Bonding to ground versus unground enamel in fluorosed teeth

Objectives To determine the effect of grinding on the bonding effectiveness of a self-etch and an etch-and-rinse adhesive to fluorosed enamel. Methods The teeth were classified using the Thylstrup and Fejerskov index (TFI). Fluorosed teeth (TFI = 5) obtained from Isparta (Turkey) and control teeth (TFI = 0) obtained from Leuven (Belgium) were used. Using a depth-marking diamond bur, 0.3 mm of enamel was removed from mid-buccal and mid-palatal/lingual surfaces of the teeth, whereas the area adjacent to the ground area was left unprepared. A two-step self-etch (Clearfil Protect Bond, Kuraray) and a three-step etch-and-rinse adhesive (Optibond FL, Kerr) were used to bond the resin composite to the ground and unground enamel. Rectangular micro-specimens were prepared using the slow-speed diamond saw and tested in tensile to determine the micro-tensile bond strength (μTBS). Results The μTBS to unground fluorosed enamel was significantly lower than to ground fluorosed enamel for Clearfil Protect Bond (15.8 ± 15.2 and 45.0 ± 12.4 MPa, p < 0.0001) and for Optibond FL (35.5 ± 21.4 and 50.5 ± 12.3 MPa, p < 0.05), respectively. In control teeth, Clearfil Protect Bond bonded better to ground enamel (p < 0.01), whereas OptiBond FL exhibited a similar bonding effectiveness to ground and unground enamel (p = 0.0634). Significance Preparation of enamel improved the resin–enamel bond strength in fluorosed teeth. The bonding effectiveness to unground enamel was lower in fluorosed teeth than in control teeth for the self-etch adhesive tested.