Shear bond strengths to dentin and fluoride release from fluoride-containing liners

The purpose of this study was to determine the shear bond strengths of five commercially available fluoride-containing restorative systems to dentin and to evaluate the fluoride release from them. The five systems evaluated were: (A) Vitrabond/Silux; (B) Zionomer Powder Liquid/Perfection; (C) Zionomer Paste Paste/Perfection; (D) TimeLine/Prisma-Fil; and (E) GC Dental Cement/Fuji II. Eighteen test specimens were prepared on the dentin surfaces of extracted human permanent first and second molars ground on 600 grit SiC paper with each system. The bonded cylinders were removed from the assembly apparatus 15 minutes after cure, stored in physiological saline at 37 degrees C for 24 hours and subjected to a shear load at 0.5 mm/min. Five cylindrical specimens were prepared for each system, the discs were suspended in 25 microL glass distilled water and the fluoride release (microgram F/mm2) determined at daily intervals for 15 days and then after 30 and 90 days. The data were analyzed by a one-way analysis of variance and Duncan's multiple range test. The following shear bond strengths (Mean +/- SD) were recorded (MPa): A: 8.86 +/- 1.49; B: 4.24 +/- 1.23; C: 4.41 +/- 1.39; D: 3.85 +/- 1.60; E: 4.81 +/- 1.21. With all the systems, the fluoride release dropped sharply during the first 7 days and then remained constant. The shear bond strength and the fluoride release from Vitrabond/Silux were significantly greater than that of the other systems.