Experimental apical scars in rats.

Abstract

In order to study the etiology of apical scars, vitallium implants were placed in four intra-maxillary and mandibular cavities of Sprague-Dawley rats. After one month the implants were removed. In half of the cavities, which were selected as experimental cavities, bleeding was avoided. In the others, the walls of the cavities were perforated in several places to induce formation of a good-quality clot. These specimens were identified as control cavities. Animals were killed on day 0 and on the second, fourth, eighth, sixteenth, twenty-eighth, and fifty-sixth days after implant extraction. The jaws were isolated and, after fixation, decalcification, and routine procedure for paraffin sections, studied under the light microscope. In the experimental cavities, the bone healing was delayed. Apical scars occurred, even when one of the two cortical bone plates remained intact. Delayed healing has been associated with the absence of a good-quality clot and with the presence of a sequestrum or suture threads in the wound. The proximity of the central nervous system or of a nerve where the cavity was prepared often leads to a delayed bone healing. The interposition of muscle fibers and the proliferation of collagen from the gingival chorion or from the periodontal ligament lead also to collagenous scars.