Influence of chlorhexidine dentin disinfection on universal adhesive performance: Interfacial adaptation and bond strength assessments

Abstract

Purpose: This study aimed to investigate the effect of chlorhexidine (CHX) cavity disinfectant on interfacial microleakage and micro-tensile bond strength (μTBS) of a universal adhesive bonded to dentin in both self-etch (SE) and etch-and-rinse (ER) modes.

Methods: Class I cavities were prepared in the coronal dentin of extracted human teeth and assigned to two etching modes (SE or ER), then subdivided by disinfection with or without CHX (n = 5). Cavities were restored using Single Bond Universal Adhesive and Filtek Z350 XT composite. After 10,000 thermal cycles, interfacial microleakage was assessed on serial B-scans obtained for each specimen using cross-polarization optical coherence tomography. For μTBS testing, resin composite was bonded to dentin discs, sectioned into beams, and subjected to tensile load until failure using a universal testing machine. Failure modes in fractured beams were analyzed under a stereomicroscope and categorized as adhesive, cohesive, or mixed. ANOVA with Bonferroni post-hoc at a significance level of 0.05 was used to compare the groups.

Results: Microleakage was not significantly influenced by the etching mode or CHX disinfection (p-value = 0.068). For μTBS, the ER group exhibited the highest values, and CHX disinfection did not significantly alter these results (p-value = 1.000). In contrast, the SE-CHX group displayed significantly lower μTBS than the ER, ER-CHX, and SE groups (p-values of <0.001, <0.001 and 0.012, respectively). ER mode primarily resulted in adhesive failures, regardless of CHX. SE group exhibited both adhesive and cohesive failures, while SE-CHX mostly showed adhesive failures.

Conclusion: The use of CHX disinfectant influences the bonding performance of universal adhesive differently depending on the application mode. Specifically, in the SE mode, CHX adversely affects bond strength to dentin. This suggests that when using universal adhesives in SE mode, clinicians should carefully consider the use of CHX disinfectants, as they may interfere with the adhesive's effectiveness.

Fig 1. Schematic illustration of the study design.

This figure is for illustrative purposes only; the individual elements are similar but not identical to the originals.

Fig 2. Representative cross-sectional images of selected specimens from ER and ER-CHX groups, along with corresponding binary images after binarization of the interfacial area.

(a) B-scan of a specimen from ER group, showing increased signal intensity and diffuse reflections at the cavity floor. Bright pixels in the corresponding binary image highlight interfacial microleakage. (b) B-scan of a specimen from ER-CHX group, similarly revealing interfacial microleakage at the cavity floor, with bright pixels in the binary image indicating areas of leakage. C: resin composite; D: dentin.

Fig 3. Representative CP-OCT images obtained from specimens of SE and SE-CHX groups, along with corresponding binary images of the resin composite-dentin interface at the cavity floor.

(a) B-scan of a specimen from SE group, showing a few scattered areas of increased signal intensity at the cavity floor. The binary image highlights these areas as isolated bright pixels along the interfacial region. (b) B-scan and binary image of a selected interface from SE-CHX specimen, showing slightly more microleakage than the SE specimen. C: resin composite; D: dentin.