Effect of endodontic irrigation protocols on crown fracture resistance

Abstract

Aim: This study aimed to evaluate the fracture resistance of tooth crowns endodontically irrigated using different protocols. Materials and methods: A total of 76 bovine incisors were divided into four groups (n = 19): irrigation with distilled water (control; CON); conventional irrigation with positive apical pressure (PAP); passive ultrasonic irrigation using continuous flushing (PUI); and irrigation with PAP and heated sodium hypochlorite solution (PHS). The force required to fracture the crown was measured on a universal testing machine at an angle of 45°. Results: The CON group had higher fracture resistance (351.71 ± 58.66 N) than the PAP and PUI groups (140.96 ± 37.26 N; 167.49 ± 40.08 N respectively). The PHS group had the lowest fracture resistance value (115.15 ± 41.07 N). Irrigation protocols had a significant effect on crown resistance (p < 0.01). Conclusion: Teeth subjected to irrigation with heated sodium hypochlorite showed decreased resistance to crown fracture. Clinical significance: The contact of the irrigating solution with the root canal walls potentially can cause their weakness, determining crown fracture.