The effects of periodontal ligament injection on pulpal and periodontal tissues.

This study was designed to investigate histologically the effects of the periodontal ligament injection on the pulp of teeth with or without subsequent amalgam restorations, and the effects of the injection on the periodontium. Eighty-eight injections were made on 55 teeth in dogs in intervals from 10-min to 30-day prefixation, while 18 teeth were not injected and evaluated as controls. After perfusion fixation, block sections were decalcified, sectioned longitudinally, stained, and evaluated microscopically by three independent examiners. The pulps were graded for degree of inflammation and the periodontal ligaments were examined for signs of tissue disruption. The results of the pulp study were evaluated statistically and showed no apparent effect on the pulp from the injection. Several periodontal ligaments showed evidence of the injection, ranging from tissue disruption shortly postinjection to areas of active external root resorption in 30-day specimens. It was concluded that this technique does not have long-term deleterious effects on the pulp, but can induce localized external root resorption.