Radiographic and microscopic evaluation of subperiosteally implanted blocks of hydroxylapatite-gelatin mixture in rabbits.

The efficacy of using gelatin as an adherent of particulate hydroxylapitite was studied by implanting preformed blocks of a hydroxylapatite-gelatin mixture subperiosteally on the buccal aspect of the mandible in rabbits. The rabbits were killed at 1, 2, 4, 12, and 24 weeks after implantation. After radiographic examination, excised specimens were decalcified and examined microscopically. The radiographic findings in the hydroxylapatite-gelatin group were essentially consistent with those of the hydroxylapatite group, except that in the hydroxylapatite group migration of particles was seen in some specimens. Microscopically the majority of the gelatin was unidentifiable at 1 week and there was no evidence of a rejection response. The degree of new bone formation and tissue response in hydroxylapatite-gelatin mixture group was essentially the same as in the hydroxylapatite group. The results indicate that gelatin is an excellent adherent for particulate hydroxylapatite, enabling easy handling and proper placement of the material with no inhibitory effect on new bone formation.