Influence of Hypochlorous Acid Obtained From an Electrolytic Device on the Mechanical Properties of Root Dentin

Sodium hypochlorite (NaOCl) exhibits antimicrobial activity. However, it is associated with negative effects in endodontics, such as cytotoxicity and alterations in the mechanical properties of root dentin, leading to the search for new alternatives. Hypochlorous acid (HClO) exhibits antimicrobial activity and low cytotoxicity as irrigation solution. Therefore, the aim of this study was to evaluate the influence of HClO on the mechanical properties of root dentin.

Samples were obtained from 120 mandibular bovine incisors, which were distributed into four experimental groups: microhardness (30 teeth/60 samples), flexural strength (15 teeth/60 samples), cohesive strength (15 teeth/60 samples), and fracture resistance (60 teeth/60 samples). For all tests, the samples were subdivided into six groups (n = 10): G1: distilled water (DW); G2:1% NaOCl; G3:2.5% NaOCl; G4:5.25% NaOCl; G5:250 ppm HClO; and G6:500 ppm HClO. The irrigation protocol was set at 30 min. Then, a Vickers tester was used to evaluate microhardness, and flexural strength, cohesive strength, and fracture resistance were evaluated in a universal testing machine. One-way ANOVA and Tukey tests were used for multiple comparisons in all evaluations (α = 5%).

The highest microhardness was observed in DW, 250 ppm HClO and 500 ppm HClO, with no statistical differences between them (p > 0.05). The highest flexural and cohesive strength were observed in DW, 1% NaOCl, HClO 250 ppm, and HClO 500 ppm, with no statistical differences between them (p > 0.05). Regarding the fracture resistance, there were no statistical differences between all groups (p > 0.05).

It was concluded that HClO preserved the mechanical properties of root dentin.