The influence of irrigating solutions on the accuracy of the electronic apex locator facility in the Tri Auto ZX handpiece

Aim To determine the influence of various irrigating solutions on the accuracy of the electronic apex locator facility in the Tri Auto ZX handpiece. Methodology One hundred and forty teeth with single canals and mature apices, scheduled for extraction for either periodontal or prosthetic reasons in 76 patients were used. Following informed written consent local anaesthesia was administered, access cavities were prepared and pulp tissue removed. The teeth were then randomly divided into seven groups according to the irrigating solutions used. The root canal length measurements were completed using the Tri Auto ZX handpiece with automatic reverse function in the presence of one or other of the following solutions: 0.9% saline, 2.5% NaOCl, 3% H2O2, 0.2% chlorhexidine, 17% EDTA, Ultracaine((R)) D-S or in the absence of an irrigating solution (control). Files were immobilized in the access cavity with composite resin. After extraction, the apical regions of the teeth were exposed and the file tips examined under a stereomicroscope. Distances between the file tips and the apical constriction were measured (mm) and analysed using a one-way ANOVA and post hoc Tukey test. Results Mean distances from the apical constriction to the file tip were longer in the 0.9% saline group (P < 0.05). There was no statistically significant difference on file tip position between the other solutions. Conclusions Tri Auto ZX gave reliable results with all irrigating solutions apart from in the presence of 0.9% saline.