Histometric analysis of ligature‐induced periodontal defects in beagle dogs‐ evaluation following ligature removalLongitudinal

The aim of the present study was to investigate the sequence of events that takes place in ligature‐induced periodontal defects following removal of the ligature. In eight beagle dogs the dentogingival fibres around six lower premolars ( 2 P 2 , 3 P 3 , 4 P 4 ) were cut to the level of the alveolar bone. Closely adapted copper bands were then cemented around the teeth. After 3 weeks the copper bands were replaced by cotton floss ligatures which were left in place for 11 weeks. The dogs were sacrificed on different dates so that it was possible to analyse defects 3, 7, 15, or 31 weeks after ligature removal. Contralateral defects one week after ligature removal served as controls. Micrographic color slides of the histological sections were analyzed using a Ferranti‐Cetec digitizer. Mean values for loss of attachment in the 15 and 31 weeks specimens were greater than in the control defects, suggesting that apical positioning of the junctional epithelium was irreversible. However, alveolar bone height tended to increase with experimental time, indicating bone repair. In the 15 and 31 weeks specimens junctional epithelium was occasionally found between the root surface and the alveolar bone It was concluded that the model does not show all the histological characteristics of naturally occurring periodontitis even in those dogs examined 31 weeks after removal of ligatures.