Effect of Remineralisation with Nano-hydroxyapatite (nHAp) and Non-collagenous Protein Analogues (PAA and STPP) on the Micro Tensile Bond Strength of the Resin Composites to Dentin – An In vitro Study

Abstract

Background: Resin-dentin bonds are less durable than enamel as they rely on organic part for mineralisation. Bond denaturation mainly takes place because of hydrolysis of polymerized resin or degradation of water-rich, resin-sparse collagen by collagenolytic endogenous matrix metalloproteinase and cysteine cathepsins. Hence, this limited stability of dentin bonding tenaciously reduces the longevity of tooth-coloured restorations. One of the strategies adopted to encounter this shortcoming is to induce biomimetic remineralisation. Aim: To assess the microtensile bond strength of resin composites to dentin following remineralisation using an experimental paste containing nano-hydroxyapatite (nHAp) and biomimetic analogues, Poly Acrylic Acid (PAA) and Sodium Tri Polyphosphate (STPP). Methodology: Nine intact freshly extracted third molar were used for this study to evaluate the microtensile bond strength after treating with three different groups; Group I with paste containing nano hydroxyapatite nHAp Group II paste containing nHAp and non-collagenous protein analogues such as (Polyacrcrylic acid and Sodium tripolyphosphate) and the control groups containing adhesive and resin composite with no additional treatment. The samples were observed over a period of 24 hours and 1 week the inter group data analysis was done using ANOVA and paired sample t test and the intra-group data analysis over period of 24 hours the post HOC Bonferroni test was used for the statistical analysis. Results: After 24 hours the group with nHAp group showed highest value for microtensile bond strength among other groups, however after one week the group with nHAp +NCP analogues(PAA+STPP) showed highest value for microtensile bond. Conclusion: The treatment with the experimental paste [nHAp+NCP] analogues (PAA+STPP)] can bring about remineralisation to improve bonding to dentin.