Adhesion of atraumatic restorative treatment materials simulating challenging clinical conditions: a focus on the effect of saliva contamination, dentin level, and caries affection

This study assessed the micro-shear bond strength (μSBS) of glass-ionomer cements (GIC) and glass hybrids (GH) comparing to a conventional resin composite under different saliva contamination conditions, dentin levels, and caries affection. Caries-free (CF) human molars (N = 60) were collected and randomly divided into six groups [CG: control group, resin composite; TG1: Conventional GIC; TG2: light-activated GIC; TG3: experimental GIC; TG4: bulk-fill GH; TG5: bulk-fill GH2 (high strength)]. Each group was further subdivided into mild saliva contamination (MSC) and severe saliva contamination (SSC). Each tooth was cut into superficial dentin (SD) and deep dentin (DD) levels to bear fillings under CF and artificial caries-induced (CI) conditions. A universal testing machine was used to measure μSBS (0.5 mm/min). Data were analyzed using Cox regression, one-way ANOVA, and Tukey’s post-hoc tests (α = 0.05). While SSC notably reduced the bond strength of CG (p = 0.0005) and TG1 (p = 0.0278), bond strength was significantly reduced when restored in DD in CG (p < 0.0001), TG1 (p < 0.0001), TG2 (p = 0.0004), and TG4 (p = 0.0033). Caries conditions had no significant impact on the bond strengths (p > 0.05). Under MSC, CG demonstrated higher bond strength and in SSC, CG, and TG2 showed superior bond strength. GICs and GHs functioned ideally in situations simulating saliva contamination and DD restorations in quasi-bench-experiment setups, as these conditions do not have significant effects on their bond strength but enhancing their bond strength is recommended for optimal performance.