Bonding of acid-etch and self-etch adhesives to human fluorosed dentine

The objective of our laboratory study was to determine the bonding efficacy of two-step self-etching primer system (Clearfil SE Bond), all-in-one adhesive (Clearfil Tri S Bond) and acid-etching system (Single Bond) to human fluorosed dentine.

Forty-eight human molars were grouped according to modified Thylstrup-Fejerskov index (TFI) into normal (N, TFI 0), mild fluorosis (ML, TFI 1-3) and moderate fluorosis (MD, TFI 4-6). Superficial dentine was exposed and ground with 600-grit silicon carbide paper. Teeth of each group were randomly divided into three sub-groups. Each sub-group was treated with one of the three bonding systems. A resin composite was built up on the bonded surfaces and stored in water at 37 degrees C for 24h. They were serially sectioned in buccal-lingual direction into 0.7-1.0mm thick slabs. Slices were trimmed for microtensile bond test and stressed in tension at a crosshead speed of 1mm/min. The data were analyzed with two-way ANOVA (p=0.05). The adhesive/dentine interfaces of the bonded specimens were examined by a FE-SEM.

Significantly higher microtensile bond strength (microTBS) was found with Clearfil SE Bond to mild fluorosed dentine than did Single Bond and Clearfil Tri S Bond. Lower microTBS were found for Single Bond (not significant) and Clearfil Tri S Bond than Clearfil SE Bond with moderately fluorosed dentine. Thickness of the hybrid layer produced by Clearfil SE Bond in mild and moderately fluorosed groups was less than with normal dentine.

Two-step self-etching system, Clearfil SE Bond, showed a higher bonding performance to fluorosed dentine than Single Bond and Tri S Bond.