Pulpal cell reaction to Bis-GMA adhesive resin

Objectives: To develop biocompatible adhesives cellular response of rat pulpal cell to Bis-GMA adhesive resin was investigated. Methods: Clearfil Linerbond 2V (Kuraray, Japan) was polymerized in two different ways (one in air at room temperature for 24 hours and the other under CO₂ at 60°C for 24 hours). Pulpal cells were isolated from incisors of Lewis rats with an enzymatic treatment (0.2% collagenase and 0.25% trypsin). The cells were seeded on the resins at an initial density of 1.5 x 10⁴ cells / cm², and cultured with DMEM + 10% FBS. 1) The number of cells was counted after 1, 3, 7 and 14 to examine the influence of the unpolymerized superficial layer, 2) Identification of dissoluted ingredients from the internal part of the anaerobically polymerized resin was performed, 3) Their concentration change with time was measured by GCMS, 4) Cell response to the ingredients was examined, and 5) Cell proliferation was examined on the resin which was preincubated in the medium for 24 hours for releasing the ingredients. Results: The unpolymerized resin layer caused fatal damage to the cells. The anaerobically polymerized resin also significantly reduced the proliferation (t-test, p<0.01). Dissolution of CQ, HEMA and reducing agents was mostly admitted within first 24 hours. The cell proliferation was slightly improved on the 24 hour-preincubated resin but was still restrained compared with the control, though it was not severely inhibited by each ingredient in such elution concentrations (p<0.01). Our other studies suggest that acute toxicity due to high degree of local concentration of the disoluting ingredients or the genotoxicity might inhibit the proliferation of the pulpal cell. Conclusions: Both the unpolymerized resin layer and the dissoluted ingredients of Bis-GMA adhesive might affect the proliferation of rat pulpal cells.