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

Variations in the morphology of apical constriction affecting electronic readings: An in vitro investigation using 3D-printed tooth models

We investigated the interference of apical constriction position and diameter on the accuracy of electronic apex locators using 3D-printed tooth models. Single-rooted tooth models with the same length, canal taper and major foramen, but variation in apical constriction position or size, were designed and 3D-printed. A mounting model was custom-made for precise measurement of both marks (0.5 and APEX/0.0) of two electronic apex locators. The electronic measurements of both devices were correlated significantly to the major foramen rather than apical constriction. The mean measurements of the group with 0.45 mm in apical constriction width were significantly shorter than those of the other groups for both marks of the two devices (p < 0.05). The variations in apical constriction position and width negatively affected the precision of the 0.5 mark of the tested devices. The 0.0 or APEX mark was consistently located the major foramen.

Kök Uçları Farklı Açılarda Rezeke Edilmiş Dişlerin Cerrahi Olmayan Yeniden Tedavilerinde 3 Elektronik Apeks Bulucunun Doğruluğu: In-Vitro Çalışma

Aim: The accuracy of three electronic apex locators (EALs) during retreatment of root-end resected teeth with different resection bevel angles were evaluated in the present study. Materials and Methods: Forty mandibular premolar teeth were divided into two groups regarding resection bevel angle after root canal filling. In the first group, the apical 3 mm of each specimen was resected at a 0-degree bevel angle using a diamond bur. The resection bevel angle was approximately 45-degree in the second group. Electronic length measurements were obtained with a size 15 K-file advanced apically in dissolved gutta percha using Dentaport ZX, Propex Pixi, and Apit 15. The filling materials were then completely removed from the root canals, and the actual lengths up to the resection region were determined. The actual length was subtracted from the electronic length measurements for each specimen. Measurements were analyzed statistically using independent sample t-test, repeated-measures analysis of variance, and Bonferroni tests. The level of statistical significance was defined as P

Influence of embedding media on the accuracy of working length determination by means of apex locator: an ex vivo study

The aim of this research was to determine ex vivo the influence on accuracy of five different embedding media, for investigative and educational purposes, and one electronic apex locator. 110 human extracted mature roots of permanent single-rooted human teeth were used. The roots were embedded in alginate, stick sponge, 2% agar–agar and 6% and 12% gelatin. The actual working length to the physiological foramen was determined under a stereo-microscope (16 ×) and the electronic working lengths with the Elements Diagnostic Unit and a K-file ISO 10. The accuracy ranges of the accumulated measurements, when allowing a ± 0.5 mm tolerance, went from 98.2% (6% and 12% gelatin), 93.7% (alginate), 92.8% (2% agar–agar) to 91.7% (sponge). The exact measurements at the physiological foramen ranged from 80.0% (6% gelatin), 76.5% (2% agar–agar), 71.8% (12% gelatin), 68.2% (alginate) to 64.5% (sponge). Although relatively seldom (n = 24), measurements with deviations of more than ± 0.5 mm were also observed; thus, the accuracy of the working length determination results per se can be considered as clinically acceptable. The results of this research allow a recommendation of the investigated embedding media for electronic working length determination models for educational and research purposes in endodontics.

Accuracy and stability of electronic apex locator length measurements in root canals with wide apical foramen: an ex vivo study

The aim of the current study was to determine the accuracy of electronic apex locator (EAL) measurements when using files of different sizes in roots with wide apical foramina while considering a new parameter of stability of EAL reading. Ten teeth with straight roots were subjected to a sequential widening of the apical foramen to 0.6, 0.7, and 0.8 mm. The roots were embedded after each enlargement stage in an alginate mold and subjected to EAL readings. Measurements were done using sequential K-file sizes and the self-adjusting file (SAF). Measurement stability was introduced as a new additional parameter. As the difference between the file size used and the apical diameter of the canal decreases, the results obtained were more accurate and stable. The stability and accuracy of the measurements coincided with each other in a statistically significant manner. Within the limitations of the present ex vivo study, it may be concluded that in straight canals with wide apical foramina of 0.6–0.8 mm, both SS K-files which fit snugly to the walls of apical foramen and the SAF file may offer both accurate and stable EAL measurements.

A comparative evaluation of two working length determination methods

The purpose of this study was to explore the level of agreement between the radiographic and the electronic apex locator (EAL) working length assessment methods, amongst teeth with different diagnoses. Working length measurements along with pulpal and periapical diagnoses data were collected from the Patient Registry Database of our Institution. The null hypothesis of this study was that pulp status does not affect the level of agreement between the two methods. The degree of agreement was assessed using the Bland-Altman method, followed by a Kruskal-Wallis test (a = 5%) that would allow the null hypothesis to be accepted. The EAL measurements agree in general with those provided by a 1.5 mm file placed coronal to the radiographic apex amid teeth with different pulpal diagnoses. Within the limitations of this study, we suggest that this setting (i.e. the distance) may be applied to all cases of endodontically treated teeth, despite the differences in pulpal diagnosis.

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.

Influence of different sized files on the accuracy of two electronic apex locators

The aim of this study was to evaluate the impact of different file sizes on the accuracy of two electronic apex locators (EALs). Thirty extracted human single-rooted permanent mandibular incisors were used. A #10 K-file was inserted in the root canal until its end could be observed (using a light microscope) through the apical foramen. One millimetre was subtracted to establish working length (WL). Electronic readings were performed using MiniApex Locator or Root ZX II, from #10 K-file to #130 K-file. Statistical analysis was performed by two-way anova and Tukey test (P ≤ 0.05). From #60 to #130 K-file, observed differences were noted between the values obtained with both EALs and WL (P ≤ 0.05). The MiniApex Locator showed increased means when measurements were made with #50 to #70 and with #120 (P = 0.008) and #130 (P = 0.005) K-files. File sizes influenced the accuracy of EALs - the greater the instrumentation size, the higher mean differences compared to WL.

In vitro evaluation of Root ZX and Raypex 6 in teeth with different apical diameters

Background:

There is a growing interest about electronic apex locators for working length determination. There are several studies dealing with their performance in different conditions.

Aims:

The aim of this study is to evaluate the accuracy of Root ZX and Raypex 6 in teeth with different apical diameters.

Materials and Methods:

Actual working length (AWL) of 80 single rooted teeth were determined as 0.5 mm short of apical foramen. The teeth were divided into 4 groups (n = 20). First group (G 0) included teeth with mature apices. Root canals of the other groups (G 32, G 57 and G 72) were enlarged until apical sizes of 0.32, 0.57 and 0.72 mm were obtained. Samples were embedded in alginate and electronic measurements (EM) were performed.

Statistical analysis:

was achieved with Fisher exact test.

Results:

Both devices revealed a high rate of success in G 0 and G 32. Their accuracy decreased significantly in G 57 and G 72 groups (P < 0.05). Intra-group results of Root ZX and Raypex 6 were similar (P > 0.05).

Conclusions:

Root ZX and Raypex 6 are reliable in teeth with mature apices. At foramen diameters exceeding 0.57 mm, their accuracy is susceptible.

Influence of root canal curvature on the accuracy of an electronic apex locator: An in vitro study

OBJECTIVE

This study investigated whether the canal curvature has an influence on the accuracy of Electronic Apex Locator.

MATERIALS AND METHODS

Sixty mandibular posterior teeth were decoronated. A number (No.) 10 file was inserted into the mesiobuccal canal and radiographs were taken to determine the degree of curvature by Schneider's method. Samples were divided into three groups of mild (<20°), moderate (20-36°) and severe curvature (>36°). After enlarging the orifice, the actual canal length was determined by introducing a file until the tip emerged through the major foramen when observed under 20X magnification. The teeth were embedded in an alginate model and the Root ZX was used to determine the electronic length. The data was analyzed by Kruskal-Wallis test followed by Mann-Whitney test.

RESULTS

The difference in measurement of Actual and Electronic working length was statistically significant between group 1 and 2 (P < 0.05) as well as between group 1 and group 3 (P < 0.05) with group 1 showing the lowest difference.

CONCLUSION

Considering ± 0.5 mm as tolerance limit for accuracy, the device was 95% accurate for the mild curvature group and 80% accurate for moderate and severe groups.

Accuracy of three electronic apex locators in determining the apical foramen in multi-rooted teeth: Randomised clinical and laboratory study

This study aimed to compare the accuracy of three electronic apex locators (EALs), Raypex 5, Apex NRG and ProPex II, in locating the apical foramen (AF) in vivo. Thirty multi-rooted teeth were included in the study. Distances from the file tip to the radiographic apex from the buccal (R1) and mesial (R2) aspect were measured after extraction. The distance from the file tip to the AF (L) was measured microscopically. Raypex 5, Apex NRG and ProPex II were accurate to within ± 0.5 mm in 84.6%, 78.6% and 66.7% of cases, respectively. R1, R2 and L measurements between the EALs were not statistically different (P > 0.05). R1 and L correlated positively (r(2) = 0.817; P < 0.001). There were no significant differences in all measurements between vital and non-vital root canals (P > 0.05). There was no statistically significant difference between the EALs. There was a positive correlation between electronic and radiographic measurements when locating the AF.

Accuracy of the Dentaport ZX apex locator for working length determination when retreating molar root canals

The aim of this study was to evaluate the accuracy of the Dentaport ZX apex locator for working length determination during root canal retreatment of mandibular molars. Fifteen extracted mandibular first molars with separate mesial canals and apical foraminae and one distal canal were selected. The mesiobuccal and distal canals were investigated; the length with the file tip at the major diameter was defined as the tooth length (TL). The canals were prepared with ProTaper files to 1 mm short of this and filled with gutta-percha and AH Plus sealer. One week later, the root fillings were removed using ProTaper retreatment files. Tooth length was remeasured and recorded as the retreatment tooth length (RTL). Then electronic measurements were taken at the major (electronic apex locator (EAL) major) and minor (EAL minor) foraminae as suggested by the instrument display. These lengths were compared with RTL and measurements 0.5 and 1 mm short of this distance. For both canals, no significant difference was found between RTL and EAL major, and 0.5 mm short of RTL and EAL minor (P > 0.05). There were significant differences found between all other readings. The Dentaport ZX could not detect the minor foramen accurately but was able to indicate the major foramen in molars undergoing a root canal retreatment procedure.

Accuracy of five electronic foramen locators with different operating systems: an ex vivo study

OBJECTIVE

The aim of this study was to evaluate, ex vivo, the precision of five electronic root canal length measurement devices (ERCLMDs) with different operating systems: the Root ZX, Mini Apex Locator, Propex II, iPex, and RomiApex A-15, and the possible influence of the positioning of the instrument tips short of the apical foramen.

MATERIAL AND METHODS

Forty-two mandibular bicuspids had their real canal lengths (RL) previously determined. Electronic measurements were performed 1.0 mm short of the apical foramen (-1.0), followed by measurements at the apical foramen (0.0). The data resulting from the comparison of the ERCLMD measurements and the RL were evaluated by the Wilcoxon and Friedman tests at a significance level of 5%.

RESULTS

Considering the measurements performed at 0.0 and -1.0, the precision rates for the ERCLMDs were: 73.5% and 47.1% (Root ZX), 73.5% and 55.9% (Mini Apex Locator), 67.6% and 41.1% (Propex II), 61.7% and 44.1% (iPex), and 79.4% and 44.1% (RomiApex A-15), respectively, considering ±0.5 mm of tolerance. Regarding the mean discrepancies, no differences were observed at 0.0; however, in the measurements at -1.0, the iPex, a multi-frequency ERCLMD, had significantly more discrepant readings short of the apical foramen than the other devices, except for the Propex II, which had intermediate results. When the ERCLMDs measurements at -1.0 were compared with those at 0.0, the Propex II, iPex and RomiApex A-15 presented significantly higher discrepancies in their readings.

CONCLUSIONS

Under the conditions of the present study, all the ERCLMDs provided acceptable measurements at the 0.0 position. However, at the -1.0 position, the ERCLMDs had a lower precision, with statistically significant differences for the Propex II, iPex, and RomiApex A-15.

Effect of pre-flaring and file size on the accuracy of two electronic apex locators

OBJECTIVE

This ex vivo study evaluated the effect of pre-flaring and file size on the accuracy of the Root ZX and Novapex electronic apex locators (EALs).

MATERIAL AND METHODS

The actual working length (WL) was set 1 mm short of the apical foramen in the palatal root canals of 24 extracted maxillary molars. The teeth were embedded in an alginate mold, and two examiners performed the electronic measurements using #10, #15, and #20 K-files. The files were inserted into the root canals until the "0.0" or "APEX" signals were observed on the LED or display screens for the Novapex and Root ZX, respectively, retracting to the 1.0 mark. The measurements were repeated after the preflaring using the S1 and SX Pro-Taper instruments. Two measurements were performed for each condition and the means were used. Intra-class correlation coefficients (ICCs) were calculated to verify the intra- and inter-examiner agreement. The mean differences between the WL and electronic length values were analyzed by the three-way ANOVA test (p<0.05).

RESULTS

ICCs were high (>0.8) and the results demonstrated a similar accuracy for both EALs (p>0.05). Statistically significant accurate measurements were verified in the pre-flared canals, except for the Novapex using a #20 K-file.

CONCLUSIONS

The tested EALs showed acceptable accuracy, whereas the pre-flaring procedure revealed a more significant effect than the used file size.

Critical diameter of apical foramen and of file size using the Root ZX apex locator: an in vitro study

INTRODUCTION

An evaluation was made of the accuracy of the Root ZX apex locator (J. Morita Corp, Tokyo, Japan) in widened foramina, considering the existing controversy over this issue in the literature.

METHODS

Ten single-root teeth were embedded in an alginate mold. The foramina were widened from 0.6 mm to 1.0 mm. The measurements were taken with all possible file sizes ≥#10. The statistical accuracy of the Root ZX was calculated for the different diameters and for the influence of file size.

RESULTS

The accuracy of the Root ZX apex locator with a range of error of ±0.5 mm was 87% in an apical foramen size of 0.6 mm and 84% using files size 45 or larger in an apical foramen size of 0.7 mm. With a tolerance of ±1 mm, the accuracy was 99% in an apical foramen size of 0.6 mm, 98% using files size 45 or larger in an apical foramen size of 0.7 mm, and 95% using files size 70 or larger in an apical foramen size of 0.8 mm. In the rest, accuracy was not certain. The measurements taken with smaller files were shorter. There were no cases of overestimation of the working length.

CONCLUSIONS

The Root ZX apex locator was accurate for an apical size of 0.6 mm, independently of the file size; between 0.7 to 0.8 mm, we should adjust the files to the foramen, whereas above size 0.9 mm the locator is not accurate. The results show that the accuracy of this electronic apex locator is gradually lost as the foramen widens. Considering the stable conditions of in vitro studies, our findings advise caution in clinical application of the locator.

Influence of preflaring on the accuracy of length determination with four electronic apex locators

INTRODUCTION

The aim of this study was to compare the influence of preflaring on the accuracy of 4 electronic apex locators (EALs): Root ZX, Elements Diagnostic Unit and Apex Locator, Mini Apex Locator, and Apex DSP.

METHODS

Forty extracted teeth were preflared by using S1 and SX ProTaper instruments. The working length was established by reducing 1mm from the total length (TL). The ability of the EALs to detect precise (-1mm from TL) and acceptable (-1+/-0.5 mm from TL) measurements in unflared and preflared canals was determined.

RESULTS

The precise and acceptable (P/A) readings in unflared canals for Root ZX, Elements Diagnostic Unit and Apex Locator, Mini Apex, and Apex DSP were 50%/97.5%, 47.5%/95%, 50%/97.5%, and 45%/ 67.5%, respectively. For preflared canals, the readings were 75%/97.5%, 55%/95%, 75%/97.5%, and 60%/87.5%, respectively. For precise criteria, the preflared procedure increased the percentage of accurate electronic readings for the Root ZX and the Mini Apex Locator (P < .05). For acceptable criteria, no differences were found among Root ZX, Elements Diagnostic Unit and Apex Locator, and Mini Apex Locator (P > .05). Fisher test indicated the lower accuracy for Apex DSP (P < .05).

CONCLUSIONS

The Root ZX and the Mini Apex Locator devices increased significantly the precision to determine the real working length after the preflaring procedure. All the EALs showed an acceptable determination of the working length between the ranges of+/-0.5mm except for the Apex DSP device, which had the lowest accuracy.

In vitro evaluation of the accuracy of five different electronic apex locators for determining the working length of endodontically retreated teeth

The aim of this study was to evaluate the accuracy of five electronic apex locators (EALs) in determining the working length (WL) of teeth after removal of the root canal obturation materials. A total of 32 extracted straight, single-rooted teeth were used. The actual canal length (AL) was determined and the WL was established by subtracting 0.5 mm from the AL. The root canals were instrumented and divided into two groups. One group (n = 6) served as control, while the other group (n = 26) was the experimental group. In the experimental group, the root canals were obturated using vertically compacted gutta-percha with AH 26 sealer. In both groups, the access cavities were restored with a provisional restoration and stored for 15 days at 37 degrees C and 100% humidity. The root canal obturation material was removed, and the teeth were then mounted in an experimental apparatus. Five EALs were used: Dentaport ZX, ProPex, Foramatron D10, Apex NRG and Apit 7. For the electronic measurement of canal length, a size 25 K-file was used. During measurement, the canal was irrigated with 2.5% sodium hypochlorite. The difference (D) between the AL and the electronically determined length (EDL), AL-EDL, was calculated and recorded for each measurement. Data were analysed by two-way anova and Fisher's PLSD test. In both groups, statistically significant differences were found among the EALs (P < 0.01). In conclusion, the Dentaport ZX, ProPex and Foramatron D10 were more accurate than the other two EALs in determining the WL in teeth after removal of the root canal obturation materials. However, the Apex NRG and Apit 7 were also reliable for determination of the WL in the majority of the cases.

Accuracy of three different electronic apex locators in detecting simulated horizontal and vertical root fractures

The aim of this in vitro study was to evaluate the accuracy of three electronic apex locators (EALs): Root ZX, Foramatron D10 and Apex NRG, in the detection of fractures in teeth having simulated horizontal and vertical root fractures. A total of 90 extracted intact, straight, single-rooted teeth were divided into six groups of 15 teeth each. In Groups A, B and C, an incomplete horizontal fracture was simulated by preparing a horizontal incision in the coronal, middle or apical portion of the root until the circumferential half of the canal was exposed in the horizontal plane respectively. In Groups D, E and F, an incomplete vertical root fracture was simulated by preparing a vertical straight incision to expose the canal in the coronal, middle or apical portion of the root all the way in the longitudinal plane respectively. The simulated fractures were 0.25 mm in thickness in all groups. The teeth were embedded in 1% agar and the canals were irrigated with saline solution during electronic measurement. Detection of the simulated root fractures was established with a size 10 K-file when the meter value reached 'APEX' on each EAL. In Groups A, B and C, Kruskal-Wallis tests revealed that there were no statistically significant differences between the three EALs. However, statistically significant differences were found among the EALs in Groups D, E and F (P < 0.0001, one-way anova and Tukey's post-hoc test). In conclusion, the three EALs tested were accurate and acceptable clinical tools in the detection of horizontal root fractures. However, the three EALs were unreliable in detecting the position of vertical root fractures.