The appearance of bone resorbing activity in ligature induced gingivitis in dogs

The in vitro bone resorbing activity of extracts from healthy and inflamed dog gingiva were compared and the appearance of the resorbing factor between 1 and 6 weeks of gingivitis was measured. Seven adult dogs were used. The gingiva were initially rendered healthy by scaling and polishing. Plaque retentive ligatures were placed around the necks of teeth so that at the end of the experiment samples of healthy gingiva and gingiva with 1 and 6 week old ligature induced gingivitis could be harvested from each dog. The bone resorbing activity of extracts from these gingival samples was studied by measuring the release of ⁴⁵Ca from prelabeled fetal rat long bones in organ culture. Six out of 7 extracts from healthy quadrants had no bone resorbing potential whereas 13 out of 14 extracts from ligatured quadrants stimulated significant amounts of bone resorption. The resorbing activity appeared during the first week after ligature placement and no significant increase in resorbing potential was noted between extracts obtained 1 and 6 weeks after ligature placement. It was concluded that the appearance of the bone resorbing factor(s) is related to the accumulation of plaque and/or the resultant inflammation and that it may be responsible for the alveolar bone loss seen in ligature induced periodontal disease in dogs.