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Three-dimensional finite element analysis of two angled narrow-diameter implant designs for an all-on-4 prosthesis
Edmundo José Moreira de Melo1, Carlos Eduardo Francischone2
1Doctoral candidate, School of Dentistry, São Leopoldo Mandic (SLMANDIC), Campinas, Brazil.
Statement Of Problem:
Although the concept of angulated dental implants has been used for the rehabilitation of the completely edentulous maxilla, its use has yet to be validated with narrow-diameter implants. Proper estimation of narrow-diameter implant dimensions and angulations is essential for the correct use of these implants.
Purpose:
The purpose of this 3D finite element analysis study was to compare the stress levels and distributions of 2 narrow-diameter angled implant arrangements supporting a maxillary fixed complete prosthesis.
Material And Methods:
Two commercially available narrow-diameter implants (3.5×11.5 mm, Unitite Prime; 2.9×11.5 mm, Unitite Slim) were compared for their performances under axial and oblique loading (masticatory force: 100 N) in simulated situations of all-on-4 treatment (2 parallel anterior implants perpendicular to the bone crest and 2 posterior implants angled at 30 degrees). An edentulous maxilla model generated from computed tomography and a prosthesis parametric computer-aided design (CAD) model were combined with computational models of implants and prosthetic components to represent implant-supported maxillary fixed complete prostheses. A condition of complete osseointegration was assumed. Peri-implant bone was analyzed by the Mohr-Coulomb criterion. Implants, abutments, and screws were analyzed by the von Mises criterion, and frameworks by the Rankine criterion.
Results:
The 3.5-mm model showed higher axial load values for peri-implant bone, implants, and abutments than the 2.9-mm model. As for oblique load, values were higher for right-sided peri-implant bone, implants, abutments, and frameworks in the 3.5-mm model than in the 2.9-mm model. The 3.5-mm model had a 16% lower risk of peri-implant bone loss for the axial load and 4% for the oblique load.
Conclusions:
The biomechanical behavior of an angled 2.9-mm implant was comparable with that of a 3.5-mm implant for an all-on-4 prosthesis. However, despite a lower risk of peri-implant bone loss, the 3.5-mm model had higher peak stress on implants and abutments than the 2.9-mm model.
