Investigating the addition of collagen and its integrin binding sequence (RGD) to glass polyalkenoate: In terms of material and cellular properties to explore a more biocompatible method of root caries restoration.

AIMS: Placement of a restoration to treat root caries disrupts many tissues. There is scope for the restorative material to interact with these to augment reductions in micro leakage afforded by an adhesive restorative material. OBJECTIVES: 1) To investigate the effects of incorporating bioactive molecules into a glass polyalkenoate (GPA) 2) To quantify the changes in physical properties of the material. METHODS: Biocompatibility of the GPA cement (Chemfil Superior, Dentsply De Trey, Konstanz, Germany) in unmodified and modified forms was ascertained using cell culture techniques. The optimum concentration of bioactive components required to promote cell attachment was determined indirectly by quantification and localisation of the fibroblast marker vimentin. The properties of surface hardness, compressive strength and adhesive bond strength were also determined prior to and following addition of the bio-additives: collagen type I and a pentapeptide containing Arg-Gly-Asp (RGD). RESULTS: Addition of Type I Collagen (100µg/ml) and RGD (5mg/ml) to ChemFil Superior had no statistically significant effect upon the compressive strength and bond strength to bovine enamel but significantly (P<0.05) increased the materials shore hardness. The addition of RGD to ChemFil Superior increased most the expression of vimentin, indicating that the cells had become more fibroblastic. This may be indicative of increased synthesis of extracellular matrix macromolecules with the potential to foster adhesion of the modified glass polyalkenoate to distracted gingival tissues. CONCLUSIONS: The results suggest that addition of bioactive molecules to GPA cement for subgingival restorations has potential clinical applications. CLINICAL SIGNIFICANCE: It is possible to envisage that the additions, as described in this paper, could foster the attachment of displaced gingival tissues to GPA restorative materials placed subgingivally where root caries has been treated. This would offer potential to form a seal around the restoration by the attached gingival tissues avoiding a periodontal pocket and depriving residual cariogenic bacteria of a nutrient supply. Further investigation of the effects upon other similar materials of such additions is warranted.