Effects of different surface treatments on the bond strength of glass fiber-reinforced composite root canal posts to composite core material

Abstract

Background/purpose: The purpose of this study was to investigate the effects of different surface treatments on the bond strength of glass fiber-reinforced composite (FRC) posts to composite core material. Materials and methods: A total of 18 FRC posts were randomly divided into six groups (n = 3), one of which was the untreated control group. Surface treatment of other groups were as follows: airborne particle abrasion with 50-mu m Al2O3 powder at 60 psi for 10 seconds through a nozzle distance of 10 mm; etching with 4% hydrofluoric (HF) acid; and surface preparation with an Er:YAG laser under three different power settings (of 300, 400, and 500 mJ, at 2 Hz and 100 mu(s)). A cylindrical Teflon mold was used to surround the treated posts, and the mold was filled with dual-cure composite core material. All samples were light-cured for 60 seconds through the top of the mold. After 24 hours of storage in water, specimens were sectioned perpendicular to the bonded interface under water cooling to obtain 2-mm thick post-and-core specimens. Each group consisted of 12 specimens. Push-out tests were performed at a cross-head speed of 0.5 mm/minute using a universal testing machine. Data were analyzed by one-way analysis of variance followed by Tukey's honestly significant difference test (alpha = 0.05). Results: The lowest bond strength was observed in the Er:YAG 500-mJ group (6.14 +/- 0.94 MPa). The acid-etched group revealed a higher bond strength (15.08 +/- 0.92 MPa) than the control group. The highest bond strength was observed in the airborne-particle abrasion group [18.89 +/- 0.83 MPa (P < 0.05)]. Conclusion: Er:YAG laser treatments on the FRC post surface decreased the bond strength. Airborne-particle abrasion and HF acid etching are alternative methods for increasing bond strength of FRC posts to composite core material. Copyright (c) 2012, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved.