WorldWideScience

Sample records for abutments

  1. 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.

  2. Earthquake Resistance of Integral Abutment Bridges

    OpenAIRE

    2009-01-01

    intermediate length bridges. Integral abutment construction eliminates joints and bearings which reduce long-term maintenance costs. However, in the absence of joints and bearings, the bridge abutments and foundations must be able to accommodate lateral movements from thermal expansion and contraction of the superstructure and from seismic events. Previous research has focused on the response to thermal expansion and contraction. The current research examines the response of integral abutment...

  3. 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.

  4. 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...

  5. Side abutment pressure distribution by field measurement

    Institute of Scientific and Technical Information of China (English)

    WANG Lian-guo; SONG Yang; HE Xing-hua; ZHANG Jian

    2008-01-01

    Given the 7123 working face in the Qidong Coal Mine of the Wanbei Mining Group, nine dynamic roof monitors were installed in the crossheading to measure the amount and velocity of roof convergence in different positions and at different times and three steel bored stress sensors were installed in the return airway to measure rock stress at depth. On the basis of this arrangement, the rule of change of the distribution of the side abutment pressure with the advance of the working face and movement of overlying strata was studied. The rule of change and the stability of rock stress at depth were measured. Secondly, the affected area and stability time of the side abutment pressure were also studied. The results show that: 1) During working, the face advanced distance was from 157 m to 99 m, the process was not effected by mining induced pressure. When the distance was 82 m, the position of peak stress was 5 m away from the coal wall. When the distance was 37 m, the position of peak stress away from the coal wall was about 15 m to 20 m and finally reached a steady state; 2) the time and the range of the peak of side rock pressure obtained from stress sensors were consistent with the results from the dynamic roof monitors; 3) the position of the peak pressure was 25 m away from the coal wall.

  6. Microleakage Evaluation at Implant-Abutment Interface Using Radiotracer Technique

    Directory of Open Access Journals (Sweden)

    Hakimeh Siadat

    2016-10-01

    Full Text Available Objectives: Microbial leakage through the implant-abutment (I-A interface results in bacterial colonization in two-piece implants. The aim of this study was to compare microleakage rates in three types of Replace abutments namely Snappy, GoldAdapt, and customized ceramic using radiotracing.Materials and Methods: Three groups, one for each abutment type, of five implants and one positive and one negative control were considered (a total of 17 regular body implants. A torque of 35 N/cm was applied to the abutments. The samples were immersed in thallium 201 radioisotope solution for 24 hours to let the radiotracers leak through the I-A interface. Then, gamma photons received from the radiotracers were counted using a gamma counter device. In the next phase, cyclic fatigue loading process was applied followed by the same steps of immersion in the radioactive solution and photon counting.Results: Rate of microleakage significantly increased (P≤0.05 in all three types of abutments (i.e. Snappy, GoldAdapt, and ceramic after cyclic loading. No statistically significant differences were observed between abutment types after cyclic loading.Conclusions: Microleakage significantly increases after cyclic loading in all three Replace abutments (GoldAdapt, Snappy, ceramic. Lowest microleakage before and after cyclic loading was observed in GoldAdapt followed by Snappy and ceramic.Keywords: Dental Implants; Dental Implant-Abutment Design; Thallium Chloride

  7. 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.

  8. 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.

  9. Prosthetic abutment influences bone biomechanical behavior of immediately loaded implants.

    Science.gov (United States)

    Camargos, Germana de Villa; Sotto-Maior, Bruno Salles; Silva, Wander José da; Lazari, Priscilla Cardoso; Del Bel Cury, Altair Antoninha

    2016-05-31

    This study aimed to evaluate the influence of the type of prosthetic abutment associated to different implant connection on bone biomechanical behavior of immediately and delayed loaded implants. Computed tomography-based finite element models comprising a mandible with a single molar implant were created with different types of prosthetic abutment (UCLA or conical), implant connection (external hexagon, EH or internal hexagon, IH), and occlusal loading (axial or oblique), for both immediately and delayed loaded implants. Analysis of variance at 95%CI was used to evaluate the peak maximum principal stress and strain in bone after applying a 100 N occlusal load. The results showed that the type of prosthetic abutment influences bone stress/strain in only immediately loaded implants. Attachment of conical abutments to IH implants exhibited the best biomechanical behavior, with optimal distribution and dissipation of the load in peri-implant bone.

  10. Prosthetic abutment influences bone biomechanical behavior of immediately loaded implants

    Directory of Open Access Journals (Sweden)

    Germana de Villa CAMARGOS

    2016-01-01

    Full Text Available Abstract This study aimed to evaluate the influence of the type of prosthetic abutment associated to different implant connection on bone biomechanical behavior of immediately and delayed loaded implants. Computed tomography-based finite element models comprising a mandible with a single molar implant were created with different types of prosthetic abutment (UCLA or conical, implant connection (external hexagon, EH or internal hexagon, IH, and occlusal loading (axial or oblique, for both immediately and delayed loaded implants. Analysis of variance at 95%CI was used to evaluate the peak maximum principal stress and strain in bone after applying a 100 N occlusal load. The results showed that the type of prosthetic abutment influences bone stress/strain in only immediately loaded implants. Attachment of conical abutments to IH implants exhibited the best biomechanical behavior, with optimal distribution and dissipation of the load in peri-implant bone.

  11. 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.

  12. 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.

  13. 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

  14. Prosthetic abutment influences bone biomechanical behavior of immediately loaded implants

    OpenAIRE

    Camargos, Germana de Villa; SOTTO-MAIOR,Bruno Salles; Silva,Wander José da; Priscilla Cardoso LAZARI; Del Bel Cury, Altair Antoninha

    2016-01-01

    Abstract This study aimed to evaluate the influence of the type of prosthetic abutment associated to different implant connection on bone biomechanical behavior of immediately and delayed loaded implants. Computed tomography-based finite element models comprising a mandible with a single molar implant were created with different types of prosthetic abutment (UCLA or conical), implant connection (external hexagon, EH or internal hexagon, IH), and occlusal loading (axial or oblique), for both i...

  15. Creep and shrinkage effects on integral abutment bridges

    Science.gov (United States)

    Munuswamy, Sivakumar

    Integral abutment bridges provide bridge engineers an economical design alternative to traditional bridges with expansion joints owing to the benefits, arising from elimination of expensive joints installation and reduced maintenance cost. The superstructure for integral abutment bridges is cast integrally with abutments. Time-dependent effects of creep, shrinkage of concrete, relaxation of prestressing steel, temperature gradient, restraints provided by abutment foundation and backfill and statical indeterminacy of the structure introduce time-dependent variations in the redundant forces. An analytical model and numerical procedure to predict instantaneous linear behavior and non-linear time dependent long-term behavior of continuous composite superstructure are developed in which the redundant forces in the integral abutment bridges are derived considering the time-dependent effects. The redistributions of moments due to time-dependent effects have been considered in the analysis. The analysis includes nonlinearity due to cracking of the concrete, as well as the time-dependent deformations. American Concrete Institute (ACI) and American Association of State Highway and Transportation Officials (AASHTO) models for creep and shrinkage are considered in modeling the time dependent material behavior. The variations in the material property of the cross-section corresponding to the constituent materials are incorporated and age-adjusted effective modulus method with relaxation procedure is followed to include the creep behavior of concrete. The partial restraint provided by the abutment-pile-soil system is modeled using discrete spring stiffness as translational and rotational degrees of freedom. Numerical simulation of the behavior is carried out on continuous composite integral abutment bridges and the deformations and stresses due to time-dependent effects due to typical sustained loads are computed. The results from the analytical model are compared with the

  16. 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.

  17. Temporal variation of clear-water scour at compound Abutments

    Directory of Open Access Journals (Sweden)

    Aminuddin Ab. Ghani

    2016-12-01

    Full Text Available Most of actual abutments in rivers are built on foundation, while there is limited number of study available on the effects of the foundation on the local scour. In this study, temporal variation of local scour around compound abutment was investigated experimentally under clear-water conditions. The results showed that a suitable level of foundation is able to decrease the scour depth and increase scour time during the flood events. The trend of temporal scour depth at compound pier and abutment is similar. The scour depth develops to top of foundation quickly, and then the foundation postpones the scour development (lag–time. Duration of lag–time depends on the foundation level, velocity ratio (U/Uc and foundation dimension. This study highlights that proper design of foundation level increases duration of scouring and provides enough time to treat bridge foundation after the flood events.

  18. 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.

  19. 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...

  20. 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.

  1. Influence of Abutment Material on the Stress of Implant-supported All-ceramic Single Crown

    Institute of Scientific and Technical Information of China (English)

    GAO Shaohuai; DUAN Haiying; LI Zhiyong

    2012-01-01

    In order to investigate the influence of abutment material on the stress of implant-supported all-ceramic single crown,a 3D finite element model of implant-supported mandibular first premolar was computed by COSMOS/M 2.85 software.Alumina,zirconia,and titanium were used as abutment materials respectively.Vertical 600 N and horizontal 225 N load was applied on the occlusal surface.The results show that the stress distribution of implant-supported single crown was similar for different abutment materials.Maximum stresses within the crown were higher when titanium abutment was used.Maximum stress of titanium abutment was lower than that of ceramic abutment.Within the screw and fixture,maximum stresses had no difference under vertical loading but higher as titanium abutment was used under horizontal loading.There was no difference of maximum stress within the bone when different abutment materials were used.The present findings indicate that the abutment material had no influence on the stress distribution of implant-supported allceramic single crown but maximum stress when the titanium abutment was lower than that of ceramic abument.

  2. Fixed reconstructions in partially edentulous patients using two-part ITI implants (Bonefit) as abutments.

    Science.gov (United States)

    Brägger, U; Hämmerle, C; Weber, H P

    1990-12-01

    Fixed reconstructions on implant abutments may be a welcome modality in the treatment of partially edentulous patients following the principles of a prophylactically oriented comprehensive care. The option to create artificial tissue integrated abutments widens the range of indications for fixed reconstructions. Risky long-span bridges as well as the preparation of intact teeth for bridge abutments may frequently be avoided. Never should the contours of the prosthesis interfere with the patient's performance of optimal plaque control. Furthermore, supportive periodontal therapy with regular maintenance visits must be provided to optimize a long-term prognosis of the dention as well as the tissue-integrated artificial abutments.

  3. 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.

  4. 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.

  5. An innovative steel-concrete joint for integral abutment bridges

    Directory of Open Access Journals (Sweden)

    Bruno Briseghella

    2015-08-01

    Full Text Available Integral abutment bridges are becoming rather common, due to the durability problems of bearings and expansion joints. At the same time, among short- and medium-span bridges, multi-beam steel-concrete composite deck with hot-rolled girder is an economical and interesting alternative to traditional pre-stressed concrete solutions. The two concepts can be linked together to design integral steel-concrete composite bridges with the benefits of two typologies. The most critical aspect for these bridges is usually the joints between deck and piers or abutments. In this paper, an innovative beam-to-pier joint is proposed and a theoretical and experimental study is introduced and discussed. The analyzed connection is aimed at combining general ease of construction with a highly simplified assembly procedure and a good transmission of hogging and sagging moment at the supports in continuous beams. For this purpose, the traditional shear studs, used at the interface between steel beam and upper concrete slab, are also used at the ends of steel profiles welded horizontally to the end plates. To better understand the behaviour of this kind of joints and the roles played by different components, three large-scale specimens were tested and an FE model was implemented. The theoretical and experimental results confirmed the potential of the proposed connection for practical applications and indicated the way to improve its structural behaviour.

  6. Ankylosed teeth as abutments for maxillary protraction: a case report.

    Science.gov (United States)

    Kokich, V G; Shapiro, P A; Oswald, R; Koskinen-Moffett, L; Clarren, S K

    1985-10-01

    It has been recognized that using the maxillary teeth to deliver extraoral force to the maxilla not only results in sutural remodeling but also periodontal remodeling and tooth movement. In patients with severe maxillomandibular malrelationships, the potential for tooth movement often limits the amount and duration of extraoral force and, consequently, affects the success of treatment. This case report describes a technique to intentionally ankylose deciduous teeth in a patient with severe maxillary retrusion. The ankylosed teeth were used as abutments to deliver an anteriorly directed intermittent extraoral force. After 12 months of treatment, the anterior crossbite was nearly corrected. At that point the ankylosed teeth loosened because of root resorption and the treatment was terminated. Cephalometric superimposition demonstrated that the occlusal correction was the result of anterior maxillary movement with little mandibular growth and no movement of the ankylosed teeth. The results suggest that intentionally ankylosed teeth may be used as abutments for extraoral traction in patients with a severe disturbance in maxillary growth.

  7. Characteristics of implant-CAD/CAM abutment connections of two different internal connection systems.

    Science.gov (United States)

    Sumi, T; Braian, M; Shimada, A; Shibata, N; Takeshita, K; Vandeweghe, S; Coelho, P G; Wennerberg, A; Jimbo, R

    2012-05-01

    Titanium or zirconium computer-aided design/computer-aided manufacturing abutments are now widely used for aesthetic implant treatments; however, information regarding microscopic structural differences that may influence the biological and mechanical outcomes of different implant systems is limited. Therefore, the characteristics of different connection systems were investigated. Optical microscopic observation and scanning electron microscopy showed different characteristics of two internal systems, namely the Astra Tech and the Replace Select system, and for different materials. The scanning electron microscopic observation showed for the Astra Tech that the implant-abutment interface seemed to be completely sealed for both titanium and zirconium abutments, both horizontally and sagittally; however, the first implant-abutment contact was below the fixture top, creating a microgap, and fixtures connected with titanium abutments showed significantly larger values (23·56μm±5·44 in width, and 168·78μm±30·39 in depth, P0·70), creating an inverted microgap. Thus, microscopy evaluation of two commonly used internal systems connected to titanium or zirconium abutments showed that the implant-abutment interface was perfectly sealed under no-loading conditions. However, an inverted microgap was seen in both systems, which may result in bacterial accumulation as well as alteration of stress distribution at the implant-abutment interface.

  8. Abutment-to-fixture load transfer and peri-implant bone stress

    NARCIS (Netherlands)

    van Oers, R.F.; Feilzer, A.J.

    2015-01-01

    Purpose: To uncover design principles for the abutment-fixture complex that reduce the stress concentration on the bone. Methods: A 3-dimensional finite element model was used to vary shape, elasticity, and connectivity of the abutment-fixture complex. We compared peri-implant bone stress of these d

  9. A Simplified Technique for Implant-Abutment Level Impression after Soft Tissue Adaptation around Provisional Restoration

    OpenAIRE

    Ahmad Kutkut; Osama Abu-Hammad; Robert Frazer

    2016-01-01

    Impression techniques for implant restorations can be implant level or abutment level impressions with open tray or closed tray techniques. Conventional implant-abutment level impression techniques are predictable for maximizing esthetic outcomes. Restoration of the implant traditionally requires the use of the metal or plastic impression copings, analogs, and laboratory components. Simplifying the dental implant restoration by reducing armamentarium through incorporating conventional techniq...

  10. Evaluation of different methods to clean titanium abutments. A scanning electron microscopic study.

    Science.gov (United States)

    Speelman, J A; Collaert, B; Klinge, B

    1992-09-01

    The cleaning effectiveness of different treatment methods for titanium abutments was evaluated using scanning electron microscopy (SEM). In the mandible of 4 beagle dogs, 25 titanium abutments were installed (modum Brånemark). After 16 weeks of plaque accumulation, mineralized deposits had formed on 23 abutments. Each of these abutments was subjected to one of the following treatment methods: scaling with (1) metal, (2) plastic, or (3) ultrasonic instruments; (4) air-polishing, (5) weekly rubber cup polishing or (6) daily brushing with a conventional toothbrush. Fourteen abutments were removed immediately after treatment. On 9 abutments, the scaling procedures and air-polishing were repeated after another 16 weeks of plaque accumulation. The abutments were prepared for SEM, and each of them was viewed and photographed at 3 different magnifications. The photomicrographs were evaluated by 3 examiners who, guided by reference pictures, gave each abutment a "cleanliness" score, ranking from 0 to 5. Regular rubber cup polishing and regular brushing resulted in the highest surface cleanliness, while the air-polishing procedure showed the lowest cleanliness score. None of the 3 scaling methods created a cleanliness score better than 3. The 3 scaling methods were considered equal in their cleaning effectiveness. No differences could be observed between surfaces treated 1 x or 2 x. Taken the present findings and those of other studies concerning the effects of scaling on the surface roughness and biocompatibility into consideration, it was concluded that plastic scalers may be the instruments of choice for debridement of titanium implant surfaces.

  11. Soft tissue response to zirconia and titanium implant abutments : an in vivo within-subject comparison

    NARCIS (Netherlands)

    van Brakel, Ralph; Meijer, Gert J.; Verhoeven, Jan Willem; Jansen, John; de Putter, Cornelis; Cune, Marco S.

    2012-01-01

    Aim To compare the health of the soft tissues towards zirconia and titanium abutments in man, as observed using histological data. Material and Methods Twenty patients received two mandibular implants with either a zirconia or titanium abutment (split mouth study design, left-right randomization). A

  12. Soft tissue response to zirconia and titanium implant abutments: an in vivo within-subject comparison.

    NARCIS (Netherlands)

    Brakel, R. van; Meijer, G.J.; Verhoeven, J.W.; Jansen, J.A.; Putter, C. de; Cune, M.S.

    2012-01-01

    AIM: To compare the health of the soft tissues towards zirconia and titanium abutments in man, as observed using histological data. MATERIAL AND METHODS: Twenty patients received two mandibular implants with either a zirconia or titanium abutment (split mouth study design, left-right randomization).

  13. 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.

  14. Biomechanical Analysis of Individual All-Ceramic Abutments Used in Dental Implantology

    Directory of Open Access Journals (Sweden)

    Ziębowicz B.

    2016-09-01

    Full Text Available The paper presents the results of finite element analysis and experimental testing under simulated physiological loading conditions on issues shaping the functional properties of individual all-ceramic abutments manufactured by CAD/CAM technology. The conducted research have cognitive significance showing the all-ceramic abutment behavior, as a key element of the implantological system, under the action of cyclic load. The aim of this study was evaluation the fatigue behavior of yttria-stabilized zirconia abutment submitted to cyclic stresses, conducted in accordance with EN ISO 14801 applies to dynamic fatigue tests of endosseous dental implants.

  15. 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.

  16. 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

  17. 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.

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

    Science.gov (United States)

    Lorenzoni, Fabio C; Coelho, Paulo G; Bonfante, Gerson; Carvalho, Ricardo M; Silva, Nelson R F A; Suzuki, Marcelo; Silva, Thelma Lopes; Bonfante, Estevam A

    2011-01-01

    To evaluate the sealing capability of external hexagon implant systems and assess the marginal fit, two groups (n = 10 each) were employed: SIN (Sistema de Implantes Nacional, Brazil) and Osseotite, (Biomet 3i, USA). Sealing capability was determined by placing 0.7 μL of 1% acid-red solution in the implant wells before the torque of their respective abutments. Specimens were then placed into 2.5 mL vials filled with 1.3 mL of distilled water with the implant-abutment interface submerged. Three samples of 100 μL water were collected at previously determinate times. The absorbance was measured with a spectrophotometer, and the data were analyzed by Two-way ANOVA (P implant-abutment interface of both groups. Gaps in the implant-abutment interface were observed along with leakage increased at the 144 hrs evaluation period.

  19. 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.

  20. Effect of abutment mobility, site, and angle of impact on retention of fixed partial dentures.

    Science.gov (United States)

    Jacobi, R; Shillingburg, H T; Duncanson, M G

    1985-08-01

    Fixed partial dentures cemented to dies of adjustable mobility were subjected to repeated impacts at three different sites. Immobile abutments retained their prostheses longer than mobile abutments. Impacts that fell between the centers of rotation of the abutments were withstood longer than impacts that fell nearer the ends of the prostheses. This study failed to show a significant difference between the effect of impacts perpendicular to the occlusal plane and impacts angled 45 degrees toward the lingual plane. The results of this study suggest that (1) crowns that anchor rigid prostheses to mobile teeth require greater retentive ability than crowns on relatively immobile abutments and (2) occlusal impacts are best withstood when they fall on the areas of the fixed partial denture over and between the centers of rotation of the abutment teeth. If a fixed partial denture must withstand loading outside these areas, as is the case with cantilevered pontics and some tilted abutments, the retainer furthermost from the anticipated eccentric load must have exceptionally good retention.

  1. Evaluation of stability of interface between CCM (Co-Cr-Mo) UCLA abutment and external hex implant

    Science.gov (United States)

    Yoon, Ki-Joon; Park, Young-Bum; Choi, Hyunmin; Cho, Youngsung; Lee, Jae-Hoon

    2016-01-01

    PURPOSE The purpose of this study is to evaluate the stability of interface between Co-Cr-Mo (CCM) UCLA abutment and external hex implant. MATERIALS AND METHODS Sixteen external hex implant fixtures were assigned to two groups (CCM and Gold group) and were embedded in molds using clear acrylic resin. Screw-retained prostheses were constructed using CCM UCLA abutment and Gold UCLA abutment. The external implant fixture and screw-retained prostheses were connected using abutment screws. After the abutments were tightened to 30 Ncm torque, 5 kg thermocyclic functional loading was applied by chewing simulator. A target of 1.0 × 106 cycles was applied. After cyclic loading, removal torque values were recorded using a driving torque tester, and the interface between implant fixture and abutment was evaluated by scanning electronic microscope (SEM). The means and standard deviations (SD) between the CCM and Gold groups were analyzed with independent t-test at the significance level of 0.05. RESULTS Fractures of crowns, abutments, abutment screws, and fixtures and loosening of abutment screws were not observed after thermocyclic loading. There were no statistically significant differences at the recorded removal torque values between CCM and Gold groups (P>.05). SEM analysis revealed that remarkable wear patterns were observed at the abutment interface only for Gold UCLA abutments. Those patterns were not observed for other specimens. CONCLUSION Within the limit of this study, CCM UCLA abutment has no statistically significant difference in the stability of interface with external hex implant, compared with Gold UCLA abutment. PMID:28018564

  2. 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.

  3. Comparison of the fracture resistance of dental implants with different abutment taper angles.

    Science.gov (United States)

    Wang, Kun; Geng, Jianping; Jones, David; Xu, Wei

    2016-06-01

    To investigate the effects of abutment taper angles on the fracture strength of dental implants with TIS (taper integrated screwed-in) connection. Thirty prototype cylindrical titanium alloy 5.0mm-diameter dental implants with different TIS-connection designs were divided into six groups and tested for their fracture strength, using a universal testing machine. These groups consisted of combinations of 3.5 and 4.0 mm abutment diameter, each with taper angles of 6°, 8° or 10°. 3-Dimensional finite element analysis (FEA) was also used to analyze stress states at implant-abutment connection areas. In general, the mechanical tests found an increasing trend of implant fracture forces as the taper angle enlarged. When the abutment diameter was 3.5 mm, the mean fracture forces for 8° and 10° taper groups were 1638.9 N ± 20.3 and 1577.1 N ± 103.2, respectively, both larger than that for the 6° taper group of 1475.0 N ± 24.4, with the largest increasing rate of 11.1%. Furthermore, the difference between 8° and 6° taper groups was significant, based on Tamhane's multiple comparison test (Pimplants with different abutment taper angles and supported the findings of the static tests. In conclusion, increases of the abutment taper angle could significantly increase implant fracture resistance in most cases established in the study, which is due to the increased implant wall thickness in the connection part resulting from the taper angle enlargement. The increasing effects were notable when a thin implant wall was present to accommodate wide abutments.

  4. A modified technique for removing a failed abutment screw from an implant with a custom guide tube.

    Science.gov (United States)

    Taira, Yohsuke; Sawase, Takashi

    2012-04-01

    Fracture of abutment screw is a serious prosthodontic complication. When the abutment screw is fractured at the junction of the screw shank and screw thread, removal of the fractured screw fragment from the screw hole can be difficult. This article describes a modified technique for removing the failed abutment screw with a custom guide tube and tungsten carbide bur. The failed screw can be removed speedily without damaging the screw hole of the implant body or the screw threads.

  5. 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.

  6. 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.

  7. 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.

  8. A utilização de abutment de zircônia na reabilitação oral: aspectos protéticos e periodontais

    OpenAIRE

    Pesqueira, Aldieris Alves [UNESP; dos Santos, Daniela Micheline; Vechiato Filho,Aljomar José; GOIATO, Marcelo Coelho; Arsufi, Guilherme Sarauza [UNESP; Andreotti, Agda Marobo [UNESP

    2014-01-01

    Zirconia abutments are used to obtain satisfactory aesthetic results in implant fixed anterior prostheses when metal abutments promote a grayish mucosal discoloration of the peri-implant soft tissues. However, there is a lack of studies to confirm the clinical performance of the peri-implant soft tissues surrouding zirconia abutments. This study described a case report of a patient treated with implant fixed all-ceramic crown made out on zirconia abutment after 3 years of followup. A 47-year-...

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Implant-abutment gap versus microbial colonization : Clinical significance based on a literature review

    NARCIS (Netherlands)

    Passos, Sheila Pestana; May, Liliana Gressler; Faria, Renata; Ozcan, Mutlu; Bottino, Marco Antonio

    2013-01-01

    Microorganisms from the oral cavity may settle at the implant-abutment interface (IAI). As a result, tissue inflammation could occur around these structures. The databases MEDLINE/PubMed and PubMed Central were used to identify articles published from 1981 through 2012 related to the microbial colon

  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.

  16. 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.

  17. 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

  18. A method for using solid modeling CAD software to create an implant library for the fabrication of a custom abutment.

    Science.gov (United States)

    Zhang, Jing; Zhang, Rimei; Ren, Guanghui; Zhang, Xiaojie

    2017-02-01

    This article describes a method that incorporates the solid modeling CAD software Solidworks with a dental milling machine to fabricate individual abutments in house. This process involves creating an implant library with 3-dimensional (3D) models and manufacturing a base, scan element, abutment, and crown anatomy. The 3D models can be imported into any dental computer-aided design and computer-aided (CAD-CAM) manufacturing system. This platform increases abutment design flexibility, as the base and scan elements can be designed to fit several shapes as needed to meet clinical requirements.

  19. 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.

  20. 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.

  1. The role of prosthetic abutment material on the stress distribution in a maxillary single implant-supported fixed prosthesis

    Energy Technology Data Exchange (ETDEWEB)

    Peixoto, Hugo Eduardo, E-mail: hugo.e.peixoto@hotmail.com [Implantology Team, Latin American Institute of Research and Education in Dentistry, Curitiba, Paraná (Brazil); Bordin, Dimorvan, E-mail: dimorvan_bordin@hotmail.com [Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Limeira avenue, 901-Vila Rezende, Piracicaba, SP 13414-903 (Brazil); Del Bel Cury, Altair A., E-mail: altcury@fop.unicamp.br [Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Limeira avenue, 901-Vila Rezende, Piracicaba, SP 13414-903 (Brazil); Silva, Wander José da, E-mail: wanderjose@fop.unicamp.br [Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Limeira avenue, 901-Vila Rezende, Piracicaba, SP 13414-903 (Brazil); Faot, Fernanda, E-mail: fernanda.faot@gmail.com [Department of Restorative Dentistry, School of Dentistry, Federal University of Pelotas, Gonçalves Chaves, 457, 2nd floor, Pelotas, Rio Grande do Sul 96015-560 (Brazil)

    2016-08-01

    Purpose: Evaluate the influence of abutment's material and geometry on stress distribution in a single implant-supported prosthesis. Materials and Methods: Three-dimensional models were made based on tomographic slices of the upper middle incisor area, in which a morse taper implant was positioned and a titanium (Ti) or zirconia (ZrN) universal abutments was installed. The commercially available geometry of titanium (T) and zirconia (Z) abutments were used to draw two models, TM1 and ZM1 respectively, which served as control groups. These models were compared with 2 experimental groups were the mechanical properties of Z were applied to the titanium abutment (TM2) and vice versa for the zirconia abutment (ZM2). Subsequently, loading was simulated in two steps, starting with a preload phase, calculated with the respective friction coefficients of each materials, followed by a combined preload and chewing force. The maximum von Mises stress was described. Data were analyzed by two-way ANOVA that considered material composition, geometry and loading (p < 0.05). Results: Titanium and zirconia abutments showed similar von Mises stresses in the mechanical part of the four models. The area with the highest concentration of stress was the screw thread, following by the screw body. The highest stress levels occurred in screw thread was observed during the preloading phase in the ZM1 model (931 MPa); and during the combined loading in the TM1 model (965 MPa). Statistically significant differences were observed for loading, the material × loading interaction, and the loading × geometry interaction (p < 0.05). Preloading contributed for 77.89% of the stress (p < 0.05). There were no statistically significant differences to the other factors (p > 0.05). Conclusion: The screw was the piece most intensely affected, mainly through the preload force, independent of the abutment's material. - Highlights: • The abutment's screw was the most impaired piece of the

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

    OpenAIRE

    Marzieh Alikhasi; Mahnaz Arshad; Hakime Siadat; Susan Rahimian

    2012-01-01

    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 ...

  3. 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.

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

    Science.gov (United States)

    de Avila, Érica Dorigatti; de Barros-Filho, Luiz Antônio Borelli; de Andrade, Marcelo Ferrarezi; Mollo, Francisco de Assis; de Barros, Luiz Antônio Borelli

    2014-01-01

    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. PMID:24955259

  5. 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

  6. Nanomechanical properties of bone around cement-retained abutment implants. A minipig study

    Directory of Open Access Journals (Sweden)

    R.R.M. de Barros

    2016-06-01

    Full Text Available Aim The nanomechanical evaluation can provide additional information about the dental implants osseointegration process. The aim of this study was to quantify elastic modulus and hardness of bone around cemented-retained abutment implants positioned at two different crestal bone levels. Materials and methods The mandibular premolars of 7 minipigs were extracted. After 8 weeks, 8 implants were inserted in each animal: crestally on one side of the mandible and subcrestally on the other (crestal and subcrestal groups. Functional loading were immediately provided with abutments cementation and prostheses installation. Eight weeks later, the animals euthanasia was performed and nanoindentation analyses were made at the most coronal newly formed bone region (coronal group, and below in the threaded region (threaded group of histologic sections. Results The comparisons between subcrestal and crestal groups did not achieve statistical relevance; however the elastic modulus and hardness levels were statistically different in the two regions of evaluation (coronal and threaded. Conclusions The crestal and subcrestal placement of cement-retained abutment implants did not affect differently the nanomechanical properties of the surrounding bone. However the different regions of newly formed bone (coronal and threaded groups were extremely different in both elastic modulus and hardness, probably reflecting their differences in bone composition and structure.

  7. 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.

  8. 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.

  9. The Influence of Implant Abutment Surface Roughness and the Type of Cement on Retention of Implant Supported Crowns

    Science.gov (United States)

    Reddy, M. Sushender; Reddy, C. Rajaneesh; Pithani, Padmaja; R, Santosh Kumar; Kulkarni, Ganesh

    2015-01-01

    Objectives: To provide relative data on the retentive characters of the commonly used cements on different implant abutment surfaces. Materials and Methods: A total of 20 implant abutments were divided into 2 groups. Ten implants were unaltered and ten were air borne particle abraded with 50μ aluminium oxide. Three luting agents (Tempbond, IRM and ImProv) were used to secure the crowns to abutments. All the crowns were removed from the abutment with an Instron machine at 0.5mm per minute and tensile bond strengths were recorded. Statistical analysis was performed using Anova, Paired t-test and Post-Hoc tests. Results: IRM showed the highest mean tensile strength among the three cements when used with treated and untreated implant abutment surfaces. Change in the abutment surface roughness had no effect on the mean tensile bond strength of TempBond and IRM cements, whereas ImProv cement showed reduced tensile strength with sandblasted surface. Conclusion: When increased retention is required IRM cement with either sandblasted or milled surface could be used and when retrievability is required cements of choice could be either TempBond or ImProv. PMID:25954694

  10. Effects of different abutment connection designs on the stress distribution around five different implants: a 3-dimensional finite element analysis.

    Science.gov (United States)

    Balik, Ali; Karatas, Meltem Ozdemir; Keskin, Haluk

    2012-09-01

    The stability of the bone-implant interface is required for the long-term favorable clinical outcome of implant-supported prosthetic rehabilitation. The implant failures that occur after the functional loading are mainly related to biomechanical factors. Micro movements and vibrations due to occlusal forces can lead to mechanical complications such as loosening of the screw and fractures of the abutment or implants. The aim of this study was to investigate the strain distributions in the connection areas of different implant-abutment connection systems under similar loading conditions. Five different implant-abutment connection designs from 5 different manufacturers were evaluated in this study. The investigation was performed with software using the finite element method. The geometrical modeling of the implant systems was done with CATIA virtual design software. The MSC NASTRAN solver and PATRAN postprocessing program were used to perform the linear static solution. According to the analysis, the implant-abutment connection system with external hexagonal connection showed the highest strain values, and the internal hexagonal implant-abutment connection system showed the lowest strain values. Conical + internal hexagonal and screw-in implant abutment connection interface is more successful than other systems in cases with increased vertical dimension, particularly in the posterior region.

  11. Color variation induced by abutments in the superior anterior maxilla: an in vitro study in the pig gingiva

    Science.gov (United States)

    Atash, Ramin

    2016-01-01

    PURPOSE The aim of this work is to evaluate different types of materials used for making implant abutments, by means of an in vitro study and a review of the literature, in order to identify the indications for a better choice of an implant-supported restoration in the anterior section. MATERIALS AND METHODS 5 implant abutments were tested in a random order in the superior anterior maxilla of pig gingiva (n = 8): titanium dioxide (Nobel Biocare); zirconium dioxide, Standard BO shade (Nobel Biocare, Kloten, Switzerland); zirconium dioxide, Light BI shade (Nobel Biocare); zirconium dioxide, Intense A 3.5 shade (Nobel Biocare); and aluminium oxide. Each abutment was tested for 2 mm and 3 mm thickness. To determine color variation, VITA Easyshade Advance spectrophotometer (Vita Zahnfabrik, Bad Sackingen, Germany) was used. RESULTS Results showed that the color variation induced by the abutment would be affected by the abutment material and gingival thickness, when the gingival thickness is 2 mm. All materials except zirconium dioxide (Standard shade) caused a visible change of color. Then, as the thickness of the gingiva increased to 3 mm, the color variation was attenuated in a significant manner and became invisible for all types of abutments, except those made of aluminium oxide. CONCLUSION Zirconium dioxide is the material causing the lowest color variation at 2 mm and at 3 mm, whereas aluminium oxide causes the highest color variation no matter the thickness. PMID:28018559

  12. The Impact of the Crown-Root Ratio on Survival of Abutment Teeth for Dentures.

    Science.gov (United States)

    Tada, S; Allen, P F; Ikebe, K; Zheng, H; Shintani, A; Maeda, Y

    2015-09-01

    Crown-root ratio (CRR) is commonly recorded when planning prosthodontic procedures. However, there is a lack of longitudinal clinical data evaluating the association between CRR and tooth survival. The aim of this longitudinal practice-based study was to assess the impact of CRR on the survival of abutment teeth for removable partial dentures (RPDs). Data were collected from 147 patients provided with RPDs at a dental hospital in Japan. In total, 236 clasp-retained RPDs and 856 abutment teeth were analyzed. Survival of abutment teeth was assessed using Kaplan-Meier methods and Cox's proportional hazard (PH) regression. The Cox PH regression was used to assess the prognostic significance of initial CRR value with adjustments for clinically relevant factors, including age, sex, frequency of periodontal maintenance programs, occlusal support area, type of abutment tooth, status of endodontic treatment, and probing pocket depth. Abutment teeth were divided into 1 of 5 risk groups according to CRR: A (≤0.75), B (0.76-1.00), C (1.01-1.25), D (1.26-1.50) and E (≥1.51). The 7-year survival rate was 89.1% for group A, 85.9% for group B, 86.5% for group C, 76.9% for group D, and 46.7% for group E. The survival curves of groups A, B, and C were illustrated to be quite similar and favorable. The multivariable analysis treating CRR as a continuous variable allowed estimation of the hazard ratio at any specific CRR value. When CRR = 0.80 was set as a reference, the estimated hazard ratio was 0.58 for CRR = 0.50 (95% confidence interval [CI], 0.36-0.91), 1.13 for CRR = 1.00 (95% CI, 0.93-1.37), 1.35 for CRR = 1.25 (95% CI, 1.02-1.80), 1.53 for CRR = 1.50 (95% CI, 1.15-2.08), or 1.95 for CRR = 2.00 (95% CI, 1.44-2.65). These practice-based longitudinal data provide information to improve the evidence-based prognosis of teeth in providing prosthodontic procedures.

  13. Biocompatibility study of lithium disilicate and zirconium oxide ceramics for esthetic dental abutments

    Science.gov (United States)

    2016-01-01

    Purpose The increasing demand for esthetically pleasing results has contributed to the use of ceramics for dental implant abutments. The aim of this study was to compare the biological response of epithelial tissue cultivated on lithium disilicate (LS2) and zirconium oxide (ZrO2) ceramics. Understanding the relevant physicochemical and mechanical properties of these ceramics will help identify the optimal material for facilitating gingival wound closure. Methods Both biomaterials were prepared with 2 different surface treatments: raw and polished. Their physicochemical characteristics were analyzed by contact angle measurements, scanning white-light interferometry, and scanning electron microscopy. An organotypic culture was then performed using a chicken epithelium model to simulate peri-implant soft tissue. We measured the contact angle, hydrophobicity, and roughness of the materials as well as the tissue behavior at their surfaces (cell migration and cell adhesion). Results The best cell migration was observed on ZrO2 ceramic. Cell adhesion was also drastically lower on the polished ZrO2 ceramic than on both the raw and polished LS2. Evaluating various surface topographies of LS2 showed that increasing surface roughness improved cell adhesion, leading to an increase of up to 13%. Conclusions Our results demonstrate that a biomaterial, here LS2, can be modified using simple surface changes in order to finely modulate soft tissue adhesion. Strong adhesion at the abutment associated with weak migration assists in gingival wound healing. On the same material, polishing can reduce cell adhesion without drastically modifying cell migration. A comparison of LS2 and ZrO2 ceramic showed that LS2 was more conducive to creating varying tissue reactions. Our results can help dental surgeons to choose, especially for esthetic implant abutments, the most appropriate biomaterial as well as the most appropriate surface treatment to use in accordance with specific clinical

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

    Science.gov (United States)

    López-Píriz, Roberto; Solá-Linares, Eva; Granizo, Juan J; Díaz-Güemes, Idohia; Enciso, Silvia; Bartolomé, José F; Cabal, Belén; Esteban-Tejeda, Leticia; Torrecillas, Ramón; Moya, José S

    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 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.

  15. 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.

  16. The Effect of abutment wall modification, filling material & copying design on retention of cement retained implant supported crown

    Directory of Open Access Journals (Sweden)

    Shima Aalaei

    2016-12-01

    Full Text Available Background and aim: Factors which can effect of tooth supported crowns are well known. On the other side, low information are existed about retention of implant supported crowns. The aim of the present study was to evaluate the effect of abutment wall modification, filling material & copying design on retention of cement retained implant supported crown. Materials and methods: In this study, 4 straight abutments were attached to their implant analogues and were embedded in the acrylic resin block. Abutments were modified to one, two, three and four walls. Then, two type copying were made: conventional and with metal extension in two screw access cavity. Access cavities were filled incompletely by three methods: copying with extension spread into the access cavity without material and conventional copying with polytetrafluoroethylene (PTFE or composite. Then cemented with temporary agent (TempBond. Required tensile force for separation of copying was measured by universal testing machine. Data were analyzed using ANOVA as statistical test. Results: About findings of this research, no significant difference were detected among two methods of filling of access cavity and engaging screw access channel (P>0.05. Four wall abutment shown significantly higher retention than the others (P<0.05 and three other abutments have no significant difference in retention. Conclusion: The type of filling material of access cavity (PTFE and composite and engaging of the copying design have no significant effects on the cemented retained of implant supported restoration but existence of all four septums increase the veneer retention significantly.

  17. 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.

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

    DEFF Research Database (Denmark)

    Hosseini, Mandana

    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...... 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...

  19. 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.

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

    Science.gov (United States)

    Wahl, Carlos; França, Fabiana Mantovani Gomes; Brito, Rui Barbosa; Basting, Roberta Tarkany; Smanio, Henrique

    2008-01-01

    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, 5 degrees C +/- 2 degrees to 55 degrees C +/- 2 degrees) 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 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.

  1. 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.

  2. Bacterial Leakage and Microgap along Implant-Abutment Connection in Three Different Implant Systems

    Directory of Open Access Journals (Sweden)

    Farshad Bajoghli

    2016-11-01

    Full Text Available A microgap between implant and abutment connection can act as a bacterial source and cause inflammation, even endanger Osseointegration and subsequently change clinical and histological parameters. The goal of this study was to evaluate the microgap and microbial leakage of implant-abutment connection in three different implant systems. In this experimental study, 28 implants in 3 groups (10 Zimmer with conical connection of 8 degrees, 10 Dentium with conical connection of 11 degrees, 8 Test implants with conical connection of 16 degrees were used. Microleakage of Escherichia coli was assessed at intervals of 5, 24, 48 hours and 2 weeks. Microgap was measured at 4 random points by scanning electron microscope. Data were analysed by Spss version 22 and kruskal-Wallis, Mann-Whitney, Chi- square, Kaplan- Meier tests. (α=0.5 Mean microgap was 4.8μm (±2.2 in Zimmer group, 3.1μm (±1.4 in Implantium group and 16.9μm (±8.7 in test group. After 2 weeks from start of the study, 20 percent of Zimmer and Dentium implants and 25 percent of test implant showed microleakage. Microleakage between Zimmer and Dentium implants was not significant; however, there was a significant difference between test implant and other groups. Microbial leakage was observed in all three implant systems. Although; there were differences in microgap between three groups, Microbial leakage was not statistically significant.

  3. 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

  4. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  6. Nutrients and bioactive compounds content of Baillonella toxisperma, Trichoscypha abut and Pentaclethra macrophylla from Cameroon.

    Science.gov (United States)

    Fungo, Robert; Muyonga, John; Kaaya, Archileo; Okia, Clement; Tieguhong, Juius C; Baidu-Forson, Jojo J

    2015-07-01

    Baillonella toxisperma, Pentaclethra macrophylla and Trichoscypha abut are important foods for communities living around forests in Cameroon. Information on the nutritional value and bioactive content of these foods is required to establish their contribution to the nutrition and health of the communities. Samples of the three foods were obtained from four villages in east and three villages in south Cameroon. The foods were analyzed for proximate composition, minerals and bioactive content using standard chemical analysis methods. T. abut was found to be an excellent source of bioactive compounds; flavonoids (306 mg/100 g), polyphenols (947 mg/100 g), proanthocyanins (61.2 mg/100 g), vitamin C (80.05 mg/100 g), and total oxalates (0.6 mg/100 g). P. macrophylla was found to be a rich source of total fat (38.71%), protein (15.82%) and total fiber (17.10%) and some bioactive compounds; vitamin E (19.4 mg/100 g) and proanthocyanins (65.0 mg/100 g). B. toxisperma, was found to have high content of carbohydrates (89.6%), potassium (27.5 mg/100 g) and calcium (37.5 mg/100 g). Flavonoids, polyphenols, vitamins C and E are the main bioactive compounds in these forest foods. The daily consumption of some of these fruits may coffer protection against some ailments and oxidative stress. Approximately 200 g of either B. toxisperma or P. macrophylla, can supply 100% iron and zinc RDAs for children aged 1-3 years, while 300 g of the two forest foods can supply about 85% iron and zinc RDAs for non-pregnant non-lactating women. The three foods provide 100% daily vitamins C and E requirements for both adults and children. The results of this study show that Baillonella toxisperma, Pentaclethra macrophylla and Trichoscypha abut can considerably contribute towards the human nutrient requirements. These forest foods also contain substantial levels of health promoting phytochemicals notably flavonoids, polyphenols, vitamins C and E. These foods therefore have

  7. 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.

  8. 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.

  9. Effect of using nano and micro airborne abrasive particles on bond strength of implant abutment to prosthesis.

    Science.gov (United States)

    Rismanchian, Mansour; Davoudi, Amin; Shadmehr, Elham

    2015-01-01

    Connecting prostheses to the implant abutments has become a concern and achieving a satisfactory retention has been focused in cement-retention prostheses recently. Sandblasting is a method to make a roughened surface for providing more retention. The aim of this study was to compare effects of nano and micro airborne abrasive particles (ABAP) in roughening surface of implant abutments and further retention of cemented copings. Thirty Xive abutments and analogues (4.5 D GH1) were mounted vertically in self-cured acrylic blocks. Full metal Ni-Cr copings with a loop on the top were fabricated with appropriate marginal adaptation for each abutment. All samples were divided into 3 groups: first group (MPS) was sandblasted with 50 µm Al2O3 micro ABAP, second group (NSP) was sandblasted with 80 nm Al2O3 nano ABAP, and the third group (C) was assumed as control. The samples were cemented with provisional cement (Temp Bond) and tensile bond strength of cemented copings was evaluated by a universal testing machine after thermic cycling. The t test for independent samples was used for statistical analysis by SPSS software (version 15) at the significant level of 0.05. Final result showed significant difference among all groups (pABAP is an efficient way for increasing bond strengths significantly, but it seems that micro ABAP was more effective.

  10. Early bacterial colonization and soft tissue health around zirconia and titanium abutments : an in vivo study in man

    NARCIS (Netherlands)

    Brakel, Ralph van; Cune, Marco S.; Winkelhoff, Arie Jan van; Putter, Cornelis de; Verhoeven, Jan Willem; Reijden, Wil van der

    2011-01-01

    AIM: To compare the early bacterial colonization and soft tissue health of mucosa adjacent to zirconia (ZrO(2)) and titanium (Ti) abutment surfaces in vivo. MATERIALS AND METHODS: Twenty edentulous subjects received two endosseous mandibular implants. The implants were fitted with either a ZrO(2) or

  11. Early bacterial colonization and soft tissue health around zirconia and titanium abutments: an in vivo study in man

    NARCIS (Netherlands)

    van Brakel, R.; Cune, M.S.; van Winkelhoff, A.J.; de Putter, C.; Verhoeven, J.W.; van der Reijden, W.

    2011-01-01

    Aim: To compare the early bacterial colonization and soft tissue health of mucosa adjacent to zirconia (ZrO2) and titanium (Ti) abutment surfaces in vivo. Materials and methods: Twenty edentulous subjects received two endosseous mandibular implants. The implants were fitted with either a ZrO2 or a T

  12. 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.

  13. The use of endodontically treated and/or fiber post-retained teeth as abutments for fixed partial dentures.

    Science.gov (United States)

    Akman, Serhan; Akman, Melek; Eskitaşcıoğlu, Gürcan; Belli, Sema

    2012-10-01

    The purpose of this in vitro study was to evaluate the effect of endodontic treatment with or without fiber-post restorations on the fracture strength of abutment teeth under fixed partial dentures (FPDs). Seventy extracted premolar and canine teeth were used. Groups of fiber-post-retained and root-filled teeth were endodontically treated. The teeth were embedded in an acrylic resin perpendicular to the horizontal plane to create fixed partial dentures. The following groups were created using different abutments: (1) sound (S) canine/S premolar, (2) S canine/endodontically treated (ET) premolar, (3) ET canine/S premolar, (4) ET canine/ET premolar, (5) S canine/fiber-post-restored (FPR) premolar, (6) FPR canine/S premolar, and (7) FPR canine/FPR premolar. Each tooth was prepared for a complete-coverage full-metal crown. Impressions were taken; metal frameworks were fabricated and cemented. The samples were exposed to 5,000 cycles of thermomechanical fatigue and loaded compressively until fracture (2 mm/min). The data were statistically analyzed using (Kruskal-Wallis test, α = 0.05). No significant difference was found among the mean fracture strengths of the groups (p = 0.696). There were distinct differences in failure patterns. All of the fracture types were horizontal, and neither vertical nor non-restorable root fractures were recorded. Premolars seemed to be a critical abutment compared to canines when they were sound under FPDs. The percentage of cervical fractures was high in endodontically treated teeth when compared to post-retained groups. In case of post-debonding, the abutment fracture did not occur. When root-filled teeth are used as abutments for FPDs, fiber-post restorations or the creation of abutments from similar structures (ET/ET or FPR/FPR) results in improved conservation of root structure under loading when compared to the abutments from different structures (S/ET, ET/S, FPR/S, S/FPR).

  14. 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.

  15. 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...

  16. 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...

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

    Science.gov (United States)

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

    2016-01-01

    Abstract 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 abutments with respect to preservation of marginal bone level and several clinical and patient‐based outcome measures. Material and Methods Fifty participants with a missing premolar were included and randomly assigned to standard (ZirDesign, DentsplySirona Implants, Mölndal, Sweden) or computer aided design/computer aided manufacturing (CAD/CAM) customized (Atlantis, DentsplySirona Implants, Mölndal, Sweden) zirconia abutment therapy. Peri‐implant bone level (primary outcome), Plaque‐index, calculus formation, bleeding on probing, gingiva index, probing pocket depth, recession, appearance of soft tissues and patients' contentment were assessed shortly after placement and one year later. Results No implants were lost and no complications related to the abutments were observed. Statistically significant differences between stock and CAD/CAM customized zirconia abutments could not be demonstrated for any of the operationalized variables. Conclusion The use of a CAD/CAM customized zirconia abutment in single tooth replacement of a premolar is not associated with an improvement in clinical performance or patients' contentment when compared to the use of a stock zirconia abutment. PMID:27476829

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. "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).

  3. 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 (Pcomposite 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

  4. 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.

  5. 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

  6. 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.

  7. Custom CAD-CAM healing abutment and impression coping milled from a poly(methyl methacrylate) block and bonded to a titanium insert.

    Science.gov (United States)

    Proussaefs, Periklis

    2016-11-01

    This article describes a technique in which a custom-made computer-aided design and computer-aided manufacturing (CAD-CAM) healing abutment milled from a poly(methyl methacrylate) (PMMA) block is fabricated and bonded to a titanium metal insert. An impression is made during dental implant surgery, and the CAD-CAM custom-made healing abutment is fabricated before second-stage surgery while appropriate healing time is allowed for the dental implant to osseointegrate. The contours of the healing abutment are based on the contours of a tentatively designed definitive prosthesis. The healing tissue obtains contours that will be compatible with the contours of the definitive prosthesis. After the milling process is complete, a titanium metal insert is bonded to the healing abutment. Placement of the custom-made CAD-CAM healing abutment at second-stage surgery allows the tissue to obtain contours similar to those of the definitive prosthesis. A custom-made CAD-CAM impression coping milled from a PMMA block and with a titanium insert is used for the definitive impression after the soft tissue has healed. This technique allows guided soft tissue healing by using a custom-made CAD-CAM healing abutment and impression coping.

  8. Fracture resistance and analysis of stress distribution of implant-supported single zirconium ceramic coping combination with abutments made of different materials.

    Science.gov (United States)

    Firidinoğlu, Kadir; Toksavul, Suna; Toman, Muhittin; Sarikanat, Mehmet; Nergiz, Ibrahim

    2012-08-01

    The purpose of this study was to compare the fracture resistance and fracture mode of single implant-zirconium coping combinations using zirconium and titanium abutments and to analyze the stress distribution pattern using three-dimensional finite elements analysis. Twenty implants with titanium and zirconium abutments were randomly divided into two groups (n = 10) and into resin blocks. Zirconium copings were cemented onto the abutments. The specimens were loaded with 135° angles to the long axis and the load values at the moment of failure were recorded using a universal test machine. Stress levels were calculated according to the maximum Von Mises criteria. The fracture resistances for titanium and zirconium abutment groups were 525.65 N and 514.05 N, respectively. No significant differences were observed between two groups regarding the fracture resistance levels. The maximum Von Mises equivalent stress concentrated on zirconium copings in both of the groups. Implant-abutment-ZrO2 coping combination has the potential to withstand physiological occlusal forces in the anterior region. Three-dimensional finite elements analysis results of the implant-abutment-ZrO2 coping combination is compatible with the results of fracture resistance.

  9. Grinding efficiency of abutment tooth with both dentin and core composite resin on axial plane.

    Science.gov (United States)

    Miho, Otoaki; Sato, Toru; Matsukubo, Takashi

    2015-01-01

    The purpose of this study was to evaluate grinding efficiency in abutment teeth comprising both dentin and core composite resin in the axial plane. Grinding was performed over 5 runs at two loads (0.5 or 0.25 N) and two feed rates (1 or 2 mm/sec). The grinding surface was observed with a 3-D laser microscope. Tomographic images of the grinding surfaces captured perpendicular to the feed direction were also analyzed. Using a non-ground surface as a reference, areas comprising only dentin, both dentin and core composite resin, or only core composite resin were analyzed to determine the angle of the grinding surface. Composite resins were subjected to the Vickers hardness test and scanning electron microscopy. Data were statistically analyzed using a one-way analysis of variance and multiple comparison tests. Multiple regression analysis was performed for load, feed rate, and Vickers hardness of the build-up material depending on number of runs. When grinding was performed at a constant load and feed rate, a greater grinding angle was observed in areas comprising both dentin and composite resin or only composite resin than in areas consisting of dentin alone. A correlation was found between machinability and load or feed rate in areas comprising both dentin and composite resin or composite resin alone, with a particularly high correlation being observed between machinability and load. These results suggest that great caution should be exercised in a clinical setting when the boundary between the dentin and composite resin is to be ground, as the angle of the grinding surface changes when the rotating diamond point begins grinding the composite resin.

  10. 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

  11. 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.

  12. 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

  13. 氧化锆全瓷修复体与氧化锆基台的适合性%Fit accuracy between zirconia abutments and zirconia crowns

    Institute of Scientific and Technical Information of China (English)

    李伟; 杨建军; 王大山; 刘广源; 杨振; 李婷

    2012-01-01

    BACKGROUND: In recent years, development of zirconia abutments has become a hotspot. The zirconia all-ceramic crowns and zirconia abutments restoration are recognized by many clinicians and patients because of their excellent aesthetic restoration effects, and the fit accuracy between them is a key factor for the implant restoration.OBJECTIVE: To develop the zirconia abutments and to study the fitness of the interface between the zirconia abutments and zirconia crowns.METHODS: Nanometer zirconia powder was used to manufacture zirconia abutments by injection molding. Five zirconia abutments and five titanium abutments were divided into two groups: Zirconia abutments-zirconia crowns group and titanium abutments-Co-Cr alloy based PFM crowns group. In the zirconia abutments-zirconia crowns group, five zirconia crowns were made upon the zirconia abutments by computer aided design and computer aided manufacturing. While in titanium abutments-Co-Cr alloy based PFM crowns group, five Co-Cr alloy based PFM crowns were made upon the titanium abutments by finished plastic cap casting. The finished crowns were inserted onto the abutments respectively to observe whether the crowns were inserted onto the abutments completely. Then the microgap models of the interface between abutments and crowns were made using silicone rubber impression, afterwards, to repair and cut these models. Microgap pictures were observed and collected by scanning electron microscope, and the microgap was tested by Digora Optime.RESULTS AND CONCLUSION: The insertion rate of the two groups was both 100%. The microgaps in the axial surface and cervical part of zirconia abutments-zirconia crowns group were significantly lower than those of titanium abutments-Co-Cr alloy based PFM crowns group (P < 0.05). The interface between zirconia abutments and zirconia crowns shows a good fitness and provides a reliable scientific basis for the clinical application.%背景:近年来,氧化锆基台的研制及临床

  14. Leakage of Microbial Endotoxin through the Implant-Abutment Interface in Oral Implants: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    Rhoodie Garrana

    2016-01-01

    Full Text Available Background. Endotoxin initiates osteoclastic activity resulting in bone loss. Endotoxin leakage through implant abutment connections negatively influences peri-implant bone levels. Objectives. (i To determine if endotoxin can traverse different implant-abutment connection (IAC designs; (ii to quantify the amount of endotoxins traversing the IAC; (iii to compare the in vitro comportments of different IACs. Materials and Methods. Twenty-seven IACs were inoculated with E. coli endotoxin. Six of the twenty-seven IACs were external connections from one system (Southern Implants and the remaining twenty-one IACs were made up of seven internal IAC types from four different implant companies (Straumann, Ankylos, and Neodent, Southern Implants. Results. Of the 27 IACs tested, all 6 external IACs leaked measurable amounts of endotoxin. Of the remaining 21 internal IACs, 9 IACs did not show measurable leakage whilst the remaining 12 IACs leaked varying amounts. The mean log endotoxin level was significantly higher for the external compared to internal types (p=0.015. Conclusion. Within the parameters of this study, we can conclude that endotoxin leakage is dependent on the design of the IAC. Straumann Synocta, Straumann Cross-fit, and Ankylos displayed the best performances of all IACs tested with undetectable leakage after 7 days. Each of these IACs incorporated a morse-like component in their design. Speculation still exists over the impact of IAC endotoxin leakage on peri-implant tissues in vivo; hence, further investigations are required to further explore this.

  15. Leakage of Microbial Endotoxin through the Implant-Abutment Interface in Oral Implants: An In Vitro Study.

    Science.gov (United States)

    Garrana, Rhoodie; Mohangi, Govindrau; Malo, Paulo; Nobre, Miguel

    2016-01-01

    Background. Endotoxin initiates osteoclastic activity resulting in bone loss. Endotoxin leakage through implant abutment connections negatively influences peri-implant bone levels. Objectives. (i) To determine if endotoxin can traverse different implant-abutment connection (IAC) designs; (ii) to quantify the amount of endotoxins traversing the IAC; (iii) to compare the in vitro comportments of different IACs. Materials and Methods. Twenty-seven IACs were inoculated with E. coli endotoxin. Six of the twenty-seven IACs were external connections from one system (Southern Implants) and the remaining twenty-one IACs were made up of seven internal IAC types from four different implant companies (Straumann, Ankylos, and Neodent, Southern Implants). Results. Of the 27 IACs tested, all 6 external IACs leaked measurable amounts of endotoxin. Of the remaining 21 internal IACs, 9 IACs did not show measurable leakage whilst the remaining 12 IACs leaked varying amounts. The mean log endotoxin level was significantly higher for the external compared to internal types (p = 0.015). Conclusion. Within the parameters of this study, we can conclude that endotoxin leakage is dependent on the design of the IAC. Straumann Synocta, Straumann Cross-fit, and Ankylos displayed the best performances of all IACs tested with undetectable leakage after 7 days. Each of these IACs incorporated a morse-like component in their design. Speculation still exists over the impact of IAC endotoxin leakage on peri-implant tissues in vivo; hence, further investigations are required to further explore this.

  16. Fixture-abutment connection surface and micro-gap measurements by 3D micro-tomographic technique analysis

    Directory of Open Access Journals (Sweden)

    Deborah Meleo

    2012-01-01

    Full Text Available X-ray micro-tomography (micro-CT is a miniaturized form of conventional computed axial tomography (CAT able to investigate small radio-opaque objects at a-few-microns high resolution, in a nondestructive, non-invasive, and tri-dimensional way. Compared to traditional optical and electron microscopy techniques, which provide two-dimensional images, this innovative investigation technology enables a sample tri-dimensional analysis without cutting, coating or exposing the object to any particular chemical treatment. X-ray micro-tomography matches ideal 3D microscopy features: the possibility of investigating an object in natural conditions and without any preparation or alteration; non-invasive, non-destructive, and sufficiently magnified 3D reconstruction; reliable measurement of numeric data of the internal structure (morphology, structure and ultra-structure. Hence, this technique has multi-fold applications in a wide range of fields, not only in medical and odontostomatologic areas, but also in biomedical engineering, materials science, biology, electronics, geology, archaeology, oil industry, and semi-conductors industry. This study shows possible applications of micro-CT in dental implantology to analyze 3D micro-features of dental implant to abutment interface. Indeed, implant-abutment misfit is known to increase mechanical stress on connection structures and surrounding bone tissue. This condition may cause not only screw preload loss or screw fracture, but also biological issues in peri-implant tissues.

  17. 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

  18. 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.

  19. 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.

  20. A comparative study of inter-abutment distance of dies made from full arch dual-arch impression trays with those made from full arch stock trays: An in vitro study

    OpenAIRE

    Reddy Jagan; Prashanti E; Kumar G; Suresh Sajjan M; Mathew Xavier

    2009-01-01

    Objectives: The dual-arch impression technique is convenient in that it makes the required maxillary and mandibular impressions, as well as the inter-occlusal record in one procedure. The accuracy of inter-abutment distance in dies fabricated from dual-arch impression technique remains in question because there is little information available in the literature. Materials and Methods: This study was conducted to evaluate the accuracy of inter-abutment distance in dies obtained from full ar...

  1. 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.

  2. Radiofrequency ablation of the liver abutting stomach: In vivo comparison of gastric injury before and after intragastric saline administration in a porcine model

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jongmee [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-gu, Seoul 135-710 (Korea, Republic of); Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine, 80 Guro-dong, Guro-gu, Seoul 152-703 (Korea, Republic of); Lim, Hyo K. [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-gu, Seoul 135-710 (Korea, Republic of)], E-mail: hyokeun.lim@samsung.com; Choi, Dongil; Kim, Seung Hoon [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-gu, Seoul 135-710 (Korea, Republic of); Min, Kwangseon [Department of Pathology, Hallym Medical Center, College of Medicine, University of Hallym, 896 Pyeongchon-dong, Dongan-gu, Anyang-si, Gyeonggi-do 431-070 (Korea, Republic of); Jeon, Yong Hwan [Department of Radiology, Kangwon National University College of Medicine, 192-1 Hyoja 2-dong, Chuncheon, Kangwon-do 200-701 (Korea, Republic of)

    2009-10-15

    Purpose: To compare the in vivo gastric injury observed during radiofrequency (RF) ablation of the liver abutting the stomach before and after the intragastric administration of chilled saline. Materials and methods: Twenty RF ablation zones were created in the livers of 10 pigs with a 1-cm-exposed active tip of an internally cooled electrode under ultrasound guidance for 10 min. Ten RF ablation zones were created before (non-saline group) and after (saline group) the intragastric administration of approximately 1000 mL of chilled saline, and 20 RF ablation zones were made in the posterior part of the left lobe abutting the stomach. The frequency and severity of the thermal injury observed in the stomach of the two groups were compared histologically. Results: All the resected gastric specimens showed thermal injuries of varying degrees of severity. The largest diameter of the gastric injury was significantly smaller in the saline group (mean 1.5 cm; range 1.3-1.8 cm) than in the non-saline group (mean 2.1 cm; range 1.8-2.4 cm) (p = 0.000). The saline group showed significantly less thermal injury to the muscular layer of the gastric wall by the histopathology (p = 0.033). Conclusions: The intragastric administration of chilled saline might be a useful technique for reducing the severity of gastric injury during RF ablation of the liver abutting the stomach.

  3. 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.

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

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    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.

  5. Four-year clinical results of fixed dental prostheses with zirconia substructures (Cercon): end abutments vs. cantilever design.

    Science.gov (United States)

    Wolfart, Stefan; Harder, Sönke; Eschbach, Stefanie; Lehmann, Frank; Kern, Matthias

    2009-12-01

    The purpose of this prospective study was to evaluate the clinical outcome of three- to four-unit posterior all-ceramic fixed dental prostheses (FDPs) made of yttria-stabilized tetragonal zirconia-polycrystal ceramic frameworks (CerconBase; Degudent). Fifty-eight restorations were placed in 48 patients. Twenty-four FDPs had an end abutment design (EAD) replacing 3 premolars and 21 molars. Thirty-four FDPs had a cantilever design (CD) replacing 11 premolars and 23 molars. The frameworks had a minimum proximal connector dimension of 3 x 3 mm. The fixed dental prostheses were cemented with glass-ionomer cement after air-abrading the inner crown surfaces. Three FDPs were defined as drop-outs. The mean observation period was 48 +/- 7 months for the EAD (21 patients/24 FDPs) and 50 +/- 14 months for the CD (25 patients/31 FDPs). The 4-yr survival rate, according to the Kaplan-Meier analyses, was 96% for the EAD and 92% for the CD. The technical complication rate was 13% for the EAD and 12% for the CD, and the biological complication rate was 21% for the EAD and 15% for the CD. For none of the analyses were significant differences found between both groups. After 4 yr the clinical outcome of three- to four-unit posterior FDPs with EAD and CD was promising.

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

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    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.

  7. 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

  8. A comparative study of inter-abutment distance of dies made from full arch dual-arch impression trays with those made from full arch stock trays: An in vitro study

    Directory of Open Access Journals (Sweden)

    Reddy Jagan

    2009-01-01

    Full Text Available Objectives: The dual-arch impression technique is convenient in that it makes the required maxillary and mandibular impressions, as well as the inter-occlusal record in one procedure. The accuracy of inter-abutment distance in dies fabricated from dual-arch impression technique remains in question because there is little information available in the literature. Materials and Methods: This study was conducted to evaluate the accuracy of inter-abutment distance in dies obtained from full arch dual-arch trays with those obtained from full arch stock metal trays. Results and Conclusion: The metal dual-arch trays showed better accuracy followed by the plastic dual-arch and stock dentulous trays, respectively, though statistically insignificant. The pouring sequence did not have any effect on the inter-abutment distance statistically, though pouring the non-working side of the dual-arch impression first showed better accuracy.

  9. 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.

  10. 小湾高拱坝拱座稳定三维极限分析%Xiaowan High Arch Dam Abutment Stability 3- D Limit Analysis

    Institute of Scientific and Technical Information of China (English)

    陈祖煜; 汪小刚; 王剑

    2000-01-01

    小湾岩体存在两组垂直结构面和一组倾向河道的卸荷裂隙。拱座稳定存在着沿拱推力方向和重力方向组合的空间滑动模式。本文首先介绍了一个建立在塑性力学上限定理基础上的边坡稳定分析三维极限分析方法,并使用这一方法计算小湾拱座的稳定安全系数,获得比较符合实际的稳定分析成果。%There are two sets of vertical shearing planes and one set of relaxed fissures dipping towards the river course in the rock mass at the Xiaowan dam site. In terms of the arch abutment stability the spatial sliding patterns created by their combination along the arch thrust and gravity directions should be considered. This paper gives a presentation of the 3- D limit analysis method developed on the basis of the plasticity mechanics upper limit theorem for slope stability analysis, and of the stability safety factor of the Xiaowan arch abutment calculated using this method which could give stability analysis results conforming to the actual conditions.

  11. Development Aad Application on Stability Analysis of Abutment of ARCH DAM%拱坝坝肩稳定性分析程序开发与应用

    Institute of Scientific and Technical Information of China (English)

    赖雅琳

    2011-01-01

    In order to resolve the problems of heavy workload and repetitive calculation on stability analysis of abutment of arch dam, the VBA language was used to develop the software of stability analysis of abutment of arch dam. The program includes two sections, one section of which is to create communication between VBA and EXCEL then extract data, and the other section of which is to realize interactive operation between VBA and AutoCAD to induce least stability safety factor. A certain arch dam was chosen in CAD map as case study and the least stability safety factor can be yielded by calculation. The results show that this program runs safely and steadily which design criteria.%采用VBA语言编程开发拱坝坝肩稳定分析程序.程序包括建立VBA与EXCEL通信并提取相关数据,VBA与CAD交互操作求最小稳定安全系数两部分.应用该系统时,用户只需要输入或选择程序默认参数数值,并在CAD地形图文件上选取若干实体,即可自动计算出对应高程的拱坝坝肩最小稳定安全系数.工程实例结果显示,程序运行安全可靠,符合设计标准.

  12. A three-dimensional finite element analysis of a passive and friction fit implant abutment interface and the influence of occlusal table dimension on the stress distribution pattern on the implant and surrounding bone

    OpenAIRE

    Sarfaraz, Hasan; Paulose, Anoopa; Shenoy, K. Kamalakanth; Hussain, Akhter

    2015-01-01

    Aims: The aim of the study was to evaluate the stress distribution pattern in the implant and the surrounding bone for a passive and a friction fit implant abutment interface and to analyze the influence of occlusal table dimension on the stress generated. Materials and Methods: CAD models of two different types of implant abutment connections, the passive fit or the slip-fit represented by the Nobel Replace Tri-lobe connection and the friction fit or active fit represented by the Nobel activ...

  13. Short implants with a nanometer-sized CaP surface provided with either a platform-switched or platform-matched abutment connection in the posterior region : a randomized clinical trial

    NARCIS (Netherlands)

    Telleman, G.; Meijer, H. J. A.; Vissink, A.; Raghoebar, G. M.

    2013-01-01

    ObjectiveTo assess the performance of short nanorough implants (8.5mm in length) provided with either a platform-matched or a platform-switched implant-abutment connection, placed in the resorbed posterior region of partially dentate patients. Materials and MethodsA total of 149 implants with a dual

  14. Efficacy of antibacterial sealing gel and O-ring to prevent microleakage at the implant abutment interface: an in vitro study.

    Science.gov (United States)

    Nayak, Aishwarya Gajanan; Fernandes, Aquaviva; Kulkarni, Raghavendra; Ajantha, Ganavalli Subramanyam; Lekha, Krishnapillai; Nadiger, Ramesh

    2014-02-01

    Gaps and hollow spaces at the implant abutment interface will act as a bacterial reservoir that may cause peri-implantitis. Hence, the sealing ability of O-ring (in addition to polysiloxane) and GapSeal (an antibacterial sealing gel) was evaluated. A total of 45 identical implant systems (ADIN Dental Implant Systems) were divided into 3 groups of 15 implants each: an unsealed group, a group sealed with O-rings, and a group sealed with GapSeal gel. The implant and abutment were gamma sterilized after assembly. Two implants from each group were randomly incubated in sterile brain heart infusion (BHI) broth tubes and checked for sterility. The remaining 13 implants were incubated in BHI broth inoculated with Enterococcus and incubated for 5 days. They were then removed from the tubes, dried aseptically, placed in 2% sodium hypochlorite solution for 30 minutes, and washed with sterile saline for 5 minutes. Next, the assembly was dried aseptically and put in sterile BHI broth tubes and incubated for 24 hours to check surface sterility. Keeping 2 implants as controls from each group, the remaining 11 implants were dismantled group-wise and placed in liquid BHI broth; the test tubes were then shaken thoroughly so that the broth would come in contact with all implant surfaces. The solution from this tube was poured on pre-prepared sterile agar plates and incubated for 24 hours. The colonies formed on the agar plate were then counted using a digital colony counter. The data thus obtained were subjected to statistical analysis by Kruskal-Wallis analysis of variance and Mann-Whitney U test. It was concluded that though microbial growth is seen in all the 3 groups, the least growth was seen in the GapSeal group followed by the O-ring group.

  15. 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

  16. 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.

  17. 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.

  18. Comparison of counteract compression properties of different ceramic crowns for implant abutment%不同基底材料的瓷修复体用于种植修复时抵抗压力载荷的比较

    Institute of Scientific and Technical Information of China (English)

    肖剑锐; 韩小宪; 林雪梅; 陈宇轩; 孔亮

    2012-01-01

    Objective To compare the counteract compression properties of different ceramic crowns for implant abutment. Methods Co-Cr alloy ceramic crowns, Titanium ceramic crowns, gold alloy ceramic crowns and whole ceramic crowns were made for the Ti-abutment and the abutment tooth in vitro (the control group). Cyclic loads were applied on the crowns and the Max loading frequencies were recorded when the ceramic showed cracks.Results The Max loading frequency in the abutment tooth crowns were 159.3±6.7,147.7±2.4,149.5±3.3 and 138.6±7.1 respectively, and those were 167.6±2.7,149.7±6.5,152.8±4.3 and 122.0±4.6 in the Ti-abutmenl crowns. The Co-Cr alloy ceramic crowns in Ti-abutment could endure more loading frequencies than in the abutment tooth (P<0.05), and the whole ceramic crowns showed the contrast (P<0.05). In the Ti-abutment, Co-Cr alloy ceramic crowns endured most loading frequencies, and the whole ceramic crowns showed the least (P<0.05). Conclusion For Ti-abutment, Co-Cr alloy ceramic crown showed the best counteract compression properties and whole ceramic crowns showed the worst.%目的 比较不同基底材料的瓷修复体用于种植修复时的抗压强度.方法 分别基于离体牙(对照组)和种植基台制作钴铬合金烤瓷、钛烤瓷、贵金属烤瓷(75%Au合金)和全瓷修复体,粘接后在咬合面进行循环加载,直至出现修复体瓷层破坏,记录最大加载次数.结果 四种修复体,用于离体基牙时出现破坏的最大加载次数(万次)分别为159.3±6.7,147.7±2.4,149.5±3.3和138.6±7.1;用于种植基台时分别为167.6±2.7,149.7±6.5,152.8±4.3和122.0±4.6.钴铬烤瓷修复用于种植基台时比用于离体基牙时可承受更多的加载次数(P<0.05),而全瓷修复体则相反(P<0.05);用于种植基台修复时,钴铬烤瓷承受加载次数较多,而全瓷修复体可承受的加载次数最少,均有统计学意义(P<0.05),钛烤瓷及贵金属烤瓷居中.结论 针对种植体基

  19. 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.

  20. 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.

  1. 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

  2. Heter-cycle abutted Cyclic Prefix based OFDM carrier frequency synchronization%一种基于异周期结构的OFDM频偏估计方法

    Institute of Scientific and Technical Information of China (English)

    饶志华; 邹国华; 郑纲

    2009-01-01

    本文设计了一种具有异周期毗邻结构的新型循环前缀(Heter-cycle abutted CP,HCA-CP),在此基础上提出了相应的OFDM 频偏估计算法.该异周期毗邻结构循环前缀由短循环前缀CP1和长循环前缀CP2两部分构成.采用该异周期毗邻结构的OFDM符号具有双周期特征,其中短循环前缀CP1对应的周期为整个循环前缀的长度L,长循环前缀CP2对应的周期为OFDM符号的数据长度N.论文中频偏估计方法利用短循环前缀CP1做相关运算获得整数倍频偏,利用长循环前缀CP2做相关运算获得引小数倍频偏,通过引入较短的CP1,牺牲极少的资源,可以有效克服现有频偏估计方法中的固定频偏估计范围的缺陷,同时具有频偏估计范围大,精度高的特点.

  3. 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。

  4. The Effect of Time Intervals on Heat Transfer to the Implant-Bone Interface during Preparation of a Titanium Abutment: An in Vitro Study

    Directory of Open Access Journals (Sweden)

    Raoofi S

    2015-09-01

    Full Text Available Statement of Problem: Thermal injury during dental implant placement and restoration is a clinical concern as it may cause bone damage and compromise osseointegration. The threshold level for heat-induced cortical bone necrosis is 47°C for 60 seconds. Objectives: To measure the amount of heat transferred to the implant-bone interface when a two-piece or one-piece abutment was prepared in vertical and horizontal direction using various time intervals. Materials and Methods: Three groups of samples (n = 24, one-piece and two-piece implant and natural teeth, were used in this study to compare the amount of heat transferred to the implant-bone interface. This study used cooling system in the 10, 20, 30, and 60 seconds time intervals. The Thermocouples (K type were attached to each sample at the crestal, middle and apical points. To have a similar condition with the oral cavity, each implant was embedded separately in transparent acrylic resin in a 37°C water bath. To have a constant cutting pressure, the turbine was fixed on the stable stand and a 100 g counterweight hanged to it. Then, the bath was fixed in front of it and cutting started at vertical and horizontal directions for 10, 20, 30, 60 seconds. Results: The maximum decrease from 37°C was observed in two-piece implant at the apical point (3.95°C after 60 seconds and the minimum decrease was seen in one-piece implant at the crestal point (0.6°C after 60 seconds. Also the minimum increase was observed in the natural teeth at the apical point (0.15°C at 10 seconds and the maximum temperature increase was seen in one-piece implant at the apical point (1.95°C at 20 seconds. Conclusions: Within the limitation of this study, it was concluded that to reduce the thermal damage on the bone tissue, an intermittent cut up to 20 seconds is acceptable. Cutting one-piece implant caused more heat transfer than that of two-piece implant

  5. 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.

  6. 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.

  7. Research on the impact analysis of Xiatun arch dam right abutment K6 karst cave and treatment plan%下屯拱坝右坝肩 K6溶洞影响分析及处理方案研究

    Institute of Scientific and Technical Information of China (English)

    王国香; 钱刚

    2016-01-01

    K6 karst cave is developed in 1140 ~1160m elevation of Xiatun arch dam right abutment.The cave is filled by clay and stones.The karst cave has larger scale,which is not beneficial for the stability of dam abutment.The karst cave has lower influence on the stability of dam abutment and downstream rocks according to analysis.The karst cave is excavated in order to improve the safety and reliability of the abutment.Concrete is backfilled,and concrete gravity pier is set.The above measures are introduced in the paper.%下屯水电站右坝肩在1140~1160m 高程发育 K6溶洞,洞内黏土夹块石充填,溶洞规模较大,对拱坝坝肩的稳定不利。经分析溶洞对拱坝坝肩及下游岩体稳定的影响较小,但为了提高坝肩的安全可靠性,对溶洞进行了清挖,并回填混凝土及设置了混凝土重力墩。本文对此加以介绍。

  8. 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

  9. 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

  10. 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

  11. Analysis of Local Stress at Transition Sections of Abutments in Large-span Steel-box Handle Basket Arch Bridges%大跨度钢箱提篮拱桥拱脚过渡段局部应力分析

    Institute of Scientific and Technical Information of China (English)

    户东阳; 何旭辉; 秦红禧

    2011-01-01

    以正在修建的某高速铁路提篮拱桥为背景,针对3个拱脚过渡段设计方案,应用大型通用软件ANSYS,分别建立全桥模型和拱脚局部模型,并对3个方案的拱脚过渡段的应力分布进行分析.可供类似桥梁设计施工参考.%Based on the handle basket arc bridge on some expressway under construction as background and aiming at three design plans for transition sections of abutments, this paper establishes full-scale model of the whole bridge and local model of abutment by means of large-scale universal software ANSYS, and analyzes stress distribution of transition sections of abutments in three plans. The analysis of this paper can be a reference for design of similar bridges.

  12. 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.

  13. 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.

  14. 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

  15. Three-dimensional finite element analysis of different abutment angles and loads of the maxillary central incisor%上颌中切牙角度基台不同载荷的三维有限元优化分析

    Institute of Scientific and Technical Information of China (English)

    陈小璇; 刘国强; 徐昕

    2015-01-01

    BACKGROUND:To optimize the oral implant design in the abutment angle has an important effect on bone resorption, and meanwhile, the high bite force from patients is also crucial to rebuild bone absorption. OBJECTIVE:To optimize the model design of the maxilary anterior teeth using Ansys Workbench 13.0 software and to investigate the stress size on the cortical and cancelous bone from different angled abutments and different loads of the central incisor. METHODS:A three-dimensional finite element model of the V-shaped cylindrical threaded implants in the maxilary bone. Abutment angle was set as 0°, 5°, 10°, 15°, 20°, 25°, 30°, and the load stress was set as 90, 105, 120, 135, 150, 165, 180, 195, 210 N. Occlusion of the central incisor was simulated on the implants, and then, buccolingual mechanical loads were loaded on the center of prostheses to observe the effects of different abutment angles and loads on the Von Mises peak stress of the maxila and mandible. RESULTS AND CONCLUSION:Under the influence of a single factor, when the abutment angles acted as variables, the Von Mises peak stress of the cortical and cancelous bone was respectively increased by 60.60% and 69.30% under labial or palatal loads; when the loading stress acted as variables, the Von Mises peak stress of the cortical and cancelous bone was increased by 68.74% and 69.30% under buccolingual loads. When the loading stress was less than 150 N and the abutment angle was less than 25°, the slop of tangent for the mandible Von Mises stress response curve was-1 to 0. It seems from the mechanical analysis that the stress of cancelous bone is more susceptible to abutment angle and load stress; the optimal abutment of screwed implant should be designed to an angle less than 25° and an bite force less than 150 N.%背景:口腔种植修复中,种植体中基台角度的优化设计对骨吸收有重要影响,同时患者的高用力也对骨质的吸收重建有着重要影

  16. 可摘局部义齿对Ⅱ型糖尿病患者基牙牙周状况的影响%The impacts of the removable partial dentures on the periodontal statuses of the type Ⅱ diabetic patients' abutments

    Institute of Scientific and Technical Information of China (English)

    宋亮; 徐斌; 徐婕; 查英

    2011-01-01

    Objective To study the impacts of the removable partial dentures on the periodontal statuses of the type II diabetic patients' abutments. Methods Sixty type II diabetic patients were selected randomly in the dental clinic. After the non-surgical periodontal treatment, removable partial dentures were restored. Five indices, including plaque index (PLI), gingival index (GI) , bleeding index (BI), probing depth (PD) and attachment loss ( AL) were compared between the abutments and the counterpart teeth on the opposite side at different time points, including before the restoration and 2 weeks, 3 months, 6 months, 12 months,24 months after the restoration. Results 1) The periodontal indices of the abutments of the type II diabetic patients were significantly higher than those of their counterparts (P < 0.01); 2) Indices of PLI, GI, BI, PD and AL of the abutments of the type II diabetic patients elevated within 6 months after the restoration (P <0.01). However, the periodontal condition tended to be stabilized and relieved as the usage time of the dentures extended further. Conclusions The removable partial denture restoration leads to the increase of the periodontal indices of the abutments of the type II diabetic patients.%目的 研究可摘局部义齿对Ⅱ型糖尿病患者基牙的影响程度.方法 选取口腔门诊就诊的Ⅱ型糖尿病患者60例,牙周非手术治疗后进行可摘局部义齿修复,研究基牙与其对侧同名牙于义齿修复前、修复后2周、3个月、6个月、12个月、24个月的菌斑指数、牙龈指数、探诊出血指数、探诊深度和临床附着丧失5项牙周指标.结果 1)Ⅱ型糖尿病患者戴用可摘局部义齿后基牙的牙周指标明显高于对照牙(P<0.01);2)Ⅱ型糖尿病患者戴用可摘局部义齿后的6个月内,基牙的牙周指标均明显升高(P<0.01);但随着戴用时间继续延长,基牙的牙周状况趋于稳定和缓解.结论 戴用可摘局部义齿可引起Ⅱ型糖

  17. 基于块体元的塑性极限下限法在拱坝坝肩稳定分析中的应用%Application of plastic limit lower bound method to stability analysis of arch dam abutment based on block elements

    Institute of Scientific and Technical Information of China (English)

    任顺; 王均星; 邓念武

    2012-01-01

    A block element lower bound limit analysis method for the stability of arch dam abutment is presented through combining block element method with lower bound limit analysis method.By utilizing block element method to disperse calculation areas,and satisfying some conditions for the block system static field in structure surface such as Mohr-Coulomb yield conditions,stress boundary conditions and the force vector and moment balance principle in block elements,a mathematical programming model solving lower bound solution of arch dam abutment strength reserve coefficient can be constituted.The interior point algorithm is employed to solve the model.Finally,a wedge example and a test of Qinglong arch dam left abutment are researched.The calculated results obtained by block element lower bound method are compared with rigid body limit equilibrium method;it is shown that the proposed method is feasible.%将块体单元法与极限分析下限法相结合,提出了拱坝坝肩稳定的块体单元极限分析下限法.借助于块体单元法离散计算区域,通过块体系统静力场在结构面上满足Mohr-Coulomb屈服条件、应力边界条件以及在块体单元上的力矢力矩平衡原理,构成求解拱坝坝肩强度储备安全系数下限解的数学规划模型,模型的求解采用内点法.最后研究了一个楔形体算例和青龙拱坝左岸坝肩实例,通过比较块体单元下限法计算结果与刚体极限平衡法计算结果,验证了该方法的可行性.

  18. 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。

  19. PES and WES evaluation of CAD/CAM custom abutments and all ceramic crowns in the anterior teeth area%红、白美学评价 CAD/CAM 个性化基台与全瓷冠在前牙区的应用

    Institute of Scientific and Technical Information of China (English)

    张晓真; 周国兴; 戴文雍; 赵毅; 邱憬; 王洁; 汤春波

    2013-01-01

    Objective:To investigate the clinic application of computer aided design&computer aided manufacturing ( CAD/CAM) custom abutments and all ceramic crowns and evaluate their esthetic effect in the anterior teeth area according to the assessment criteria Pink Esthetic Score ( PES ) and White Esthetic Score ( WES ) .Methods:Totally 73 CAD/CAM custom abutments and all ceramic crowns were used in 51 implant-supported prosthesis cases .The esthetic prosthetic effect was evaluated according to the assessment cri-teria PES and WES.Results:The 3-month-follow-up results of totally 73 CAD/CAM custom abutments and all ceramic crowns of 51 pa-tients:the percentage of the PES scores of 10,8-9,6-7 and≤5 was 9.59%,71.23%,17.81%,and 1.37%,respectively;the percent-age of the WES scores of 10,8-9,6-7 and ≤5 was 39.73%,60.27%,0%,and 0%,respectively.The 6-month-follow-up results: the percentage of the PES scores of 10,8-9,6-7 and≤5 was 8.22%,69.86%,17.81%,and 4.11%,respectively;the percentage of the WES scores of 10,8-9,6-7 and≤5 was 36.99%,61.64%,1.37%,and 0%,respectively.The 1-year-follow-up results:the percentage of the PES scores of 10,8-9,6-7 and≤5 was 5.48%,68.49%,20.55%,and 5.48%,respectively;the percentage of the WES scores of 10,8-9,6-7 and ≤5 was 31.51%,64.38%,4.11%,and 0%,respectively.During the follow-up of 1 to 3 years,there was only one abutment got fractured when the torque control was installed ,and one loosened during observation .In all cases,the gingivae were in healthy condition ,and no further obvious gingival retreat or periimplantitis occurred .Conclusions:PES and WES are objective ,integrat-ed and comparable .CAD/CAM custom abutments and all ceramic crowns have good biocompatibility and chemical stability ,and can be more widely used in the anterior teeth area .However,their long term effects need to be confirmed by further follow-up.%目的:研究计算机辅助设计及计算机辅助制作( CAD/CAM )个性化基台及全瓷冠的临床

  20. Digital restorative dentistry and prosthodontics(18)---The fit of all-ceramic crowns and custom abutments%数字化口腔修复(18)--CAD/CAM全瓷冠与个性化基台的适合性

    Institute of Scientific and Technical Information of China (English)

    强翔; 姚江武

    2016-01-01

    目的:比较不同计算机辅助设计和制造( computer aided design/manufacture,CAD/CAM)全瓷冠与氧化锆个性化基台的边缘和内部适合性。方法:用CAD/CAM分别设计和加工氧化锆个性化基台和全瓷冠3组( IPS e. max、Enamic和Suprinity),每组各5个全瓷冠。通过微机断层扫描( micro computed tomography,micro⁃CT)测量全瓷冠与氧化锆个性化基台的绝对边缘差异( absolute marginal discrepancy,AMD)、轴面间隙( axial gap,AG)、咬合间隙( oc⁃clusal gap,OG),比较不同材料全瓷冠与氧化锆个性化基台的边缘和内部适合性。结果:Enamic组分别与IPS e. max组和Suprinity组AMD之间的比较差异均具有统计学意义(P<0.05);而IPS e. max组与Suprinity组AMD之间的差异则无统计学意义(P>0.05)。 Suprinity组分别与IPS e. max组和Enamic组AG之间的比较差异均具有统计学意义(P<0.05);IPS e. max组与Enamic组AG之间的差异不具有统计学意义(P>0.05)。 Suprinity组、IPS e. max组和Enamic组3组OG之间的比较差异具有统计学意义(P<0.05)。结论:不同的CAD/CAM全瓷冠材料影响其边缘和内部适合性。 Suprinity和IPS e. max陶瓷材料的边缘适合性优于Enamic材料,Suprinity材料全瓷冠的轴面间隙和咬合间隙最小。%Objective:To compare the marginal and internal fits of different computer aided design/manufacture ( CAD/CAM) all⁃ceramic crowns seated on zirconia custom abutments. Methods:CAD/CAM systems were used to fabricate a zirconia custom abutment and three groups( IPS e. max,Enamic and Suprinity) of all⁃ceramic crowns for five samples,respec⁃tively. The absolute marginal discrepancy( AMD) ,axial gap( AG) ,and occlusal gap( OG) were evaluated by micro computed tomography( micro⁃CT) for comparing the marginal and internal fits of all⁃ceramic crowns and zirconia custom abutments. Re

  1. Comparison of Design Schemes of Inclined Pile and Vertical Pile in Embedded Rock Pile of Thin Walled Abut-ment%薄壁桥台嵌岩桩基础斜桩与直桩设计方案的比较

    Institute of Scientific and Technical Information of China (English)

    张利强

    2012-01-01

      According to the pile foundation engineering of 2nd section of Monapo bridge foundation project in Nampula-Cua-mbaroad road upgrading and regeneration in Mozambique, calculation analysis was made on the stress and reinforcement of different base heights and pile lengths of embedded rock pile of thin walled abutment with Prokon 2.5 structure analysis software, so as to provide the basis for rational selection of pile foundation type based on different formation conditions and base heights in the design.%  结合莫桑比克Nampula-Cuamba道路升级改造项目第二标段Monapo桥基础桩基工程,采用Prokon 2.5结构分析软件对薄壁桥台嵌岩斜桩和直桩在不同台高和不同桩长的受力和配筋情况分别进行计算分析,从而为设计中根据不同地层条件和不同台高选择合理的桩基形式提供依据.

  2. 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

  3. Three-D finite element analysis of the stress distribution in periodontal tissue of abutments with or without extracoronal retainer%冠外固位体义齿基牙牙周组织应力分布的三维有限元分析

    Institute of Scientific and Technical Information of China (English)

    林苑云; 郑美华; 韦佩伶; 张雯

    2012-01-01

    目的 研究下颌第一磨牙缺失、第二磨牙近中倾斜30°或45°时,用栓道附着体义齿或套筒冠义齿2种冠外固位体( extra-coronal retainer,ECR)义齿修复的基牙牙周组织应力分布.方法 采用CT扫描技术和Mimics、Freeform、ANSYS软件,建立下颌第一磨牙缺失、第二磨牙近中倾斜30°或45°及ECR义齿修复后的三维有限元模型,模拟加载并计算分析基牙牙周组织应力的分布情况.结果 下颌第二磨牙近中倾斜30°、45°模型,修复前第二前磨牙Von Mises应力分别是2.80 MPa、3.47 MPa,栓道附着体义齿修复后分别是19.26 MPa、25.18 MPa,套筒冠义齿修复后分别是19.47 MPa、24.48 MPa,ECR义齿修复后下颌第二前磨牙牙周组织应力明显增大;修复前第二磨牙Von Mises应力分别是20.45 MPa、20.50 MPa,栓道附着体义齿修复后分别是15.02 MPa、11.84 MPa,套筒冠义齿修复后分别是18.04 MPa、12.18 MPa,ECR义齿修复后下颌第二磨牙牙周组织应力明显减小.结论 栓道附着体义齿和套筒冠义齿均能改善倾斜基牙牙周组织的应力分布,当下颌第二磨牙近中倾斜角度过大或下颌第二前磨牙牙周状况欠佳时,应该考虑增加近中端基牙数目.%Objective To compare abutment' s periodontal stress distribution of two types of extra-coronal retainer (ECR) restoration (key-key-way attachment denture and telescopic crown denture) in the case of the lower first molar missed along the lower second molar with 30 or 45 degree mesial tilting. Methods Threedimensional finite element models of lower first molar missed along lower second molar with 30 or 45 degree mesial tilt with or without ECR restoration were constructed by combination of the computed tomographic (CT) scanning and Mimics, Freeform and ANSYS softwares. Axial occlusal force and oblique occlusal force of 200 N were applied to the lower second molar on the central fossae in each case. The stress distributions in the surrounding

  4. 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.

  5. 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.

  6. 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)

  7. 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.

  8. 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

  9. 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。

  10. 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

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

    OpenAIRE

    OZYILMAZ, Eda; 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...

  12. Characteristics of deformation and stress distribution of small coal pillars under leading abutment pressure

    Institute of Scientific and Technical Information of China (English)

    Wu Hai; Zhang Nong; Wang Weijun; Zhao Yiming; Cao Peng

    2015-01-01

    Based on the engineering project on a small coal pillar of 12,521 working face roadway in Xieqiao Coalmine, data regarding surface displacements of the coal pillar, deep displacements and mining stress have been collected and analyzed. The results show that macroscopic transverse fractures of the inner coal pillar are developed within 2–4 m of the roadway surface, which is located outside the coal pillar anchorage zone. There is a displacement of 530 mm at the monitoring point in the 6 m deep zone of the pillar. Transfer of the fracture zone is found in a small coal pillar and the fractures within 3–4 m of the coal-rock zone from the roadway surface undergo propagation and closure of cracks which means this fracture zone is transferred from 3–4 m outside the roadway to only 2–3 m from the roadway sur-face. In the monitoring zone, vertical and horizontal stresses increase with a feature that shows that acceleration in the deep zone of the pillar is greater than that in the shallow zone. Furthermore, the accel-eration of vertical stress is also greater than that of horizontal stress with a peak value in the 4 m zone. The research findings provide a reference for the regulation of a reasonable width of coal pillar in coalmi-nes and optimal control design of surrounding rock.

  13. 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.

  14. A new portable vibrator for plaster pouring: effect on the marginal fit at cylinder-abutment

    Directory of Open Access Journals (Sweden)

    Pâmela Cândida Aires Ribas de Andrade

    2012-10-01

    Full Text Available OBJECTIVE: The aim of this study was to test a new portable vibrator for plaster pouring (developed for this purpose, comparing the effect of its use on the accuracy of working cast of implant-supported restorations to the conventional vibrator. MATERIAL AND METHODS: From a master cast with 2 implants, 30 transfer moldings were made randomly and divided into three groups: Group I (GI: pouring performed in an outsourced dental laboratory with conventional plaster vibrator (10 casts, Group II (GII: pouring performed in the laboratory of the Federal University of Santa Catarina (UFSC with conventional plaster vibrator (10 casts and Group III (GIII: pouring performed with the portable vibrator fabricated for this study (10 casts. The position of the analogue and marginal adaptation of the infrastructure were verified by testing the single screw on the master model and on the working model. The measurement of misfit was blindly performed with a precision microscope and analyzing unit, Quadra-Check 200. The data were statistically analyzed by analysis of variance (ANOVA and the Holm-Sidak test (α=0.05. RESULTS: Means±standard deviations were as follows: GI: 19.19±4.73 µm; GII: 21.72±5.41 µm; GIII: 13.5±2.39 µm (P<0.05, with GIII significantly lower as compared to the other groups. CONCLUSION: Within the limitations of this study, it was concluded that a greater accuracy of working cast was achieved when a portable vibrator was used for casting molds.

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

    OpenAIRE

    Golmoradizadeh

    2013-01-01

    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 i...

  16. Clinical Evaluation of an Acrylic Pontic ’Adhesively’ Bonded to Uncut Abutment Teeth: 18 Month Results

    Science.gov (United States)

    1974-12-23

    acid etch technique, permit reconstruction of fractured anterior teeth in one sitting often without anesthesia. ’ 3. Orthodontic banding is accom...their own misuse of "flipper" partial dentures, patients scheduled for full arch extractions whose previous partial dentures were no longer usable...because of already completed extractions , and some few patients with no previous prosthetic experience who, after being made aware of the

  17. E-glass fiber reinforced composite as an oral implant abutment material. In vitro bacterial adhesion assay and biomechanical tests

    OpenAIRE

    2015-01-01

    [spa] Los materiales compuestos de resina reforzados con fibras de vidrio E (FRC) están aumentando su uso en aplicaciones dentales y ortopédicas como materiales de soporte de carga. Esto es debido a que exhiben una mejor adaptación biomecánica con los tejidos vivos en comparación con los materiales tradicionales, así como por sus propiedades biocompatibles. Recientemente, se ha observado que mejora la formación del tejido gingival peri-implantario. Además, pilares de FRC reforzados unidirecc...

  18. Marginal bone and soft tissue behavior following platform switching abutment connection/disconnection – a dog model study

    OpenAIRE

    Coutinho Alves, Célia

    2016-01-01

    La literatura científica parece indicar que la conexión/desconexión del pilar protésico puede provocar alteraciones en la inserción epitelial, causando sangrado y ulceración en el mismo. Esta ruptura mecánica se puede considerar como una herida abierta con la exposición del tejido conjuntivo, lo cual puede resultar en una respuesta inflamatoria y consecuentemente en migración apical epitelial. Esta tesis resume un trabajo de investigación experimental “in vivo” diseñado con el ...

  19. 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.

  20. Clinical Bonding of Resin Nano Ceramic Restorations to Zirconia Abutments : A Case Series within a Randomized Clinical Trial

    NARCIS (Netherlands)

    Schepke, Ulf; Meijer, Henny J. A.; Vermeulen, Karin M.; Raghoebar, Gerry M.; Cune, Marco S.

    2016-01-01

    Background: New dental materials are introduced and promoted in the field without extensive clinical testing. Using those materials in a clinical setting might result in unacceptable early failure rates. Purpose: The purpose of this paper was to analyze bonding of a new dental restorative material t

  1. 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 .

  2. Legal Application:Abutment between Being and Ought-to-be%法律适用:实然与应然的对接

    Institute of Scientific and Technical Information of China (English)

    陈文华

    2013-01-01

    法律适用并不是简单的包摄与被包摄关系。制定法的不合目的性、不周延性、模糊性及滞后性决定了法律规范不仅是不明确的,而且是有漏洞的。因此,在法律适用过程中,法官往往需要经过设证、归纳及类推等环节才能最后确定可以适用于待决案件的裁判规则。不仅如此,从法律适用的过程观察,法律适用实际上是应然的法律规范与实然的案件事实不断接近,以致最后对接起来的创造性司法活动。%Legal application cannot be simply described as subsuming or being subsumed .Legal regulations tend to be ambiguous or even flawed due to the vague purpose , lack of continuity , ambiguity and hysteretic nature in the process of legal prescription .Therefore , in the process of legal application , the judges need to undergo the process of presumption , induction and analogy before coming to the final judging principles for the cases involved . In addition, examining the process of legal application , we can conclude that legal application in fact is a creative judicial activity and a continuous approach between ought -to-be legal regulations and being the facts of cases .

  3. Grouting Reinforcement Construction Technology for Mortar Rubble Masonry Abutment%浆砌片石桥台注浆加固施工技术

    Institute of Scientific and Technical Information of China (English)

    马晓力; 孟屯良; 王俊涛

    2009-01-01

    采用注浆技术加固浆砌片石桥台在其它路段已有成功先例,但整套技术目前尚不成熟,施工工艺上还有需要通过实践探索进行改进的地方.结合广东省清远至连州一级公路改造(高速)项目中几座浆砌片石桥台注浆加固的施工情况,介绍了小孔道注浆、钢花管注浆锚杆与基础钢花管注浆的施工工艺及施工中的几个关键技术问题的解决方法.

  4. 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.

  5. COST COMPARISON BETWEEN BARN WITH STRUCTURAL ELEMENTS MADE OF CONCRETE AND METAL SHED WITH ROOF TRUSS AND PRECAST ABUTMENTS FOR THE SINOP-MT

    Directory of Open Access Journals (Sweden)

    K. A. F. Miranda

    2016-07-01

    Full Text Available The purpose of this article it was show a cost comparative between two constructive methods employed in sheds in the city of Sinop-MT, constructed with precast beams of armed concrete and structural system of the roofs varying between metalic trellis and precast concrete beams. For this, it was created a standard project, with the same architetonic dimensions, being dimensioned all elements for both methods. To the elaborationof the structural projects were followed cauculation scripts always with the assistence of the softwares VisualVentos, Ftool, DimPerfil and Superporticos, like the current norms. As a result the two buildings studied showed numerous differences, both in costs as in structural features, having a big variation in the self weight of approximately 47%. As element wich made this comparative relevant, stands out that the roof system of the shed with metalic structure had a variation of 173% when compared with the competitor shed. Thus, the constructive system, where all the parts were made of concrete, showed a cost variation of 52% to minus when compared to the competing system, were ignored in the quantitative elements outside the structure in which both were equal

  6. Influence of connection type of zirconia abutment with titanium implant on stress distribution in abutment and bone using finite element analysis%氧化锆瓷基台与钛种植体联合应用中不同连接体设计的有限元分析

    Institute of Scientific and Technical Information of China (English)

    吴春锋; 谢乔; 王书明; 宋应亮

    2014-01-01

    目的:分析不同氧化锆基台对基台自身及钛种植体周围骨组织应力的影响,为氧化锆基台设计提供理论依据.方法:采用计算机辅助设计建立5种不同设计的氧化锆基台模型,并根据不同的基台模型设计了与之对应的种植体、牙槽骨及全瓷冠模型.用三维有限元方法对每个模型进行100 N的斜向加载,分析不同氧化锆基台的设计对基台自身及牙槽骨应力分布及应力峰值的影响.结果:5种设计的等效应力的分布基本一致,基台的应力主要集中在基台颈部连接体上方,皮质骨及松质骨的应力主要集中于骨与种植体连接的最上方.5种设计等效应力的峰值不同,圆形连接体设计时氧化锆基台,皮质骨及松质骨的等效应力峰值均小于其他各设计组.结论:圆形连接体设计是本研究5种设计中氧化锆基台与钛种植体相连的最佳设计形式.

  7. Influence of implant zirconia abutment types on stress distribution in bone and abutment-a three-dimensional finite element analysis%不同结构氧化锆瓷基台及种植体周骨壁应力的有限元分析

    Institute of Scientific and Technical Information of China (English)

    杨炎忠; 周延民; 田小华; 王林; 陈淑萍; 付丽

    2008-01-01

    目的 研究不同结构氧化锆瓷基台及种植体周骨壁应力的分布情况,为临床应用提供理论指导.方法 采用建模软件Altair Hypermesh建立三维有限元模型,应用Altair Hyperview后处理软件对模型中不同载荷条件下的三种不同结构氧化锆瓷基台及种植体周骨壁应力的分布情况进行分析,并与常规钛基台进行比较.结果 Replace基台模型的种植体周骨壁应力明显小于Lifecore实心基台模型和Lifecore螺栓固定基台模型的种植体周骨壁应力,而Replace基台模型的基台等效应力明显大于Lifecore实心基台模型和Lifecore螺栓固定基台模型的基台等效应力,Replace基台模型的螺栓等效应力峰值明显大于Lifecore螺栓固定基台的模型的螺栓等效应力峰值;Lifecore实心基台模型的种植体周骨壁应力略小于Lifecore螺栓固定基台模型的种植体周骨壁应力,而Lifecore实心基台模型的基台等效应力略大于Lifecore螺栓固定基台模型的基台等效应力;氧化锆基台模型与钛基台模型比较,两者无明显差异.结论 基台与种植体连接方式的不同对氧化锆瓷基台及种植体周骨壁应力的分布有影响,提示临床上应该根据患者情况选择最合适的基台;基台材料的改变对应力分布无明显影响,从生物力学考虑可以放心使用氧化锆瓷基台.

  8. Using MatLab software for deducing safety factor of point shearing resistance on the arch abutment space%利用MatLab软件推导拱座空间点抗剪安全系数

    Institute of Scientific and Technical Information of China (English)

    沈可

    2002-01-01

    利用MatLab数学软件,详尽推导出基于摩尔--库仑准则的空间点抗剪最小、最大安全系数公式,表明空间点和平面点具有类似的点抗剪安全系数表达式.讨论了空间点抗剪安全系数公式在拱座稳定分析中的应用.

  9. 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.

  10. Long-term stability of peri-implant tissues after bone or soft tissue augmentation. Effect of zirconia or titanium abutments on peri-implant soft tissues. Summary and consensus statements. The 4th EAO Consensus Conference 2015

    NARCIS (Netherlands)

    Sicilia, Alberto; Quirynen, Marc; Fontolliet, Alain; Francisco, Helena; Friedman, Anton; Linkevicius, Tomas; Lutz, Rainer; Meijer, Henny J.; Rompen, Eric; Rotundo, Roberto; Schwarz, Frank; Simion, Massimo; Teughels, Wim; Wennerberg, Ann; Zuhr, Otto

    2015-01-01

    Introduction: Several surgical techniques and prosthetic devices have been developed in the last decades, aiming to improve aesthetic, hygienic and functional outcomes that may affect the peri-implant tissues, such as procedures of bone and soft tissue augmentation and the use of custom-made abutmen

  11. 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.

  12. Study on application of argil fly-ash concrete to highway-bridge abutment-backfill%陶粒粉煤灰混凝土在桥涵台背回填中的应用研究

    Institute of Scientific and Technical Information of China (English)

    葛折圣; 黄晓明; 张肖宁; 高俊合

    2006-01-01

    通过材料性能试验、土工离心模型试验和数值计算,研究陶粒粉煤灰混凝土的物理力学性能及其在桥涵台背回填的应用效果.首先,通过材料性能试验研究不同配合比的陶粒粉煤灰混凝土的物理力学性能;其次,通过土工离心模型试验和数值计算研究陶粒粉煤灰混凝土用作桥涵台背回填材料时,作用于台背的土压力和回填体的变形特性.研究发现:陶粒粉煤灰混凝土具有轻质、高强度、高模量和易施工等诸多优点;陶粒粉煤灰混凝土回填体作用于台背的土压力明显小于常规回填材料;回填区和地基的沉降变形亦明显小于其他材料.结果表明:陶粒粉煤灰混凝土作为台背回填材料具有明显的优越性,是一种值得推荐的桥涵台背回填材料.

  13. 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.

  14. Load bearing mechanism between geosynthetic reinforced pile-supported embankment and piled abutment constructed on soft soils%软基上桩承加筋路基与桩基桥台的承载机理

    Institute of Scientific and Technical Information of China (English)

    佘志通; 佘智敏

    2015-01-01

    采用ABAQUS有限元软件建立桩承加筋路基和桩基桥台模型,系统研究桩基桥台-路基-地基的相互作用性状,包括桥台桩基水平位移、桥头路面沉降、桥台桩弯矩等的变化规律,分析深厚软土地基的超孔压固结,并提出若干施工建议.

  15. 下颌磨牙游离缺失套筒冠修复的基牙受载分析%Three-dimensional Finite Element Displacement and Stress Analysis of Abutment Teeth Retained by Conical Telescope

    Institute of Scientific and Technical Information of China (English)

    陆轩; 满毅; 林映荷; 管东华

    2005-01-01

    目的研究下颌磨牙游离缺失采用第一、第二前磨牙为基牙的套筒冠修复,义齿受载时不同基牙的位移与应力分布特点.方法采用螺旋CT扫描、自编程序和ANSYS软件建立起精确的套筒冠三维有限元模型,在其上进行不同载荷的加载,分析不同基牙的位移与应力分布趋势. 结果套筒冠义齿在受载情况下不同基牙的位移差别占其总位移的9%以下,应力均匀分布于不同基牙.结论套筒冠义齿中不同位置的基牙受载时共同下沉,承担着牙合力.

  16. 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。

  17. 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

  18. 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.

  19. Occlusal Recording Components for Dental Implant- Supported Prostheses

    OpenAIRE

    A. Monzavi; Alikhasi, M.; Taghavi, F.

    2012-01-01

    In this article, three techniques for maxillo-mandibular relationship for Replace-Select implants are described. The use of healing abutments, planning abutments, and Impression copings are presented, and the advantages and disadvantages are discussed.

  20. Chief Joseph Dam, Columbia River, Washington, Additional Units and Structural Modification Foundation Report

    Science.gov (United States)

    1988-01-01

    steel and concrete formwork had to be custom-made to fit the overbreaks (25%+) etc. c. Quarry waste overruns (increased from the estimated 25% to about... Tunnel 38 6.03 Piezometers 38 6.04 Upstream Seepage Control Blankets 38 SECTION 7. LEFT ABUTMENT SETTLEMENT AREA 7.01 General 39 7.02 Construction...17. no longer read. 10. Piezometers, Monthly. Right abutment; 70 (3 taken 90 out of service). Left abutment; 20 in serv- ice. 11. Relief Tunnel Twice

  1. 基于ABAQUS研究软土条件下路基填土对桥台桩基的影响%Research on the Influence of Embankment Fill on Pile Foundation of Bridge Abutment in Soft Soil Based on ABAQUS

    Institute of Scientific and Technical Information of China (English)

    李克磊; 袁有为

    2016-01-01

    通过应用有限元软件ABAQUS建立软土地基条件下有台后填土时的三维桥台群桩基础模型,分析单桩和桩侧土体竖向相对位移关系、群桩中不同位置桩的桩侧负摩阻力以及填土高度和摩擦系数对桩侧负摩阻力的影响.研究表明填土高度、摩擦系数和单桩所处于群桩中的位置都是桩侧负摩阻力产生变化的原因.

  2. 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.

  3. 牙周病伴牙列缺损经套筒冠义齿修复后牙周微生态变化的研究%Microbiological study on abutment after restoration of dentition defect with conical telescopic removable denture in patients with periodontitis

    Institute of Scientific and Technical Information of China (English)

    刘晓青; 罗晓晋; 武峰

    2007-01-01

    目的 探讨牙周病伴牙列缺损的患者,经套筒冠义齿修复后对牙周组织的影响.方法 选择18例牙周病伴游离端缺损欲行套筒冠修复的患者,分为洁治组和非洁治组,记录修复时、修复后1、3、6个月4个时段基牙的菌斑指数(PLI)、牙龈指数(GI)、牙龈出血指数(BOP)、探诊深度(PD)、牙齿松动度,采用产黑菌及具核梭杆菌的选择性培养基对龈下菌斑标本进行分离培养,并进行对照比较.结果 经套筒冠修复后,牙齿松动度逐渐变小,与修复前相比差异有统计学意义(P<0.05).非洁治组基牙PLI,GI及产黑菌与具核梭杆菌的检出率在修复后3个月与修复前相比差异有统计学意义(P<0.05),6个月后差异仍有统计学意义(P<0.01).洁治组差异无统计学意义(P>0.05).结论 牙周病伴牙列缺损患者经套筒冠修复后,进行牙周序列治疗对提高修复体的成功率具有重要意义.

  4. Refining cast implant-retained restorations by electrical discharge machining.

    Science.gov (United States)

    Schmitt, S M; Chance, D A; Cronin, R J

    1995-03-01

    The UCLA abutment was developed to create implant-retained restorations with ideal contours, excellent esthetics, and minimal vertical space requirements for restorative materials. A major drawback of this abutment is that casting inaccuracies in the lost-wax process are difficult to control. This article describes a method of refining cast implant-retained restorations by use of electrical discharge machining.

  5. 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

  6. 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...

  7. 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 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.

  8. 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

  9. 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.

  10. 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.

  11. An improved index for the waxed stage of an implant-retained framework.

    Science.gov (United States)

    Adrian, E D; Krantz, W A; Ivanhoe, J R; Edge, M J

    1991-11-01

    A method for making an improved index for the waxed stage of Branemark implant-retained frameworks is described. The index improves visibility of the tooth and abutment cylinder relationship permitting the optimization of framework dimensions and contour.

  12. A comparison of the accuracy of two removable die systems with intact working casts.

    Science.gov (United States)

    Aramouni, P; Millstein, P

    1993-01-01

    This study evaluated the reproducibility of die position using two removable die systems and two die stones. Poly(vinyl siloxane) impressions were made of a stainless steel, U-shaped arch with four evenly spaced abutments. Six groups were evaluated: Zeiser system/Fuji Rock; Zeiser system/Die Keen; solid cast/Fuji Rock; solid cast/Die Keen; Fuji Rock/Pindex; and Die Keen/Pindex. An optical comparator was used to measure the height of each abutment, the distance between the anterior abutments, and the distance between the posterior abutments. The Zeiser system with either Fuji Rock or Die Keen yielded the greatest accuracy. Die Keen exhibited more linear expansion than Fuji Rock, and solid casts had less distortion than the Pindex system.

  13. 76 FR 12958 - Amnor Hydro West Inc.; Notice of Preliminary Permit Application Accepted for Filing and...

    Science.gov (United States)

    2011-03-09

    ... channel beginning near the left abutment of the dam and connecting with three 63-inch-diameter butterfly valves; (2) three new 656-foot-long, 63-inch-diameter steel penstocks that connect to a new...

  14. 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.

  15. Patient specific root-analogue dental implants – additive manufacturing and finite element analysis

    OpenAIRE

    Gattinger Johannes; Bullemer Christian N.; Harrysson Ola L. A.

    2016-01-01

    Aim of this study was to prove the possibility of manufacturing patient specific root analogue two-part (implant and abutment) implants by direct metal laser sintering. The two-part implant design enables covered healing of the implant. Therefore, CT-scans of three patients are used for reverse engineering of the implants, abutments and crowns. Patient specific implants are manufactured and measured concerning dimensional accuracy and surface roughness. Impacts of occlusal forces are simulate...

  16. Effect of different veneering techniques on the fracture strength of metal and zirconia frameworks

    OpenAIRE

    Turk, Ayse Gozde; Ulusoy, Mubin; Yuce, Mert; Akin, Hakan

    2015-01-01

    PURPOSE To determine whether the fracture strengths and failure types differed between metal and zirconia frameworks veneered with pressable or layering ceramics. MATERIALS AND METHODS A phantom molar tooth was prepared and duplicated in 40 cobalt-chromium abutments. Twenty metal (IPS d.SIGN 15, Ivoclar, Vivadent, Schaan, Liechtenstein) and 20 zirconia (IPS e.max ZirCAD, Ivoclar) frameworks were fabricated on the abutments. Each framework group was randomly divided into 2 subgroups according ...

  17. A simple procedure for retrieval of a cement-retained implant-supported crown: a case report.

    Science.gov (United States)

    Buzayan, Muaiyed Mahmoud; Mahmood, Wan Adida; Yunus, Norsiah Binti

    2014-02-01

    Retrieval of cement-retained implant prostheses can be more demanding than retrieval of screw-retained prostheses. This case report describes a simple and predictable procedure to locate the abutment screw access openings of cementretained implant-supported crowns in cases of fractured ceramic veneer. A conventional periapical radiography image was captured using a digital camera, transferred to a computer, and manipulated using Microsoft Word document software to estimate the location of the abutment screw access.

  18. 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.

  19. A comparative evaluation of implant supported zirconia framework gap of two CAD/CAM systems

    Directory of Open Access Journals (Sweden)

    Narges Ameri

    2016-11-01

    computer-aided manufacturing (CAM systems (AmannGirrbach and Zirkonzahn. Materials and Methods: The master model of 3-unit FDP was made of two implant abutments (AmannGirrbach and Zirkonzahn from canine to second premolar. Twelve frameworks were manufactured using each fabricating system from semi-sintered zirconia blanks, which had to be sintered for final density after milling. After manufacturing, the absolute marginal discrepancy in each abutment were determined by means of Video Measurement System (VMS. The data were analyzed, using independent and paired t test (P=0.05. Results: For the premolar abutment, the absolute marginal discrepancy of frameworks fabricated by AmannGirrbach system was significantly greater than those of the other system (P=0.005. There was no significant difference between the marginal discrepancy of canine and premolar abutments (P>0.05. Conclusion: Within the limitations of this study, it could be concluded that the marginal fit of zirconia FDPs was significantly dependent on the CAD/CAM system used, but the abutment size was not an effective factor.

  20. Effect of load on the bone around bone-anchored amputation prostheses.

    Science.gov (United States)

    Stenlund, Patrik; Trobos, Margarita; Lausmaa, Jukka; Brånemark, Rickard; Thomsen, Peter; Palmquist, Anders

    2016-06-24

    Osseointegrated transfemoral amputation prostheses have proven successful as an alternative method to the conventional socket-type prostheses. The method improves prosthetic use and thus increases the demands imposed on the bone-implant system. The hypothesis of the present study was that the loads applied to the bone-anchored implant system of amputees would result in locations of high stress and strain transfer to the bone tissue and thus contribute to complications such as unfavourable bone remodeling and/or elevated inflammatory response and/or compromised sealing function at the tissue-abutment interface. In the study, site-specific loading measurements were made on amputees and used as input data in finite element analyses to predict the stress and strain distribution in the bone tissue. Furthermore, a tissue sample retrieved from a patient undergoing implant revision was characterized in order to evaluate the long-term tissue response around the abutment. Within the limit of the evaluated bone properties in the present experiments, it is concluded that the loads applied to the implant system may compromise the sealing function between the bone and the abutment, contributing to resorption of the bone in direct contact with the abutment at the most distal end. This was supported by observations in the retrieved clinical sample of bone resorption and the formation of a soft tissue lining along the abutment interface. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

  1. Finite element analyses of two antirotational designs of implant fixtures.

    Science.gov (United States)

    Akour, Salih N; Fayyad, Mohammed A; Nayfeh, Jamal F

    2005-03-01

    The purpose of this study was to compare the effect of cyclic compressive forces on loosening of the abutment retaining screw of dental implant fixtures with two different antirotational designs using the finite element analysis. A three-dimensional model of externally hexed and trichannel dental implant fixtures with their corresponding abutments and retaining screws was developed. Comparison between the two designs was carried out using finite element analysis. The results revealed that the externally hexed design has significantly higher overall stress, contact stress, and deflection compared with the trichannel design. The trichannel antirotational design has the least potential for fracture of the implant/abutment assembly in addition to its capability for preventing rotation of the prosthesis and loosening of the screw.

  2. Microstructural characterization and hardness properties of electric resistance welding titanium joints for dental applications.

    Science.gov (United States)

    Ceschini, Lorella; Boromei, Iuri; Morri, Alessandro; Nardi, Diego; Sighinolfi, Gianluca; Degidi, Marco

    2015-06-01

    The electric resistance welding procedure is used to join a titanium bar with specific implant abutments in order to produce a framework directly in the oral cavity of the patient. This investigation studied the effects of the welding process on microstructure and hardness properties of commercially pure (CP2 and CP4) Ti components. Different welding powers and cooling procedures were applied to bars and abutments, normally used to produce the framework, in order to simulate the clinical intraoral welding procedure. The analyses highlighted that the joining process did not induce appreciable changes in the geometry of the abutments. However, because of unavoidable microstructural modifications in the welded zones, the hardness decreased to values lower than those of the unwelded CP2 and CP4 Ti grades, irrespective of the welding environments and parameters.

  3. 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

    of crowns, cement excess and technical complications. The aesthetic outcome was assessed by using the Copenhagen Index Score, and the patient-reported outcomes were recorded using the OHIP-49 questionnaire. The statistical analyses were mainly performed by using mixed model of ANOVA for quantitative data...... and PROC NLMIXED for ordinal categorical data. RESULTS: The 3-year survival rate was 100% for implants and 97% for abutments and crowns. Significantly more marginal bone loss was registered at gold-alloy compared to zirconia abutments (P = 0.040). The mPlI and mBI were not significantly different at three......-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...

  4. Responses to compound objects in monkey inferotemporal cortex: the whole is equal to the sum of the discrete parts.

    Science.gov (United States)

    Sripati, Arun P; Olson, Carl R

    2010-06-09

    It is commonly thought that neurons in monkey inferotemporal cortex are conjunction selective--that a neuron will respond to an image if and only if it contains a required combination of parts. However, this view is based on the results of experiments manipulating closely adjacent or confluent parts. Neurons may have been sensitive not to the conjunction of parts as such but to the presence of a unique feature created where they abut. Here, we compare responses to two sets of images, one composed of spatially separate and the other of abutting parts. We show that the influences of spatially separate parts combine, to a very close approximation, according to a linear rule. Nonlinearities are more prominent--although still weak--in responses to images composed of abutting parts.

  5. 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...... ceramics (n=8). The palatal surfaces of the crowns were exposed to cyclic loading of 800 N with a frequency of 2 Hz, which continued to 4.2 million cycles or until fracture of the copings, abutments, or implants. The number of cycles and the fracture modes were recorded. The fracture modes were analyzed...... and resisted more cyclic loads than the ceramic restorations, particularly when the metal ceramic crowns were veneered with glass-ceramics....

  6. 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

  7. 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

    2016-07-05

    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.

  8. One-step surgical placement of Brånemark implants: a prospective multicenter clinical study.

    Science.gov (United States)

    Becker, W; Becker, B E; Israelson, H; Lucchini, J P; Handelsman, M; Ammons, W; Rosenberg, E; Rose, L; Tucker, L M; Lekholm, U

    1997-01-01

    This prospective longitudinal multicenter study evaluated the clinical outcomes after placement and restoration of one-step Brånemark implants into the maxillae and mandibles of completely and partially edentulous patients. Six surgical treatment centers participated in this study, in which 135 implants were placed into 63 adult patients. All implants were stable after placement. The majority of implants were placed into type B bone with minimal jaw resorption and type 2 bone quality. After implant placement, standard transmucosal healing abutments were firmly placed. The average amount of time between implant placement and prosthetic abutment connection was 170 days in the maxillae and 147 days in the mandibles. To evaluate crestal bone changes caused by implant placement, a periodontal probe was used to measure midbuccally from the top of the implant cylinder to the alveolar crest; in 29 patients, 54 midbuccal bone crest sites were remeasured following prosthetic abutment connection. Crestal bone changes in mandibles and maxillae were statistically and clinically insignificant. Six implants were lost prior to loading and one implant has not been restored. No implants or restorations were lost after loading. At 1 year, the implant success rate was 95.6%. Mesiodistal radiographic measurements from 34 patients were averaged, and changes from prosthetic abutment connection to, on average, 12 months follow-up were compared. The radiographs, which were digitalized, measured from the bottom of the implant cylinder to the most coronal bone in contact with implant thread. For mandibular implants, the mean radiographic bone level at prosthetic abutment connection was 1.07 mm; after loading, it was 1.35 mm. For maxillary implants, the mean radiographic bone height at prosthetic abutment connection was 1.16 mm; after loading, it was 1.36 mm. These changes were not statistically significant. The 1-year outcomes from this patient series indicate that one-step Br

  9. Evaluation in a Dog Model of Three Antimicrobial Glassy Coatings: Prevention of Bone Loss around Implants and Microbial Assessments.

    Directory of Open Access Journals (Sweden)

    Roberto López-Píriz

    Full Text Available The aim of the present study is to evaluate, in a ligature-induced peri-implantitis model, the efficacy of three antimicrobial glassy coatings in the prevention of biofilm formation, intrasulcular bacterial growth and the resulting peri-implant bone loss.Mandibular premolars were bilaterally extracted from five beagle dogs. Four dental implants were inserted on each hemiarch. Eight weeks after, one control zirconia abutment and three with different bactericidal coatings (G1n-Ag, ZnO35, G3 were connected. After a plaque control period, bacterial accumulation was allowed and biofilm formation on abutments was observed by Scanning Electron Microscopy (SEM. Peri-implantitis was induced by cotton ligatures. Microbial samples and peri-implant crestal bone levels of all implant sites were obtained before, during and after the breakdown period.During experimental induce peri-implantitis: colony forming units counts from intrasulcular microbial samples at implants with G1n-Ag coated abutment remained close to the basal inoculum; G3 and ZnO35 coatings showed similar low counts; and anaerobic bacterias counts at control abutments exhibited a logarithmic increase by more than 2. Bone loss during passive breakdown period was no statistically significant. Additional bone loss occurred during ligature-induce breakdown: 0.71 (SD 0.48 at G3 coating, 0.57 (SD 0.36 at ZnO35 coating, 0.74 (SD 0.47 at G1n-Ag coating, and 1.29 (SD 0.45 at control abutments; and statistically significant differences (p<0.001 were found. The lowest bone loss at the end of the experiment was exhibited by implants dressing G3 coated abutments (mean 2.1; SD 0.42.Antimicrobial glassy coatings could be a useful tool to ward off, diminish or delay peri-implantitis progression.

  10. Effect of the shades of background substructures on the overall color of zirconia-based all-ceramic crowns

    OpenAIRE

    Suputtamongkol, Kallaya; Tulapornchai, Chantana; Mamani, Jatuphol; Kamchatphai, Wannaporn; Thongpun, Noparat

    2013-01-01

    PURPOSE The objective of this study was to determine the effect of the color of a background substructure on the overall color of a zirconia-based all-ceramic crown. MATERIALS AND METHODS Twenty one posterior zirconia crowns were made for twenty subjects. Seven premolar crowns and six molar crowns were cemented onto abutments with metal post and core in the first and second group. In the third group, eight molar crowns were cemented onto abutments with a prefabricated post and composite core ...

  11. 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.

  12. Method for partially coating laser diode facets

    Science.gov (United States)

    Dholakia, Anil R. (Inventor)

    1990-01-01

    Bars of integral laser diode devices cleaved from a wafer are placed with their p regions abutting and n regions abutting. A thin BeCu mask having alternate openings and strips of the same width as the end facets is used to mask the n region interfaces so that multiple bars can be partially coated over their exposed p regions with a reflective or partial reflective coating. The partial coating permits identification of the emitting facet from the fully coated back facet during a later device mounting procedure.

  13. Rigid connections between natural teeth and implants: a technical note.

    Science.gov (United States)

    Lindh, T; Gunne, J; Danielsson, S

    1997-01-01

    In the posterior partially edentulous jaw, implants may be used to supplement existing natural dentition. Frequently, the maxillary sinuses and the mandibular nerve preclude the fabrication of freestanding implant-retained prostheses. However, if an implant and a natural abutment are combined, a fixed prosthesis can be fabricated, restoring the arch into the premolar area. The histories of three patients with attachments connecting implant-retained ceramotitanium crowns with crowns on natural abutments are described. A design for a rigid custom-made attachment for the Brånemark system, using standard components with a machine-duplication, spark-erosion technique, is suggested.

  14. Digital Mandibular Arch Restoration at an Increased Occlusal Vertical Dimension in One Visit.

    Science.gov (United States)

    Hartrick, Nancy E; Acker, Steven R

    2017-01-01

    This case demonstrates how a fully digital technique was used to restore the mandibular arch to proper function and improved esthetics. The initial treatment plan to restore implants replacing the lower right molars had to be altered due to space limitations. A direct deprogrammer was utilized to determine the proper jaw relationship at an acceptable occlusal vertical dimension. A computer-aided design system was employed to digitally create and fabricate implant/abutment-supported cement-retained lithium-disilicate crowns, toothsupported lithium-disilicate crowns, and screw-retained hybrid abutment lithium-disilicate crowns in one visit.

  15. Pembuatan "Primary Crown" pada Perawatan dengan Restorasi Jembatan Konvensional (Laporan Kasus Klinik

    Directory of Open Access Journals (Sweden)

    Suhandi Sidjaya

    2015-10-01

    Full Text Available Secondaire caries was considered as an important contributor to the complication in fixed prosthodontic (crown & bridgework. One factor that is improper cervical margin of the restoration could lead to desementation and further to secondair caries occurance. Tensile stress as leverage at long span bridge could open the cervical margin of the retainer. Metal coping as primary coping could protect the abutment teeth of long span bridge of this possibility. This article reported two cases treated with long span conventional bridge on primary metal coping at its abutment.

  16. 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.

  17. Managing complex orthodontic problems: the use of implants for anchorage.

    Science.gov (United States)

    Kokich, V G

    1996-06-01

    Today implants are commonly used to replace missing teeth in partially edentulous adult orthodontic patients. Because these patients are missing teeth, orthodontic mechanics may be complicated or often impossible because of insufficient anchorage. In these situations, it may be feasible to use the implant initially as an orthodontic anchor to facilitate complex tooth movement and secondarily as an abutment for a crown or fixed prosthesis. This article will discuss the ramifications and requirements for using implants as anchors and abutments in adult orthodontic patients.

  18. Patient specific root-analogue dental implants – additive manufacturing and finite element analysis

    Directory of Open Access Journals (Sweden)

    Gattinger Johannes

    2016-09-01

    Full Text Available Aim of this study was to prove the possibility of manufacturing patient specific root analogue two-part (implant and abutment implants by direct metal laser sintering. The two-part implant design enables covered healing of the implant. Therefore, CT-scans of three patients are used for reverse engineering of the implants, abutments and crowns. Patient specific implants are manufactured and measured concerning dimensional accuracy and surface roughness. Impacts of occlusal forces are simulated via FEA and compared to those of standard implants.

  19. Stress analysis in platform-switching implants: a 3-dimensional finite element study.

    Science.gov (United States)

    Pellizzer, Eduardo Piza; Verri, Fellippo Ramos; Falcón-Antenucci, Rosse Mary; Júnior, Joel Ferreira Santiago; de Carvalho, Paulo Sérgio Perri; de Moraes, Sandra Lúcia Dantas; Noritomi, Pedro Yoshito

    2012-10-01

    The aim of this study was to evaluate the influence of the platform-switching technique on stress distribution in implant, abutment, and peri-implant tissues, through a 3-dimensional finite element study. Three 3-dimensional mandibular models were fabricated using the SolidWorks 2006 and InVesalius software. Each model was composed of a bone block with one implant 10 mm long and of different diameters (3.75 and 5.00 mm). The UCLA abutments also ranged in diameter from 5.00 mm to 4.1 mm. After obtaining the geometries, the models were transferred to the software FEMAP 10.0 for pre- and postprocessing of finite elements to generate the mesh, loading, and boundary conditions. A total load of 200 N was applied in axial (0°), oblique (45°), and lateral (90°) directions. The models were solved by the software NeiNastran 9.0 and transferred to the software FEMAP 10.0 to obtain the results that were visualized through von Mises and maximum principal stress maps. Model A (implants with 3.75 mm/abutment with 4.1 mm) exhibited the highest area of stress concentration with all loadings (axial, oblique, and lateral) for the implant and the abutment. All models presented the stress areas at the abutment level and at the implant/abutment interface. Models B (implant with 5.0 mm/abutment with 5.0 mm) and C (implant with 5.0 mm/abutment with 4.1 mm) presented minor areas of stress concentration and similar distribution pattern. For the cortical bone, low stress concentration was observed in the peri-implant region for models B and C in comparison to model A. The trabecular bone exhibited low stress that was well distributed in models B and C. Model A presented the highest stress concentration. Model B exhibited better stress distribution. There was no significant difference between the large-diameter implants (models B and C).

  20. National Dam Safety Program. Jones Lake Dam (MO 31486), White River Basin, Oregon County, Missouri. Phase I Inspection Report.

    Science.gov (United States)

    1980-08-01

    flows are passed by an uicontrolled , concrete- lined earth cut spillway located in the left abutment. No operating facilities exist. 2.4 EVALUATION... creating an unsafe condition, these deficiencies should only be corrected under the direc- tion of an engineer experienced in the design and construc

  1. A method for designing plates in treatments of proximal humeral fracture and distal radial fracture

    Directory of Open Access Journals (Sweden)

    Lin Wang

    2016-11-01

    Full Text Available The purpose of this paper was to quickly design fixation plates for fractured proximal humerus and distal radius according to the requirements of surgical treatment. Therefore, a new method to quickly design cloverleaf plate appropriate for proximal humerus and volar plate appropriate for distal radius is put forward. First, three-dimensional (3D reconstruction models of fractured proximal humerus and distal radius were generated based on deforming mean parametric models of proximal humerus and distal radius, respectively. Second, based on region-of-interest marked on the 3D reconstruction model of proximal humerus and distal radius, abutted surfaces of cloverleaf plate and volar plate were established, respectively. Then, parametric abutted surface was established after setting rational parameters for the surface of the cloverleaf plate. Parametric abutted surface of volar plate was established using the same method. Finally, parametric cloverleaf plate and volar plate are generated through thickening their respective parametric abutted surfaces. The parametric plates, acting as templates, accelerate and simplify the design process and therefore allow users to construct plate with editing valid parameters easily. Group of cloverleaf plates and volar plates with different sizes were generated quickly, showing that the proposed method is feasible and effective.

  2. Impact of platform switching on inter-proximal bone levels around short implants in the posterior region; 1-year results from a randomized clinical trial

    NARCIS (Netherlands)

    Telleman, Gerdien; Raghoebar, Gerry M.; Vissink, Arjan; Meijer, Henny J. A.; Meyer, H.J.A.

    2012-01-01

    Aim To assess the outcome of short implants (8.5 mm) supplied with a conventional platform-matched implant-abutment connection or a platform-switched design. Materials and Methods Eighty patients with one or more missing teeth in the posterior zone were randomly assigned to be treated with implants

  3. 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…

  4. 77 FR 55459 - Takes of Marine Mammals Incidental to Specified Activities; Piling and Fill Removal in Woodard...

    Science.gov (United States)

    2012-09-10

    ... creosoted timber, pilings, metal scraps and concrete abutment 2. Piling and Structure Removal Remove 10,000... the status of the Washington inland waters stock of harbor seals and its occurrence in the action area... for the Washington Inland Waters stock of harbor seals, the number of individual seals harassed...

  5. That's really too bad

    Institute of Scientific and Technical Information of China (English)

    刘京西

    2009-01-01

    @@ Oh! I failed my final exam. B:That's really too bad! But don't feel upset about it. A:But what should I say to my father? B:Come on!It could have happened to anybody! A:唉,我期末考试没及格.

  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. A Three-Dimensional Finite Element Study on the Biomechanical Simulation of Various Structured Dental Implants and Their Surrounding Bone Tissues.

    Science.gov (United States)

    Zhang, Gong; Yuan, Hai; Chen, Xianshuai; Wang, Weijun; Chen, Jianyu; Liang, Jimin; Zhang, Peng

    2016-01-01

    Background/Purpose. This three-dimensional finite element study observed the stress distribution characteristics of 12 types of dental implants and their surrounding bone tissues with various structured abutments, implant threads, and healing methods under different amounts of concentrated loading. Materials and Methods. A three-dimensional geometrical model of a dental implant and its surrounding bone tissue was created; the model simulated a screw applied with a preload of 200 N or a torque of 0.2 N·m and a prosthetic crown applied with a vertical or an inclined force of 100 N. The Von Mises stress was evaluated on the 12 types of dental implants and their surrounding bone tissues. Results. Under the same loading force, the stress influence on the implant threads was not significant; however, the stress influence on the cancellous bone was obvious. The stress applied to the abutment, cortical bone, and cancellous bone by the inclined force applied to the crown was larger than the stress applied by the vertical force to the crown, and the abutment stress of the nonsubmerged healing implant system was higher than that of the submerged healing implant system. Conclusion. A dental implant system characterised by a straight abutment, rectangle tooth, and nonsubmerged healing may provide minimum value for the implant-bone interface.

  8. A Three-Dimensional Finite Element Study on the Biomechanical Simulation of Various Structured Dental Implants and Their Surrounding Bone Tissues

    Directory of Open Access Journals (Sweden)

    Gong Zhang

    2016-01-01

    Full Text Available Background/Purpose. This three-dimensional finite element study observed the stress distribution characteristics of 12 types of dental implants and their surrounding bone tissues with various structured abutments, implant threads, and healing methods under different amounts of concentrated loading. Materials and Methods. A three-dimensional geometrical model of a dental implant and its surrounding bone tissue was created; the model simulated a screw applied with a preload of 200 N or a torque of 0.2 N·m and a prosthetic crown applied with a vertical or an inclined force of 100 N. The Von Mises stress was evaluated on the 12 types of dental implants and their surrounding bone tissues. Results. Under the same loading force, the stress influence on the implant threads was not significant; however, the stress influence on the cancellous bone was obvious. The stress applied to the abutment, cortical bone, and cancellous bone by the inclined force applied to the crown was larger than the stress applied by the vertical force to the crown, and the abutment stress of the nonsubmerged healing implant system was higher than that of the submerged healing implant system. Conclusion. A dental implant system characterised by a straight abutment, rectangle tooth, and nonsubmerged healing may provide minimum value for the implant-bone interface.

  9. 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.

  10. 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.

  11. 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.

  12. 75 FR 5846 - Supplemental Notice of Intent To Prepare an Environmental Assessment and Request for Public...

    Science.gov (United States)

    2010-02-04

    ..., cultural resources, and visitor experiences of a national park unit and any tribal lands within or abutting... regarding sensitive park resources, tribal concerns, changes in tourism patterns, and air tour operations..., cultural, and historical resources. Input is also welcome on other areas to be addressed in...

  13. Mechanical design, analysis, and laboratory testing of a dental implant with axial flexibility similar to natural tooth with periodontal ligament.

    Science.gov (United States)

    Pektaş, Ömer; Tönük, Ergin

    2014-11-01

    At the interface between the jawbone and the roots of natural teeth, a thin, elastic, shock-absorbing tissue, called the periodontal ligament, forms a cushion which provides certain flexibility under mechanical loading. The dental restorations supported by implants, however, involve comparatively rigid connections to the jawbone. This causes overloading of the implant while bearing functional loading together with neighboring natural teeth, which leads to high stresses within the implant system and in the jawbone. A dental implant, with resilient components in the upper structure (abutment) in order to mimic the mechanical behavior of the periodontal ligament in the axial direction, was designed, analyzed in silico, and produced for mechanical testing. The aims of the design were avoiding high levels of stress, loosening of the abutment connection screw, and soft tissue irritations. The finite element analysis of the designed implant revealed that the elastic abutment yielded a similar axial mobility with the natural tooth while keeping stress in the implant at safe levels. The in vitro mechanical testing of the prototype resulted in similar axial mobility predicted by the analysis and as that of a typical natural tooth. The abutment screw did not loosen under repeated loading and there was no static or fatigue failure.

  14. 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.

  15. Spillway for Benbrook Dam, Clear Fork of the Trinity River, Texas: Model Investigation

    Science.gov (United States)

    1949-03-01

    section at tho too of tho spillway to tho trapezoidal cross section of tho exit channel. Concreto training walls 11 ft in height will confine the...embankment sections to the spillway, thus eliminating the concreto sec- tiona . This procedure would require training walls at each abutment t o protect

  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. 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.

  18. 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.

  19. Twelve-year results of a direct-bonded partial prosthesis in a patient with advanced periodontitis: a clinical report.

    Science.gov (United States)

    Minami, Hiroyuki; Minesaki, Yoshito; Suzuki, Shiro; Tanaka, Takuo

    2012-08-01

    Prosthodontic treatment for patients with advanced periodontitis is a therapeutic challenge. A minimally invasive technique is preferred to preserve the remaining mobile abutment teeth. This report describes the initial clinical treatment and 12-year follow-up of a direct-bonded prosthesis reinforced with a cast metal framework, used as a conservative treatment option to replace periodontally involved maxillary lateral incisors.

  20. Three-dimensional finite element analysis of platform switched implant

    Science.gov (United States)

    2017-01-01

    PURPOSE The purpose of this study was to analyze the influence of the platform switching concept on an implant system and peri-implant bone using three-dimensional finite element analysis. MATERIALS AND METHODS Two three-dimensional finite element models for wide platform and platform switching were created. In the wide platform model, a wide platform abutment was connected to a wide platform implant. In the platform switching model, the wide platform abutment of the wide platform model was replaced by a regular platform abutment. A contact condition was set between the implant components. A vertical load of 300 N was applied to the crown. The maximum von Mises stress values and displacements of the two models were compared to analyze the biomechanical behavior of the models. RESULTS In the two models, the stress was mainly concentrated at the bottom of the abutment and the top surface of the implant in both models. However, the von Mises stress values were much higher in the platform switching model in most of the components, except for the bone. The highest von Mises values and stress distribution pattern of the bone were similar in the two models. The components of the platform switching model showed greater displacement than those of the wide platform model. CONCLUSION Due to the stress concentration generated in the implant and the prosthodontic components of the platform switched implant, the mechanical complications might occur when platform switching concept is used. PMID:28243389

  1. Genetic Environment and Transcription of ampC in an Acinetobacter baumannii Clinical Isolate

    OpenAIRE

    Segal, Heidi; Nelson, E.C.; Elisha, B. Gay

    2004-01-01

    An ampC gene was cloned from a clinical isolate of Acinetobacter baumannii (strain RAN). DNA sequencing and primer extension studies showed that ampC is transcribed from a promoter contained within a putative insertion sequence element which has been found to abut several different genes in Acinetobacter spp.

  2. Magnetic expression of some major lineaments and cretaceous quiet zone in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Subrahmanyam, A.S.; Murthy, K.S.R.; Lakshminarayana, S.; Rao, M.M.M.; Venkateswarlu, K.; Rao, T.C.S.

    anomaly due to the 85¡E ridge abutting the continental shelf of Chilka Lake in ECMI. Studies by Mukhopadhyay and Krishna (1992) and Murthy et al. (1993) indicate that the landward limit of this quite zone is bounded by the COB at the foot...

  3. Surface hydride on titanium by cathodic polarization promotes human gingival fibroblast growth.

    Science.gov (United States)

    Xing, Rui; Salou, Laëtitia; Taxt-Lamolle, Sébastien; Reseland, Janne E; Lyngstadaas, Ståle P; Haugen, Håvard J

    2014-05-01

    Connective tissue seal to dental abutment is crucial for peri-implant health. Several efforts have been made previously to optimize abutment surfaces, but no consensus has been reached regarding the optimal surface architecture and/or composition for soft tissue seal. Here, we report on experiments using cathodic polarization in organic acids to optimize titanium (Ti) surfaces for use as abutments. The three main factors affecting surface topography and chemistry were electrolyte composition, current density, and polarization time. Under identical conditions, oxalic acid created rougher surfaces than tartaric acid and acetic acid, and acetic acid produced more surface hydride. Surface hydride amount was suggested to first increase and then decrease with current density from 1 mA/cm(2) to 15 mA/cm(2) . The complexity of the surface topography and hydride production both increased with polarization time. Proliferation rate of human gingival fibroblasts (HGFs) was positively correlated with surface hydride content, suggesting the positive effect of surface hydride on connective tissue growth around dental abutment. Changes in surface topography and hydrophilicity did not significantly influence HGF growth.

  4. Design of Parachute Component Materials from Kevlar 29 and 49

    Science.gov (United States)

    1976-07-01

    with warp yarns sized with 2% polyvinyl alcohol. Determination of the number of ends and picks per inch of a given yarn denier needed to obtain a...but it was found that application of as little as 1/2 to 1% of poly vinyl butyral to the thread gave better structural integrity, improved

  5. 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

    2017-01-01

    in a way to obtain variable buccal bone thicknesses. Three combinations regarding the implant-abutment metal (TiTi, TiZr, or ZrZr) and the number of implants (one, two, or three) were assessed. Two CBCT units (Scanora 3D - Sc and Cranex 3D - Cr) and two voxel resolutions (0.2 and 0.13 mm) were used...

  6. 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...

  7. 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

  8. 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.

  9. 16 CFR 1632.8 - Glossary of terms.

    Science.gov (United States)

    2010-01-01

    .... Two twin size bedding sets on frames, usually slipcovered, and abutted to a corner table. They also... folded or rolled up for storage. It usually consists of resilient material covered by ticking. (p) High... usually be converted into a playpen. (v) Press-back lounges. Longer and wider than conventional sofa...

  10. [Loading and strength of single- and multi-unit fixed dental prostheses. 1. Retention and resistance

    NARCIS (Netherlands)

    Baat, C. de; Witter, D.J.; Meijers, C.C.A.J.; Vergoossen, E.L.; Creugers, N.H.J.

    2014-01-01

    The degree to which single- and multi-unit fixed dental prostheses are able to withstand loading forces is dependent, among other things, on the quality of their retention and resistance. The quality of the retention and resistance of the configuration of an abutment tooth prepared for a metal and m

  11. Proceedings of the 1997 Battlespace Atmospherics Conference 2-4 December 1997

    Science.gov (United States)

    1998-03-01

    and M-inch thick aluminum plates treated with Camouflage Chemical Agent Resitant Coating (CARC). One side of each plate firmly abuts the styrofoam...to a octopus low frequency pass filter. The octopus is actually PVC piping with holes along its length. The reason for the pipe array is to filter

  12. 77 FR 25781 - Environmental Impact Statement; Washington, DC

    Science.gov (United States)

    2012-05-01

    ... & Environmental Division, Infrastructure Project Management Administration, District of Columbia, Department of... Southeast Freeway abuts the north side of Virginia Avenue SE throughout nearly all the project limits. In... future increase demand for freight land transportation in the U.S. The current deficiencies of...

  13. 76 FR 63914 - Sabine River Authority of Texas and Sabine River Authority, State of Louisiana; Notice of...

    Science.gov (United States)

    2011-10-14

    ... Louisiana; Notice of Application Tendered for Filing With the Commission and Establishing Procedural... 80-foot-wide, 55-foot-high powerhouse located in the right abutment, containing two vertical Kaplan... FERC Online Support. n. Procedural Schedule: The application will be processed according to...

  14. METHOD AND SYSTEM FOR LASER WELDING

    DEFF Research Database (Denmark)

    2008-01-01

    The invention relates to laser welding of at least two adjacent, abutting or overlapping work pieces in a welding direction using multiple laser beams guided to a welding region, wherein at least two of the multiple laser beams are coupled into the welding region so as to form a melt and at least...

  15. 30 CFR 816.81 - Coal mine waste: General requirements.

    Science.gov (United States)

    2010-07-01

    ... foundation and abutments must be stable under all conditions of construction. (d) Foundation. Sufficient foundation investigations, as well as any necessary laboratory testing of foundation material, shall be...) Ensure mass stability and prevent mass movement during and after construction; (3) Ensure that the...

  16. 30 CFR 816.71 - Disposal of excess spoil: General requirements.

    Science.gov (United States)

    2010-07-01

    ... construction periods. Critical construction periods shall include at a minimum: (i) Foundation preparation... construction; (3) Ensure that the final fill is suitable for reclamation and revegetation compatible with the... a minimum long-term static safety factor of 1.5. The foundation and abutments of the fill must...

  17. 30 CFR 715.18 - Dams constructed of or impounding waste material.

    Science.gov (United States)

    2010-07-01

    ... loading) 1.0 (iv) The dam, foundation, and abutments shall be stable under all conditions of construction...) of this section and for all increments of construction. (v) Seepage through the dam, foundation, and...) constructed of waste materials, in accordance with the requirements of this section. (b) Construction of...

  18. 30 CFR 817.81 - Coal mine waste: General requirements.

    Science.gov (United States)

    2010-07-01

    ... 1.5. The foundation and abutments must be stable under all conditions of construction. (d) Foundation. Sufficient foundation investigations, as well as any necessary laboratory testing of foundation...) Ensure mass stability and prevent mass movement during and after construction; (3) Ensure that the...

  19. 76 FR 51929 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To Delist the Valley...

    Science.gov (United States)

    2011-08-19

    ... become an adult, since the adults are not wood borers. The larva remains within the stem, becomes a pupa... also abut or overlap in that area. The beetle is a wood borer, dependent on, and found only in... in small groups, on the leaves or stems of living elderberry shrubs (Barr 1991, p. 4). The...

  20. 77 FR 60237 - Endangered and Threatened Wildlife and Plants; Removal of the Valley Elderberry Longhorn Beetle...

    Science.gov (United States)

    2012-10-02

    ... not wood borers. The larva remains within the stem, becomes a pupa, and finally emerges from its... in the southern San Joaquin Valley. This subspecies is a wood borer that is dependent on its host... also abut or overlap in that area. The valley elderberry longhorn beetle is a wood borer, dependent...

  1. Mechanical behavior of quartz fiber reinforced epoxy resins for teeth restoration.

    Science.gov (United States)

    Visco, A M; Calabrese, L; Campo, N; Torrisi, L; Oteri, G; Lo Giudice, G; Cicciù, D

    2006-01-01

    In this work composite materials, based on quartz fibers and epoxy resins, were employed with the aim to restore damaged teeth. The composite materials were chosen because they show biomechanical features very similar to that of the dentine, the main constituent of the tooth. Extracted teeth were rebuilt with two different restorative procedures: in the first, the composite material was pre-formed in a conical trunk shape abutment (PA) and then bonded to a fiber quartz post with a dental bonder. In the second rebuilt system the abutment was prepared by cross linking the resin on the fiber quartz post with a halogen lamp (CRA). The restored teeth were then mechanically tested and observed with a Scanning Electron Microscope (SEM) with the aim to study the interaction between the reconstructive materials. Wetting and roughness measurements were also carried out in order to study the interface adhesion between the post and the abutments. Characterization analysis evidenced that the CRA restorative procedure improves the adhesion between the substitutive materials and shows higher fracture strength than the PA ones. Anyway both the rebuilt systems are able to support the masticator load. An explanation of the interfacial post-abutment interaction phenomenon is discussed.

  2. 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.

  3. Clinical and radiologic evaluation of 2-stage IMZ implants placed in a single-stage procedure : 2-year results of a prospective comparative study

    NARCIS (Netherlands)

    Heydenrijk, K; Raghoebar, GM; Meijer, HJA; Stegenga, B

    2003-01-01

    Purpose: The aim of this study was to evaluate the feasibility of using a 2-stage implant system in a single-stage procedure and to study the impact of the microgap between the implant and the abutment. Materials and Methods: Sixty edentulous patients (Cawood class V or VI) participated in this stud

  4. 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.

  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. 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.

  7. [Monitoring trends in fixed partial denture design based on national surveys].

    Science.gov (United States)

    Fejérdy, Pál; Tollas, Ors Lehel; Fejérdy, László; Borbély, Judit; Hermann, Peter

    2007-12-01

    To restore partially edentulous arches reasonable number of fixed partial dentures (FPD) are used in Hungary. This paper describes statistic parameters of these restorations based on analysis of a large sample size. Dentists of the Department of Prosthodontics performed oral health surveys according to WHO criteria, first survey in 1985-1989 and second in 2003-2004. The oral surveys were carried out at the lung cancer screening stations among those individuals originally referred to undergo x-ray lung screening examination. In the "first" survey data collected on 6224 FPD; in the "second" survey data collected on 3676 fixed restorations were analyzed. Besides time parameters, number of pontic teeth, abutment teeth to pontic teeth ratio (abutment saturation), position of pontic teeth in the arch, position of abutment teeth in the arch, main features of "tooth location" adjacent to restoration (remnant tooth, crown, artificial tooth, missing tooth), framework- and veneering materials were investigated. For interpreting data SPSS 10.0.5 for Windows was applied. Restorations' mean survival time was 9.34 +/- 8.47 years. Average number of FPD unit was: 6.34 for the maxillary and 4.62 for the mandibular jaw. Average number of abutment teeth was 3.58 in the upper and 2.82 in the lower jaw. Most frequent abutment teeth of both the maxillary and mandibular jaw were canines (23%) (20%). In order of frequency: pontics of the upper jaw replaced first premolars (27%) and second premolars (23%); lower jaw pontics replaced first molars (36%) and second premolars (21%). Findings of our survey demonstrated that results were much jaw dependent, while participants' sex and age influenced the outcome less. Comparison between left and right side of the arch revealed considerable symmetry. Recently collected data of 2004 have shown increased extension of fixed partial dentures with significantly higher number of abutment teeth involved. Statistical analysis of data collected on fixed

  8. A hedgehog-responsive region in the Drosophila wing disc is defined by debra-mediated ubiquitination and lysosomal degradation of Ci.

    Science.gov (United States)

    Dai, Ping; Akimaru, Hiroshi; Ishii, Shunsuke

    2003-06-01

    Transcription factor Ci mediates Hedgehog (Hh) signaling to determine the anterior/posterior (A/P) compartment of Drosophila wing disc. While Hh-inducible genes are expressed in A compartment cells abutting the A/P border, it is unclear how the boundaries of this region are established. Here, we have identified a Ci binding protein, Debra, that is expressed at relatively high levels in the band abutting the border of the Hh-responsive A compartment region. Debra mediates the polyubiquitination of full-length Ci, which then leads to its lysosomal degradation. Debra is localized in the multivesicular body, suggesting that the polyubiquitination of Ci directs its sorting into lysosome. Thus, Debra defines the border of the Hh-responsive region in the A compartment by inducing the lysosomal degradation of Ci.

  9. 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

  10. 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...

  11. A preliminary study on the short-term efficacy of chairside computer-aided design/computer-assisted manufacturing- generated posterior lithium disilicate crowns.

    Science.gov (United States)

    Reich, Sven; Fischer, Sören; Sobotta, Bernhard; Klapper, Horst-Uwe; Gozdowski, Stephan

    2010-01-01

    The purpose of this preliminary study was to evaluate the clinical performance of chairside-generated crowns over a preliminary time period of 24 months. Forty-one posterior crowns made of a machinable lithium disilicate ceramic for full-contour crowns were inserted in 34 patients using a chairside computer-aided design/computer-assisted manufacturing technique. The crowns were evaluated at baseline and after 6, 12, and 24 months according to modified United States Public Health Service criteria. After 2 years, all reexamined crowns (n = 39) were in situ; one abutment exhibited secondary caries and two abutments received root canal treatment. Within the limited observation period, the crowns revealed clinically satisfying results.

  12. 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.

  13. 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.

  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. Dynamic Properties of the Painter Street Overpass at Different Levels of Vibration

    DEFF Research Database (Denmark)

    Ventura, C. E.; Brincker, Rune; Andersen, P.

    2005-01-01

    in California. Strong motion instruments were installed on the bridge in 1977, and since then it has recorded the motions from more than ten significant earthquakes. Because of the valuable amount of strong motion data available, the aim of the ambient vibration tests was to determine the dynamic...... from analyses of selected strong motion records. The magnitude of the events investigated ranges from ML=4.4 to ML=6.9, which produced accelerations of up to 0.54g at the free field site, 1.3g at the abutments, and 0.86g on the deck. The results of this study indicate that the overall dynamic...... properties of the bridge are very sensitive to the level of ground shaking and that soil-structure interaction is very important for this type structural system. Although the superstructure exhibited a nearly elastic response, the motions at the abutments and base of piers were significantly different...

  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. Optimal restoration of dental esthetics and function with advanced implant-supported prostheses: a clinical report.

    Science.gov (United States)

    Meulen, Peter van der; Linden, Wynand van der; Eeden, Ronnie van

    2012-07-01

    For more than 25 years, computer-aided design and computer-aided manufacturing (CAD/CAM) technology has been used in implant restorative dentistry. Today this technology offers a means of milling titanium frameworks that fit dental implants accurately. This report presents a restoratively driven protocol employing advanced implant restorative and surgical techniques. Treatment of a patient with advanced periodontitis with extensive loss of hard and soft tissues is presented. After extraction of the patient's remaining hopeless teeth, dental implants were placed, along with interim, fixed-margin abutments and abutment protection caps. Two days later, acrylic resin fixed-interim prostheses restored the patient's esthetics and partial masticatory function. After implant osseointegration, maxillary, and mandibular frameworks for definitive prostheses were milled from Ti alloy, using one specific CAD/CAM technology. The benefits of this technology are also discussed.

  19. 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...

  20. 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.

  1. Analyzing Engineering Geology Condition of Dam Site of Mohe Water Supply Hydroproject and Comparing Type of Dam%磨河供水工程枢纽坝址工程地质条件分析及坝型比选

    Institute of Scientific and Technical Information of China (English)

    高峰

    2012-01-01

    In this paper,the strata textures and structures of dam foundation and dam abutment of Mohe Water Supply Hydroproject are investigated,surveyed and analyzed,Through initial analysis on stability of dam foundation and dam abutment,the applicability of two dam types is compared roughly.The two types of dam are stone masonry gravity dam and arch dam.And the gravity dam is recommended.%对磨河供水工程枢纽坝址的坝基、坝肩地层结构、构造进行了调查、勘测研究。通过坝基、坝肩的稳定性初步分析,比较了浆砌石重力坝及拱坝的适用性,推荐采用重力坝。

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

    Science.gov (United States)

    Rinke, S; Schäfer, S; Roediger, M

    2011-01-01

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

  3. 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.

  4. 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

  5. KUPSnet: Knowledge-based Ubiquitous and Persistent Sensor Network Testbed for Threat Assessment

    Science.gov (United States)

    2010-09-16

    investigate wireless propa- gation channels. In the narrowband case, Rayleigh, Rician, and Nakagami distributions were used to model the flat fading, and a...but also compare it with other popular clutter models, namely, log-normal, Weibull, and Nakagami . It shows that the log-logistic model achieves the...Additionally, we compare the goodness-of-fit of LLD with existing popular models, namely, log-normal, Weibull, and Nakagami by means of maximum likelihood

  6. Worldwide Report, Environmental Quality, No. 406.

    Science.gov (United States)

    2007-11-02

    Levi Vega M ’Drastic’ Measures Adopted MEXICO Lack of Irrigation Intensifies Drought in Veracruz (Rogelio Freyre; EXCELSIOR, 12 May 83) 33...of na- tive flora and fauna. ^ It had been created $>y consolidating sever- al- existing reserves and adding two abut- ting strips...in this period was reclaimed and that was not fully reclaimed. -The chief threat to flora is the constant tendency of man to lower the variety of

  7. 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.

  8. A comparison of vernier acuity for narrowband and broadband stimuli.

    Science.gov (United States)

    Barrett, Brendan T; Whitaker, David

    2004-01-01

    This study investigates the influence of contrast and exposure duration on vernier acuity thresholds for abutting and separated narrowband stimuli, and asks whether these data can predict broadband vernier performance. Vernier thresholds were determined for sinusoidal grating stimuli at two spatial frequencies (1 and 8 c/deg) across a range of contrasts (0.05-0.8) and exposure durations (35-2100 ms). Performance was assessed for the abutting configuration, and when a gap equivalent to 0.5 to 1.5 times the spatial period of the grating was introduced between the upper and lower halves of the grating. Vernier thresholds were also determined for a square-wave stimulus as a function of contrast (0.06 to 0.78). Exposure duration was fixed at 2100 ms. In addition, thresholds were determined at the appropriate contrast levels for the fundamental frequency (1.8 c/deg) of the square-wave, and for a number of the harmonics (3F, 5F, 7F, 9F). Our results provide support for filter models of vernier acuity by showing that vernier performance for abutting and closely-separated broadband stimuli represents the envelope of vernier sensitivity of those spatial frequency mechanisms that are activated by the broadband stimulus. In the case of high frequency grating stimuli presented for long exposure durations, vernier performance can be invariant across much of the contrast range. Despite this, however, contrast independence is not exhibited for abutting broadband stimuli because, within the broadband stimuli, the contrast of the higher harmonic components never reaches a level to reveal this plateau.

  9. 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.

  10. A Prospective Clinical and Radiographic Assessment of Platform-Switched Laser-Microchannel Implants Placed in Limited Interimplant Spaces.

    Science.gov (United States)

    Nevins, Myron; Leziy, Sonia; Kerr, Eric; Janke, Ulrich; Rasperini, Giulio; Hanratty, James; Pasquinelli, Kirk; Testori, Tiziano; Shapoff, Cary A; Kim, David M

    This multicenter clinical trial of platform-switched laser-microchannel implants supports findings from a previous preclinical trial. Previous information indicated that an interimplant distance narrower than 3 mm would result in decrease in the crestal bone level, but the results of this investigation suggest that a more optimistic clinical result can be anticipated for implants and abutments with a laser-microchannel surface.

  11. Intelligence Support to Urban Operations

    Science.gov (United States)

    2015-12-01

    consideration because they have been specifically built for military purposes. Permanent-type fortifications can be made of earth , wood, rock, brick...changes to selected routes. Where urban areas abut the ocean or sea, large lakes, and major rivers, the surface of these bodies of water may provide...utility systems. In older cities, they may include ancient hand-dug tunnels and catacombs. Both attacker and defender can use subsurface areas to

  12. Finite Element Analysis of the Effect of Superstructure Materials and Loading Angle on Stress Distribution around the Implant

    OpenAIRE

    Jafari K; Vojdani M; Mahdavi F; Heidary H

    2014-01-01

    Statement of Problem: A general process in implant design is to determine the reason of possible problems and to find the relevant solutions. The success of the implant depends on the control technique of implant biomechanical conditions. Objectives: The goal of this study was to evaluate the influence of both abutment and framework materials on the stress of the bone around the implant by using threedimensional finite element analysis. Materials and Methods: A three-dimensi...

  13. A Three-Dimensional Finite Element Study on the Biomechanical Simulation of Various Structured Dental Implants and Their Surrounding Bone Tissues

    OpenAIRE

    Zhang, Gong; Yuan, Hai; Chen, Xianshuai; Wang, Weijun; Chen, Jianyu; Liang, Jimin; Zhang, Peng

    2016-01-01

    Background/Purpose. This three-dimensional finite element study observed the stress distribution characteristics of 12 types of dental implants and their surrounding bone tissues with various structured abutments, implant threads, and healing methods under different amounts of concentrated loading. Materials and Methods. A three-dimensional geometrical model of a dental implant and its surrounding bone tissue was created; the model simulated a screw applied with a preload of 200 N or a torque...

  14. Finite Element Analysis of the Effect of Superstructure Materials and Loading Angle on Stress Distribution around the Implant

    Directory of Open Access Journals (Sweden)

    Jafari K

    2014-12-01

    Full Text Available Statement of Problem: A general process in implant design is to determine the reason of possible problems and to find the relevant solutions. The success of the implant depends on the control technique of implant biomechanical conditions. Objectives: The goal of this study was to evaluate the influence of both abutment and framework materials on the stress of the bone around the implant by using threedimensional finite element analysis. Materials and Methods: A three-dimensional model of a patient’s premaxillary bone was fabricated using Cone Beam Computed Tomography (CBCT. Then, three types of abutment from gold, nickel-chromium and zirconia and also three types of crown frame from silver-palladium, nickel-chromium and zirconia were designed. Finally, a 178 N force at angles of zero, 30 and 45 degrees was exerted on the implant axis and the maximum stress and strain in the trabecular, cortical bones and cement was calculated. Results: With changes of the materials and mechanical properties of abutment and frame, little difference was observed in the level and distribution pattern of stress. The stress level was increased with the rise in the angle of pressure exertion. The highest stress concentration was related to the force at the angle of 45 degrees. The results of the cement analysis proved an inverse relationship between the rate of elastic modulus of the frame material and that of the maximum stress in the cement. Conclusions: The impact of the angle at which the force was applied was more significant in stress distribution than that of abutment and framework core materials.

  15. 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.

  16. 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.

  17. A dual epimorphic and compensatory mode of heart regeneration in zebrafish

    OpenAIRE

    Sallin, Pauline; de Preux Charles, Anne-Sophie; Duruz, Vincent; Pfefferli, Catherine; Jaźwińska, Anna

    2015-01-01

    Zebrafish heart regeneration relies on the capacity of cardiomyocytes to proliferate upon injury. To understand the principles of this process after cryoinjury-induced myocardial infarction, we established a spatio-temporal map of mitotic cardiomyocytes and their differentiation dynamics. Immunodetection of phosphohistone H3 and embryonic ventricular heavy chain myosin highlighted two distinct regenerative processes during the early phase of regeneration. The injury-abutting zone comprises a ...

  18. Evaluation in Accuracy to Two Impression Techniques: In Case of Bone Anchored Bridge

    OpenAIRE

    Sularsih Sularsih; Ishida, O; Meinar Nur Ashrin; Okajima, M; Ichikawa, T.

    2013-01-01

    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...

  19. 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.

  20. Histological evaluation of bone reactions to aluminium oxide dental implants in man: a case report.

    Science.gov (United States)

    Piattelli, A; Podda, G; Scarano, A

    1996-04-01

    Alumina implants have been shown to possess high biocompatibility. The authors present the case of an aluminium oxide ceramic implant removed because of fracture of the abutment after a 30-month loading period. It was possible to observe microscopically that the implant was covered by highly mineralized mature compact lamellar bone; no connective tissue or inflammatory cells were present at the interface. Osteocytes were observed very close to the bone-implant interface. These features indicate the good biocompatibility of the implant.

  1. Novel Techniques with the Aid of a Staged CBCT Guided Surgical Protocol

    OpenAIRE

    Evdokia Chasioti; Mohammed Sayed; Howard Drew

    2015-01-01

    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 sin...

  2. 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.

  3. 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.

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

    Directory of Open Access Journals (Sweden)

    Prakash Kumar Dubey

    2014-01-01

    Full Text Available 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.

  5. 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.

  6. National Program for Inspection of Non-Federal Dams. Richville Dam (VT 00074) Richelieu River Basin, Shoreham.

    Science.gov (United States)

    1978-09-01

    the Champlain Thrust Fault uplifted the Paleozoic carbonates and quartzites to overlie the younger shales. A branch of this fault known as the Orwell ...abutment will be overtopped) is 260 cfs. iPlanimetered from Bridport, Vt.; Sudbury, Vt.; Orwell , Vt; Vt-N.Y.; and Cornwall, Vt. 7.5 minute quad theets...the following pertinent facts with relation S to this project frc. testimony of George ’?. Davis and Roger Seamans of thu Fish & Ga-e Service: (1) The

  7. In Situ Repair of Deteriorated Concrete in Hydraulic Structures: Feasibility Study

    Science.gov (United States)

    1987-05-01

    wider. Since formwork is not required, drypack is especially appropriate for use in vertical members. It is not appropriate for the repair of...improve the abrasion resistance of the concrete in outlet tunnel walls of dams. The impregnation process consists of four basic steps: a...to repair piles, footings, piers, retaining walls, abutments, base plates, tunnels , and dams. Preplaced-aggregate concrete provides low shrinkage

  8. 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...

  9. 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.

  10. Modified Technique for Making Auto-polymerized Polymethylmethacrylate Resin Custom Tray

    OpenAIRE

    Chidambaranathan, Ahila Singaravel; Reddy, Ramesh; Rajendran, Suresh; Balasubramaniam, Muthu Kumar

    2016-01-01

    Custom made tray for dental impression is designed to provide a uniform space for the impression material and thereby improve the accuracy of the resultant working cast. Auto-polymerized acrylic resins have been the most commonly used material for the fabrication of these trays. The custom tray produces more accurate and reliable results for inter-abutment distance at the occlusal and gingival level than stock trays. This article describes a modified technique for fabrication of auto-polymeri...

  11. Implant Gigi One-Piece vs Two-Pieces dalam Praktek Sehari-Hari

    Directory of Open Access Journals (Sweden)

    Dian Lestari Kurnia

    2014-12-01

    prosedur bedah dan prosedur prostetik lebih sederhana. Desain ini juga meniadakan celah mikro pada perbatasan implant dan abutment. Desain implant gigi one-piece memiliki keterbatasan pada pilihan prosedur prostetik apabila dibandingkan dengan desain implant gigi two-pieces.   One-Piece Versus Two-pieces Tooth Implant In Daily Practice. Implant had been a gold standard to replace missing tooth. However, implant marketed today was considered complex, and needs a second surgery. Complications may occur such as screw loosening or fracture and the presence of micro gap at implant-abutment-junction that is found causing fixture failure. The one-piece-implant design may offer some advantages. Purpose: this paper was aimed to discuss the pros and cons of one-piece-implants and two-piece-implants. Case 1 A 43-year-old woman came to place an implant on #16. The available bone height was 5 mm. A trans alveolar sinus lift procedure was performed with 0,5 cc allograft. A 12 mm one-piece-implant was inserted. Case 2 A 24-year-old woman came to place an implant on #46. The available bone height was 12 mm and a 10 mm two-piece-implant was inserted. Discussion: One-piece-implant offers some advantage. It needs no second surgery, easier placement protocol, and more natural prosthetic procedures. The design is preventing the failure in implant-abutment-junction failure. The absence of micro gap in one-piece-implant seems superior in preventing crestal bone resorption. However, the prosthetic option was limited in one-piece-implant. Two-piece-implant offers more choices in prosthetic abutment. Conclusion: One-piece-implant was easier and provide simple protocol with limited choice on prosthetic.

  12. Implant Gigi One-Piece vs Two-Pieces dalam Praktek Sehari-Hari

    OpenAIRE

    Dian Lestari Kurnia; Amilia Ramadhani; Rikko Hudyono

    2014-01-01

    Saat ini, implant merupakan pilihan terbaik untuk menggantikan gigi yang tanggal, akan tetapi prosedur pemasangannya terbilang rumit dan memerlukan prosedur bedah kedua untuk pemasangan prostetik. Beberapa komplikasi seperti screw patah atau longgar dan adanya celah mikro pada batas pertemuan implant dan abutment dapat menyebabkan kegagalan implant. Studi kasus ini bertujuan untuk membahas mengenai keuntungan dan kerugian desain implant gigi one-piece dan two-pieces. Kasus pertama, seorang wa...

  13. 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.

  14. 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...

  15. MR imaging manifestations of skin tumors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeong-hyon; Kim, Jee Young [The Catholic University of Korea, Department of Diagnostic Radiology, St. Vincent' s Hospital, Suwon, Gyeonggi-do (Korea); Chun, Kyung Ah [The Catholic University of Korea, Department of Diagnostic Radiology, Uijeongbu St. Mary Hospital, Uijeongbu, Gyeonggi-do (Korea); Jee, Won-Hee [The Catholic University of Korea, Department of Diagnostic Radiology, Kangnam St. Mary' s Hospital, Seoul (Korea); Sung, Mi-Sook [The Catholic University of Korea, Department of Diagnostic Radiology, Holy family Hospital, Bucheon, Gyeonggi-do (Korea)

    2008-11-15

    In this study, we evaluated MR imaging findings of skin tumors and categorized them into four types: (1) discrete mass lesions of the dermis and epidermis, (2) mass lesions of the subcutis with or without abutment to the skin, (3) diffuse or localized skin thickening without a true mass, and (4) a skin mass with bone destruction. The categorization of MR images may be useful in the differential diagnosis of skin tumors. (orig.)

  16. A technique to stabilize record bases for Gothic arch tracings in patients with implant-retained complete dentures.

    Science.gov (United States)

    Raigrodski, A J; Sadan, A; Carruth, P L

    1998-12-01

    Clinicians have long expressed concern about the accuracy of the Gothic arch tracing for recording centric relation in edentulous patients. With the use of dental implants to assist in retaining complete dentures, the problem of inaccurate recordings, made for patients without natural teeth, can be significantly reduced. This article presents a technique that uses healing abutments to stabilize the record bases so that an accurate Gothic arch tracing can be made.

  17. Influence of fine threads and platform-switching on crestal bone stress around implant-a three-dimensional finite element analysis.

    Science.gov (United States)

    Khurana, Pardeep; Sharma, Arun; Sodhi, Kiranmeet Kaur

    2013-12-01

    The aims of this study were to investigate the effect of implant fine threads on crestal bone stress compared to a standard smooth implant collar and to analyze how different abutment diameters influenced the crestal bone stress level. Three-dimensional finite element imaging was used to create a cross-sectional model in SolidWorks 2007 software of an implant (5-mm platform and 10 mm in length) placed in the premolar region of the mandible. The implant model was created to resemble a commercially available fine thread implant. Abutments of different diameters (5.0 mm: standard, 4.5 mm, 4.0 mm, and 3.5 mm) were loaded with a force of 100 N at 90° vertical and 40° oblique angles. Finite element analysis was done in COSMOSWorks software, which was used to analyze the stress patterns in bone, especially in the crestal region. Upon loading, the fine thread implant model had greater stress at the crestal bone adjacent to the implant than the smooth neck implant in both vertical and oblique loading. When the abutment diameter decreased progressively from 5.0 mm to 4.5 mm to 4 mm and to 3.5 mm the thread model showed a reduction of stress at the crestal bone level from 23.2 MPa to 15.02 MPa for fine thread and from 22.7 to 13.5 MPa for smooth collar implant group after vertical loading and from 43.7 MPa to 33.1 MPa in fine thread model and from 36.9 to 20.5 MPa in smooth collar implant model after oblique loading. Fine threads increase crestal stress upon loading. Reduced abutment diameter that is platform switching resulted in less stress translated to the crestal bone in the fine thread and smooth neck.

  18. A root submergence technique for pontic site development in fixed dental prostheses in the maxillary anterior esthetic zone

    OpenAIRE

    Choi, Sunyoung; Yeo, In-Sung; Kim, Sung-Hun; Lee, Jai-Bong; Cheong, Chan Wook; Han, Jung-Suk

    2015-01-01

    Purpose This case report discusses the effect of a root submergence technique on preserving the periodontal tissue at the pontic site of fixed dental prostheses in the maxillary anterior aesthetic zone. Methods Teeth with less than ideal structural support for fixed retainer abutments were decoronated at the crestal bone level. After soft tissue closure, the final fixed dental prostheses were placed with the pontics over the submerged root area. Radiographic and clinical observations at the p...

  19. 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

  20. Preformed stainless steel crown in special conditions in adults: Two case reports

    OpenAIRE

    Madhu, S

    2015-01-01

    Stainless steel crowns (SSC) are extensively used in child patients. They are mainly used following the pulp therapy in deciduous teeth. They are also used in multi-surface restoration, as an abutment in space maintainers, correction of anterior tooth cross bite, restoration of hypoplasic teeth, etc. In permanent teeth, they are mainly used as interim restorations following root canal treatment in first molars prior to the eruption of permanent second molars. The main advantage of SSC is its ...

  1. 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...

  2. The conversion partial denture: a clinical report.

    Science.gov (United States)

    Waliszewski, Michael P; Brudvik, James S

    2004-04-01

    The treatment alternative described maximizes the benefit of remaining teeth while allowing simplified alteration of the prosthesis if abutments are lost during the life span of the removable partial denture (RPD). A conversion partial is an RPD whose tooth-frame assembly components are individually fabricated and then joined with an acrylic resin major connector. The conversion RPD optimizes retention and stabilization of a terminal dentition and can be easily converted to an immediate complete denture.

  3. 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.

  4. Transmission block to simplify combined pelvic and inguinal radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Kalnicki, S.; Zide, A.; Maleki, N.; DeWyngaert, J.K.; Lipsztein, R.; Dalton, J.F.; Bloomer, W.D.

    1987-08-01

    A homogeneous dose distribution of radiation to inguinal lymph nodes and deep pelvic structures can be achieved with use of a transmission block over the central portion of a large anterior pelvic-inguinal portal, together with a smaller posterior field. This relatively simple technique permits individualization of isodose distributions and eliminates the problems of matching abutting portals. Reproducibility of daily setup and optimization of machine utilization are both improved.

  5. Transmission block to simplify combined pelvic and inguinal radiation therapy.

    Science.gov (United States)

    Kalnicki, S; Zide, A; Maleki, N; DeWyngaert, J K; Lipsztein, R; Dalton, J F; Bloomer, W D

    1987-08-01

    A homogeneous dose distribution of radiation to inguinal lymph nodes and deep pelvic structures can be achieved with use of a transmission block over the central portion of a large anterior pelvic-inguinal portal, together with a smaller posterior field. This relatively simple technique permits individualization of isodose distributions and eliminates the problems of matching abutting portals. Reproducibility of daily setup and optimization of machine utilization are both improved.

  6. 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.

  7. Cast Partial Denture versus Acrylic Partial Denture for Replacement of Missing Teeth in Partially Edentulous Patients

    Directory of Open Access Journals (Sweden)

    Pramita Suwal

    2017-03-01

    Full Text Available Aim: To compare the effects of cast partial denture with conventional all acrylic denture in respect to retention, stability, masticatory efficiency, comfort and periodontal health of abutments. Methods: 50 adult partially edentulous patient seeking for replacement of missing teeth having Kennedy class I and II arches with or without modification areas were selected for the study. Group-A was treated with cast partial denture and Group-B with acrylic partial denture. Data collected during follow-up visit of 3 months, 6 months, and 1 year by evaluating retention, stability, masticatory efficiency, comfort, periodontal health of abutment. Results: Chi-square test was applied to find out differences between the groups at 95% confidence interval where p = 0.05. One year comparison shows that cast partial denture maintained retention and stability better than acrylic partial denture (p< 0.05. The masticatory efficiency was significantly compromising from 3rd month to 1 year in all acrylic partial denture groups (p< 0.05. The comfort of patient with cast partial denture was maintained better during the observation period (p< 0.05. Periodontal health of abutment was gradually deteriorated in all acrylic denture group (p

  8. 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.

  9. 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.

  10. 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. PMID:27555900

  11. 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.

  12. 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.

  13. 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.

  14. Prosthetic reconstruction with an obturator using swing-lock attachment for a patient underwent maxillectomy: A clinical report

    Science.gov (United States)

    2016-01-01

    Patients who underwent resection of maxilla due to benign or malignant tumor, or accident will have defect in palatal area. They get retention, support and stability from remaining tissues which are hardly optimal. The advantage of swing-lock attachment design is having multiple contacts on labial and lingual side of the abutment teeth by retentive strut and palatal bracing component. Because the force is distributed equally to abutment teeth, abutment teeth of poor prognosis can be benefited from it. It is also more advantageous to cover soft tissue defects which are hard to reach with conventional prosthesis. A 56-year-old female patient who had undergone a maxillectomy due to malignant melanoma complaining of loose and unstable surgical obturator. Surveyed crowns were placed on #12, 26, and 27. Teeth #11, 21, 22, and 23 had lingual rest seat and #24 had mesial rest seat to improve stability and support of the obturator. This clinical report presents the prosthetic management of a patient treated with obturator on the maxilla using swing-lock attachment to the remaining teeth. PMID:27826392

  15. Does dental zinc phosphate cement really shrink in clinical applications?

    Science.gov (United States)

    Liu, Yang; Yu, Hai-Yang

    2009-08-01

    Crowns are cemented onto abutments with adhesives; and zinc phosphate cement is a routine permanent luting agent, which is believed to secure crowns to abutments by non-adhesive micro-mechanical interlocking. Because it has been proven, and the public widely accepts, that zinc phosphate cement forms no chemical bonds with either the crown or the tooth tissue; it is impossible for the cement to attain adequate retention force if it contracts in volume. Assuming that the cement contracts in volume after setting, the prosthesis tends to loose and is doomed to be hampered by fretting damage when it functions during the masticatory cycle; thus the prognosis for the prosthesis is questionable. However, zinc phosphate is popular because of its brilliant clinical record. This paradox between theory and practice indicates that something might be wrong with the standing theory. The most possible problem with previous studies is that their samples' dimensions differ from those that are used clinically, which causes the studies' results, which claim that the cement shrinks, to deviate from clinical results. The real rationale must be that the zinc phosphate cement tends to expand in volume, and thus mechanically fasten the crown to the abutment.

  16. 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.

  17. Decision-making for treatment planning a cantilevered fixed partial denture.

    Science.gov (United States)

    Hill, Edward E

    2009-01-01

    Considerable controversy exists in the dental literature regarding cantilevered pontics. This article discusses basic concepts of the cantilever fixed partial denture (CFPD) in which one cantilevered pontic is supported by only one or two abutment teeth. Three primary factors should be considered carefully to optimize the prognosis for a CFPD: abutment selection, control of functional forces, and rigidity/strength of connectors. Abutments should have a root surface area greater than the tooth being replaced and a crown-to-root ratio of 2:3. They also should exhibit minimal mobility and be vital and periodontally sound. Contact on cantilevered pontics should be light in centric position and nonexistent in excursions. CFPDs ideally should be metal or metal-ceramic, and connectors, which are high-stress areas, require bulk for strength. A cantilevered prosthesis may require more consideration and planning than a conventional fixed partial denture, but when kept within the patient's biological limitations and executed properly, can provide a restorative option with many advantages.

  18. Width design for gobs and isolated coal pillars based on overall burst-instability prevention in coal mines

    Institute of Scientific and Technical Information of China (English)

    Junfei Zhang; Fuxing Jiang; Sitao Zhu; Lei Zhang

    2016-01-01

    An investigation was conducted on the overall burst-instability of isolated coal pillars by means of the possibility index diagnosis method (PIDM). First, the abutment pressure calculation model of the gob in side direction was established to derive the abutment pressure distribution curve of the isolated coal pillar. Second, the overall burst-instability ratio of the isolated coal pillars was defined. Finally, the PIDM was utilized to judge the possibility of overall burst-instability and recoverability of isolated coal pillars. The results show that an overall burst-instability may occur due to a large gob width or a small pillar width. If the width of the isolated coal pillar is not large enough, the shallow coal seam will be damaged at first, and then the high abutment pressure will be transferred to the deep coal seam, which may cause an overall burst-instability accident. This approach can be adopted to design widths of gobs and isolated coal pillars and to evaluate whether an existing isolated coal pillar is recoverable in skip-mining mines.

  19. A 6-year Evaluation of 223 Tapered Dental Implants and associated prosthesis in 92 patients at a University Hospital.

    Science.gov (United States)

    Nagi, Sana Ehsen; Khan, Farhan Raza; Ali, Rabia

    2016-10-01

    The aim of the retrospective study was to assess the clinical and radiographic outcome of the dental implant surgery and prosthetics. It was conducted at the Aga Khan University Hospital, Karachi, and comprised of medical charts and radiographic records of patients visiting between 2010 and 2015. Variables such as implant dimensions, final prosthesis, method of retention, loading protocol and patient factors were analysed. A total of 223 implants (143(64.1%) in maxilla and 80(35.9%) in mandible) were placed in 92 subjects (50(54.3%) males and 42(45.7%) females). All implants were Zimmer tapered screw-vent. Length of 108(48.4%) implants was 11.5mm and diameter of 84(37.7%) implants was 4.7mm. Besides, 6(2.7%) implants failed to osseointegrate, whereas 1(0.4%) implant failed at 12 months of loading. Among the 216(96.9%) successful implants, 140(64.8%) served as bridge abutments, 72(33.3%) were single crown abutments and 4(1.9%) were overdenture abutments. Also, 37(17.1%) implants were immediately loaded. The six-year survival rate of implants was 96.9%.

  20. 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.

  1. Influence of a micro-thread at cervical position and a cylindrical intermediate zone on the mechanical behaviour of dental implants: A three-dimensional finite element analysis.

    Science.gov (United States)

    Garitaonaindia, Ugutz; Alcaraz, José Luis

    2015-09-01

    The purpose of this work is to analyse the influence on the biomechanical behaviour of dental implants of a micro-thread at their cervical part as well as of a cylindrical geometry at an intermediate zone. Stresses and strains in the elements involved, that is, bone, implant, screw and abutment, have to be considered in detail. Three different three-dimensional finite element models are generated to analyse the behaviour of the various components under the so-called tightening and operating conditions. For the modelling, material specifications for the cancellous bone and cortical bone, on one hand, and titanium properties for the implant, screw and abutment, on the other, are implemented. The tightening condition was fixed according to the stresses in the screw. The operating conditions were simulated by applying a force of 150 N, taking into account ISO 14801:2007 standard. The maximum stress under tightening conditions occurs always in the screw, while under operating conditions it is produced at the screw or the abutment, although considerable stress values are also present in the implant. In all the models, the maximum stress at the junction between the implant and the bone occurs within the cortical bone. Implants provided with micro-thread at the cervical position are advantageous over homogeneously threaded implants since lower stresses in both the implant and the adjacent bone are produced. A cylindrical intermediate portion on the implant surface does not present special advantage over the implants with continuous external thread under tightening and operating conditions.

  2. 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.

  3. The photoelastic study of the stress distribution on the supporting tissues of removable partial dentures with different designs%不同设计形式RPD对支持组织应力分布影响的光弹分析

    Institute of Scientific and Technical Information of China (English)

    胡月; 高勃; 常翔双

    2012-01-01

    目的:探讨分裂式设计与RPI设计制作的钴铬合金铸造支架RPD修复Kennedy Ⅰ类缺损对支持组织应力分布的影响,为优化义齿设计提供实验依据.方法:分别以分裂式设计和RPI设计两种设计形式的钴铬合金铸造支架RPD修复下颌牙双侧游离缺失,用三维光弹应力冻结切片技术测试义齿加载后对基牙和缺牙区牙槽骨的应力分布,并加以分析比较.结果:钴铬合金分裂式设计的铸造支架RPD承受压力沿基牙牙体长轴传导,基牙远中所受扭力较小.结论:对于Kennedy Ⅰ类牙列缺损,钴铬合金分裂式设计的铸造支架RPD使支持组织受力均匀、合理,减小了基牙受到的扭力,达到基牙保护的目的,是一种值得推广的设计.%Objective: To study the stress distribution on the supporting tissues of Kennedy Class I removable partial dentures with splitting and RPI designs of CoCr alloy, in order to provide basis for the application of casting frame flexible denture. Method: Mandible bilateral distal-extension edentulous were restored with RPDs in splitting and RPI designs of CoCr alloy.Three dimensional photoelastic frozen section method was used to test the stress distribution on abutment and e-dentulous alveolar.The stress of two forms dentures were compared with each other. Result: The metal framework removable partial denture with splitting exhibited lower torque on the distal of the abutment teeth,and the stress transferred to the abutments though the long axel of teeth. Conclusion: Among Kennedy class I removable partial dentures, the metal framework removable partial denture with splitting exhibits better stress pattern .reduce the torque to the abutment, protect the abutment, and should be considered as a preferable design.

  4. 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.

  5. 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

  6. 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

  7. Implant fracture under dynamic fatigue loading: influence of embedded angle and depth of implant.

    Science.gov (United States)

    Suzuki, Hiroaki; Hata, Yoshiaki; Watanabe, Fumihiko

    2016-09-01

    The purpose of this study was to investigate the relationship between implant fracture under cyclic-fatigue loading at different embedding angles, embedding depths, and loading forces. Twenty-four cylinder-type implants 3.3 mm in diameter and 10 mm in length were used. Test specimens were 30 mm(3) resin blocks with one surfaces inclined at angles of either 5°, 10°, 15° and 20° and embedded vertically with implants at depths of either 5 or 10 mm to the these surfaces. A straight abutment was connected to the implant and cut to 5 mm in length, and a hemispherical crown 5 mm in diameter and 7 mm in length was cast with a 12 % gold-silver-palladium alloy and cemented onto the abutment. Each specimen was mounted onto a fatigue loading device to apply repeated vertical loads of 294, 392, and 490 N to the coronal edge of the crown 60 times per min until reaching 100,000 cycles. For each respective specimen, we recorded the combined conditions of embedding and loading forces and the number of loading cycles until fracture, and then observed the fracture sites microscopically. The number of loading cycles until implant fracture tended to decrease in proportion to increased loading forces and embedded angles, and decreased embedded depths. Implant fracture was observed at angles of inclination over 10°. For specimens with an implant embedded at a depth of 5 mm, almost all fractures occurred at the center of the implant body; however, for those embedded at a depth of 10 mm, fractures occurred at the interface between the implant body and the abutment. These results demonstrate that implant fracture is associated with the loading axis, the amount of loading, and the embedded depth of the implant.

  8. Angled cool-tip electrode for radiofrequency ablation of small superficial subcapsular tumors in the liver: A feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Il; Shin, Min Woo; Shin, Won Seon [Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); and others

    2016-09-15

    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. 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. 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. 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.

  9. Response Classification Images in Vernier Acuity

    Science.gov (United States)

    Ahumada, Albert J., Jr.; Beard, B. L.; Ellis, Stephen R. (Technical Monitor)

    1997-01-01

    Orientation selective and local sign mechanisms have been proposed as the basis for vernier acuity judgments. Linear image features contributing to discrimination can be determined for a two choice task by adding external noise to the images and then averaging the noises separately for the four types of stimulus/response trials. This method is applied to a vernier acuity task with different spatial separations to compare the predictions of the two theories. Three well-practiced observers were presented around 5000 trials of a vernier stimulus consisting of two dark horizontal lines (5 min by 0.3 min) within additive low-contrast white noise. Two spatial separations were tested, abutting and a 10 min horizontal separation. The task was to determine whether the target lines were aligned or vertically offset. The noises were averaged separately for the four stimulus/response trial types (e.g., stimulus = offset, response = aligned). The sum of the two 'not aligned' images was then subtracted from the sum of the 'aligned' images to obtain an overall image. Spatially smoothed images were quantized according to expected variability in the smoothed images to allow estimation of the statistical significance of image features. The response images from the 10 min separation condition are consistent with the local sign theory, having the appearance of two linear operators measuring vertical position with opposite sign. The images from the abutting stimulus have the same appearance with the two operators closer together. The image predicted by an oriented filter model is similar, but has its greatest weight in the abutting region, while the response images fall to nonsignificance there. The response correlation image method, previously demonstrated for letter discrimination, clarifies the features used in vernier acuity.

  10. 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.

  11. Static density functional study of graphene-hexagonal bilayer ice interaction.

    Science.gov (United States)

    Anick, David J

    2014-09-04

    Periodic static ab initio studies are conducted of hexagonal bilayer ice (HBL) and basal layers of ice-1h adsorbed on graphene using the model BLYP-D in CRYSTAL09. Eight high-symmetry periodic forms of HBL are optimized, of which four have lower energy; their electronic binding energy to graphene is ∼1.6 kcal/mol per abutting H2O. Optimized geometries have the property of maximizing the occurrence of a certain O-H-C alignment motif. One lattice is selected for more detailed study. Its 2-D shear translation potential energy surface is found to have barrier heights in two zigzag directions of ∼140 cal/mol per abutting H2O. A second hexagonal bilayer can be added and the electronic binding energy drops from ∼1.7 to ∼1.0 kcal/mol per abutting H2O. For ice-1h monolayer adsorbed on graphene, a proton-ordered form in which half of the O's nearest the graphene carry a proton pointing toward graphene is preferred over proton-ordered forms in which either all or none of those O's have H's pointing toward graphene. Cohesive energy for two-layer ice-1h on graphene is 0.66 kcal/mol of H2O higher than for HBL, supporting experimental evidence that the graphene+HBL isomer is more stable. However, the HBL and two-HBL structures are unstable or at best metastable with respect to four layers of ice-1h.

  12. Evaluating the Illinois Stream Valley segment model as an effective management tool.

    Science.gov (United States)

    Warrner, Stephen S; Fischer, Robert U; Holtrop, Ann M; Hinz, Leon C; Novak, James M

    2010-11-01

    Stream habitat assessments are conducted to evaluate biological potential, determine anthropogenic impacts, and guide restoration projects. Utilizing these procedures, managers must first select a representative stream reach, which is typically selected based on several criteria. To develop a consistent and unbiased procedure for choosing sampling locations, the Illinois Department of Natural Resources and the Illinois Natural History Survey have proposed a technique by which watersheds are divided into homogeneous stream segments called valley segments. Valley segments are determined by GIS parameters including surficial geology, predicted flow, slope, and drainage area. To date, no research has been conducted to determine if the stream habitat within a valley segment is homogeneous and if different valley segments have varying habitat variables. Two abutting valley segments were randomly selected within 13 streams in the Embarras River watershed, located in east-central Illinois. One hundred meter reaches were randomly selected within each valley segment, and a transect method was used to quantify habitat characteristics of the stream channel. Habitat variables for each stream were combined through a principal components analysis (PCA) to measure environmental variation between abutting valley segments. A multivariate analysis of variance (MANOVA) was performed on PCA axes 1-3. The majority of abutting valley segments were significantly different from each other indicating that habitat variability within each valley segment was less than variability between valley segments (5.37 ≤ F ≤ 245.13; P ≤ 0.002). This comparison supports the use of the valley segment model as an effective management tool for identifying representative sampling locations and extrapolating reach-specific information.

  13. Effect of splinting in accuracy of two implant impression techniques.

    Science.gov (United States)

    de Avila, Erica Dorigatti; de Matos Moraes, Fernanda; Castanharo, Sabrina Maria; Del'Acqua, Marcelo Antonialli; de Assis Mollo, Francisco

    2014-12-01

    Because there is no consensus in the literature about the need for a splint between copings, the aim of this study was to evaluate, in vitro, the accuracy of 2 impression techniques for implant-supported prostheses. A master cast was fabricated with four parallel implant abutment analogs and a passive framework. Two groups with 5 casts each were formed: Group 1 (squared impression copings with no splint: S) and Group 2 (splinted squared impression copings, using metal drill burs and Pattern resin: SS). The impression material used was polyvinyl siloxane with open trays for standard preparation of the casts. For each cast, the framework was positioned, and a titanium screw was tightened with 10 N·cm torque in analog A, after which measurements of the abutment-framework interface gaps were performed at analogs C and D. This process was repeated for analog D. These measurements were analyzed using software. A one-way analysis of variance (ANOVA) with a confidence interval of 95% was used to analyze the data. Significant differences were detected between S and SS in relation to the master cast (P ≤ 0.05). The median values of the abutment-framework interface gaps were as follows: master cast: 39.64 μm; squared impression copings with no splint: 205.86 μm; splinted squared impression copings: 99.19 μm. Under the limitations of this study, the technique presented for Group 2 produces better results compared with the technique used for Group 1.

  14. Measurement and analysis of alkaline phosphatase and aspartate aminotransferase activity levels in gingival cervical fluid after treatment of telescope retained fixed bridge%套筒冠式固定桥基牙龈沟液中碱性磷酸酶和天冬氨酸转氨酶的检测分析

    Institute of Scientific and Technical Information of China (English)

    武峰; 赵彬; 姚蔚

    2011-01-01

    Objective To explore the role of telescopic crown retainers fixed bridge in periodontal maintenance. Methods A total of 64 abutment teeth were selected from 16 patients and divided into experimental and control groups (n=32 each). The gingival index and sulcus bleeding index of abutments in the both two groups were detected at 6 and 12 months before and after repair. The alkaline phosphatase (ALP) and aspartate aminotransferase (AST) activity levels in gingival cervical fluid were measured using automatic biochemistry analyzer. Results There were significant differences in Gl and SBI between the experimental and control groups, as well as in ALP and AST activity levels (P<0.05). Conclusion Telescope retained fixed bridge might help protect the periodontal tissue of abutment teeth.%目的 探索套筒冠固位式固定桥对于牙周维护的作用.方法 选择16例患者共64颗基牙,分为实验组和对照组,每组32颗基牙.在修复前以及修复后6 、12个月,对基牙进行牙龈指数(GI)和龈沟出血指数(SBI)的检测,利用全自动生化分析仪检测基牙龈沟液中碱性磷酸酶(ALP)和天冬氨酸转氨酶(AST)活性水平.结果 在修复前与修复后12 个月实验组与对照组之间GI、SBI比较差异有统计学意义(P<0.05),ALP、AST活性水平差异也有统计学意义(P<0.05).结论 套筒冠式固定桥有利于基牙牙周组织的保护.

  15. An overview of U.S. predoctoral dental implant programs and their directors.

    Science.gov (United States)

    Barwacz, Christopher A; Avila-Ortiz, Gustavo; Allareddy, Veerasathpurush; Tamegnon, Monelle; Hoogeveen, Kaitlin

    2015-03-01

    The aim of this study was to provide an overview of current predoctoral implant programs in the United States, including curricular characteristics and clinical practices regarding implant therapy education and program directors' characteristics. An electronic survey was sent to predoctoral implant program directors of all 64 accredited U.S. dental schools; 52 of the 60 eligible programs responded, for a response rate of 87%. The responding program directors were primarily affiliated with either prosthodontics departments (44%) or restorative dentistry departments (40%). Structurally, 80.8% of the responding schools integrate their implant programs into the third year of the curriculum. Clinical implant therapy exercises reported were simulation exercises without direct patient care (90.4% of responding schools) and direct patient care under supervision (94.2%). The most frequently taught restorative modalities are posterior single-tooth implant crown (96.2%), mandibular implant-retained overdenture (88.5%), and anterior implant-supported single crown (61.5%). A majority (74.5%) of responding programs utilize analog surgical guide planning, while 25.5% reported use of digital guided surgery planning software. All schools in the Northwest and 66.7% in the South Central regions utilize custom abutments as the primary abutment design, while a majority of schools in the North Central (62.5%), Northeast (53.8%), Southwest (66.7%), and Southeast (80%) regions use stock abutments (p=0.02). Regional differences were significant with regard to fixation modality, with all the Northwest programs using screw retention and 90% of Southeast and 87.5% of North Central programs using cement retention (p=0.002). This study demonstrated that while institutions share program director and curricular similarities, clinical practices and modalities vary significantly by region.

  16. 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

  17. Angled Cool-Tip Electrode for Radiofrequency Ablation of Small Superficial Subcapsular Tumors in the Liver: A Feasibility Study

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Il [Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul 03722 (Korea, Republic of); Kim, Il Jung [Department of Radiology, Bucheon St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, Bucheon 14647 (Korea, Republic of); Lee, Shin Jae [Department of Radiology, CHA Bundang Medical Center, CHA University, Seongnam 13496 (Korea, Republic of); Shin, Min Woo; Shin, Won Sun; Chung, Yong Eun; Kim, Gyoung Min; Kim, Man Deuk; Won, Jong Yun; Lee, Do Yun [Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul 03722 (Korea, Republic of); Choi, Jin Sub [Department of Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul 03722 (Korea, Republic of); Han, Kwang-Hyub [Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul 03722 (Korea, Republic of)

    2016-11-01

    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. 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. 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. 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.

  18. A prospective study of Astra single tooth implants.

    Science.gov (United States)

    Palmer, R M; Smith, B J; Palmer, P J; Floyd, P D

    1997-06-01

    A new design of single tooth implant (AstraTech, Molndal Sweden) featuring a microthreaded conical neck and TiO blast surface was evaluated clinically and radiographically after 2 years in function. Fifteen patients (age range 16 to 48) with missing maxillary anterior teeth (6 central incisors, 8 laterals, 1 bicuspid) had 4, 13 mm and 11, 15 mm implants placed under local anaesthesia and left for a period of 6 months before exposure and abutment connection/crown fabrication. All patients were seen at 4 to 6 monthly intervals for hygienist maintenance. Radiographs using Rinn holders and a long cone technique were taken at the crown insertion and after 1 year (14 subjects) and 2 years (12 subjects). All implants were successfully integrated at stage 2, and no implants have been lost. The internal conical seal design of the abutment/implant interface facilitated connection and there were no cases of abutment screw loosening. No soft tissue problems were observed, and the gingival morphology/health was well maintained. One crown was recemented after 18 months in function, and 1 crown was replaced because of a fracture to the porcelain incisal edge. At crown insertion, the mean bone level was 0.46 to 0.48 mm apical to the top of the implant and there were no statistically significant changes in the bone level over the 2 years of the study. In conclusion, the single tooth Astra implants were highly successful and bone changes within the first 2 years of function were comparable with other systems reporting high long-term success rates.

  19. Prosthetic rehabilitation using adhesive bridge and fixed-fixed bridge on the maxilla and telescopic crown overdenture on mandible

    Directory of Open Access Journals (Sweden)

    Indah Sulistiawaty

    2016-12-01

    Full Text Available Prosthetic rehabilitation is the rehabilitation process of masticatory and esthetics function for patients missing teeth and alveolar bone by means of manufacture and installation of dentures. The prosthetic rehabilitation commonly used include denture adhesive bridge, fixed-fixed bridge, as well as telescopic overdenture. Adhesive bridge is bridge denture consisting of single pontic and two retainer wings attached to the abutment using cement or resin. Fixed-fixed bridge is a bridge denture with rigid connectors on both ends of the pontics, whereas the telescopic crown Overdenture is a removable denture that uses linked precision on the original tooth in the form of primary coping on abutment and secondary coping on the denture. To expose the procedures of prosthetic rehabilitation using adhesive bridge and fixed-fixed bridge on the maxilla and telescopic crown Overdenture on mandible. Male patients aged 32 years came with complaints of difficulty to chew food because he had lost some teeth behind. In the maxilla, teeth are lost in the region of 15 and 16 performed by making the fixed-fixed bridge with abutment teeth 14 and 17. Loss of teeth in the region of 26, performed the manufacture of adhesive bridge with a box preparation on the occlusal 25 and 27. In the mandible, tooth loss in the region of 36,37,46, and 47 performed manufacture of telescopic crown Overdenture with primer coping on the teeth 35.38, 45, and 48 and the secondary coping on a metal frame. Prosthetic rehabilitation especially in the case of loss of back teeth is very important because with the denture patients can chew properly and maintain the stomatognathic system.

  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. Dielectric relaxation in double potassium yttrium orthophosphate K 3Y(PO 4) 2 doped by praseodymium and dysprosium ions

    Science.gov (United States)

    Szulia, S.; Kosmowska, M.; Kołodziej, H. A.; Mizer, D.; Czupińska, G.

    2011-12-01

    We report the paper presents the results of electric properties of double potassium yttrium orthophosphates doped by lanthanide ions K 3Y( 1-x)Ln x(PO 4) 2 ( x = 0.01, 0.05, Ln = Pr 3+, Dy 3+). Electric permittivity and dielectric loss measurements have been performed on polycrystalline samples in the temperature range -50-120 °C and frequency range 1 kHz-1 MHz by means of HP 4282A impedance meter. The frequency and temperature dependence of electric properties were analyzed by theoretical models of dielectric relaxation in order to obtain information abut molecular dynamic of our solids in external electric field.

  2. 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.

  3. Reference: 367 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available ng et al. 2006 May. Plant Cell 18(5):1226-38. Mutations in genes encoding components of the heterotrimeric G-protein complex were... previously shown to confer altered sensitivity to increased levels of D-glucose. This ...idopsis thaliana. THYLAKOID FORMATION1 (THF1) is here demonstrated in vivo as a Galpha interaction partner that functions downstre...brane and the stroma. Contact between root plastidic THF1 and GPA1 at the plasma membrane occurs at sites where... the plastid membrane abuts the plasma membrane, as demonstrated by Förster resonance energy transfer (FR

  4. 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.

  5. 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.

  6. Serial extraction protocol for partial arches in implant dentistry: principles and clinical methodology.

    Science.gov (United States)

    Cavallaro, John S; Greenstein, Gary; Greenstein, Ben

    2010-01-01

    Serial extraction protocol (SEP) is a clinical technique that facilitates using natural tooth abutments to support a fixed interim resin prosthesis, while inserting a sufficient number of implants to retain a definitive fixed prosthesis. A Class 1 protocol allows all necessary implants to be placed during one surgical appointment, while a Class 2 protocol requires two or more rounds of implant installation to achieve sufficient support for a definitive fixed prosthesis. The SEP methodology can be used to restore full and partially edentulous dentitions. This article addresses rehabilitation of partial arches using an SEP protocol.

  7. 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.

  8. National Program for Inspection of Non-Federal Dams. Winsor Dam (MA 00588), Quabbin Spillway (MA 00589), Goodnough Dike (MA 00590), Connecticut River Basin, Ware, Massachusetts. Phase I Inspection Report.

    Science.gov (United States)

    1978-09-01

    Non-Federal Dams; use cover date for date of report. I9. KEYa WORDS (Coon#~ o rSeeres side at femoser and *osROifr IV mesa imb".) DAMS, INSPECTION...lII m a j6. Repoint the lower courses of the Intake Structure stone masonry exterior walls. 17. FMI animal burrow holes on upper berm of Winsor Dam...grass slope Animal Burrows in Embank- Several noted on upper berm near right * ment abutment Vegetation on Embankment Grass in good condition, mowed

  9. Análise biomecânica de próteses implantossuportadas parafusadas e cimentadas por meio do método dos elementos finitos

    OpenAIRE

    Guilherme Costa Carvalho Silva

    2013-01-01

    As próteses implantossuportadas podem ser retidas por parafusos ou por meio de cimento. Um fator relevante que pode influenciar a opção por um dos dois tipos de retenção é o comportamento biomecânico supostamente distinto entre eles. Por meio do método dos elementos finitos 3D, foram comparadas as tensões e deslocamentos nos parafusos, implantes, abutments e no tecido ósseo periimplantar de próteses implantossuportadas parafusadas e cimentadas. Foram construídos dois modelos distintos, consis...

  10. Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis

    OpenAIRE

    Esteban Pérez-Pevida; Aritza Brizuela-Velasco; David Chávarri-Prado; Antonio Jiménez-Garrudo; Fernando Sánchez-Lasheras; Eneko Solaberrieta-Méndez; Markel Diéguez-Pereira; Fernández-González, Felipe J.; Borja Dehesa-Ibarra; Francesca Monticelli

    2016-01-01

    The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D) finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP), conv...

  11. Giant Cell Tumor of Bone: Documented Progression over 4 Years from Its Origin at the Metaphysis to the Articular Surface

    Directory of Open Access Journals (Sweden)

    Colin Burke

    2016-01-01

    Full Text Available The exact location of origin for giant cell tumors of bone (GCTB remains controversial, as lesions are not routinely imaged early but rather late when the tumor is large and clinically symptomatic. At the time of diagnosis, GCTB are classically described as lucent, eccentric lesions with nonsclerotic margins, located within the epiphysis to a greater extent than the metaphysis. Here we present a case of a biopsy proven GCTB initially incidentally seen on MRI as a small strictly metaphyseal lesion, which over the course of several years expanded across a closed physis to involve the epiphysis and abut the articular surface/subchondral bone plate.

  12. 57年来本溪地区干湿程度演变分析(英文)

    Institute of Scientific and Technical Information of China (English)

    吉奇; 祝奎; 詹克荣; 吴英杰

    2010-01-01

    [Objective] The research aimed to analyze the evolution situation of dry and wet degree in Benxi area in recent 57 years.[Method] By using the annual,quarterly and monthly temperature and precipitation data in Benxi area during 1953-2009,the interdecadal variations of temperature,precipitation,dry and wet index were analyzed.[Result] The annual average temperature in Benxi area displayed the obvious increase trend,and the linear trend rate was 0.29 ℃/10 a.But the precipitation showed the obvious decrease tr...

  13. 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.

  14. Barcoding Eophila crodabepis sp. nov. (Annelida, Oligochaeta, Lumbricidae), a Large Stripy Earthworm from Alpine Foothills of Northeastern Italy Similar to Eophila tellinii (Rosa, 1888)

    Science.gov (United States)

    Paoletti, Maurizio G.; Blakemore, Robert J.; Csuzdi, Csaba; Dorigo, Luca; Dreon, Angelo Leandro; Gavinelli, Federico; Lazzarini, Francesca; Manno, Nicola; Moretto, Enzo; Porco, David; Ruzzier, Enrico; Toniello, Vladimiro; Squartini, Andrea; Concheri, Giuseppe; Zanardo, Marina; Alba-Tercedor, Javier

    2016-01-01

    A new Italian earthworm morphologically close to the similarly large and anecic Eophila tellinii (Rosa, 1888) is described. Distribution of Eophila crodabepis sp. nov. extends over 750 km2 from East to West on the Asiago Plateau and Vittorio Veneto Hills, from North to South on mounts Belluno Prealps (Praderadego and Cesen), Asiago, Grappa and onto the Montello foothills. This range abuts that of Eophila tellinii in northern Friuli Venezia Giulia region. Known localities of both E. tellinii and E.crodabepis sp. nov. are mapped. mtDNA barcoding definitively separates the new western species from classical Eophila tellinii (Rosa, 1888). PMID:27019284

  15. 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.

  16. A/E/C CAD Standard, Release 4.0

    Science.gov (United States)

    2009-07-01

    structures) 0 0.35 122 23 X S-HYDR- COFF Cofferdam 0 0.35 42 182 X X X X S-HYDR-COND Diversionary/bypass conduits and culverts 0 0.35 122 23 X X X X S-HYDR...Abutments 0 0.35 83 42 X X X S-WALL-CELL Cell 0 0.35 53 44 X S-WALL- COFF Cutoff wall 0 0.35 30 86 X X X X X S-WALL-CURT Curtain/breast wall 0 0.35

  17. 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.

  18. 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.

  19. 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.

  20. Modified Technique for Making Auto-polymerized Polymethylmethacrylate Resin Custom Tray

    Science.gov (United States)

    Reddy, Ramesh; Rajendran, Suresh; Balasubramaniam, Muthu Kumar

    2016-01-01

    Custom made tray for dental impression is designed to provide a uniform space for the impression material and thereby improve the accuracy of the resultant working cast. Auto-polymerized acrylic resins have been the most commonly used material for the fabrication of these trays. The custom tray produces more accurate and reliable results for inter-abutment distance at the occlusal and gingival level than stock trays. This article describes a modified technique for fabrication of auto-polymerized Polymethylmethacrylate (PMMA) resin trays. PMID:28050525

  1. Dimensional accuracy of 2-stage putty-wash impressions: influence of impression trays and viscosity.

    Science.gov (United States)

    Balkenhol, Markus; Ferger, Paul; Wöstmann, Bernd

    2007-01-01

    The aim of this in vitro study was to evaluate the influence of the impression tray and viscosity of the wash material on the dimensional accuracy of impressions taken using a 2-stage putty-wash technique. Identically shaped metal stock trays (MeTs) and disposable plastic stock trays (DiTs) were used for taking impressions (n = 10) of a mandibular cast (4 abutments) with 2 different impression materials. Dies were poured and the relative diameter deviation was calculated after measurement. Zero viscosity of the materials was determined. Dimensional accuracy was significantly affected when DiTs were used. Lower-viscosity wash materials led to more precise impressions.

  2. 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.

  3. Biological adaptation to misfits of immediately loaded fixed prostheses following computer-guided surgery.

    Science.gov (United States)

    Puterman, Israel; Kan, Joseph Y K; Rungcharassaeng, Kitichai; Oyama, Kotaro; Morimoto, Taichiro; Lozada, Jaime

    2012-04-01

    In this clinical report, following computer-guided (3D Procera Software Planning Program, Nobel Biocare, Yorba Linda, CA) placement and immediate provisionalization of 12 dental implants (NobelSpeedy™ Replace, Nobel Biocare), misfits of the prefabricated screw-retained interim prostheses were noted at several implant-abutment junctions. Nevertheless, adaptation of the misfits was observed 10 days later, after the loosened screws were tightened. While a high mean marginal bone loss of 2.1 mm (range: 1.4 to 3.5 mm) was noted, all implants remained osseointegrated at 3-year follow-up.

  4. 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. 

  5. Reliability of the impression replica technique.

    Science.gov (United States)

    Falk, Anders; Vult von Steyern, Per; Fransson, Håkan; Thorén, Margareta Molin

    2015-01-01

    The aim of this study was to evaluate the reliability of the impression replica technique with a four-unit zirconia fixed dental prosthesis (FDP). Marginal and internal fit were measured by repeatedly placing the FDP on an epoxy cast using light-body silicone material corresponding to cement. All measured marginal and internal fit points showed varying values. The greatest variations were seen at the most distal margin (33 μm) and at the distal abutment of the FDP (77 μm). The results showed that the technique gives moderate variations and is a useful method to evaluate marginal and internal fit.

  6. National Dam Safety Program. Beaver Dam Lake (Inventory Number N.Y. 619) , Hudson River Basin, Orange County, New York. Phase I Inspection Report

    Science.gov (United States)

    1980-09-11

    Beyond Too AT AQF i~ ToS, A 5~eCPAC QMDT, ,5Arurawab AReA AUur 40o c’. e. Abutments - Embankinent Contact At1L lMi UT - M L IP? Coj-j4 WALL 1 1 Crosio n...34f ",’ j CC 9) S tr11, A M Y~) ’L-~A( al. Coic rete Su pf ac es _’/T P21CI ,k i, ,jb 7/Al A/) (Iap(𔃺,07 pT,,/ A /AI1fPAC-iI6S ANT’ 100 4Z 7PJA

  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. Nature of the crust under Afar: new igneous, not thinned continental

    Science.gov (United States)

    Mohr, Paul

    1989-10-01

    Thinned continental crust is considered absent from beneath Afar, except for isolated remnants such as comprise the Danakil Block. The Ethiopian Plateau sialic crust thins abruptly across the plateau-Afar margin to abut new igneous crust under Afar, generated during the early development of the Red Sea basin. Analyses of stretching and sea-floor spreading amounts elsewhere in the Red Sea and Gulf of Aden basins are employed to support this concept. The dual layering of the Afar crust, and the similarity of P-wave velocities in these layers to velocities in sialic crust, lead to the proposal that new continental crust can be generated at magmatic rift zones.

  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. Diseño del puente Abbas Ibn Firnás sobre el río Guadalquivir en Córdoba

    OpenAIRE

    2013-01-01

    The work for the New Access to the Cordoba Airport includes the construction of the Abbas Ibn Firnas Bridge to cross the Guadalquivir River. This cable-stayed bridge has two spans of 132.50 m each, and three approach spans on the right bank that add 100 meters to its length. The most important and singular aspect of the structure is the design of the mixed concrete and steel arches that open into two hexagonal tubes braced from the central pier to the abutments and the arrangement of the stru...

  11. A bioactive dental luting cement--its retentive properties and 3-year clinical findings.

    Science.gov (United States)

    Jefferies, Steven R; Pameijer, Cornelis H; Appleby, David C; Boston, Daniel; Lööf, Jesper

    2013-02-01

    A clinical validation study was conducted to determine the performance of a new bioactive dental cement (Ceramir C&B, Doxa Dental AB) for permanent cementation. The cement is a new formulation class, which is a hybrid material comprised of calcium aluminate and glass-ionomer components. A total of 38 crowns and bridges were cemented in 17 patients; 31 of the abutment teeth were vital and seven were non-vital. Six restorations were bridges with a total of 14 abutment teeth (12 vital/ two non-vital). One fixed splint comprising two abutment teeth was also included. Preparation parameters were recorded, as well as cement characteristics such as working time, setting time, seating characteristics, and ease of cement removal. Baseline data were recorded for the handling of the cement, gingival inflammation, and pre-cementation sensitivity. Post-cementation parameters included post-cementation sensitivity, gingival tissue reaction, marginal integrity, and discoloration. All patients were seen for recall examinations at 30 days and 6 months. Fifteen of 17 subjects and 13 of 17 patients were also available for subsequent comprehensive 1- and 2-year recall examination, and 13 patients were available for a 3-year recall examination. Restorations available for the 3-year recall examination included 14 single-unit full-coverage crown restorations, four three-unit bridges comprising eight abutments, and one two-unit splint. Three-year recall data yielded no loss of retention, no secondary caries, no marginal discolorations, and no subjective sensitivity. All restorations rated excellent for marginal integrity. Average visual analogue scale (VAS) score for tooth sensitivity decreased from 7.63 mm at baseline to 0.44 mm at 6-month recall, 0.20 mm at 1-year recall, and 0.00 mm at 2- and 3-year recall. Average gingival index (GI) score for gingival inflammation decreased from 0.56 at baseline to 0.11 at 6-month recall, 0.16 at 1-year recall, 0.21 at 2-year recall, and 0.07 at 3

  12. 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.

  13. Use of transparent vinyl polysiloxane in a minimally invasive approach for creating composite resin undercuts for partial removable dental prostheses.

    Science.gov (United States)

    Varjão, Fabiana Mansur

    2012-01-01

    A technique using a transparent vinyl polysiloxane material developed for use with light-polymerized composite resin and that does not require a lubricant is presented for creating composite resin undercuts for partial removable dental prosthesis clasps. With a surveyor, the undercut is waxed on the diagnostic cast according to the intended path of insertion. The transparent vinyl polysiloxane is used to fabricate a template for the undercut. The template is used intraorally to create the undercut in composite resin on the abutment tooth.

  14. 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.

  15. Strength of CAD/CAM-generated esthetic ceramic molar implant crowns

    OpenAIRE

    D. Wolf; 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...

  16. Repair of a large furcation perforation: a four-year follow-up.

    Science.gov (United States)

    Ibarrola, Jose L; Biggs, Stephen G; Beeson, Thomas J

    2008-05-01

    This case report describes the management of a large furcation perforation in a maxillary first molar. Although the majority of the pulpal floor was destroyed and the mesiobuccal root was damaged, an attempt was made to repair the defect and restore the tooth. An absorbable gelatin sponge matrix was placed, and the defect was repaired with gray ProRoot mineral trioxide aggregate. Subsequently the endodontic treatment was completed; the tooth was restored and was later used as a fixed partial denture abutment. A 55-month recall showed no evidence of periodontal breakdown, no symptoms, and complete healing of all periradicular lesions.

  17. Morse taper implants at different bone levels: a finite element analysis of stress distribution

    OpenAIRE

    Toniollo, Marcelo Bighetti; Macedo, Ana Paula; Palhares, Daniel; Calefi, Paulo Linares; Sorgini, Danilo Balero; Mattos, Maria da Gloria Chiarello de

    2012-01-01

    AIM: To explore the biomechanical effects of the different implantation bone levels of Morse taper implants, employing a finite element analysis (FEA). METHODS: Dental implants (TitamaxCM) with 4x13 mm and 4x11 mm, and their respective abutments with 3.5 mm height, simulating a screwed premolar metal-ceramic crown, had their design performed using the software AnsysWorkbench 10.0. They were positioned in bone blocks, covered by 2.5 mm thickness of mucosa. The cortical bone was designed with 1...

  18. 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.

  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. Avaliação clínica do grau de paralelismo obtido no preparo de planos de guia de dentes suportes de prótese parcial remóvivel, utilizando paralelizador intrabucal

    OpenAIRE

    Borges, Alexandre Luiz Souto [UNESP

    2005-01-01

    The aim of this study was to evaluate the efficiency of the ParalAB intraoral device as a transference method of guide planes and to verify the influence of the arch and position of the abutment teeth on preparations produced by students and dentists. 321 guide planes were prepared by different collaborators using the ParalAB device on 92 casting models deriving from patients of partial removable denture dental clinic. The preparations were divided in two groups: group 1: dentists (n=44) and ...

  1. Evaluation of mine scale longwall top Coal caving parameters using continuum analysis

    Institute of Scientific and Technical Information of China (English)

    Manoj Khanal; Deepak Adhikary; Rao Balusu

    2011-01-01

    A mine-scale analysis of Longwall Top Coal Caving (LTCC) is performed using a continuum mechanics finite element solver called COSFLOW.The uniqueness of COSFLOW is that it incorporates Cosserat continuum theory in its formulation for describing the load deformation of bedded rocks.It is shown that such a continuum based code is valuable for assessing the feasibility of introducing LTCC in any mine.Various LTCC parameters,for example chock convergences,top coal failure behavior,strata caving mechanism,abutment stresses and vertical stresses,were evaluated for a mine using COSFLOW.

  2. Pseudoprominent aorta: Radiographic findings and CT correlation

    Energy Technology Data Exchange (ETDEWEB)

    Brown, K.T.; Shepard, J.A.O.; Stewart, W.J.

    1985-05-01

    The presence of a persistent left-sided superior vena cava (LSVC) in the absence of a right-sided superior vena cava (RSVC) may be suspected on a posteroanterior (PA) chest radiograph because of a prominent-appearing ascending aorta, which results from the absence of the RSVC. In the absence of an RSVC, the right upper lobe abuts and outlines the course of the ascending aorta, allowing better demonstration of its profile. This report describes a patient with this finding on a PA chest radiograph. Computed tomographic correlation is presented.

  3. 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.

  4. 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.

  5. Nitride based quantum well light-emitting devices having improved current injection efficiency

    Science.gov (United States)

    Tansu, Nelson; Zhao, Hongping; Liu, Guangyu; Arif, Ronald

    2014-12-09

    A III-nitride based device provides improved current injection efficiency by reducing thermionic carrier escape at high current density. The device includes a quantum well active layer and a pair of multi-layer barrier layers arranged symmetrically about the active layer. Each multi-layer barrier layer includes an inner layer abutting the active layer; and an outer layer abutting the inner layer. The inner barrier layer has a bandgap greater than that of the outer barrier layer. Both the inner and the outer barrier layer have bandgaps greater than that of the active layer. InGaN may be employed in the active layer, AlInN, AlInGaN or AlGaN may be employed in the inner barrier layer, and GaN may be employed in the outer barrier layer. Preferably, the inner layer is thin relative to the other layers. In one embodiment the inner barrier and active layers are 15 .ANG. and 24 .ANG. thick, respectively.

  6. A practice-based clinical evaluation of the survival and success of metal-ceramic and zirconia molar crowns: 5-year results.

    Science.gov (United States)

    Rinke, S; Kramer, K; Bürgers, R; Roediger, M

    2016-02-01

    This practice-based study evaluates the survival and success of conventionally luted metal-ceramic and zirconia molar crowns fabricated by using a prolonged cooling period for the veneering porcelain. Fifty-three patients were treated from 07/2008 to 07/2009 with either metal-ceramic crowns (MCC) or zirconia crowns (ZC). Forty-five patients (26 female) with 91 restorations (obser-vational period: 64.0 ± 4.8 months) participated in a clinical follow-up examination and were included in the study. Estimated cumulative survival (ECSv), success (ECSc) and veneering ceramic success (ECVCSc) were calculated (Kaplan-Meier) and analysed by the crown fabrication technique and the position of the restoration (Cox regression model) (P crowns placed on tooth-neighboured abutments (n = 47), (5-year VCF-rate: 4.3%). In the present study, zirconia molar crowns demonstrated a 5-year ECSv, ECSc and ECVCSc comparable to MCCs. Irrespective of the fabrication technique, crowns on terminal abutments bear a significantly increased risk for VCFs. Clinical investigations with an increased number of restorations are needed.

  7. Fit of zirconia all-ceramic crowns with different cervical margin designs, before and after porcelain firing and glazing.

    Science.gov (United States)

    Miura, Shoko; Inagaki, Ryoichi; Kasahara, Shin; Yoda, Masanobu

    2014-01-01

    The purpose of this study is to investigate the fit of zirconia cores and all-ceramic crowns prepared with different cervical margin designs. The radius of curvature between the axial wall and the occlusal surface was set to 1 mm in an abutment using the cervical shoulder marginal design (S) and to 0.2 and 0.5 mm in abutments with round shoulders (0.2RS and 0.5RS, respectively). The internal gaps of the cores were 45-138 μm (S), 41-141 μm (0.2RS), and 43-133 μm (0.5RS). The internal gaps of the all-ceramic crowns were 40-115 μm (S), 45-113 μm (0.2RS), and 42-126 μm (0.5RS). There were no significant differences in one-way ANOVA for any region in any marginal design before and after firing the porcelain. The marginal gaps between the all-ceramic crowns and dies were 27 ± 25 (S), 30 ± 29 (0.2RS), and 24 ± 27 μm (0.5RS), again with no significant differences in one-way ANOVA.

  8. 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.)

  9. 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.

  10. 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.

  11. 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.

  12. [Novel possibilities for the rehabilitation of patients presenting with congenital external and middle ear malformations].

    Science.gov (United States)

    Mileshina, N A; Osipenkov, S S; Bakhshinian, V V; Tavartkiladze, G A

    2014-01-01

    The objective of the present study was to estimate the advantages of cochlear Baha BIA 400 abutments in the intraoperative and early postoperative periods. A total of 10 implantations of the systems with the use of hydroxyapatite bone cement were performed in 9 patients of different age. Stability of the implants and intensity of skin reactions were evaluated. The data obtained indicate that the use of cochlear Baha BIA 400 abutments significantly simplifies and shortens the surgical stage of rehabilitation producing a good cosmetic result. The use of the Osstell instrument made it possible to estimate stability of the implants intraoperatively and evaluate the effectiveness of osteointegration during the follow-up period. Analysis of the results of the study provided a basis on which to improve the quality and shorten duration of the rehabilitative treatment of the patients presenting with congenital external and middle ear malformations. Moreover, the data obtained can be used to develop practical recommendations for the further work in this area.

  13. Elastomeric shutter mechanism

    Science.gov (United States)

    Curtis, Clifford M.

    1995-05-01

    An elastomeric shutter mechanism for opening and closing a passageway in the wall of a vessel, such as a submarine hull is presented. A single, unitary, retractable shutter member made of an elastomeric material is partially attached to the wall around a portion of a passageway. The single, unitary, retractable shutter member is moveable from a closed position when the unattached portion of the shutter member is abutting the wall around the passageway to an open position when the unattached portion of the shutter member is retracted away from the wall around the passageway. Cables are attached to the inside surface of the shutter member for retracting the shutter member and opening the passageway. Mechanical stops are positioned inside of the vessel for abutting the shutter member when retracted to the open position by the cables. On an underwater vessel such as a submarine, the shutter member is sealed in the closed position by a pressure differential between the inside surface and the outside surface of the shutter member or latched in place in the closed position. Split ribs are included on the inside surface of the shutter member to resist the expansion of the shutter member when maintained in the closed position by the pressure differential.

  14. 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 crystallization exceeded 120 μm, which is the clinically acceptable threshold.

  15. Assessment of stress state of rock mass with the help of seismic soundings

    Energy Technology Data Exchange (ETDEWEB)

    Blyakhman, A.S.; Proskuryakov, V.M.

    1984-01-01

    Method of measurement using seismic soundings without drilling boreholes is described. A physical basis is provided for the method used and the results are supplied for the assessment of the stress state of rock mass in the Norilsk coal basin. In the last few years, wide use has been made of linear profiling without drilling boreholes in order to determine the stress state of rock needed for predicting outbursts in coal seams. The method can be used to investigate rectilinear sections of mine workings which are over 20 m. However, in order to resolve a variety of mine problems, e.g. predicting and investigating dynamic phenomena, it is necessary to acquire information about the state of rock mass up to 10 to 15 m. With this in mind the VNIMI has developed a new variant of seismic sounding without the need to drill boreholes which, unlike other known methods, makes it possible to determine parameters of the abutment pressure along the whole perimeter of the rock mass in question. The investigations carried out indicate that the increases and decreases in stress as well as the rise and fall in the rate of stress wave propagation in the abutment zone can be approximated with sufficient accuracy by line segments. Results of the investigations obtained with the help of seismic soundings at the Oktyabrskii mine, Norilsk coal basin, are given.

  16. The Benefit System and its scope in contemporary orthodontic protocols

    Directory of Open Access Journals (Sweden)

    Benedict Wilmes

    2015-01-01

    Full Text Available Currently, the alveolar process is the most preferred insertion site for orthodontic mini-implants. However, due to the varying bone quality and the risk of root contact, the survival rate of implants inserted in the alveolar ridge still needs improvement. Other regions, such as the anterior palate and the mental region provide much better conditions for temporary anchorage device (TAD insertion since the amount and quality of the available bone are far superior. Mini-implants with different types of abutments and connectors allow the construction of versatile and cost efficient appliances for a large variety of orthopedic and orthodontic applications. Utilizing TAD′s in the anterior palate and the mental region eliminates the risk of root injury and takes the implants out of the path of tooth movement. The design of the interchangeable abutment system provides the orthodontist with a skeletal anchorage system that integrates easily into clinical practice and allows treatment of cases that were difficult or impossible to treat previously.

  17. The use of attachments in combination implant and natural-tooth fixed partial dentures: a technical report.

    Science.gov (United States)

    Cohen, S R; Orenstein, J H

    1994-01-01

    When implants and natural teeth are combined, forces on the abutments need to be controlled so that neither the teeth nor the implants sustain excessive amounts of force. The technique described addresses reduction of potentially harmful cantilever effects in a fixed prosthesis that is facultatively removable. A nonrigid attachment is used in the implant crown. Telescopic copings are definitively cemented on the natural teeth. Provisionally cemented overcastings incorporate this nonrigid connection between the pontics and the implant crowns. The means of connection employs a semiprecision attachment in which the female connector is placed within the relatively immobile implant crown. The male connector is placed on the pontic seating into the implant crown. This relationship limits cantilever forces exerted on the natural-tooth abutment. The nonrigid connection of the tooth-supported retainer limits cantilever forces and directs occlusal loads axially in a direction along the long axis of the implant. This arrangement is acceptable as compared to the complete tooth-supported arrangement described by Shillingburg; in this situation, the implant will not migrate. Since 1986, this arrangement has been used clinically without attachment migrations, implant failure, or endodontic therapy, with only minor screw-loosening episodes.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. Implant-supported fixed dental prostheses with CAD/CAM-fabricated porcelain crown and zirconia-based framework.

    Science.gov (United States)

    Takaba, Masayuki; Tanaka, Shinpei; Ishiura, Yuichi; Baba, Kazuyoshi

    2013-07-01

    Recently, fixed dental prostheses (FDPs) with a hybrid structure of CAD/CAM porcelain crowns adhered to a CAD/CAM zirconia framework (PAZ) have been developed. The aim of this report was to describe the clinical application of a newly developed implant-supported FDP fabrication system, which uses PAZ, and to evaluate the outcome after a maximum application period of 36 months. Implants were placed in three patients with edentulous areas in either the maxilla or mandible. After the implant fixtures had successfully integrated with bone, gold-platinum alloy or zirconia custom abutments were first fabricated. Zirconia framework wax-up was performed on the custom abutments, and the CAD/CAM zirconia framework was prepared using the CAD/CAM system. Next, wax-up was performed on working models for porcelain crown fabrication, and CAD/CAM porcelain crowns were fabricated. The CAD/CAM zirconia frameworks and CAD/CAM porcelain crowns were bonded using adhesive resin cement, and the PAZ was cemented. Cementation of the implant superstructure improved the esthetics and masticatory efficiency in all patients. No undesirable outcomes, such as superstructure chipping, stomatognathic dysfunction, or periimplant bone resorption, were observed in any of the patients. PAZ may be a potential solution for ceramic-related clinical problems such as chipping and fracture and associated complicated repair procedures in implant-supported FDPs.

  3. Analysis on Filling Ratio and Shield Supporting Pressure for Overburden Movement Control in Coal Mining with Compacted Backfilling

    Directory of Open Access Journals (Sweden)

    Yanli Huang

    2016-12-01

    Full Text Available Since the weight of overburden is sustained by both the backfill body and the unmined solid coal in coal mining with compacted backfilling (CMCB panels, the stress and deformation characteristics of the surrounding rocks in coal mining are radically changed. The overburden movement control mechanism by coordinating with backfill body and shield in CMCB was studied systematically in this paper. Based on the analysis of deformational and structural characteristics of surrounding rock in CMCB panels, the methods of theoretical analysis, numerical simulation and engineering test are employed. The results show that the fracture of the main roof is mainly controlled by the filling ratio φ and is non-correlated to the shield supporting pressure p. However, p has a significant control effect on the deflection of roof within the shield canopy length, and adversely affects the filling ratio. With the increase of the filling ratio of the gob, the maximum sagging of the immediate and the main roofs, the peak front and the influence range of the abutment pressures are gradually reduced. Correspondingly, the stable period of internal pressure of backfill body in the gob is shortened. Engineering practice shows that the sagging of the gob roof, the distribution of the abutment pressure, the distribution of the internal pressure in the backfill body, and the ground surface sagging results obtained by the in-situ measurement are approximately corresponding to the theoretical analysis and numerical simulation results.

  4. 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.

  5. 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.

  6. Crystalline anatase-rich titanium can reduce adherence of oral streptococci.

    Science.gov (United States)

    Dorkhan, Marjan; Hall, Jan; Uvdal, Per; Sandell, Anders; Svensäter, Gunnel; Davies, Julia R

    2014-01-01

    Dental implant abutments that emerge through the mucosa are rapidly covered with a salivary protein pellicle to which bacteria bind, initiating biofilm formation. In this study, adherence of early colonizing streptococci, Streptococcus gordonii, Streptococcus oralis, Streptococcus mitis and Streptococcus sanguinis to two saliva-coated anodically oxidized surfaces was compared with that on commercially pure titanium (CpTi). Near edge X-ray absorption (NEXAFS) showed crystalline anatase was more pronounced on the anodically oxidized surfaces than on the CpTi. As revealed by fluorescence microscopy, a four-species mixture, as well as individual bacterial species, exhibited lower adherence after 2 h to the saliva-coated, anatase-rich surfaces than to CpTi. Since wettability did not differ between the saliva-coated surfaces, differences in the concentration and/or configuration of salivary proteins on the anatase-rich surfaces may explain the reduced bacterial binding effect. Anatase-rich surfaces could thus contribute to reduced overall biofilm formation on dental implant abutments through diminished adherence of early colonizers.

  7. 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

  8. Restoring the gingival contour by means of provisional resin crowns after single-implant treatment.

    Science.gov (United States)

    Jemt, T

    1999-02-01

    A consecutive group of 55 patients was treated with 63 single-implant restorations. The soft tissue was allowed to heal to either provisional resin crowns (n = 25) that were placed at the time of second-stage surgery, or to healing abutments (n = 38) before final crown insertion. An index that assessed the size of the interproximal mucosa adjacent to the single-implant restorations was used to evaluate the volume of the papillae 2 years after crown insertion. The results indicated that the use of provisional crowns may restore soft tissue contour faster than healing abutments alone, but the papillae adjacent to single-implant restorations presented similar volume in both groups after 2 years in function. Furthermore, the mean marginal bone loss at the implants was 0.9 mm after 1 year, and no differences were observed between the 2 groups. The present data focus on the need for more scientific data to evaluate different clinical procedures for optimizing esthetic results in implant dentistry.

  9. 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.

  10. Basic Finite Element Analysis of Para-periodontal Ligament in All-ceramic Zirconia Fixed Partial Denture.

    Science.gov (United States)

    Nomoto, Syuntaro; Matsunaga, Satoru; Sato, Toru; Yotsuya, Mamoru; Abe, Shinichi

    2015-01-01

    The purpose of the present study was to investigate the validity of incorporating a para-periodontal ligament in the test mold used in a basic fracture test of a zirconia all-ceramic fixed partial denture (FPD). A simplified three-dimensional finite element analysis model was designed based on the three-unit FPD fracture test. Two types of model, one with and one without a para-periodontal ligament between the abutment and base mold, were fabricated. Microfocus CT of the missing first molar area in a dry human mandible was performed. A three-dimensional model was then fabricated based on the data obtained. A load of 600 N was applied to the center of the pontic and stress distribution observed. The model with the para-periodontal ligament showed stress dispersion to the dental root with rotation of the abutment mold. Stress distribution in the finite element analysis model with a para-periodontal ligament showed greater similarity with that in the mandibular model than with that in the other two models without a para-periodontal ligament.

  11. Cassette loaded with a resilient packing to connect socket ends on the sea bed

    Energy Technology Data Exchange (ETDEWEB)

    Tuson, S.P.R.

    1983-06-08

    A cassette loaded with a resilient packing is used to connect a pipe on the sea bed to one end of a hollow shaft forming part of the crosspiece of a cardan joint at the base of an articulated columns mounted on the sea bed. The resilient packing comprises a stack of rubber rings and metallic washers disposed between end rings and capable of being derformed in torsion, the packing in use being compressed between an abutment on the end of the hollow shaft in the cardan joint and an abutment on the adjacent end of the pipe. The cassette comprises a tubular body which can be fitted in or removed from a housing for a bearing of the cardan joint, the end rings of the packing projecting through the opposite ends of the tubular body of the cassette. The cassette is fitted with jacks for compressing the packing, and wedges for retaining the packing in a compressed state until the cassette is fitted in the bearing housing, whereupon the jacks are again operated to compress further the packing and enable the wedges to be removed. Release of the jacks then allows the packing to expand within the cassette and engage the ends of the packing against the ends of the hollow shaft and pipe so as to form a connection therebetween. 2 drawings.

  12. Equipment for removing and refitting resilient packing in a cardan joint on the sea bed

    Energy Technology Data Exchange (ETDEWEB)

    Tuson, S.P.R.

    1983-06-08

    Equipment for removing and refitting resilient packing in a cardan joint at the base of a platform or column mounted on the sea bed, the cardan joint connected a pipe in the sea bed with a pipe leading up the column, said packing comprising a stack of rubber rings and metallic washers disposed between end plates and capable of being deformed in torsion and said packing being compressed between an abutment on the end of a hollow shaft in the cardan joint and an abutment on the adjacent end of a pipe. The equipment, comprising a casing, a carriage movable along guides on the casing, and a fork-shaped gripper mounted on the carriage, is provided with hooks adapted to secure the casing to the cardan joint, and drive means operable to move the carriage so that the gripper embraces the packing when the casing is secured to the cardan joint, said gripper including power operated pinchers having jaws arranged to engage lugs on the end plates of the packing and operable to force the end plates towards one another to compress the packing and reduce the overall length of the packing. 6 drawings.

  13. 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.

  14. "Evolution Canyon," a potential microscale monitor of global warming across life.

    Science.gov (United States)

    Nevo, Eviatar

    2012-02-21

    Climatic change and stress is a major driving force of evolution. The effects of climate change on living organisms have been shown primarily on regional and global scales. Here I propose the "Evolution Canyon" (EC) microscale model as a potential life monitor of global warming in Israel and the rest of the world. The EC model reveals evolution in action at a microscale involving biodiversity divergence, adaptation, and incipient sympatric speciation across life from viruses and bacteria through fungi, plants, and animals. The EC consists of two abutting slopes separated, on average, by 200 m. The tropical, xeric, savannoid, "African" south-facing slope (AS = SFS) abuts the forested "European" north-facing slope (ES = NFS). The AS receives 200-800% higher solar radiation than the ES. The ES represents the south European forested maquis. The AS and ES exhibit drought and shade stress, respectively. Major adaptations on the AS are because of solar radiation, heat, and drought, whereas those on the ES relate to light stress and photosynthesis. Preliminary evidence suggests the extinction of some European species on the ES and AS. In Drosophila, a 10-fold higher migration was recorded in 2003 from the AS to ES. I advance some predictions that could be followed in diverse species in EC. The EC microclimatic model is optimal to track global warming at a microscale across life from viruses and bacteria to mammals in Israel, and in additional ECs across the planet.

  15. Biological Width around One- and Two-Piece Implants Retrieved from Human Jaws

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    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.

  16. Full mouth rehabilitation of a patient with mandibular implant screw retained Fp-3 prosthesis opposing maxillary acrylic removable over-denture.

    Science.gov (United States)

    Jain, Ashish R; Nallaswamy, Deepak; Ariga, Padma; Philip, Jacob Mathew

    2013-04-01

    A hybrid denture is one that is fabricated over a metal framework and retained by screws threaded into the implant abutments. The anterior part of a mandibular hybrid denture is fixed on implants while the posterior part of the denture is extended and cantilevered from implants. This article presents the fabrication of a maxillary over-denture opposing mandibular implant retained hybrid prosthesis. A total of four implants were placed in the mandibular arch. Castable abutments were used to produce the optimal angulations. Framework was waxed, cast recovered, and the fit was refined until the framework seated passively on the master cast. The mandibular denture teeth were waxed to the hybrid framework, and a final wax try-in was performed to verify and correct maxillomandibular relations before processing. The prosthesis was inserted after verification of occlusion, retention, and stability. The rehabilitation of edentulous patients with hybrid dentures has been observed to achieve greater masticatory function and psychological satisfaction than with conventional over-dentures. Producing a passive-fitting substructure for a fixed removable screw retained hybrid prosthesis is arguably one of the most technically complex tasks in implant dentistry. The technique presented may not initially produce a perfectly passive framework, but use of disclosing media and adjusting the internal aspect of the casting can result in non-binding, fully seated prostheses.

  17. Full mouth rehabilitation of a patient with mandibular implant screw retained Fp-3 prosthesis opposing maxillary acrylic removable over-denture

    Directory of Open Access Journals (Sweden)

    Ashish R Jain

    2013-01-01

    Full Text Available A hybrid denture is one that is fabricated over a metal framework and retained by screws threaded into the implant abutments. The anterior part of a mandibular hybrid denture is fixed on implants while the posterior part of the denture is extended and cantilevered from implants. This article presents the fabrication of a maxillary over-denture opposing mandibular implant retained hybrid prosthesis. A total of four implants were placed in the mandibular arch. Castable abutments were used to produce the optimal angulations. Framework was waxed, cast recovered, and the fit was refined until the framework seated passively on the master cast. The mandibular denture teeth were waxed to the hybrid framework, and a final wax try-in was performed to verify and correct maxillomandibular relations before processing. The prosthesis was inserted after verification of occlusion, retention, and stability. The rehabilitation of edentulous patients with hybrid dentures has been observed to achieve greater masticatory function and psychological satisfaction than with conventional over-dentures. Producing a passive-fitting substructure for a fixed removable screw retained hybrid prosthesis is arguably one of the most technically complex tasks in implant dentistry. The technique presented may not initially produce a perfectly passive framework, but use of disclosing media and adjusting the internal aspect of the casting can result in non-binding, fully seated prostheses.

  18. Peri-Implant Strain in an In Vitro Model.

    Science.gov (United States)

    Hussaini, Souheil; Vaidyanathan, Tritala K; Wadkar, Abhinav P; Quran, Firas A Al; Ehrenberg, David; Weiner, Saul

    2015-10-01

    An in vitro experimental model was designed and tested to determine the influence that peri-implant strain may have on the overall crestal bone. Strain gages were attached to polymethylmethacrylate (PMMA) models containing a screw-type root form implant at sites 1 mm from the resin-implant interface. Three different types of crown superstructures (cemented, 1-screw [UCLA] and 2-screw abutment types) were tested. Loading (1 Hz, 200 N load) was performed using a MTS Mechanical Test System. The strain gage data were stored and organized in a computer for statistical treatment. Strains for all abutment types did not exceed the physiological range for modeling and remodeling of cancellous bone, 200-2500 με (microstrain). For approximately one-quarter of the trials, the strain values were less than 200 με the zone for bone atrophy. The mean microstrain obtained was 517.7 με. In conclusion, the peri-implant strain in this in vitro model did not exceed the physiologic range of bone remodeling under axial occlusal loading.

  19. 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

  20. 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

  1. Level II scour analysis for Bridge 36 (DUXBTH00040036) on Town Highway 4, crossing Crossett Brook, Duxbury, Vermont

    Science.gov (United States)

    Wild, Emily C.; Degnan, James R.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure DUXBTH00040036 on Town Highway 4 crossing the Crossett Brook, Duxbury, 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 north-central Vermont. The 4.9-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover on the upstream left overbank is pasture. The upstream and downstream right overbanks are forested. The downstream left overbank is brushland, while the immediate banks have dense woody vegetation.In the study area, the Crossett Brook has an incised, sinuous channel with a slope of approximately 0.006 ft/ft, an average channel top width of 55 ft and an average bank height of 9 ft. The channel bed material ranges from gravel to bedrock with a median grain size (D50) of 51.6 mm (0.169 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 1, 1996, indicated that the reach was stable.The Town Highway 4 crossing of the Crossett Brook is a 29-ft-long, two-lane bridge consisting of a 26-foot concrete slab span (Vermont Agency of Transportation, written communication, October 13, 1995). The opening length of the structure parallel to the bridge face is 26 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 35 degrees to the opening while

  2. 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

  3. Level II scour analysis for Bridge 18 (SHEFTH00410018) on Town Highway 41, crossing Millers Run, Sheffield, Vermont

    Science.gov (United States)

    Wild, Emily C.; Boehmler, Erick M.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure SHEFTH00410018 on Town Highway 41 crossing Millers Run, Sheffield, 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 White Mountain section of the New England physiographic province in northeastern Vermont. The 16.2-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is grass upstream and downstream of the bridge while the immediate banks have dense woody vegetation. In the study area, Millers Run has an incised, straight channel with a slope of approximately 0.01 ft/ft, an average channel top width of 50 ft and an average bank height of 6 ft. The channel bed material ranges from sand to boulder with a median grain size (D50) of 50.9 mm (0.167 ft). The geomorphic assessment at the time of the Level I and Level II site visit on August 1, 1995, indicated that the reach was laterally unstable, which is evident in the moderate to severe fluvial erosion in the upstream reach. The Town Highway 41 crossing of the Millers Run is a 30-ft-long, one-lane bridge consisting of a 28-foot steel-stringer span (Vermont Agency of Transportation, written communication, March 28, 1995). The opening length of the structure parallel to the bridge face is 22.2 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 20 degrees to the opening. The computed

  4. 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.

  5. Generating a Homogeneous Dose Distribution in the Junction Region between Two Adjacent Fields in Electron Beam Therapy

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    Mohammad Javad Tahmasebi Birgani

    2010-09-01

    Full Text Available Introduction: Treatment with megavoltage electron beams is ideal for irradiating superficial tumors because of their limited range in tissues. However, for electron treatment of extended areas, such as the chest wall, two or more adjacent fields can be used. Abutment of these fields may lead to significant dose in homogeneities in the junction region. The aim of this study is to offer a new method for generating a homogeneous dose distribution in the junction region between two adjacent fields in electron beam therapy. Materials and Methods: Several approaches have been proposed to solve the problem of ‘hot’ and ‘cold’ spots in the junction region between abutting electron fields. These techniques are based on beam-edge modifying devices or penumbra generators which act to broaden the electron beam penumbra, and thus facilitate field matching. But use of these devices is time consuming and design of the modifications to the applicators are generally applicator dependent. An idea which was originally proposed for matching two adjacent photon fields (with dose inhomogeneity of about 2% is resurrected here. This method is based on the rotation of the gantry such that the adjacent fields have a common edge and the overlap region in treatment volume is eliminated. For this purpose, the effective source to surface distance (SSDeff for the available electron beam energies (6, 9, 12 and 15 MeV and applicators (cones (6 × 6, 10 × 10, 15 ×15, 20 × 20 and 25 × 25 cm2 have been determined for a Varian 2100C linear accelerator. Result: Using SSDeff, in respect to beam divergence, one can use the photon beam behavior for electron beams and achieve a uniform dose distribution in adjacent electron fields. Discussion and Conclusion: Compared to beam-edge modifying devices or penumbra generators that are usually time consuming to plan and set up, rotating the gantry to eliminate the overlap region is simple and applicable in the problem of abutting

  6. Strain analysis of different diameter Morse taper implants under overloading compressive conditions

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    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.

  7. 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.

  8. Effects of resistance form on attachment strength of resin-retained castings.

    Science.gov (United States)

    Wilkes, P W; Shillingburg, H T; Johnson, D L

    2000-01-01

    This study evaluated the effects of tooth preparation design on resistance to dislodgment of a resin-bonded fixed partial denture (RBFPD). The variations of tooth preparation tested included axial coverage, retentive grooves, and an occlusal rest. Patterns of the tooth preparation designs were prepared and cast in a base metal alloy. Retainer patterns were waxed to refractory casts of metal dies, cast, finished and then bonded to the dies. The complete assemblies were loaded to failure on an Instron mechanical testing machine, and analysis indicated that retainers with occlusal rests were the most resistant. Grooves provided no statistically significant increase in resistance to failure of the cement. Increased axial coverage did not increase resistance to dislodgment. Successful fixed partial dentures (FPDs) depend on cast retainers to resist displacement of the restoration during function. Introduction of resin-bonded restorations opened the possibility of FPDs with minimal reduction of abutments. Specific questions concerning long term success and tooth preparation designs were prominent concerns. The influence of resistance form on overall stability of a restoration was also of particular interest. Buonocore established the foundation for retention of composite resins to acid-pitted enamel. Rochette used this technology to bond perforated cast metal splints to periodontally compromised teeth. A mechanical interlock was created as composite resin engaged these perforations and sustained the cast splint to acid-etched enamel. Howe adapted this design for replacement of anterior teeth by adding porcelain to a metal ceramic framework and then bonding the framework to abutments without tooth preparations. The advantages of these procedures were their conservative nature, esthetics, and ease of rebonding after dislodgment. Livaditis and Thompson adapted the procedure proposed by Tanaka of corrosion-pitting the bonding surface of a base metal alloy. They increased the

  9. 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

  10. Marginal and internal fit of all-ceramic crowns fabricated with two different CAD/CAM systems.

    Science.gov (United States)

    Lee, Kyu-Bok; Park, Charn-Woon; Kim, Kyo-Han; Kwon, Tae-Yub

    2008-05-01

    This study evaluated the accuracy of marginal and internal fit between the all-ceramic crowns manufactured by a conventional double-layer computer-aided design/computer-aided manufacturing (CAD/CAM) system and a single-layer system. Ten standardized crowns were fabricated from each of these two systems: conventional double-layer CAD/CAM system (Procera) and a single-layer system (Cerec 3D). The copings and completed crowns were seated on the abutments by a special device that facilitated uniform loading, and the marginal discrepancies were measured. Internal gaps were also measured using a low-viscosity silicone material. Marginal discrepancies of Procera copings were significantly smaller than those of Procera crowns and Cerec 3D crowns (p 0.05). On internal gaps, Cerec 3D crowns showed significantly larger internal gaps than Procera copings and crowns (p system demonstrated acceptable marginal and internal fit.

  11. The use of enamel matrix derivative (Emdogain) for improvement of probing attachment level of the autotransplanted teeth.

    Science.gov (United States)

    Hamamoto, Yoshioki; Takahashi, Kouji; Sakurai, Hiromasa; Akiba, Katsumi; Izumi, Naoya; Kanoh, Hiroyuki; Yoshizawa, Michiko; Saito, Chikara

    2005-12-01

    The enamel matrix derivative (EMD, Emdogain) was used for the purpose to obtain the periodontal regeneration on the denuded root-surfaces of the donor teeth in two cases of the immediate tooth-transplantation. The root-surfaces at the cervical portion of the teeth were denuded because of extrusion. The healthy periodontium of each tooth remained at the apical portion of the roots. The denuded root-surfaces were cleansed before extraction. Then, the donor teeth were gently extracted with forceps, administered EMD, and transplanted so that the denuded surfaces were covered by gingival flaps. After the transplantation, the mean probing attachment level (PAL) improved 3.2 mm and 1.5 mm, respectively. The mean probing pocket depth was within normal level. The actual supporting areas of the roots of the transplanted teeth increased and the teeth worked as the abutments of prosthetic bridges.

  12. Supercharged two-cycle engines employing novel single element reciprocating shuttle inlet valve mechanisms and with a variable compression ratio

    Science.gov (United States)

    Wiesen, Bernard (Inventor)

    2008-01-01

    This invention relates to novel reciprocating shuttle inlet valves, effective with every type of two-cycle engine, from small high-speed single cylinder model engines, to large low-speed multiple cylinder engines, employing spark or compression ignition. Also permitting the elimination of out-of-phase piston arrangements to control scavenging and supercharging of opposed-piston engines. The reciprocating shuttle inlet valve (32) and its operating mechanism (34) is constructed as a single and simple uncomplicated member, in combination with the lost-motion abutments, (46) and (48), formed in a piston skirt, obviating the need for any complex mechanisms or auxiliary drives, unaffected by heat, friction, wear or inertial forces. The reciprocating shuttle inlet valve retains the simplicity and advantages of two-cycle engines, while permitting an increase in volumetric efficiency and performance, thereby increasing the range of usefulness of two-cycle engines into many areas that are now dominated by the four-cycle engine.

  13. Strategic extraction protocol: Use of an image-fusion stereolithographic guide for immediate implant placement.

    Science.gov (United States)

    Dada, Karim; Pariente, Leon; Daas, Marwan

    2016-11-01

    Increasingly, patients are demanding a smooth transition from a hopeless dentition to a fixed implant-supported prosthesis without the use of an interim removable denture. This raises new challenges in adapting computer-aided design and computer-aided manufacturing (CAD-CAM) techniques to patients whose treatment plan includes immediate implant placement in fresh extraction sockets. To facilitate this conversion to a rehabilitated dentition, a strategic extraction protocol (SEP) can be applied. The SEP consists of selecting strategic, remaining, hopeless teeth as abutments to stabilize an image-fusion stereolithographic guide and to allow the immediate placement of sufficient implants to support an immediately loaded fixed prosthesis. The remaining supporting teeth are extracted in the same surgical session before the placement of the interim prosthesis.

  14. Rilievo e ricostruzione virtuale del Ponte Sud di Hierapolis di Frigia (Turchia

    Directory of Open Access Journals (Sweden)

    Giacomo Di Giacomo

    2013-05-01

    Full Text Available The paper concerns the topographical survey and the 3D reconstruction of a Roman bridge-aqueduct located immediately to the south of Hierapolis in Phrygia (south-western Turkey, along the ancient route directed to Colosse and the internal Anatolia; only its southern abutment and scarce remains of the northern one are preserved. It is in a very difficult location, inside the narrow and deep valley, and it was never studied before. During the 2011 field work campaign of the Italian Archaeological Mission, it was surveyed using a high precision differential GPS system (for the plan documentation and its positioning in the digital archaeological map of Hierapolis and through a Motorized Robotic Total Station (for the documentation of the elevation and the creation of a 3D model of the southern side with the aim of its virtual reconstruction.

  15. Fabrication of a CAD/CAM monolithic zirconia crown to fit an existing partial removable dental prosthesis

    Science.gov (United States)

    2016-01-01

    Fabricating a surveyed prosthesis beneath an existing partial removable dental prosthesis (PRDP) is a challenging and time-consuming procedure. The computer-aided design/computer-assisted manufacturing (CAD/CAM) technology was applied to fabricate a retrofitted, surveyed zirconia prosthesis to an existing PRDP. CAD/CAM technology enabled precise and easy replication of the contour of the planned surveyed crown on the existing abutment tooth. This technology ensured excellent adaptation and fit of newly fabricated crown to the existing PRDP with minimal adjustments. In this case report, a seventy-year-old male patient presented with fractured existing surveyed crown. Because the existing PRDP was serviceable, new crown was fabricated to the existing PRDP. PMID:27555903

  16. Fitting accuracy and fracture resistance of crowns using a hybrid zirconia frame made of both porous and dense zirconia.

    Science.gov (United States)

    Nakamura, Takashi; Sugano, Tsuyoshi; Usami, Hirofumi; Wakabayashi, Kazumichi; Ohnishi, Hiroshi; Sekino, Tohru; Yatani, Hirofumi

    2015-01-01

    The purpose of this study is to evaluate the fitting accuracy and fracture resistance of crowns using a hybrid zirconia frame made of both porous and dense zirconia. Commercial semi-sintered zirconia, sintered dense zirconia and sintered hybrid zirconia were used. Sintered zirconia was milled using the CAD/CAM system, and semi-sintered zirconia was milled and sintered to fabricate molar crown frames. Completed frames were veneered with tooth-colored porcelain. The marginal and internal gaps between frames/crowns and abutments were measured. Each crown specimen was subjected to a fracture test. There were no significant differences in marginal and internal gap among all the frames and crowns. The crown with the hybrid zirconia frame had a 31-35% greater fracture load than that with the commercial or dense zirconia frame (pcrowns with a hybrid zirconia frame have a high fracture resistance.

  17. Dielectric relaxation and electronic spectroscopy of double potassium yttrium tetraoxophosphate(V) K 3Y(PO 4) 2 doped by neodymium and europium ions

    Science.gov (United States)

    Szulia, S.; Kosmowska, M.; Kołodziej, H. A.; Sobczyk, M.; Czupińska, G.

    2011-12-01

    The paper presents the results of our investigation on electric properties of double potassium yttrium tetraoxophosphate(V) doped by lanthanide ions K 3Y (1-x)Ln x(PO 4) 2 ( x = 0.01, 0.05, Ln = Eu 3+, Nd 3+). Electric permittivity and dielectric loss measurements have been performed on polycrystalline samples in the temperature range -50 °C to +120 °C and frequency range 1 kHz-1 MHz by means of HP 4282A impedance meter. The frequency and temperature dependence of electric properties were analyzed by theoretical models of dielectric relaxation in order to obtain information abut molecular dynamic of our solids in external electric field.

  18. Successful Loading of a Bone-Anchored Hearing Implant at 1 Week After Surgery

    DEFF Research Database (Denmark)

    Høgsbro, Morten; Agger, Andreas; Johansen, Lars Vendelbo

    2017-01-01

    OBJECTIVE: To assess implant stability and safety of loading a bone-anchored implant 1 week after surgery. The patients were loaded at 1 week for fast rehabilitation and ease of logistics. DESIGN: Single center, prospective cohort study of 25 adults with expected normal skin and bone quality....... INTERVENTION: Implantation of the Baha BA400 implant system using a linear incision technique without skin thinning. Abutment lengths of 8, 10, and 12 mm were used. MAIN OUTCOME MEASURES: Implant stability quotient (ISQ) 0, 7, 14, 30 days and 3, 6, and 12 months postoperatively. RESULTS: Twenty-five patients...... with initial dip. ISQ for patients in the initial dip group eventually increased despite the early and continued loading. CONCLUSION: Loading of the implant system under study 1 week after surgery have been successful for 25 patients with expected normal bone quality followed up for 1 year. No implants were...

  19. Understanding dental CAD/CAM for restorations--the digital workflow from a mechanical engineering viewpoint.

    Science.gov (United States)

    Tapie, L; Lebon, N; Mawussi, B; Fron Chabouis, H; Duret, F; Attal, J-P

    2015-01-01

    As digital technology infiltrates every area of daily life, including the field of medicine, so it is increasingly being introduced into dental practice. Apart from chairside practice, computer-aided design/computer-aided manufacturing (CAD/CAM) solutions are available for creating inlays, crowns, fixed partial dentures (FPDs), implant abutments, and other dental prostheses. CAD/CAM dental solutions can be considered a chain of digital devices and software for the almost automatic design and creation of dental restorations. However, dentists who want to use the technology often do not have the time or knowledge to understand it. A basic knowledge of the CAD/CAM digital workflow for dental restorations can help dentists to grasp the technology and purchase a CAM/CAM system that meets the needs of their office. This article provides a computer-science and mechanical-engineering approach to the CAD/CAM digital workflow to help dentists understand the technology.

  20. Theory and test research on permeability of coal and rock body influenced by mining

    Institute of Scientific and Technical Information of China (English)

    QI Qing-xin; LI Hong-yan; WANG You-gang; DENG Zhi-gang; LAN Hang; PENG Yong-wei; LI Chun-rui

    2009-01-01

    Stress distribution rules and deformation and failure properties of coal and rock bodies influenced by mining were analyzed. Experimental research on permeability of coal and rock samples under different loading conditions was finished in the laboratory. In-situ measurement of coal permeability influenced by actual mining was done as well. Theory analysis show that permeability varied with damage development of coal and rock under stress, and the influence of fissure on permeability was greatest. Laboratory results show that under different loading conditions permeability was different and it varied with stress, which indicated that permeability was directly related to the loading process. In-situ tests showed that permeability is related to abutment stress to some degree. The above results may be referenced to gas prevention and drainage.

  1. Amyloidosis cutis dyschromica: A rare reticulate pigmentary dermatosis

    Directory of Open Access Journals (Sweden)

    Shyam Verma

    2015-01-01

    Full Text Available We are reporting a rare case of amyloidosis cutis dyschromica in a 41-year-old man. This is a rare form of primary cutaneous amyloidosis characterized by reticulate pigmentation with hypopigmented and hyperpigmented macules, onset in childhood, familial tendency in some, occasional mild itching and deposition of amyloid in the papillary dermis. Our case also had multiple bilaterally symmetrical hyperpigmented keratotic papules abutting the axillary vault resembling those seen in Dowling-Deogs disease. The other unusual feature in this patient was the strong family history of vitiligo, which we are unable to explain. We have also tried to explain the mechanism leading to the hyperpigmentation and hypopigmentation in amyloidosis cutis dyschromica.

  2. 三种烤瓷桥临床修复六年的回顾分析%The 6-year clinical comparison of compound galvano-ceramic bridges with gold alloy and Ni-Cr alloy ceramic bridges

    Institute of Scientific and Technical Information of China (English)

    孙凤; 张相嗥; 刘峰; 周团锋; 孙萍

    2008-01-01

    目的 追踪观察金沉积基底冠熔结镍铬桥体烤瓷桥、金合金烤瓷桥和镍铬合金烤瓷桥的临床效果,为评价不同烤瓷桥临床修复的远期效果提供参考.方法 制作金沉积基底冠熔结镍铬桥体烤瓷桥(A组)35件,同期分别制作金合金烤瓷桥(B组)和镍铬合金烤瓷桥(c组)各35件,临床检查105件修复体的边缘密合性,随访复查修复体的基牙继发龋和修复体折裂、折断、脱落情况.结果 105件修复体平均随访6年.A组边缘密合性好(100%),明显好于B组(91%)与C组(77%)(P0.05).其余修复体均无桥架松动、折断以及修复体脱落.结论 金沉积基底冠熔结镍铬桥体烤瓷桥有良好的边缘密合度,强度可满足临床要求,有临床应用价值.但其与常规铸造合金烤瓷桥一样,需谨慎使用,提倡用于无髓基牙烤瓷桥修复.%Objective To evaluate and compare effects of compound galvano-ceramic bridges with Ni-Cr alloy ceramic bridges and gold alloy ceramic bridges in clinic.Methods A total of 105 bridges were made for 103 patients.Of them,35 were compound galvano-ceramic bridges,35 Ni-Cr alloy ceramic bridges,and 35 gold alloy ceramic bridges respectively.The marginal fitness and fracture of ceramic bridges were checked and caries or second caries of all abutments were also examined in clinic at 6 years after cementation.Results The marginal fitness of compound galvano-ceramic bridges was evaluated as good in 100% of the bridges,which was better than the fitness of gold alloy ceramic bridges(91%) and Ni-Cr alloy ceramic bridges(77%)(P0.05).None of compound galvano-ceramic bridge was found out caries or second caries of abutments.Two of 35(6%) gold alloy ceramic bridges was found out second caries of abutments and five of 35(14%) Ni-Cr alloy ceramic bridges were found out caries or second caries of abutments at 6 years.None of frameworks of all bridges was loose or broken.Conclusions The 6-year clinical study on compound galvano

  3. PERAWATAN PULPOTOMI MORTAL SATU KALI KUNJUNGAN PADA MOLAR SULUNG NON VITAL (Laporan Kasus

    Directory of Open Access Journals (Sweden)

    Bariah Bariah

    2015-08-01

    Full Text Available Non-vital teeth are supposed to be treated with root canal treatment and root canal filling. However, the problem on root canal treatment on deciduous molars, especially with children who is noncooperative because the difficulty to get access to the root canal on children and root canals on deciduous molars are very complex. Mortal pulpotomy is the way to eliminate necrotic pulp tissue in pulp chamber and replace it with material filling. The material is a combination between formocresol and zinc oxide eugenol. The result on formocresol pulpotomy on deciduous teeth can be seen in clinical, radiographic and histological examination of the teeth, abutment tissue and the growth permanent teeth germ. On this patient the mortal pulpotomy treatment had been done with formocresol on one visit. After a month, on the clinical evaluation there are no subjective complaints and no signs of gingival inflammation.

  4. A multi-faceted treatment approach for anterior reconstructions using current ceramics, implants, and adhesive systems.

    Science.gov (United States)

    Hajtó, Jan; Gehringer, Uwe; Ozcan, Mutlu

    2010-01-01

    Of all developments in dental technology, fulfilling the esthetic and functional demands of the patient, especially regarding anterior reconstructions, is still a challenge for both dentists and dental technicians. This becomes more difficult for patients with a previous treatment history that is not ideal. This case presentation demonstrates reconstruction of an anterior zirconia resin-bonded fixed dental prosthesis (RBFDP) for the mandible with a combined approach utilizing veneers for harmonized space distribution on the abutment teeth and an implant-supported zirconia fixed dental prosthesis in the anterior segment of the maxilla. Adhesive cementation of the restorations is also presented in a step-by-step approach based on the current state of the art.

  5. Test studies of gas flow in rock and coal surrounding a mined coal seam

    Institute of Scientific and Technical Information of China (English)

    Lv Youchang

    2012-01-01

    An analysis of the variation rule of abutment pressure at the mining working face in a single coal seam and the mechanical behavior of surrounding rock during stoping is presented.Consideration of the elastic and plastic deformation zones that develop during the mining process allowed the determination of a relationship between horizontal stress and vertical stress.Based on this,a confined pressure unloading test was conducted by the use of the "gas-containing coal thermo-fluid-solid coupling 3-axis servo seepage" experimental apparatus.Thus,gas flow patterns in the elastic and plastic zones were derived from an experimental point of view.Darcy's law and the Klinkenberg effect were used to derive a gas flow equation for the elastic and plastic stress fields.The study of gas flow phenomena at the working face during coal mining is of great importance for the study of gas migration and enrichment oatterns.

  6. Electrolytic/fuel cell bundles and systems including a current collector in communication with an electrode thereof

    Science.gov (United States)

    Hawkes, Grant L.; Herring, James S.; Stoots, Carl M.; O& #x27; Brien, James E.

    2013-03-05

    Electrolytic/fuel cell bundles and systems including such bundles include an electrically conductive current collector in communication with an anode or a cathode of each of a plurality of cells. A cross-sectional area of the current collector may vary in a direction generally parallel to a general direction of current flow through the current collector. The current collector may include a porous monolithic structure. At least one cell of the plurality of cells may include a current collector that surrounds an outer electrode of the cell and has at least six substantially planar exterior surfaces. The planar surfaces may extend along a length of the cell, and may abut against a substantially planar surface of a current collector of an adjacent cell. Methods for generating electricity and for performing electrolysis include flowing current through a conductive current collector having a varying cross-sectional area.

  7. Entre santos y ‘traquetos’.

    Directory of Open Access Journals (Sweden)

    Hernán Moreano.

    2010-01-01

    Full Text Available This article describes the situation of people living in the Ecuadorian provinces of Esmeraldas, Carchi and Sucumbios, which abut the Colombian departments of Nariño and Putumayo. Nowadays this place is considered a war zone due to the high presence of illegal armed groups linked to the drug trade and other related activities. As a result, both states conducted daily monitoring operations to deter the presence of coca leaf crops, cocaine laboratories and clandestine bases of guerrillas and paramilitaries. This study had the cooperation of residents that lived within the 725 km border, who recounted how their daily lives were and what their demands were to reduce their vulnerability to illegal activity. In addition was a brief description of the historical context of drug trafficking in the Andean region and the influence of the anti-drug policy of the United States.

  8. Wind turbine tower for storing hydrogen and energy

    Science.gov (United States)

    Fingersh, Lee Jay

    2008-12-30

    A wind turbine tower assembly for storing compressed gas such as hydrogen. The tower assembly includes a wind turbine having a rotor, a generator driven by the rotor, and a nacelle housing the generator. The tower assembly includes a foundation and a tubular tower with one end mounted to the foundation and another end attached to the nacelle. The tower includes an in-tower storage configured for storing a pressurized gas and defined at least in part by inner surfaces of the tower wall. In one embodiment, the tower wall is steel and has a circular cross section. The in-tower storage may be defined by first and second end caps welded to the inner surface of the tower wall or by an end cap near the top of the tower and by a sealing element attached to the tower wall adjacent the foundation, with the sealing element abutting the foundation.

  9. Correlation between improper dental prosthetic restoration and temporomandibular disorders%不良修复体与颞下颌关节紊乱病的相关性研究

    Institute of Scientific and Technical Information of China (English)

    刘志明; 付东杰; 张周文; 彭友俭

    2015-01-01

    目的:研究不良修复体导致颞下颌关节紊乱病(TMD)的因素。方法选择199例佩戴不良修复体并导致 TMD 的患者,根据不良修复体引起的症状分为3组:咬合垂直距离改变组、咬合紊乱组、基牙损伤组。治疗后随访12个月,通过分析 TMD 治疗的有效性,探讨不良修复体引起 TMD 的因素。结果咬合垂直距离改变、咬合紊乱、基牙损伤3组治疗有效率分别为89.55%、89.06%、32.35%,基牙损伤组治疗有效率与其他2组比较,差异均有统计学意义(P<0.05),提示咬合垂直距离改变和咬合紊乱更容易导致 TMD 。结论不良修复体所导致的上下颌垂直距离改变、咬合关系紊乱与基牙损伤与颞下颌关节滑膜炎、关节盘移位及骨关节病存在相关性。%Objective To investigate the factors of temporomandibular disorders(TMD) caused by the improp‐er dental prosthetic restoration .Methods 199 cases of improper dental prosthetic restoration and TMD were selected and divided into 3 groups according to the symptoms caused by improper dental prosthetic restoration :occlusion ver‐tical distance change ,occlusion disorders and abutment tooth injury .The follow up after treatment lasted for 12 months .The factors of improper dental prosthetic restoration caused TMD were investigated by analyzing the TMD treatment effectiveness .Results The treatment effective rates in the occlusion vertical distance change group ,occlu‐sion disorders group and abutment tooth injury group were 89 .55% ,89 .06% and 32 .35% respectively ,the effective rate had statistical difference between the abutment tooth injury group with the other two groups(P< 0 .05) ,which prompting that occlusion vertical distance change and occlusion disorders could more easily lead to TMD .Conclusion The occlusion vertical distance change ,occlusion disorders and abutment tooth injury caused by improper dental prosthetic restoration have

  10. Ragged Chute rehabilitation project

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Paul; Slopek, Richard [Canadian Projects Ltd., Calgary, (Canada); Guzwell, Robert [TransAlta, Calgary, (Canada)

    2010-07-01

    The Ragged Chute development, located in northern Ontario, was originally constructed to provide compressed air to a local silver mining company. It was composed of a free overflow spillway, the air plant intake, a concrete gravity retaining wall and an earthfill dyke abutment. The advantage of the river flow and the head developed by the dam for the air plant was recently put to use by the addition of a hydro plant. This paper provided an overview of the use of the river flow over the years and described the recent rehabilitation work being done to upgrade the installations to current dam safety standards. Site inspections were carried out in 2006 as part of the dam safety review to assess the overall condition of the structures. The major operation of the rehabilitation work involved the upgrading of the original fixed crest spillway with a new labyrinth spillway structure. Canadian Hydro completed the dam safety safety rehabilitation work by October 2009.

  11. Modeling aquifer systems with analytic elements and subdomains

    Science.gov (United States)

    Fitts, C. R.

    2010-07-01

    A new approach for analytic element (AE) modeling of groundwater flow is presented. The approach divides the modeled region into polygonal subdomains, each with its own analytic flow model and its own local isotropic or anisotropic aquifer parameters. This allows analytic modeling of systems where the anisotropy ratio and direction vary spatially, an AE capability not possible without subdomains. It also allows for flexible layering in a model, with more layers in the area of interest abutting fewer layers in the far field. The approach is demonstrated in a model with seven subdomains and a mix of single-layer and triple-layer areas. Checks of the model indicate that the inter-subdomain boundary conditions can be approximated well, and where the differential equation is approximated (multilayer areas and transient flow), that approximation can be quite accurate.

  12. The aftershock sequence of the 2015 April 25 Gorkha-Nepal earthquake

    Science.gov (United States)

    Adhikari, L. B.; Gautam, U. P.; Koirala, B. P.; Bhattarai, M.; Kandel, T.; Gupta, R. M.; Timsina, C.; Maharjan, N.; Maharjan, K.; Dahal, T.; Hoste-Colomer, R.; Cano, Y.; Dandine, M.; Guilhem, A.; Merrer, S.; Roudil, P.; Bollinger, L.

    2015-12-01

    The M 7.8 2015 April 25 Gorkha earthquake devastated the mountainous southern rim of the High Himalayan range in central Nepal. The main shock was followed by 553 earthquakes of local magnitude greater than 4.0 within the first 45 days. In this study, we present and qualify the bulletin of the permanent National Seismological Centre network to determine the spatio-temporal distribution of the aftershocks. The Gorkha sequence defines a ˜140-km-long ESE trending structure, parallel to the mountain range, abutting on the presumed extension of the rupture plane of the 1934 M 8.4 earthquake. In addition, we observe a second seismicity belt located southward, under the Kathmandu basin and in the northern part of the Mahabarat range. Many aftershocks of the Gorkha earthquake sequence have been felt by the 3 millions inhabitants of the Kathmandu valley.

  13. Physeal arrest of the distal radius.

    Science.gov (United States)

    Abzug, Joshua M; Little, Kevin; Kozin, Scott H

    2014-06-01

    Fractures of the distal radius are among the most common pediatric fractures. Although most of these fractures heal without complication, some result in partial or complete physeal arrest. The risk of physeal arrest can be reduced by avoiding known risk factors during fracture management, including multiple attempts at fracture reduction. Athletes may place substantial compressive and shear forces across the distal radial physes, making them prone to growth arrest. Timely recognition of physeal arrest can allow for more predictable procedures to be performed, such as distal ulnar epiphysiodesis. In cases of partial arrest, physeal bar excision with interposition grafting can be performed. Once ulnar abutment is present, more invasive procedures may be required, including ulnar shortening osteotomy or radial lengthening.

  14. Three Dimensional Analysis of Pier Extension and Guide Wall Design Alternatives to Mitigate Local Scour Risk at the BNSF Railroad Bridge Downstream of the Prado Dam

    Energy Technology Data Exchange (ETDEWEB)

    Lottes, S. A. [Argonne National Lab. (ANL), Argonne, IL (United States); Bojanowski, C. [Argonne National Lab. (ANL), Argonne, IL (United States); Sinha, N. [Argonne National Lab. (ANL), Argonne, IL (United States); Kerenyi, K [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-03-01

    The primary objectives of the computational fluid dynamics (CFD) analysis are (1) to verify that the design concept of using wedge shaped pier extensions to divert flow around piers as a scour counter measure has the intended effect on the flow, (2) to refine the design of the length and orientation of the pier extensions within the channel and (3) to optimize the guide walls that will protect a set of outer piers and the abutments on each side of the channel. The original proposed design is shown in Figure 1.3. The results of this effort are the recommended designs that are judged to be the best designs based on results from the set of test cases run combined with engineering judgment. The refined designs from the CFD analysis are expected to be tested in a limited set of physical model experiments to verify that they work well.

  15. Evolutionary design of a generalized polynomial neural network for modelling sediment transport in clean pipes

    Science.gov (United States)

    Ebtehaj, Isa; Bonakdari, Hossein; Khoshbin, Fatemeh

    2016-10-01

    To determine the minimum velocity required to prevent sedimentation, six different models were proposed to estimate the densimetric Froude number (Fr). The dimensionless parameters of the models were applied along with a combination of the group method of data handling (GMDH) and the multi-target genetic algorithm. Therefore, an evolutionary design of the generalized GMDH was developed using a genetic algorithm with a specific coding scheme so as not to restrict connectivity configurations to abutting layers only. In addition, a new preserving mechanism by the multi-target genetic algorithm was utilized for the Pareto optimization of GMDH. The results indicated that the most accurate model was the one that used the volumetric concentration of sediment (CV), relative hydraulic radius (d/R), dimensionless particle number (Dgr) and overall sediment friction factor (λs) in estimating Fr. Furthermore, the comparison between the proposed method and traditional equations indicated that GMDH is more accurate than existing equations.

  16. Seismic fragility of a highway bridge in Quebec retrofitted with natural rubber isolators

    Directory of Open Access Journals (Sweden)

    G. H. Siqueira

    Full Text Available This paper presents fragility curves for the evaluation of a highway bridge retrofitted with seismic isolator devices. The object of this study is the Chemin des Dalles bridge over Highway 55 located in Trois-Rivières in Quebec, Canada. A series of synthetic ground motions time histories compatible with eastern Canada are used to capture the uncertainties related to the hazard. The seismic isolator model represents natural rubber bearing placed under the longitudinal girders over the bents and the abutments of the bridge. NRB isolators are placed in these locations to uncouple the movement of the superstructure and the infrastructure, increasing the flexibility of the system and decreasing the forces transmitted to the infrastructure. Finally, a set of fragility curves for the as-built and retrofitted models are compared to evaluate the effectiveness of seismic isolation to decrease the seismic vulnerability of this bridge.

  17. Crystal Structure of the Catalytic Core of an RNA-Polymerase Ribozyme

    Energy Technology Data Exchange (ETDEWEB)

    Shechner, David M.; Grant, Robert A.; Bagby, Sarah C.; Koldobskaya, Yelena; Piccirilli, Joseph A.; Bartel, David P.; (MIT); (HHMI); (UC)

    2010-09-02

    Primordial organisms of the putative RNA world would have required polymerase ribozymes able to replicate RNA. Known ribozymes with polymerase activity best approximating that needed for RNA replication contain at their catalytic core the class I RNA ligase, an artificial ribozyme with a catalytic rate among the fastest of known ribozymes. Here we present the 3.0 angstrom crystal structure of this ligase. The architecture resembles a tripod, its three legs converging near the ligation junction. Interacting with this tripod scaffold through a series of 10 minor-groove interactions (including two A-minor triads) is the unpaired segment that contributes to and organizes the active site. A cytosine nucleobase and two backbone phosphates abut the ligation junction; their location suggests a model for catalysis resembling that of proteinaceous polymerases.

  18. Histology of the Larval Neodiprion abietis (Hymenoptera: Diprionidae Digestive Tract

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    Christopher J. Lucarotti

    2011-01-01

    Full Text Available The alimentary canal of Neodiprion abietis larvae is a straight tube divided into foregut, midgut, and hindgut. Posterior to the mouth, the foregut is further divided into the pharynx, esophagus (crop, and proventriculus, all of which are lined with cuticle. A pair of muscular, chitin-lined pouches branch off the anterior foregut and lie lateral to the alimentary canal. Gastric caeca are located at the anterior end of the midgut, where the peritrophic membrane is formed and was observed throughout the midgut. A single layer of midgut columnar epithelial cells abuts on the basal lamina at one end with microvilli extending into the gut lumen at the other. Nidi of regenerative cells were observed between columnar epithelial cells at the basal lamina. Malpighian tubules are attached to the posterior end of the midgut. The hindgut consists of the pylorus, a muscular ileum connecting to a bulbous rectum, which then opens to the anus.

  19. Non-favorable positioning of anterosuperior dental implants — case report

    Directory of Open Access Journals (Sweden)

    Tatiana Miranda DELIBERADOR

    2009-06-01

    Full Text Available Introduction: The treatment with implants has demonstrated to be a good alternative to oral rehabilitation. However, it is important to follow some criteria in order to achieve success. Objective: This report showed an alternative approach to a clinical condition of non-favorable positioning of anterosuperior dental implants, added to an also non- favorable initial prosthetic planning. Case report: Female patient, 60 years old, with fixed prosthesis over labial inclined implants, in the central and lateral superior incisors region, and with peri-implant disease. A new approach with fixed prosthesis and single abutments, what allows cleaning, and also removable gingival mask was applied. Monitoring of 3, 6, 9 and 12 months were done. Conclusion: The use of a prosthetic alternative such as gingival mask demonstrated to be efficient regarding esthetic and masticatory functions, contributing to oral hygiene, an important factor to peri-implanttissues health.

  20. A Novel Technique for Immediate Loading Single Root Form Implants With an Interim CAD/CAM Milled Screw-Retained Crown.

    Science.gov (United States)

    Proussaefs, Periklis

    2016-08-01

    A technique is described where an interim abutment and crown are fabricated in the laboratory by utilizing computer-aided design/computer-aided manufacturing (CAD/CAM) technology and placed the day of dental implant surgery. The design and contours of the interim crown are designed by the computer software to be identical to the contours of the tentatively designed definitive prosthesis. The interim crown satisfies esthetics immediately after dental implant surgery while allowing the tissue to heal and obtain contours similar to the contours of the definitive prosthesis. The interim crown can be either cement retained or screw retained. The presented technique describes fabrication of a screw-retentive interim crown. After osseointegration is confirmed, a definitive impression is made with a CAD/CAM impression coping. The definitive prosthesis is then fabricated.