Application of alpha-tricalcium phosphate coatings on titanium subperiosteal orthodontic implants reduces the time for absolute anchorage: a study using rabbit femora.

We are currently developing a small perforated titanium subperiosteal implant specifically for orthodontic therapy, which can be placed anywhere on the bone surface. In the present study, we coated this implant with hydroxyapatite (HA) or alpha-tricalcium phosphate (alpha-TCP) in an attempt to shorten the initial stabilization period relative to the few months that is usually required. The coated implants were placed beneath the periosteum in rabbit femora. The implants were observed by radiographically and histologically, and measured the tensile strength of the bone-implant interface. Two weeks after placement, the volume of new bone formed in the perforations of the implant was significantly greater for the alpha-TCP-coated implants than for the HA-coated implants. Our findings indicate that new bone is formed faster in the surrounding area with alpha-TCP- and HA-coated subperiosteal implants than with uncoated implants, and that alpha-TCP is a particularly effective stimulator of new bone formation.