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Öğe Effects of cantilever design and material on stress distribution in fixed partial dentures - a finite element analysis(WILEY, 2005) Eraslan, O; Sevimay, M; Usumez, A; Eskitascioglu, GThe purpose of this study was to examine the stress distribution in distal cantilevered fixed partial dentures (FPDs) that are designed with different cantilever morphology and made from different restorative materials. The finite element (FE) method was used to create models of two restoration types; metal-ceramic and an all-ceramic FPDs. Both models were designed with distal cantilevers involving the first and second premolars as abutments and cantilever extension involving at the premolar or molar. The width of connector between the cantilever and the primary abutment restoration was 2.25 mm. The load applied during the FE analysis was positioned at the cusp tips of all teeth. The FE analysis of the models revealed that Von Mises stress values with maximum stress concentrations were observed on connectors of distal cantilevers. Stress concentration sites were also observed at the distal cervical area of the second premolar tooth. Models with premolar cantilever extensions restored with all-ceramic induced lower Von Mises stress values than metal-ceramic restorations, however models with molar cantilever extensions restored with all-ceramic restorations induced higher Von Misses stress values than metal-ceramic restorations. If the distal cantilever length and restorative material is appropriately chosen, the failure frequency may be reduced. All ceramic can be used as restorative material, when the cantilevers length is not more than the mesiodistal dimension of a premolar tooth and metal-ceramic restorations can be used in longer situations.Öğe The influence of occlusal loading location on stresses transferred to implant-supported prostheses and supporting bone: A three-dimensional finite element study(MOSBY-ELSEVIER, 2004) Eskitascioglu, G; Usumez, A; Sevimay, M; Soykan, E; Unsal, EStatement of problem. Information about the influence of occlusal loading by location on the stress distribution in an implant-supported fixed partial denture and supporting bone tissue is limited. Purpose. The purpose of this study was to investigate the effect of loading at I to 3 different locations on the occlusal surface of a tooth on the stress distributions in an implant-supported mandibular fixed partial denture (FPD) and surrounding bone, using 3-dimcnsional finite element analysis. Material and methods. A 3-dimensional finite element model of a mandibular section of bone (Type 2) with missing second premolar and its superstructures were used in this study. A 1-piece 4.1 X 10-mm screw-shape ITI dental implant system (solid implant) was modeled for this study. Cobalt-Chromium (Wiron 99) was used as the crown framework material and porcelain was used for occlusal surface. The implant and its superstructure were simulated in a Pro/Engineer 2000i program. Total loads at 300 N were applied at the following locations: 1) tip of buccal cusp (300 N); 2) tip of buccal cusp (150 N) and distal fossa (150 N); or 3) tip of buccal cusp (100 N), distal fossa (100 N), and mesial fossa (100 N). Results. The results demonstrated that vertical loading at I location resulted in high stress values within the bone and implant. Close stress levels were observed within the bone for loading at 2 locations and 3 locations; the former created the most extreme stresses and the latter the most even stresses within the bone. With loading at 2 or 3 locations, stresses were concentrated on the framework and occlusal surface of the FPD, and low stresses were distributed to the bone. Conclusion. For the loading conditions investigated, the optimal combination of vertical loading was found to be loading at 2 or 3 locations which decreased the stresses within the bone. In this situation, von Mises stresses were concentrated on the framework and occlusal surface of the FPD.Öğe The influence of various occlusal materials on stresses transferred to implant-supported prostheses and supporting bone: A three-dimensional finite-element study(WILEY-LISS, 2005) Sevimay, M; Usumez, A; Eskitascioglu, GThe aim of this numerical analysis was to evaluate the amount and localization of stress that occurs with various materials used in implant-crown design under functional forces. Computer-aided design techniques and a finite-element stress analysis method were used for evaluation. A 4.1 x 10-mm implant placed in the mandibular second premolar area was simulated and analyzed. Simulation and analysis were performed with the use of COS-MOS/M software and Pro/Engineer 2001 on a Dual Pentium III 1-GHz computer. Crown designs were as follows: porcelain fused to noble metal crown, porcelain fused to base metal crown, In-Ceram porcelain crown, and IPS Empress 2 porcelain crown. A 300-N vertical force was applied to the centric relation stop points of the crowns. The results of this study indicated that different types of restorative materials play an important role in the amount and distribution of the stresses in the superstructure and the implant. The highest stress values were observed in the IPS Empress 2 porcelain crown design (600 MPa). Porcelain fused to base metal and In-Ceram framework designs transferred less stress to abutment. Type of restorative materials used in implant crown designs are significant factors in the amount and distribution of the stresses on superstructure and implant under functional forces. Porcelain fused to base metal (149 MPa) and In-Ceram (173 MPa) crown designs induced higher von Mises stress values within the framework than porcelain fused to noble metal (108 MPa) and IPS Empress 2 (119 MPa) porcelain crown designs. (c) 2005 Wiley Periodicals, Inc.Öğe Three-dimensional finite element analysis of the effect of different bone quality on stress distribution in an implant-supported crown(MOSBY-ELSEVIER, 2005) Sevimay, M; Turhan, F; Kilicarslan, MA; Eskitascioglu, GStatement of problem. Primary implant stability and bone density arc variables that arc considered essential to achieve predictable osscointegration and long-term clinical survival of implants. Information about the influence of bone quality on stress distribution in an implant-supported crown is limited. Purpose. The purpose of this study was to investigate the effect of 4 different bone qualities on stress distribution in an implant-supported mandibular crown, using 3-dimensional (3-D) finite element (FE) analysis. Material and methods. A 3-D FE model of a mandibular section of bone with a missing second premolar tooth was developed, and an implant to receive a crown was developed. A solid 4.1 x 10-mm screw-type dental implant system (ITI; solid implant) and a metal-ceramic crown using Co-Cr (Wiron 99) and feldspathic porcelain were modeled. The model was developed with FE software (Pro/Engineer 2000i program), and 4 types of bone quality (D1, D2, D3, and D4) were prepared. A load of 300 N was applied in a vertical direction to the buccal cusp and distal fossa of the crowns. Optimal bone quality for an implant-supported crown was evaluated. Results. The results demonstrated that von Mises stresses in D3 and D4 bone quality were163 MPa and 180 MPa, respectively, and reached the highest values at the neck of the implant. The von Mises stress values in D1 and D2 bone quality were 150 MPa and 152 MPa, respectively, at the neck of the implant. A more homogenous stress distribution was seen in the entire bone. Conclusion. For the bone qualities investigated, stress concentrations in compact bone followed the same distributions as in the D3 bone model, but because the trabecular bone was weaker and less resistant to deformation than the other bone qualities modeled, the stress magnitudes were greatest for D3 and D4 bone.
