Variations in the configuration of pulp chambers subjacent to protostylids

This study aimed to clarify the positional relationship between the crown contour and pulp chamber of protostylids using three-dimensional reconstructed images.

Fourteen molars with protostylids from Japanese subjects were subjected to micro-computed tomography. The external surface configurations of the teeth and pulp chambers were reconstructed. Hard tissue thicknesses in appointed buccal areas were measured on the reconstructed images.

Well-developed protostylids exhibited pulp-prominences above or at the cervical line level. Those that were moderately developed exhibited bulges of the pulp chamber subjacent to the protostylids. Ten of the 14 teeth had prominences in the crown pulp above or at the cervical line level. In addition, 13 teeth exhibited pulp chamber bulges surrounding the lower tooth trunk. No significant differences were apparent in the buccal horizontal thickness of the hard tissue between the protostylids with pulp chamber prominences and the protostylids without pulp chamber prominences at the cervical line level.

Pulp chamber configurations subjacent to protostylids vary based on the development of the traits of the protostylids. Minimum possible taper should be applied during standard vital tooth preparations, as reduced residual dentin thickness is predicted in well- and moderately developed protostylids.