Effect of adhesive liner on the shear bond strength of indirect restoration to enamel and dentin

Purpose: This study investigated whether the bonding of a resin inlay to enamel and dentin could be improved by applying both an adhesive system and a low-viscosity microfilled resin to the underlying tooth substrate. Materials and Methods: A self-etching primer system (Clearfil SE Bond) and a low-viscosity microfilled resin composite (Protect Liner F) was applied to one half of enamel or dentin slices, with the remaining slices served as non-lined specimens, with only Clearfil SE Bond applied. Composite inlays (Estenia) were fabricated indirectly and cemented with a dual-cured resin cement (Panavia Fluoro Cement). After 24-hour storage in 37 ̊C water, the bonded inlays were subjected to a micro-shear bond test, whereby a shear force was applied to the inlays. The data were compared with observations of the directly placed controls (Clearfil SE bond and Clearfil AP-X); statistical analysis was carried out using ANOVA and Fisher's PLSD test. Morphological observations using confocal laser scanning microscopy were also performed. Results: The enamel surfaces did not show any a statistical difference between the shear bond strength values observed in the lined and non-lined groups (p>0.05). However, the bonding capacity of Estenia inlay with the liner to dentin was slightly higher than that of the non-lined restoration. The bonding of indirect restorations to enamel was almost the same as that of the directly placed resin composite (p>0.05). Conclusion: The resin liner might improve the bonding of resin cement to dentin, whereas no effect was observed on enamel. The results of the present study suggest that, from the perspective of shear stress, it seems advantageous if an adhesive layer on the cavosurface enamel were thin rather than thick. (Int Chin J Dent 2003; 3: 36-44.)