Accuracy of two root canal length measurement devices integrated into rotary endodontic motors when removing gutta-percha from root-filled teeth

An Ex-Vivo Study Comparing the Accuracy of the E-Connect S+ and Morita Tri Auto ZX2+ Endodontic Handpieces in Root Canal Length Determination

INTRODUCTION

This ex vivo study evaluated the accuracy of the Electronic Apex Locator (EAL) and Automatic Apical Stop (AAS) functions of the E-Connect S+ and Morita Tri Auto ZX2+ cordless apex locators in determining patency length.

METHODS

Sixty-four human teeth with a single root were randomly allocated into E-connect or Morita groups (n = 32). The canals were accessed and preflared, after which a size 15 K-file was inserted into the canal to the major foramen and recorded as the actual length (AL). Matched measurements were taken using the AAS and EAL functions and visually confirmed with confocal microscopy. The variance between canal length (mm), the persons correlation (ρ) between function and AL, and the accuracy (%) of the canal length relative to the AL (Δmm) between devices and functions were assessed.

RESULTS

Regardless of device or function, all measurements were within 1±Δmm and correlated strongly (ρ > 0.97) with the AL. When considering a more stringent clinically acceptable range of 0.5±Δmm from the AL, all devices and functions demonstrated similar accuracy levels (84%-94%). However, at lower tolerance ranges, the E-connect device with the EAL function exhibited the highest accuracy. On average, all devices and functions stopped short of the AL (mean Δmm>0).

CONCLUSION

The E-Connect S+ and Morita Tri Auto ZX2+ apex locators provided reliable accuracy in determining the position of the major foramen. These findings demonstrate a high level of reproducibility in canal length measurements using both cordless endodontic handpieces, regardless of whether the EAL or AAS functions were employed.

Influence of endodontic motors on the behaviour of root canal shaping instruments: an in vitro comparative study

AIMS

The endodontic literature reports a lot of comparative study on endodontic instruments, concerning as well their geometry, instrumental dynamics, material, mechanical behavior or heat treatment. However, to our knowledge, no study has focused on the influence of endodontic motors on the shaping abilities of endodontic instruments. Thus, the aim of this study was to analyze the influence of the endodontic motors on root canal shaping instruments.

METHOD

Dual Move (MICRO-MEGA, Besançon, France), Canal Pro CL2i (COLTENE, Alstätten, Suisse), Canal Pro Jeni Motor (COLTENE, Alstätten, Suisse), Ai Motor (WOODPECKER, Guilin, China), Wave One motor (VDW, Postfach, Munich) and Smart A (WOODPECKER, Guilin, China) were pre-clinically compared in continuous rotation and reciprocating motion on a traction/compression bench using resin blocks. Canal shaping in continuous rotation and reciprocating motion were performed with One Curve and One RECI instruments (MICRO-MEGA, Besançon, France), respectively. The penetration/removal forces, making it possible to objectify the cutting effect and screwing effect of the instruments during root canal shaping, were analyzed.

RESULTS

The results showed (i) that endodontic motors influence the mechanical behavior of endodontic instruments, (ii) that the influence of the motors is essentially felt during reciprocating motion and (iii) that the reciprocating angles influence the mechanical behavior of endodontic instruments.

CONCLUSION

Only endodontic instruments are widely studied in literature while endodontic motors have a direct influence on root canal treatment. This study analyzes the influence of the endodontic motors on root canal shaping instruments. This study tends to demonstrate that Jeni Motor could optimize the mechanical behavior of endodontic instruments.

Evaluation of foramen locating accuracy of an endodontic motor integrated with electronic foramen employing optimal glide path kinematics

OBJECTIVE

This study aimed to evaluate the accuracy of the auto apical function in the maintenance of the apical limit of instrumentation during glide path procedures when associated to OGP kinematics of Tri Auto ZX2, compared to the continuous rotation of the same motor, as well as Root ZX II and VDW Gold.

MATERIALS AND METHODS

Forty-eight extracted human mandibular single-rooted premolars were selected. After endodontic access, cervical pre-flaring was performed using size 30, 0.10 taper rotary instruments, and the apical foramen size was standardized to 200 μm. Teeth were randomly divided into four groups (n = 12) according to the device and kinematics. For all the groups, the Auto Apical Stop function (AAS) was set to the 0.0 mark. Glide path instruments size 25, .01 taper were activated inside the canals until the apical limit was reached. Then, the files were fixed with cyanoacrylate to the teeth and decoupled from the equipment. Data were statistically analyzed in GraphPad Prism 6.0 software with the significance set at 5% (Kruskal-Wallis tests).

RESULTS

There was no difference in the mean deviation between the groups. No significant difference was found among the groups when the distributions and percentages of differences between the file tip and the apical foramen were compared (P > 0.05).

CONCLUSION

The use of auto apical function at the 0.0 mark of all tested devices provided an adequate control of the apical limit during glide path preparation. Foramen locating accuracy of Tri Auto ZX2 in OGP kinematics was similar to those of Tri Auto ZX2, Root ZX II, and VDW Gold in continuous kinematics.

CLINICAL RELEVANCE

Clinical strategies in canal negotiation and glide path as OGP motion associated to electronic foramen locators could reduce iatrogenic risk of deviation and file fractures and create an easier initial preparation to facilitate endodontic procedures.

Is canal overinstrumentation able to produce apical root dentinal microcracks in extracted teeth?

AIM

To assess the impact of mechanical overinstrumentation of root canals in extracted teeth on the development of dentinal microcracks in the apical portion of the root by means of micro-computed tomographic (micro-CT) analysis. Root canal preparation short of the canal terminus and at the apical foramen (AF) were used as controls.

METHODOLOGY

Twenty 2-rooted maxillary premolars with two canals were selected, scanned in a micro-CT device and the root canals prepared sequentially using Reciproc M-Wire R25 instruments to working lengths: 1 mm short of the AF (AF - 1 mm), at the AF (AF), and overinstrumentation (AF + 1 mm). A micro-CT scan of each specimen was performed after each time point. After reconstruction and co-registration procedures, the images were screened from the cementoenamel junction to the apex (n = 55 352) to identify the presence of dentinal microcracks in the apical third of the root.

RESULTS

After the analyses of 55 352 slices, dentinal microcracks were visualized in 12.45% of the images (6892 slices), with 5.73% (3174 slices) in the cervical, 3.57% (1976 slices) in the middle and 3.15% (1740 slices) in the apical third. All dentinal microcracks observed at all time points (AF - 1 mm, AF and AF + 1 mm) were already present in the corresponding images before canal instrumentation. Therefore, no new microcracks were detected, regardless of the working length used for canal instrumentation.

CONCLUSION

Reciprocating root canal preparation either short, at or beyond the AF (overinstrumentation) did not create dentinal microcracks in the roots of extracted 2-rooted maxillary premolars.

Evaluation of the accuracy of different apex locators in determining the working length during root canal retreatment

Background. This study aimed to assess the accuracy of three electronic apex locators (EALs) (Dentaport ZX [J Morita, Tokyo, Japan], Propex Pixi [Dentsply Maillefer, Ballaigues, Switzerland], and iPex II [NSK, Tokyo, Japan]) during root canal retreatment. Methods. The root canal lengths of 90 extracted single-rooted human teeth were determined under a dental operating microscope at ×10 magnification. The actual working length (AWL) was 0.5 mm less than the root length. Electronic measurements were performed with the three EALs. The root canals were instrumented and filled to the actual working length using the lateral compaction technique. After seven days, the teeth were retreated until the retreatment file was applied to the root canal at the working length determined by EALs, and then, the three EALs were used for determining the retreatment working length. Data were analyzed using chi-squared and Kruskal-Wallis tests. Results. In the retreatment, the accuracy of EALs was reported at %83.3 for Dentaport ZX, %83.4 forPropex Pixi, and %80 for iPex II within a tolerance of 0.5± mm of the AWL. Conclusion. Under the limitations of this study, Dentaport ZX, Propex Pixi, and iPex II can be a useful adjunct during retreatment. Clinicians should be aware that residual materials in the root canal during retreatment can affect the accuracy of EALs.

Accuracy of electronic apical functions of a new integrated motor compared to the visual control of the working length-an ex vivo study

OBJECTIVES

To evaluate ex vivo the efficacy of the integrated motor Tri Auto ZX2 in controlling the apical extent of preparation compared to conventional visual control (CVC) of the working length (WL).

MATERIALS AND METHODS

Eighty standardized mandibular premolars were divided into five groups (n = 16). In the CVC group, instruments were used in continuous rotation (CR) and visual control performed by means of rubber stoppers. For each of the remaining groups, it was assigned a combination of a motion (CR or optimal torque reverse (OTR)), and an apical function (Auto Apical Reverse (AAR) or Optimum Apical Stop (OAS)). Root canals were prepared using the apical functions at 0.5 mark using an alginate model. Difference between the final WL and the actual length post-instrumentation was calculated. Data were analyzed statistically with the significance set at 5% (ANOVA, Tukey HSD).

RESULTS

There was no difference in the mean WL among the groups, except between the CR combined to OAS compared to CVC (P > 0.05). Although CVC resulted in two cases beyond the foramen, no significant difference was found among the groups when comparing the distributions of measurements (P > 0.05).

CONCLUSIONS

All combinations of motion and apical control functions of Tri Auto ZX2 provided an adequate apical limit ex vivo, similar to the visual control using rubber stoppers.

CLINICAL RELEVANCE

TriAuto ZX2 was efficient to control the apical extent of preparation dispensing the need for calibrating the files, regardless of the different settings. This motor might potentially prevent over-instrumentation by continuously monitoring the apical limit.

Comparison of four electronic root canal length measurement devices

OBJECTIVE

The objective of this study is to evaluate the performance of four electronic root canal length measurement devices (ERCLMDs) [Root ZX, Raypex 6, ProPex II, and VDW Gold with ERCLMD] in wet and dry root canals with different major foramen diameters, in association with three file positions within the final 1 mm of canals.

MATERIALS AND METHODS

Fifty roots were divided into five groups that were instrumented apically to the terminus diameter using K-files 15, 20, 30, 40, and 60. ERCLMD measurements were made when the file tip was at major foramen, 0.5 mm and 1.0 mm short of the foramen, when the apex touched to the surface of saline or was immersed 3 mm into saline, and when the canal was dry or was irrigated with saline. The differences between the electronic lengths and the actual lengths were calculated. The data were analyzed using the three-, two-, and one-way ANOVA and the LSD test (p < .05).

RESULTS

Overall, the four ERCLMDs demonstrated 12.8% unstable and beyond the foramen measurements (11.3%). About 85% of the beyond the foramen measurements had foramen diameters 0.40 and 0.60. ERCLMD comparisons related to the file positions in the foramen diameters showed significant differences between ERCLMDs in each foramen diameter (p < .05).

CONCLUSIONS

All ERCLMDs provided highly accurate measurements within the final 1 mm of the foramen. Wet or dry canals and apex conditions did not adversely affect the accuracy of the ERCLMDs' readings. ProPex II located the file positions in the teeth with different foramen diameters more accurately than the other ERCLMDs.

An ex vivo comparison of working length determination by three electronic root canal length measurement devices integrated into endodontic rotary motors

AIM

The objective of this study was to compare the accuracy of working length (WL) determination by X-Smart Dual, ENDOAce, and Gold Reciproc motor, in manual mode and mechanical preparation set to auto apical reverse (AAR) mode.

MATERIALS AND METHODS

Forty-five anterior teeth were included in the study. The canal length was determined by introducing #10 file into the canal until it emerged at the apical foramen. The incisal edges were adjusted to obtain 18 mm standard length. The teeth were embedded in Plexiglas tubes, filled with alginate, and measured in manual and AAR modes.

RESULTS

Within and between the groups, there was no significant difference in WL measurements, both in manual and AAR modes. In the X-Smart Dual group, all manual measurements were within root canal limits, while 13 % of AAR mode measurements were recorded when the file tip passed the apical foramen. In the ENDOAce group, 13 and 7 % of the measurements, in manual and AAR modes respectively, were recorded when the file tip passed the foramen. In the Gold Reciproc motor group, 27 and 33 % of the measurements, in manual and AAR modes respectively, were recorded when the file tip passed the foramen.

CONCLUSION

With the limitation of this ex vivo study, the tested devices presented no significant differences in length measurements and were within the clinical accepted margin of error.

CLINICAL RELEVANCE

Mechanical preparation must be confined to the root canal system. The adverse results of overinstrumentation emphasize the need to reconsider the ±0.50 mm margin of error that is clinically acceptable for WL measurements.

Influence of instrument size and varying electrical resistance of root canal instruments on accuracy of three electronic root canal length measurement devices

AIM

To evaluate the influence of instrument size and the effect of the electrical resistance of endodontic instruments on the accuracy of three electronic root canal length measurement devices (ERCLMDs).

METHODOLOGY

Thirty single-rooted extracted human teeth were divided into three groups (n = 10) on the basis of the ERCLMD used: Root ZX II (J. Morita, Kyoto, Japan); ProPex (Dentsply Maillefer, Ballaigues, Switzerland); and iPex II (NSK, Tochigi, Japan). The electronic working length measurements (EWL) were made with K-files in the sequence sizes 08, 10, 15, 20, 25 and 30. The actual working length (AWL) was calculated by fixing a size 30 K-file in the canal and exposing the apical 5 mm of the root. The minor foramen was identified under an optical microscope, and its distance from the file tip was calculated. The accuracy of the ERCLMDs was evaluated in terms of percentages of accurate measurements (0.0 mm tolerance) and measurements with tolerance limits of ±0.5 mm and ±1.0 mm. The findings were analysed with the McNemar test, Pearson's chi-square tests and two-way analysis of variance. The multiple comparison procedures were carried out using Holm-Sidak method. The maximum electrical resistance tolerated by ERCLMDs was evaluated by connecting commercially available resistors between the file clip and the root canal instrument. The resistance was gradually increased until it started to affect the ERCLMD readings.

RESULTS

The ERCLMDs were able to actually locate the minor foramen in 7% of samples. File size did not affect the accuracy of ERCLMDs (P > 0.05). Overall, the ERCLMDs gave 65% readings within a tolerance limit of ±0.5 mm and 90% within a tolerance of ±1.0 mm. The electrical resistance of endodontic files was less than the maximum electrical resistance tolerated by ERCLMDs (0.6-1 Ω vs. 2500-4000 Ω).

CONCLUSIONS

The size of the root canal instrument did not affect the accuracy of ERCLMDs in this laboratory study.

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.

An in vitro stereomicroscopic comparative evaluation of a combination of apex locator and endodontic motor with an integrated endodontic motor

Objective:

To compare the efficacy of an integrated apex locator and an apex locator and endodontic motor assembly in maintaining the working length when operated under autoreverse mode.

Study Design:

Thirty distobuccal roots of intact maxillary first molars were taken and access cavities were prepared. The teeth were divided into Group I: Prepared with TCM Endo V and Group II: Prepared with ProPex and NSK assembly. The instrumentation was ended in ProTaper F3 file, which was cemented in the canal. The roots were sectioned, observed under a stereomicroscope and the distance from instrument tip to the apical foramen was measured.

Results:

Mean difference in the deviation of two groups was 0.075 mm, P = 0.34 (>0.05) which was statistically insignificant when assessed with unpaired t-test.

Conclusion:

The assembly of ProPex-NSK Endo-mate DT and the apex locating endomotor TCM Endo V Nouvag are clinically acceptable.

In vivo evaluation of the iPex and Root ZX electronic apex locators using various irrigants

AIM

To evaluate in vivo the performance of the iPex and Root ZX electronic apex locators (EALs) in the presence of several irrigant solutions: 2.5% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX).

METHODOLOGY

Thirty-two single-rooted human teeth that were scheduled for extraction were selected. Teeth with metallic restorations, fractures, root resorption, pulp necrosis or open apices were not included The working length (WL) was determined electronically for the root canals with the iPex and Root ZX EALs in the presence of two different irrigant solutions, 2.5% NaOCl and 2% CHX. After the teeth had been extracted, a size 10 K-file was used to determine the reference working length (RWL), which was established at 0.5 mm short of the major foramen. In each case, the RWL was subtracted from the electronic measurements. Positive values indicated electronic measurements that exceeded the RWL (long measurements), whereas negative values indicated measurements that were short of the RWL. The values obtained with the different irrigants and EALs were compared using the paired t-test. Significance was set at P < 0.05.

RESULTS

The accuracy of the iPex nor Root ZX EAL was not affected by 2.5% NaOCl or 2% CHX (P > 0.05). However, significant differences were observed between the readings of the iPex and Root ZX, irrespective of whether 2.5% NaOCl or 2% CHX was used as the irrigant (P < 0.05). The iPex was less accurate than the Root ZX in determining the RWL.

CONCLUSIONS

The accuracy of neither the iPex nor Root ZX EAL was affected by the irrigant used. However, the iPex was less accurate than the Root ZX in determining the RWL both for 2.5% NaOCl and for 2% CHX.

Effects of Dissolving Solutions on the Accuracy of an Electronic Apex Locator-Integrated Endodontic Handpiece

The effects of three dissolving agents on the accuracy of an electronic apex locator- (EAL-) integrated endodontic handpiece during retreatment procedures were evaluated. The true lengths (TLs) of 56 extracted incisor teeth were determined visually. Twenty teeth were filled with gutta-percha and a resin-based sealer (group A), 20 with gutta-percha and a zinc oxide/eugenol-based sealer (group B), and 16 roots were used as the control group (group C). All roots were prepared to TL. Guttasolv, Resosolv, and Endosolv E were used as the dissolving solutions. Two evaluations of the handpiece were performed: the apical accuracy during the auto reverse function (ARL) and the apex locator function (EL) alone. The ARL function of the handpiece gave acceptable results. There were significant differences between the EL mode measurements and the TL (P < 0.05). In these comparisons, Tri Auto ZX EL mode measurements were significantly shorter than those of the TL.

Clinical reproducibility of three electronic apex locators

AIM

To compare the reproducibility of three electronic apex locators (EALs), Dentaport ZX, RomiApex A-15 and Raypex 5, under clinical conditions.

METHODOLOGY

Forty-eight root canals of incisors, canines and premolars with or without radiographically confirmed periapical lesions required root canal treatment in 42 patients. In each root canal, all three EALs were used to determine the working length (WL) that was defined as the zero reading and indicated by 'Apex', '0.0' or 'red square' markings on the EAL display. A new K-file of the same size was used for each measurement. The file length was fixed with a rubber stop and measured to an accuracy of 0.01 mm. Measurements were undertaken by two calibrated operators. Differences in zero readings between the three EALs in the same root canal were statistically analysed using paired t-tests with the Bonferroni correction, Bland-Altman plot and Linn's concordance correlation coefficients at α = 0.05.

RESULTS

Mean and standard deviation values measured by the three EALs showed no statistically significant differences. Identical readings by all three EALs were found in 10.4% of root canals. Forty-three per cent of readings differed by less than ± 0.5 mm and 31.3% exceeded a difference of ± 1 mm.

CONCLUSIONS

The clinical reproducibility of Dentaport ZX, RomiApex A-15 and Raypex 5 was confirmed with the majority of readings within the ± 1.0 mm range. However, the small number of identical zero readings suggests that EALs are not reliable as the sole means of WL determination under clinical conditions.