The Influence of Experimental Periodontitis on Tooth Extrusion in Monkeys

The purpose of this study was to evaluate the influence of experimental periodontitis on tooth extrusion in teeth withoutocclusal contact. Three squirrel monkeys were used. Upper first and second molars on each side were selected, one side as the experimental site, and the other as the control site. Cotton ligatures were placed around the gingival margins of experimental teeth to establish experimental periodontitis. The animals were fed a soft diet and toothbrusing was done at the control site three times per week during the whole experimental period. At 24 weeks after the cotton ligature placement at the gingival margin, antagonistic crowns were cut away from the gingival margin. We then set the apparatus so as to eliminate the buccal and lingual pressure which might influence tooth extrusion of the upper molar. At 20 weeks after the extrusion period, we measured the amount of tooth extrusion for each four week period. The following results were obtained; 1. Teeth without occlusal contact had been extruded, regardless of experimental or control site, at 20 weeks after loss ofocclusal contact. 2. There were no significant differences in tooth extrusion between teeth with slight periodontitis and control teeth. These results suggest that slight periodontitis may not be an influential factor in the acceleration of tooth extrusion, and that the prompt recovery of occlusal contact should be practiced for teeth without adequateocclusal contact.