Quantitative Evaluation of Debris Removal from NiTi Rotary Endodontic Instruments After Different Cleaning Procedures

Objectives: Endodontic instruments require thorough decontamination and sterilization before use and reuse to ensure the safety and success of treatments. However, standardized protocols are lacking. This study aimed to quantitatively assess the effectiveness of different cleaning protocols in removing debris from NiTi rotary file surfaces. Methods: Forty-eight new Mtwo NiTi rotary instruments (sizes 10/.04, 15/.05, 20/.06, and 25/.06) were randomly assigned to four groups (n = 12). A set of new sterile instruments (Group I) served as the negative control. After usage for primary endodontic treatment, instruments underwent different cleaning protocols: steam sterilization without cleaning (Group II); ultrasonic cleaning + steam sterilization (Group III); and manual cleaning with a scouring sponge + ultrasonic cleaning + steam sterilization (Group IV). Back-scattered scanning electron microscopy (SEM) micrographs of the apical, middle, and coronal sections were processed using Fiji software (version 2.14.0) to quantify debris as a percentage of the total selected area. Results: No significant differences were found among the three sections within each group, although higher debris amounts were observed from coronal to apical in Groups I and II. Group I had the least debris, while Group II showed the most, with statistically significant differences compared to other groups (p < 0.05). There was no significant difference between Groups III and IV, though Group IV showed notably less debris. Conclusions: The combination of mechanical, chemical, and ultrasonic cleaning proved most effective at removing debris from endodontic instruments. Current cleaning methods, however, remain insufficient for complete debris removal, highlighting the need for further research to standardize and improve cleaning and sterilization protocols or preferably use single-use/single-patient instruments.