Avaliação do comportamento biomecânico de diferentes tipos de abutments instalados sobre implantes

Abstract

Oral rehabilitation with prostheses on implants can be the ideal choice to replace a lost tooth. The success of this treatment depends not only on osseointegration but also on selecting the right abutment-implant combination. The development of materials with improved biomechanical and aesthetic properties is on the rise, along with a wide range of prosthetic components. Therefore, it's crucial to study the causes of technical complications related to the abutment-implant assembly. This thesis has three objectives: 1- evaluate the mechanical behavior of two-piece abutments (16º internal angle Morse Cone and 11.5º internal angle Morse Cone) before and after cyclic fatigue testing, following ISO 14801:2016 guidelines. 2- Assess mechanical stress distributions in three types of abutments with different restorative materials on 16º conical implants. 3- Describe a clinical case illustrating the single rehabilitation of two upper central incisors with 16º conical implants, immediate loading, and maintenance of prosthetic and peri-implant space. After analyzing the data from the first study, significant differences were found between the three groups in the loosening test when comparing values with and without fatigue (p < 0.001) within each group. When comparing the groups, there were also significant differences between them (p < 0.001), except between the GM and CMt groups without fatigue (p = 0.840). In the pull-out test of the CMt group, frictional locking occurred only after fatigue (average = 94.2 N). Finite Element Analysis (FEA) showed varied stress distribution in all groups. Stress was concentrated in the upper and middle third regions of the implant, as well as in the opposite region of load application for all three groups. Although the CMo group had lower loosening rates, it exhibited worse stress distribution compared to the GM and CMt groups. On the other hand, the CMt group showed satisfactory frictional locking after passing fatigue tests. In the second study, high stresses were observed in the superficial threads of implant fixation in all groups, with the best stresses seen in groups 1 and 3. Comparing the groups, biomechanical differences could be evaluated. The maximum supported stresses were better distributed in Group 1, but when evaluating screw thread stress, Group 1 showed the worst result. In the third study, initial planning combined with the correct choice of abutment-implant assembly and new technologies allow for stable and functional final restorations.