In vivo measurement accuracy in vital and necrotic canals with the Endex apex locator

Ex Vivo Evaluation of the Accuracy of 3 Electronic Apex Locators in Different Environments: A Micro-Computed Tomography Study

Objective:

The aim of this study was to compare the accuracy of three electronic apex locators (EALs) (Propex Pixi, Mini Root ZX, Raypex 5) in determining working length (WL) under different environments (existence of blood-pulp/sodium hypochlorite in root canal space) using micro-computed tomography (micro-CT) measurements.

Methods:

Twenty-five single-rooted human teeth that were scheduled for extraction were selected for the study. Measurements were performed with the Propex Pixi, Mini Root ZX, Raypex 5 in vivo conditions in the presence of NaOCl irrigant solution or blood-pulp tissue. After that the teeth were extracted and scanned using micro-CT. The measurements of WL obtained with the different EALs in different environments were statistically compared. Significance was set at P<0.05.

Results:

There were no significant differences among the WL measurements performed with EALs or micro CT groups under different clinical enviroments. All EALs tested gave reliable results in respect to apical constriction.

Conclusion:

The accuracy of the tested EALs is not affected by pulp tissues and blood or NaOCl.

An in vivo comparison of accuracy of two electronic apex locators in determining working length using stainless steel and nickel titanium files

Purpose

A key factor affecting the success of endodontic treatment is correct determination of root canal working length (WL). The purpose of this in vivo study was to compare the accuracy of Propex II and iPex II electronic apex locator (EAL) in determining the WL under clinical conditions, to that of radiographic working length (RWL) using stainless steel (SS) and nickel–titanium (NiTi) hand files.

Patients and methods

Thirty-seven patients, with 60 anterior teeth (60 canals) scheduled for endodontic treatment participated in this study after ethical approval. Electronic working length (EWL) was determined by the Propex II and iPex II according to manufacturer’s instructions using SS Hand K-files and NiTi Hand files. RWL was determined after EWL determination. The results obtained with each EAL with SS and NiTi files were compared with RWL. Data was analyzed statistically at a significance level of p < 0.05. Interclass correlation coefficient was calculated.

Results

Statistical analysis revealed no significant difference between the EALs, indicating similar accuracies between them with respect to accuracy in determining the WL (p > 0.05). No significant difference was found between the EWL and RWL and between SS and NiTi files for WL determination (p > 0.05) as well. The result also displayed a high intraclass correlation coefficient between the RWL and EWL measurement methods.

Conclusion

Under the in vivo clinical conditions of this study, both Propex II and iPex II were similar to the RWL determination technique showing high correlation to RWL. Both are clinically acceptable EAL for WL determination and both SS hand K-file and NiTi file can be used interchangeably without compromising the WL during treatment.

Consistency of electronic measurements of endodontic working length when using multiple devices from the same manufacturer-an in vitro study

OBJECTIVES

To assess the consistency of electronic determination of endodontic working length obtained from four identical electronic root canal length measurement devices (ERCLMD) from five different types of ERCLMD each under various in vitro conditions.

MATERIALS AND METHODS

Eight extracted teeth, seven single-rooted teeth, and one molar were accessed. Root length was measured and instruments were inserted and fixed with the tip placed beyond and short of the apical constriction, in roots with an artificial perforation or an open apex. Devices tested were Root ZX (Morita, Kyoto, Japan), Dentaport ZX (Morita), Apex ID (SybronEndo, Glendora, USA), ProPex II (Dentsply Maillefer, Victoria, Australia), and Raypex 6 (VDW-Antaeos, Munich, Germany). Teeth were irrigated with different solutions (NaOCl, EDTA, CHX). ERCLMDs were connected and measurements were recorded. Consistency was classified by the scores 0-4. Comparisons were carried out using the Kruskal-Wallis test (α = 0.05). For multiple testing, the level of significance was adjusted and analysis was performed using the Mann-Whitney U test.

RESULTS

Among the five types of ERCLMD, Apex ID and Raypex 6 showed the highest consistency. There was no statistically significant difference between the settings and conditions. Raypex 6 showed the highest consistency for measurements in case of a perforation.

CONCLUSION

Different devices from one type of ERCLMD show a high consistency. Nevertheless, general statements on the accuracy of one type of ERCLMD taken from studies investigating only one device per type should be drawn with caution.

CLINICAL RELEVANCE

The study refers to the reliability and repeatability of determination of endodontic working length by using ERCLMDs.

Controversies in Endodontics

Diseases of the dental pulp often have an infectious origin, and treatments are aimed to control infections of the root canal system. Endodontic treatment principles originally evolved on the basis of trial and error, and only in recent decades have scientific methods been adopted to support clinical strategies. Yet, relevant research on the disease processes, their diagnoses, and efficient treatment are rare in the endodontic literature. Hence, the advancement of biologically based knowledge significant to clinical endodontics has been slow. Therefore, many differences of opinion still prevail in this field of dentistry. This review highlights and analyzes the background of some of the more heavily debated issues in recent years. Specifically, it deals with disagreements regarding the clinical management of pulpal exposures by caries in the adult dentition, definitions of success and failure of endodontic therapy, and causes of and measures to control infections of the root canal system. Clearly, a most apparent gap in the published endodontic literature is the lack of randomized clinical trials that address the more significant controversial matters relating to the management of pulpal wounds, medication, and the number of appointments required for the treatment of infected root canals. However, trials in endodontics require extremely long follow-up periods if valid conclusions are to be generated. Therefore, it is not to be expected that there will be rapid solutions to these issues in the foreseeable future.

Accuracy of an electronic apex locator in the retreatment of teeth obturated with plastic or cross-linked gutta-percha carrier-based materials: an ex vivo study

INTRODUCTION

This ex vivo study evaluated the accuracy of the Root ZX electronic apex locator (EAL) (J Morita Corp, Kyoto, Japan) in determining the working length during retreatment of canals sealed with 2 different carrier-based obturating materials (ProTaper Obturator [Dentsply Maillefer, Ballaigues, Switzerland] and GuttaCore [Dentsply Maillefer]) and also evaluated whether they influenced its accuracy differently.

METHODS

Fifty extracted single-rooted human teeth with sound apices were selected for the study. We measured canals with the direct visual technique using a #10 K-file and shaped them with ProTaper Universal instruments (Dentsply Maillefer) up to this predetermined length. After instrumentation, we determined the canal length again using the visual technique (direct length [DL]). This value was considered the "reference point." Specimens were then placed in a tooth holder (Pro-Train; Simit Dental, Mantova, Italy), and the canal length was electronically measured (electronic length 1 [EL1]). Specimens were then obturated with ProTaper Obturators (group 1, n = 25) and GuttaCore (group 2, n = 25). Seven days later, a new electronic length was determined (electronic length 2 [EL2]) during retreatment procedures in the presence of the obturating material. EL1 and EL2 values were compared with DL using the Bland and Altman method. The different influences of the tested materials on the accuracy of the EAL were calculated with repeated measures analysis of variance.

RESULTS

Both EL1 and EL2 values provided a statistically significant overestimation of the actual canal length (DL [P < .05]), with the EL2 values higher from DL. The 2 different materials did not influence the accuracy of the EAL differently (P = .486).

CONCLUSIONS

The measurements obtained with the EAL tested during orthograde retreatments can lead clinicians to overinstrumentation and consequent overfilling of the endodontic space.

Working Length Determination of Root Canal of Young Permanent Tooth: An In vitro Study

BACKGROUND

Determination of correct working length is one of the keys to success in endodontic therapy.

AIM

The aim of this study was to evaluate the diagnostic efficacy of various methods to determine working length of root canal.

MATERIALS AND METHODS

Tactile method was assessed using digital radiography and compared with electronic method using apex locator. A total sample of 30 single rooted young permanent teeth the (mandibular first premolars) with matured apices were selected for the study. Access cavity preparation was carried out. Working length was measured by tactile method using digital radiography and electronic method using apex locator with no 15 K file. Actual working length was established by grinding of cementum and dentine from the root apex and was observed under stereomicroscope. Data was collected and statistical analysis was carried out with the help of SPSS-15.

RESULTS

The results of this study showed that there was a significant difference between tactile method assessed by digital radiography and electronic method using apex locator.

CONCLUSION

Apex locator was found to be more reliable and accurate when compared with the actual length.

Clinical efficacy of electronic apex locators: systematic review

INTRODUCTION

Apical constriction has been proposed as the most appropriate apical limit for the endodontic working length. Despite being the most used, some limitations are attributed to the radiographic method of working length determination. It lacks precision because it is based on the average position of the apical constriction. The electronic apex locators have been presented as an alternative to the odontometry performed by radiography. These devices detect the transition of the pulp to the periodontal tissue, which is anatomically very close to the apical constriction and may perform with improved accuracy.

METHODS

A systematic review was performed to compare the radiographic and electronic methods. Clinical studies that compared both methods were searched for on 7 electronic databases, a manual search was performed on the bibliography of articles collected on the electronic databases, and the authors were contacted to ask for references of more research not detected on the electronic and manual search.

RESULTS

Twenty-one articles were selected. The majority were comparative or evaluation studies, and very few clinical studies comparing both methods are available. Several methodological limitations are present on the collected articles and debated in this review.

CONCLUSIONS

Although the available scientific evidence base is short and at considerable risk of bias, it is still possible to conclude that the apical locator reduces the patient radiation exposure and also that the electronic method may perform better on the working length determination. At least one radiographic control should be performed to detect possible errors of the electronic devices.

Ex vivo accuracy of Root ZX II, Root ZX Mini and RomiApex A-15 apex locators in extracted vital pulp teeth

The objective of this study was to compare, ex vivo, the accuracy of three electronic apex locators (EALs), Root ZX II, Root ZX Mini and RomiApex A-15, in detecting the apical foramen (AF). Forty extracted single-Rooted human teeth with vital pulp were used in this study. After access preparation, the Root canal length of each tooth was measured by placing a #10 file until the tip was visible at the AF under a stereomicroscope. The teeth were subsequently embedded in an alginate model. In each Root canal, all three EALs were used to determine the working length, which was defined as the zero reading or equivalent. The distance between the file tip and AF was measured to an accuracy of 0.01 mm. Results were analyzed using analysis of variance and the Chi-squared test. Root ZX II, Root ZX Mini and RomiApex A-15 were accurate within 0.5 mm, 62.5, 56.2, 50% of the time. No significant differences were found between the three EALs (p > 0.05). Considering all EALs, the mean distance from the file tip to AF was 4.49 mm. The accuracy of the three EALs evaluated in this study was not statistically significantly different. The 'Apex' or '0.0' marks of the EALs do not indicate the AF itself, but just a position coronal 0.49 mm to the AF. Using a tolerance of ± 0.5 mm from the actual lengths, the ZX II yielded the most acceptable measurements.

Influence of apical periodontitis on the accuracy of 3 electronic root canal length measurement devices: an in vivo study

INTRODUCTION

The aim of this in vivo study was to evaluate the influence of apical periodontitis (AP) on the accuracy of Dentaport ZX (J Morita, Kyoto, Japan), Raypex 5 (VDW, Munich, Germany), and i-Root (S-Denti, Seoul, Korea) electronic root canal length measurement devices (ERCLMDs).

METHODS

Thirty-two single-rooted teeth scheduled for extraction, consisting of 16 teeth with AP and 16 teeth with normal periapex (NP), were selected. The access cavity was prepared, and the coronal portion of the canal was flared. The electronic working length (EWL) was determined by each ERCLMD according to each manufacturer's instructions. Each tooth was extracted, and the actual working length (AWL) was determined by inserting a size 15 K-file until the tip could be seen at a position tangential to the major foramen and then 0.5 mm was subtracted from the measurement. The distance from the file tip (EWL) to the point 0.5 mm coronal to the major foramen (AWL) was calculated. Data were analyzed using the nonparametric Fisher exact test and the chi-square test. Statistical significance was set at P < .05.

RESULTS

The accuracies of Dentaport ZX, Raypex 5, and i-Root within ± 0.5 mm in the AP group were 93.8%, 81.3%, and 75.0%; they were 93.3%, 86.7%, and 73.3% in the NP group, respectively. There were no significant differences between the accuracy of each device in the 2 groups (P > .05). Considering the 2 groups of AP and NP, there were no statistically significant differences in the accuracy of the ERCLMDs (P > .05).

CONCLUSIONS

The presence of AP did not influence the accuracy of ERCLMDs.

In vivo accuracy of three electronic root canal length measurement devices: Dentaport ZX, Raypex 5 and ProPex II

AIM

To compare in vivo three different electronic root canal length measurement devices: Dentaport ZX, Raypex 5 and ProPex II.

METHODOLOGY

Thirty single-rooted permanent teeth scheduled for extraction because of periodontal disease were selected from 10 adult patients (ranging from 45 to 67 years) and divided into three groups of 10 teeth. Before the extraction, an access cavity was prepared and the crown was adjusted to establish a stable reference point for all measurements. The working length in Group 1 was determined using the Dentaport ZX apex locator. A K-file with the largest diameter that could reach the last green bar on the screen was stabilized in the canal using a dual-curable flow resin composite. The same procedure was used for the Raypex 5 (the file reached the last yellow bar) and Propex II (0.0 orange bar) apex locators. The teeth were then extracted and cleared. The distance between the tip of the file and the major foramen was then calculated for each tooth using digital photography according to Axiovision AC software (Carl Zeiss). Positive values were assigned when the file tip passed beyond the major foramen, negative values when the tip was short of the foramen and zero value when the file tip and the foramen coincided. Statistical analysis was performed using the chi-squared test or Fisher's exact test (P ≤ 0.05).

RESULTS

  Dentaport ZX, Raypex 5 and ProPex ΙΙ produced, respectively, 6, 2 and 4 out of 10 correct measurements, 0, 6 and 5 long measurements and 4, 2, and 1 short measurements. The differences between the three electronic root canal length measurement devices were not significant (P = 0.507).

CONCLUSIONS

Under the in vivo conditions of this study, the three electronic root canal length measurement devices were not significantly different in terms of locating the major foramen.

Accuracy of Root ZX II in locating foramen in teeth with apical periodontitis: an in vivo study

INTRODUCTION

This study was conducted in vivo to investigate the accuracy of Root ZX II in locating the apical foramen in teeth with apical periodontitis (AP).

METHODS

Twenty-seven single-root teeth scheduled for extractions were selected; in AP group, there were 12 teeth with pulp necrosis and radiographic evidence of apical lesions, and VT group consisted of 15 vital teeth. After endodontic access, the coronal portion of the canal was flared, and electronic measurement was performed by using a 15 K-file until the device level reading "APEX" was reached. The file was fixed in place, and the tooth was extracted. The apical third of the root was shaved until exposure of the file. The distance from the file tip to the most coronal border of the apical foramen was obtained.

RESULTS

The mean distance in AP group was +0.117 (standard deviation, 0.373) and in VT group was -0.105 (standard deviation, 0.218). The unpaired t test showed no difference between the groups when comparing the mean distances (P > .05). The apical foramen was accurately located within ±0.5 mm in 83% of the teeth in AP group and in 100% of VT group. Statistical analysis showed no difference between the groups (P = .1092).

CONCLUSIONS

The Root ZX II device was accurate in locating the apical foramen regardless of the presence of AP.

The effect of file size on the accuracy of the raypex 5 apex locator: an in vitro study

Background and aims

Determining the proper length of the root canals is essential for successful endodontic treatment. The purpose of this in vitro study was to evaluate the effect of file size on the accuracy of the Raypex 5 electronic apex locator for working length determination of uninstrumented canals.

Materials and methods

Twenty maxillary central incisors with single straight canals were used. Following access cavity preparation, electronic working length by means of Raypex 5 apex locator and actual working length were determined. Data were analyzed using ANOVA with repeated measurements and LSD test.

Results

There was no significant difference between electronic and actual working lengths when a size 15 K-file was used.

Conclusion

Under the conditions of the present study, a size 15 K-file is a more suitable size for de-termining working length.

Ex vivo evaluation of the ability of four different electronic apex locators to determine the working length in teeth with various foramen diameters

BACKGROUND

The aim of this ex vivo study was to evaluate the accuracy of four electronic apex locators (EALs) to determine the working length in teeth with various foramen diameters. Our previous study revealed that electronically measured canal length was influenced by the root canal diameter. It is not known whether foramen size would interfere with the reading accuracy of an EAL.

METHODS

A total of 36 extracted human lower single rooted premolar teeth were divided into four groups of nine teeth each. In groups A, B and C, the root canals were instrumented using #10-80, #10-100 and #10-120 K-files, and the tip of size #80, #100 and #120 K-files were permitted to pass through the apical foramen to a length of 1mm, respectively. In group D, the teeth were instrumented using #10-140 K-files and the tip of #140 K-file was permitted to pass through the apical foramen to a length of 5 mm. Thus, the average apical foramen diameters in groups A, B, C and D were approximately 0.82 mm, 1.02 mm, 1.22mm and 1.5 mm, respectively. The teeth were then mounted in 1% agar and four EALs were used: Root ZX, Foramatron D10, Apex NRG and Apit 7. For electronic measurement, sizes #10 and #80, #10 and #100, #10 and #120, and #10 and #140 K-files were used for groups A, B, C and D, respectively. During electronic measurement the canals were flushed with 6% sodium hypochlorite solution.

RESULTS

Three-way ANOVA and Bonferroni test showed that EAL, file size and foramen size all had a significant influence on the measurement error (P<0.0001), with all the interactions between these three factors being significant (P<0.0001).

CONCLUSIONS

The four EALs were unreliable to determine the working length of teeth with a wide apical foramen, when using a small size file. The Root ZX and Foramatron D10 showed significantly better scores than the other two EALs and may be more reliable to determine the working length of teeth with a wide apical foramen, if a tight-fit file is used.

Influence of pulp vitality on length determination by using the elements diagnostic unit and apex locator

OBJECTIVE

The aim of this study was to compare the influence of the pulp condition (vital or necrotic) on the determination of the root canal length by using a fourth generation electronic apex locator (EAL).

STUDY DESIGN

The Elements Diagnostic Unit and Apex Locator was used to measure 143 teeth, totaling 294 canals with different conditions (236 necrotic and 58 vital pulp), for root length. After assessing the root canal and ascertaining the tooth length by using the EAL, the position of the file was confirmed by radiograph. The distance between the file tip and the root end was measured radiographically and was compared with the electronic measurement.

RESULTS

Under clinical conditions within an acceptable range lower than 0.5 mm, the concordance between the 2 measurements was 96.6%. This new EAL showed no significant difference (P < or = .05) on accuracy of root canal length determination between vital cases (94.8%) and necrotic cases (97%).

CONCLUSION

This device proved to be reliable regardless of the pulpal vitality.

Ex vivo accuracy of three electronic apex locators: Root ZX, Elements Diagnostic Unit and Apex Locator and ProPex

AIM

To compare ex vivo the accuracy of three electronic apex locators (EALs): Root ZX, Elements Diagnostic Unit and Apex Locator and ProPex.

METHODOLOGY

Electronic working length determination was carried out in 40 extracted teeth using an ex vivo model. After access preparation, a first operator determined the reference length (AL) for each tooth under a 30x stereomicroscope using the apical constriction as the apical landmark. All teeth were then measured with each EAL and the results obtained were compared with the corresponding AL. The AL was subtracted from the electronically determined distance. The measurements exceeding the AL were recorded as positive (long) and the measurements short of the AL were recorded as negative. Data were analyzed using the Friedman Test and Tukey multiple range test for nonparametric correlation amongst groups. Statistical significance was considered at P < 0.05.

RESULTS

Comparing the differences between measurements obtained with the three EALs and those obtained with the stereomicroscope, the percentage of measurements within +/-0.5 mm of the AL was 97.37% (84.22% within 0.5 mm short of AL) for the Root ZX, 94.28% (88.57% within 0.5 mm short of AL) for the Elements and 100% (35.9% within 0.5 mm short of AL) for the ProPex. The mean difference between the AL and the lengths measured by the Root ZX, the Elements and the ProPex were, respectively, -0.157 +/- 0.228, -0.103 +/- 0.359 and 0.307 +/- 0.271 mm.

CONCLUSIONS

The results of the present study confirm that the EALs determined the canal length within +/-0.5 mm from the apical constriction in the majority of cases. The majority of the ProPex readings were long.

An Evaluation of Root ZX and Elements Diagnostic Apex Locators

The purpose of this study was to compare the accuracy of the Root ZX and Elements Diagnostic electronic apex locators under clinical conditions. Thirty-six teeth planned for extraction were used. Each tooth was decoronated, coronally flared with Orifice Shapers, and irrigated with 2.6% sodium hypochlorite. Working lengths were measured with K-files using both electronic apex locators. The files were cemented at the last measured working length and the teeth were extracted. The apical 4-mm of each canal were exposed and photographed under 15x and 30x magnification. Images of each apex were projected and the distance from the file tip to the minor diameter was determined. The mean distances from the file tip to the minor diameter were 0.346 mm for the Elements Diagnostic and 0.410-mm for the Root ZX beyond the minor constriction. In locating the minor constriction the Root ZX was accurate 75% of the time to +/-0.5 mm, 83.3% +/-0.75 mm, and 88.9% to +/-1 mm. The Elements Diagnostic was accurate 75% of the time to +/-0.5 mm, 88.9% to +/-0.75 mm, and 91.7% to +/-1 mm. There was no statistically significant difference between the accuracy of the two electronic apex locators in locating the minor diameter (p < 0.05).

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.

Electronic apex locators

Prior to root canal treatment at least one undistorted radiograph is required to assess canal morphology. The apical extent of instrumentation and the final root filling have a role in treatment success, and are primarily determined radiographically. Electronic apex locators reduce the number of radiographs required and assist where radiographic methods create difficulty. They may also indicate cases where the apical foramen is some distance from the radiographic apex. Other roles include the detection of root canal perforation. A review of the literature focussed first on the subject of electronic apex location. A second review used the names of apex location devices. From the combined searches, 113 pertinent articles in English were found. This paper reviews the development, action, use and types of electronic apex locators.

Electronic apex locator

Locating the appropriate apical position always has been a challenge in clinical endodontics. The electronic apex locator (EAL) is used for working length determination as an important adjunct to radiography. The EAL helps to reduce the treatment time and the radiation dose, which may be higher with conventional radiographic measurements. According to recent publications, the accuracy of frequency-dependent EALs appears to be much higher compared with traditional-type EALs (simple resistance type or impedance type). This article reviews the history and the working mechanism of the currently available EALs, and suggests the correct usage of the apex locator for a better canal length measurement.

Clinical evaluation of the measuring accuracy of ROOT ZX in primary teeth

OBJECTIVE

The aim of this study was to assess the accuracy of an electronic device (Root ZX; Morita, Tokyo, Japan) for measuring the root canal length in primary teeth.

STUDY DESIGN

The pulp tissue was removed from 71 nonrestorable teeth scheduled to be extracted under general anesthesia, and the root canals (n = 105) were irrigated (H(2)O(2), 3%; NaOCl, 1%). Subsequently, the length was determined clinically with the electronic device prior to extraction. Treatments were performed by 2 dentists (42 and 63 root canals). After extraction, the real length was recorded and the 2 measurements were compared.

RESULTS

Measurements were affected significantly by the dentists (P < .01; chi(2)). However, regression analysis revealed sufficient accuracy of the device, with a tendency to estimate the root canal length just short (x = -0.98 +/- 1.75 mm) of the apex. These results were not influenced by tooth type, root canal type, status of the periapex, or clinical condition (P > .05; chi(2)).

CONCLUSION

Root ZX can be strongly recommended for clinical implementation of endodontics in primary teeth, particularly when treating fidgety children.

Clinical accuracy of a new apex locator with an automatic compensation circuit

A new circuit was designed to automatically compensate for measurement errors of an electronic apex locator in various electrolytes. Thirty-one root canals were clinically tested for accuracy. A file was inserted into the canal until the apex signal was obtained, at which point the file was immobilized with glass-ionomer cement. After extraction, the apical area was exposed and the position of the file tip was examined under an operating microscope. Distances from the major foramen and cemento dentinal junction (CDJ) were recorded. The average distance from the major foramen was -0.13 mm with a range of -1.28 mm and +0.46 mm. The average distance in 26 detectable CDJ samples was +0.18 mm with a range of -0.98 mm and +0.65 mm. The measurements, which were within +/- 0.5 mm, were 94% (29/31) from the major foramen and 92% (24/26) from the CDJ. Measurement consistencies within one SD were 81% for the major foramen and 65% for the CDJ, respectively. Measurements within two SD were 97% for the major foramen and 92% for the CDJ. There were no differences between the smaller (< # 25) and larger apical foramens (< or = 25) or vital and nonvital pulps.

In vitro measurement accuracy of an electronic apex locator in teeth with simulated apical root resorption

The purpose of this in vitro study was to evaluate the accuracy of Root ZX apex locator to determine the working length in teeth with simulated apical root resorption. Fifty extracted, single-rooted, human teeth with mature apices were used in this study. An irregular cavity defect was drilled at the apex of each tooth simulating an apical root resorption. Three operators used the Root ZX to measure the working lengths, comparing the electronic readings with the direct visual measurements. The Root ZX was 62.7%, 94.0%, and 100.0% accurate to within 0.5 mm, 1 mm, and 1.5 mm of the direct visual measurements, respectively. Statistically significant differences were observed between operator A and B and A and C (p < 0.01), but no significant differences were detected between operator B and C (p > 0.01).

Influence of the canal contents on the electrical assisted determination of the length of root canals

The purpose of this study was to compare the influence of the root canal status on the determination of the root canal length by an electronic apex locator in vital and necrotic canals and canals with root canal filling retrieval. One hundred seven teeth with a total of 171 canals with various contents (105 vital pulp, 47 necrotic pulp, and 19 retrieval of root canal filling materials) were measured for root canal length in vivo with the AFA Apex Finder. The distance between the file tip and the radiographic apex was also determined on radiographs. In 86% of the evaluated roots, the file tip position as indicated by the Apex Finder was located within 0.5 mm of a point 1.0-mm short of the radiographic apex. The Apex Finder showed higher accuracy for determining the apical constriction in vital canals (93.9%) than in necrotic canals (76.6%), and this difference was statistically significant (p < or = 0.05). The Apex Finder indicated the point -1 mm +/- 0.5 mm in canals with retrieval of root canal filling materials in 68.4% of these cases, but because of the small number of retrieval cases, this is not comparable statistically with vital and necrotic cases. The authors concluded that the AFA Apex Finder is highly accurate in vital canals.

Accuracy of a new apex locator: an in vitro study

AIM

The purpose of this study was to test in an in vitro model the accuracy of a Bingo 1020 electronic apex locator, to compare the results to those of a well known apex locator, Root ZX, as well as to those of the radiographic method of tooth length determination.

METHODOLOGY

A total of 120 extracted teeth, preserved in Thymol solution and kept refrigerated, was used for the study. The experiment was performed on single-rooted teeth and on one-root canal, chosen randomly, in multirooted teeth. The teeth were randomly divided into 12 groups of 10 teeth each. After access preparation, the actual length (AL) was measured. The teeth were embedded in an alginate model specially developed for testing apex locators. Electronic tooth length measurements (EL) were carried out prior to root canal preparation using the two electronic apex locators (EAL) - Root ZX and Bingo 1020; three measurements were taken and an average computed. After the third measurement, the file was left in the root canal and a periapical radiograph was taken. The radiographic length (RL) was recorded by measuring the file length from the coronal reference point to the tip of the file. Each root canal was then prepared to a no. 40 K-file diameter using a standardized technique; saline was used for irrigation. Upon completion of the root canal preparation, EL measurements were taken by each EAL in dry conditions and with different irrigation solutions. Each measurement was repeated three times. The RL was recorded according to the last EL measurement. Results were subjected to statistical analysis.

RESULTS

In all parameters tested, a significant statistical difference was found between Bingo 1020 and the Root ZX. Measurements obtained using the Bingo 1020 were consistently closer to the AL (0.08 mm) than those obtained using the Root ZX. Both EALs measured the tooth length with great accuracy and a positive correlation of 0.76 (P = 0.00) existed between the two devices. No significant difference was found between the two apex locators when measurements were taken with the different irrigants (P = 0.34) and the content of the root canal did not affect the accuracy of the measurements. Lengths obtained by calculations from the radiographs were longer than the AL as well as the length obtained by both EALs (P = 0.00).

CONCLUSIONS

The Bingo 1020 proved to be as reliable as Root ZX and was user friendly. Under the experimental conditions, electronic measurements were more reliable than radiographs in the process of root length determination.

Methodological considerations in the determination of working length

AIM

The aim of this study was to evaluate the diagnostic efficacy of an electronic system for the determination of working length, in comparison with two radiological methods (conventional film and digital radiography).

METHODOLOGY

The study sample consisted of 28 root canals belonging to 20 human mandibular teeth. A comparison was made between the working length measurements obtained by two radiological methods (conventional film and digital radiography) and an apex locator, using as gold standard the observation of the file position within the root following selective grinding of the root tissue.

RESULTS

The electronic method was satisfactory in 67.8% of cases, versus 50.6% and 61.4% for the conventional and digital radiological methods. respectively. No statistically significant differences occurred between the techniques according to the chi-squared and Kruskal-Wallis nonparametric tests.

CONCLUSIONS

None of the techniques was totally satisfactory in establishing the true working length. There were no differences between the techniques investigated.

Effect of using electronic apex locators on selected endodontic treatment parameters

The purpose of this study was to determine the effect of using electronic apex locators on the number of radiographs taken and the adequacy in length of the final obturation. Patients in an undergraduate student endodontics clinic participated in the study. The working length (WL) was estimated by the authors for all cases (36 teeth; 58 canals), using both a preoperative standardized radiograph and an electronic measurement. The students were then asked to place WL files to one of the estimates (electronic or radiographic; chosen by random assignment) and take a WL radiograph. Neither the students nor their instructors knew which method was chosen for the estimates. Once treatment was completed, the total number of working radiographs was counted. The number of cases with acceptable (0 to 2 mm short of the apex) or unacceptable obturation was also blindly registered. An electronic estimate of the WL improved length quality of the final obturation, compared with a radiographic estimate. The number of working radiographs taken was less in the electronic apex locator group in anterior and premolar teeth, but not in molars.

An in vitro comparison of two modern apex locators

Two apex locators were compared regarding their ability to accurately locate the apical constriction in the presence of various canal fluids at different meter readings. Forty-one root canals were filled with 1% NaOCl, 3% H2O2, and 0.9% NaCl, respectively. Electronic working length (EWL) measurements were recorded with the apex locators Root ZX (meter readings: "Apex", "0.5", and "1") and Apit (meter readings: "Apex" and "3"). The deviation of the EWL from the apical constriction was determined. The proportion of measurements within +/- 0.5 mm of the apical constriction ranged between 0.76 and 0.85 for Root ZX at the meter readings "Apex" and "0.5," regardless of the canal contents. Apit consistently displayed shorter measurement values than Root ZX and reached the highest proportions at the meter reading "Apex": 0.59 (1% NaOCl), 0.61 (3% H2O2), and 0.68 (0.9% NaCl). In the presence of NaOCl, Root ZX provides the more accurate EWL measurements at the meter reading "0.5" and "Apex."

Accuracy of four electronic apex locators: an in vitro evaluation

In the present study, the accuracy and operator dependency of four electronic canal length measuring devices (Apex Finder AFA Model 7005, Apex-Finder, Neosono Ultima EZ and Apit 2) were compared under a set of specified conditions. The electronic apex locators were tested in unflared dry, flared wet and flared dry canals, and in a gelatin as well as in a sodium hypochlorite sponge model. Fifteen extracted single-canaled teeth were selected. The differences between canal lengths obtained by the electronic apex locators and actual canal lengths were scored. Only the Apex-Finder was found to be unreliable (measurements higher than +/- 0.5 mm from the apical foramen). This device was also found to be particularly dependent on operator. A ranking based on a precision of +/- 0.1 mm from the apical foramen showed the Apex Finder AFA Model 7005 to be the most accurate. Early coronal flaring did not ensure better or more precise readings. The gelatin model was evaluated to be more suitable for testing electronic apex locators in vitro than the sodium hypochlorite model.

In vitro evaluation of the reliability of the Root ZX electronic apex locator

AIM

An experimental comparison of the Root ZX apex locator with the real measurement of the root canal length was carried out using a saline gel to simulate the periodontium.

METHODOLOGY

Lengths were taken when the needle reached the 0.5 mark and the Apex mark on the meter. These measurements were then compared with a calculated reference length representing the real length of the root canal. Reliability was assessed using Student's t-test. Precision was assessed using the mean and standard deviation of differences.

RESULTS

The Root ZX gave measurements within a range of 0.5 mm in 84.72% of the cases. The intra-operator and inter-operator variabilities were not statistically significant (P > 0.05).

CONCLUSIONS

The Root ZX is not capable of detecting the '0.5 mm from the foramen' position and thus, should only be used to detect the foramen (major diameter).

An in vivo evaluation of an electronic apex locator that uses the ratio method in vital and necrotic canals

The purpose of this study was to compare the canal length determined by an apex locator to the apical constriction in both vital and necrotic canals. Informed consent was obtained from patients waiting to have teeth extracted. The teeth were anesthetized, isolated, and accessed. The pulp was considered vital if bleeding was present in the pulp chamber. The Root ZX was used to measure the root canal length. The file was cemented into place, and the tooth was extracted. Twenty-nine teeth containing 34 cemented files were studied, and the distance from the apical constriction was measured. The Root ZX was 82.3% accurate to within 0.5 mm of the apical constriction. The mean distance from the apical constriction was 0.21 mm in vital cases versus 0.49 mm for necrotic cases. There was no statistical difference between the ability of the Root ZX to determine the apical constriction in vital canals versus necrotic canals.

Electronic length measurement using small and large files in enlarged canals

Electronic apex locators are frequently used attached to a small size endodontic file; however, the effect on the measurement of the relative diameters of the file and the root canal has not been clarified. In this study, the length of enlarged canals was measured using small size files and files matching the canal diameter to observe a possible discrepancy. The accuracy of electronic length control during canal preparation with rotary files was also assessed. The root canals in 21 extracted, single rooted teeth were accessed, and their actual length (AL) established by passing a size 10 file just through the minor apical foramen. The teeth were then embedded in an alginate mold. The initial canal length (IL) was measured with the Root ZX apex locator by negotiating a size 10 file to the apical constriction. The canal was enlarged to size 60 with rotary files while the length was continuously controlled with the apex locator. Then, the final length measurements were obtained with a size 10 file and a size 60 file (FL-10 and FL-60, respectively). The average values of IL, FL-10 and FL-60 were calculated and compared using Repeated Measures Analysis of Variance followed by Tukey's Studentized Range test (P < 0.05). Using composite resin, the size 60 files were secured at the FL-60 length, the teeth were removed from the alginate mold, stained with Picroformal DI Buoin stain and the position of the file tip was observed histomorphometrically after the apical 4 mm of the canal was exposed by grinding the buccal aspect of the root. The IL was 0.45 mm shorter than AL (P < 0.05). The differences between FL-10, FL-60 and IL were not statistically significant. Histomorphometrically, the apical constriction was absent in all the teeth, but the file tips were confined within the root. This study concluded that the Root ZX indicated the location of an apical constriction even when the anatomic constriction was eliminated. In the enlarged canals, length measurements obtained with small and large size files were comparable.

An in vivo evaluation of Root ZX electronic apex locator

The Root ZX has been introduced recently as a device capable of performing accurately in the presence of sodium hypochlorite, blood, water, local anesthetic, and pulpal tissues. The Root ZX was used to locate the apical foramen in 26 root canals of vital teeth. After extraction of the teeth, a stereomicroscope was used to confirm visually the relationship of the tip of the endodontic file to the apical foramen. The Root ZX located exactly the apical foramen in 17 canals (65.4%), was short in 1 canal (3.8%), and was overextended in 8 canals (30.8%). When a potential error of +/-0.5 mm from the foramen is accepted as a tolerable range for the clinical application of an electronic apex locator, the Root ZX was able to locate the foramen within this range in 25 teeth for a clinical accuracy rate of 96.2%.

In vitro evaluation of the accuracy of several electronic apex locators

This study describes two tests of the in vitro accuracy of several models of electronic canal length measuring devices (ECLMDs) using a gelatin test model and extracted human teeth with fully formed apices. In part 1, four previously untested ECLMDs were used in dry canals after access and pulpectomy. File lengths with wth file tip just visible at the foramen were compared to ECLMD lengths. Clinically significant ECLMD measurements of > or + 0.5 mm than visual length were noted with two ECLMDs 16.6% and 10% of the time. The other two ECLMDs had no measurements >0.5 mm than the visual measurement. The gelatin test model proved highly accurate with 4 of 6 ECLMDs tested thus far. Part 2 compared the accuracy of a previously tested ECLMD using the gelatin model when taking length measurements with canals both dry and wet with distilled water in them. There was no difference between measurements in wet or dry canals. Irrigation with distilled water may be a clinical aid when using resistance ECLMDs.

An in vivo evaluation of the ENDEX and RCM Mark II electronic apex locators in root canals with different contents

The accuracy of many apex locators is affected by electrolytes including sodium hypochlorite. According to the manufacturer a new device, the ENDEX, overcomes this problem. The purpose of this study was to assess the accuracy of the ENDEX in comparison with a traditional device, the RCM Mark II. The lengths of 61 canals with various contents (vital pulp, necrotic pulp, pus/exudate, sodium hypochlorite, and water) were determined in vivo. Files were cemented within the canals at lengths determined by the ENDEX. The teeth were then radiographed and extracted, and the distance between the file tip and apical foramen was recorded. Derived readings for the RCM Mark II were compared with the actual ENDEX reading and corresponding radiograph. The results indicated that most of the file tips that were at the radiographic apex actually extended through the apical foramen, and canal content had a varying effect on each device. The overall accuracy of the ENDEX (71.7%) was higher than that of the RCM Mark II (43.5%) within 0.5 mm of the apical foramen. The ENDEX, unlike the RCM Mark II, proved accurate in the presence of sodium hypochlorite.