Microtensile Bond Strength of Porcelain Laminate Veneers Bonded to Fluorosed Teeth

Abstract

The aim of this study was to evaluate the microtensile bond strengths (MTBSs) of porcelain laminate veneers bonded to normal and fluorosed teeth. Forty human incisors, including 20 normal and 20 moderately fluorosed teeth [Thylstrup Fejerskov Index (TFI) = 4 to 6], were collected. The labial surfaces of the teeth were ground up to 1 mm and polished with #600 silicon carbide abrasive paper. The surfaces were bonded to 1-mm-thick ceramic slices (5 x 5 mm(2)) previously made (VitaVM7) using one of two ceramic cement systems (RelyX or Clapearl) following the manufacturers' instructions. A resin composite was added on top of the ceramic slices and built up to 5-mm thickness to serve as grips. The specimens were stored in water (37 degrees C) for 24 hours, and beams of adhesive interface with a surface area of approximately 1.25 mm(2) were obtained. Then the beams were subjected to MTBS tests at a crosshead speed of 1.0 mm/min. The data were analyzed with two-way ANOVA. The results of the MTBS test (MPa) were 20.55 +/- 5.83 (RelyX/fluorosed), 20.16 +/- 4.61 (RelyX/normal), 18.74 +/- 2.88 (Clapearl/fluorosed), and 21.06 +/- 4.99 (Clapearl/normal). There were no significant differences in the MTBSs among the four groups (p > 0.05). The MTBSs of ceramic cement systems used were not influenced by the moderately fluorosed teeth.