Abstract
Background: Repairing aged composite resin is a challenging process. Many surface treatment options have been proposed to this end. This study evaluated the effect of different surface treatments on the shear bond strength (SBS) of microhybrid composite resin repairs. Methods: Sixty-four cylindrical specimens of a Filtek Z2503M composite resin were fabricated and stored in 37°C distilled water for two weeks. The specimens were divided into 8 groups according to the following surface treatments: composite primer (group 1); composite primer + G-premio (group 2); composite primer + SE bond (group 3); roughening with coarse-grit diamond bur + composite primer + G-premio (group 4); roughening with coarse-grit diamond bur + composite primer + SE bond (group 5); Er,Cr:YSG + G premio (group 6) Er,Cr:YSG + Se bond (group 7); bulk composite (positive control group). Then the same composite resins were packed on specimens into layers. After being stored in distilled water for 24 hours, specimens were thermocycled. The SBS of the resin composites were tested with a universal test machine. Data was analyzed using one-way ANOVA and Tukey test (P < 0.05). Results: One-way ANOVA indicated no significant differences between groups 2, 3, 4, 5, 7 and control group. SBS of group 1 and 6 was significantly lower than control group. Surface treatment with diamond bur + composite primer + SE bond resulted in the highest bond strength. Conclusions: Surface roughening with bur and using sixth generation adhesives (SE bond) and eighth generation bonding agents (G-premio) and laser with sixth generation indicated similar result to intact composite, although use of composite primer did not lead to acceptable bond strength for repairing composite. However Clearfil SE bond show highest bond strength.
Highlights
Repairing aged composite resin is a challenging process
►► Surface roughening with bur and using sixth and eighth generation bonding agents are valuable way for composite repair initial steps of polymerization [10,11]
The highest shear bond strength (SBS) was obtained for B & composites between group 1 (CP) & SE and CP and SE and the lowest SBS was obtained for Laser & Gprimio
Summary
Repairing aged composite resin is a challenging process. Many surface treatment options have been proposed to this end. In spite of the considerable advances in resin composite components, marginal failures have occurred due to abrasion, discoloration, secondary decay, polymerization contraction, microleakage, poor anatomical form, pain and tenderness, which limit the composites’ lifetime [3,4,5,6,7,8] In these cases, selected treatments include repair or replacement of the entire restoration. A variety of methods has been proposed to obtain the bond strength between the old and new composite interface These techniques (including rinsing, Shokripor et al roughening surface with bur or disc, sandblasting, etching, use of silane and different bonding) are used to change the surface topography [14,15,16,17,18]
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