Effects of alkaline phosphatase on bone healing around plasma-sprayed titanium implants: a pilot study in rabbits.

Alkaline phosphatase (ALP) is an enzyme thought to be important in the process of biomineralization. ALP promotes hydrolysis of phosphate containing substrates, produces orthophosphate and increases the uptake of calcium. ALP has been demonstrated recently to induce mineralization of collagen sheets in the animal body. Many factors are being investigated to try to increase the quantity of bone around dental implants. The aim of this study was an evaluation of the bone formation around dental implants used in conjunction with ALP extracted from calf intestine. Titanium plasma-sprayed implants were put for 30 min in glasses containing 500 micrograms of ALP, and then inserted into the femoral articular surface of the knee joint. The implants were retrieved after 2, 3, 4 and 8 weeks, and treated to obtain thin ground sections. The histological examination showed a higher quantity of bone trabeculae, and at 2 and 3 weeks, the presence of plump, elongated, highly stained, very active ALP-positive osteoblasts around the treated specimens. ALP seems, in the experimental conditions of this pilot study, to have a positive effect on bone formation around titanium plasma-sprayed implants.