Periosteum in regeneration of palatal defects

The influence of the periosteum on the regeneration of palatal bone was investigated in this study. Eighty, 8-week-old, purebred beagle dogs were assigned randomly to four groups: (1) unoperated dogs as a group control; dogs in which the mid-third of the palate was surgically removed and (2) left unrepaired (unrepaired controls); (3) repaired with mucosal flaps; (4) repaired with mucoperiosteal flaps. Five animals from each group were killed at 4, 6, 8, and 12 weeks after surgery and coronal sections examined under light microscopy. Among the animals with complete soft tissue healing, 8 of 12 dogs from Group 2, 11 of 20 from Group 3, and 10 of 19 from Group 4 showed complete bone regeneration. No significant differences were found overall in bone thickness and bone density measurements between Group 3 and Group 4. Histologically, a well-differentiated periosteum was present on the maxilla at 4 weeks, even in animals in which the periosteum had not been preserved in the original flap. These results suggest that maintaining the periosteum at surgical closure does not influence bone regeneration in beagles up to 12 weeks of age. We suggest that osteoprogenitor cells, migrating from the undisturbed local periosteum adjacent to the defect, were responsible for the new bone growth in our study.