Histomorphometric and micro-computed tomography analysis of pulpal response to three different pulp capping materials

Introduction: This study evaluated the responses of baboon dental pulps after the application of 3 pulp capping materials. Methods: Thirty premolar teeth in four 3-year old baboons were randomly assigned to 1 of 3 pulp capping materials. A split-mouth design was used, and intra-animal side randomization was applied to the 3 experimental groups (calcium hydroxide, ProRoot white mineral trioxide aggregate, white Portland cement) and the control group (no pulp capping material). Animals were divided into 4 groups (n = 8 teeth/pulp capping material). The animals were killed after 4 months. Histomorphometric analysis and micro-computed tomography were performed on the retrieved specimens. Results: Pulps capped with ProRoot white mineral trioxide aggregate and white Portland cement exhibited thicker reparative hard tissue deposition over the exposed pulps when compared with those that were capped with calcium hydroxide (P < .007), but they were not significantly different from one another (P > .05). No tubular reparative dentin could be identified from any of the specimens. Dentin tunnel defects were evident in all groups. There was no reparative hard tissue formation in the negative control group. Conclusions: Reparative hard tissue formation in pulps capped with Portland cement-based materials differs only in quantity (thickness) but not in quality from those that were formed after direct pulp capping with calcium hydroxide. It appears that other growth factors and up-regulation of transcription factors are required apart from those sequestered via the application of alkaline pulp capping materials for dental pulp stem cells to commit to the odontoblast lineage.