Cortical bone stress distribution in mandibles with different configurations restored with prefabricated bar-prosthesis protocol: a three-dimensional finite-element analysis.

摘要

PURPOSE: To evaluate stress distribution in different horizontal mandibular arch formats restored by protocol-type prostheses using three-dimensional finite element analysis (3D-FEA). MATERIALS AND METHODS: A representative model (M) of a completely edentulous mandible restored with a prefabricated bar using four interforaminal implants was created using SolidWorks 2010 software (Inovart, Sao Paulo, Brazil) and analyzed by Ansys Workbench 10.0 (Swanson Analysis Inc., Houston, PA) to obtain the stress fields. Three mandibular arch sizes were considered for analysis, regular (M), small (MS), and large (ML). Three unilateral posterior loads (L) (150 N) were used: perpendicular to the prefabricated bar (L1); 30 degrees oblique in a buccolingual direction (L2); 30 degrees oblique in a lingual-buccal direction (L3). The maximum and minimum principal stresses (sigma(max), sigma(min)), the equivalent von Mises (sigma(vM)), and the maximum principal strain (sigma(max) ) were obtained for type I (M.I) and type II (M.II) cortical bones. RESULTS: Tensile stress was more evident than compression stress in type I and II bone; however, type II bone showed lower stress values. The L2 condition showed highest values for all parameters (sigma(vM), sigma(max), sigma(min), varepsilon(max)). The sigma(vM) was highest for the large and small mandibular arches. CONCLUSION: The large arch model had a higher influence on sigma(max) values than did the other formats, mainly for type I bone. Vertical and buccolingual loads showed considerable influence on both sigma(max) and sigma(min) stresses.