Search

This study evaluated the influence of cross-section geometry of the bar framework on the distribution of static stresses in an overdenture-retaining bar system simulating horizontal misfit and bone loss. Three-dimensional FE models were created including two titanium implants and three cross-section geometries (circular, ovoid or Hader) of bar framework placed in the anterior part of a severely resorbed jaw. One model with 1.4-mm vertical loss of the peri-implant tissue was also created. The models set were exported to mechanical simulation software, where horizontal displacement (10, 50 or 100 μm) was applied simulating the settling of the framework, which suffered shrinkage during the laboratory procedures. The bar material used for the bar framework was a cobalt--chromium alloy. For evaluation of bone loss effect, only the 50-μm horizontal misfit was simulated. Data were qualitatively and quantitatively evaluated using von Mises stress for the mechanical part and maximum principal stress and μ-strain for peri-implant bone tissue given by the software. Stresses were concentrated along the bar and in the join between the bar and cylinder. In the peri-implant bone tissue, the μ-strain was higher in the cervical third. Higher stress levels and μ-strain were found for the models using the Hader bar. The bone loss simulated presented considerable increase on maximum principal stresses and μ-strain in the peri-implant bone tissue. In addition, for the amplification of the horizontal misfit, the higher complexity of the bar cross-section geometry and bone loss increases the levels of static stresses in the peri-implant bone tissue., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Purpose: To evaluate the influence of different metallic flask systems for acrylic resin denture processing on tooth displacement and framework misfit of mandibular fixed implant-supported complete dentures., Methods: Standard mandibular implant-supported complete dentures in five implants were waxed and randomly assigned to three groups: G1 - conventional flask, G2 - double flask, and G3 - occlusion flask. Framework misfit in all the implants and the linear distances between teeth (I-I - incisor-to-incisor; P-P - premolar-to-premolar; M-M - molar-to-molar; RI-RM - right-incisor-to-right-molar; and LI-LM - left-incisor-to-left-molar) were measured before and after denture processing using an optical microscope. Dentures were processed by hot water curing cycle (9h/74°C). Collected data were analyzed by paired Student's t-test and one-way ANOVA (α=0.05)., Results: All the measured distances presented changes in tooth displacement after denture processing. However, the M-M distance for G1 (p=0.003) and the P-P (p=0.042) and LI-LM (p=0.044) distances for G3 showed statistically significant differences. Differences between the flask systems were not statistically significant. Statistically significant differences in the framework misfit due to denture processing were found for all the implants and groups, with the exception of right median implant for G2 and right distal implant for G3. A comparison of the flask systems found statistically significant differences in which G1 presented an increase in the misfit values and G2 and G3 a decrease., Conclusions: Different flask systems did not cause significant changes in tooth displacement. Frameworks misfit values were influenced by the different flask systems. The conventional flask presented an increase in the framework misfit, while the experimental flasks showed a decrease., (Copyright © 2013 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.)

The masticatory system's ability to function depends on the distribution of occlusal contacts to promote mandibular stabilization. The patient in this case report was experiencing temporomandibular dysfunction, which was treated by creating an adequate bite plane using indirect composite resin restorations (overlays) made from a wax-up. This therapy made it possible to improve esthetics as well as centric and excursive mandibular occlusion without the need for drilling.