Influence of Facial Bone Thickness After Implant Placement into the Healed Ridges on the Remodeled Facial Bone and Considering Soft Tissue Recession: A Systematic Review

Purpose: A systematic review was performed of the dimensional changes in facial cortical bone following implant placement into healed ridges, with the aim of establishing a minimum bone thickness that limits such changes. The influence of such bone remodeling upon the soft tissues and implant survival was also evaluated. Materials and Methods: A search was done of two electronic databases (MEDLINE via PubMed and CENTRAL), complemented by a manual search and lists of references. The risk of bias and methodological quality were assessed using the Cochrane Collaboration tool, the Methodological Index for Non-randomized Studies (MINORS), and the Quality Appraisal Checklist for Case Series. Results: The search yielded 536 publications, of which 11 (four randomized clinical trials, two non-randomized clinical trials, and five case series) were entered in the review. All the included studies reported vertical and horizontal implant facial bone resorption. Decreased facial bone thickness was correlated with increased vertical bone resorption, which in turn was associated with slight soft tissue retraction. A meta-analysis could not be performed, due to the heterogeneity of the study designs and measurement sites. Conclusion: No minimum facial bone thickness was seen that would completely avoid peri-implant bone loss and maintain soft tissue stability. However, a thickness of approximately 2 mm was associated with diminished vertical bone resorption and less peri-implant mucosal recession. Keywords: dental implants, facial bone resorption, facial bone thickness, implant success, marginal bone loss, soft tissue recession