Comparison between two methods of working length determination and its effect on radiographic extent of root canal filling: a clinical study [ISRCTN71486641]

BACKGROUND: Obtaining a correct working length is critical to the success of endodontic therapy. Different methods have been used to identify this crucial measurement. The Aim of this clinical study was to compare the effect of working length determination using apex locator alone or in combination with working length radiograph on the apical extent of root canal filling. METHODS: A total number of 66 patients, 151 canals were randomized into two groups, In group (I) working length was determined by apex locator alone, while in group (II) working length was determined by apex locator confirmed by working length radiograph, length of obturation was assessed, and the total number of radiographs was recorded. The data were analyzed using SAS system and T. tests were carried out. Statistical significance was considered to be P ≤ 0.05. RESULTS: Sixty seven canals in group I were treated with a mean distance from the tip of root canal filling to radiographic apex -0.5 mm ± 0.5 and a mean of a total number of radiographs of 2.0, while in group II eighty four canals were treated with a mean distance from the tip of root canal filling to radiographic apex -0.4 mm ± 0.5 and a mean of a total number of radiographs of 3.2. There was no statistically significant difference in the mean distance from the tip of root filling to radiographic apex between group I and group II (P > 0.05). CONCLUSION: The practice of using electronic apex locator in the determination of working length is useful and reliable with no statistical difference of the radiographic extent of root canal filling when using apex locator alone or in combination with working length radiograph. Under the clinical conditions of this study, it is suggested that the correct use of an apex locator alone could prevent the need for further diagnostic radiographs for determination of working length. This method can be useful in patients who need not to be exposed to repeated radiation because of mental, medical or oral conditions

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

Erdemir, Ali/0000-0003-1140-3887WOS: 000245988400008PubMed: 17309740Aim 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

A comparison between two electronic apex locators: an ex-vivo investigation.

Aim To compare ex vivo the performance of the Apex Finder and the Root ZX apex locators, with and without irrigant, in canals having different diameters. Methodology Sixty canals in 60 teeth were prepared using stainless steel hand files and 0.04 taper NiTi rotary instruments. During preparation the narrowest diameter of the canal was transported to the apical root surface. The canals were irrigated with RC-Prep and 5% NaOCl solution. Six groups were obtained, each with 10 canals having the same diameter of foramen, either 0.15, 0.20, 0.25, 0.40, 0.60 and 0.80 mm. A size 15 K-file was advanced into each canal until its tip was observed under x10 magnification to reach the foramen and the corresponding length recorded. The measurements were performed to an accuracy of 0.25 mm as a base unit of length. The teeth were then fixed to a plastic bar suspended over a glass container filled with 0.9% NaCl solution. Each apex locator was tested when the K-file was at the foramen, or 0.5, 1.0, 1.5 and 2.0 mm short; with the root apex immersed into the solution; with the canal dry or irrigated with NaCl. To evaluate the accuracy of both electronic apex locators (EALs) each electronically determined distance was compared with the actual length and the data analysed using the General Linear Model and the Student t-test. Results Out of 2400 measurements 100 were electrically unstable, all with the Root ZX. In total, 521 measurements located the position of the file tip beyond the apex, in general, in high conductive conditions with the Root ZX and in low conductive conditions with the Apex Finder. No significant difference in terms of accuracy was found between the two EALs when the file tip was at the foramen (Root ZX mean +0.12 mm, SD 1.22 mm; Apex Finder mean +0.57 mm, SD 1.16 mm). Comparing all the measurements performed with the file tip within 2 mm of the foramen, in all the different conditions tested, the accuracy was affected (P < 0.025) by diameter of the foramen, type of EAL, distance to the apex, and by several interactions. Conclusions Under the different ex vivo conditions both EALs provided accurate measurements when the file tip was at the foramen. The accuracy of the Apex Finder was negatively influenced by high conductive conditions, whilst the Root ZX provided inaccurate and unstable measurements mostly in low conductive conditions

A comparison between two electronic apex locators: an in vivo investigation.

Aim To compare in vivo the Apex Finder and Root ZX electronic apex locators (EALs) at five different stages during root canal instrumentation. Methodology The Apex Finder and Root ZX were used in 64 teeth with either vital or necrotic pulps. Informed consent was obtained by each patient under a study protocol approved by an ethical committee from the University of Trieste. Measurements were made: (stage 1) before instrumentation and irrigation; (stage 2) after brief filing, irrigation with 70% isopropyl alcohol and partial drying; (stage 3) after canal lubrication with EDTA gel (RC-Prep); (stage 4) after complete instrumentation and irrigation with NaOCl 5%; (stage 5) after drying of the final instrumented canal. Stages 2, 3 and 5 were considered low canal conductivity conditions and stage 4 as high. Teeth were then extracted and a size 15 K-file was inserted until its tip was observed under stereomicroscope to reach the foramen and the corresponding length was recorded to an accuracy of 0.25 mm and compared with values derived from the EALs. Results The data revealed 133 unstable measurements (out of 640): some (68) related to low canal conductivity conditions (more frequently for Root ZX, 67; P < 0.05), and others (63) related to NaOCl presence in the canal (more frequently for Apex Finder, 58; P < 0.05). Accuracy was calculated only on stable measurements. The Root ZX showed significantly (P < 0.05) more precise measurements overall (-0.03 +/- 0.39 mm) compared with the Apex Finder (-0.31 +/- 0.46 mm). Under dry canal conditions the Apex Finder provided the greatest accuracy (-0.0 +/- 0.21) compared with the Root ZX (-0.05 +/- 0.32) (significance P < 0.05). Conclusions Under the five different clinical situations both EALs revealed accurate measurements. Apex Finder was negatively influenced by NaOCl in the root canal. The Root ZX was more frequently unable to reveal stable measurements in low conductivity canals