A Micro–computed Tomographic Evaluation of the Accuracy of 3 Electronic Apex Locators in Curved Canals of Mandibular Molars

In Vitro Evaluation of the Dynamic Cyclic Fatigue Resistance of a New TruNatomy Glider File after Different Cycles of Use

INTRODUCTION

Determination of the glide path is recommended before using rotary instruments. This study aimed to evaluate the dynamic cyclic fatigue resistance of new and used glider rotary instruments in up to 6 root canals.

METHODS

Seventy-two TruNatomy Glider files were used for the preparation of root canals of extracted lower molars, which were then submitted to the dynamic cyclic fatigue test carried out in a curved metallic artificial canal. The instruments were divided into 4 groups (n = 18): Control group, new instruments without any use in the root canal; Group 2U, instruments used in 2 mesial canals; Group 4U, instruments used in 4 mesial canals; Group 6U, instruments used in 6 mesial canals. The time to failure (TF) of the instrument was recorded, and the number of cycles to failure (NCF) was calculated. The data were submitted to 1-way analysis of variance and to the Games-Howell test for multiple comparisons, adopting a significance level of 5%.

RESULTS

TF and NCF were significantly affected by the number of file uses. The Games-Howell test revealed that TF and NCF were significantly greater in the control group than in Group 4U. In Group 2U, TF and NCF were intermediate and not significantly different from the control group. Group 6U had significantly lower TF and NCF than all other groups.

CONCLUSION

The TruNatomy Glider can be used as a glide path for up to 2 mesial canals of mandibular molars, whereas its use on 4 or 6 root canals is not suggested.

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.

Clinical accuracy and precision of 3 multi-frequency electronic apex locators assessed through micro-CT imaging

INTRODUCTION

This study aimed to compare the in vivo accuracy and precision of 3 electronic apex locators (EALs) in determining the position of the major foramen using micro-computed tomographic (micro-CT) technology.

METHODS

After access preparation of 23 necrotic or vital teeth from 5 patients, canals were negotiated and hand files were used to determine the position of the foramen with 3 EALs: Propex Pixi, Woodpex III and Root ZX II. After fixing the silicon stop to the file, teeth were extracted and scanned in a micro-CT device with and without the instrument inserted into the canal. Datasets were co-registered, and the accuracy and precision of the EALs were determined at a tolerance level of ± 0.5 mm by measuring the distance from the tip of the instruments to a tangential line crossing the margins of the foramen. Statistical comparisons were performed using Friedman with post hoc Related Samples Sign and Spearman tests (α = 5%).

RESULTS

A significant difference was detected comparing the accuracy of Root ZX II (100%), Woodpex III (86.96%) and Propex Pixi (52.17%) (P < .05). There was a lack of significance in the relationship between the pulp status and the accuracy of tested EALs (P > .05). Propex Pixi was significantly less precise than Root ZX II (P < .05), while no difference was found between Woodpex III to either Root ZX II or Propex Pixi (P > .05).

CONCLUSIONS

EALs presented similar precision, but Woodpex III and Root ZX II showed better accuracy to determine the position of the apical foramen than Propex Pixi.

Micro-CT study of the in vivo accuracy of a wireless electronic apex locator

INTRODUCTION

This study aimed to compare the in vivo accuracy of Wirele-X and RootZX II electronic apex locators (EALs) in determining the position of the major foramen using micro-CT as analytical tool.

METHODS

Eleven vital teeth from 5 patients planned for extraction were used. After conventional access cavity preparation, root canals were flared and negotiated up to the apical third with sizes 08 and 10 K-files followed by irrigation with 2.5% NaOCl. K-type files were used to determine the working length of the selected canals using Root ZX II and Wirele-X apex locators until their numeric displays read '0.0'. After fixing the silicon stop to the file, teeth were extracted and imaged in a micro-CT device using a double-scan protocol. Image stacks, with and without the file in the root canal, were then co-registered and the measurement error calculated as the absolute difference between the tip of the file and the major foramen. Positive and negative values were recorded when the file tip was detected beyond or short the major foramen, respectively. Accuracy was determined on stable measurements within ± 0.5 mm when the file tip did not extend beyond the major foramen. The Chi-square test was applied to compare the ability of the EALs to detect the position of the major foramen, while T test for dependent variables was used to verify differences in the two measurements obtained in each tooth. Significance level was set at 5%.

RESULTS

Within a tolerance level of ± 0.5 mm, no significant differences were observed between the tested EALs regarding the absolute distance values (p=0.82) or in their ability to detect the position of the major foramen (Χ²=0.2588; p=0.6109). The accuracy of the Root ZX II and the Wirele-X apex locators within ± 0.5 mm were 81.8% and 90.9%, respectively.

CONCLUSIONS

Root ZX II and Wirele-X performed similarly regarding the in vivo detection of the major foramen. Using strict criteria, the accuracy of the Root ZX II and the Wirele-X apex locators were 81.8% and 90.9%, respectively.

Morphological changes of the root apex in anterior teeth with periapical periodontitis: an in-vivo study

Introduction

The aim was to analyze the morphological changes of root apex in anterior teeth with periapical periodontitis.

Methods

32 untreated anterior teeth with periapical periodontitis were enrolled, compared with the healthy contralateral teeth. Two-dimensional measurement of Cone-beam computed tomography was used to determine the location and measure diameter of the apical constriction according to Schell’s methods. An open-source software (3D Slicer) was used to reconstruct the teeth. The apical constriction form was analysis according to Schell’s topography. The distances of apical constriction to apical foramen and anatomical apex were measured respectively.

Results

The difference value between buccolingual and mesiodistal diameter was (0.06 ± 0.09) mm and (0.04 ± 0.04) mm in periapical periodontitis and controls (p < 0.05). The mean distance between apical constriction and anatomical apex was significantly shorter in periapical periodontitis than controls, so was the mean distance of apical constriction to apical foramen. The most common form of apical constriction was flaring (65.6%) in periapical periodontitis.

Conclusions

The anterior teeth with periapical periodontitis had shorter distances of apical constriction to anatomical apex and apical foramen, bigger disparities between the diameters of buccolingual and mesiodistal, and higher proportion of flaring apical constriction.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02062-z.

Micro-computed tomography analysis of root canal morphology and thickness of crown and root of mandibular incisors in Chinese population

OBJECTIVES

The aim of this study was to investigate the root canal morphology and the thickness of crown and root of mandibular incisors in a Chinese subpopulation by micro-computed tomography (micro-CT).

METHODS

In total, 208 mandibular incisors were scanned using micro-CT. The anatomical features of the canals (canal configuration, apical constriction, foramen-to-apex distance, accessory canal vertical distribution, and canal geometrical parameters) and the thickness of the crown and root 2/3 were evaluated.

RESULTS

Three canal categories, labeled as Single (77.88%), Merged (15.87%), and Separated (6.25%), were summarized. The most frequent constriction type in main foramina was single constriction (42.53%). Wide and narrow diameters in a single main foramen were 0.37 ± 0.14 mm and 0.26 ± 0.07 mm, respectively. The distance from the anatomical foramen to the physiological foramen and the anatomical apex was 0.49 ± 0.20 mm and 0.36 ± 0.28 mm, respectively. During the virtual root-end resection, 97.12% of roots underwent successful resection at the 2-mm level, with the foramina visible on the resection surface. During 2-D cross-sectional analyses, the shape parameters of the root and canal showed significant positive correlation (P < 0.05). The thickest and thinnest walls were the incisal and proximal walls (P < 0.05) of the crown, respectively. The buccal walls were significantly thicker than the lingual walls on the crown (P < 0.05), whereas the lingual walls were thicker on the root 2/3 (P < 0.05).

CONCLUSIONS

This study provides detailed information about the root canal morphology and thickness of the crown and root of mandibular incisors in a Chinese population. An understanding of morphology can benefit endodontic treatment.

CLINICAL RELEVANCE

Adequate knowledge of the crown, root, and canal morphology, as well as the thickness distribution of the crown and root, is essential for successful root canal therapy and prevention of complications.

A laboratory study of the accuracy of three electronic apex locators: influence of embedding media and radiographic assessment of the electronic apical limit

AIM

To evaluate several factors that might interfere with the use of electronic root canal length measurement devices (ERCLMDs) in a laboratory setting, including two different embedding media (alginate and electroconductive gel), three different types of devices and the radiographic view on the assessment of the electronic readings.

METHODOLOGY

Thirty single-rooted extracted human mandibular premolars were selected. After access and canal pre-flaring, a size 10 K-file was inserted in the canal up to the major apical foramen under magnification (×10), and this length was recorded as the actual length (AL) of the canal. Teeth were mounted on a specific endodontic training kit platform (ProTrain). Two different embedding media (electroconductive gel and alginate) and three different ERCLMDs: Apex ID (SybronEndo, Glendora, CA, USA), CanalPro Apex Locator (Coltene-Endo, Cuyahoga Falls, OH, USA) and the Root ZX II (J. Morita, Tokyo, Japan), were tested. Following the measurement at the 0.5 mark of each ERCLMD using alginate, two periapical radiographs (bucco-lingual and proximal views) were taken. The difference between the electronic readings and the AL, as well as the distance from the file tip to the apex of the roots on the radiographs, was calculated. Data were analysed statistically (two-way anova, Tukey's and chi-squared tests) at 5% significance level.

RESULTS

The incidence of over-extended readings was significantly greater (P < 0.05) when using the ProTrain electroconductive gel, except for Root ZX II at the 0.5 mark. Root ZX, CanalPro and Apex ID had similar accuracy when the 0.0/APEX mark was used to locate the foramen. For the radiographic method, no difference was found between the devices or radiographic views.

CONCLUSION

Compared with alginate, the conductive gel of the ProTrain kit negatively affected most of the electronic readings. The three evaluated ERCLMDs had similar accuracy in locating the apical foramen when using the mark 0.0/APEX and alginate as the embedding media. Although the ProTrain platform allows radiographs to be exposed in both bucco-lingual and proximal views, no difference was found between the views when evaluating the apical limit provided by the 0.5 mark in mandibular premolars embedded in alginate.

The influence of periapical lesions on the repeatability of two electronic apex locators in vivo

OBJECTIVES

To determine the influence of periapical lesions on the repeatability of two electronic apex locators (EALs), Root ZX II, and RomiApex A-15, in maxillary anterior teeth, in vivo.

MATERIALS AND METHODS

After approval by the local ethics committee, 43 maxillary anterior teeth scheduled for root canal therapy were assigned to two groups. The periapical lesion (PAL) group included 21 teeth with necrotic pulps and radiographically visible periapical lesion, and the normal periapex (NPA) group consisted of 22 teeth with vital pulps and no periapical lesion. In each canal, Root ZX II and RomiApex A-15 were used to determine working length defined as the "zero" reading on the display. Two consecutive measurements were performed with each EAL on each tooth and a second operator measured the endodontic file with a digital caliper without knowledge of the EAL being used or the tooth diagnosis. The absolute value of the difference between the first and second measurement (measurement pairs) was calculated. Repeatability was evaluated by the Bland-Altman method, and an aligned ranks transformation ANOVA was conducted to compare the EALs.

RESULTS

The median absolute difference between measurement pairs was significantly lower (p < 0.001) and the limits of agreement were narrower in the NPA group. Among the EALs, median absolute differences were significantly smaller for Root ZX (p < 0.001).

CONCLUSIONS

Measurements were more repeatable when no periapical lesion was present. Root ZX showed better repeatability than RomiApex.

CLINICAL RELEVANCE

Periapical lesions seem to influence successive in vivo measurements with EALs.

The accuracy of electronic apex locators for determining working length: An in vitro study with artificial teeth

This study aimed to determine the accuracy of four electronic apex locators (EALs) (I-Root, Propex Pixi, Novapex and Bassi iRoot Apex), using artificial mandibular and maxillary permanent molars. The root length (RL) from 40 artificial teeth was initially determined with Kerr hand files. Then, the electronic RL were obtained for the same root canals with each EAL, and the results were compared with those obtained using hand files. The accuracy of the EALs was determined through analysis of the divergences observed in relation to the lengths obtained with files. All EALs were effective for determining the RL in the artificial teeth, showing results similar to those obtained by hand. The Bassi iRoot Apex had higher accuracy (96.7%) than the Propex Pixi (89.1%) and Novapex (85.8%) (P < 0.05). Based on the results, all EALs tested had a similar performance, and artificial teeth may be used to determine the accuracy of these devices.

Correlation of objective image quality and working length measurements in different CBCT machines: An ex vivo study

To investigate potential correlations between objective CBCT image parameters and accuracy in endodontic working length determination ex vivo. Contrast-to-noise ratio (CNR) and spatial resolution (SR) as fundamental objective image parameters were examined using specific phantoms in seven different CBCT machines. Seven experienced observers were instructed and calibrated. The order of the CBCTs was randomized for each observer and observation. To assess intra-operator reproducibility, the procedure was repeated within six weeks with a randomized order of CBCT images. Multivariate analysis (MANOVA) did not reveal any influence of the combined image quality factors CNR and SR on measurement accuracy. Inter-operator reproducibility as assessed between the two observations was poor, with a mean intra-class correlation (ICC) of 0.48 (95%-CI  0.38, 0.59) for observation No. 1. and 0.40 (95%-CI 0.30, 0.51) for observation No. 2. Intra-operator reproducibility pooled over all observers between both observations was only moderate, with a mean ICC of 0.58 (95%-CI 0.52 to 0.64). Within the limitations of the study, objective image quality measures and exposure parameters seem not to have a significant influence on accuracy in determining endodontic root canal lengths in CBCT scans. The main factor of variance is the observer.

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.

In Vivo Evaluation of 3 Electronic Apex Locators: Root ZX Mini, Apex ID, and Propex Pixi

INTRODUCTION

The aim of this in vivo study was to compare the accuracy of 3 electronic apex locators (EALs) (Root ZX mini [J Morita Corp, Tokyo, Japan], Apex ID [SybronEndo, Glendora, CA], and Propex Pixi [Dentsply Maillefer, Ballaigues, Switzerland]) to determine the working length.

METHODS

Thirty single-rooted human teeth that were scheduled for extraction were selected for the study. Electronic measurements were performed with the 3 EALs. After the teeth had been extracted, a #10 K-file was used to determine the actual working length, which was established at 0.5 mm short of the major foramen. The data were statistically analyzed with analysis of variance (α = 0.05).

RESULTS

No significant differences were found among the experimental groups (P > .05). The mean distance from the actual working length to the file tip was 0.163 ± 0.032 mm when Root ZX mini was used, 0.343 ± 0.032 mm for Propex Pixi , and 0.012 ± 0.008 mm for Apex ID.

CONCLUSIONS

Under the in vivo conditions of this study, no statistically significant differences were observed among the 3 EALs.

Root canal treatment in elderly patients: A review and clinical considerations

Life expectancy has increased as a result of advancements in health care services; thus, maintaining healthy dentition is an important factor in overall health. Furthermore, the growing desire of elderly patients to maintain their teeth has led to an increased need for the performance of complex dental treatment in elderly patients. Root canal therapy is an essential phase of such treatments. Elderly patients may exhibit one or more systemic conditions that require special care, in addition to other changes that occur within the dentition and oral mucosa as a result of aging. These make root canal treatment in elderly patients a great challenge. The aim of this review was to characterize pathologic and physiologic changes in elderly patients that can interfere with root canal treatment procedures, as well as attitudes of elderly patients toward such treatment, guidelines and clinical considerations for management of root canal treatment in elderly patients.