Comparative Evaluation of Effect of Different Surface Pretreatments on Bond Strengths of Thermocycled Composite and Amalgam Rerestored with Composite Resin: An In Vitro Study

Abstract

Purpose:The purpose of this in vitro study was to evaluate the effect of different surface pretreatment methods on bond strengths of aged composite and aged amalgam rerestored with composite resin. Materials and methods: A total of 72 specimens measuring 5 × 5 × 3 mm were fabricated. A total of 36 composite resin specimens and 36 amalgam specimens were fabricated using customized metallic molds. All the samples were artificially aged by thermocycling (5,000 cycles, 5°-55°C) and then stored in artificial saliva for 1 month. The specimens were divided into six groups (each having 12 specimens) based on different surface treatments (group I-aged composite treated with diamond bur; group II-aged composite treated with diamond bur and silane coupling agent; group III-aged composite treated with air abrasion and silane coupling agent; group IV-aged amalgam treated with diamond bur; group V-aged amalgam treated with diamond bur, metal bond, and silane coupling agent; and group VI-aged amalgam treated with air abrasion metal bond and silane coupling agent). All specimens were then rerestored with composite restoration and again kept for thermocycling. The specimen was tested under universal testing machine for shear bond strength. Statistical analysis was done using analysis of variance (ANOVA) and post hoc analysis. Results: Aged composite treated with air abrasion and silane coupling agent (group III) exhibited the maximum bond strength with a mean of 52.3385 ± 10.656 MPa, followed by aged composite treated with diamond bur and silane coupling agent (group II) with a mean of 50.653 ± 13.182 MPa. The least strength was displayed in aged amalgam treated with diamond bur (group IV) with a mean of 26.3 ± 9.421. One-way ANOVA showed statistically significant difference (p = 0.001) among the groups. Conclusion: Aged composite treated with air abrasion and silane coupling agents increases the bond strength of the repaired composite efficiently. Mechanical surface treatment of aged amalgam along with silane coupling agent and metal bond in cases amalgam repair with composite also improves the bond strength and can be a better alternative in such cases.