Scanning electron microscopic study of pulp stones in human permanent teeth.

Scanning electron microscopy was used to examine pulp stones which are small calcified formations found in the coronal and/or radicular part of the dental pulp. Pulp stones range considerably in size and shape. Most are round or oval but others can be irregular and may correspond to a reduced duplicate of the pulp chamber anatomy. Both free and attached pulp stones were observed. The surface aspect was variable and frequently exhibited large resorption zones. Three characteristic features were observed on fractures: a) no characteristic organization where the mineralized mass is compact and homogeneous, b) a concentric architecture around an initiating central core, and c) a linear orientation along the pulp axis showing mineralized fibres and vessels. The findings suggest that the presence or absence of tubules should not be the sole factor for denticle classification since tubules can be also observed in "false" pulp stones. Cellular oval lacunae connected by long extensions were also found. Various stages of mineralization were seen, in particular, a deposition of fine needle shaped crystals on a collagenous matrix, and the fusion of numerous small calcospherules to the mineralized mass.