Nickel-Titanium Endodontic File Degradation Assessment via Multi-sensor Fusion and Composite Wear Index: In-Vitro Study

Abstract

Standard root canal treatment involves cleaning, shaping, and enlarging the canals, a process that carries a high risk of file fatigue and failure. While Ni–Ti shape memory alloy files have reduced the frequency of these errors, their wear and fatigue remain abrupt and unpredictable for the practitioner. In this study, a measurement-driven methodology is developed to quantify the in-situ wear progression of a WaveOne Gold (#25) endodontic file using multi-sensor metrology and signal processing. Root canal procedures on extracted human teeth are instrumented with three synchronized sensors—a dynamometer (force), an accelerometer (vibration), and a microphone (acoustic emission)—to acquire high-resolution time-series data under realistic operating conditions. Parameters such as RMS, mean, and Standard deviation fail to provide an accurate understanding of file wear and are less sensitive to sudden changes due to file wear. In this study, force, vibration and acoustics signals are analyzed to calculate various time and frequency-based parameters. These parameters are then used to calculate the composite wear index of the file, indicating the relative wear of the file as opposed to when it was new. The study shows that increase in composite wear index more than 50% indicates severe damage to the endodontic file. This metrology-based framework highlights how integrated sensing, feature engineering, and condition-index formulation can support evidence-based file replacement decisions and enable predictive maintenance strategies for rotary endodontic instruments. © The Author(s), under exclusive licence to Metrology Society of India 2026.