FRACTURE AND DEFORMATION RATE OF PROTAPER NEXT files AMONG POSTGRADUATE STUDENTS

Document Type : Original Article

Authors

1 Associate Professor, Department of Endodontics, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia

2 Teacher Assistant, Department of Oral Biology, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia

Abstract

Aim: To evaluate the fracture and deformation rate of ProTaper Next nickel-titanium (NiTi) rotary instruments among the postgraduate students (PTN, Dentsply Maillefer, Ballaigues, Switzerland). Materials and Methods: A total of 624 discarded PTN rotary NiTi instruments were collected over 22 months after their clinical use by residents in a graduate endodontic program. The files selected were the X1 (17/04), X2 (25/06), and X3 (30/07). The files’ length was measured and all were examined under the stereomicroscope for defects, such as unwinding, fracture, and blunt tips. The fracture faces of the separated files were examined and photographed under the scanning electron microscope. The data were analyzed using the Chi-squared and Kruskal-Wallis tests. Results: The defect rate of all files was 4.8% and consisted of 2.9% fractures and 1.9% deformation. The file that fractured most frequently was the X3 (55.6% of the total fractured files) because of cyclic fatigue. Deformation without fracture was observed largely in the X1 because of blunt tips. Cyclic fatigue was the cause of 94.4% of fractured instruments and was more frequent in larger sizes.   Conclusions: The ProTaper Next rotary files are more liable to fracture than deformity. Fractures commonly are attributable to cyclic fatigue and are more likely to occur in larger instruments. The small sizes frequently developed blunt tips.  

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