Abstract
BackgroundTo obtain prolonged clinical success with composite restorations, better bonding of resin to the tooth substrate is crucial.AimThe study was aimed to evaluate the microtensile bond strength (µTBS) of bulk-fill composite resin restorations when bonded to a cavity previously restored with amalgam, comparing with that of freshly prepared dentin.Materials and methodMesio-occlusal cavity preparations were done on 80 extracted human mandibular molars with a buccolingual width of 4 mm and a 1.5 mm axial depth by placing the gingival seat 0.5 mm coronal to the cementoenamel junction (CEJ) and were restored with fine-grain amalgam alloy. After thermocycling, the amalgam restorations were removed. Disto-occlusal cavities with similar dimensions of mesial cavities were prepared, and both the proximal surfaces were filled with bulk-fill composite using either etch-and-rinse or self-etch adhesives. Following thermomechanical cyclic loading, all the teeth were sectioned for µTBS testing. Bond strength data expressed in megapascals (MPa) were subjected to statistical analyses using analysis of variance (ANOVA) and Tukey’s multiple post-hoc tests.ResultsThe total-etch adhesive exhibited statistically higher bond strength values to both dentin substrates compared to self-etch adhesives (p<0.05). Failure mode analysis reported more of adhesive failures.ConclusionThe µTBS of bulk-fill composite resin restorations bonded to a cavity previously restored with amalgam was significantly lower than that of freshly prepared dentin. Total-etch adhesives bond strength was higher than self-etch adhesives to both the substrates tested.
Highlights
The use of composite resin materials through adhesive techniques is becoming a more popular procedure for replacing defective silver amalgam restorations
The total-etch adhesive exhibited statistically higher bond strength values to both dentin substrates compared to self-etch adhesives (p
Achieving a reliable bond between the tooth substrate and composite resin is critical for better retention with minimal microleakage, which, in turn, results in the clinical longevity of the restoration
Summary
The use of composite resin materials through adhesive techniques is becoming a more popular procedure for replacing defective silver amalgam restorations. Achieving a reliable bond between the tooth substrate and composite resin is critical for better retention with minimal microleakage, which, in turn, results in the clinical longevity of the restoration. Corrosion being the shortcoming of amalgam, over a period of time, deposits corrosive products at the interface, causing the discoloration of the underlying dentin [1]. This process, in turn, causes changes like reduced mineral volume, increased porosity of intertubular dentin, and degradation of collagen by host-mediated enzymes, all of which inevitably may have a negative impact on the performance of the adhesive bonding. To obtain prolonged clinical success with composite restorations, better bonding of resin to the tooth substrate is crucial
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