The interrelationship between the root surface and alveolar bone of the replanted avulsed tooth after etching

It has been suggested that removal of the damaged nonvital periodontal ligament (PDL) may result in slower destruction of tooth substance following replantation of teeth. It has also been suggested that citric acid conditioning of surgically exposed dentin may enhance connective tissue attachment on root surfaces. The aim of this study was to examine the interrelationship between the acid etched root surface of the replanted tooth and the alveolar bone. Forty-five available anterior teeth from six monkeys were divided into 3 groups in this experiment. All teeth were extracted and dried for 2 hrs. In the first group the teeth were replanted immediately after endodontic therapy. The teeth in the second group were replanted after immersion in 10% sodium hypochlorite and subsequently irrigation with normal saline. In the third group, the cementum and necrotic PDL were removed by grinding the root surfaces which were then treated with citric acid (PH = 1) for 3 minutes followed by normal saline irrigation. All teeth were replanted without splinting and were subjected to histological examination at 12 week post-replantation. Close apposition of collagen fibrils of the new connective tissue to the exposed root surface was observed in most cases in the second and third group, although bony ankylosis and inflammatory root resorptions were also found in some areas. Teeth in the first group, the control experiment, had much more replacement and inflammatory resorptions. Then the result suggested that demineralization with citric acid on the denuded avulsed tooth prior to replantation may decrease the chance of replacement resorption and result in fibrous adhesion to the alveolar bone.