Mechanical response of different frameworks for maxillary all-on-four implant-supported fixed dental prosthesis: 3D finite element analysis.

Abstract

This study's purpose is to assess the stress distribution in the peri-implant bone, implants, and prosthetic framework using two different posterior implant angles. All-on-four maxillary prostheses fabricated from feldspathic-ceramic-veneeredzirconia-reinforced lithium silicate (ZLS) and feldspathic-ceramic-veneeredcobalt-chromium (CoCr) were designed with17 or 30-degree-angled posterior implants. Posterior cantilever and frontal vertical loads were applied to all models. The distribution of maximum and minimum principal stresses (σmax and σmin) and von Mises stress (σVM) wasevaluated. Under posterior cantilever load, with an increase in posterior implant angle, σmax decreased by 4 and 7MPa in the cortical bone when ZLS and CoCr were used as a prosthetic framework, respectively. Regardless of the framework material, 17-degree-angled posterior implants showed the highest σVM (541.36MPa under posterior cantilever load; 110.79MPa under frontal vertical load) values. Regardless of the posterior implant angle, ZLS framework showed the highest σVM (91.59MPa under posterior cantilever load; 218.99MPa under frontal vertical load) values. Increasing implant angle from 17 to 30° caused a decrease in σmax values in the cortical bone. Designs with 30-degree posterior implant angles and ZLS framework material may be preferred in All-on-four implant-supported fixed complete dentures.