Comparison of different designs of implant-retained overdentures and fixed full-arch implant-supported prosthesis on stress distribution in edentulous mandible – A computed tomography-based three-dimensional finite element analysis

Abstract

A finite element analysis was used to compare the effect of different designs of implant-retained overdentures and fixed full-arch implant-supported prosthesis on stress distribution in edentulous mandible. Four models of an human mandible were constructed. In the OR (O'ring) group, the mandible was restored with an overdenture retained by four unsplinted implants with O'ring attachment; in the BC (bar-clip) -C and BC groups, the mandibles were restored with overdentures retained by four splinted implants with bar-clip anchor associated or not with two distally placed cantilevers, respectively; in the FD (fixed denture) group, the mandible was restored with a fixed full-arch four-implant-supported prosthesis. Models were supported by the masticatory muscles and temporomandibular joints. A 100-N oblique load was applied on the left first molar. Von Mises (σvM), maximum (σmax) and minimum (σmin) principal stresses (in MPa) analyses were obtained. BC-C group exhibited the highest stress values (σvM=398.8, σmax=580.5 and σmin=-455.2) while FD group showed the lowest one (σvM=128.9, σmax=185.9 and σmin=-172.1). Within overdenture groups, the use of unsplinted implants reduced the stress level in the implant/prosthetic components (59.4% for σvM, 66.2% for σmax and 57.7% for σmin versus BC-C group) and supporting tissues (maximum stress reduction of 72% and 79.5% for σmax, and 15.7% and 85.7% for σmin on the cortical and trabecular bones, respectively). Cortical bone exhibited greater stress concentration than the trabecular bone for all groups. The use of fixed implant dentures and removable dentures retained by unsplinted implants to rehabilitate edentulous mandible reduced the stresses in the periimplant bone tissue, mucosa and implant/prosthetic components.

Biomechanical influence of crown-to-implant ratio on stress distribution over internal hexagon short implant: 3-D finite element analysis with statistical test

“…These limitations are related to the environment of a computer simulation; the material properties were assumed to be linear, isotropic, and homogeneous and are subjected to a static occlusal loading. But bone modeling with anisotropic properties is more upscale and problematic and consumes more time for development (Barão et al, 2013). However, the implants showed a small margin of simplification, approaching the real clinical situation, as in previous studies (de Faria Almeida et al, 2014;Santiago Junior et al, 2013;de Moraes et al, 2013;Moraes et al, 2013).…”

“…The stress maps were plotted for qualitative analysis. Von Mises analysis was used to evaluate the stress distribution in the implant, retaining-screw, and crown; von Mises interpretation is adequate for analysis of ductile material (Barão et al, 2013). A high stress concentration should reveal the probability of failure (Spazzin et al, 2013).…”

Stress analysis in oral obturator prostheses over parallel and tilted implants: photoelastic imaging

“…Also, according to Barão et al, 20 this greater movement requires the attachment system in a more critical way. Furthermore, the unilateral load is clinically relevant because it simulates the first phase of chewing, wherein the food stuff is placed in the prosthesis's working side and no contact occurs in the nonworking side.…”

Impact of fixed implant supported prostheses in edentulous patients: protocol for a systematic review

“…Selection of which type depends on the patient bone volume and soft tissue conditions7 in addition to economic factors and treatment cost. Fixed full arch implant supported prostheses may be either screw or cement retained and are indicated in the presence of enough bone and inter-arch space 6. Clinical factors that may prohibit a fixed restoration are mostly related to bone or soft tissues deficiencies.…”