Effect of etchant type and the use of silane on the shearbond strength of composite resin to porcelain.

Abstract

Background: This study was formulated to compare the effect of 5%hydrofluoric acid in comparison to37%phosphoric acid with and without the application of silane on bond strength of composite to porcelain.Materials and Methods: Specimen preparation was divided in to two phases, metal-disks fabrication (8mm-diameterand 4mm-thickness) and ceramic veneering. Thirty two specimens were prepared, sandblasted with 50 μm aluminumoxide, and divided into four groups of eight samples. Groups I and III were etched with 37%phosphoric acid whilegroups II and IV were etched with 5%hydrofluoric acid; and groups I and II were silaneted while groups III and IV werenot. Heliobond, and resin composite were applied to each specimen using a plastic transparent split mold (4mmdiameterand 4mm-height). Specimens were stored in distilled water for 24 hours then thermocycled for 100 cycles.Shear bond strength was determined by a Zwick universal machine at a cross-head speed 5 mm/minute.Results: Mean shear bond strength values were 21.02(group I), 23.31(group II), 4.00(group III), and 18.60(group IV).Paired-t revealed that specimens treated with 5%hydrofluoric acid were significantly higher than those treated with37%phosphoric acid regardless the use of silane. The use of silane dramatically enhanced the bond strength ofcomposite resin to porcelain for both acids. All specimens treated with 37%phosphoric acid without silane showedadhesive failure, while those treated with 5%hydrofluoric acid showed mostly cohesive failure within ceramic.Conclusion: Silane improved the shear bond strength of composite to ceramic, and hydrofluoric acid performedgreater bond strength compared to phosphoric acid.