WorldWideScience

Sample records for abutments

  1. Integral Abutment and Jointless Bridges

    OpenAIRE

    Cristian-Claudiu Comisu

    2005-01-01

    Integral bridges, or integral abutment and jointless bridges, as they are more commonly known in the USA, are constructed without any movement joints between spans or between spans and abutments. Typically these bridges have stub-type abutments supported on piles and continuous bridge deck from one embankment to the other. Foundations are usually designed to be small and flexible to facilitate horizontal movement or rocking of the support. Integrally bridges are simple or multiple span ones t...

  2. An introduction to single implant abutments.

    LENUS (Irish Health Repository)

    Warreth, Abdulhadi

    2013-01-01

    This article is an introduction to single implant abutments and aims to provide basic information about abutments which are essential for all dental personnel who are involved in dental implantology. Clinical Relevance: This article provides a basic knowledge of implants and implant abutments which are of paramount importance, as replacement of missing teeth with oral implants has become a well-established clinical procedure.

  3. Transition Slabs of Integral Abutment Bridges

    OpenAIRE

    Dreier, Damien; Muttoni, Aurelio; BURDET, Olivier

    2011-01-01

    Over the past decades, an increasing number of bridges with integral abutment have been built in Switzerland. This type of bridge offers various advantages over standard bridges with abutments, equipped with expansion joints and bearings that require regular inspection and maintenance. One main concern of integral abutment bridges is related to the soil-structure interaction, in particular between the transition slab and the embankment. To avoid any expansion joints, transition slabs are dire...

  4. Comparison of Fracture Resistance and Failure Mode of Different Zirconia Abutments with Titanium Abutment

    Directory of Open Access Journals (Sweden)

    Ghasem Omati Shabestari

    2013-02-01

    Full Text Available Background and Aims: One of the decicive factors on the final esthetic results of implant treatment is theabutment material. Ceramic abutments are nowadays very popular in this regard. The purpose of this study was tocompare the fracture resistance of three zirconia abutments with titanium abutment.Materials and Methods: Four groups of abutments 4 recorded for each specimen. The data were analyzed using One-way ANOVA.Results: The mean values recorded for fracture resistance of different zirconia abutments varied between 426 to688 N; however, there was no significant differences among the groups

  5. Local scour at abutments: A review

    Indian Academy of Sciences (India)

    Abdul Karim Barbhuiya; Subhasish Dey

    2004-10-01

    Failure of bridges due to local scour has motivated many investigators to explore the causes of scouring and to predict the maximum scour depth at abutments. In this paper, a detailed review of the up-to-date work on scour at abutments is presented including all possible aspects, such as flow field, scouring process, parameters affecting scour depth, time-variation of scour and scour depth estimation formulae.

  6. Laboratory technique for coloring titanium abutments to improve esthetics.

    Science.gov (United States)

    Wadhwani, Chandur P K; O'Brien, Richard; Kattadiyil, Mathew T; Chung, Kwok-Hung

    2016-04-01

    Titanium alloys are used for implant abutments onto which prostheses are attached. One major disadvantage of titanium abutments is their esthetics; the metallic gray color may show through the restorative material or through surrounding tissues. A laboratory technique using readily available household items is described that can alter the abutment color by anodization. PMID:26723096

  7. 21 CFR 872.3630 - Endosseous dental implant abutment.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Endosseous dental implant abutment. 872.3630... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3630 Endosseous dental implant abutment. (a) Identification. An endosseous dental implant abutment is a premanufactured prosthetic...

  8. Clinical Use of Laser-Microtextured Abutments: A Case Series.

    Science.gov (United States)

    Shapoff, Cary A; Babushkin, Jeffrey A; Wohl, David J

    2016-01-01

    This article discusses the clinical use of laser-microtextured abutments on dental implant restorations. Four cases are presented, each using one of the four commercially available laser-microtextured abutment styles. Numerous preclinical and clinical studies have shown the positive effects of laser microtexturing on the implant platform in limiting crestal bone loss and benefiting soft tissue stability. Other histologic studies of laser microtexturing on the implant abutment have demonstrated the ability of this specific feature to block epithelial downgrowth and provide a functional connective tissue attachment to the abutment surface. Other abutment designs, styles, and materials have only demonstrated a soft tissue seal with epithelial adhesion and a circular ring of connective tissue fibers around the abutment without direct contact. This article presents clinical and radiographic case examples from a private practice perspective on the longterm successful use of microtextured abutments with respect to crestal bone levels, exceptional soft tissue health, and stability with minimal sulcular depth. PMID:27560683

  9. Dynamic Soil-Structure Interaction in Bridge Abutments

    OpenAIRE

    Martínez Cutillas, Antonio; Mateo Bermejo, J.; Alarcón Álvarez, Enrique

    1996-01-01

    Strong motion obtained in instrumental short-span bridges show the importance of the abutments in the dynamic response of the whole structure. Many models have been used in order to take into account the influence of pier foundations although no reliable ones have been used to analyse the abutment performance. In this work three-dimensional Boundary Element models in frequency domain have been proposed and dimensionless dynamic stiffness of standard bridge abutments have been obtained.

  10. Abrasion of abutment screw coated with TiN

    OpenAIRE

    Jung, Seok-Won; Son, Mee-Kyoung; Chung, Chae-Heon; Kim, Hee-Jung

    2009-01-01

    STATEMENT OF PROBLEM Screw loosening has been a common complication and still reported frequently. PURPOSE The purpose of this study was to evaluate abrasion of the implant fixture and TiN coated abutment screw after repeated delivery and removal with universal measuring microscope. MATERIAL AND METHODS Implant systems used for this study were Osstem and 3i. Seven pairs of implant fixtures, abutments and abutment screws for each system were selected and all the fixtures were perpendicularly m...

  11. Time-wise variation of scouring at bridge abutments

    Indian Academy of Sciences (India)

    A Melih Yanmaz; Omer Kose

    2007-06-01

    Accurate estimation of the maximum possible depth of scour at bridge abutments is important in decision-making for the safe depth of burial of footings. Besides, investigation of the geometric features of scour holes around abutments provides useful information for the degree of scour counter-measure to be implemented against excessive scouring. Experiments have been performed to investigate time-dependent characteristics of scour holes around vertical wall abutments under clear water conditions with uniform bed materials. Temporal variations of scour depth and scour contours were measured. Using this information, an empirical relation was developed for temporal variation of scour depth. Additional relations were also derived for time-dependent volume and surface area of the scour holes around abutments. The findings of this study may provide useful informatoin for preliminary design of abutment footings and placement details of armoring counter-measures, such as riprap.

  12. Implant adaptation of stock abutments versus CAD/CAM abutments: a radiographic and Scanning Electron Microscopy study

    Science.gov (United States)

    Apicella, Davide; Veltri, Mario; Chieffi, Nicoletta; Polimeni, Antonella; Giovannetti, Agostino; Ferrari, Marco

    2011-01-01

    Summary Introduction The study evaluated a null-hypothesis of no differences of fit between stock abutments and CAD/CAM titanium, gold sputtered and zirconia abutments when examined for radiographic adaptation and Scanning Electron Microcopy (SEM) at their inner aspect. The agreement between microscopic and radiographic fit was also assessed. Methods Implants (Osseospeed, Astra Tech, Mölndal, Sweden) were connected to titanium abutments (Ti-design, Astra Tech, Mölndal, Sweden) (control group n=12), to stock zirconia abutments (Zir-design, Astra Tech) (group 1 n=12) and to third party zirconia abutments (Aadva Zr abutment, GC, Tokyo, Japan) as observed under SEM (JEOL JSM-6060LV, Tokyo, Japan). Two independent operators blindly evaluated the images, according to a three-score scale: perfect adaptation, no complete adaptation, and clear evidence of no adaptation. A Kruskal-Wallis test was applied to assess significant differences in adaptation scores between the groups. Results All specimens showed precise SEM adaptation at all tested interfaces and no radiographically apparent gaps. No significant differences were found and therefore the null-hypothesis tested was accepted. Radiographic and SEM scores were in agreement. Discussion CAD/CAM titanium, gold sputtered and zirconia abutments and third-part CAD/CAM zirconia abutments show an adaptation to Astra Tech implants that is comparable to that of stock titanium and zirconia abutments. Clinicians might be able to verify such adaptation with an x-ray. In-vivo studies would be needed to evaluate the clinical outcome of CAD/CAM abutments. PMID:22238709

  13. Clinical evaluation of isolated abutment teeth in removable partial dentures

    Directory of Open Access Journals (Sweden)

    Zarrati S

    2011-02-01

    Full Text Available "nBackground and Aims: Nowadays, removable partial dentures are applied to patients who are not able to use dental implants or fixed prosthesis. Although based on the studies the users of removable partial dentures are in the risk of plaque accumulation and unacceptable changes such as gingivitis, periodontitis and mobility in abutment tooth. It is not clear whether the negative effects of removable partial dentures are more on the isolated teeth which are a kind of abutment adjacent to endentulous area in both sides. The purpose of this study was to investigate the clinical condition of isolated abutment teeth without splinting in comparison to control abutment from the aspects of B.O.P (bleeding on probing, mobility, pocket depth and gingivitis."nMaterials and Methods: In this cross-sectional study, the prepared questionnaires were filled out by 50 patients who received removable partial dentures in department of removable prosthodontics of dental school of Tehran University of Medical Sciences. The patients had isolated abutment tooth and did not have any systemic disease. The obtained data were analyzed. Using Wilcoxon, exact Fisher and Kruskal-Wallis test."nResults: B.O.P (P=0.004, pocket depth (P=0.035, and mobility (P<0.001 in isolated abutments were more than those in control abutments, but there were not significant differences in the degree of caries (P=0.083 and gingivitis (P=0.07."nConclusion: This study showed that clinical condition of isolated abutments is worse than that of control abutments. More attention should be paid to healthiness of isolated teeth without splinting and periodic follow ups should be done in these cases.

  14. Velocity and turbulence at a wing-wall abutment

    Indian Academy of Sciences (India)

    Abdul Karim Barbhuiya; Subhasish Dey

    2004-02-01

    Experimental investigation of the 3D turbulent flow field around a 45° wing-wall abutment, resting on a rough rigid bed, is reported. The experiment was conducted in a laboratory flume using the Acoustic Doppler Velocimeter (ADV). Profiles of time-averaged velocity components, turbulent intensity components, turbulent kinetic energy and Reynolds stresses at different azimuthal planes are presented. Vector plots of flow fields at azimuthal and horizontal planes show the presence of a primary vortex associated with the downflow in the upstream side of the abutment and a wake vortex on the downstream side. The shear stresses acting on the bed around the abutment are estimated from the Reynolds stresses and velocity gradients. The data presented in this study would be useful to researchers for future development and comparison of theoretical models of flow fields around bridge abutments.

  15. Distribution of lateral floor abutment pressure in a stope

    Institute of Scientific and Technical Information of China (English)

    Zhang Hualei; Wang Lianguo; Sun Jian

    2011-01-01

    In order to study the distribution of lateral floor abutment pressure at a working face, we first used elasticity theory to establish a distribution model of lateral floor abutment pressure and then analysed its distribution. Second, we established a three-dimensional numerical simulation model of the Haizi Coal Mine No. 86 mining area by using FLAC3D (ITASCA Consulting Group) software. We investigated the distribution of lateral floor abutment pressure of a stope, which indicated that the position of abutment pressure peak varies at different floor depths. We then determined the rational reinforcement range of a floor roadway, based on the conclusion reached earlier. Finally, we used our conclusions in support of the No. 86 mining area crossing-roadway. The supported crossing-roadway remained stable when mining the upper workface, which validates the accuracy of our numerical simulation and provides a future reference for the support of span-roadways under similar conditions.

  16. Mechanical testing of thin-walled zirconia abutments

    Directory of Open Access Journals (Sweden)

    Luigi CANULLO

    2013-01-01

    Full Text Available Although the use of zirconia abutments for implant-supported restorations has gained momentum with the increasing demand for esthetics, little informed design rationale has been developed to characterize their fatigue behavior under different clinical scenarios. However, to prevent the zirconia from fracturing, the use of a titanium connection in bi-component aesthetic abutments has been suggested. Objective Mechanical testing of customized thin-walled titanium-zirconia abutments at the connection with the implant was performed in order to characterize the fatigue behavior and the failure modes for straight and angled abutments. Material and Methods Twenty custom-made bi-component abutments were tested according to ISO 14801:2007 either at a straight or a 25° angle inclination (n=10 each group. Fatigue was conducted at 15 Hz for 5 million cycles in dry conditions at 20°C±5°C. Mean values and standard deviations were calculated for each group. All comparisons were performed by t-tests assuming unequal variances. The level of statistical significance was set at p≤0.05. Failed samples were inspected in a polarized-light and then in a scanning electron microscope. Results Straight and angled abutments mean maximum load was 296.7 N and 1,145 N, the dynamic loading mean Fmax was 237.4 N and 240.7 N, respectively. No significant differences resulted between the straight and angled bi-component abutments in both static (p=0.253 and dynamic testing (p=0.135. A significant difference in the bending moment required for fracture was detected between the groups (p=0.01. Fractures in the angled group occurred mainly at the point of load application, whereas in the straight abutments, fractures were located coronally and close to the thinly designed areas at the cervical region. Conclusion Angled or straight thin-walled zirconia abutments presented similar Fmax under fatigue testing despite the different bending moments required for fracture. The main

  17. Abutments influence in the dynamic response of bridges

    OpenAIRE

    Martínez Cutillas, Antonio; Gómez Lera, Sagrario; Alarcón Álvarez, Enrique

    1996-01-01

    A simplified analytical model of a short span bridge is proposed. The inertial interaction effects of pier foundations and abutments has been included in order to evaluate the response sensitivities to different soil-structure interaction variables. The modification of natural frequency and damping properties is shown for typical short span bridges of the integral deck-abutment type for longitudinal vibrations or general bridges for the transverse ones.

  18. Clinical evaluation of isolated abutment teeth in removable partial dentures

    OpenAIRE

    Zarrati S; Baheri Mghadam T; Nematollahi F

    2011-01-01

    "nBackground and Aims: Nowadays, removable partial dentures are applied to patients who are not able to use dental implants or fixed prosthesis. Although based on the studies the users of removable partial dentures are in the risk of plaque accumulation and unacceptable changes such as gingivitis, periodontitis and mobility in abutment tooth. It is not clear whether the negative effects of removable partial dentures are more on the isolated teeth which are a kind of abutment adjacent to ...

  19. VORTEX FLOW FIELD IN A SCOUR HOLE AROUND ABUTMENTS

    Institute of Scientific and Technical Information of China (English)

    Abdul Karim BARBHUIYA; Subhasish DEY

    2003-01-01

    The three-dimensional flow field in a scour hole around different abutments under a clear water regime was experimentally measured in a laboratory flume, using the Acoustic Doppler Velocimeter (ADV). Three types of abutments used in the experiments were vertical-wall (rectangular section), 45° wing-wall (45° polygonal section) and semicircular. The threedimensional time-averaged velocity components were detected at different vertical planes for vertical-wall abutment and azimuthal planes for wing-wall and semicircular abutments. The velocity components were also measured at different horizontal planes. In the upstream, presentations of flow field through vector plots at vertical / azimuthal and horizontal planes show the existence of a primary vortex associated with the downflow inside the scour hole. On the other hand, in the downstream, the flow field shows a reversed flow near the abutments having a subsequent recovery with a passage of flow as a part of the main flow. The data presented in this paper would be useful to the researchers for the development and verification of mathematical models of flow field in a scour hole at bridge abutments.

  20. Stress distribution among periodontally compromised abutments: A comparative study using three-dimensional finite element analysis

    Directory of Open Access Journals (Sweden)

    Rajkiran Chitumalla

    2012-01-01

    Full Text Available Aims: The aim of the study was to evaluate the stress distribution patterns in teeth and supporting structures of fixed prosthesis and design modifications in a fixed prosthesis with either normal or reduced bone support of an additional abutment. Study was also undertaken to disprove Ante′s law. Materials and Methods: Main models and variations of main models (modification 1, 2, 3, 4, 5, 6, 7, 8 were subjected to 200 N at angulations of 90° and 15° on functional cusps. Results for each loading were obtained as stress distribution color images and numerical values were recorded. A three-dimensional finite element analysis study of variations of normal models was performed using two finite element softwares, namely PRO-Engineer wildfire version 1.0 manufacturer: Parametric technology corporation, Needham, MA 02494 U.S.A. Results: When periodontal compromised abutment teeth was splinted with an additional abutment an increase of stress was observed in periodontally compromised abutments so an additional abutment is not required. Eventhough the pericemental area of compromised abutments with an additional abutment (canine was more than the combined pericemental area of pontics to be replaced, stress generated was more on abutments. This disproves Ante′s law. Hence, it may be a reference, but should not be the ultimate criterion in determining the number of multiple abutments. Conclusions: When periodontal compromised abutment teeth was splinted with an additional abutment an increase of stress was observed in periodontally compromised abutments so an additional abutment is not required. Even though the pericemental area of compromised abutments with an additional abutment (canine was more than combined pericemental area of pontics to be replaced, stress generated was more on abutments. This disproves Ante′s law. Hence, it may be a reference, but should not be the ultimate criterion in determining the number of multiple abutments.

  1. The applicability of PEEK-based abutment screws.

    Science.gov (United States)

    Schwitalla, Andreas Dominik; Abou-Emara, Mohamed; Zimmermann, Tycho; Spintig, Tobias; Beuer, Florian; Lackmann, Justus; Müller, Wolf-Dieter

    2016-10-01

    The high-performance polymer PEEK (poly-ether-ether-ketone) is more and more being used in the field of dentistry, mainly for removable and fixed prostheses. In cases of screw-retained implant-supported reconstructions of PEEK, an abutment screw made of PEEK might be advantageous over a conventional metal screw due to its similar elasticity. Also in case of abutment screw fracture, a screw of PEEK could be removed more easily. M1.6-abutment screws of four different PEEK compounds were subjected to tensile tests to set their maximum tensile strengths in relation to an equivalent stress of 186MPa, which is aused by a tightening torque of 15Ncm. Two screw types were manufactured via injection molding and contained 15% short carbon fibers (sCF-15) and 40% (sCF-40), respectively. Two screw types were manufactured via milling and contained 20% TiO2 powder (TiO2-20) and >50% parallel orientated, continuous carbon fibers (cCF-50). A conventional abutments screw of Ti6Al4V (Ti; CAMLOG(®) abutment screw, CAMLOG, Wimsheim, Germany) served as control. The maximum tensile strength was 76.08±5.50MPa for TiO2-20, 152.67±15.83MPa for sCF-15, 157.29±20.11MPa for sCF-40 and 191.69±36.33MPa for cCF-50. The maximum tensile strength of the Ti-screws amounted 1196.29±21.4MPa. The results of the TiO2-20 and the Ti screws were significantly different from the results of the other samples, respectively. For the manufacturing of PEEK abutment screws, PEEK reinforced by >50% continuous carbon fibers would be the material of choice. PMID:27434650

  2. [Interproximal tooth cleansing of abutment teeth and pontic design].

    Science.gov (United States)

    Kocher, T; Plagmann, H C; Engelsmann, U; Schlüter, R

    1990-03-01

    This clinical study was an attempt to find out if a patient's home care plaque control at his or her abutment tooth is more effectively enhanced by a modified ridge lap or a hygienic pontic design. Oral hygiene was performed either with a tooth brush alone or in combination with an interdental brush. We found that the effectivity of interproximal toothcleaning was not influenced by the pontic design and that only interdental brushes permit a good plaque control at the proximal area of the abutment tooth. This implies that "self cleansing" is non-existent in these tooth areas. PMID:2257819

  3. Replacing worn overdenture abutments of an unknown implant system by using laser welding: a clinical report.

    Science.gov (United States)

    Mohunta, Vrinda V; Stevenson, James A; Lee, Damian J

    2014-09-01

    This clinical report describes a procedure for replacing worn ball abutments with low-profile resilient abutments by using laser welding when the implant system for a mandibular implant-supported overdenture could not be identified. PMID:24836281

  4. Experimental and Analytical Investigations of Piles and Abutments of Integral Bridges

    OpenAIRE

    Arsoy, Sami

    2000-01-01

    Bridges without expansion joints are called "integral bridges." Eliminating joints from bridges crates concerns for the piles and the abutments of integral bridges because the abutments and the piles are subjected to temperature-induced cyclic lateral loads. As temperatures change daily and seasonally, the lengths of integral bridges increase and decrease, pushing the abutment against the approach fill and pulling it away. As a result the bridge superstructure, the abutment, the approach f...

  5. Acrylic resin guide for locating the abutment screw access channel of cement-retained implant prostheses.

    Science.gov (United States)

    Ahmed, Ayman; Maroulakos, Georgios; Garaicoa, Jorge

    2016-05-01

    Abutment screw loosening represents a common and challenging technical complication of cement-retained implant prostheses. This article describes the fabrication of a simple and accurate poly(methyl methacrylate) guide for identifying the location and angulation of the abutment screw access channel of a cement-retained implant prosthesis with a loosened abutment screw. PMID:26794698

  6. AN INTEGRATED APPROACH FOR SIMULATING AND PREDICTING SCOUR AROUND ABUTMENTS

    Institute of Scientific and Technical Information of China (English)

    L.Q.ZHANG; D.H.ZHAO; H.W.SHEN

    2006-01-01

    A new experimental and numerical approach to predict scour around abutments located either in the floodplain of a compound channel or in a rectangular channel was investigated. A prediction equation for the scour around abutments was proposed on the basis of the experimental study. A special horizontal two-dimensional (2D) numerical model was combined with the experimental studies. The 2D model is based on the principles of the finite volume method with Riemann solvers. The corrections to account for the impacts of the hydrostatic pressure assumption, turbulence, and three-dimensional behavior were embedded in the 2D model. The proposed prediction equation is based on both experimental and numerical techniques for estimation of scour depths in cases with different channel geometries and abutment lengths under various flow conditions. A comparison was done of the measured scour depths from the experiments and the calculated scour depths from the prediction equation. It was proved that the scour depths predicted with the proposed equation matched better with the measured values than another similar prediction equation.

  7. Glass fiber-reinforced abutments for dental implants. A pilot study.

    Science.gov (United States)

    Behr, M; Rosentritt, M; Lang, R; Handel, G

    2001-04-01

    Titanium abutments in dental implants shine through all-ceramic crowns and therefore limit excellent esthetic results. Prototypes of tooth-colored fiber-reinforced abutments were investigated to avoid the shining-through effect. In vitro, the fracture strength was determined after thermal cycling and mechanical loading of all-ceramic single crowns and four-unit bridges made of a fiber-reinforced composite. The suprastructures were adhesively fixed onto fiber-reinforced implant abutments and compared with those fixed on standard titanium abutments. The median of the fracture strength of the titanium-supported all-ceramic crowns was significantly higher than the median of crowns fixed onto the prototypes. But this value was still more than twice as high as the maximum loading force under oral conditions. No statistical difference was found between four-unit bridges made by fiber-reinforced composite inserted onto titanium abutments and those inserted onto fiber-reinforced abutments. Fiber-reinforced abutment prototypes for dental implants avoided the shining-through effect associated with metal abutments. Their load-bearing capacity after in vitro stress simulation was higher than the maximum oral loading force. With some improvements, the fiber-reinforced implant abutments are therefore a promising alternative to titanium abutments. PMID:11251668

  8. On the Performance of Super-Long Integral Abutment Bridges: Parametric Analyses and Design Optimization

    OpenAIRE

    Lan, Cheng

    2012-01-01

    The concept of "integral abutment bridge" has recently become a topic of remarka-ble interest among bridge engineers, not only for newly built bridges but also during refurbishment processes. The system constituted by the substructure and the superstructure can achieve a composite action responding as a single structural unit; the elimination of expansion joint and bearings on the abutments, greatly reduce the construction and maintenance costs. To maximize the benefits from integral abutment...

  9. Distribution of Side Abutment Stress in Roadway Subjected to Dynamic Pressure and Its Engineering Application

    OpenAIRE

    Yao Qiangling; Zhou Jian; Li Yanan; Tan Yingming; Jiang Zhigang

    2015-01-01

    The borehole stress-meter was employed in this study to investigate the distribution of the side abutment stress in roadway subjected to dynamic pressure. The results demonstrate that the side abutment stress of the mining roadway reaches a peak value when the distance to the gob is 8 m and the distribution curve of the side abutment stress can be divided into three zones: stress rising zone, stress stabilizing zone, and stress decreasing zone. Further numerical investigation was carried out ...

  10. Evaluation on Impact Interaction between Abutment and Steel Girder Subjected to Nonuniform Seismic Excitation

    OpenAIRE

    Yue Zheng; Xiang Xiao; Lunhai Zhi; Guobo Wang

    2015-01-01

    This paper aims to evaluate the impact interaction between the abutment and the girder subjected to nonuniform seismic excitation. An impact model based on tests is presented by taking material properties of the backfill of the abutment into consideration. The conditional simulation is performed to investigate the spatial variation of earthquake ground motions. A two-span continuous steel box girder bridge is taken as the example to analyze and assess the pounding interaction between the abut...

  11. Effect of Abutment Modification and Cement Type on Retention of Cement-Retained Implant Supported Crowns

    OpenAIRE

    Mitra Farzin; Kianoosh Torabi; Ahmad Hasan Ahangari; Reza Derafshi

    2014-01-01

    Objective: Provisional cements are commonly used to facilitate retrievability of cement-retained fixed implant restorations; but compromised abutment preparation may affect the retention of implant-retained crowns.The purpose of this study was to investigate the effect of abutment design and type of luting agent on the retentive strength of cement-retained implant restorations. Materials and Method: Two prefabricated abutments were attached to their corresponding analogs and embedded in an ac...

  12. Effect of abutment modification and cement type on retention of cement-retained implant supported crowns.

    Directory of Open Access Journals (Sweden)

    Mitra Farzin

    2014-06-01

    Full Text Available Provisional cements are commonly used to facilitate retrievability of cement-retained fixed implant restorations; but compromised abutment preparation may affect the retention of implant-retained crowns.The purpose of this study was to investigate the effect of abutment design and type of luting agent on the retentive strength of cement-retained implant restorations.Two prefabricated abutments were attached to their corresponding analogs and embedded in an acrylic resin block. The first abutment (control group was left intact without any modifications. The screw access channel for the first abutment was completely filled with composite resin. In the second abutment, (test group the axial wall was partially removed to form an abutment with 3 walls. Wax models were made by CAD/CAM. Ten cast copings were fabricated for each abutment. The prepared copings were cemented on the abutments by Temp Bond luting agent under standardized conditions (n=20. The assemblies were stored in 100% humidity for one day at 37°C prior to testing. The cast crown was removed from the abutment using an Instron machine, and the peak removal force was recorded. Coping/abutment specimens were cleaned after testing, and the testing procedure was repeated for Dycal luting agent (n=20. Data were analyzed with two- way ANOVA (α=0.05.There was no significant difference in the mean transformed retention (Ln-R between intact abutments (4.90±0.37 and the abutments with 3 walls (4.83±0.25 using Dycal luting agent. However, in TempBond group, the mean transformed retention (Ln-R was significantly lower in the intact abutment (3.9±0.23 compared to the abutment with 3 walls (4.13±0.33, P=0.027.The retention of cement-retained implant restoration can be improved by the type of temporary cement used. The retention of cast crowns cemented to implant abutments with TempBond is influenced by the wall removal.

  13. [Arthroscopic distal ulna resection after post traumatic ulno carpal abutment].

    Science.gov (United States)

    Mathoulin, C; Pagnotta, A

    2006-11-01

    Ulno carpal abutments secondary to the sequels of a fracture of the radius are often due to the inversion of the distal radio ulnar index by shortening relative to the radius. This positive ulnar variance eventually leads to an abutment between the head of the ulnar and the proximal articular face of the lunate with alteration of the cartilaginous carpal surfaces. The wrist arthroscopy makes diagnosis and treatment possible in a less invasive way. The patients are operated on as outpatients under local regional anaesthetic using a pneumatic tourniquet. The arthroscope is positioned using the 3-4 radio carpal opening permitting exploration of the joint. The surgical treatment is performed by arthroscopy using a burr and going in through the 6R radio carpal opening. In this way we use the technique of partial resection of the distal ulna. We have a series of 62 patients who have benefited from the technique of partial resection of the ulnar head by arthroscopy. There were 30 men and 32 women. The average age was 66 years old (between 45 and 82). Our average follow-up is 32 months (between 12 and 60 months). Recovery of mobility was immediate in all cases with persistent pain in the radio ulnar joint in 8 cases. Arthroscopic treatment of ulno carpal abutment has proved itself effective and innocuous. It should nevertheless be reserved for operations on small sized inversions of the distal radio ulnar index (less than 5 mm). In the event of larger ulnar variances we prefer ulnar shortening osteotomy. The other techniques will be restricted to cases where the distal radio ulnar joint has been impaired. PMID:17361890

  14. Study of displacements of a bridge abutment using FEM

    Directory of Open Access Journals (Sweden)

    Wymysłowski Michał

    2016-06-01

    Full Text Available Steel sheet piles are often used to support excavations for bridge foundations. When they are left in place in the permanent works, they have the potential to increase foundation bearing capacity and reduce displacements; but their presence is not usually taken into account in foundation design. In this article, the results of finite element analysis of a typical abutment foundation, with and without cover of sheet piles, are presented to demonstrate these effects. The structure described is located over the Więceminka river in the town of Kołobrzeg, Poland. It is a single-span road bridge with reinforced concrete slab.

  15. Effect of abutment modeling on the seismic response of bridge structures

    Institute of Scientific and Technical Information of China (English)

    Ady Aviram; Kevin R.Mackie; Bozidar Stojadinovic

    2008-01-01

    Abutment behavior significantly influences the seismic response of certain bridge structures.Specifically in the case of short bridges with relatively stiff superstructures typical of highway overpasses,embankment mobilization and inelastic behavior of the soil material under high shear deformation levels dominate the response of the bridge and its column bents.This paper investigates the sensitivity of bridge seismic response with respect to three different abutment modeling approaches.The abutment modeling approaches are based on three increasing levels of complexity that attempt to capture the critical components and modes of abutment response without the need to generate continuum models of the embankment,approach,and abutment foundations.Six existing reinforced concrete bridge structures,typical of Ordinary Bridges in California,are selected for the analysis.Nonlinear models of the bridges are developed in OpenSees.Three abutment model types of increasing complexity are developed for each bridge,denoted as roller,simplified,and spring abutments.The roller model contains only single-point constraints.The spring model contains discrete representations of backfill,bearing pad,shear key,and back wall behavior.The simplified model is a compromise between the efficient roller model and the comprehensive spring model.Modal,pushover,and nonlinear dynamic time history analyses are conducted for the six bridges using the three abutment models for each bridge.Comparisons of the analysis results show major differences in mode shapes and periods,ultimate base shear strength,as well as peak displacements of the column top obtained due to dynamic excitation.The adequacy of the three abutment models used in the study to realistically represent all major resistance mechanisms and components of the abutments,including an accurate estimation of their mass,stiffness,and nonlinear hysteretic behavior,is evaluated.Recommendations for abutment modeling are made.

  16. Simplified modelling of bridge abutments-soil interaction under seismic effects

    OpenAIRE

    Martínez Cutillas, Antonio; Alarcón Álvarez, Enrique

    1995-01-01

    A simplified model is proposed to show the importance that the dynamic soil-abutment interaction can have in the global behavior of bridges submitted to seismic loading. The modification of natural frequency and damping properties is shown in graphic form for typical short span bridges of the integral deck-abutment type for longitudinal vibrations or general ones for transverse vibrations.

  17. Fracture resistance of abutment screws made of titanium, polyetheretherketone, and carbon fiber-reinforced polyetheretherketone

    Directory of Open Access Journals (Sweden)

    Eduardo Aloisio Fleck NEUMANN

    2014-08-01

    Full Text Available Fractured abutment screws may be replaced; however, sometimes, the screw cannot be removed and the entire implant must be surgically removed and replaced. The aim of this study was to compare the fracture resistance of abutment retention screws made of titanium, polyetheretherketone (PEEK and 30% carbon fiber-reinforced PEEK, using an external hexagonal implant/UCLA-type abutment interface assembly. UCLA-type abutments were fixed to implants using titanium screws (Group 1, polyetheretherketone (PEEK screws (Group 2, and 30% carbon fiber-reinforced PEEK screws (Group 3. The assemblies were placed on a stainless steel holding apparatus to allow for loading at 45o off-axis, in a universal testing machine. A 200 N load (static load was applied at the central point of the abutment extremity, at a crosshead speed of 5 mm/minute, until failure. Data was analyzed by ANOVA and Tukey’s range test. The titanium screws had higher fracture resistance, compared with PEEK and 30% carbon fiber-reinforced PEEK screws (p 0.05. Finally, visual analysis of the fractions revealed that 100% of them occurred at the neck of the abutment screw, suggesting that this is the weakest point of this unit. PEEK abutment screws have lower fracture resistance, in comparison with titanium abutment screws.

  18. Effect of the number of abutments on biomechanics of Branemark prosthesis with straight and tilted distal implants

    Directory of Open Access Journals (Sweden)

    Marcos Michelon Naconecy

    2010-04-01

    Full Text Available OBJECTIVE: This study aimed to evaluate the bending moments, and compressive and tensile forces in implant-supported prostheses with three, four or five abutments. MATERIAL AND METHODS: Ten Pd-Ag frameworks were tested over two master models with: 1 parallel vertical implants, and 2 tilted distal implants. Strain gauges were fixed on the abutments of each master model to measure the deformation when a static load of 50 N was applied on the cantilever (15 mm. The deformation values were measured when the metallic frameworks were tested over three, four or five abutments, and transformed into force and bending moment values. Data were analyzed by ANOVA and Tukey's test for multiple comparisons at 5% level of significance. RESULTS: Abutment #1 (adjacent to the cantilever had the highest values of force and sagittal bending moment for all tests with three, four or five abutments. Independently from the number of abutments, axial force in abutment #1 was higher in the vertical model than in the tilted model. Total moment was higher with three abutments than with four or five abutments. Independently from the inclination of implants, the mean force with four or five abutments was lower than that with three abutments. CONCLUSION: The results suggest that in the set-ups with four or five abutments tilted distal implants reduced axial force and did not increase bending moments.

  19. Beam-edge modifier for abutting electron fields

    International Nuclear Information System (INIS)

    Abutment of unmodified electron fields to irradiate large areas can lead to significant dose inhomogeneities in the region of junction of the fields. In this paper we describe the design and dosimetric characteristics of a device developed to broaden the electron beam penumbra and thereby to improve the dose uniformity in the overlap region. The device is a high-density triangular-toothed comb capable of reducing the beam intensity without seriously degrading the beam energy. The effect of the comb is such that a single device will generate a beam penumbra which is broad and very nearly linear at all depths for all clinically used beam energies. Results are shown for various field configurations and energies. With a gap of 5.0 cm between the treatment cone and phantom surface the dose ''ripple'' in the region beneath the teeth was found not to exceed +- 5% at 0.5-cm depth

  20. Assessment of the NCHRP abutment scour prediction equations with laboratory and field data

    Science.gov (United States)

    Benedict, Stephen T.

    2014-01-01

    The U.S. Geological Survey, in coopeation with nthe National Cooperative Highway Research Program (NCHRP) is assessing the performance of several abutment-scour predcition equations developed in NCHRP Project 24-15(2) and NCHRP Project 24-20. To accomplish this assssment, 516 laboratory and 329 fiels measurements of abutment scor were complied from selected sources and applied tto the new equations. Results will be used to identify stregths, weaknesses, and limitations of the NCHRP abutment scour equations, providing practical insights for applying the equations. This paper presents some prelimiray findings from the investigation.

  1. A Simple Method for Making Diagnostic Casts for Dental Implants Using Acrylic Abutments

    Directory of Open Access Journals (Sweden)

    H. Siadat

    2007-06-01

    Full Text Available The use of multiple implants in the same jaw requires a detailed knowledge of abutment angulation. The position and angulation of the abutments play an important role in treatment planning and fabrication of the custom tray. Therefore diagnostic casts thatcontain cover screws may cause problems during implant therapy.The current article describes a technique for making a preliminary cast with acrylic custom abutments in order to help the clinician select an appropriate impression technique and evaluate the location and angulations of the implant bodies. This method can also aid the technician to provide adequate and proper space for the fabrication of an open custom tray.

  2. Non-rigid connector in fixed partial dentures with pier abutment: An enigma simplified

    Directory of Open Access Journals (Sweden)

    Prince Kumar

    2012-01-01

    Full Text Available In the fixed partial denture (FPD prosthesis with rigid connectors, forces of mastication are transmitted to the terminal retainers, which make the middle abutment act as a class I lever fulcrum. This techno-clinical cycle often causes failure of the fixed partial dentures. To overcome this dilemma, a non-rigid connector may be incorporated on the distal aspect of the middle (pier abutment. The non-rigid connector counterbalances the effects of these forces of leverage. This clinical report presents the use of a non-rigid connector in a long-span, five-unit FPD, replacing two missing teeth with an intermediate pier abutment.

  3. Torque Removal Evaluation of Screw in One-Piece and Two-Piece Abutments Tightened with a Handheld screwdriver

    Directory of Open Access Journals (Sweden)

    Jalil Ghanbarzadeh

    2013-12-01

    Full Text Available Introduction: Some clinicians use a handheld screw driver instead of a torque wrench to definitively tighten abutment screws. The aim of this study was to compare the removal torque of one-piece and two-piece abutments tightened with a handheld driver and a torque control ratchet. Methods: 40 ITI implants were placed in acrylic blocks and divided into 4 groups. In groups one and two, 10 ITI one-piece abutments (Solid® and in groups three and four, 10 ITI two-piece abutments (Synocta® were placed on the implants. In groups one and three abutments were tightened by 5 experienced males and 5 experienced females using a handheld driver. In groups two and four abutments were tightened using a torque wrench with torque values of 10, 20 and 35 N.cm. Insertion torque and removal torque values of the abutments were measured with a digital torque meter. Results: The insertion torque values (ITVs of males in both abutments were significantly higher than those of females. ITVs in both Solid® and Synocta® abutments tightened with a handheld screwdriver were similar to the torque of 20 N.cm in the torque wrench. Removal torque values (RTVs of solid® abutments were higher than those of synocta® abutments. Conclusion: The one- piece abutments (solid® showed higher RTVs than the two-piece abutments (synocta®. Hand driver does not produce sufficient preload force for the final tightening of the abutment

  4. Soil Structure Interaction for Integral Abutment Bridge Using Spring Analogy Approach

    International Nuclear Information System (INIS)

    The reaction of the backfill behind the abutments and adjacent to the piles plays a significant role in the behavior of the Integral bridge. The handling of soil-structure interaction in the analysis and design of integral abutment bridges has always been problematic due to its complexity. This study describes the implementation of a 2-D finite element model of IAB system which explicitly incorporates the soil response. The superstructure members and the pile have been represented by means of three-node isoperimetric beam elements with three degree of freedom per node. The Eight node isoperimetric quadrilateral element has been used to model the abutment. The backfill was idealized by uncoupled 'Winkler' spring. The applic1ability of this model is demonstrated by analyzing a single span IA bridge. The results have shown that the shear forces at the tops of the supported piles were only 12% to 16% of the load which at the top of abutment.

  5. Soil Structure Interaction for Integral Abutment Bridge Using Spring Analogy Approach

    Energy Technology Data Exchange (ETDEWEB)

    Thanoon, W A [Faculty Engineering, Nizwa University (Oman); Abdulrazeg, A A; Jaafar, M S; Kohnehpooshi, O [Department of Civil Engineering, University Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Noorzaei, J, E-mail: jamal@eng.upm.edu.my [Institute of Advance Technology, University Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2011-02-15

    The reaction of the backfill behind the abutments and adjacent to the piles plays a significant role in the behavior of the Integral bridge. The handling of soil-structure interaction in the analysis and design of integral abutment bridges has always been problematic due to its complexity. This study describes the implementation of a 2-D finite element model of IAB system which explicitly incorporates the soil response. The superstructure members and the pile have been represented by means of three-node isoperimetric beam elements with three degree of freedom per node. The Eight node isoperimetric quadrilateral element has been used to model the abutment. The backfill was idealized by uncoupled 'Winkler' spring. The applic1ability of this model is demonstrated by analyzing a single span IA bridge. The results have shown that the shear forces at the tops of the supported piles were only 12% to 16% of the load which at the top of abutment.

  6. Marginal Vertical Fit along the Implant-Abutment Interface: A Microscope Qualitative Analysis

    Directory of Open Access Journals (Sweden)

    Nicola Mobilio

    2016-09-01

    Full Text Available The aim of this study was to qualitatively evaluate the marginal vertical fit along two different implant-abutment interfaces: (1 a standard abutment on an implant and (2 a computer-aided-design/computer-aided-machine (CAD/CAM customized screw-retained crown on an implant. Four groups were compared: three customized screw-retained crowns with three different “tolerance” values (CAD-CAM 0, CAD-CAM +1, CAD-CAM −1 and a standard titanium abutment. Qualitative analysis was carried out using an optical microscope. Results showed a vertical gap significantly different from both CAD-CAM 0 and CAD-CAM −1, while no difference was found between standard abutment and CAD-CAM +1. The set tolerance in producing CAD/CAM screw-retained crowns plays a key role in the final fit.

  7. DEEP COLLIERY PRESSURE BUMPS AND ITS PREVENTIONS UNDER THE ACTION OF ABUTMENT PRESSURE

    Institute of Scientific and Technical Information of China (English)

    杜计平; 张先尘; 田昌栋; 闫培华

    1999-01-01

    Based on field measurement, the relations was introduced between mining depth and the peak value places of abutment pressures in long wall face of the deep colliery with caving method to handle goaf, and the reasons and kinds of pressure bumps are analysed under the action of the moving and constant abutment pressures formed by the method of long wall caving or room and pillar mining, and the relative precautions were put forward to prevent the pressure bumps in deep mining.

  8. The Influence of Post in Endodontically Treated Molar Abutment on Fixed Dentures Success Rate

    OpenAIRE

    Pralita Kusumawardhini; Alysia Henrietta; Saraventi Saraventi

    2013-01-01

    Many dentists believe that the tooth need reinforcement provided by post before the definite restoration is placed. However, others suggest not to use post when posterior teeth especially molars, still have significant amount of tooth structure. Therefore, when endodontically treated molar is considered to be used as fixed denture abut-ment, clinicians must have proper knowledge about the impact of post placement. This literature will describe considerations regarding post placement in endodo...

  9. Non-rigid connector in fixed partial dentures with pier abutment: An enigma simplified

    OpenAIRE

    Prince Kumar; Vishal Singh; Roshni Goel; Harkanwal P Singh

    2012-01-01

    In the fixed partial denture (FPD) prosthesis with rigid connectors, forces of mastication are transmitted to the terminal retainers, which make the middle abutment act as a class I lever fulcrum. This techno-clinical cycle often causes failure of the fixed partial dentures. To overcome this dilemma, a non-rigid connector may be incorporated on the distal aspect of the middle (pier) abutment. The non-rigid connector counterbalances the effects of these forces of leverage. This clinical report...

  10. A Retrospective Study of Implant–Abutment Connections on Crestal Bone Level

    OpenAIRE

    Lin, M.-I.; Shen, Y.-W.; Huang, H.-L.; Hsu, J.-T.; Fuh, L.-J.

    2013-01-01

    This study compared the effects of external hex, internal octagon, and internal Morse taper implant–abutment connections on the peri-implant bone level before and after the occlusal loading of dental implants. Periapical radiographs of 103 implants (63 patients) placed between 2002 and 2010 were collected, digitized, standardized, and classified into groups based on the type of implant–abutment connection. These radiographs were then analyzed with image-processing software to measure the peri...

  11. Local scour around bridge abutments under ice covered condition- an experimental study

    Institute of Scientific and Technical Information of China (English)

    Peng WU; Faye HIRSHFIELD; Jue-yi SUI

    2015-01-01

    The local scour around bridge abutments has been an active research topic for many decades. But very few studies have been conducted regarding the impacts of ice cover on the local scour phenomenon around bridge abutments. A series of ice covered flume experiments were conducted in this study. The shape factors of different abutment types in the local scour were compared. Under ice cover, the shape factor for semi-circular abutments ranges from 0.66~0.71. Three different non-uniform sediments were used withD50s of 0.58 mm, 0.50 mm, and 0.47 mm respectively. Two types of ice cover, namely smooth and rough cover, were created to simulate the impacts of ice cover around the abutments. Maximum scour depth was analyzed under different conditions. The contours of the scour holes were plotted to show the bed morphology and sediment deposition around bridge abutments. An empirical relationship between maximum scour depth, densimetric Froude number and sediment size was developed.

  12. Mechanical properties of alumina-zirconia composites for ceramic abutments

    Directory of Open Access Journals (Sweden)

    Maria Cecilia Corrêa de Sá e Benevides de Moraes

    2004-12-01

    Full Text Available The need for new materials to substitute injured or damaged parts of the human body has led scientists of different areas to investigate bioceramics since the 70's, when other materials in use started to show rejection problems. Ceramics show some advantages like being the material that best mimics the bone tissue, although present low toughness when compared with the metallic materials. As patients have become more and more demanding regarding esthetic and biocompatibility aspects of their dental restorations, ceramic material has become a main object of scientific interest especially from the material point of view. The alumina-zirconia composites are one of the relatively good and promising candidate for biomaterials application, due to biocompatibility and their mechanical properties that combines high flexural strength with a high toughness. The aim of the present work is to analyze the mechanical properties of these composites, where Y-TZP zirconia content was varied from 5 to 80 wt.% These systems can achieve a flexural strength 93 % and fracture toughness 29 % superior when compared to the pure alumina ceramics. These results showed that ceramic abutments components can be prepared for prosthetic rehabilitations with dental implants.

  13. Determination of Abutment Pressure in Coal Mines with Extremely Thick Alluvium Stratum: A Typical Kind of Rockburst Mines in China

    Science.gov (United States)

    Zhu, Sitao; Feng, Yu; Jiang, Fuxing

    2016-05-01

    This paper investigates the abutment pressure distribution in coal mines with extremely thick alluvium stratum (ETAS), which is a typical kind of mines encountering frequent intense rockbursts in China. This occurs due to poor understanding to abutment pressure distribution pattern and the consequent inappropriate mine design. In this study, a theoretical computational model of abutment pressure for ETAS longwall panels is proposed based on the analysis of load transfer mechanisms of key stratum (KS) and ETAS. The model was applied to determine the abutment pressure distribution of LW2302S in Xinjulong Coal Mine; the results of stress and microseismic monitoring verified the rationality of this model. The calculated abutment pressure of LW2302S was also used in the terminal mining line design of LW2301N for rockburst prevention, successfully protecting the main roadway from the adverse influence of the abutment pressure.

  14. Fatal complications after stereotactic body radiation therapy for central lung tumors abutting the proximal bronchial tree

    Science.gov (United States)

    Haseltine, Justin M.; Rimner, Andreas; Gelblum, Daphna Y.; Modh, Ankit; Rosenzweig, Kenneth E.; Jackson, Andrew; Yorke, Ellen D.; Wu, Abraham J.

    2016-01-01

    Purpose Stereotactic body radiation therapy (SBRT) is associated with excess toxicity following treatment of central lung tumors. Risk-adapted fractionation appears to have mitigated this risk, but it remains unclear whether SBRT is safe for all tumors within the central lung zone, especially those abutting the proximal bronchial tree (PBT). We investigated the dependence of toxicity on tumor proximity to PBT and whether tumors abutting the PBT had greater toxicity than other central lung tumors after SBRT. Materials and methods A total of 108 patients receiving SBRT for central lung tumors were reviewed. Patients were classified based on closest distance from tumor to PBT. Primary endpoint was SBRT-related death. Secondary endpoints were overall survival, local control, and grade 3+ pulmonary adverse events. We compared tumors abutting the PBT to nonabutting and those ≤1 cm and >1 cm from PBT. Results Median follow-up was 22.7 months. Median distance from tumor to PBT was 1.78 cm. Eighty-eight tumors were primary lung and 20 were recurrent or metastatic; 23% of tumors were adenocarcinoma and 71% squamous cell. Median age was 77.5 years. Median dose was 4500 cGy in 5 fractions prescribed to the 100% isodose line. Eighteen patients had tumors abutting the PBT, 4 of whom experienced SBRT-related death. No other patients experienced death attributed to SBRT. Risk of SBRT-related death was significantly higher for tumors abutting the PBT compared with nonabutting tumors (P 1cm from PBT (P = .014). Conclusions Even with risk-adapted fractionation, tumors abutting PBT are associated with a significant and differential risk of SBRT-related toxicity and death. SBRT should be used with particular caution in central-abutting tumors, especially in the context of anti-vascular endothelial growth factor therapy. PMID:26577006

  15. The Influence of Post in Endodontically Treated Molar Abutment on Fixed Dentures Success Rate

    Directory of Open Access Journals (Sweden)

    Pralita Kusumawardhini

    2013-05-01

    Full Text Available Many dentists believe that the tooth need reinforcement provided by post before the definite restoration is placed. However, others suggest not to use post when posterior teeth especially molars, still have significant amount of tooth structure. Therefore, when endodontically treated molar is considered to be used as fixed denture abut-ment, clinicians must have proper knowledge about the impact of post placement. This literature will describe considerations regarding post placement in endodontically treated molar abutment in fixed partial dentures and their influence to the success rate. Previous studies implied the need of proper measurement of the amount of remaining tooth structure, the type of intracoronal reinforcement of the abutment, and the functional loads to ensure the success of fixed denture treatment. When planning definitive restorations for endodontically treated abutment teeth, some even suggest to use post and core to fulfill the need of reinforcement. On the contrary, others find that when a post is use in endodontically treated abutment teeth, the failure of custom made-tapered cast post and core is relatively high, whereas the use of amalgam or composite core in posterior teeth especially molars with adequate amount of tooth structure is sufficient due to post system’s limited influence on the suc-cess rate. Based on literature review, for cases with adequate tooth stucture, it can be concluded that the influ-ence of post placement in endodontically treated molar abutment to fixed partial dentures success rate is very limited.DOI: 10.14693/jdi.v18i2.64

  16. A digital approach to fabricating an abutment replica to control cement volume in a cement-retained implant prosthesis.

    Science.gov (United States)

    Lee, Ju-Hyoung; Park, In-Sook; Sohn, Dong-Seok

    2016-07-01

    If a cement-retained implant prosthesis is placed on an abutment, excess cement should be minimized or removed to prevent periimplant inflammation. Various methods for fabricating an abutment replica have been introduced to maintain tissue health and reduce clean-up time. The purpose of this article is to present an alternative technique for fabricating an abutment replica with computer-aided design/computer-aided manufacturing (CAD/CAM) technology. PMID:26946917

  17. Radiologic Evaluation of Bone Loss at Implants with Biocide Coated Titanium Abutments: A Study in the Dog

    OpenAIRE

    López-Píriz, R.; Bartolomé, J. F.; Cabal, B.; Esteban-Tejeda, L.; Torrecillas, Ramón; J. S. Moya

    2012-01-01

    The objective of the present study is to evaluate bone loss at implant abutments coated with a soda-lime glass containing silver nanoparticles subjected to experimental peri-implantitis. Five beagle dogs were used in the experiments, 3 implants were installed in each quadrant of the mandibles. Glass/n-Ag coted abutments were connected to implant platform. Cotton floss ligatures were placed in a submarginal position around the abutment necks and the animals were subject to a diet which allowed...

  18. Reduction of Bridge Construction and Maintenance Costs through Coupled Geotechnical and Structural Design of Integral Abutment Bridges

    OpenAIRE

    Frosch, Robert J; Bobet, Antonio; Khasawneh, Yazen

    2014-01-01

    Elimination expansion joints in the superstructure of integral abutment bridges offers the advantage of reducing the initial and life cycle costs of the structure. However, such elimination may have an adverse effect on the displacement demand at the pile-abutment connection and on the earth pressures on the abutment wall due to the thermal expansion/contraction cycles of the bridge. These adverse effects have resulted in regulations that impose restrictions on the maximum length and skew ang...

  19. The Effect of Abutment Surface Roughness on the Retention of Implant-Supported Crowns Cemented with Provisional

    Directory of Open Access Journals (Sweden)

    Seyyed Mohammad Abrisham

    2012-09-01

    Full Text Available Introduction: Surface roughness can increase the retention of castings by ridges and grooves that are microretentive. This study compared the retention of implant-supported crowns when used with 3 different surface roughness abutments and one temporary cement. Methods: Thirty solid abutments (ITI, 4 mm high, were divided into three groups randomly. In the first group, 10 abutments were roughened with sandblast (50-µm aluminum oxide and in the second group, 10 abutments were roughened with diamond bur. The third group had no surface treatment. Then, thirty implant fixture analogs (ITI were placed in the center of acrylic cylinders. After that a solid abutment was tightened on the each fixture analog with 35 N/cm force. Thirty base metal crowns were made on the 4 mm ITI abutment analogs using plastic coping. The prepared copings were cemented on the abutments by TempBond temporary cement and finally, crowns were pulled from the abutment in a universal test machine at a cross speed of 0.5cm/min. Results: The mean tensile strength in sandblasted, bur treated, and control group were 64.38±8, 91.37±7.19, and 58.61±1.93, respectively. Bur treated group showed higher tensile strength in comparison with two other groups. Conclusion: Surface modification of implant abutment by diamond bur may be an effective method to increase retention of crown when TempBond is used.

  20. Evaluation of the marginal fit at implant-abutment interface by optical coherence tomography

    Science.gov (United States)

    Kikuchi, Keisuke; Akiba, Norihisa; Sadr, Alireza; Sumi, Yasunori; Tagami, Junji; Minakuchi, Shunsuke

    2014-05-01

    Vertical misfit of implant-abutment interface can affect the success of implant treatment; however, currently available modalities have limitations to detect these gaps. This study aimed to evaluate implant-abutment gaps in vitro using optical coherence tomography (OCT). Vertical misfit gaps sized 50, 100, 150, or 200 μm were created between external hexagonal implants and titanium abutments (Nobel Biocare, Göteborg, Sweden). A porcine gingival tissue slice, 0.5, 1.0, 1.5, or 2.0 mm in thickness, was placed on each implant-abutment interface. The gaps were evaluated by swept-source OCT at a center wavelength of 1330 nm (Panasonic Healthcare, Ehime, Japan) with beam angles of 90, 75 and 60 deg to the implant long-axis. The results suggested that while the measurements were precise, gap size and gingival thickness affected the sensitivity of detection. Gaps sized 100 μm and above could be detected with good accuracy under 0.5- or 1.0-mm-thick gingiva (GN). Around 70% of gaps sized 150 μm and above could be detected under 1.5-mm-thick GN. On the other hand, 80% of gaps under 2.0-mm-thick GN were not detected due to attenuation of near-infrared light through the soft tissue. OCT appeared as an effective tool for evaluating the misfit of implant-abutment under thin layers of soft tissue.

  1. Non-linear 3D evaluation of different oral implant-abutment connections.

    Science.gov (United States)

    Streckbein, P; Streckbein, R G; Wilbrand, J F; Malik, C Y; Schaaf, H; Howaldt, H P; Flach, M

    2012-12-01

    Micro-gaps and osseous overload in the implant-abutment connection are the most common causes of peri-implant bone resorption and implant failure. These undesirable events can be visualized on standardized three-dimensional finite element models and by radiographic methods. The present study investigated the influence of 7 available implant systems (Ankylos, Astra, Bego, Brånemark, Camlog, Straumann, and Xive) with different implant-abutment connections on bone overload and the appearance of micro-gaps in vitro. The individual geometries of the implants were transferred to three-dimensional finite element models. In a non-linear analysis considering the pre-loading of the occlusion screw, friction between the implant and abutment, the influence of the cone angle on bone strain, and the appearance of micro-gaps were determined. Increased bone strains were correlated with small (< 15°) cone angles. Conical implant-abutment connections efficiently avoided micro-gaps but had a negative effect on peri-implant bone strain. Bone strain was reduced in implants with greater wall thickness (Ankylos) or a smaller cone angle (Bego). The results of our in silico study provide a solid basis for the reduction of peri-implant bone strain and micro-gaps in the implant-abutment connection to improve long-term stability.

  2. A comparative radiographic evaluation of the titanium and zirconium implant-abutment gap of three different implant connections

    Directory of Open Access Journals (Sweden)

    Majid Sahebi

    2016-07-01

    Full Text Available Background and Aims: In response to esthetic demand and use of zirconia abutments; detection of implant-abutment connection misfit is so important. The purpose of this study was to evaluate the sensitivity and specificity of radiographic images in the detection of abutment-implant connection misfit in zirconia and titanium abutments of three different implant connections. Materials and Methods: One regular implant fixture of Branemark, Noble active and Replace systems were mount in acrylic models. Two pieces titanium and zirconium abutments were attached to the implants, once with correct adaptation and once with 0.5 mm spacer. Digital radiographic images were taken of 12 created states with zero degree vertical and horizontal inclination and evaluated by 10 specialists in implant treatment in two different time penods. Data were analyzed using Kappa analysis. Results: Interclass Correlation Coefficients (ICC of the agreement of answers in the first and second times were 97.4 and 97.5, respectively (P<0/001. Sensitivity of detecting gap in all groups was acceptable (95-100% except titanium abutment in Noble active which was the lowest value (35%. Specificity of all groups were acceptable (80-95% except zirconia abutments in Noble active and Replace with 45% and 30% values, respectively, and titanium abutments in Branemark had the highest value (95%. Conclusion: The sensitivity of radiographic images in detection of abutment-implant connection misfit only in Noble active with titanium abutment was not acceptable. Specificity of radiographic images in the absence of gap in titanium abutments was more favorable.

  3. Elasto-Viscoplastic Block Element Method and its Application to Arch Dam Abutment Slopes

    Science.gov (United States)

    Chen, S.-H.; Shahrour, I.; Egger, P.; Wang, W.-M.

    2002-08-01

    This paper presents an elasto-viscoplastic block element method and its application to the deformation and stability study of arch dam abutment slopes. The paper is composed of two parts. The first part concerns the numerical methods used in the analysis, which includes the identification of the rock blocky system, the algorithm of unconfined seepage flow in discontinuity network taking the grout curtain and drainage curtain into account, and the elasto-viscoplastic block element method as well. In the second part a complicated arch dam abutment slope is studied, from which the seepage flow, the deformation, and the safety factor of the abutment slope are obtained. Based on the analysis suggestions about the seepage control and stabilization measures are made.

  4. Mechanical behavior of single-layer ceramized zirconia abutments for dental implant prosthetic rehabilitation

    OpenAIRE

    Jiménez Melendo, Manuel; Llena Blasco, Oriol; Bruguera Alvarez, August; Llena Blasco, Jaime; Yáñez Vico, Rosa María; García Calderón, Manuel; Vaquero Aguilar, Cristina; Velázquez Cayón, Rocío; Gutiérrez Pérez, José Luis; Torres Lagares, Daniel

    2014-01-01

    Objectives: This study was undertaken to characterize the mechanical response of bare (as-received) and single-layer ceramized zirconia abutments with both internal and external connections that have been developed to enhanced aesthetic restorations. Material and Methods: Sixteen zirconia implant abutments (ZiReal Post®, Biomet 3i, USA) with internal and external connections have been analyzed. Half of the specimens were coated with a 0.5mm-thick layer of a low-fusing fluroapatite ceramic. Me...

  5. Sealing Capability and SEM Observation of the Implant-Abutment Interface

    Directory of Open Access Journals (Sweden)

    Fabio C. Lorenzoni

    2011-01-01

    water were collected at previously determinate times. The absorbance was measured with a spectrophotometer, and the data were analyzed by Two-way ANOVA (<.05 and Tukey's test. Marginal fit was determined using SEM. Leakage was observed for both groups at all times and was significantly higher at 144 hrs. SEM analysis depicted gaps in the implant-abutment interface of both groups. Gaps in the implant-abutment interface were observed along with leakage increased at the 144 hrs evaluation period.

  6. Resin-bonded cast splints for loosened abutment teeth to anchor a removable partial denture: a case report.

    Science.gov (United States)

    Shimizu, Hiroshi; Tsue, Fumitake; Takahashi, Yutaka

    2009-03-01

    This case report describes a technique to stabilize loosened abutment teeth by seating resin-bonded cast splints with rest seats and surveyed guide planes to anchor a removable partial denture. This technique can achieve sufficient stability of the abutment teeth and proper support and bracing of the removable partial denture with minimal intervention.

  7. Analysis of load distribution in tooth-implant supported fixed partial dentures by the use of resilient abutment

    Directory of Open Access Journals (Sweden)

    Glišić Mirko

    2016-01-01

    Full Text Available Introduction. Differences between the tooth and implant response to load can lead to many biological and technical implications in the conditions of occlusal forces. Objective. The objective of this study was to analyze load distribution in tooth/implant-supported fixed partial dentures with the use of resilient TSA (Titan Shock Absorber, BoneCare GmbH, Augsburg, Germany abutment and conventional non-resilient abutment using finite element method. Methods. This study presents two basic 3D models. For one model a standard non-resilient abutment is used, and on the implant of the second model a resilient TSA abutment is applied. The virtual model contains drawn contours of tooth, mucous membranes, implant, cortical bones and spongiosa, abutment and suprastructure. The experiment used 500 N of vertical force, applied in three different cases of axial load. Calculations of von Mises equivalent stresses of the tooth root and periodontium, implants and peri-implant tissue were made. Results. For the model to which a non-resilient abutment is applied, maximum stress values in all three cases are observed in the cortical part of the bone (maximum stress value of 49.7 MPa. Measurements of stress and deformation in the bone tissue in the model with application of the resilient TSA abutment demonstrated similar distribution; however, these values are many times lower than in the model with non-resilient TSA abutment (maximum stress value of 28.9 MPa. Conclusion. Application of the resilient TSA abutment results in more equal distribution of stress and deformations in the bone tissue under vertical forces. These values are many times lower than in the model with the non-resilient abutment.

  8. Long-term stability analysis of the left bank abutment slope at Jinping I hydropower station

    Directory of Open Access Journals (Sweden)

    Long Zhang

    2016-06-01

    Full Text Available The time-dependent behavior of the left bank abutment slope at Jinping I hydropower station has a major influence on the normal operation and long-term safety of the hydropower station. To solve this problem, a geomechanical model containing various faults and weak structural planes is established, and numerical simulation is conducted under normal water load condition using FLAC3D, incorporating creep model proposed based on thermodynamics with internal state variables theory. The creep deformations of the left bank abutment slope are obtained, and the changes of principal stresses and deformations of the dam body are analyzed. The long-term stability of the left bank abutment slope is evaluated according to the integral curves of energy dissipation rate in domain and its derivative with respect to time, and the non-equilibrium evolution rules and the characteristic time can also be determined using these curves. Numerical results show that the left bank abutment slope tends to be stable in a global sense, and the stress concentration is released. It is also indicated that more attention should be paid to some weak regions within the slope in the long-term deformation process.

  9. Long-term stability analysis of the left bank abutment slope at Jinping I hydropower station

    Institute of Scientific and Technical Information of China (English)

    Long Zhang; Qiang Yang; Yaoru Liu

    2016-01-01

    The time-dependent behavior of the left bank abutment slope at Jinping I hydropower station has a major influence on the normal operation and long-term safety of the hydropower station. To solve this problem, a geomechanical model containing various faults and weak structural planes is established, and numerical simulation is conducted under normal water load condition using FLAC3D, incorporating creep model proposed based on thermodynamics with internal state variables theory. The creep deformations of the left bank abutment slope are obtained, and the changes of principal stresses and deformations of the dam body are analyzed. The long-term stability of the left bank abutment slope is evaluated ac-cording to the integral curves of energy dissipation rate in domain and its derivative with respect to time, and the non-equilibrium evolution rules and the characteristic time can also be determined using these curves. Numerical results show that the left bank abutment slope tends to be stable in a global sense, and the stress concentration is released. It is also indicated that more attention should be paid to some weak regions within the slope in the long-term deformation process.

  10. Resisting momentum in the abutment to rotating of freight car bogie

    Directory of Open Access Journals (Sweden)

    Pavels GAVRILOVS

    2008-01-01

    Full Text Available On the Latvian railway, derailments of freight cars take place in the course of shunting work on marshalling yards. A number of factors during shunting work on marshalling yards may contribute to the derailments of rolling stock: longitudinal dynamics during braking of cars with the turned off brakes by locomotive, hauling down cars from a marshalling hill with braking position controlled by an operator, dry internal rails in curves, absence of greasing in the pivot unit of freight bogies. At present, measures allowing elimination of the car derailments during shunting work are developed.During the period between repairs, the abutment unit of freight car often works in conditions of dry friction. Our observations suggest that at the time of taking a car into repair, there is often an absence of greasing between trail bearing and center plate of the abutment, and a presence of sandy dust. It increases a friction and, together with high contact pressures and dynamic influence, hinders the turn of bogie at motion of car.In this paper, the results of studying the resisting moment in the abutment to turning of bogie is reported. The study was conducted on the basis of freight bogie of type 18-100; the body was leant on the center plate unit of the abutment, on the center plate unit, and on the sliders. Experiments were conducted, with the use of greasing and at the dry friction of center plate unit.

  11. Formation and evolution of gas flow channels in the abutment pressure area

    Institute of Scientific and Technical Information of China (English)

    Zhang Yong; Zhang Xibin; Xu Lifeng; Zhang Jiangli; Zhou Genli

    2012-01-01

    The permeability of coal ahead of the working face obviously changes dues to changes in abutment pressure.The formation and evolution of gas flow channels within the abutment pressure area was studied by analyzing the fracture extension mechanism and fracture development in different zones of the abutment pressure area.Fracture and damage mechanics theory is used to understand the observations.The following two techniques were used to understand the evolution of gas flow channels:field observation of the characteristic fractures at different positions relative to the working face and fluorescence micrographs of prepared coal samples.Bending tensile fractures develop along an approximately vertical direction that forms a microscopic network of channels in areas of stress concentration.The abutment pressure affects the local stress and,hence,the local gas conduction.The fractures induced by large deformation and plastic flow form macroscopically networked channels in the reduced stress area.Closer to the working face the gas flow channels evolve from microscopic to macroscopic and from isolated to network.Gas permeability continuously increases during this time.This is corroborated by field observations of the displacement of top coal and the gas flow from gas extraction drillings.

  12. Evaluation on Impact Interaction between Abutment and Steel Girder Subjected to Nonuniform Seismic Excitation

    Directory of Open Access Journals (Sweden)

    Yue Zheng

    2015-01-01

    Full Text Available This paper aims to evaluate the impact interaction between the abutment and the girder subjected to nonuniform seismic excitation. An impact model based on tests is presented by taking material properties of the backfill of the abutment into consideration. The conditional simulation is performed to investigate the spatial variation of earthquake ground motions. A two-span continuous steel box girder bridge is taken as the example to analyze and assess the pounding interaction between the abutment and the girder. The detailed nonlinear finite element (FE model is established and the steel girder and the reinforced concrete piers are modeled by nonlinear fiber elements. The pounding element of the abutment is simulated by using a trilinear compression gap element. The elastic-perfectly plastic element is used to model the nonlinear rubber bearings. The comparisons of the pounding forces, the shear forces of the nonlinear bearings, the moments of reinforced concrete piers, and the axial pounding stresses of the steel girder are studied. The made observations indicate that the nonuniform excitation for multisupport bridge is imperative in the analysis and evaluation of the pounding effects of the bridges.

  13. Relevance between abutment pressure and fractal dimension of crack network induced by mining

    Institute of Scientific and Technical Information of China (English)

    Gao Mingzhong; Jin Wencheng; Dai Zhixu; Xie Jing

    2013-01-01

    Based on the geological conditions of coal mining face No. 15-14120 at No. 8 mine of Pingdingshan coal mining group, the real-time evolution of coal-roof crack network with working face advancing was collected with the help of intrinsically safe borehole video instrument. And according to the geology of this working face, a discrete element model was calculated by UDEC. Combining in situ experimental data with numerical results, the relationship between the fractal dimension of boreholes’ wall and the distri-bution of advanced abutment pressure was studied under the condition of mining advance. The results show that the variation tendency of fractal dimension and the abutment pressure has the same charac-teristic value. The distance between working face and the peak value of the abutment pressure has a slight increasing trend with the advancing of mining-face. When the working face is set as the original point, the trend of fractal dimension from the far place to the origin can be divided into three phases:constant, steady increasing and constant. And the turning points of these phases are the max-influencing distance (50 m) and peak value (15 m) of abutment pressure.

  14. Distribution of Side Abutment Stress in Roadway Subjected to Dynamic Pressure and Its Engineering Application

    Directory of Open Access Journals (Sweden)

    Yao Qiangling

    2015-01-01

    Full Text Available The borehole stress-meter was employed in this study to investigate the distribution of the side abutment stress in roadway subjected to dynamic pressure. The results demonstrate that the side abutment stress of the mining roadway reaches a peak value when the distance to the gob is 8 m and the distribution curve of the side abutment stress can be divided into three zones: stress rising zone, stress stabilizing zone, and stress decreasing zone. Further numerical investigation was carried out to study the effect of the coal mass strength, coal seam depth, immediate roof strength, and thickness on the distribution of the side abutment stress. Based on the research results, we determined the reasonable position of the mining roadway and the optimal width of the barrier pillar. The engineering application demonstrates that the retention of the barrier pillar with a width of 5 m along the gob as the haulage roadway for the next panel is feasible, which delivers favorable technological and economic benefits.

  15. The effect of mucosal cuff shrinkage around dental implants during healing abutment replacement.

    Science.gov (United States)

    Nissan, J; Zenziper, E; Rosner, O; Kolerman, R; Chaushu, L; Chaushu, G

    2015-10-01

    Soft tissue shrinkage during the course of restoring dental implants may result in biological and prosthodontic difficulties. This study was conducted to measure the continuous shrinkage of the mucosal cuff around dental implants following the removal of the healing abutment up to 60 s. Individuals treated with implant-supported fixed partial dentures were included. Implant data--location, type, length, diameter and healing abutments' dimensions--were recorded. Mucosal cuff shrinkage, following removal of the healing abutments, was measured in bucco-lingual direction at four time points--immediately after 20, 40 and 60 s. anova was used to for statistical analysis. Eighty-seven patients (49 women and 38 men) with a total of 311 implants were evaluated (120 maxilla; 191 mandible; 291 posterior segments; 20 anterior segments). Two-hundred and five (66%) implants displayed thick and 106 (34%) thin gingival biotype. Time was the sole statistically significant parameter affecting mucosal cuff shrinkage around dental implants (P < 0.001). From time 0 to 20, 40 and 60 s, the mean diameter changed from 4.1 to 4.07, 3.4 and 2.81 mm, respectively. The shrinkage was 1%, 17% and 31%, respectively. The gingival biotype had no statistically significant influence on mucosal cuff shrinkage (P = 0.672). Time required replacing a healing abutment with a prosthetic element should be minimised (up to 20/40 s), to avoid pain, discomfort and misfit. PMID:26132112

  16. Cancer of Oral Cavity Abutting the Mandible; Predictors of Loco-regional Failure

    International Nuclear Information System (INIS)

    The purpose of this study is to analyze the causes of Loco-regional failure in 51 patients with tumors of the oral cavity abutting the mandible. Patients and Methods: This cross-sectional study (27 patients were operated upon in the retrospective section and 24 patients in the prospective section of the study) was done in the department of Surgical Oncology, National Cancer Institute, Cairo University, from January 2003 to January 2008. Fifty-one patients, with oral cavity cancerous lesions abutting the mandible, were operated upon by segmental mandibulectomy en-bloc with primary tumor resection in addition to modified radical or selective neck dissection according to the status of the cervical lymph nodes. Results: During a median follow-up of 2 years, 29 patients (56.8%) had local recurrences, the incidence of nodal recurrence after neck dissection was detected in 4 patients (7.8%). On multivariate analysis, tumor depth, tumor grade, oral mucosa, soft tissue and bone surgical margins in addition to metastatic lymphadenopathy were independent prognostic factors of loco-regional failure and disease-free survival. Conclusion: Oral cavity cancers abutting the mandible should be treated with great caution by a multidisciplinary oncology team (resection and reconstruction surgeons) as it has a very aggressive biologic behavior. Negative intraoperative pathological margins should be attempted since this is the critical point for patients with cancers abutting the mandible? Further research on the biologic margin and genetic study is required

  17. Live-bed scour experiments with 45° wing-wall abutments

    Indian Academy of Sciences (India)

    M H Mazumder; A K Barbhuiya

    2014-10-01

    Live bed scour experiments were conducted using four types of noncohesive bed sediments with median diameters d50 = 0.26 mm, 0.42 mm, 1.06 mm and 1.92 mm and five 45° wing-wall abutments of lengths l = 0.04 m, 0.06 m, 0.08 m, 0.10 m and 0.12 m. The tests were conducted in the range of flow velocity varies from 0.71 to 5 times of the critical velocity. The plotting of non-dimensional scour depths (scour depths/abutment lengths) vs non-dimensional flow intensity (flow intensity/critical velocity) show one peak value of scour depth close to the threshold velocity and thereafter, it reduces and again attain a live-bed maximum in the range of flow intensity 3 to 5 times of the critical velocity. It is also observed that the scour depth increases with the increase in sediment sizes up to threshold value of flow for all sediment sizes and abutment lengths. Further, the scour depth decreases with the increase of non-uniformity under all flow conditions. A design equation is proposed for estimating maximum scour depth at 45°wing-wall abutment under live-bed condition. The calculated values of scour depths using proposed equation, and also with three different live-bed local scour equations, are compared with the measured values of scour depths.

  18. Percutaneous Radiofrequency Ablation for the Hepatocellular Carcinoma Abutting the Diaphragm: Assessment of Safety and Therapeutic Efficacy

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Tae Wook; Rhim, Hyun Chul; Kim, Eun Young; Kim, Young Sun; Choi, Dong Il; Lee, Won Jae; Lim, Hyo K. [Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2009-02-15

    To assess the safety and therapeutic efficacy of a percutaneous radiofrequency (RF) ablation for the hepatocellular carcinoma (HCC) abutting the diaphragm. We retrospectively assessed 80 patients who underwent a percutaneous RF ablation for a single nodular (< 4 cm) HCC over the last four years. Each patient underwent an ultrasound-guided RF ablation using internally cooled electrodes for the first-line treatment. We divided patients into two subgroups based on whether the index tumor was abutting (less than 5 mm) the diaphragm or not: group A (abutting; n = 31) versus group B (non-abutting; n = 49). We compared the two subgroups for complications and therapeutic efficacy using image and the review of medical records. The statistical assessment included an independent t-test, Fisher's exact test, and chi-square test. The assessment of the diaphragmatic swelling at CT immediately following the procedure was more severe in group A than group B (mean thickness change:1.44 vs. 0.46 mm, p = 0.00). Further, right shoulder pain was more common in group A than B (p = 0.01). Although minor complications (hemothorax 1 case, pleural effusion 1 case) were noted only in group A, no major thoracic complication occurred in either group. The technical success rate was lower in group A than group B (84% vs. 98%, p = 0.03). As well, the primary and secondary technique effectiveness rates in group A and group B were 90% versus 98% (p = 0.29) and 79% versus 91% (p = 0.25), respectively. The local tumor progression rate was higher in group A than in group B (29% vs. 6%, p = 0.02). We found that the percutaneous RF ablation for the HCC abutting the diaphragm is a safe procedure without major complications. However, it is less effective with regard to technical success and local tumor control.

  19. Analytical solutions of hard roof’s bending moment, deflection and energy under the front abutment pressure before periodic weighting

    Institute of Scientific and Technical Information of China (English)

    Jiang Haijun; Cao Shenggen; Zhang Yun; Wang Chen

    2016-01-01

    The distribution of front abutment pressure is closely related to the force, deformation and energy distri-bution of hard roof before periodic weighting. So it is necessary to carry out research on the relationship between them. According to front abutment pressure distribution feature, using the location of peak front abutment pressure as the dividing point, coal seam is divided into two parts along the direction of min-ing:the yield zone that is the area between the faceline and the point where the maximum front abut-ment pressure occurs, and the elastic zone that is the part before the point of peak front abutment pressure. The proposed mechanical model of unit width hard roof at the panel center before periodic weighting consists of five parts including the yield zone. All parameters of the deflection equations for each of the five parts that satisfy the continuity conditions and natural boundary conditions are obtained by using the Matlab software. The continuous curves of front abutment pressure, deflection, bending moment and bending strain energy density distribution of hard roof are obtained by iterative approxima-tion method, and the relationship between the yield zone width and the above curves are analyzed in detailed.

  20. Hasarlı Çene Kemiklerinde Abutment Boyunun Dental İmplant Sistemi Üzerindeki Etkileri

    Directory of Open Access Journals (Sweden)

    Sinan KÖSE

    2015-01-01

    Full Text Available The purpose of this study is to investigate the stresses occurred onhard and soft bones after recovering the deficiency caused by totally edentulousand damaged mandible by using abutments with different lengths andprosthesis filling material. Two different damaged parts of 2.5 and 4.5 mm indepth were created with the aid of Solidworks program on the right hand sideof the mandible. Implants were then applied between the foremen channels.Later, the damaged models were recovered by abutment with different lengthsas for the first method. Two models using abutment were, therefore, obtainedfor the damaged parts of 2.5 and 4.5 mm in depth. In the second method, for thesame damaged cases, prosthesis filling material was used to recover deficiencykeeping the abutment length constant. Finally, there were totally obtained 4different damaged models of two fixed with abutment and two fixed with fillingmaterial and 1 undamaged model. At the second step of this study, the stressvalues were obtained on lower jaw bones by using finite element method underthe maximum chewing force and compared to each other. The results showedthat stress data obtained particularly on the soft and hard bones weredistributed more uniformly on the damaged models fixed with prosthesis fillingmaterial compared to the damaged models recovered by abutment. Moreover,the stress values obtained for models fixed with different abutment length wererather high in comparison to those of the filling material application

  1. The use of CAD/CAM technology to fabricate a custom ceramic implant abutment: a clinical report.

    Science.gov (United States)

    Bertolini, Martinna de Mendonça e; Kempen, Juan; Lourenço, Eduardo José Veras; Telles, Daniel de Moraes

    2014-05-01

    Well-placed dental implants are a prerequisite of functional and esthetically successful dental implant-supported crowns. The presence of soft tissue is essential for excellent esthetics because the dental implant or titanium abutment may become visible if the soft-tissue contour is not acceptable. This clinical report describes the use of a custom ceramic implant abutment designed with computer-aided design and computer-aided manufacturing (CAD/CAM) technology by milling a zirconia framework that was cemented extraorally to a prefabricated titanium abutment with a reduced diameter. This ceramic abutment has the strength and precise fit of a titanium interface and also the esthetic advantages of shaded custom-milled zirconia, with no visible metal. PMID:24433839

  2. Evaluation of fracture resistance of indirect composite resin crowns by cyclic impact test: influence of crown and abutment materials.

    Science.gov (United States)

    Sakoguchi, Kenji; Minami, Hiroyuki; Suzuki, Shiro; Tanaka, Takuo

    2013-01-01

    This study evaluated the effect of abutment materials on the fracture resistance of composite crowns for premolars. Composite crowns were fabricated using two different indirect composite resin materials (Meta Color Prime Art or Estenia C&B) and cemented onto either a metal (Castwell M.C. 12) or composite resin (Build-It FR and FibreKor) abutment with resin cement (Panavia F2.0). Twenty-four specimens were fabricated for four groups (n=6 each) and subjected to 280-N cyclic impact loading at 1.0 Hz. The number of cycles which caused the composite crown to fracture was defined as its fracture resistance. All data were statistically analyzed using ANOVA and the Bonferroni test (α=0.05). Composite crowns cemented onto resin abutments showed higher fracture resistance than those cemented onto metal abutments.

  3. Esthetic Considerations for Reconstructing Implant Emergence Profile Using Titanium and Zirconia Custom Implant Abutments: Fifty Case Series Report.

    Science.gov (United States)

    Kutkut, Ahmad; Abu-Hammad, Osama; Mitchell, Richard

    2015-10-01

    Titanium and zirconia custom implant abutments are now commonly used for esthetic implant dentistry. Custom implant abutments allow the clinician to improve an implant's emergence profile, to customize cervical margins in accordance with the anatomy of the natural root, and to compensate for poor implant angulation. All of these are essential for optimum esthetic outcomes. Computer-aided design/computer-aided machining (CAD/CAM) technology allows the clinician to design custom implant abutment configurations and create natural-looking superstructures that are in harmony with the adjacent dentition and soft tissue. The CAD/CAM technique provides precise fit, reduces the cost of the procedure, and eliminates dimensional inaccuracies inherent in the conventional waxing and casting technique. The aim of this report is to describe a simplified technique for reconstructing emergence profiles during implant restoration using milled titanium and zirconia custom implant abutments. The results of 50 consecutive cases are reported. PMID:24175922

  4. Abutment-Supported Papilla: A Combined Surgical and Prosthetic Approach to Papilla Reformation.

    Science.gov (United States)

    Urban, Istvan A; Klokkevold, Perry R; Takei, Henry H

    2016-01-01

    Restoration of lost interdental papilla remains one of the most challenging goals for clinicians. When a single tooth is replaced with an implant, the papilla between the tooth and the implant can often be maintained or predictably reconstructed as long as the periodontal attachment and bone of the adjacent tooth is preserved. However, if the periodontal support is compromised on the neighboring natural tooth, the papilla will often be deficient or missing. This article presents a multidisciplinary treatment approach to regenerate the interdental papilla between an implant and a periodontally compromised tooth using surgical procedures and a customized abutment. Specifically, an abutment with modified subgingival contours is used to enhance support of the surgically reformed papilla. PMID:27560670

  5. Fabricating abutment crowns for existing removable partial dentures using custom resin clasp analogs.

    Science.gov (United States)

    Livaditis, G J

    1998-11-01

    A universal approach for fabricating abutment crowns for existing removable partial dentures is described. A replica (analog) of the clasp assembly is generated and transferred to a traditional working cast, which includes the abutment die. The analog is incorporated into the working cast as a removable component to allow the formation of the crown contours. The article reviews in detail the procedures required to transfer accurately all the essential components and information from the mouth to the working cast while allowing the patient uninterrupted use of the removable partial denture. Prestabilizing the removable partial denture, creating the analog impression, avoiding errors due to soft tissue components, forming a precise analog base, selecting materials, generating a rigid resin analog, and prescribing a path of insertion and withdrawal to the analog are described. The method replicates all types of clasps and can generate all types of fixed prosthodontic retainers to function harmoniously with the existing partial denture.

  6. Fabricating abutment crowns for existing removable partial dentures using custom resin clasp analogs.

    Science.gov (United States)

    Livaditis, G J

    1998-11-01

    A universal approach for fabricating abutment crowns for existing removable partial dentures is described. A replica (analog) of the clasp assembly is generated and transferred to a traditional working cast, which includes the abutment die. The analog is incorporated into the working cast as a removable component to allow the formation of the crown contours. The article reviews in detail the procedures required to transfer accurately all the essential components and information from the mouth to the working cast while allowing the patient uninterrupted use of the removable partial denture. Prestabilizing the removable partial denture, creating the analog impression, avoiding errors due to soft tissue components, forming a precise analog base, selecting materials, generating a rigid resin analog, and prescribing a path of insertion and withdrawal to the analog are described. The method replicates all types of clasps and can generate all types of fixed prosthodontic retainers to function harmoniously with the existing partial denture. PMID:9813815

  7. Effect of the number of abutments on biomechanics of Branemark prosthesis with straight and tilted distal implants

    OpenAIRE

    Marcos Michelon Naconecy; Tomás Geremia; André Cervieri; Eduardo Rolim Teixeira; Rosemary Sadami Shinkai

    2010-01-01

    OBJECTIVE: This study aimed to evaluate the bending moments, and compressive and tensile forces in implant-supported prostheses with three, four or five abutments. MATERIAL AND METHODS: Ten Pd-Ag frameworks were tested over two master models with: 1) parallel vertical implants, and 2) tilted distal implants. Strain gauges were fixed on the abutments of each master model to measure the deformation when a static load of 50 N was applied on the cantilever (15 mm). The deformation values were mea...

  8. Transpulmonary computed tomography-guided radiofrequency ablation of liver neoplasms abutting the diaphragm with multiple bipolar electrodes

    OpenAIRE

    Q. Zhang; Li, X; Pan, J.; Z. Wang

    2015-01-01

    Background: Neoplasm abutting the diaphragm is one kind of the special sites of liver neoplasms treated with radiofrequency ablation (RFA), the purpose of this study is to evaluate the feasibility and safety of computed tomography (CT)-guided RFA of liver neoplasms abutting the diaphragm with multiple bipolar electrodes sequentially passing through the lung parenchyma. Materials and Methods: 37 patients were treated with transpulmonary CT-guided RFA. Technical success rate, perioperative comp...

  9. The effect of resin cements and primer on retentive force of zirconia copings bonded to zirconia abutments with insufficient retention

    OpenAIRE

    Kim, Seung-Mi; Yoon, Ji-Young; Lee, Myung-Hyun; Oh, Nam-Sik

    2013-01-01

    PURPOSE The purpose of this study was to investigate the effect of resin cements and primer on the retentive force of zirconia copings bonded to zirconia abutments with insufficient retention. MATERIALS AND METHODS Zirconia blocks (Lava, 3M ESPE, St. Paul, MN, USA) were obtained and forty sets of zirconia abutments and copings were fabricated using CAD/CAM technology. They were grouped into 4 categories as follows, depending on the types of resin cements used, and whether the primer is applie...

  10. LATE RESULTS OF PATIENTS’ ORTHOPEDIC TREATMENT USING FIXED PARTIAL DENTURES, DEPENDING ON THE FUNCTIONAL STATE OF THE ABUTMENT TEETH

    OpenAIRE

    Ozhogan, Z. R.; Klymyuk, Y. V.

    2015-01-01

    Treatment of partial adentia involves preparation of abutment teeth, followed by the production of fixed partial dentures. However, the abutment tooth vitality should be taken into account and the periodontal reserve power should be considered to prevent functional overload. The hygienic condition of the oral cavity is also necessary to be monitored during treatment and at different times after it.Using clinical indices data, the preservation of vital teeth was found to be a more reliable cri...

  11. Biomechanical Analysis of Tapered Integrated Screw and Sensitivity Analysis on Abutment Loosening in Dental Implants

    OpenAIRE

    Milad Farzadi; Mohammadreza Mallakzadeh

    2013-01-01

    Background and Aims: Different mechanisms have been developed for connecting abutment to implant. One of the most popular mechanisms is Tapered Integrated Screw (TIS), which is a Tapered Interference Fit (TIF) with a screw integrated at the bottom of that. The aim of this study was to investigate the mechanism of TIS and effective factors in employing TIS during design and implementation processes using an analytic method.Materials and Methods: Relevant equations were developed to predict tig...

  12. Correction of Malpositioned Implants through Periodontal Surgery and Prosthetic Rehabilitation Using Angled Abutment

    Directory of Open Access Journals (Sweden)

    Érica Dorigatti de Avila

    2014-01-01

    Full Text Available When dental implants are malpositioned in relation to the adjacent teeth and alveolar bone or in an excessive buccal or lingual position, the final prosthesis rehabilitation impairs the peri-implant health of the gingival tissues and the aesthetics of the patient. Thus, the purpose of this case was to report and discuss a multidisciplinary protocol for the treatment of a compromised maxillary tooth in a patient with an abscess in his right central incisor due to an excessive buccal implant position. The patient presented with an implant-supported provisional restoration on his right maxillary central incisor and a traumatic injury in his left central incisor. The treatment protocol consisted in (i abutment substitution to compensate the incorrect angulation of the implant, (ii clinical crown lengthening, (iii atraumatic extraction of the left central incisor, and (iv immediate implant placement. Finally, (v a custom abutment was fabricated to obtain a harmonious gingival contour around the prosthetic crown. In conclusion, when implants are incorrectly positioned in relation to the adjacent teeth, associated with soft-tissue defects, the challenge to create a harmonious mucogingival contours may be achieved with an interdisciplinary approach and with the placement of an appropriate custom abutment.

  13. Accuracy of different abutment level impression techniques in All-On-4 dental implants

    Directory of Open Access Journals (Sweden)

    Marzieh Alikhasi

    2012-01-01

    Full Text Available Background and Aims: Passive fit of prosthetic frameworks is a major concern in implant dentistry. Impression technique is one of the several variables that may affect the outcome of dental implants. The purpose of this study was to compare the three dimensional accuracy of direct and indirect abutment level implant impressions ofALL-ON-4 treatment plan.Materials and Methods: A reference acrylic resin model with four Branemark fixtures was made according to All-On-4 treatment plan. Multiunit abutments were screwed into the fixtures and two special trays were made for direct and indirect impression techniques. Ten direct and ten indirect impression techniques with respective impression transfers were made. Impressions were poured with stone and the positional accuracy of the abutment analogues in each dimension of x, y, and z axes and also angular displacement (Δθ were evaluated using a Coordinate Measuring Machine (CMM. Data were analyzed using T- test.Results: The results showed that direct impression technique was significantly more accurate than indirect technique (P<0.001.Conclusion: The results showed that the accuracy of direct impression technique was significantly more than that of indirect technique in Δθ and Δr coordinate and also Δx, Δy, Δz.

  14. 重载铁路桥台设计%Abutment Design of Heavy Haul Railway

    Institute of Scientific and Technical Information of China (English)

    严章荣

    2012-01-01

    针对山西中南部铁路通道采用的30 t轴重荷载,分析目前国内外重栽铁路的发展特点,拟定桥台的设计标准、设计荷载以及荷载检算模式,通过对台身偏心及应力检算,确定了空心桥台的结构尺寸.设计的矩形空心桥台台长随填土高增加而增加,其结构整体刚度好、台身圬工量较省、方便施工,能够满足30t轴重列车的运营要求.%Focusing on the axle load of 30 tons which was applied to the Railway Passage in Central and Southern Shanxi, the development characteristics of heavy haul railway at home and abroad at present were analyzed. The design criteria, design load and the load calculation model were formulated. After the eccentricities and the stresses are checked out, the structure size of hollow abutment was defined. The design results show that the rectangular hollow abutment which the abutment length increases with the increase of earth filling's height, has a good rigidity with less amount of masonry, can be convenient for construction, and can meet the requirements of train's operation under 30t axle load.

  15. Preload and torque removal evaluation of three different abutment screws for single standing implant restorations

    Directory of Open Access Journals (Sweden)

    Rafael Augusto Stüker

    2008-02-01

    Full Text Available Several authors still consider the mechanical problems of fracture and component loosening as the main causes of failure of implant-supported restorations. The purpose of this in vitro study was to compare the preload of three types of screw for transmucosal abutment attachment used in single implant-supported prosthesis through strain gauge and removal torque measurements. Three external hex fixtures were used, and each received a transmucosal abutment (Cera One®, which was fixed to the implant with its respective screw: Group A- gold screw, Group B- titanium screw and Group C- surface-treated titanium screw (Ti-Tite®. Ten screws of each type were attached applying a 30.07±0.28 Ncm torque force and maintained in position for 5 minutes. After this, the preload values were measured using strain gauges and a measurement cell. Gold screws presented higher preload values (131.72±8.98 N, followed by surface-treated titanium screws (97.78±4.68 N and titanium screws (37.03±5.69 N. ANOVA (p<0.05 and Tukey's test (p<0.05 were applied. Statistically significant differences were found among the groups for both preload and removal torque values. In conclusion, gold screws may be indicated to achieve superior longevity of the abutment-implant connection and, consequently, prosthetic restoration due to greater preload values yielded.

  16. Repeatability and reproducibility of individual abutment impression, assessed with a blue light scanner

    Science.gov (United States)

    Kim, Dong-Yeon; Lee, Jae-Jun; Kim, Ji-Hwan

    2016-01-01

    PURPOSE We assessed the repeatability and reproducibility of abutment teeth dental impressions, digitized with a blue light scanner, by comparing the discrepancies in repeatability and reproducibility values for different types of abutment teeth. MATERIALS AND METHODS To evaluate repeatability, impressions of the canine, first premolar, and first molar, prepared for ceramic crowns, were repeatedly scanned to acquire 5 sets of 3-dimensional data via stereolithography (STL) files. Point clouds were compared and the error sizes were measured (n=10, per type). To evaluate reproducibility, the impressions were rotated by 10-20° on the table and scanned. These data were compared to the first STL data and the error sizes were measured (n=5, per type). One-way analysis of variance was used to assess the repeatability and reproducibility of the 3 types of teeth, and Tukey honest significant differences (HSD) multiple comparison test was used for post hoc comparisons (α=.05). RESULTS The differences with regard to repeatability were 4.5, 2.7, and 3.1 µm for the canine, premolar, and molar, indicating the poorest repeatability for the canine (P<.001). For reproducibility, the differences were 6.6, 5.8, and 11.0 µm indicating the poorest reproducibility for the molar (P=.007). CONCLUSION Our results indicated that impressions of individual abutment teeth, digitized with a blue light scanner, had good repeatability and reproducibility. PMID:27350856

  17. Soft Tissue Response to Titanium Abutments with Different Surface Treatment: Preliminary Histologic Report of a Randomized Controlled Trial

    Science.gov (United States)

    Canullo, Luigi; Dehner, Jan Friedrich; Penarrocha, David; Checchi, Vittorio; Mazzoni, Annalisa; Breschi, Lorenzo

    2016-01-01

    The aim of this preliminary prospective RCT was to histologically evaluate peri-implant soft tissues around titanium abutments treated using different cleaning methods. Sixteen patients were randomized into three groups: laboratory customized abutments underwent Plasma of Argon treatment (Plasma Group), laboratory customized abutments underwent cleaning by steam (Steam Group), and abutments were used as they came from industry (Control Group). Seven days after the second surgery, soft tissues around abutments were harvested. Samples were histologically analyzed. Soft tissues surrounding Plasma Group abutments predominantly showed diffuse chronic infiltrate, almost no acute infiltrate, with presence of few polymorphonuclear neutrophil granulocytes, and a diffuse presence of collagenization bands. Similarly, in Steam Group, the histological analysis showed a high variability of inflammatory expression factors. Tissues harvested from Control Group showed presence of few neutrophil granulocytes, moderate presence of lymphocytes, and diffuse collagenization bands in some sections, while they showed absence of acute infiltrate in 40% of sections. However, no statistical difference was found among the tested groups for each parameter (p > 0.05). Within the limit of the present study, results showed no statistically significant difference concerning inflammation and healing tendency between test and control groups. PMID:27366741

  18. The Effect of Laser-Etched Surface Design on Soft Tissue Healing of Two Different Implant Abutment Systems: An Experimental Study in Dogs.

    Science.gov (United States)

    Neiva, Rodrigo; Tovar, Nick; Jimbo, Ryo; Gil, Luiz F; Goldberg, Paula; Barbosa, Joao Pm; Lilin, Thomas; Coelho, Paulo G

    2016-01-01

    This study describes the early soft tissue morphology around two different implant systems that received either smooth or laser-etched abutments in a beagle dog model. Implants were placed in the healed mandibular molar region of eight beagle dogs and allowed to heal for 7 weeks. When the most apical aspect of the junctional epithelium (JE) was above or within the upper half of the laser-etched region, fibers were oriented perpendicular to the abutment surface. In contrast, JE positioned within the lower half of the laser-etched region or within or below the implant-abutment gap level presented fibers oriented parallel to the abutment surface. PMID:27560671

  19. Effect of vegetated-banks on local scour around a wing-wall abutment with cir-cular edges

    Institute of Scientific and Technical Information of China (English)

    AFZALIMEHR Hossein; BAKHSHI Somayeh; GALLICHAND Jacques; SUI Jueyi

    2014-01-01

    Failure of bridges due to local scour in the vicinity of bridge abutments is a common occurrence. In this study, experime-nts under two different channel conditions were conducted to assess the impacts of vegetation on channel banks on local scour around a wing-wall abutment with circular edges. Some experiments were conducted in channel with vegetation on channel banks, and other experiments in channel without vegetation on channel bank. The flow velocity and Reynolds stress distributions in scour holes around a wing-wall abutment with circular edges were compared under these 2 different channel conditions. Results reveal that the vegetated-banks can reduce the time for achieving the equilibrium condition from 17 h to 9 h. Also, vegetated-bank channels can result in a significant decrease in the maximum scour depth from 0.084 m (for bare channel bank) to 0.00032 m. Additionally, around the abutment, vegetated-banks play a significant role in diminishing the Reynolds stress (RS) near the bed and removing negative values in RS distribution by weakening unfavorable pressure gradient and down-flow in the upstream of abutment.

  20. Radiologic evaluation of bone loss at implants with biocide coated titanium abutments: a study in the dog.

    Directory of Open Access Journals (Sweden)

    Roberto López-Píriz

    Full Text Available The objective of the present study is to evaluate bone loss at implant abutments coated with a soda-lime glass containing silver nanoparticles subjected to experimental peri-implantitis. Five beagle dogs were used in the experiments, 3 implants were installed in each quadrant of the mandibles. Glass/n-Ag coted abutments were connected to implant platform. Cotton floss ligatures were placed in a submarginal position around the abutment necks and the animals were subject to a diet which allowed plaque accumulation, and after 15 weeks the dogs were sacrificed. Radiographs of all implant sites were obtained at the beginning and at the end of the experimentally induced peri-implantitis. The radiographic examination indicated that significant amounts of additional bone loss occurred in implants without biocide coating, considering both absolute and relative values of bone loss. Percentages of additional bone loss observed in implants dressed with a biocide coated abutment were about 3 times lower (p<0.006 distal aspect; and p<0.031 at mesial aspect than the control ones. Within the limits of the present study it seems promising the use of soda-lime glass/nAg coatings on abutments to prevent peri-implant diseases.

  1. Effect of Abutment Taper on the Fracture Resistance of all-Ceramic Three-unit Bridges

    OpenAIRE

    F. Gerami-Panah; H. Jalali; L. Sedighpour

    2005-01-01

    Statement of Problem: The connector area is the weakest zone of an all-ceramic fixed partial denture (FPD), where most catastrophic failures of the prostheses tend to occur.Purpose: The aim of the present study was to assess the effect of the convergence angle of abutments on the fracture resistance of three-unit fixed partial dentures made of IPSEmpress2.Materials and Methods: Forty extracted human premolars and molars were used to reproduce twenty, 3-unit fixed partial dentures, for the rep...

  2. Implications of Surface and Bulk Properties of Abutment Implants and Their Degradation in the Health of Periodontal Tissue

    Directory of Open Access Journals (Sweden)

    Erica Dorigatti de Avila

    2013-12-01

    Full Text Available The aim of the current review was to investigate the implications of the surface and bulk properties of abutment implants and their degradation in relation to periodontal health. The success of dental implants is no longer a challenge for dentistry. The scientific literature presents several types of implants that are specific for each case. However, in cases of prosthetics components, such as abutments, further research is needed to improve the materials used to avoid bacterial adhesion and enhance contact with epithelial cells. The implanted surfaces of the abutments are composed of chemical elements that may degrade under different temperatures or be damaged by the forces applied onto them. This study showed that the resulting release of such chemical elements could cause inflammation in the periodontal tissue. At the same time, the surface characteristics can be altered, thus favoring biofilm development and further increasing the inflammation. Finally, if not treated, this inflammation can cause the loss of the implant.

  3. The effect of platform switching on the levels of metal ion release from different implant–abutment couples

    Science.gov (United States)

    Alrabeah, Ghada O; Knowles, Jonathan C; Petridis, Haralampos

    2016-01-01

    The improved peri-implant bone response demonstrated by platform switching may be the result of reduced amounts of metal ions released to the surrounding tissues. The aim of this study was to compare the levels of metal ions released from platform-matched and platform-switched implant–abutment couples as a result of accelerated corrosion. Thirty-six titanium alloy (Ti-6Al-4V) and cobalt–chrome alloy abutments were coupled with titanium cylinders forming either platform-switched or platform-matched groups (n=6). In addition, 18 unconnected samples served as controls. The specimens were subjected to accelerated corrosion by static immersion in 1% lactic acid for 1 week. The amount of metal ions ion of each test tube was measured using inductively coupled plasma mass spectrometry. Scanning electron microscope (SEM) images and energy dispersive spectroscopy X-ray analyses were performed pre- and post-immersion to assess corrosion at the interface. The platform-matched groups demonstrated higher ion release for vanadium, aluminium, cobalt, chrome, and molybdenum compared with the platform-switched groups (PTitanium was the highest element to be released regardless of abutment size or connection (P<0.05). SEM images showed pitting corrosion prominent on the outer borders of the implant and abutment platform surfaces. In conclusion, implant–abutment couples underwent an active corrosion process resulting in metal ions release into the surrounding environment. The highest amount of metal ions released was recorded for the platform-matched groups, suggesting that platform-switching concept has a positive effect in reducing the levels of metal ion release from the implant–abutment couples. PMID:27357323

  4. The effect of platform switching on the levels of metal ion release from different implant-abutment couples.

    Science.gov (United States)

    Alrabeah, Ghada O; Knowles, Jonathan C; Petridis, Haralampos

    2016-01-01

    The improved peri-implant bone response demonstrated by platform switching may be the result of reduced amounts of metal ions released to the surrounding tissues. The aim of this study was to compare the levels of metal ions released from platform-matched and platform-switched implant-abutment couples as a result of accelerated corrosion. Thirty-six titanium alloy (Ti-6Al-4V) and cobalt-chrome alloy abutments were coupled with titanium cylinders forming either platform-switched or platform-matched groups (n=6). In addition, 18 unconnected samples served as controls. The specimens were subjected to accelerated corrosion by static immersion in 1% lactic acid for 1 week. The amount of metal ions ion of each test tube was measured using inductively coupled plasma mass spectrometry. Scanning electron microscope (SEM) images and energy dispersive spectroscopy X-ray analyses were performed pre- and post-immersion to assess corrosion at the interface. The platform-matched groups demonstrated higher ion release for vanadium, aluminium, cobalt, chrome, and molybdenum compared with the platform-switched groups (P<0.05). Titanium was the highest element to be released regardless of abutment size or connection (P<0.05). SEM images showed pitting corrosion prominent on the outer borders of the implant and abutment platform surfaces. In conclusion, implant-abutment couples underwent an active corrosion process resulting in metal ions release into the surrounding environment. The highest amount of metal ions released was recorded for the platform-matched groups, suggesting that platform-switching concept has a positive effect in reducing the levels of metal ion release from the implant-abutment couples. PMID:27357323

  5. Assessment of the tensile strength of hexagonal abutments using different cementing agents

    Directory of Open Access Journals (Sweden)

    Carlos Wahl

    2008-12-01

    Full Text Available The aim of this study was to assess the uniaxial tensile strength after thermal cycling in replicas of CeraOne®abutments (abutment and coping sets, using four types of cements (n = 10. A zinc phosphate cement (Fosfato de Zinco®/ SSW, a resin-modified glass ionomer cement (RelyX®luting / 3M-ESPE, a zinc oxide-eugenol cement (ZOE®/ SSW and a zinc oxide cement without eugenol (TempBond NE®/ KERR were used. After cementation, the samples were submitted to thermal cycles (1,000 cycles, 5ºC ± 2º to 55ºC ± 2º for thirty seconds in each bath. Next, the samples were submitted to the tensile test in a universal test machine (0.5 mm/min. The data were submitted to ANOVA and the Tukey-Kramer test (p < 0.05, and statistically significant difference was found among the cements. The highest tensile strength mean value found was for zinc phosphate cement (33.6 kgf followed by the resin-modified glass ionomer cement (20.5 kgf, zinc oxide-eugenol cement (8.4 kgf and the temporary cement (3.1 kgf. Therefore, it was found that the permanent cements presented higher tensile strength, and the temporary cement could be used in situations requiring reversibility and the removal of cemented dental implant-supported prostheses.

  6. Histology of a dental implant with a platform switched implant-abutment connection

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    Vittoria Perrotti

    2011-10-01

    Full Text Available Background: Peri-implant crestal bone must be stable for aesthetic reasons. Aim of this study was a histologic analysis of an implant with a platform switched implant-abutment connection. Materials and methods: A 32-year-old male patient participated in this study. The patient needed a bilateral mandibular restoration. Four implants were used, and were immediately restored and loaded the same day of insertion. After a 6 weeks healing period, one implant with platform-switched abutment was retrieved with trephine. Before retrieval the implant was osseointegrated and not mobile. On one side of the implant, a 1 mm resorption of the crestal bone was present. On the contrary, on the other side no bone resorption had occurred and about 1 mm of bone was present over the implant shoulder. Results: The bone-implant contact percentage was 65.1 ± 6.3 %. Platform- switching could help in maintaining the height of the peri-implant crestal bone.

  7. EFFECTS OF FLOW INTENSITY, OBSTACLE ALIGNMENT AND CROSS-SECTION GEOMETRY ON SCOUR AT BRIDGE ABUTMENTS

    Institute of Scientific and Technical Information of China (English)

    A. H. CARDOSO; J. S. SANTOS; M. ROCA

    2002-01-01

    Experiments are reported on the effects of flow intensity, obstacle alignment and cross-section geome try on the equilibrium scour depth around abutments. The effect of flow intensity was studied for clear water flow conditions, the obstacle alignment was studied for a wide range of angles of the obstacle with the flow direction, and tests on the cross-section geometry apply only to the case where the abut ment extends into the main channel of a compound cross-section (two-stage channel). The channel bank and flood plain were built up with sand. The hypothesis of zero scour for flow velocities smaller than approximately 50% of the threshold velocity for the beginning of motion in the approaching flow cannot be rejected; maximum scour occurs for obstacles protruding at right angle from the cross-section walls, the reduction being small when obstacles point upstream; compared with rigid banks, the scour depth seems to be significantly reduced when channel bank and flood plain are constituted of alluvial material.

  8. Combination of natural teeth and osseointegrated implants as prosthesis abutments in a posterior cantilever bridge

    Directory of Open Access Journals (Sweden)

    Michael Josef Kridanto Kamadjaja

    2008-06-01

    Full Text Available Dental implants have been used for several decades. Patients of all ages have chosen dental implants to replace a single tooth or several teeth or to support partial or full dentures. This paper reports two cases of patients treated with dental implant as alternative to replace the missing teeth and connected with natural tooth as abutments in a fixed restoration with distal cantilever bridge. The underlining reasons that we decided to make such kind fixed prostheses are because of clinically imposible to put the implant on certain area and the patients asked for prostheses as optimum as possible, so the mastication function could return to the homeostasis condition. The benefit of these treatments are that prostheses could be made as optimum as possible with a more economic price, so the patients feel quite satisfied. The result shows that a few years after the treatments finished there is no any disadvantageous effect of connecting teeth to implants as abutments in fixed partial dentures and there is no sign of a harmful effect to the opposing teeth either.

  9. Biomechanical Analysis of Tapered Integrated Screw and Sensitivity Analysis on Abutment Loosening in Dental Implants

    Directory of Open Access Journals (Sweden)

    Milad Farzadi

    2013-02-01

    Full Text Available Background and Aims: Different mechanisms have been developed for connecting abutment to implant. One of the most popular mechanisms is Tapered Integrated Screw (TIS, which is a Tapered Interference Fit (TIF with a screw integrated at the bottom of that. The aim of this study was to investigate the mechanism of TIS and effective factors in employing TIS during design and implementation processes using an analytic method.Materials and Methods: Relevant equations were developed to predict tightening and loosening torques, contactpressure and preloads with and without bone tissue in this analysis. The efficiency is defined as the ratio of the loosening torque to the tightening torque. The effects of the change in elastic modulus and thickness of the bone on operation of this mechanism were investigated.Results: In this study, 14 independent parameters such as taper angle, friction coefficient, abutment and implantgeometry that are effective on performance of TIS mechanism were presented. The role of some factors was shown in the performance of ITI implant using sensitivity analysis.Conclusion: It was shown that friction coefficient, contact length, and implant radius play major roles on tightening and loosening torques and efficiency of the mechanism. Furthermore, the results revealed that the change in the elastic modulus and thickness of the bone influenced the efficiency of the mechanism less than 15%.

  10. Investigation of the Effects of Abutment and Implant Length on Stability of Short Dental Implants

    Directory of Open Access Journals (Sweden)

    Eda OZYILMAZ

    2015-01-01

    Full Text Available The use of dental implants to solve different problems in dentistry has been growing rapidly. The success rates of dental implants are also very important for patients. Depending on the bone level of patients, short dental implants are very popular and widely used by many dentists. Although many dentists are using short dental implants frequently, It can be guessed that there can be stability problems because of crown to implant ratios. In this study, it is aimed to find out the effects of dental implant and abutment lengths on stability of short dental implants. 3 different short dental implant design made with the use of Solidworks 2013. Abutment lengths were 3,5 mm, 4 mm, 4,5 mm, 5 mm and implant lengths were 5 mm, 6 mm, 7 mm for each model. Human mandible model is transferred from Computed Tomography. Then, each implant model is mounted to modeled mandible and Finite Element Analysis is performed for each model. In order to see the effects of implant number on stability, we performed same analysis by placing 4 implants to the mandible

  11. Repeatability and reproducibility of individual abutment impression, assessed with a blue light scanner

    Science.gov (United States)

    Kim, Dong-Yeon; Lee, Jae-Jun; Kim, Ji-Hwan

    2016-01-01

    PURPOSE We assessed the repeatability and reproducibility of abutment teeth dental impressions, digitized with a blue light scanner, by comparing the discrepancies in repeatability and reproducibility values for different types of abutment teeth. MATERIALS AND METHODS To evaluate repeatability, impressions of the canine, first premolar, and first molar, prepared for ceramic crowns, were repeatedly scanned to acquire 5 sets of 3-dimensional data via stereolithography (STL) files. Point clouds were compared and the error sizes were measured (n=10, per type). To evaluate reproducibility, the impressions were rotated by 10-20° on the table and scanned. These data were compared to the first STL data and the error sizes were measured (n=5, per type). One-way analysis of variance was used to assess the repeatability and reproducibility of the 3 types of teeth, and Tukey honest significant differences (HSD) multiple comparison test was used for post hoc comparisons (α=.05). RESULTS The differences with regard to repeatability were 4.5, 2.7, and 3.1 µm for the canine, premolar, and molar, indicating the poorest repeatability for the canine (Pteeth, digitized with a blue light scanner, had good repeatability and reproducibility. PMID:27350856

  12. Effect of Abutment Taper on the Fracture Resistance of all-Ceramic Three-unit Bridges

    Directory of Open Access Journals (Sweden)

    F. Gerami-Panah

    2005-12-01

    Full Text Available Statement of Problem: The connector area is the weakest zone of an all-ceramic fixed partial denture (FPD, where most catastrophic failures of the prostheses tend to occur.Purpose: The aim of the present study was to assess the effect of the convergence angle of abutments on the fracture resistance of three-unit fixed partial dentures made of IPSEmpress2.Materials and Methods: Forty extracted human premolars and molars were used to reproduce twenty, 3-unit fixed partial dentures, for the replacement of second premolars. All teeth were prepared according to the guidelines outlined for all-ceramic crowns and bridges, except for the convergence angles of the abutments. The specimens were randomly divided into two groups of 10, with total occlusal convergence angles of 12° and 22°. Fixed partial dentures with a uniform thickness of 0.8 mm were fabricated using IPS-Empress2 and were bonded to the corresponding models. Connectordimensions were set to 4 mm height and 4mm width. The radius of curvature at the gingival embrasure was carved to 0.9 mm. All specimens were exposed to 10,000 preloading cycles and a load of 40 N at a frequency of 1.3 Hz in a standardized testing machine at a cross head speed of 1mm/min. Student t-test was performed to detect any difference in the mean fracture resistance between the two groups (α = 0.05.Results: Mean failure loads (and standard deviations of the 12° and 22° groups were 1009.12 N (208.05 and 1182.72 N (144.67, respectively. Statistical analysis revealed a significant difference (P <0.04 between the mean failure loads of the two groups. Mostfractures occurred through the connectors.Conclusion: The mean failure loads of the investigated fixed partial dentures were higher in the abutments with 22° taper as compared to those with a taper of 12°.

  13. Rehabilitation of the edentulous mandible with implant-supported overdenture using ball attachments and healing abutments: A case report

    OpenAIRE

    PARK, JUN-BEOM

    2009-01-01

    For many years, osseointegrated implant-supported overdentures have been used in the rehabilitation of the edentulous lower jaw with excellent results. In this report, additional implants with healing abutments were applied posterior to mental foramen on each side was used to achieve additional support to the overdenture.

  14. The Relationship between Biofilm and Physical-Chemical Properties of Implant Abutment Materials for Successful Dental Implants

    Directory of Open Access Journals (Sweden)

    Erica Dorigatti de Avila

    2014-05-01

    Full Text Available The aim of this review was to investigate the relationship between biofilm and peri-implant disease, with an emphasis on the types of implant abutment surfaces. Individuals with periodontal disease typically have a large amount of pathogenic microorganisms in the periodontal pocket. If the individuals lose their teeth, these microorganisms remain viable inside the mouth and can directly influence peri-implant microbiota. Metal implants offer a suitable solution, but similarly, these remaining bacteria can adhere on abutment implant surfaces, induce peri-implantitis causing potential destruction of the alveolar bone near to the implant threads and cause the subsequent loss of the implant. Studies have demonstrated differences in biofilm formation on dental materials and these variations can be associated with both physical and chemical characteristics of the surfaces. In the case of partially edentulous patients affected by periodontal disease, the ideal type of implant abutments utilized should be one that adheres the least or negligible amounts of periodontopathogenic bacteria. Therefore, it is of clinically relevance to know how the bacteria behave on different types of surfaces in order to develop new materials and/or new types of treatment surfaces, which will reduce or inhibit adhesion of pathogenic microorganisms, and, thus, restrict the use of the abutments with indication propensity for bacterial adhesion.

  15. Effect of abutment angulation in the retention and durability of three overdenture attachment systems: An in vitro study

    Science.gov (United States)

    Ustrell, Raul; Mendes, Jose Manuel; Braga, Ana Cristina; Berastegui, Esther

    2016-01-01

    PURPOSE This in vitro study investigated and compared the durability and retention of three types of attachments. MATERIALS AND METHODS Three commercially available attachments were investigated: Clix®, Dalbo-Plus® and Locator®. In total, 72 samples of these attachments were placed in the acrylic resin forms and subjected to mechanical testing (5400 cycles of insertion and removal) over the respective ball or Locator abutments immersed in artificial saliva at pH 7 and 37℃. The abutments were placed at angulations of 0°, 10° and 20°. The retention force was recorded at the beginning and after 540, 1080, 2160, 3240, 4320 and 5400 insertion-removal cycles. RESULTS The results revealed that there were significant differences in the average values of the insertion/removal force due to angulation (F (2.48) = 343619, P<.05) and the type of attachment (F (7.48) = 23.220, P<.05). CONCLUSION Greater angulation of the abutments was found to influence the retention capacity of the attachments, and the fatigue test simulating 5 years of denture insertion and removal did not produce wear in the metal abutments. PMID:26949484

  16. Microbial diversity of supra- and subgingival biofilms on freshly colonized titanium implant abutments in the human mouth.

    Science.gov (United States)

    Heuer, W; Stiesch, M; Abraham, W R

    2011-02-01

    Supra- and subgingival biofilm formation is considered to be mainly responsible for early implant failure caused by inflammations of periimplant tissues. Nevertheless, little is known about the complex microbial diversity and interindividual similarities around dental implants. An atraumatic assessment was made of the diversity of microbial communities around titanium implants by single strand conformation polymorphism (SSCP) analysis of the 16S rRNA gene amplicons as well as subsequent sequence analysis. Samples of adherent supra- and subgingival periimplant biofilms were collected from ten patients. Additionally, samples of sulcusfluid were taken at titanium implant abutments and remaining teeth. The bacteria in the samples were characterized by SSCP and sequence analysis. A high diversity of bacteria varying between patients and within one patient at different locations was found. Bacteria characteristic for sulcusfluid and supra- and subgingival biofilm communities were identified. Sulcusfluid of the abutments showed higher abundance of Streptococcus species than from residual teeth. Prevotella and Rothia species frequently reported from the oral cavity were not detected at the abutments suggesting a role as late colonizers. Different niches in the human mouth are characterized by specific groups of bacteria. Implant abutments are a very valuable approach to study dental biofilm development in vivo. PMID:20931254

  17. Microbial diversity of supra- and subgingival biofilms on freshly colonized titanium implant abutments in the human mouth.

    Science.gov (United States)

    Heuer, W; Stiesch, M; Abraham, W R

    2011-02-01

    Supra- and subgingival biofilm formation is considered to be mainly responsible for early implant failure caused by inflammations of periimplant tissues. Nevertheless, little is known about the complex microbial diversity and interindividual similarities around dental implants. An atraumatic assessment was made of the diversity of microbial communities around titanium implants by single strand conformation polymorphism (SSCP) analysis of the 16S rRNA gene amplicons as well as subsequent sequence analysis. Samples of adherent supra- and subgingival periimplant biofilms were collected from ten patients. Additionally, samples of sulcusfluid were taken at titanium implant abutments and remaining teeth. The bacteria in the samples were characterized by SSCP and sequence analysis. A high diversity of bacteria varying between patients and within one patient at different locations was found. Bacteria characteristic for sulcusfluid and supra- and subgingival biofilm communities were identified. Sulcusfluid of the abutments showed higher abundance of Streptococcus species than from residual teeth. Prevotella and Rothia species frequently reported from the oral cavity were not detected at the abutments suggesting a role as late colonizers. Different niches in the human mouth are characterized by specific groups of bacteria. Implant abutments are a very valuable approach to study dental biofilm development in vivo.

  18. Distribution laws of abutment pressure around fully mechanized top-coal caving face by in-situ measurement

    Institute of Scientific and Technical Information of China (English)

    CHANG Ju-cai

    2011-01-01

    In order to obtain the distribution rules of abutment pressure around the 1151 (3) fully mechanized top-coal caving (FMTC) face of Xieqiao Colliery, the KSE-Ⅱ-1 type bore-hole stress gauges were installed in the tailentry and headentry to measure the mining-induced stress. The distribution rules of the front and side abutment pressure were demonstrated. The results show that distribution rules of stress are obviously different in the vicinity of the face and entries. The peak value of abutment pressure in the protective coal pillar and face are located commonly in front of the working face along the strike, and they are located at the stress-decreased zone near the face. There is no stress peak value in the lateral coal mass beside the headentry in front of the face on the strike, and the peak value of abutment pressure appears at the rear area of the face. There are stress peak values both in the protective coal pillar and in the lateral coal mass beside the headentry to the dip.

  19. Zirconia- versus metal-based, implant-supported abutments and crowns

    DEFF Research Database (Denmark)

    Hosseini, Mandana

    was to test the reliability and validity of six aesthetic parameters used at the Copenhagen Dental School to assess the aesthetic outcome of implant-supported restorations. The aims of study III and IV were to compare the influence of different abutment and crown materials on biological, biomechanical......To restore oral functions in patients with missing teeth, single-tooth implants are a well-documented treatment option. Along with high survival rates, aesthetic factors have become an important clinical outcome variable for evaluating treatment success of implant-supported restorations. Thus...... studies have reported on aesthetic, biological, biomechanical and patient-reported outcomes of implant-supported single-tooth restorations of various biomaterials. The aim of the present thesis was to investigate the clinical performance of zirconia-based implant-supported single-tooth restorations...

  20. Economical bridge solutions based on innovative composite dowels and integrated abutments ecobridge

    CERN Document Server

    Băncilă, Radu

    2015-01-01

    This book is an outcome of the research project “ECOBRIDGE – Demonstration of ECOnomical BRIDGE solutions based on innovative composite dowels and integrated abutments – RFCS – CT 2010-00024”, which has been co-funded by the Research Fund for Coal and Steel (R.F.C.S.) of the European Community. The main topics of the book are the following: design of integral bridges, innovative composite dowels for the shear transmission, construction of bridges, structural analysis of bridges and monitoring. The book joins the technical experience and the contributions of the involved research partners. The technical content of all the papers is present-day in the field of the design, construction and monitoring of innovative composite bridges. The efficient design and construction improve and consolidate the market position of steel construction and steel producing industry. In addition, the advanced forms of construction are contributing to savings in material and energy consumption for the structure during prod...

  1. RADIOACTIVE OR NATURAL TRACER。TECHNIQUES FOR LEAK DETERMINING OF DAM ABUTMENT

    Institute of Scientific and Technical Information of China (English)

    陈建生; 杜国平; 等

    1995-01-01

    Infiltration and localization of preferential infiltration zones at the dam abutment are measured using radioactive tracer tests of flow in boreholes,meanwhile interconnection between boreholes and the energing water points is analysed.The theory and practice of radioactive tracer synthetic detective method are described to give methods and calculation formulae used under the condition of stable flow in single well to measure permeability coefficient and hydrostatic heads.Major single hole techniques including measurement for seepage line,velocity,rate of seepage flow and relationship of recharge of groundwater in aquifers are introduced briefly.The possibilities offered by natureal tracers are analysed,uincluding electric-conduct,pH-value and temperature of water as well as stable isotopes(D,18O) and tritium.Furthermore,the sensibilities of this theory and methods were confirmed by detecting seepage flow field of Xinanjiang Dam.

  2. Accuracy of 3D white light scanning of abutment teeth impressions: evaluation of trueness and precision

    Science.gov (United States)

    Jeon, Jin-Hun; Kim, Hae-Young; Kim, Ji-Hwan

    2014-01-01

    PURPOSE This study aimed to evaluate the accuracy of digitizing dental impressions of abutment teeth using a white light scanner and to compare the findings among teeth types. MATERIALS AND METHODS To assess precision, impressions of the canine, premolar, and molar prepared to receive all-ceramic crowns were repeatedly scanned to obtain five sets of 3-D data (STL files). Point clouds were compared and error sizes were measured (n=10 per type). Next, to evaluate trueness, impressions of teeth were rotated by 10°-20° and scanned. The obtained data were compared with the first set of data for precision assessment, and the error sizes were measured (n=5 per type). The Kruskal-Wallis test was performed to evaluate precision and trueness among three teeth types, and post-hoc comparisons were performed using the Mann-Whitney U test with Bonferroni correction (α=.05). RESULTS Precision discrepancies for the canine, premolar, and molar were 3.7 µm, 3.2 µm, and 7.3 µm, respectively, indicating the poorest precision for the molar (Pteeth types were 6.2 µm, 11.2 µm, and 21.8 µm, respectively, indicating the poorest trueness for the molar (P=.007). CONCLUSION In respect to accuracy the molar showed the largest discrepancies compared with the canine and premolar. Digitizing of dental impressions of abutment teeth using a white light scanner was assessed to be a highly accurate method and provided discrepancy values in a clinically acceptable range. Further study is needed to improve digitizing performance of white light scanning in axial wall. PMID:25551007

  3. Bone loss at implant with titanium abutments coated by soda lime glass containing silver nanoparticles: a histological study in the dog.

    Science.gov (United States)

    Martinez, Arturo; Guitián, Francisco; López-Píriz, Roberto; Bartolomé, José F; Cabal, Belén; Esteban-Tejeda, Leticia; Torrecillas, Ramón; Moya, José S

    2014-01-01

    The aim of the present study was to evaluate bone loss at implants connected to abutments coated with a soda-lime glass containing silver nanoparticles, subjected to experimental peri-implantitis. Also the aging and erosion of the coating in mouth was studied. Five beagle dogs were used in the experiments. Three implants were placed in each mandible quadrant: in 2 of them, Glass/n-Ag coated abutments were connected to implant platform, 1 was covered with a Ti-mechanized abutment. Experimental peri-implantitis was induced in all implants after the submarginal placement of cotton ligatures, and three months after animals were euthanatized. Thickness and morphology of coating was studied in abutment cross-sections by SEM. Histology and histo-morphometric studies were carried on in undecalfied ground slides. After the induced peri-implantitis: 1.The abutment coating shown losing of thickness and cracking. 2. The histometry showed a significant less bone loss in the implants with glass/n-Ag coated abutments. A more symmetric cone of bone resorption was observed in the coated group. There were no significant differences in the peri-implantitis histological characteristics between both groups of implants. Within the limits of this in-vivo study, it could be affirmed that abutments coated with biocide soda-lime-glass-silver nanoparticles can reduce bone loss in experimental peri-implantitis. This achievement makes this coating a suggestive material to control peri-implantitis development and progression. PMID:24466292

  4. Bone loss at implant with titanium abutments coated by soda lime glass containing silver nanoparticles: a histological study in the dog.

    Directory of Open Access Journals (Sweden)

    Arturo Martinez

    Full Text Available The aim of the present study was to evaluate bone loss at implants connected to abutments coated with a soda-lime glass containing silver nanoparticles, subjected to experimental peri-implantitis. Also the aging and erosion of the coating in mouth was studied. Five beagle dogs were used in the experiments. Three implants were placed in each mandible quadrant: in 2 of them, Glass/n-Ag coated abutments were connected to implant platform, 1 was covered with a Ti-mechanized abutment. Experimental peri-implantitis was induced in all implants after the submarginal placement of cotton ligatures, and three months after animals were euthanatized. Thickness and morphology of coating was studied in abutment cross-sections by SEM. Histology and histo-morphometric studies were carried on in undecalfied ground slides. After the induced peri-implantitis: 1.The abutment coating shown losing of thickness and cracking. 2. The histometry showed a significant less bone loss in the implants with glass/n-Ag coated abutments. A more symmetric cone of bone resorption was observed in the coated group. There were no significant differences in the peri-implantitis histological characteristics between both groups of implants. Within the limits of this in-vivo study, it could be affirmed that abutments coated with biocide soda-lime-glass-silver nanoparticles can reduce bone loss in experimental peri-implantitis. This achievement makes this coating a suggestive material to control peri-implantitis development and progression.

  5. Effect of abutment shade, ceramic thickness, and coping type on the final shade of zirconia all-ceramic restorations: in vitro study of color masking ability

    Science.gov (United States)

    Oh, Seon-Hee

    2015-01-01

    PURPOSE The aim of the study was to evaluate the effect of abutment shade, ceramic thickness, and coping type on the final shade of zirconia all-ceramic restorations. MATERIALS AND METHODS Three different types of disk-shaped zirconia coping specimens (Lava, Cercon, Zirkonzahn: ø10 mm × 0.4 mm) were fabricated and veneered with IPS e.max Press Ceram (shade A2), for total thicknesses of 1 and 1.5 mm. A total of sixty zirconia restoration specimens were divided into six groups based on their coping types and thicknesses. The abutment specimens (ø10 mm × 7 mm) were prepared with gold alloy, base metal (nickel-chromium) alloy, and four different shades (A1, A2, A3, A4) of composite resins. The average L*, a*, b* values of the zirconia specimens on the six abutment specimens were measured with a dental colorimeter, and the statistical significance in the effects of three variables was analyzed by using repeated measures analysis of variance (α=.05).The average shade difference (ΔE) values of the zirconia specimens between the A2 composite resin abutment and other abutments were also evaluated. RESULTS The effects of zirconia specimen thickness (P<.001), abutment shade (P<.001), and type of zirconia copings (P<.003) on the final shade of the zirconia restorations were significant. The average ΔE value of Lava specimens (1 mm) between the A2 composite resin and gold alloy abutments was higher (close to the acceptability threshold of 5.5 ΔE) than th ose between the A2 composite resin and other abutments. CONCLUSION This in-vitro study demonstrated that abutment shade, ceramic thickness, and coping type affected the resulting shade of zirconia restorations. PMID:26576252

  6. 多年冻土区路桥过渡段的一种新结构%A New Structure of Roadbed-Abutment Transition Part on Permafrost

    Institute of Scientific and Technical Information of China (English)

    刘建坤; 鲍维猛; 黎明; 葛建军

    2004-01-01

    The design of roadbed-abutment transition part is always a challenging problem in transportation engineering, especially in permafrost distribution zone. A new type of roadbed-abutment transition part on permafrost was presented, and long-term observation was conducted for the deformation and the thermal regime of a roadbed-abutment transition part in the constructing Qinghai-Tibet Railway. In this paper, a new structure was presented and the observed settlements both in the subgrade and the base and its dependency with the thermal regime (permafrost table) were analyzed. In conclusion the roadbed-a-butment transition method for permafrost distribution zone was evaluated.

  7. Bone Loss at Implant with Titanium Abutments Coated by Soda Lime Glass Containing Silver Nanoparticles: A Histological Study in the Dog

    OpenAIRE

    Martinez, Arturo; Guitián, Francisco; López-Píriz, R.; Bartolomé, J. F.; Cabal, B.; Esteban-Tejeda, L.; Torrecillas, Ramón; J. S. Moya

    2014-01-01

    The aim of the present study was to evaluate bone loss at implants connected to abutments coated with a soda-lime glass containing silver nanoparticles, subjected to experimental peri-implantitis. Also the aging and erosion of the coating in mouth was studied. Five beagle dogs were used in the experiments. Three implants were placed in each mandible quadrant: in 2 of them, Glass/n-Ag coated abutments were connected to implant platform, 1 was covered with a Ti-mechanized abutment. Experimental...

  8. Bone response from a dynamic stimulus on a one-piece and multi-piece implant abutment and crown by finite element analysis.

    Science.gov (United States)

    Hajimiragha, Habib; Abolbashari, Mohammadreza; Nokar, Saeed; Abolbashari, AmirHossein; Abolbashari, Mehrdad

    2014-10-01

    The present study was done to evaluate the effects of different types of abutments on the rate and distribution of stress on the bone surrounding the implant by dynamic finite element analysis method. In this study two ITI abutment models-one-piece and multi-piece-along with fixture, bone, and superstructure have been simulated with the help of company-made models. The maximum Von Mises stress (MVMS) was observed in the distobuccal area of the cortical bone near the crest of implant in two implant models. In the multi-piece abutment, MVMS was higher than the one-piece model (27.9 MPa and 23.3 MPa, respectively). Based on the results of this study, it can be concluded that type of abutment influences the stress distribution in the area surrounding the implant during dynamic loading.

  9. Randomized Controlled Clinical Trial of All-Ceramic Single Tooth Implant Reconstructions Using Modified Zirconia Abutments: Radiographic and Prosthetic Results at 1 Year of Loading

    OpenAIRE

    Thoma, Daniel S.; Brandenberg, Francine; Fehmer, Vincent; Büchi, Dominik L.E.; Hämmerle, Christoph H.F.; Sailer, Irena

    2015-01-01

    This study aims to test whether or not veneering of the submucosal part of zirconia abutments with pink dental ceramic affects radiographic and technical outcomes of implant-supported single crowns (ISSC).

  10. "EFFECTS OF FLOW INTENSITY, OBSTACLE ALIGNMENT AND CROSS-SECTION GEOMETRY ON SCOUR AT BRIDGE ABUTMENTS" CARDOSO, A.H., SANTOS, J.S. and ROCA, M.

    Institute of Scientific and Technical Information of China (English)

    Bruce W. MELVILLE

    2002-01-01

    The authors present new measurements of maximum (equilibrium) local scour depth at bridge abutments, the new data being analysed in terms of the multiplying factors given in Melville (1992,1997) and Melville and Coleman (2000). The design method presented in these publications is referred to here as the University of Auckland (UoA) Method. The authors' data apply to the following factors:∏f (flow intensity), ∏θ (abutment alignment) and ∏g (approach channel geometry).

  11. Clinical Outcome of Inter-Proximal Papilla between a Tooth and a Single Implant Treated with CAD/CAM Abutments: a Cross-Sectional Study

    OpenAIRE

    Tiago Borges; Tiago Lima; Ágata Carvalho; Vasco Carvalho

    2012-01-01

    ABSTRACT Objectives The aim of this study was to assess the clinical outcomes achieved with Computer-Assisted Design/Computer-Assisted Manufacturing implant abutments in the anterior maxilla. Material and Methods Nineteen patients with a mean age of 41 (range form 26 to 63) years, treated with 21 single tooth implants and 21 Computer-Assisted Design/Computer-Assisted Manufacturing (CAD/CAM) abutments in the anterior maxillary region were included in this study. The patients followed 4 criteri...

  12. Periodontal and pulpal conditions of abutment teeth. Status after four to eight years following the incorporation of fixed reconstructions.

    Science.gov (United States)

    Reichen-Graden, S; Lang, N P

    1989-01-01

    In the present retrospective clinical study, 58 patients were examined 4 to 8 years (median 77 months) following the incorporation of a fixed reconstruction. No regular maintenance care had been provided during the interval period. The periodontal conditions represented by the Plaque Control Record (PCR), the Gingival Index (GI) and pocket probing depths were examined on 182 abutment teeth of 94 reconstructions. Pulpal vitality and periapical pathology were assessed clinically as well as radiographically. The periodontal parameters of the abutment teeth were compared with homologous contralateral uncrowned teeth. Significantly higher plaque prevalence, gingival indices, and pocket probing depths were found in the crowned teeth. Also, bleeding on probing was observed more frequently whenever the crown margins were located subgingivally. At the end of the interval period, 3.7% of the originally vital abutments had lost their vitality. A technical failure rate of 7.4% with no apparent differences between conventional and extension bridges was noted. This study indicates that even with precise marginal fit and in the absence of a regular maintenance program, the supragingival location of the crown margin is more favourable than the subgingival location for the maintenance of oral health. PMID:2701195

  13. Distribution pattern of front abutment pressure of fully-mechanized working face of soft coal isolated island

    Institute of Scientific and Technical Information of China (English)

    Xu Wenquan; Wang Enyuan; Shen Rongxi; Song Dazhao; Zhang Jingmin

    2012-01-01

    The front abutment pressure of a fully-mechanized workface of 11061 soft coal isolated island of Liangbei Coal Mine was measured and studied using a self-developed mining-induced stress monitoring system associated with electromagnetic radiation technology,and the effects of abutment pressure distribution on strata behavior we discussed.The results indicate that the mining-induced influencing distance advanced at the fully-mechanized working face of soft coal isolated island is larger than that at the general working face at the isolated island,besides the fracture zone in front of working face was widened to some extent,and the influencing range caused by relaxations on both roadways became bigger with the advancing working face.Moreover,it can be indicated that mining has significant effect on strata behavior of fully-mechanized working face of soft coal isolated island,which is mostly distributed in the area of stress concentration.The research results have an important reference value for revealing the distribution pattern of the front abutment pressure of a fully-mechanized working face of soft coal isolated island,and controlling the coal-rock dynamic disaster occurrence under similar mining conditions.

  14. Analysis of Stability of Gaixia Arch Dam Abutment%盖下拱坝坝肩稳定分析

    Institute of Scientific and Technical Information of China (English)

    房巍; 刘晓青

    2011-01-01

    Taking Gaixia arch dam as the object of the research and combining finite elements and rigid limit equilibrium method to study the stability of Gaixia arch dam abutment in static and dynamic conditions, the anti-slide safety factor of the abutment is obtained. The results satisfy the specification; it is shown that the Gaixia arch dam abutment is safe. The results can be taken as reference for practical projects.%以盖下拱坝为研究对象,结合有限元和刚体极限平衡法,分析了盖下拱坝坝肩岩体在静、动力条件下的稳定性,得到坝肩岩体的抗剪安全系数.所得结果满足规范要求,说明盖下拱坝坝肩是稳定的.研究成果为实际工程提供了参考依据.

  15. USE THE REIMPLANTED TOOTH AS ABUTMENT FOR FIXED PAR TIAL DENTURE

    Directory of Open Access Journals (Sweden)

    Golmoradizadeh

    2013-04-01

    Full Text Available ABSTRACT: OBJECTIVE: Use of the fixed partial denture is more favorable t han the removable partial denture for my patient, she complained about e dentulism in upper right side and a little discomfort with second upper premolar. Clinical examin ation shows the tooth was crown less and radio graphically tooth had a big periapical lesi on with poor prognosis. METHOD: After root canal treatment and extraction the tooth, clea n and irrigate the socket, we are implanted it with hydroxyapatite again and follow the patient for six months. After six months, radio graph shows that the tooth was in ideal condition without mobility, then the tooth has used as an abutment for fixed partial denture with canine and 2 nd molar in order to have a better prognosis we used semi precision attachment, and foll ow her for three years. RESULT: Three years follow the patient shows the tooth is in an ac ceptable condition radio-graphically without mobility and patient was comfortable esthetically a nd functionally. CONCLUSION: In my opinion in this case use of the hydroxyapatite, crown lengthening during the re- implantation and use the semi precision attachment was the reaso n of increase the prognosis after treatment

  16. Effects of Dental Implant-abutment Interfaces on the Reliability of Implant Systems

    Directory of Open Access Journals (Sweden)

    Zhang Xiao

    2016-01-01

    Full Text Available In this paper, by analyzing the effects of two different kinds of implant-abutment connection interfaces under the same working condition on the mechanical and fatigue performances of the implant system as well as on the surrounding bones, we intend to study such effects on the reliability of the implants and provide a theoretical basis for the design and clinical application of dental implant systems. For the purpose, we adopt a 3-D modeling method to establish the model, and use FEA (finite element analysis to carry out static mechanic and fatigue analysis on the implant system and its surrounding bones; then we make the two implant systems, and carry out fatigue tests on a dynamic fatigue testing machine to verify the FEA results. After comparing the results from the two different systems, we find that the stress distribution and fatigue safety factor of the system which has deeper axial matching of the taper connection are better than those of the other system, that is to say, between the two major elements of a implant system, the axial length of the connecting taper and the size of the hexagon, the former has greater effects than the latter. When the axial matching is deeper, the stress distribution of the implant system will be better, the fatigue safety factor will be higher, and the implant system will be more reliable.

  17. An in vivo assessment of the effects of using different implant abutment occluding materials on implant microleakage and the peri-implant microbiome

    Science.gov (United States)

    Rubino, Caroline

    Microleakage may be a factor in the progression of peri-implant pathology. Microleakage in implant dentistry refers to the passage of bacteria, fluids, molecules or ions between the abutment-implant interface to and from the surrounding periodontal tissues. This creates a zone of inflammation and reservoir of bacteria at the implant-abutment interface. Bone loss typically occurs within the first year of abutment connection and then stabilizes. It has not yet been definitively proven that the occurrence of microleakage cannot contribute to future bone loss or impede the treatment of peri-implant disease. Therefore, strategies to reduce or eliminate microleakage are sought out. Recent evidence demonstrates that the type of implant abutment channel occluding material can affect the amount of microleakage in an in vitro study environment. Thus, we hypothesize that different abutment screw channel occluding materials will affect the amount of observed microleakage, vis-a-vis the correlation between the microflora found on the abutment screw channel occluding material those found in the peri-implant sulcus. Additional objectives include confirming the presence of microleakage in vivo and assessing any impact that different abutment screw channel occluding materials may have on the peri-implant microbiome. Finally, the present study provides an opportunity to further characterize the peri-implant microbiome. Eight fully edentulous patients restored with at dental implants supporting screw-retained fixed hybrid prostheses were included in the study. At the initial appointment (T1), the prostheses were removed and the implants and prostheses were cleaned. The prostheses were then inserted with polytetrafluoroethylene tape (PTFE, TeflonRTM), cotton, polyvinyl siloxane (PVS), or synthetic foam as the implant abutment channel occluding material and sealed over with composite resin. About six months later (T2), the prostheses were removed and the materials collected. Paper

  18. Transpulmonary computed tomography-guided radiofrequency ablation of liver neoplasms abutting the diaphragm with multiple bipolar electrodes

    Directory of Open Access Journals (Sweden)

    Q Zhang

    2015-01-01

    Full Text Available Background: Neoplasm abutting the diaphragm is one kind of the special sites of liver neoplasms treated with radiofrequency ablation (RFA, the purpose of this study is to evaluate the feasibility and safety of computed tomography (CT-guided RFA of liver neoplasms abutting the diaphragm with multiple bipolar electrodes sequentially passing through the lung parenchyma. Materials and Methods: 37 patients were treated with transpulmonary CT-guided RFA. Technical success rate, perioperative complications, and local tumor progression were investigated. Results: The number of electrode (s sequentially passing through the lung parenchyma (NPLP was 1 electrode in 20 patients, 2 electrodes in 14 cases, and 3 electrodes in 3 cases. Technical success rate was 100%. The most of the perioperative complications were self-limiting and mainly included pneumothorax (11 cases, 2 needed percutaneous drainage, hemorrhage of the electrode track in the lung parenchyma (6 cases, a small amount of hemoperitoneum in perihepatic space (8 cases and discomfort of the right shoulder (7 cases. Local tumor progression occurred in 6 cases during the follow-up (3–12 months. Multivariate logistic regression analysis showed that the incidence of pneumothorax was not related to NPLP (P = 0.50, length of the electrode (s in the lung parenchyma (P = 0.18, types of anesthesia (P = 0.10, and indwelling time of the electrode (s in the lung parenchyma (P = 0.28. Conclusion: CT-guided RFA of liver neoplasms abutting the diaphragm with multiple bipolar electrodes sequentially passing through the lung parenchyma is a feasible and safe therapeutic option.

  19. Carpal Tunnel Cross-Sectional Area Affected by Soft Tissues Abutting the Carpal Bones.

    Science.gov (United States)

    Gabra, Joseph N; Li, Zong-Ming

    2013-02-01

    The carpal tunnel accommodates free movement of its contents, and the tunnel's cross-sectional area is a useful morphological parameter for the evaluation of the space available for the carpal tunnel contents and of potential nerve compression in the tunnel. The osseous boundary of the carpal bones as the dorsal border of the carpal tunnel is commonly used to determine the tunnel area, but this boundary contains soft tissues such as numerous intercarpal ligaments and the flexor carpi radialis tendon. The aims of this study were to quantify the thickness of the soft tissues abutting the carpal bones and to investigate how this soft tissue influences the calculation of the carpal tunnel area. Magnetic resonance images were analyzed for eight cadaveric specimens. A medical balloon with a physiological pressure was inserted into an evacuated tunnel to identify the carpal tunnel boundary. The balloon-based (i.e. true carpal tunnel) and osseous-based carpal tunnel boundaries were extracted and divided into regions corresponding to the hamate, capitate, trapezoid, trapezium, and transverse carpal ligament (TCL). From the two boundaries, the overall and regional soft tissue thicknesses and areas were calculated. The soft tissue thickness was significantly greater for the trapezoid (3.1±1.2mm) and trapezium (3.4±1.0mm) regions than for the hamate (0.7±0.3mm) and capitate (1.2±0.5mm) regions. The carpal tunnel area using the osseous boundary (243.0±40.4mm(2)) was significantly larger than the balloon-based area (183.9±29.7mm(2)) with a ratio of 1.32. In other words, the carpal tunnel area can be estimated as 76% (= 1/1.32) of the osseous-based area. The abundance of soft tissue in the trapezoid and trapezium regions can be attributed mainly to the capitate-trapezium ligament and the flexor carpi radialis tendon. Inclusion of such soft tissue leads to overestimations of the carpal tunnel area. Correct quantification of the carpal tunnel area aids in examining carpal

  20. Carpal Tunnel Cross-Sectional Area Affected by Soft Tissues Abutting the Carpal Bones.

    Science.gov (United States)

    Gabra, Joseph N; Li, Zong-Ming

    2013-02-01

    The carpal tunnel accommodates free movement of its contents, and the tunnel's cross-sectional area is a useful morphological parameter for the evaluation of the space available for the carpal tunnel contents and of potential nerve compression in the tunnel. The osseous boundary of the carpal bones as the dorsal border of the carpal tunnel is commonly used to determine the tunnel area, but this boundary contains soft tissues such as numerous intercarpal ligaments and the flexor carpi radialis tendon. The aims of this study were to quantify the thickness of the soft tissues abutting the carpal bones and to investigate how this soft tissue influences the calculation of the carpal tunnel area. Magnetic resonance images were analyzed for eight cadaveric specimens. A medical balloon with a physiological pressure was inserted into an evacuated tunnel to identify the carpal tunnel boundary. The balloon-based (i.e. true carpal tunnel) and osseous-based carpal tunnel boundaries were extracted and divided into regions corresponding to the hamate, capitate, trapezoid, trapezium, and transverse carpal ligament (TCL). From the two boundaries, the overall and regional soft tissue thicknesses and areas were calculated. The soft tissue thickness was significantly greater for the trapezoid (3.1±1.2mm) and trapezium (3.4±1.0mm) regions than for the hamate (0.7±0.3mm) and capitate (1.2±0.5mm) regions. The carpal tunnel area using the osseous boundary (243.0±40.4mm(2)) was significantly larger than the balloon-based area (183.9±29.7mm(2)) with a ratio of 1.32. In other words, the carpal tunnel area can be estimated as 76% (= 1/1.32) of the osseous-based area. The abundance of soft tissue in the trapezoid and trapezium regions can be attributed mainly to the capitate-trapezium ligament and the flexor carpi radialis tendon. Inclusion of such soft tissue leads to overestimations of the carpal tunnel area. Correct quantification of the carpal tunnel area aids in examining carpal

  1. Dental devices; reclassification of root-form endosseous dental implants and endosseous dental implant abutments. Final rule.

    Science.gov (United States)

    2004-05-12

    The Food and Drug Administration (FDA) is reclassifying root-form endosseous dental implants and endosseous dental implant abutments from class III to class II (special controls). Root-form endosseous dental implants are intended to be surgically placed in the bone of the upper or lower jaw arches to provide support for prosthetic devices, such as artificial teeth, in order to restore the patient's chewing function. Endosseous dental implant abutments are separate components that are attached to the dental implant and intended to aid in prosthetic rehabilitation. FDA is reclassifying these devices on its own initiative on the basis of new information. Elsewhere in this issue of the Federal Register, FDA is announcing the availability of the guidance document that will serve as the special control for these devices. FDA is taking this action under the Federal Food, Drug, and Cosmetic Act (the act), as amended by the Medical Device Amendments of 1976 (the 1976 amendments), the Safe Medical Devices Act of 1990, the Food and Drug Administration Modernization Act of 1997, and the Medical Device User Fee and Modernization Act of 2002. PMID:15141676

  2. In vitro infrared thermography assessment of temperature peaks during the intra-oral welding of titanium abutments

    Science.gov (United States)

    Degidi, Marco; Nardi, Diego; Sighinolfi, Gianluca; Merla, Arcangelo; Piattelli, Adriano

    2012-07-01

    Control of heat dissipation and transmission to the peri-implant area during intra-oral welding is very important to limit potential damage to the surrounding tissue. The aim of this in vitro study was to assess, by means of thermal infrared imaging, the tissue temperature peaks associated with the thermal propagation pathway through the implants, the abutments and the walls of the slot of the scaffold, generated during the welding process, in three different implant systems. An in vitro polyurethane mandible model was prepared with a 7.0 mm v-shape slot. Effects on the maximum temperature by a single welding procedure were studied using different power supplies and abutments. A total of 36 welding procedures were tested on three different implant systems. The lowest peak temperature along the walls of the 7.0 mm v-shaped groove (31.6 ± 2 °C) was assessed in the specimens irrigated with sterile saline solution. The highest peak temperature (42.8 ± 2 °C) was assessed in the samples with a contemporaneous power overflow and premature pincers removal. The results of our study suggest that the procedures used until now appear to be effective to avoid thermal bone injuries. The peak tissue temperature of the in vitro model did not surpass the threshold limits above which tissue injury could occur.

  3. Stock Versus CAD/CAM Customized Zirconia Implant Abutments - Clinical and Patient-Based Outcomes in a Randomized Controlled Clinical Trial

    NARCIS (Netherlands)

    Schepke, Ulf; Meijer, Henny J A; Kerdijk, Wouter; Raghoebar, Gerry M; Cune, Marco

    2016-01-01

    BACKGROUND: Single-tooth replacement often requires a prefabricated dental implant and a customized crown. The benefits of individualization of the abutment remain unclear. PURPOSE: This randomized controlled clinical trial aims to study potential benefits of individualization of zirconia implant ab

  4. History, observation and mathematical models in the seismic analysis of the Valadier abutment area in the Colosseum

    Directory of Open Access Journals (Sweden)

    D. D'Ayala

    1995-06-01

    Full Text Available The present work aimed to outline the need to investigate different fields of research to interpret the structural behaviour of a monument as complex as the Colosseum. It is shown how defining the numerical models first. then refining them, followed by interpretation of results. is strictly linked with the inforination gathered from historical records and observation of the ~nonumenta s it is today. The study is confined to the area of the Valadier abutment. analysing its state and its seismic behaviour before and after the XIX century restoration using different ilumerical tools, from the elastic modal analysis to the non linear step by step time history direct integration. The procedure comparatiely evaluates the reliability in the interpretation of the results and identifies future lines or research.

  5. Free-end saddle length influence on stress level in unilateral complex partial denture abutment teeth and retention elements

    Directory of Open Access Journals (Sweden)

    Patrnogić Vesna

    2013-01-01

    Full Text Available Background/Aim. Different types of dental restorations are used for the therapy of unilateral free-end saddle edentulism. Unilateral complex partial denture is one of the indications for the Kennedy class II partial edentulism. The abscence of major connector and denture plate is an advantage compared to the conventional restorations, because of better comfort and shorter period of adaptation. The aim of the study was to analyse the influence of free-end saddle length change on the behaviour of unilateral complex partial denture supporting structures. Methods. Stress levels of the canine and the first premolar as retentional teeth and the attachments were tested under the influence of physiological forces with the loading point shifting distally in relation to the saddle length change. A virtual real size 3D model of the fixed part of the restoration (the canine and the first premolar with milled crowns was created using the CATIA computer program. It was connected to the mobile part of partial denture with the SD snap in latch attachment. Mobile part of the restoration was designed in the region of 2, 3 and 4 lateral teeth (second premolar, first, second and third molar. By using the finite element method (FEM stress levels analysis was performed under the load of physiological forces of 150 N in the free-end saddle teeth zone. Results. The results of analysis show that physiological forces cause a different stress distribution on the abutment teeth and the attachment, depending on the saddle length. Conclusion. The stress level values obtained for the abutment teeth as well as the attachment are far lower than the marginal ones. The behaviour of the system changes under this defined stress, but no plastic deformation occurs.

  6. Clinical Outcome of Inter-Proximal Papilla between a Tooth and a Single Implant Treated with CAD/CAM Abutments: a Cross-Sectional Study

    Directory of Open Access Journals (Sweden)

    Tiago Borges

    2012-09-01

    Full Text Available Objectives: The aim of this study was to assess the clinical outcomes achieved with Computer-Assisted Design/Computer-Assisted Manufacturing implant abutments in the anterior maxilla.Material and Methods: Nineteen patients with a mean age of 41 (range form 26 to 63 years, treated with 21 single tooth implants and 21 Computer-Assisted Design/Computer-Assisted Manufacturing (CAD/CAM abutments in the anterior maxillary region were included in this study. The patients followed 4 criteria of inclusion: (1 had a single-tooth implant in the anterior maxilla, (2 had a CAD/CAM abutment, (3 had a contralateral natural tooth, (4 the implant was restored and in function for at least 6 months up to 2 years. Cases without contact point were excluded. Presence/absence of the interproximal papilla, inter tooth-implant distance (ITD and distance from the base of the contact point to dental crest bone of adjacent tooth (CPB were accessed. Results: Forty interproximal spaces were evaluated, with an average mesial CPB of 5.65 (SD 1.65 mm and distal CPB of 4.65 (SD 1.98 mm. An average mesial ITD of 2.49 (SD 0.69 mm and an average distal ITD of 1.89 (SD 0.63 mm were achieved. Papilla was present in all the interproximal spaces accessed. Conclusions: The restoration of dental implants using CAD/CAM abutments is a predictable treatment with improved aesthetic results. These type of abutments seem to help maintaining a regular papillary filling although the variations of the implant positioning or the restoration teeth relation.

  7. Clinical Outcome of Inter-Proximal Papilla between a Tooth and a Single Implant Treated with CAD/CAM Abutments: a Cross-Sectional Study

    Science.gov (United States)

    Lima, Tiago; Carvalho, Ágata; Carvalho, Vasco

    2012-01-01

    ABSTRACT Objectives The aim of this study was to assess the clinical outcomes achieved with Computer-Assisted Design/Computer-Assisted Manufacturing implant abutments in the anterior maxilla. Material and Methods Nineteen patients with a mean age of 41 (range form 26 to 63) years, treated with 21 single tooth implants and 21 Computer-Assisted Design/Computer-Assisted Manufacturing (CAD/CAM) abutments in the anterior maxillary region were included in this study. The patients followed 4 criteria of inclusion: (1) had a single-tooth implant in the anterior maxilla, (2) had a CAD/CAM abutment, (3) had a contralateral natural tooth, (4) the implant was restored and in function for at least 6 months up to 2 years. Cases without contact point were excluded. Presence/absence of the interproximal papilla, inter tooth-implant distance (ITD) and distance from the base of the contact point to dental crest bone of adjacent tooth (CPB) were accessed. Results Forty interproximal spaces were evaluated, with an average mesial CPB of 5.65 (SD 1.65) mm and distal CPB of 4.65 (SD 1.98) mm. An average mesial ITD of 2.49 (SD 0.69) mm and an average distal ITD of 1.89 (SD 0.63) mm were achieved. Papilla was present in all the interproximal spaces accessed. Conclusions The restoration of dental implants using CAD/CAM abutments is a predictable treatment with improved aesthetic results. These type of abutments seem to help maintaining a regular papillary filling although the variations of the implant positioning or the restoration teeth relation. PMID:24422016

  8. EPS材料在防治桥头跳车中的应用%Application of EPS Material in the Control of Vehicle Jumping at Bridge Abutment

    Institute of Scientific and Technical Information of China (English)

    焦莉

    2012-01-01

    EPS (Expanded Polystyrene)materials have the properties of super light, water resistance, antt-ageing and good mechanical property and convenience in construction. Because of its good properties.EPS has been widely used in decreasing the different settlement at the bridge abutment and preventing the jump at the bridge abutment. To ensure effective application of EPS, the embankment fill should be executed according to constructing quality standard.%EPS材料具有超轻、耐水,不易老化、力学性能良好和施工便捷等优点,在处理桥台和路基相接处差异沉降,防治桥头跳车中得到广泛应用.为保证EPS应用效果,路基应按照施工质量标准进行填筑.

  9. A Stress Analysis on Abutment Teeth of Dowel Cemented Fixed Partial Dentures : On the effect of the resorption of alveoar bone

    OpenAIRE

    KATAOKA, SHIGERU; KOSAKA, SHIGERU; TSUCHIYA, SOHICHIRO; AMARI, MITSUHARU

    1995-01-01

    Stress in abutment teeth with cemented dowels and those with crown margins in fixed-fixed and cantilever bridges that resorp alveolar bone were analyzed by a two dimensional finite element method. Stress in all parts of the dentin in both bridges increased with the resorption of alveolar bone. Moreover, in th dentin and apex of the dowel in cantilever bridges, extreme stress when there were large amounts of resorption of alveolar bone, was seen. Therefore, in cantilevers bridges, cemented dow...

  10. Safety evaluation of replacement reinforcement quality in abutment contact zones of ultra-high arch dam in first impoundment period based on prototype monitoring

    Directory of Open Access Journals (Sweden)

    Bo HU

    2012-06-01

    Full Text Available Reinforcement quality evaluation at the abutment is an important research direction. Prototype monitoring and theoretical derivation were integrated to study the replacement reinforcement quality in abutment contact zones of the Xiaowan ultra-high arch dam. The principles of monitoring layout and design are introduced in detail. Prototype monitoring shows that the increment of the interfacial compressive stress is much larger in the impoundment stage than in the regulating stage. The water pressure and time-effect are two main factors affecting the interfacial stress. The time-effect is the key factor in the initial impoundment stage, and the water pressure is the key factor after impoundment. The contact properties are significantly improved by grouting. This study shows that there are three typical stages in the joint opening hydrographs, namely the compression stage, opening stage, and stable stage. There is a nonlinear relationship between the joint opening and temperature, which can be well described by the S-function. In conclusion, the reinforcement effect is satisfying, and the abutment is safe.

  11. Improving the long-term stability of Ti6Al4V abutment screw by coating micro/nano-crystalline diamond films.

    Science.gov (United States)

    Xie, Youneng; Zhou, Jing; Wei, Qiuping; Yu, Z M; Luo, Hao; Zhou, Bo; Tang, Z G

    2016-10-01

    Abutment screw loosening is the most common complication of implanting teeth. Aimed at improving the long-term stability of them, well-adherent and homogeneous micro-crystalline diamond (MCD) and nano-crystalline diamond (NCD) were deposited on DIO(®) (Dong Seo, Korea) abutment screws using a hot filament chemical vapor deposition (HFCVD) system. Compared with bare DIO(®) screws, diamond coated ones showed higher post reverse toque values than the bare ones (pcoated disks showed lower friction coefficients of 0.15 and 0.18 in artificial saliva when countered with ZrO2 than that of bare Ti6Al4V disks of 0.40. Though higher cell apoptosis rate was observed on film coated disks, but no significant difference between MCD group and NCD group. And the cytotoxicity of diamond films was acceptable for the fact that the cell viability of them was still higher than 70% after cultured for 72h. It can be inferred that coating diamond films might be a promising modification method for Ti6Al4V abutment screws. PMID:27393893

  12. Live-Load Testing Application Using a Wireless Sensor System and Finite-Element Model Analysis of an Integral Abutment Concrete Girder Bridge

    Directory of Open Access Journals (Sweden)

    Robert W. Fausett

    2014-01-01

    Full Text Available As part of an investigation on the performance of integral abutment bridges, a single-span, integral abutment, prestressed concrete girder bridge near Perry, Utah was instrumented for live-load testing. The live-load test included driving trucks at 2.24 m/s (5 mph along predetermined load paths and measuring the corresponding strain and deflection. The measured data was used to validate a finite-element model (FEM of the bridge. The model showed that the integral abutments were behaving as 94% of a fixed-fixed support. Live-load distribution factors were obtained using this validated model and compared to those calculated in accordance to recommended procedures provided in the AASHTO LRFD Bridge Design Specifications (2010. The results indicated that if the bridge was considered simply supported, the AASHTO LRFD Specification distribution factors were conservative (in comparison to the FEM results. These conservative distribution factors, along with the initial simply supported design assumption resulted in a very conservative bridge design. In addition, a parametric study was conducted by modifying various bridge properties of the validated bridge model, one at a time, in order to investigate the influence that individual changes in span length, deck thickness, edge distance, skew, and fixity had on live-load distribution. The results showed that the bridge properties with the largest influence on bridge live-load distribution were fixity, skew, and changes in edge distance.

  13. Findings of a Four-Year Randomized Controlled Clinical Trial Comparing Two-Piece and One-Piece Zirconia Abutments Supporting Single Prosthetic Restorations in Maxillary Anterior Region

    Directory of Open Access Journals (Sweden)

    Guerino Paolantoni

    2016-01-01

    Full Text Available The purpose of this randomized controlled study is to investigate the clinical results obtained over four years and incidence of complications associated with one- versus two-piece custom made zirconia anchorages, in single tooth implant-supported restorations of the maxillary anterior region. Sixty-five patients, with a total of 74 missing maxillary teeth, were selected in the period from February 2007 to July 2010. Two different ways of custom made zirconia abutment and final prosthetic restoration were evaluated: a standard zirconia abutment associated with a pressed layer of lithium disilicate with an all-ceramic cemented restoration versus one-piece restoration with the facing porcelain fired and pressed straight to the custom made zirconia abutment. In 29 cases, the restoration consisted of an all-ceramic restoration for cementation (two pieces; in 45 cases the restoration was a screw-retained restoration (one piece. Three all-ceramic restorations broke during the observation time. Two one-piece restorations fractured after 26 months. At follow-up examination there were no significant differences between one-piece and two-piece groups regarding the PI, BI, and MBL. Awaiting studies with longer follow-up times, a careful conclusion is that zirconia anchorages for single-implant restorations seem to demonstrate good short-term technical and biological results.

  14. The behavior of implant-supported dentures and abutments using the cemented cylinder technique with different resinous cements

    Directory of Open Access Journals (Sweden)

    Ivete Aparecida de Mathias Sartori

    2008-01-01

    Full Text Available Objective: Evaluate the behavior of implant-supported dentures and their components, made by cemented cylinder technique, using threetypes of resin cements. Methods: Fifty three patients, of whom 26 were women and 27 men, aged between 25 and 82 years. Results: With partial (54.43% and total (45.57% implant-supported dentures, of the Cone Morse, external and internal hexagon types (Neodent®, Curitiba, Brazil, totaling 237 fixations, were analyzed. The resin cements used were Panavia® (21.94%, EnForce® (58.23% and Rely X® (19.83% and the components were used in accordance with the Laboratory Immediate Loading - Neodent® sequence. The period of time of denture use ranged between 1 and 5 years. The results reported that 5(2.1% cylinders were loosened from metal structure (both belonging to Rely X group, 2(0.48% implants were lost after the first year of use, 16(6.75% denture retention screws wereloosened and 31(13.08% abutment screws were unloosened.Conclusion: The reasons for these failures probably are: metal structure internal retention failure, occlusal pattern, cementation technique and loading conditions. The cemented cylinder technique was effective when used in partial and total implant-supported rehabilitations, keeping prosthetic components stable, despite the resin cement utilized. However, further clinical studies must be conducted.

  15. Comparison of strain generated in bone by "platform-switched" and "non-platform-switched" implants with straight and angulated abutments under vertical and angulated load: A finite element analysis study

    Directory of Open Access Journals (Sweden)

    Susan Paul

    2013-01-01

    Full Text Available Purpose: The aim of this study was to evaluate the microstrain exhibited by bone around immediately loaded, platform-switched, and non-platform-switched implants under vertical and angled loading using a finite element analysis (FEA and also to evaluate whether platform-switched implants evoke a better response than non-platform-switched implants on a mechanical basis. Materials and Methods: Three-dimensional finite element study was undertaken to model and analyze an immediate loaded situation. FEA was chosen for this study since it is useful in determining the stress and strain around the dental implant. Bone responses to vertical and angulated loads on straight and angulated abutments (platform-switched and non-platform-switched abutments were evaluated. Results: Non-platform-switched abutments tend to exhibit a lower tensile stress and compressive stress but higher microstrain value (conducive to higher chance of bone resorption than platform-switched abutments. Ideal bone remodeling values of microstrain (50-3000 μϵ were exhibited by platform-switched straight abutments under vertical load and angled load (with an abutment-implant diameter difference of 1 mm. Conclusion: In spite of the obvious advantages, the practice of immediate loading is limited due to apprehension associated with compromised bone response and a higher rate of bone loss around an immediately loaded implant. The mechanical basis for the concept of "platform switching" in immediately loaded situation is analyzed in this context. The results of this limited investigation indicated that the ideal values of microstrain (50-3000 microstrain can be exhibited by platform switching of dental implants (with an abutment-implant diameter difference of 1 mm and can be considered as a better alternative for prevention of crestal bone loss when compared to non-platform-switched implants.

  16. Displacements Prediction in Double-Arch Dam Rock Abutment Using SPSS Software Based on Extensometer Readings Case study: Karun 4 Concrete Dam, Iran

    Directory of Open Access Journals (Sweden)

    Hadi kamali Bandpey

    2012-11-01

    Full Text Available In this study we present a method for Displacements Prediction in Double-Arch Dam Rock Abutment Using SPSS Software Based on Extensometer Readings. Displacement in dams is the most tangible and important parameter which could be crucial in their safety. Different elevation displacements are yielded by various loadings and the thrust force imposed on foundation and abutment. Most concrete dams are constructed on stone foundations. Displacements in foundation and abutment are measured by extensometers. Karun 4 Concrete dam is designed with 11 galleries, from elevation 1016 to 802 m, in the order from top elevation (dam crest elevation 1032 to the bottom elevation (dam foundation elevation 806 within the dam body. As a whole, 19 extensometers in the left bank, 17 in the right, and one more in the middle are implemented in the dam. Karun 4 dam has already been impounded with water up to the elevation 1003. Displacements in Karun 4 are recorded by extensometers whence water was leveled in 7 elevations 943.68, 953.36, 973.55, 983.28, 993.17, 1003.13. In this study, using SPSS we have tried to predict the displacements for a situation in which water will be elevated to the elevations 1013, 1023, 1032 in the future for elevations which are equipped with anchor. The most predicted displacement pertaining to the left bank when water was leveled to the elevation 1013, was 3.65 mms by R2 = 0.9997 for the implemented anchor. Proceeding further, as water is leveled to the elevations 1023 and 1033, the most predicted displacement respectively would be 4.31 and 5.66 by R2 = 0.9941; and is related to the anchor implemented in the elevation 936.05. The most predicted displacement for the right bank is 5.9397, 7.2347 and 8.6877 mms by R2 = 0.9995 for the elevation 888.128 m.

  17. Effects of Length and Inclination of Implants on Terminal Abutment Teeth and Implants in Mandibular CL1 Removable Partial Denture Assessed by Three-Dimensional Finite Element Analysis

    OpenAIRE

    Amir Fayaz; Alahyar Geramy; Yeganeh Memari; Zahra Rahmani Rahmani

    2016-01-01

    Objectives: This study sought to assess the effects of length and inclination of implants on stress distribution in an implant and terminal abutment teeth in an implant assisted-removable partial denture (RPD) using three-dimensional (3D) finite element analysis (FEA).  Materials and Methods: In this in vitro study, a 3D finite element model of a partially dentate mandible with a distal extension RPD (DERPD) and dental implants was designed to analyze stress distribution in bone around termin...

  18. The State of Prosthetic Bed Mucous Membrane and Periodontium of Abutment and Preserved Teeth in Conditions of Considerable and Total Loss of Teeth and Use of Removable Dentures

    OpenAIRE

    Vasylyshyn, U.

    2014-01-01

    The paper deals with the study of impact of considerable loss of teeth and long-term use of removable dentures on mucous membrane of prosthetic bed and periodontium of abutment and preserved teeth, and also impact on the appearance and course of inflammatory processes in these parts. Materials and research methods: the patients of Dentistry Centre of IFNMU clinic (105 people  from 45 to 70 years old) with considerable and total loss of teeth, treated by the removable dentures, were the object...

  19. Multicolor fluorescent in situ hybridization to define abutting and overlapping gene expression in the embryonic zebrafish brain

    Directory of Open Access Journals (Sweden)

    Hauptmann Giselbert

    2011-04-01

    Full Text Available Abstract Background In recent years, mapping of overlapping and abutting regulatory gene expression domains by chromogenic two-color in situ hybridization has helped define molecular subdivisions of the developing vertebrate brain and shed light on its basic organization. Despite the benefits of this technique, visualization of overlapping transcript distributions by differently colored precipitates remains difficult because of masking of lighter signals by darker color precipitates and lack of three-dimensional visualization properties. Fluorescent detection of transcript distributions may be able to solve these issues. However, despite the use of signal amplification systems for increasing sensitivity, fluorescent detection in whole-mounts suffers from rapid quenching of peroxidase (POD activity compared to alkaline phosphatase chromogenic reactions. Thus, less strongly expressed genes cannot be efficiently detected. Results We developed an optimized procedure for fluorescent detection of transcript distribution in whole-mount zebrafish embryos using tyramide signal amplification (TSA. Conditions for hybridization and POD-TSA reaction were optimized by the application of the viscosity-increasing polymer dextran sulfate and the use of the substituted phenol compounds 4-iodophenol and vanillin as enhancers of POD activity. In combination with highly effective bench-made tyramide substrates, these improvements resulted in dramatically increased signal-to-noise ratios. The strongly enhanced signal intensities permitted fluorescent visualization of less abundant transcripts of tissue-specific regulatory genes. When performing multicolor fluorescent in situ hybridization (FISH experiments, the highly sensitive POD reaction conditions required effective POD inactivation after each detection cycle by glycine-hydrochloric acid treatment. This optimized FISH procedure permitted the simultaneous fluorescent visualization of up to three unique transcripts

  20. Analysis on distribution law of the abutment pressure of the integrated coal beside the road-in packing for gob-side entry retaining in fully-mechanized caving face

    Institute of Scientific and Technical Information of China (English)

    Zhu Chuanqu; Liu Ze; Wang Weijun; Zhang Daobing

    2009-01-01

    The three-dimensional damage constitutive relationship of coal is established and distribution law of the abut-ment pressure of the integrated coal beside the road-in packing for gob-side entry retaining in fully-mechanized caving face under the effect of given deformation of the main roof is analyzed by the damage mechanics theory. And the rela-tionship between distribution of the abutment pressure and thickness of coal seam is explored. The presented result is of great theoretical significance and practical value to the study on stability control of the surrounding rock of road-in pack-ing for gob-side entry retaining in fully-mechanized caving face.

  1. In vitro synchrotron-based radiography of micro-gap formation at the implant–abutment interface of two-piece dental implants

    International Nuclear Information System (INIS)

    Micro-radiography using hard X-ray synchrotron radiation is the first potential tool to allow an evaluation of the mechanical behavior of the dental implant–abutment complex during force application, thus enabling the enhancement of the design of dental implants which has been based on theoretical analysis to date. Micro-gap formation at the implant–abutment interface of two-piece dental implants was investigated in vitro using high-resolution radiography in combination with hard X-ray synchrotron radiation. Images were taken with the specimen under different mechanical loads of up to 100 N. The aim of this investigation was to prove the existence of micro-gaps for implants with conical connections as well as to study the mechanical behavior of the mating zone of conical implants during loading. Synchrotron-based radiography in comparison with classical laboratory radiography yields high spatial resolution in combination with high contrast even when exploiting micro-sized features in highly attenuating objects. The first illustration of a micro-gap which was previously indistinguishable by laboratory methods underlines that the complex micro-mechanical behavior of implants requires further in vitro investigations where synchrotron-based micro-imaging is one of the prerequisites

  2. D型便梁加固既有桥台施工技术%Type D beam strengthened with abutment construction technology

    Institute of Scientific and Technical Information of China (English)

    张留

    2014-01-01

    Bao Xi railway double track two Dao Gou Bridge Abutment with both type D beam reinforcement, through the relationship between old and new, on line analysis of existing line is busy and so on, elaborates the technical measures of temporary pier construction, beam transport and installation, safety protection to ensure the operation safety of the line.%包西铁路复线二道沟大桥既有桥台采用D型便梁加固,通过对新旧线路关系、既有线路繁忙情况等方面的分析,详细阐述了临时支墩施工、便梁的运输及安装、既有线安全防护等确保线路运营安全的技术措施。

  3. 氧化锆基台在种植体支持的全瓷修复中的应用%The application of zirconia abutment in implant supported all - ceramic restoration

    Institute of Scientific and Technical Information of China (English)

    王大山; 杨建军; 邓悦; 吴品林; 杨振; 杨凤丽; 张慧敏

    2011-01-01

    目的 探讨氧化锆基台的应用及种植体支持的全瓷修复体的临床效果.方法 选择安多键内连接种植系统φ4.0×10ram种植体植入缺牙区,上颌植入6个月、下颌植入3个月后安装自制的氧化锆基台;将基台予以磨改预留修复间隙,取印模,灌制石膏模型;应用CAD/CAM制作全瓷冠、桥;将全瓷修复体与基台粘接固位;应用MINRAY口内数字X线摄片系统和X线摄片定位仪,拍摄安装氧化锆基台时和全瓷修复体粘接后36个月时的X线片进行测量,对比分析.结果 自制的氧化锆基台能与种植体顺利装配,应用该基台和CAD/CAM制作的全瓷冠、桥修复体完成的15例患者18颗种植义齿全瓷修复的即刻效果满意,追踪30-36个月,所有患者的种植义齿使用良好,修复体和基台均无松动脱落与折裂、折断,牙周无炎症及牙槽骨吸收,部分患者的牙槽骨显示增高,患者满意度高.结论 应用氧化锆基台配合CAD/CAM氧化锆全瓷冠、桥修复体,不仅可获得满意的美学效果,还有益于种植义齿周围组织的健康.%Objective ThiS study is to discuss the application of zirconia abutment and Lhe clinical results of the implant supponed all - ceramic restoration.Methods Embed the Anthogyr inter - joins implant system ( φ 4.0 × 10mm)into the edentulous region, install the self - made zirconia abutment after 6 months maxilla implantation or 3 months mandible implantation; Then the abutment is ground to reserve restoration space and the impression is made to cast plaster mould; Make the all - ceramic crown/ bridge by CAD/CAM before adhere and fix the all - ceramic restoration with the abutment; Use MINRAY digital X - ray shooting system and X - ray holders system to shoot X - ray at the time of zirconia abutment installation and 36 months after the adhesion of the all - ceramic restoration then carry out measurement and comparative analysis.Results The self - made zirconia abutment can match well

  4. Clinical research on abutment gingivitis and secondary caries after partial centure fixing%固定义齿修复后基牙牙龈炎、继发龋的临床观察

    Institute of Scientific and Technical Information of China (English)

    徐频频; 林燕; 麻广丽; 周国锋

    2014-01-01

    目的:观察固定义齿修复后基牙牙龈炎与继发龋的临床表现,对比两种疾病的牙周指标。方法选取本院口腔科接受固定义齿修复的患者共50例:25例患者接受治疗后发生基牙牙龈炎,设定为A组;25例患者接受治疗后发生继发龋,设定为B组,对比两组患者的菌斑指数、社区牙周治疗需要指数、探诊深度以及菌斑细菌分布。结果 A组与B组患者的菌斑指数、社区牙周治疗需要指数、探诊深度差异无统计学意义,A组与B组的菌斑细菌分布差异有统计学意义(P<0.05)。结论固定义齿修复后基牙牙龈炎与继发龋的发生率较高,基牙牙龈炎与继发龋患者的牙周指标无显著差异,因此医生应注重患者固定义齿修复后的健康宣教,以降低牙周疾病的发生率。%Objective To observe the clinical manifestation of abutment gingivitis and secondary caries after partial denture fixing,and to have a comparison of periodontal index between abutment gingivitis and secondary caries. Meth-ods Fifty patients who received partial denture fixing were divided randomly into two groups.Twenty-five patients had abutment gingivitis,and twenty-five patients had secondary caries. The PLI,CPITN,PD and the classification of bacte-rial of two groups were compared. Results The PLI,CPITN,PD of both groups had no difference,but the classification of bacterial in both groups were significantly different (P<0.05). Conclusion The incidence of abutment gingivitis and secondary caries after partial denture fixing is massive. Although the periodontal index between patients who had abut-ment gingivitis or secondary caries after partial denture fixing have no difference. Doctors should strengthen the health education after treatment to reduce the rate of periodontal disease.

  5. Factors associated with fixed partial denture abutment gingivitis and secondary caries%固定义齿基牙牙龈炎继发龋菌斑因素的研究

    Institute of Scientific and Technical Information of China (English)

    李文晋; 李瑛; 牛金亮; 金慧兰; 王涛; 刘艳

    2011-01-01

    Objective To investigate the factors associated with fixed partial denture abutment gingivitis and secondary caries.Methods Forty patients with gingivitis or secondary caries after fixed partial denture abutment were included in this study, comprising 57 abutment teeth in all (42 with gingivitis and 15 with secondary caries).The peridontal index of abutment tooth, the severity of secondmry caries and constituent ratio of dental plaques were investigated and compared between the two conditions.Results Peridontal index was comparable between patients with abutment gingivitis and those with secondary caries (P>0.05).The constituent ratio of Staphylococci in dental plaque was significantly higher in secondary caries than in abutment gingivitis, while the constituent ratios of Spirochaetes, Fusobocterium and Eubacterium was lower in secondary caries than in abutment gingivitis (P<0.05).Conclusion It is as equally important to protect abutment peridontal tissue after treatment.Patients should be educated to keep good oral cavity hygiene and regular clinic visit in order to reduce gingivitis and secondary caries.%目的 通过对固定义齿修复后基牙牙龈炎、继发龋的观察,分析基牙牙龈炎、继发龋与牙周组织及菌斑的关系.方法 收集固定义齿修复后出现牙龈炎、继发龋的病例40例,共57颗固定义齿修复体,其中基牙牙龈炎42颗,继发龋15颗.观察基牙的牙周指数、继发龋坏的情况以及菌斑细菌构成比.结果 基牙牙龈炎组与继发龋组的牙周指数差异无统计学意义(P>0.05).基牙继发龋组牙菌斑中球菌的构成比高于基牙牙龈炎组,螺旋体、梭形杆菌和真杆菌的构成比低于基牙牙龈炎组,差异有统计学意义(P<0.05).结论 固定义齿修复后牙周组织的保护同样很重要.固定义齿修复后要对患者进行口腔卫生宣教,指导患者注意保持口腔卫生,定期复诊,以减少牙龈炎、继发龋的发生.

  6. 采动剧烈垮冒煤巷的支承压力分布规律研究%Study on Abutment Pressure Distribution Law in Collapse Coal Roadway with Mining-induced Violently

    Institute of Scientific and Technical Information of China (English)

    李开晴; 何富连; 严红; 韩红强

    2011-01-01

    针对阳煤集团新元公司采动剧烈的垮冒煤巷普遍存在顶板严重下沉、巷帮严重臌帮和巷道底鼓等问题,对煤柱支承压力进行了现场实测和计算机三维数值模拟,分析研究采动剧烈影响下的煤巷支承压力分布规律,得出应力集中系数平均值达3.2及煤巷支承压力的分布范围,从而为采动剧烈垮冒煤巷的支护方案设计提供科学依据。%Aiming at the problems such as roof severe subsidence,the ribs of roadway ingression and floor heave in roadway of Yangguan coal industry Co.Ltd Xinyuan corporation,abutment pressure of coal pillars are analyzed by field measurements and 3D numerical simulation to research on the distribution law of abutment pressure in the mining-induced violently collapse coal roadway.The average value of stress concentration factor is 3.2,and the abutment distribution scale is obtained.These results can supply the scientific basis for the supporting scheme design.

  7. 西南某水电站坝肩抗力体长期稳定性分析%NUMERICAL LONG-TERM STABILITY OF DAM ABUTMENT RESISTANCE BODY FOR A HYDROPOWER STATION IN SOUTHWEST CHINA

    Institute of Scientific and Technical Information of China (English)

    杨根兰; 黄润秋

    2011-01-01

    Long-term stability of dam abutment resistance body is very important for a hydropower station. The a-butment resistance body stability of complex rock mass dam under the action of water thrust is particularly important. There are widely altered rocks in the dam abutment of a hydropower station in Southwest China. On the basis of altered rock rheological property and its viscous-elastic-plastic constitutive model, the stress and deformation fields characteristics in the resistance body slope have been simulated with 3D numerical method during the reservoir operation period. The study results show that te third stress field is formed after 6months of water storage. The dam abutment resistance body is in the most dangerous situation. Local destruction between altered rock and fault may appear. According to the simulated deformation value and plastic zones after 5 years of water storage,the abutment resistance body of the whole dam is in a long-term stable state.%水电工程对坝肩抗力体长期稳定性要求极高,因此,对于复杂岩土体坝肩抗力体在水推力作用下的稳定性评价显得尤为重要.西南某水电工程坝肩岩体普遍发育有蚀变岩,因此需对其抗力体长期稳定性进行评价.根据考虑蚀变岩体流变特性的黏-弹-塑性本构模型,对水库蓄水运行期抗力体边坡应力、形变场等特征进行了三维数值模拟研究.研究表明,坝肩抗力体在蓄水6个月后“三次应力场”基本形成,即此时抗力体处于最危险状态,可能会出现蚀变岩带与断层交叉部位的局部破坏;通过对蓄水5a后模拟得到的变形值及塑性区变化情况分析,得出坝肩抗力体整体上是长期稳定的.

  8. Discussion about the Shoulderless and Local microshoulder Abutment Tooth Preparation of Full Crown Restoration%牙体牙列缺损美容修复牙体预备方法的临床探讨

    Institute of Scientific and Technical Information of China (English)

    刘建东; 刘曼丽; 周嘉洪

    2011-01-01

    Objective:In order to adapt the demand that patients who don't want to destroy their natural tooth tissue by routine method at basic hospital.To discuss the method that shouldless and local microshoulder abutment tooth preparation of full crown for retaining tissue of tooth and shorting the time of tooth preparation.Methods: 995 abutment tooth which from 490 cases have been cured by the method of shouldless and local microshoulder abutment tooth preparation by writer in 10 years from 2001 to 2010.Among the cases ,Swaged metal full crown which formed the line concave the crown edge of dental cervix but not any shoulder preparation.PFM which formed the microshoulder on the labial or buccal surface and the line concave at the proximal or lingual surface in thc abutment tooth.Results: By revisiting and observing the above-mentioned 490 cases during one to seven years.The restorations of 483 cases are all in good condition and there are no abnormality in pulp、periodontal and periapical tissue besides four cases which the local edge of porcelain veneer crown appear metallochrome lightly and three cases which appear topical stenopaic at the edge of porcelain veneer crown.There are no dental canies and breaking, the restorations have not been destroyed and moved.Conclusion:Compare the method which mentioned with the routine method can retain more tissue of tooth, accentuate the restention and resisting force of abutment tooth, shorten the time of tooth preparation and reduce the possible nuisance to tooth, gingival and paradentium during the course of abutment tooth preparation which allay patients and relief their trepidation to abutment tooth preparation.%目的:为适应基层农村患者惧怕磨牙和不愿接受常规牙体预备的要求,探讨一种微小肩台的全冠牙体预备方法,以减少因预备肩台而磨去较多牙体组织和缩短口内操作时间,减轻患者痛苦.方法:从2001年至2010年的10年时间里,共对490例患者的995颗需做

  9. Prevention of bacterial leakage at implant-abutment connection level: an in vitro study of the efficacy of three different implant systems.

    Science.gov (United States)

    Carinci, F; Lauritano, D; Cura, F; Lopez, M A; Andreasi Bassi, M; Confalone, L; Pezzetti, F

    2016-01-01

    Peri-implantitis is the main cause of implant failures. Peri-implantitis is provoked by the presence of bacterial infiltration around Implant-Abutment Connection (IAC). Reduction of bacterial leakage may be achieved by improving the accuracy and precision of the two pieces of IAC. The aim of the present in vitro study was to evaluate bacterial microleakage from the inside to the outside of the IAC, testing the efficacy of three new designs of internal conical connection (FN - nano-fix -, NQ - uNiQo - and Elisir implant systems by FMD, Rome, Italy). To identify the efficacy of three new IAC, the passage of genetically modified Escherichia coli across IAC was evaluated. A total of 17 implants were used (5 FN, 6 NQ and 6 Elisir). All implants were immerged in a bacterial culture for 48 h and bacteria amount was then measured inside and outside IAC with Real-time PCR. Bacterial quantification was performed by Real-Time Polymerase Chain Reaction using the absolute quantification with the standard curve method. In all the tested implants, bacteria were found in the inner side, with a median percentage of 1.9% FN, 1.4% NQ and 2.6% Elisir. The analysis revealed that in both cases (internally and externally), bacteria grew in the first 48 hours but subsequently started to die, probably due to nutrient consumption. Of the three, the most efficacious connection was NQ. Within the limitations of this study, it was concluded that the best implant connection reducing bacterial leakage al IAC level was NQ (NQ implant system by FMD, Rome, Italy). PMID:27469551

  10. A Novel Scheme and Evaluations on a Long-Term and Continuous Biosensor Platform Integrated with a Dental Implant Fixture and Its Prosthetic Abutment.

    Science.gov (United States)

    Li, Yu-Jung; Lu, Chih-Cheng

    2015-01-01

    A miniature intra-oral dental implant system including a built-in biosensor device is proposed in this article. The dental implant system, or platform, is replaced over maxilla and allows relatively non-invasive procedures for a novel biosensing scheme for human blood analysis. Due to placement of the implant fixture, periodontal ligaments and the pulp structure, which are regarded as the main origin of pain, are thus removed, and long-term, continuous blood analysis and management through maxillary bone marrow becomes achievable through the dental implant platform. The new pathway of biological sensing is for the first time presented to realize an accurate and painless approach without injections. The dental implant system mainly consists of an implant fixture and a prosthetic abutment, a biosensor module, a bluetooth 4.0 wireless module and a dc button cell battery. The electrochemical biosensor possesses three electrodes, including working, reference and counter ones, which are arranged to pass through the titanium implant fixture below the biosensor module. The electrodes are exposed to the blood pool inside the maxillary bone marrow and perform oxidation/reduction reactions with the coating of biosensing enzyme. To prove the proposed platform, the immobilization process of glucose oxidase (GOD) enzyme and in vitro detections of glucose levels are successfully carried out, and proven sensitivity, linearity and repeatability of the glucose biosensor system are obtained. Moreover, a preliminary canine animal model adopting the new pathway shows significant consistency with the traditional method through dermal pricks for blood sugar detection. Despite the prospective results, further challenges in engineering implementation and clinical practices are addressed and discussed. In brief, the novel biosensing pathway and intra-oral biosensor platform may increasingly reveal their promising value and feasibilities in current bio-medical analysis, diagnosis, drug

  11. A Novel Scheme and Evaluations on a Long-Term and Continuous Biosensor Platform Integrated with a Dental Implant Fixture and Its Prosthetic Abutment

    Directory of Open Access Journals (Sweden)

    Yu-Jung Li

    2015-09-01

    Full Text Available A miniature intra-oral dental implant system including a built-in biosensor device is proposed in this article. The dental implant system, or platform, is replaced over maxilla and allows relatively non-invasive procedures for a novel biosensing scheme for human blood analysis. Due to placement of the implant fixture, periodontal ligaments and the pulp structure, which are regarded as the main origin of pain, are thus removed, and long-term, continuous blood analysis and management through maxillary bone marrow becomes achievable through the dental implant platform. The new pathway of biological sensing is for the first time presented to realize an accurate and painless approach without injections. The dental implant system mainly consists of an implant fixture and a prosthetic abutment, a biosensor module, a bluetooth 4.0 wireless module and a dc button cell battery. The electrochemical biosensor possesses three electrodes, including working, reference and counter ones, which are arranged to pass through the titanium implant fixture below the biosensor module. The electrodes are exposed to the blood pool inside the maxillary bone marrow and perform oxidation/reduction reactions with the coating of biosensing enzyme. To prove the proposed platform, the immobilization process of glucose oxidase (GOD enzyme and in vitro detections of glucose levels are successfully carried out, and proven sensitivity, linearity and repeatability of the glucose biosensor system are obtained. Moreover, a preliminary canine animal model adopting the new pathway shows significant consistency with the traditional method through dermal pricks for blood sugar detection. Despite the prospective results, further challenges in engineering implementation and clinical practices are addressed and discussed. In brief, the novel biosensing pathway and intra-oral biosensor platform may increasingly reveal their promising value and feasibilities in current bio-medical analysis

  12. 高肋板式桥台静载试验与分析%The Static Load Test and Analysis of the High Rib-plate-shaped Bridge Abutment

    Institute of Scientific and Technical Information of China (English)

    王解军; 刘昕炜; 李旺

    2015-01-01

    In view of the high rib-plate-shaped bridge abutment of the simple supported beam bridge in an engineering example,taking the ribbed slab,the pile cap and the pile foundation into con-sideration,we use the finite element software,MIDAS /CIVIL,to build the solid element model,which we calculate the horizontal displacement and stress under the load.With the vehicle load making the stat-ic load test,we use the total station to measure the horizontal displacement of the abutment on the top, and using the resistance strain gauge to measure the stress of the ribbed slab.By comparing the experi-mental results with the theoretical value,we make the technical condition evaluation of bridge abutment.%针对某工程实例简支梁桥的高肋板式桥台,采用有限元软件 MIDAS /CIVIL,考虑肋板、承台及桩基础,建立桥台结构实体有限元模型,对荷载作用下肋板的水平位移和应力进行计算分析。对桥台进行静载试验,采用车辆加载,全站仪测试台顶水平位移,电阻应变计与应变仪测试肋板应力。通过实测结果与理论值的对比分析,对桥台的技术状况进行评定。

  13. 可摘局部义齿基牙健康状况的临床观察%Clinic observation on abutment teeth healthily status with the patients wearing removable partial denture

    Institute of Scientific and Technical Information of China (English)

    孙迎春; 高平; 张恩; 陶伟

    2001-01-01

    Objective: To compare the effect of different factors (1) oral hygiene habits (2)designs of dentures (3)material of dentures on abutment teeth of removable partial dentures (RPDs). Methods: Abutment teeth healthily of examined patients status after they had worn RPDs two years with index about the caries, periodontal and oral hygiene habits . Their results were analyzed with χ2 statistics. Results:The patients oral hygiene habits and different designs of dentures are close relation with abutment teeth healthily status but different material of dentures is not significantly. Conclusion: The abutment teeth healthily status are relativei with many factors, but oral hygiene is a most important factor.%目的:对比患者不同的口腔卫生习惯、不同的义齿设计、不同的义齿材料等,以分析可摘局部义齿(RPDs)[摘要]目的:对比患者不同的口腔卫生习惯、不同的义齿设计、不同的义齿材料等,以分析可摘局部义齿(RPDs)对口腔微生态的影响。方法:在病人戴入RPDs 2a后,用龋病、牙周病常用指数及口腔卫生指数,来检查基牙健康状况,用χ2检验分析它们之间的结果有无差异。结果:患者的口腔卫生习惯、义齿的不同设计、均与基牙健康密切相关。而两种不同材料的义齿对基牙的损坏无显著性差异。结论:RPDs基牙的健康与多因素有关,而口腔卫生状况是决定RPDs口腔微生态的重要因素。

  14. Analysis on Stability Simulation of Right Abutment Slope, Delsi-Tanisagua Hydroelectric Project, Ecuador%厄瓜多尔德尔西水电站右坝肩边坡稳定性模拟分析

    Institute of Scientific and Technical Information of China (English)

    梁晓波; 张为法

    2014-01-01

    基于厄瓜多尔德尔西水电站前期地质勘查资料,用Gocad软件建立右坝肩边坡的三维地质模型,导入Flac3d做弹塑性分析和强度折减计算,根据计算所得位移场和应力场的分布规律,分析评价右坝肩边坡的天然稳定性,探讨边坡的可能破坏情况。%Based on data on geological exploration at the feasible study stage of Delsi-Tanisagua Hydroelectric Project in Ecuador, 3D geological model of slope in right abutment is built with Gocad.Then Flac3d is introduced to perform the elastic-plastic analysis and the strength reduction calculation.In accordance with the distribution law of displacement field and stress field from the calculation, the natural stability of the slope in the right abutment is analyzed and assessed, and the potential failure of the slope isstudied.

  15. The clinical study on abutment dentin hypersensitivity after preparation for crown and bridge%冠桥基牙制备后牙本质敏感的临床治疗研究

    Institute of Scientific and Technical Information of China (English)

    邓文正; 郭庆; 陆辉; 邱伟芳

    2013-01-01

    Objective To evaluate the effects of professional oral allergy desensitization paste for treating abutment dentin hypersensitivity after preparation for Crown and bridge.Methods 226 patients,repaired by porcelain Crown and bridge,were randomly divided into test group and control group,n =113.Test group:Professional oral allergy desensitization paste was used after tooth preparation and before bonding the ceramic Crown and bridge,for 113 cases.Control group:Gluma desensitizer was used after tooth preparation and before bonding the ceramic Crown and bridge,for 113 cases.Adopted cold air blowing,dentin sensitivity was evaluated by recording the value of visual analogue pain scores (VAS).Results The abutment sensitivity of the test group,by using desensitizing paste therapy after tooth preparation,significantly reduced.The abutment sensitivity after desensitizing paste therapy was statistically significant compared with that of before using desensitization paste and control group (P<0.001).The abutment sensitivity of test group was statistically significant compared with that of control group after the ceramic Crown and bridge was bonded (P<O.O01).Conclusion Professional oral allergy desensitization paste has good effect on treating abutment dentin hypersensitivity after preparation for Crown and bridge.%目的:评价抗敏口腔专业用脱敏膏对于烤瓷冠桥基牙制备后牙本质过敏的治疗疗效.方法:选取做烤瓷冠桥修复的226例患者,随机分为实验组和对照组,各113例.实验组:113例备牙后和烤瓷冠桥粘固前使用抗敏口腔专业用脱敏膏进行脱敏.对照组:113例备牙后、烤瓷冠桥粘固前使用Gluma脱敏剂脱敏.牙本质敏感度的评价采用冷空气喷吹法,记录视觉模拟疼痛评分(visual analogue scale,VAS)值.结果:实验组于备牙后使用脱敏膏治疗基牙敏感显著降低,与使用前对照组比较差异有统计学意义(P<0.001);与对照组相比,实验组粘固后基牙敏

  16. 固定桥基牙牙槽骨吸收三维有限元模型的建立%Construction of a three-dimensional finite element model of the absorbed alveolar bone of fixed partial denture abutments

    Institute of Scientific and Technical Information of China (English)

    陈艳; 吴娴; 张一岭; 张翼

    2011-01-01

    目的:通过建立左侧下颌后牙5单位固定桥双基牙侧牙槽骨吸收的有限元模型,为分析双基牙侧牙槽骨吸收对牙周膜应力的影响打下基础.方法:采用多层螺旋CT扫描技术与Mimics、Ansys软件相结合对88张层厚为0.6 mm的CT断层影像进行三维重建,在此基础上建立双基牙侧牙槽骨吸收模型.结果:建立了5单位固定桥有限元模型及双基牙侧牙槽骨吸收的有限元模型,包括牙齿、牙周膜、牙槽骨.结论:所建模型结构完整,单元划分精细,能够较精确地模拟牙槽骨吸收的实体状态,为加载后的基牙牙周膜应力分析提供基础.%AIM : To construct three-dimensional finite element models ( FEMs) of five-unit fixed partial denture of left mandible so as to analyze the effects of double abutments alveolar bone resorption on periodontal ligament stress.METHODS: Eighty-eight CT slice pictures (0.6mm in thickness) were treated with multislice helical computed tomography scanning technology, Mimics and Ansys Software to build the FEMs.Then the alveolar bone of double abutments inordinately absorbed models on the basis of the FEMs was built.RESULTS : A three-dimensional FEMs of five - unit fixed partial denture and al,veolar hone resorption of double abutments model were constructed, including teeth.periodontal ligaments and alveolar bone.CONCLUSION : The constructed models had the advantages of intact structure, precise elements and can simulate the natural situation of alveolar bone resorbtion and can provide basis for further research of periodontal ligament stress induced by loading.

  17. Clinical evaluation of tilted implant and angled abutement.%倾斜种植体与角度基台在种植修复中的临床应用

    Institute of Scientific and Technical Information of China (English)

    铁朝荣; 张文捷; 陈建钢

    2011-01-01

    目的:观察倾斜种植体与角度基台联合应用的临床疗效,探讨相关手术和修复技巧.方法:牙列缺损(失)病例17例,倾斜植入种植体25枚,随访时间0.5~2年,观察种植体稳定性、炎症、X线改变等指标,评价临床疗效.结果:除2例种植体脱落外,其余25枚种植体均获成功,临床成功率92%.结论:倾斜种植体在骨量不足或邻牙倾斜种植修复中可发挥独特的作用.但由于倾斜种植体应力主要集中在其颈部,临床应用应以多枚种植体连冠修复为宜,以便分散应力;在无牙颌修复中,为减轻远中扭力,应尽量减少游离端长度.%Objective: To study the outcome of tilted implant and angle abutement in clinic. Method:17 patients recived 27tilted implant. In 0.5~2 years of follow-up, implant stability, inflammation, and X-rays change were obtained and assessed. Rusult:25 implant were remained, 2 implants were lost, successful rate was 92 %. Conclusion: tilted implant with angle abutement could be used in patients with inadequate bone or inclined tooth. Because the stress was located in the neck of tilted implant, It is recommended that connected tooth-tooth restorations was useful. In edentulous patients, long cantilever should be avoided.

  18. 钛种植体基台和不同合金的体外耐腐蚀性能%In vitro corrosion resistance of titanium abutment and different alloys

    Institute of Scientific and Technical Information of China (English)

    黄伟城; 吴泽键; 陈伟生

    2015-01-01

    背景:各种医用生物材料在应用于口腔环境之前,除了对其机械性能和理、化学性能予以严格的考察之外,还需要进行口腔环境耐腐蚀性实验,以保证材料的生物相容性.目的:分析钛种植体基台和不同钛合金的体外耐腐蚀性能.方法:构建体外人工唾液腐蚀环境,pH=6.0,温度(37±0.5) ℃,利用动电位极化技术、扫描电镜、X射线衍射等方式评估钛合金、金合金、镍铬合金及钛种植体基台在人工唾液中浸泡24 h的耐腐蚀性能.结果与结论:不同合金的稳态电位不同,其中金合金钝化区范围最大,其次为钛种植体基台和钛合金,镍铬合金钝化区范围最小.经过24 h的人工唾液浸泡后,不同材料的表面均开始出现钝化膜,扫描电镜显示,镍铬合金表面可见明显的腐蚀痕迹,出现大量直径较大的深点蚀坑,其余 3 种合金均未出现明显腐蚀现象;镍铬合金表面铬、钼、铝含量均出现减少现象,镍、氧含量增加,其余合金表面未出现明显改变;镍铬合金表面生成 Cr2O3,钛种植体基台及钛合金表面均生成TiO2,金合金表面仍为Au、Pt单相存在,未生成化合物.表明钛合金与钛种植体基台具有相似的耐腐蚀性能,且差于金合金,但优于镍铬合金.%BACKGROUND:Except for mechanical properties and physical and chemical properties, corrosion resistance testing is necessary for a variety of biomedical materials applied in the oral environment to ensure the biocompatibility of materials. OBJECTIVE:To explore the corrosion resistance of titanium abutment and different titanium aloysin vitro. METHODS:Corrosion environment byin vitroartificial saliva was constructed with pH=6.0 at (37±0.5)℃. Potentiodynamic polarization technique, scanning electron microscope and X-ray diffraction methods were employed to assess the corrosion resistance of titanium aloy, gold aloy, nickel-chromium aloy, and titanium abutment immersed in the

  19. Stability analysis of abutment slope at left bank of Jinping-Ⅰ Hydropower Project during construction%锦屏一级水电站左岸坝肩边坡施工期稳定分析

    Institute of Scientific and Technical Information of China (English)

    漆祖芳; 姜清辉; 唐志丹; 周创兵

    2012-01-01

    The geological conditions of the high and steep abutment slope at left bank of Jinping-I Hydropower Project are very complicated, mainly developed with the faults of f5, f8, f42-9, the lamprophyre veins of X, the release fractures oriented parallel to slope surface and deep fractures. The combination of the fault of f42-9.9, the lamprophyre veins of X and the deep fracture of SL^ form a tensile dehiscent deformable body at the abutment slope of the left bank; the stability of the abutment slope is very bad during construction, especially when the slope is excavated to the elevation of 1 780 m, all rock masses that prevent the tensile dehiscent deformable body from sliding are excavated; the outcrop of the fault of f42-9 at the surface of the excavated slope makes the stability of the tensile dehiscent deformable body abruptly become worse. The strength reduction FEM considering excavation process is applied to calculate the stability safety factor of the abutment slope; and a new slope instability criterion is proposed as follows: in finding the mutant site on the relationship curves between △δ/△F5 of key points and the strength reduction factors, the critical state of instability of the slope could be determined; in this criteria, △δ/△Ft5 which stands the change rate of horizontal displacement with the strength reduction factors, is the ratio of the horizontal displacement's increment and the strength reduction factor's increment. Comparing with other slope instability criteria, a new criterion is proved to be a reasonable and practical slope instability criterion; based on this criterion, the stability safety factors are calculated when the slope is excavated and reinforced to different elevations; the overall stability and security of the abutment slope at the left bank are reasonably evaluated during its construction.%锦屏一级水电站左岸坝肩高陡边坡地质条件复杂、主要发育有f5、f8、f42-9断层,煌斑岩脉X,顺坡卸荷裂

  20. Marginal fit at cylinder-abutment interface before and after overcasting procedure Adaptação marginal na interface intermediário-cilindro antes e após as sobrefundições

    Directory of Open Access Journals (Sweden)

    Luciana Martins Cres Moraes

    2005-12-01

    Full Text Available The aim of this study was to measure marginal fit at cylinder-abutment interface, before and after overcasting procedure. A hexagonal implant was fixed to a stainless steel base and a Estheticone-like abutment used during all the experiment. Before casting procedure, gold (Group I and Ni-Cr-Be (Group II premachined cylinders were tightened to the abutment with gold and titanium screws (in both groups, with 10Ncm and 20Ncm torque values for the same screw type. Vertical measures were taken at the light microscope (Mitutoyo 5050, Tokyo, Japan three times in six different parts along the abutment-cylinder interface for each torque value. Cylinders were overcast with Ag-Pd (Group I or Ni-Cr-Be (Group II alloy. After casting, the same measures and torque values were repeated. Intragroup differences (10 or 20Ncm torque values, before and after casting and intergroup differences (10 and 20Ncm torque values, before or after casting were analyzed by the Paired t Test; (pO objetivo deste estudo foi medir a adaptação marginal na interface intermediário-cilindro, antes e após a sobrefundição. Um implante do tipo hexágono externo afixado numa base de aço inoxidável e um intermediário do tipo Estheticone foram usados durante todo o experimento. Antes das fundições, cilindros pré-usinados de ouro (Grupo I e de Ni-Cr-Be (Grupo II foram aparafusados ao intermediário com parafusos de ouro e titânio em ambos os grupos, com torques de 10Ncm e 20Ncm para o mesmo tipo de parafuso. As medidas verticais foram feitas num microscópio óptico (Mitutoyo 5050, Tóquio, Japão três vezes em seis locais diferentes ao longo da interface intermediário-cilindro para cada valor de torque. Os cilindros foram encerados e fundidos tanto em liga de Ag-Pd (Grupo I ou liga de Ni-Cr-Be (Grupo II. Após as fundições, as mesmas medidas e os mesmos valores de torque foram repetidos. As diferenças intra-grupo (torques de 10 ou 20Ncm, antes e após as fundições e as

  1. Análisis del comportamiento mecánico de una aleación Ni-Cr-Mo para pilares dentales/Analysis of Mechanical Behavior of Ni-Cr-Mo alloy for Dental Abutments

    Directory of Open Access Journals (Sweden)

    Luis Alberto Laguado Villamizar

    2012-12-01

    Full Text Available El presente estudio caracteriza una aleación aplicable al diseño de pilares para implantes dentales. Se propone un material biocompatible y de alta resistencia mecánica como alternativa a las aleaciones de Titanio, disminuyendo los costos de materia prima y procesamiento. Se realizan pruebas mecánicas de tracción y de compresión a la aleación de Ni-Cr-Mo, posteriormente se realiza modelado 3D y simulación de sus propiedades mecánicas por medio de análisis de elementos finitos. Como resultado se obtiene que el material disminuye su resistencia mecánica después del proceso de fundición empleado. El modelo de simulación es válido para análisis de resistencia en pilares dentales.This study presents the characterization of a dental implant alloy for abutments. It proposes a biocompatible material and high mechanical resistance as an alternative to Titanium alloys, lowering costs of raw materials and processing. Mechanical testing of the Ni-Cr-Mo alloy and subsequently perform simulations of its mechanical properties by means of finite element analysis. As a result is obtained that the material reduces its mechanical strength after the casting for electric induction molding process. The simulation model is valid to make analysis of resistance to this type of dental devices.

  2. 单个后牙缺失伴远端基牙倾斜的树脂黏结固定桥修复研究%Restoration of single posterior tooth anodontia accompanied tilted distal abutment with resin bonded fixed partial denture

    Institute of Scientific and Technical Information of China (English)

    宁江海; 高飞; 王燕一; 侯康林

    2009-01-01

    目的 观察树脂黏结固定桥(RBFPD)修复下颌单个后牙缺失合并桥基牙倾斜患者的临床效果,并总结其适应证和设计特点.方法 选择2002-2003年在解放军总医院口腔科就诊的典型下颌单个后牙缺失、远端基牙近中倾斜的患者18例,所有患者基牙倾斜度不超过50°,基牙无明显松动,牙周无异常.根据基牙倾斜和模型观测结果,设计(牙合)支托和固位体的位置和形态,义齿选择普通钛合金烤瓷或钻铬合金烤瓷修复,并在修复体完成后进行5年随访.随访时进行临床检查、X线片检查并询问患者主观感受.结果 远端倾斜基牙平均倾斜33°.随访5年后,2例修复病例修复体脱落,其余义齿功能良好,牙周无明显炎症.基牙以及桥体下方牙龈无明显红肿,X线片示基牙牙周间隙无异常,患者对于修复体的外观及使用情况满意.5年期间修复体的成功率为88.9%.结论 对于伴有基牙倾斜的单个后牙缺失,采用树脂黏结固定桥进行修复的效果可靠,并具有磨牙少、基牙无需进行根管治疗等优点.%Objective To evaluate the restorative effects of customarily designed resin bonded fixed partial denture (RBFPD) on single posterior tooth anodontia accompanied by tilted distal abutment, and summarize the indications and characteristics of RBFPD. Methods From 2002 to 2003, 18 outpatients with single posterior tooth anodontia accompanied by tilted distal abutment were selected for the present study in the Department of Stomatology, General Hospital of People's Liberation Army. The gradient of tilted abutment was less than 50°. All the teeth with abutments were vital without obvious loosening or abnormal periodontal condition. The position and configuration of occlusion rest and retainer of denture were designed according to the inclination of abutment and cast survey. Titanium alloy or cobalt-chromium porcelain fused to metal RBFPD was prescribed, and all patients were

  3. 不同载荷下天然牙一种植牙联合桥基牙应力分布%Stress Distribution on Abutment of Tooth- Implant Fixed Bridge Under Different Loading

    Institute of Scientific and Technical Information of China (English)

    胡建军; 周延民; 王志彪; 张理生; 孟维艳; 周振平

    2001-01-01

    目的:揭示天然牙一种植体联合支持固定桥在不同载荷下基牙的应力反应规律,指导临床优化设计。方法:采用三维有限元方法建模型计算、分析。结果:斜向载荷下种植体的最大应力值是天然牙的2~2.5倍,集中斜向载荷与分散斜向载荷下种植体最大应力值无明显差异,是垂直载荷下种值体最大应力值2~2.5倍。集中垂直载荷下天然牙、种植体的最大应力值高于分散垂直载荷下的最大应力值。天然牙集中斜向载荷下最大应力值大于分散斜向载荷下的最大应力值。结论:天然牙一种植体联合桥承受侧向力的能力弱,种值体应具有高强度,天然牙根应粗大,减小侧向力;集中载荷比分散f荷破坏作用大,桥体与基牙的骆面咬合接触点应分布均匀,建立多点咬合接触。%To discovery the stress distribution on the abutments of tooth - implant fixed bridge under differ ent loading.Method: By 3- D finite element modeling computed and analyzed .Results: Under oblique loading, stress on the implant was 2 ~ 2.5 times as big as on tooth. There was no significant deviation of the biggest stress on the implant between concentrated oblique loading and oblique dispered loading. The biggest stress on implant under concentrated oblique loading was 2 ~ 2.5 times as big as vertical laoding. Both tooth and implant, the stress under concentrated vertical loading was bigger than under dispersed vertical loading. On the tooth, stress under concentrated oblique loading was bigger than under dispersed oblique loading. Conclusion:The ability of supporting oblique force for tooth- implant fixed bridge is weak. Implant should be of higher strength, tooth root should be stronger, oblique force should be less. Distruction of condentrated loading for abutment is more serious than dispersed loading. The bite points should be well distributed.

  4. Glass fiber composite resin cores used in wedge-shaped defect dew pulp abutment teeth%玻璃纤维桩复合树脂核在楔状缺损露髓基牙中的应用

    Institute of Scientific and Technical Information of China (English)

    胡建江; 姚悦; 李远祥; 熊雷

    2015-01-01

    目的:观察玻璃纤维桩复合树脂核在楔缺露髓基牙修复中的临床疗效。方法:选取101颗经完善根管治疗的楔缺露髓牙(上颌45颗,下颌56颗),经纤维桩修复后患者经过3、6、12个月随访,观察其临床修复效果。结果:修复后3、6、12个月复查随访发现,上颌前牙11颗,前磨牙27颗,磨牙6颗,下颌前牙15颗,前磨牙33颗,磨牙8颗冠桥无脱落,桩核无脱落及折断,牙齿无折断,X线检查无根折;上颌前牙1颗,桩核脱落,牙齿无折断,X线检查根中1/3折断。修复3、6、12个月效果比较,差异无统计学意义(>0.05)。结论:玻璃纤维桩复合树脂核在楔缺露髓基牙修复中的3、6、12个月的临床疗效无显著性差异。玻璃纤维桩在牙体缺损修复中具有抗牙折性、美观效果好等优点。%Objective To observe the glass fiber composite resin cores in wedge of pulp abutment clinical curative effect of repair. Methods Select 101 after perfect root canal therapy of wedge dew pulp teeth (maxillary 44,mandible 56),the fiber pile repair patients after two years after 3,6 and 12 months follow- up,observe its clinical repair effect. Results Repair after 3,6 and 12 months follow- up findings:review of the maxillary anterior teeth 11,27,premolar teeth six, jaw teeth before 15,premolar 33, molar eight crown bridge without, pile nuclear free fall off and break, no broken teeth,X- ray rootless fold;Upper front teeth one pile nuclear fall off, no broken teeth,X- ray check a third break in the root.Repair effect of 3,6 and 12 months the differences of no statistical significance ( >0.05). Conclusion Glass fiber composite resin cores in wedge of pulp abutment repair clinical curative effect of 3,6 and 12 months there was no significant difference.Glass fiber post in tooth defect have fight tooth folding resistance, beautiful effect is good.

  5. Impact of Unloading-Reinforcement on Excavation Slope of Abutment of Baihetan Hydropower Station%卸荷—加固效应对白鹤滩坝肩开挖高边坡的影响

    Institute of Scientific and Technical Information of China (English)

    陈星; 邢喜旺; 赵明亮

    2012-01-01

    Based on the unloading rock mass mechanic theory, this paper systematically studies the stability and reinforcement methods of excavation high slope of abutment by taking Raihetan hydropower station for an example. And the initial, excavation, unloading and reinforcement operating conditions are calculated and analyzed with finite elemental program of ADINA. Then the influence of unloading-reinforcing effect on the stress, displacement and plastic zone of excavation slope are comparative analyzed. The results show that there appears sign of instability in local area, but the high slope can maintain stability for taking reasonable reinforcement measures.%以白鹤滩水电站坝肩开挖高边坡工程为例,基于卸荷岩体力学理论与方法,系统研究了坝肩开挖高边坡的稳定性及加固措施,并以有限元计算程序ADINA为平台,分别计算分析了初始工况、开挖工况、卸荷工况、加固工况应力应变情况,对比分析了卸荷—加固效应对边坡开挖应力、位移、塑性区的不同影响.结果表明,白鹤滩坝肩高边坡在开挖后局部区域有失稳迹象,但采取合适的加固措施,该高边坡仍能保持稳定.

  6. 分光光度仪比较四种常用全瓷冠在三种基底表面的色度学参数%Spectrophotometric comparison of the colorimetric data of three dark color abutments overlaid by four types of all-ceramic crowns

    Institute of Scientific and Technical Information of China (English)

    陈奕帆; 李晓敏; 张琳; 王剑

    2015-01-01

    AIM:To evaluate the colorimetric parameter of 3 dark color abutments overlaid by 4 all-ceramic crowns using a digital dental spectrophotometer. METHODS: Abutments of Co-Cr alloys, Au-Pt alloys and ND8 (n=10) were made and were respectively tried in 4 groups of all-ceramic crowns (Procera aluminia, Procera zirconi-a, Lava zirconia and IPS E. max glass-ceramic lithium disilicate-reinforced monolithic crown) (n=10) respectively. The colorimetric data of the cervical, body and incisal sites of the samples were recorded and analyzed by a spectropho-tometer. The CIE L∗a∗b∗ values were measured again after veneer. The unglazed A2 ( Vitapan Classical) shade tab was used as the control. The L∗a∗b∗values and the color difference between the samples and control were calculated and statistically analyzed. RESULTS: There was significant difference of the lightness and saturation among 3 abut-ments. But after all-ceramic copings were tried in, the difference of the L∗values of the Pro-Alu copings and E. max HO copings decreased greatly. TheΔE value of the Pro-Alu copings was the smallest among all ceramic copings. And the ΔE value of the copings on the ND8 abutment was smallest among 3 abutments. After veneer, the consistency of the L∗ a∗b∗ values of all the copings increased, the IPS E. max HO crowns had very close L∗ values and the Pro-Zir crowns had similar a∗b∗ values in 3 groups of abutments. CONCLUSION:4 ceramic copings can promote the light-ness and hue of the dark abutments. All the copings on the ND8 abutment had small ΔE values. Veneering porcelain can increase the colorimetric match between the abutments to some extent. IPS E. max HO crowns have little difference of lightness and Procera zirconia has little difference of saturation among the abutmens.%目的::采用分光光度比色仪比较3种深色基底表面4种全瓷冠各部分的色度学参数。方法:制作钴铬合金、金铂合金及ND8色基牙预备体,分别戴

  7. 水电工程坝肩高边坡岩体渗透特性的时空变化%Time and Space Change of Permeability for Rock Mass in Dam Abutment High Slopes of Hydropower Engineering

    Institute of Scientific and Technical Information of China (English)

    李宏; 田洪圆; 刘建军

    2015-01-01

    针对中国西南大型水利水电工程坝肩高陡边坡裂隙岩体,其渗透特性随地质历史、爆破削坡、加固、蓄水/泄洪、降雨等自然和施工过程而分布变化的时空特征,介绍了相关实验、理论模型、数值分析成果,评述了研究现状和进展。展示了为促进这个问题由定性向定量发展,众多研究者各自的探索与贡献。提出在应力变形全过程、强卸荷施工、多场耦合、锚固喷浆、尺寸效应、三维模式和深部监测机制等方面,对边坡裂隙岩体的渗透特性随裂隙、节理、断层而损伤破裂演变的规律,亟需进一步深入开展研究。%With regard to the seepage characteristics of the fractured rock mass in the dam abutment high-steep slopes for large scale hydraulic and hydropower engineering in Southwest China,the experimental,theoretical models and numerical simulation study results about its time and space features in the distribution changes due to natural and construction process such as geological history,blasting excavation,support,impounding and flood discharge,rainfall,etc. are introduced. The current research state and progress is assessed. The probing efforts and contributions from researchers in this field,who desire to put this problem forward from qualitative to quantitative stage,are shown in the paper. It is proposed that in aspects of the mechanism like stress-strain whole process,intensive unloading,multiple field coupling,anchorage and shotcrete,scale effect,three dimensional pattern and monitoring in depth,further study is urgently needed in order to make the regularity clear about the evolution of permeability of fracture rock mass in slopes along the damage and failure surrounding cracks,joints and faults.

  8. 4种固定方式对外伤脱位牙和基牙早接触的影响%Effects of four kinds of fixing methods on the premature contact of traumatically dislocated teeth and abutment teeth

    Institute of Scientific and Technical Information of China (English)

    东红岗; 张莹; 薛慧; 柳军

    2011-01-01

    目的:探讨成品牙弓夹板、方丝片段弓技术、光敏树脂贴合夹板及超强纤维增强复合树脂夹板4种固定外伤脱位牙技术对基牙、脱位牙早接触的影响.方法:选择外伤性脱位牙病人46例,88个脱位牙(不完全脱位牙≤2个,无冠根折或牙槽骨骨折),276个基牙(基牙无松动、缺失或萌出不全).随机分成4组,分别采用成品牙弓夹板、方丝片段弓、光敏树脂贴合夹板、超强纤维增强复合树脂夹板4种技术进行单颌固定(固定6周).48 h后观察早接触状况.结果:外伤脱位牙固定术后48 h,在脱位牙、基牙出现早接触方面,成品牙弓夹板组与方丝片段弓组相比无显著性差异(P>0.05);超强纤维增强复合树脂夹板组与光敏树脂贴合夹板组无显著性差异(P>0.05);光敏树脂贴合夹板组与成品牙弓夹板组、方丝片段弓组相比有显著性差异(P<0.05);超强纤维增强复合树脂夹板组与成品牙弓夹板组、方丝片段弓组相比有显著性差异(P<0.05).结论:外伤脱位牙采用方丝片段弓和成品牙弓夹板技术固定后,金属固定材料产生的形变是造成基牙、脱位牙早接触的主要原因;超强纤维增强复合树脂夹板技术和光敏树脂贴合夹板技术固定材料形变小,出现基牙、脱位牙早接触的几率相对较小.%AIM; To compare the effects of four different fixing methods on the premature contact of trau-matically dislocated teeth and abutment teeth. METHODS: Eighty-eight traumatically dislocated teeth (incomplete dislocated teeth ≤2, with no crown, root or alveolar bone fracture) and 276 abutment teeth (no loosening, no missing or incomplete eruption) in 46 patients were chosen. The teeth were randomly divided into four groups and were treated with dental splint, segmented arch, composite resin splint and Super fiber-composite resin splint, respectively. Fixation lasted for 6 weeks. Premature contact was recorded 48h after

  9. 柱式桥台前坡改造数值分析与现场检测%Study on buried abutment slope transformation based on numerical simulation and site detections

    Institute of Scientific and Technical Information of China (English)

    朱登元; 姚占勇; 葛守仁

    2015-01-01

    In order to get more traffic clearance under bridge during the road upgrading transformation,an internal and external reinforcement program was proposed to the underpass grade separation.The internal program was the soil rein-forcement by the Soletanche method to active pressure soil and passive pressure soil of the abutment,and the external program was the anchored retaining wall by tie rods.Based on Abaqus6. 10,the nonlinear FEM software,a 3D elastic-plastic numeric model was built to simulate the transformation process from buried abutment slope to anchored retaining wall.Two kinds of the construction processes were simulated,one was the slope soil excavation in layer vertically only and the other was in section horizontally and in layer vertically,and the soil reinforcement area was determined.Based on site detections to the top displacement and the bolt tension force of the retaining wall,stability analysis during the soil excavation and the wall construction were done,and the anchor pull test was carried out.The results indicated that the stability factor of the slope soil excavation program in layer vertically was 1. 61,while the program in layer vertically and in section horizontally was 1. 84,and the latter program was better.The top displacement of the wall increased mainly during the construction process,and the tension forces of the bolt did not change suddenly,and the wall and the soil behind the wall were stable.The soil reinforcement by the Soletanche method could enhance the soil shear strength and the resistance to deformation,and there was no collapse,fall,and slip during the construction process.%为了增加桥下被交道路的通行空间,采取袖阀管劈裂注浆加固柱式桥台台后主动压力区土体及台前被动压力区土体,并在分段分级挖除台前填土过程中增设锚杆钢筋混凝土挡墙的内外部双重加固措施;采用Abaqus6.10非线性分析软件,建立柱式桥台前坡加固改造的三维弹塑

  10. 双端固定桥两基牙牙周膜厚度分别不同时的生物力学分析%Biomechanical Analysis of the Stress Distribution of Rigid Fixed Bridge During Different Thickness of Periodontal Membranes Around Abutments

    Institute of Scientific and Technical Information of China (English)

    刘建平; 冯晓刚; 王乐

    2011-01-01

    Objective: To study the effects of the different thickness of periodontal membranes around abutments to stress distribution of rigid fixed bridge. Methods: Two-dimensional images of mandible bones, teeth and periodontal supporting tissue of healthy people were scanned by spiral CT. Three-dimensional digital model was developed by imaging software. The three-dimensional finite element model of fixed denture on mandible posterior teeth was then developed. Stress distribution of fixed bridge loaded with the same vertical and horizontal forces was analyzed during different thickness of periodontal membranes around abutments. Results: There were no apparent differences in stress between the fixed bridge abutments and the surface of alveolar bones when the thickness of periodontal membrane around the abutments were less than 0.1 mm.When the thickness of periodontal membranes were between 0.1 mm and 0.4 mm, the stress of the alveolar bones surface reduced with the increase of the thickness of periodontal membranes, and there was a non-linear relationship between them. There was no change in the stress of the alveolar bones surface with the increase of the thickness of periodontal membranes when the thickness was more than 0.4 mm. Conclusions: Periodontal membranes around abutments exhibited cushioning effect when their thicknesses were in certain area. When it was too thicker or thinner, the cushioning effect will disappear.%目的:研究双端固定桥两基牙牙周膜厚度分别不同时对固定桥各部位应力分布的影响.方法:采用螺旋CT扫描获取健康人下颌骨、牙齿及牙周支持组织的二维图像,通过图像合成软件建立三维数字模型,并应用三维有限元分析软件生成下颌后牙固定桥的三维有限元分析模型.在相同垂直载荷和水平载荷情况下,分析两基牙牙周膜厚度分别不同时固定桥的应力分布.结果:当基牙牙周膜厚度小于0.1mm时固定桥基牙与牙槽骨表面应力大小

  11. Effect of lifting arm abutting head method on correcting displacement of PICC into internal jugular vein in preterm infants%举臂靠头法纠正早产儿PICC异位于颈静脉的效果观察

    Institute of Scientific and Technical Information of China (English)

    邓桂珍; 谭瑞贞; 邓玉环; 邵巧仪

    2015-01-01

    Objective To analyze the effect of lifting arm abutting head method on correcting displacement of PICC into internal jugular vein in preterm infants. Methods Between June 2013 to October 2014 42 premature infants with peripherally inserted central catheter ( PICC) heterotopia were selected in the study. Twenty-two of them were randomly selected in experimental group and they adopted the method of lifting arm abutting head to correct catheter heterotopia. The remaining 20 cases were in control group and adopted conventional method. Results There was statistical significance in the differences of adjusting times and successful rate between the control group and the experimental group (t=3. 89,χ2 =78. 49,P0. 05). Conclusion Lifting arm abutting head method to adjust PICC heterotopia is simple and easy to operate. It can not only help to reduce the pain of patients, but reduce patients’ family burden.%目的:分析举臂靠头法在早产儿经外周静脉穿刺置入中心静脉导管( PICC)异位于颈静脉的处理效果。方法选取2013年6月到2014年10月行PICC置管导管尖端异位于颈静脉的早产儿42例作研究对象,随机选取22例为实验组,采用举臂靠头法对异位的导管进行调整,监测调整后效果,其余20例为对照组,以常规方法调整。结果实验组调整次数及成功率与对照组相比较,两者有统计学意义(t=3.89,χ2=78.49,均P0.05)。结论采取举臂靠头法对PICC异位于颈静脉进行正位,操作简单、方便,减少病人的痛苦,减轻家庭负担。

  12. Clinical analysis of the influence of temporary crowns on abutment and implant after tooth preparation%牙体制备后临时冠桥修复对基牙及修复体影响的临床分析

    Institute of Scientific and Technical Information of China (English)

    吴启建; 徐敏; 李桂苓

    2015-01-01

    Objective Analysis the effect of temporary crown and bridge repair on the abutment and dental restoration. Methods Randomly selected 80 patients between 2013-2014 a clinical investigation, using retrospective analysis method, the application of direct or indirect method, improve the function, cosmetic repair effect.Results All patients were back on time,within the given time line PFM, casting crown and bridge repair, clinical observation, try effect is good,smooth in place restoration,restoration margin closed closed, try occlusal height is normal, no displacement of abutment teeth, no missing area, elongation polices jaw teeth.Temporary crown bridge can protect the abutment teeth, protect fix clearance and occlusal relationship, avoid teeth mobile embedded plug caused by food, maintain a healthy oral and periodontal tissue. Play a good role.Conclusion The temporary crown and bridge of protect teeth, worth clinical promotion.%目的:分析牙体制备后临时冠桥修复对基牙及修复体的影响。方法选取2013~2014年我院收治的患者80例,采用回顾分析法,应用直接或间接制作方法,提高功能,美观的修复效果。结果本组患者均在规定时间内按时复诊,行烤瓷、铸造冠桥的修复,临床观察,试戴效果良好,顺利就位修复体,修复体边缘封闭密合,试戴咬合高度正常,无基牙移位,无缺失区,対颌牙伸长。临时冠桥的制作能保护基牙,保护修复间隙和咬合关系,避免牙齿移动引起食物嵌塞,维护口腔牙周组织健康。结论临时冠桥所起到的保护牙齿作用,值得临床推广使用。

  13. Glass Fiber Reinforced Composite Resin Post Repair Broken Porcelain Teeth Abutments Clinical Effect%玻璃纤维增强型复合树脂桩核修复基牙折断烤瓷牙的临床效果研究

    Institute of Scientific and Technical Information of China (English)

    刘聪慧

    2015-01-01

    目的:探讨基牙折断烤瓷牙行玻璃纤维增强型复合树脂桩核修复的临床效果。方法:74例患者基牙折断烤瓷牙患者用完全随机数字表法,分为对照组和实验组,各37例。对照组接受铸造金属桩核修复治疗,实验组以推行玻璃纤维增强型复合树脂桩核修复疗法,对比两组临床疗效。结果:实验组总有效率明显高于对照组,并发症发生率显著低于对照组,就诊次数、复诊周期及松动率均低于对照组,咬合力及主观满意度评分均高于对照组,差异具有显著统计学意义(P<0.05)。结论:基牙折断烤瓷牙行玻璃纤维增强型复合树脂桩核修复临床效果确切,并发症少。%Objective: To investigate the abutment teeth broken porcelain broker glass fiber reinforced composite resin post core and the clinical effect of repairing.Methods: 74 patients of abutment teeth broken porcelain teeth patients with completely randomized digital table method, divided into experimental group and control group, each of 37 cases. The control group received metal cast post core restoration treatment, experimental group with the implementation of the glass fiber reinforced composite resin post core restoration therapy, compared two groups of clinical curative effect.Results:The experimental group was better than that in control group, the incidence of complications was significantly lower than the control group, and treatment referral cycle times, and loosening rate was lower than the control group, bite force and subjective satisfaction scores were higher than those in the control group, there was a statistically significant difference (P<0.05).Conclusion:Abutment broken porcelain broker glass fiber reinforced composite resin post and core in the restoration of the exact clinical effect, complication.

  14. 云南沙沙坡水电工程右岸坝肩开挖光面爆破设计%On the Blasting Design of Abutment Excavation on the Right Bank of the Dam at Shapo Hydro-power Station in Yunnan

    Institute of Scientific and Technical Information of China (English)

    黄少鹏

    2014-01-01

    文章介绍了云南沙沙坡水电工程右岸坝肩岩体深孔台阶光面爆破开挖的设计和施工情况,着重对钻孔的设计和布置、装药结构进行了较详实地描述,可为类似工程项目施工提供参考。%This paper introduced the blasting design of the abutment of deep hole bench on the right bank of the dam at Shapo hydro-power station in Yunnan. The author gave a detail description of the design and layout of the driling hole and charge structure offering a reference for similar project construction.

  15. Clinical analysis on removable partial denture in Kennedy Ⅰ dentition defect after Loose abutments were fixed by combined crowns%联冠固定松动基牙后可摘义齿修复肯氏I类牙列缺损的临床疗效观察

    Institute of Scientific and Technical Information of China (English)

    顾斌; 李萍; 刘娜; 刘洪臣

    2012-01-01

    Objective: To evaluate clinical therapeutic effect of removable partial denture on Kennedy I dentition defect after loose abutment were fixed by combined crowns or stabilized by continuous clasp. Methods: Forty patients of Kennedy I dentition defect with loose premolars were collected and divided into 2 groups randomly. Before the restoration with removable partial denture, loose abutments in one group were fixed with combined porcelain fused to metal crowns, while those in the other group were repaired with continuous clasp. Effects of two kinds of treatment were evaluated respectively after 1-5 years follow-up period. Statistic analysis was performed. Results: At 5 years, the success ration of combined porcelain fused to metal crowns group was better than continuous clasp group. The differences of satisfaction rate, plaque control record, probing depth, clinical attachment loss, bleeding on probing and bone support were significant (P<0.05). Conclusion: Good clinical effect of RPD in Kennedy I dentition defect might be obtained after loose abutments were fixed by combined crowns combined with complete periodontal therapy.%目的:分别用烤瓷联冠固定基牙和连续高位卡环稳定基牙,利用可摘局部义齿(removable partial denture,RPD)修复双侧磨牙缺失,比较两者间的临床疗效.方法:选取肯氏Ⅰ类牙列缺损近缺失端基牙I-II度松动病例40例,在进行完善的牙周基础治疗后,分别采用烤瓷联冠固定基牙和连续高位卡环稳定基牙,行可摘局部义齿修复.术后复查,随访1-5年,通过比较患者的主观感受和临床检查结果进行疗效评价.结果:烤瓷联冠组5年临床成功率高于连续高位卡环组,两组患者的满意率、牙周菌斑指数、牙周袋探诊深度、临床附着水平、探诊后出血指数、牙槽骨支持指数差异有统计学意义(P<0.05).结论:对肯氏I类牙列缺损伴前磨牙松动的患牙,经完善的牙周治疗后,烤瓷联冠固定松动

  16. 镍铬合金烤瓷修复体拆除前后患牙龈下菌群的变化%Variation in subgingival flora of abutments before and after removal of nickel-chromium alloy porcelain-fused-to-metal restoration

    Institute of Scientific and Technical Information of China (English)

    郭大伟; 宋玲; 张春艳; 曹阳; 李菁文; 梁星

    2013-01-01

    BACKGROUND:Currently, there are few reports on the effect of nickel-chromium (Ni-Cr) al oy porcelain-fused-to-metal (PFM) restoration on subgingival flora of abutment. OBJECTIVE:To investigate the effect of the Ni-Cr al oy PFM restoration on subgingival flora ratio of abutment. METHODS:Nine patients (12 teeth) who suspected that Ni-Cr al oy PFM could affect their health and therefore came to hospital to ask for removal of the prosthesis were selected in this study. Their subgingival plaques of abutment were obtained before and 1 month, 3 months after the Ni-Cr al oy PFM restorations were removed, respectively, and the changes of subgingival flora were observed and analyzed by the method of denaturing gradient gel electrophoresis. RESULTS AND CONCLUSION:The images of denaturing gradient gel electrophoresis in subgingival bacteria of experimental group had significant changes at 1 and 3 months after Ni-Cr al oy PFM restorations removed, furthermore, there were significant differences in the images of denaturing gradient gel electrophoresis at 1 and 3 months. In addition, the specific bands were selected from denaturing gradient gel electrophoresis image that appeared before Ni-Cr al oy PFM restorations removed and weakened or disappeared after the removal of restorations, then 16S rDNA sequence in the specific bands were analyzed. The results showed that the gene sequences of these bands were closest related to Eikenel a corrodens, Campylobacter rectus and Eubacterium saphenu. These findings indicated that the Ni-Cr al oy PFM restorations would result in the changes of the proportion of subgingival microflora and increases in the detection rates of some periodontal pathogens.%背景:目前有关镍铬合金烤瓷修复体对龈下菌群影响的研究还较少。  目的:探讨镍铬合金烤瓷修复体对龈下菌群构成比的影响。  方法:选择因怀疑镍铬合金烤瓷修复体影响健康而要求拆除原修复体的烤瓷牙患者9

  17. 腹腔镜与CT引导下射频消融治疗横膈下肝血管瘤的对比研究%Radiofrequency ablation for hepatic hemangiomas abutting the diaphragm: a comparison of computed tomography guided versus laparoscopic approach

    Institute of Scientific and Technical Information of China (English)

    牛海刚; 高君; 丁雪梅; 柯山; 孙文兵; 辛宗海; 宁纯民; 国世刚; 李晓龙

    2014-01-01

    目的 比较CT和腹腔镜路径射频消融(radiofrequency ablation,RFA)治疗横膈下方肝血管瘤的安全性和有效性.方法 回顾性分析RFA治疗43例患者的43个膈下肝血管瘤的临床资料,19例接受CT引导下经皮RFA治疗(CT组),24例接受腹腔镜路径RFA治疗(腹腔镜组).结果 43例肝血管瘤的直径为6.0~11.8cm,平均(9.4±1.7 cm).2组患者血管瘤直径差异无统计学意义(t=0.42,P>0.05).所有患者均顺利完成RFA治疗,无技术失败.两组消融时间差异无统计学意义(t=0.07,P>0.05).CT组和腹腔镜组完全消融率分别为94.7%(18/19)和91.7%(22/24)(Fisher,P>0.05).RFA治疗后,15例患者发生21例次胸部并发症,其中CT组13例患者(68.4%,13/19),腹腔镜组2例患者(8.3%,2/24)(Fisher,P<0.05).2例出现严重并发症(胸腔积液和膈肌破裂,Ⅲ级),均发生在CT组,其余为轻微并发症(Ⅰ级).所有轻微并发症经保守治疗痊愈,2例严重并发症分别通过胸腔引流和胸腔镜手术治愈.结论 腹腔镜路径下RFA治疗膈下肝血管瘤可明显降低胸部并发症发生率,是膈下肝血管瘤首选的治疗方案.%Objective To compare the safety and therapeutic efficacy of computed tomography (CT) guided versus laparoscopic RF ablation for hepatic hemangiomas abutting the diaphragm.Methods 43 cases of hepatic hemangiomas abutting the diaphragm were divided into two groups receiving respectively CT guided (19 cases) or laparoscopic RF ablation (laparoscopic ablation group,24 cases).Results The mean diameter of the 43 hemangiomas was (9.4 ± 1.7) cm (6.0-11.8 cm).There was no difference in the diameter of hemangiomas between the two groups (t =0.42,P > 0.05).RF ablation was performed successfully for all patients.There was no difference in ablation times between groups (t =0.07,P >0.05).There were 21 thoracic complications in 15 patients,including 13 (68.4%,13/19) patients in the CT-guided ablation group and 2 (8.3%,2/24) patients in

  18. 4种玻璃离子水门汀对ITI基台与金属内冠之间粘接力的比较研究%A comparative study on adhesive force of cast crown copings cemented to ITI abutments using four glass ionomer cements

    Institute of Scientific and Technical Information of China (English)

    程耀; 傅柏平

    2014-01-01

    目的:研究4种玻璃离子类水门汀对ITI种植系统标准颈粘接固位基台和金属内冠之间的粘接力。方法将10只金属内冠与10只I T I标准颈粘接固位基台分别使用以下4种水门汀进行交叉粘固:A组为玻璃离子水门汀(日本);B组为树脂加强型玻璃离子水门汀(美国);C组为暂时粘固用玻璃离子水门汀(日本);D组为玻璃离子水门汀(德国);粘固后测试并记录样本粘接力(N),同时观察并记录粘固界面的断裂模式,最后,对粘接力进行统计学处理。所有内冠和基台经清洗后重复使用。结果4种水门汀的粘接力及由大至小的排列顺序为C组(183.6±29.4) N>D组(153.4±36.2) N>B组(144.4±41.1) N>A组(109.9±25.7)N,其中C组的粘接力最高,A组的粘接力最低,A组显著低于其它3种水门汀(PD(153.4±36.2N)>B(144.4±41.1N)>A (109.9±25.7N). Group C produced the highest adhesive force, while group A exhibited the lowest adhesive force, significantly lower than other three luting cements(P<0.05). The fracture surface observation shows that group A and D fractured at the interface of cement and abutments, while group B and C exhibited as“mixed fracture”mode. Conclusion Both conventional glass ionomer cement and resin-modified glass ionomer cements possessed the clinically acceptable adhesive forces, while the provisional glass ionomer luting cements was not suitable for the provisional cementation of implant crowns due to the too high adhesive force.

  19. Field test and numerical analysis on behaviors of low-cap pile foundation supporting bridged abutment subjected to embankment load%低承台桥台桩基侧向受力性状试验与数值分析

    Institute of Scientific and Technical Information of China (English)

    聂如松; 冷伍明; 杨奇; 岳健

    2012-01-01

    Based on field test results, a three-dimensional finite element method was set up to explore the settlement of the pile foundation, the bending moment of the piles, the horizontal movement of pile head, shear force and earth pressure on pile shafts with increasing embankment load behind the abutment wall. The results show that the calculated and measured results agree well; the lateral deformation of pile head and maximum bending moment of pile with the increase of embankment load increases linearly. In 20 m depth, the distribution of shear force along the pile depth is in "S" shaped pattern, the distribution of the earth pressure along the depth direction is of a parabola. The mechanical model of low-cap pile foundation is equivalent with the statically indeterminate beam of the pile head and pile embedded in a certain depth soil. The conclusions can be helpful and give references for pile design and construction.%基于现场测试结果,采用三维有限元技术分析低承台桥台桩基在台后路基填土过程中桩基沉降、桩身弯矩、桩顶水平变形、桩身剪力和桩侧附加水平挤压力随台后填土荷载增加的变化规律.研究结果表明:计算结果与实测结果吻合较好:桩顶水平变形和桩身最大弯矩随填土荷载的增加近似呈线性增加:深度方向20m范围内,桩身剪力图呈“S”型,桩侧附加水平挤压力图呈抛物线型.低承台桥台桩基力学模型等同于桩项和桩端嵌入一定深度、具有一定变位的超静定梁结构.本文所得结论可以为桥台桩基的设计和施工提供参考.

  20. Zirconia abutments and restorations: from laboratory to clinical investigations.

    Science.gov (United States)

    Ferrari, M; Vichi, A; Zarone, F

    2015-03-01

    In last years the use of zirconia in dentistry has become very popular. Unfortunately, the clinical indications for a dental use of zirconia are not completely clear yet, neither are their limitations. The objective of this review was to evaluate the basic science knowledge on zirconia and to discuss some aspects of the clinical behavior of zirconia-based restorations. In particular, one of the goals was highlighting the possible correlation between in vitro and in vivo studies. The definition of concepts like success, survival and failure was still debated and the correlation between in vitro results and predictability of clinical behavior was investigated. PMID:25576437

  1. Abutting Absence : Love Letters from Two Eras / Tiina Kirss

    Index Scriptorium Estoniae

    Kirss, Tiina, 1957-

    2008-01-01

    Irene Lääne ja Toomas Hiio koostatud raamatust "Ühtekuuluvuse teel : Johan Laidoneri kirjad abikaasale" (Tallinn : Varrak, 2008) ja Käbi Laretei raamatust "Kuhu kadus kõik see armastus?" (Tallinn : SE & JS, 2008)

  2. Noninvasive method for retrieval of broken dental implant abutment screw

    Directory of Open Access Journals (Sweden)

    Jagadish Reddy Gooty

    2014-01-01

    Full Text Available Dental implants made of titanium for replacement of missing teeth are widely used because of ease of technical procedure and high success rate, but are not free of complications and may fail. Fracturing of the prosthetic screw continues to be a problem in restorative practice and great challenge to remove the fractured screw conservatively. This case report describes and demonstrates the technique of using an ultrasonic scaler in the removal of the fracture screw fragment as a noninvasive method without damaging the hex of implants.

  3. The fitness of copings constructed over UCLA abutments and the implant, constructed by different techniques: casting and casting with laser welding Adaptação de copings de ritânio ao implante, construídos sobre pilares UCLA por duas técnicas: fundição e fundição com soldagem de bordo laser

    Directory of Open Access Journals (Sweden)

    Elza Maria Valadares da Costa

    2004-12-01

    Full Text Available The alternative for the reposition of a missing tooth is the osteointegrated implant being the passive adaptation between the prosthodontic structure and the implant a significant factor for the success of this experiment, a comparative study was done between the two methods for confectioning a single prosthodontic supported by an implant. To do so a screwed implant with a diameter of 3.75mm and a length of 10.0mm (3i Implant innovations, Brasil was positioned in the middle of a resin block and over it we screwed 15 UCLA abutments shaped and anti-rotationable (137CNB, Conexão Sistemas de Próteses, Brasil with a torque of 20N.cm without any laboratorial procedure (control group - CTRLG. From a silicon model 15 UCLA-type calcinatable compounds (56CNB, Conexão Sistemas de Próteses, Brasil were screwed (20 N.cm, received a standard waxing (plain buccal surface and were cast in titanium (casting group - CG and other 15 compounds, UCLA - type shaped in titanium (137 CNB, Conexão Sistemas de Próteses, Brasil received the same standard waxing. These last copings were cast in titanium separated from each other and were laser-welded to the respective abutments on their border (Laser-welding group - LWG. The border adaptation was observed in the implant/compound interface, under measurement microscope, on the y axis, in 4 vestibular, lingual, mesial and distal referential points previously marked on the block. The arithmetical means were obtained and an exploratory data analysis was performed to determine the most appropriate statistical test. Descriptive statistics data (µm for Control (mean±standard deviation: 13.50 ± 21.80; median 0.00, for Casting (36.20±12.60; 37.00, for Laser (10.50 ±12.90; 3.00 were submitted to Kruskal-Wallis ANOVA, alpha = 5%. Results test showed that distorsion median values differ statistically (kw = 17.40; df =2; p = 0.001A reposição de um elemento dentário pode ser feita por um implante osseointegrado sendo que a

  4. Variation Sentence Pattern and Variated Rhetoric---On the Study of Rhetorical Effect of"not A,but B"in the Novel of one Word is Worth Ten Thousand Words%变异句式与变异修辞--《一句顶一万句》中“不是 A,而是 B”的“拧巴”修辞

    Institute of Scientific and Technical Information of China (English)

    江南

    2016-01-01

    In the novel of One Sentence Worth Ten Thousands,the best feature of language is considered to be creating a kind of"winding"language and"Ningba"rhetorical effect.The effect is formed by the heavy use of complex sentences"is not A,but B"in the text,which usually appears in the form of three types of variation:progressive affirmation;brought forward negation of Speech variants and negative and positive parallel differentiation.Variation patterns show the writer's unique personality and style,not only to strengthen the theme and the emotion expression and highlight the character,but at the same time,through the sentence repetition and"fold around"to create a certain rhyme and rhythm .%刘震云《一句顶一万句》在语言上明显的特点是在文本中较多使用了“不是 A,而是 B”的句式,创造了一种“缠绕”的语言及其“拧巴”的修辞效果,在小说中,这种句式常以三种变异形式出现:肯定递进式;承前否定式的辞格变体;否定、肯定并列辨析式。各种变异句式展现了作家独特的个性和风格,不仅强化了主题、情感的表达,凸显了人物性格,同时通过句式的重复与“折绕”创造了某种韵律与节奏。

  5. 应用牙科分光光度比色仪对钴铬合金基底表面4种全瓷冠色度学特征的研究%The study of the colorimetric characteristics of the cobalt-chrome alloys abutments covered by four different all-ceramic crowns by using dental spectrophotometer

    Institute of Scientific and Technical Information of China (English)

    陈奕帆; 刘红春; 孟玉坤; 巢永烈; 刘长虹

    2015-01-01

    ObjectiveThis study aims to evaluate the optical data of the different sites of the cobalt-chrome (Co-Cr) alloy abutments covered by four different all-ceramic crowns and the color difference between the crowns and target tab using a digital dental spectrophotometer. Methods   Ten Co-Cr alloy abutments were made and tried in four different groups of all-ceramic crowns, namely, Procera aluminia, Procera zirconia, Lava zirconia (Lava-Zir), and IPS E.max glass-ceramic lithium disilicate-reinforced monolithic. The color data of the cervical, body, and incisal sites of the samples were recorded and analyzed by dental spectrophotometer. The CIE L*, a*, b* values were again measured after veneering. The color difference between the abutments covered by all-ceramic crowns and A2 dentine shade tab was evaluated. Results   The L* and b* values of the abut-ments can be increased by all of the four groups of all-ceramic copings, but a* values were decreased in most groups. A statistical difference was observed among four groups. After being veneered, the L* values of all the copings declined slightly, and the values of a*, b* increased significantly. When compared with A2 dentine shade tab, the ΔΕ of the crowns was below 4. Conclusion   Four ceramic copings were demonstrated to promote the lightness and hue of the alloy abutments effec-tively. Though the colorimetric baseline of these copings was uneven, veneer porcelain can efficiently decrease the color difference between the samples and thee target.%目的:采用牙科分光光度比色仪

  6. About deterioration in the abutment rocks of some large dams in Northern Italy

    Directory of Open Access Journals (Sweden)

    M. C. SPADEA

    1981-06-01

    Full Text Available Si espongono i dati sperimentali riguardanti le velocità delle onde
    elastiche longitudinali ottenute nelle rocce d'imposta di alcune grandi
    dighe del Nord Italia e se ne studia la variazione nel tempo. Sulla
    base della trattazione di O'Connell e Budiansky sulla velocità delle onde
    sismiche in solidi fratturati asciutti, si è poi stimata la densità di frattura
    nei vari casi.
    Lo studio eseguito ha permesso di evidenziare una diminuzione nei
    valori di velocità e un conseguente aumento della fratturazione da imputarsi
    dapprima all'azione dirompente dell'esplosivo (nella fase di costruzione
    e poi alla microsismicità provocata nei sistemi rocciosi di spalla
    dalla dinamica del manufatto. La fenomenologia si presenta diversa nei
    vari casi; l'effetto, comunque, è per lo più consistente.

  7. A random fatigue of mechanize titanium abutment studied with Markoff chain and stochastic finite element formulation.

    Science.gov (United States)

    Prados-Privado, María; Prados-Frutos, Juan Carlos; Calvo-Guirado, José Luis; Bea, José Antonio

    2016-11-01

    To measure fatigue in dental implants and in its components, it is necessary to use a probabilistic analysis since the randomness in the output depends on a number of parameters (such as fatigue properties of titanium and applied loads, unknown beforehand as they depend on mastication habits). The purpose is to apply a probabilistic approximation in order to predict fatigue life, taking into account the randomness of variables. More accuracy on the results has been obtained by taking into account different load blocks with different amplitudes, as happens with bite forces during the day and allowing us to know how effects have different type of bruxism on the piece analysed. PMID:27073012

  8. Removable Partial Denture Supported by Implants with Prefabricated Telescopic Abutments - A Case Report

    OpenAIRE

    Kumar, Lalit; Sehgal, Komal

    2014-01-01

    Implants have been designed to rehabilitate edentulous patients with fixed prosthesis or implant supported overdentures. Implant-supported single crowns and fixed partial dentures have become successful treatment alternatives to removable and fixed partial dentures. However, it is common to have clinical situations which make it impossible to use conventional as well as implant supported fixed partial dentures. The implant supported removable partial dentures can be a treatment modality that ...

  9. Investigation of the Effects of Abutment and Implant Length on Stability of Short Dental Implants

    OpenAIRE

    Eda OZYILMAZ; Aykul, Halil; OZYILMAZ, Emre; Dalkiz, Mehmet; M. Burak BİLGİN

    2015-01-01

    The use of dental implants to solve different problems in dentistry has been growing rapidly. The success rates of dental implants are also very important for patients. Depending on the bone level of patients, short dental implants are very popular and widely used by many dentists. Although many dentists are using short dental implants frequently, It can be guessed that there can be stability problems because of crown to implant ratios. In this study, it is aimed to find out...

  10. Free-end saddle length influence on stress level in unilateral complex partial denture abutment teeth and retention elements

    OpenAIRE

    Patrnogić Vesna; Todorović Aleksandar; Šćepanović Miodrag; Radović Katarina; Vesnić Jelena; Grbović Aleksandar

    2013-01-01

    Background/Aim. Different types of dental restorations are used for the therapy of unilateral free-end saddle edentulism. Unilateral complex partial denture is one of the indications for the Kennedy class II partial edentulism. The abscence of major connector and denture plate is an advantage compared to the conventional restorations, because of better comfort and shorter period of adaptation. The aim of the study was to analyse the influence of free-end saddle length change on the beha...

  11. Microbial diversity of supra- and subgingival biofilms on freshly colonized titanium implant abutments in the human mouth

    OpenAIRE

    Heuer, W.; Stiesch, M.; Abraham, W. R.

    2010-01-01

    Abstract Supra- and subgingival biofilm formation is considered to be mainly responsible for early implant failure caused by inflammations of periimplant tissues. Nevertheless, little is known about the complex microbial diversity and interindividual similarities around dental implants. An atraumatic assessment was made of the diversity of microbial communities around titanium implants by single strand conformation polymorphism (SSCP) analysis of the 16S rRNA gene amplicons as well...

  12. Clear-water abutment and contraction scour in the Coastal Plain and Piedmont Provinces of South Carolina, 1996-99

    Science.gov (United States)

    Benedict, Stephen T.

    2016-01-01

    The U.S. Geological Survey, in cooperation with the South Carolina Department of Transportation, collected observations of clear-water aburment and contraction scour at 146 bridges in the Coastal Plain and Piedmont of South Carolina. Scour depths ranged from 0 to 23.6 feet. Theoretical scour depths were computed at each bridge and compared with observed scour. This comparison showed that theoretical scour depths, in general, exceeded the observed scour depths and often were excessive. A comparison of field data with dimensionless relations for laboratory data showed that the range of dimensionless variables used in laboratory investigations was outside of the range for field data in South Carolina, suggesting laboratory relations may not be applicable to field conditions in South Carolina. Variables determined to be important in developing scour within laboratory studies were investigated to understand their influence within the South Carolina field data, and many of these variables appeared to be insignificant under field conditions found in South Carolina. The strongest explanatory variables were embankment length, geometric-contraction ratio, approach velocity, and soil cohesion. Envelope curves developed with the field data are useful tools for assessing reasonable ranges of scour depth in South Carolina. These tools are simple to apply and are an improvement over the current methods for predicting theoretical scour.

  13. Impact of local and systemic factors on the incidence of failures up to abutment connection with modified surface oral implants

    OpenAIRE

    Alsaadi, Ghada; Quirynen, Marc; Michiles, Katleen; Teughels, Wim; Komárek, Arnost; van Steenberghe, Daniel

    2008-01-01

    Aim: This study aimed to assess the influence of systemic and local bone and intra-oral factors on the occurrence of early TiUnite(trade mark) implant failures. Material and Methods: A total of 283 consecutive patients (187 females; mean age 56.2), who received a total of 720 TiUnite(trade mark) implants, at the Department of Periodontology of the University Hospital of the Catholic University of Leuven, were prospectively followed. The following aspects were particularly assessed: hypertensi...

  14. A Novel Scheme and Evaluations on a Long-Term and Continuous Biosensor Platform Integrated with a Dental Implant Fixture and Its Prosthetic Abutment

    OpenAIRE

    Yu-Jung Li; Chih-Cheng Lu

    2015-01-01

    A miniature intra-oral dental implant system including a built-in biosensor device is proposed in this article. The dental implant system, or platform, is replaced over maxilla and allows relatively non-invasive procedures for a novel biosensing scheme for human blood analysis. Due to placement of the implant fixture, periodontal ligaments and the pulp structure, which are regarded as the main origin of pain, are thus removed, and long-term, continuous blood analysis and management through ma...

  15. Einfluss von Fluorid-Ionen auf die Dynamik der galvanischen Korrosion im System Titan-Implantat / Abutment / Suprakonstruktion (Titan / Titan und Titan / Co-Cr-Mo-Legierung)

    OpenAIRE

    Herbst, Julia Friederike Jutta

    2015-01-01

    Die Fluoridexposition im Rahmen der täglichen Zahnpflege kann das galvanische Korrosionsverhalten von Implantatmaterialien empfindlich beeinflussen. Von besonderem Interesse ist dabei die Dynamik der Reaktion auf eine spontane Fluoridexposition. Zur Untersuchung dieser Dynamik wurde die Reaktion der Kopplungen Ti/Ti und Ti/CoCrMo auf die Zugabe verschiedener Fluoridkonzentrationen sowohl im neutralen als auch im sauren Milieu mittels elektrochemischer Rauschmessungen aufgezeichnet. Anschließe...

  16. Percutaneous radiofrequency ablation of hepatocellular carcinoma abutting the diaphragm and gastrointestinal tracts with the use of artificial ascites: safety and technical efficacy in 143 patients

    Energy Technology Data Exchange (ETDEWEB)

    Song, Inyoung; Rhim, Hyunchul; Lim, Hyo K.; Kim, Young-sun; Choi, Dongil [Sungkyunkwan University School of Medicine, Department of Radiology and Center for Imaging Science, Samsung Medical Center, Seoul (Korea)

    2009-11-15

    The purpose of this study was to assess the feasibility, safety and efficacy of radiofrequency ablation (RFA) with the use of artificial ascites for hepatocellular carcinoma (HCC) adjacent to the diaphragm and gastrointestinal tract. One hundred forty-three patients with 181 HCCs who underwent US-guided percutaneous RFA with the use of artificial ascites were retrospectively reviewed. Among the 181 HCCs, 148 HCCs were defined as problematic nodules for two major reasons: poor sonic window or possible thermal injury. We artificially induced ascites before performing RFA by dripping 5% dextrose in a water solution. We assessed the technical success of introducing artificial ascites, technical feasibility of the use of artificial ascites and complications. The technical success rate, as well as the primary and secondary technique success rate, was assessed by regular follow-up CT examinations. RFA with artificial ascites was successfully achieved in 130 of 143 patients. The primary technique effectiveness was 85.3%. During follow-up (mean, 20.4 months), remote intrahepatic recurrence occurred in 49 patients and local tumor progression occurred in 15 patients. Three (2.1%) of the 143 patients experienced major complications (hemoperitoneum, lobar infarction and biloma) related to the RFA procedure. The use of artificial ascites is a simple and useful technique to minimize collateral thermal injury and to improve the sonic window. (orig.)

  17. The Influence of Abutment Surface Treatment and the Type of Luting Cement on Shear Bond Strength between Titanium/Cement/Zirconia

    Directory of Open Access Journals (Sweden)

    Beata Śmielak

    2015-01-01

    Full Text Available Objectives. The objectives of this study were to evaluate the shear bond strength of zirconia cylinders on a modified titanium surface using different luting cement types. Material and Methods. Eighty titanium disks were divided into two groups (n=40, which were treated with either grinding or a combination of sandblasting and grinding. Then, each group was subdivided into 4 groups (n=10 and the disks were bonded to disks of sintered zirconia using one of four cement types (permanent: composite cement; temporary: polycarboxylate cement, zinc-oxide-eugenol cement, and resin cement. Shear bond strength (SBS was measured in a universal testing machine. Fracture pattern and site characteristic were recorded. A fractographic analysis was performed with SEM. The chemical analysis of the composition of the fractures was performed using energy-dispersive X-ray spectroscopy (EDS. The results of the experiment were analyzed with two-way analysis of variance and Tukey post hoc test. Results. The highest mean values of SBS were achieved when grinding was combined with sandblasting and when composite cement was used (18.18 MPa. In the temporary cement group, the highest mean values of SBS were for polycarboxylate cement after grinding (3.57 MPa. Conclusion. The choice of cement has a crucial influence on the titanium-cement-zirconia interface quality.

  18. Effect of the gonadal integrity and the gender on responses of bone crestal levels in dogs with two dental prosthetic abutment types

    Directory of Open Access Journals (Sweden)

    Gilberto Valenzuela Vásquez

    2015-01-01

    Full Text Available Catorce perros mestizos adultos (5 intactos y 9 esterilizados, compuestos por siete machos y siete hembras fueron utilizadas para evaluar el efecto de dos tipos de aditamentos protésicos de implantes dentales sobre el nivel de la cresta ósea alveolar. Los implantes dentales fueron colocados quirúrgicamente en zonas de cuartos premolares inferiores y restaurados con aditamentos protésicos convencionales (CONV y de cambio de plataforma (PFS. Ambos aditamentos protésicos fueron evaluados en cada perro. El estudio duró 180 días, en los que se realizó la restauración al día 60 post-quirúrgicamente colocados los implantes, la evaluación del nivel de la cresta ósea alveolar se realizó en los días 0, 30, 60 y 90 después de la restauración (corona cementada a través de medición indirecta utilizando un sensor radiográfico digital. Los datos experimentales se analizaron mediante un diseño completamente al azar, la unidad experimental fue el perro (efecto aleatorio, el tratamiento era el tipo de pilar protésico (efectos fijos, y el nivel de la cresta ósea de cada lado del implante (mesial y distal fue la observación. Además, factores como la condición gonadal (intactos y castrados y el género (masculino y femenino se incluyeron en el análisis estadístico para evaluar su papel en la magnitud de los cambios (interacciones en los niveles de cresta ósea alveolar. El promedio de pérdida de hueso crestal fue 0.400 ± 0.186 mm. En general, los perros con CONV tuvieron una mayor pérdida de la cresta ósea que los perros con PFS. En los perros intactos que recibieron PFS se observó una menor pérdida ósea, pero en perros castrados, el tipo de aditamento no tuvo efecto (P = 0,98 en el nivel de pérdida de la cresta ósea; por lo tanto, se detectó una interacción (P 0.77 entre el género y el tipo de aditamento, de manera similar, analizado como único factor de variación, el género no tuvo efecto (P = 0,26 en las respuestas del nivel de la cresta ósea al tipo de pilar protésico (-0.401vs. -0.385 mm, para macho y hembras respectivamente. Sin importar el tipo de pilar protésico, tanto machos como hembras mostraron pérdidas similares (-0.405 vs. -0.393, P>0.65, mientras que los perros castrados mostraron una mayor (30,8%, P <0,01 pérdida ósea crestal comparado con perros intactos. En conclusión, los perros con PFS mostraron una menor pérdida ósea crestal que áquellos que recibieron CONV; sin embargo, independientemente del género, esta respuesta sólo se mantuvo en perros intactos, por lo tanto, la condición gonadal tiene un efecto sobre la magnitud de los cambios de los niveles de hueso crestal alveolares como respuesta al tipo de aditamento protésico en perros con implantes dentales .

  19. Stress distribution of inlay-anchored adhesive fixed partial dentures: a finite element analysis of the influence of restorative materials and abutment preparation design

    OpenAIRE

    Magne, Pascal; Perakis, Nikolaos; Belser, Urs Christophe; Krejci, Ivo

    2002-01-01

    Indirect composite or ceramic fixed partial dentures (FPDs) have become an alternative to conventional metal-ceramic adhesive fixed partial dentures (AFPDs). Little information about the adequate restorative material and tooth preparation design for inlay-anchored AFPDs is available to the clinician.

  20. Using a guide template with a handpiece sleeve to locate the abutment screw position of a cement-retained implant restoration.

    Science.gov (United States)

    Kang, Hye-Won; Lee, Du-Hyeong

    2015-09-01

    The existing techniques for drilling a screw access hole in cement-retained restorations are limited by inaccurate drill guidance and ineffective cooling of the drilling area. An approach for fabricating a guide template to provide screw retrievability using computer-aided design and computer-aided manufacturing (CAD/CAM) is described. A handpiece sleeve was made by 3-dimensional printing and incorporating it into a vacuum-formed template. The handpiece sleeve not only guides the head of the handpiece accurately but also enables the cooling water to reach the area of drilling directly. PMID:26013071

  1. Clinical Application of Overlay Abutment in Restoring of Mandible Complete Denture%覆盖基牙在下颌全口义齿修复中的临床应用

    Institute of Scientific and Technical Information of China (English)

    李红燕

    2006-01-01

    目的:观察覆盖基牙在下颌全口义齿修复中的临床效果.方法:通过对19例患者覆盖基牙作金属顶冠、下颌全口义齿修复上颌牙齿少量缺失,下颌牙齿大量缺失的牙列缺损问题进行了初步探讨.结果:经半年的随访观察覆盖基牙作金属顶冠,下颌全口义齿试戴后,义齿平稳无翘动,面型良好,垂直距离合适,咀嚼效能患者满意.结论:覆盖基牙作金属项冠,下颌全口义齿的固位性和稳定性有了不同程度的增强,效果良好,易于推广.

  2. 浅析电视综艺晚会灯光设计中LED大屏幕的运用%A Brief Talk abut Application of LED Large Screen in TV Gala Lighting Design

    Institute of Scientific and Technical Information of China (English)

    陈璐璐

    2014-01-01

    总结了电视综艺晚会中,LED大屏幕的应用对灯光设计的不利影响,分析在灯光设计中合理运用LED大屏幕,使灯光与LED大屏幕良好配合、相得益彰的方法。%Some methods of the reasonable use for large screen cooperated well with lighting design were summarized in TV gala.

  3. Application of crown lengthening surgery for molar abutments in fixed partial denture restoration%磨牙冠延长术在固定义齿修复中的应用

    Institute of Scientific and Technical Information of China (English)

    朱文军; 赵克; 陈卓凡; 李京平

    2008-01-01

    目的:观察磨牙冠延长术后作为固定义齿基牙的修复效果及相关问题.方法:临床牙冠骀龈距过小且被选为固定义齿基牙的末端磨牙21例,施以冠延长术,即翻瓣术或翻瓣术联合牙槽骨修整术,然后于2-8w后以固定义齿修复.6个月、1年后复查.检查修复体固位情况、固位体边缘、牙龈健康状况、龈沟出血指数等.结果:6-12个月后义齿固位良好,边缘密合,患者无不适,牙龈无明显红肿,龈沟出血指数与对称牙出血指数差异均无统计学意义(P>0.05).结论:对于临床牙冠短的磨牙,冠延长术是改善其固定修复效果的一种有效方法.

  4. The Reactivity Study of Abutment Peridontal Tissue to Different Porcelain Teeth%基牙牙周组织对不同种类烤瓷牙底冠的反应性初探

    Institute of Scientific and Technical Information of China (English)

    陈碧霞

    2014-01-01

    Objective:To observe the Th17 cytokines changes in gingival crevicular fluid of different kinds porcelain tooth after restoration.Method:96 cases with single-crown repair mandibular molar were divided into co-cr alloy group,galvanized forming group and zirconium dioxide group,the Th17 cytokines level in gingival crevicular fluid after respectively repair 1,3 months were detected.Result:IL-17 and IL-21 level in gingival crevicular fluid of co-cr alloy group after restoration 1,3 months were significantly higher than those before restoration(P0.05).IL-17 and IL-21 level in gingival crevicular fluid of zirconium dioxide group after restoration 1,3 months were as same as before restoration(P>0.05).IL-17 and IL-21 level in gingival crevicular fluid of co-cr alloy group after restoration 1,3 months were higher than those of galvanized forming group and zirconium dioxide group(P0.05);二氧化锆组修复后1、3个月,龈沟液中IL-17和IL-21水平与修复前比较差异无统计学意义(P>0.05);在修复后1、3个月,钴铬合金组的IL-17和IL-21水平高于金合金组和二氧化锆组(P<0.05);金合金组的IL-17水平高于二氧化锆组(P<0.05)。结论:金合金、二氧化锆全瓷冠是理想的烤瓷修复材料,二者均优于钴铬合金。

  5. Analysis on the monitoring data of piezometer level of right abutment at a dam%某大坝右岸坝肩测压管水位监测资料分析

    Institute of Scientific and Technical Information of China (English)

    张雪芹

    2011-01-01

    为有效掌握土石坝右坝肩的渗流状态,根据大坝绕坝渗流的监测资料,结合工程实际,考虑库水位、降雨量以及时效等因素的影响,对大坝右岸测压管渗压水位进行统计分析,通过相关性分析来判断右岸绕坝渗流的形态.分析结果表明,大坝右岸绕坝渗流性态正常.

  6. The Analgesic Effect of Tramadol in the Preparation of Abutment for Vital Teeth%曲马多在活髓牙基牙制备中的镇痛作用

    Institute of Scientific and Technical Information of China (English)

    凌翔; 金燕; 陈卫民

    2002-01-01

    目的:评价曲马多对活髓牙基牙制备时镇痛效果.方法:临床上需作固定义齿修复的患者60例随机分成两组,活髓牙基牙制备前,治疗组口服曲马多胶囊50 mg;对照组采用2%利多卡因局部浸润麻醉,观察两种药物在活髓牙基牙制备时镇痛效果及不良反应.结果:活髓牙基牙制备时,利多卡因与曲马多镇痛效果相似,差异无显著性(P>0.05),总有效率分别为96.7%,100.0%.治疗组仅见轻度不良反应.结论:活髓牙基牙制备时口服曲马多镇痛安全、有效.

  7. Evaluation of pre-tightening in abutments and prosthetic screws on different implant connections = Avaliação do pré-aparafusamento em pilares e parafusos protéticos em diferentes conexões de implante

    Directory of Open Access Journals (Sweden)

    Panza, Leonardo Henrique Vadenal

    2010-01-01

    Conclusão: Os tipos de conexão do implante ou pilar fetaram a manutenção do préaparafusamento. As conexões de hexágono interno e externo foram efetivas para evitar o deslocamento horizontal das coroas

  8. The change of rotational freedom following different insertion torques in three implant systems with implant driver

    OpenAIRE

    Kwon, Joo-Hyun; Han, Chong-Hyun; Kim, Sun-Jai; Chang, Jae-Seung

    2009-01-01

    STATEMENT OF PROBLEM Implant drivers are getting popular in clinical dentistry. Unlike to implant systems with external hex connection, implant drivers directly engage the implant/abutment interface. The deformation of the implant/abutment interface can be introduced while placing an implant with its implant driver in clinical situations. PURPOSE This study evaluated the change of rotational freedom between an implant and its abutment after application of different insertion torques. MATERIAL...

  9. 从模因论视角分析句式“不是A,而是B”--以刘震云小说《一句顶一万句》为例%On the Sentence Not A,but B from the Angle of the Meme Theory--Taking the Novel A Top 10000 for Example

    Institute of Scientific and Technical Information of China (English)

    王娇娇; 李瑞楠

    2016-01-01

    《一句顶一万句》中,句式“不是A,而是B”的重复运用体现了语言模因的特点,但这种句式模因的复制、传播并不是完全常规的,往往伴随一些模因变体的出现。语言模因“不是A,而是B”的复制传播主要有以下三种模因形式:基因型模因、表现型模因和基因表现型。这些模因句式往往能产生预期与反预期效果、零度语言、拧巴与“绕”等特殊的修辞效果,同时这些变体模因也能让读者感悟到另类的生存哲学。%In Liu Zhenyun's novel A Top 10000,Sentence Not A, but B continuous use reflects the char⁃acteristics of language memes,but the spread of the memes copy is not a complete routine.They often appear with the emergence of the memes variant. The copies transmitted form of Language memes"instead of A, B"ba⁃sically has the following three kinds of memes genotype meme, phenotype meme and gene phenotype meme which is based on memetics.Accordingly,these memes sentence often produce special rhetorical effect ,such as expectations and the desired effect, zero language, screw-ups,and comprehension of survival philosophy be⁃hind these sentence patterns.

  10. The effect of shades of luting cements and abutments on the colors of three CAD/CAM all-ceramic laminate materials%粘接剂与基牙颜色对三种CAD/CAM全瓷贴面颜色的影响

    Institute of Scientific and Technical Information of China (English)

    王宣儒; 姚佳景; 黄慧

    2013-01-01

    目的 评价全瓷修复体材料、基牙颜色及粘接剂对CAD/CAM椅旁系统修复体色泽的影响.方法 选择三种CAD/CAM椅旁全瓷修复材料:IPS Empress CAD、IPS E.max CAD和Cerec Blocs.每种材料各制备出厚度为(0.8±0.02)mm的试样18片,随机分为3组,以聚四氟乙烯为模板,制作15mm×13mm×2mm的3种颜色的基牙树脂试件,分别采用2种颜色(Transparent与Bleach)的粘接剂粘接瓷片与基牙树脂,每组3片,静压2min,光照20s,使用台式分光亮度仪测量三种全瓷材料的透光度,比较粘接前后修复体的L*、a*、b*值,并计算粘接前后的色差△E.结果 不管基牙颜色或瓷片种类如何,透明色粘接剂组粘接前后的色差△E皆显著大于漂白色粘接剂组.Cerec Blocs组粘接前后的色差最大,E.max组的色差最小,而Empress则介于两者之间.结论 三种全瓷材料中,Empress的透光度最佳,Cerec Blocs陶瓷材料更易受基牙颜色与粘接剂的影响.透明色粘接剂对基牙树脂与瓷贴面复合体的颜色影响大于漂白色粘接剂.

  11. Oral Abstract Session 3: Orthognathic/Implants

    DEFF Research Database (Denmark)

    Hartlev, Jens

    Immediate Placement And Provisionalization Of Single-tooth Implants Involving A Final Individual Abutment. A 3-year Clinical And Radiographic Retrospektive Study......Immediate Placement And Provisionalization Of Single-tooth Implants Involving A Final Individual Abutment. A 3-year Clinical And Radiographic Retrospektive Study...

  12. Precision Attachment: Retained Overdenture

    OpenAIRE

    Jayasree, K; Mrs.M.Bharathi; Nag, V. Dileep; B. Vinod

    2011-01-01

    Precision attachments are small interlocking devices to connect prosthesis and abutments that offer a variety of solutions to the challenge of balance between functional stability and cosmetic appeal. Precision attachments have wide applications, used in fixed removable bridge, removable partial dentures, overdentures, implant retained overdentures, and maxillofacial prosthesis. Attachment retained overdentures helps in distribution of masticatory forces, minimizes trauma to abutments and sof...

  13. THE INFLUENCE OF SURFACE-FREE ENERGY ON SUPRAGINGIVAL AND SUBGINGIVAL PLAQUE MICROBIOLOGY - AN IN-VIVO STUDY ON IMPLANTS

    NARCIS (Netherlands)

    QUIRYNEN, M; VANDERMEI, HC; BOLLEN, CML; VANDENBOSSCHE, LH; DOORNBUSCH, GI; VANSTEENBERGHE, D; BUSSCHER, HJ

    1994-01-01

    THE INFLUENCE OF SURFACE FREE ENERGY on supra- and subgingival plaque microbiology was examined in 9 patients with functional fixed prostheses supported by endosseous titanium implants. Two abutments (trans-mucosal part of the 2 stage implant) were replaced by either a new titanium abutment or a flu

  14. Influence of all-ceramic and porcelain-fused-to-metal restorations on peri-implant gingival discoloration:a spectrophotometric comparison

    DEFF Research Database (Denmark)

    Peng, Min; Fei, Wei; Hosseini, Mandana;

    2013-01-01

    PURPOSE: To compare the gingival discoloration of implant supported all-ceramic and Porcelain-Fused-to-Metal (PFM) restorations in anterior maxillary region by spectrophotometric evaluation. METHODS: Eighteen patients with 29 implant-supported single crowns (11 all-ceramic restorations, 9 PFM...... restorations with titanium abutment and 9 PFM restorations with gold alloy abutment) in anterior maxillary area were recruited. The color difference between peri-implant gingival and contra-lateral/neighboring tooth mucosa were assessed using a spectrophotometer in CIELab coordinates. Subjective gingival...... restorations with titanium abutment (3.5+2.5) as regard to spectrophotometric evaluation of gingival discoloration, and no significant difference was found between the PFM restorations with titanium abutment and PFM restorations with gold alloy abutment (6.3+3.8) either. There was, however, significant...

  15. Morse taper dental implants and platform switching: The new paradigm in oral implantology

    Science.gov (United States)

    Macedo, José Paulo; Pereira, Jorge; Vahey, Brendan R.; Henriques, Bruno; Benfatti, Cesar A. M.; Magini, Ricardo S.; López-López, José; Souza, Júlio C. M.

    2016-01-01

    The aim of this study was to conduct a literature review on the potential benefits with the use of Morse taper dental implant connections associated with small diameter platform switching abutments. A Medline bibliographical search (from 1961 to 2014) was carried out. The following search items were explored: “Bone loss and platform switching,” “bone loss and implant-abutment joint,” “bone resorption and platform switching,” “bone resorption and implant-abutment joint,” “Morse taper and platform switching.” “Morse taper and implant-abutment joint,” Morse taper and bone resorption,” “crestal bone remodeling and implant-abutment joint,” “crestal bone remodeling and platform switching.” The selection criteria used for the article were: meta-analysis; randomized controlled trials; prospective cohort studies; as well as reviews written in English, Portuguese, or Spanish languages. Within the 287 studies identified, 81 relevant and recent studies were selected. Results indicated a reduced occurrence of peri-implantitis and bone loss at the abutment/implant level associated with Morse taper implants and a reduced-diameter platform switching abutment. Extrapolation of data from previous studies indicates that Morse taper connections associated with platform switching have shown less inflammation and possible bone loss with the peri-implant soft tissues. However, more long-term studies are needed to confirm these trends. PMID:27011755

  16. Effect of Vertical Misfit on Screw Joint Stability of Implant-Supported Crowns

    Science.gov (United States)

    Assunção, Wirley Gonçalves; Delben, Juliana Aparecida; Tabata, Lucas Fernando; Barão, Valentim Adelino Ricardo; Gomes, Érica Alves

    2011-08-01

    The passive fit between prosthesis and implant is a relevant factor for screw joint stability and treatment success. The aim of this study was to evaluate the influence of vertical misfit in abutment-implant interface on preload maintenance of retention screw of implant-supported crowns. The crowns were fabricated with different abutments and veneering materials and divided into 5 groups ( n = 12): Gold UCLA abutments cast in gold alloy veneered with ceramic (Group I) and resin (Group II), UCLA abutments cast in titanium veneered with ceramic (Group III) and resin (Group IV), and zirconia abutments with ceramic veneering (Group V). The crowns were attached to implants by gold retention screws with 35-N cm insertion torque. Specimens were submitted to mechanical cycling up to 106 cycles. Measurements of detorque and vertical misfit in abutment-implant interface were performed before and after mechanical cycling. ANOVA revealed statistically significant difference ( P titanium exhibited the highest misfit values. Pearson correlation test did not demonstrate significant correlation ( P > 0.05) between vertical misfit and detorque value. It was concluded that vertical misfit did not influence torque maintenance and the abutments cast in titanium exhibited the highest misfit values.

  17. Influence of ZOE and formocressol on shear bond strength of composite to the dentin of primary teeth

    Directory of Open Access Journals (Sweden)

    Soleymani AA

    2011-02-01

    Full Text Available "nBackground and Aims: Nowadays, removable partial dentures are applied to patients who are not able to use dental implants or fixed prosthesis. Although based on the studies the users of removable partial dentures are in the risk of plaque accumulation and unacceptable changes such as gingivitis, periodontitis and mobility in abutment tooth. It is not clear whether the negative effects of removable partial dentures are more on the isolated teeth which are a kind of abutment adjacent to endentulous area in both sides. The purpose of this study was to investigate the clinical condition of isolated abutment teeth without splinting in comparison to control abutment from the aspects of B.O.P (bleeding on probing, mobility, pocket depth and gingivitis."nMaterials and Methods: In this cross-sectional study, the prepared questionnaires were filled out by 50 patients who received removable partial dentures in department of removable prosthodontics of dental school of Tehran University of Medical Sciences. The patients had isolated abutment tooth and did not have any systemic disease. The obtained data were analyzed. Using Wilcoxon, exact Fisher and Kruskal-Wallis test."nResults: B.O.P (P=0.004, pocket depth (P=0.035, and mobility (P<0.001 in isolated abutments were more than those in control abutments, but there were not significant differences in the degree of caries (P=0.083 and gingivitis (P=0.07."nConclusion: This study showed that clinical condition of isolated abutments is worse than that of control abutments. More attention should be paid to healthiness of isolated teeth without splinting and periodic follow ups should be done in these cases.

  18. Scour and Scour Countermeasures at Bridge Sites

    Institute of Scientific and Technical Information of China (English)

    CHIEW Yee-Meng

    2008-01-01

    This paper examines scour and scour countermeasures at bridge piers and abutments.Abutment scour is by far more complex than its counterpart associated with piers because of the possibility of the presence of a floodplain. Notwithstanding this, the mechanism of scour at both piers and abutments is very similar; moreover, the failure mechanisms associated with both armor-ing and flow-altering countermeasures are not very different. In rivers with a floodplain, abutment scour becomes much more complex. In cases where the abutment ends at or near to the flood-plain, it can initiate bank erosion, which clearly is an important erosion problem that is quite distinct from the customary scour at either an abutment in rivers without a floodplain or a pier. For this rea-son, abutment scour can be very site-specific while pier-scour is more generic in nature. To this end, the ability to identify the type of abutment scour that may form in a particular channel is closely related to an engineer's ability to propose devices for effective scour countermeasure.By summarizing research efforts on using riprap as a pier or abutment countermeasure over the past few decades, this paper highlights the deficiencies of riprap in arresting pier scour. To this end,different failure mechanisms are identified. They are shear failure, winnowing failure, edge failure,bedform-induced failure and bed-degradation induced failure. Each failure mechanism can singly or, more likely, combine to cause the eventual breakdown of the riprap layer. The study shows that a riprap layer is vulnerable to other failure mechanisms even though it is adequately designed against shear failure, rendering it ineffective in arresting scour.

  19. Movement laws and mechanical characteristics of top coal in blasting face

    Institute of Scientific and Technical Information of China (English)

    SUN Guang-zhong; JIANG Zhi-gang

    2010-01-01

    Measuring the top coal movement and abutment pressure about Teaching Third Mine that belonged to the National Energy Investment and Development. It shows that the top coal's strong compression occurs 6 m in front of the face, the top coal is in front of side abutment pressure concentration increase area at this time, and the top coal horizontal displacement increase rapidly. Also analyzed the top coal mechanical properties, and the top coal under abutment pressure turned into block state. Finally, analyzed the top coal failure mechanism and the structure of the mechanical model, and also made a theoretical analysis of the top coal's ultimate bearing capacity.

  20. Fixed dental prostheses with vertical tooth preparations without finish lines: A report of two patients.

    Science.gov (United States)

    Agustín-Panadero, Rubén; Solá-Ruíz, María Fernanda; Chust, César; Ferreiroa, Alberto

    2016-05-01

    Tooth abutments can be prepared to receive fixed dental prostheses with different types of finish lines. The literature reports different complications arising from tooth preparation techniques, including gingival recession. Vertical preparation without a finish line is a technique whereby the abutments are prepared by introducing a diamond rotary instrument into the sulcus to eliminate the cementoenamel junction and to create a new prosthetic cementoenamel junction determined by the prosthetic margin. This article describes 2 patients whose dental abutments were prepared to receive ceramic restorations using vertical preparation without a finish line. PMID:26774314

  1. Provenance signature of pre-cambrian and mesozoic rocks in the nearshore placers of Konkan, central west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Gujar, A.R.; Angusamy, N.; Rajamanickam, G.V.

    :31 27 April 2009 reflect the source rocks: metamorphic, igneous rocks and reworked Kaladgi sand- stone. The absence of metamorphic rocks in the coastal region, which is abutted by basaltic rocks, confirms the predominant source for various heavy minerals...

  2. Bone Anchored Hearing Treatment Procedure

    Medline Plus

    Full Text Available ... implanted, the Baha device will allow sound to travel through bone and restore close-to-normal hearing ... through the abutment so the sound can then travel through the head to the functional cochlea, or ...

  3. Bone Anchored Hearing Treatment Procedure

    Medline Plus

    Full Text Available ... always changing. And technology even with the Baha system has changed recently. It's always getting more powerful, smaller, more sophisticated, just like computers. The good news is that the abutment stays ...

  4. 18 CFR 12.35 - Specific inspection requirements.

    Science.gov (United States)

    2010-04-01

    ... abutments; (x) The functioning of foundation drains and relief wells; (xi) The stability of critical slopes... structures; (iii) The structural adequacy and stability of structures under all credible loading...

  5. Bone Anchored Hearing Treatment Procedure

    Medline Plus

    Full Text Available ... up the sound, a processor, which is a computer inside the hearing aid which is correcting for ... getting more powerful, smaller, more sophisticated, just like computers. The good news is that the abutment stays ...

  6. Bone Anchored Hearing Treatment Procedure

    Medline Plus

    Full Text Available ... noise. This device also lacks some of the disadvantages of more conventional treatments for that. It used ... snaps on to the abutment. And then we wind a little gauze around, the whole idea being ...

  7. Device having expandable mandrel for making nuclear fuel element storage tubes

    International Nuclear Information System (INIS)

    A device for manufacturing containers for storing nuclear materials. The purpose of the device is to maintain angular sheet metals in the precise position required during the welding operation which is performed along the outer edges of their flange portions. The device includes a core, a thrust bearing and a counter-pressure bearing. The core is sub-divided into two separate core portions. Spring means tend to draw the core portions toward each other. Fluid operated cylinder-piston units tend to separate the core portions against the action of said spring means. Adjustment screw means provided with abutment means and screwed into one of said core portions project into the other of said core portions with the abutment means thereof. The second core portion has abutment means cooperating with the abutment means on said adjustment screw means

  8. 33 CFR 165.1187 - Security Zones; Golden Gate Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay...

    Science.gov (United States)

    2010-07-01

    ... from the surface to the sea floor, within 25 yards of all piers, abutments, fenders and pilings of the...) Regulations. (1) In accordance with the general regulations in § 165.33 of this part, entry into...

  9. Single tooth replacement using a ceramic resin bonded fixed partial denture: A case report

    OpenAIRE

    Kara, Haluk Baris; Aykent, Filiz

    2012-01-01

    This article describes the use of an all ceramic resin-bonded fixed partial denture as a conservative solution for the replacement of an incisor. It is a minimally invasive technique that does not discolor the abutment teeth.

  10. Prosthetic improvement of pronounced buccally positioned zygomatic implants: a clinical report.

    Science.gov (United States)

    Bacchi, Ataís; Santos, Mateus Bertolini Fernandes dos; Pimentel, Marcele Jardim; Nóbilo, Mauro Antonio de Arruda; Consani, Rafael Leonardo Xediek

    2014-08-01

    This report presents a prosthetic technique for the improvement of surgically positioned, buccally placed zygomatic implants with the use of custom abutments for improved retention screw position and an esthetic implant reconstruction. The patient presented four zygomatic implants with pronounced buccal inclination. The anterior implants were inclined toward the location where the anterior artificial teeth should be placed during rehabilitation. As the manufacturer does not provide angulated abutments, we attempted the waxing and overcasting of a prosthetic abutment, repositioning the access holes of the prosthetic screws to a more palatal position. This clinical report demonstrates that abutment customization could be an interesting way to relocate the access holes of the prosthetic screws in cases of zygomatic implants with pronounced buccal inclination.

  11. Bone Anchored Hearing Treatment Procedure

    Medline Plus

    Full Text Available ... This slide serves to demonstrate that there is care needed for the surgical wound postoperatively. And that ... week later, and then Jessica has to take care of her abutment a little by just making ...

  12. 76 FR 12958 - Amnor Hydro West Inc.; Notice of Preliminary Permit Application Accepted for Filing and...

    Science.gov (United States)

    2011-03-09

    ... (Reclamation) and are currently used for irrigation. The sole purpose of a preliminary permit, if issued, is to... channel beginning near the left abutment of the dam and connecting with three 63-inch-diameter...

  13. Directory of Open Access Journals (Sweden)

    Luigi CANULLO

    2013-01-01

    Full Text Available Although the use of zirconia abutments for implant-supported restorations has gained momentum with the increasing demand for esthetics, little informed design rationale has been developed to characterize their fatigue behavior under different clinical scenarios. However, to prevent the zirconia from fracturing, the use of a titanium connection in bi-component aesthetic abutments has been suggested.ObjectiveMechanical testing of customized thin-walled titanium-zirconia abutments at the connection with the implant was performed in order to characterize the fatigue behavior and the failure modes for straight and angled abutments.Material and MethodsTwenty custom-made bi-component abutments were tested according to ISO 14801:2007 either at a straight or a 25° angle inclination (n=10 each group. Fatigue was conducted at 15 Hz for 5 million cycles in dry conditions at 20°C±5°C. Mean values and standard deviations were calculated for each group. All comparisons were performed by t-tests assuming unequal variances. The level of statistical significance was set at p≤0.05. Failed samples were inspected in a polarized-light and then in a scanning electron microscope.ResultsStraight and angled abutments mean maximum load was 296.7 N and 1,145 N, the dynamic loading mean Fmax was 237.4 N and 240.7 N, respectively. No significant differences resulted between the straight and angled bi-component abutments in both static (p=0.253 and dynamic testing (p=0.135. A significant difference in the bending moment required for fracture was detected between the groups (p=0.01. Fractures in the angled group occurred mainly at the point of load application, whereas in the straight abutments, fractures were located coronally and close to the thinly designed areas at the cervical region.ConclusionAngled or straight thin-walled zirconia abutments presented similar Fmax under fatigue testing despite the different bending moments required for fracture. The main

  14. <特別講演要旨>インプラントシステムの分類と特色と今後の潮流

    OpenAIRE

    坪井, 陽一; ツボイ, ヨウイチ; Yoichi, TSUBOI

    1998-01-01

    Clinical sudies of current implant systems and their characteristics such as survival rates were reviewed. In addition, trends in fixture-abutment connections, aesthetic components, and tissue management were considered. The survival rate of the implant systems was around 90% even though some systems only showed long-term (more than five years) implant survival and cervical bone resorption around implants. The recent trend of fixture-abutment connections have been shifting from external to in...

  15. Jointless and Smoother Bridges: Behavior and Design of Piles

    OpenAIRE

    Frosch, Robert J; Chovichien, Voraniti; Durbin, Katrinna; Fedroff, David

    2006-01-01

    Integral abutment bridges have been used in the United States for decades. By eliminating expensive expansion joints, the piles supporting the end bent accommodate the total thermal movement of the bridge. Currently, integral bridges are designed based upon experience, and a rational design specification has not been developed. Furthermore, the interaction of the abutment, pile, and soil remains uncertain. A better understanding regarding the behavior of this system is needed. The objective o...

  16. Fiber-reinforced composites in fixed partial dentures

    OpenAIRE

    Garoushi, Sufyan; Vallittu, Pekka

    2006-01-01

    Fiber-reinforced composite resin (FRC) prostheses offer the advantages of good esthetics, minimal invasive treatment, and an ability to bond to the abutment teeth, thereby compensating for less-than-optimal abutment tooth retention and resistance form. These prostheses are composed of two types of composite materials: fiber composites to build the framework and hybrid or microfill particulate composites to create the external veneer surface. This review concentrates on the use of fiber reinfo...

  17. Influence of ZOE and formocressol on shear bond strength of composite to the dentin of primary teeth

    OpenAIRE

    Soleymani AA; Bahrololoomi Z; Parkam S

    2011-01-01

    "nBackground and Aims: Nowadays, removable partial dentures are applied to patients who are not able to use dental implants or fixed prosthesis. Although based on the studies the users of removable partial dentures are in the risk of plaque accumulation and unacceptable changes such as gingivitis, periodontitis and mobility in abutment tooth. It is not clear whether the negative effects of removable partial dentures are more on the isolated teeth which are a kind of abutment adjacent to ...

  18. The influence of screw type, alloy and cylinder position on the marginal fit of implant frameworks before and after laser welding Influência do tipo de parafuso, liga e da posição do cilindro na adaptação marginal das infra-estruturas sob implantes antes e após a soldagem a laser

    OpenAIRE

    Daniela Castilio; Ana Paula Ribeiro do Vale Pedreira; Paulo Henrique Orlato Rossetti; Leylha Maria Nunes Rossetti; Wellington Cardoso Bonachela

    2006-01-01

    Misfit at the abutment-prosthetic cylinder interface can cause loss of preload, leading to loosening or fracture of gold and titanium screws. OBJECTIVES: To evaluate the influence of screw type, alloy, and cylinder position on marginal fit of implant frameworks before and after laser welding. METHODS: After Estheticone-like abutments were screwed to the implants, thirty plastic prosthetic cylinders were mounted and waxed-up to fifteen cylindrical bars. Each specimen had three interconnected p...

  19. Platform switching: A panacea for bone loss??

    OpenAIRE

    Desai, Manthan H.; Patil, Veena A.

    2013-01-01

    The goal of modern implant therapy entails more than just the successful osseointegration of the implant. A successful result must also include an esthetic and functional restoration surrounded by stable peri-implant tissue levels that are in harmony with the existing dentition. In an attempt to improve long-term bone maintenance around implants, a new implant-to abutment connection referred to as “platform switching” has been proposed. It refers to the use of an abutment of smaller diameter ...

  20. A Comparison of Zirconia CAD/CAM to Conventionally Fabricated Single Implant Restorations in the Esthetic Zone

    OpenAIRE

    Borzangy, Sary

    2015-01-01

    Objective: This project aimed to determine whether single tooth implant restorations fabricated with CAD/CAM zirconia abutments/porcelain fused to zirconia crowns reveal different biological and esthetic outcomes compared with prefabricated anatomic titanium abutments/porcelain fused to metal crowns in the esthetic zone. Materials and Methods: Thirty patients who needed a single implant restoration in the esthetic zone were included in the study. Twenty-nine patients completed screening, b...

  1. Three dimensional mathematical model of tooth for finite element analysis

    Directory of Open Access Journals (Sweden)

    Puškar Tatjana

    2010-01-01

    Full Text Available Introduction. The mathematical model of the abutment tooth is the starting point of the finite element analysis of stress and deformation of dental structures. The simplest and easiest way is to form a model according to the literature data of dimensions and morphological characteristics of teeth. Our method is based on forming 3D models using standard geometrical forms (objects in programmes for solid modeling. Objective. Forming the mathematical model of abutment of the second upper premolar for finite element analysis of stress and deformation of dental structures. Methods. The abutment tooth has a form of a complex geometric object. It is suitable for modeling in programs for solid modeling SolidWorks. After analyzing the literature data about the morphological characteristics of teeth, we started the modeling dividing the tooth (complex geometric body into simple geometric bodies (cylinder, cone, pyramid,.... Connecting simple geometric bodies together or substricting bodies from the basic body, we formed complex geometric body, tooth. The model is then transferred into Abaqus, a computational programme for finite element analysis. Transferring the data was done by standard file format for transferring 3D models ACIS SAT. Results. Using the programme for solid modeling SolidWorks, we developed three models of abutment of the second maxillary premolar: the model of the intact abutment, the model of the endodontically treated tooth with two remaining cavity walls and the model of the endodontically treated tooth with two remaining walls and inserted post. Conclusion Mathematical models of the abutment made according to the literature data are very similar with the real abutment and the simplifications are minimal. These models enable calculations of stress and deformation of the dental structures. The finite element analysis provides useful information in understanding biomechanical problems and gives guidance for clinical research.

  2. Anterior all-ceramic superstructures: chance or risk?

    Science.gov (United States)

    Rinke, Sven

    2015-03-01

    The use of zirconia abutments for single-tooth restorations is well documented and supported by clinical studies with observational periods of up to 5 years. However, data for fixed partial dentures (FPDs) on all-ceramic abutments are lacking. Therefore, this indication cannot yet be generally recommended. Based on the available clinical studies, it can be assumed that the treatment results for anterior restorations can be improved by using all-ceramic abutments, especially in situations with a reduced thickness of the peri-implant soft tissues (< 2 mm). Zirconia abutments for single-tooth restorations can be restored with glass-ceramic crowns on a lithium-disilicate base or crowns with oxide-ceramic structures (alumina or zirconia). If the restorations are cemented adhesively, then all of the cement residues must be carefully removed. Superstructures based on zirconia ceramics can be removed to a certain degree if they are cemented temporarily or screwfixed with directly veneered abutments. However, prior to providing a general recommendation for temporary cementation or screw-fixation of all-ceramic superstructures, additional clinical data are needed. PMID:25606583

  3. Seepage problem in Papan dam and the treatment

    Energy Technology Data Exchange (ETDEWEB)

    Sharghi, A. [JTMA Co., Tehran (Iran, Islamic Republic of); Palassi, M. [Tehran Univ. (Iran, Islamic Republic of). Dept. of Civil Engineering

    2003-07-01

    The Papan dam in the Krygyz Republic is 97 metres high. It is located in the Osh Oblast, within a narrow and steep sided gorge on the Ak-Bura River, approximately 20 kilometres south of the City of Osh. The impoundment of the dam revealed large inflows of water to the downstream dam through the upper half of the dam and through the joints in the right abutment. A number of options were considered before a treatment method was selected. The causes of the leakage were poor grouting, and joints and fissures in the abutment. The remedial process involved the use of a plastic concrete cutoff wall extended from the crest of the dam to a depth of approximately 70 metres, in addition to the use of a grouting curtain in the right abutment. 2 figs.

  4. Corrosion Analysis of an Experimental Noble Alloy on Commercially Pure Titanium Dental Implants

    Science.gov (United States)

    Bortagaray, Manuel Alberto; Ibañez, Claudio Arturo Antonio; Ibañez, Maria Constanza; Ibañez, Juan Carlos

    2016-01-01

    Objective: To determine whether the Noble Bond® Argen® alloy was electrochemically suitable for the manufacturing of prosthetic superstructures over commercially pure titanium (c.p. Ti) implants. Also, the electrolytic corrosion effects over three types of materials used on prosthetic suprastructures that were coupled with titanium implants were analysed: Noble Bond® (Argen®), Argelite 76sf +® (Argen®), and commercially pure titanium. Materials and Methods: 15 samples were studied, consisting in 1 abutment and one c.p. titanium implant each. They were divided into three groups, namely: Control group: five c.p Titanium abutments (B&W®), Test group 1: five Noble Bond® (Argen®) cast abutments and, Test group 2: five Argelite 76sf +® (Argen®) abutments. In order to observe the corrosion effects, the surface topography was imaged using a confocal microscope. Thus, three metric parameters (Sa: Arithmetical mean height of the surface. Sp: Maximum height of peaks. Sv: Maximum height of valleys.), were measured at three different areas: abutment neck, implant neck and implant body. The samples were immersed in artificial saliva for 3 months, after which the procedure was repeated. The metric parameters were compared by statistical analysis. Results: The analysis of the Sa at the level of the implant neck, abutment neck and implant body, showed no statistically significant differences on combining c.p. Ti implants with the three studied alloys. The Sp showed no statistically significant differences between the three alloys. The Sv showed no statistically significant differences between the three alloys. Conclusion: The effects of electrogalvanic corrosion on each of the materials used when they were in contact with c.p. Ti showed no statistically significant differences. PMID:27733875

  5. Transcriptome, genetic editing, and microRNA divergence substantiate sympatric speciation of blind mole rat, Spalax.

    Science.gov (United States)

    Li, Kexin; Wang, Liuyang; Knisbacher, Binyamin A; Xu, Qinqin; Levanon, Erez Y; Wang, Huihua; Frenkel-Morgenstern, Milana; Tagore, Satabdi; Fang, Xiaodong; Bazak, Lily; Buchumenski, Ilana; Zhao, Yang; Lövy, Matěj; Li, Xiangfeng; Han, Lijuan; Frenkel, Zeev; Beiles, Avigdor; Cao, Yi Bin; Wang, Zhen Long; Nevo, Eviatar

    2016-07-01

    Incipient sympatric speciation in blind mole rat, Spalax galili, in Israel, caused by sharp ecological divergence of abutting chalk-basalt ecologies, has been proposed previously based on mitochondrial and whole-genome nuclear DNA. Here, we present new evidence, including transcriptome, DNA editing, microRNA, and codon usage, substantiating earlier evidence for adaptive divergence in the abutting chalk and basalt populations. Genetic divergence, based on the previous and new evidence, is ongoing despite restricted gene flow between the two populations. The principal component analysis, neighbor-joining tree, and genetic structure analysis of the transcriptome clearly show the clustered divergent two mole rat populations. Gene-expression level analysis indicates that the population transcriptome divergence is displayed not only by soil divergence but also by sex. Gene ontology enrichment of the differentially expressed genes from the two abutting soil populations highlights reproductive isolation. Alternative splicing variation of the two abutting soil populations displays two distinct splicing patterns. L-shaped FST distribution indicates that the two populations have undergone divergence with gene flow. Transcriptome divergent genes highlight neurogenetics and nutrition characterizing the chalk population, and energetics, metabolism, musculature, and sensory perception characterizing the abutting basalt population. Remarkably, microRNAs also display divergence between the two populations. The GC content is significantly higher in chalk than in basalt, and stress-response genes mostly prefer nonoptimal codons. The multiple lines of evidence of ecological-genomic and genetic divergence highlight that natural selection overrules the gene flow between the two abutting populations, substantiating the sharp ecological chalk-basalt divergence driving sympatric speciation.

  6. Rib fractures after reirradiation plus hyperthermia for recurrent breast cancer. Predictive factors

    International Nuclear Information System (INIS)

    Combining reirradiation (reRT) and hyperthermia (HT) has shown high therapeutic value for patients with locoregional recurrent breast cancer (LR). However, additional toxicity of reirradiation (e.g., rib fractures) may occur. The aim of this study is to determine the impact of potential risk factors on the occurrence of rib fractures. From 1982-2005, 234 patients were treated with adjuvant reRT + HT after surgery for LR. ReRT consisted typically of 8 fractions of 4 Gy twice a week, or 12 fractions of 3 Gy four times a week. A total of 118 patients were irradiated with abutted photon and electron fields. In all, 60 patients were irradiated using either one or alternating combinations of abutted AP electron fields. Hyperthermia was given once or twice a week. The 5-year infield local control (LC) rate was 70 %. Rib fractures were detected in 16 of 234 patients (actuarial risk: 7 % at 5 years). All rib fractures occurred in patients treated with a combination of photon and abutted electron fields (p = 0.000); in 15 of 16 patients fractures were located in the abutment regions. The other significant predictive factors for rib fractures were a higher fraction dose (p = 0.040), large RT fields, and treatment before the year 2000. ReRT + HT results in long-term LC. The majority of rib fractures were located in the photon/electron abutment area, emphasizing the disadvantage of field overlap. Large abutted photon/electron fields combined with 4 Gy fractions increase the number of rib fractures in this study group. However, as these factors were highly correlated no relative importance of the individual factors could be estimated. Increasing the number of HT sessions a week does not increase the risk of rib fractures. (orig.)

  7. A technique for the management of screw access opening in cement-retained implant restorations

    Directory of Open Access Journals (Sweden)

    Hamid Kermanshah

    2014-01-01

    Full Text Available Introduction: Abutment screw loosening has been considered as a common complication of implant-supported dental prostheses. This problem is more important in cement-retained implant restorations due to their invisible position of the screw access opening. Case Report: This report describes a modified retrievability method for cement-retained implant restorations in the event of abutment screw loosening. The screw access opening was marked with ceramic stain and its porcelain surface was treated using hydrofluoric acid (HF, silane, and adhesive to bond to composite resin. Discussion: The present modified technique facilitates screw access opening and improves the bond between the porcelain and composite resin.

  8. Fracture mode during cyclic loading of implant-supported single-tooth restorations

    DEFF Research Database (Denmark)

    Hosseini, Mandana; Kleven, Erik; Gotfredsen, Klaus

    2012-01-01

    restorations of zirconia abutment-retained crowns with zirconia copings veneered with glass-ceramics (n=8) and feldspathic ceramics (n=8). The control group was composed of 16 metal ceramic restorations of titanium abutment-retained crowns with gold alloy copings veneered with glass (n=8) and feldspathic...... restorations than in metal ceramic restorations. Significantly more loading cycles until veneering fracture were estimated with metal ceramic restorations veneered with glass-ceramics than with other restorations. CONCLUSIONS: The metal ceramic restorations demonstrated fewer and less severe fractures...... and resisted more cyclic loads than the ceramic restorations, particularly when the metal ceramic crowns were veneered with glass-ceramics....

  9. An overview of the corrosion aspect of dental implants (titanium and its alloys

    Directory of Open Access Journals (Sweden)

    Chaturvedi T

    2009-01-01

    Full Text Available Titanium and its alloys are used in dentistry for implants because of its unique combination of chemical, physical, and biological properties. They are used in dentistry in cast and wrought form. The long term presence of corrosion reaction products and ongoing corrosion lead to fractures of the alloy-abutment interface, abutment, or implant body. The combination of stress, corrosion, and bacteria contribute to implant failure. This article highlights a review of the various aspects of corrosion and biocompatibility of dental titanium implants as well as suprastructures. This knowledge will also be helpful in exploring possible research strategies for probing the biological properties of materials.

  10. Multiple piece turbine rotor blade

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Russell B; Fedock, John A

    2013-05-21

    A multiple piece turbine rotor blade with a shell having an airfoil shape and secured between a spar and a platform with the spar including a tip end piece. a snap ring fits around the spar and abuts against the spar tip end piece on a top side and abuts against a shell on the bottom side so that the centrifugal loads from the shell is passed through the snap ring and into the spar and not through a tip cap dovetail slot and projection structure.

  11. Specific Cleavages by RNase H Facilitate Initiation of Plus-Strand RNA Synthesis by Moloney Murine Leukemia Virus

    OpenAIRE

    Schultz, Sharon J.; Zhang, Miaohua; Champoux, James J.

    2003-01-01

    Successful generation, extension, and removal of the plus-strand primer is integral to reverse transcription. For Moloney murine leukemia virus, primer removal at the RNA/DNA junction leaves the 3′ terminus of the plus-strand primer abutting the downstream plus-strand DNA, but this 3′ terminus is not efficiently reutilized for another round of extension. The RNase H cleavage to create the plus-strand primer might similarly result in the 3′ terminus of this primer abutting downstream RNA, yet ...

  12. Structure of the crust beneath the Southeastern Tibetan Plateau from Teleseismic Receiver Functions

    NARCIS (Netherlands)

    Xu, Lili; Rondenay, S.; Hilst, R.D. van der

    2008-01-01

    Southeastern Tibet marks the site of presumed clockwise rotation of the crust due to the India-Eurasian collision and abutment against the stable Sichuan basin and South China block. Knowing the structure of the crust is a key to better understanding crustal deformation and seismicity in this region

  13. 33 CFR 118.75 - Lights on single-opening drawbridges.

    Science.gov (United States)

    2010-07-01

    ... SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.75 Lights on single-opening drawbridges. (a) Bridges in this class. Bridges of the folding, pontoon and similar type single opening drawbridges are... span. (c) Pier or abutment lights. Every swing bridge shall be lighted so that the end of each...

  14. Diffusion welding in air. [solid state welding of butt joint by fusion welding, surface cleaning, and heating

    Science.gov (United States)

    Moore, T. J.; Holko, K. H. (Inventor)

    1974-01-01

    Solid state welding a butt joint by fusion welding the peripheral surfaces to form a seal is described along with, autogenetically cleaning the faying or mating surfaces of the joint by heating the abutting surfaces to 1,200 C and heating to the diffusion welding temperature in air.

  15. Effect of tightening torque on the marginal adaptation of cement-retained implant-supported fixed dental prostheses

    Directory of Open Access Journals (Sweden)

    Jalil Ghanbarzadeh

    2015-01-01

    Conclusion: Within the limitations of this study, the marginal misfit of cement-retained FDPs increased continuously when the tightening torque increased. After cutting the connectors, the marginal misfit of the ANRs was higher than those of the straight abutment retainers.

  16. [Attaching single- and multi-unit fixed dental prostheses

    NARCIS (Netherlands)

    Kreulen, C.M.; Wolke, J.G.C.; Baat, C. de; Creugers, N.H.J.

    2013-01-01

    A single- or multi-unit fixed dental prosthesis can be attached to the abutment teeth through mechanical retention and gap sealing or by adhesion. For sealing the gap, water-soluble cements are appropriate, such as zinc phosphate, polycarboxylate, and (resin-modified) glasionomer cement. Attachment

  17. Laser repair hardfacing of titanium alloy turbine

    Directory of Open Access Journals (Sweden)

    A. Klimpel

    2011-12-01

    Full Text Available Purpose: of this paper: work out repair technology of worn abutments of aircraft jet engine blades forged of titanium alloy WT3-1.Design/methodology/approach: The study were based on the analysis of laser HPDL powder surfacing of titanium alloy plates using wide range chemical composition consumables of titanium alloys and mixtures of pure titanium and spherical powder of WC indicated that very hard and highest quality deposits are provided by powder mixture of 40-50%Ti+60-50%WC.Findings: It was found that it is possible to achieve high quality deposits, free of any defects. HPDL technology can be used to repair worn turbine blade.Research limitations/implications: It was found that it is possible to repair the worn areas abutments of blades of zero compression stage of aircraft engine turbine by HPDL laser surfacing with using composite powder mixture of 50%Ti+50%WC as an additional material.Practical implications: The technology can be applied for repair worn abutments of aircraft jet engine blades.Originality/value: Repairing worn abutments of aircraft jet engine blades.

  18. Axial clamp for nuclear reactor head penetration conoseal joints

    Energy Technology Data Exchange (ETDEWEB)

    Hackley, T.A.

    1987-03-31

    A method is described for forming a sealed coupling between two bodies, each body presenting an annular abutment surface. The respective bodies are arranged so that their respective annular abutment surfaces are axially adjacent one another, defining a space therebetween, wherein a deformable gasket is disposed within the space. The method comprises: providing one of the bodies with an annular projection; providing the other body with threads for receiving an annular locknut which can be tightened to bear against the annular projection of the one body; applying an external axial forced to the bodies for compressing the abutment surfaces together against the gasket to form a seal between the bodies; immobilizing the bodies relative to one another while the external force is being applied to the bodies by hand-tightening an annular locknut via the threads of the other body until the locknut abuts the annular projection of the one body, substantially preventing relative axial movement between the bodies when the external axial force is withdrawn; and withdrawing the external axial force applied to the bodies, leaving the two bodies coupled together via the seal.

  19. Consensus report - reconstructions on implants. The Third EAO Consensus Conference 2012

    DEFF Research Database (Denmark)

    Gotfredsen, Klaus; Wiskott, Anselm

    2012-01-01

    This group was assigned the task to review the current knowledge in the areas of implant connections to abutments/reconstructions, fixation methods (cement vs. screw retained) for implant-supported reconstructions, as well as the optimal number of implants for fixed dental prosthesis and implant...

  20. 口腔种植学专业名词(草案)%Terms of oral implantology(Draft)

    Institute of Scientific and Technical Information of China (English)

    中华口腔医学会口腔种植专业委员会

    2007-01-01

    @@ 说明:(1)按英文字母顺序排列;(2)[ ]内为注释 A abutment 基台 [ the portion of an implant above the neck used to provide support for a fixed, fixed-detachable, or removable dental prosthesis

  1. Factors affecting the possibility to detect buccal bone condition around dental implants using cone beam computed tomography

    DEFF Research Database (Denmark)

    Liedke, Gabriela S; Spin-Neto, Rubens; da Silveira, Heloisa E D;

    2016-01-01

    OBJECTIVES: To evaluate factors with impact on the conspicuity (possibility to detect) of the buccal bone condition around dental implants in cone beam computed tomography (CBCT) imaging. MATERIAL AND METHODS: Titanium (Ti) or zirconia (Zr) implants and abutments were inserted into 40 bone blocks...

  2. A 3-year prospective study of implant-supported, single-tooth restorations of all-ceramic and metal-ceramic materials in patients with tooth agenesis

    DEFF Research Database (Denmark)

    Hosseini, Mandana; Worsaae, Nils; Schiødt, Morten;

    2013-01-01

    -up examinations, the biological outcome variables such as survival rate of implants, marginal bone level, modified Plaque Index (mPlI), modified Sulcus Bleeding Index (mBI) and biological complications were registered. The technical outcome variables included abutment and crown survival rate, marginal adaptation...

  3. Clinical crown lengthening to improve implant results.

    Science.gov (United States)

    Kohner, J

    1992-01-01

    Clinical crown lengthening is used as an adjunct to implant procedures, and can help provide a better long-term prognosis by establishing proper occlusal planes and aiding in preparation of the abutment teeth. Crown lengthening procedures may be especially useful when caries or a fracture extends below the gingival margin, compromising impression taking and marginal fit.

  4. A rationale method for evaluating unscrewing torque values of prosthetic screws in dental implants

    Directory of Open Access Journals (Sweden)

    Felipe Miguel Saliba

    2011-02-01

    Full Text Available OBJECTIVES: Previous studies that evaluated the torque needed for removing dental implant screws have not considered the manner of transfer of the occlusal loads in clinical settings. Instead, the torque used for removal was applied directly to the screw, and most of them omitted the possibility that the hexagon could limit the action of the occlusal load in the loosening of the screws. The present study proposes a method for evaluating the screw removal torque in an anti-rotational device independent way, creating an unscrewing load transfer to the entire assembly, not only to the screw. MATERIAL AND METHODS: Twenty hexagonal abutments without the hexagon in their bases were fixed with a screw to 20 dental implants. They were divided into two groups: Group 1 used titanium screws and Group 2 used titanium screws covered with a solid lubricant. A torque of 32 Ncm was applied to the screw and then a custom-made wrench was used for rotating the abutment counterclockwise, to loosen the screw. A digital torque meter recorded the torque required to loosen the abutment. RESULTS: There was a significant difference between the means of Group 1 (38.62±6.43 Ncm and Group 2 (48.47±5.04 Ncm, with p=0.001. CONCLUSION: This methodology was effective in comparing unscrewing torque values of the implant-abutment junction even with a limited sample size. It confirmed a previously shown significant difference between two types of screws.

  5. 78 FR 18769 - Establishment of the First State National Monument

    Science.gov (United States)

    2013-03-28

    ... Court House and the New Castle Historic District, including the Green, the Sheriff's House, and numerous.... The Sheriff's House, abutting the Court House on the Green, is architecturally significant and is all... in fee, and an easement for the protection of and access to the New Castle Court House and the...

  6. Relationships of a growing magnetic flux region to flares

    NARCIS (Netherlands)

    Schadee, A.; Martin, S.F.; Bentley, R.D.; Antalova, A.; Kucera, A.; Dezs, L.; Gesztelyi, L.; Harvey, K.L.; Jones, H.; Livi, S.H.B.; Wang, J.

    1984-01-01

    Some sites for solar flares are known to develop where new magnetic flux emerges and becomes abutted against opposite polarity pre-existing magnetic flux (review by Galzauskas/1/). We have identified and analyzed the evolution of such flare sites at the boundaries of a major new and growing magnetic

  7. 75 FR 81187 - South Dakota: Final Authorization of State Hazardous Waste Management Program Revision

    Science.gov (United States)

    2010-12-27

    ..., ``Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use'' (66 FR... the State except for lands located within formal Indian Reservations within or abutting the State of South Dakota, including the Cheyenne River Indian Reservation, Crow Creek Indian Reservation,...

  8. A case of intrathoracic ectopic liver i a patient without diaphragmetic defect

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Geun; Ryu, Dae Shick; Park, Man Soo; Kang, Chae Hoon; Choi, Soo Jung; Shin, Dong Rock [Dept. of Radiology, Gangneung Asan Hospital, College of Medicine, University of Ulsan, Gangneung (Korea, Republic of)

    2016-06-15

    We reported a patient with intrathoracic ectopic liver without diaphragmatic defect that was incidentally detected on chest radiography. Chest dynamic CT showed a subpleural mass abutting the diaphragm with isodense enhancement to liver tissue during arterial and delayed images, suggesting intrathoracic ectopic liver.

  9. Clean-air video will interest MDs who treat patients with allergies, respiratory problems.

    Science.gov (United States)

    Rafuse, J

    1996-03-15

    Canada Mortgage and Housing Corporation wants physicians to help raise public awareness abut the importance of indoor air quality to health. Physicians across Canada are being sent a colourful poster that calls attention to indoor air pollution and ways to make a home healthier, included are order forms for the Clean Air Guide and a companion video, This Clean House. PMID:8634972

  10. Clean-air video will interest MDs who treat patients with allergies, respiratory problems.

    OpenAIRE

    Rafuse, J

    1996-01-01

    Canada Mortgage and Housing Corporation wants physicians to help raise public awareness abut the importance of indoor air quality to health. Physicians across Canada are being sent a colourful poster that calls attention to indoor air pollution and ways to make a home healthier, included are order forms for the Clean Air Guide and a companion video, This Clean House.

  11. Rail crash demonstration scenarios

    International Nuclear Information System (INIS)

    The paper describes the manner in which the rail crash scenario was selected for public demonstration. A simplified risk assessment led to the short listing of three contender scenarios involving a drop from a high level, a crash into an abutment and the crash of a train into a stationary flask. Predictive work led to the final selection of the train crash. (author)

  12. Experimental and computational investigation of Morse taper conometric system reliability for the definition of fixed connections between dental implants and prostheses.

    Science.gov (United States)

    Bressan, Eriberto; Lops, Diego; Tomasi, Cristiano; Ricci, Sara; Stocchero, Michele; Carniel, Emanuele Luigi

    2014-07-01

    Nowadays, dental implantology is a reliable technique for treatment of partially and completely edentulous patients. The achievement of stable dentition is ensured by implant-supported fixed dental prostheses. Morse taper conometric system may provide fixed retention between implants and dental prostheses. The aim of this study was to investigate retentive performance and mechanical strength of a Morse taper conometric system used as implant-supported fixed dental prostheses retention. Experimental and finite element investigations were performed. Experimental tests were achieved on a specific abutment-coping system, accounting for both cemented and non-cemented situations. The results from the experimental activities were processed to identify the mechanical behavior of the coping-abutment interface. Finally, the achieved information was applied to develop reliable finite element models of different abutment-coping systems. The analyses were developed accounting for different geometrical conformations of the abutment-coping system, such as different taper angle. The results showed that activation process, occurred through a suitable insertion force, could provide retentive performances equal to a cemented system without compromising the mechanical functionality of the system. These findings suggest that Morse taper conometrical system can provide a fixed connection between implants and dental prostheses if proper insertion force is applied. Activation process does not compromise the mechanical functionality of the system.

  13. Jicarilla Apaches.

    Science.gov (United States)

    Van Roekel, Gertrude B.

    Geronimo's surrender in 1886 ended some 200 years' warfare against encroaching white man in that broad area abutting the Rocky Mountains. Thus, the free-roaming period of Apache life, marked by repeated instances of bad faith and broken treaties, was ended and the Jicarilla Apaches were delivered to their reservation in northern New Mexico. The…

  14. [Resin-bonded fixed partial dentures

    NARCIS (Netherlands)

    Kreulen, C.M.; Creugers, N.H.J.

    2013-01-01

    A resin-bonded fixed partial denture is a prosthetic construction which can replace I or several teeth in an occlusal system and which comprises a pontic element which is adhesively attached to 1 or more abutment teeth. To compensate for the limited shear strength of the adhesive layer, the Jixed pa

  15. A New Design for Anterior Laminate Fixed-Partial dentures; PTU Type I

    Directory of Open Access Journals (Sweden)

    A. Pahlevan

    2006-03-01

    Full Text Available A new fixed-partial denture design using laminates is described for the replacement of a missing anterior tooth. In this article advantages, disadvantages, indications and contraindications of the new design have been discussed. This method is best suited forcases with missing incisors and esthetically compromised abutment teeth.

  16. A New Design for Anterior Laminate Fixed-Partial dentures; PTU Type I

    OpenAIRE

    A. Pahlevan

    2006-01-01

    A new fixed-partial denture design using laminates is described for the replacement of a missing anterior tooth. In this article advantages, disadvantages, indications and contraindications of the new design have been discussed. This method is best suited forcases with missing incisors and esthetically compromised abutment teeth.

  17. 30 CFR 717.18 - Dams constructed of or impounding waste material.

    Science.gov (United States)

    2010-07-01

    ... material. 717.18 Section 717.18 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT... demonstrated through appropriate engineering analysis, to have no adverse effect on stability. (2) Plans for... (cases II and III with seismic loading) 1.0 (iv) The dam, foundation, and abutment shall be stable...

  18. 30 CFR 715.18 - Dams constructed of or impounding waste material.

    Science.gov (United States)

    2010-07-01

    ... material. 715.18 Section 715.18 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT... engineering analysis, to have no adverse effect on stability. (2) Plans for dams subject to this section, and... loading) 1.0 (iv) The dam, foundation, and abutments shall be stable under all conditions of...

  19. Peri-implant tissue behavior around non-titanium material: Experimental study in dogs.

    Science.gov (United States)

    Maté Sánchez de Val, José Eduardo; Gómez-Moreno, Gerardo; Pérez-Albacete Martínez, Carlos; Ramírez-Fernández, Maria Piedad; Granero-Marín, Jose Manuel; Gehrke, Sergio Alexandre; Calvo-Guirado, José Luis

    2016-07-01

    The aim of this study is to assess the effectiveness of using non-titanium abutments for better establishment of peri-implant biological width and to assess the stability of the soft tissue. Forty-eight tapered dental titanium implants with internal connection of 3.5mm in diameter and 10mm length were implanted in post extraction alveoli of 6 dogs. Twenty-four abutments made in a reinforced polyetheretherketone (PEEK) formed the test group, and 24 titanium abutments, the control group. The groups were randomized. Histological, histomorphometric, ISQ and radiological analyses were performed. Greatest differences (control group vs. test group) were found at PM-Lc (Mucosa to lingual bone contact) (2.91±0.03 vs. 3.71±0.18), and to PM Lingual-IS (2.65±0.43 vs. 3.57±0.38). Reinforced PEEK constitutes an effective alternative to conventional titanium abutments, given its high rate of biocompatibility, preservation of bone height and soft tissue stability. PMID:27045596

  20. 76 FR 12102 - Pacific Gas and Electric Company; Notice of Preliminary Permit Application Accepted for Filing...

    Science.gov (United States)

    2011-03-04

    ... Gas and Electric Company; Notice of Preliminary Permit Application Accepted for Filing and Soliciting Comments, Motions to Intervene, and Competing Applications On January 31, 2011, Pacific Gas and Electric... and generator constructed on the right (west) abutment at the downstream side of the existing...

  1. CORROSION RESISTANT JACKETED METAL BODY

    Science.gov (United States)

    Brugmann, E.W.

    1958-08-26

    Reactor faul elements of the elongated cylindrical type which are jacketed in a corrosion resistant material are described. Each feel element is comprised of a plurality of jacketed cylinders of fissionable material in end to end abutting relationship, the jackets being welded together at their adjoining ends to retain the individual segments together and seat the interior of the jackets.

  2. [A PhD completed 3. Soft tissue development around an implant in the aesthetic zone].

    Science.gov (United States)

    Patil, R C

    2016-01-01

    A randomised clinical trial was carried out in order to determine whether changes in the abutment design result in improved quality of the peri-implant mucosal tissue according to the parameters attachment strength, sotft tissue stability and developmemt, and maintenance of bone levels. Twenty-nine patients were included. They received 2, non-adjacent endosseous implants replacing missing teeth in the aesthetic zone. Subsequently, conventional (control) and experimental abutments (with an additional macro groove of about 0.5 mm in depth ) were placed. After 6 weeks and 1 year the effect of the 2 different abutment designs were measured according to the specified parameters. In addition, patients' and dentists' satisfaction concerning the muco-gingival results were compared. It was concluded that the 2 abutments produced no significantly different effect on muco-gingival aesthetics. On the basis of additional comparative research between Caucasian and Indian individuals it was concluded that the gingival biotype could best be determined quantitatively. PMID:27430041

  3. Microbiological and biochemical effectiveness of an antiseptic gel on the bacterial contamination of the inner space of dental implants: a 3-month human longitudinal study.

    Science.gov (United States)

    D'Ercole, S; Tetè, S; Catamo, G; Sammartino, G; Femminella, B; Tripodi, D; Spoto, G; Paolantonio, M

    2009-01-01

    Microbial penetration inside the implants internal cavity produces a bacterial reservoir that is associated with an area of inflamed connective tissue facing the fixture-abutment junction. The aim of this clinical trial is to evaluate the effectiveness of a 1 percent chlorhexidine gel on the internal bacterial contamination of implants with screw-retained abutments and on the level of AST secreted in peri-implant crevicular fluid. Twenty-five patients (aged 29 to 58 years) each received one implant. Three months after the end of the restorative treatment, and immediately after a clinical and radiographic examination and the abutment removal, microbiological samples were obtained from the internal part of each fixture and biochemical samples were collected by peri-implant sulci. The patients were then divided into two groups: the control (CG; n=10) and test (TG; n=15) groups. The CG had the abutment screwed into place and the crown cemented without any further intervention. In contrast, before the abutment placement and screw tightening, the TG had the internal part of the fixture filled with a 1 percent chlorhexidine gel. Three months later, the same clinical, microbiological and biochemical procedures were repeated in both groups. Total bacterial count, specific pathogens and AST activity were detected. The clinical parameters remained stable throughout the study. From baseline to the 3-month examination, the total bacterial counts underwent a significant reduction only in the TG. In contrast, the AST activity showed a significant increase in the CG. The administration of a 1% chlorhexidine gel appears to be an effective method for the reduction of bacterial colonization of the implant cavity and for safeguarding the health status of peri-implant tissue over a 3-month administration period.

  4. Group D. Initiator paper. Implants--peri-implant (hard and soft tissue) interactions in health and disease: the impact of explosion of implant manufacturers.

    Science.gov (United States)

    Ivanovski, Saso

    2015-01-01

    1. The best-documented implants have a threaded solid screw-type design and are manufactured from commercially pure (grade IV) titanium. There is good evidence to support implants ≥ 6 mm in length, and ≥ 3 mm in diameter. 2. Integrity of the seal between the abutment and the implant is important for several reasons, including minimization of mechanical and biological complications and maintaining marginal bone levels. Although the ideal design features of the implant-abutment connection have not been determined, an internal connection, micro-grooves at the implant collar, and horizontal offset of the implant-abutment junction (platform switch) appear to impart favorable properties. 3. Implants with moderately rough implant surfaces provide advantages over machined surfaces in terms of the speed and extent of osseointegration. While the favorable performances of both minimally and moderately rough surfaces are supported by long-term data, moderately rough surfaces provide superior outcomes in compromised sites, such as the posterior maxilla. 4. Although plaque is critical in the progression of peri-implantitis, the disease has a multi-factorial aetiology, and may be influenced by poor integrity of the abutment/implant connection. Iatrogenic factors, such as the introduction of a foreign body. (e.g., cement) below the mucosal margin, can be important contributors. 5. Clinicians should exercise caution when using a particular implant system, ensuring that the implant design is appropriate and supported by scientific evidence. Central to this is access to and participation in quality education on the impact that implant characteristics can have on clinical outcomes. Caution should be exercised in utilizing non-genuine restorative componentry that may lead to a poor implant-abutment fit and subsequent technical and biological complications. PMID:25764593

  5. Machined and plastic copings in three-element prostheses with different types of implantabutment joints: a strain gauge comparative analysis

    Directory of Open Access Journals (Sweden)

    Renato Sussumu Nishioka

    2010-06-01

    Full Text Available OBJECTIVE: Using strain gauge (SG analysis, the aim of this in vitro study was quantify the strain development during the fixation of three-unit screw implant-supported fixed partial dentures, varying the types of implant-abutment joints and the type of prosthetic coping. The hypotheses were that the type of hexagonal connection would generate different microstrains and the type of copings would produce similar microstrains after prosthetic screws had been tightened onto microunit abutments. MATERIALS AND METHODS: Three dental implants with external (EH and internal (IH hexagonal configurations were inserted into two polyurethane blocks. Microunit abutments were screwed onto their respective implant groups, applying a torque of 20 Ncm. Machined Co-Cr copings (M and plastic prosthetic copings (P were screwed onto the abutments, which received standard wax patterns. The wax patterns were cast in Co-Cr alloy (n=5, forming four groups: G1 EH/M; G2 EH/P; G3 IH/M and G4 IH/P. Four SGs were bonded onto the surface of the block tangentially to the implants, SG 1 mesially to implant 1, SG 2 and SG 3 mesially and distally to implant 2, respectively, and SG 4 distally to implant 3. The superstructure's occlusal screws were tightened onto microunit abutments with 10 Ncm torque using a manual torque driver. The magnitude of microstrain on each SG was recorded in units of microstrain (µε. The data were analyzed statistically by ANOVA and Tukey's test (p0.05. The hypotheses were partially accepted. CONCLUSIONS: It was concluded that the type of hexagonal connection and coping presented similar mechanical behavior under tightening conditions.

  6. All-ceramic and porcelain-fused-to-metal fixed partial dentures: a comparative study by 2D finite element analyses

    Directory of Open Access Journals (Sweden)

    Andréa Barreira Motta

    2007-10-01

    Full Text Available All-ceramic fixed partial dentures (FPDs have an esthetic approach for oral rehabilitation. However, metal-ceramic FPDs are best indicated in the posterior area where the follow-up studies found a lower failure rate. This 2D finite element study compared the stress distribution on 3-unit all-ceramic and metal-ceramic FPDs and identified the areas of major risk of failure. Three FPD models were designed: (1 metal-ceramic FPD; (2 All-ceramic FPD with the veneering porcelain on the occlusal and cervical surface of the abutment tooth; (3 All-ceramic FPD with the veneering porcelain only on the occlusal surface. A 100 N load was applied in an area of 0.5 mm² on the working cusps, following these simulations: (1 on the abutment teeth and the pontic; (2 only on the abutment teeth; and (3 only on the pontic. Relative to the maximum stress values found for the physiological load, all-ceramic FPD with only occlusal veneering porcelain produced the lowest stress value (220 MPa, followed by all-ceramic FPD with cervical veneering porcelain (322 MPa and metal-ceramic FPD (387 MPa. The stress distribution of the load applied on the abutments was significantly better compared to the other two load simulations. The highest principal stress values were low and limited in a small area for the three types of models under this load. When the load was applied on the pontic, the highest stress values appeared on the connector areas between the abutments and pontic. In conclusion, the best stress values and distribution were found for the all-ceramic FPD with the veneering porcelain only on the occlusal surface. However, in under clinical conditions, fatigue conditions and restoration defects must be considered.

  7. Periodontal considerations of the removable partial overdenture.

    Science.gov (United States)

    Gomes, B C; Renner, R P

    1990-10-01

    1. An overdenture, whether complete or partial, is an excellent mode of treatment in the mutilated dentition for the preservation of the residual ridge. 2. Selection of patients for an overdenture should be based on past history of dental neglect, the status of the teeth and their periodontium, including present oral hygiene status, and patient motivation. The patients with a history of dental neglect, poor oral hygiene, and lack of motivation in having the teeth and the periodontium restored to health as well as strict compliance to a home-care regimen and recall schedule are not good candidates for treatment with an overdenture. 3. The choice of teeth or roots to serve as overdenture abutments must include their periodontal evaluation, which should consist of a detailed periodontal examination, diagnosis, prognosis, and treatment when this is indicated, including chemical protection (fluoride gel) and an oral hygiene regimen tailored to individual needs. 4. The knowledge and expertise in the selection and implementation of appropriate periodontal treatment modalities is of paramount importance in restoring optimum periodontal health to the overdenture abutments before overdenture fabrication. 5. The maintenance phase of the overdenture abutments as well as of the existing natural teeth is of critical importance in the preservation of health of these abutments and teeth. This maintenance phase should consist of periodic recalls based on individual needs; a detailed periodontal evaluation, including patient's motivation and status of oral hygiene and denture hygiene; and detection of caries. If necessary, appropriate periodontal and/or restorative therapy should be performed, and oral hygiene measures reinforced. This will ensure longevity of both abutment teeth or roots and of the existing natural teeth resulting in a long-term success of an overdenture. 6. Because there is evidence of high incidence of periodontal disease and dental caries in overdenture wearers

  8. 三种不同连接方式的天然牙—游离端种植体联合支持的 固定义齿集中载荷应力分析%Three-dimensional finite element analysis of three different connectors used in fixed partial denture supported by the combination of an natural tooth and extensional implant—stress analysis under concentrated loading

    Institute of Scientific and Technical Information of China (English)

    白雪芹; 周延民; 周振平; 许力强

    2001-01-01

    Objective To analyze the stress value and the stress distributionunder concentrated loading for three different connectors used in the fixed partial denture supported by the combination of an natural tooth and extensional implant.Methods Three-dimensional finite element stress analysis method was used.Results ①The maximal stress value of the implant abutment was higher than the maximal stress value of the nature tooth for the rigid connector of fixed partial denture;②When we used rigid attachments.The maximal stress value of the implant abutment was the highest;③When resilient attachment was used the maximal stress value of the implant abutment was the lowest.Conclusion ①Rigid connector of fixed partial denture may damage the implant abutments and the protect measurement must be taken;②Rigid attachment of fixed partial denture destructs the implant abutment mostly;③Resiliant attachment design is the protection function for the implant abutments.%目的 研究三种不同连接方式的天然牙——游离端种植体联合支持的固定义齿在集中载荷下的应力值和应力分布。方法 应用三维有限元应力分析法。结果 ①固定连接式固定义齿的种植体基牙应力峰值高于天然牙;②刚性栓道式固定义齿的种植体基牙应力峰值最高;③缓冲式固定义齿的种植体基牙应力峰值最低。结论 ①固定连接式固定义齿设计可能损伤种植体基牙,需采取适当措施;②刚性栓道式固定义齿设计对种植体基牙损伤最大;③缓冲式固定义齿设计有利于保护种植体基牙。

  9. Long-term effects of biodegradable versus durable polymer-coated sirolimus-eluting stents on coronary arterial wall morphology assessed by virtual histology intravascular ultrasound

    Institute of Scientific and Technical Information of China (English)

    LIU Hui-liang; ZHANG Jiao; JIN Zhi-geng; LUO Jian-ping; MA Dong-xing; YANG Sheng-li; LIU Ying; HAN Wei; JING Li-min; MENG Rong-ying

    2011-01-01

    Background The durable presence of polymer coating on drug-eluting stent (DES) surface may be one of the principal reasons for stent thrombosis. The long-term coronary arterial response to biodegradable polymer-coated sirolimus-eluting stent (BSES) in vivo remained unclear.Methods Forty-one patients were enrolled in this study and virtual histology intravascular ultrasound (VH-IVUS) was performed to assess the native artery vascular responses to BSES compared with durable polymer-coated SES (DSES) during long-term follow-up (median: 8 months). The incidence of necrotic core abutting to the lumen was evaluated at follow-up.Results With similar in-stent late luminal loss (0.15 mm (0.06-0.30 mm) vs. 0.19 mm (0.03-0.30 mm), P=0.772), the overall incidence of necrotic core abutting to the lumen was significantly less in BSES group than in DSES group (44% vs.63%, P <0.05) (proximal 18%, stented site 14% and distal 12% in BSES group, proximal 19%, stented site 28% and distal 16% in DSES group). The DSES-treated segments had a significant higher incidence of necrotic core abutting to the lumen through the stent struts (73% vs. 36%, P <0.01). In addition, more multiple necrotic core abutting to the lumen was observed in DSES group (overall: 63% vs. 36%, P <0.05). Furthermore, when the stented segments with necrotic core abutting to the lumen had been taken into account only, DSES-treated lesions tended to contain more multiple necrotic core abutting to the lumen through the stent struts than BSES-treated lesions (74% vs. 33%), although there was no statistically significant difference between them (P=0.06).Conclusions By VH-IVUS analysis at follow-up, a greater frequency of stable lesion morphometry was shown in lesions treated with BSESs compared with lesions treated with DSESs. The major reason was BSES produced less toxicity to the arterial wall and facilitated neointimal healing as a result of polymer coating on DES surface biodegraded as time went by.

  10. Internal erosion under spillway rested on an embankment dam

    Directory of Open Access Journals (Sweden)

    Mohammad Sedghi-Asl

    2015-12-01

    Full Text Available In this paper we investigate the mechanism of internal erosion caused in the right abutment of the Shahghasem dam’s spillway. Shahghasem dam is an earthen dam located in Yasouj, in southwest of Iran. A significant hole and pipe have been observed in the corner of the right abutment from upstream view. The foundation is Marlstone, which has low cohesion and susceptible for internal erosion and piping in some conditions. Going through details of the design maps has shown that Lane’s criteria for selecting safe dimensions of the seepage control measures have not been considered properly. A series of the supportive walls are designed to attach to the right part of the spillway in order to increase the length of seepage. The pipe route of the erosion should also be grouted with high quality concrete.

  11. A 2-year report on maxillary and mandibular fixed partial dentures supported by Astra Tech dental implants. A comparison of 2 implants with different surface textures

    DEFF Research Database (Denmark)

    Karlsson, U; Gotfredsen, K; Olsson, C

    1998-01-01

    In 50 partially edentulous patients, 133 (48 maxillary; 85 mandibular) Astra Tech dental implants of 2 different surface textures (machined; TiO-blasted) were alternately installed, supporting 52 fixed partial dentures (FPDs). Before abutment connection 2 machined implants (1 mandibular; 1...... maxillary) were found to be non-osseointegrated and were replaced. Another implant could not be restored due to a technical complication. Two FPDs were remade because of technical complications, both because of abutment fractures. Thus, after 2 years in function, the cumulative survival rates were 97.......7% and 95.7% for implants and prostheses, respectively. There was no statistically significant difference in survival rate between the 2 types of implants, 100% (TiO-blasted) vs 95.3% (machined), P = 0.24. After 2 years in function, when both jaw and type of implants were combined, the mean (SD) marginal...

  12. Study of mechanical principle of floor heave of roadway driving along next goaf in fully mechanized sub-level caving face

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-jun; HOU Chao-jiong

    2001-01-01

    On the basis of analyzing floor strata mechanical circumstance of the roadway, the mechanical model was established. The relative displacement of roadway floor, narrow pillar floor coal mass and floor strata was calculated, the results showed that the high abutment pressure on coal mass beside the roadway was the main reason to lead to relative displacement of floor stra ta. And the roadway floor heave come mainly from three aspects. Firstly, the roadway floor strata is easily fractured by the stretch stress. Secondly, because the high abutment pressure is greater than the uniaxial compressive strength of floor strata, when the roadway floor strata are fractured, the coal mass floor strata at the same depth will be fractured, and broken rock will fluid into the open roadway. Thirdly, comparing with the coal mass floor, the roadway floor is relative ascending

  13. Establishing time-dependent model of deformation modulus caused by bedrock excavation rebound by inverse analysis method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Rock rebound relaxation deformation,or even rock burst,caused by the excavation of dam base and abutment or high rock slope affects their stability and results in the fall of mechanical properties of the rock.So an inverse analysis method was proposed in this paper to establish the time-dependent model of deformation modulus caused by excavation rebound.The basic principle is based on the combination of observed data of the excavation rebound deformation of dam abutment or rock slope,and the calculated rebound deformation by FEM under ground stress at the corresponding time in the excavation process.The norm of the residuals of observed data and calculated data are taken as the objective function.Accordingly,the time-dependent model of bedrock deformation modulus can be established.The method displays its significance in the design of excavation,construction and operation management of dam base and high slope.

  14. Temporary space maintainers retained with composite resin. Part II: Fracture load in vitro.

    Science.gov (United States)

    Grajower, R; Stern, N; Zamir, S T; Kohavi, D

    1981-01-01

    The average fracture load during occlusal loading of pontics which were bonded to natural abutment teeth in vitro was found to be 56.1, 57.5 and 74.2 kg for natural, acrylic resin, and Restodent pontics, respectively. Coating the roots of the abutment teeth with a thin layer of silicone rubber before embedding them in stone slightly reduced the strength of the fixed partial dentures. Thermocycling the specimens with coated roots caused a considerable decrease in strength to fracture loads of 33.0, 17.9, and 37.3 kg for natural, acrylic resin, and Restodent pontics, respectively. Fracture of the enamel of natural tooth pontics was observed in a few specimens. The superior strength of the fixed partial dentures with natural tooth and Restodent pontics would indicate that these pontics are superior for clinical trials rather than acrylic resin pontics.

  15. Clinical evaluation of simple fixed space maintainers bonded with flow composite resin.

    Science.gov (United States)

    Simsek, Sera; Yilmaz, Yucel; Gurbuz, Taskin

    2004-01-01

    The aim of this study was to evaluate the clinical performance of simple fixed space maintainers bonded by using a flow composite resin (Tetric Flow) to prevent space resulting from early extracted primary teeth. For that reason, 64 fixed space maintainers (34 in the lower jaw and 30 in the upper jaw) were applied to 45 patients. The patients followed up for 12 to 18 months. Survival rate, prevention ability of that space, and whether damage to the abutment teeth occurred were evaluated. Five percent of space maintainers were determined to be unsuccessful at the end of the control period. During this period, loss of space among the abutment teeth was found to be statistically insignificant (P > .05). Finally, it was observed that the use of simple fixed space maintainers was successful due to operator experience and the choosing of favorable patient groups.

  16. Modular fuel-cell stack assembly

    Science.gov (United States)

    Patel, Pinakin

    2010-07-13

    A fuel cell assembly having a plurality of fuel cells arranged in a stack. An end plate assembly abuts the fuel cell at an end of said stack. The end plate assembly has an inlet area adapted to receive an exhaust gas from the stack, an outlet area and a passage connecting the inlet area and outlet area and adapted to carry the exhaust gas received at the inlet area from the inlet area to the outlet area. A further end plate assembly abuts the fuel cell at a further opposing end of the stack. The further end plate assembly has a further inlet area adapted to receive a further exhaust gas from the stack, a further outlet area and a further passage connecting the further inlet area and further outlet area and adapted to carry the further exhaust gas received at the further inlet area from the further inlet area to the further outlet area.

  17. Frequency and spectrum of abnormalities in the bone marrow of the wrist: MR imaging findings

    Energy Technology Data Exchange (ETDEWEB)

    Alam, F.; Schweitzer, M.E. (Thomas Jefferson Univ., Philadelphia, PA (United States). Dept. of Radiology); Li Xiaoxian (Dept. of Radiology, Tangshan Gongren Hospital, Tangshan (China)); Malat, J. (Department of Radiology, Naples Radiologists, Naples (Italy)); Hussain, S.M. (Thomas Jefferson Univ., Philadelphia, PA (United States). Dept. of Radiology Rijksuniversiteit Leiden (Netherlands). Dept. of Diagnostic Radiology)

    1999-06-01

    Objective. To describe the frequency of marrow abnormalities on wrist MR imaging and the MR findings of these various abnormalities.Design and patients. Five hundred and nineteen patients were studied at 1.5 T. Two observers recorded the presence and location of avascular necrosis, occult fractures and arthritic edema [focal osteoarthritis, ulnolunate abutment, rheumatoid arthritis, septic arthritis, gouty arthritis and scapholunate advanced collapse (SLAC)].Results and conclusion. One hundred and eighty-seven (36%) patients demonstrated marrow abnormalities in the wrist, of which 101 were diagnosed as arthritis [64 (34%) as focal osteoarthritis, 17 (9%) as ulnolunate abutment, 15 (8%) as rheumatoid arthritis, 2 as septic arthritis, 2 as SLAC, and 1 as gouty arthritis]. Seventy-two patients had occult fractures and in 27 patients avascular necrosis was seen. MR imaging can reveal various abnormalities in bone marrow of the wrist when findings on radiography are normal or equivocal. (orig.) With 17 figs., 13 refs.

  18. Fabrication of a screw-retained restoration avoiding the facial access hole: a clinical report.

    Science.gov (United States)

    Garcia-Gazaui, Sabrina; Razzoog, Michael; Sierraalta, Marianella; Saglik, Berna

    2015-11-01

    Dental implant restorations may be either screw-retained or cemented onto an abutment. While each method has its advantages and disadvantages, cemented restorations are commonly used in the maxillary arch, usually because of esthetic concerns. Available bone in the anterior maxilla dictates the placement of the implant, which may result in a facially positioned screw-access opening. Still, a growing volume of literature states that periimplant soft tissues respond more favorably to screw-retained crowns than cement-retained crowns. This clinical report outlines a treatment with a new method of fabricating a custom abutment-crown combination for a screw-retained restoration. The technique allows the channel for the screw to be placed at an angle other than parallel to the implant body. In this case, the practitioner may choose either a screw-retained or cement-retained implant restoration, where previously only a cemented restoration was possible. PMID:26344192

  19. Fiber-reinforced composites in fixed partial dentures

    Directory of Open Access Journals (Sweden)

    Vallittu P

    2006-08-01

    Full Text Available Fiber-reinforced composite resin (FRC prostheses offer the advantages of good esthetics, minimal invasive treatment, and an ability to bond to the abutment teeth, thereby compensating for less-than-optimal abutment tooth retention and resistance form. These prostheses are composed of two types of composite materials: fiber composites to build the framework and hybrid or microfill particulate composites to create the external veneer surface. This review concentrates on the use of fiber reinforcement in the fabrication of laboratory or chairside-made composite-fixed partial dentures of conventional preparation. Other applications of FRC in dentistry are briefly mentioned. The possibilities fiber reinforcement technology offers must be emphasized to the dental community. Rather than limiting discussion to whether FRC prostheses will replace metal-ceramic or full-ceramic prostheses, attention should be focused on the additional treatment options brought by the use of fibers. However, more clinical experience is needed.

  20. Vcsel structure

    DEFF Research Database (Denmark)

    2015-01-01

    The invention relates to a VCSEL structure based on a novel grating reflector. The grating reflector comprises a grating layer with a contiguous core grating region having a grating structure, wherein an index of refraction of high-index sections of the grating structure is at least 2.......5, and wherein an index of refraction of low-index sections of the grating structure is less than 2. The core grating region defines a projection in a direction normal to the grating layer. The grating reflector further comprises a cap layer abutting the grating layer, and an index of refraction of the cap layer...... the projection of the core grating region, the grating layer is also abutted by a second low-index layer and/or by air, an index of refraction of the second low-index layer or air being less than 2. The VCSEL structure furthermore comprises a first reflector and an active region for providing a cavity...

  1. Mandibular implant-retained overdenture: a clinical trial of two anchorage systems.

    Science.gov (United States)

    Menicucci, G; Lorenzetti, M; Pera, P; Preti, G

    1998-01-01

    This in-vivo study aimed to investigate the load on the working-side implant and on the edentulous distal mucosa of the nonworking side in a mandibular implant-retained overdenture (MIR-OVD) anchored to 2 implants by either a ball- or a clips-and-bar attachment. Three female patients were provided with duplicate dentures anchored in the 2 ways. Strain on the implant was investigated using a strain-gauged abutment, and load on the mucosa was measured using a suitably placed load cell. Ball attachments appeared to provide greater stability to the MIR-OVD, since load was more evenly distributed onto the distal mucosa of both sides. When the MIR-OVD was bar-anchored, axial load on the working-side abutment increased. PMID:9857597

  2. Complex fixed implant-supported restoration in a site compromised by periodontitis: a case report.

    Science.gov (United States)

    Happe, Arndt; Kunz, Andreas

    2016-01-01

    Periodontal disease presents a big challenge for clinicians placing dental implants. Besides the implant treatment, additional surgical procedures such as grafting or sinus floor elevation are often necessary to achieve a satisfactory result. Patient compliance is also important for achieving long-term treatment success. In the case presented here, digital planning and computer-aided surgery facilitated placement of the implants and fabrication of the prosthetic superstructures. The patient then wore INTERNAT IONAL metal-based provisional fixed partial dentures (FPDs) for about a year, while her compliance and oral hygiene were evaluated. During this period, the occlusal relations remained stable and the good condition of the hard and soft tissue was maintained. In the maxilla, the final restoration incorporated custom zirconia abutments and a zirconia framework fabricated using CAD/CAM technology. Titanium abutments and a cast non-precious metal framework were fabricated for the mandible. PMID:27092346

  3. A clinical study on relationship of dental caries and removable partial denture of the aged patients%老年患者基牙龋病与可摘局部义齿关系的临床研究

    Institute of Scientific and Technical Information of China (English)

    李行懿; 陈娜; 刘聪

    2011-01-01

    Objective To characterize (patterns of caries after placing RPD. Methods A total of 95 patients were included in this study. A clinical examination of caries lesions on abutment teeth was conducted by me. Results The incidence of caries on abutment teeth and on nonabutment teeth were respectively 23. 67% and 3. 45%. ( P < 0.05). 27.49% of abutment teeth had new caries on the posterior oral cavity, onlyl3.89% of that on the anterior oral cavity. (P<0. 05). The incidence of caries on proximal surfaces adjacent to dentures was 25. 72% , under denture rests was 9. 33% , on root surfaces was 3. 02% , on tooth surfaces in contact with denture clasps was 1. 36% . The incidence of caries on abutment teeth of three groups classified by the oral hygienic habit were respectively 8. 91% 、24. 09%、44. 29% (P<0.01). Conclusion RPD wearers had more caries incidence. Abutment teeth had a higher of incidence of caries than nonabutment teeth. On the posterior oral cavity, abutment teeth had more caries incidence. Proximal surfaces adjacent to dentures abutment teeth had more caries incidence. Proximal surfaces adjacent to dentures were at highest risk of being decayed, surfaces under denture rests were next. The incidence of root caries on abutment teeth significantly increased. The incidence of caries on tooth surfaces in contact with denture clasps was not high.%目的 观察老年患者戴用可摘局部义齿2-3年后的龋病发病情况及其临床特点.方法 对95例戴用可摘局部义齿2-3年患者的基牙和非基牙的龋齿发病情况进行检查.结果 基牙龋齿发病率23.67%高于非基牙3.45%(P<0.05).口腔后部基牙龋齿发病率27.49%高于口腔前部基牙13.89%(P<0.05).基牙邻接面龋发病率25.72%,支托窝龋发病率9.33%,根面龋发病率3.02%,卡环龋发病率1.36%.口腔卫生习惯优、良、差三级的基牙龋齿发病率分别为8.91%、24.09%、44.29%,差异有显著性(P<0.01).结论 患者戴用可摘局部义齿后易患龋

  4. Numerical and experimental analysis of an in-scale masonry cross-vault prototype up to failure

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, Michela; Calderini, Chiara; Lagomarsino, Sergio [Department of Civil, Chemical and Environmental Engineering, University of Genoa, Via Montallegro 1, Genoa (Italy); Milani, Gabriele [Department of Architecture, Built Environment and Construction Engineering, Milan Polytechnic University, Piazza Leonardo da Vinci 32, Milan (Italy)

    2015-12-31

    A heterogeneous full 3D non-linear FE approach is validated against experimental results obtained on an in-scale masonry cross vault assembled with dry joints, and subjected to various loading conditions consisting on imposed displacement combinations to the abutments. The FE model relies into a discretization of the blocks by means of few rigid-infinitely resistant parallelepiped elements interacting by means of planar four-noded interfaces, where all the deformation (elastic and inelastic) occurs. The investigated response mechanisms of vault are the shear in-plane distortion and the longitudinal opening and closing mechanism at the abutments. After the validation of the approach on the experimentally tested cross-vault, a sensitivity analysis is conducted on the same geometry, but in real scale, varying mortar joints mechanical properties, in order to furnish useful hints for safety assessment, especially in presence of seismic action.

  5. Membranes and Bone Substitutes in a One-Stage Procedure for Horizontal Bone Augmentation: A Histologic Double-Blind Parallel Randomized Controlled Trial.

    Science.gov (United States)

    Merli, Mauro; Moscatelli, Marco; Mariotti, Giorgia; Pagliaro, Umberto; Breschi, Lorenzo; Mazzoni, Annalisa; Nieri, Michele

    2015-01-01

    The aim of this histologic, double-blind, parallel, randomized controlled trial was to compare anorganic bone mineral-collagen membranes (BB) and betatricalcium phosphate-pericardium collagen membranes (CJ) in a one-stage procedure for horizontal bone augmentation. A biopsy was performed in the regenerated area at abutment connection 6 months after surgery. Five patients were assigned and treated with the BB combination and five patients were treated with the CJ combination. At abutment connection, 6 months after grafting, no significant differences were evident in the histomorphometric comparisons, even if the percentage of residual graft, using the marrow spaces and soft tissue as a reference, tended to be greater in the CJ group (P = .0759). PMID:26133135

  6. Turbocharger with variable nozzle having vane sealing surfaces

    Science.gov (United States)

    Arnold, Philippe; Petitjean, Dominique; Ruquart, Anthony; Dupont, Guillaume; Jeckel, Denis

    2011-11-15

    A variable nozzle for a turbocharger includes a plurality of vanes rotatably mounted on a nozzle ring and disposed in a nozzle flow path defined between the nozzle ring and an opposite nozzle wall. Either or both of the faces of the nozzle ring and nozzle wall include(s) at least one step that defines sealing surfaces positioned to be substantially abutted by airfoil surfaces of the vanes in the closed position of the vanes and to be spaced from the airfoil surfaces in positions other than the closed position. This substantial abutment between the airfoil surfaces and the sealing surfaces serves to substantially prevent exhaust gas from leaking past the ends of the airfoil portions. At the same time, clearances between the nozzle ring face and the end faces of the airfoil portions can be sufficiently large to prevent binding of the vanes under all operating conditions.

  7. Influence of post and core materials on distortion around 4-unit zirconia bridge margins.

    Science.gov (United States)

    Inagaki, Tasuku; Komada, Wataru; Nemoto, Reina; Yoshida, Keiichi; Miura, Hiroyuki

    2014-01-01

    The purpose of this study was to evaluate the surface strain of zirconia fixed partial denture frameworks and their abutment roots when restored with two types of post and core materials. Artificial mandibular first premolars and second molars were used as the abutment teeth. Posts and cores were of two types: resin composite with glass fiber posts (RC) and cast platinum gold alloy (MC). The cores and 4-unit zirconia frameworks were bonded to the specimens. Static loading was applied to the occlusal surfaces, and the surface strain of the frameworks and roots (distal premolar and mesial molar) was measured by strain gauge method. Premolar root showed a significantly higher magnitude of principal strain than molar root. RC showed a significantly higher magnitude of principal strain than MC. The results suggest that MC restrain the surface strain compared to RC when the missing teeth are replaced by a 4-unit zirconia framework. PMID:24786351

  8. Yuba River analysis aims to aid spring-run chinook salmon habitat rehabilitation

    OpenAIRE

    Pasternack, Gregory; Fulton, Aaron A; Morford, Scott L

    2010-01-01

    Spring-run chinook salmon historically migrated far upstream into Sierra Nevada rivers but are now confined to gravel-limited reaches below large dams ringing the Central Valley. In this study, topographic analysis and photo interpretation reveal the 100-year history of channel conditions in the bedrock canyon on the Yuba River below Englebright Dam, which also abuts the UC Sierra Foothill Research and Extension Center. Historical evidence shows that alluvial bars provided spring-run chinook ...

  9. Application of a new precision attachment for bilateral free ended partial edentulism: a case report

    OpenAIRE

    Tokar, Emre; Uludağ, Bülent; Karacaer, Özgül

    2013-01-01

    INTRODUCTION: Metal parts or metal endings of removable partial dentures become visible especially during smile and this condition constitutes a major disadvantage for partial edentulous patients with high esthetic expectations. Precision attachments are used as direct retainer transmitting less stress to abutments and they provide better esthetics compared to classic clasp of a removable partial denture.CASE REPORT: This clinical report describes application of combined denture with resilien...

  10. Impact of collimator leaf width and treatment technique on stereotactic radiosurgery and radiotherapy plans for intra- and extracranial lesions

    OpenAIRE

    Lu Mei; Meyer Jeffrey J; Chang Zheng; Kirkpatrick John P; Wang Zhiheng; Wu Q Jackie; Huntzinger Calvin; Yin Fang-Fang

    2009-01-01

    Abstract Background This study evaluated the dosimetric impact of various treatment techniques as well as collimator leaf width (2.5 vs 5 mm) for three groups of tumors – spine tumors, brain tumors abutting the brainstem, and liver tumors. These lesions often present challenges in maximizing dose to target volumes without exceeding critical organ tolerance. Specifically, this study evaluated the dosimetric benefits of various techniques and collimator leaf sizes as a function of lesion size a...

  11. Comparative study on stress distribution around internal tapered connection implants according to fit of cement- and screw-retained prostheses

    OpenAIRE

    Lee, Mi-Young; Heo, Seong-Joo; Park, Eun-Jin; Park, Ji-Man

    2013-01-01

    PURPOSE The aim of this study was to compare the passivity of implant superstructures by assessing the strain development around the internal tapered connection implants with strain gauges. MATERIALS AND METHODS A polyurethane resin block in which two implants were embedded served as a measurement model. Two groups of implant restorations utilized cement-retained design and internal surface of the first group was adjusted until premature contact between the restoration and the abutment comple...

  12. Comparison of the marginal gap of zirconia-fabricated copings generated by CAD/CAM and Copy-Milling methods

    OpenAIRE

    Abdolhamid Alhavaz; Ladan Jamshidy

    2015-01-01

    Introduction: This study was conducted to compare the marginal fit of single-tooth zirconia-based copings fabricated by CAD/CAM process (Cercon; Degudent) and Copy Milling (Dentium). Materials and Methods: One in vitro prepared abutment from one mandibular molar model served as a template for replication of 40 epoxy resin (highly filled) dies, which had been taken by polyvinyl siloxane impression material. Copings were manufactured on epoxy replicas by two processes: the CAD/CAM (Cercon; Degu...

  13. New modulator for the optical signal in a fiber

    Institute of Scientific and Technical Information of China (English)

    ZHANG Tian-hao; JIA Feng; WANG Shun-li; MAN Jiang wei; NIU Kai; WANG Xu-cheng; YANG Jia

    2006-01-01

    A new modulator for the optical signal in a fiber based on multi-beam interference is designed. In the experiment,the distance of a couple of abutted fibers was modulated through a piezoelectric ceramic pipe driven by 50 Hz AC voltage, so that the amplitude of the transmitted optical signal was modulated. The modulation ratio is about 10% ,S/N ratio is about 60 dB and the bandwidth is about 200 KHz.

  14. Ataque sulfático externo en hormigones de presa con formación de thaumasita

    OpenAIRE

    Chinchón-Payá, S.; Aguado, A.; Nugterenc, H. W.; Chinchón, S.

    2015-01-01

    Concrete core samples extracted from different areas of the Mequinenza Dam (Spain) have been studied and expansive reactions affecting the structure were not found. However, expansive reactions in the concrete of certain parts located near the abutments of two galleries have been observed as a consequence of an external sulfate attack due to the sulfur compounds contained in the lignites that are present on the surrounding terrain. Secondary gypsum, ettringite, and thaumasite, as well as seve...

  15. Macroeconomics of Stagflation Under Flexible Exchange Rates

    OpenAIRE

    Kouri, Pentti J.K.

    1982-01-01

    The concerns of macroeconomic policy in the industrial countries in recent years have shifted the focus of open-economy macroeconomics to new and interesting problems. Although no synthesis, or a fully coherent theory of policy, has yet emerged from this research, the results have already led to major revisions in views abut the nature of the problems that policy has to deal with. This paper provides a selective survey and discussion of some of the results of recent research with emphasis on ...

  16. Fiber reinforced composite loop space maintainer: An alternative to the conventional band and loop

    OpenAIRE

    Ramakrishna Yeluri; Autar Krishen Munshi

    2012-01-01

    The stainless steel band and loop appliance is the most commonly used fixed space maintainer in pediatric dentistry. But there are several disadvantages with this appliance such as the need for a cast or a working model, decalcification of the abutment tooth, loosening because of breakage or dissolution of the luting agent, tendency to get embedded in the soft tissue and the possibility of metal allergy. The purpose of this article is to present a simple, laboratory design of a "Fiber Reinfor...

  17. Alternative approach to management of early loss of second primary molar: a clinical case report.

    Science.gov (United States)

    Agarwal, Ravi; Chaudhry, Kalpna; Yeluri, Ramakrishna; Singh, Chanchal; Munshi, Autar K

    2014-05-01

    Preservation of space after premature loss of the second primary molar is essential to prevent mesial drifting of the permanent first molar. Various modifications of distal shoe space maintainers, which have been documented, are all nonfunctional in nature. This paper describes an innovative design of a functional distal shoe space maintainer that is intended to overcome the disadvantages of conventional non-functional space maintainers and that does not hamper the periodontal status of the abutment tooth.

  18. Childhood allergic bronchopulmonary aspergillosis presenting as a middle lobe syndrome

    OpenAIRE

    Shah, Ashok; Gera, Kamal; Panjabi, Chandramani

    2016-01-01

    Allergic bronchopulmonary aspergillosis (ABPA) is infrequently documented in children with asthma. Although collapse is not uncommon, middle lobe syndrome (MLS) as a presentation of ABPA is rather a rarity. A 9-year-old female child with asthma presented with increase in intensity of symptoms along with a right midzone patchy consolidation on a chest radiograph. In addition, an ill-defined opacity abutting the right cardiac border with loss of cardiac silhouette was noted. A right lateral vie...

  19. Unexpected difficulty in ventilating the lungs after tracheal intubation -A case report-

    OpenAIRE

    Lee, Jong-Yeon; Lee, Su-Yeon; Shin, Inho; Chung, Kum-Hee; Chun, Duk-hee

    2011-01-01

    We experienced difficulty in ventilating the lungs of a patient after tracheal intubation. After intubation, an insufficient amount of tidal volume (VT) was delivered to the patient and the fiberoptic bronchoscopic examination identified partial abutment of the endotracheal tube (ETT) orifice against the tracheal wall. After various attempts to correctly place the ETT, a double-lumen endotracheal tube was placed to achieve a sufficient VT. It is important to notice that even an appropriately ...

  20. Frontal fixed prosthetic restoration in edentulous space modification

    OpenAIRE

    PICOS, ANDREI; PICOS, ALINA M.; STRATICA, DORIANA M.; BARBUR, ADINA; Dinu, Cristian

    2013-01-01

    This study case presents a 53 years old patient with severe aesthetic dysfunctions due to an ectopic maxillary canine associated with a frontal edentulous space. Orthodontic treatment proposition was refused by the patient. After canine extraction, metalo-ceramic fixed partial prosthesis successfully restored the aesthetic damage in the conditions of a non-gingival smile. Adapted abutment teeth preparations were made in order to provide necessary space for aesthetic alignment of artificial te...

  1. Rehabilitation of maxillary arch with attachment-retained mesh-reinforced single complete denture

    OpenAIRE

    Vamsi Krishna, C H; Rao, A Kaleshwar; Sekhar, N Chandra; Shastry, Y Mahadev

    2014-01-01

    Fabrication of conventional complete dentures was one of the most commonly advised treatment options to mange edentulous patients since many years. One of the commonly encountered challenging tasks in prosthodontics is a clinical situation in which patients have maxillary completely edentulous arches opposing mandibular natural dentition. This situation can be effectively managed by retaining some of the natural teeth as overdenture abutments. Tooth supported overdenture retained by attachmen...

  2. In-situ stress measurements and stress change monitoring to monitor overburden caving behaviour and hydraulic fracture pre-conditioning

    Institute of Scientific and Technical Information of China (English)

    Puller Jesse W.; Mills Ken W.; Jeffrey Rob G.; Walker Rick J.

    2016-01-01

    A coal mine in New South Wales is longwall mining 300 m wide panels at a depth of 160–180 m directly below a 16–20 m thick conglomerate strata. As part of a strategy to use hydraulic fracturing to manage potential windblast and periodic caving hazards associated with these conglomerate strata, the in-situ stresses in the conglomerate were measured using ANZI strain cells and the overcoring method of stress relief. Changes in stress associated with abutment loading and placement of hydraulic fractures were also measured using ANZI strain cells installed from the surface and from underground. Overcore stress mea-surements have indicated that the vertical stress is the lowest principal stress so that hydraulic fractures placed ahead of mining form horizontally and so provide effective pre-conditioning to promote caving of the conglomerate strata. Monitoring of stress changes in the overburden strata during longwall retreat was undertaken at two different locations at the mine. The monitoring indicated stress changes were evi-dent 150 m ahead of the longwall face and abutment loading reached a maximum increase of about 7.5 MPa. The stresses ahead of mining change gradually with distance to the approaching longwall and in a direction consistent with the horizontal in-situ stresses. There was no evidence in the stress change monitoring results to indicate significant cyclical forward abutment loading ahead of the face. The for-ward abutment load determined from the stress change monitoring is consistent with the weight of over-burden strata overhanging the goaf indicated by subsidence monitoring.

  3. Research and Digital Modelling of Environmental Noise and its Reduction by applying Light Structures

    OpenAIRE

    Grubliauskas, Raimondas

    2009-01-01

    General characteristic of the dissertation Problem of the work. With a rapid development of industrialisation and urbanisation, the environmental pollution has greatly increased. Upon automating the manufacturing industry and agriculture, with traffic flows in towns and residential areas increasing and household equipment becoming more modern, the number of acoustic discomfort zones is rapidly growing. People are exposed to noise not only at workplaces abut also on the streets and at ...

  4. Preoperative therapies for resectable and borderline resectable pancreatic cancer

    OpenAIRE

    Varadhachary, Gauri R.

    2011-01-01

    In the era of multidetector high quality CT imaging, it is feasible and critical to use objective criteria to define resectable pancreatic cancer. This allows accurate pretreatment staging and the development of stage-specific therapy. Tumors of borderline resectability have emerged as a distinct subset and the definition has been expanded in the last few years. Borderline resectable tumors are defined as those with tumor abutment of

  5. The Relation between Theory of Justice of John Rawls by Kant\\\\\\'s Ethics and Hegel\\\\\\'s philosophy of Right

    Directory of Open Access Journals (Sweden)

    Asgar Dirbaz

    2011-01-01

    "Theory of justice" due to the boroad variety of social sciences, audience many attracted. Readers of this theory found a wide variety of disciplines ranging from psychology and economic to ethical issues. Selected topic for which it repeatedly Rawls in his book and his theory  named the Kantian and did not name in Hegel, the Hegelian's philosophy of Right theory of the hidden angles of this article will focus on, as well as his abut influence on some views Interpreters

  6. Ceramics for Dental Applications: A Review

    Directory of Open Access Journals (Sweden)

    Julie A. Holloway

    2010-01-01

    Full Text Available Over the past forty years, the technological evolution of ceramics for dental applications has been remarkable, as new materials and processing techniques are steadily being introduced. The improvement in both strength and toughness has made it possible to expand the range of indications to long-span fixed partial prostheses, implant abutments and implants. The present review provides a state of the art of ceramics for dental applications.

  7. A minimally invasive approach for a compromised treatment plan.

    Science.gov (United States)

    Maibaum, Wayne W

    2016-01-01

    A primary goal in dentistry is the execution of appropriate treatment plans that are minimally invasive and maintainable. However, it is sometimes necessary to repair existing dental restorations or revise treatment plans to accommodate changes in a patient's condition. In the present case, a patient who was satisfied with a removable partial overdenture lost a critical abutment tooth. A creative, minimally invasive approach enabled the patient to keep his existing partial prosthesis and avoid the need for a full reconstruction or complete denture.

  8. Propagation, structural similarity and image quality

    OpenAIRE

    Pérez Rodríguez, Jorge; Mas Candela, David; Espinosa Tomás, Julián; Vázquez Ferri, Carmen; Illueca Contri, Carlos

    2012-01-01

    Natural images usually show a strong dependency between one point and its neighbourhood. This fact helps to the image interpretation and should be considered when determining the final image quality. The aim of this work is to propose an objective index which allows comparing natural images on the retina and, from them, to obtain relevant information abut the visual quality of a particular subject. The morphological data of the subject's eye are considered and the light propagation through th...

  9. Post extubation negative pressure pulmonary edema due to posterior mediastinal cyst in an infant.

    Science.gov (United States)

    Dubey, Prakash Kumar

    2014-01-01

    A 3-month-old male child underwent uneventful inguinal herniotomy under general anesthesia. After extubation, airway obstruction followed by pulmonary edema appeared for which the baby was reintubated and ventilated. The baby made a complete recovery and extubated after about 2 h. A post-operative computed tomography scan revealed a posterior mediastinal cystic mass abutting the tracheal bifurcation. Presumably, extrinsic compression by the mass on the tracheal bifurcation led to the development of negative pressure pulmonary edema.

  10. A Forgotten Technique for Replacement of Maxillary Anteriors and an associated Bony Defect: A Case Report

    OpenAIRE

    Manoaharan, P S; Ali, S.A Mohamed; Selvarangam, Suganya; Balaji, J.; Ibthigar, Mohamed

    2015-01-01

    Fixed replacement of maxillary anterior teeth with an associated bony defect has challenged the restoring dentist with problems like weight of the prosthesis thereby leading to weakening of abutment teeth, difficulty in establishing smile line and mechanical stability. This article describes the management of a patient with such defect with a forgotten prosthesis – the Andrew bridge system, which has a fixed and a removable prosthetic component with retentive clips, which anchors on to a bar ...

  11. Gap comparison between single crown and three-unit bridge zirconia substructures

    OpenAIRE

    Anunmana, Chuchai; Charoenchitt, Masnisa; Asvanund, Chanavut

    2014-01-01

    PURPOSE To compare marginal and internal gaps of zirconia substructure of single crowns with those of three-unit fixed dental prostheses. MATERIALS AND METHODS Standardized Co-Cr alloy simulated second premolar and second molar abutments were fabricated and subsequently duplicated into type-III dental stone for working casts. After that, all zirconia substructures were made using Lava™ system. Marginal and internal gaps were measured in 2 planes (mesial-distal plane and buccal-palatal plane) ...

  12. GÜNCEL DENTAL BİLGİSAYAR DESTEKLİ TASARIM/BİLGİSAYAR DESTEKLİ ÜRETİM SİSTEMLERİ

    OpenAIRE

    BEŞİR KALAYCI, Bilge; BAYINDIR, Funda

    2015-01-01

    Processing of ceramic materials with high fracture resistance and new improvement in computer technology lead to development of dental computeraided design/computer-aided manufacturing technology. The technology, which is used in both the dental laboratory and the dental clinic, can be applied to inlays, onlays, crowns, fixed partial dentures, implant abutments, and even full-mouth reconstruction. CAD/CAM systems is also being used in orthodontics. Several highly advanced chairside and labora...

  13. Fabrication of a metal-ceramic crown to fit an existing partial removable dental prosthesis using ceramic pressed to metal technique: a clinical report

    OpenAIRE

    Seo, Jae-Min; Ahn, Seung-Geun

    2014-01-01

    Fabricating a crown to retrofit an existing abutment tooth for a partial removable dental prosthesis (PRDP) is one of the most time-consuming and labor-intensive clinical procedures. In particular, when the patient is concerned with esthetic aspects of restoration, the task of fabricating becomes more daunting. Many techniques for the fabrication of all-metallic or metal-ceramic crowns have been discussed in the literature. This article was aimed to describe a simple fabrication method in whi...

  14. Replacement of missing lateral incisors with lithium disilicate glass-ceramic veneer-fixed dental prostheses: a clinical report

    OpenAIRE

    Bissasu, Sami M; Al-houri, Nabil A

    2014-01-01

    Key Clinical Message This report describes the use of lithium disilicate glass-ceramic veneer-fixed dental prostheses in replacing congenitally missing maxillary lateral incisors. This kind of prosthesis has an advantage over a lingual-retainer resin-bonded fixed dental prosthesis in its capability of changing the color and shape of the abutment teeth. The prostheses provided an acceptable esthetics and comfort for the patient.

  15. Comparison of Fracture Toughness of All-Ceramic and Metal–Ceramic Cement Retained Implant Crowns: An In Vitro Study

    OpenAIRE

    Rao, S.; Chowdhary, R.

    2014-01-01

    To evaluate the fracture toughness of cement-retained implant-supported metal–ceramic molar crown with that of all-ceramic crowns, fabricated using IPS Empress 2 and yttria-stabilized zirconia copings. An dental implant and abutment was embedded in a clear polymethyl methacrylate model. A wax pattern reproducing the anatomy and dimension of a mandibular molar was made using inlay wax. Copings were made from the manufacturers guidelines for zirconia, metal ceramic and empress crown, in total o...

  16. Rehablitation of mandibular fracture with anterior teeth loss

    OpenAIRE

    Singh, Meenakshi; Singh, Ajay; Rajpal, Jaisika; K. K. Gupta; Singh, Vibha

    2011-01-01

    We report here on rehabilitating a case with mandibular fracture and lower anterior teeth loss. Three double-staged implants were placed in the lower anterior region; in an attempt to rehabilitate the condition of five missing lower teeth, two natural teeth were prepared to act as natural abutments. Teeth implant-supported prosthesis was fabricated. Patient with a right mandibular fracture and loss of lower anterior missing teeth was successfully rehabilitated with teeth implant-supported pro...

  17. Spinous process fractures associated with Baastrup disease.

    Science.gov (United States)

    Pinto, Pedro S; Boutin, Robert D; Resnick, Donald

    2004-01-01

    Patients with Baastrup disease may experience pain owing to irritation of the periosteum or adventitial bursae between abutting spinous processes. We are not aware of any reports in the literature that describe stress fractures of the spinous fractures in patients with Baastrup disease. In this case report, we present two cases of spinous process fractures in lumbar vertebrae associated with Baastrup disease and describe their appearance with conventional radiography, bone scintigraphy, computed tomography (CT) and magnetic resonance (MR) imaging. PMID:15158230

  18. Standardizing the evaluation criteria on treatment outcomes of mandibular implant overdentures: a systematic review

    Science.gov (United States)

    Kim, Ha-Young; Shin, Sang-Wan

    2014-01-01

    PURPOSE The aim of this review was to analyze the evaluation criteria on mandibular implant overdentures through a systematic review and suggest standardized evaluation criteria. MATERIALS AND METHODS A systematic literature search was conducted by PubMed search strategy and hand-searching of relevant journals from included studies considering inclusion and exclusion criteria. Randomized clinical trials (RCT) and clinical trial studies comparing attachment systems on mandibular implant overdentures until December, 2011 were selected. Twenty nine studies were finally selected and the data about evaluation methods were collected. RESULTS Evaluation criteria could be classified into 4 groups (implant survival, peri-implant tissue evaluation, prosthetic evaluation, and patient satisfaction). Among 29 studies, 21 studies presented implant survival rate, while any studies reporting implant failure did not present cumulative implant survival rate. Seventeen studies evaluating peri-implant tissue status presented following items as evaluation criteria; marginal bone level (14), plaque Index (13), probing depth (8), bleeding index (8), attachment gingiva level (8), gingival index (6), amount of keratinized gingiva (1). Eighteen studies evaluating prosthetic maintenance and complication also presented following items as evaluation criteria; loose matrix (17), female detachment (15), denture fracture (15), denture relining (14), abutment fracture (14), abutment screw loosening (11), and occlusal adjustment (9). Atypical questionnaire (9), Visual analog scales (VAS) (4), and Oral Health Impact Profile (OHIP) (1) were used as the format of criteria to evaluate patients satisfaction in 14 studies. CONCLUSION For evaluation of implant overdenture, it is necessary to include cumulative survival rate for implant evaluation. It is suggested that peri-implant tissue evaluation criteria include marginal bone level, plaque index, bleeding index, probing depth, and attached gingiva

  19. NEUTRONIC REACTORS

    Science.gov (United States)

    Anderson, J.B.

    1960-01-01

    A reactor is described which comprises a tank, a plurality of coaxial steel sleeves in the tank, a mass of water in the tank, and wire grids in abutting relationship within a plurality of elongated parallel channels within the steel sleeves, the wire being provided with a plurality of bends in the same plane forming adjacent parallel sections between bends, and the sections of adjacent grids being normally disposed relative to each other.

  20. Optimization of friction stir welding parameters for improved corrosion resistance of AA2219 aluminum alloy joints

    OpenAIRE

    G. Rambabu; D. Balaji Naik; C.H. Venkata Rao; K. Srinivasa Rao; G. Madhusudan Reddy

    2015-01-01

    The aluminium alloy AA2219 (Al–Cu–Mg alloy) is widely used in the fabrication of lightweight structures with high strength-to-weight ratio and good corrosion resistance. Welding is main fabrication method of AA2219 alloy for manufacturing various engineering components. Friction stir welding (FSW) is a recently developed solid state welding process to overcome the problems encountered in fusion welding. This process uses a non-consumable tool to generate frictional heat on the abutting surfac...

  1. キンゾク セッチャク ギホウ ヲ オウヨウ シタ ホテツ チリョウ ニ ツイテ

    OpenAIRE

    田中, 卓男; タナカ, タクオ; Tanaka, Takuo

    1997-01-01

    A new prosthetic restoration attracting many dentists is the adhesion-fixed partial denture. The adhesion-fixed partial denture requires minimal teeth preparation and is easier to construct and manipulate than are conventional fixed partial dentures. To attach an adhesion-fixed partial denture to abutment teeth, resin material must be bonded to the teeth and metal framework. The tooth surfaces require etching with acid and the retainers are surface treated to enhance the adhesive bonding with...

  2. The Overall Survival, Complication-Free Survival, and Related Complications of Combined Tooth-Implant Fixed Partial Dentures:A Literature Review

    OpenAIRE

    Peter Borg; James Puryer; Lisa McNally; Dominic O’Sullivan

    2016-01-01

    This paper reviews the literature regarding possible complications, complication-free survival, and overall survival of fixed dental prostheses that use both implants and natural teeth as abutments. The paper also provides clinical guidelines for treatment based on this literature review. An electronic search utilizing the MEDLINE, BIOSIS Citation Index, and Web of Science™ Core Collection databases was undertaken, and a review of the 25 selected texts studying 22 different patient cohorts wa...

  3. 金属接着技法を応用した補綴治療について : 接着ブリッジの基礎と臨床

    OpenAIRE

    田中, 卓男; タナカ, タクオ; Tanaka, Takuo

    1997-01-01

    A new prosthetic restoration attracting many dentists is the adhesion-fixed partial denture. The adhesion-fixed partial denture requires minimal teeth preparation and is easier to construct and manipulate than are conventional fixed partial dentures. To attach an adhesion-fixed partial denture to abutment teeth, resin material must be bonded to the teeth and metal framework. The tooth surfaces require etching with acid and the retainers are surface treated to enhance the adhesive bonding with...

  4. セッチャク ブリッジ ニ ミル セッチャク ホテツ リンショウ ノ レキシ

    OpenAIRE

    田中, 卓男; タナカ, タクオ; Tanaka, Takuo

    2013-01-01

    A new prosthetic restoration attracting many dentists is the adhesion-fixed partial denture. The adhesion-fixed partial denture requires minimal teeth preparation and is easier to construct and manipulate than are conventional fixed partial dentures. To attach an adhesion-fixed partial denture to abutment teeth, resin material must be bonded to the teeth and metal framework. The tooth surfaces require etching with acid and the retainers are surface treated to enhance the adhesive bonding with...

  5. 接着ブリッジに見る接着補綴臨床の歴史

    OpenAIRE

    田中, 卓男; タナカ, タクオ; Tanaka, Takuo

    2013-01-01

    A new prosthetic restoration attracting many dentists is the adhesion-fixed partial denture. The adhesion-fixed partial denture requires minimal teeth preparation and is easier to construct and manipulate than are conventional fixed partial dentures. To attach an adhesion-fixed partial denture to abutment teeth, resin material must be bonded to the teeth and metal framework. The tooth surfaces require etching with acid and the retainers are surface treated to enhance the adhesive bonding with...

  6. Prostatic atrophy: its spatial proximity to carcinoma and intraepithelial neoplasia based on annotation of digital slides.

    Science.gov (United States)

    Iczkowski, Kenneth A; Torkko, Kathleen C; Wilson, R Storey; Lucia, M Scott; Bostwick, David G

    2014-01-01

    Whether atrophy is a precursor to high-grade prostatic intraepithelial neoplasia (HGPIN) and cancer is controversial. A virtual slide set comprising 48 prostatectomy cases was used to investigate associations among the amounts and spacing of these entities. Foci of atrophy without inflammation (A), atrophy with inflammation (AI), cancer (by patterns), and HGPIN were digitally annotated. Atrophy's proximity to cancer and HGPIN was assessed with two measurements: abutment (touching) or nearness (≤2 μm without touching). Area sums per specimen were computed for A, AI, cancer, and HGPIN. Abutment rates of AI and A foci to cancer were 23% versus 21% (p = NS); for nearness, 29% of AI foci were near to cancer versus 12% of A (P = .0001). Abutment or nearness of A and AI to HGPIN were in the 1.4% to 2.4% range. When A, AI, or HGPIN abutted cancer, it was disproportionately to Gleason grade 3 cancer foci even after adjusting for the lesser frequency of higher-grade cancer foci. Area sums of A, AI, or (A + AI) per specimen showed no correlations with those of HGPIN, and mostly negative ones with area sum and with tumor volume of cancer. In conclusion, atrophy with inflammation showed some preferential spatial association to cancer, although area sums of atrophy with or without inflammation correlated negatively with those of cancer. These divergent spatial associations suggest that atrophy and inflammation in biopsy specimens may have clinical relevance. The frequency of inflammatory atrophy (AI) merging with HGPIN was far less than reported previously, weakening the theory that AI gives rise to HGPIN. PMID:24157066

  7. Finite element analysis for dental implants subjected to thermal loads

    Directory of Open Access Journals (Sweden)

    Mohamad Reza Khalili

    2013-10-01

    Full Text Available   Background and Aims: Dental implants have been studied for replacement of missing teeth for many years. Productivity of implants is extremely related to the stability and resistance under applied loads and the minimum stress in jaw bone. The purpose of this study was to study numerically the 3D model of implant under thermal loads.   Materials and Methods: Bone and the ITI implant were modeled in “Solidworks” software. To obtain the exact model, the bone was assumed as a linear orthotropic material. The implant system, including implant, abutment, framework and crown were modeled and located in the bone. After importing the model in Abaqus software, the material properties and boundary conditions and loads were applied and after meshing, the model was analyzed. In this analysis, the loads were applied in two steps. In the first step, the mechanical load was applied as tightening torque to the abutment and the abutment was tightened in the implant with 35 N.cm torque. In the second step, the thermal load originated from drinking cold and hot water was applied as thermal flux on the ceramic crown surface in this model.   Results: Thermal analysis results showed that the thermal gradient in the bone was about 5.5 and 4.9 degrees of centigrade in the case of drinking cold and hot water respectively , although the maximum gradient of the whole system was reduced to 14 degrees, which occurred, in the crown by drinking cold water.   Conclusion Thermal stresses were so small and it was because of the low thermal gradient. Maximum stresses occurred in the abutment were due to the tension preloads which were originated from the tightening torque.

  8. Immediate/early loading of zygomatic implants: Clinical experiences after 2 to 5 years of follow-up

    OpenAIRE

    Aparicio, Carlos; Ouazzani, Wafaa; Aparicio, Arnau; Fortes, Vanessa; Muela, Rosa; Pascual, Andrés; Codesal, María; Barluenga, Natalia; Franch, Monica

    2010-01-01

    The aim of the present study is to report on the clinical outcomes of immediate/early loading of zygomatic implants for prosthetic rehabilitation of edentulous and severely resorbed maxillary cases. A total of 47 zygomatic and 129 regular implants were placed in 25 consecutive patients with total (N = 23) or partial (N = 2) edentulism in the maxilla. The patients had less than 4 mm of available bone height and width distal to the canine pillars. Straight and angulated abutments and impression...

  9. Workshop on adaptive grid methods for fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Wiley, J.C. [Univ. of Texas, Austin, TX (United States)

    1995-07-01

    The author describes a general `hp` finite element method with adaptive grids. The code was based on the work of Oden, et al. The term `hp` refers to the method of spatial refinement (h), in conjunction with the order of polynomials used as a part of the finite element discretization (p). This finite element code seems to handle well the different mesh grid sizes occuring between abuted grids with different resolutions.

  10. Adaptive numerical methods for partial differential equations

    Energy Technology Data Exchange (ETDEWEB)

    Cololla, P. [Univ. of California, Berkeley, CA (United States)

    1995-07-01

    This review describes a structured approach to adaptivity. The Automated Mesh Refinement (ARM) algorithms developed by M Berger are described, touching on hyperbolic and parabolic applications. Adaptivity is achieved by overlaying finer grids only in areas flagged by a generalized error criterion. The author discusses some of the issues involved in abutting disparate-resolution grids, and demonstrates that suitable algorithms exist for dissipative as well as hyperbolic systems.

  11. Evaluation of Accuracy of Direct Transfer Snapon Impression Coping Closed Tray Impression Technique and Direct Transfer Open Tray Impression Technique: An In Vitro Study

    OpenAIRE

    T Balamurugan; Manimaran, P.

    2012-01-01

    Accuracy of the implant impression technique is one of the key factor determining the strain free fit of the prosthesis fabricated which influences the treatment success. Two implant impression techniques namely the closed tray technique with transfer coping and open tray technique were evaluated for accuracy with stone casts obtained from them. Casts were evaluated using a custom constructed bar on strain gage (SYSCOM) and abutment coordinates using Coordinate Measuring Machine (TESA micro-H...

  12. Vliv vybraných faktorů na distribuci a populační dynamiku druhu Coenagrion ornatum (Odonata).

    OpenAIRE

    Papík, Vojtěch

    2011-01-01

    The Ornate Bluet (Coenagrion ornatum) is one of three species from the order Odonata in the Czech Republic registered on the Natura 2000 list. This bachelor thesis deal with description of ecology requirements and practical protection of this species. The aim of this thesis was to create a comprehensive set of information abut environmental claims Coenagrion ornatum. The thesis was based on a comparison with taxonomically related species Coenagrion mercuriale. For this purpose was used a...

  13. Farklı tipteki dental implantların mekanik yönden başarı ve başarısızlığı: iki yıllık takip çalışması

    OpenAIRE

    Akin, Hakan; Coskun, M Emre; Sari, Fatih; Tugut, Faik; Ozdemir, Hakan; Ozdemir, Ali Kemal

    2011-01-01

    Purpose: In this study different implant systems were evaluated mechanically. Material and Method: 101implants including MIS, ITI, Biolok and Biotec implants in 32 patients which were good general health status. The implants were followed up over a period of 2 years and mechanical failure of the implants was evaluated. Results: One implant fracture, 2 screw fracture and 18 screw and abutment loosening were observed. The two-year short follow up success rates were %87,23 for MIS implants, %86,...

  14. Prosthodontic Perspective to All-On-4® Concept for Dental Implants

    OpenAIRE

    Taruna, M; B Chittaranjan; Sudheer, N; Tella, Suchita; Abusaad, Md.

    2014-01-01

    The clinical success and longevity of endosteal dental implants as load bearing abutments are controlled largely by the mechanical setting in which they function. The treatment plan is responsible for the design, number and position of the implants. In biomechanically compromised environment such as poor quality bone, strain to the crestal bone can be reduced by increasing the anterioposterior spread of implants, placement of longer implants and maximizing the number of implants. The All-on-4...

  15. Repairing and strengthening a fractured Hader bar.

    Science.gov (United States)

    Herrero, D B

    1997-01-01

    Stresses from occlusion and metal fatigue over time can cause fracture of overdenture retention bars. Often failure of the bar necessitates the removal and remake of the bar. This may damage the abutment, especially if there are dowel posts involved. This article describes a method for reinforcing the existing bar without having to remove the bar or significantly alter the overdenture. The fractured bar can be prepared in the mouth to receive a reinforcing superstructure that will be cemented.

  16. Prevention of Cutaneous Tissue Contracture During Removal of Craniofacial Implant Superstructures for CT and MRI Studies

    Directory of Open Access Journals (Sweden)

    Maureen Sullivan

    2010-04-01

    Full Text Available Objectives: Head and neck cancer patients who have lost facial parts following surgical intervention frequently require craniofacial implant retained facial prostheses for restoration. Many craniofacial implant patients require computed tomography and magnetic resonance imaging scans as part of their long-term follow-up care. Consequently removal of implant superstructures and peri-abutment tissue management is required for those studies. The purpose of the present paper was to describe a method for eliminating cranial imaging artifacts in patients with craniofacial implants.Material and Methods: Three patients wearing extraoral implant retained facial prostheses needing either computed tomography or magnetic resonance imaging studies were discussed. Peri-implant soft tissues contracture after removal of percutaneous craniofacial implant abutments during computed tomography and magnetic resonance imaging studies was prevented using a method proposed by authors. The procedure involves temporary removal of the supra-implant components prior to imaging and filling of the tissue openings with polyvinyl siloxane dental impression material.Results: Immediately after filling of the tissue openings with polyvinyl siloxane dental impression material patients were sent for the imaging studies, and were asked to return for removal of the silicone plugs and reconnection of all superstructure hardware after imaging procedures were complete. The silicone plugs were easily removed with a dental explorer. The percutaneous abutments were immediately replaced and screwed into the implants which were at the bone level.Conclusions: Presented herein method eliminates the source of artifacts and prevents contracture of percutaneous tissues upon removal of the implant abutments during imaging.

  17. Retrofit of existing railway bridges of short to medium spans for high-speed traffic using viscoelastic dampers

    OpenAIRE

    MOLINER CABEDO, EMMANUELA; Museros Romero, Pedro; MARTÍNEZ RODRIGO, MARÍA DE LOS DOLORES

    2012-01-01

    This paper presents a study on the energy-absorbing capacities of viscoelastic dampers (VEDs) for reducing the resonant vibrations of simply supported high-speed railway bridges of short to medium span. The proposed solution is based on retrofitting the bridge with a set of discrete VEDs connected to the slab and to an auxiliary structure, placed underneath the bridge deck and resting on the abutments. In this investigation attention is focused on mitigating flexural vibrations; therefore, bo...

  18. Untersuchung zum Einfluss von Präparationsart, Zementspalteinstellung und Art des Befestigungszements auf die Passgenauigkeit CAD-CAM gefertigter vollkeramischer Kronengerüste

    OpenAIRE

    Hmaidouch, Rim

    2011-01-01

    Apart from fracture resistance and aesthetics, marginal and internal accuracy of fit is valued as one of the most important criteria for long-term success of all-ceramic crowns and bridges, because inadequate fit is potentially damaging for both abutment and periodontal tissues. This in-vitro study evaluated the influence of two different tooth preparation forms, two luting space settings (LSS) and four cement types on the marginal and internal adaptation of all-ceramic crown copings produced...

  19. Digitally enhanced dentistry: the power of digital design.

    Science.gov (United States)

    Guichet, David

    2015-03-01

    New digital processes are used in treatment planning for implants and design and manufacture of surgical guides, abutments, provisionals and final restorations. The multiple technologies of 3-D cone beam CT imaging, intraoral scanning, laboratory scanning, 3-D digital restorative design and CAD/CAM production have contributed to this trend. Simultaneously, restorative materials have been introduced that have improved strength and esthetic qualities. Integration of these capabilities creates opportunities for enhanced restorative performance, decreased costs and improved practice efficiency. PMID:25864301

  20. Stability of dental implants in grafted bone in the anterior maxilla: longitudinal study.

    LENUS (Irish Health Repository)

    Al-Khaldi, Nasser

    2010-06-06

    We aimed to assess the stability over time of dental implants placed in grafted bone in the maxilla using resonance frequency analysis, and to compare the stability of implants placed in grafted and non-grafted bone. Data were collected from 23 patients (15 test and 8 controls) in whom 64 implants (Brånemark system, Nobel Biocare, Göteborg, Sweden) were placed in accordance with the two-stage surgical protocol. In the test group 36 fixtures were placed in grafted bone, and in the control group 28 fixtures were placed in non-grafted bone. Resonance frequency analysis was used to assess the test sites at implant placement and abutment connection. The mean (SD) implant stability quotient (ISQ) for test sites at the time of implant placement was 61.91 (6.68), indicating excellent primary stability, and was 63.53 (5.76) at abutment connection. ISQ values at abutment connection were similar for test and control sites. Implants placed in grafted bone compared favourably with those in non-grafted bone, and showed excellent stability.

  1. Effect of Luting Agents on Retention of Dental Implant-Supported Prostheses.

    Science.gov (United States)

    Pan, Yu-Hwa; Lin, Tai-Min; Liu, Perng-Ru; Ramp, Lance C

    2015-10-01

    To evaluate the retentive strength of 7 different luting agents in cement-retained implant abutment/analog assemblies. Fifty-six externally hexed dental implant abutment/analog assemblies and cast superstructures were divided randomly into 7 groups for cementation with each of the 7 luting agents. Five definitive cements tested were zinc phosphate cement, All-Bond 2, Maxcem, RelyX Luting cement, HY-Bond, and two provisional cements, ImProv and Premier. Cast superstructures were cemented onto the implant abutments and exposed to 1000 thermal cycles (0°C-55°C) and 100 000 cycles on a chewing simulator (75 N load). A universal testing machine was used to measure cement failure load of the assembled specimens. Cement failure load was evaluated with 1-way ANOVA and Duncan's multiple range analysis. Significant differences in cement failure loads were measured (P zinc phosphate cement were analogous, and higher than HY-Bond. Improv and Premier constituted a pair, which demonstrated the lowest retentive values. Within the limitations of this in vitro study, Maxcem and All-Bond 2 are good candidates for cement-retained implant prostheses while concerning retention. PMID:24666355

  2. Adaptive methylation regulation of p53 pathway in sympatric speciation of blind mole rats, Spalax.

    Science.gov (United States)

    Zhao, Yang; Tang, Jia-Wei; Yang, Zhi; Cao, Yi-Bin; Ren, Ji-Long; Ben-Abu, Yuval; Li, Kexin; Chen, Xue-Qun; Du, Ji-Zeng; Nevo, Eviatar

    2016-02-23

    Epigenetic modifications play significant roles in adaptive evolution. The tumor suppressor p53, well known for controlling cell fate and maintaining genomic stability, is much less known as a master gene in environmental adaptation involving methylation modifications. The blind subterranean mole rat Spalax eherenbergi superspecies in Israel consists of four species that speciated peripatrically. Remarkably, the northern Galilee species Spalax galili (2n = 52) underwent adaptive ecological sympatric speciation, caused by the sharply divergent chalk and basalt ecologies. This was demonstrated by mitochondrial and nuclear genomic evidence. Here we show that the expression patterns of the p53 regulatory pathway diversified between the abutting sympatric populations of S. galili in sharply divergent chalk-basalt ecologies. We identified higher methylation on several sites of the p53 promoter in the population living in chalk soil (chalk population). Site mutagenesis showed that methylation on these sites linked to the transcriptional repression of p53 involving Cut-Like Homeobox 1 (Cux1), paired box 4 (Pax 4), Pax 6, and activator protein 1 (AP-1). Diverse expression levels of p53 between the incipiently sympatrically speciating chalk-basalt abutting populations of S. galili selectively affected cell-cycle arrest but not apoptosis. We hypothesize that methylation modification of p53 has adaptively shifted in supervising its target genes during sympatric speciation of S. galili to cope with the contrasting environmental stresses of the abutting divergent chalk-basalt ecologies.

  3. Posterior implants for distal extension removable prostheses: a retrospective study.

    Science.gov (United States)

    Mitrani, Ricardo; Brudvik, James S; Phillips, Keith M

    2003-08-01

    Common complaints associated with the Kennedy Class I (bilateral free end) and Class II (unilateral free end) removable partial denture situations are lack of stability, minimal retention, and unesthetic retentive clasping. Some of the same complaints have been reported for implant overdentures with only anterior implants. Starting in 1995, 10 of these patients were treated at the University of Washington with posterior osseointegrated implants to provide stability and/or retention of the removable prostheses, eliminating the need for clasps when possible. This article describes implant alternatives and prosthesis designs and presents a follow-up clinical evaluation of at least 1 year consisting of patient satisfaction, radiographic examination, and soft tissue health. Two groups were evaluated. Group 1 included patients whose implants were used as vertical stops for mandibular distal extension prostheses. Care was taken to ensure that the implants were not loaded laterally by creating a single-point contact at the center of a modified healing abutment. In these cases, sufficient retention was available from the anterior teeth and/or implant abutments. Group 2 included patients whose implants required retention because of lack of adequate tooth abutments. In those cases, a resilient type of attachment was used, which allowed for a small divergence from the path of insertion. Results indicated consistent increased satisfaction in all patients, minimal component wear, no radiographic evidence of excessive bone loss, and stable peri-implant soft tissues. PMID:12956479

  4. The Prosthetic Influence and Biomechanics on Peri-Implant Strain: a Systematic Literature Review of Finite Element Studies

    Directory of Open Access Journals (Sweden)

    Julius Maminskas

    2016-09-01

    Full Text Available Objectives: To systematically review risks of mechanical impact on peri-implant strain and prosthetic influence on stability across finite element studies. Material and Methods: An online literature search was performed on MEDLINE and EMBASE databases published between 2011 and 2016. Following keywords tiered screening and selection of the title, abstract and full-text were performed. Studies of finite element analysis (FEA were considered for inclusion that were written in English and revealed stress concentrations or strain at peri-implant bone level. Results: There were included 20 FEA studies in total. Data were organized according to the following topics: bone layers, type of bone, osseointegration level, bone level, design of implant, diameter and length of implant, implant-abutment connection, type of supra-construction, loading axis, measurement units. The stress or strain at implant-bone contact was measured over all studies and numerical values estimated. Risks of overloading were accented as non-axial loading, misfits, cantilevers and the stability of peri-implant bone was related with the usage of platform switch connection of abutment. Conclusions: Peri-implant area could be affected by non-axial loading, cantilever prosthetic elements, crown/implant ratio, type of implant-abutment connection, misfits, properties of restoration materials and antagonistic tooth. The heterogeneity of finite element analysis studies limits systematization of data. Results of these studies are comparable with other findings of in vitro, in vivo, prospective and retrospective studies.

  5. Laser welding and syncristallization techniques comparison: “Ex vivo” study

    Science.gov (United States)

    Meleti, Marco; Vescovi, Paolo; Merigo, Elisabetta; Rocca, Jean-Paul

    2013-01-01

    Background and aims: Stabilization of implant abutments through electric impulses at high voltage for a very short time (electrowelding) was developed in the Eighties. In 2009, the same procedure was performed through the use of laser (laser welding) The aim of this study is to compare electrowelding and laser welding for intra-oral implant abutments stabilization on “ex vivo models” (pig jaws). Materials and methods: Six bars were welded with two different devices (Nd:YAG laser and Electrowelder) to eighteen titanium implant abutment inserted in three pig jaws. During the welding process, thermal increase was recorded, through the use of k-thermocouples, in the bone close to the implants. The strength of the welded joints was evaluated by a traction test after the removal of the implants. For temperature measurements a descriptive analysis and for traction test “values unpaired t test with Welch's correction” were performed: the significance level was set at PLaser welding gives a lower thermal increase than Electrowelding at the bone close to implants (Mean: 1.97 and 5.27); the strength of laser welded joints was higher than that of Electrowelding even if nor statistically significant. (Mean: 184.75 and 168.29) Conclusion: Electrowelding seems to have no advantages, in term of thermal elevation and strength, while laser welding may be employed to connect titanium implants for immediate load without risks of thermal damage at surrounding tissues. PMID:24511205

  6. Effect of various putty-wash impression techniques on marginal fit of cast crowns.

    Science.gov (United States)

    Nissan, Joseph; Rosner, Ofir; Bukhari, Mohammed Amin; Ghelfan, Oded; Pilo, Raphael

    2013-01-01

    Marginal fit is an important clinical factor that affects restoration longevity. The accuracy of three polyvinyl siloxane putty-wash impression techniques was compared by marginal fit assessment using the nondestructive method. A stainless steel master cast containing three abutments with three metal crowns matching the three preparations was used to make 45 impressions: group A = single-step technique (putty and wash impression materials used simultaneously), group B = two-step technique with a 2-mm relief (putty as a preliminary impression to create a 2-mm wash space followed by the wash stage), and group C = two-step technique with a polyethylene spacer (plastic spacer used with the putty impression followed by the wash stage). Accuracy was assessed using a toolmaker microscope to measure and compare the marginal gaps between each crown and finish line on the duplicated stone casts. Each abutment was further measured at the mesial, buccal, and distal aspects. One-way analysis of variance was used for statistical analysis. P values and Scheffe post hoc contrasts were calculated. Significance was determined at .05. One-way analysis of variance showed significant differences among the three impression techniques in all three abutments and at all three locations (P < .001). Group B yielded dies with minimal gaps compared to groups A and C. The two-step impression technique with 2-mm relief was the most accurate regarding the crucial clinical factor of marginal fit.

  7. 3-D numerical modelling of stresses around a longwall panel with top coal caving

    Energy Technology Data Exchange (ETDEWEB)

    Yasitli, N.E.; Unver, B. [University of Hacettepe, Ankara (Turkey). Dept. of Mining Engineering

    2005-06-01

    There is a considerable amount of lignite reserve in the form of thick seams in Turkey. It is rather complicated to predict the characteristics of strata response to mining operation in thick seams. However, a comprehensive evaluation of ground behaviour is a prerequisite for maintaining an efficient production, especially when top coal winning by means of caving behind the face is applied. A comprehensive modelling of deformations and induced stresses is vital for the selection of optimum production strategy. In this study, numerical modelling and analysis of a longwall panel at Omerler underground coalmine have been carried out by using the software called FLAC(3D) developed based on the finite difference technique. Firstly, a 3-D numerical model of the M3 panel has been prepared. Secondly, induced stresses formed around the longwall face have been determined as a function of face advance where the face was located at the bottom of thick coal-seam. Results obtained from modelling studies have revealed that the front abutment vertical stress was maximum at 7 metres in front of the face and magnitude of front abutment stress was found to increase up to a distance of 200 metres away from the face start line. As the face was further advanced after 200 m from the face start line, there was not any significant change in the characteristics of front abutment stresses. Results of numerical analysis of the panel were in good agreement with in situ observations.

  8. Catastrophic failure of a monolithic zirconia prosthesis.

    Science.gov (United States)

    Chang, Jae-Seung; Ji, Woon; Choi, Chang-Hoon; Kim, Sunjai

    2015-02-01

    Recently, monolithic zirconia restorations have received attention as an alternative to zirconia veneered with feldspathic porcelain to eliminate chipping failures of veneer ceramics. In this clinical report, a patient with mandibular edentulism received 4 dental implants in the interforaminal area, and a screw-retained monolithic zirconia prosthesis was fabricated. The patient also received a maxillary complete removable dental prosthesis over 4 anterior roots. At the 18-month follow-up, all of the zirconia cylinders were seen to be fractured, and the contacting abutment surfaces had lost structural integrity. The damaged abutments were replaced with new abutments, and a new prosthesis was delivered with a computer-assisted design and computer-assisted manufacturing fabricated titanium framework with denture teeth and denture base resins. At the 6-month recall, the patient did not have any problems. Dental zirconia has excellent physical properties; however, care should be taken to prevent excessive stresses on the zirconia cylinders when a screw-retained zirconia restoration is planned as a definitive prosthesis.

  9. Transfer Impression in Prosthodontics Implants for the Range of the Practitioner

    Directory of Open Access Journals (Sweden)

    Érica Alves GOMES

    2006-09-01

    Full Text Available Introduction: The success of an implant supported restoration is directly associated with accuracy and passive fit of fixture and abutments components, stability of implant/abutment interface, as well as adequate distribution of mastigatory loads to the set. The procedure of the implant or abutment transfer impression is one of the most important phase to obtain passivity fit for prosthesis/implant set. Objective: The aim of this study was to present a literature review to allow the practitioner necessary subsidies for right selection and indication of the most adequate impression material, type of the tray that proportionate more accuracy impressions, more favorable impression copping, as well as more appropriated types and impression techniques to each restoration, based on indexator PUBMED with impression, techniques, implants and fit terms and 26 being selected originals and actual manuscripts. Conclusion: From the literature review was concluded that addition silicone and polyether with custom trays and square impression copings showed more accuracy impression; conical impression copings should be indicate in small inter-arch space; impression copings should be splinted during the multiple restorations impression and customized to single restoration of esthetics site.

  10. Examples of model-free implant restorations using Cerec inLab 4.0 software.

    Science.gov (United States)

    Reich, S; Schley, J; Kern, T; Fiedler, K; Wolfart, S

    2012-01-01

    This case report demonstrates two ways to fabricate model-free implant restorations with the Cerec inLab 4.0 software. Because the patient, a woman with a history of periodontal disease, did not wish to have a removable partial denture, implant therapy was planned for the restoration of her edentulous areas 14/15 and 24/25. In addition, the restoration was to provide functional relief of the natural maxillary anterior teeth. The two implants for the first quadrant were planned as single-tooth restorations. Each was designed as a full contour implant supra-structure using the Cerec Biogeneric abutment design technique. After completing the design phase, each restoration proposal was split into two parts: a zirconia abutment and a lithium disilicate crown. For the restoration of the second quadrant, custom 20-degree-angled abutments were individualized and acquired with the Cerec camera. A block crown was then designed, milled in burn-out acrylic resin, and fabricated from a lithium disilicate glass-ceramic ingot according to the press ceramic technique. Additionally methods of provisional restorations are discussed.

  11. Dynamic responses of bridge-approach embankment transition section of high-speed rail

    Institute of Scientific and Technical Information of China (English)

    杨长卫; 孙海玲; 张建经; 朱传彬; 颜利平

    2013-01-01

    Based on the vehicle track coupling dynamics theory, a new spatial dynamic numerical model of vehicle track subgrade coupling system was established considering the interaction among different structural layers in the subgrade system. The dynamic responses of the coupled system were analyzed when the speed of train was 350 km/h and the transition was filled with graded broken stones mixed with 5% cement. The results indicate that the setting form of bridge-approach embankment section has little effect on the dynamic responses, thus designers can choose it on account of the practical circumstances. Because the location about 5 m from the bridge abutment has the greatest deformation, the stiffness within 0 5 m zone behind the abutment should be specially designed. The results of the study from vehicle track dynamics show that the maximum allowable track deflection angle should be 0.09% and the coefficient of subgrade reaction(K30) is greater than 190 MPa within the 0 5 m zone behind the abutment and greater than 150 MPa in other zones.

  12. A two-short-implant-supported molar restoration in atrophic posterior maxilla: A finite element analysis

    Science.gov (United States)

    2016-01-01

    PURPOSE The aim of this study was to investigate the stress distribution of 2-short implants (2SIs) installed in a severely atrophic maxillary molar site. MATERIALS AND METHODS Three different diameters of internal connection implants were modeled: narrow platform (NP), regular platform (RP), and wide platform (WP). The maxillary first molars were restored with one implant or two short implants. Three 2SI models (NP-oblique, NP-vertical, and NP-horizontal) and four single implant models (RP and WP in a centered or cantilevered position) were used. Axial and oblique loadings were applied on the occlusal surface of the crown. The von Mises stress values were measured at the bone-implant, peri-implant bone, and implant/abutment complex. RESULTS The highest stress distribution at the bone-implant interface and the peri-implant bone was noticed in the RP group, and the lowest stress distribution was observed in the 2SI groups. Cantilevered position showed unfavorable stress distribution with axial loading. 2SI types did not affect the stress distribution in oblique loading. The number and installation positions of the implant, rather than the bone level, influenced the stress distribution of 2SIs. The implant/abutment complex of WP presented the highest stress concentration while that of 2SIs showed the lowest stress concentration. CONCLUSION 2SIs may be useful for achieving stable stress distribution on the surrounding bone and implant-abutment complex in the atrophic posterior maxilla.

  13. Shape-memory alloy overload protection device for osseointegrated transfemoral implant prosthetic limb attachment system

    Science.gov (United States)

    Xu, Wei; Shao, Fei; Hughes, Steven

    2002-11-01

    The osseointegrated trans-femoral implant system provides a direct anchoring technique to attach prosthetic limb. This technique was first introduced PI Brenmark in Sweden. The UK had the first clinical trial in 1997 and currently has 6 active limb wearers. The success of this procedure has the potential for improved gait function and mobility, increased employability and significant long-term improvements in the quality of life for above knee amputees. However, the significant load involved in the trans-femoral implant system has caused permanent deformation and/or fractures of the implant abutment in several occasions. To protect the implant system, the implant abutment in particularly, an overloading protection device was introduced. The device uses mechanical mechanism to release torsion overload on the abutment. However, the bending overload protection remains unsolved. To solve the problem, a new overload protection device was developed. This device uses SMA component for bending overload protection. In this paper, the results of non-linear finite element modelling of the SMA and steel (AISI 1040) components were presented. Experiments were also carried out using steel components to assess the design which is based on the non-linear property of the materials.

  14. Clinical application of single-tooth replacement with ankylos implant system

    International Nuclear Information System (INIS)

    Objective: To evaluate the clinical effects of Ankylos implant system to restore the loss of single-tooth. Methods: 90 cases with loss of single-tooth were selected and treated with routinely two-stage surgery. When the patients presented with deficient alveolar ridge, guided bone regeneration (GBR), osteotome sinus floor elevation, lateral antrostomy surgery with simultaneous placement of implant were applied. They were restored with platinum ceramic crown. All the implants were followed up, and the records were kept about stability of the implant and abutment, the status of surrounding soft tissue, sealability of implant abutment junction and the marginal bone lossing through X-ray checking,and satisfaction of the patients to mastication and aspect of the restorations. The follow-up time was 1-2.5 years. Results: Among the cases,one case had peri-implant inflammation, and one case had porcelain dropped. No loosening occurred in the other implants and abuments. Implant abutment junction was sealed well. The marginal bone loss 1 year after final restoration was less than 1 mm. Soft tissue surrounding implants was healthy. The satisfaction rate was 98.9% (89/90). According to standard of implant success, 88 cases were successful, the 2.5-year cumulative success rate was 97.8%, 2 cases failed, and the failure rate was 2.2 %. Conclusion: A satisfactory treatment effects could be gotten by using Ankylos implant system to restore the loss of single-tooth. (authors)

  15. Electrochemical cell with electrode hold-down

    Energy Technology Data Exchange (ETDEWEB)

    Boudrot, R.J.; Shambaugh, J.S.; Zeltzer, H.

    1981-06-30

    A primary electrochemical cell including a hold-down unit for securing and preventing movement of a physically large battery stack of the cell is disclosed. The battery stack is disposed within a rectangular metal housing of the cell, together with an electrolytic solution, and comprises a large number of rectangular anodes and cathode structures arranged in the battery stack in alternation. The hold-down unit is disposed in the cell in abutment with the top of the battery stack and an inner surface of a cover assembly secured to the housing. The hold-down unit includes a pair of opposed end sections in abutment with the interior surfaces of one pair of walls of the housing and lying orthogonally to the planes of the components of the battery stack, and a pair of opposed connecting sections in abutment with the interior surfaces of the other pair of walls of the housing and interconnecting the pair of end sections. The connecting sections are spaced from the battery stack and define, together with the end sections, top and side openings. These openings, together with large openings in the end sections, minimize the displacement of electrolytic solution in the region of the cell above the battery stack. The connecting sections further include insulated, resilient, angularly-oriented tabs capable of deflection by contact with the top cover assembly for compensating for variations in tolerances associated with the manufacture and assembly of the components of the cell.

  16. Diseño de estribos abiertos en puentes de carretera obtenidos mediante optimización híbrida de escalada estocástica

    Directory of Open Access Journals (Sweden)

    Luz, A.

    2015-12-01

    Full Text Available This article deals with the minimum cost automatic design of reinforced concrete open abutments of road bridges, using a two-hybrid stochastic hill climbing algorithms with a neighborhood move based on the mutation operator from the genetic algorithms. These algorithms are based on the simulated annealing (SAMO as well as on the threshold accepting procedure (TAMO. Both algorithms were applied to an open abutment which has 40 discrete variables. Savings have been found 18 % compared to an abutment of 9 m in height really executed. SAMO improves by only 0.5 % a similar run by TAMO. Additionally, the paper presents a parametric study of commonly used abutments from 6 to 15 m in height for different bearing conditions. Further, the results presented are of much value for the preliminary design of open abutments of road bridges. Finally, it is shown that cost savings are mainly located in the footing of these structures.Este artículo se ocupa del diseño automático de estribos abiertos de hormigón armado en puentes de carretera de coste mínimo, empleando para ello dos algoritmos híbridos de escalada estocástica con operadores de mutación basados en los algoritmos genéticos. Los algoritmos empleados se basan en el recocido simulado (SAMO y en la aceptación por umbrales (TAMO. Ambos algoritmos se aplican a un estribo definido por 40 variables discretas. Se han comprobado ahorros económicos superiores al 18 % respecto a un estribo de referencia de una altura de 9 m realmente construido, con diferencias pequeñas entre ambos algoritmos, del 0,5 % a favor de SAMO. Además, se ha realizado un estudio paramétrico para alturas de estribo entre 6 y 15 m para diferentes tensiones admisibles del terreno que ofrece criterios de predimensionamiento a los proyectistas. Se ha comprobado, además, que el ahorro económico se localiza fundamentalmente en la zapata de estas estructuras.

  17. 种植支持式单端固定桥斜向集中载荷下的三维位移%Three-dimensional Displacement of Implant-supported Cantilever Fixed Partial Denture under Oblique Loading

    Institute of Scientific and Technical Information of China (English)

    王宏仁; 李爱洁; 陈新民

    2013-01-01

    本实验旨在研究种植支持式单端固定桥(CFPD)斜向集中受载时的三维位移.采用比格犬下颌骨作为实验对象,即刻种植ITI种植体两枚,建立以两种植体为基牙的种植支持式CFPD,采用数字激光散斑技术测量其在斜向加载时不同加载量下的三维位移.结果表明:斜向加载桥体时,随着载荷量的增加,基牙和桥体的位移量随之增大.在相同载荷下,桥体位移量最大,近缺隙侧基牙位移量次之,远缺隙侧基牙位移量最小;斜向加载基牙时,相应受载基牙位移量最大,桥体和邻近基牙位移量次之.在相同加载条件下,加载基牙时CFPD的位移量较加载桥体时的位移量小.因此,可认为种植支持式CFPD是一种可行的修复方式,但是在使用过程中要避免斜向受力,尤其是桥体的斜向受力.%The purpose of this study was to research the three-dimensional displacements of implant-supported cantilever fixed partial denture (CFPD) under oblique loading.One Beagle dog was used in this experiment.Two immediate implants of ITI were inserted in the mandible of the dog,and the implant-supported CFPD which used the implants as abutments was made in vitro fresh mandible.Then the digital laser speckle technique was employed to measure the three-dimensional displacements of CFPD under different oblique loading.We found that when an oblique loading was exerted on the pontic,the displacement increased with increasing of load.Under equal loading,the displacement of the abutment near to the pontic was smaller than that of the pontic but greater than that of the abutment far from the pontic.When oblique loading was exerted on the abutment,the displacement of the direct loaded abutment was greater than that of the other abutment and the pontic.Under the equal loading,the displacement of implant-supported CFPD of loading on pontic was greater than that of loading on abutments.The experiments demonstrated that implant-supported cantilever

  18. Level II scour analysis for Bridge 29 (HUNTTH00290029) on Town Highway 29, crossing Cobb Brook, Huntington, Vermont

    Science.gov (United States)

    Flynn, Robert H.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure HUNTTH00290029 on Town Highway 29 crossing Cobb Brook, Huntington, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in northwestern Vermont. The 4.16-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest upstream and downstream of the bridge. In the study area, Cobb Brook has an incised, straight channel with a slope of approximately 0.024 ft/ft, an average channel top width of 53 ft and an average bank height of 4 ft. The channel bed material ranges from gravel to bedrock with a median grain size (D50) of 112.0 mm (0.367 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 25, 1996, indicated that the reach was stable. The Town Highway 29 crossing of Cobb Brook is a 36-ft-long, one-lane bridge consisting of one 30-foot steel-beam span (Vermont Agency of Transportation, written communication, December 11, 1995) and a wooden deck. The opening length of the structure parallel to the bridge face is 27 ft.The bridge is supported by vertical, concrete abutments. The channel is skewed approximately 25 degrees to the opening while the opening-skew-to-roadway was measured to be 20 degrees. VTAOT records indicate an opening-skew-to-roadway of zero degrees. A scour hole 1.5 ft deeper than

  19. Rib fractures after reirradiation plus hyperthermia for recurrent breast cancer. Predictive factors

    Energy Technology Data Exchange (ETDEWEB)

    Oldenborg, Sabine; Valk, Christel; Os, Rob van; Voerde Sive Voerding, Paul zum; Crezee, Hans; Tienhoven, Geertjan van; Rasch, Coen [University of Amsterdam, Department of Radiation Oncology, Z1-215, Academic Medical Center, Amsterdam (Netherlands); Oei, Bing; Venselaar, Jack [Institute Verbeeten (BVI), Tilburg (Netherlands); Randen, Adrienne van [University of Amsterdam (AMC), Department of Radiology Academic Medical Center, Amsterdam (Netherlands)

    2016-04-15

    Combining reirradiation (reRT) and hyperthermia (HT) has shown high therapeutic value for patients with locoregional recurrent breast cancer (LR). However, additional toxicity of reirradiation (e.g., rib fractures) may occur. The aim of this study is to determine the impact of potential risk factors on the occurrence of rib fractures. From 1982-2005, 234 patients were treated with adjuvant reRT + HT after surgery for LR. ReRT consisted typically of 8 fractions of 4 Gy twice a week, or 12 fractions of 3 Gy four times a week. A total of 118 patients were irradiated with abutted photon and electron fields. In all, 60 patients were irradiated using either one or alternating combinations of abutted AP electron fields. Hyperthermia was given once or twice a week. The 5-year infield local control (LC) rate was 70 %. Rib fractures were detected in 16 of 234 patients (actuarial risk: 7 % at 5 years). All rib fractures occurred in patients treated with a combination of photon and abutted electron fields (p = 0.000); in 15 of 16 patients fractures were located in the abutment regions. The other significant predictive factors for rib fractures were a higher fraction dose (p = 0.040), large RT fields, and treatment before the year 2000. ReRT + HT results in long-term LC. The majority of rib fractures were located in the photon/electron abutment area, emphasizing the disadvantage of field overlap. Large abutted photon/electron fields combined with 4 Gy fractions increase the number of rib fractures in this study group. However, as these factors were highly correlated no relative importance of the individual factors could be estimated. Increasing the number of HT sessions a week does not increase the risk of rib fractures. (orig.) [German] Der kombinierte Einsatz von Rebestrahlung (reRT) und Hyperthermie (HT) zeigt eine hohe Wirksamkeit bei Patienten mit lokoregional rezidiviertem Brustkrebs (LR). Jedoch koennen zusaetzliche toxische Effekte von reRT (z. B. Rippenfrakturen

  20. 单端固定桥斜向受载三维位移的数字激光散斑技术研究%Study on the Digital Laser Speckle Technique of Three-dimensional Displacement of Cantilever Fixed Partial Denture under Oblique Loading

    Institute of Scientific and Technical Information of China (English)

    李爱洁; 陈新民; 徐祖杰; 张东姣

    2013-01-01

    The purpose of this study was to investigate the three-dimensional displacement of the cantilever fixed partial denture (CFPD) under an oblique loading. One Beagle dog was used in this experiment. The CFPD. which used the second premolar and the first molar as abutments and the second molar as pontic, was made in vitro fresh mandible of the Beagle dog. and the digital laser speckle (DLS) technique was employed to measure the three-dimensional displacement of the CFPD under the oblique loading for the first time. We found that when an oblique loading was exerted on the pontic, the displacement of CFPD was the greatest, and the displacement of the abutment near the pontic was smaller than that of the pontic but greater than that of the abutment far from the pontic. We also found that when an oblique loading was exerted on the abutment, the displacement of the directly loaded abutment was greater than that of the other abutment and the pontic. Under the oblique loading, the displacement increased with increasing of load. The experiment demonstrated that it would be advisable for the clinicians to avoid oblique loading, especially the oblique loading of the pontic when using the CPDF. The DLS technique may be one kind of methods for measuring the three-dimensional displacements of the small and irregular objects.%该实验旨在研究单端固定桥(CFPD)在斜向加载时的位移情况.采用新鲜离体比格犬下颌骨作为实验对象,制作可(765—|) CFPD,首次采用数字激光散斑技术测量CFPD在斜向加载时,不同加载量下的三维位移.结果表明:斜向加载桥体时,整个CFPD出现最大位移量,桥体位移量大于近缺隙侧基牙,近缺隙侧基牙大于远缺隙侧基牙;斜向加载基牙时,相应受载基牙位移量最大,桥体和邻近基牙次之.在斜向加载过程中,随着加载量的增加,位移量也增大.因此,可认为CFPD在使用过程中要避免斜向受力,尤其是桥体的斜向受力.此外,本研究

  1. Angled Cool-Tip Electrode for Radiofrequency Ablation of Small Superficial Subcapsular Tumors in the Liver: A Feasibility Study

    Science.gov (United States)

    Kim, Il Jung; Lee, Shin Jae; Shin, Min Woo; Shin, Won Sun; Chung, Yong Eun; Kim, Gyoung Min; Kim, Man Deuk; Won, Jong Yun; Lee, Do Yun; Choi, Jin Sub; Han, Kwang-Hyub

    2016-01-01

    Objective To evaluate the feasibility of angled cool-tip electrode for radiofrequency ablation of small superficial subcapsular liver tumors abutting abdominal wall, in order to traverse normal liver parenchyma, and thereby, obtain favorable configuration of ablation margin. Materials and Methods In this study, we retrospectively analyzed 15 small superficial subcapsular liver tumors abutting abdominal wall in 15 patients, treated with radiofrequency ablation from March 2013 to June 2015 using a cool-tip electrode manually modified to create 25–35° angle at the junction between exposed and insulated segments. The tumors were hepatocellular carcinoma (n = 13) and metastases (n = 2: cholangiocellular carcinoma and rectosigmoid cancer), with maximum diameter of 10–26 mm (mean, 15.68 ± 5.29 mm). Under ultrasonographic guidance, the electrode tip was advanced to the depth of the tumors' epicenter about 1 cm from the margin. The tip was re-directed to penetrate the tumor for radiofrequency ablation. Minimal ablation margin was measured at immediate post-treatment CT. Radiological images and medical records were evaluated for success rate, length of minimal ablation margin and complications. Results Technical success rate of obtaining complete necrosis of the tumors was 100%, with no procedure-related complication. Minimal ablation margin ranged from 3–12 mm (mean, 7.07 ± 2.23 mm). CT/MRI follow-up at 21–1022 days (mean, 519.47 ± 304.51 days) revealed no local recurrence, but distant recurrence in 9 patients. Conclusion Using an angled cool-tip electrode for radiofrequency ablation of small superficial subcapsular tumors abutting abdominal wall may be a feasible technique for obtaining adequate ablation margin and lower complication rate.

  2. Effect of axial loads on implant-supported partial fixed prostheses by strain gauge analysis

    Directory of Open Access Journals (Sweden)

    Luis Gustavo Oliveira de Vasconcellos

    2011-12-01

    Full Text Available OBJECTIVES: The present study used strain gauge analysis to perform an in vitro evaluation of the effect of axial loading on 3 elements of implant-supported partial fixed prostheses, varying the type of prosthetic cylinder and the loading points. MATERIAL AND METHODS: Three internal hexagon implants were linearly embedded in a polyurethane block. Microunit abutments were connected to the implants applying a torque of 20 Ncm, and prefabricated Co-Cr cylinders and plastic prosthetic cylinders were screwed onto the abutments, which received standard patterns cast in Co-Cr alloy (n=5. Four strain gauges (SG were bonded onto the surface of the block tangentially to the implants, SG 01 mesially to implant 1, SG 02 and SG 03 mesially and distally to implant 2, respectively, and SG 04 distally to implant 3. Each metallic structure was screwed onto the abutments with a 10 Ncm torque and an axial load of 30 kg was applied at five predetermined points (A, B, C, D, E. The data obtained from the strain gauge analyses were analyzed statistically by RM ANOVA and Tukey's test, with a level of significance of p<0.05. RESULTS: There was a significant difference for the loading point (p=0.0001, with point B generating the smallest microdeformation (239.49 µε and point D the highest (442.77 µε. No significant difference was found for the cylinder type (p=0.748. CONCLUSIONS: It was concluded that the type of cylinder did not affect in the magnitude of microdeformation, but the axial loading location influenced this magnitude.

  3. Experimental Study on Cracking, Reinforcement, and Overall Stability of the Xiaowan Super-High Arch Dam

    Science.gov (United States)

    Lin, Peng; Zhou, Weiyuan; Liu, Hongyuan

    2015-03-01

    The Xiaowan super-high arch dam has faced challenging construction problems. Here, we provide a scientifically-based reference for applying geomechanical model testing to support the nonlinear design of super-high arch dams. We applied experimental similarity theory and techniques. Based on four 3D geomechanical model tests, the dam stress characteristics, deformation distribution, and the safety factors of the dam foundation were identified and compared. We also analyzed cracking characteristics of the up- and downstream dam surfaces and induced joints in the dam heel, the rock mass failure process of the dam-foundation interface, and the abutments. We propose foundation reinforcement measures for weak rock masses, alteration zones, and other faults in the abutments based on the 3D and plane tests each at a different elevation. The results show that all dam deformations remained normal with no yielding or tensile cracking under a normal water load. The reinforced rock mass increased the crack initial safety in the dam heel and toe by ~20 %. The minimum crack initial safety factor ( K 1) of the dam heel was 1.4. The induced joint in the dam heel contributed to a reduction in tensile stress at the upstream dam heel, improving K 1. Compared with similar projects following reinforcement measures, the abutment stiffness and overall stability of the Xiaowan arch dam satisfy operational requirements. Four years of monitoring operations show that key areas near the dam remained normal and the dam foundation is functioning well. Our results may also be applicable to the design and construction of similar projects worldwide.

  4. 阐述市政桥梁下部结构施工技术

    Institute of Scientific and Technical Information of China (English)

    徐严严

    2015-01-01

    the lower part of the bridge structure including the bridge abutment, bridge piers and foundation, etc. They each play an important role. The main role of the abutment is supporting structure of bridge span structure. Piers usualy refers to, in the middle of a multi span or large span bridge abutment. It suffered more load, in addition to the descendents of the upper structure load, wind, water pressure, and some areas because of the cold weather in winter and the possibility of ice load, then there is due to emergencies such as impact force. Base is coming from the upper structure under the action of load, and the load along with respect to the foundation.%桥梁的下部结构包括桥台、桥墩和基础等。它们各自都起着重要的作用。桥台的主要作用就是支承桥跨结构的结构物。桥墩通常是指位于多跨或者大跨越桥梁的中间的支承物。它承受着较多的载荷,除了上部结构传递下来的载荷之外,还包括风力、流水的压力以及某些地区冬天由于天气冷而可能出现的冰载荷,再有就是由于突发事件的撞击力等。基础的作用就是承受由上部结构传来的载荷,并将载荷连同自重一起传给地基。

  5. Stress analysis of mandibular implant-retained overdenture with independent attachment system: effect of restoration space and attachment height.

    Science.gov (United States)

    Ebadian, Behnaz; Talebi, Saeid; Khodaeian, Niloufar; Farzin, Mahmoud

    2015-01-01

    In this in vitro study, 2 implants were embedded in the interforaminal region of an acrylic model. Two kinds of retention mechanisms were used to construct complete overdentures: ball type and direct abutment (Locator). The ball-type retention mechanism models included 3 different collar heights (1, 2, and 3 mm) with 15 mm occlusal plane height, and 3 different occlusal plane heights (9, 12, and 15 mm) with 1 mm collar height. The direct abutment models included 3 different occlusal plane heights (9, 12, and 15 mm) with 1 mm cuff height. Vertical unilateral and bilateral loads of 150 N were applied to the central fossa of the first molar. The stress of the bone around the implant was analyzed by finite element analysis. The results showed that by increasing vertical restorative space, the maximum stress values around implants were decreased in both unilateral and bilateral loading models. The results also showed that the increase in maximum stress values around implants correlated with the ball attachment collar height. The Locator attachment with a 1 mm cuff height and 9 mm occlusal plane height demonstrated 6.147 and 3.914 MPa in unilateral and bilateral loading conditions, respectively. While a reduction in the collar height of a ball-type retention mechanism and an increase in the vertical restorative space in direct abutment retention mechanisms are both biomechanically favorable, and may result in reduced stress in peri-implant bone, a ball attachment seems to be more favorable in the stress distribution around an implant than a Locator attachment.

  6. Penumbra modifier for optimal electron fields combination

    International Nuclear Information System (INIS)

    Abutment of two or more electron fields to irradiate extended areas may lead to significant dose inhomogeneities in the junction region. This study describes the geometric and dosimetric characteristics of a device developed to modify the penumbra of an electron beam and therapy improve of dose uniformity in the over lap region when fields are abutted. The device is lipowitz metal block placed on top of the insertion plate of the electron applicator and positioned to stop part of he electron beam on side of field abutment. The air-scattered electrons beyond the block increase the penumbra width from about 1,4 to 2-7-43.4 cm at SSD 100 cm, the modified penumbra is broad and almost linear at all depths for the 6.8, and 15 MeV electron beams used. Film dosimetry was used to obtain profiles, iso-dose distributions, single modified beams and matched fields of 6, 10, and 15 MeV. Wellhofer dosimetry system was used to obtain beam profiles and iso-dose distributions of single modified beams needed for CADPLAN treatment planning system, which used to optimize and compare the skin gap to be used and to quantify the dose uniformity in a junction of the field separation for both modified and non-modified beams. Results are presented for various field configurations without the penumbra modifier; lateral setup error of 2-3 mm may introduce dose variations of 20% or more in the junction region. Similar setup error cause less than 5% dose variations when the penumbra modifier is used to match the field

  7. Evaluation in Accuracy to Two Impression Techniques: In Case of Bone Anchored Bridge

    Directory of Open Access Journals (Sweden)

    Sularsih Sularsih

    2013-07-01

    Full Text Available Purpose: The purpose of this study was to investigate and compare the accuracy of two procedures: open tray with splinting technique and closed tray impression techniques, in innovative in vitro experiments. Materials and Methods: One master cast was fabricated with 4 abutment replica implants with almost parallel position in an anterior region of an edentuloys mandibular plaster cast. The working cast was taken impessions with open tray splinting technique (group 1 and closed tray technique (group 2 using polyvinyl siloxane impression material. The Type III dental stone ws poured into around the impressions. The accuracy of impression procedured were measured 24 hours long after pouring dental stone to each impression. Four sited were marked to measured on every platform of implant analogs. The analyzing stylus was positioned to each site and the heights, horizontal inclination and saggital incliniation were measured using the Laser displacement transducer (LK G115; Keyence, Osaka, Japan. Measurements of these 16 points of four implants per a model was repeated 7 times under the same condition. The gap between the abutment and superstructure at one screw test was evaluated with a digital microscope system (VH-Z100 & VH-5000; Keyence, Osaka, Japan. The mean and standard deviation estimated from the samples of each subgroup were statistically analyzed by ANOVA test (P<0.05 as the level of significance. Results: The relative differences of implant heights, horizontal inclination and saggital inclination of each implant on closed tray technique was statistically different to master cast and open tray with splinting (P<0.005. Conclusion: The open tray technique was more accurate comparing to the closed tray technique. The gap between the abutment and superstructure in the open tray with splinting technique was smaller comparing to closed tray technique.DOI: 10.14693/jdi.v17i1.111

  8. Fracture resistance of a selection of full-contour all-ceramic crowns: an in vitro study.

    Science.gov (United States)

    Zesewitz, Tim F; Knauber, Andreas W; Northdurft, Frank P

    2014-01-01

    This study aimed to evaluate the fracture resistance of monolithic single crowns made from zirconia (ZI), lithium disilicate (LS2), or feldspar ceramic (FC). Five groups of crowns representing a maxillary first molar were made with the appropriate dimensions according to the manufacturer's instructions. The ZI and LS2 crowns were luted adhesively or cemented conventionally on a metal abutment tooth analog. The feldspar ceramic crowns were luted adhesively. All specimens underwent axial loading until fracture. The crowns in the ZI groups possessed the highest fracture resistance independent of the mode of fixation.

  9. Biofilm and saliva affect the biomechanical behavior of dental implants.

    Science.gov (United States)

    Bordin, Dimorvan; Cavalcanti, Indira M G; Jardim Pimentel, Marcele; Fortulan, Carlos A; Sotto-Maior, Bruno S; Del Bel Cury, Altair A; da Silva, Wander José

    2015-04-13

    Friction coefficient (FC) was quantified between titanium-titanium (Ti-Ti) and titanium-zirconia (Ti-Zr), materials commonly used as abutment and implants, in the presence of a multispecies biofilm (Bf) or salivary pellicle (Pel). Furthermore, FC was used as a parameter to evaluate the biomechanical behavior of a single implant-supported restoration. Interface between Ti-Ti and Ti-Zr without Pel or Bf was used as control (Ctrl). FC was recorded using tribometer and analyzed by two-way Anova and Tukey test (pbehavior of a single implant-supported restoration. PMID:25711169

  10. Machine learning and statistical methods for the prediction of maximal oxygen uptake: recent advances

    OpenAIRE

    Abut F; Akay MF

    2015-01-01

    Fatih Abut, Mehmet Fatih AkayDepartment of Computer Engineering, Çukurova University, Adana, TurkeyAbstract: Maximal oxygen uptake (VO2max) indicates how many milliliters of oxygen the body can consume in a state of intense exercise per minute. VO2max plays an important role in both sport and medical sciences for different purposes, such as indicating the endurance capacity of athletes or serving as a metric in estimating the disease risk of a person. In general, the direct measurement...

  11. Machine learning and statistical methods for the prediction of maximal oxygen uptake: recent advances

    OpenAIRE

    Akay, Fatih

    2015-01-01

    Fatih Abut, Mehmet Fatih AkayDepartment of Computer Engineering, Çukurova University, Adana, TurkeyAbstract: Maximal oxygen uptake (VO2max) indicates how many milliliters of oxygen the body can consume in a state of intense exercise per minute. VO2max plays an important role in both sport and medical sciences for different purposes, such as indicating the endurance capacity of athletes or serving as a metric in estimating the disease risk of a person. In general, the direct measure...

  12. Cell wall glycoproteins at interaction sites between parasitic giant dodder (Cuscuta reflexa) and its host Pelargonium zonale.

    Science.gov (United States)

    Striberny, Bernd; Krause, Kirsten

    2015-01-01

    The process of host plant penetration by parasitic dodder (genus Cuscuta) is accompanied by molecular and structural changes at the host/parasite interface. Recently, changes in pectin methyl esterification levels in the host cell walls abutting parasitic cells in established infection sites were reported. In addition to that, we show here that the composition of cell wall glycoproteins in Cuscuta-infected Pelargonium zonale undergoes substantial changes. While several arabinogalactan protein epitopes exhibit decreased abundances in the vicinity of the Cuscuta reflexa haustorium, extensins tend to increase in the infected areas. PMID:26367804

  13. Orbitofrontal cholesterol granuloma: percutaneous endoscopic-assisted curettage.

    Science.gov (United States)

    Selva, Dinesh; Lai, Tze; Krishnan, Suren

    2003-11-01

    This paper describes the use of endoscopic visualization in curettage of orbital cholesterol granuloma (OCG). Two males aged 54 and 50 years presented with orbitofrontal cholesterol granulomas arising in the superolateral frontal bone and abutting the dura. The granulomas were approached via a superior eyelid crease incision and a 70 degree rigid endoscope was used to visualize curettage of the granuloma from the inner surface of the frontal bone and the dura. Both patients made an uncomplicated recovery and there was no recurrence at eight months and two years follow up. Percutaneous endoscopic curettage is an alternative to blind curettage, lateral orbitotomy or frontal craniotomy for OCG. PMID:14670153

  14. Mechanisms regulating proteostasis are involved in sympatric speciation of the blind mole rat, Spalax galili.

    Science.gov (United States)

    Rodriguez, Karl A; Li, Kexin; Nevo, Eviatar; Buffenstein, Rochelle

    2016-01-01

    Genome-wide analysis demonstrates extensive genomic adaptive complexes involved in sympatric speciation between blind mole rats (Spalax galili) in abutting populations living in basalt and chalk soils. Among the gene ontology (GO) enrichment, musculature and metabolism stood out in basalt dwellers while nutrition and neurogenetics were highlighted in chalk residents. Measurements of mechanisms regulating protein homeostasis inspired by these GO terms suggest that at the proteomic level there is also a habitat/soil-type driven divergence with the basalt residents exhibiting higher proteasome activity whereas elevated levels of markers of autophagy are evident in the chalk inhabitants.

  15. Fiber reinforced composite loop space maintainer: An alternative to the conventional band and loop

    Directory of Open Access Journals (Sweden)

    Ramakrishna Yeluri

    2012-01-01

    Full Text Available The stainless steel band and loop appliance is the most commonly used fixed space maintainer in pediatric dentistry. But there are several disadvantages with this appliance such as the need for a cast or a working model, decalcification of the abutment tooth, loosening because of breakage or dissolution of the luting agent, tendency to get embedded in the soft tissue and the possibility of metal allergy. The purpose of this article is to present a simple, laboratory design of a "Fiber Reinforced Composite" (FRC loop space maintainer and discuss the advantages over the traditional band and loop space maintainers.

  16. Fiber reinforced composite loop space maintainer: An alternative to the conventional band and loop.

    Science.gov (United States)

    Yeluri, Ramakrishna; Munshi, Autar Krishen

    2012-04-01

    The stainless steel band and loop appliance is the most commonly used fixed space maintainer in pediatric dentistry. But there are several disadvantages with this appliance such as the need for a cast or a working model, decalcification of the abutment tooth, loosening because of breakage or dissolution of the luting agent, tendency to get embedded in the soft tissue and the possibility of metal allergy. The purpose of this article is to present a simple, laboratory design of a "Fiber Reinforced Composite" (FRC) loop space maintainer and discuss the advantages over the traditional band and loop space maintainers.

  17. 延長ブリッジ装着時の咬合面垂直荷重に対する下顎骨の力学的反応

    OpenAIRE

    岩崎, 精彦; 吉原, 隆二; 甘利, 光治

    1994-01-01

    Extension-bridge has been accepted as the substitute for removable partial dentures for patients missing most distal teeth due to the fact that removable partial dentures cause discomfort for patients. On the other hand, it is pointed out that the cantilever force of the extension-bridge causes periodontal disease with absorption of bone and gingivitis of the abutment teeth. In this study, we attached the three-unit-extension-bridge to the dried mandibular bone of an adult human and force cor...

  18. Controlling floor heave of extraction opening by reinforcing sides and roof

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-jun

    2005-01-01

    The effect of reinforcing roof, sides and floor corners to control floor heave of extraction opening was analyzed, It was proved by engineering practice and numerical simulation that reinforcing any part of surrounding rock have certainly control effect for floor heave, in the basis of this, the new way that roof, sides and floor corners were reinforced to control floor heave was put forward. Contrasting control result of reinforcing floor with this, it is determined that reinforcing is more suitable to control floor heave of extraction opening than reinforcing floor when advancing abutment pressure is in some range.

  19. Peroneal spastic flatfoot in adolescents with accessory talar facet impingement: a preliminary report.

    Science.gov (United States)

    Niki, Hisateru; Aoki, Haruhito; Hirano, Takaaki; Akiyama, Yui; Fujiya, Hiroto

    2015-07-01

    This study analyzed imaging, arthroscopic findings, and treatment responses for peroneal spastic flatfoot (PSFF) caused by talocalcaneal impingement at the accessory anterolateral talar facet (AALTF) (accessory talar facet impingement) in 13 adolescents without histories of trauma and tarsal coalition. The AALTF was determined with computed tomography and MRI. Focal abutting bone marrow edema (FABME) on MRI around the AALTF was confirmed. In seven patients who underwent AALTF resection, subtalar arthroscopy was performed. All experienced alleviation PSFF after treatment; reduction in FABME was observed. AALTF resection alone is beneficial for PSFF caused by accessory talar facet impingement when peroneal spasms are restored by an injection of local anesthesia.

  20. DOES PROXIMITY TO A GOLF COURSE MATTER?

    OpenAIRE

    Owusu-Edusei, Kwame; Espey, Molly

    2003-01-01

    In this study, we augment an earlier study by estimating the effect of golf courses on housing values using a data set of single-family homes sold between 1994 and 2000. We find that there is generally a positive impact on houses proximate to open space (golf courses and neighborhood parks). The value of proximity to a golf course is found to be greater than figures reported in previous studies. Proximity impacts extend beyond abutting properties and go as far as to those within almost a quar...

  1. Cohesin and the nucleolus constrain the mobility of spontaneous repair foci.

    Science.gov (United States)

    Dion, Vincent; Kalck, Véronique; Seeber, Andrew; Schleker, Thomas; Gasser, Susan M

    2013-11-01

    The regulation of chromatin mobility in response to DNA damage is important for homologous recombination in yeast. Anchorage reduces rates of recombination, whereas increased chromatin mobility correlates with more efficient homology search. Here we tracked the mobility and localization of spontaneous S-phase lesions bound by Rad52, and find that these foci have reduced movement, unlike enzymatically induced double-strand breaks. Moreover, spontaneous repair foci are positioned in the nuclear core, abutting the nucleolus. We show that cohesin and nucleolar integrity constrain the mobility of these foci, consistent with the notion that spontaneous, S-phase damage is preferentially repaired from the sister chromatid.

  2. Laser repair hardfacing of titanium alloy turbine

    OpenAIRE

    A. Klimpel; D. Janicki; A. Lisiecki; A. Rzeźnikiewicz

    2011-01-01

    Purpose: of this paper: work out repair technology of worn abutments of aircraft jet engine blades forged of titanium alloy WT3-1.Design/methodology/approach: The study were based on the analysis of laser HPDL powder surfacing of titanium alloy plates using wide range chemical composition consumables of titanium alloys and mixtures of pure titanium and spherical powder of WC indicated that very hard and highest quality deposits are provided by powder mixture of 40-50%Ti+60-50%WC.Findings: It ...

  3. Method for generating a mesh representation of a region characterized by a trunk and a branch thereon

    Science.gov (United States)

    Shepherd, Jason; Mitchell, Scott A.; Jankovich, Steven R.; Benzley, Steven E.

    2007-05-15

    The present invention provides a meshing method, called grafting, that lifts the prior art constraint on abutting surfaces, including surfaces that are linking, source/target, or other types of surfaces of the trunk volume. The grafting method locally modifies the structured mesh of the linking surfaces allowing the mesh to conform to additional surface features. Thus, the grafting method can provide a transition between multiple sweep directions extending sweeping algorithms to 23/4-D solids. The method is also suitable for use with non-sweepable volumes; the method provides a transition between meshes generated by methods other than sweeping as well.

  4. Consumption Externalities and Diffusion in Pharmaceutical Markets: Antiulcer Drugs

    OpenAIRE

    Berndt, Ernst R.; Robert S. Pindyck; Pierre Azoulay

    2000-01-01

    We examine the role of consumption externalities in the demand for pharmaceuticals at both the brand level and over a therapeutic class of drugs. These effects emerge when use of a drug by others affects its value, and/or conveys information abut efficacy and safety to patients and physicians. This can affect that rate of market diffusion for a new entrant, and can lead to herb behavior whereby a particular drug can dominate the market despite the availability of close substitutes. We use dat...

  5. Effect on the Occurrence and Epidemic of Corn Northern Leaf Blight in Two-plant Cultivation Mode%双株栽培模式对玉米大斑病流行时间动态影响

    Institute of Scientific and Technical Information of China (English)

    傅俊范; 刘震; 景殿玺; 周如军; 薛彩云

    2014-01-01

    The two-plant cultivation mode is the production of corn in Liaoning province on the new cultivation mode, which consists of two-plant orientation cultivation mode and two-plant abutted cultivation mode. According to the principles of plant disease epidemiology, epidemic dynamics of Northern Leaf Blight of corn was comparative-ly studied among two-plant orientation cultivation mode, two-plant abutted cultivation mode and conventional culti-vation mode, by using field experimental design and artificial inoculation technique. The research showed that the disease indexes in two-plant orientation cultivation mode and two-plant abutted cultivation mode were lower than conventional cultivation mode. By comparative analysis with SPSS 11.5, Logistic model is suitable for describing the epidemic dynamics of Northern Leaf Blight in the two-plant orientation cultivation mode, two-plant abutted cultiva-tion mode and conventional cultivation mode.%双株栽培模式是辽宁省玉米生产的新型栽培模式,包括双株定向栽培模式和双株紧靠栽培模式。根据植物病害流行学原理,通过田间试验设计及人工接种技术,对双株定向栽培模式、双株紧靠栽培模式和常规栽培模式下玉米大斑病发生流行动态进行比较研究。调查研究发现,双株定向栽培模式和双株紧靠栽培模式的病情指数低于常规栽培模式。通过SPSS 11.5软件对比分析,Logistic模型适用于描述双株定向栽培模式、双株紧靠栽培模式和常规栽培模式下玉米大斑病流行时间动态。

  6. Zirconia Rehabilitation Focused on the Emergence Profile: A Case Report.

    Science.gov (United States)

    Mesquita, Alfredo Mikail Melo; Kojima, Alberto Noriyuki; Giovani, Elcio Madaglena; Saraceni, Cintia Helena Coury; Rodrigues, Flávia Pires

    2016-06-01

    The first choice for anterior rehabilitation has been metal-free materials due to their successful aesthetic results. However, the definitive clinical work accuracy may be affected by the lack of clinicians' expertise and familiarization with the latest techniques, as well as recurrent laboratory procedures. This manuscript presents a clinical experience with zirconia ceramic for anterior crowns and zirconia CAD/CAM abutments, including both clinical and laboratory steps after the implant installation. The 'emergence profile' and the 'double scanning' techniques obtained by the waxing technique appear to be a very promising procedure for aesthetic improvement of the single-implant zirconia restoration in anterior teeth.

  7. Study of behaviour of workings in longwall panel based on field instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    V.R. Sastry; Roshan Nair [National Institute of Technology Karnataka, Mangalore (India). Department of Mining Engineering

    2009-07-01

    The paper presents field monitoring study of two adjacent longwall panels based on stress measurements in longwall block and barrier, load transferred on to the gate roads and convergence measurements in the gate roads during face retreat in the panels. Results indicated that the section of barrier lying in the goaf experienced higher abutment stress when compared with the section lying ahead of face. There was a transfer of load in gate roads ahead of face after the occurrence of roof fall in goaf. Maximum cumulative convergence of more than 8 mm was observed in the gate roads during weightings.

  8. Masticatory function and patient satisfaction with implant-supported mandibular overdentures: a prospective 5-year study

    DEFF Research Database (Denmark)

    Bakke, Merete; Holm, Betty; Gotfredsen, Klaus

    2002-01-01

    participated. They were in good health but had retention problems with their mandibular dentures. First, all patients received new dentures. After 3 months, two Astra Tech implants were placed in the anterior part of the mandible, and 6 months later the abutments were connected. Patient assessment...... (questionnaire) and functional recordings (chewing ability, bite force, electromyographic activity) were performed with the new dentures, and again 3 months, 1 year, and 5 years after overdenture treatment. RESULTS: After treatment, all patients were able to comminute hard and tough food, the maximum bite force...

  9. Estimation of potential scour at bridges on local government roads in South Dakota, 2009-12

    Science.gov (United States)

    Thompson, Ryan F.; Wattier, Chelsea M.; Liggett, Richard R.; Truax, Ryan A.

    2014-01-01

    In 2009, the U.S. Geological Survey and South Dakota Department of Transportation (SDDOT) began a study to estimate potential scour at selected bridges on local government (county, township, and municipal) roads in South Dakota. A rapid scour-estimation method (level-1.5) and a more detailed method (level-2) were used to develop estimates of contraction, abutment, and pier scour. Data from 41 level-2 analyses completed for this study were combined with data from level-2 analyses completed in previous studies to develop new South Dakota-specific regression equations: four regional equations for main-channel velocity at the bridge contraction to account for the widely varying stream conditions within South Dakota, and one equation for head change. Velocity data from streamgages also were used in the regression for average velocity through the bridge contraction. Using these new regression equations, scour analyses were completed using the level-1.5 method on 361 bridges on local government roads. Typically, level-1.5 analyses are completed at flows estimated to have annual exceedance probabilities of 1 percent (100-year flood) and 0.2 percent (500-year flood); however, at some sites the bridge would not pass these flows. A level-1.5 analysis was then completed at the flow expected to produce the maximum scour. Data presented for level-1.5 scour analyses at the 361 bridges include contraction, abutment, and pier scour. Estimates of potential contraction scour ranged from 0 to 32.5 feet for the various flows evaluated. Estimated potential abutment scour ranged from 0 to 40.9 feet for left abutments, and from 0 to 37.7 feet for right abutments. Pier scour values ranged from 2.7 to 31.6 feet. The scour depth estimates provided in this report can be used by the SDDOT to compare with foundation depths at each bridge to determine if abutments or piers are at risk of being undermined by scour at the flows evaluated. Replicate analyses were completed at 24 of the 361 bridges

  10. Comparison of Marginal Bone Changes with Internal Conus and External Hexagon Design Implant Systems: A Prospective, Randomized Study.

    Science.gov (United States)

    Cooper, Lyndon F; Tarnow, Dennis; Froum, Stuart; Moriarty, John; De Kok, Ingeborg J

    2016-01-01

    A central dental implant success criterion is the marginal bone response as measured longitudinally. Factors that influence marginal bone changes include osseous and soft tissue architecture, occlusal loading factors, implant position, implant design, and inflammatory processes. The evolution of implant design is multifactorial and includes the implant-abutment interface geometries. The primary objective of this study was to compare the proximal marginal bone changes following placement and loading of internal conus design implants (ICI) and external hex design implants (EXI) used in the treatment of posterior partial edentulism. Among 45 enrolled participants, 39 were treated with 47 ICI or 46 EXI implants using a one-stage implant protocol. Prosthetic restoration was completed after 12 weeks using stock titanium abutments and all-ceramic crowns. Follow-up visits including clinical and radiographic examinations were performed 6 months after permanent restoration and then annually for 3 years. Marginal bone level changes, papilla index scores, condition of the peri-implant mucosa, presence of complications, and participant satisfaction were evaluated. The mean marginal bone level change from implant placement to 3 years was -0.25 ± 0.60 mm and -0.5 ± 0.93 mm for ICI and EXI implants, respectively. The change recorded from permanent restoration to 3 years was a gain of 0.31 ± 0.41 mm versus 0.04 ± 0.51 mm for ICI and EXI implants, respectively (P 90%) of participants stated they were satisfied or very satisfied with their implant prosthesis and rated function and esthetics highly for both implant types after 3 years in function. Modestly greater marginal bone loss occurred at EXI implants. Further, more positive papilla scores were found between adjacent ICI implants than between adjacent EXI implants. EXI implants displayed more abutment complications than the ICI implants. The implant-abutment interface design may contribute to therapeutic outcome differences

  11. Management of long span partially edentulous maxilla with fixed removable denture prosthesis

    Directory of Open Access Journals (Sweden)

    Mahilan I Jeyavalan

    2012-01-01

    Full Text Available Restoration of a long span partially edentulous maxilla with tooth supported prosthesis is challenging because of inherent anatomic limitations and unfavourable biomechanics present after the loss of teeth. A tooth supported fixed-removable prosthesis is a treatment option for restoration of such long span partially edentulous maxillary arches. This prosthesis meets the requirements for esthetics, phonetics, comfort, and hygiene, as well as favourable biomechanical stress distribution to the remaining natural tooth abutments. This article presents a procedure for fabrication of a fixed-removable prosthesis that has cement-retained custom cast bar metal substructure and a ball attachment retained removable superstructure prosthesis.

  12. Cell wall glycoproteins at interaction sites between parasitic giant dodder (Cuscuta reflexa) and its host Pelargonium zonale.

    Science.gov (United States)

    Striberny, Bernd; Krause, Kirsten

    2015-01-01

    The process of host plant penetration by parasitic dodder (genus Cuscuta) is accompanied by molecular and structural changes at the host/parasite interface. Recently, changes in pectin methyl esterification levels in the host cell walls abutting parasitic cells in established infection sites were reported. In addition to that, we show here that the composition of cell wall glycoproteins in Cuscuta-infected Pelargonium zonale undergoes substantial changes. While several arabinogalactan protein epitopes exhibit decreased abundances in the vicinity of the Cuscuta reflexa haustorium, extensins tend to increase in the infected areas.

  13. Strength of CAD/CAM-generated esthetic ceramic molar implant crowns

    OpenAIRE

    Wolf, D; Bindl, A; Schmidlin, P R; Lüthy, H; Mörmann, W H

    2008-01-01

    PURPOSE: 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. MATERIALS AND METHODS: 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...

  14. Evaluation of the adaptation of zirconia-based fixed partial dentures using micro-CT technology

    OpenAIRE

    Marcia Borba; Walter Gomes Miranda Jr.; Paulo Francisco Cesar; Jason Allan Griggs; Alvaro Della Bona

    2013-01-01

    The objective of the study was to measure the marginal and internal fit of zirconia-based all-ceramic three-unit fixed partial dentures (FPDs) (Y-TZP - LAVA, 3M-ESPE), using a novel methodology based on micro-computed tomography (micro-CT) technology. Stainless steel models of prepared abutments were fabricated to design FPDs. Ten frameworks were produced with 9 mm2 connector cross-sections using a LAVATM CAD-CAM system. All FPDs were veneered with a compatible porcelain. Each FPD was seated ...

  15. Interface Coupling Transition in a Thin EpitaxialAntiferromagnetic Film Interacting with a Ferromagnetic Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Finazzi, M.; Brambilla, A.; Biagioni, P.; Graf, J.; Gweon, G.-H.; Scholl, A.; Lanzara, A.; Duo, L.

    2006-09-07

    We report experimental evidence for a transition in theinterface coupling between an antiferromagnetic film and a ferromagneticsubstrate. The transition is observed in a thin epitaxial NiO film grownon top of Fe(001) as the film thickness is increased. Photoemissionelectron microscopy excited with linearly polarized x rays shows that theNiO film is antiferromagnetic at room temperature with in-plane uniaxialmagnetic anisotropy. The anisotropy axis is perpendicular to the Fesubstrate magnetization when the NiO thickness is less than about 15A,but rapidly becomes parallel to the Fe magnetization for a NiO coveragehigher than 25 A.

  16. CT staging of lung cancer: the role of artificial pneumothorax

    International Nuclear Information System (INIS)

    To determine the role of artificially induced pneumothorax in the evaluation of the chest wall and mediastinal invasion in patients with peripheral bronchogenic carcinoma. CT scans of 22 patients obtained after induced pneumothorax were evaluated. All patients had peripheral lung mass abutting the pleura on a routine CT scan. Room air of 200-400ml was introduced through intrathoracic negative pressure initially, followed by pressure injection through the 18 gauge long bevelled needle under fluoroscopic control. Conclusively, CT with artificial pneumothorax added more information than conventional CT in the evaluation of the chest wall or mediastinal invasion by lung cancer without notable risk

  17. Level II scour analysis for Bridge 26 (ROYATH00540026) on Town Highway 54, crossing Broad Brook, Royalton, Vermont

    Science.gov (United States)

    Burns, Ronda L.; Weber, Matthew A.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure ROYATH00540026 on Town Highway 54 crossing Broad Brook, Royalton, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the New England Upland section of the New England physiographic province in central Vermont. The 11.9-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover on the left bank upstream and downstream is pasture with trees and brush on the immediate banks. The right bank, upstream and downstream of the bridge, is forested. In the study area, Broad Brook has an incised, sinuous channel with a slope of approximately 0.01 ft/ft, an average channel top width of 37 ft and an average bank height of 4 ft. The channel bed material ranges from sand to boulders with a median grain size (D50) of 66.3 mm (0.218 ft). The geomorphic assessment at the time of the Level I site visit on April 13, 1995 and the Level II site visit on July 11, 1996, indicated that the reach was stable. The Town Highway 54 crossing of Broad Brook is a 29-ft-long, one-lane bridge consisting of one 24-foot steel-beam span with a timber deck (Vermont Agency of Transportation, written communication, March 23, 1995). The opening length of the structure parallel to the bridge face is 23.3 ft. The bridge is supported by a vertical, concrete face laid-up stone abutment with concrete wingwalls on the left and a laid-up stone

  18. Level II scour analysis for Bridge 33 (TUNBTH00450033) on Town Highway 45, crossing the First Branch White River, Tunbridge, Vermont

    Science.gov (United States)

    Wild, E.C.; Severance, Timothy

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure TUNBTH00450033 on Town Highway 45 crossing the First Branch White River, Tunbridge, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the New England Upland section of the New England physiographic province in central Vermont. The 86.4-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture upstream and downstream of the bridge, while woody vegetation sparsely covers the immediate banks. In the study area, the First Branch White River has an incised, sinuous channel with a slope of approximately 0.003 ft/ft, an average channel top width of 68 ft and an average bank height of 7 ft. The channel bed material ranges from sand to gravel with a median grain size (D50) of 27.1 mm (0.089 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 18, 1995, indicated that the reach was laterally unstable due to a cut-bank present on the upstream right bank and a wide channel bar in the upstream reach. The Town Highway 45 crossing of the First Branch White River is a 67-ft-long, one-lane bridge consisting of one 54-foot timber thru-truss span (Vermont Agency of Transportation, written communication, March 23, 1995). The opening length of the structure parallel to the bridge face is 53.5 ft. The bridge is supported on the right by a vertical, concrete abutment

  19. Level II scour analysis for Bridge 12 (BRAITH00230012) on Town Highway 23, crossing Ayers Brook, Braintree, Vermont

    Science.gov (United States)

    Olson, Scott A.

    1996-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure BRAITH00230012 on town highway 23 crossing Ayers Brook, Braintree, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). A Level I study is included in Appendix E of this report. A Level I study provides a qualitative geomorphic characterization of the study site. Information on the bridge available from VTAOT files was compiled prior to conducting Level I and Level II analyses and can be found in Appendix D. The site is in the Green Mountain physiographic province of central Vermont in the town of Braintree. The 18.8-mi2 drainage area is in a predominantly rural watershed. In the vicinity of the study site, the surface cover of the left and right banks is pasture. In the study area, Ayers Brook has a meandering channel with a slope of approximately 0.003 ft/ft, an average channel top width of 46 ft and an average channel depth of 5 ft. The predominant channel bed material is sand and gravel (D50 is 6.15 mm or 0.0202 ft). The geomorphic assessment at the time of the Level I and Level II site visit on November 16, 1994, indicated that the reach was laterally unstable. Also at the time of the site visit, there was considerable backwater at the bridge site due to a beaver dam downstream. The beaver dam was ignored in the analyses. The town highway 23 crossing of Ayers Brook is a 28-ft-long, one-lane bridge consisting of one 23-foot span (Vermont Agency of Transportation, written communication, August 24, 1994). The bridge is supported by vertical timber cribwork abutments with wingwalls on the upstream and downstream sides of the right abutment. The lower half of the right abutment and wingwalls are constructed of laid-up stone. The right abutment and wingwalls are also protected by stone fill. The channel is skewed approximately 45

  20. Cascade Mountain Range in Oregon

    Science.gov (United States)

    Sherrod, David R.

    2016-01-01

    The Cascade mountain system extends from northern California to central British Columbia. In Oregon, it comprises the Cascade Range, which is 260 miles long and, at greatest breadth, 90 miles wide (fig. 1). Oregon’s Cascade Range covers roughly 17,000 square miles, or about 17 percent of the state, an area larger than each of the smallest nine of the fifty United States. The range is bounded on the east by U.S. Highways 97 and 197. On the west it reaches nearly to Interstate 5, forming the eastern margin of the Willamette Valley and, farther south, abutting the Coast Ranges. 

  1. A 3-DFE Stress analysis of a cantilevered fixed particle denture.%用三维有限元方法对单端固定桥进行应力分析

    Institute of Scientific and Technical Information of China (English)

    李美华; 王伟; 董丽华; 冯剑桥; 周振平

    2000-01-01

    Objective:To analyze the stress state of a cantilevered fixed particle dentures. Methods:three-dimensional finite methods was used to analyze the stresses of a posterior cantilevered fixed partial denture by altering the splinted abutments and the length of the Pontic in the peridontitium with normal and reduced bone support, to analyze and calculate the stress and displacement. Result:High stress concentration lied around the abutment closet the cantilever. Reduced bone support increased the deflection and stress concentration. When teeth were splinted together, displacement and stress concentration was reduced. That the number of splinted abutments were increased didn't result in a proportional reduction of stress in the periodontium, long cantilevered Pontic obviously increased the stress and the deflection of a cantilevered fixed partial denture. Conclude:It is better to select one molar Pontic and at least two abutments for a successful posterior cantilevered fixed partial denture.%目的:分析磨牙游离缺失单端固定桥修复的受力情况。方法:运用三维有限元应力分析法,对一侧磨牙游离缺失通过改变牙槽骨支持高度,采用不同基牙数目,不同桥体长度建立不同的单端固定桥有限元模型进行应力和位移的计算和分析。结果:较高的应力集中在游离端近中的基牙上,牙槽骨高度降低会增加基牙的移位及应力集中;单纯增加基牙的数目不会导致牙周组织中应力明显相应减少;基牙数目增加会减少修复体移位及应力集中;增加桥体长度会引起义齿应力明显增加和向远中移位。结论:游离缺失端行单端固定桥修复最好选择桥体为一个磨牙长度,且基牙数至少两个,以提高单端固定桥修复的成功率。

  2. Seepage Analysis of Upper Gotvand Dam Concerning Gypsum Karstification (2D and 3D Approaches)

    DEFF Research Database (Denmark)

    Sadrekarimi, Jamshid; Kiyani, Majid; Fakhri, Behnam;

    2011-01-01

    Upper Gotvand Dam is constructed on the Karun River at the south west of Iran. In this paper, 2D and 3D models of the dam together with the foundation and abutments were established, and several seepage analyses were carried out. Then, the gypsum veins that are scattered throughout the foundation...... model locates the phreatic surface somewhat higher than the 2D model. This means that the 2D model estimates lower pore water pressure pattern in comparison with the 3D model. These may be attributed to the fact that with 2D model the lateral components of vectors of seepage velocity are ignored...... flux through the foundation ground....

  3. Prosthodontic maintenance requirements of implant-retained overdentures using the locator attachment system.

    Science.gov (United States)

    Vere, Joe; Hall, Derek; Patel, Raj; Wragg, Phillip

    2012-01-01

    The aim of this study was to investigate the prosthodontic maintenance requirements of patients rehabilitated with maxillary and mandibular implant-retained overdentures using the Locator Attachment System by retrospectively reviewing case records. Fifty patients made 112 unplanned return visits over a 3-year period. The most common reasons for returning were denture adjustments (n = 45), inadequate retention (n = 39), and loosening of the implant abutments (n = 14). Implant-retained overdentures using the Locator Attachment System have comparable prosthodontic maintenance requirements to other attachment systems. Problems associated with these prostheses are usually simple to resolve chairside.

  4. Implant success lies in complications management: A report of two cases

    Directory of Open Access Journals (Sweden)

    Sapna Rani

    2016-01-01

    Full Text Available At present, implant supported or retained prostheses are considered as a first therapeutic alternative for patients. Although the success rate of dental implants is very high, no treatment is without complications; same applies to implants also. Implant failure can be due to biological factors, i.e., loss of osseointegration or due to technical complications. This case report presents implant complications involving both factors along with the management of these cases. In implant supported overdenture patient, loss of implant on the right side and implant body fracture of the left side implant is reported and in another patient abutment screw fracture and its management is reported.

  5. Digitization of dental alginate impression: Three-dimensional evaluation of point cloud.

    Science.gov (United States)

    Kim, So-Ri; Lee, Wan-Sun; Kim, Woong-Chul; Kim, Hea-Young; Kim, Ji-Hwan

    2015-01-01

    The purpose of this study was to evaluate the digitization of alginate impressions by analyzing differences between the scan data of two types of impressions (alginate and rubber) taken from the master die and the scan data for the master die. The master die and impressions were digitized using a dental laser scanner (7 series, Dental Wings, Montreal, Canada). The crown portion of the abutment teeth in the digital data of 20 impressions was divided into three regions: cervical surface, middle surface, and occlusal surface. An independent t-test showed a significant difference (pdigitization of alginate impressions in the future. PMID:26632232

  6. Coherent processing for ISAR imaging with sparse apertures

    Institute of Scientific and Technical Information of China (English)

    SHENG JiaLian; ZHANG Lei; XU Gang; XING MengDao; BAO Zheng

    2012-01-01

    To implement target detection,tracking and imaging in a multifunctional radar system,the wideband measurements for inverse synthetic aperture radar (ISAR) imaging are usually sparsely recorded.Considering the incoherence problem in such sparse-aperture ISAR (SA-ISAR) systems,we concentrate on the study of a coherent processing method in this work.Based on an all-pole model,the incoherence parameters between abutting sub-apertures can be effectively estimated.After coherence compensation,an optimization-based SA-ISAR imaging approach is provided from the view of statistics.Simulation and real data experiments validate the feasibility and effectiveness of the proposals.

  7. Marginal and Internal Fit of Conventional Metal-Ceramic and Lithium Disilicate CAD/CAM Crowns.

    Science.gov (United States)

    Nam, Se-Jin; Yoon, Mi-Jung; Kim, Won-Hee; Ryu, Gil-Ju; Bang, Min-Ki; Huh, Jung-Bo

    2015-01-01

    This study aimed to evaluate and compare the marginal and internal gap widths of lithium disilicate computer-aided design / computer-assisted manufacture (LDC) crowns and conventionally produced porcelain-fused-to-metal (PFM) crowns. A convenience sample of 21 patients treated with a single restoration was selected. PFM and LDC crowns were fabricated for each selected abutment tooth, following traditional crown preparation. Silicone replicas were produced, and internal gaps and marginal gaps were measured. Internal gaps were significantly larger for the axial and occlusal surfaces of LDC crowns than for those of PFM crowns (P .05). Both LDC crowns and PFM crowns showed clinically acceptable marginal fit. PMID:26340013

  8. A device for removing gases during unloading of coke ovens

    Energy Technology Data Exchange (ETDEWEB)

    Yatsura, V.A.; Matsegora, N.T.; Mikhaylenko, V.Ya.; Nayman, A.M.; Stepko, G.V.

    1983-01-01

    In the device for outlet of gases during unloading of coking furnaces, which includes a dust trapping hood, a collector for outlet of the gases with valves, a gas collecting chamber with openings on the side wall, which is located above the collector and has drives for vertical movement of the collector channels and a connecting branch pipe, attached to the dust trapping hood, in order to increase the operational reliability, the gas collecting chamber is fixed above the collector and is equipped with vertical partitions which divide it into sections, whose number is equal to the number of furnaces being serviced, the connecting branch pipe is equipped with runners mounted on its exterior surface (Pv) and interacting with the side wall of the gas collection chamber and the connecting branch pipe is attached to the dust trapping hood by means of shock absorbers. The device provides for continuous abutment between the dust trapping hood and the gas collector, which makes it possible to perform dust trapping throughout the entire cycle of coal outlet, including the time for fulfillment of auxiliary operations. The device is operationally reliable, since the shifting of the hood and the unevennesses of the solid wall along which the abutting device moves are eliminated by the compensators, which prevents failures.

  9. [Attaching single- and multi-unit fixed dental prostheses].

    Science.gov (United States)

    Kreulen, C M; Wolke, J G C; de Baat, C; Creugers, N H J

    2013-11-01

    A single- or multi-unit fixed dental prosthesis can be attached to the abutment teeth through mechanical retention and gap sealing or by adhesion. For sealing the gap, water-soluble cements are appropriate, such as zinc phosphate, polycarboxylate, and (resin-modified) glasionomer cement. Attachment through adhesion can be performed with composite cement. If the hard tooth tissue is prepared adequately, composite cement provides sufficient adhesion, but self-adhesive composite cement is now also available. For the adhesion of the composite cement to the restorative materials of the single- or multi-unit fixed dental prosthesis, surface sandblasting, silanizing, and tin coating and the application of a metal primer or chemically active composite are available. Cementing a single- or multi-unit dental prosthesis involves 3 phases: 1. Cleansing the single- or multi-unit dental prosthesis and the abutment tooth/teeth; 2. Preparing the hard tooth tissue, mixing the cement and placing the single- or multi-unit dental prosthesis; 3. Removing the excess cement. PMID:24340689

  10. Load-application devices: a comparative strain gauge analysis.

    Science.gov (United States)

    Nishioka, Renato Sussumu; de Vasconcellos, Luis Gustavo Oliveira; Jóias, Renata Pilli; Rode, Sigmar de Mello

    2015-01-01

    In view of the low loading values commonly employed in dentistry, a load-application device (LAD) was developed as option to the universal testing machine (UTM), using strain gauge analysis. The aim of this study was to develop a load-application device (LAD) and compare the LAD with the UTM apparatus under axial and non-axial loads. An external hexagonal implant was inserted into a polyurethane block and one EsthetiCone abutment was connected to the implant. A plastic prosthetic cylinder was screwed onto the abutment and a conical pattern crown was fabricated using acrylic resin. An impression was made and ten identical standard acrylic resin patterns were obtained from the crown impression, which were cast in nickel-chromium alloy (n=10). Four strain gauges were bonded diametrically around the implant. The specimens were subjected to central (C) and lateral (L) axial loads of 30 kgf, on both devices: G1: LAD/C; G2: LAD/L; G3: UTM/C; G4: UTM/L. The data (με) were statistically analyzed by repeated measures ANOVA and Tukey's test (p<0.05). No statistically significant difference was found between the UTM and LAD devices, regardless of the type of load. It was concluded that the LAD is a reliable alternative, which induces microstrains to implants similar to those obtained with the UTM. PMID:26200149

  11. Stress Distribution in Single Dental Implant System: Three-Dimensional Finite Element Analysis Based on an In Vitro Experimental Model.

    Science.gov (United States)

    Rezende, Carlos Eduardo Edwards; Chase-Diaz, Melody; Costa, Max Doria; Albarracin, Max Laurent; Paschoeto, Gabriela; Sousa, Edson Antonio Capello; Rubo, José Henrique; Borges, Ana Flávia Sanches

    2015-10-01

    This study aimed to analyze the stress distribution in single implant system and to evaluate the compatibility of an in vitro model with finite element (FE) model. The in vitro model consisted of Brånemark implant; multiunit set abutment of 5 mm height; metal-ceramic screw-retained crown, and polyurethane simulating the bone. Deformations were recorded in the peri-implant region in the mesial and distal aspects, after an axial 300 N load application at the center of the occlusal aspect of the crown, using strain gauges. This in vitro model was scanned with micro CT to design a three-dimensional FE model and the strains in the peri-implant bone region were registered to check the compatibility between both models. The FE model was used to evaluate stress distribution in different parts of the system. The values obtained from the in vitro model (20-587 με) and the finite element analysis (81-588 με) showed agreement among them. The highest stresses because of axial and oblique load, respectively were 5.83 and 40 MPa for the cortical bone, 55 and 1200 MPa for the implant, and 80 and 470 MPa for the abutment screw. The FE method proved to be effective for evaluating the deformation around single implant. Oblique loads lead to higher stress concentrations. PMID:26192032

  12. Comparison of Conventional Methods and Laser-Assisted Rapid Prototyping for Manufacturing Fixed Dental Prostheses: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    Giorgio Pompa

    2015-01-01

    Full Text Available This study assessed whether there are differences in marginal fit between laser-fusion and conventional techniques to produce fixed dental prostheses (FDPs. A master steel die with 2 abutments was produced to receive a posterior 4-unit FDPs and single copings. These experimental models were divided into three groups (n=20/group manufactured: group 1, Ni-Cr alloy, with a lost-wax casting technique; group 2, Co-Cr alloy, with selective laser melting (SLM; and group 3, yttria-tetragonal zirconia polycrystal (Y-TZP, with a milling system. All specimens were cut along the longitudinal axis and their adaptation was measured at the marginal and shoulder areas on the right and left sides of each abutment. Measurements were made using a stereomicroscope (×60 magnification and a scanning electron microscope (×800 magnification. The data were analyzed using one-way analysis of variance and the Bonferroni post hoc test, with a significance cutoff of 5%. Significant differences (P<0.05 were observed between group 3 and the other groups. The marginal opening was smallest with Co-Cr alloy substructures, while the shoulder opening was smallest with Ni-Cr alloy substructures. Within the limitations of this study, the marginal fit of an FDP is better with rapid prototyping (RP via SLM than conventional manufacturing systems.

  13. Comparison of Conventional Methods and Laser-Assisted Rapid Prototyping for Manufacturing Fixed Dental Prostheses: An In Vitro Study.

    Science.gov (United States)

    Pompa, Giorgio; Di Carlo, Stefano; De Angelis, Francesca; Cristalli, Maria Paola; Annibali, Susanna

    2015-01-01

    This study assessed whether there are differences in marginal fit between laser-fusion and conventional techniques to produce fixed dental prostheses (FDPs). A master steel die with 2 abutments was produced to receive a posterior 4-unit FDPs and single copings. These experimental models were divided into three groups (n = 20/group) manufactured: group 1, Ni-Cr alloy, with a lost-wax casting technique; group 2, Co-Cr alloy, with selective laser melting (SLM); and group 3, yttria-tetragonal zirconia polycrystal (Y-TZP), with a milling system. All specimens were cut along the longitudinal axis and their adaptation was measured at the marginal and shoulder areas on the right and left sides of each abutment. Measurements were made using a stereomicroscope (×60 magnification) and a scanning electron microscope (×800 magnification). The data were analyzed using one-way analysis of variance and the Bonferroni post hoc test, with a significance cutoff of 5%. Significant differences (P < 0.05) were observed between group 3 and the other groups. The marginal opening was smallest with Co-Cr alloy substructures, while the shoulder opening was smallest with Ni-Cr alloy substructures. Within the limitations of this study, the marginal fit of an FDP is better with rapid prototyping (RP) via SLM than conventional manufacturing systems. PMID:26576419

  14. Strata behavior investigation for high-intensity mining in the water-rich coal seam

    Institute of Scientific and Technical Information of China (English)

    Ding Huande; Miao Xiexing; Ju Feng; Wang Xiulin; Wang Qingcang

    2014-01-01

    This paper describes a specific case of mining in a water-rich coal seam in western China. Water inrushes, roof caving and other disasters induced by intensive mining operation could pose great threats to the safety of coal mines. The strata behavior during the high-intensity extraction in the water-rich coal seam is analyzed by employing the numerical simulation method and in situ monitoring. The results show that about 10 m ahead of the workface, the front abutment pressure peaks is at 34.13 MPa, while the peak of the side abutment pressure is located about 8 m away from the gateway with the value of 12.41 MPa;the height of the fracture zone, the first weighting step and the cycle weighting step are calculated to be 45, 50 and 20.8 m, respectively; pressure distribution in the workface is characterized by that the vertical pressure in the center occurs earlier and is stronger than those on both ends. Then, the results above are verified by in situ measurement, which may provide a basis for safe mining under similar conditions.

  15. Dimensional Stability of Polyether, Alginate, and Silicone Impression Materials After Disinfection With 2% Sanosil Through the Immersion Technique

    Directory of Open Access Journals (Sweden)

    Izadi

    2014-10-01

    Full Text Available Background To prevent diseases transmission, infection control in dental offices without reducing the accuracy and dimensional stability of impression materials is very important. Objectives The aim of this study was to evaluate the effects of Sanosil disinfectants on the dimensional stability of some usual impression materials. Materials and Methods Three types of impression material, namely, alginate, condensational silicone, and polyether, were used in this study. Impressions were obtained from the master steel model. Fifteen impressions of each material (control group were immersed in water for ten minutes and impressions of study groups were disinfected by immersion in 2% Sanosil for ten minutes. Then impressions were poured by type III gypsum according to the manufacture's instruction. Dimensions of casts in the two anterior dimensions, i.e. interval between the anterior abutments and interval between anterior-posterior abutments, were recorded by a digital caliper with the accuracy of 0.01 mm. Data were analyzed with SPSS through two-way ANOVA test. Results The results showed that there was no significant difference in the mean dimension of casts prepared by different impression materials in anterior and anterior-posterior dimensions in comparison to the original model after disinfection with Sanosil. Conclusions The study revealed that disinfection with 2% Sanosil has no significant effect on casts dimensions of alginate, silicone, and polyether impression and dimensional stability is maintained.

  16. Influence of Implant Position on Stress Distribution in Implant-Assisted Distal Extension Removable Partial Dentures: A 3D Finite Element Analysis.

    Directory of Open Access Journals (Sweden)

    Yeganeh Memari

    2014-10-01

    Full Text Available Distal extension removable partial denture is a prosthesis with lack of distal dental support with a 13-fold difference in resiliency between the mucosa and the periodontal ligament, resulting in leverage during compression forces. It may be potentially destructive to the abutments and the surrounding tissues. The aim of this study was to assess the effect of implant location on stress distribution, in distal extension implant assisted removable partial dentures.Three-dimensional models of a bilateral distal extension partially edentulous mandible containing anterior teeth and first premolar in both sides of the arch, a partial removable denture and an implant (4×10mm were designed. With the aid of the finite element program ANSYS 8.0, the models were meshed and strictly vertical forces of 10 N were applied to each cusp tip. Displacement and von Mises Maps were plotted for visualization of results.When an implant was placed in the second premolar region, the highest stress on implant, abutment tooth and cancellous bone was shown. The lowest stress was shown on implant and bone in the 1(st molar area.Implants located in the first molar area showed the least distribution of stresses in the analyzed models.

  17. Establishment of Epithelial Attachment on Titanium Surface Coated with Platelet Activating Peptide

    Science.gov (United States)

    Sugawara, Shiho; Maeno, Masahiko; Lee, Cliff; Nagai, Shigemi; Kim, David M.; Da Silva, John; Kondo, Hisatomo

    2016-01-01

    The aim of this study was to produce epithelial attachment on a typical implant abutment surface of smooth titanium. A challenging complication that hinders the success of dental implants is peri-implantitis. A common cause of peri-implantitis may results from the lack of epithelial sealing at the peri-implant collar. Histologically, epithelial sealing is recognized as the attachment of the basement membrane (BM). BM-attachment is promoted by activated platelet aggregates at surgical wound sites. On the other hand, platelets did not aggregate on smooth titanium, the surface typical of the implant abutment. We then hypothesized that epithelial BM-attachment was produced when titanium surface was modified to allow platelet aggregation. Titanium surfaces were coated with a protease activated receptor 4-activating peptide (PAR4-AP). PAR4-AP coating yielded rapid aggregation of platelets on the titanium surface. Platelet aggregates released robust amount of epithelial chemoattractants (IGF-I, TGF-β) and growth factors (EGF, VEGF) on the titanium surface. Human gingival epithelial cells, when they were co-cultured on the platelet aggregates, successfully attached to the PAR4-AP coated titanium surface with spread laminin5 positive BM and consecutive staining of the epithelial tight junction component ZO1, indicating the formation of complete epithelial sheet. These in-vitro results indicate the establishment of epithelial BM-attachment to the titanium surface. PMID:27741287

  18. A 10-Year Clinical Evaluation of Resin-Bonded Fixed Dental Prostheses on Non-Prepared Teeth.

    Science.gov (United States)

    Piemjai, Morakot; Özcan, Mutlu; Garcia-Godoy, Franklin; Nakabayashi, Nobuo

    2016-06-01

    This study evaluated the conditions of the non-invasive resin-bonded fixed dental prostheses (FDP) and patient satisfaction up to 10 years of clinical function. A total of 23 patients who required fixed prostheses in the areas of mandibular anterior and premolar, and maxillary anterior region received resin-bonded restorations between 1999-2003. In 13 patients with 14 edentulous areas were restored with an adhesive pontic (natural tooth, acrylic and porcelain). Two indirect proximal veneers using resin composite were placed in each space in 10 patients having 13 edentulous spaces. All prostheses were bonded to the proximal surface of adjacent teeth using resin cement based on 4-META/MMA-TBB. No debonding of proximal veneers but 4 pontic debonding was observed which were rebonded and remained functional until final follow up. The abutments in pontic and proximal veneer groups were free of caries and hypersensitivity. Periodontal health was improved after treatment and was maintained for 10 years except for 4 abutments that still showed some bleeding on probing. Non-invasive resin-bonded FDPs are simple, pain-free, less costly treatment procedures that could provide acceptable clinical longevity with high patient satisfaction. PMID:27424337

  19. End plug for fuel rod and welding method therefor

    International Nuclear Information System (INIS)

    An end plug of a fuel rod comprises a pressure-insertion portion having a diameter somewhat greater than the inner diameter of a fuel cladding tube and a welding portion having a diameter substantially the same as the outer diameter of the cladding tube. A V-shaped recess having an outer diameter smaller than the greatest outer diameter of the pressure-insertion portion is formed over the entire circumferential surface of the outer circumference of the connection portion of the pressure-insertion portion and the welding portion. The pressure-insertion portion of the end plug is inserted to the end of the cladding tube till the end of the cladding tube abuts against the inclined surface of the V-shaped recess. The abutting surfaces of the end plug and the cladding tube are subjected to resistance welding in this state. The inner portion bulged from the inclined surface of the V-shaped recess is filled in the recess in a molten state. Lowering of temperature of the cladding tube in the vicinity of the welded portion is decreased by γ heat during reactor operation. Accordingly, lowering of ductility of the cladding tube and degradation of material of the welded region due to segregation of hydrogen in the cladding tube can be suppressed. (I.N.)

  20. Deformation Monitoring of Geomechanical Model Test and Its Application in Overall Stability Analysis of a High Arch Dam

    Directory of Open Access Journals (Sweden)

    Baoquan Yang

    2015-01-01

    Full Text Available Geomechanical model testing is an important method for studying the overall stability of high arch dams. The main task of a geomechanical model test is deformation monitoring. Currently, many types of deformation instruments are used for deformation monitoring of dam models, which provide valuable information on the deformation characteristics of the prototype dams. However, further investigation is required for assessing the overall stability of high arch dams through analyzing deformation monitoring data. First, a relationship for assessing the stability of dams is established based on the comprehensive model test method. Second, a stability evaluation system is presented based on the deformation monitoring data, together with the relationships between the deformation and overloading coefficient. Finally, the comprehensive model test method is applied to study the overall stability of the Jinping-I high arch dam. A three-dimensional destructive test of the geomechanical model dam is conducted under reinforced foundation conditions. The deformation characteristics and failure mechanisms of the dam abutments and foundation were investigated. The test results indicate that the stability safety factors of the dam abutments and foundation range from 5.2 to 6.0. These research results provide an important scientific insight into the design, construction, and operation stages of this project.

  1. Improved design of long-span resin-bonded fixed partial dentures: three case reports.

    Science.gov (United States)

    Botelho, Michael G

    2003-03-01

    When single-tooth implants are not appropriate, the use of resin-bonded fixed partial dentures is a preferred treatment option when the abutments are relatively sound. However, the use of resin-bonded fixed partial dentures (RBFPDs) for replacing two or more missing teeth is considered to have a guarded prognosis, as long-span RBFPDs have been shown to be less successful than single pontic prostheses. The use of properly modified nonrigid connectors may well improve the success of long-span RBFPDs by reducing harmful interabutment stresses that appear to be responsible for retainer debonding in long-span RBFPDs. For such long-span prostheses, it is advised that the major retainer have wraparound on at least three surfaces of the abutment or have strategically placed opposing axial grooves or slots. It is considered essential that the connector allow interabutment movement in both the horizontal and vertical planes so that the retainer with the greater resistance and retention form does not stress and possibly debond the minor retainer. The upside-down positioning of the nonrigid connector and the matrix incorporated with the major retainer is considered important for successful maintenance, if a debond should occur due to greater loading on the major retainer, because it can be removed and recemented easily. Clinical cases are described that replace two or more missing teeth using fixed-movable RBFPDs with nonrigid connectors. PMID:12731596

  2. Biological Width around One- and Two-Piece Implants Retrieved from Human Jaws

    Directory of Open Access Journals (Sweden)

    Ricardo Judgar

    2014-01-01

    Full Text Available Several histologic studies regarding peri-implant soft tissues and biological width around dental implants have been done in animals. However, these findings in human peri-implant soft tissues are very scarce. Therefore, the aim of this case series was to compare the biological width around unloaded one- and two-piece implants retrieved from human jaws. Eight partially edentulous patients received 2 test implants in the posterior mandible: one-piece (solid implants that comprise implant and abutment in one piece and two-piece (external hexagon with a healing abutment implants. After 4 months of healing, the implants and surrounding tissue were removed for histologic analysis. The retrieved implants showed healthy peri-implant bone and exhibited early stages of maturation. Marginal bone loss, gaps, and fibrous tissue were not present around retrieved specimens. The biologic width dimension ranged between 2.55 ± 0.16 and 3.26 ± 0.15 to one- and two-piece implants, respectively (P0.05. Within the limits of this study, it could be shown that two-piece implants resulted in the thickening of the connective tissue attachment, resulting in the increase of the biological width, when compared to one-piece implants.

  3. Laser Welded versus Resistance Spot Welded Bone Implants: Analysis of the Thermal Increase and Strength

    Directory of Open Access Journals (Sweden)

    Carlo Fornaini

    2014-01-01

    Full Text Available Introduction. The first aim of this “ex vivo split mouth” study was to compare the thermal elevation during the welding process of titanium bars to titanium implants inserted in pig jaws by a thermal camera and two thermocouples. The second aim was to compare the strength of the joints by a traction test with a dynamometer. Materials and Methods. Six pigs’ jaws were used and three implants were placed on each side of them for a total of 36 fixtures. Twelve bars were connected to the abutments (each bar on three implants by using, on one side, laser welding and, on the other, resistance spot welding. Temperature variations were recorded by thermocouples and by thermal camera while the strength of the welded joint was analyzed by a traction test. Results. For increasing temperature, means were 36.83 and 37.06, standard deviations 1.234 and 1.187, and P value 0.5763 (not significant. For traction test, means were 195.5 and 159.4, standard deviations 2.00 and 2.254, and P value 0.0001 (very significant. Conclusion. Laser welding was demonstrated to be able to connect titanium implant abutments without the risk of thermal increase into the bone and with good results in terms of mechanical strength.

  4. Mining pressure monitoring and analysis in fully mechanized backfilling coal mining face-A case study in Zhai Zhen Coal Mine

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qiang; ZHANG Ji-xiong; KANG Tao; SUN Qiang; LI Wei-kang

    2015-01-01

    Fully mechanized solid backfill mining (FMSBM) technology adopts dense backfill body to support the roof. Based on the distinguishing characteristics and mine pressure control principle in this technology, the basic principles and methods for mining pressure monitoring were analyzed and established. And the characteristics of overburden strata movement were analyzed by monitoring the support resistance of hydraulic support, the dynamic subsidence of immediate roof, the stress of backfill body, the front abutment pressure, and the mass ratio of cut coal to backfilled materials. On-site strata behavior measurements of 7403W solid backfilling working face in Zhai Zhen Coal Mine show that the backfill body can effectively support the overburden load, obviously control the overburden strata movement, and weaken the strata behaviors distinctly. Specific performances are as follows. The support resistance decreases obviously; the dynamic subsidence of immediate roof keeps consistent to the variation of backfill body stress, and tends to be stable after the face retreating to 120-150 m away from the cut. The peak value of front abutment pressure arises at 5-12 m before the operating face, and mass ratio is greater than the designed value of 1.15, which effectively ensures the control of strata movement. The research results are bases for intensively studying basic theories of solid backfill mining strata behaviors and its control, and provide theoretical guidance for engineering design in FMSBM.

  5. Application of the 2-piece orthodontic C-implant for provisional restoration with laser welded customized coping: a case report.

    Science.gov (United States)

    Paek, Janghyun; Ahn, Hyo-Won; Jeong, Do-Min; Shim, Jeong-Seok; Kim, Seong-Hun; Chung, Kyu-Rhim

    2015-01-01

    This article presents the application of laser welding technique to fabricate an orthodontic mini-implant provisional restoration in missing area after limited orthodontic treatment. A 15-year-old boy case is presented. Two-piece orthodontic C-implant was placed after regaining space for missing right mandibular central incisor. Due to angular deviation of implant, customized abutment was required. Ready-made head part was milled and lingual part of customized abutment was made with non-precious metal. Two parts then were laser welded (Master 1000, Elettrolaser Italy, Verona, Italy) and indirect lab composite (3 M ESPE Sinfony, St. Paul, MN, USA) was built up. The patient had successful result, confirmed by clinical and radiographic examinations. Before the patient is ready to get a permanent restoration later on, this provisional restoration will be used. This case shows that a two-piece orthodontic C-implant system can be used to maintain small edentulous space after orthodontic treatment. PMID:25885663

  6. Influence of rectification procedure on the counter-torque force of prosthetic screws of implant-retained frameworks

    Directory of Open Access Journals (Sweden)

    Mauro Antonio de Arruda Nobilo

    2008-01-01

    Full Text Available Objective: To evaluate the counter-force of prosthetic screws before and after the rectification procedure of the seating base of prosthetic framework screws. Methods: With a metal matrix containing three replicas of conical abutments (Micro-Unit; Conexão placed at 10 mm from center to center, ten multiple cast structures were made of a titanium monoblock. The multiple cast structures were fastened onto the metal matrix abutments with a torque of 10 NCm. The screwing sequence was performed from the central pillar towards the distal ones. The force (Ncmnecessary for counter-torque was evaluated using a digital torque meter (TQ3000; Lutron, Taipei, Taiwan. This procedure was carried out before and after rectification of the seating base of the prosthetic screws, by means of a manual rectifier tip (Conexão Sistemas de Prótese, São Paulo, Brazil. The mean counter-torque values were calculated for each structure before and after rectification. The t-Test for paired samples was used to compare the evaluated situations. Results: Significant difference was observed between the mean counter-torque force value of the prosthetic screws before (5.78±1.03Ncm and after (7.06±0.62Ncm the rectification procedures (p<0.01. Conclusion: The rectifying process of the seating base significantly increased the values of force required to counter-torque the prosthetic screws of cast implant-retained multiple frameworks.

  7. Effect of the Crystallization Process on the Marginal and Internal Gaps of Lithium Disilicate CAD/CAM Crowns

    Directory of Open Access Journals (Sweden)

    Jae-Hong Kim

    2016-01-01

    Full Text Available The aim of this study is to quantify the effect of the crystallization process on lithium disilicate ceramic crowns fabricated using a computer-aided design/computer-aided manufacturing (CAD/CAM system and to determine whether the effect of crystallization is clinically acceptable by comparing values of fit before and after the crystallization process. The mandibular right first molar was selected as the abutment for the experiments. Fifteen working models were prepared. Lithium disilicate crowns appropriate for each abutment were prepared using a commercial CAD/CAM system. Gaps in the marginal area and 4 internal areas of each crown were measured twice—before and after crystallization—using the silicone replica technique. The mean values of fit before and after crystallization were analyzed using a paired t-test to examine whether the conversion that occurred during crystallization affected marginal and internal gaps (α=0.05. Gaps increased in the marginal area and decreased in the internal areas after crystallization. There were statistically significant differences in all of the investigated areas (P<0.05. None of the values for marginal and internal fit of lithium disilicate CAD/CAM crowns after crystallization exceeded 120 μm, which is the clinically acceptable threshold.

  8. Effect of the Crystallization Process on the Marginal and Internal Gaps of Lithium Disilicate CAD/CAM Crowns.

    Science.gov (United States)

    Kim, Jae-Hong; Oh, Seunghan; Uhm, Soo-Hyuk

    2016-01-01

    The aim of this study is to quantify the effect of the crystallization process on lithium disilicate ceramic crowns fabricated using a computer-aided design/computer-aided manufacturing (CAD/CAM) system and to determine whether the effect of crystallization is clinically acceptable by comparing values of fit before and after the crystallization process. The mandibular right first molar was selected as the abutment for the experiments. Fifteen working models were prepared. Lithium disilicate crowns appropriate for each abutment were prepared using a commercial CAD/CAM system. Gaps in the marginal area and 4 internal areas of each crown were measured twice-before and after crystallization-using the silicone replica technique. The mean values of fit before and after crystallization were analyzed using a paired t-test to examine whether the conversion that occurred during crystallization affected marginal and internal gaps (α = 0.05). Gaps increased in the marginal area and decreased in the internal areas after crystallization. There were statistically significant differences in all of the investigated areas (P < 0.05). None of the values for marginal and internal fit of lithium disilicate CAD/CAM crowns after crystallization exceeded 120 μm, which is the clinically acceptable threshold. PMID:27123453

  9. Assessment of convergence angle of full veneer preparations carried out by practitioners with different levels of experience

    International Nuclear Information System (INIS)

    To investigate the convergence angle (CA) of dies achieved by clinicians with different levels of experience and to study the effect of the number and location of abutments on the CA. Two hundred and ninety one dies were obtained and mounted with the occlusal plane of the prepared teeth parallel to the floor. Photographs of facial and proximal aspects were taken for each die. The photographs were transferred into a personal computer and an AutoCAD software program was used to measure the bucco-lingual and mesio-distal CA of each preparation. Analysis of Variance (ANOVA) was used to test the significance at 95% confidence level. The greatest mean CA was in the teeth prepared by general practitioners (25.7degree) while the smallest was in teeth prepared by prosthodontists (16.9 degree). Statistically significant difference was found among CA values of the three groups (P<.0001). Statistical significant difference was also found between the CA of the preparation for single crown and for fixed partial denture abutments. No statistically significant differences were found between the CA of the anterior and posterior tooth preparations. The prosthodontists produced a lower convergence angle of prepared teeth compared to students and general practitioners. There is a need for all groups to exert extra effort to reduce the CA during tooth preparation. The recommended 6 degree taper is difficult to be achieved clinically (author)

  10. Osseointegration of dental implants in patients with and without radiotherapy

    International Nuclear Information System (INIS)

    Between 1987 and 1997, 275 dental implants were inserted in the mandibles of 63 patients with squamous cell carcinoma of the lower oropharyngeal level following a radical surgical procedure. Thirty-five of these patients had been preirradiated with a complete dose of 60 Gy. In a retrospective analysis we have reviewed the data of these patients for age, sex, localization of the implants, irradiation, interval of implantation and interval of the abutment operation. Thus far, the median follow-up time is 65 months. The 5-year success rate for all implants was 97.9%. We found that radiotherapy, age, sex, localization of implantation or the interval between the end of the tumor therapy and the time of implantation did not have any significant influence on osseointegration or loss of osseointegration. Only the time interval between implantation and the abutment operation was recorded to be of any great significance (p=0.0001). No augmentation in the osteoradionecrosis rate could be recorded after dental implantation (1.6%), which leads us to conclude that radiotherapy (60 Gy) in patients with head and neck cancers should not be regarded as a contraindication for dental implantation. (orig.)

  11. Combustor bulkhead heat shield assembly

    Energy Technology Data Exchange (ETDEWEB)

    Zeisser, M.H.

    1990-06-19

    This paper describes a gas turbine engine having an annular combustion chamber defined by an annular, inner liner, a concentric outer liner, and an upstream annular combustor head, wherein the head includes a radially extending bulkhead having circumferentially distributed openings for each receiving an individual fuel nozzle therethrough. It comprises: a segmented heat shield assembly, disposed between the combustion chamber interior and the bulkhead, including generally planar, sector shaped heat shields, each shield abutting circumferentially with two next adjacent shields and extending radially from proximate the inner liner to proximate the outer liner, the plurality of shields collectively defining an annular protective barrier, and wherein each sector shaped shield further includes an opening, corresponding to one of the bulkhead nozzle openings for likewise receiving the corresponding nozzle therethrough, the shield opening further including an annular lip extending toward the bulkhead and being received within the bulkhead opening, raised ridges on the shield backside, the ridges contacting the facing bulkhead surface and defining a flow path for a flow of cooling air issuing from a sized supply opening disposed in the bulkhead, the flow path running ultimately from adjacent the annular lip to the edges of each shield segment, wherein the raised edges extend fully along the lateral, circumferentially spaced edges of each shield segment and about the adjacent shield segments wherein the raised ridges further extend circumferentially between the annular lip and the abutting edge ridges.

  12. Level II scour analysis for Bridge 32 (TUNBTH00600032) on Town Highway 60, crossing First Branch White River, Tunbridge, Vermont

    Science.gov (United States)

    Wild, Emily C.

    1998-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure TUNBTH00600032 on Town Highway 60 crossing the First Branch White River, Tunbridge, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in appendix D. The site is in the New England Upland section of the New England physiographic province in central Vermont. The 92.9-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture upstream and downstream of the bridge, while woody vegetation sparsely covers the immediate banks. In the study area, the First Branch White River has a sinuous channel with a slope of approximately 0.001 ft/ft, an average channel top width of 82 ft and an average bank height of 7 ft. The channel bed material ranges from sand to gravel with a median grain size (D50) of 24.4 mm (0.08 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 18, 1995, indicated that the reach was laterally unstable, as a result of block failure of moderately eroded banks. The Town Highway 60 crossing of the First Branch White River is a 74-ft-long, one-lane bridge consisting of a 71-foot timber thru-truss span (Vermont Agency of Transportation, written communication, August 24, 1994). The opening length of the structure parallel to the bridge face is 64 ft.The bridge is supported by vertical, laid-up stone abutments with upstream wingwalls. The channel is not skewed to the opening

  13. Level II scour analysis for Bridge 44 (LINCTH00330044) on Town Highway 33, crossing the New Haven River, Lincoln, Vermont

    Science.gov (United States)

    Burns, Ronda L.; Wild, Emily C.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure LINCTH00330044 on Town Highway 33 crossing the New Haven River, Lincoln, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D.The site is in the Green Mountain section of the New England physiographic province in west-central Vermont. The 6.3-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest.In the study area, the New Haven River has an incised, sinuous channel with a slope of approximately 0.02 ft/ft, an average channel top width of 56 ft and an average bank height of 6 ft. The channel bed material ranges from gravel to boulder with a median grain size (D50) of 101.9 mm (0.334 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 10, 1996, indicated that the reach was stable.The Town Highway 33 crossing of the New Haven River is a 33-ft-long, one-lane bridge consisting of one 31-foot timber-beam span (Vermont Agency of Transportation, written communication, December 14, 1995). The opening length of the structure parallel to the bridge face is 29.3 ft. The bridge is supported by vertical, wood-beam crib abutments with wingwalls. The channel is skewed approximately 25 degrees to the opening while the opening-skew-to-roadway is zero degrees.A scour hole 1.0 ft deeper than the mean thalweg depth was observed along the right abutment during the Level I assessment. The

  14. Environmentally Friendly Solution to Ground Hazards in Design of Bridges in Earthquake Prone Areas Using Timber Piles

    Science.gov (United States)

    Sadeghi, H.

    2015-12-01

    Bridges are major elements of infrastructure in all societies. Their safety and continued serviceability guaranties the transportation and emergency access in urban and rural areas. However, these important structures are subject to earthquake induced damages in structure and foundations. The basic approach to the proper support of foundations are a) distribution of imposed loads to foundation in a way they can resist those loads without excessive settlement and failure; b) modification of foundation ground with various available methods; and c) combination of "a" and "b". The engineers has to face the task of designing the foundations meeting all safely and serviceability criteria but sometimes when there are numerous environmental and financial constrains, the use of some traditional methods become inevitable. This paper explains the application of timber piles to improve ground resistance to liquefaction and to secure the abutments of short to medium length bridges in an earthquake/liquefaction prone area in Bohol Island, Philippines. The limitations of using the common ground improvement methods (i.e., injection, dynamic compaction) because of either environmental or financial concerns along with the abundance of timber in the area made the engineers to use a network of timber piles behind the backwalls of the bridge abutments. The suggested timber pile network is simulated by numerical methods and its safety is examined. The results show that the compaction caused by driving of the piles and bearing capacity provided by timbers reduce the settlement and lateral movements due to service and earthquake induced loads.

  15. Effects of Live Load on Seismic Response of Bridges: A Preliminary Study

    Directory of Open Access Journals (Sweden)

    Sanders D.H.

    2012-01-01

    Full Text Available Although live load is well known to have a dynamic effect on bridge response in addition to its self-weight, the significance of these effects on seismic response is unclear. In addition, most bridge design specifications have few requirements concerning the inclusion of live load in their seismic design provisions. The main objective of this study is therefore to investigate and obtain insight into the effect of vehicle-bridge interaction during earthquake shaking. The study consists of both experimental and analytical investigations. This paper focuses on the experimental work, which includes shake table testing of a 2/5-scale model of a horizontally curved steel girder bridge loaded with a series of representative vehicles. Preliminary experimental results show that the presence of the live load had a clear beneficial effect on performance for small amplitude motions, but that this improvement diminished with increasing amplitude of shaking. Parameters used to measure performance include column displacements, abutment shear forces, abutment uplift, and concrete spalling.

  16. Level II scour analysis for Bridge 34 (HUNTTH00210034) on Town Highway 21, crossing Brush Brook, Huntington, Vermont

    Science.gov (United States)

    Burns, Ronda L.; Ivanoff, Michael A.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure HUNTTH00210034 on Town Highway 21 crossing Brush Brook, Huntington, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in central Vermont. The 6.23-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest. In the study area, Brush Brook has an incised, straight channel with a slope of approximately 0.03 ft/ft, an average channel top width of 43 ft and an average bank height of 4 ft. The channel bed material ranges from gravel to boulder with a median grain size (D50) of 90.0 mm (0.295 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 26, 1996, indicated that the reach was stable. The Town Highway 21 crossing of Brush Brook is a 28-ft-long, one-lane bridge consisting of one 26-foot steel-beam span with a timber deck (Vermont Agency of Transportation, written communication November 30, 1995). The opening length of the structure parallel to the bridge face is 25.4 ft. The bridge is supported by vertical, concrete abutments with a wingwall on the upstream right. The channel is skewed approximately 5 degrees to the opening and the computed opening-skew-to-roadway is 5 degrees. A tributary enters Brush Brook on the right bank immediately downstream of the bridge. At the confluence, the

  17. Level II scour analysis for Bridge 31 (HUNTTH00220031) on Town Highway 22, crossing Brush Brook, Huntington, Vermont

    Science.gov (United States)

    Flynn, Robert H.; Degnan, James R.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure HUNTTH00220031 on Town Highway 22 crossing Brush Brook, Huntington, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, obtained from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in west-central Vermont. The 5.01-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover consists of trees and brush. In the study area, Brush Brook has an incised, straight channel with a slope of approximately 0.06 ft/ft, an average channel top width of 44 ft and an average bank height of 4 ft. The channel bed material ranges from boulder to gravel with a median grain size (D50) of 107.0 mm (0.352 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 25, 1996, indicated that the reach was stable. The Town Highway 22 crossing of Brush Brook is a 34-ft-long, one-lane bridge consisting of one 30-foot steel I-beam span (Vermont Agency of Transportation, written communication, November 30, 1995). The opening length of the structure parallel to the bridge face is 31.2 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 15 degrees to the opening while the computed opening-skew-to-roadway is 10 degrees. The VTAOT computed opening-skewto-roadway is 2 degrees. A scour hole 1.0 ft deeper than the mean thalweg depth was

  18. Putty Index: An Important Aid for the Direct Fabrication of Fiber Reinforced Composite Resin FPD.

    Science.gov (United States)

    Gupta, Nidhi; Singh, Kunwarjeet

    2014-12-01

    Fiber reinforced composite resin fixed partial dentures (FRCFPD) with composite resin, PFM or all ceramic pontic can be used as a short term or long term alternative to conventional fixed partial dentures or implant supported crown in young patients where conventional FPD is contraindicated (large pulp chambers) or in patient's unwilling to invasive implant placement surgical procedure and those who do not want to allow preparation of natural sound abutments for placement of retainers for FPD. FRCFPD can be successfully used for replacing missing anterior tooth (Turker and Sener, J Prosthet Dent 100:254-258, 2008), in conditions which allows minimum occlusal loading of pontic, over jet and overbite not greater than 3 mm (Ricketts, Provocations and perceptions in craniofacial orthopedics: dental science and facial art/parts 1 and 2. Rocky Mountain Orthodontics, Denver, p 7023, 1990) and structurally sound and intact abutments for the fiber reinforced matrix (Rose et al., Quintessence Int 33:579-583, 2002). The successful esthetic and functional rehabilitation of missing tooth with fiber reinforced composite resin FPD depends on accurate positioning of pontic in patient's mouth. It is difficult to hold the pontic in proper position with instrument or fingers while direct fabrication in mouth. For accurate positioning, stabilization of pontic is very important which can be achieved with putty index. Putty index maintain pontic in accurate mesiodistal, labiolingual and cervicoincisal position while fabricating FRCFPD directly. PMID:26199513

  19. PRECISION ATTACHMENTS; APPLICATIONS AND LIMITATIONS

    Directory of Open Access Journals (Sweden)

    Prabhakar

    2012-12-01

    Full Text Available ABSTRACT: A unique concern of a removable denture when compare d to others is retention. Retention is the ability of the prosthesis to resist the movement of denture away from the supporting tissues/teeth. The component of removable d enture which provides retention is called as direct retainer. 1,3,4 A direct retainer can be either an extracoronal or intracoronal retainer. Extracoronal direct retainer uses mechanical resistance to displa cement through components placed on external surface of abutment teeth. Intracoronal retainer is either cast or attached to tally within the restored natural contours of an abutment tooth. 1 One of the main drawbacks of extracoronal retainers used in partial dentures is visibility. Many patients find themselves in an aest hetically compromised state when these retainers are placed on teeth in visible area. Preci sion attachments provide solution for this problem. Also, precision attachments provide better ve rtical support and better stimulation to the underlying tissue through intermittent vertical massage. 1,9 Although the history of intracoronal retainers goes back to 5 th and 4 th centuries BC, technically more sound developments began in early 2 0 th century AD, with Dr. Herman E. S. Chayes formulating the principle of internal attachme nt in 1906. Since then precision attachments are playing an important role in removabl e and fixed partial denture, conventional and implant supported overdenture. 9

  20. Novel Techniques with the Aid of a Staged CBCT Guided Surgical Protocol

    Directory of Open Access Journals (Sweden)

    Evdokia Chasioti

    2015-01-01

    Full Text Available The case report will present some novel techniques for using a “staged” protocol utilizing strategic periodontally involved teeth as transitional abutments in combination with CBCT guided implant surgery. Staging the case prevented premature loading of the grafted sites during the healing phase. A CBCT following a tenting screw guided bone regeneration procedure ensured adequate bone to place an implant fixture. Proper assessment of the CBCT allowed the surgeon to do an osteotome internal sinus lift in an optimum location. The depth of the bone needed for the osteotome sinus floor elevation was planned. The staged appliance allowed these sinus-augmented sites to heal for an extended period of time compared to implants, which were uncovered and loaded at an earlier time frame. The staged protocol and CBCT analysis enabled the immediate implants to be placed in proper alignment to the adjacent fixture. After teeth were extracted, the osseointegrated implants were converted to abutments for the transitional appliance. Finally, the staged protocol allowed for soft tissue enhancement in the implant and pontic areas prior to final insertion of the prosthesis.

  1. Characteristics of pulmonary cysts in Birt-Hogg-Dube syndrome: Thin-section CT findings of the chest in 12 patients

    Energy Technology Data Exchange (ETDEWEB)

    Tobino, Kazunori, E-mail: tobino@juntendo.ac.jp [Department of Respiratory Medicine, Juntendo University, School of Medicine, 2-1-1 Hongo, Bunkyo-Ku, Tokyo 113-8421 (Japan); Gunji, Yoko [Department of Respiratory Medicine, Juntendo University, School of Medicine, 2-1-1 Hongo, Bunkyo-Ku, Tokyo 113-8421 (Japan); Kurihara, Masatoshi [Pneumothorax Center, Nissan Tamagawa Hospital, 4-8-1 Seta, Setagaya-Ku, Tokyo 158-0095 (Japan); The Study Group of Pneumothorax and Cystic Lung Diseases, 4-8-1 Seta, Setagaya-Ku, Tokyo 158-0095 (Japan); Kunogi, Makiko; Koike, Kengo [Department of Respiratory Medicine, Juntendo University, School of Medicine, 2-1-1 Hongo, Bunkyo-Ku, Tokyo 113-8421 (Japan); Tomiyama, Noriyuki [Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871 (Japan); Johkoh, Takeshi [Department of Radiology, Kinki Central Hospital of Mutual Aid Association of Public School Teachers, Kurumazuka 3-1, Itami, Hyogo 664-0872 (Japan); Kodama, Yuzo [Department of Respiratory Medicine, Juntendo University, School of Medicine, 2-1-1 Hongo, Bunkyo-Ku, Tokyo 113-8421 (Japan); Iwakami, Shin-ichiro [Department of Respiratory Medicine, Juntendo University, Shizuoka Hospital, 1129 Nagaoka, Izunokuni, Shizuoka 410-2295 (Japan); Kikkawa, Mika [Biochemical Research Center, Division of Proteomics and Biomolecular Sciences, Juntendo University, Graduate School of Medicine, Bunkyo-Ku, Tokyo (Japan); Takahashi, Kazuhisa [Department of Respiratory Medicine, Juntendo University, School of Medicine, 2-1-1 Hongo, Bunkyo-Ku, Tokyo 113-8421 (Japan); Seyama, Kuniaki [Department of Respiratory Medicine, Juntendo University, School of Medicine, 2-1-1 Hongo, Bunkyo-Ku, Tokyo 113-8421 (Japan); Study Group of Pneumothorax and Cystic Lung Diseases, 4-8-1 Seta, Setagaya-Ku, Tokyo 158-0095 (Japan)

    2011-03-15

    Purpose: To describe in detail the characteristic chest computed tomography (CT) findings of Birt-Hogg-Dube (BHD) syndrome. Materials and methods: Thin-section chest CT scans of consecutive 12 patients with genetically diagnosed BHD syndrome were retrospectively evaluated by two observers, especially about the characteristics (distribution, number, size, shape and relation to pleura) of pulmonary cysts. Interobserver agreement in the identification of abnormalities on the CT images was achieved using the {kappa} statistic, and the degree of interobserver correlation for the characterization of pulmonary cysts was assessed using the Spearman rank correlation coefficient. Results: Multiple pulmonary cysts were seen in all patients. The number of cysts in each patient was various (range, 29-407), and cysts of various sizes (from a few mm to 2 cm or more) were seen in all patient. 76.6% (mean) of cysts were irregular-shaped, and 40.5% (mean) of cysts were located along the pleura. The mean extent score of cysts was 13% of the whole lung, and the distribution of cysts was predominantly in the lower medial zone. Finally, cysts abutting or including the proximal portions of lower pulmonary arteries or veins were also seen in all patients. Conclusion: Multiple, irregular-shaped cysts of various sizes with lower medial lung zone predominance are characteristic CT findings of BHD syndrome. Cysts abutting or including the proximal portions of lower pulmonary arteries or veins may also exist in this syndrome in a high probability.

  2. Development and utilization of a mechanical barrier for large-calibre cavern necks. The ''Spider Plug''; Entwicklung und Einsatz einer mechanischen Absperrung fuer grosskalibrige Kavernenhaelse. Der ''Spider Plug''

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifer, K.; Maut, D. [UGS GmbH, Mittenwalde (Germany)

    2013-08-01

    An hydraulic separation of a well and the cavern can be necessary for different workover applications, e.g. casing milling or underreaming. The separation is needed to ensure a mud circulation during such operations. In that case a barrier is set after flooding the cavern, which will then be used as a mechanical abutment for the cement bridge. If the diameter of the cavern neck has been enlarged due to e.g. unwanted leaching processes or unstabilized underreaming processes, it might get impossible to set a standard plug with the available technologies into those diameters. Therefore UGS GmbH has developed a mechanical plug, which is set hydraulically. The so called 'Spider Plug' is used as basis for a cement bridge and can be removed by drilling after the workover has been done. Depending on the dimension of the setting tool a cavern neck up to 50'' diameter can be plugged by the 'Spider Plug'. Up to now a number of successful operations on different locations has shown, that the 'Spider Plug' is a practicable and cost-efficient solution for a mechanical abutment of large cavern necks. (orig.)

  3. Detailed design of neutron guide tubes at the upgraded JRR-3, (3)

    International Nuclear Information System (INIS)

    JRR-3, currently a heavy water moderated and cooled 10 MW reactor, is to be upgraded to a light water moderated and cooled, heavy water reflected 20 MW reactor. Two guide tubes for thermal neutron and three for cold will be installed in the reactor to transport thermal and cold neutrons from the reactor hall to the experiment hall. This reports the basic design data of the guide tubes and the sensitivity analyses of transmission on the parameters such as, size of tube, nickel layer thickness and reflectivity. The NEUGT program was developed to calculate the guide tube transmission. The design assessment showed in the case of no abutment error that the T1 guide tube for thermal neutron, the C1 guide tube for cold and the C3 guide tube for cold are expected to have a transmission of 78 % (for 3A neutron) 69 % (for 5A neutron) and 62 % (for 7A neutron), respectively. The analyses also showed the effect of abutment error on transmission and the spectra and the angular distribution at the exit of the guide tubes. (author)

  4. Influence of Lithological Characters of Coal Bearing Formation on Stability of Roof of Coal Seams

    Institute of Scientific and Technical Information of China (English)

    孟召平; 彭苏萍; 李国庆; 黄为; 芦俊; 雷志勇

    2003-01-01

    Lithology is one of the important factors influencing the stability of roof of coal seams. In order to investigate this, the phenomenon of underground pressure and distribution of pressure were studied by using the local observation and simulation test with similar materials. The observation results show that the distance of initial weighting and periodic weighting of the mudstone roof is shorter than that of sandstone roofs. The sandstone roof with a high strength has a longer distance of initial weighting and periodic weighting, the abutment stress on the working face is big and the height of caving and fracture zone is high. The peak point of abutment stress in the sandstone roof is near to the working face and the pressure bump is inclined to occur. The result is contrary to that in case of the mudstone roof with a low strength. While in the transition zone of nipped sandstone, roof rock-mass is broken and is poor in stability, therefore, it is difficult to hold the roof.

  5. Clinical observation of desensitizing effects of hybrid coat and toro fluorine on tooth dentin after tooth preparation%劲润与多乐氟对备牙后牙本质敏感脱敏效果临床观察

    Institute of Scientific and Technical Information of China (English)

    辜健敏; 赵峰

    2014-01-01

    Objective To evaluate and compare the desensitization effects of hybrid coat dentin protection film and toro fluorine on crown-bridge preparation of tooth dentin of vital pulp abutment tooth. Methods 60 patients( total 137 vital pulp teeth)were selected and divided randomly into three groups:hybrid coat group,toro fluorine group and control group. The patientsˊcrowns were temporarily repaired after preparation of teeth dentin for the vital pulp abutment teeth under local anesthesia. Seven days later,the temporary crown was removed;and hybrid coat and toro fluorine,and distilled water were applied on the surface of vital pulp abutment teeth,respectively,and the sensitivity of the vital pulp teeth to mechanical and temperature stimulations was evaluated based on visible analogue scale/score( VAS ). Results The VAS values of the hybrid coat group and toro fluorine group after the desensitization treatment were lower than those before the treatment,and were significantly lower than that of the control group(P0. 05)and the control group itself had no statistical difference in VAS value before and after desensitization(P>0. 05). Conclusion Both hybrid coat dentin protection film and toro fluorine on crown-bridge prepared tooth dentin of vital pulp abutment tooth can relieve the dentin sensitivity symptoms of vital pulp abutment tooth after full-crown preparation,and they have not statistical difference in efficiency.%目的评价、对比劲润牙本质保护膜与多乐氟对冠桥活髓基牙预备后牙本质敏感的脱敏效果。方法将60例患者(共137颗活髓牙)随机分为3组:劲润组、多乐氟组、对照组,局麻下活髓基牙行牙体预备后临时冠修复。7 d后去除临时冠,采用可视分级评价法( VAS),观察在活髓基牙表面分别涂抹劲润、多乐氟及蒸馏水前后,机械刺激和温度刺激活髓基牙的敏感程度。结果劲润组和多乐氟组脱敏治疗后VAS值均低于治疗前

  6. Clinical Research of Repairing Single Posterior Tooth Loss by Adhesion Fixed Bridge%粘结固定桥修复单个后牙缺失的临床研究

    Institute of Scientific and Technical Information of China (English)

    彭蓓; 储雯; 张婉丽; 杨杨; 张晓渝; 王祥云; 黄大海

    2013-01-01

    目的 观察改良C型粘结固定桥修复下颌单个后牙缺失伴桥基牙倾斜的患者的临床效果.方法 选择口腔门诊下颌单个后牙缺失并伴远端基牙向近中或舌侧倾斜的32例患者,采用改良C型粘结桥修复,修复体粘结后即刻、半年、la和2a观察,对修复体边缘适合性、基牙菌斑指数、X线片检查和患者主观感受等方面进行评价.结果 修复后半年内复查,未有一例失败,基牙菌斑指数与对照牙相比,差异无统计学意义(P>0.05);0.5~2a定期复查有4例舌侧属翼板松脱,但患者自觉咀嚼功能良好,X线片显示基牙牙周膜间隙无异常,基牙菌斑指数与对照牙相比,差异有统计学意义(P<0.05).结论 改良C型粘结固定桥修复下颌单个后牙缺失,短期临床修复效果较好,树脂粘接技术也能满足临床修复的要求,但修复后牙周的维护是很有必要的.%Objective To observe the clinical result of patients with single posterior tooth and abutment tooth bevel repaired by improved C-type retainer adhesion fixed bridge. Methods 32 patients with loss of mandibule single posterior tooth and abutment tooth bevel buccal or lingual direction were selected using C-type retainer adhesion fixed bridge to restore. We observed the bonder compatibility, abutment dental plaque index, radiography and subjective perception of patients after bond instantly, half a year,1year and 2 years after treatment. Results Patients were reviewed in half a year after treatment, and there was no failure. Compared with control teeth, abutment dental plaque index didn't show statistically significant difference (P > 0.05). 4 cases occurred lingual wing loosening after recheck in 0.5-2 years, but patients felt good masticatory function. Radiography displayed normal periodontal membrane space, abutment dental plaque achieved statistically significant difference (P<0.05). Conclusion Improved C-type retainer adhesion fixed bridge has better repair

  7. Level II scour analysis for Bridge 24 (MANCUS00070024) on U.S. Route 7, crossing Lye Brook, Manchester, Vermont

    Science.gov (United States)

    Olson, Scott A.

    1997-01-01

    28, 1995). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 45 degrees to the opening while the opening-skew-to-roadway is 55 degrees. At the time of construction, the downstream channel was relocated (written communication, Dan Landry, VTAOT, January 2, 1997). A levee on the downstream right bank was also constructed and is protected by type-4 stone-fill (less than 60 inches diameter) extending from the bridge to more than 300 feet downstream. Type-2 stone fill (less than 36 inches diameter) covers the downstream right bank from the bridge to more than 300 feet downstream. Type-2 stone-fill also extends from the bridge to 220 feet upstream on both upstream banks. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and recommended rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995) for the 100- and 500-year discharges. In addition, the incipient roadway-overtopping discharge is analyzed since it has the potential of being the worst-case scour scenario. Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows ranged from 1.0 to 1.6 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour computations for the left abutment ranged from 14.5 to 16.1 ft. with the worst-case occurring at the 100-year discharge. Abutment scour computations for the right abutment ranged from 6.9 to 10.4 ft. with

  8. Level II scour analysis for Bridge 23 (GLOVTH00410023) on Town Highway 41, crossing Sherburne Brook, Glover, Vermont

    Science.gov (United States)

    Olson, Scott A.; Boehmler, Erick M.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure GLOVTH00410023 on Town Highway 41 crossing Sherburne Brook, Glover, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the New England Upland section of the New England physiographic province in northern Vermont. The 2.57-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is primarily forest with small areas of lawn and a home on the right overbank and a gravel roadway along the upstream left bank. In the study area, Sherburne Brook has an incised, sinuous channel with a slope of approximately 0.03 ft/ft, an average channel top width of 33 ft and an average bank height of 6 ft. The channel bed material ranges from gravel to boulder with a median grain size (D50) of 57.3 mm (0.188 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 24, 1994, indicated that the reach was stable. The Town Highway 41 crossing of Sherburne Brook is a 24-ft-long, one-lane bridge consisting of one 21-foot steel-beam span with a timber deck (Vermont Agency of Transportation, written communication, August 4, 1994). The opening length of the structure parallel to the bridge face is 20.3 ft. The bridge is supported by vertical, granite block abutments. The channel is skewed approximately 55 degrees to the opening while the measured opening-skew-to-roadway is 30 degrees. One foot

  9. Level II scour analysis for Bridge 48 (FFIETH00300048) on Town Highway 30, crossing Wanzer Brook, Fairfield, Vermont

    Science.gov (United States)

    Flynn, Robert H.; Boehmler, Erick M.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure FFIETH00300048 on Town Highway 30 crossing Wanzer Brook, Fairfield, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in northwestern Vermont. The 6.78-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover upstream of the bridge and on the downstream right bank is primarily pasture. The downstream left bank is forested. In the study area, Wanzer Brook has an incised, straight channel with a slope of approximately 0.03 ft/ft, an average channel top width of 65 ft and an average bank height of 5 ft. The channel bed material is cobble with a median grain size (D50) of 111 mm (0.364 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 11, 1995, indicated that the reach was stable. The Town Highway 30 crossing of Wanzer Brook is a 31-ft-long, two-lane bridge consisting of one 28-foot steel-beam span (Vermont Agency of Transportation, written communication, March 8, 1995). The opening length of the structure parallel to the bridge face is 26 ft.The bridge is supported by vertical stone wall abutments with concrete caps and “kneewall” footings. The channel is skewed approximately 25 degrees to the opening while the measured opening-skew-to-roadway is 20 degrees. A scour hole 1.5 ft deeper than

  10. 可摘局部义齿基牙楔状缺损充填修复的临床疗效分析%Removable Partial Denture Restoration of Wedge-shaped Defect Clinical Analysis

    Institute of Scientific and Technical Information of China (English)

    田云霞

    2013-01-01

      目的:分析研究临床采用三种材料对可摘局部义齿基牙颈部楔状缺损的临床修复疗效.方法:选取我院口腔门诊2009年3月~2010年3月收治的62例患者174颗楔状缺损可摘局部义齿基牙,随机分为为A组、B组及C组.分别采用三种材料对其缺损部位进行修复,修复2年后采用改良的USPHS系统评价修复体的疗效.结果:A组、B组与C组比较有显著性差异(P<0.05)有统计学意义.结论:可摘局部义齿基牙楔状缺损应及早黏结修复以改善该处的集中应力状况,以提高楔状缺损患者的生活质量.%Objective:To study three glass ionomer cements materials for removable partial denture abutments cervical wedge-shaped defects of clinical therapeutic effect of repair.Methods:In our hospital in 2009 March~2010 March dental clinic in 62 patients 174 wedge-shaped defect with removable partial denture abutments,respectively,using three kinds of materials on the defect repair,restoration after 2 years by using the improved USPHS system restoration effect evaluation.Results:The amalgam group,Dyract group and GC Fuji IX composite GP glass ionomer cement group had significant difference (P<0.05) was statistically significant.Conclusion:Removable partial denture abutment teeth wedge-shaped defects should be early restorations to improve the concentrated stress condition,in order to improve the quality of life in patients with wedge shaped defect.

  11. Development and Application of SCAR Markers for Discriminating Cytoplasmic Male Sterile Lines from Their Cognate Maintainer Lines in Indica Rice

    Institute of Scientific and Technical Information of China (English)

    LU Chao; LIU Jian; JIANG Jian-hua; Caleb Manamik BRERIA; TAN He-lin; Masahiko ICHII; HONG De-lin

    2013-01-01

    The DNA fragments about 1 600 bp were amplified using random amplified polymorphism DNA (RAPD) primer OPA12 with the templates of mitochondrial DNA of Zhenshan 97A and Zhenshan 97B,and were sequenced.The nucleotide sequences and lengths of the fragments from Zhenshan 97A and Zhenshan 97B showed no difference.The precise length of the fragment was 1 588 bp.Sequence characterized amplification region (SCAR) primers were then developed to discriminate the cytoplasmic male sterile (CMS) lines and their maintainer lines.A specific 1 588 bp fragment could be amplified with SCAR primers,CHI19F2/CHI19R2 and CHI20F3/CHI23R3,in the mitochondrial DNA of Zhenshan 97A,but not Zhenshan 97B.Furthermore,the specific fragment could be also amplified from the total DNA from green leaf tissues of Zhenshan 97A with SCAR primers,but not Zhenshan 97B.With the corresponding primers,the specific fragment could also be amplified from the total DNA of green leaves of other two CMS lines with wild abortive type cytoplasm (CMS-WA),namely Zhenpin A and Tianfeng A,but not in their maintainer lines.Moreover,using total DNA as template,each of the four pairs of SCAR primers could also be used to amplify the 1 588 bp fragment in CMS-ID (Indonesia paddy type) line Ⅱ-32A,but not in Ⅱ-32B,and the specific fragment was amplified from the DNA of both F1 and F2 seedlings of Shanyou 63.The results of detecting the genetic purity of a man-made mixture of the seeds of Zhenshan 97A using CHI20F3/CHI23R3 were completely consistent with the phenotypes.Taken together,these results indicated that the specific 1 588 bp-fragment amplified by CHI20F3/CHI23R3 was the unique amplification products of CMS mitochondrial DNA,and could be used to distinguish CMS-WA and CMS-ID lines from their corresponding maintainer lines at the seedling stage.

  12. 路桥过渡段路堤加筋现场试验和数值模拟分析%Experimental and numerical simulation analysis on geosynthetic reinforced embankment at bridge approaches

    Institute of Scientific and Technical Information of China (English)

    张军; 郑俊杰; 马强; 董友扣

    2011-01-01

    采用土工格栅加筋处理路堤填土可有效解决路堤填土压缩变形过大的问题,从而减小路桥过渡段桥台与路堤的差异沉降以及缓解桥头跳车的现象.通过现场试验对加筋路堤中格栅上、下表面土压力与格栅变形进行了监测分析.采用有限元方法对比分析路堤在加筋与未加筋2种工况下路桥过渡段路堤变形的差异.结果表明:路堤加筋技术在桥台附近减载作用明显,随着距桥台距离的增加,减载作用逐渐减弱;路堤加筋技术有效减小了桥台与路堤的差异沉降.最后,对桩体弹性模量、桩径、筋材抗拉刚度、路堤填土黏聚力和路堤填土内摩擦角进行了参数分析.%Geosynthetic can be used to reinforce the embankment fill so that it can solve problems of excessive compression effectively, thus reduce differential settlements between bridge abutment and embankment and alleviate bump at the approach of the bridge. The stress and deformation of the soil above and below the geosynthetic were measured through the field test. In addition, the differential settlements at the bridge approach under two conditions (embankment with and without geosynthetic reinforcement) were analyzed by finite element method. The results show that load-reduction of the reinforced embankment technique is significant at the vicinity of bridge abutment, while the effect moderates with the distance from the bridge abutment; and the reinforced embankment technique can relieve the differential settlement at the bridge approach effectively. Finally, parametric studies on elastic modulus and diameter of pile, tensile stiffness of geosynthetic, cohesion and friction angle of embankment fill were carried out.

  13. Clinical evaluation of IPS e.max Press ceramic endocrowns in individual maxillary anterior teeth malposition%铸瓷髓腔固位冠修复个别上前牙错位的疗效观察

    Institute of Scientific and Technical Information of China (English)

    李雪铃; 杨凌; 朱文军; 林雪峰

    2015-01-01

    Objective The present study aimed to evaluate the clinical effects of IPS e.max Press ceramic endocrowns applied in individual maxillary anterior teeth malposition. Methods Fifteen malposed maxillary anterior teeth were selected from fifteen patients in this study. All the malposed teeth had been endodontically treated and performed with ultrasonic scaling. After 1-2 weeks, the IPS e.max Press ceramic endocrowns were fabricated and cemented with resin cement. The color, shape, margin fitness, preservation of the restorations and the gingival health of the abutments were reviewed after 6 months and 12 months respectively. Results The margins of all restorations were well sealed; the colorsand shapes of the restorations were satisfied and matched with the natural teeth; and the periodontal tissues of the abutments were healthy. Except for one case with displacement of the abutment, the remaining endocrowns were functioning well without loosening. The preservation rate of the restorations was 100%(15/15), and the clinically acceptable rate was 93.3%(14/15). Conclusions Application of IPS e.max Press ceramic endocrowns in repairing individual maxillary anterior teeth malposition could obtain satisfied effects.%目的:探讨IPS e.max Press铸瓷髓腔固位冠在个别上前牙错位修复中的临床疗效。方法选择15例个别上前牙错位的患者,经完善根管治疗和(或)牙周治疗,1~2周后制作IPS e.max Press铸瓷髓腔固位冠,树脂粘接剂粘固。并于6个月、1年后复查修复体的颜色、形态、边缘密合性、牙龈健康情况、基牙及修复体的保存情况。结果1年内所有修复体边缘密合、牙龈健康、颜色美观;除1例基牙移位外,其余髓腔固位冠无松动移位。保存率100%(15/15),临床可接受率为93.3%(14/15)。结论 IPS e.max Press铸瓷髓腔固位冠用于个别上前牙错位的修复可取得良好的效果。

  14. Characterization of a new SCCmec element in Staphylococcus cohnii.

    Directory of Open Access Journals (Sweden)

    Zhiyong Zong

    Full Text Available BACKGROUND: Many SCCmec elements of coagulase-negative staphylococci (CoNS could not be typed using multiplex PCR. Such a 'non-typable' SCCmec was encountered in a Staphylococcus cohnii isolate. METHODOLOGY/PRINCIPAL FINDINGS: The SCCmec type of methicillin-resistant S. cohnii clinical isolate WC28 could not be assigned using multiplex PCR. Newly-designed primers were used to amplify ccrA and ccrB genes. The whole SCCmec was obtained by three overlapping long-range PCR, targeting regions from left-hand inverted repeat (IRL to ccrA/B, from ccrA/B to mecA and from mecA to orfX. The region abutting IRL was identified using inverse PCR with self-ligated enzyme-restricted WC28 fragments as the template. WC28 SCCmec had a class A mec gene complex (mecI-mecR1-mecA. The ccrA and ccrB genes were closest (89.7% identity to ccrA(SHP of Staphylococcus haemolyticus strain H9 and to ccrB3 (90% identity of Staphylococcus pseudintermedius strain KM241, respectively. Two new genes potentially encoding AAA-type ATPase were found in J1 region and a ψTn554 transposon was present in J2 region, while J3 region was the same as many SCCmec of Staphylococcus aureus. WC28 SCCmec abutted an incomplete SCC element with a novel allotype of ccrC, which was closest (82% identity to ccrC1 allele 9 in Staphylococcus saprophyticus strain ATCC 15305. Only two direct target repeat sequences, one close to the 3'-end of orfX and the other abutting the left end of WC28 SCCmec, could be detected. CONCLUSIONS/SIGNIFICANCE: A new 35-kb SCCmec was characterized in a S. cohnii isolate, carrying a class A mec gene complex, new variants of ccrA5 and ccrB3 and two novel genes in the J1 region. This element is flanked by 8-bp perfect inverted repeats and is similar to type III SCCmec in S. aureus and a SCCmec in S. pseudintermedius but with different J1 and J3 regions. WC28 SCCmec was arranged in tandem with an additional SCC element with ccrC, SCC(WC28, but the two elements might have

  15. The application of modified telescopic inner-crown on fixed partial denture for the patients with tilted molars in mandible%改良内冠式套筒冠在下颌倾斜基牙固定修复中的应用

    Institute of Scientific and Technical Information of China (English)

    熊萍; 林云红; 刘彦

    2015-01-01

    Objective To evaluate the clinical effects of the modified telescopic denture on restoration for the patients with tilted mo-lars as abutments in mandible. Methods The fixed partial denture was made for 27 patients with the first molar defect and the second molar tilted in mandible. The axis of the tilted abutment was adopted by using the modified telescopic inner-crown to achieve a common path of insertion for a fixed partial denture. Results A 0. 5-2 years′follow-up study was conducted on the patients to evaluate the effects of the modified telescopic inner-crown on the fixed partial denture. After they were applied to these patients,all dentures were comfortable, stable and functioning. The abutments were healthy without endodontic and periodontal disease. X-Ray showed no absorption of alveolar. Conclusions The modified telescopic denture is a well-accepted treatment modality in patients with the titled molars.%目的:探讨改良内冠式套筒冠在下颌第一磨牙缺失,第二磨牙倾斜固定修复中的应用效果。方法通过改良套筒内冠改变倾斜基牙轴向,与另一侧基牙取得共同就位道,固定修复下颌缺失牙。结果27个固定桥经过0.5~2年临床观察,固位稳定,基牙无继发龋,无牙龈炎症,无松动,咀嚼效果较好。 X线片显示,倾斜基牙牙槽骨无明显吸收。结论改良内冠式套筒冠可用于倾斜基牙的固定修复,扩大了固定修复的适应范围。

  16. Strain analysis of different diameter Morse taper implants under overloading compressive conditions

    Directory of Open Access Journals (Sweden)

    Carolina Guimarães CASTRO

    2015-01-01

    Full Text Available The aim of this study was to evaluate the amount of deformation from compression caused by different diameters of Morse taper implants and the residual deformation after load removal. Thirty Morse taper implants lacking external threads were divided into 3 groups (n = 10 according to their diameter as follows: 3.5 mm, 4.0 mm and 5.0 mm. Two-piece abutments were fixed into the implants, and the samples were subjected to compressive axial loading up to 1500 N of force. During the test, one strain gauge remained fixed to the cervical portion of each implant to measure the strain variation. The strain values were recorded at two different time points: at the maximum load (1500 N and 60 seconds after load removal. To calculate the strain at the implant/abutment interface, a mathematical formula was applied. Data were analyzed using a one-way Anova and Tukey’s test (α = 0.05. The 5.0 mm diameter implant showed a significantly lower strain (650.5 μS ± 170.0 than the 4.0 mm group (1170.2 μS ± 374.7 and the 3.5 mm group (1388.1 μS ± 326.6 (p < 0.001, regardless of the load presence. The strain values decreased by approximately 50% after removal of the load, regardless of the implant diameter. The 5.0 mm implant showed a significantly lower strain at the implant/abutment interface (943.4 μS ± 504.5 than the 4.0 mm group (1057.4 μS ± 681.3 and the 3.5 mm group (1159.6 μS ± 425.9 (p < 0.001. According to the results of this study, the diameter influenced the strain around the internal and external walls of the cervical region of Morse taper implants; all diameters demonstrated clinically acceptable values of strain.

  17. Clinical observation of Hybrid Coat dental adhesive resin cement on postoperative hypersensitivity in vital teeth preparation for crown restoration%劲润牙本质保护膜防治牙体预备后牙本质敏感的近期疗效观察

    Institute of Scientific and Technical Information of China (English)

    牛薇

    2012-01-01

    目的 评价劲润牙本质保护膜(Hybrid coat)对活髓基牙预备后牙本质敏感的防治效果.方法 将54例(共115颗)进行固定桥修复行牙体预备的基牙,对缺牙区两侧基牙随机分组,试验组在牙体预备后表面用劲润牙本质保护膜处理,对照组牙体预备后不做任何处理,所有基牙均采用暂时冠修复,备牙后和10天试戴修复体时观察治疗效果,评定疗效,并对戴牙前评定的疗效进行统计学分析.结果 经劲润牙本质保护膜处理过的基牙牙本质敏感症状明显改善,两次疗效比价,有效率差别有统计学意义(P<0.05).结论 劲润牙本质保护膜可以有效防治活髓基牙预备后的牙本质敏感症状,值得在临床上推广应用.%Objective To evaluate the effect in preventing dentin hypersentivity by using Hybrid coat dental adhesive resin cement on prepared vital pulp abutment teeth. Methods 115 prepared vital pulp abutment teeth of 54 cases were randomly divided into experiment group and control group: One was treated with Hybrid coat dental adhesive resin cement, and the other was without any treatment as control. All of the prepared abutment teeth were protected by temporary crown or bridge. To evaluate the effect of hypersensitivity wheri try in the terminal restotations 10 days later. Then the results were analyzed using statistics software. Results After 10 days, the symptom of dentin hypersentivity by using Hybrid coat dental adhesive resin cement in experiment group was obviously alleviated. Conclusion Conclusion: Dentin hypersentivity can be effectively released by using Hybrid coat dental adhesive resin cement after tooth prepartion.

  18. Performance-based seismic assessment of skewed bridges with and without considering soil-foundation interaction effects for various site classes

    Science.gov (United States)

    Ghotbi, Abdoul R.

    2014-09-01

    The seismic behavior of skewed bridges has not been well studied compared to straight bridges. Skewed bridges have shown extensive damage, especially due to deck rotation, shear keys failure, abutment unseating and column-bent drift. This research, therefore, aims to study the behavior of skewed and straight highway overpass bridges both with and without taking into account the effects of Soil-Structure Interaction (SSI) due to near-fault ground motions. Due to several sources of uncertainty associated with the ground motions, soil and structure, a probabilistic approach is needed. Thus, a probabilistic methodology similar to the one developed by the Pacific Earthquake Engineering Research Center (PEER) has been utilized to assess the probability of damage due to various levels of shaking using appropriate intensity measures with minimum dispersions. The probabilistic analyses were performed for various bridge configurations and site conditions, including sand ranging from loose to dense and clay ranging from soft to stiff, in order to evaluate the effects. The results proved a considerable susceptibility of skewed bridges to deck rotation and shear keys displacement. It was also found that SSI had a decreasing effect on the damage probability for various demands compared to the fixed-base model without including SSI. However, deck rotation for all types of the soil and also abutment unseating for very loose sand and soft clay showed an increase in damage probability compared to the fixed-base model. The damage probability for various demands has also been found to decrease with an increase of soil strength for both sandy and clayey sites. With respect to the variations in the skew angle, an increase in skew angle has had an increasing effect on the amplitude of the seismic response for various demands. Deck rotation has been very sensitive to the increase in the skew angle; therefore, as the skew angle increased, the deck rotation responded accordingly

  19. Exporting the European Idea of a National Language: Some Educational Implications of the Use of English and Indigenous Languages in the Philippines

    Science.gov (United States)

    Smolicz, Jerzy J.; Nical, Illuminado

    1997-09-01

    The Philippines has a bilingual education policy, using English and a major indigenous language, Tagalog, renamed "Filipino". This article describes a study on the problem facing approximately two thirds of the population who do not have English or Filipino as their first or home language. Senior secondary school students were asked abut their attitudes towards English, Filipino and their home language (Cebuana, Ilocano or Waray). Attitudes to the three languages differed. Some respondents favoured Filipino over English, others vice versa. Most respondents showed attachment to their home languages. The study concluded that it is possible for Filipinos to be literate in their mother tongue and still be fluent in Filipino, as the national language of the country, with English continuing in its role as the international language.

  20. Legal obstacles and incentives to the development of small-scale hydroelectric power in Rhode Island

    Energy Technology Data Exchange (ETDEWEB)

    None,

    1980-05-01

    The legal and institutional obstacles to the development of small-scale hydroelectric energy at the state level are discussed. The Federal government also exercises extensive regulatory authority in the area, and the dual regulatory system from the standpoint of the appropriate legal doctrine, the law of pre-emption, application of the law to the case of hydroelectric development, and an inquiry into the practical use of the doctrine by the FERC is examined. In Rhode Island, any private rights in the flowing waters of a river or stream depend upon ownership of the abutting land. It appears Rhode Island follows the reasonable use theory of riparian law. The Department of Environmental Management is the most significant administrative agency with regard to dam construction, alteration, and operation in the state of Rhode Island.