Three-dimensional finite element analysis of buccally cantilevered implant-supported prostheses in a severely resorbed mandible

Abstract

PURPOSE The aim of the study was to compare the lingualized implant placement creating a buccal cantilever with prosthetic-driven implant placement exhibiting excessive crown-to-implant ratio. MATERIALS AND METHODS Based on patient's CT scan data, two finite element models were created. Both models were composed of the severely resorbed posterior mandible with first premolar and second molar and missing second premolar and first molar, a two-unit prosthesis supported by two implants. The differences were in implants position and crown-to-implant ratio; lingualized implants creating lingually overcontoured prosthesis (Model CP2) and prosthetic-driven implants creatingan excessive crown-to-implant ratio (Model PD2). A screw preload of 466.4 N and a buccal occlusal load of 262 N were applied. The contacts between the implant components were set to a frictional contact with a friction coefficient of 0.3. The maximum von Mises stress and strain and maximum equivalent plastic strain were analyzed and compared, as well as volumes of the materials under specified stress and strain ranges. RESULTS The results revealed that the highest maximum von Mises stress in each model was 1091 MPa for CP2 and 1085 MPa for PD2. In the cortical bone, CP2 showed a lower peak stress and a similar peak strain. Besides, volume calculation confirmed that CP2 presented lower volumes undergoing stress and strain. The stresses in implant components were slightly lower in value in PD2. However, CP2 exhibited a noticeably higher plastic strain. CONCLUSION Prosthetic-driven implant placement might biomechanically be more advantageous than bone quantity-based implant placement that creates a buccal cantilever.

Stress analysis of a single prosthesis on a poorly positioned implant

“…Uniform distribution in the rest of the abutment body (Figure 3.c). The experimental group showed 875.63 MPa and was 28% greater than the control group (683.88 MPa), a result similar to that of Alom et al (2021), who, when analyzing a buccal cantilever in a single prosthesis, found greater stress in the abutment of the group tested.…”

“…Planning for implant installation is essential, however, often due to anatomical limitations such as pronounced resorption of the maxillae and consequent approximation of important structures such as the maxillary sinus, nasal fossa, mentual foramen and even the inferior alveolar nerve, This procedure aims to simplify planning, thus avoiding extensive surgeries, minimizing costs and morbidity (Alom et al, 2021;da Silva et al, 2018;Manea et al, 2019;Muangsisied et al, 2021).…”