PREVALENCE OF VISUALLY DETECTABLE DEFECTS IN ROTARY NICKEL-TITANIUM ENDODONTIC INSTRUMENTS UNDER CONDITIONS OF REPEATED USE IN CLINICAL DENTAL PRACTICE
DOI:
https://doi.org/10.32782/3041-1394.2026-2.1Keywords:
endodontics, rotary instruments, endodontic files, visual assessment, endodontic treatment, root canals, mechanical preparationAbstract
Introduction. Mechanical loading to which rotary nickel-titanium endodontic instruments are subjected during root canal preparation may result in structural alterations of different types. Some of these alterations are represented by macroscopically identifiable deformations of the working part of the instrument, whereas other defects remain undetectable during routine clinical inspection. Assessment of visually detectable defects is particularly relevant for dental practices in which nickel-titanium instruments are reused after cleaning and sterilization. Aim of the study. To determine the prevalence and features of macroscopically detectable defects in reused rotary nickel-titanium endodontic instruments and to evaluate the distribution of such defects depending on the ISO size of the instrument. Research materials and methods. The study was designed as a single-center cross-sectional observational investigation. A total of 120 rotary nickel-titanium endodontic instruments that had been repeatedly used in clinical practice and had undergone a standard cleaning and sterilization cycle were subjected to visual analysis. Inspection was performed with the naked eye under standard lighting conditions. The instruments were additionally stratified according to ISO size into groups #15, #20, #25, #30, and #35. Results. Visually detectable defects were identified in 37 of the 120 analyzed instruments, corresponding to an overall prevalence of 30.83%. The prevalence of identified defects among files of different sizes was distributed as follows: among size 15 files – 9/20 (45%); among size 20 files – 11/25 (44%); among size 25 files – 9/35 (25.71%); among size 30 files – 5/22 (22.72%); and among size 35 files – 3/18 (16.67%). Conclusion. Almost one-third of the reused and sterilized rotary nickel-titanium instruments demonstrated at least one defect that could be identified visually with the naked eye. Within the analyzed sample, the prevalence of macroscopic defects was highest among instruments of sizes #15, #20, and #25. However, ISO size should not be considered an isolated causal factor without taking into account the specific metallurgical characteristics of the instruments and the particular features of their clinical use.
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