INFLUENCE OF MONOCORTICAL AND BICORTICAL ANCHORAGE ON THE INTEGRATIONOF TITANIUM IMPLANTS - A STUDY IN THE RABBIT TIBIA

The study aimed to evaluate the removal torque and bone tissue respons e to titanium implants supported by one or two cortical layers, A tota l of 72 screw titanium implants, either 10 or 16 mm in length and 3.75 mm in diameter, were inserted in right and left tibiae of 18 adult Ne w Zealand rabbits. The implants engaged either one or two cortical lay ers, and the animals were allowed a healing period of 6 or 12 weeks. T he degree of integration was assessed by measuring the removal torque with a torque gauge manometer, Histomorphometric calculations were als o performed in 10-mu m-thick ground sections. All implants were clinic ally stable at the end of the experiment, The removal torque was two t imes higher for the bicortical implants after 6 weeks, and three times higher after 12 weeks, than for the monocortical ones. The 16-mm impl ants also showed a statistically higher amount of bone contact and bon e area after 6 and 12 weeks, respectively, than the short ones. The re sults support bicortical anchorage of implants also in the clinical si tuation. (C) Munksgaard, 1996.