Response of class II molecule-expressing cells and macrophages to cavity preparation and restoration with 4-META /MMA-TBB resin

Aim The aim was to test the hypothesis that the resin and bonding agent 4-META/MMA-TBB (4-META), has the potential to prevent transdentinal antigenic challenges. Methodology Class I cavity preparation and immediate restoration with 4-META were made in the maxillary right first molars of 36 six-week-old Wistar rats. Contralateral teeth with an unrestored cavity served as positive control (cavity without 4-META) group. The maxillary first molars of 12 age-matched normal rats (total 24 teeth) were also examined as negative control (intact tooth group). At 3 or 28 days after cavity preparation, the teeth were subjected to immunoperoxidase staining using OX6 (anticlass II molecules) and ED1 (antimacrophages) as primary antibodies. Results A total of 10 teeth were not available for histological examination. In the teeth filled with 4-META at 3 days, the density of OX6+ and ED1+ cells in the coronal pulp was significantly higher than that in the intact tooth group. At 28 days, formation of sound reparative dentine was noted and the density of the immunocompetent cells was comparable to the intact teeth. In the teeth without 4-META at 3 days, pulpal abscess was observed in 14 out of 16 and the density of OX6+ and ED1+ cells was significantly increased (P < 0.001, paired t-test) compared with the 4-META group. Partial pulp necrosis had developed in the teeth without 4-META at 28 days. Conclusions Restoration with 4-META significantly reduced transdentinal antigenic challenges. This property may have special implications for 4-META's capacity to protect the dentine/pulp complex.