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Electronic apex locator 'apical constriction' reading versus micro-computed tomography landmarks in molars: an in
Hongtao Hu1, Mingwen Liu1, Jingwen Yang1
1State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, 430079, China.
Background:
The aim of this in vitro study was to use micro-computed tomography (µCT) to determine the anatomical position corresponding to the 'apical constriction' (AC) reading of three different electronic apex locators (EALs) in extracted human molars.
Materials And Methods:
Fifty-six extracted human molars (138 canals) were scanned using µCT to assess apical morphology (presence/absence of a single AC) and, for canals with a single AC, to measure the distance from the major apical foramen (AF) to the narrowest diameter (Md). Using a modified mounting model (MM), the distance from the AF to the EAL's 'AC' reading (Ld) was measured for three devices: Root ZX II, Raypex 6, and Elements Apex Locator. Ld values were compared among the EALs within morphological subgroups using one-way analysis of variance (ANOVA) and the Least Significant Difference (LSD) post-hoc test. Significance was set at P < 0.05.
Results:
No statistically significant differences were found among the mean Ld readings of the three EALs, either overall or within the 'AC present' and 'AC absent' morphological subgroups (P > 0.05). Within the 'AC present' group, mean Ld values for the Elements Apex Locator and Raypex 6 were significantly shorter (coronal) than the mean µCT-measured distance Md (P = 0.005 and P = 0.008, respectively). In contrast, the mean Ld for Root ZX II did not differ significantly from the mean Md (P = 0.095).
Conclusions:
The 'AC' reading of the three EALs generally indicated a position slightly coronal to the major apical foramen, irrespective of AC presence. While the three EALs provided comparable readings relative to each other, their accuracy in corresponding to the anatomical AC (when present) varied in this in vitro model, with Root ZX II showing closer agreement with µCT findings.
