Precision in endodontics: Comparison of four different working length determination methods with three irrigation solutions – An in vivo study
Abstract
Accurate working length determination is essential for endodontic success, yet the optimal method among radiographic, electronic, and imaging-based techniques remains debated. The aim of the study was to compare the accuracy of working length (WL) determination using an electronic apex locator (EAL), an integrated apex locator (IAL), cone beam computed tomography (CBCT), and conventional periapical radiography and to evaluate the influence of three root canal irrigants – three percent sodium hypochlorite (NaOCl), Twinkleen, and saline – on measurement accuracy. A prospective in vivo randomized comparative study was conducted on forty-five single-rooted permanent teeth requiring primary root canal treatment. Preoperative CBCT (Carestream CS9300) served as the reference standard. WL was additionally determined by conventional periapical radiography (Carestream RVG 5200), the Root ZX Mini EAL (J Morita, Japan), and the CanalPro CL2i IAL (COLTENE-Whaledent, USA). Participants were randomly allocated to three groups ( n = fifteen each) by irrigant: Group I – three percent NaOCl; Group II–Twinkleen; Group III–Saline. One-way analysis of variance and Tukey’s post hoc test (alpha = 0.05) were used for statistical analysis. Both the Root ZX Mini and CanalPro CL2i produced WL measurements closely approximating CBCT values across all irrigants, with mean differences ≤0.23 mm and interdevice differences ≤0.10 mm ( P > 0.05). Conventional radiographs showed the greatest deviation from CBCT (mean difference approximately 0.64 mm). No statistically significant difference was found among any measurement pair. Saline caused the least variability, followed by Twinkleen and three percent NaOCl. Both standalone and IALs provide clinically accurate, radiation-free WL determination comparable to CBCT across all three irrigants. IALs offer additional procedural efficiency and are suitable for routine clinical practice.