Delayed partial pulpotomy in permanent incisors of monkeys

Summary. Pulpal exposures, approximately 1 mm in size, were created in 35 developing permanent incisors of five monkeys. These were left untreated for one of three time intervals: 4, 48 or 168 hours. After these periods, a standardized partial pulpotomy procedure was performed. When haemostasis had occurred, a layer of Dycal was applied over the pulp stump and the cavity filled with amalgam. Radiographs were taken 1 month and 6 months after treatment. The jaws were removed 6 months after partial pulpotomy and prepared for histological examination. The clinical examination and 1‐month radiographs revealed no abnormality; on the 6‐month radiographs a periapical radiolucency was observed on one tooth. All teeth showed continued root development over the experimental period. Histologically, 27 pulps had healed, three pulp wounds were incompletely healed, and five, all in one animal, were severely inflamed. Four of these five failures were associated with extensive bacterial contamination. In all teeth, cervical dentine was deposited but the amounts varied considerably. The success of pulpotomy was not jeopardized by delaying treatment for up to 168 hours after pulpal exposure.