PULP CAPPING WITH SYNTHETIC HYDROXYAPATITE IN HUMAN PREMOLARS

Classically, calcium hydroxide is used as a pulp capping agent in humans to form a dentinal bridge over vital dental pulp tissue. The aim of the present study was to determine whether synthetic hydroxyapatite could be used as a substitute. For this purpose, pulp capping with microsized hydroxyapatite (mean size = 38 nm +/- 15 nm) was done under local anesthesia in 12 normal premolars, to be extracted for orthodontic purposes from 12 different young patients, having given their informed consent. Clinically, the healing was uneventful in all patients. Half of the teeth were extracted at 3 months and the other half at 6 months. The pulps were studied under light microscopy and under scanning and transmission electron microscopy using nondecalcified sections. In all cases, a continuous, well-calcified bridge was observed and no inflammatory cells were present in the residual pulp. In some cases denticles containing some synthetic hydroxyapatite crystals were found in the radicular pulp. The calcified bridge was made up by osteodentine and near the pulp tubular dentine with a layer of predentine and odontoblasts were noted. Odontoblastic processes were located in dentinal tubules and the intertubular dentine showed interwoven calcified collagen fibrils and hydroxyapatite crystals with a mean length of 0.1-mu-m along their c axis.