"Collagen adhesion" revisited

Histologie studies of periodantai reconstructive therapies have repeatediy shown a zane of nandescript connective tissue adoptaticn, or collagen adhesian. to the root surface between the apicai extension ot the junctional epithelium and the coronal extension of identitiabie regenerated cementum. To clarify the nature of this zone, supra-aiveoiar periodontai defects were created bilaterally in the mandibuior premolar region in three beagle dags, and exposed raats were Instrumented to remove the cementum. Fiaps were then caranally advanced and sutured. Histologie analysis after 12 weeks af healing showed instrumented raot dentin not associated with junctianai epitheiium, new cementum, raaf resarptlon, or ankyiosis in 27 of 60 root surfaces. In 10 of these specimens subsequenfiy examined by transmission electron microscopy, collagen fibrils were generaiiy oriented parailei to ond in dose proximity ta the raot. A mechanism of collagen attachment was, in fact, functioning at sites of collagen adhesion; these areas may validiy be induded In the histologie attachment level reparfed in studies of periodontai reconstructive irerapy.