ONLAY SILICONE AND HYDROXYAPATITE-TRICALCIUMPHOSPHATE COMPOSITE (HAP-TCP) BLOCKS INTERFERE WITH NASAL BONE-GROWTH IN RABBITS

We investigated how a new type of synthetic porous hydroxyapatite cera mic (HAP-TCP) acts when it is implanted in growing membranous bone, Se venty-six New Zealand White infant male rabbits (I-week-olds) were use d, Rabbits received HAP-TCP block or silicone block implantation in th eir right nasal bone, The left nasal bone was used for a sham, Serial or cross-sectional examinations by morphometry, radiology, blood bioch emistry, and histology were carried out, Both the HAP-TCP and silicone groups exhibited no systemic growth disturbance in terms of morphomet ry and blood biochemistry. Dual energy x-ray absorptiometry (DEXA) rev ealed, however, a decrease in the bone mineral content (BMC) of the ri ght nasal bone in the silicone group, Histology revealed a superior af finity of HAP-TCP to bone tissue than that of silicone, When a HAP-TCP block was implanted under the periosteum it bonded directly to bone t issue, However, sinking of the implants into the bone tissue were note d both in the HAP-TCP and the silicone groups in longitudinal observat ion, These results suggest that although HAP-TCP has superior affinity to bone tissue, this by itself is not enough sufficient reason to bel ieve that HAP-TCP can be effectively applied during the growth period.