Controversy persists as to the role of occlusal overload in peri-implantitis. Animal studies have not revealed the biological threshold for fatigue failure in the peri-implant bone. On the other hand, clinical studies have demonstrated a link between parafunction and implant failure, although variables such as intensity and frequency of loads, as well as bone density, have led to different outcomes. The absence of specific engineering “building codes” for the clinician has relegated prosthetic design planning to intuitive guidelines for all patients. For example, higher crown to implant ratios (2–3:1), implant cantilever prostheses and non-splinted restorative designs have been avoided because of the concern for overload. However, evidence has not supported this general approach. A call for preclinical research to establish specific patient load thresholds is in order to establish a customized treatment plan.

According to the American Academy of Implant Dentistry, 500,000 dental implants are placed in the USA annually. These numbers continue to climb despite the unknown role of occlusion in the biological outcomes of osseointegrated implants. Natural teeth that present with initial occlusal discrepancies have demonstrated deeper probing depths and poorer prognoses than those without these discrepancies. However, there are no controlled studies that evaluate the effect of occlusion on implants in humans, due to the fact that they would be countered to the Helsinki accords. What remains is an available body of evidence that is broad and heterogeneous. What is lacking is a study that would reveal the link between specific mechanical loads and histological changes, to serve as a guide to the clinician for implant prosthetic design and occlusal therapy. It is known that the response to increased mechanical stress below a certain threshold will strengthen the bone by increasing the bone density or apposition of the bone.