With implants, the load is transferred directly from the implant to surrounding bone through the ankylosed root analog and adverse effects have not been found to be as pronounced during non-axial loading. However, there are thresholds of non-axial forces that have been shown to cause crestal bone loss around implants. Duyck et al. have shown that a transverse force of 14.7 N applied on a distance of 50 mm from the top of the implant results in a bending moment of 73.5 Ncm when repeated with 2520 cycles at a frequency of 1 Hz causes crater like defects lateral to the osseointegrated implants.

This may offer a threshold to explain why fixed dental prostheses that are designed with cantilever arms ≥ 8 mm have demonstrated marginal bone loss, leading to peri-implantitis.

Splinting

The use of splinting to decrease force magnitudes on implant restorations and thereby protect against occlusal overload leading to marginal bone loss continues to be controversial. Vigolo et al. conducted a 10-year split-mouth design on 44 patients with splinted and non-splinted implant restorations on the right and left maxillary posterior quadrant, respectively. He found no difference in crestal bone loss, despite that 17% of the implants were placed in bone quality type IV. However, notable to the patient cohort profile was the absence of any bruxers. Naert et al. treated a larger population with 644 implants. Two hundred thirty-five were restored with single crowns and 409 with a splinted prosthesis. After a 16-year follow-up, 95.8% of all restorations survived. Statistical analysis showed no significant difference in hazard rate between implant-supported single crowns and those splinted by means of fixed prostheses. It was also shown that neither restoration design, jaw site nor implant position (anterior or posterior) had a significant effect on bone loss. Despite the fact that patients were widely accepted for treatment, no data were reported on the number of bruxers. While recommendations have been made to splint crowns in patients with parafunction, no clinical or histological evidence has demonstrated marginal bone response advantages.