An Experimental Study of Trauma from Occlusion in Rhesus Monkeys

Abstract

The purpose of this study was to produce an experimental model of traumatic occlusion in Rhesus monkeys and to characterize the changes in periodontal tissues clinically and histopathologically.
Nine Rhesus monkeys were used. Four weeks after beginning the oral hygiene program, all 4 canines were cut away from the gingival margin. Immediately after this, all the monkeys showed distinct signs of bruxism (grinding). At week 0 cast restorations designed to fill the “free entry” without disturbing the intercuspal occlusal position, were set at the 2 nd maxillary premolars (experimental teeth). Thereafter only the experimental teeth were in contact with the occluding teeth during lateral movement caused by bruxism.
The results were as follows:
1) Mobility of the experimental teeth increased markedly during the first 6 weeks but showed no increase thereafter.
2) Histological specimens of experimental teeth showed that destructive changes in tissues were seen during the first 4 weeks and repairable changes in tissues were seen after week 8.
3) Mobility of the experimental teeth in animals, in which restorations of the experimental teeth were removed and canines reinstalled in their original position, markedly decreased.
4) New bone formation was seen on the side of the periodontal ligament on experimental teeth in animals in which restorations of the experimental teeth were removed and canines reinstalled in their original position.
It was concluded that trauma from occlosion in monkeys was produced at the 2 nd maxillary premolars by the experimental procedures, and was comparable to that observed in humans. The tissue changes caused by trauma from occlusion were reversible and no pocket formation was apparent under conditions of intensive plaque control .