The combined effects of plaque and physical stress on periodontal tissues.

Experiments have been performed in beagle dogs in attempts to evaluate the effect of orthodontic- and jiggling-type trauma on the supporting structures of premolars. The results reported have unanimously demonstrated that in situations where orthodontic or jiggling forces were inflicted on teeth with a normal periodontium, or on teeth with overt signs of gingivitis, the periodontal ligament tissue reacted by transitory signs of inflammation. These phenomena occurred without a concomitant loss of connective tissue attachment and development of pathologically deepened periodontal pockets. If the jiggling trauma was inflicted on teeth with an ongoing plaque-associated, destructive periodontitis, the resulting inflammatory reactions caused enhanced loss of attachment and angular bony defects. Furthermore, orthodontic tilting movements of teeth (intrusion) in a plaque-infected dentition may shift a supragingivally located plaque into a subgingival position resulting in periodontal tissue breakdown.