Effects of exposure to 4-META/MMA-TBB on Pulp Cell differentiation

Objectives: Adhesive restorative systems have expanded the range of possibilities for the direct pulp-capping technique, providing evidences of clinical success in vital pulp therapy. However, quite few studies have described the direct responses of pulp cells following the application of resinous materials to pulp exposure. To address this issue, effects of exposure to an adhesive resin, 4-methacryloxyethyl trimellitate anhydride/metlyl methacrylate-tri-n-butyl borane (4-META/MMA-TBB) on cellular activity were investigated in established rat dental pulp cell line (RPC-C2A). Methods: RPC-C2A cells were cultured on the normal plastic plates or the disks prepared with 4-META/MMA-TBB (Super Bond® C&B, Sun Medical, Japan) iná-MEM containing 10% FBS. After 25 days and 30 days, DNA content and ALP activity were measured. Dead cell ratio in the culture was also evaluated with cytotoxicity assay kit after treatment with lower concentrations(0.1ìM or less) of 4-META/MMA-TBB. Moreover, total RNA in each group was extracted and RT-PCR analysis was performed. Results: At day 30, amount of DNA obtained from the cells on the normal plastic group and the one on the 4-META/MMA-TBB were comparable. In contrast, ALP activity in 4-META/MMA-TBB group was higher than in normal plastic group at day 30. Furthermore, cells in each group expressed mRNA of BMP-2 and ALP. 4-META/MMA-TBB (0.001ìM or less) did not influence dead cell ratio at the confluent state, indicating that exposure to this resinous material would not induce cytotoxic response in the pulp cells. Conclusions: 4-META/MMA-TBB does not have any direct toxic effects on the pulp cells, and stimulates cellular differentiation, suggesting that this resinous material could be usefully applied to the direct pulp-capping technique.