Quantitative analysis of troughing depth for successful instrument retrieval using the loop technique: A cross-sectional in vivo study.

Abstract

Introduction: Fractured endodontic instruments complicate root canal treatment by obstructing cleaning and shaping. The loop technique is a widely used retrieval method, but the optimal depth of dentin troughing required for successful retrieval remains unclear. Insufficient troughing can lead to failed attempts, wasted materials, and operator fatigue, whereas excessive troughing may increase chair side time, cause dentin loss, and lead to iatrogenic errors.

Aim: The aim of the study was to evaluate the depth of dentin troughing required for successful retrieval of fractured endodontic instruments using the loop technique and to analyze secondary outcomes, including retrieval time and success rates.

Materials and methods: This cross-sectional in vivo study included 60 teeth with fractured instruments, comprising 39 rotary and 21 hand instruments. The procedure was performed using high magnification, with a modified Gates Glidden drill and an ISO 25 sonic spreader to create a staging platform and expose the file head. The loop technique, employing a 27-gauge syringe and 0.02 mm Stainless steel wire, was used for retrieval. Troughing depth and retrieval time were recorded. Measurements were taken using a stereo microscope and analyzed with ImageJ software.

Statistical analysis: Data obtained were statistically analyzed using ANOVA, paired samples test. P < 0.05 was considered statistically significant.

Results: The mean troughing depth was significantly greater for rotary instruments (0.42 mm ± 0.25 mm) than for hand instruments (0.28 mm ± 0.18 mm). The overall success rate was 98.3%, with no significant difference between rotary (97.4%) and hand instruments (100%). Retrieval time was significantly longer for rotary instruments (46.2 ± 3.2 min) than for hand instruments (32.4 ± 2.4 min, P < 0.05).

Conclusion: Rotary instruments require deeper troughing and longer retrieval times compared to hand instruments. This study provides evidence-based guidance for optimizing fractured instrument retrieval while preserving tooth structure and minimizing procedural risks.