Exploring the Effect of Saliva Contamination on Shear Bond Strength of Dental Adhesives

Background: Contamination of saliva during restorative procedures may be one of the most common clinical concerns in adhesive dentistry. It may interfere with adhesive systems-dentin interaction, and eventually lead to shear bond strength (SBS) loss and influence the restoration longevity. Systems that are generally employed are the etch-and-rinse and self-etch adhesives but sensitivity to salivary contamination is a major issue. The objective of the present study was to determine how saliva contamination influences the SBS of these adhesive systems. Methods: This comparative in-vitro study was conducted on 120 human premolars that had been extracted. The teeth were randomly subdivided into four sets (n = 30 each): Group A (etch-and-rinse without contamination), Group B (etch-and-rinse with saliva contamination), Group C (self-etch without contamination), and Group D (self-etch with contamination). Preparation of composite build-ups was done then SBS testing done using universal testing machine. Failure modes were evaluated under the stereomicroscopy. Statistical analyses were ANOVA, independent t-tests, chi-square tests. The significant p-value was assumed to be less than 0.05. Results: The maximum SBS was noted in etch-and-rinse that was not contaminated with saliva (Group A; 22.4 ± 2.8 MPa) and significantly lower in saliva-contaminated etch-and-rinse (14.1 ± 3.2 MPa, p = 0.001). The bond strength of self-etch adhesives was relatively lower in general (Group C: 18.3 ± 2.9 MPa), although contamination resulted in a weaker drop (Group D: 13.9 ± 2.7 MPa, p = 0.01). A failure mode analysis revealed that there were higher adhesive failures in contaminated groups (p = 0.002). Conclusion: Saliva contamination greatly compromises the SBS of both adhesive systems with the etch-and-rinse more susceptible. Proper moisture management and selection of adhesives are very important to long-term restorative success.