Interrelationship between epithelial and connective tissue attachments during wound healing of the periodontal tissues.

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The purpose of this study was to investigate the interrelationship between epithelial and connective tissue attachments during wound healing of the periodontal tissues. Elastic rubber was inserted between the first and second molars of the maxilla in rats. The rubber was removed after one week, and a notch was made on the most apical region of the exposed root surface using a scalpel. The animals were fed a powdered fed, and sacrificed from immediately to 24 weeks after the removal of the elastic rubber. Regenerative changes of the periodontal tissues were observed light microscopically, immunohistochemically and electron microscopically. One week after the removal, the majority of the exposed root surface was covered by exudate and inflammatory cells although regenerative epithelial cells revealed to form a pocket epithelium. The notch was filled by epithelial cells of the pocket epitheium and the root surface was covered by a long junctional epithelium at the more apical site after four weeks. The long junctional epithelium tended to decrease in length and width with the passage of time. Twenty weeks after the removal, the notched root surface was covered by connective tissue which was closely similar in arrangement and morphology to the periodontal ligament. Immunohistochemical studies showed that laminin was positive to the basal lamina of the epithelial attachment and fibronectin was positive to that of the connective tissue attachment. From these results it is suggested that the epithelial attachment forming by a long junctional epithelium can be replaced by connective tissue attachment on the exposed root surface in rats.