Effects of implant diameter, implant-abutment connection type, and bone density on the biomechanical stability of implant components and bone: A finite element analysis study.

Statement Of Problem: Various kinds of implants of different diameters and connection types are used for patients with a range of bone densities and tooth sizes. However, comprehensive studies simultaneously analyzing the biomechanical effects of different diameters, connection types, and bone densities are scarce.

Purpose: The purpose of this 3-dimensional finite element analysis study was to evaluate the stress and strain distribution on implants, abutments, and surrounding bones depending on different diameters, connection types, and bone densities.

Material And Methods: Twelve 3-dimensional models of the implant, restoration, and surrounding bone were simulated in the mandibular first molar region, including 2 bone densities (low, high), 2 implant-abutment connection types (internal tissue level, internal bone level), and 3 implant diameters (3.5 mm, 4.0 mm, and 4.5 mm). The occlusal force was 200 N axially and 100 N obliquely. Statistical analysis was performed using the general linear model univariate procedure with partial eta squared (η) (α=.05).

Results: For bone tissue, low-density bone induced a larger maximum and minimum principal strain (in magnitude) than high-density bone (P<.001). As the implant diameter increased, the volume of the cancellous bone in low-density bone at the atrophy region (strain<200 με) increased (P<.001). For implant and abutment, the internal bone-level connection type was associated with increased peak stress as compared with the tissue-level connection type (P<.001). For all models, the stress distribution on the implant complex was influenced by implant diameter (P<.001): a decrease in implant diameter increased the stress concentration.

Conclusions: The implant connection type had a greater impact on the stress of the implant and abutment than the diameter. A tissue-level connection was more advantageous than a bone-level connection in terms of stress distribution of the implant and abutment. Bone density was the most influential factor on bone strain. The selection of dental implants should be made considering these factors and other important factors including tooth size.