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)

Apical migration of oral epithelium in experimental dehiscence wounds.

The purpose of the present investigation was to determine if the placement of free mucosal grafts would delay the apical migration of oral epithelium into surgically created dehiscence wounds. Dehiscence wounds, measuring 8 x 6 mm, were surgically created on the mandibular canines of 5 beagle dogs. The exposed root surface was then curetted and horizontal grooves were made, one at a point just below the gingival sulcus and the other at the apical border of the dehiscence. Experimental teeth received free alveolar mucosal grafts while the contralateral teeth served as controls. The grafts were placed with the epithelial side against the tooth surface to bridge the dehiscence at the level of the coronal notch and were sutured in place. The flaps were then repositioned (over the mucosal grafts) and sutured. Apical migration of the oral epithelium, after 10 days, was assessed histologically using the coronal and apical grooves as points of reference. The oral epithelium was detected in the coronal one half of the dehiscence, in both the control and experimental teeth. There were no significant differences observed between the two, suggesting that the placement of a mucosal graft, as described here, provides little benefit in delaying apical migration of oral epithelium. The fact that the epithelium failed to reach the apical half of the dehiscence may indicate that features of this wound model may help our understanding of epithelial cellular kinetics operative in periodontal wound healing.