This study was performed 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 (Charisma®, Heraeus Kulzer, Germany) were aged for 5 min, 1 hour, 24 hours, and 1 week in 37℃ 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 (Artglass®, Heraeus Kulzer, Germany) were aged for 1 week in 37℃ 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 bonding agent.

The repair material(Charisma®) 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 Charisma® specimens aged for 1 hour was significantly higher in Group 2 and Group 5 than in Group 1 (p<0.05), and that of Charisma® specimens aged for 1 week was significantly higher in Group 3 and Group 5 than in Group 1 (p<0.05). No significant difference was found in the bond strength of specimens aged for 5 min and 24 hours.

2. In Group 2 of the Charisma® specimens, there was significant difference between the bond strength of 24 hours and that of 1 week (p<0.05).

3. In Group 4 of the Charisma® specimens, the shear bond strength of specimens aged for 24 hours was significantly higher than the others(p<0.05).

4. There was no significant difference between the shear bond strength of the Artglass® specimens.

5. Most of the Charisma® specimens showed cohesive fractures. Artglass® specimens that were etched with acid (phosphoric or hydrofluoric) for 30 sec showed more cohesive fractures.