Browsing by Author "Erkmen, Erkan"
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Article Citation Count: 52Biomechanical comparison of implant retained fixed partial dentures with fiber reinforced composite versus conventional metal frameworks: A 3D FEA study(Elsevier, 2011) Erkmen, Erkan; Meric, Gokce; Kurt, Ahmet; Tunc, Yahya; Eser, AtilimFiber reinforced composite (FRC) materials have been successfully used in a variety of commercial applications. These materials have also been widely used in dentistry. The use of fiber composite technology in implant prostheses has been previously presented, since they may solve many problems associated with metal alloy frameworks such as corrosion, complexity of fabrication and high cost. The hypothesis of this study was that an FRC framework with lower flexural modulus provides more even stress distribution throughout the implant retained fixed partial dentures (FPDs) than a metal framework does. A 3-dimensional finite element analysis was conducted to evaluate the stress distribution in bone, implant-abutment complex and prosthetic structures. Hence, two distinctly different models of implant retained 3-unit fixed partial dentures, composed of Cr-Co and porcelain (M-FPD model) or FRC and particulate composite (FRC-FPD model) were utilized. In separate load cases, 300 N vertical, 150 N oblique and 60 N horizontal forces were simulated. When the FRC-FPD and M-FPD models were compared, it was found that all investigated stress values in the M-FPD model were higher than the values in the FRC-FPD model except for the stress values in the implant-abutment complex. It can be concluded that the implant supported FRC-FPD could eliminate the excessive stresses in the bone-implant interface and maintain normal physiological loading of the surrounding bone, therefore minimizing the risk of peri-implant bone loss due to stress-shielding. (C) 2010 Elsevier Ltd. All rights reserved.Article Citation Count: 14Biomechanical comparison of two different collar structured implants supporting 3-unit fixed partial denture: A 3-D FEM study(Taylor & Francis Ltd, 2012) Meric, Gokce; Erkmen, Erkan; Kurt, Ahmet; Eser, Atilim; Oezden, Ahmet UtkuObjective. The purpose of the study was to compare the effects of two distinct collar geometries of implants on stress distribution in the bone as well as in the fixture-abutment complex, in the framework and in the veneering material of 3-unit fixed partial denture (FPD). Material and methods. The 3-dimensional finite element analysis method was selected to evaluate the stress distribution in the system composed of 3-unit FPD supported by two different dental implant systems with two distinct collar geometries; microthread collar structure (MCS) and non-microthread collar structure (NMCS). In separate load cases, 300 N vertical, 150 N oblique and 60 N horizontal, forces were utilized to simulate the multidirectional chewing forces. Tensile and compressive stress values in the cortical and cancellous bone and von Mises stresses in the fixture-abutment complex, in the framework and veneering material, were simulated as a body and investigated separately. Results. In the cortical bone lower stress values were found in the MCS model, when compared with NMCS. In the cancellous bone, lower stress values were observed in the NMCS model when compared with MCS. In the implant-abutment complex, highest von Mises stress values were noted in the NMCS model; however, in the framework and veneering material, highest stress values were calculated in MCS model. Conclusions. MCS implants when compared with NMCS implants supporting 3-unit FPDs decrease the stress values in the cortical bone and implant-abutment complex. The results of the present study will be evaluated as a base for our ongoing FEA studies focused on stress distribution around the microthread and non-microthread collar geometries with various prosthesis design.Article Citation Count: 7Biomechanical effects of two different collar implant structures on stress distribution under cantilever fixed partial dentures(Taylor & Francis Ltd, 2011) Meric, Gokce; Erkmen, Erkan; Kurt, Ahmet; Eser, Atilim; Ozden, Ahmet UtkuObjective. The purpose of the study was to compare the effects of two distinct collar geometries of implants on stress distribution in the bone around the implants supporting cantilever fixed partial dentures (CFPDs) as well as in the implant-abutment complex and superstructures. Materials and methods. The three-dimensional finite element method was selected to evaluate the stress distribution. CFPDs which was supported by microthread collar structured (MCS) and non-microthread collar structured (NMCS) implants was modeled; 300 N vertical, 150 N oblique and 60 N horizontal forces were applied to the models separately. The stress values in the bone, implant-abutment complex and superstructures were calculated. Results. In the MCS model, higher stresses were located in the cortical bone and implant-abutment complex in the case of vertical load while decreased stresses in cortical bone and implant-abutment complex were noted within horizontal and oblique loading. In the case of vertical load, decreased stresses have been noted in cancellous bone and framework. Upon horizontal and oblique loading, a MCS model had higher stress in cancellous bone and framework than the NMCS model. Higher von Mises stresses have been noted in veneering material for NMCS models. Conclusion. It has been concluded that stress distribution in implant-supported CFPDs correlated with the macro design of the implant collar and the direction of applied force.Article Citation Count: 8Biomechanical evaluation of a fiber-reinforced composite prosthesis supported by implants with and without a microthread collar design(Elsevier Taiwan, 2010) Meric, Gokce; Erkmen, Erkan; Kurt, Ahmet; Eser, Atilim; Celik, GokhanBackground/purpose: A fiber-reinforced composite (FRC) resin system was introduced as an alternative for implant-retained fixed dental prostheses (FDPs); however, the stress distribution in the bone around the implants which support the FRC-FDP has so far not been reported. The aim of this study was to investigate the biomechanical behavior of FRC-FDPs supported by implants with different collar geometries. Materials and methods: A 3-dimensional finite element analysis method was selected to evaluate the stress distribution. FRC-FDPs were supported by 2 different dental implant systems with 2 distinct collar geometries: a microthread collar structure (MCS) and a non-MCS (NMCS). In separate load cases, 300-N vertical, 150-N oblique, and 60-N horizontal forces were simulated. Tensile and compressive stress values in the cortical and cancellous bone and von Mises stresses in the fixture-abutment complex, the framework, and veneer material were calculated. Results: The MCS model revealed higher compression stresses at the cortical bone than did the NMCS model under all 3 load conditions. Moreover, higher tensile stresses under the oblique loads at the cortical bone were shown with the MCS model. In each model, stresses were much higher in the implant abutment complex than in the cortical bone, and they were very low in the cancellous bone. Conclusion: Although additional experimental and clinical studies are needed, FRC-FDPs can be considered a suitable and alternative treatment choice for an implant-supported prosthesis. The implant design and geometry affect the load-transmission mechanisms. Implants with an MCS that supports FRC-FDPs were shown to be superior in terms of the stress distribution in the bone around the implant compared to implants with an NMCS. Copyright (C) 2010, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved.Article Citation Count: 8Biomechanical Evaluation of Different Fixation Methods for Mandibular Anterior Segmental Osteotomy Using Finite Element Analysis, Part One: Superior Repositioning Surgery(Lippincott Williams & Wilkins, 2016) Kilinc, Yeliz; Erkmen, Erkan; Kurt, AhmetThe aim of the current study was to comparatively evaluate the mechanical behavior of 3 different fixation methods following various amounts of superior repositioning of mandibular anterior segment. In this study, 3 different rigid fixation configurations comprising double right L, double left L, or double I miniplates with monocortical screws were compared under vertical, horizontal, and oblique load conditions by means of finite element analysis. A three-dimensional finite element model of a fully dentate mandible was generated. A 3 and 5mm superior repositioning of mandibular anterior segmental osteotomy were simulated. Three different finite element models corresponding to different fixation configurations were created for each superior repositioning. The von Mises stress values on fixation appliances and principal maximum stresses (P-max) on bony structures were predicted by finite element analysis. The results have demonstrated that double right L configuration provides better stability with less stress fields in comparison with other fixation configurations used in this study.Article Citation Count: 7Biomechanical Evaluation of Different Fixation Methods for Mandibular Anterior Segmental Osteotomy Using Finite Element Analysis, Part Two: Superior Repositioning Surgery With Bone Allograft(Lippincott Williams & Wilkins, 2016) Kilinc, Yeliz; Erkmen, Erkan; Kurt, AhmetIn this study, the biomechanical behavior of different fixation methods used to fix the mandibular anterior segment following various amounts of superior repositioning was evaluated by using Finite Element Analysis (FEA). The three-dimensional finite element models representing 3 and 5mm superior repositioning were generated. The gap in between segments was assumed to be filled by block bone allograft and resignated to be in perfect contact with the mandible and segmented bone. Six different finite element models with 2 distinct mobilization rate including 3 different fixation configurations, double right L (DRL), double left L (DLL), or double I (DI) miniplates with monocortical screws, correspondingly were created. A comparative evaluation has been made under vertical, horizontal and oblique loads. The von Mises and principal maximum stress (P-max) values were calculated by finite element solver programme. The first part of our ongoing Finite Element Analysis research has been adressed to the mechanical behavior of the same fixation configurations in nongrafted models. In comparison with the findings of the first part of the study, it was concluded that bone graft offers superior mechanical stability without any limitation of mobilization and less stress on the fixative appliances as well as in the bone.Article Citation Count: 5Does the angulation of the mandibular third molar influence the fragility of the mandibular angle after trauma to the mandibular body? A three-dimensional finite-element study(Taylor & Francis Ltd, 2018) Kilinc, Yeliz; Zor, Zeynep Fatma; Tumer, Mehmet Kemal; Erkmen, Erkan; Kurt, AhmetThe relationship between mandibular third molar (M3) angulation and mandibular angle fragility is not well established. The aim of this study was to evaluate the impact of M3 angulation on the mandibular angle fragility when submitted to a trauma to the mandibular body region. A three-dimensional (3D) mandibular model without M3 (Model 0) was obtained by means of finite-element analysis (FEA). Four models were generated from the initial model, representing distoangular (Model D), horizontal (Model H), mesioangular (Model M) and vertical (Model V) angulations. A blunt trauma with a magnitude of 2000 N was applied perpendicularly to the sagittal plane in the mandibular body. Maximum principal stress (P-max) (tensile stress) values were calculated in the bone. The lowest P-max stress values were noted in Model 0. When the M3 was present extra stress fields were found around marginal bone of second molar and M3. Comparative analysis of the models with M3 revealed that the highest level of stress was found in Model V, whereas Model D showed the lowest stress values. The angulation of M3 affects the stress levels in the mandibular angle and has an impact on mandibular fragility. The mandibular angle becomes more fragile in case of vertical impaction when submitted to a trauma to the mandibular body region.Conference Object Citation Count: 2How do implant threads and diameters affect the all-on-four success? A 3D finite element analysis study(Ios Press, 2022) Zor, Zeynep Fatma; Kilinc, Yeliz; Erkmen, Erkan; Kurt, AhmetBACKGROUND: The effect of different thread designs and diameters on the all-on-four concept is unclear. OBJECTIVE: The aim of the study was to clarify the differences in stress distribution of dental implants with various thread designs and diameters based on the all-on-four concept with three dimensional (3D) finite element analysis (FEA). METHODS: A 3D model of a totally edentulous mandible was used to perform the FEA. Four different models (M1, M2, M3, and M4) including 3.5 and 4.3 mm diameter dental implants with active and passive threaded designs were generated. The dental implants were positioned according to the all-on-four concept. The Von Mises stresses on dental implants and maximum and minimum principal stresses (Pmax and Pmin) on bony structures were calculated under vertical, oblique and horizontal loads. RESULTS: For Von Mises stresses, the highest stress values were detected on the distal implants for all models. Distal implants had also the highest stress values for vertical loading. The Von Mises stresses were found to be concentrated around the implant's neck. In all models the highest Pmax and Pmin stresses occurred in the bone surrounding the distal implant. It was noted that the active threaded implants showed the highest Pmax and Pmin stress values. CONCLUSION: The implant thread design and diameter might have a strong influence on the stress values in the all-on-four concept.Article Citation Count: 22Influence of prosthesis type and material on the stress distribution in bone around implants: A 3-dimensional finite element analysis(Elsevier Taiwan, 2011) Meric, Gokce; Erkmen, Erkan; Kurt, Ahmet; Tunc, Yahya; Eser, AtilimBackground/purpose: The design and materials of a prosthesis affect the loading of dental implants and deformation of the bone. The aim of the study was to evaluate the effects of prosthesis design and materials on the stress distribution of implant-supported prostheses. Materials and methods: A 3-dimensional finite element analysis method was selected to evaluate the stress distribution in the bone. Three different models were designed as follows: a 3-unit implant-supported fixed partial denture (FPD) composed of a metal framework and porcelain veneer with (M2) or without a cantilevered extension (M1) and an FPD composed of a fiber-reinforced composite (FRC) framework and a particulate composite veneer without a cantilevered extension (M3). In separate load cases, 300-N vertical, 150-N oblique, and 60-N horizontal forces were applied to the prostheses in the models. von Mises stress values in the cortical and cancellous bone were calculated. Results: In cortical bone, the highest von Mises stresses were noted in the M2 Model with a vertical load; whereas, higher stresses were observed in the M1 Model with horizontal and oblique loads. The lowest stress values were determined in the M3 Model for all loading conditions. In cancellous bone, decreased stress values were found with all 3 models under the applied loads. Conclusions: Prosthesis design and materials affect the load-transmission mechanism. Although additional experimental and clinical studies are needed, FRC FPDs can be considered a suitable alternative treatment choice for implant-supported prostheses. Within the limitations of the study, the 3-unit FPD supported by 2 implants with a cantilevered extension revealed acceptable stress distributions. Copyright (C) 2011, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved.