ANOVA) compared to the other groups. Glazed full-contour zirconia showed similar contact wear at the antagonist compared to veneering technique (p=0.513, post-hoc LSD). Crowns with conventional veneering showed significantly lower load-bearing capacity (pzirconia to full-contour with glazed surface might be an alternative to traditionally veneered restorations. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. Unusual extraction behaviour of crown ether when intercalated in bentonite

    International Nuclear Information System (INIS)

    Sivaiah, M.V.; Krishna, R.M.; Murthy, G.S.; Venkatesan, K.A.; Sasidhar, P.

    2005-01-01

    Di-cyclo-hexano-18-crown-6 (DCH18C6) has been intercalated in bentonite and the product, Ben-Crown, characterized by micro-elemental analysis, TG-DTA analysis, X-ray diffraction and IR spectroscopy. The permanent negative charge present in the bentonite layer has been exploited for more efficient extraction of cesium and strontium by Ben-Crown at nitric acid concentrations (≤ 1.0 M) that gave only a meagre extraction when either DCH18C6 or bentonite alone were employed. The extraction of cesium and strontium has been investigated as a function of time, temperature, and the concentrations of nitric acid, metal ion and sodium nitrate. An unusual extraction phenomenon was observed at low concentrations of nitric acid (≤ 1.0 M) in the absence of any organo-philic agents. Rapid extraction of the metal ion was followed by the establishment of an equilibrium, which occurred after 150 min. Distribution coefficients (K d ) of 599 and 1007 ml g -1 were obtained, respectively, for the extraction of cesium and strontium from 0.1 M nitric acid by Ben-Crown; K d decreased with an increase in the temperature or in the concentrations of nitric acid and sodium nitrate. The extraction data were fitted by the Langmuir adsorption model and the apparent experimental exchange capacity obtained by linear regression analysis was in good agreement with the amount of crown ether (0.22 mmol g -1 ) intercalated in bentonite. The enthalpy change (ΔH 0 ) for the extraction of cesium and strontium was found to be exothermic. (authors)

  11. Bud development and shoot morphology in relation to crown location

    Science.gov (United States)

    Kukk, Maarja; Sõber, Anu

    2015-01-01

    Plant architecture is shaped by endogenous growth processes interacting with the local environment. The current study investigated crown development in young black alder trees, assessing the effects of local light conditions and branch height on individual bud mass and contents. In addition, we examined the characteristics of parent shoots [the cross-sectional area (CSA) of stem and total leaf area, shoot length, the number of nodes, the number and total mass of buds per shoot] and leaf–stem as well as bud–stem allometry, as several recent studies link bud development to hydraulic architecture. We sampled shoots from top branches and two lower-crown locations: one subjected to deep shade and the other resembling the upper branches in light availability. Sampling was carried out three times between mid-July and late October, spanning from the early stages of bud growth to dormancy. Individual bud mass and shoot characteristics varied in response to light conditions, whereas leaf–stem allometry depended on branch height, most likely compensating for the increasing length of hydraulic pathways. Despite the differences in individual bud mass, the number of preformed leaves varied little across the crown, indicating that the plasticity in shoot characteristics was mainly achieved by neoformation. The relationship between total bud mass and stem CSA scaled similarly across crown locations. However, scaling slopes gradually decreased throughout the sampling period, driven by bud rather than by stem growth. This suggests that the allometry of total bud mass and CSA of stem is regulated locally, instead of resulting from crown-level processes. PMID:26187607

  12. The relationship between the position of mesiodens and complications

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Yun Hwa; Nah, Kyung Soo; Cho, Bong Hae [Department of Oral and Maxillofacial Radiology, College of Dentistry, Pusan National University, Pusan (Korea, Republic of)

    2008-06-15

    The purpose of this study was to evaluate the relationship between the position of mesiodens and its complications. The subjects for this study consisted of 172 patients with mesiodens. Panoramic radiographs and cross-sectional tomography were taken of all of the subjects. Their clinical records and radiographs were analyzed in order to study the direction and vertical and sagittal position of mesiodens, as well as complications caused by mesiodens. The number of mesiodens was one in 112 cases (65.1%) and two in 60 cases (34.9%). Complications were found in 121 mesiodentes (52.2%), with being median diastema the most frequent. The incidence of complications was high in erupted mesiodens (75.0%), in horizontal mesiodens (89.8%) and in mesiodens located within the arch (75.7%), but was low in mesiodens impacted above apex (29.8%), in normal position (34.4%) and in palatally positioned mesiodens (46.5%). It was suggested that the frequency of complications was different according to the vertical position, the direction of the crown and the sagittal position.

  13. Fracture Strength of Aged Monolithic and Bilayer Zirconia-Based Crowns.

    Science.gov (United States)

    Lameira, Deborah Pacheco; Buarque e Silva, Wilkens Aurélio; Andrade e Silva, Frederico; De Souza, Grace M

    2015-01-01

    The purpose of this study was to evaluate the effect of design and surface finishing on fracture strength of yttria-tetragonal zirconia polycrystal (Y-TZP) crowns in monolithic (1.5 mm thickness) and bilayer (0.8 mm zirconia coping and 0.7 mm porcelain veneer) configuration after artificial aging. Bovine incisors received crown preparation and Y-TZP crowns were manufactured using CAD/CAM technique, according to the following groups (n = 10): Polished monolithic zirconia crowns (PM); Glazed monolithic zirconia crowns (GM); Bi-layer crowns (BL). Crowns were cemented with resin cement, submitted to artificial aging in a chewing simulator (2.5 million cycles/80 N/artificial saliva/37 °C), and tested for fracture strength. Two remaining crowns referring to PM and GM groups were submitted to a chemical composition analysis to measure the level of yttrium after aging. One-way ANOVA and Tukey's test (P = .05) indicated that monolithic zirconia crowns presented similar fracture strength (PM = 3476.2 N ± 791.7; GM = 3561.5 N ± 991.6), which was higher than bilayer crowns (2060.4 N ± 810.6). There was no difference in the yttrium content among the three surfaces evaluated in the monolithic crowns. Thus, monolithic zirconia crowns present higher fracture strength than bilayer veneered zirconia after artificial aging and surface finishing does not affect their fracture strength.

  14. Enhancing a eucalypt crown condition indicator driven by high spatial and spectral resolution remote sensing imagery

    Science.gov (United States)

    Evans, Bradley; Lyons, Tom; Barber, Paul; Stone, Christine; Hardy, Giles

    2012-01-01

    Individual crown condition of Eucalyptus gomphocephala was assessed using two classification models to understand changes in forest health through space and time. Using high resolution (0.5 m) digital multispectral imagery, predictor variables were derived from textural and spectral variance of all pixels inside the crown area. The results estimate crown condition as a surrogate for tree health against the total crown health index. Crown condition is derived from combining ground-based crown assessment techniques of density, transparency, dieback, and the regrowth of foliage. This object-based approach summarizes the pixel data into mean crown indices assigned to crown objects which became the carrier of information. Models performed above expectations, with a significant weighted Cohen's kappa (κ>0.60 and p<0.001) using 70% of available data. Using in situ data for model development, crown condition was predicted forwards (2010) and backwards (2007) in time, capturing trends in crown condition and identifying decline in the healthiest between 2008 and 2010. The results confirm that combining spectral and textural information increased model sensitivity to small variations in crown condition. The methodology provides a cost-effective means for monitoring crown condition of this or other eucalypt species in native and plantation forests.

  15. Tree crown structure indicators in a natural uneven-aged mixed coniferous forest in northeastern Mexico

    Science.gov (United States)

    Javier Jimenez-Perez; Oscar Aguirre-Calderon; Horst Kramer

    2006-01-01

    Characterization of tree crown structure provides critical information to assess a variety of ecological conditions for multiple purposes and applications. For biomass growth, for example, tree crowns have basic physiological functions: assimilation, respiration, and transpiration. How tree crowns spatially interact and grow can bring about a seamless landscape of...

  16. The use of Hall technique preformed metal crowns by specialist paediatric dentists in the UK

    OpenAIRE

    Roberts, A; McKay, A; Albadri, S

    2018-01-01

    Examines treatment planning involving Hall technique preformed metal crowns by specialists in paediatric dentistry. Explores clinical situations in which specialists in paediatric dentistry feel it is appropriate or not to fit Hall technique preformed metal crowns. Investigates which types of carious lesions are being treated with Hall technique preformed metal crowns by specialists in paediatric dentistry.

  17. 18-Crown-6 and Dibenzo-18-crown-6 Assisted Extraction of Cesium from Water into Room Temperature Ionic Liquids and Its Correlation with Stability Constants for Cesium Complexes

    Directory of Open Access Journals (Sweden)

    Igor Vladimirovich Pletnev

    2009-12-01

    Full Text Available The pH-profiles of the extraction of Cs+ into four conventional (1-butyl-3-methylimidazolium hexafluorophosphate and bis[trifluoromethylsulphonyl]imides of 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, and 1-(2-ethylhexyl-3- methylimidazolium and two novel (trioctylmethylammonium salicylate and tetrahexylammonium dihexylsulfosuccinate room temperature ionic liquids have been determined both in the absence and in the presence of crown ether (18-crown-6 or dibenzo-18-crown-6. The pH-profiles of distribution ratio of crown ethers have been established in the same conditions. The relationship of cesium extraction efficiency both with the stability of its complexes with crown ethers and crown ethers’ distribution ratio has been clarified.

  18. Neurological complications of chickenpox

    Directory of Open Access Journals (Sweden)

    Girija A

    2007-01-01

    Full Text Available Aim: To assess the neurological complications of chickenpox with prognosis. Background: The neurological complications occur in 0.03% of persons who get chickenpox. There is no universal vaccination against chicken pox in India. Most patients prefer alternate modalities of treatment. Hence these complications of chickenpox are likely to continue to occur. Study Design: A prospective study was conducted for 2 years (from March 2002 on the admitted cases with neurological complications after chickenpox (with rash or scar. Patients were investigated with CT/MRI, CSF study, EEG and nerve conduction studies and hematological workup. They were followed-up for 1 year and outcome assessed using modified Rankin scale. Results: The latency for the neurological complications was 4-32 days (mean: 16.32 days. There were 18 cases: 10 adults (64% and 8 children (36%. Cerebellar ataxia (normal CT/MRI was observed in 7 cases (32% (mean age: 6.85 years. One patient (6 years had acute right hemiparesis in the fifth week due to left capsular infarct. All these cases spontaneously recovered by 4 weeks. The age range of the adult patients was 13-47 years (mean: 27 years. The manifestations included cerebellar and pyramidal signs (n-4 with features of demyelination in MRI who recovered spontaneously or with methylprednisolone by 8 weeks. Patient with encephalitis recovered in 2 weeks with acyclovir. Guillain Barre syndrome of the demyelinating type (n-2 was treated with Intravenous immunoglobulin (IVIG and they had a slow recovery by a modified Rankin scale (mRs score of 3 and 2 at 6 months and 1 year, respectively. One case died after hemorrhage into the occipital infarct. There were two cases of asymmetrical neuropathy, one each of the seventh cranial and brachial neuritis. Conclusion: Spontaneous recovery occurs in post-chickenpox cerebellar ataxia. Rarely, serious complications can occur in adults. The demyelinating disorders, either of the central or peripheral

  19. PEEK Primary Crowns with Cobalt-Chromium, Zirconia and Galvanic Secondary Crowns with Different Tapers—A Comparison of Retention Forces

    Directory of Open Access Journals (Sweden)

    Veronika Stock

    2016-03-01

    Full Text Available In prosthetic dentistry, double crown systems have proved their suitability as retainers for removable partial dentures. However, investigations in this context, regarding polyetheretherketone, are scarce. Therefore, the aim of this study was to test the retention force (RF between polyetheretherketone (PEEK primary and cobalt-chromium (CoCr, zirconia (ZrO2 and galvanic (GAL secondary crowns with three different tapers. Primary PEEK-crowns were milled with the tapers 0°, 1°, and 2° (n = 10/taper, respectively. Afterwards, 90 secondary crowns were fabricated: (i 30 CoCr-crowns milled from Ceramill Sintron (AmannGirrbach, Koblach, Austria (n = 10/taper, (ii 30 ZrO2-crowns milled from Ceramill ZI (AmannGirrbach, Koblach, Austria (n = 10/taper, and (iii 30 GAL-crowns made using electroforming (n = 10/taper. RF was measured in a pull-off test (20 pull-offs/specimen and data were analyzed using 2-/1-way Analysis of Variance (ANOVA followed by the Tukey-Honestly Significant Difference (HSD post hoc test and linear regression analyses (p < 0.05. The measured mean RF values ranged between 9.6 and 38.2 N. With regard to the 0°, 1°, and 2° tapered crowns, no statistically significant differences between CoCr and ZrO2 were observed (p > 0.141. At 0° taper, no differences in retention forces between GAL, CrCr, and ZrO2 crowns were found (p = 0.075. However, at 1° and 2° taper, lower RF for GAL-crowns were observed (p < 0.009, p < 0.001, respectively. According to this laboratory study, PEEK might be a suitable material for primary crowns, regardless of the taper and the material of secondary crown. Long-term results, however, are still necessary.

  20. Comparison of Primary Molar Crown Dimensions with Stainless Steel Crowns in a Sample of Iranian Children

    Directory of Open Access Journals (Sweden)

    Hossein Afshar

    2015-06-01

    Full Text Available Background and aims. Due to anatomic variation in tooth anatomy between populations, this study compared the buccolingual (BL and mesiodistal (MD dimensions of primary molars with those of stainless steel crowns (SSCs in anIranian population. Materials and methods. Impressions were taken from both dental arches of children, and casts were poured. Teeth with caries, restoration, hypoplasia or other dental anomalies were excluded. 216 primary molars were selected and divided into 4 groups of 54 each (maxillary and mandibular first and second primary molars. MD/BL dimensions were measured using a digital caliper with 0.01 mm precision on casts and SCCs (3M brand. Data were assessed using paired t-test, post hoc test and ANOVA. P < 0.05 was considered statistically significant. Results. The MD dimension of the lower first molar SSC and the BL dimension of the lower second molar SSC had the least difference with the corresponding values of the respective teeth. The MD dimension of the upper second molar SSC and the BL dimension of the upper first molar SSC had the greatest difference with the corresponding values in the respective teeth. Comparison of the two different brands of SSCs for the upper first molar revealed that both types had significant differences with the teeth in terms of both MD (P = 0.0 and BL (P = 0.0 dimensions. Conclusion. In the studied population, best adaptation was seen in second lower molars and the least adaptationswere seen in first and second upper molars.

  1. Tensile bond strength of ceramic crowns to dentin using resin cements.

    Science.gov (United States)

    Simon, James F; de Rijk, Waldemar G; Hill, Jennifer; Hill, Nathaniel

    2011-01-01

    This study measured the bond strength of the self-adhesive resin cements and a bonded resin cement for crowns bonded to extracted teeth with preparations having a total taper greater than 30 degrees. A crown pull-off test was used with direction of pull along the path of insertion. The CAD/CAM system Cerec was used to create crowns with the pull-off loop as an integral part of the crown structure. One hundred extracted human molars were prepared for all-ceramic crowns with a 1.5-mm shoulder, greater than 30-degree axial wall convergence, a flat occlusal surface and 3 to 5 mm occlusal/ gingival height. All-ceramic crowns were cemented with five different self-adhesive cements (Rely X Unicem, Maxcem Elite, BisCem, SmartCem 2, and G-Cem) and one bonded resin cement (Multilink). Forfour cements (excluding GCem and Multilink) there were 2 groups, one with HF etching and one without ceramic surface treatment. The crowns were then subject to tensile stress until either the crown fractured or the crown was lifted off from the tooth. For several cements, the bond strength exceeded the tensile strength of the all-ceramic crown; thus, the crown fractured, leaving the cemented part of the crown on the tooth. The effect of ceramic surface etching was not statistically significant at p = 0.05; however, for each cement, the treated crowns showed a lower coefficient of variance (COV). For this study, the COV ranged from 24.9 % to 97.9 %. Loads ranged from 41.3 to 190.3 N. Some of the new self-etching resin cements can create bonds to non-retentive crown preparations that are stronger than the strength of a ceramic crown; however, these high bond strengths may not be able to be achieved consistently.

  2. [Complications of Gaucher's disease].

    Science.gov (United States)

    Modrego Pardo, P J; Garzarán, G; González, N; Baiges, J J; Gazulla, J

    1992-10-01

    We discuss two cases of Gaucher's disease of the adult with neurological complications. First of the patients came to Hospital due to sudden pain in dorso-lumbar region and motor weakness of lower extremities. In the neurological exploration there were no concluding objective deficit signs except an unstable deambulation. After several hours of rest, symptoms disappeared progressively. In the radiology of the raquis a crushed in the last three dorsal vertebral was seen; this finding together with the clinic the patient showed, suggested a mild and transitory medullar compression. Second patient suffered an intraparenchymatous brain hemorrhage on the course of a platelet depletion and with other mild coagulation disorders. This type of complication have never been described in Gaucher's disease.

  3. Immediate postpartum complications.

    Science.gov (United States)

    St George, L; Crandon, A J

    1990-02-01

    Two hundred and sixty-nine (5.4%) of the 4,998 patients who delivered in Westmead Hospital, New South Wales in 1985 had immediate postpartum complications. This analysis was compared with figures from a major institution in another state of Australia. Early detection and prompt management without procrastination was the key to a successful outcome in the fourth stage of labour (i.e. within 24 hours of delivery). Nearly three-quarters of the complications were due to postpartum haemorrhage (PPH). The contributory factors are analysed and discussed. Reappraisal of the indications for induction of labour, epidural analgesia and forceps delivery is necessary to reduce the incidence of postpartum haemorrhage. The study reinforces the need for undiminished vigilance in the fourth stage of labour even if the first 3 stages are uncomplicated.

  4. [Complications of liver cirrhosis].

    Science.gov (United States)

    Bratović, Ismet; Jazić, Altaira

    2003-01-01

    Increase in portal venous pressure after anatomical or functional obstruction of portal venous system represents the most important complication of liver cirrhosis. Important sequels of portal hypertension are not dependable of etiology of liver disease. They are: increased collateral circulation in portal system and low pressure venous system (esophageal and gastric varices, portal hypertensive gastropathy and colopathy, hemorrhoids, collateral circulation through anterior abdominal wall, increased lymphatic flow, ascites, splenomegaly with occasional hypersplenismus, hepatic encephalopathy, hepatorenal syndrome.

  5. Thromboembolic Complications Following Trauma

    Science.gov (United States)

    2009-12-01

    these physiologic derangements, it is estimated that hypercoagulable disorders, such as factor V Leiden and hyperhomocysteinemia, may be present in...risk factors of venous thrombosis. Hum Genet 2001;109:369-84. 3. Knudson MM, Ikossi DG. Venous thromboembolism after trauma. Curr Opin Crit Care...R E V I E W A R T I C L E Thromboembolic complications following trauma Daniel F. McLaughlin, Charles E. Wade, Howard R. Champion, Jose Salinas, and

  6. Thrombophilia and Pregnancy Complications

    Directory of Open Access Journals (Sweden)

    Louise E. Simcox

    2015-11-01

    Full Text Available There is a paucity of strong evidence associated with adverse pregnancy outcomes and thrombophilia in pregnancy. These problems include both early (recurrent miscarriage and late placental vascular-mediated problems (fetal loss, pre-eclampsia, placental abruption and intra-uterine growth restriction. Due to poor quality case-control and cohort study designs, there is often an increase in the relative risk of these complications associated with thrombophilia, particularly recurrent early pregnancy loss, late fetal loss and pre-eclampsia, but the absolute risk remains very small. It appears that low-molecular weight heparin has other benefits on the placental vascular system besides its anticoagulant properties. Its use is in the context of antiphospholipid syndrome and recurrent pregnancy loss and also in women with implantation failure to improve live birth rates. There is currently no role for low-molecular weight heparin to prevent late placental-mediated complications in patients with inherited thrombophilia and this may be due to small patient numbers in the studies involved in summarising the evidence. There is potential for low-molecular weight heparin to improve pregnancy outcomes in women with prior severe vascular complications of pregnancy such as early-onset intra-uterine growth restriction and pre-eclampsia but further high quality randomised controlled trials are required to answer this question.

  7. Clinical Evaluation of Monolithic Zirconia Crowns: A Short-Term Pilot Report.

    Science.gov (United States)

    Kitaoka, Aki; Akatsuka, Ryo; Kato, Hiroaki; Yoda, Nobuhiro; Sasaki, Keiichi

    This study aimed to prospectively evaluate the clinical performance of monolithic zirconia crowns made of yttria-stabilized tetragonal zirconia polycrystal. A total of 26 crowns placed on premolar or molar teeth in 18 patients were evaluated at the time of crown placement and at 2 weeks, 6 months, 1 year, and 2 years after placement. Twenty-five crowns rated as satisfactory according to the California Dental Association quality evaluation system. Most of the abutment and antagonist teeth showed good periodontal condition. An enamel cracking occurred on one antagonist tooth 1 year after placement. Monolithic zirconia crowns can be a clinically acceptable prosthetic option.

  8. Failure analysis of various monolithic posterior aesthetic dental crowns using finite element method

    Science.gov (United States)

    Porojan, Liliana; Topală, Florin

    2017-08-01

    The aim of the study was to assess the effect of material stiffness and load on the biomechanical performance of the monolithic full-coverage posterior aesthetic dental crowns using finite element analysis. Three restorative materials for monolithic dental crowns were selected for the study: zirconia; lithium disilicate glass-ceramic, and resin-based composite. Stresses were calculated in the crowns for all materials and in the teeth structures, under different load values. The experiments show that dental crowns made from all this new aesthetic materials processed by CAD/CAM technologies would be indicated as monolithic dental crowns for posterior areas.

  9. Clinical evaluation of and parental satisfaction with resin-faced stainless steel crowns.

    Science.gov (United States)

    Roberts, C; Lee, J Y; Wright, J T

    2001-01-01

    This study evaluated the clinical success and parental acceptance of anterior primary dentition caries treatment with prefabricated resin-faced stainless steel crowns. A retrospective analysis of maxillary anterior primary dentition caries treatment using Whiter Biter II Crowns was performed. Each crown was evaluated for retention, fracture, interface failure, color match, marginal integrity, and surface texture. Parental satisfaction regarding the esthetics of the crowns was evaluated by survey. Thirty-eight crowns were evaluated in 12 children. The average crown age at time of examination was 20.7 months. Three teeth were lost to trauma with all other crowns remaining intact. Twelve crowns (32%) showed loss of at least some facial resin. Nine crowns (24%) had complete loss of the resin facing. Overall parental satisfaction with the treatment was excellent, however, satisfaction with crown esthetics received the lowest rating. While parental satisfaction with treatment of anterior primary dentition caries with prefabricated resin-faced stainless steel crowns is excellent, the high failure rate of the resin facings is problematic.

  10. Effect of water temperature on the fit of provisional crown margins during polymerization.

    Science.gov (United States)

    Ogawa, T; Aizawa, S; Tanaka, M; Matsuya, S; Hasegawa, A; Koyano, K

    1999-12-01

    When fabricating a provisional crown with the direct technique, dentists are concerned with margin discrepancies that result from polymerization shrinkage. This in vitro study examined the effect of water temperature on the fit of provisional crown margins during resin polymerization. The experiment was designed to simulate a direct technique to fabricate provisional crowns. After mixing autopolymerizing methyl methacrylate resin, the material was placed in a preformed polycarbonate crown. The crown was seated on a prepared premolar-shaped die with a shoulder margin. After 1 minute and 50 seconds, the crown was removed and polymerization was continued under the following conditions: 20 degrees C air, and water at 0 degrees C, 10 degrees C, 20 degrees C, 30 degrees C, 40 degrees C, 60 degrees C, and 80 degrees C. Six minutes after polymerization, the crown was trimmed and reseated on the die. Discrepancy of crown margin was measured with a 3-dimensional digitizer. Margin discrepancy varied with the condition during resin-polymerization (ANOVA, P crowns polymerized in 20 degrees C and 30 degrees C water revealed the best margin fit, showing 3 times more accurate margin fit than those polymerized in 20 degrees C air (Bonferroni/Dunn procedure, P provisional crowns using the direct technique. Water temperatures of 20 degrees C and 30 degrees C produced the best fit at the margin of the provisional crown.

  11. Canopy Fuel Load Mapping of Mediterranean Pine Sites Based on Individual Tree-Crown Delineation

    Directory of Open Access Journals (Sweden)

    Giorgos Mallinis

    2013-12-01

    Full Text Available This study presents an individual tree-crown-based approach for canopy fuel load estimation and mapping in two Mediterranean pine stands. Based on destructive sampling, an allometric equation was developed for the estimation of crown fuel weight considering only pine crown width, a tree characteristic that can be estimated from passive imagery. Two high resolution images were used originally for discriminating Aleppo and Calabrian pines crown regions through a geographic object based image analysis approach. Subsequently, the crown region images were segmented using a watershed segmentation algorithm and crown width was extracted. The overall accuracy of the tree crown isolation expressed through a perfect match between the reference and the delineated crowns was 34.00% for the Kassandra site and 48.11% for the Thessaloniki site, while the coefficient of determination between the ground measured and the satellite extracted crown width was 0.5. Canopy fuel load values estimated in the current study presented mean values from 1.29 ± 0.6 to 1.65 ± 0.7 kg/m2 similar to other conifers worldwide. Despite the modest accuracies attained in this first study of individual tree crown fuel load mapping, the combination of the allometric equations with satellite-based extracted crown width information, can contribute to the spatially explicit mapping of canopy fuel load in Mediterranean areas. These maps can be used among others in fire behavior prediction, in fuel reduction treatments prioritization and during active fire suppression.

  12. The marginal fit of selective laser melting-fabricated metal crowns: an in vitro study.

    Science.gov (United States)

    Xu, Dan; Xiang, Nan; Wei, Bin

    2014-12-01

    The selective laser melting technique is attracting interest in prosthetic dentistry. The marginal fit is a key criterion for fixed restorations. The purpose of the study was to evaluate the marginal fit of cast cobalt-chromium alloy crowns versus the fit of selective laser melting-fabricated crowns. The marginal gap widths of 36 single crowns (18 selective laser melting-fabricated cobalt-chromium metal crowns and 18 cobalt-chromium cast crowns) were determined with a silicone replica technique. Each crown specimen was cut into 4 sections, and the marginal gap width of each cross section was evaluated by stereomicroscopy (× 100). The Student t test was used to evaluate whether significant differences occurred in the marginal gap widths between the selective laser melting-fabricated and cast cobalt-chromium metal crowns (α=.05). The mean marginal gap width of the cast crowns (170.19 μm) was significantly wider than that of the selective laser melting-fabricated crowns (102.86 μm). Selective laser melting-fabricate cobalt-chromium dental crowns found improved marginal gap widths compared with traditional cast crowns. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  13. Crown ethers as size-selective synergists in solvent extraction systems: a new selectivity parameter

    International Nuclear Information System (INIS)

    Kinard, W.F.; McDowell, W.J.

    1981-01-01

    Mixtures of macrocyclic polyethers (crown ethers) and organic-phase-soluble liquid cation exchangers have been found to produce a synergistic effect in the extraction of metal ions. The synergistic effect is size selective; that is, it tends to be greatest for those ions that best fit the crown ether cavity. The mixtures of a liquid cation exchanger and a crown ether also allow metal ion extraction from common mineral-acid anion systems (NO 3 - , Cl - , SO 4 2- ) that would be impossible with the crown ether alone, because of the difficulty of solubilizing those anions in nonpolar solvents. This cooperation makes the use of crown ethers as size-selective coordinators available for process applications. Size selectivity of compounds such as crown ethers may thus become a useful new parameter in designing selective solvent extraction systems. Results are reported for alkali (including Cs) and alkaline earth (including Sr) extraction by HDEHP mixed with various crown ethers. (author)

  14. 18F-fluorination by crown ether-metal fluoride

    International Nuclear Information System (INIS)

    Irie, T.; Fukushi, K.; Ido, T.; Kasida, Y.; Nozaki, T.

    1982-01-01

    18 F-Fluorination by ''naked'' 18 F - anion produced by complexing anhydrous K 18 F, which was prepared from aqueous 18 F, with 18 -Crown-6 was described for preparing 18 F-21-fluoroprogesterone. In order to find out optimum conditions in this labelling method, various factors were investigated such as the solubility of KF in organic solvents containing 18 -Crown-6 and its reactivity for the nucleophilic displacement of 21-mesylate of progesterone. Chloroform was a good solvent in solubilization of KF and its reactivity. Problems in this labelling procedure were also examined, such as a supporter for transferring the labelled anhydrous K 18 F and reaction vessels. Use of a Teflon reaction vessel resulted in a good radiochemical yield based on the starting activity of $ 18 water. (author)

  15. 18F-fluorination by crown ether-metal fluoride

    International Nuclear Information System (INIS)

    Irie, T.; Fukushi, K.; Ido, T.; Kasida, Y.; Nozaki, T.

    1984-01-01

    For non-carrier-added 18 F-labeling of organic compounds, details were studied concerning the previously developed KF-crown ether method. In the modified method, a minute amount of KOH instead of carrier KF is added for the preparation of the anhydrous 18 F from aqueous carrier-free 18 F. The following factors were examined in order to determine optimum conditions for the preparation of the anhydrous non-carrier-added 18 F and the labeling synthesis with it: effects of the vessel on the evaporation of the 18 F-KOH solution and the amount of added KOH for the conversion of aqueous 18 F to anhydrous 18 F, the solubilized activity of the 18 F obtained by the evaporation in organic solutions containing 18-Crown-6 and the labeling reaction, as exemplified by the synthesis of 21-fluoroprogesterone. (author)

  16. Modeling tree crown dynamics with 3D partial differential equations.

    Science.gov (United States)

    Beyer, Robert; Letort, Véronique; Cournède, Paul-Henry

    2014-01-01

    We characterize a tree's spatial foliage distribution by the local leaf area density. Considering this spatially continuous variable allows to describe the spatiotemporal evolution of the tree crown by means of 3D partial differential equations. These offer a framework to rigorously take locally and adaptively acting effects into account, notably the growth toward light. Biomass production through photosynthesis and the allocation to foliage and wood are readily included in this model framework. The system of equations stands out due to its inherent dynamic property of self-organization and spontaneous adaptation, generating complex behavior from even only a few parameters. The density-based approach yields spatially structured tree crowns without relying on detailed geometry. We present the methodological fundamentals of such a modeling approach and discuss further prospects and applications.

  17. Modeling Tree Crown Dynamics with 3D Partial Differential Equations

    Directory of Open Access Journals (Sweden)

    Robert eBeyer

    2014-07-01

    Full Text Available We characterize a tree's spatial foliage distribution by the local leaf area density. Considering this spatially continuous variable allows to describe the spatiotemporal evolution of the tree crown by means of 3D partial differential equations. These offer a framework to rigorously take locally and adaptively acting effects into account, notably the growth towards light. Biomass production through photosynthesis and the allocation to foliage and wood are readily included in this model framework. The system of equations stands out due to its inherent dynamic property of self-organization and spontaneous adaptation, generating complex behavior from even only a few parameters. The density-based approach yields spatially structured tree crowns without relying on detailed geometry. We present the methodological fundamentals of such a modeling approach and discuss further prospects and applications.

  18. Design algorithm for generatrix profile of cylindrical crowned rollers

    Directory of Open Access Journals (Sweden)

    Creţu Spiridon

    2017-01-01

    Full Text Available The cross-section of roller profile controls the pressure distribution in the contact area and radically affects the roller bearings basic dynamic load rating and rating lives. Today the most used roller profiles are the logarithmic profile and cylindrical-crowned (ZB profile. The logarithmic profile has a continuous evolution with no discontinuities till the intersection with the end fillet while ZB profile has two more discontinuities at the intersections points between the crowning circle and straight line generatrix. Using a semianalytical method, a numerical study has been carried out to find the optimum ZB profile for rollers incorporated in cylindrical rollers bearings. The basic reference rating life (L10_r has been used as optimization criterion.

  19. Increasing the thermopower of crown-ether-bridged anthraquinones

    Science.gov (United States)

    Ismael, Ali K.; Grace, Iain; Lambert, Colin J.

    2015-10-01

    We investigate strategies for increasing the thermopower of crown-ether-bridged anthraquinones. The novel design feature of these molecules is the presence of either (1) crown-ether or (2) diaza-crown-ether bridges attached to the side of the current-carrying anthraquinone wire. The crown-ether side groups selectively bind alkali-metal cations and when combined with TCNE or TTF dopants, provide a large phase-space for optimising thermoelectric properties. We find that the optimum combination of cations and dopants depends on the temperature range of interest. The thermopowers of both 1 and 2 are negative and at room temperature are optimised by binding with TTF alone, achieving thermpowers of -600 μV K-1 and -285 μV K-1 respectively. At much lower temperatures, which are relevant to cascade coolers, we find that for 1, a combination of TTF and Na+ yields a maximum thermopower of -710 μV K-1 at 70 K, whereas a combination of TTF and Li+ yields a maximum thermopower of -600 μV K-1 at 90 K. For 2, we find that TTF doping yields a maximum thermopower of -800 μV K-1 at 90 K, whereas at 50 K, the largest thermopower (of -600 μV K-1) is obtain by a combination TTF and K+ doping. At room temperature, we obtain power factors of 73 μW m-1 K-2 for 1 (in combination with TTF and Na+) and 90 μW m-1 K-2 for 2 (with TTF). These are higher or comparable with reported power factors of other organic materials.We investigate strategies for increasing the thermopower of crown-ether-bridged anthraquinones. The novel design feature of these molecules is the presence of either (1) crown-ether or (2) diaza-crown-ether bridges attached to the side of the current-carrying anthraquinone wire. The crown-ether side groups selectively bind alkali-metal cations and when combined with TCNE or TTF dopants, provide a large phase-space for optimising thermoelectric properties. We find that the optimum combination of cations and dopants depends on the temperature range of interest. The

  20. Theobrominium perchlorate dibenzo-18-crown-6 3.25-hydrate

    Directory of Open Access Journals (Sweden)

    Vladislav Kulikov

    2013-07-01

    Full Text Available The co-crystal, C7H9N4O2+·ClO4−·C20H24O6·3.25H2O, consists of theobrominium (3,7-dimethyl-2,6-dioxo-1H-purin-9-ium cations, perchlorate anions and dibenzo-18-crown-6 and water molecules. The crown ether is in a bent conformation, in which the planes of the aromatic rings subtend an angle of 63.7 (1°. Intermolecular O—H...O hydrogen bonding between the water molecules and the O atoms of the cyclic ether delimit an empty space reminiscent of a hollow cage. The water molecules are additionally linked to the cations by N—H...O hydrogen bonding. One of the positions of the water molecules is occupied only fractionally (25% and is located outside this framework.

  1. Predicting adverse obstetric outcome after early pregnancy events and complications: a review

    DEFF Research Database (Denmark)

    van Oppenraaij, R H F; Jauniaux, E; Christiansen, O B

    2009-01-01

    pregnancy with an OR > 2.0 after complications in the index pregnancy are the risk of LBW and very low birthweight (VLBW) after a threatened miscarriage, the risk of pregnancy-induced hypertension, pre-eclampsia, placental abruption, preterm delivery (PTD), small for gestational age and low 5-min Apgar...... score after detection of an intrauterine haematoma, the risk of VPTD and intrauterine growth restriction after a crown-rump length discrepancy, the risk of VPTD, LBW and VLBW after a vanishing twin phenomenon and the risk of PTD, LBW and low 5-min Apgar score in a pregnancy complicated by severe...

  2. [Finite element analysis of the maxillary central incisor with traditional and modified crown lengthening surgery and post-core restoration in management of crown-root fracture].

    Science.gov (United States)

    Zhen, M; Wei, Y P; Hu, W J; Rong, Q G; Zhang, H

    2016-06-01

    To construct three-dimensional finite element models with modified crown lengthening surgery and post-core restoration in management of various crown-root fracture types, to investigate the intensity and distribution of stressin models mentioned above, and to compare and analyze the indications of traditional and modified crown lengthening surgeries from the mechanic point of view. Nine three-dimensional finite element models with modified crown lengthening surgery and post-core restoration were established and analyzed by micro-CT scanning technique, dental impression scanner, Mimics 10.0, Geomagic studio 9.0 and ANSYS 14.0 software. The von Mises stress of dentin, periodontal ligament, alveolar bone, post and core, as well as the periodontal ligament area and threshold limit value were calculated and compared with the findings of traditional crown lengthening models which had been published earlierby our research group. The von Mises stress intensity of modified crown lengthening models were: dentin>post>core>alveolar bone>periodontal ligament. The maximum von Mises stress of dentin(44.37-80.58 MPa)distributed in lingual central shoulder. The periodontal ligament area of the modified crown lengthening surgery was reduced by 6% to 28%, under the same crown-root fracture conditions, the periodontal ligament area of modified crown lengthening models was larger than that of the traditional crown lengthening models. In modified crown lengthening surgery models, the von Mises stress of periodontal ligament of B3L1m, B3L2m, B3L3m models exceeded their limit values, however, the von Mises stress of periodontal ligament of the B2L2c, B2L3c, B3L1c, B3L2c, B3L3c models exceeded their limit values in traditional crown lengthening surgery models. The modified crown lengthening surgery conserves more periodontal supporting tissues, which facilitates the long-term survival of teeth. The indication of modified crown lengthening surgery is wider than traditional method. The

  3. Fracture toughness of zirconia ceramic crowns made by feather-edge tooth preparation design

    Directory of Open Access Journals (Sweden)

    Mirković Nemanja

    2012-01-01

    Full Text Available Background/Aim. Fracture toughness determines functional crown strenght and prevents damages on ceramics during mastication. There is a lack of relevant literature data about fracture toughness of crowns made by feather-edge preparation. Mechanical testing of ceramic samples is supposed to show if feather-edge tooth preparation is a successful method for making ceramic crowns without any risk of reduction of their mechanical properties. This research was done to establish effects of feather-edge tooth preparation on fracture toughness of single zirconia ceramic crowns. Methods. The research was performed as an experimental study. Sixty (60 ceramic crowns were made on non-carious extracted human premolars. Thirty (30 crowns were made on the basis of feather-edge preparation (experimental group I. The group II included 30 crowns made on 1 mm rounded shoulder. Crowns fabrication was executed on a copy mill production system “Zirkonzahn” (Zirkonzahn GMBH, Gais, Germany. The spherical compression test was used to determine fracture toughness, using 6 mm diameter ceramic ball. Fracture load for damaging ceramic crown was recorded on a universal testing machine - Zwick, type 1464, with the speed of 0.05 mm/min. Results. The results of this research introduced significant differences between fracture toughness of ceramic samples in every examined group. However, fracture toughness of crowns from both group was above 2 000 N, what was double beyond a recommended value. The mean value of fracture toughness in the feather-edge group was 2 090 N, and in shoulder group it was 2 214 N. Conclusion. This research showed a high fracture toughness of zirconia crowns made on feather-edge preparation. The examined crowns showed a fracture resistance at a sufficient distance in relation to the minimum values of functional loads. Further research of functional loads of these crown is necessary, as well as research of marginal adaptation of cemented crowns and

  4. [Fracture toughness of zirconia ceramic crowns made by feather-edge tooth preparation design].

    Science.gov (United States)

    Mirković, Nemanja; Gostović, Aleksandra Spadijer; Lazić, Zoran; Trifković, Branka

    2012-07-01

    Fracture toughness determines functional crown strenght and prevents damages on ceramics during mastication. There is a lack of relevant literature data about fracture toughness of crowns made by feather-edge preparation. Mechanical testing of ceramic samples is supposed to show if feather-edge tooth preparation is a successful method for making ceramic crowns without any risk of reduction of their mechanical properties. This research was done to establish effects of feather-edge tooth preparation on fracture toughness of single zirconia ceramic crowns. The research was performed as an experimental study. Sixty (60) ceramic crowns were made on non-carious extracted human premolars. Thirty (30) crowns were made on the basis of feather-edge preparation (experimental group I). The group II included 30 crowns made on 1 mm rounded shoulder. Crowns fabrication was executed on a copy mill production system "Zirkonzahn" (Zirkonzahn GMBH, Gais, Germany). The spherical compression test was used to determine fracture toughness, using 6 mmn diameter ceramic ball. Fracture load for damaging ceramic crown was recorded on a universal testing machine--Zwick, type 1464, with the speed of 0.05 mm/min. The results of this research introduced significant differences between fracture toughness of ceramic samples in every examined group. However, fracture toughness of crowns from both group was above 2000 N, what was double beyond a recommended value. The mean value of fracture toughness in the feather-edge group was 2090 N, and in shoulder group it was 2214 N. This research showed a high fracture toughness of zirconia crowns made on feather-edge preparation. The examined crowns showed a fracture resistance at a sufficient distance in relation to the minimum values of functional loads. Further research of functional loads of these crown is necessary, as well as research of marginal adaptation of cemented crowns and gingival inflammatory response.

  5. Synthesis and Characterisation of Macrocyclic Diamino Chiral Crown Ethers

    Directory of Open Access Journals (Sweden)

    Janet L. Scott

    2004-05-01

    Full Text Available A benign and efficient synthesis of chiral macrocyclic ‘aza-crown’ ethers of varying ring size is reported. The synthesis involves a Schiff base condensation of ether linked dialdehydes of varying chain length and (1R,2R-(–-1,2-diaminocyclohexane under mild conditions to yield the macrocycles, which are subsequently reduced to yield the diamino analogues.

  6. Laboratory fire behavior measurements of chaparral crown fire

    Science.gov (United States)

    C. Sanpakit; S. Omodan; D. Weise; M Princevac

    2015-01-01

    In 2013, there was an estimated 9,900 wildland fires that claimed more than 577,000 acres of land. That same year, about 542 prescribed fires were used to treat 48,554 acres by several agencies in California. Being able to understand fires using laboratory models can better prepare individuals to combat or use fires. Our research focused on chaparral crown fires....

  7. Provisional Crown Dislodgement during Scuba Diving: A Case of Barotrauma

    OpenAIRE

    Gulve, Meenal Nitin; Gulve, Nitin Dilip

    2013-01-01

    Changes in ambient pressure, for example, during flying, diving, or hyperbaric oxygen therapy, can lead to barotrauma. Although it may seem that this issue was neglected in dental education and research in recent decades, familiarity with and understanding of these facts may be of importance for dental practitioners. We report the case of a patient who experienced barotrauma involving dislodgement of a provisional crown during scuba diving. Patients who are exposed to pressure changes as a pa...

  8. In vitro evaluation of the marginal integrity of CAD/CAM interim crowns.

    Science.gov (United States)

    Kelvin Khng, Kwang Yong; Ettinger, Ronald L; Armstrong, Steven R; Lindquist, Terry; Gratton, David G; Qian, Fang

    2016-05-01

    The accuracy of interim crowns made with computer-aided design and computer-aided manufacturing (CAD/CAM) systems has not been well investigated. The purpose of this in vitro study was to evaluate the marginal integrity of interim crowns made by CAD/CAM compared with that of conventional polymethylmethacrylate (PMMA) crowns. A dentoform mandibular left second premolar was prepared for a ceramic crown and scanned for the fabrication of 60 stereolithical resin dies, half of which were scanned to fabricate 15 Telio CAD-CEREC and 15 Paradigm MZ100-E4D-E4D crowns. Fifteen Caulk and 15 Jet interim crowns were made on the remaining resin dies. All crowns were cemented with Tempgrip under a 17.8-N load, thermocycled for 1000 cycles, placed in 0.5% acid fuschin for 24 hours, and embedded in epoxy resin before sectioning from the mid-buccal to mid-lingual surface. The marginal discrepancy was measured using a traveling microscope, and dye penetration was measured as a percentage of the overall length under the crown. The mean vertical marginal discrepancy of the conventionally made interim crowns was greater than for the CAD/CAM crowns (P=.006), while no difference was found for the horizontal component (P=.276). The mean vertical marginal discrepancy at the facial surface of the Caulk crowns was significantly greater than that of the other 3 types of interim crowns (Pcrowns was significantly larger than that of the other 3 types, with no difference at the lingual margins (P=.150). The mean percentage dye penetration for the Paradigm MZ100-E4D crowns was significantly greater and for Jet crowns significantly smaller than for the other 3 crowns (Pcrowns at the facial surface and with the horizontal marginal discrepancies of the Caulk interim crowns at the lingual surface (Pcrowns fabricated by CAD/CAM as compared with PMMA crowns; however, this difference was not observed for the horizontal component. The percentage dye penetration was correlated with vertical and horizontal

  9. Keratomycosis complicating pterygium excision

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    Merle H

    2011-10-01

    Full Text Available Harold Merle1, Jérôme Guyomarch1, Jean-Christophe Joyaux1, Maryvonne Dueymes2, Angélique Donnio1, Nicole Desbois2 1Department of Ophthalmology, 2Laboratory of Microbiology, University Hospital of Fort-de-France, Martinique, French West Indies Abstract: The authors describe a case of keratomycosis that appeared after the exeresis of a pterygium. A 48-year-old patient had been referred with a red right eye associated with an abscess of the cornea along the ablation zone of the pterygium. The surgery had been performed a month beforehand. The abscess was 6 mm high and 4 mm wide. The authors instigated a treatment that included amphotericin B (0.25% after noticing a clinical aspect evoking a fungal keratitis and finding several septate filaments on direct examination. On day 10, a Fusarium dimerum was isolated on Sabouraud agar. After 15 days of treatment, the result was favorable and the size of the ulceration as well as the size of the abscess had progressively decreased. The antifungal treatment was definitively stopped at 14 weeks. Infectious-related complications of the pterygium surgery are rare and are essentially caused by bacterial agents. Secondary infections by fungus are rare. There have been two previous cases reported: one that appeared 15 years after radiotherapy and another that appeared at 3 weeks post surgery, consecutive to the use of mitomycin C. To the authors' knowledge, this is the first case of a keratomycosis due to F. dimerum reported that complicated the exeresis of a pterygium without the use of an adjuvant antihealing treatment. Pterygium surgery is a common procedure; nevertheless, ophthalmologists need to be aware of the existence of potential infectious complications. Keywords: keratitis, corneal abscess, Fusarium

  10. Cryptococcal meningitis complicating sarcoidosis.

    Science.gov (United States)

    Leonhard, Sonja E; Fritz, Daan; van de Beek, Diederik; Brouwer, Matthijs C

    2016-08-01

    Cryptococcal meningitis is an uncommon but severe complication of sarcoidosis. We present 2 patients with cryptococcal meningitis complicating sarcoidosis and compared findings with 38 cases reported in the literature. When analyzing our patients and 38 cases reported in the literature, we found that median age of sarcoidosis patients with cryptococcal meningitis was 39 years (range 30-48); 27 of 33 reported cases (82%) had a history of sarcoidosis. Only 16 of 40 patients (40%) received immunomodulating therapy at the time of diagnosis of cryptococcal meningitis. The diagnosis of cryptococcal meningitis was delayed in 17 of 40 patients (43%), mainly because of the initial suspicion of neurosarcoidosis. Cerebrospinal fluid (CSF) examination showed mildly elevated white blood cell count (range 23-129/mm). Twenty-nine of 32 cases (91%) had a positive CSF culture for Cryptococcus neoformans and 25 of 27 cases (93%) had a positive CSF C neoformans antigen test. CD4 counts were low in all patients in whom counts were performed (84-228/mL). Twelve patients had an unfavorable outcome (32%), of which 7 died (19%) and 24 patients (65%) had a favorable outcome. The rate of unfavorable outcome in patients with a delayed diagnosis was 7 of 17 (41%) compared to 5 of 28 (21%) in patients in whom diagnosis was not delayed. Cryptococcal meningitis is a rare but life-threatening complication of sarcoidosis. Patients were often initially misdiagnosed as neurosarcoidosis, which resulted in considerable treatment delay and worse outcome. CSF cryptococcal antigen tests are advised in patients with sarcoidosis and meningitis.

  11. Predicting complicated choledocholithiasis.

    Science.gov (United States)

    Kummerow, Kristy L; Shelton, Julia; Phillips, Sharon; Holzman, Michael D; Nealon, William; Beck, William; Sharp, Kenneth; Poulose, Benjamin K

    2012-09-01

    Management of choledocholithiasis and its complications is variable and often requires transfer to a specialty facility. This study links patient-specific characteristics with the outcome measure of complicated choledocholithiasis to identify high-risk patients who may require expedited treatment or transfer to a higher level of care. Patients with a discharge diagnosis of choledocholithiasis (CDL) were identified from the 2009 Nationwide Inpatient Sample (NIS). Patient characteristics were identified associated with the primary outcome measure of complicated choledocholithiasis (cCDL), defined as acute pancreatitis or cholangitis during the admission for CDL. Predictors of mortality were also evaluated. Analysis was performed using complex-sample univariate and adjusted analyses. We identified 123,990 discharges with a diagnosis of CDL. The overall incidence of CDL was 314 per 100,000 NIS discharges. Forty-one percent of CDL discharges were for cCDL (acute pancreatitis 31%, cholangitis 12%). Risk factors for cCDL included age (risk increased 0.8% per year), male gender (odds ratio [OR] 1.2, 95% confidence interval [CI] 1.1-1.2), alcohol abuse (OR 1.5, CI 1.3-1.8), diabetes (OR 1.1, CI 1.0-1.2), hypertension (OR 1.1, CI 1.0-1.2), obesity (OR 1.2, CI 1.1-1.3), nonelective admission (OR 2.3, CI 2.0-2.6), and Asian/Pacific Islander race/ethnicity (OR 1.2, CI 1.0-1.5). Patients with cCDL had increased odds of mortality (OR 1.5, CI 1.2-2.0). Increased age, nonelective admission, and specific comorbid conditions are associated with cCDL, which has increased mortality. These factors can be used to identify patients needing timely access to treatment or transfer to a higher level of care. Copyright © 2012 Elsevier Inc. All rights reserved.

  12. Neurologic complications of metronidazole.

    Science.gov (United States)

    Sarna, Justyna R; Furtado, Sarah; Brownell, A Keith W

    2013-11-01

    Metronidazole (Flagyl®) is an antimicrobial agent commonly used in clinical practice. Although it is generally well tolerated with minimal side effects, there are a host of still under-recognized neurologic complications of metronidazole treatment. The following review is aimed at summarizing current literature pertaining to metronidazole-induced neurotoxicity including clinical syndromes, neuroradiological findings, prognosis and proposed pathophysiology. Recognition of the neurotoxic effects of metronidazole is critical as prompt discontinuation is generally associated with full clinical recovery and radiological resolution. Complications neurologiques du métronidazole. Le métronidazole (Flagyl®) est un agent antimicrobien utilisé couramment en pratique clinique. Bien qu'il soit généralement bien toléré et que ses effets secondaires soient minimes, il existe une myriade de complications neurologiques du traitement par le métronidazole qui ne sont pas toujours reconnues. Le but de cette revue constitue un sommaire de la littérature actuelle concernant la neurotoxicité induite par le métronidazole dont les syndromes cliniques, les constatations neuroradiologiques, le pronostic et l'hypothèse physiopathologique expliquant cette neurotoxicité. Il est important d'identifier ces effets neurotoxiques du métronidazole étant donné que l'arrět immédiat du traitement est généralement associé à une guérison clinique complète et à la disparition des signes radiologiques.

  13. Complications of decorative tattoo.

    Science.gov (United States)

    Shinohara, Michi M

    2016-01-01

    Decorative tattoo is a popular practice that is generally safe when performed in the professional setting but can be associated with a variety of inflammatory, infectious, and neoplastic complications, risks that may be increased with current trends in home tattooing. Modern tattoo inks contain azo dyes and are often of unknown composition and not currently regulated for content or purity. Biopsy of most (if not all) tattoo reactions presenting to the dermatologist is recommended, given recent clusters of nontuberculous mycobacterial infections occurring within tattoo, as well as associations between tattoo reactions and systemic diseases such as sarcoidosis. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. ACUTE APPENDICITIS COMPLICATING PREGNANCY

    Science.gov (United States)

    Sprong, David H.; Pollock, William F.

    1959-01-01

    Acute appendicitis occurs as a complication of pregnancy in about 0.1 per cent of cases. Diagnosis may be somewhat more difficult during the second and third trimesters dur to the displacement of viscera and the increased incidence of pyelitis and constipation. It is based on the same symptoms and signs as in nonpregnant patients. The treatment is immediate operation regardless of the stage of pregnancy. A McBurney incision is preferred and it is placed somewhat higher than usual in the later stages of pregnancy. When operation is done promptly there is little danger to either mother or fetus. PMID:13833485

  15. Lemierre's Syndrome Complicating Pregnancy

    Directory of Open Access Journals (Sweden)

    M. Thompson

    2007-01-01

    Full Text Available Lemierre's syndrome is an anaerobic suppurative thrombophlebitis involving the internal jugular vein secondary to oropharyngeal infection. There is only one previous case report in pregnancy which was complicated by premature delivery of an infant that suffered significant neurological damage. We present an atypical case diagnosed in the second trimester with a live birth at term. By reporting this case, we hope to increase the awareness of obstetricians to the possibility of Lemierre's syndrome when patients present with signs of unabating oropharyngeal infection and pulmonary symptoms.

  16. Complications of cancer therapy

    International Nuclear Information System (INIS)

    Moskowitz, P.S.; Parker, B.R.

    1985-01-01

    The purpose of this chapter is to review systematically the toxicity of contemporary chemotherapy and irradiation on normal tissues of growing children. Whenever possible, the separate toxicity of chemotherapy, irradiation, and combination therapy is addressed. However, it is not always possible to quantitate specifically such reactions in the face of multiple drug therapy, which may enhance radiation injury or reactivate prior radiation injury. Prior detailed reviews have provided important sources of information concerning radiation injury for this more general discussion. The information provided will assist both the clinician and the radiologist in the recognition of early and late complications of therapy in pediatric oncology

  17. Management of complicated wounds.

    Science.gov (United States)

    Hendrix, Sam M; Baxter, Gary M

    2005-04-01

    Most injuries, including those with significant tissue loss, can be successfully managed with proper therapy. With delayed healing, potential causes for the delay, such as sequestra, foreign bodies, and excessive motion,should be determined and treated to permit complete wound resolution. Horses have the innate ability to heal rapidly; however, minor injuries can quickly turn into complicated wounds, given the severity of the inciting trauma and the less than ideal environment in which the horses are housed. Wound management must focus on a combination of timely surgical and medical intervention to ensure the best potential outcome.

  18. Reliability of metalloceramic and zirconia-based ceramic crowns.

    Science.gov (United States)

    Silva, N R F A; Bonfante, E A; Zavanelli, R A; Thompson, V P; Ferencz, J L; Coelho, P G

    2010-10-01

    Despite the increasing utilization of all-ceramic crown systems, their mechanical performance relative to that of metal ceramic restorations (MCR) has yet to be determined. This investigation tested the hypothesis that MCR present higher reliability over two Y-TZP all-ceramic crown systems under mouth-motion fatigue conditions. A CAD-based tooth preparation with the average dimensions of a mandibular first molar was used as a master die to fabricate all restorations. One 0.5-mm Pd-Ag and two Y-TZP system cores were veneered with 1.5 mm porcelain. Crowns were cemented onto aged (60 days in water) composite (Z100, 3M/ESPE) reproductions of the die. Mouth-motion fatigue was performed, and use level probability Weibull curves were determined. Failure modes of all systems included chipping or fracture of the porcelain veneer initiating at the indentation site. Fatigue was an acceleration factor for all-ceramic systems, but not for the MCR system. The latter presented significantly higher reliability under mouth-motion cyclic mechanical testing.

  19. Reliability of Metalloceramic and Zirconia-based Ceramic Crowns

    Science.gov (United States)

    Silva, N.R.F.A.; Bonfante, E.A.; Zavanelli, R.A.; Thompson, V.P.; Ferencz, J.L.; Coelho, P.G.

    2010-01-01

    Despite the increasing utilization of all-ceramic crown systems, their mechanical performance relative to that of metal ceramic restorations (MCR) has yet to be determined. This investigation tested the hypothesis that MCR present higher reliability over two Y-TZP all-ceramic crown systems under mouth-motion fatigue conditions. A CAD-based tooth preparation with the average dimensions of a mandibular first molar was used as a master die to fabricate all restorations. One 0.5-mm Pd-Ag and two Y-TZP system cores were veneered with 1.5 mm porcelain. Crowns were cemented onto aged (60 days in water) composite (Z100, 3M/ESPE) reproductions of the die. Mouth-motion fatigue was performed, and use level probability Weibull curves were determined. Failure modes of all systems included chipping or fracture of the porcelain veneer initiating at the indentation site. Fatigue was an acceleration factor for all-ceramic systems, but not for the MCR system. The latter presented significantly higher reliability under mouth-motion cyclic mechanical testing. PMID:20660796

  20. Plant responses to Agrobacterium tumefaciens and crown gall development

    Science.gov (United States)

    Gohlke, Jochen; Deeken, Rosalia

    2014-01-01

    Agrobacterium tumefaciens causes crown gall disease on various plant species by introducing its T-DNA into the genome. Therefore, Agrobacterium has been extensively studied both as a pathogen and an important biotechnological tool. The infection process involves the transfer of T-DNA and virulence proteins into the plant cell. At that time the gene expression patterns of host plants differ depending on the Agrobacterium strain, plant species and cell-type used. Later on, integration of the T-DNA into the plant host genome, expression of the encoded oncogenes, and increase in phytohormone levels induce a fundamental reprogramming of the transformed cells. This results in their proliferation and finally formation of plant tumors. The process of reprogramming is accompanied by altered gene expression, morphology and metabolism. In addition to changes in the transcriptome and metabolome, further genome-wide (“omic”) approaches have recently deepened our understanding of the genetic and epigenetic basis of crown gall tumor formation. This review summarizes the current knowledge about plant responses in the course of tumor development. Special emphasis is placed on the connection between epigenetic, transcriptomic, metabolomic, and morphological changes in the developing tumor. These changes not only result in abnormally proliferating host cells with a heterotrophic and transport-dependent metabolism, but also cause differentiation and serve as mechanisms to balance pathogen defense and adapt to abiotic stress conditions, thereby allowing the coexistence of the crown gall and host plant. PMID:24795740

  1. Assessment of nickel release from stainless steel crowns.

    Directory of Open Access Journals (Sweden)

    Nahid Ramazani

    2014-06-01

    Full Text Available Adverse effects of dental materials, especially metals, have been an important issue in recent decades.The purpose of this study was to determine the amount of nickel released from stainless steel crowns in artificial saliva.In this in-vitro study, 270 stainless steel crowns were divided into five groups, each with nine subgroups. Each group (I to V was comprised of four, five, six, seven and eight crowns, respectively. Each subgroup was placed in a polyethylene jar containing artificial saliva and held in an incubator at 37°C for four weeks. The amount of released nickel was determined on days 1, 7, 14, 21 and 28, using an atomic absorption spectrophotometer. Wilcoxon Signed-Rank and Kruskal-Wallis with Dunn's post hoc tests (SPSS software, v. 18 were used for statistical analysis at a significance level of 0.05.The mean level of nickel on day 1 was more than that of day 7; this difference was statistically significant for all groups (P < 0.05, except for group II (P = 0.086. Also, the mean difference of released nickel between the groups was significant on day 1 (P = 0.006 and was insignificant on day 7 (P = 0.620. The nickel levels were zero on days 14, 21, and 28.The amount of nickel was below the toxic level and did not exceed the dietary intake.

  2. Surgical crown lengthening: a 12-month study - radiographic results

    Directory of Open Access Journals (Sweden)

    Daniela Eleutério Diniz

    2007-08-01

    Full Text Available OBJECTIVE: The purpose of this study was to perform a radiographic follow-up evaluation after a 12-month healing period, following crown lengthening surgery. MATERIAL AND METHODS: Twenty-three periodontally healthy subjects (mean age 32.5 years that required crown lengthening surgery in premolars were recruited. In a total of 30 premolars, full thickness flaps, osseous resection, and flap suturing were performed. The restorative margin was defined in the pre-surgical phase and maintained unaltered during the healing period, serving as a reference point. Standardized bitewing radiographs were taken before and after osseous reduction, and at 2, 3, 6, and 12-month healing periods. RESULTS: Intact lamina dura was observed at both mesial and distal alveolar crests only from the 3rd month. At 12-months, all alveolar crests presented lamina dura. The overall mean distance from the restorative margin to the alveolar crest achieved after osseous resection was 3.28±0.87 mm at mesial and 2.81±0.51 mm at distal sites. No significant radiographic changes in the bone crest were observed during a 12-month healing period. CONCLUSION: The findings of this study suggest that the radiographic proximal bone level observed on bitewing radiographs following crown lengthening surgery can be used as a reference to predict the future level of the healed alveolar crest.

  3. Dental ceramics and the molar crown testing ground

    Directory of Open Access Journals (Sweden)

    Van P. Thompson

    2004-01-01

    Full Text Available All ceramic crowns are highly esthetic restorations and their popularity has risen with the demand for life-like and cosmetic dentistry. Recent ceramic research has concentrated on developing a fundamental understanding of ceramic damage modes as influenced by microstructure. Dental investigations have elucidated three damage modes for ceramic layers in the 0.5-2 mm thickness using point contacts that duplicate tooth cuspal radii; classic Hertzian cone cracking, yield (pseudo-plastic behavior, and flexural cracking. Constitutive equations based upon materials properties have been developed that predict the damage modes operational for a given ceramic and thickness. Ceramic thickness or thickness of the stiff supporting core in layer crowns is critical in flexural cracking as well as the flaw state of the inner aspect of the crown. The elastic module of the supporting structure and of the luting cement and its thickness play a role in flexural fracture. Clinical studies of ceramics extending over 16 years are compared to the above relationships and predictions. Recommendations for clinical practice are made based upon the above.

  4. In vitro study of fracture strength of provisional crown materials.

    Science.gov (United States)

    Karaokutan, Isil; Sayin, Gulsum; Kara, Ozlem

    2015-02-01

    The purpose of this report was to evaluate the effect of the fabrication method and material type on the fracture strength of provisional crowns. A master model with one crown (maxillary left second premolar) was manufactured from Cr-Co alloy. The master model was scanned, and the data set was transferred to a CAD/CAM unit (Yenamak D50, Yenadent Ltd, Istanbul, Turkey) for the Cercon Base group. For the other groups, temporary crowns were produced by direct fabrication methods (Imident, Temdent, Structur Premium, Takilon, Systemp c&b II, and Acrytemp). The specimens were subjected to water storage at 37℃ for 24 hours, and then they were thermocycled (TC, 5000×, 5-55℃) (n=10). The maximum force at fracture (Fmax) was measured in a universal test machine at 1 mm/min. Data was analyzed by non-parametric statistics (α=.05). Fmax values varied between 711.09-1392.1 N. In the PMMA groups, Takilon showed the lowest values (711.09 N), and Cercon Base showed the highest values (959.59 N). In the composite groups, Structur Premium showed the highest values (1392.1 N), and Acrytemp showed the lowest values (910.05 N). The composite groups showed significantly higher values than the PMMA groups (P=.01). Composite-based materials showed significantly higher fracture strengths than PMMA-based materials. The CAD-CAM technique offers more advantages than the direct technique.

  5. Descriptive statistics of tree crown condition in the Southern United States and impacts on data analysis and interpretation

    Science.gov (United States)

    KaDonna C. Randolph

    2006-01-01

    The U.S. Department of Agriculture Forest Service, Forest Inventory and Analysis Program (FIA) utilizes visual assessments of tree crown condition to monitor changes and trends in forest health. This report describes and discusses distributions of three FIA crown condition indicators (crown density, crown dieback, and foliage transparency) for trees in the Southern...

  6. Comparative evaluation of marginal leakage of provisional crowns cemented with different temporary luting cements: In vitro study

    Directory of Open Access Journals (Sweden)

    Sheen Juneja Arora

    2016-01-01

    Conclusion: The temporary cements with eugenol showed more microleakage than those without eugenol. SC-10 crowns showed more microleakage compared to Protemp 4 crowns. SC-10 crowns cemented with Kalzinol showed maximum microleakage and Protemp 4 crowns cemented with HY bond showed least microleakage.

  7. Immediate implant placement and complete mouth rehabilitation with CAD-CAM titanium frameworks and cemented crowns for a patient with severe periodontal disease: A clinical report.

    Science.gov (United States)

    Wang, Pei; Tang, Chunbo; Tang, Yi; Wu, Yunong

    2017-08-04

    The technique of immediate implantation has been widely used to reduce treatment time and bone loss after extraction. However, immediate implant placement in infected extraction sockets is generally contraindicated. This clinical report describes a treatment protocol for immediate implantation after the extraction of teeth with generalized chronic periodontitis. The technique used for the oral rehabilitation used computer-assisted design and computer-assisted manufacturing (CAD-CAM) titanium frameworks and cemented zirconia crowns. The titanium frameworks overcame suboptimal implant position and the cemented crowns provided excellent function and esthetics despite the locations of screw-access openings. No clinical complications occurred during a 13-month follow-up. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  8. Diabetic ketoacidosis complicating pregnancy.

    Science.gov (United States)

    Bryant, S N; Herrera, C L; Nelson, D B; Cunningham, F G

    2017-01-01

    Although diabetic ketoacidosis (DKA) in pregnancy can result in significant adverse consequences for both mother and fetus, the response to treatment, time course of recovery, and perinatal outcomes have not been well studied in pregnancy. We examined the precipitating factors, laboratory abnormalities, treatment strategies, and clinical recovery in pregnancies complicated by DKA. This is a retrospective cohort study of pregnancies complicated by DKA between October 1999 and June 2015. The diagnosis was verified by hyperglycemia; anion gap >12 mEq/L, pH diabetes (67%), and almost all presented with nausea and vomiting (97%). Over half had poor compliance with prescribed insulin. The initial mean blood glucose was 380 mg/dL, within 6 hours, it was <200 mg/dL. By 12 hours, the acidosis had resolved in 90% of patients. Nausea and vomiting is a prominent presenting feature of DKA in pregnancy. With aggressive insulin and resuscitation, hyperglycemia and acidosis improve rapidly. With current treatment, good perinatal outcomes can be expected.

  9. In vitro microleakage of luting cements and crown foundation material.

    Science.gov (United States)

    Lindquist, T J; Connolly, J

    2001-03-01

    Microleakage is a concern for the long-term prognosis of a cemented crown and foundation. The aims of this investigation were, first, to evaluate microleakage of zinc phosphate cement and resin-reinforced glass ionomer cement under ideal (dry) versus contaminated (wet) conditions, and second, to compare 3 foundations under both ideal and contaminated conditions. One hundred forty extracted molar teeth were cleaned and mounted. Tooth preparations for complete veneer cast crowns were completed with a chamfer finish line. A mesial surface class II cavity preparation 4 mm wide buccolingually and 2 mm deep was made in each tooth. Seven restorative groups were formed: amalgam/cavity varnish, amalgam/dentinal bonding agent, and composite/dentinal bonding agent, each with dry and contaminated groups, and a seventh group of class II cavity preparations without foundations. Finish lines for crown margins were refined 1.5 mm gingival to the restoration. Artificial crowns were cast in type III gold. Treatment groups were divided into 4 cement groups: dry and contaminated zinc phosphate cement and dry and contaminated resin-reinforced glass ionomer cement. The specimens were thermocycled and immersed in erythrosine B solution for 24 hours. Subsequently, they were rinsed, and their coronal portions were embedded in clear resin. Teeth were sectioned mesiodistally, and standard photomicrographs were made. The microleakage of each restoration and crown was measured. The least foundation microleakage was recorded for amalgam/dentinal bonding agents (ideal group) and composite/dentinal bonding agents (ideal group). The most microleakage was observed within the group without a foundation. In cement groups, the control and experiment sides were evaluated separately but displayed the same order of finding. The least leakage was recorded with resin-reinforced glass ionomer cement (ideal group); the most microleakage was noted with zinc phosphate cement (ideal group). An interaction was

  10. Retention of metal-ceramic crowns with contemporary dental cements.

    Science.gov (United States)

    Johnson, Glen H; Lepe, Xavier; Zhang, Hai; Wataha, John C

    2009-09-01

    New types of crown and bridge cement are in use by practitioners, and independent studies are needed to assess their effectiveness. The authors conducted a study in three parts (study A, study B, and study C) and to determine how well these new cements retain metal-ceramic crowns. The authors prepared teeth with a 20-degree taper and a 4-millimeter length. They cast high-noble metal-ceramic copings, then fitted and cemented them with a force of 196 newtons. The types of cements they used were zinc phosphate, resin-modified glass ionomer, conventional resin and self-adhesive modified resin. They thermally cycled the cemented copings, then removed them. They recorded the removal force and calculated the stress of dislodgment by using the surface area of each preparation. They used a single-factor analysis of variance to analyze the data (alpha = .05). The mean stresses necessary to remove crowns, in megapascals, were 8.0 for RelyX Luting (3M ESPE, St. Paul, Minn.), 7.3 for RelyX Unicem (3M ESPE), 5.7 for Panavia F (Kuraray America, New York) and 4.0 for Fuji Plus (GC America, Alsip, Ill.) in study A; 8.1 for RelyX Luting, 2.6 for RelyX Luting Plus (3M ESPE) and 2.8 for Fuji CEM (GC America) in study B; and 4.9 for Maxcem (Kerr, Orange, Calif.), 4.0 for BisCem (Bisco, Schaumburg, Ill.), 3.7 for RelyX Unicem Clicker (3M ESPE), 2.9 for iCEM (Heraeus Kulzer, Armonk, N.Y.) and 2.3 for Fleck's Zinc Cement (Keystone Industries, Cherry Hill, N.J.) in study C. Powder-liquid versions of new cements were significantly more retentive than were paste-paste versions of the same cements. The mean value of crown removal stress for the new self-adhesive modified-resin cements varied appreciably among the four cements tested. All cements retained castings as well as or better than did zinc phosphate cement. Powder-liquid versions of cements, although less convenient to mix, may be a better clinical choice when crown retention is an issue. All cements tested will retain castings

  11. Case report: management of crown-root fracture in lower first primary molar caused by injury to the chin: report of an unusual case.

    Science.gov (United States)

    Hariharan, V S; Rayen, R

    2012-08-01

    Dental traumas are highly prevalent lesions in primary teeth, but crown-root fractures are seldom observed in primary molars. When trauma is sustained to the chin, the posterior primary teeth are at increased risk of trauma. The treatment of fractured teeth can be complicated, sometimes because of difficulties with the final restoration. A 4-year-old girl was referred to a Specialty Dental clinic by a general dental practitioner with complaints of pain in her left mandibular posterior teeth region while biting. History revealed that she had fallen ten days before while playing. Chin laceration was sutured in the trauma centre, but no dental treatment was carried out. She was subsequently discharged. Later, she had pain while biting for which she was referred to the clinic by her general dental practitioner. Extra-oral examination demonstrated a healing laceration on the chin. Radiographic examination showed the presence of an unusual complicated crown-root fracture of the left mandibular first primary molar. Pulpectomy was carried out and the fracture was stabilised with glass ionomer cement and a preformed metal crown was placed. Patient was reviewed after 3, 6 and 12 months both radiographically and clinically. Though radiographically it was found that the obturating material was resorbed completely at the 12 month visit, clinically the patient was asymptomatic until now (after 15 months). The patient is still under review. This case highlights the need for a systematic history and examination in all cases of dental trauma. It also demonstrates that conservative management is possible and not all primary teeth with crown-root fractures need to be extracted.

  12. Readmissions Complications and Deaths - Hospital

    Data.gov (United States)

    U.S. Department of Health & Human Services — Readmissions, Complications and Deaths - provider data. This data set includes provider data for 30-day death and readmission measures, the hip/knee complication...

  13. Influence of implant position on clinical crown length and peri-implant soft tissue dimensions at implant-supported single crowns replacing maxillary central incisors

    DEFF Research Database (Denmark)

    Peng, Min; Fei, Wei; Hosseini, Mandana

    2013-01-01

    The aims of the present study were to evaluate the influence of implant position on clinical crown length and marginal soft tissue dimensions at implant-supported single crowns of maxillary central incisors, and to validate the papilla index score (PIS). Twenty-five patients, who had lost one...... as controls. Paired sample t-testand Pearson´s correlation analysis were used to analyze implant position, dimension of crownand papilla fill.Cohen’s ¿ andSpearman correlation were used to validate the PIS.The implant-supported crown was statistically longer than the contra-lateral tooth......, and there was significant correlation between the oro-facial position of the implant and the crown length difference (r=.607, p=.001). The distalpapilla was significantly shorter than the mesialpapilla at implant-supported crowns (ptooth (p=.415...

  14. Simulation of clinical fractures for three different all-ceramic crowns

    Science.gov (United States)

    Øilo, Marit; Kvam, Ketil; Gjerdet, Nils R

    2014-01-01

    Comparison of fracture strength and fracture modes of different all-ceramic crown systems is not straightforward. Established methods for reliable testing of all-ceramic crowns are not currently available. Published in-vitro tests rarely simulate clinical failure modes and are therefore unsuited to distinguish between the materials. The in-vivo trials usually lack assessment of failure modes. Fractographic analyses show that clinical crowns usually fail from cracks initiating in the cervical margins, whereas in-vitro specimens fail from contact damage at the occlusal loading point. The aim of this study was to compare three all-ceramic systems using a clinically relevant test method that is able to simulate clinical failure modes. Ten incisor crowns of three types of all-ceramic systems were exposed to soft loading until fracture. The initiation and propagation of cracks in these crowns were compared with those of a reference group of crowns that failed during clinical use. All crowns fractured in a manner similar to fracture of the clinical reference crowns. The zirconia crowns fractured at statistically significantly higher loads than alumina and glass-ceramic crowns. Fracture initiation was in the core material, cervically in the approximal areas. PMID:24698209

  15. Shear bond strength of self-ligating orthodontic brackets on different types of porcelain crowns

    Directory of Open Access Journals (Sweden)

    Karamdeep Singh Ahluwalia

    2013-01-01

    Full Text Available Aim: The aim of this study is to compare shear bond strength (SBS and adhesive remnant index (ARI of self-ligating orthodontic brackets bonded to different porcelain crowns. Materials and Methods: Three groups of different types of porcelain crowns, each containing 12 crowns were fabricated by the same technician and allocated to one of the study groups as follows: Group I - IPS porcelain crowns (Ivoclar Vivadent AG, Schaan, Liechtenstein, Group II - Porcelain fused to zirconia crowns (Zirkonzahn GmbH, Gais, Italy, Noritake Co., Tokyo, Japan and Group III - Conventional porcelain fused to metal crowns (Ceramco3, Densply, PA, USA. The orthodontic brackets were bonded to these crowns using hydrofluoric acid (HFA + silane etching protocol. After bonding, the SBS of the brackets were tested with a universal testing machine under standard test conditions. Results: Statistical evaluation using analysis of variance showed a significant difference between the groups (P 0.05. Chi-square comparison revealed no significant difference in ARI scores between groups (P > 0.05. Conclusions: When HFA + silane etching protocol were used, IPS crowns showed the greatest SBS of orthodontic brackets. The ARI score was non-significant. Therefore, if there is a need to place crowns over teeth then these crowns can be used for restoration of teeth before orthodontic treatment.

  16. Strength of CAD/CAM-generated esthetic ceramic molar implant crowns.

    Science.gov (United States)

    Wolf, Daniel; Bindl, Andreas; Schmidlin, Patrick R; Lüthy, Heinz; Mörmann, Werner H

    2008-01-01

    One-visit in-office CAD/CAM fabrication of esthetic ceramic crowns as a superstructure for posterior implants is quite new. The aim of the study was to evaluate the strength of esthetic ceramic CAD/CAM crowns with varied occlusal thickness and seated with adhesive and nonadhesive cements on titanium and zirconia abutments. Esthetic ceramic CAD/CAM-generated molar crowns (n = 15 per group) with occlusal thicknesses of 0.5 mm and 1.5 mm were seated on titanium (1) and zirconia (2) abutments: noncemented (a) and with nonadhesive cement (b) or 2 adhesive resin-based cements (c) and (d). In addition, 15 molar crowns with 5.5-mm occlusal thickness were seated on short zirconia abutments (3) using cements (c) and (d). All crowns had the identical occlusal morphology and were loaded with a crosshead speed of 0.5 mm/min until fracture. Load data were analyzed using 2-way ANOVA, the Scheffé test, and Weibull probability of failure analysis. Fracture loads of 1.5-mm occlusal thickness crowns (a, b, c, d) were higher (P crowns (except for group ld). Occlusal 5.5-mm crowns on short zirconia abutments had similar (2c) or less (2d) strength than the respective 1.5-mm crowns. Nonadhesive crowns (1b, 2b) were weaker (P crowns (1c, 1d, 2c, 2d). Fracture loads of 0.5- and 1.5-mm crowns were significantly higher on titanium than on zirconia abutments with both cements. Adhesive cement d generally showed higher fracture loads than c on both titanium and zirconia. Esthetic ceramic CAD/CAM molar implant crowns gained high strength with adhesive cements on both titanium and zirconia implant abutments compared to nonadhesive cementation.

  17. Evaluation of marginal circumference and marginal thickness changes in precrimped stainless steel crowns, after recrimping

    Directory of Open Access Journals (Sweden)

    Afshar H

    2006-07-01

    Full Text Available Background and Aim: The need for recrimping precrimped stainless steel crowns by the dentist in clinic is controversial. This study aimed to evaluate the rate of marginal circumference and marginal thickness change of precrimped stainless steel crowns after recrimping. Materials and Methods: In this experimental study, 30 primary photos were taken from margins of 30 S.S.Cs (3M, Ni-Cr related to tooth 85 with a digital camera fixed at a determined distance. Margins of crowns were crimped by 114 and 137 pliers with a controlled force (0.2 N and then 30 secondary photos were taken in the same conditions. The circumference of crown margins in primary (group A and secondary (group B photos were assessed by a digitizer system. Comparing the circumferences of crown margins in primary and secondary photos showed a significant decrease after crimping. Thickness of 30 random points on the crown margins of a crown similar to mentioned cases was measured by SEM (×150. Then similar procedures including taking a primary photo, crimping and taking a secondary photo was done for the sample crown. After significant reduction in margin circumference, thickness of 30 other random points on the crown margin were measured by SEM. Data were analyzed by paired sample t-test with p<0.05 as the limit of significance. Results: The mean marginal circumference of precrimped stainless steel crowns was reduced by 7.3% which was significant (P<0.001. On the other hand the mean marginal thickness of sample stainless steel crown showed 18µ increase. Conclusion: According to the results of this study, marginal circumference of precrimped stainless steel crowns (3M, Ni-Cr showed a significant decrease after crimping. It is concluded that crimping the stainless steel crowns even for precrimped ones seems necessary.

  18. Hip complications following chemoradiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, P.J.; Sebag Montefiore, D.J.; Arnott, S.J. [Saint Bartholomew`s Hospital, London (United Kingdom)

    1995-12-01

    Chemoradiotherapy protocols are a recent development in the management of tumours where preservation of organ function is important. It is now recognized that such combined treatment may produce adverse effects below the accepted dose thresholds for either modality. This enhancement of toxicity is generally thought to reflect depletion of stem cells within the tissue concerned. We report four patients who have developed avascular necrosis or fractures of the hip following chemoradiotherapy for carcinoma of the vulva or anus. These complications developed after a radiation dose of 4500 cGy in 20 fractions. The possible role of cytotoxic agents in sensitizing bone to radiation damage is discussed, and a novel mechanism is proposed to account for this phenomenon. (author).

  19. Hip complications following chemoradiotherapy

    International Nuclear Information System (INIS)

    Jenkins, P.J.; Sebag Montefiore, D.J.; Arnott, S.J.

    1995-01-01

    Chemoradiotherapy protocols are a recent development in the management of tumours where preservation of organ function is important. It is now recognized that such combined treatment may produce adverse effects below the accepted dose thresholds for either modality. This enhancement of toxicity is generally thought to reflect depletion of stem cells within the tissue concerned. We report four patients who have developed avascular necrosis or fractures of the hip following chemoradiotherapy for carcinoma of the vulva or anus. These complications developed after a radiation dose of 4500 cGy in 20 fractions. The possible role of cytotoxic agents in sensitizing bone to radiation damage is discussed, and a novel mechanism is proposed to account for this phenomenon. (author)

  20. [Complications of peripheral regional anesthesia].

    Science.gov (United States)

    Neuburger, M; Büttner, J

    2011-11-01

    Peripheral regional anesthesia is a commonly used and safe procedure and eneral complications or side effects are generally rare. Nerve damage has an incidence allergies, dislocation of catheters and knotting or loops in catheters. Besides the general complications, there are some specific complications depending on the puncture site, such as pneumothorax or renal puncture.

  1. with pulmonary Complications

    Directory of Open Access Journals (Sweden)

    Majid Mirsadraee

    2013-05-01

    Full Text Available   Introduction: Data on imaging findings in pulmonary complications of chemical agents is scarce. The current study aimed to evaluate radiological findings of late onset pulmonary complications in chemical warfare victims (CWV and to guide pulmonologists in diagnosis of these subjects.   Materials and Methods: Ninety- three male CWV were enrolled in this prospective study, 20-25 years (mean=23 after exposure. Demographic and clinical data were recorded. High resolution computed Tomography (HRCT of the lung was performed during inspiration and expiration and was double reported blindly by two radiologists. Final diagnosis was made according to HRCT findings. The HRCT findings, final diagnosis, and distribution of the abnormalities were compared between subjects whom had been exposed to more complex chemical agents used during the second half of the war and simpler agents during the first half. Results: The most frequent HRCT findings were air trapping (56.7% and mosaic attenuation (35.1%. The distribution of abnormalities was mostly local (79.4% and bilateral (73% especially in lower regions (61.3%. The diagnosed respiratory diseases included bronchiolitis obliterans (43%, chronic obstructive pulmonary disease (COPD (27.9%, asthma (23.6%, bronchiectasis (13.9% and interstitial lung disease (ILD (9.6%. Frequency of subjects involved in the second half of the period of war was more than the first period (P-value < 0.05 but the HRCT findings were similar. Conclusions: Bronchiolitis obliterans with picture of focal bilateral air trapping was the most common finding in CWV but asthma appeared to have become a new problem in these subjects.

  2. Neurologic complications of bariatric surgery.

    Science.gov (United States)

    Kumar, Neeraj

    2014-06-01

    The increasing utilization of bariatric surgery has been accompanied by an increased incidence and awareness of related neurologic complications. The purpose of this review is to provide up-to-date information on the neurologic complications related to bariatric surgery. Neurologic complications related to bariatric surgery are predominantly due to nutrient deficiencies. Common early complications include Wernicke encephalopathy due to thiamine deficiency, and late complications include myelopathy or myeloneuropathy due to vitamin B12 or copper deficiency. Early recognition and prompt institution of treatment is essential to prevent long-term disability. Often, life-long supplementation may be required.

  3. Fracture Resistance of Monolithic High Translucency Zirconia Implant-Supported Crowns.

    Science.gov (United States)

    Brizuela-Velasco, Aritza; Diéguez-Pereira, Markel; Álvarez-Arenal, Ángel; Chávarri-Prado, David; Solaberrieta, Eneko; Fernández-González, Felipe J; Chento-Valiente, Yelko; Santamaría-Arrieta, Gorka

    2016-10-01

    To evaluate the resistance to axial forces of screw-retained monolithic high translucency zirconia (mHTZr) crowns compared with high translucency zirconia + feldspathic ceramic (HTZrC) crowns, low translucency zirconia + feldspathic ceramic (LTZrC) crowns, and metal-ceramic (MC) crowns, and also to observe the different fracture patterns between all groups. Twenty-four crowns were fabricated (6 of each group) and loaded until failure, using a testing machine with a 5.0-kN load cell. Mean fracture results varied between 1092.7 N (LTZrC group) and 3439.7 N (mHTZr group). No statistically significant differences were found between the HTZrC, LTZrC, and MC groups. However, statistically significant differences (P zirconia implant-supported crowns proved to be the toughest group studied when an axial force was applied. Fracture patterns varied between different materials, chipping being the most common occurrence.

  4. [Clinical evaluation of the zirconia all ceramic crowns in 40 consecutive patients].

    Science.gov (United States)

    Qi, Bing; He, Yan

    2016-06-01

    To investigate clinical application, aesthetics, stability and bio-compatibility of zirconia all-ceramic crowns in prosthodontic patients. Computer aided design and manufacturing techniques were used to make zirconia all ceramic crowns in 40 patients. They were divided into 2 groups according to the thickness of the gingival thickness. After 12 months of clinical observation, the aesthetics, stability, and bio-compatibility were evaluated by the crown color, crown edge fitness, losing ratio and gingival health. The data were analyzed using SPSS 13.0 software package. Slight marginal discrepancy was observed in 2 zirconia all ceramic crowns, no evidence of decay was observed at 1 year. Zirconia all ceramic crowns have a low fracture rate, good biological properties and excellent esthetic properties. It is ideal esthetic prosthesis.

  5. Holographic evaluation of the marginal fits of complete crowns loaded at the central fossa

    Science.gov (United States)

    Chen, Terry Y.; Chang, Guan L.; Wu, Shih H.

    1995-05-01

    In dentistry, a defect of cementation on the margins of crowns accumulates bacterial plaque easily. This can result in recurrent caries and periodontal disease. In this paper holographic interferometry was applied to evaluate the effect of masticatory force on various complete crowns. Four complete molar crowns made from different materials (Au alloy, Pd-Ag alloy, Ni-Cr alloy, and porcelain fused to metal) were tested. The out-of-plane displacements of the crown specimens were measured by the method of multiple observations. The displacements measured range from 6 to 10 micrometers under normal load (25 N). However, the marginal openings of all four crowns were estimated to be less than 0.2 micrometers . In addition the defect of the crown was examined.

  6. Holographic evaluation of the marginal fit of complete crowns loaded at central fossa

    Science.gov (United States)

    Chen, Terry Y.; Chang, Guan L.; Wu, Shih H.

    1993-07-01

    In dentistry, the defect of cementation on the margins of crowns accumulates bacterial plaque easily. This can result in recurrent caries and periodontal disease. In this paper holographic interferometry is applied to study the effect of masticatory force on various complete crowns. Four complete molar crowns made from different casting materials (Au, Pd-Ag, Ni-Cr, and PFM) were tested. The horizontal displacements of two points near the margin, measured by the method of multiple observations, could be as large as 15 micrometers under normal load (25 kgw). However, the marginal discrepancy of all four crowns estimated were quite small (cementation between the crown and the tooth is quite good. Nevertheless, when the load was increased to 45 kgw, a defect of cementation was found on the Pd-Ag crown.

  7. MOLECULAR CLIPS BASED ON THE CROWN ETHERS: PROSPECTIVE RECEPTORS FOR THE Sr2+CATIONS REMOVAL

    Directory of Open Access Journals (Sweden)

    A. Yu. Lyapunov

    2015-04-01

    Full Text Available Strontium cation complexation with diphenylglycoluril-based molecular clips containing 12-crown-4, 15-crown-5, 18-crown-6 and 21-crown-7 residues was qualitatively studied by FAB mass-spectrometry. It was found that at low concentrations of Sr2+ cations molecular clip with fragments of 15-crown-5 is the most effective, and it is assumed that it is due to the formation of the most stable «sandwich-type» complex. The higher removal degree with an excess of Sr2+ cations is observed in the case of molecular clips with fragments of 18-crown-6 due to the formation of 1:2 composition complexes.

  8. Fracture Resistance of Non-Metallic Molar Crowns Manufactured with CEREC 3D

    Science.gov (United States)

    Madani, Dalia A.

    Objectives. To compare fracture strength and fatigue resistance of ceramic (ProCAD, Ivoclar-Vivadent) (C) and resin composite (Paradigm MZ100, 3M/ ESPE) (R) crowns made with CEREC-3D. Methods. A prepared ivorine molar tooth was duplicated to produce 40 identical prepared specimens made of epoxy resin (Viade). Twenty (C) crowns and 20 (R) were cemented to their dies using resin cement. Ten of each group were subjected to compressive loading to fracture. The remaining 10 of each group were subjected to mechanical cyclic loading for 500,000 cycles. The survivors were subjected to compressive loading to fracture. Results. No significant difference in mean fracture load was found between the two materials. However, only 30% of the (C) crowns vs. 100% of the (R) crowns survived the cyclic loading test. Conclusions. (R) crowns demonstrated higher fatigue Resistance than (C) crowns in-vitro and might better resist cracking in-vivo.

  9. Bis(hydroxyammonium hexachloridoplatinate(IV–18-crown-6 (1/2

    Directory of Open Access Journals (Sweden)

    Evgeny Bulatov

    2014-01-01

    Full Text Available In the title complex, (NH3OH2[PtCl6]·2C12H24O6, the PtIV atom is coordinated by six chloride anions in a slightly distorted octahedral geometry. The Pt—Cl bond lengths are comparable to those reported for other hexachloridoplatinate(IV species. The hydroxyammonium groups act as linkers between the [PtCl6]2− anion and the crown ether molecules. The anion is linked to two hydroxyammonium cations via O—H...Cl hydrogen bonds and each hydroxyammonium moiety is linked to a crown ether molecule by hydrogen bonds between ammonium H atoms and 18-crown-6 O atoms. The crown ether molecules have the classic crown shape in which all O atoms are located in the inner part of the crown ether ring and all –CH2– groups are turned to the outside.

  10. [Complications of induced abortions].

    Science.gov (United States)

    Duprez, D; Fortuna, P

    1989-02-01

    All physicians should be aware of the possible complications of induced abortions if only because the procedure is so commonplace. Some 250,000 induced abortions occur annually in France, amounting to 24.4 abortions per 100 live births. The rates of different complications of induced abortions before 12 weeks are .5-5/1000 for uterine perforation, .5-3.4% for hemorrhage with or without placental retention, 1% for endometritis, .3% for salpingitis .5% for continuing pregnancy, and .006 to .3/10,000 for death. A well done curettage is preferable to a poorly performed aspiration procedure. If an aspiration is done, the practitioner should bear in mind that retention of 50-200 cc of blood clots may occur if dilatation is insufficient. Symptoms appear 1-5 days after the abortion and end with expulsion of the clots or aspiration. Curettage is useless, as the clots do not represent a true retention. Uterine contractions during the aspiration can occasionally prompt a premature decision that evacuation is complete. Retention is difficult to diagnose immediately after aspiration but can be sonographically confirmed after the 8th day. Aspiration should be done after the 6th week and before the 12th week. Aspiration before the 6th week is often painful and is associated with higher rates of partial retention and of complete failure. Endouterine aspiration, regardless of technical proficiency, establishes a pathway between the vagina and the uterine cavity, which exposes the latter to the risk of trauma, endometrial lesions, and perforation. Induced abortion promotes infection by 2 mechanisms. Latent infections that were not detected in the medical history or physical examination can emerge and cause endometritis, which should be treated by ice, rest, and antibiotics. Or contamination of the passage by an infected cervical mucus can lead to salpingitis, abscess, and pelviperitonitis, or even general peritonitis. More often, these conditions develop from inadequately treated

  11. Unicuspid and bicuspid tooth crown formation in squamates.

    Science.gov (United States)

    Handrigan, Gregory R; Richman, Joy M

    2011-12-15

    The molecular and developmental factors that regulate tooth morphogenesis in nonmammalian species, such as snakes and lizards, have received relatively little attention compared to mammals. Here we describe the development of unicuspid and bicuspid teeth in squamate species. The simple, cone-shaped tooth crown of the bearded dragon and ball python is established at cap stage and fixed in shape by the differentiation of cells and the secretion of dental matrices. Enamel production, as demonstrated by amelogenin expression, occurs relatively earlier in squamate teeth than in mouse molars. We suggest that the early differentiation in squamate unicuspid teeth at cap stage correlates with a more rudimentary tooth crown shape. The leopard gecko can form a bicuspid tooth crown despite the early onset of differentiation. Cusp formation in the gecko does not occur by the folding of the inner enamel epithelium, as in the mouse molar, but by the differential secretion of enamel. Ameloblasts forming the enamel epithelial bulge, a central swelling of cells in the inner enamel epithelium, secrete amelogenin at cap stage, but cease to do so by bell stage. Meanwhile, other ameloblasts in the inner enamel epithelium continue to secrete enamel, forming cusp tips on either side of the bulge. Bulge cells specifically express the gene Bmp2, which we suggest serves as a pro-differentiation signal for cells of the gecko enamel organ. In this regard, the enamel epithelial bulge of the gecko may be more functionally analogous to the secondary enamel knot of mammals than the primary enamel knot. Copyright © 2011 Wiley Periodicals, Inc., A Wiley Company.

  12. Crown retention and flexural strength of eight provisional cements.

    Science.gov (United States)

    Lawson, Nathaniel C; Burgess, John O; Mercante, Donald

    2007-12-01

    Few studies have compared the retention of resin-based and zinc-oxide noneugenol provisional cements. Crown retention testing is difficult and variable; therefore, a simpler method of testing by using flexural strength is indicated. The purpose of this study was to measure the retention of base metal alloy castings to dentin provided by 8 provisional cements (3 resin-based and 5 zinc oxide) and correlate the retention to their flexural strength. Flexural strength specimens (2.5 x 2.5 x 22 mm) were made of each cement. The specimens were placed in a 3-point bending testing mode and loaded at 1 mm/min until failure. Ten extracted teeth were milled to a standardized complete crown preparation, fitted with Rexillium III castings, and cemented with each provisional cement. The specimens were subjected to a tensile load (1 mm/min) until failure in a universal testing machine. The flexural strength for each cement was calculated in MPa and correlated to the retention. A 1-way ANOVA and Tukey HSD post hoc analysis were used to determine significant intergroup differences (alpha=.05). Linear regression was used to correlate flexural strength and crown retention (alpha=.05). Significant differences were found in the flexural strengths and retention provided by the various cements. Flexure strength was correlated with cement retention for resin-based cements (r=0.998) but not zinc-oxide noneugenol cements (r=0.058). Based on a 20-degree preparation, stronger cements provide increased retention. Therefore, the desired amount of retention should be based on both the cement and a clinical evaluation of the preparation.

  13. Crown dimensions and proximal enamel thickness of mandibular second bicuspids

    Directory of Open Access Journals (Sweden)

    Sérgio Augusto Fernandes

    2011-08-01

    Full Text Available To achieve proper recontouring of anterior and posterior teeth, to obtain optimal morphology during enamel stripping, it is important to be aware of dental anatomy. This study aimed at evaluating crown dimensions and proximal enamel thickness in a sample of 40 extracted sound, human, mandibular, second bicuspids (20 right and 20 left. Mesiodistal, cervico-occlusal and buccolingual crown dimensions were measured using a digital caliper, accurate to 0.01 mm. Teeth were embedded in acrylic resin and cut along their long axes through the proximal surfaces to obtain 0.7 mm-thick central sections. Enamel thickness on the cut sections was measured using a perfilometer. Comparative analyses were carried out using the Student's-t test (α= 5%. The mean mesiodistal crown widths for right and left teeth were 7.79 mm (± 0.47 and 7.70 mm (± 0.51, respectively. Mean cervico-occlusal heights ranged from 8.31 mm (± 0.75 on the right to 8.38 mm (± 0.85 on the left teeth. The mean values for the buccolingual dimension were 8.67 mm (± 0.70 on the right and 8.65 mm (± 0.54 on the left teeth. The mean enamel thickness on the mesial surfaces ranged from 1.35 mm (± 0.22 to 1.40 mm (± 0.17, on the left and right sides, respectively. On the distal surfaces, the corresponding values were 1.44 mm (± 0.21 and 1.46 mm (± 0.12. No significant differences were found between measurements for right and left teeth. However, enamel thickness was significantly greater on the distal surfaces, compared with the mesial surfaces.

  14. The Effect of Crown-to-Implant Ratio on the Clinical Performance of Extra-Short Locking-Taper Implants.

    Science.gov (United States)

    Mangano, Francesco; Frezzato, Irene; Frezzato, Alberto; Veronesi, Giovanni; Mortellaro, Carmen; Mangano, Carlo

    2016-05-01

    The aim of the present prospective 5-year study was to evaluate the influence of crown-to-implant ratio (C/I ratio) on the survival, peri-implant marginal bone loss, and complications of extra-short (6.5 mm) locking-taper implants placed in the posterior areas of the jaw. Over a 2-year period, all patients presenting with partial edentulism associated with vertical defects of the posterior alveolar ridges and sufficient bone volume to place extra-short (6.5 mm length × 5 mm diameter) implants were considered for inclusion in this study. Fifty-one patients (22 men, 29 women; aged between 40 and 75 years) were included in this study. Sixty-eight extra-short, locking-taper implants were placed to support 49 single crowns and 9 fixed partial dentures. The C/I ratio was implants and ≥2 for 17 implants. All patients underwent the 5-year clinical examination. Two implants failed. Failure proportion was 2% in the C/Ishort, locking-taper implants may be successfully used in the posterior areas of the jaw.

  15. Treatment of oblique crown fractures in maxillary premolars using adhesive tooth fragment reattachment: 19 years of follow up.

    Science.gov (United States)

    Ferraz, José Antonio Brufato; Pécora, Jesus Djalma; Saquy, Paulo Cesar; Sousa-Neto, Manoel Damião

    2011-12-01

    This report presents an oblique crown fracture in the maxillary right premolars of an adolescent because of fall, which was treated using adhesive tooth fragment reattachment. The impact of the mandible base to the floor caused minor fractures in multiple teeth, severe fracture of teeth 14 and 15, and condylar fractures. The fragments of teeth 43, 45, 46, and 16 were lost at the site of accident. The condylar fractures were managed with a non-surgical conservative approach combining mandibular immobilization and stabilization of temporomandibular joints with maxillomandibular fixation using acrylic splints. After 3 months, the interocclusal splints were removed, and the patient was referred for dental care. Teeth 14 and 15 presented complicated oblique crown fractures causing separation of the buccal and palatal fragments, which were in place, attached to the gingival tissue. Tooth 15 presented chronic hyperplastic pulpits. The fragments were banded for stabilization during the endodontic treatment, and the bands served as matrix for adhesive tooth fragment reattachment. The other fractured teeth received direct composite resin restorations. After 8 years, tooth 16 developed pulp necrosis and was treated endodontically and restored with composite resin. Clinical and radiographic examination 19 years after trauma showed a good adaptation of the tooth fragment/composite resin restoration, good periodontal health, no signs of root resorption, and intact lamina dura. © 2011 John Wiley & Sons A/S.

  16. DNA methylation mediated control of gene expression is critical for development of crown gall tumors.

    Directory of Open Access Journals (Sweden)

    Jochen Gohlke

    Full Text Available Crown gall tumors develop after integration of the T-DNA of virulent Agrobacterium tumefaciens strains into the plant genome. Expression of the T-DNA-encoded oncogenes triggers proliferation and differentiation of transformed plant cells. Crown gall development is known to be accompanied by global changes in transcription, metabolite levels, and physiological processes. High levels of abscisic acid (ABA in crown galls regulate expression of drought stress responsive genes and mediate drought stress acclimation, which is essential for wild-type-like tumor growth. An impact of epigenetic processes such as DNA methylation on crown gall development has been suggested; however, it has not yet been investigated comprehensively. In this study, the methylation pattern of Arabidopsis thaliana crown galls was analyzed on a genome-wide scale as well as at the single gene level. Bisulfite sequencing analysis revealed that the oncogenes Ipt, IaaH, and IaaM were unmethylated in crown galls. Nevertheless, the oncogenes were susceptible to siRNA-mediated methylation, which inhibited their expression and subsequently crown gall growth. Genome arrays, hybridized with methylated DNA obtained by immunoprecipitation, revealed a globally hypermethylated crown gall genome, while promoters were rather hypomethylated. Mutants with reduced non-CG methylation developed larger tumors than the wild-type controls, indicating that hypermethylation inhibits plant tumor growth. The differential methylation pattern of crown galls and the stem tissue from which they originate correlated with transcriptional changes. Genes known to be transcriptionally inhibited by ABA and methylated in crown galls became promoter methylated upon treatment of A. thaliana with ABA. This suggests that the high ABA levels in crown galls may mediate DNA methylation and regulate expression of genes involved in drought stress protection. In summary, our studies provide evidence that epigenetic processes

  17. Wear Behavior of Ceramic CAD/CAM Crowns and Natural Antagonists

    OpenAIRE

    Naumova, Ella A.; Schneider, Stephan; Arnold, Wolfgang H.; Piwowarczyk, Andree

    2017-01-01

    Objective: Evaluation of wear behavior of computer-aided design/computer-aided manufacturing (CAD/CAM) crowns from various restorative materials and natural antagonists. Method: Full CAD/CAM crowns fabricated with nanoceramic resin (Lava Ultimate (LU)), a glass ceramic in a resin interpenetrating matrix (Vita Enamic (VE)) and a lithium silicate reinforced ceramic enriched with zirconia (Vita Suprinity (VS)) were cemented on human molars. The crown and antagonists were subjected to simulated c...

  18. Clinical evaluations of cast gold alloy, machinable zirconia, and semiprecious alloy crowns: A multicenter study.

    Science.gov (United States)

    Park, Ji-Man; Hong, Yong-Shin; Park, Eun-Jin; Heo, Seong-Joo; Oh, Namsik

    2016-06-01

    Few studies have compared the marginal and internal fits of crowns fabricated from machinable palladium-silver-indium (Pd-Ag-In) semiprecious metal alloy. The purpose of this clinical study was to evaluate and compare the marginal and internal fits of machined Pd-Ag-In alloy, zirconia, and cast gold crowns. A prospective clinical trial was performed on 35 participants and 52 abutment teeth at 2 centers. Individuals requiring prosthetic restorations were treated with gold alloy or zirconia crowns (2 control groups) or Pd-Ag-In alloy crowns (experimental group). A replica technique was used to evaluate the marginal and internal fits. The buccolingual and mesiodistal cross-sections were measured, and a noninferiority comparison was conducted. The mean marginal gaps were 68.2 μm for the gold crowns, 75.4 μm for the zirconia crowns, and 76.9 μm for the Pd-Ag-In alloy crowns. In the 5 cross-sections other than the distal cross-section, the 2-sided 95% confidence limits for the differences between the Pd-Ag-In alloy crowns and the 2 control groups were not larger than the 25-μm noninferiority margin. The control groups displayed smaller internal gaps in the line angle and occlusal spaces compared with the Pd-Ag-In crown group. The marginal gaps of machinable Pd-Ag-In alloy crowns did not meet the noninferiority criterion in the distal margin compared with zirconia and gold alloy crowns. Nonetheless, all 3 crowns had clinically applicable precision. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  19. A Comparison of Marginal Fit Between Lithium-Disilicate Press and CAD Fabricated Crowns

    Science.gov (United States)

    2014-05-27

    KBC, Nicholls JI. Evaluation of the marginal fit of a zirconia ceramic computer-aided machined (CAM) crown system. J Prosthet Dent 2010;104:216-27. 7...Workshops _Abstract _Other 6. Title: "A comparison of marginal fit between lithium-disilicate press and CAD fabricated crowns " 7. Intended...thesis manuscript entitled: "A comparison of marginal fit between lithium-disilicate press and CAD fabricated crowns " Is appropriately acknowledged

  20. Fracture Strength of Aged Monolithic and Bilayer Zirconia-Based Crowns

    Directory of Open Access Journals (Sweden)

    Deborah Pacheco Lameira

    2015-01-01

    Full Text Available The purpose of this study was to evaluate the effect of design and surface finishing on fracture strength of yttria-tetragonal zirconia polycrystal (Y-TZP crowns in monolithic (1.5 mm thickness and bilayer (0.8 mm zirconia coping and 0.7 mm porcelain veneer configuration after artificial aging. Bovine incisors received crown preparation and Y-TZP crowns were manufactured using CAD/CAM technique, according to the following groups (n=10: Polished monolithic zirconia crowns (PM; Glazed monolithic zirconia crowns (GM; Bi-layer crowns (BL. Crowns were cemented with resin cement, submitted to artificial aging in a chewing simulator (2.5 million cycles/80 N/artificial saliva/37°C, and tested for fracture strength. Two remaining crowns referring to PM and GM groups were submitted to a chemical composition analysis to measure the level of yttrium after aging. One-way ANOVA and Tukey’s test (P=.05 indicated that monolithic zirconia crowns presented similar fracture strength (PM=3476.2 N ± 791.7; GM=3561.5 N ± 991.6, which was higher than bilayer crowns (2060.4 N ± 810.6. There was no difference in the yttrium content among the three surfaces evaluated in the monolithic crowns. Thus, monolithic zirconia crowns present higher fracture strength than bilayer veneered zirconia after artificial aging and surface finishing does not affect their fracture strength.

  1. Fracture Strength of Aged Monolithic and Bilayer Zirconia-Based Crowns

    Science.gov (United States)

    Lameira, Deborah Pacheco; Silva, Wilkens Aurélio Buarque e; Silva, Frederico Andrade e; De Souza, Grace M.

    2015-01-01

    The purpose of this study was to evaluate the effect of design and surface finishing on fracture strength of yttria-tetragonal zirconia polycrystal (Y-TZP) crowns in monolithic (1.5 mm thickness) and bilayer (0.8 mm zirconia coping and 0.7 mm porcelain veneer) configuration after artificial aging. Bovine incisors received crown preparation and Y-TZP crowns were manufactured using CAD/CAM technique, according to the following groups (n = 10): Polished monolithic zirconia crowns (PM); Glazed monolithic zirconia crowns (GM); Bi-layer crowns (BL). Crowns were cemented with resin cement, submitted to artificial aging in a chewing simulator (2.5 million cycles/80 N/artificial saliva/37°C), and tested for fracture strength. Two remaining crowns referring to PM and GM groups were submitted to a chemical composition analysis to measure the level of yttrium after aging. One-way ANOVA and Tukey's test (P = .05) indicated that monolithic zirconia crowns presented similar fracture strength (PM = 3476.2 N ± 791.7; GM = 3561.5 N ± 991.6), which was higher than bilayer crowns (2060.4 N ± 810.6). There was no difference in the yttrium content among the three surfaces evaluated in the monolithic crowns. Thus, monolithic zirconia crowns present higher fracture strength than bilayer veneered zirconia after artificial aging and surface finishing does not affect their fracture strength. PMID:26576423

  2. Effect of Different Luting Agents on the Retention of Lithium Disilicate Ceramic Crowns

    OpenAIRE

    Mobilio, Nicola; Fasiol, Alberto; Mollica, Francesco; Catapano, Santo

    2015-01-01

    No studies are available that evaluate the retention of disilicate crowns according to different cementation procedures. The purpose of this study was to measure the retention of lithium disilicate crowns cemented using two different cementation systems. Twenty extracted mandibular premolars were prepared. Anatomic crowns were waxed and hot pressed using lithium disilicate ceramic. Teeth were divided into two groups (n = 10): (1) self-curing luting composite and (2) glass-ionomer cement (GIC)...

  3. Fatigue resistance and microleakage of CAD/CAM ceramic and composite molar crowns.

    Science.gov (United States)

    Kassem, Amr S; Atta, Osama; El-Mowafy, Omar

    2012-01-01

    The aim of this study was to determine effect of compressive cyclic loading on fatigue resistance and microleakage of monolithic CAD/CAM molar ceramic and composite crowns. Thirty-two extracted molars were prepared to receive CEREC crowns according to manufacturer's guidelines using a special paralleling device (Parallel-A-Prep). Sixteen feldspathic ceramic crowns (VITABLOCS Mark II) (VMII) and 16 resin-composite crowns (Paradigm-MZ100 blocks) (PMZ) were milled using a CEREC-3D machine. Eight crowns of each group were cemented to their respective teeth using self-etching resin cement (Panavia-F-2.0) (PAN), and eight were cemented using self-adhesive resin cement (RelyX-Unicem-Clicker) (RXU). Following storage for 1 week in water, specimens were subjected to uniaxial compressive cyclic loading in an Instron testing machine at 12 Hz for 1,000,000 cycles. Load was applied at the central fossa, and the cycle range was 60-600 N. Specimens were then subjected to microleakage testing. Data were statistically analyzed using factorial ANOVA and Post Hoc (Tukey HSD) tests. All composite crowns survived compressive cyclic loading without fracture, while three ceramic crowns from the subgroup cemented with RXU developed surface cracks at the center of occlusal surfaces, extending laterally. Microleakage scores of ceramic crowns cemented with PAN were significantly lower than those of the other three subgroups (p crowns were more fatigue-resistant than VMII ceramic crowns. Cement type had a significant effect on fatigue resistance of the ceramic crowns but not the composite ones. Microleakage scores of ceramic crowns cemented with PAN were significantly lower than those of the other subgroups (p < 0.05). © 2011 by The American College of Prosthodontists.

  4. Biomechanical three-dimensional finite element analysis of monolithic zirconia crown with different cement type

    OpenAIRE

    Ha, Seung-Ryong

    2015-01-01

    PURPOSE The objective of this study was to evaluate the influence of various cement types on the stress distribution in monolithic zirconia crowns under maximum bite force using the finite element analysis. MATERIALS AND METHODS The models of the prepared #46 crown (deep chamfer margin) were scanned and solid models composed of the monolithic zirconia crown, cement layer, and prepared tooth were produced using the computer-aided design technology and were subsequently translated into 3-dimens...

  5. In Vitro Fit and Cementation Resistance of Provisional Crowns for Single Implant-Supported Restorations

    OpenAIRE

    Moris,Izabela Cristina Maurício; Oliveira,Juliana Elias de; Faria,Adriana Cláudia Lapria; Ribeiro,Ricardo Faria; Rodrigues,Renata Cristina Silveira

    2015-01-01

    Abstract: This study aimed to verify marginal fit and the effect of cement film thickness standardization on retention of provisional crowns made with prefabricated acrylic cylinders on abutments, using two temporary luting agents subjected or not to mechanical cycling. Provisional crowns were made from bis-acryl (Luxatemp Fluorescence) or methyl methacrylate (Duralay) resins on acrylic cylinders and marginal fit and cement film thickness were evaluated. For retention evaluation, crowns were ...

  6. Radiochemical determination of 210Pb using crown ether

    International Nuclear Information System (INIS)

    Vajda, N.; Bodizs, D.; Vodicska, M.

    1994-01-01

    Gamma spectrometric determination of 210 Pb following chemical separation has been performed very precisely and with high sensitivity, due to the low and constant self-absorption of the chemically pure sample. A simple and quick method for the chemical separation of lead using crown ether has been developed. Its four steps are described in detail. The new method was verified using phosphate ore and gypsum samples that were measured in an interlaboratory comparison and with a standard reference material. This method can also be used for self-absorption correction in direct gamma spectrometry of 210 Pb. (N.T.) 4 refs.; 2 figs.; 2 tabs

  7. Suppressing Nonradiative Recombination in Crown-Shaped Quantum Wells

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kwangwook [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Ju, Gunwu [Gwangju Institute of Science and Technology; Korea Institute of Science and Technology; Na, Byung Hoon [Samsung Advanced Institute of Technology; Hwang, Hyeong-Yong [Gwangju Institute of Science and Technology; Jho, Young-Dahl [Gwangju Institute of Science and Technology; Myoung, NoSoung [Gwangju Institute of Science and Technology; Yim, Sang-Youp [Gwangju Institute of Science and Technology; Kim, Hyung-jun [Korea Institute of Science and Technology; Lee, Yong Tak [Gwangju Institute of Science and Technology

    2018-02-06

    We examined the structural and optical properties of a crown-shaped quantum well (CSQW) to suppress nonradiative recombination. To reduce carrier loss in defect traps at the well/barrier interface, the CSQW was designed to concentrate carriers in the central region by tailoring the bandgap energy. Temperature-dependent photoluminescence measurements showed that the CSQW had a high activation energy and low potential fluctuation. In addition, the long carrier lifetime of the CSQW at high temperatures can be interpreted as indicating a decrease in carrier loss at defect traps.

  8. Provisional Crown Dislodgement during Scuba Diving: A Case of Barotrauma.

    Science.gov (United States)

    Gulve, Meenal Nitin; Gulve, Nitin Dilip

    2013-01-01

    Changes in ambient pressure, for example, during flying, diving, or hyperbaric oxygen therapy, can lead to barotrauma. Although it may seem that this issue was neglected in dental education and research in recent decades, familiarity with and understanding of these facts may be of importance for dental practitioners. We report the case of a patient who experienced barotrauma involving dislodgement of a provisional crown during scuba diving. Patients who are exposed to pressure changes as a part of their jobs or hobbies and their dentists should know the causes of barotrauma. In addition, the clinician must be aware of the possible influence of pressure changes on the retention of dental components.

  9. Stress distribution difference between Lava Ultimate full crowns and IPS e.max CAD full crowns on a natural tooth and on tooth-shaped implant abutments.

    Science.gov (United States)

    Krejci, Ivo; Daher, René

    2017-04-01

    The goal of this short communication is to present finite element analysis comparison of the stress distribution between CAD/CAM full crowns made of Lava Ultimate and of IPS e.max CAD, adhesively luted to natural teeth and to implant abutments with the shape of natural teeth. Six 3D models were prepared using a 3D content-creating software, based on a micro-CT scan of a human mandibular molar. The geometry of the full crown and of the abutment was the same for all models representing Lava Ultimate full crowns (L) and IPS e.max CAD full crowns (E) on three different abutments: prepared natural tooth (n), titanium abutment (t) and zirconia abutment (z). A static load of 400 N was applied on the vestibular and lingual cusps, and fixtures were applied to the base of the models. After running the static linear analysis, the post-processing data we analyzed. The stress values at the interface between the crown and the abutment of the Lt and Lz groups were significantly higher than the stress values at the same interface of all the other models. The high stress concentration in the adhesive at the interface between the crown and the abutment of the Lava Ultimate group on implants might be one of the factors contributing to the reported debondings of crowns.

  10. Postoperative pulmonary complications updating.

    Science.gov (United States)

    Langeron, O; Carreira, S; le Saché, F; Raux, M

    2014-01-01

    Postoperative pulmonary complications (PPCs) are a major contributor to the overall risk of surgery. PPCs affect the length of hospital stay and are associated with a higher in-hospital mortality. PPCs are even the leading cause of death either in cardiothoracic surgery but also in non-cardiothoracic surgery. Thus, reliable PPCs risk stratification tools are the key issue of clinical decision making in the perioperative period. When the risk is clearly identified related to the patient according the ARISCAT score and/or the type of surgery (mainly thoracic and abdominal), low-cost preemptive interventions improve outcomes and new strategies can be developed to prevent this risk. The EuSOS, PERISCOPE and IMPROVE studies demonstrated this care optimization by risk identification first, then risk stratification and new care (multifaceted) strategies implementation allowing a decrease in PPCs mortality by optimizing the clinical path of the patient and the care resources. Copyright © 2014 Société française d’anesthésie et de réanimation (Sfar). Published by Elsevier SAS. All rights reserved.

  11. Neuromuscular complications in cancer.

    Science.gov (United States)

    Grisold, W; Grisold, A; Löscher, W N

    2016-08-15

    Cancer is becoming a treatable and even often curable disease. The neuromuscular system can be affected by direct tumor invasion or metastasis, neuroendocrine, metabolic, dysimmune/inflammatory, infections and toxic as well as paraneoplastic conditions. Due to the nature of cancer treatment, which frequently is based on a DNA damaging mechanism, treatment related toxic side effects are frequent and the correct identification of the causative mechanism is necessary to initiate the proper treatment. The peripheral nervous system is conventionally divided into nerve roots, the proximal nerves and plexus, the peripheral nerves (mono- and polyneuropathies), the site of neuromuscular transmission and muscle. This review is based on the anatomic distribution of the peripheral nervous system, divided into cranial nerves (CN), motor neuron (MND), nerve roots, plexus, peripheral nerve, the neuromuscular junction and muscle. The various etiologies of neuromuscular complications - neoplastic, surgical and mechanic, toxic, metabolic, endocrine, and paraneoplastic/immune - are discussed separately for each part of the peripheral nervous system. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Renal complications of anaesthesia.

    Science.gov (United States)

    McKinlay, J; Tyson, E; Forni, L G

    2018-01-01

    Peri-operative acute kidney injury is common, accounting for 30-40% of all in-hospital cases of acute kidney injury. It is associated with clinically significant morbidity and mortality even with what was hitherto regarded as relatively trivial increases in serum creatinine, and carries over a 12-fold relative risk of death following major abdominal surgery. Comorbid conditions such as diabetes, hypertension, liver disease and particularly pre-existing chronic kidney disease, as well as the type and urgency of surgery, are major risk factors for the development of postoperative acute kidney injury. As yet, there are no specific treatment options for the injured kidney, although there are several modifiable risk factors of which the anaesthetist should be aware. As well as the avoidance of potential nephrotoxins and appropriate volume balance, optimal anaesthetic management should aim to reduce the risk of postoperative renal complications. This may include careful ventilatory management and blood pressure control, as well as appropriate analgesic strategies. The choice of anaesthetic agent may also influence renal outcomes. Rather than concentrate on the classical management of acute kidney injury, this review focuses on the potential development of acute kidney injury peri-operatively, and the means by which this may be ameliorated. © 2018 The Association of Anaesthetists of Great Britain and Ireland.

  13. Monolithic zirconia dental crowns. Internal fit, margin quality, fracture mode and load at fracture.

    Science.gov (United States)

    Schriwer, Christian; Skjold, Anneli; Gjerdet, Nils Roar; Øilo, Marit

    2017-09-01

    Dental all-ceramic restorations of zirconia, with and without an aesthetic veneering layer, have become a viable alternative to conventional metal-ceramic restorations. The aim of this study was to evaluate whether factors of the production methods or the material compositions affect load at fracture, fracture modes, internal fit or crown margins of monolithic zirconia crowns. Sixty crowns made from six different commercially available dental zirconias were produced to a model tooth with a shallow circumferential chamfer preparation. Internal fit was assessed by the replica method. The crown margin quality was assessed by light microscopy on an ordinal scale. The cemented crowns were loaded centrally in the occlusal fossa with a horizontal steel cylinder with a diameter of 13mm at 0.5mm/min until fracture. Fractographic analysis was performed on the fractured crowns. There were statistically significant differences among the groups regarding crown margins, internal fit and load at fracture (pFracture analyses revealed that all fractures started cervically and propagated to the occlusal surface similar to clinically observed fractures. There was statistically significant correlation between margin quality and load at fracture (Spearman's rank correlation, pfracture. The hard-machined Y-TZP zirconia crowns had the best margin quality and the highest load at fracture. Reduction of margin flaws will improve fracture strength of monolithic zirconia crowns and thereby increase clinical success. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. Radium separation through complexation by aqueous crown ethers and ion exchange or solvent extraction

    Energy Technology Data Exchange (ETDEWEB)

    Chiarizia, R.; Dietz, M.L.; Horwitz, E.P. [Argonne National Lab., IL (United States). Chemistry Div.; Burnett, W.C. [Florida State Univ., Tallahassee, FL (United States). Dept. of Oceanography

    1997-11-01

    The effect of three water-soluble, unsubstituted crown ethers (15-crown-5 (15C5), 18-crown-6 (18C6) and 21-crown-7 (21C7)) on the uptake of Ca, Sr, Ba and Ra cations by a sulfonic acid cation exchange resin, and on the extraction of the same cations by xylene solutions of dinonylnaphthalenesulfonic acid (HDNNS) from aqueous hydrochloric acid solutions has been investigated. The crown ethers enhance the sorption of the larger cations by the ion exchange resin, thereby improving the resin selectivity over calcium, a result of a synergistic interaction between the crown ether and the ionic functional groups of the resin. Similarly, the extraction of the larger alkaline earth cations into xylene by HDNNS is strongly synergized by the presence of the crown ethers in the aqueous phase. Promising results for intra-Group IIa cation separations have been obtained using each of the three crown ethers as the aqueous ligands and the sulfonic acid cation exchange resin. Even greater separation factors for the radium-calcium couple have been measured with the crown-ethers and HDNNS solutions in the solvent extraction mode. The application of the uptake and extraction results to the development of radium separation schemes is discussed and a possible flowchart for the determination of {sup 226}Ra/{sup 228}Ra in natural waters is presented.

  15. Wear Behavior of Ceramic CAD/CAM Crowns and Natural Antagonists

    Directory of Open Access Journals (Sweden)

    Ella A. Naumova

    2017-02-01

    Full Text Available Objective: Evaluation of wear behavior of computer-aided design/computer-aided manufacturing (CAD/CAM crowns from various restorative materials and natural antagonists. Method: Full CAD/CAM crowns fabricated with nanoceramic resin (Lava Ultimate (LU, a glass ceramic in a resin interpenetrating matrix (Vita Enamic (VE and a lithium silicate reinforced ceramic enriched with zirconia (Vita Suprinity (VS were cemented on human molars. The crown and antagonists were subjected to simulated chewing. 3D data sets, before and after the chewing simulation, were generated and matched. Occlusal surface roughness, vertical and volume loss of the crowns and antagonists were analyzed. Results: Crown roughness was significantly different between the LU and VE groups after chewing simulation. Crown vertical loss differed in all groups. The highest crown volume loss was found in the LU group, and the lowest in the VE group. Comparisons between the LU and VE groups and the LU and VS groups were significantly different. The highest antagonist volume loss was reached in the VE group, the lowest was in the LU group. Conclusion: Roughness increased after chewing simulation. LU crowns are the most natural antagonist-friendly; these were the most susceptible to vertical and volume loss. Of the tested materials, the VE crowns are the most stable regarding occlusion.

  16. Fracture Strength of Aged Monolithic and Bilayer Zirconia-Based Crowns

    OpenAIRE

    Lameira, Deborah Pacheco; Silva, Wilkens Aur?lio Buarque e; Silva, Frederico Andrade e; De Souza, Grace M.

    2015-01-01

    The purpose of this study was to evaluate the effect of design and surface finishing on fracture strength of yttria-tetragonal zirconia polycrystal (Y-TZP) crowns in monolithic (1.5 mm thickness) and bilayer (0.8 mm zirconia coping and 0.7 mm porcelain veneer) configuration after artificial aging. Bovine incisors received crown preparation and Y-TZP crowns were manufactured using CAD/CAM technique, according to the following groups (n = 10): Polished monolithic zirconia crowns (PM); Glazed mo...

  17. Measuring residual stress in ceramic zirconia-porcelain dental crowns by nanoindentation.

    Science.gov (United States)

    Zhang, Y; Allahkarami, M; Hanan, J C

    2012-02-01

    Residual stress plays a critical role in failure of ceramic dental crowns. The magnitude and distribution of residual stress in the crown system are largely unknown. Determining the residual stress quantitatively is challenging since the crown has such complex contours and shapes. This work explored the feasibility and validity of measuring residual stress of zirconia and porcelain in ceramic crowns by nanoindentation. Nanoindentation tests were performed on the cross-section of a crown for both porcelain and zirconia along four critical locations: the thickest, thinnest and medium porcelain thicknesses. Zirconia and porcelain pieces, chipped off from the crown and annealed at 400 °C, were used as reference samples. The residual stress was determined by comparing the measured hardness of the stressed sample with that of the reference sample. Nanoindentation impression images were acquired through a scanning probe microscope (SPM) equipped with a Hysitron Triboindenter. Zirconia showed large pile-up. Residual stress is determined along the thickness of crowns at the chosen locations for both porcelain and zirconia. The measured results were compared with the results from X-ray diffraction (XRD) and finite element modeling (FEM). Results show there are large amounts of residual stresses in the dental crown and their magnitude differs between locations due to the complex shape of the crown. The average residual stress readings were as high as -637 MPa and 323 MPa for zirconia and porcelain respectively. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. Finite element analysis of the influence of geometry and design of zirconia crowns on stress distribution.

    Science.gov (United States)

    Anami, Lilian Costa; Lima, Julia Magalhaes da Costa; Corazza, Pedro Henrique; Yamamoto, Eron Toshio Colauto; Bottino, Marco Antonio; Borges, Alexandre Luiz Souto

    2015-02-01

    To evaluate the influence of the geometry and design of prosthetic crown preparations on stress distribution in compression tests, using finite element analysis (FEA). Six combinations of 3D drawings of all-ceramic crowns (yttria-stabilized zirconia framework and porcelain veneer) were evaluated: F, flat preparation and simplified crown; FC, flat preparation and crown with contact point; FCM, flat preparation and modified crown; A, anatomical preparation and simplified anatomical crown framework; AC, anatomical preparation and crown with contact point; and ACM, anatomical preparation and modified crown. Bonded contact types at all interfaces with the mesh were assigned, and the material properties used were according to the literature. A 200 N vertical load was applied at the center of each model. The maximum principal stresses were quantitatively and qualitatively analyzed. The highest values of tensile stress were observed at the interface between the ceramics in the region under the load application for the simplified models (F and A). Reductions in stress values were observed for the model with the anatomical preparation and modified infrastructure (ACM). The stress distribution in the flat models was similar to that of their respective anatomical models. The modified design of the zirconia coping reduces the stress concentration at the interface with the veneer ceramic, and the simplified preparation can exert a stress distribution similar to that of the anatomical preparation at and near the load point, when load is applied to the center of the crown. © 2014 by the American College of Prosthodontists.

  19. 18-Crown[6]ether functionalized reduced graphene oxide for membrane-free ion selective sensing

    DEFF Research Database (Denmark)

    Olsen, Gunnar; Ulstrup, Jens; Chi, Qijin

    The focus of this work is on the synthesis of a 1-Aza-18-crown[6]ether functionalized reduced graphene oxide (RGO-crown[6]) with specific K+ binding sites on the RGO surface. Glassy carbon electrodes (GCE) functionalized with RGO-crown[6] weretested for selective potentiometric sensing of K......+ , with a detection limit of 10-5 M without inference from other ions (Na+ , Li+ , NH4+ and Ca2+) in concentrations up to 2.5 × 10-2 M. Similar sensing was achieved with functionalized disposable SPE electrodes. The results demonstrate that RGO-crown[6] is a conductive material full of promise for application...

  20. Extracting oil palm crown from WorldView-2 satellite image

    Science.gov (United States)

    Korom, A.; Phua, M.-H.; Hirata, Y.; Matsuura, T.

    2014-02-01

    Oil palm (OP) is the most commercial crop in Malaysia. Estimating the crowns is important for biomass estimation from high resolution satellite (HRS) image. This study examined extraction of individual OP crown from a WorldView-2 image using twofold algorithms, i.e., masking of Non-OP pixels and detection of individual OP crown based on the watershed segmentation of greyscale images. The study site was located in Beluran district, central Sabah, where matured OPs with the age ranging from 15 to 25 years old have been planted. We examined two compound vegetation indices of (NDVI+1)*DVI and NDII for masking non-OP crown areas. Using kappa statistics, an optimal threshold value was set with the highest accuracy at 90.6% for differentiating OP crown areas from Non-OP areas. After the watershed segmentation of OP crown areas with additional post-procedures, about 77% of individual OP crowns were successfully detected in comparison to the manual based delineation. Shape and location of each crown segment was then assessed based on a modified version of the goodness measures of Möller et al which was 0.3, indicating an acceptable CSGM (combined segmentation goodness measures) agreements between the automated and manually delineated crowns (perfect case is '1').

  1. Polyaza crown ether as non-nucleosidic building blocks in DNA-conjugates

    DEFF Research Database (Denmark)

    Jakobsen, Ulla; Rohr, Katja; Madsen, Rasmus K

    2007-01-01

    The synthesis of amphiphilic polyaza crown ether monomers X (palmityl-substituted), Y (cholesteryl-substituted) and Z (dipalmityl-subtituted) and their incorporation into oligonucleotides are described. Their effects on thermal duplex stability were investigated by UV melting curve analysis....... Thermal denaturation experiments showed remarkable stabilization of dsDNA by polyaza crown ether monomers when incorporated in opposite positions. The series of polyaza crown ether monomers (X, Y, and Z) with different lipophilicity showed a trend of increased stability of the corresponding ds......DNA with increasing lipophilicity of the polyaza crown ether monomer....

  2. QTL analysis of crown rust resistance in perennial ryegrass under conditions of natural and artificial infection

    DEFF Research Database (Denmark)

    Schejbel, Britt; Jensen, Louise Friis Bach; Xing, Yongzhong

    2007-01-01

    Crown rust is an economically devastating disease of perennial ryegrass. Both artificial crown rust inoculations, with the possibility of several selection cycles in one year, as well as marker-assisted selection can be used for more efficient breeding of new resistant cultivars. The objective...... of this study was to map quantitative trait loci (QTL) for response to crown rust infection in perennial ryegrass. In order to identify relevant markers for response to crown rust infection, QTL mapping was performed on a ryegrass mapping population which was evaluated for resistance in the field for two years...

  3. Extracting oil palm crown from WorldView-2 satellite image

    International Nuclear Information System (INIS)

    Korom, A; Phua, M-H; Hirata, Y; Matsuura, T

    2014-01-01

    Oil palm (OP) is the most commercial crop in Malaysia. Estimating the crowns is important for biomass estimation from high resolution satellite (HRS) image. This study examined extraction of individual OP crown from a WorldView-2 image using twofold algorithms, i.e., masking of Non-OP pixels and detection of individual OP crown based on the watershed segmentation of greyscale images. The study site was located in Beluran district, central Sabah, where matured OPs with the age ranging from 15 to 25 years old have been planted. We examined two compound vegetation indices of (NDVI+1)*DVI and NDII for masking non-OP crown areas. Using kappa statistics, an optimal threshold value was set with the highest accuracy at 90.6% for differentiating OP crown areas from Non-OP areas. After the watershed segmentation of OP crown areas with additional post-procedures, about 77% of individual OP crowns were successfully detected in comparison to the manual based delineation. Shape and location of each crown segment was then assessed based on a modified version of the goodness measures of Möller et al which was 0.3, indicating an acceptable CSGM (combined segmentation goodness measures) agreements between the automated and manually delineated crowns (perfect case is '1')

  4. Effect of misfit of cement-retained implant single crowns on crestal bone changes.

    Science.gov (United States)

    Chen, Chun-Jung; Papaspyridakos, Panos; Guze, Kevin; Singh, Medha; Weber, Hans-Peter; Gallucci, German O

    2013-01-01

    The purpose of this clinical study was to compare peri-implant crestal bone levels between misfitting (overhanging/open margin) cement-retained implant single crowns (SCs) vs accurately fitted implant SCs. Seventeen subjects were divided into two groups: test group (misfitting crowns, n = 10) and control group (accurately fitted crowns, n = 7). Crestal bone level changes were assessed using digital software. The average differences in mean bone loss within and between the two groups were statistically significant. Cement-retained implant SCs with marginal misfit resulted in more crestal bone loss than accurately fitted crowns after a mean of 3 years in function.

  5. Using an Existing Crown to Repair a Damaged Cast Post and Core Restoration

    OpenAIRE

    Arabolu, Manikya; Nair, K Chandrasekharan; Raheel, Syed Ahmed; Tarakji, Bassel; Azzeghaiby, Saleh Nasser; Nassani, Mohammad Zakaria

    2014-01-01

    A fractured coronal tooth structure beneath an intact crown is a common clinical occurrence. If the underlying root is healthy, the tooth is restored with a post and core followed by refabrication of the crown. This paper describes a technique of using the existing intact crown for the above-mentioned situation. A 34-year-old female was referred with a fractured right canine with an intact crown. A post was found fractured in the canal which was subsequently retrieved. A new fiber post was ce...

  6. Twenty-nine-month follow-up of a paediatric zirconia dental crown.

    Science.gov (United States)

    Lopez Cazaux, Serena; Hyon, Isabelle; Prud'homme, Tony; Dajean Trutaud, Sylvie

    2017-06-14

    The aim of this paper is to present the long-term follow-up of one paediatric zirconia crown on a deciduous molar. Preformed crowns are part of the armamentarium in paediatric dentistry. In recent years, aesthetic alternatives to preformed metal crowns have been developed, first preveneered crowns and then zirconia crowns. This paper describes the restoration of a primary molar with a zirconia crown (EZ-Pedo, Loomis, California, USA) in an 8-year-old boy. In this clinical case, the protocol for the implementation and maintenance of zirconia crowns is detailed. The patient was followed up for 29 months until the natural exfoliation of his primary molar. The adaptation of the zirconia crown, the gingival health and the wear on the opposing tooth were considered. In this case, the paediatric zirconia crown allowed sustainable functional restoration while restoring a natural appearance of the tooth. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  7. CAD/CAM glass ceramics for single-tooth implant crowns: a finite element analysis.

    Science.gov (United States)

    Akça, Kvanç; Cavusoglu, Yeliz; Sagirkaya, Elcin; Aybar, Buket; Cehreli, Murat Cavit

    2013-12-01

    To evaluate the load distribution of CAD/CAM mono-ceramic crowns supported with single-tooth implants in functional area. A 3-dimensional numerical model of a soft tissue-level implant was constructed with cement-retained abutment to support glass ceramic machinable crown. Implant-abutment complex and the retained crown were embedded in a Ø 1.5 × 1.5 cm geometric matrix for evaluation of mechanical behavior of mono-ceramic CAD/CAM aluminosilicate and leucite glass crown materials. Laterally positioned axial load of 300 N was applied on the crowns. Resulting principal stresses in the mono-ceramic crowns were evaluated in relation to different glass ceramic materials. The highest compressive stresses were observed at the cervical region of the buccal aspect of the crowns and were 89.98 and 89.99 MPa, for aluminosilicate and leucite glass ceramics, respectively. The highest tensile stresses were observed at the collar of the lingual part of the crowns and were 24.54 and 25.39 MPa, respectively. Stresses induced upon 300 N static loading of CAD/CAM aluminosalicate and leucite glass ceramics are below the compressive strength of the materials. Impact loads may actuate the progress to end failure of mono-ceramic crowns supported by metallic implant abutments.

  8. Considerations during crown reattachment procedure over the pulpal exposure: case report

    Directory of Open Access Journals (Sweden)

    Bona Kim

    2012-11-01

    Full Text Available Crown reattachment is the most conservative treatment which can be used to restore fractured tooth, presumably with sufficient strength, while maintaining original contour, incisal translucency, and reducing chair time and cost. However, in case of crown fracture with pin-point pulp exposure, we should cautiously minimize the irritation to the pulp and consider pre-treatment pulpal status, choice of pulp capping materials, choice of bonding system and treatment sequence during crown reattachment procedures. This case reports the considerations while crown reattachment with direct pulp capping using calcium hydroxide (Dycal, Dentsply Caulk.

  9. Chest complication after abdominal surgery

    International Nuclear Information System (INIS)

    Koh, B. H.; Choi, J. Y.; Hahm, C. K.; Kang, S. R.

    1981-01-01

    In spite of many advances in medicine, anesthetic technique and surgical managements, pulmonary problems are the most frequent postoperative complications, particularly after abdominal surgery. As postoperative pulmonary complications, atelectasis, pleural effusion, pneumonia, chronic bronchitis and lung abscess can be occurred. This study include evaluation of chest films of 2006 patients (927 male, 1079 female), who had been operated abdominal surgery from Jan. 1979 to June, 1980 in the Hanyang university hospital. The results were as follows: 1. 70 cases out of total 2006 cases (3.5%) developed postoperative chest complications, 51 cases (5.5%) in male, 19 cases (1.8%) in female. 2. The complication rate was increased according to the increase of age. The incidence of the postoperative complications over 40 years of age was higher than the overall average complications rate. 3. The most common postoperative pulmonary complication was pleural effusion, next pneumonia, atelectasis and pulmonary edema respectively. 4. The complication rate of the group of upper abdominal surgery is much higher than the group of lower abdominal surgery. 5. Complication rate was increased according to increase of the duration of operation. 6. There were significant correlations between the operation site and side of the complicated hemithorax

  10. Evaluation of zirconia-based posterior single crowns supported by zirconia implants: preliminary results of a prospective multicenter study.

    Science.gov (United States)

    Spies, Benedikt Christopher; Kohal, Ralf-Joachim; Balmer, Marc; Vach, Kirstin; Jung, Ronald E

    2017-05-01

    The aim of this uncontrolled prospective multicenter study was to determine the success and survival rate of posterior single crowns composed of zirconia frameworks hand-layered with a leucite-reinforced feldspathic ceramic supported by one-piece zirconia oral implants. In two centers, sixty patients received 71 zirconia oral implants. To obtain a clear indication of posterior implant-supported single crowns (ISSCs), 14 patients (25 implants) were excluded from the analysis (11 bridges, three anterior crowns). The remaining patients were provided with single implants in posterior regions. As one patient lost his implant and another refused further participation after final prosthesis insertion, 44 ISSCs/patients (19 females, 25 males) were available for evaluation. Of these patients, all were seen at prosthetic delivery and the 6- and 12-month follow-up appointments. Evaluations were performed using modified United States Public Health Service (USPHS) criteria. Restorations within Alpha and Bravo ratings were regarded as success. This included minor chippings, a slight roughness, slightly soundable restoration margins and minimal contour deficiencies. In case of more distinct defects that could, however, be repaired to a clinically acceptable level, restorations were regarded as surviving. Kaplan-Meier plots and log-rank tests were used for the success/survival analyses and the calculation of potential group differences (gender, jaw and center). After a mean observation period of 12.5 months (SD: 0.8 months), no ISSC had to be replaced, resulting in a Kaplan-Meier survival rate of 100%. The Kaplan-Meier success rate was 90.9% (one major chipping, one obvious roughness, one significant crevice and one pronounced over-contouring). Minor chippings and occlusal roughness were frequent complications. No significantly different survival/success rates could be observed between the mentioned groups. The frequent incidence of minor chippings suggests a high technique

  11. Complicity and torture.

    Science.gov (United States)

    Shue, Henry

    2017-04-01

    One of the great merits of On Complicity and Compromise is that it wades into specific swamps where ordinary theorists fear to slog. It is persuasive that in general it can be right sometimes to be complicit in wrongdoing by others through causally contributing to the wrongdoing, but not sharing its purpose, if by being involved one can reasonably expect to lessen the extent of the wrong that would otherwise be suffered by the victims. I focus on whether the book's general thesis is applicable to torture, which depends on what torture and the torture situation are in fact like. I focus on the case to which the chapter several times refers: the innovative CIA paradigm of torture. First, to the extent that the paradigm, which is predominantly mental, or psychological, torture succeeds in its goal of producing regression to a compliant state, the physician would be unable to rely on the torture victim's expressions of preferences or interests as authentically his own. Second, since disorientation plays such a large role in the CIA's style of torture (adopted at Guantanamo by the military), the authorities would refuse to allow a stable relationship to be built up with any one doctor by any victim, making comprehension of the victim's preferences difficult. Third, even if the doctor could somehow judge what the victim's genuine interests were, the control of the situation is much too totalistic to allow the physician any action independent of what the torture regime requires. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  12. Transcript profiling of crown rootless1 mutant stem base reveals new elements associated with crown root development in rice

    Directory of Open Access Journals (Sweden)

    Van Anh Le Thi

    2011-08-01

    Full Text Available Abstract Background In rice, the major part of the post-embryonic root system is made of stem-derived roots named crown roots (CR. Among the few characterized rice mutants affected in root development, crown rootless1 mutant is unable to initiate crown root primordia. CROWN ROOTLESS1 (CRL1 is induced by auxin and encodes an AS2/LOB-domain transcription factor that acts upstream of the gene regulatory network controlling CR development. Results To identify genes involved in CR development, we compared global gene expression profile in stem bases of crl1 mutant and wild-type (WT plants. Our analysis revealed that 250 and 236 genes are down- and up-regulated respectively in the crl1 mutant. Auxin induces CRL1 expression and consequently it is expected that auxin also alters the expression of genes that are early regulated by CRL1. To identify genes under the early control of CRL1, we monitored the expression kinetics of a selected subset of genes, mainly chosen among those exhibiting differential expression, in crl1 and WT following exogenous auxin treatment. This analysis revealed that most of these genes, mainly related to hormone, water and nutrient, development and homeostasis, were likely not regulated directly by CRL1. We hypothesized that the differential expression for these genes observed in the crl1 mutant is likely a consequence of the absence of CR formation. Otherwise, three CRL1-dependent auxin-responsive genes: FSM (FLATENNED SHOOT MERISTEM/FAS1 (FASCIATA1, GTE4 (GENERAL TRANSCRIPTION FACTOR GROUP E4 and MAP (MICROTUBULE-ASSOCIATED PROTEIN were identified. FSM/FAS1 and GTE4 are known in rice and Arabidopsis to be involved in the maintenance of root meristem through chromatin remodelling and cell cycle regulation respectively. Conclusion Our data showed that the differential regulation of most genes in crl1 versus WT may be an indirect consequence of CRL1 inactivation resulting from the absence of CR in the crl1 mutant. Nevertheless

  13. Resin composite repair for implant-supported crowns.

    Science.gov (United States)

    Bonfante, Estevam A; Suzuki, Marcelo; Hirata, Ronaldo; Bonfante, Gerson; Fardin, Vinicius P; Coelho, Paulo G

    2017-08-01

    This study evaluated the reliability of implant-supported crowns repaired with resin composites. Fifty-four titanium abutments were divided in three groups (n = 18 each) to support resin nanoceramic molar crowns, as follows: (LU) (Lava Ultimate, 3M ESPE); LU repaired with either a direct or an indirect resin composite. Samples were subjected to mouth-motion accelerated-life testing in water (n = 18). Cumulative damage with a use stress of 300 N was used to plot Weibull curves for group comparison. Reliability was calculated for a mission of 100,000 cycles at 400 N load. Beta values were 0.83 for LU, 0.31 and 0.27 for LU repaired with Filtek and Ceramage, respectively. Weibull modulus for LU was 9.5 and η = 1047 N, m = 6.85, and η = 1002 N for LU repaired with Ceramage, and m = 4.65 and η = 766 N for LU repaired with Filtek (p material, and detailed fractography is presented. The performance of resin nanoceramic material repaired with an indirect composite was maintained after accelerated-life testing compared to unrepaired controls. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1481-1489, 2017. © 2016 Wiley Periodicals, Inc.

  14. Metabolic changes in Avena sativa crowns recovering from freezing.

    Science.gov (United States)

    Henson, Cynthia A; Duke, Stanley H; Livingston, David P

    2014-01-01

    Extensive research has been conducted on cold acclimation and freezing tolerance of fall-sown cereal plants due to their economic importance; however, little has been reported on the biochemical changes occurring over time after the freezing conditions are replaced by conditions favorable for recovery and growth such as would occur during spring. In this study, GC-MS was used to detect metabolic changes in the overwintering crown tissue of oat (Avena sativa L.) during a fourteen day time-course after freezing. Metabolomic analysis revealed increases in most amino acids, particularly proline, 5-oxoproline and arginine, which increased greatly in crowns that were frozen compared to controls and correlated very significantly with days after freezing. In contrast, sugar and sugar related metabolites were little changed by freezing, except sucrose and fructose which decreased dramatically. In frozen tissue all TCA cycle metabolites, especially citrate and malate, decreased in relation to unfrozen tissue. Alterations in some amino acid pools after freezing were similar to those observed in cold acclimation whereas most changes in sugar pools after freezing were not. These similarities and differences suggest that there are common as well as unique genetic mechanisms between these two environmental conditions that are crucial to the winter survival of plants.

  15. Coordinate geometry method for capturing and evaluating crown preparation geometry.

    Science.gov (United States)

    Tiu, Janine; Waddell, J Neil; Al-Amleh, Basil; Jansen van Vuuren, Wendy-Ann; Swain, Michael V

    2014-09-01

    A validated universal method requiring no human input is needed to capture and evaluate preparation geometries in a manner that can be used to see the correlation of different parameters. The purpose of this study was to present a method of capturing and evaluating crown preparation geometry. One manually machined acrylic resin block and 9 randomly selected preparations for ceramic complete crowns prepared by general dentists were selected and prepared. The specimens were scanned (3D scanner; Nobel Biocare), and buccolingual and mesiodistal cross section images were collected. The images were imported into digitizing software (Engauge Digitizer 4.1) to convert the outlines into x and y coordinates. Six points were chosen by using a set of algorithms, and the resulting parameters were calculated. The acrylic resin block was milled with a 12 degree total occlusal convergence (TOC) instrument producing a 12.83 degree TOC. For the other specimens, average TOC values ranged from 18 degrees to 52 degrees. The mean average margin width was 0.70 mm, and the mean average base dimension was 6.23 mm. The surface area/volume ratio, resistance length, and limiting taper were also calculated. The method described provides a basis for accurately evaluating preparation geometry without human input. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  16. Induced mutations for tolerance of oats to crown rust

    International Nuclear Information System (INIS)

    Simons, M.D.; Frey, K.J.

    1977-01-01

    Seeds of three oat (Avena sativa and A. abyssinica) strains were treated with ethyl methanesulphonate (EMS), and crown rust (caused by Puccinia coronata var. avenae) tolerance ratios of M 5 -derived lines were compared with untreated checks. Tolerance ratios of mutant lines tended to be distributed in both plus and minus directions. No mutant oat line had a significant increase in grain yield, but many showed significantly depressed yields. With C.I. 6665, only five of 130 mutagen-derived lines were not significantly below the check for grain yield; one of these had significantly improved tolerance. Re-treatment of selected strains from a previous EMS treatment (original cultivar was Clintland-60) gave one M 5 -derived oat line (of 100 tested) that was equal to Clintland-60 in grain yield and sustained no damage from crown rust (i.e. it had a tolerance ratio of 100). EMS treatment of the highly susceptible tetraploid C.I. 2110 resulted in both significantly increased and reduced tolerance. (author)

  17. Short implants supporting single crowns in atrophic jaws.

    Science.gov (United States)

    Al-Ansari, Asim

    2014-09-01

    PubMed-Medline, Web of Science, Cochrane Library, ProQuest Dissertations and Theses, LILACS, Ebsco-Dentistry and Oral Sciences Source, Scirus, Embase, Scopus and Journal Ovid databases were searched. In addition hand searching of 14 relevant journals was undertaken along with screening of the reference lists of screened article and reviews. Randomised controlled clinical trials (RCTs), controlled clinical trials (CCTs), prospective cohort studies and case series were included. Studies where short (biological failure proportion (BFP), prosthetic failure proportion (PFP) and radiographic marginal bone loss (MBL) were 5.9% (95% CI: 3.7-9.2%), 3.8% (95%CI: 1.9-7.4%), 2.8% (95%CI: 1.4-5.7%) and 0.83 mm (95%CI: 0.54-1.12 mm) respectively. Quantitative analysis showed that placement in the mandible (p = 0.0002) and implants with length ≤ 8 mm (p = 0.01) increased FP, BFP and MBL, whereas qualitative assessment revealed that crown-to-implant ratio did not influence MBL. Within the limitations of the present systematic review with meta-analysis, it is suggested that single crowns supported by short implants are an acceptable and predictable option in the short- and long-term treatment of the atrophic jaws.

  18. The confusing array of tooth-colored crowns.

    Science.gov (United States)

    Christensen, Gordon J

    2003-09-01

    The venerable PFM crown or fixed prosthesis still dominates the tooth-colored restoration market. However, use of PFMs is declining slightly, as the many new all-ceramic and resin-based composite crowns and fixed-prosthesis products flood the market. Several situations may indicate the use of materials other than PFM. They include patients requiring a high level of esthetic acceptability, patients with proven or perceived allergies to the metals used in dentistry and bruxing or clenching patients with metal allergies or desire to eliminate metal from their mouths. PFM restorations have been proven during 40 years of successful use. They provide acceptable esthetics for most situations, minimal fracture during service, proven ability to serve in multiple-unit situations and excellent fit, and the profession has detailed knowledge of these restorations' advantages, disadvantages and physical characteristics. PFM restorations have only a few well-known negative characteristics. Be cautious as you elect to move from the reliability and positive history of PFM to relatively unknown types of restorations.

  19. Sonographic Diagnosis of Complicated Cholecystitis.

    Science.gov (United States)

    Shapira-Rootman, Mika; Mahamid, Ahmad; Reindorp, Nadir; Nachtigal, Alicia; Zeina, Abdel-Rauf

    2015-12-01

    Early detection of the complications of cholecystitis is important for clinical management, yet only a small percentage of patients have a correct diagnosis before surgery. The purpose of our study was to identify sonographic findings that are associated with complicated cholecystitis. Sonographic, surgical, and pathologic reports were reviewed for 70 patients who underwent early cholecystectomies from January 2010 to August 2014. Sonograms were assessed for 16 independent variables. Statistical analyses were performed to evaluate associations between various sonographic features and complicated cholecystitis. Sonographic signs associated with complicated cholecystitis (Pcholecystitis. In most cases, sonograms reflected severe inflammation, with multiple sonographic signs. Although multiple sonographic signs are associated with complicated cholecystitis, none of them is sensitive and specific enough to definitively diagnose it. Sonograms usually reflect severe inflammation, with numerous sonographic signs. Thus, in the right clinical context, sonograms of severe cholecystitis should alert radiologists to the possibility of complications. © 2015 by the American Institute of Ultrasound in Medicine.

  20. Gastrointestinal Complications After Bariatric Surgery

    OpenAIRE

    Ma, Irene T.; Madura, James A.

    2015-01-01

    Bariatric surgery is increasingly being performed in the medically complicated obese population as convincing data continue to mount, documenting the success of surgery not only in achieving meaningful weight loss but also in correcting obesity-related illnesses. Several surgical procedures with varying degrees of success and complications are currently being performed. This article discusses the short- and long-term gastrointestinal complications for the 4 most common bariatric surgical proc...

  1. Functional and esthetic considerations for single-tooth Ankylos implant-crowns: 8 years of clinical performance.

    Science.gov (United States)

    Döring, Katrin; Eisenmann, Eduard; Stiller, Michael

    2004-01-01

    Following the loss of an anterior natural tooth, the mucogingival complex begins to collapse. The early placement of endosseous dental implants can prevent or reduce the extent of this collapse. If there is a long interval between the loss of the natural tooth and the placement of the implant prosthetic replacement, this collapse tends to increase significantly. This paper will report on the clinical success of this implant product in the fabrication of esthetic, functional, and harmonious replacements for missing single, natural teeth for a period of 8 years. A total of 275 single Ankylos implant tooth restorations in the anterior and posterior jaw regions were placed and monitored for 8 years. Of these, 264 implants were restored using the titanium Balance abutments, and only 11 were restored using ceramic abutments. The final restorations were either metal-ceramic or full-ceramic crowns and were cemented with glass ionomer cement. The survival rate was 98.2%, with only 5 implants being lost during the healing phase. There were no other implant losses in the postloading period that averaged 3.2 years. To date, there have been no mechanical complications associated with the prosthetic components (ie, screw loosening, screw breaking, or crown breaking) for either the titanium or the ceramic abutments. Experience with the Ankylos system with single-tooth replacement indications may be considered positive with regard to the esthetic and functional results of the treatment. The lack of mechanical complications and problems with the hard and soft tissue in the loading phase of the implants suggests the functional safety of the tapered connection between implant and abutment.

  2. [Complications of acute otitis media].

    Science.gov (United States)

    Laulajainen-Hongisto, Anu; Lempinen, Laura; Jero, Jussi

    2012-01-01

    Most cases of acute otitis media (AOM) resolve even without antibiotic treatment. In the pre-antibiotic era, AOM complications were common and could lead to deafness and neurological sequelae. With the use of antibiotics, the complications have become less frequent, but they may still evolve. The possible increase in the occurrence of complications has to be considered if we start treating AOM more conservatively and if bacterial antibiotic resistance situation becomes more problematic. These rare but possibly lethal complications should be diagnosed and treated promptly. The need for cochlear implantation has to be evaluated soon after an episode of meningitis if deafness is suspected.

  3. [Neurological complication of influenza infections].

    Science.gov (United States)

    Brydak, Lidia B

    2002-01-01

    The aim of this study was to present neurological complications of influenza infections. Infections caused by influenza viruses can be very serious and may lead even to death resulted from the post-infectious complications. The most often occurring complications are pneumonia, bronchitis, bronchiolitis, myocarditis and otitis media. The other group is neurological post-influenza complications, including dementia, epileptic disorders, cerebrovascular disease, febrile convulsions, toxic encephalopathy, encephalitis, meningitis, subarachnoid hemorrhages, lethargic encephalitis, psychosis or increase in the number of cases of Parkinson's disease. The first way of prevention of influenza is vaccination that results in healthy, social and economic benefits.

  4. [Preliminary evaluation of clinical effect of computer aided design and computer aided manufacture zirconia crown].

    Science.gov (United States)

    Wang, Yu-guang; Xing, Yan-xi; Sun, Yu-chun; Zhao, Yi-jiao; Lü, Pei-jun; Wang, Yong

    2013-06-01

    To evaluate clinical effects of computer aided design and computer aided manufacturing (CAD/CAM) milled zirconia crown in three aspects: aesthetic, contact wear and fracture. Sixty patients were divided into two groups.In one group, 35 full contour CAD/CAM zirconia crown were made on molars of 30 patients. The manufacturing process of zirconia crown was as follow. First, the three dimensional(3-D) data of working models, antagonist impression and check records were acquired by 3-D laser scanning Dental wings S50. Then full contour zirconia crowns, which had functional occlusal contacts with antagonistic teeth, and appropriate contact with adjacent teeth were designed with Zeno-CAD(V4.2.5.5.12919) software. ZENOSTAR Zr pure zirconia material was milled in digital controlled machine WIELAND 4030 M1.In the end, the zirconia crown were completed with the method of second sintering and polishing. After clinical try-in, the crown was cemented.In the control group, thirty gold alloy full crown were made and cemented on molars of 30 patients. According to the modified U S Public Health Service Criteria(USPHS) evaluation standard, all crowns were evaluated on the same day, at three months, half a year, one year and two years following delivery. There were three aspects we were focusing on in the evaluation: aesthetic, contact wear(restoration and antagonist), and fracture. In all the prosthesis we evaluated during the 24 months, no fracture was found. Contact wear of crowns varies according to different antagonist teeth. The zirconia crowns show privilege in aesthesis, toughness and anti-wearing.However, there is contact wear on antagonistic natural teeth. Thus it is a good choice when full zirconia crowns are indicated on two antagonistic teeth in both jaws.

  5. Load-bearing capacity and the recommended thickness of dental monolithic zirconia single crowns.

    Science.gov (United States)

    Sun, Ting; Zhou, Shanyu; Lai, Renfa; Liu, Ruoyu; Ma, Shuyuan; Zhou, Zhiying; Longquan, Shao

    2014-07-01

    The aim of this study was to evaluate the load bearing capacity and a reasonable thicknesss of dental monolithic zirconia crowns. Polymethyl methacrylate (PMMA) abutment tooth specimens were made by CAD/CAM technic. Monolithic zirconia crowns (MZC), monolithic lithium disilicate crowns (MLC), layered zirconia crowns (LZC) and metal ceramic crowns(MCC), of which the occlusal thickness was 1.5mm were thereafter fabricated and cemented on the abutment tooth specimens. MCC with occlusal thicknesses of 0.6mm, 0.8mm, 1.00mm, 1.2mm were also made. All specimens underwent load-to-fracture test. Weibull parameters (σ0) and (m) were calculated. Fracture modes were also evaluated. The mean fracture load was 1863.16±116.81 for MLC, 2284.77±355.60 for MCC, 2308.0±510.94 for LZC, 4109.93±610.18 for MZC (1.5mm), 3068.31±233.88 for MZC (1.2mm), 2429.88±315.03 for MZC (1.0mm), 1814.60±68.21 for MZC (0.8mm) and 1308.38±111.38 for MZC (0.6mm). The fracture load of MZC was significantly higher than MCC, LZC and MLC (P0.05). Monolithic zirconia crowns exhibit higher fracture loads than monolithic lithium disilicate crowns, layered zirconia crowns and metal ceramic crowns. The fracture resistance of monolithic zirconia crowns with a thickness of 1.0mm can be equal to metal ceramic crowns. Doubling the monolithic zirconia core from 0.6mm to 1.5mm increases the fracture resistance of this restorative system threefold. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Effect of Intraoral Mechanical Cleaning Techniques on Bond Strength of Cast Crowns to Metal Cores.

    Science.gov (United States)

    AlZain, Sahar; Kattadiyil, Mathew T; AlHelal, Abdulaziz; Alqahtani, Ali

    2017-11-30

    To evaluate the effect of cleaning of metal cores from provisional cement, using an intraoral airborne-particle abrasion method, on the bond strength of permanent resin cement with cast crowns to cores. Thirty stainless steel models of a standard complete crown tooth preparation were fabricated. Thirty Type III gold crowns were fabricated. Each cast crown corresponded to one stainless steel crown preparation model. All crowns were cemented with noneugenol zinc oxide cement and stored for 7 days at 37°C. All crowns were debonded, and the cement was cleaned with airborne-particle abrasion using 50 μm aluminum oxide at 4.1 bar (0.41 MPa) followed by ultrasonic cleaning. Based on the mechanical cleaning technique of the remaining provisional cement on surfaces of cast cores, specimens were equally divided into 3 groups: hand cleaning (HC) with a dental excavator, hand cleaning followed by polishing using a brush and pumice (BP), and hand cleaning followed by intraoral airborne-particle abrasion (APA). All crowns were then cemented to their corresponding cores using universal resin cement. All crowns were stored for 7 days at 37°C. An Instron universal testing machine was used to record the bond strength of crowns. Airborne-particle abrasion method for intraoral mechanical cleaning revealed a statistically significantly higher bond strength compared to the other two methods. When comparing the three methods of provisional cement cleaning from metal cores, airborne-particle abrasion resulted in the highest bond strength for cast crowns. © 2017 by the American College of Prosthodontists.

  7. Placenta associated pregnancy complications in pregnancies complicated with placenta previa

    Directory of Open Access Journals (Sweden)

    Yael Baumfeld

    2017-06-01

    Conclusions: Our study demonstrated an increased rate of placental insufficiency associated complications in women with placenta previa. This is of clinical relevance and suggests that a careful surveillance for women with placenta previa may help in minimizing maternal, fetal and neonatal complications.

  8. Comparison of Complications in Removable Mandibular Acrylic Splint and Cantilever Herbst for Management of Class II Malocclusion: A Retrospective Study.

    Science.gov (United States)

    Kanuru, R K; Bhasin, Vinny; Khatri, Amit; Dodda, K K; Singh, Era; Grover, Shekhar

    2017-05-01

    Numerous appliances are present for the management of class II malocclusion. We have conducted a study to compare the clinical complications during treatment with either a removable mandibular acrylic splint (RMS) or with a cantilever Herbst (HC) appliance for the management of class II malocclusion. This study consisted of records of 114 patients (61 males, 53 females), who were divided into two groups. Group I received RMS and group II received HC for the treatment of class II, Division 1 malocclusion. They were further subdivided according to the telescopic system used [Dentaurum type I or propulsor mandibular abzil (PMA)] and fixation mode (splint with crowns or GripTite bands). Patients' clinical records were assessed to identify clinical complications. The results of the study showed that the incidence of complications during treatment in both groups was statistically nonsignificant. The complications with either crown or band were also statistically nonsignificant. The Dentaurum group showed more susceptibility to complications than the PMA group. The PMA telescopic system is more efficient as compared with Dentaurum. Complication resulting from Herbst appliance is independent type of appliance used and mode of fixation. Herbst appliance is the treatment of choice for class II malocclusion.

  9. Short (8-mm) locking-taper implants supporting single crowns in posterior region: a prospective clinical study with 1-to 10-years of follow-up.

    Science.gov (United States)

    Mangano, Francesco Guido; Shibli, Jamil Awad; Sammons, Rachel Lilian; Iaculli, Flavia; Piattelli, Adriano; Mangano, Carlo

    2014-08-01

    The aim of this study was to evaluate the long-term outcome of short (8-mm) locking-taper implants supporting single crowns in the posterior regions and to analyze the influence of different factors on implant survival and implant-crown success rates. Between June 2002 and September 2011, all patients referred to two private practices for treatment with short (8-mm) implants supporting single tooth restorations in posterior areas of both jaws were considered for inclusion in this study. At each annual follow-up session, clinical and radiographic parameters were assessed. Implant-crown success criteria included absence of pain, suppuration, mobility, and peri-implant radiolucency, distance between the implant shoulder and the first visible bone-to-implant contact (DIB) implant-crown success were assessed using the Kaplan-Meier survival estimator; Chi-square test was applied to evaluate correlations between the study variables. The statistical analysis was performed at the patient and at the implant level. Two hundred and fifteen implants (124 maxilla; 91 mandible) were placed in 194 patients (104 men; 90 women). Three implants failed (2 maxilla; 1 mandible). The 10-year cumulative survival rate was 98.4% (patient-based) and 98.5% (implant-based). Among the surviving implants, the mean DIB was 0.31 (±0.24), 0.43 (±0.29), and 0.62 (±0.31) mm at the 1-, 5-, and 10-year follow-up session; two biologic and three prosthetic complications were reported, for a 10-year cumulative implant-crown success rate of 95.8% (patient-based) and 95.9% (implant-based). The implant survival and implant-crown success rates did not differ significantly with respect to patients' gender, age, smoking habit, parafunctional habit, implant location, implant diameter, and bone type. The use of short (8-mm) locking-taper implants is a predictable treatment modality for the restoration of single tooth gaps of posterior segments of dentition. © 2013 John Wiley & Sons A/S. Published by John

  10. Fracture Strength and Failure Mode of Maxillary Implant-Supported Provisional Single Crowns : A Comparison of Composite Resin Crowns Fabricated Directly Over PEEK Abutments and Solid Titanium Abutments

    NARCIS (Netherlands)

    Santing, H.J.; Meijer, Henny J.A.; Raghoebar, G.M.; Ozcan, M.

    2012-01-01

    Background: Polyetheretherketone (PEEK) temporary abutments have been recently introduced for making implant-supported provisional single crowns. Little information is available in the dental literature on the durability of provisional implant-supported restorations. Purpose: The objectives of this

  11. Cemented versus screw-retained implant-supported single-tooth crowns: a 10-year randomised controlled trial.

    Science.gov (United States)

    Vigolo, Paolo; Mutinelli, Sabrina; Givani, Andrea; Stellini, Edoardo

    2012-01-01

    The purpose of this randomised controlled trial was to compare the long-term clinical outcome of cemented and screw-retained implant-supported single-tooth crowns. Eighteen consecutive patients presenting with single-tooth bilateral edentulous sites in the canine/molar region with adequate bone width, similar bone height at the implant sites, and an occlusal scheme that allowed for the establishment of identical occlusal cusp/fossa contacts were treated. Each patient received two identical implants according to a split-mouth design. One side was randomly selected to be restored with a cemented implant-supported single crown, and the other was restored with a screw-retained implant-supported single crown. Outcome measures were implant success, complications, marginal bone levels and peri-implant soft tissue health. Ten years after initial loading, 2 patients moved away and were lost to follow-up. Two implants placed in the same patient failed 5 years after their insertion; the remaining 30 implants survived, resulting in a cumulative implant success rate of 93.7%. No complication occurred. The mean marginal bone resorption at 10 years after implant placement, measured on intraoral radiographs, was 1.1 ± 0.2 mm for both types of restorations. There were no statistically significant differences between the two groups with respect to peri-implant marginal bone level at the 10-year follow-up appointment (T2) (P = 0.58); at the 4-year follow-up appointment (T1) a statistically significant difference was observed (P = 0.01), but this was not considered clinically relevant (mean difference: -0.06 mm). The status of the soft tissue around the implants remained stable over the evaluation period. No statistically significant difference was identified for the facial keratinised gingiva between the two groups at T1 (P = 0.10) or at T2 (P = 0.07). Within the limitations of this study, the results indicate that there was no evidence of a significant difference in the clinical

  12. Retention Load Values of Telescopic Crowns Made of Y-TZP and CoCr with Y-TZP Secondary Crowns: Impact of Different Taper Angles

    Directory of Open Access Journals (Sweden)

    Susanne Merk

    2016-05-01

    Full Text Available This study aimed to examine and compare the retention load values (RL of different telescopic crown assemblies (Y-TZP and CoCr primary crowns with electroformed and Y-TZP secondary crowns each with three different taper angles (0°, 1° and 2°. Thirty Y-TZP primary crowns with electroformed gold copings (Z/G group and Y-TZP secondary crowns (Z/Z group and 30 CoCr primary crowns with electroformed gold copings (C/G group and Y-TZP secondary crowns (C/Z group, each with taper angles of 0°, 1° and 2°, were fabricated, respectively. With the exception of the electroformed gold copings, all specimens were Computer-Aided-Design/Computer-Aided-Manufacturing (CAD/CAM-milled, then sintered and afterwards manually adapted. In order to stabilize the gold copings, they were fixed in a tertiary structure. The secondary crowns were constructed with a hook, which ensured self-alignment with an upper chain. Afterwards, 20 pull-off test cycles were performed in a universal testing machine under artificial saliva and after weighing the secondary crowns with a 5 kg object for 20 s. Data were analyzed by one-way and two-way Analysis of Variance (ANOVA. C/Z with 1° showed higher (p = 0.009 RL than 0° and 2° tapers. C/G at 1° also showed higher (p = 0.001 RL than at tapers of 0° and 2°. Z/G and C/G at 0° showed lower RL than Z/Z and C/Z (p < 0.001. Primary crowns had no impact on the 0° group. Z/G showed lower RL as compared to C/Z within the 1° group (p = 0.007 and Z/Z in the 2° group (p = 0.006. The primary crown material had no influence on RL. Electroformed copings showed lower RL. Further investigations for 1° as well as for the long-term performance after thermomechanical aging are necessary.

  13. Three-dimensional finite element analysis of molars with thin-walled prosthetic crowns made of various materials.

    Science.gov (United States)

    Dejak, Beata; Młotkowski, Andrzej; Langot, Cezary

    2012-04-01

    The aim of the study was to compare the strength of thin-walled molar crowns made of various materials under simulation of mastication. Five 3D FE models of the first lower molar with the use of contact elements were created: intact tooth; tooth with a zirconia crown; tooth with a porcelain crown; tooth with a gold alloy crown and tooth with a composite crown. The computer simulations of mastication were conducted. For the models, equivalent stresseswere calculated using the modified von Mises failure criterion (mvM). Contact stresses at the adhesive interface between the cement and tooth structure under the crowns were analyzed. Equivalent stresses in the crowns, did not exceed the tensile strength of their material. The mvM stresses in resin cement under the zirconia crown were 1.3 MPa, and under the composite crown they increased over 6 times. The tensile and shear contact stressesunder the stiff crowns (ceramics and gold alloy), were several times lower than those under the composite one. The maximum mvM stresses in the tooth structure for the zirconia crown were only 2.8 MPa, whereas for the composite crown were 6.4 MPa. The higher elastic modulus the crown was, the lower the equivalent stresses occurred in the composite luting cement and in the tooth structures. Also contact stresses decreased with the increasing stiffness of the crowns. Under physiological loads, the thin-walled crowns perfectly luted to molars, made of zirconia ceramic, gold alloys and composite resin are resistant to failure. Prosthetic crowns made of stiff materials are less prone to debonding than those made of composite resin. Prosthetic crowns made of a material with a higher elastic modulus than enamel will strengthen the dental structures of molar teeth. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. An in vivo evaluation of fit of zirconium-oxide based ceramic single crowns, generated with two CAD/CAM systems, in comparison to metal ceramic single crowns.

    Science.gov (United States)

    Biscaro, Leonello; Bonfiglioli, Roberto; Soattin, Massimo; Vigolo, Paolo

    2013-01-01

    The purpose of this study was to assess in vivo the marginal fit of single crowns produced using two CAD/CAM all-ceramic systems, in comparison to more traditional metal ceramic crowns. Thirty vital, caries-free, and previously untreated teeth were chosen in five patients who needed extraction for implant placement and therefore were included in this study. In the control group (C), 10 regular metal ceramic crowns with porcelain occlusal surfaces were fabricated. In the other two groups (Z and E), CAD/CAM technology was used for the fabrication of 20 zirconium-oxide-based ceramic single crowns with two systems. All zirconia crowns were cemented with glass-ionomer cement, always following the manufacturer's instructions. The same dentist carried out all clinical phases. The teeth were extracted 1 month later. Marginal gaps along vertical planes were measured for each crown, using a total of four landmarks for each tooth by means of a microscope at a magnification of 50×. On completion of microscopic evaluation, representative specimens from each group were prepared for ESEM evaluation. Mean and standard deviations of the four landmarks (mesial, distal, buccal, palatal) at each single crown were calculated for each group. Multivariate analysis of variance (MANOVA) was performed to determine whether the four landmarks, taken into consideration together, differed between groups. Two-way ANOVA was performed to study in detail, for each landmark, how the three systems used to produce the FPDs affected the gap measurements. Differences were considered to be significant at p compared to more traditional metal ceramic crowns. © 2012 by the American College of Prosthodontists.

  15. Surface fire effects on conifer and hardwood crowns--applications of an integral plume model

    Science.gov (United States)

    Matthew Dickinson; Anthony Bova; Kathleen Kavanagh; Antoine Randolph; Lawrence Band

    2009-01-01

    An integral plume model was applied to the problems of tree death from canopy injury in dormant-season hardwoods and branch embolism in Douglas fir (Pseudotsuga menziesii) crowns. Our purpose was to generate testable hypotheses. We used the integral plume models to relate crown injury to bole injury and to explore the effects of variation in fire...

  16. A semi-empirical model for predicting crown diameter of cedrela ...

    African Journals Online (AJOL)

    A semi-empirical model relating age and breast height has been developed to predict individual tree crown diameter for Cedrela odorata (L) plantation in the moist evergreen forest zones of Ghana. The model was based on field records of 269 trees, and could determine the crown cover dynamics, forecast time of canopy ...

  17. Zirconia crowns--an esthetic and resistant restorative alternative for ECC affected primary teeth.

    Science.gov (United States)

    Planells del Pozo, P; Fuks, A B

    2014-01-01

    The present report discusses briefly the problem of ECC in very young children and the recommended approaches for prevention and treatment. The esthetic restoration of the maxillary incisors with Zirconia Nu Smile crowns is described. It is also stressed that the luxation injury two months after placement did not damage the appearance nor the stability of the crowns.

  18. Randomized clinical study of wear of enamel antagonists against polished monolithic zirconia crowns.

    Science.gov (United States)

    Esquivel-Upshaw, J F; Kim, M J; Hsu, S M; Abdulhameed, N; Jenkins, R; Neal, D; Ren, F; Clark, A E

    2018-01-01

    To test the hypothesis that there is no difference in the in vivo maximum wear of enamel opposing monolithic zirconia crowns, enamel opposing porcelain fused to metal crowns and enamel opposing enamel. Thirty patients needing single crowns were randomized to receive either a monolithic zirconia or metal-ceramic crown. Two non-restored opposing teeth in the same quadrants were identified to serve as enamel controls. After cementation, quadrants were scanned for baseline data. Polyvinylsiloxane impressions were obtained and poured in white stone. Patients were recalled at six-months and one-year for re-impression. Stone models were scanned using a tabletop laserscanner to determine maximum wear. Statistical analysis was performed using Mann-Whitney U to determine any significant differences between the wear of enamel against zirconia and metal-ceramic crowns. Sixteen zirconia and 14 metal-ceramic crowns were delivered. There were no statistical differences in mean wear of crown types (p=0.165); enamel antagonists (p=0.235) and enamel controls (p=0.843) after one year. Monolithic zirconia exhibited comparable wear of enamel compared with metal-ceramic crowns and control enamel after one year. This study is clinically significant because the use of polished monolithic zirconia demonstrated comparable wear of opposing enamel to metal-ceramic and enamel antagonists. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Polyacrylonitrile (PAN)/crown ether composite nanofibers for the selective adsorption of cations

    NARCIS (Netherlands)

    Tas, Sinem; Kaynan, Ozge; Ozden-Yenigun, Elif; Nijmeijer, Dorothea C.

    2016-01-01

    In this study, we prepared electrospun polyacrylonitrile (PAN) nanofibers functionalized with dibenzo-18-crown-6 (DB18C6) crown ether and showed the potential of these fibers for the selective recovery of K+ from other both mono- and divalent ions in aqueous solutions. Nanofibers were characterized

  20. First report of Fusarium redolens causing crown rot of wheat (Triticum spp.) in Turkey

    Science.gov (United States)

    Fusarium crown rot, caused by a complex of Fusarium spp., is a yield-limiting disease of wheat world-wide, especially in dry Mediterranean climates. In order to identify Fusarium species associated with crown rot of wheat, a survey was conducted in summer 2013 in the major wheat growing regions of T...