Formocresol pulpotomy in teeth of dogs with induced pulpal and periapical pathoses

Abstract

Formocresol pulpotomy has been recommended for all infected primary molars irrespective of pulp vitality. Microscopic evidence is lacking when teeth with less than optimal pulpal preoperative conditions are treated. This study evaluated clinically, radiographically, and microscopically the effect of the five-minute formocresol pulpotomy in primary and permanent teeth of dogs with induced pulpal and periapical pathoses. Radicular pulps of 18 permanent and 12 primary teeth were exposed to the oral flora for 28 and 14 days, respectively, to produce pathoses that would contraindicate routine use of the pulpotomy. The five-minute formocresol pulpotomy was performed and nine permanent teeth were evaluated after four weeks and another nine after 12 weeks; the primary teeth were evaluated after 14 days. Eight permanent and four primary "control” teeth had their radicular pulps exposed to the oral flora for identical periods but were not treated by formocresol. In permanent teeth clinical success was 90 per cent, radiographic success was 30 per cent, and microscopic success of bloc sections was 10 per cent. The vital pulp reacted to formocresol by forming a homogenous band of markedly eosinophilic tissue, interpreted as "fixation;" very pale staining tissue was apical to this. A second area of marked eosinophilic tissue was in the apical part of all vital canals, apical to which was vital normal pulp. Similar trends were seen in the primary teeth. No "fixation," organization or repair was seen within any periapical lesion. The microscopic periapical appearance of related vital permanent and all necrotic canals indicated that formocresol pulpotomy is not particularly effective in teeth with induced pulpal and periapical pathoses. The findings suggest that it be used only under optimal clinical conditions.