Differences in cyclic fatigue resistance between ProTaper Next and ProTaper Universal instruments at different...

Area of Science:

• Endodontics
• Dental Materials Science
• Biomaterials Engineering

Background:

• Advancements in rotary file design and alloys aim to enhance cyclic fatigue (CF) resistance.
• Rotary endodontic instruments are crucial for effective root canal preparation.

Purpose of the Study:

• To compare the cyclic fatigue resistance of ProTaper Universal (PTU) and ProTaper Next (PTN) rotary files.
• To evaluate CF resistance at various points of curvature in simulated root canals.

Main Methods:

• 420 instruments (240 PTU, 180 PTN) were divided into 14 groups based on file type and testing location (5mm, 8mm, or 12mm from the tip).
• Files were subjected to cyclic rotation at 300 rpm in stainless steel curved canals (60°, r = 3 mm) until fracture.
• Cyclic fatigue resistance was analyzed using Weibull analysis, calculating mean half-life, beta, and eta values.

Main Results:

• ProTaper Next (PTN) instruments exhibited significantly longer cyclic fatigue life than ProTaper Universal (PTU) files at all tested locations, with over 98% probability.
• The PTU S1 instrument demonstrated significantly higher CF resistance compared to other tested instruments at 5mm from the tip.

Conclusions:

• The ProTaper Universal S1 instrument is the most resistant to cyclic fatigue at 5mm from the tip.
• ProTaper Next files offer significantly greater cyclic fatigue resistance than ProTaper Universal files at other tested distances from the apex.