Combined effects of implant insertion depth and alveolar bone quality on periimplant bone strain induced by a wide-diameter, short implant and a narrow-diameter, long implant.

Statement of Problem: Strain levels in periimplant bone are affected by implant dimensions, bone quality, and implant insertion depth, resulting in different bone maintenance characteristics.
Purpose: The purpose of this study was to evaluate the biomechanical response of the jaw bone to a wide-diameter, short (WDS) implant, and a narrow-diameter, long (NDL) implant for various simulated clinical scenarios.
Material and Methods: The finite element method was used to evaluate periimplant bone strain distribution for 5 × 6-mm (WDS) and 3.5 × 10.7-mm (NDL) implants. A 3-dimensional segment of the mandible was constructed from a computerized tomography image of the premolar region. Occlusal force was simulated by applying a 100-N oblique load on the abutment. Bone strain distributions for 5 different implant insertion depths and 2 different levels of alveolar bone quality were evaluated.
Results: For an NDL implant, approximately 60% to 80% of the bone volume surrounding the implant was subjected to 200-1000 μstrain (μɛ), and 15% to 35% was subjected to 1000-3000 μɛ, regardless of the alveolar bone quality. For a WDS implant, the bone volume subjected to 1000-3000 μɛ increased, and the bone volume subjected to 200-1000 μɛ decreased in lower quality alveolar bone. For both implant types, bone volume experiencing strain levels less than 200 μɛ, and/or greater than 3000 μɛ, was predicted to be relatively small.
Conclusions: In general, the thread design promoted relatively high strain around the thread tips, and the bone inside grooves was less strained. A more even and higher strain distribution in the periimplant bone was generated by the WDS implant as compared to the NDL implant. Regardless of the implant dimensions and simulated clinical scenarios, the development of high strain in the alveolar region was inevitable. Strain levels in periimplant bone were reduced as the insertion depth of the implant was increased.
(Copyright © 2010 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.)