Influence of particle size of calcium phosphate ceramics as a capping agent on the formation of a hard tissue barrier in amputated dental pulp

The purpose of this research was to compare the effect of two different particle sizes of hydroxyapatite and β-tricalcium phosphate as capping agents on hard tissue barrier formation after experimental pulpotomy in canine dental pulp. By the thirtieth day after pulp exposure and capping with hydroxyapatite-300 (particle size, 300 μm), a hard tissue barrier was formed in 8 of 17 specimens. A newly formed barrier was seen around the hydroxyapatite particles and connecting neighboring particles. Capping with tricalcium phosphate-300 (particle size, 300 μm) led to the formation of a hard tissue barrier surrounding the particles in 11 of 17 specimens. In contrast, using hydroxyapatite-40 (particle size, 40 μm) and β-tricalcium phosphate-40 (particle size, 40 μm), hard tissue barrier formation was poor and almost all pulp tissues showed infiltrations of inflammatory cells or abscess formation. These findings suggest that the particle size of hydroxyapatite and β-tricalcium phosphate is an important factor in reparative hard tissue formation.