Osteoclastic Activity Differs When Cultured on Deciduous and Permanent Dentine

Deciduous tooth resorption occurs as a physiological process in all diphyodont animals during eruption of the permanent dentition, while resorption of permanent tooth roots always occurs under pathological conditions. Our previous report, in which we cultured osteoclasts on bovine deciduous and permanent dentine slices, suggests that deciduous teeth exhibit a higher degree of resorption than permanent teeth. This could be due to a difference in odontoclast activity and/or susceptibility for resorption between deciduous and permanent dentitions. Objectives: The purpose of this study was to analyze biochemically, the differential resorption activity between deciduous and permanent dentine. Methods: Osteoclasts obtained by co-culture were cultured on bovine deciduous and permanent dentine slices. Cathepsin K, MMP-9 and MMP-13 message levels in osteoclasts cultured on deciduous and permanent dentine were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). Results: A statistically significant difference in the levels of Cathepsin K (P < 0.001), MMP-9 (P < 0.01) and MMP-13 (P < 0.005) expression was observed, with osteoclasts cultured on deciduous dentine expressing more. In our previous study, we reported that the volume of resorption pits/osteoclast also varied significantly (P < 0.001), with deciduous being resorbed more than permanent. Conclusions: These results confirm our hypothesis that osteoclast activity differs when cultured on deciduous and permanent dentine.