FEM studies were made on a zirconia dental bridge of 4 elements with supports on 2.4 and 2.7, and edentation on 2.5 and 2.6. Appling a compressive force of 350N on Z direction, quite normal for mastication, was analyzed the behavior of the dental bridge. Zirconia, although having a high mechanical strength, is fragile when rotation or bending movements occur. The analysis reveals some bridge deficiencies, which may be due either to inaccuracies in the prosthetic abutment construction (especially in relation to their inclination), to the technique of realization or to insufficient dental support. In our study, the most vulnerable elements are the crowns on teeth 2.4 and 2.7. Finite element analysis, highlighting possible structural and design deficiencies, may be a solution to improve dental bridges. The only disadvantage of the finite element analysis that was performed before the actual restoration is related to the fact that performing the simulations involves a time-consuming phase.

In order to increase the patient�s quality of life, interdisciplinary studies on dental materials are becoming more and more frequent in an attempt to assess as accurately as possible the resistance of dental restorations over time. One of the methods of analysis of resistance to the masticatory forces of dental restorations is the finite element method (FEM). We studied a 3-element dental bridge made of a metallic Co-Cr-Mo alloy and dental ceramics, designed for the prosthesis of a tooth 3.6. On each element of the dental bridge we applied a force of 250 N in the direction Z and a force of 100 N in the Y direction. The most vulnerable areas, where the highest stresses occur, are located predominantly in the neck regions and around the points of contact between the elements of the dental bridge. However, the experimentally determined values have low intensities that would not endanger the resistance of the restoration unless it is overloaded.

Canine edentulous raises numerous aesthetic and functional problems, and rehabilitation with implant support require special attention during occlusal equilibration due to forces developed at this level. In this paper, we present a case of edentation of 23, prosthesis with a metal-ceramic crowns cemented on a dental implant. Because residual bone crest present inadequate size for implantation, we used an autograft of chin covered by a PRF membrane prior insertion of the implant.

Objectives. In this study we evaluated corrosion resistance of three types of metal alloys (two NiCr and one CoCr). Methods. Samples (coded A, B, C) of circular shape, with dimensions 13 x 1.5 mm, sanded and polished, were introduced in Fusayama Meyer artificial saliva at pH 5.2 and 37 ± 0.5°C and tested in terms of corrosion resistance with a potentiostat/galvanostat (model 4000 PARSTAT, Princeton Applied Research). Results. Open circuit potential EOC [mV] ranged between 21.316 and 5.75. Corrosion potential Ecor [mV] was between -73.536 and -395.662, and the corrosion current density icor [A/cm2] was between 1.237 x 10-6 and 905.13 x 10-9. Conclusion. The best corrosion behavior in Fusayama Meyer artificial saliva at pH 5.2 and at a temperature of 37 ± 0.5°C is the alloy A, followed by the alloy C.

Aim of the study was the comparative analysis of the experimental dilation of some materials used in the fabrication of physiognomic fixed prosthetic restorations. Material and methods. 3 biomaterials used in the fabrication of physiognomic fixed prosthetic restorations, pressed ceramic IPS e.max Press Ivoclar Vivadent, WhitePeaks Copra Smile (ZrO2, 600 MPa) and WhitePeaks Copra Supreme (ZrO2, 1100 MPa) were comparatively analyzed. The temperature increase was carried out from 20OC to 400OC, with the speed of 2 degrees/minute in a dilatometer. The repetition of the heating was done 2 times, with a 30-minute break between attempts. Results. The smallest expansion occurred for the e.max sample, followed by Zr600 and Zr1100. Conclusions. The present study demonstrated the production of a thermal expansion at the level of pressed ceramics and biomaterials based on zirconium dioxide upon experimental heating in the range of 20-400OC in dilatometer. Subjecting pressed ceramic or zirconium dioxide prosthetic restorations to high temperatures during the clinical-technical phases of occlusal processing/adaptation without adequate cooling may introduce residual thermal stresses into the material structure, which may subsequently lead to cracking of the prosthetic restorations under stress conditions determined by masticatory forces.