The effects of apical modification on the vitality of replanted permanent monkey teeth

Abstract

A study was conducted on the effects in a rhesus monkey of increasing the surface area of pulpal tissue available for revascularisation and regeneration of nerves after replantation of permanent teeth. Four teeth were replanted and used for controls, including two with incomplete apical development. Twelve teeth with completed apical development were replanted immediately after apical modification to increase the surface area of exposed pulp. The technique consisted of creating a facial and lingual groove in the apical region and exposing additional pulpal tissue. Radiographs were taken periodically and the replanted teeth were stable during the study period. The monkey was sacrificed after 93 days. The first hypothesis, that the apically modified teeth would sustain a healthy periodontium clinically for a period of ninety days, was disproved. Histological sections of the teeth and their supporting tissues showed varying amounts of root resorption and ankylosis. All of the apically modified teeth showed pulp necrosis, while three of the four control teeth had reestablished blood and vascular supplies and appeared vital. Ingrowth of granulation tissue was seen in the replanted teeth with pulp necrosis including one control tooth which had failed to revascularize. The second hypothesis, that the apically modified teeth would demonstrate significantly more apical revascularisation and nerve regeneration than the control teeth, was also disproved. In conclusion, the apical modification technique as performed to increase the area available for regeneration of nerves and vessels was not a success. As expected, however, immediate replantation of avulsed teeth resulted in reestablishment of periodontal membrane attachments.