Periodontal ligament cell kinetics following experimental regenerative procedures

The present study analyzed the cell kinetics in periodontal ligament (PDL) apical to curetted root surfaces following an experimental regeneration procedure. 3 mm of the buccal and interproximal bone was removed around the premolars and molars in 4 Macaca fascicularis monkeys. The exposed root surfaces were planed thoroughly. Before replacing the flaps, pieces of Millipore filter were attached to the crowns of 1 premolar and 1 molar in each quadrant to cover the exposed roots. The adjacent teeth had no physical barriers and served as control wounds. The treatment procedure in 4 segments and sacrifice of the monkeys were scheduled to provide observational periods of 1, 2, 3 and 7 days. 1 h before sacrifice, 3-H thymidine was injected intravenously. Autoradiographs of buccolingual sections were prepared and the labelling index (LI) in the PDL apical to curetted root surface measured in 200 micron increments. The LI remained increased in the first 200 micron of the PDL in both the experimental and control wounds at all observation periods compared to similar zones on the unwounded lingual surfaces. The LI was highest in the first 200 micron zone and decreased to almost normal levels at about 600 micron from the curetted root surface. There were no statistically significant differences between the LI for the PDL apical to experimental and control wounds at all observation periods. The present findings suggest that following experimental regeneration procedures in monkeys, a very limited zone of the PDL apical to the wound acts as a source for cells migrating into the wound.(ABSTRACT TRUNCATED AT 250 WORDS)