Effects of different ceramic and composite materials on stress distribution in inlay and onlay cavities: 3-D finite element analysis.

To reduce loss of tooth tissue and to improve esthetic results, inlay and onlay restorations are good treatment choices for extensive cavities in posterior teeth. The aim of this paper was to evaluate, by means of three-dimensional finite element analysis, the effects of restorative material and cavity design on stress distribution in the tooth structures and restorative materials. Two different nanofilled composites and two different all-ceramic materials were used in this study. A permanent molar tooth was modeled with enamel and dentin structures. 3-D inlay and onlay cavity designs were created. Von Mises, compressive, and tensile stresses on the restorative materials, core materials, enamel, and dentin were evaluated separately. On the effect of restorative material, results showed that in the case of materials with low elastic moduli, more stress was transferred to the tooth structures. Therefore, compared to the nanofilled composites, the all-ceramic inlay and onlay materials tested transferred less stress to the tooth structures. On the effect of cavity design, the onlay design was more efficacious in protecting the tooth structures than the inlay design.

Stability of zygomatic plate-screw orthodontic anchorage system: a finite element analysis.

OBJECTIVE: To evaluate the biomechanical properties of a standard and a newly designed plate-screw orthodontic anchorage system. MATERIALS AND METHODS: A three-dimensional model of the posterior maxilla, including the zygomatic buttress region, was prepared. Insertion of standard and newly designed plates was simulated on the three-dimensional model. The effect of 200 g of orthodontic force on the plate, screws, and zygomatic bone was evaluated in three-dimensional models by finite element analysis. To determine the force distribution, Von Mises stress, principal maximum and minimum stress, and principal maximum and minimum elastic strain values were evaluated. RESULTS: In all plate models the highest stresses occurred on the threaded bone site where the force application unit was attached. CONCLUSION: Changing the plate configuration did not affect the stress distribution in the newly designed plates. To equalize the force distribution, new plate designs that change the location of the force application unit are required.

Three-dimensional finite element analysis of stress distribution in inlay-restored mandibular first molar under simultaneous thermomechanical loads.

Functional occlusal loads and intraoral temperature changes create stress in teeth. The purpose of this study was to evaluate the impact of simultaneous thermomechanical loads on stress distribution related to inlay restored teeth by three-dimensional finite element analysis. A mandibular first molar was constructed with tooth structures, surrounding bone and inlays of Type II gold alloy, ceramic, and composite resin. Stress patterns on the restorative materials, adhesive resin, enamel and dentin were analyzed after simulated temperature changes from 36°C to 4 or 60°C for 2 s with 200-N oblique loading. The results showed that the three types of inlays had similar stress distribution in the tooth structures and restorative materials. Concerning the adhesive resin, the composite resin inlay model exhibited lower stresses than ceramic and gold alloy inlays. Simultaneous thermomechanical loads caused high stress patterns in inlay-restored teeth. Composite resin inlays may be the better choice to avoid adhesive failure.

The comparison of angular and curvilinear marginal mandibulectomy on force distribution with three dimensional finite element analysis.

AIM: The purpose of this study was to analyse and compare right angled and curved osteotomy design on stress distribution and to determine an osteotomy design which decreases the risk of pathologic fracture. PATIENTS AND METHODS: Solid mathematical model of the mandible was created by three dimensional finite element analysis and two different osteotomy, right angled and curvilinear osteotomy was performed on model. 150 N incisal force vertically and 250 N molar force to the angulus area oblically were applied. The effects of osteotomy types to the stress formation and risk of fracture between models were evaluated. RESULTS: Right angled osteotomy causes much more stress in the posteroinferior quadrant and mainly localized on the horizontal and vertical osteotomy intersection area. On the other hand, the distribution of the stress on curvilinear formed osteotomy shows posteroinferior localization and stress spreads wider area. Furthermore the amount of stress was less than right-angled one. CONCLUSION: In this study, curved osteotomy denominated less stress distribution. The shape of osteotomy might be a factor to decrease the risk of postoperative atrophic mandible fracture.