A nationwide cross-sectional study on endodontic instrument fractures and development of a comprehensive classification system

Abstract

Aim: To assess the incidence and characteristics of instrument fractures in root canals and provide researchers with a systematic classification system that will facilitate diagnosis, research, and treatment planning.

Materials and methods: In this cross-sectional and observational study, we collected the data on 887 intraoral periapical (IOPA) radiographs taken from different geographical and clinical practices in India. The images containing instrument fractures were classified according to the location of fractures within the canal (coronal, middle, and apical third) and their relationship to canal curvature. The IOPA images were independently evaluated by two experienced endodontists, and the kappa statistics was applied to estimate interobserver agreement (≥80%). Descriptive statistics were analyzed using the SPSS software version 22.0.

Results: The location of 54.3% of fractures was in the middle third of the canal, followed by apical thirds (24.5%) and coronal thirds (19.8%). Fractures beyond the periapex were rare (1.4%). Of the fractures, 54.3% had curvatures of the canal and of those, 33.1% or 3.1% of the fractures occurred within mild to moderate curvatures. The study found statistically significant differences in fractures in the different regions of the canal (P < 0.01). A unique classification system was created to categorize fractures by location, extent, and curvature involvement which can be used and applied in both clinical and research settings.

Conclusions: The research draws the attention to the lack of a standardized classification system for instrument fractures, an underappreciated aspect of endodontics. The classification system proposed here will enhance communication, educate on diagnosis, treatment planning, and provide support for advanced education in the field.

Keywords: Endodontic instrument fracture; endodontic instrumentation; new classification; root canal treatment.

Figure 1

Intra-oral clinical radiographs representing Type I, Type II, Type III, Type IV, and instrument fracture in moderately and severely curved canals. The degree of curvature was determined by measuring the angle formed at the intersec+on of two lines: one drawn along the long axis of the canal (a and b) and the other extending from the apical foramen to the point of ini+al curvature (b and c).”

Figure 2

Schematic presentation of the proposed classification for Type I – Instrument separation, and the head of the instrument is in the coronal third. (a) fractured instrument in the coronal third, (b) fractured instrument in the coronal third and extends in the middle third, (c) fractured instrument in the coronal third and extends in the apical third, and (d) fractured instrument in the coronal third and extends beyond the apical foramen; Type II – Instrument separation and the head of the instrument is in the middle third. (a) fractured instrument in the middle third, (b) fractured instrument in the middle third and extends in the apical third, and (c) fractured instrument in the middle third and extends beyond the apical foramen; Type III – Instrument separation is in the apical third. (a) fractured instrument in the apical third, (b) fractured instrument in the apical third and extends and extends beyond the apical foramen; Type IV – Instrument separation is beyond the apical foramen; and Instrument fracture in moderately and severely curved canals (Type 1: Above the curvature, Type 2: Involving the curvature, and Type 3: Beyond the curvature)