Effect of chlorhexidine concentration on themechanical properties of dental adhesive resins

Abstract

Introduction: Matrix metalloproteinases (MMP) have been impli-cated in collagen degradation within the hybrid layer. Incorpora-tion of chlorhexidine, a potent MMP inhibitor, into dentaladhesive resin may help to prevent dentin bond degradation. Theobjective of this study was to investigate the effect of chlorhexidineconcentration on the mechanical properties of experimental dentaladhesive resins.Materials and methods: Resin ÔIÕ beams and discs were preparedfrom three light-cured, experimental copolymer blends (R1, R2 andR3) containing 0.0, 1.0 and 2.0 wt% chlorhexidine diacetate (CDA).The flexural strength (FS) and flexural modulus (FM) weremeasured using three-point flexural tests after 24 h dry and wetstorage. FS and FM were analyzed using two-way ANOVA, withresin material, CDA concentration and storage time as independentfactors. Knoop hardness was analysed using two-way ANOVA,with resin material and CDA concentration as independent factors.Results: Incorporation of CDA had no significant effect on FS ofdry and wet R1, R2 and R3 specimens. FM of dry R1, R2 and R3specimens decreased significantly (P < 0.05) with increasing con-centration of CDA. No significant effect of CDA on FM of wetR1, R2 and R3 specimens was observed. In general, FS and FM ofneat and CDA-incorporated R1, R2 and R3 specimens decreasedsignificantly (P < 0.05) following water storage. Addition of CDAsignificantly (P < 0.05) reduced the Knoop hardness of dry R1,R2 and R3 specimens.Conclusion: Chlorhexidine decreased the flexural modulus andKnoop hardness of copolymer blends; no significant effect onmechanical properties was observed under wet conditions.