Bonding durability of HEMA-free and HEMA-containing one-step adhesives to dentine surrounded by bonded enamel.

OBJECTIVE

To evaluate the bonding durability of HEMA-free and HEMA-containing one-step adhesives to dentine surrounded by bonded enamel after 1-year storage in water.

MATERIAL AND METHOD

Flat coronal dentine surfaces of extracted human molars were prepared, leaving the surrounding enamel. Two one-step self-etch adhesive systems: HEMA-containing Tri-S Bond (TSB; Kuraray Medical Inc., Tokyo, Japan) and HEMA-free G Bond (GB; GC Co., Tokyo, Japan), were applied to both dentine and the surrounding enamel surfaces according to manufacturers' instructions. Following resin composite crown (Clearfil AP-X, Kuraray Medical Inc., Tokyo, Japan) build-ups, the bonded specimens were stored in 37 degrees C water for 24h (control group), 3 months, 6 months and 1 year. After the designated periods of water storage, the specimens were serially sectioned perpendicular to the adhesive interface into 0.7 mm thick slabs, and then trimmed to form hour-glass configurations with a 1mm2 cross-sectional area. The micro-tensile bond strength (muTBS) test was carried out at a crosshead speed of 1.0mm/min. The muTBS data were statistically analyzed using two-way ANOVA, t test, and Tukey's HSD post hoc multiple comparison tests (alpha=0.05).

RESULTS

After 1 year water of storage, the bond strength of TSB to dentine was significantly lower compared with the 1-day, 3-month and 6-month groups (p<0.05). On the other hand, the muTBS of GB decreased over time, but there was no significant difference between the experimental periods (p>0.05).

CLINICAL SIGNIFICANCE

Bonded enamel margins may not maintain the integrity of the resin-dentine interface created by HEMA-free and HEMA-containing one-step adhesives.