Shear bond strength of repaired composite resin restorations

This study was peformed to evaluate the interfacial shear bond strength of base (direct and indirect) and repair composites with aging and surface treatment methods. Direct composite resin specimens (, Heraeus Kulzer, Germany) were aged for 5 min, 1 hour, 24 hours, and 1 week in distilled water before surface treatment, and then divided into five groups Group 1, grinding; Group 2, grinding and application of bonding agent, Group 3, grinding, etching with 37% phosphoric acid for 30sec, and application of bonding agent, Group 4, grinding, etching with 37% phosphoric acid for 30sec, silane treatment, and application of bonding agent ; Group 5, grinding, etching with 4% hydrofluoric acid for 30sec. silane treatment, and application of bonding agent. Indirect composite resin specimens (, Heraeus Kulzer, Germany) were aged for 1 week in distilled water and divided into seven groups Group 1 - Group 5, equal to Charisma specimens; Group 6, grinding, etching with 37% phosphoric acid for 60sec, silane treatment, and application of bonding agent; Group7, grinding, etching with 4% hydrofluoric acid for 60 sec, silane treatment, and application of bond-ing agent. The repair material() was then added on the center of the surface (5 mm in diameter. 5 mm in height). The shear bond strength was tested and the data was analyzed using one-way ANOVA and the Student- Newman-Keuls test. The following conclusions were drawn. 1 The shear bond strength of specimens aged for 1 hour was significantly higher in Group 2 and Group 5 than in Group 1 (p specimens aged for 1 week was signifi-cantly higher in Group 3 and Group 5 than in Group 1 (p specimens, there was significant difference between the bond strength of 24 hours and that of 1 week (p specimens, the shear bond strength of specimens aged for 24 hours was significantly higher than the others(p specimens, 5. Most of the specimens showed cohesive fractures. Artglass^{\circledR}$ specimens that were etched with acid (phosphoric or hydrofluoric) for 30 sec showed more cohesive fractures.