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.