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Examining the Bond Strength of Universal Adhesive to Dentin Contaminated with Amalgam in Resin Composite Restorations
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T Rostamzadeh    , M Rashidabadi , Z Hadian , A Hasanzade Haghighi * |
| 2.Department of Orthodontics, School of Dentistry, Guilan University of Medical Sciences, Rasht, I.R.Iran. , azadehh.hsnzd@gmail.com |
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Abstract: (418 Views) |
Background and Objective: Amalgam has long been used in restorative dentistry, but its replacement with composite resin raises concerns about dentin contamination compromising adhesion. This study aimed to evaluate the bond strength of universal adhesive to amalgam-contaminated dentin in resin composite restorations.
Methods: In this in-vitro study, 32 sound premolars were divided into 8 groups (n=4, 2 samples per tooth): G1 and G2 as control groups (self-etch and etch-and-rinse modes on intact dentin, respectively). G3 and G4 (self-etch and etch-and-rinse modes on amalgam-contaminated dentin, respectively). G5 and G6 contaminated dentin with chlorhexidine treatment (self-etch and etch-and-rinse, respectively). G7 and G8 (contaminated dentin with 0.5 mm dentin removal in self-etch and etch-and-rinse, respectively). After occlusal enamel removal, all groups except controls received amalgam restorations. Following thermocycling (10,000 cycles, 5-55°C), amalgam was removed. The dentin surfaces were bonded with universal All-Bond Universal and restored with composite cylinders. All groups underwent a second identical thermocycling protocol before microshear bond strength (μSBS) testing (0.5 mm/min). The fracture patterns were examined with a stereomicroscope.
Findings: According to the results, the control groups (G1 and G2) showed the highest mean bond strength, 17.80±3.87 MPa and 18.88±3.44 MPa, respectively. In contrast, the dentin removal groups (G7 and G8) had the lowest values, 12.89±3.45 MPa and 13.84±4.35 MPa, respectively. The groups G1 and G2 exhibited significantly higher µSBS than certain other groups (G7, G4, G8), while the chlorhexidine pre-treated groups (G5, G6) showed no statistically significant differences. No significant correlation was found between bond strength and failure types (p=0.425), nor between failure patterns and etching methods (p>0.05).
Conclusion: The self-etch mode on contaminated dentin performed similarly to intact dentin. Chlorhrxidine preserved bond strength, while excessive dentin removal is discouraged. |
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| Keywords: Chlorhexidine, Dentin Refreshment, Microshear Bond Strength, Universal Adhesive. |
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Type of Study: Experimental |
Subject:
Restorative Dentistry
Received: 2025/05/9 | Accepted: 2025/11/5
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