Methods: Sixty maxillary first molars of 5-week-old rats were treated pulpotomy with calcium hydroxide and calcium carbonate and examined by micro CT(R_mCT®) at 0, 3, 7, 14 and 28 days after treatment. After dehydrating and Paraffin embedding, the specimens were serially sectioned at 4μm on a microtome. Hematoxylin-eosin staining and immunoreactivity for osteopotin were analyzed at 1, 3, 7, 14 and 28 days.
Results: The average calcified area in the image reconstructions of the median sagittal plane of micro-CT pictures were calculated as 26.28, 30.48, 34.94mm2 for calcium carbonate group and 26.94, 30.30, 34.68 mm2 for calcium hydroxide group on 7, 14, 28 days, respectively using with Software I-View® (J. Rigaku, Japan), no significant differences were found between two agents. Inflammatory reaction and dentin-like hard tissue structure were observed in both groups. Osteopotin immunoreactivity was observed in the matrix at 1 day in both groups, especially just beneath the necrotic layer in calcium hydroxide group. At 7 days, immunoreactivity remained evident along the superficial layer of the newly formed dentin bridge matrix in both groups.
Conclusion: Our findings indicated that the calcium carbonate-induced reparative dentinogenic process is basically similar to the process induced by calcium hydroxide, which follows the proliferation, migration and differentiation of progenitor cells. Calcium carbonate induced to formation of dentin-like hard tissue, and might show less toxic effect than traditional calcium hydroxide agents.