Effects of cortical bone thickness and implant length on bone strain and interfacial micromotion in an immediately loaded implant.

Purpose: The aim of this study was to evaluate the effects of cortical bone thickness and implant length on strain in the surrounding bone and micromotion at the bone-implant interface in single immediately loaded implants.
Materials and Methods: Experiments with rapid prototyping technique and finite element simulations were performed to evaluate bone strain and micromotion at the bone-implant interface. Implants (13-mm long) were embedded into models with three thicknesses of cortical bone (0.5, 1.7, and 3.4 mm), and implants with different lengths (11.5 and 15.0 mm) were inserted into models with 1.7 mm of thickness of cortical bone. Vertical and lateral loads of 130 N were applied to the models.
Results: On lateral loading, the strains were highly concentrated on one side of the mandible in both experimental and finite element models. Sliding and gap distances were reduced when the cortical bone was thicker and when the implant was longer.
Conclusion: Placement of a longer implant into thicker cortical bone will result in reduced sliding and gap distances. However, bone strain is influenced more by the cortical bone thickness than by the implant length for single immediately loaded implants.