Hypochlorous acid as a potential cavity conditioner for caries-affected dentin

To evaluate the effects of hypochlorous acid (HOCl) conditioning on bond strength to caries-affected dentin (CAD), antibacterial efficacy against Streptococcus mutans (S. mutans), and dental pulp cell compatibility. Extracted human molars with occlusal caries were pretreated with 50 ppm HOCl before adhesive application (Clearfil SE Bond 2), with untreated specimens serving as controls. Microtensile bond strength (µTBS) was evaluated after 24-hour storage and 10,000 thermocycles. Antibacterial efficacy was assessed by colony-forming unit (CFU) enumeration following S. mutans incubation with HOCl solution. Rat dental pulp cells were cultured with HOCl at concentrations of 0, 0.5, 1, 5, 10, and 50 ppm. Cell viability was assessed using Cell Counting Kit-8. Data underwent statistical analysis using one-way ANOVA with Tukey's post hoc test (α = 0.05). HOCl pretreatment significantly enhanced µTBS to CAD (from 25.6 ± 4.3 to 35.8 ± 7.2, p < 0.001) and maintained bond stability after thermocycling (32.1 ± 4.5, p > 0.05). HOCl demonstrated significant antibacterial efficacy against S. mutans with substantial reduction of viable bacteria (p < 0.001). Additionally, HOCl maintained compatibility with dental pulp cells. HOCl shows a promise as a dentin conditioner, offering enhance bond performance to CAD with improved bond durability, while providing antibacterial benefits and maintaining biocompatibility.