• ankylosis;
  • antibiotics;
  • endodontic treatment;
  • replantation;
  • root resorption

Abstract Administration of antibiotics is usually recommended when a traumatically avulsed tooth is replanted, in order to prevent bacterial contamination. In the present study, permanent lateral incisors of monkeys were extracted, allowed to dry for 1 h and then replanted. Some teeth had their pulp chambers opened labially and left open for 3 wk after replantation. The monkeys were treated with antibiotics (i.m.) either at the lime of replantation or 3 wk after replantation. In some monkeys, antibiotics were placed in the pulpal cavity. Comparisons were made of the effect of endodontic treatment on periodontal healing and root resorption. The monkeys were killed 8 wk after replantation. It was found that after systemic antibiotic treatment at the time of replantation there was no inflammatory root resorption. Also, endodontic treatment at the time of replantation prevented inflammatory root resorption. When systemic antibiotic treatment was instituted 3 wk after (he replantation, there was no reduction of the inflammatory root resorption as compared with teeth without antibiotic treatment. Application of antibiotics in the pulp 3 wk after replantation almost completely eliminated the inflammatory resorption. In all the treatment groups where administration of antibiotics or endodontic treatment had prevented, reduced or eliminated inflammatory root resorption, 30–45% of the root surface area was ankylotic 8 wk after replantation.