Biomechanical Evaluation of Subcrestal Placement of Dental Implants: In Vitro and Numerical Analyses

Background: This study investigates the effect of depth of insertion in subcrestal cortical bone (SB) and thickness of connected cortical bone (CB) for a subcrestal implant placement on bone stress and strain using statistical analyses combined with experimental strain-gauge tests and numerical finite element (FE) simulations. Methods: Three experimental, artificial jawbone models and 72 FE models were prepared for evaluation of bone strain and stress around various equicrestal and subcrestal implants. For in vitro tests, rosette strain gauges were used with a data acquisition system to measure bone strain on the bucco-lingual side. The maximum von Mises stresses in the bone were statistically analyzed by analysis of variance for FE models. Results: The experimental bone strains reduced significantly (22% to 49%) as the thickness of CB increased. FE analyses indicated that the suggested CB thickness for efficiently minimizing bone stress was 0.5 to 2.5 mm. The results for the depth of SB were not absolute because obvious stress reductions only presented at a certain range of depth (0.6 to 1.2 mm). Conclusion: Within the limitations of this study, increasing the thickness of CB and maintaining the depth of SB within a limited range can provide the benefit of decreasing the stress and strain in surrounding bone for subcrestally placed implants. J Periodontol 2011;82:302-310.