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Published on: January 28, 2020
Effect of solid abutment diameter and implant placement depth on stress distribution in the posterior mandible: A
Gabriela Ayres1, Ana Paula Macedo1, Beatriz Roque Kubata1
1Department of Dental Materials and Prosthesis, School of Dentistry of Ribeirão Preto, University of São Paulo (USP), São Paulo, SP, Brazil.
Statement Of Problem:
Narrow diameter implants have been considered effective for implant placement in anterior region of maxilla and mandible. However, in regions with heavy masticatory loads, narrow implants may be excessively stressed.
Purpose:
The purpose of this finite element analysis study was to evaluate the stress generated by narrow implants placed level with and below the bone margin in the posterior mandible and the biomechanical effects of different solid abutment diameters.
Material And Methods:
Four 3-dimensional models of an implant-supported prosthesis were simulated in the mandibular bone section of the first molar region. The implants were placed level with and below the bone margin, differing in the gingival height of the prosthetic abutments and testing different abutment diameters. The occlusal force of 365 N was simulated both axially and obliquely to represent medium-intensity physiological loads. Equivalent von Mises stresses were evaluated in the implant-to-abutment connection, and maximum and minimum principal stresses were evaluated in the surrounding bone.
Results:
For the implant-abutment interface, under axial loading, stress values decreased by approximately 19 % with increasing abutment diameter. For the surrounding bone under axial loads, tensile stress values increased with subcrestal implant placement, averaging 32.8 MPa for cortical bone and 18.5 MPa for trabecular bone. Conversely, compressive stress in cortical bone decreased by an average of 76.2 MPa with subcrestal implant placement. Regarding the change in abutment diameter, there were no major variations in the stress values of the surrounding bone. With oblique loading, all stresses were considerably higher than with axial loading.
Conclusions:
Although subcrestal implants showed higher stress values, stresses in the bone crest area decreased. Larger diameter abutments tended to generate better stress distribution for posterior prostheses.
