Impact of peri-implant bone resorption, prosthetic materials, and crown to implant ratio on the stress distribution of short implants: a finite element analysis
Medical & Biological Engineering & Computing. 2021;59(4):813-824.
ABSTRACT
The purpose of this study was to determine the effects of prosthetic materials and crown/implant (C/I) ratio on short implants with a marginal bone resorption. Three-dimensional finite element analysis was used to simulate stress distribution under static loading in non-resorption and resorption scenarios (3-mm vertical bone loss) in implants restored with single crowns and C/I ratios of 1:1, 1.5:1, and 2:1 were evaluated. Different crown materials were used: porcelain-fused to metal, porcelain-fused to zirconia, monolithic zirconia, and zirconia-based crown veneered with indirect composite resin. The C/I ratio, the peri-implant bone resorption, and the loading conditions were the key factors affecting the generated stress in short implants. In non-resorption models, von Mises stress ranged between 50 and 105 MPa whereas in resorption models, the values ranged from 168 to 322 MPa, both increasing with the higher C/I ratio under oblique forces. Under axial loading, the C/I ratio did not influence the stress values as the presence of resorption was the only parameter increasing, 57 MPa for the non-resorption models and 101 MPa for the resorption models, respectively. Preference of a prosthetic material was ineffective on the distribution of stress in the bone and implant structure under static loading in any models. The peri-implant bone resorption and a higher C/I ratio in short implants increase the stress values under both axial and oblique forces, whereas the crown material does not influence stress distribution in the surrounding bone and implant structure.
KEYWORDS
Dental implants · Implant prosthesis · Crown restoration · Bone resorption · Finite element analysis
STUDY SUMMARY
This three-dimensional finite element study modelled stress distribution around short dental implants under static loading, comparing three crown-to-implant ratios, four crown materials and models with and without 3 mm of peri-implant bone resorption. Simulated von Mises stress was higher in the resorption models and increased with a higher crown-to-implant ratio under oblique loading, while under axial loading only the presence of resorption raised stress values. The crown material did not affect stress distribution in any model; the results come from computer simulation rather than from clinical or laboratory measurement.