|
An Evaluation of the Bond Strength of Universal Adhesives to Amalgam-Contaminated Dentin in Resin Composite Restorations
|
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 |
|
|
Abstract: (834 Views) |
Background and Objective: The substitution of amalgam restorations with composite resin has consistently been a matter of clinical concern, primarily due to the potential for dentin contamination by residual amalgam particles and the subsequent adverse effects on adhesive bond strength. This study aimed to evaluate the microshear bond strength of a universal adhesive to amalgam-contaminated dentin in composite resin restorations.
Methods: In this in vitro study, a total of 32 sound premolar teeth were randomly assigned to 8 experimental groups, with 4 teeth per group and 2 bonded specimens prepared from each tooth. The groups were defined as follows: G1 and G2 served as negative controls (healthy, non-contaminated dentin) using self-etch and etch-and-rinse adhesive application modes, respectively. G3 and G4 received contaminated dentin treated with self-etch and etch-and-rinse modes, respectively. G5 and G6 received contaminated dentin followed by application of 2% chlorhexidine prior to adhesive application in self-etch and etch-and-rinse modes, respectively. G7 and G8 received contaminated dentin followed by removal of a 0.5 mm layer of superficial dentin, again using self-etch and etch-and-rinse modes, respectively. After the occlusal enamel was removed, all groups except the control groups received amalgam restorations. The specimens were then subjected to thermocycling (10,000 cycles, temperatures ranging from 5°C to 55°C). Subsequently, the amalgam was removed, and a universal adhesive was applied to the dentin surfaces, followed by fabrication of composite resin cylinders. Microshear bond strength (μSBS) was measured at a crosshead speed of 0.5 mm/min after additional thermocycling, and failure patterns were examined using a stereomicroscope.
Findings: The highest mean bond strength values were observed in the control groups: G1 (self-etch) yielded 17.80±3.78 MPa, and G2 (etch-and-rinse) yielded 18.88±3.44 MPa. In contrast, the lowest values were recorded in the dentin removal groups: G7 (self-etch) at 12.89±3.45 MPa and G8 (etch-and-rinse) at 13.84±4.35 MPa. Statistical analysis revealed that the bond strengths of G1 and G2 were significantly superior to those of G4 (contaminated dentin, etch-and-rinse), G7, and G8. However, groups pretreated with 2% chlorhexidine (G5 and G6) did not demonstrate statistically significant differences compared to controls. Furthermore, no significant association was found between bond strength values and failure types, nor between failure patterns and the etching mode employed.
Conclusion: The findings of this study revealed that the universal adhesive system, when used in self-etch mode, produced bond strength results on amalgam-contaminated dentin that were similar to those obtained on healthy, non-contaminated dentin. Furthermore, the application of 2% chlorhexidine helped preserve bond strength values. Conversely, the removal of excessive dentin (0.5 mm) is not recommended as it led to reduced bond strength. |
Article number: e25 |
| Keywords: Universal Adhesive, Dentin Adhesion, Microtensile Bond Strength, Chlorhexidine. |
|
|
Full-Text [PDF 894 kb]
(34 Downloads)
|
Type of Study: Experimental |
Subject:
Restorative Dentistry
Received: 2025/05/9 | Accepted: 2025/11/5 | Published: 2026/07/1
|
|
|
|
|
|
|
| Send email to the article author |
|
|
