INFLUENCE OF CONVENTIONAL FORCEPS EXTRACTION AND EXTRACTION WITH AN EXTRUSION INSTRUMENT ON CEMENTOBLAST LOSS AND EXTERNAL ROOT RESORPTION OF REPLANTED MONKEY INCISORS

Cementoblast loss and root resorption on the root surface was register ed histologically after removal and immediate replantation of maxillar y central incisors in monkeys (Cecropithecus aethiops). Incisors were removed with either a conventional extraction technique using forceps or with a special designed extrusion instrument and in both cases teet h were immediately replanted. Altogether 18 monkeys were used for the experiments in which 9 monkeys were sacrificed after 3 d and 9 animals after 8 wk. Histological analysis was made in horizontal sections per pendicular to the long axis of the tooth using either 24 measuring poi nts or 12 sections. Histometric analysis showed extensive cementoblast loss in the periodontal Ligament (PDL) and with a maximum of damage o ccurring on the corner surfaces of the root, Extracted teeth showed si gnificantly more extensive cementoblast loss than extruded teeth. Root resorption was also found in the corner locations and was significant ly more frequent in extracted than in extruded teeth. There was a simi larity in the distribution of cementoblast loss and root resorption in dicating that root resorption develops in the same areas where cemento blast loss takes place, i.e. locations that are more compressed during removal of the tooth and must have caused by mechanical damage to the PDL exerted on the root surface during tooth removal.