Effect of intracanal cryotherapy on the fracture resistance of endodontically treated teeth.

OBJECTIVE: The aim of this study is to evaluate the effect of intracanal cryotherapy on the fracture resistance of endodontically treated teeth. MATERIALS AND METHODS: Sixty single-rooted maxillary lateral incisor teeth with single root canals were selected and randomly divided into two groups (n = 30). The specimens were immersed in distilled water, which was heated to 37 °C during the procedures. The root canals were chemomechanically prepared up to the apical size of 50 and assigned to either the control group or the cryotherapy group. The specimens in the cryotherapy group were irrigated with 20 mL sterile cold (2.5 °C) saline solution, which was delivered with an EndoVac system for 5 min, whereas the specimens in the control group received a sterile saline solution at room temperature. The fracture resistance of the specimens was then tested with a universal testing machine. The data was analyzed using the independent sample t test with a 5% significance threshold. RESULTS: The fracture strength of the specimens in the intracanal cryotherapy group was significantly lower than that of the control group (p< .05). CONCLUSIONS: Application of intracanal cryotherapy as a final irrigant reduced the vertical fracture resistance of prepared roots when compared to the control group.

Cyclic Fatigue Resistance of XP-Endo Shaper, K3XF, and ProTaper Gold Nickel-titanium Instruments.

INTRODUCTION: The aim of this study was to compare the cyclic fatigue resistance of the ProTaper Gold (PTG; Dentsply Maillefer, Ballaigues, Switzerland), K3XF (SybronEndo, Orange, CA), and XP-endo Shaper (FKG Dentaire, La Chaux-de-Fond, Switzerland) nickel-titanium rotary instruments at intracanal temperatures. METHODS: Eighteen XP-endo Shaper (30.01), 18 K3XF (30.04), and 18 PTG F3 (30.09v) instruments were used to test the cyclic fatigue resistance at an intracanal temperature of 35° ± 2°C. The instruments were tested in a metal block that simulated a canal curvature angle of 60° and a curvature or radius of 5 mm. All instruments were operated until fracture occurred, and then the number of cycles to failure was calculated. The lengths of fractured fragments were measured with a digital caliper. The data were analyzed statistically using 1-way analysis of variance and the Tukey post hoc test with significance set at P < .05. RESULTS: The XP-endo Shaper instruments showed a significantly higher number of cycles to fracture than the K3XF and PTG instruments (P < .05). There was no difference between the PTG and K3XF instruments (P > .05). CONCLUSIONS: The XP-endo Shaper instruments exhibited greater cyclic fatigue resistance compared with the other instruments at the intracanal temperature.