The effect of resin infiltration and oxidative pre-treatment on microshear bond strength of resin composite to hypomineralised enamel

Background Reduced bond strengths of resin composites to hypomineralised enamel increase restorative failure. Aim To investigate if the adhesion of resin composite to hypomineralised enamel can be improved by pre‐treatments: resin infiltration, oxidative pre‐treatment followed by a resin infiltration, or oxidative pre‐treatment. Design Twenty‐one enamel specimens in each of five Groups: 1) Normal enamel; 2) Hypomineralised enamel; 3) Hypomineralised enamel pre‐treated with a resin infiltrant, (Icon®); 4) Hypomineralised enamel pre‐treated with 5.25% sodium hypochlorite then treatment with resin infiltrant; 5) Hypomineralised enamel pre‐treated with 5.25% sodium hypochlorite. A resin composite rod was bonded to each specimen using Clearfil™ SE bond as the adhesive (hereafter termed ‘routine bonding’), then subjected to microshear bond strength (MSBS) testing. Results Overall, the mean MSBS between the five groups differed significantly (P = 0.001). Pre‐treatment of hypomineralised enamel with 5.25% sodium hypochlorite with or without subsequent resin infiltration in Groups 4 and 5 prior to routine bonding resulted in increased mean MSBS compared to Groups 2 and 3, with mean MSBS values not differing significantly when compared to routine bonding to normal enamel. Conclusion Increased bond strength of resin composite to hypomineralised enamel was obtained by pre‐treatment of hypomineralised enamel specimens with 5.25% sodium hypochlorite with or without subsequent resin infiltration.