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Öğe The effect of fibre insertion on fracture resistance of root filled molar teeth with MOD preparations restored with composite(WILEY, 2005) Belli, S; Erdemir, A; Ozcopur, M; Eskitascioglu, GAim To evaluate the effect of using flowable composite with or without leno woven ultra high modulus polyethylene fibre reinforcement on fracture resistance of root filled mandibular molars with mesio-occluso-distal (MOD) preparations. Methodology Sixty sound extracted human mandibular molars were randomly assigned to five groups (n = 12). Group 1 did not receive any preparation. From groups 2 to 5, the teeth were root filled and MOD preparations were created. Group 2 remained unrestored. Group 3 was restored with a dentine bonding system (DBS; SE Bond, Kuraray, Japan) and composite resin (CR) (AP-X; Kuraray). In group 4, flowable composite resin (Protect Liner F; Kuraray) was used before restoring teeth with CR. In group 5, leno woven ultra high modulus polyethylene ribbon fibre (Ribbond, Seattle, WA, USA) was inserted into the cavities in a buccal to lingual direction and the teeth were then restored with DBS and CR. After finishing and polishing, the specimens were stored in 100% humidity at 37 degreesC for 1 day. Compressive loading of the teeth was performed using a universal testing machine at a crosshead speed of 0.5 mm min(-1). The mean load necessary to fracture the samples were recorded in newtons (N) and were subjected to analysis of variance (anova) and Tukey post-hoc test. Results The mean load necessary to fracture the samples in each group were (in N): group 1: 1676.75 +/-154.63(a), group 2: 376.51 +/- 37.36(b), group 3: 733.23 +/- 133.33(c), group 4: 786.48 +/- 145.34(c), group 5: 943.63 +/- 121.15(d). There were statistically significant differences between the groups annotated with different letters. Conclusions (i) Use of flowable composite resin under composite restorations had no effect on fracture resistance of root filled molar teeth with MOD preparations, (ii) use of polyethylene ribbon fibre under composite restorations in root filled teeth with MOD preparations significantly increased fracture strength.Öğe Effect of hybrid layer on stress distribution in a premolar tooth restored with composite or ceramic inlay: An FEM study(WILEY-LISS, 2005) Belli, S; Eskitascioglu, G; Eraslan, O; Ssenawongse, P; Tagami, JThe aim of this finite elemental stress analysis study was to evaluate the effect of hybrid layer on distribution and amount of stress formed under occlusal loading in a premolar tooth restored with composite or ceramic inlay. The mandibular premolar tooth was selected as the model based on the anatomical measurements suggested by Wheeler. The analysis is performed by using a Pentium II IBM compatible computer with the SAP 2000 structural analysis program. Four different mathematical models including the following structures were evaluated: 1) composite inlay, adhesive resin, and tooth structure; 2) composite inlay, adhesive resin, hybrid layer, and tooth structure; 3) ceramic inlay, adhesive resin, and tooth structure; 4) ceramic inlay, adhesive resin, hybrid layer, and tooth structure. Loading was applied from the occlusal surface of the restoration, and shear stresses under loading were evaluated. The findings were drawn by the Saplot program, and the results were analyzed by graphical comparison method. The output indicated that the hybrid layer acts as a stress absorber in models 2 and 4. The hybrid layer has also changed mathematical values of stress on cavity floors in both restoration types. Ceramic inlay collected the stress inside the body of the material, but the composite inlay directly transferred the stress through dental tissues. As a result, it was concluded that the hybrid layer has an effect on stress distribution under loading in a premolar tooth model restored with composite or ceramic inlay. (c) 2005 Wiley Periodicals, Inc.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 Evaluation of vertical forces created with finite element stress analysis on periodontal defects.(AMER ASSOC DENTAL RESEARCH, 1999) Eskitascioglu, G; Unsal, E; Ozgey, S; Unsal, MK[Abstract not Available]Öğe Finite element analysis of stress distribution of 2 different tooth preparation designs in porcelain-fused-to-metal crowns(QUINTESSENCE PUBLISHING CO INC, 2006) Oyar, P; Ulusoy, M; Eskitascioglu, GPurpose: The aim of this clinical simulation study was to investigate the effect of anatomic and nonanatomic occlusal preparation design on stress distribution in different metal-ceramic crowns and tooth and bone. Materials and Methods: For the finite element analysis method, a 2-dimensional mathematical model of a mandibular second premolar tooth and its supporting tissues was used. The analysis was performed by using a structural analysis program. Four groups were designed: gold-palladium alloy/anatomic occlusal preparation (Au-Pd/A), Au-Pd alloy/nonanatomic (flat) occlusal preparation (Au-Pd/N), nickel-chromium alloy/anatomic occlusal preparation (Ni-Cr/A), and Ni-Cr alloy/nonanatomic occlusal preparation (Ni-Cr/N). A distributed type load of 400 N (total) was applied to the centric stop points on the tip of the buccal cusp and on the central developmental groove in centric occlusion to all types of restorations. Results: The results demonstrated that shear stresses in the dentin tissues and restorations in Au-Pd/A and Ni-Cr/A were similar. The shear stresses within the restorations in Au-Pd/N and Ni-Cr/N were similar. Conclusion: Anatomic occlusal preparation designs were advantageous in stress distribution in the dentin tissue. Nonanatomic occlusal preparation designs were found to be advantageous in the stress amount and distribution in the porcelain structure. Occlusal preparation designs and restorative materials showed no differences in stress distribution and amount in the pulp tissue and bone tissues.Öğe The in vitro effect of pulpal pressure and luting agent on tensile bond strength of complete cast crowns(MOSBY-ELSEVIER, 2004) Ozturk, AN; Belli, S; Eskitascioglu, GStatement of problem. The degree to which pulpal pressure may affect bond strength of complete cast crowns is unknown. Purpose. The aim of this in vitro study was to evaluate the effect of simulated pulpal pressure on the tensile bond strength of complete cast crowns luted with 2 different cements. Material and methods. Forty-eight human mandibular canine teeth were cleaned and stored in saline solution. The crowns were prepared by I investigator, and standardization of the preparation was accomplished by fixing a dental handpiece in a parallelometer. Uniform grooves, 0.5 mm in depth, were prepared with burs with depth guides. The complete crowns were prepared with a 0.5-mm shoulder margin. Teeth were randomly divided into 2 groups of 24 teeth each (Group I and Group 11). In Group 1, bonding and tensile test procedures of the teeth were carried out under simulated pulpal pressure (15 cm of saline solution). In Group 11, simulated pulpal pressure was not used. The roots were removed I mm below the cementoenamel junction to create direct communication with the pulp chamber. The remaining pulpal tissues were carefully removed, and crowns were embedded in acrylic resin. The acrylic resin was then penetrated by a stainless steel tube that connected the pulp chamber and the barrel of a disposable plastic 5-ml syringe. The pulp chambers were filled with physiological saline solution under elevated pressure to locate the area of greatest permeability on the dentinal surface. Crowns were cast (Co-Cr alloy) with a 20-mm bar to allow testing of the bond strength. Each of the 2 groups were further divided into 2 luting cement groups of 12 each (Group 1, A and 13, and Group 11, A and B). Group IA/IIA and Group IB/IIB specimens were luted with a polycarboxylate luting cement (Poly-F Plus) and an adhesive luting cement (Superbond C&B), respectively. After storage in distilled water for 24 hours, all specimens were subjected to a tensile bond test in a universal testing machine at a crosshead speed of 0.5 mm/min until failure. The maximum load at fracture (Newton) was recorded. The results were then evaluated with 2-way analysis of variance and Tukey's honestly significant difference tests (alpha = .05). Results. Simulated pulpal pressure increased the bond strength of cast complete crowns cemented with all adhesive luting agent (P = .01). No significant difference was found in the bond strength of complete cast crowns cemented with polycarboxylate cement with or without pupal pressure. Superbond C&B adhesive luting agent showed significantly higher bond strength values for Group 1 (388.9 +/- 32.7) and Group 11 (300.9 +/- 66.8), when compared with polycarboxylate cement for Group 1 (221.3 +/- 17.3) and Group 11 (186.8 +/- 38.5) (P = .001). Conclusion. Simulated pulpal pressure had a positive effect on the retention of complete cast crowns when cemented with Superbond C&B adhesive luting agent. Superbond C&B significantly increased the retention of crowns in either the presence or absence of pulpal pressure.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 Microleakage of endodontically treated teeth with different dowel systems(MOSBY-ELSEVIER, 2004) Usumez, A; Cobankara, FK; Ozturk, N; Eskitascioglu, G; Belli, SStatement of problem. Several new esthetic dowel systems are available for the restoration of endodontically treated teeth, but little is known about how effectively these dowels seal the restored teeth. Purpose. The purpose of this in vitro study was to compare microleakage of 3 esthetic, adhesively luted dowel systems with a conventional dowel system. Material and methods. The root canals of 41 human intact single-rooted extracted teeth were prepared using a step-back technique. The teeth were randomly divided into 4 experimental groups (n=10), and I tooth served as a positive control. The decoronated roots were obturated with gutta-percha using lateral condensation. Roots were restored with I of the following dowel systems according to the manufacturer's instructions: (1) stainless steel dowels (ParaPost), (2) glass fiber dowels (Snowpost), (3) resin-supported polyethylene fiber (Ribbond) dowels, or (4) zirconia dowels (Cosmopost). Using a fluid filtration method, coronal leakage of the specimens along the dowel space and root canal restorative material was measured. Fluid movement measurements were made at 2-minute intervals for 8 minutes to measure the presence of voids existing in the obturated canals, at I week, 3 months, and 6 months following dowel insertion. A repeated-measures analysis of variance (ANOVA) was used to analyze logarithmic transformations of data (time and dowel material) for significant differences. The Tukey HSD test and paired 2-tailed tests were used to perform multiple comparisons (alpha=.05). Results. The data indicated that the leakage values varied according to the dowel system used (P<.01). There was significant interaction between dowel systems and time of testing (P<.01). The sealing ability of zirconia dowels decreased over time (P<.01), but sealing abilities of stainless steel and resin-supported polyethylene fiber dowels remained constant (P>.05). The sealing ability of glass fiber dowels increased at 3 months (P=.032) and remained constant over the next 3 months (P=.758). Statistically, resin-supported polyethylene fiber and glass fiber dowels showed the lowest coronal leakage when compared with stainless steel and zirconia dowels at all time periods (P<.01). There were no significant differences between resin-supported polyethylene fiber and glass fiber dowels at any time period. The initial leakage measurement in zirconia dowel and stainless steel dowels were similar (P=.914), but became significantly different at 3 and 6 months (P<.01). Conclusion. Resin-supported polyethylene fiber dowels and glass fiber dowels tested exhibited less microleakage compared to zirconia dowel systems. The latter system should be further evaluated because of its unacceptable level of leakage.Öğe Nasal prosthesis rehabilitation: A case report(QUINTESSENCE PUBLISHING CO INC, 2004) Gurbuz, A; Kalkan, M; Ozturk, AN; Eskitascioglu, GA nasal prosthesis can reestablish esthetic form and anatomic contours for midfacial defects often more effectively than can surgical reconstruction. This case report describes the clinical and laboratory procedures for fabricating a nasal prosthesis.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.Öğe Three-dimensional finite-element analysis of functional stresses in different bone locations produced by implants placed in the maxillary posterior region of the sinus floor(MOSBY-ELSEVIER, 2005) Koca, OL; Eskitascioglu, G; Usumez, AStatement of problem. Implants placed in the posterior maxilla have lower success rates compared to implants placed in other oral regions. Inadequate bone levels have been suggested as a reason for this differential success rate. Purpose. The purpose of this study was to determine the amount and localization of functional stresses in implants and adjacent bone locations when the implants were placed in the posterior maxilla in proximity to the sinus using finite element analysis (FEA). Material and methods. A 3-dimensional finite element model of a maxillary posterior section of bone (Type 3) was used in this study. Different bony dimensions were generated to perform nonlinear calculations. A singlepiece 4.1 x 10-mm screw-shaped dental implant system (ITI solid implant) was modeled and inserted into atrophic maxillary models with crestal bone heights of 4, 5, 7, 10, or 13 rum. In some models the implant penetrated the sinus floor. Cobalt-Chromium (Wiron 99) was used as the crown framework material placed onto the implant, and porcelain was used for occlusal surface of the crown. A total average occlusal force (vertical load) of 300 N was applied at the palatal Cusp (150 N) and mesial fossa (150 N) of the crown. The implant and superstructure were simulated in finite element software (Pro/Engineer 2000i program). Results. For the porcelain Superstructure for bone levels, maximum von Mises stress values were observed on the mesial fossae and palatal cusp. For the bone structure, the maximum von Mises stress values were observed in the palatal cortical bone adjacent to the implant neck. There was no stress within the spongy bone. High stresses occurred within the implants for all bone levels. Conclusion. The maximum von Mises stresses in the implants were localized in the neck of implants for 4- and 5-mm bone levels, but for 7-, 10-, and 13-mm bone levels more even stresses occurred within the implants.Öğe Use of polyethylene ribbon to create a provisional fixed partial denture after immediate implant placement: A clinical report(MOSBY-ELSEVIER, 2004) Eskitascioglu, G; Eskitascioglu, A; Belli, SProvisional restorations are generally necessary to restore lost function and esthetics during the implant integration period. This article describes the fabrication of an esthetic, economic, and conservative bonded provisional fixed partial denture for a patient restored with implants. A reinforcing polyethylene ribbon was used to bond the natural lateral incisors to the adjacent teeth. An acceptable esthetic outcome was obtained, and the result was satisfactory to the patient.
