Hierarchy of variables correlated to odontoblast-like cell numbers following pulp capping

Objectives. Following tooth pulp exposure, pulpal repair is accomplished by dentine bridge secretion by odontoblast-like cells. However, little information is available about the hierarchy of variables, which influence odontoblast-like cell numbers. The purpose of this study was to examine correlations between pulp capping events and odontoblast-like cell numbers. Methods. Two hundered and fifty standardised pulp exposed cavities were prepared in non-human primate teeth according to ISO usage guidelines. Exposed pulps were capped with Calcium hydroxide [Ca(OH)2], and multi-step and self-etching primer composite resins. Teeth were collected from 3 to 60-days to observe pulp reactions. Statistical analysis was evaluated using analysis of variance. Results. The hierarchy of variables correlated to odontoblast-like cells were the dentine bridge area (P=0.0001), time since pulp exposure (P=0.0001), odontoblast numbers opposite the exposure site (P=0.0002), and pulp capping materials (P=0.0313). Other pulp capping variables were found to be less likely to be correlated with odontoblast-like cell numbers. Conclusions. The area of dentine bridge formation is directly related to the numbers of odontoblast-like cells, cell activity is time dependent, and the cell numbers are much lower than original odontoblast cells. The time-lag between the appearance of odontoblast-like cells at the site of pulp exposure, and the limited numbers of these cells, explain why pulpal repair is difficult to achieve successfully following pulp exposure.