A histologic investigation of direct pulp capping in rodents with dentin adhesives and calcium hydroxide

Objective: To investigate reactions of pulp tissue when in contact with the dentin adhesives Resulcin AquaPrime + MonoBond (RAPMB, Merz Dental), Scotchbond 1 (SB1, 3M ESPE), and Gluma Comfort Bond (GCB, Heraeus Kulzer) in comparison with calcium hydroxide after 1 to 70 days. Method and Materials: An occlusal cavity was prepared in 152 molars of 76 Wistar rats. The pulps were exposed and dentin adhesives placed on the pulp tissue of 10 molars for each dentin adhesive group and time period. Eight molars per time period served as controls and were capped with calcium hydroxide. All cavities were restored with composite resin. The animals were sacrificed 1, 3, 7, and 70 days after pulp capping. Pulp tissue was histologically evaluated for the following criteria: bacterial infection, inflammatory cells, necrosis, and reparative dentin. The data were statistically evaluated using the Kruskal-Wallis test (P .05). Results: Overall, significantly more bacterial infections were detected 1, 3, 7, and 70 days after pulp capping with dentin adhesive (P .05). In all dentin adhesive groups, 1 day after direct pulp capping, significantly more inflammatory cells were found, whereas after 7 days, this was only the case for the SB1 group (P .05). After 70 days, capping with calcium hydroxide resulted in significantly less necrosis than with RAPMB and SB1 (P .05). Regarding necrosis, SB1 showed the worst results: Pulp necrosis occurred significantly more often than with calcium hydroxide and GCB (P .05). After the application of calcium hydroxide, significantly more reparative dentin formation occurred (P .05). Conclusion: Direct pulp capping with calcium hydroxide seems to produce remarkably better results than with dentin adhesive. Keywords: calcium hydroxide, dentin adhesive, direct pulp capping, histology, rat, tissue reactions