Comparison of Accuracy of Dentaport ZX, Rootor and E-Pex Pro Electronic Apex Locators in Two Simulated Clinical Conditions: An In Vitro Study.

Background: The aim of this in vitro study was to determine the accuracy in measuring the working length (WL) using Dentaport ZX, Rootor, and a newly introduced budget friendly electronic apex locator (EAL), E-Pex Pro in two commonly simulated clinical conditions (in the presence of irrigant and blood). Materials and Methodology: Eighty-eight single-rooted premolars were randomly assigned to two groups according to simulated clinical conditions: Group 1: Presence of irrigant (5% NaOCl) and Group 2: Presence of blood. WL was determined with all three EAL and was then compared with actual length (AL) of the tooth, which was measured using Vision Inspection System. The difference between the length measured by EAL and AL was tabulated and statistically analyzed using one-way analysis of variance (ANOVA) with post hoc Dunnett's test. All testing was done using two-sided tests at alpha 0.05 (95% confidence level). Thus, the criteria for rejecting the null hypothesis were "P < 0.05."
Results: Measurement using Dentaport ZX, Rootor, and E-Pex Pro had an accuracy of 99.79%, 99.69%, and 99.64%, respectively, in Group 1 and 99.95%, 99.7%, and 99.74%, respectively, in Group 2. ANOVA revealed that the mean error value is least for Dentaport ZX followed by Rootor and then E-Pex pro EAL.
Conclusion: Dentaport ZX gave better results both in the presence of NaOCl and blood followed by Rootor and E-Pex Pro EALs. Copyright:

INTRODUCTION

Proper biomechanical preparation and disinfection of the root canal space are of paramount importance, and Apical Constriction (AC) is the point recommended up to which all instrumentation and obturation must terminate. Diligence in adhering to Working Length (WL) helps to ensure that neither the root canal system nor the periodontal ligament is damaged.[12]

Somma et al. and Saatchi et al. conducted in vivo studies and found that Dentaport ZX gave better results when compared to other electronic apex locator (EALs).[34] Another research done by Altunbaş et al. showed that Dentaport ZX gave the most accurate result, followed by rootor.[5] E-Pex Pro has recently been introduced and has gained worldwide popularity as compared to other EALs for its ease of use and accurate values.[6]

Hence, this study was done to determine the accuracy in measuring the WL using Dentaport ZX (Morita Co, Japan) – third-generation EAL, Rooter EAL (Meta Biomed, Korea), and a newly introduced budget friendly EAL namely E-Pex Pro (Eighteeth, China) – fourth-generation EAL, in two commonly simulated clinical conditions and comparing the actual length (AL) using Vision Inspection System (VIS). To the best of our knowledge, there are no published studies that have compared all these three EALs for determining the WL in the presence of NaOCl and blood. This study was designed according to CRIS Guidelines (Checklist for Reporting In-vitro Studies). The null hypothesis for this study states that there is no difference in the accurccy of WL determined for at least two out of the three EALs.

MATERIALS AND METHODOLOGY

Approval for this in vitro study was obtained from the Scientific Review Committee of the institute-176112018. Eighty-eight freshly extracted caries-free, single-rooted premolar teeth without any visible defects were randomly assigned to two groups (n = 44) after preparing standard access opening. Sample size was determined using One-way analysis of variance (ANOVA) power analysis. Ten extra samples were prepared to compensate for any loss of sample. Randomization was done by a nurse who was kept independent of the study.

In Group 1 (n = 44), root canals were checked for patency with a No: 10 size K file (Mani, Japan) and irrigated with 5 ml of 5% NaOCl (Prime Dental, India) using a 27G side vented needle (Prime Dental, India) to eliminate necrotic debris and pulpal remnants. Root canal instruments were not used to prevent enlargement of the canal. The canal was again irrigated in the similar manner with 5 ml of 5% NaOCl to remove the organic matter. In Group 2 (n = 44), the pulp remnants in the root canal were neither extirpated nor was irrigation done.

The sample teeth were immersed in a plastic container containing freshly mixed alginate and their roots embedded up to the cervical level. 0.5 ml of 5% NaOCl was injected into the canal in Group 1, and 0.5 ml of human blood sample freshly procured from blood bank was injected into the canal to reproduce the clinical condition of bleeding in Group 2.

Adequate care was taken to keep the alginate models moist hence readings were recorded within 2 h.

Using all the three EALs – Dentaport ZX EAL, Rootor EAL, and E-Pex Pro EAL, electronic measurements were recorded for each, respectively, when the reading remained stable for a minimum of 5 s.

Fresh irrigant or blood, respectively, was used to replenish the sample each time before the new EAL was used.

For each tooth sample, the procedure was repeated three times with three respective EAL, and the mean value was calculated and subsequently recorded.

After determining the WL using all three EALs, the AL of the root canal was determined till the minor apical foramen by viewing the sample directly in the following manner. The tooth was sectioned with a diamond disk longitudinally till the canal was fully visible in the longitudinal direction. The very same file that was used to measure the electronic WL was inserted, and the samples were observed under ×35 magnification using VIS for the AL determination. Distance between the silicon stop and minor apical foramen/AC was noted down, and this was the AL.

The comparison of the recorded AL using VIS and the values obtained with the EALs was done, and the difference was tabulated and subjected to statistical analysis.

Statistical analysis

The error between the groups was also compared between the three EALs using one-way ANOVA with post hoc Dunnett's test. All testing was done using two-sided tests at alpha 0.05 (95% confidence level). Thus, the criteria for rejecting the null hypothesis were “P < 0.05.”

RESULTS

The measurement using Dentaport ZX, Rootor, and E-Pex Pro EALs had an accuracy of 99.79%, 99.69%, and 99.64%, respectively, in Group 1 and 99.95%, 99.7%, and 99.74%, respectively, in Group 2 [Figure 1].

Figure 1

Multiple Comparison Graph Showing Mean of working length with Dentaport ZX, Rootor, and E-Pex Pro electronic apex locator

The mean error value was least for Dentaport ZX followed by Rootor and then E-Pex Pro EAL [Table 1 and Figure 2].

Table 1

Descriptive statistics of error in working length (accuracy) with different electronic apex locators

EAL	Error in WL
	Hypochlorite	Blood	All
Dentaport ZX
n	44	44	88
Mean	0.17	0.12	0.14
Median	0.17	0.17	0.17
SD	0.17	0.11	0.15
SEM	0.03	0.02	0.02
Rootor
n	44	44	88
Mean	0.22	0.22	0.22
Median	0.17	0.17	0.17
SD	0.15	0.14	0.14
SEM	0.02	0.02	0.02
E-Pex Pro
n	44	44	88
Mean	0.30	0.25	0.28
Median	0.33	0.17	0.33
SD	0.20	0.17	0.19
SEM	0.03	0.03	0.02

EAL: Electronic apex locator, WL: Working length, SD: Standard deviation, SEM: Standard error of mean

Figure 2

Multiple Comparison Graph Showing Mean of Error in working length with Dentaport ZX, Rootor, and E-Pex Pro electronic apex locator

Pairwise comparison of Dentaport ZX with Rootor and E-Pex Pro EALs demonstrated an error which was statistically significant (P < 0.05). Thus, the null hypothesis was rejected. However, the error between the Rootor and E-Pex Pro was comparable, but the difference was not statistically significant (P > 0.05). As the mean value of the error in WL using Dentaport ZX is the least, it provides the most accurate measure [Table 2].

Table 2

Post-hoc (Dunnet’s) pairwise comparisons for error (accuracy)

EAL		Mean difference (I-J)	SE	95% CI for difference		P
I	J			Lower	Upper
Dentaport ZX	Rootor	−0.075	0.022	−0.128	−0.023	<0.05
	E-Pex Pro	−0.133	0.025	−0.194	−0.073	<0.05
Rootor	Dentaport ZX	0.075	0.022	0.023	0.128	<0.05
	E-Pex Pro	−0.058	0.025	−0.117	0.002	>0.05
E-Pex Pro	Dentaport ZX	0.133	0.025	0.073	0.194	<0.05
	Rootor	0.058	0.025	−0.002	0.117	>0.05

EAL: Electronic apex locator, SE: Standard deviation, CI: Confidence interval

DISCUSSION

Canal preparation is a key aspect of endodontic treatment, and effective canal preparation can be achieved by determining the correct WL.[7] The WL calculation requires precision and skill, and there is a need to use techniques that provides accurate results. At the same time, the techniques of WL determination also need to take into consideration the issues of practicality and actual clinical conditions such as the presence of remnants of pulp tissue and irrigant.[8] Failure to determine the WL accurately can lead to incomplete cleaning, perforation through AC, incomplete apical seal which can lead to apical leakage, overfilling, or underfilling. All these lead to increased incidence of postoperative pain and diminish the success rate of root canal treatment.

Many in vitro studies have proven that the accuracy of EAL is up to 95% in determining the AC. The procedure used was as follows: AL was obtained by inserting a file into the canal until the file tip became just visible at the level of the apical foramen under ×5 magnification. The file was measured, and 0.5 mm was subtracted.[910] In a study done by Fouad and Reid, it was found that when the dental students used EAL, it resulted in better obturation length than when WL was determined using radiographs.[11] In many clinical studies, when EAL was compared with the radiographic measurement, efficiency of EAL was in the range of 81.5%–97%.[12]

Even though EALs are relatively accurate, factors such as severe hemorrhage and inflammatory exudate, calcified or blocked canals, and immature apices affect the efficiency of EAL.[131415] The newer generation EALs consist of powerful microprocessors and can calculate and generate mathematical quotients and algorithms for an accurate result.[16]

In this study, 5% NaOCl was used as it is the most commonly used irrigant and because in many studies when different concentrations of NaOCl were used, 5% NaOCl gave better results.[1718]

For this study, alginate was used as the embedding material as it has the similar electrical impedance as that of human periodontium.[19] Alginate is elastic, nonsticky, firm, and provides a smooth surface. The affordable cost, easy manipulation, and procurement make alginate a choice for in vitro test on EALs. However, there is a tendency for alginate to desiccate; unless it is kept in a moist environment. This limits the working time of alginate; hence, the measurements were taken within 2 h of model preparation.

In this study, Visual Inspection System (VIS) was used to determine the AL. In most of the previous studies, stereomicroscope was used to measure the AL.[62021] VIS is a much better option than stereomicroscope because the magnification of VIS is 50–200X (multi-layer coated lens), whereas magnification of stereomicroscope is 5–45X, travel for VIS is 100 mm, whereas for stereomicroscope is 6 mm and reading for VIS displays immediately on Digital Read Out, whereas for stereomicroscope measurement has to be done manually. To the best of our knowledge, no similar study has been done using VIS.

In this study, when the error in WL, i.e., the accuracy was evaluated, there was a significant difference, in which Dentaport ZX gave better result followed by Rootor and then E-Pex Pro EAL. The results obtained are similar to other studies.[2223]

On evaluating the accuracy of the Dentaport ZX and the Rootor EALs to detect root perforations both in dry canal as well as in the presence of NaOCl, Ethylenediaminetetraacetic acid (EDTA), and saline solution; Aggarwal et al. found out that Dentaport ZX gave significantly better results than rootor in the presence of all the irrigants.[23] This study has not evaluated the performance of EALs in perforations, but a limited inference may be drawn as to similar results obtained in both studies.

Dentaport ZX accuracy remains unaffected by the presence of electrolytes and can be allocated to the fact that the impedance of Dentaport ZX is measured at each frequency and the position of the file is determined from the ratio between impedances at higher and lower frequency. Different electrolytes have varied dielectric constants; change in the electrolyte material, which is a change in dielectric constant, will influence equally the numerator and denominator, and hence the final ratio will remain unaffected.

In a similar study by Taneja et al., canal Pro gave better result than Root ZX Mini and Apex ID when the accuracy was evaluated in the presence of NaOCl, blood and in open apex case. The samples in the present study are prepared in accordance to this study.[6]

In another study done by Prasad et al., on evaluation of the accuracy of Root ZX and i-Root EAL for determining WL in the presence of saline, NaOCl, chlorhexidine digluconate, and EDTA, it was concluded that Root ZX and i-Root gave almost similar results that were not statistically different.[22]

In a study carried out by Bilaiya et al., the accuracy of Root ZX Mini, I-Pex, and E-Pex Pro EALs was calculated in the presence of NaOCl, chlorhexidine, and EDTA to detect root perforations. It was observed that there was no significant difference in the accuracy of all three EALs, and the accuracy was enhanced in dry conditions.[24] This was the only study where E-Pex Pro EAL has been used. A literature search showed that no study has been done using E-Pex Pro EAL to evaluate their efficiency in simulated clinical conditions.

The limitation of this study is that it was done in in vitro conditions. In clinical conditions, we come across numerous challenges such as leakage of saliva through cervical caries or open margins, metallic restorations in adjacent or opposite teeth, or teeth with immature blunderbuss canal which can affect the efficiency of EAL.

CONCLUSION

The following conclusions can be drawn from this in vitro study:

Dentaport ZX gave better results both in the presence of NaOCl and blood followed by Rootor and E-Pex Pro EALs.

The performance of Dentaport ZX was superior to Rootor and E-Pex Pro EAL in the presence of irrigants and blood. It may be inferred that both Rootor and E-Pex Pro EALs are also reliable for the determination of WL. E-Pex Pro, being a more budget friendly EAL, is a good option for dentists who have started their practice and have budgetary constraints.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.