Biological Effects of a Restorative Material During Ex-Vivo Culture

Testing of dental materials has limited investigations on their effects on pulp cell behaviour. Whilst there is greater understanding of the therapeutic mode of action of calcium hydroxide, suggesting a role in mediating tissue repair, there is little biological evidence for similar reparative effects of currently used resin bonding agents in restorative dentistry. Objectives: To investigate effects of a commercially available self etch resin bonding agent on the pulp using an ex-vivo culture system. Methods: Transverse 2mm think sections were prepared from incisor teeth extracted from 28 day old male Wistar rats. Affi blue agarose beads were soaked in commercial bond and either polymerised or left in the unpolymerised phase and applied to the pulpal tissue in the tooth slices. Cultures were maintained for 1 and 5 days prior to histological processing for microscopic analysis. Beads soaked in PBS and slices cultured in the absence of beads served as controls. Scanning electron microscopy (SEM) was used to confirm adhesion of bond to agarose and tissue were examined histological following culture. Results: SEM demonstrated bond coating of beads confirming these as an appropriate material carrier. All control cultures showed maintenance of cell and tissue architecture throughout the culture periods, minimal tissue damage at the site of bead application. In cultures with un-polymerised bond, formation of a fibro-cellular lining around the bead with close bead-cell integration was observed. Polymerised bond appeared to induce a clear space between bead and cells. No clear evidence of cytotoxicity was observed in cultures with beads coated with either phase despite direct pulpal application. Conclusions: These preliminary results demonstrate that a commercially used bonding agent can stimulate tissue responses within the dental pulp following culture, with little cytotoxicity and suggest that direct pulp capping with resin based materials should be investigated further. (Supported by Welsh Assembly Govnt).