Clinical efficacy of electronic apex locators: systematic review

Comparative Accuracy and Reliability of Three Electronic Apex Locators in Determining the Apical Constriction of Molar Canals: A Micro-CT Evaluation

Background: Determining the correct apical limit for root canal treatment is essential for its success. This study evaluates the accuracy of three electronic apex locators (EALs) in locating the apical constriction (AC) in molar canals. Methods: Forty extracted human mandibular molars were scanned using micro-CT, and endodontic access cavities were created. Teeth were mounted in alginate, and three EALs-Root ZX-mini, Root ZX-II, and Sirona integrated apex locator-were used to measure the canal working length in dry canals and with EDTA gel. Micro-CT scans were performed with files in place, and the distance from the AC was calculated. Measurements within 0.1-0.5 mm were categorized as 'close'. Those extending beyond towards the major foramen were categorized as 'beyond', otherwise they were classified as 'far'. Data analysis was conducted with a level of significance set at 5%. Results: Most readings for all EALs were in the 'close' category, with significant differences between devices (p < 0.0001). Root ZX-mini and Root ZX-II had 74.4% and 72.5% 'close' readings, respectively, versus 51% for Sirona integrated. Accuracy did not differ significantly between dry and EDTA-treated canals (p = 0.306). All EALs demonstrated excellent operator reliability (ICC 0.996-1.00). Conclusions: All EALs accurately determined AC, unaffected by lubricants. However, Root ZX-mini and Root ZX-II outperformed Sirona integrated. All EALs showed consistent reliability.

Clinicians' perspectives, inducements, preferences, and clinical experiences regarding the use of electronic apex locator and apex locator integrated engine-driven instrumentation: a cross-sectional study

BACKGROUND

This study aimed to investigate the perspectives, preferences, and clinical experiences regarding using electronic apex locator and apex locator integrated instrumentation of dentists and endodontists.

METHODS

A web-based questionnaire consisting of 3 parts and 23 closed-ended questions to achieve the objective of the study was carried out in ethical conditions between August and October 2023. The first part of survey included demographic information, while the second part was about evaluating electronic apex locator usage. In the last part, only participants' use of apex locator-integrated instrumentation was evaluated. Data were analyzed at a significance level of p < 0.05.

RESULTS

A total of 297 clinicians, including 59 endodontists and 34 endodontic residents/Ph.D. students participated in the questionnaire. Endodontists and endodontic residents/Ph.D. students perform statistically significantly more root canal treatments per week on average (p = 0.001). For the working length determination method (multiple option question), 78.5% of participants use an electronic apex locator and 39.7% apex locator-integrated engines. However, the preference rate for electronic apex determination technique was generally 95.6%, with the full rate confirmation of endodontists and endodontic residents/Ph.D. students (100%). A total of 21 endodontists out of 59 prefer apex locator integrated engine-driven instrumentation. Although many of these specialized clinicians use this technique, they stated that they measure electronic working length passively for confirmation of the working length before (90.5%) and after the preparation (66.7%).

CONCLUSIONS

Dentists, as well as endodontists, are skeptical about apex locator-integrated engine-driven instrumentation. Using this technique as a supporter rather than a primary way for preparation within safe limits may give safer results in terms of treatment outcomes.

Impact of passive ultrasonic irrigation on the outcome of non-surgical root canal treatment: a systematic review and meta-analysis of randomized clinical trials

OBJECTIVE

This systematic review aimed to assess the impact of Passive Ultrasonic Irrigation on the periapical healing rate of primary root canal treatment compared to conventional syringe irrigation.

METHODS

Registered a priori in the PROSPERO database, this review was conducted by two independent reviewers who performed an electronic search up to December 2023. The search included databases such as MEDLINE (PubMed), Scopus, Web of Science, Embase, LILACS, and the Cochrane Library, as well as grey literature. We included randomized clinical trials (RCTs) that focused on patients undergoing primary root canal treatments. The study compared intervention groups using PUI with control groups that did not use activation techniques. Periapical healing was assessed over follow-up periods of at least six months, utilizing either periapical radiographs or cone-beam computed tomography. To synthesize the findings, a meta-analysis and trial sequence analysis were conducted, employing the Relative Risk as the measure of effect, with a 95% confidence interval. The GRADE approach was utilized to assess the certainty of the evidence.

RESULTS

The meta-analysis incorporated three RCTs, involving 474 patients (501 teeth). The analysis revealed that PUI led to a higher rate of periapical healing compared to CSI (Relative Risk: 1.10; 95% Confidence Interval: 1.01-1.21, I² = 0%), with moderate certainty of evidence.

CONCLUSIONS

Despite the limited number of high-quality RCTs, the findings showed a positive impact of PUI on periapical healing rates in primary root canal treatments, in comparison to CSI.

REGISTER

CRD42021290894.

Efficacy of electronic apex locators in comparison with intraoral radiographs in working length determination- a systematic review and meta-analysis

BACKGROUND

Successful endodontic treatment needs accurate determination of working length (WL). Electronic apex locators (EALs) were presented as an alternative to radiographic methods; and since then, they have evolved and gained popularity in the determination of WL. However, there is insufficient evidence on the post-operative pain, adequacy, and accuracy of EALs in determining WL.

OBJECTIVE

The systematic review and meta-analysis aims to gather evidence regarding the effectiveness of EALs for WL determination when compared to different imaging techniques along with postoperative pain associated with WL determination, the number of radiographs taken during the procedure, the time taken, and the adverse effects.

METHODS

For the review, clinical studies with cross-over and parallel-arm randomized controlled trials (RCTs) were searched in seven electronic databases, followed by cross-referencing of the selected studies and related research synthesis. Risk of bias (RoB) assessment was carried out with Cochrane's RoB tool and a random-effects model was used. The meta-analysis was performed with the RevMan software 5.4.1.

RESULTS

Eleven eligible RCTs were incorporated into the review and eight RCTs into the meta-analysis, of which five had high RoB and the remaining six had unclear RoB. Following meta-analysis, no significant difference in postoperative pain was found among the EAL and radiograph groups (SMD 0.00, CI .29 to .28, 354 participants; P value = 0.98). Radiograph group showed better WL accuracy (SMD 0.55, CI .11 to .99, 254 participants; P value = 0.02), while the EAL group had 10% better WL adequacy (RR 1.10, CI 1.03-1.18, 573 participants; P value = 0.006).

CONCLUSION

We found very low-certainty evidence to support the efficacy of different types of EAL compared to radiography for the outcomes tested. We were unable to reach any conclusions about the superiority of any type of EAL. Well-planned RCTs need to be conducted by standardizing the outcomes and outcome measurement methods.

Evaluation of changes in root canal length and accuracy of the electronic apex locator during different stages of endodontic treatment and retreatment

This study evaluated changes in the root canal length (RCL) and the accuracy of the electronic apex locator (EAL) during the different stages of endodontic treatment and retreatment. Fifty-six mesial root canals of mandibular molars were selected. The actual root canal length (AL) of the canals was obtained by inserting a size 15 hand file up to the apical foramen, under magnification. The electronic lengths were obtained at the "APEX" mark of Root ZX II, using an alginate model. Both measurements were performed at three different stages of the initial root canal treatment-unflared, flared, and concluded-and at two stages of retreatment, after achieving patency and repreparation. Data were statistically analyzed and the significance level established was 5%. All stages produced a significant reduction in the AL (p < 0.05). The greatest variation was observed between the unflared-flared stages (0.2 mm) and between concluded-patency stages (0.09 mm), with no difference between them (p > 0.05). The accuracy of Root ZX II was negatively affected after achieving patency, presenting statistically significant difference compared to the other stages (p < 0.05). A significant reduction in the RCL was observed along the different stages of endodontic treatment and retreatment. The EAL was accurate to measure the root canals in most stages, except after achieving patency for endodontic retreatment. Determining and monitoring the RCL is an essential step towards a favorable prognosis, since it reduced along the different stages evaluated. Root ZX II was not accurate for endodontic retreatment.

Can ultrasonography be used to determine working length in endodontic treatment? An in vitro study

This study was conducted to evaluate efficacy of ultrasonography (USG) in determining working length in in-vitro conditions. Twenty five access cavities of maxillary incisor teeth were opened and actual working lengths (AWL) were measured with dental operating microscope. The working length were then measured with an electronic apex locator and USG. USG and apex locator measurements were statistically analyzed using one sample t-test and compared with AWL. The mean AWL measurment was 20.68 mm. USG measured the working length slightly longer (21.09 mm) than the measurements of apex locator (20.64 mm). Statistical analysis showed that the USG method provided similar measurements to electronic apex locators and with no statistical difference with actual working length (P < .05). USG emerges as a promising method for working length measurement that allows simultaneous visualization of root tip anatomy in cases where electronic apex locators may be insufficient and there is buccal cortical bone loss.

Influence of Embedding Medium on iPex Electronic Apex Locator Accuracy: An Ex Vivo Comparative Study Using Alginate, Saline, and Gelatin Models

AIM

Accurate working length determination during root canal treatment is essential for achieving successful outcomes. This study aimed to evaluate the impact of embedding medium on the accuracy of iPex electronic apex locator (EAL).

MATERIALS AND METHODS

Sixty-one extracted single-rooted teeth were decoronated and coronally flared with Gates-Glidden burs. Actual canal length (ACL) was obtained by introducing a size 8 K-file until its tip reached the most coronal border of the apical foramen. This step was performed thrice and then averaged. Deducting 0.5 mm from the ACL provided the working length (WL). The teeth were randomly placed in plastic containers filled with freshly mixed alginate, gelatin, or saline, with the lip clip placed in the medium. The blinded operator obtained electronic measurements using iPex by advancing a K-file with a size compatible with the canal attached to the file clip and advanced until the 0.0 mark, then withdrawn to the 0.5 mark. This step was performed thrice and then averaged. Data were analyzed using ANOVA and Tukey's post hoc test, with significance level set at 5% (α = 0.05).

RESULTS

The mean difference between WL and iPex length obtained in the gelatin model was significantly longer than the difference with mean iPex length in alginate (p = 0.005) and in saline (p < 0.001). There was no significant difference between iPex readings obtained in alginate and saline (p = 0.249).

CONCLUSION

The use of freshly mixed alginate or saline for ex vivo assessment of iPex is recommended, whereas the use of gelatin could increase the chances of readings longer than looked for.

CLINICAL SIGNIFICANCE

Identifying the optimum embedding medium for ex vivo testing of EALs permits the comparison and assessment of several factors affecting EALs' precision under standardized conditions. This helps in understanding EAL performance in vivo and in optimizing its clinical utilization.

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.

An in vitro evaluation of the WIRELE-x electronic apex locator

This study evaluated the accuracy of the Wirele-X (Forum Tec, Ashkelon, Israel), a novel Bluetooth-enabled wireless electronic apex locator. Thirty-one extracted teeth with mature apices were used. Under 10X magnification, the actual canal lengths were determined. The teeth were embedded in alginate and electronic canal lengths were obtained using the Root ZX II and Wirele-X electronic apex locators. The actual canal lengths and electronic canal lengths were compared with Student's t-test. The average distance from the file tip to the actual canal length was -0.11 mm (±0.16) for the Root ZX II, and - 0.07 mm (±0.21) for the Wirele-X. There were no statistically significant differences between the two electronic apex locators in their ability to determine the actual canal length (p > 0.05). The wireless apex locator (Wirele-X) and the wired apex locator (Root ZX II) were found to be equally accurate.

Accuracy of the KontrolFlex AccuFile when used with the Root ZX electronic apex locator in vitro

The aims of this study were to determine the efficacy of the KontrolFlex™ Accufile™ compared to the READY•STEEL™ Flexofile® using an electronic apex locator and to evaluate the instrument's design via scanning electron microscopy. Actual canal lengths of 30 extracted teeth were determined under magnification. An alginate model was used to determine experimental canal lengths with the Root ZX II apex locator (EAL) and size #10 Accufiles and Flexofiles. Differences between actual lengths and experimental lengths were compared with Student's t test. The average experimental lengths were short of the actual length by -0.10 mm (±0.34) and -0.12 mm (±0.16) for the Accufile and Flexofile, respectively with no statistical difference (p > 0.05). SEM images revealed similar non-cutting Batt tips and a square cross-section for the Accufile and triangular for the Flexofile. Both files provided similarly high levels of reliability when used with the Root ZX II EAL.

Single versus multiple visits for endodontic treatment of permanent teeth

BACKGROUND

Root canal treatment (RoCT), or endodontic treatment, is a common procedure in dentistry. The main indications for RoCT are irreversible pulpitis and necrosis of the dental pulp caused by carious processes, coronal crack or fracture, or dental trauma. Successful RoCT is characterised by an absence of symptoms (i.e. pain) and clinical signs (i.e. swelling and sinus tract) in teeth without radiographic evidence of periodontal involvement (i.e. normal periodontal ligament). The success of RoCT depends on a number of variables related to the preoperative condition of the tooth, as well as the endodontic procedures. RoCT can be carried out with a single-visit approach, which involves root canal system obturation (filling and sealing) directly after instrumentation and irrigation, or with a multiple-visits approach, in which the treatment is completed in two or more sessions and obturation is performed in the last session. This review updates the previous versions published in 2007 and 2016.

OBJECTIVES

To evaluate the benefits and harms of completion of root canal treatment (RoCT) in a single visit compared to RoCT over two or more visits, with or without medication, in people aged over 10 years.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 25 April 2022.

SELECTION CRITERIA

We included randomised controlled trials and quasi-randomised controlled trials in people needing RoCT comparing completion of RoCT in a single visit compared to RoCT over two or more visits.  DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were 1. tooth extraction and 2. radiological failure after at least one year (i.e. periapical radiolucency). Our secondary outcomes were 3. postoperative and postobturation pain; 4. swelling or flare-up; 5. analgesic use and 6. presence of sinus track or fistula after at least one month. We used GRADE to assess certainty of evidence for each outcome. We excluded five studies that were included in the previous version of the review because they did not meet the current standard of care (i.e. rubber dam isolation and irrigation with sodium hypochlorite).

MAIN RESULTS

We included 47 studies with 5805 participants and 5693 teeth analysed. We judged 10 studies at low risk of bias, 17 at high risk of bias and 20 at unclear risk of bias. Only two studies reported data on tooth extraction. We found no evidence of a difference between treatment in one visit or treatment over multiple visits, but we had very low certainty about the findings (risk ratio (RR) 0.46, 95% confidence interval (CI) 0.09 to 2.50; I2 = 0%; 2 studies, 402 teeth). We found no evidence of a difference between single-visit and multiple-visit treatment in terms of radiological failure (RR 0.93, 95% CI 0.81 to 1.07; I2 = 0%; 13 studies, 1505 teeth; moderate-certainty evidence). We found evidence of a higher proportion of participants reporting pain within one week in single-visit groups compared to multiple visit groups (RR 1.55, 95% CI 1.14 to 2.09; I2 = 18%; 5 studies, 638 teeth; moderate-certainty evidence).  We found no evidence of a difference in the proportion of participants reporting pain until 72 hours postobturation (RR 0.97, 95% CI 0.81 to 1.16; I2 = 70%; 12 studies, 1329 teeth; low-certainty evidence), pain intensity until 72 hours postobturation (mean difference (MD) 0.26, 95% CI -4.76 to 5.29; I2 = 98%; 12 studies, 1258 teeth; low-certainty evidence) or pain at one week postobturation (RR 1.05, 95% CI 0.67 to 1.67; I2 = 61%; 9 studies, 1139 teeth; very low-certainty evidence). We found no evidence of a difference in swelling or flare-up incidence (RR 0.56 95% CI 0.16 to 1.92; I2 = 0%; 6 studies; 605 teeth; very low-certainty evidence), analgesic use (RR 1.25 95% CI 0.75 to 2.09; I2 = 36%; 6 studies, 540 teeth; very low-certainty evidence) or sinus tract or fistula presence (RR 1.00, 95% CI 0.24 to 4.28; I2 = 0%; 5 studies, 650 teeth; very low-certainty evidence). Subgroup analysis found no differences between single-visit and multiple-visit RoCT for considered outcomes other than proportion of participants reporting post-treatment pain within one week, which was higher in the single-visit groups for vital teeth (RR 2.16, 95% CI 1.39 to 3.36; I2 = 0%; 2 studies, 316 teeth), and when instrumentation was mechanical (RR 1.80, 95% CI 1.10 to 2.92; I2 = 56%; 2 studies, 278 teeth).

AUTHORS' CONCLUSIONS

As in the previous two versions of the review, there is currently no evidence to suggest that one treatment regimen (single-visit or multiple-visit RoCT) is more effective than the other. Neither regimen can prevent pain and other complications in the 12-month postoperative period. There was moderate-certainty evidence of higher proportion of participants reporting pain within one week in single-visit groups compared to multiple-visit groups. In contrast to the results of the last version of the review, there was no difference in analgesic use.

How is working length determination taught? A survey to assess what is recommended in undergraduate Schools of Dentistry in Brazil

INTRODUCTION

To analyse what are the methods for working length (WLD) determination taught for undergraduate students in Brazilian Dental Schools and the perception of professors about the use of electronic WL determination in the clinical practice.

METHODS

An online questionnaire with eighteen closed questions was sent to 209 Schools of Dentistry in Brazil using the Google Forms Platform. The questionnaire was structured to analyse the perception of professors in the department of endodontics about the method of working length determination taught in undergraduate courses in Dentistry. The data collected in the questionnaires were transferred to an Excel^® spreadsheet and analysed using absolute and relative frequencies. The non-parametric Mann-Whitney test was used to compare groups.

RESULTS

Of the 209 schools contacted, 41 (19.61%) returned answers to the questionnaire. According to professors, electronic working length (WL) determination had a shorter length of time to perform it (p < .001), WL measurement accuracy (p < .001) and ease of performance (p < .001). Professors felt safer when maintaining patency when using electronic WL determination (p = .0020).

CONCLUSIONS

Both radiographic and electronic methods of WL determination are taught in Brazilian Schools of Dentistry. The electronic method was used more frequently, especially in undergraduate clinical courses.

Are electronic apex locators accurate in determining working length in primary teeth pulpectomies? A systematic review and meta-analysis of clinical studies

BACKGROUND

The lack of a well-defined apical constriction in primary teeth raises concerns regarding the accuracy of electronic apex locators (EALs) for measuring working length.

OBJECTIVES

To evaluate the accuracy of EALs in determining working length in primary teeth pulpectomies.

METHODS

Two reviewers searched ten databases up to September 2021. Clinical studies evaluating the accuracy of the electronic measurement of working length in primary teeth pulpectomies were included. Studies without a comparison group, with samples smaller than ten root canals, and that did not use a multiple frequency EAL were excluded. A meta-analysis was conducted to assess the paired differences in mean lengths between measurements obtained by electronic and comparative methods. In addition, a meta-analysis of proportion was applied according to the level of difference between the measures. The risk of bias and applicability of the studies were assessed using the QUADAS-2 tool. The certainty of evidence was assessed with the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.

RESULTS

Twenty-nine studies were included in the qualitative analysis and twenty-three in the quantitative analysis. The methods of comparison for the electronic measurement were the radiographic method, radiovisiographic, scanning electron microscopy, and direct visualization. The meta-analysis showed that the electronic measurement tends to be shorter than radiographic measurement, while the other methods showed no difference. The proportion analysis showed a higher pooled proportion of difference values between electronic and comparative measurements within -0.5 to +0.5 mm (69.31%). The certainty of the evidence suggested very low confidence in estimating the outcome.

DISCUSSION

The results of this review denote a good performance of the EALs in determining working length in primary teeth pulpectomies. However, these results are based on clinical studies with low methodological quality and high heterogeneity, which require careful interpretation for clinical practice.

CONCLUSIONS

Although the results suggest acceptable accuracy of EALs in determining working length in primary teeth pulpectomies, the low quality of the included studies and the very low certainty of the evidence require clinicians to interpret these results with caution. More robust evidence is required to support that these devices are accurate for primary teeth.

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.

Root canal length estimated by cone-beam computed tomography at different slice thicknesses, dedicated endodontic software, or measured by an electronic apex locator

The aim of the present study was to evaluate the agreements between the root canal length estimations using cone-beam computed tomography (CBCT) at different slice thicknesses, dedicated software, or an electronic apex locator (EAL) and the actual lengths (AL). In total, 111 extracted human molars with 302 root canals were chosen. Teeth were scanned using a CBCT device at a voxel size of 0.075 mm. Root canal lengths were estimated using CBCT software at different slice thicknesses (0.6, 1.2, and 2.4 mm) and dedicated software for proposed or operator lengths. The endodontic access cavities were created, and root canal lengths were estimated with an EAL for electronic length (EL) and a ruler for AL. Data were tested using paired t-tests and Bland-Altman plots to detect the differences between the methods in length estimation at a significance of 0.05. The accuracy in the range of ± 0.5 mm was 100% for the EAL. There was an agreement between the EL and CBCT at a slice thickness of 1.2 mm (p = 0.349). CBCT at the smallest slice thickness estimation was not the best modality in agreement with the AL. The EAL was an accurate and reliable method for root canal length measurement.

Accidental Extrusion of Sodium Hypochlorite in a Patient Taking Alendronate: A Case Report With an 8-Year Follow-up

Extrusion of sodium hypochlorite (NaOCl) is a very rare accident with the most common complications including pain, swelling, and hematoma. It can occur even if procedural guidelines, predisposing conditions, and risk factors are taken into consideration. A 59-year-old female patient was admitted to the endodontics department to treat a left maxillary first premolar (World Dental Federation tooth 24). The medical history included osteoporosis and systemic medication with alendronate. Initially, the diagnosis was "symptomatic irreversible pulpitis" with "normal apical tissues." During instrumentation of the buccal canal, accidental extrusion of 2.5% NaOCl occurred into the periapical tissues, resulting from misinterpretation of the working length, and caused severe pain and bleeding. The canal was immediately flushed using copious irrigation with saline solution. An analgesic and corticosteroid were prescribed. At 3 and 7 days, ecchymosis and slight hematoma were observed extraorally in the area of the affected tooth and an intraoral ulceration at the apex of the affected tooth. At 15 days, minimal signs of ecchymosis were observed, and the treatment was resumed. At 30 days after the accident, there was complete remission of the sequelae. The clinical, radiographic, and tomographic assessment after 1 month, 1 year, and 8 years showed favorable case evolution. During the 8-year follow-up, the patient maintained the systemic use of alendronate. It can be concluded that NaOCl extrusion is an accident that causes patients and clinicians to experience an unpleasant consequence. The radiographic working length should always be determined carefully. A successful outcome can be achieved in patients who take alendronate.

Influence of Coronal Preflaring on the Accuracy of Electronic Working Length Determination: Systematic Review and Meta-Analysis

AIM

To conduct a systematic review and meta-analysis according to the following PICO question: in extracted human permanent teeth, does preflaring, compared with unflared canals, influence the accuracy of WL determination with EAL?

MATERIAL AND METHODS

A systematic review was conducted according to the PRISMA checklist, using the following databases: PubMed, Science Direct, Scopus, and Web of Science. Studies related to WL determination using EAL both in preflared and unflared root canals of extracted human teeth were included. The outcome of interest was the accuracy of the electronic WL determination. A quality assessment of the included studies was performed, determining the risk of bias. The meta-analyses were calculated with the 5.4 RevMan software using the inverse variance method with random effects. PROSPERO registration: CRD42021243412.

RESULTS

Ten experimental studies fulfilled the inclusion criteria, and most of them found that preflaring increases the accuracy of the EALs in WL determination. The calculated OR was 1.98 (95% CI = 1.65-2.37; p < 0.00001; I2 = 10%), indicating that the determination of WL by EALs is almost twice as accurate in preflared canals. The accuracy of Root ZX in WL determination increases more than three times (OR = 3.25; p < 0.00001). Preflaring with Protaper files significantly increases the accuracy of EALs (OR = 1.76; p < 0.00001). The total risk of bias of the included studies was low. No obvious publication bias was observed.

CONCLUSIONS

The results indicate a significant increase in the accuracy of WL determination with EAL after preflaring, doubling the percentage of exact measurements. Preflaring should be recommended as an important step during mechanical enlargement of the root canal, not only because it improves the access of the files to the canal, but also because it allows one to obtain more accurate electronic determinations of WL.

Endodontic length measurements using 3D Endo, cone-beam computed tomography, and electronic apex locator

BACKGROUND

The objective of this study is to investigate the accuracy of the 3D Endo software, cone-beam computed tomography (CBCT) software, and the electronic apex locator (EAL) in endodontic length determination.

METHODS

302 root canals in 111 human extracted molars were chosen. Access cavity was performed, and root canal lengths were measured with a digital caliper for actual length (AL) and EAL for electronic length. Teeth were then scanned using CBCT device at voxel size of 0.10 mm. It measured root canal lengths using the CBCT (Romexis Viewer), 3D Endo for proposed length (3D-PL) and correct length (3D-CL). Mean differences between the four methods with the AL were calculated and compared. Fisher's exact test, paired t-test, Bland-Altman plot were used to test the differences among the experimental modalities in working length determination at the significance of 0.05.

RESULTS

The accuracy in the range of ± 0.5 mm of the EAL ProPex II was highest among the experimental modalities, however this method disagreed with the actual length.

CONCLUSIONS

The correct working length after adjustment from the semi-automatically length by the 3D Endo software and Romexis Viewer measurements agreed with the AL.

Endodontic length measurements using cone beam computed tomography with dedicated or conventional software at different voxel sizes

The aim of this study is to investigate the accuracies and the agreements of the 3D Endo software, conventional CBCT software Romexis Viewer at three voxel sizes, and the EAL ProPex Pixi in endodontic length measurements. Three hundred and twenty-nine root canals in 120 intact human extracted molars were accessed. The actual lengths (AL) and electronic lengths (EL) were measured using the ruler and electronic apex locator (EAL), respectively. Teeth were scanned using the CBCT at different voxel sizes (0.075, 0.10, and 0.15 mm). Root canal lengths were measured using 3D Endo with proposed length (3D-PL) by software, corrected length (3D-CL), Romexis Viewer. The Fisher's exact test, paired t-test and Bland-Altman plots were calculated to detect the agreements of the four methods with AL measurements. The ProPex Pixi measurements obtained the highest accuracy in the range of ± 0.5 mm. There was agreement between the 3D-PL and the 3D-CL with AL measurements at voxel size of 0.15 mm and at voxel size of 0.10 mm, respectively. The CBCT Romexis Viewer measurements agreed with AL at three voxel sizes. The conventional CBCT measurements using Romexis Viewer and dedicated software did not reach to the 100% accuracy in the range of ± 0.5 mm.

The fate of overfilling in root canal treatments with long-term follow-up: a case series

This study describes 6 cases of endodontic overfilling with successful clinical outcomes during long-term (up to 35 years) radiographic follow-up. Successful endodontic treatment depends on proper shaping, disinfection, and obturation of root canals. Filling materials should completely fill the root canal space without exceeding the anatomical apex. Overfilling may occur when the filling material extrudes into the periapical tissues beyond the apex. The present case series describes 6 root canal treatments in which overfilling of root canal sealer and gutta-percha accidentally occurred. Patients’ teeth were periodically checked with periapical radiographs in order to evaluate the outcomes during long-term follow-up. All cases showed healing and progressive resorption of the extruded materials in the periapex. The present cases showed that if a 3-dimensional seal was present at the apical level, overfilling did not negatively affect the long-term outcomes of root canal treatment.

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 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.

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.

Endodontic Length Measurements Using Different Modalities: An In Vitro Study

INTRODUCTION

The aim of this study was to investigate and compare the accuracy of the 3D Endo software, conventional CBCT software Romexis Viewer, and the EAL E-Pex Pro in WL determination.

MATERIALS AND METHODS

Three hundred and two root canals in 110 intact human extracted molars were accessed. The actual lengths (ALs) were measured. Root canal lengths were measured using 3D Endo with proposed length (3D-PL) by software, correct length (3D-CL), Romexis Viewer, and the E-Pex Pro. The percentages of the measurements in the range of ±0.5 mm to the AL were compared using the Fisher's exact test. The paired t test and Bland-Altman plots were calculated to detect the agreement of the four methods with the AL measurements. The statistical significance was set at P<0.05.

RESULTS

The accuracies in the range of ±0.5 mm to the AL were 83.8%, 86.7%, 48.3%, and 99.7% for 3D-PL, 3D-CL, Romexis Viewer, and E-PexPro, respectively. There were agreements between 3D-PL and Romexis Viewer with the AL measurements.

CONCLUSION

The CBCT measurements using 3D Endo with the proposed length by the software and Romexis Viewer with the voxel size of 0.15 mm agreed with the AL measurements of the root canals.

Multifrequency Impedance Method Based on Neural Network for Root Canal Length Measurement

Root canal therapy is the most fundamental and effective approach for treating endodontics and periapicalitis. The length of the root canal must be accurately measured to clean the pathogenic substances in it. This study aims to present a multifrequency impedance method based on a neural network for root canal length measurement. A circuit system was designed which generates a current of frequencies from 100 Hz to 20 kHz in order to augment the data of impedance ratios with different combinations of frequencies. Several impedance ratios and other quantified characteristics, such as the type of tooth and file, were selected as features to train a neural network model that could predict the distance between the file and apical foramen. The model uses leave-one-out cross-validation, adopts the Adam optimizer and regularization, and has two hidden layers with nine and five nodes, respectively. The neural network-based multifrequency impedance method exhibits nearly 95% accuracy, compared with the dual-frequency impedance ratio method (which demonstrated no more than 85% accuracy in some situations). This method may eliminate the influence of human and environmental factors on measurement of the root canal length, thereby increasing measurement robustness.

Glide Path with Reciprocating Driven Pathfinding Instrument: Performance and Fracture Rate

INTRODUCTION

This study assessed the number of mesial and distal canals of mandibular molars in which the R-Pilot pathfinding reciprocating instrument reached the working length (WL) during macro glide path procedure. Fracture and deformation rates were also evaluated.

METHODS

One hundred fifty-six root canals of 52 teeth were scouted to the length of the apical foramen. Then the R-Pilot instrument was positioned at the canal orifice and activated. The instrument was moved by using a pecking motion and light apical pressure. This procedure was repeated in an attempt to reach the WL. The type of fracture and/or instrument deformation was assessed by scanning electron microscopy, whereas the roots with fractured instruments were scanned through micro-computed tomography. The percentage frequency distribution of fractures, deformations, and root canals in which the R-Pilot reached the WL were recorded and statistically compared by using the Pearson's χ² test with α = 5%.

RESULTS

R-Pilot instruments reached the WL in 139 root canals (89.10%), and χ² test showed a significant difference between the observed frequencies and the expected frequencies (χ² = 95.41, P = .000). The observed frequencies of fractures (2.56%) and deformations (1.92%) were also significantly lower than the expected (fracture: χ² = 140.41, P = .000; deformation: χ² = 144.23, P = .000). Fractures occurred mostly at the apical and curved parts of the root canals.

CONCLUSIONS

R-Pilot reached the WL in 89.10% of the root canals of mandibular molars with fracture and deformation rates of 2.56% and 1.92%, respectively.

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 three different apex locators in determining the working length of mandibular first molar teeth with irreversible pulpitis compared with an intraoral periapical radiograph: A block randomized, controlled, clinical trial

AIM

The aim of the present study was to assess the clinical accuracy APEX and 0.5 marks of three different apex locators - iPex II, Root ZX, and Apex ID - before and after canal preparation in the mandibular first molar.

METHODS

Sixty patients between the ages of 13-60 years participated in the study. After access gaining and canal preparation stages files were inserted with the apex locator clip attached until the electronic apex locators (EALs) shows readings of APEX and 0.5 marks and same is confirmed with periapical radiographs. Eighteen apex locator readings were recorded from each tooth, and 1080 readings were obtained from the 60 patients.

RESULTS

Differences among readings from apex locators and radiographic readings were assessed using paired t test. Only in two patients (1 male and 1 female) were the APEX mark readings different from the radiograph estimation. When the 0.5 mark readings of three different EALs were compared with each other, we could observe that the readings from Root ZX differed significantly (P < 0.05).

CONCLUSIONS

In the present study, we observed the negligible differences in readings between the EAL at the APEX mark readings, coinciding with the radiographic observation. Clinically, we recommend the apical foramen be located with the apex locators' APEX mark readings prior to identifying the apical constriction position.

Influence of the Maxillary Sinus on the Accuracy of the Root ZX Apex Locator: An Ex Vivo Study

This study evaluated the accuracy of the Root ZX (J. Morita, Tokyo, Japan) electronic apex locator in determining the working length when palatal maxillary molar roots are in a relationship with the sinus. Seventeen human maxillary molars with vital pulp were scheduled for an extraction and implant placement as part of a periodontal treatment plan. The access cavity was prepared, and a #10 K file (Dentsply Maillefer, Ballaigues, Switzerland) was inserted into the palatal root using the Root ZX apex locator in order to determine the electronic working length (EWL); then, the teeth were extracted. To determine the real working length (RWL), a #10 K file was introduced into the root canal until its tip touched a glass plate. EWL and RWL were compared. Images reconstructed with CBCT (cone beam computerized tomography) revealed that eight palatal roots were related to the maxillary sinus, whereas nine were not. The results showed a significant difference between the EWL and the RWL of the palatal roots related to the sinus (p < 0.001). No significant difference was observed in measurements of roots not in contact with the sinus (p > 0.05). Within the study limitations, the reliability of Root ZX was influenced by the relationship of the roots with the maxillary sinus.

Quality of Root Canal Fillings Performed by Undergraduate Students and the Related Factors on the Treatment Outcome: A 2- to 5-Year Follow-Up

Objective

To evaluate radiographically the quality of root canal fillings performed by undergraduate students between 2012 and 2015, and to investigate the impact of their quality in correlation with root type, preoperative periapical status, and type of restorative treatment on the treatment outcome.

Methods

Six hundred seventy-seven non-surgical root canal treatments were performed by undergraduate students from the Aristotle University of Thessaloniki at the endodontic department clinics between 2012 and 2015. Two hundred forty-four teeth (349 roots) fulfilled the criteria and were clinically and radiographically re-examined between 2016 and 2017, and the outcome was classified as "success" or "failure." Root canal fillings were radiographically evaluated in terms of apical extension and density. The root filling was classified as acceptable when both parameters were rated as acceptable. Statistical analysis was performed using generalized estimating equations. Pairwise comparisons were performed by the sequential Bonferroni method. Intra-examiner and inter-examiner agreements were checked by the intraclass correlation coefficient and Cohen's kappa. The statistical significance level was set at P<0.05.

Results

The percentage of the roots with acceptable root canal fillings was 40.4%. The molar roots demonstrated the lowest rate (30.7%) compared with the anterior (53%, P<0.05) and premolar teeth (43%, P>0.05). The results of the correlation of the quality of the root canal fillings with the root type, preoperative periapical status, type of coronal restoration, and the treatment outcome showed that the unacceptable quality of root canal filling in relation to root or presence of periapical lesion or crown revealed the lowest success rates (47.2%, 40.3%, and 52.3%, respectively). In contrast, results showed that roots with canal fillings of acceptable quality demonstrated success rates close to 90%, regardless of the other variables.

Conclusion

Within the limitations of the present study, the percentage of radiographically acceptable root canal fillings performed in the undergraduate clinic of the Department of Endodontology at Aristotle University of Thessaloniki was low (40.4%). Results showed that there was a strong association of higher success rates with root fillings of acceptable quality.

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.

Factors Affecting the Outcome of Non-Surgical Endodontic Treatments Performed by Undergraduate Students in a Greek Dental School

Objective:

To evaluate the outcome of initial endodontic treatments performed by undergraduate students in a Greek dental school and to determine the factors that may impact the treatment outcome.

Methods:

From a randomly selected sample of 677 non-surgical endodontic treatments performed between 2012 and 2015, follow-up appointments were scheduled with patients whose dental records matched the inclusion criteria. After clinical and radiographic examination, the treatment outcome was classified as ‘success’ (healed/healing) or ‘failure’ (uncertain/unsatisfactory healing). The statistical analysis of the data was performed using generalized estimating equations. Intra-examiner and inter-examiner agreements were checked with the intraclass correlation coefficient and with Cohen’s kappa. The statistical significance level was set at P<0.05.

Results:

A total of 244 teeth (349 roots) were included for further analysis, and the mean follow-up period was 2.8 years. Overall, the success rate for the treated roots was 72.8%. Μultivariate analysis revealed four decisive factors as having a positive impact on the outcome, namely, the absence of voids within the root fillings (P<0.001), the absence of pre-operative periapical lesions (P=0.001), the extension of the root filling material by 0-2 mm from the radiographic apex (P<0.001) and the root type (anterior roots: P=0.015 and premolar roots: P=0.011). The association of gender, arch, pulp status and type of coronal restoration with the outcome was not statistically significant (P>0.05). Moreover, when the outcome according to pre-operative periapical status and the technical variables of root fillings (apical extension and density) was investigated, roots without periapical lesion, with a root filling material extended 0-2 mm within the apex and without voids revealed the highest success rate (94.5%).

Conclusion:

The success rate of non-surgical endodontic treatments performed in a Greek dental school was in the range of those reported in other studies. The pre-operative periapical status, technical variables of root fillings (apical extension and density) and root type were regarded as significant prognostic factors of the outcome.

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.

The Accuracy of a New Cone-beam Computed Tomographic Software in the Preoperative Working Length Determination Ex Vivo

INTRODUCTION

This study investigates the accuracy of 3D Endo software (Dentsply Sirona, Salzburg, Austria) to determine the working length when using preoperative cone-beam computed tomographic (CBCT) scans of extracted teeth, compared with conventional CBCT software and an electronic apex locator (EAL).

METHODS

CBCT scans of 30 premolars were obtained. Using OnDemand3D software (Cybermed, Seoul, Korea), the measurement obtained from the coronal reference to the apical foramen (AF) was recorded as the conventional CBCT length. Then, using 3D Endo software (Dentsply Sirona), the suggested length (3D-SL) and the operator-adjusted length (3D-OL) were obtained. Teeth were accessed, and the actual length was measured. Finally, the teeth were embedded in alginate to obtain the electronic length (EL) using the EAL Root ZX (J Morita, Tokyo, Japan). The means of the absolute values and the percentages of distribution of the tested measurement methods were compared to the actual length.

RESULTS

No difference was found regarding the mean measurements (analysis of variance, P > .05). All the CBCT measurements presented a high reliability (Dahlberg's formula). The measurements within a ±0.5-mm range from the AF were 86.6% for the 3D-SL, 80% for the 3D-OL and EL, and 73.3% for the CBCT length. The EL presented significantly fewer underestimated measurements (P < .05). The 3D-OL and 3D-SL presented significantly fewer measurements beyond the AF (P < .05).

CONCLUSIONS

The preoperative working length determination using 3D Endo was reliable and similar to conventional CBCT software. However, the combined use of CBCT with an EAL is required to increase the accuracy in the location of the AF.

Comparison of Digital Radiography, Conventional Film and Self-Developing Film for Working Length Determination

INTRODUCTION

Accurate measurement of working length of the root canal is an important factor in endodontic treatment, because it determines the level of cleaning and shaping of the canal. This can be performed using numerous methods including conventional, digital and self-developing methods, which are studied in this work.

METHODS AND MATERIALS

In this study, 50 maxillary molars with appropriate conditions for the analysis were collected and their mesiobuccal canal lengths were estimated by three different types of radiographs with and without file. Next, two endodontists and a radiologist reviewed all the images under the same conditions. The precise lengths of the canals were measured by removing teeth from their casts and direct observation. Finally, data regarding differences in radiographic length and actual length were examined by SPSS 16.0 software and Repeated Measures ANOVA test.

RESULTS

There was no significant difference in any of the radiographic states. The differences of root canal lengths were not significant for the first (endodontist) and third (endodontist) observers; whereas, there were significant differences for the second observer (radiologist). The differences were not significant for samples without files (P=0.89). However, the differences were significant for samples with files (P=0.03).

CONCLUSION

Since analysis showed that there were no significant differences between the results of digital radiography, conventional film and self-developing film methods in working length determination, the clinician can choose any of these methods according to the working conditions without being concerned about losing the accuracy.

Use of artificial primary teeth for endodontic laboratory research: experiments related to canal length determination

Background

Due to the scarcity of exfoliated/extracted human primary teeth with complete roots, artificial teeth were developed as an alternative to be used for educational and laboratory research purposes. This study aimed to assess the feasibility of using artificial primary teeth for conducting laboratory research through an experiment related to canal length determination, comparing artificial teeth with natural teeth.

Methods

Thirty anterior and 21 posterior artificial teeth, and the same number of natural primary teeth were selected. After preparing the access cavity, the root canal length was determined by two examiners twice using three different methods: radiography and two electronic apex locators. Then, the actual root canal length was measured by inserting a K-file up to the apical foramen (reference standard). Accuracy was calculated using Bland-Altman analysis and intraclass correlation coefficient (ICC). The inter- and intra-examiner reproducibility was also calculated using the ICC.

Results

The methods using the electronic apex locators showed better accuracy in both artificial and natural teeth. Trends observed with artificial primary teeth were similar to those observed with natural teeth, except for the results in artificial anterior teeth.

Conclusions

The model of artificial teeth might be a good alternative for educational purposes; however, improvements are necessary to employ these teeth for research purposes when considering experiments for canal length determination.

Electronic supplementary material

The online version of this article (10.1186/s12903-017-0420-3) contains supplementary material, which is available to authorized users.

In vivo assessment of accuracy of Propex II, Root ZX II, and radiographic measurements for location of the major foramen

Objectives

The aim of this in vivo study was to assess the accuracy of 2 third-generation electronic apex locators (EALs), Propex II (Dentsply Maillefer) and Root ZX II (J. Morita), and radiographic technique for locating the major foramen (MF).

Materials and Methods

Thirty-two premolars with single canals that required extraction were included. Following anesthesia, access, and initial canal preparation with size 10 and 15 K-flex files and SX and S1 rotary ProTaper files, the canals were irrigated with 2.5% sodium hypochlorite. The length of the root canal was verified 3 times for each tooth using the 2 apex locators and once using the radiographic technique. Teeth were extracted and the actual WL was determined using size 15 K-files under a × 25 magnification. The Biostat 4.0 program (AnalystSoft Inc.) was used for comparing the direct measurements with those obtained using radiographic technique and the apex locators. Pearson's correlation analysis and analysis of variance (ANOVA) were used for statistical analyses.

Results

The measurements obtained using the visual method exhibited the strongest correlation with Root ZX II (r = 0.94), followed by Propex II (r = 0.90) and Ingle's technique (r = 0.81; p < 0.001). Descriptive statistics using ANOVA (Tukey's post hoc test) revealed significant differences between the radiographic measurements and both EALs measurements (p < 0.05).

Conclusions

Both EALs presented similar accuracy that was higher than that of the radiographic measurements obtained with Ingle's technique. Our results suggest that the use of these EALs for MF location is more accurate than the use of radiographic measurements.

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.

The maxillary molar endodontic access opening: A microscope-based approach

This article reviews the basic clinical techniques of performing a maxillary molar endodontic access opening, starting from the initial access opening into the pulp chamber, to the point where a size #10 file has been advanced to the apices of all three or four (or more) canals. The article explains how the use of the dental surgical operating microscope or microscope-level loupes magnification of ×6–8 or greater, combined with head-mounted or coaxial illumination, improve the ability of a dentist to identify microscopic root canal orifices, which facilitates the efficient creation of conservative access openings with adequate straight-line access in maxillary molars. Magnified photos illustrate various microscopic anatomical structures or landmarks of the initial access opening. Techniques are explored for implementing an access opening for teeth with vital versus necrotic pulpal tissues. The article also explores the use of piezoelectric or ultrasonic instruments for revealing root canal orifices and for removing pulp stones or calcified pulpal tissue inside the pulp chamber.

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.