Clinical investigation of second mesiobuccal canals in endodontically treated and retreated maxillary molars

Incidence of Middle Mesial Canals in Mandibular Molars during Root Canal Treatment and Nonsurgical Retreatment

INTRODUCTION

Large-scale clinical studies on the incidence of middle mesial canals (MMCs) in nonsurgical root canal treatment (RCT) and retreatment of mandibular molars are lacking. The primary aim of this observational study was to determine the incidence of MMCs in mandibular first and second molars that received RCT or nonsurgical retreatment (NSRetx). The secondary aim was to determine factors associated with incidence of MMCs.

METHODS

Included were 3018 mandibular molars that received RCT (n = 1624) or NSRetx (n = 1394) by 3 endodontists in a private practice. Demographic and procedural data were collected. Bivariate and multivariable (Poisson regression model) analyses were performed.

RESULTS

Incidence of MMCs was 8.8% (n = 267). Although the bivariate analysis showed that NSRetx was significantly associated with incidence of MMCs, this association did not reach the threshold for statistical significance after controlling for all covariates (P = .07). Multivariable analysis on the entire cohort showed that incidence of MMCs was significantly associated with younger age (risk ratio [RR] = 1.62; 95% confidence interval [CI], 1.28-2.06), male gender (RR = 1.48; 95% CI, 1.18-1.85), preoperative cone-beam computed tomography (CBCT) (RR = 1.48; 95% CI, 1.17-1.89), and first molar (RR = 2.30; 95% CI:1.74-3.05). Subgroup multivariable analyses revealed that incidence of MMCs was associated with male gender only in the RCT group (RR = 2.26; 95% CI, 1.55-3.30) but not in the NSRetx group (RR = 1.11; 95% CI, 0.82, 1.50); and with preoperative CBCT only in the NSRetx group (RR = 1.78; 95% CI, 1.28, 2.50) but not in the RCT group (RR = 1.10; 95% CI, 0.71, 1.69). Associations with younger age and first molar remained unchanged.

CONCLUSIONS

Overall incidence of MMCs was 8.8%. Incidence of MMCs was significantly higher in younger patients and in mandibular first molars but was not associated with the type of treatment.

Effect of the progressive taper enlargement of buccal root canals of three-rooted maxillary molars: A stepwise micro-CT study

This study evaluated unprepared canal areas, volume of dentine removal, and dentine thickness after the progressive enlargement of the buccal canals of 22 maxillary molars, with and without the MB2, using instruments with the same tip size (0.25 mm) but 4 different tapers (0.03, 0.05, 0.06 and 0.08 v). Micro-CT scans were performed after each instrument. Data were compared using a general linear mixed model post hoc comparisons with Kenward-Roger for Wald F tests (α = 5%). After each treatment step, it was observed an increase in the percentage volume of removed dentine and a decrease in the unprepared areas and dentine thickness at the pericervical region of all canals (p < 0.05). The percentage reduction of dentine thickness in MB2 canal was higher than in the mesiobuccal and distobuccal canals (p < 0.05). Knowledge of pre-operative dimensions and dentine thickness before enlargement of buccal canals of maxillary molars is an important factor to avoid excessive dentine removal.

Clinical identification and endodontic management of furcation canals: a case series

In the case of endodontic infection, the presence of furcation canals can be at the origin of a periodontal lesion located in the furcation. The furcation being very close to the marginal periodontium, this type of lesion can be favorable to the genesis of an endo-periodontal lesion. These furcation canals are lateral canals located on the pulp chamber floor and constitute one of the many physiological communication pathways between endodontic and periodontal tissues. These canals are most often difficult to localize, shape, and to fill because of their small diameter and length. The disinfection of the pulp chamber floor with sodium hypochlorite solution may contribute to the disinfection of furcation canals when they are not identified, shaped, and/or filled. This case series illustrates the endodontic management of visible furcation canals associated with an endo-periodontal lesion. These furcation canals had a large diameter which allowed their identification during the endodontic treatment.

Location angle of second mesio-buccal canal in maxillary molars of an Indian population: an in vivo retrospective CBCT evaluation and proposal of a new classification

Background

The current investigation was designed for predicting the location angle of second mesio-buccal root canal in permanent maxillary (first and second) molars with the aid of proposed measuring points and line using cone beam computed tomography in an Indian population.

Methods

Three-hundred and twenty-four scans of permanent maxillary (first (n = 162) and second (n = 162)) molars with mesio-buccal 2 root canals and unassociated to the current evaluation were acquired. The maxillary molars were viewed with CSI imaging software. The images were captured and were further assessed using 3D Slicer. The assessment included of measuring the distance between the main mesio-buccal and mesio-buccal 2 canal and the angle at which the MB2 it is located utilizing proposed lines joining the disto-buccal and palatal canals. The data was tabulated for the incidence of various angles where the MB2 is located and MB-MB2 distance was determined. The angles denoted were either positive; I (0.1° to 1.9°), II (2° to 4°), III (>4°) or negative I (-0.1° to -1.9°), II (-2° to -4°), III (>-4°). On the data tabulated a new Banga Vhorkate and Pawar's (BVP's) angular classification for maxillary molars was proposed.

Results

The existence of positive angle III was found in 41.35% of maxillary first molars (36 right and 31 left of 162), whereas positive angle II appeared in 41.98% of maxillary second molars (32 right and 36 left of 162). The MB1-MB2 in maxillary 1^st molar is seen to be 3.12-3.31 mm and this distance in maxillary 2^nd molar is 2.8-3.1 mm. The disto-buccal to palatal canal orifice mean distance was 5.06-5.22 mm in maxillary first molars and 4.9-5.8 mm in maxillary second molars.

Conclusion

Accurate diagnosis of the location of second mesio-buccal canal increases the success rate of endodontic treatment and a better prognosis. The new proposed classification may be considerably helpful in the urge to locate the mesio-buccal 2 canal.

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

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

The Prevalence and Location of the Second Mesiobuccal Canals in Maxillary First and Second Molars Assessed by Cone-Beam Computed Tomography

Objective

This retrospective study aimed to investigate the prevalence and location of the second mesiobuccal (MB2) canal in the mesiobuccal root of the maxillary first molar (MFM) and the maxillary second molar (MSM) through cone-beam computed tomography (CBCT) imaging.

Methods

One thousand two hundred CBCT images of the MFM and MSM were divided equally and analyzed. To standardize the methodology of MB2 detection, the observation and measurements were located at the pulpal floor by 1 mm apically. The distances between canals were calculated from the center point of the MB2 canal (PMB2) to the center point of both the first mesiobuccal canal (PMB1) and the palatal canal (PP). The data were provided in the form of frequencies and percentages. The chi-square test was used to analyze the differences among maxillary molars, while the significance level was set at 0.05.

Results

The prevalence of the MB2 canal in the MFM and MSM was 46.7% (p=0.020) and 17.7% (p=0.457), respectively. Additionally, the prevalence of the MB2 canal was more frequent in females. The average distance between PMB1 and PMB2 for MFM and MSM was 1.87±0.42 mm and 1.24±0.76 mm, respectively. Furthermore, the average distances of PMB2 and PP were 0.74±0.21 mm and 0.43±0.18 mm for MFM and MSM, respectively.

Conclusion

The MB2 canal was found in 386 (32.2%) of the maxillary molars. The Saudi people have a high possibility of discovering the MB2 canal. The CBCT is a useful and high-precision diagnostic tool not only for detecting but also for locating in vivo MB2 canal in the mesiobuccal root of maxillary molars.

Assessment of Mesiobuccal Canal Configuration, Prevalence and Inter-Orifice Distance at Different Root Thirds of Maxillary First Molars: A CBCT Study

Aim

The aims of this study were to assess the prevalence and configuration of the second mesiobuccal (MB2) canal in the mesiobuccal MB root of permanent maxillary first molars at different root levels in a Saudi sub-population using cone‑beam computed tomography (CBCT) and to measure the inter-orifice distance between MB & MB2 at the pulpal floor level.

Materials and Methods

This retrospective study was carried out on CBCT images of Saudi patients seen at King Abdul Aziz University. A total of 106 maxillary first molars were evaluated using a specialized software program (iCAT CBCT software). The prevalence of MB2, canal configuration and location of joining (apical-middle-coronal), if present was calculated. Also, the inter-orifice distance between both canals was measured at the level of the pulpal floor. Chi‑square and one-way analysis of variance (ANOVA) were used.

Results

The MB2 canal was found in 92 (86.8%) maxillary first molar teeth. The MB and MB2 canals were joined in 61 (58%) cases, where the location of joining was 14 (23%), 17 (27%), and 31 (50%) in the coronal, middle, and apical third, respectively. The mean inter-orifice distance between both canals at the level of the pulpal floor was 2.52±0.76 mm.

Conclusion

The prevalence of MB2 canal in this Saudi sub-population was high. The prevalence decreased as the root canal approached the apical third. There was no correlation between the average distance and occurrence of canal joining. CBCT is useful in detecting and mapping the mesiobuccal root canal system, with a likelihood of enhancing the quality of root canal treatment.

Decision making process by senior residents of Saudi Board in restorative dentistry for nonsurgical endodontic retreatment: A retrospective study

Background

Despite the general guidelines for retreatment, differences in decision making exist for secondary endodontic treatment and may be related to many factors including education, clinical experience, dentist specialty, patient preferences and economic resources. Aim of the study was to evaluate the decision making of the Saudi Board in Restorative Dentistry (SBRD) senior residents in the endodontic retreatment of molar teeth as per the scientific guidelines of the American Association of Endodontists (AAE) and also to identify the causes of retreatment and measure how far they become deviated from their taught retreatment principles and inter-individual variability.

Materials and methods

Case histories have been obtained from the files of cases treated in the SBRD Resident Comprehensive Case Archives in the SCHS from 2003 to 2015 in Riyadh region. The cases were only confined to Complex I and Complex II cases according to RDITN (Restorative Dental Index of Treatment Need), and seen by R3 and R4 residents only. Residents' diagnosis was recorded as well as their treatment plan and any given notes regarding their decisions to retreat. Differences between the two groups (R3 and R4) residents and within the same group, regarding endodontic retreatment decisions and reasons for their treatment options were analyzed using Chi-Square test and Fisher's Exact test.

Results

The majority of residents in both R4 and R3 groups followed the recommended guidelines. R3 residents preferred to retreat all cases while R4 chose 'no to retreat' in few cases. Although R4 residents preferred nonsurgical retreatment more than R3 residents, the difference was insignificant. R4 residents preferred 'no therapy' or 'follow up' more frequent than R3 residents. Members of the R3 residents agreed more or less with each other as did those of the R4 residents without significant inter-individual variations within each group regarding the choice of retreatment).

Conclusions

R4 residents appeared more likely, although not significant, to choose no retreatment or follow up than R3 residents. Conventional nonsurgical retreatment had the highest selection by both R3 and R4 residents. No significant inter-individual variations within each group regarding the choice of retreatment. There is a need to establish evidence based guidelines for more uniform management of failed root treated teeth.

The Association between Choice of Diagnostic Imaging Modality and Long-term Treatment Outcomes for Patients Undergoing Nonsurgical Root Canal Treatment on Maxillary First Molars

INTRODUCTION

Radiography has played a fundamental role in the advancement of nonsurgical root canal therapy (NSRCT), allowing for more accurate diagnosis and treatment. Typically, providers choose to perform NSRCT using periapical (PA) radiographs alone or, often in more difficult cases, in conjunction with cone-beam computed tomographic (CBCT) imaging. This study aimed to evaluate the outcomes of NSRCT based on imaging modality selection for the initial treatment of maxillary first molars.

METHODS

A retrospective chart review was conducted using 1385 cases of NSRCT on maxillary first molars. Charts were reviewed for patient demographics and treatment outcomes. Based on the imaging modality used, patients were stratified into 2 groups (PA radiographs alone or PA radiographs + CBCT imaging). Those who required additional treatment(s) after the completion of NSRCT were classified as having "posttreatment disease." Statistical analysis was performed to assess the differences between groups.

RESULTS

After the completion of primary endodontic therapy, 5.8% (n = 81) of the entire sample had posttreatment disease. CBCT imaging was used in 13.4% (n = 185) of NSRCTs. Although not significant, cases that were difficult enough to require the use of CBCT imaging had a higher rate of posttreatment disease compared to those that could be completed with PA radiographs alone (8.6% vs 5.4%, P > .05). Results from a multivariable logistic regression model showed that the need for CBCT imaging had a nonsignificant positive association with posttreatment disease (P > .05).

CONCLUSIONS

The decision to use CBCT imaging appears to serve as a proxy for case complexity and the associated increase in risk of posttreatment disease. This is important to keep in mind when assessing treatment prognosis.

Mesiobuccal Root Canal Morphology of Maxillary First Molars in a Brazilian Sub-Population - A Micro-CT Study

Objective:

This study aimed to investigate the root canal system morphology of maxillary first molar mesiobuccal (MB) roots in a Brazilian sub-population using micro-computed tomography.

Methods:

Ninety-six MB roots were scanned with a micro-CT (Skyscan 1173, Bruker). Three-dimensional images were analyzed regarding the number of pulp chamber orifices, the number and classification of the canals, the presence of accessory canals in different thirds of the root as well as the number and type of apical foramina.

Results:

A single entrance orifice was found in 53.0% of the samples, two in 43.9% and only 3.1% had three orifices. The second mesiobuccal root canal (MB2) was present at some portion of the root in 87.5% of the specimens. A single apical foramen was present in 16.7%, two in 22.9%, and three or more foramina in 60.4% of the roots. Only 55.3% and 76.1% of the root canals could be arranged by Weine’s and Vertucci’s classifications, respectively.

Conclusion:

The number of orifices at the pulp chamber level could not work as a predictor of the MB2 presence. The most prevalent canal configuration was Weine type IV / Vertucci type V. The anatomical complexity of the MB root could not be entirely classified by the current most accepted classifications.

The MB3 canal in maxillary molars: a micro-CT study

OBJECTIVES

To assess the internal and external morphologies of the mesiobuccal (MB) root of maxillary molars presenting a third root canal (MB3), using micro-computed tomography (micro-CT).

MATERIAL AND METHODS

Two-hundred and sixty-five extracted maxillary first and second molars with different root configurations were imaged in a micro-CT scanner at 19.6-μm pixel size. Sixteen teeth presenting MB3 canal were selected and evaluated regarding root configuration, minimal dentine thickness 2 mm under the furcation area, canal configuration of the MB root, MB3 canal morphology (location, independent or confluent orifice, and anatomy types), and the apical anatomy (aspect ratio, number of accessory canals and foramina, presence of isthmus, and independent MB3 foramen).

RESULTS

Overall, a high variability in canal configuration was detected in the MB root. MB3 canal was observed in 10 maxillary first molars and 6 maxillary second molars (n = 16). Minimal dentine thickness related to the MB3 canal at the coronal third was smaller than that of the MB1 canal. A complex internal anatomy comprising 13 different root canal configurations was observed. A high number of independent MB3 orifices at the pulp chamber floor was observed in the first molars (7 out of 10 teeth), while most of the specimens (n = 14) showed a confluent anatomy of the MB3 canal. A varied number of accessory canals and foramina were observed. At the apical third, isthmus could be observed in 6 specimens, while an independent MB3 foramen was present in 37.5% of the MB roots.

CONCLUSIONS

MB3 canal is a rare anatomical variation present in maxillary first and second molars. Its presence can be associated to a complex internal anatomy of the MB root which includes the presence of isthmuses and multiple accessory canals and foramina at the apical third, but also a thin dentine thickness at the coronal third and a confluent anatomy of the MB3 with the other main canals.

Cone-beam-computed-tomography of the symmetry of root canal anatomy in mandibular incisors

This study aimed to evaluate the prevalence of internal symmetry (the number and morphology of root canals) in the mandibular incisors using cone beam computed tomography (CBCT). A total of 302 CBCT scans involving 1,208 mandibular incisors were evaluated using the Vertucci's classification regarding the number and configuration of root canals. The central mandibular incisors exhibited two root canals in 22.6% of patients and lateral incisors in 24.3% of patients. Most teeth (76.4%) had a type I configuration (a single root canal, 1-1), 21.7% had type II (2-1), 1.1% had type V (1-2), and 0.8% had type IV (2-2). Teeth with a type-III configuration (1-2-1) were not found. In total, 17.5% of patients had a symmetric appearance of the two-canalled central mandibular incisors and 20.5% had a bilateral appearance of the two-canal lateral incisors. Moreover, in 12.3% of the patients, all four incisors showed two root canals. The highest degree of symmetry was found in incisors that had one root canal (central incisors: 217 of 302, lateral incisors: 229 of 302), followed by type 2-1 incisors (central incisors 50, lateral incisors 58). The influence of sex and age on the prevalence of symmetries was not significant. Concluding, the internal anatomy of the mandibular incisors cannot not be sufficiently predicted from the root canal anatomy of the contralateral tooth. Thorough clinical and radiographic inspection of each tooth remains mandatory to address the internal anatomy of the mandibular incisors correctly.

Fracture behavior of root-amputated teeth at different amount of periodontal support - a preliminary in vitro study

Background

The purpose of this study was to evaluate the effect of the amount of periodontal support on the fracture resistance of root-amputated maxillary molar teeth restored with either direct class. I. restorations or class II. mesio-occluso-distal (MOD) indirect overlay restorations with cuspal coverage.

Methods

Sixty sound maxillary first molars were collected and randomly divided into four groups. In Groups 1 and 2, MOD cavities were prepared and all cusps were reduced by 2 mm, whereas in Group 3 and 4, only a conservative Class I. cavity was prepared. Subsequently, root canal treatment was performed and the mesio-buccal roots were amputated. Groups 1 and 2 were restored with indirect composite overlay, while Groups 3 and 4 received direct composite fillings. After restoration, teeth were embedded as follows: Groups 1 and 3: normal bone level, Groups 2 and 4: furcation involvement. The specimens were submitted to static fracture resistance testing. Fracture thresholds and fracture patterns were measured and evaluated.

Results

Group 1 had the highest fracture resistance (2311,6 N) among the restored groups and showed statistically significant difference compared to Group 2 (p = 0.038) and Group 4 (p = 0.011). There was no statistically significant difference in terms of fracture resistance between the rest of the groups. In terms of the fracture patterns, Group 3 was characterized by the highest percentage (60%) of mostly favorable fractures, while the rest of the groups showed predominantly unfavorable ones.

Conclusions

The amount of periodontal support seems to influence the fracture resistance of root-amputated and restored maxillary molars.

The second mesiobuccal canal in three-rooted maxillary first molar of Karnataka Indian sub-populations: A cone-beam computed tomography study

Introduction

Elusive second mesiobuccal canal (MB2) in maxillary first molar are often missed during endodontic therapy and are a major cause of treatment failures. Its prevalence is known to vary among different populations and there is limited information on its prevalence in Indian population.

Aim

This study investigated the prevalence and location of second mesiobuccal (MB2) canal in mesiobuccal root of maxillary first molar using cone beam computed tomography (CBCT) images in an Indian population.

Materials and methods

CBCT images of 598 three rooted maxillary first molars were studied. In each CBCT image, the floor of pulp chamber was located and advanced by 2 mm to standardize the observation for MB2 canal. Its location was determined in relation to mesiobuccal (MB1) and palatal (P) canal.

Statistical analysis

The data was analysed using descriptive statistics. The presence of MB2 canal was correlated with age, gender and tooth position using Chi square test.

Results

The prevalence of MB2 canal in three rooted maxillary first molar was 61.9%. It was seen that the prevalence of MB2 was highest in 20-40years age group (67.4%) followed by > 40 years (57.5%) and lowest in <20 years (50.6%) and the difference was statistically significant (p = 0.005). It is located mesiopalatally; 2.5 mm ± 0.6 mm palatally and 1.0 ± 0.4mmmesially to the MB1 canal or present directly on the line joining the MB1 and palatal canal.

Conclusion

There is a high probability of finding MB2 canal in Indian patients. The access cavity must be modified from a triangular shape to rhomboid shape. Troughingmesiopaltally (about 2.5 mm palatally and 1 mm mesially) from MB1 to a depth of about 2 mm from the floor of pulp chamber may be necessary for locating MB2 canal.

An original micro-CT study and meta-analysis of the internal and external anatomy of maxillary molars-implications for endodontic treatment

The aim of this work was to conduct a radiological micro-CT study and meta-analysis to determine the morphological features of the root canal anatomy of the maxillary molars. The radiological study included micro-CT scans of 110 maxillary first molars and 98 maxillary second molars. To identify articles eligible for inclusion in our meta-analysis, PubMed, Embase, and Web of Science were search comprehensively. The following data were extracted: study type (cadaveric, intraoperative or imaging), Vertucci types of canal configuration, presence/number of canals, roots, apical foramina, apical deltas, and inter-canal communications. The mesiobuccal root was the most variable with respect to canal configuration, type I being the most common configuration followed by type II and type IV. Type I was the most common canal configuration in the distobuccal and palatal root. Regarding the number of canals in the maxillary first and second molars, one canal was most prevalent in all roots of the three molars, except for the mesiobuccal root of maxillary first molar, in which two canals were most prevalent. The most prevalent number of roots in all maxillary molars was three. Knowledge of endodontic anatomy determines the parameters of root canal treatment and significantly affects the probability of success. It is therefore especially important to know the morphology of the root canal system in order to perform endodontic treatment correctly. Clin. Anat. 31:838-853, 2018. © 2018 Wiley Periodicals, Inc.

The prevalence of second canals in the mesiobuccal root of maxillary molars: A cone beam computed tomography study

The aim of this study was to determine the prevalence of MB2 canals in permanent maxillary molars utilising CBCT; in patients attending a university hospital. A total of 200 patient scans, (100 female and 100 male patients), were enrolled in the study. In total, 800 teeth were analysed, and teeth with additional canals in their MB roots (MB2) were identified. First maxillary molar teeth exhibited the highest prevalence of MB2 canals, 92% and 87%, for teeth 16 and 26, respectively. Second maxillary molar teeth showed a lower prevalence of MB2 canals, 69% and 65%, for the 17 and 27, respectively. There were no associations of significance between the prevalence of MB2 canals and patient age or gender. Root morphology and anatomy of permanent maxillary first and second molar teeth was found to be highly variable. The prevalence of additional canals in the MB roots is a frequent finding which has previously been underreported.

Geometric features of second mesiobuccal canal in permanent maxillary first molars: a cone-beam computed tomography study

Background/purpose

Inadequacy to locate the second mesiobuccal canal (MB2) canal leads to the highest probability of endodontic failure in permanent maxillary first molars (PMFMs) and still remains a constant challenge for many clinicians. The aim of this study was to characterize the geometrical features between MB2 and other orifices of examined PMFMs using cone-beam computed tomography images.

Materials and methods

A total of 108 teeth qualified in the cone-beam computed tomography image archives were enrolled in the present study. The intersecting point (T) was determined as the perpendicular line (h, altitude of triangle) projected from the vertex of the MB2 canal orifice to mesiobuccal canal orifice-palatal canal orifice line (MB1-P). We measured the geometric features of PMFMs with the MB2 canal, including the interorifice distances, area, altitude, and the ratio between the canal orifices.

Results

The average interorifice distance was found to be 1.91 ± 0.59 mm for MB1-MB2, 5.73 ± 0.66 mm for MB1-P, and 4.11 ± 0.79 mm for MB2-P, with significant gender difference for MB1-MB2 distance. For the MB1-T distance, a significant difference was found between genders (P = 0.02), with males averaging 1.78 ± 0.07 mm, and females 1.48 ± 0.11 mm. For the MB1-P distance, the majorities of both genders were found in the 20–40% cut-off. A portion of the males exhibited a tendency towards the 40–80% cut-off, while females shifted in the reverse direction towards the 0–20% cut-off.

Conclusion

In clinical scenarios, these anatomical characteristics of the root canals system could be beneficial to locating the MB2 canal.

Magnification devices for endodontic therapy

BACKGROUND

After the introduction of microsurgical principles in endodontics involving new techniques for root canal treatment, there has been a drive to enhance the visualisation of the surgical field. It is important to know if the technical advantages for the operator brought in by magnification devices such as surgical microscopes, endoscopes and magnifying loupes, are also associated with advantages for the patient in terms of improvement of clinical and radiographic outcomes. This version updates the review published in 2009.

OBJECTIVES

To evaluate and compare the effects of endodontic treatment performed with the aid of magnification devices versus endodontic treatment without magnification devices. We also aimed to compare the different magnification devices used in endodontics with one another.

SEARCH METHODS

The following electronic databases were searched: the Cochrane Oral Health Group Trials Register (to 13 October 2015), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2015, Issue 9), MEDLINE via OVID (1946 to 13 October 2015) and EMBASE via OVID (1980 to 13 October 2015). We searched the US National Institutes of Health Trials Register (http://clinicaltrials.gov) and the WHO Clinical Trials Registry Platform for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We considered all randomised controlled trials (RCTs) and quasi-randomised controlled trials comparing endodontic therapy performed with versus without one or more magnification devices, as well as randomised and quasi-randomised trials comparing two or more magnification devices used as an adjunct to endodontic therapy.

DATA COLLECTION AND ANALYSIS

We conducted screening of search results independently and in duplicate. We obtained full papers for potentially relevant trials. The Cochrane Collaboration statistical guidelines were to be followed for data synthesis.

MAIN RESULTS

No trials met the inclusion criteria for this review.

AUTHORS' CONCLUSIONS

No article was identified in the current literature that satisfied the criteria for inclusion. It is unknown if and how the type of magnification device affects the treatment outcome, considering the high number of factors that may have a significant impact on the success of endodontic surgical procedure. This should be investigated by further long-term, well-designed RCTs that conform to the CONSORT statement (www.consort-statement.org/).

Root canal morphology of South Asian Indian maxillary molar teeth

OBJECTIVE

The objective was to study the root canal morphology of South Asian Indian Maxillary molars using a tooth clearing technique.

MATERIALS AND METHODS

Hundred teeth each comprising of first, second, and third molars collected from different dental schools and clinics in India were subjected to standard dye penetration, decalcification and clearing procedure before being studied.

RESULTS

The first molar mesiobuccal roots exhibited 69% Type I, 24% Type II, 4% Type IV, 2% Type V, and 1% exhibited a Vertuccis Type VIII canal anatomy. In the group with three separate roots the second molar mesiobuccal roots in exhibited 80.6% Type I, 15.3% Type II, 2.7% Type IV, and 1.4% Type V canal anatomy while the third molars mesiobuccal roots exhibited 57.4% Type I, 32% Type II, 2.1% Type III, 8.5% Type IV, 1% had a Type V canal anatomy in the similar group.

CONCLUSION

A varied root canal anatomy was seen in the mesiobuccal root canal of the maxillary molars.

Frequency of second mesiobuccal canal in permanent maxillary first molars using the operating microscope and selective dentin removal: A clinical study

Purpose:

The aim of this study was to investigate whether the combination of operating microscope and selective dentin removal increased the frequency of second mesiobuccal (MB2) canal detection in permanent maxillary first molar teeth.

Materials and Methods:

One hundred fifty permanent maxillary first molars indicated for root canal treatment were randomly selected from patients belonging to the age group of 18–45 years irrespective of gender. After access cavity preparation and location of main canals, the MB2 canal orifice was sought in all teeth with an endodontic explorer under direct vision (Stage I), then under magnification with the aid of operating microscope (Stage II) and finally with the combined use of operating microscope and selective dentin removal (Stage III).

Results:

MB2 canals were detected in 36%, 54% and 72% of the teeth in Stages I–III, respectively.

Conclusion:

This study demonstrated that dental operating microscope when used along with adjunctive aids such as selective dentin removal/troughing and good clinical knowledge will increase the ability of dental clinician to locate MB2 canals.

Microscope magnification and ultrasonic precision guidance for location and negotiation of second mesiobuccal canal: An in vivo study

Objective:

The aim of this study was to evaluate the influence of using the dental operating microscope (DOM) and ultrasonics for the detection of second mesiobuccal (MB2) canal orifice in maxillary first molars.

Materials and Methods:

Sixty subjects seeking root canal therapy for maxillary first molar were assessed for the presence of MB2 canal using endodontic explorer without magnification. Teeth in which the MB2 canal orifice could not be located were examined under magnification using DOM. If the MB2 canal orifice could not be found even after using DOM, ultrasonic tips were used to prepare 3-mm-long trough from the mesiobuccal canal orifice toward the palatal canal and examined under DOM for location of the canal.

Results:

With naked eye, the MB2 canal was located in 12 teeth; with the use of the DOM, the MB2 canal was located in 21 additional teeth; and with the combined use of ultrasonic tip and DOM, the MB2 canal was located in 9 more teeth. Statistical comparisons between the tested techniques were done by analyzing the Receiver Operating Characteristic (ROC) curves; a statistically significant difference was found (P < 0.001).

Conclusion:

The results of this study indicate that the DOM and ultrasonics provide increased opportunity for the dentist to detect canal orifices.

CBVT analysis of canal configuration of the mesio-buccal root of maxillary first permanent molar teeth: An in vitro study

CONTEXT

For successful endodontic treatment, it's imperative to locate and obturate all root canals. As concluded by Ingle, the major cause for failure of root canal therapy is in ability to recognize all theexisting canals and subsequent failure in their obturation.

AIM

To analyze the canal configuration of the mesio-buccal root of maxillary first permanent molar teeth.

MATERIALS AND METHODS

A total of 30 recently extracted human permanent maxillary first molars were collected and stored in a container with 5% Sodium Chloride solution for four days. Teeth with open apices, external resorption, improperly formed roots and teeth with previous restorations were excluded. Using the dental modeling wax, teeth were arranged in a 'U' shaped arch with roots embedded inside the wax and occlusal surface remaining free. 10 teeth were arranged in each arch and three such sample plates were prepared. Flat surface of the base encasing enabled the plate to be mounted on flat plastic bite plate. With bite plate roughly centered in the focal trough area Axial, Coronal and Sagittal section Cone-Beam Computed Tomography (CBCT) images were taken with Kodak 9000 Extra-oral Imaging System. Images displayed on a monitor were inspected by two endodontists using Kodak Dental Imaging Software 3D Module V2.2.

STATISTICAL ANALYSIS

When the data was observed, it was found that 24 teeth out of total 30 teeth examined showed some variation (i.e. possible additional canal) along the length of the mesio-buccal root canal. Out of these 24 teeth, 13 showed presence of additional canal at coronal third, 7 showed presence of additional canal at middle third and four showed presence of additional canal in apical third level. Percentage analysis was done as there was no group comparison to be done.

RESULTS

Cone-Beam Volumetric Tomography (CBVT) evaluation positively identified the variations in mesio-buccal canal in 80% of samples. Out of these, 54.16% were in coronal 3(rd), 29.16% in middle 3(rd) and 16.66% were in apical 3(rd).

CONCLUSION

Within the limitations of this study, it can be concluded that- (1) more than half of maxillary first molars have four canals and (2) most of the additional canals were located in the MBR and CBVT is a good diagnostic tool to help diagnose these additional canals. Further investigations using larger sample sizes would be helpful.

Maxillary first Molar with three canal orifices in MesioBuccal root

The present case describes root canal treatment in a maxillary first molar with unusual anatomy. A male patient was referred for the treatment of maxillary left first molar tooth. Clinical examination of the pulpal floor revealed 3 orifices in the mesio buccal root. The tooth was treated successfully. Anatomic variations must be taken into consideration in clinical and radiographic evaluation during endodontic treatment

Microcomputed tomography analysis of mesiobuccal orifices and major apical foramen in first maxillary molars

OBJECTIVE

Aim of the study was to determined by microcomputed tomography (µCT) the horizontal distance between the main (MB1) and the second mesiobuccal canal (MB2) orifices, the vertical distance between the MB1 and MB2 orifices planes, and the distance between the anatomic apex and major apical foramen (AF). Furthermore, we characterized the entire internal and external anatomy of the MB, distalbuccal (DB) and palatal (P) maxillary first molars roots.

MATERIALS AND METHODS

Twenty-two intact extracted first maxillary molars were scanned by X-ray computed transaxial µCT and then 2D and 3D images were processed and analyzed.

RESULTS

The results showed that 77.27% of the mesiobuccal (MB) roots presented a second MB canal, and 29.41% of the MB2 were independent from the MB1 canals. In 15 teeth, there were three root canal orifices on the chamber floor, and 10 of these teeth presented MB2 canals. The mean vertical distance between the MB1 and MB2 planes was 1.68 ± 0.83 mm. Seven teeth had four orifices. The mean horizontal interorificial distance between the MB1 and MB2 orifices was 1.21 ± 0.5 mm. Accessory canals were observed in 33.33% of the roots, loops in 6.06%, while isthmuses were found in 15 of the 22 MB roots. Of the total roots, 74.24% presented one foramen, while all of the roots showed a major apical foramen that was not coincident with the anatomic apex.

CONCLUSIONS

Our µCT analysis provided interesting features on the horizontal and vertical distance between the MB1 and MB2 orifices and on the distance of AF and anatomic apex.

CLINICAL RELEVANCE

These results have an important clinical value because might support the endodontist in the recruitment, negotiation and obturation of maxillary first molar canal system.

Endodontic management of a maxillary first molar with unusual location of second mesio buccal orifice

Maxillary first molar can have a mesio-buccal-2 (MB2) orifice located palatally, but adjacent to the mesio buccal orifice. An awareness and understanding of this root canal morphology can contribute to the successful outcome of root canal treatment. This report discusses endodontic treatment of a maxillary first molar with unusual location of second mesio buccal orifice. Conventional diagnostic aids such as radiographs play an important role in assessment of complex root canal morphologies. These modalities, however, do not provide detailed information of the complexity as a result of their inherent limitations. This article discusses the variations in the orifice location and the use of latest adjuncts in successfully diagnosing and negotiating them.

Mesiobuccal root canal anatomy of Korean maxillary first and second molars by cone-beam computed tomography

OBJECTIVE

The aim of this study was to investigate the types of canal configurations and the incidence of a second mesiobuccal (MB2) canal in Korean maxillary molar mesiobuccal (MB) roots by analyzing cone-beam computed tomographic (CBCT) images.

STUDY DESIGN

Three-dimensional CBCT images of 458 maxillary first molars and 467 second molars from 276 Korean patients were analyzed to determine the incidence of an MB2 canal, the types of canal configurations, and the correlations between the incidence of an MB2 canal and age, gender, and tooth position.

RESULTS

The incidence of 2-canaled MB roots was 71.8% in first molars and 42.2% in second molars, with the most common configurations being Weine types III and II. The frequency of an MB2 canal decreased with age in both molars (P < .05).

CONCLUSIONS

Types III and II canal configurations were the most prevalent in the 2-canaled MB roots of Korean maxillary molars.

Morphologic Variations of Maxillary Molars Palatal Root and the Importance of Its Knowledge for Endodontic Practice: A Case Series

Aim

The present report describes and discusses root canal variations in the internal morphology of maxillary molars.

Background

Dental internal anatomy is directly related to all the technical stages of the endodontic treatment. Even though, in some situations a typical anatomical characteristics can be faced, and the professional should be able to identify them.

Case descriptions

This clinical report describes five cases with different pulpar and periapical diagnostics where the endodontic treatment was performed, in which during the treatment the unusual occurrence of two or three canals in the palatal root ‘or even two distinct palatal roots’ of first and second maxillary molars, were described and important details for achieving treatment success were discussed.

Conclusion

The knowledge of tooth internal anatomy must be considered during clinical and radiographic examinations. This should be valued not only to find atypical canals but also to enable calcified canals cleaning and shaping, once they are frequently omitted during endodontic therapy.

Clinical significance

Anatomic variations can occur in any tooth, and palatal roots of maxillary first and second molars are no exception. The complexity of the root canal system and the importance of identifying its internal anatomy for planning endodontic treatment increase the chances of success.

How to cite this article

Scarparo RK, Pereira L, Moro D, Gründling G, Gomes M, Grecca FS. Morphologic Variations of Maxillary Molars Palatal Root and the Importance of Its Knowledge for Endodontic Practice: A Case Series. J Contemp Dent Pract 2011;12(2):138-142.

Morphological characteristics of mesiobuccal root canals of the first maxillary molars

Introduction. The first maxillary molar is a tooth with three roots, and mesiobuccal one is with the most complex canal morphology. Factors influencing variations of its morphology are numerous, and may significantly complicate endodontic treatment. Objective. The objective was to investigate the number, configuration and curvature orientation of the mesiobuccal root canals in the maxillary first molars. Methods. The study was conducted on 200 mesiobuccal (MB) roots of extracted first molars in human subjects using radiography. In each canal Flexofile was introduced until reaching the apical foramen and the root was then radiographed in series from two projections. Number of root canals (MB1, MB2 and MB3), configuration according to Vertucci classification, and the orientation of the curvature were established. Relevant statistical parameters and the significance of differences were computed (p<0.05). Results. Of total 200 mesiobuccal roots 86.5% were with two, 9% with three, and 4.5% with a single canal. Most frequent configurations were type IV (36%) and II (34.5%). From the clinical projection all MB1 canals were oriented distally, from the proximal 78% palatally and 22% buccally. The orientation of all MB2 canals was distal from the clinical projection, from the proximal projection 76% were oriented palatally, and 24% buccally. The MB3 canal was always oriented distally from the clinical projection, and buccally from the proximal aspect. Conclusion. The mesiobuccal roots of the first maxillary molars showed multiple canals in 96%, with dominant Vertucci type II and IV of configuration. All canals were curved.

Magnification devices for endodontic therapy

BACKGROUND

After the introduction of microsurgical principles in endodontics, involving new techniques for root canal treatment, there has been a continuous search for enhancing the visualisation of the surgical field. It would be interesting to know if the technical advantages for the operator brought in by magnification devices like surgical microscope, endoscope and magnifying loupes, are also associated with advantages for the patient, in terms of improvement of clinical and radiographic outcomes.

OBJECTIVES

The purpose of this systematic review was to evaluate and compare the effects of endodontic treatment performed with the aid of magnification devices versus endodontic treatment without magnification devices. We also aimed at comparing among them the different magnification devices used in endodontics (microscope, endoscope, magnifying loupes).

SEARCH STRATEGY

The Cochrane Oral Health Group Trials Register, CENTRAL, MEDLINE and EMBASE were searched with appropriate search strategies. Handsearching included nine dental journals. The bibliographies of relevant clinical trials and relevant articles were checked for identifying studies outside the handsearched journals. Seven manufacturers of instruments in the field of endodontics and/or endodontic surgery, as well as the authors of the identified randomised controlled trials (RCTs) were contacted in order to identify unpublished or ongoing RCTs. There were no language restrictions. The last electronic search was conducted on 2nd April 2009, and the last handsearching was undertaken on 31st January 2009.

SELECTION CRITERIA

All randomised and quasi-randomised trials comparing endodontic therapy performed with or without using one or more types of magnification device, as well as randomised and quasi-randomised trials comparing two or more magnification devices used as an adjunct to endodontic therapy were considered.

DATA COLLECTION AND ANALYSIS

Screening of studies and data extraction were conducted independently and in duplicate. The Cochrane Collaboration statistical guidelines were to be followed for data synthesis.

MAIN RESULTS

No trial could be included in the present review. All of the prospective trials that were identified, all dealing with endodontic surgery, had to be excluded for various reasons. Only one RCT was identified comparing three magnificators (magnifying loupes, surgical microscope, endoscope) in endodontic surgery. No RCT was found that compared the outcome of endodontic therapy using or without using a given magnification device.

AUTHORS' CONCLUSIONS

No objective conclusion can be drawn from the results of this review as no article was identified in the current literature that satisfied the criteria for inclusion. It is unknown if and how the type of magnification device affects the treatment outcome, considering the high number of factors that may have a significant impact on the success of endodontic surgical procedure. This should be investigated by further long-term RCTs with large sample size. Technical advantages of magnificators have been widely reported in low evidence level studies, but they should be systematically addressed to know if there can be the clinical indication for using a given magnification device for specific clinical situations, such as for molar teeth, or if they can all be used interchangeably. Well-designed RCTs should also be performed to determine the true difference in terms of treatment success rates between using or not using a magnification device in both conventional and surgical endodontic treatment, if any exist.

Effects of imaging system and exposure on accurate detection of the second mesio-buccal canal in maxillary molar teeth

OBJECTIVES

The objectives of this study were to determine observer ability to detect the second mesio-buccal canal (MB2) in maxillary molars using analog film, CMOS, and photostimulable phosphor x-ray detectors across a wide range of radiation exposures and to determine the optimal exposures for these modalities accurately detecting presence of the MB2.

RESEARCH DESIGN

Using 6 experimental models with 2 maxillary molars in each, images were generated with the 3 detector modalities at nominal x-ray beam angulations of 0 degrees and 10 degrees across a range of radiation exposures. Observers independently assessed presence of the MB2 in images presented in random order. Horizontal root sections were then evaluated to determine true MB2 presence.

RESULTS

For single images at optimal exposures, the correct number of mesiobuccal canals could be identified 55% of the time for CMOS (RVG 6000), 44% of the time for analog x-ray film (InSight), and 39% of the time for photostimulable phosphor (DenOptix). Statistically significant differences were observed between the imaging modalities (chi2 = 23.4, crucial value = 5.99, P < or = .05). RVG 6000 CMOS outperformed both DenOptix photostimulable phosphor (z score = -5.5) and InSight analog direct exposure x-ray film (z score = 4). Exposure affected the rate of accuracy for MB2 detection across the exposure range tested for RVG 6000 and for film, but not to any appreciable degree for DenOptix.

CONCLUSIONS

The CMOS detector (RVG-6000) performed best for evaluating presence of the MB2. This was the only modality to exceed 50% reliability with optimal exposure when single images were considered.

Root and root canal morphology of the human permanent maxillary first molar: a literature review

The objective of this study was to review the literature with respect to the root and canal systems in the maxillary first molar. Root anatomy studies were divided into laboratory studies (in vitro), clinical root canal system anatomy studies (in vivo) and clinical case reports of anomalies. Over 95% (95.9%) of maxillary first molars had three roots and 3.9% had two roots. The incidence of fusion of any two or three roots was approximately 5.2%. Conical and C-shaped roots and canals were rarely found (0.12%). This review contained the most data on the canal morphology of the mesiobuccal root with a total of 8399 teeth from 34 studies. The incidence of two canals in the mesiobuccal root was 56.8% and of one canal was 43.1% in a weighted average of all reported studies. The incidence of two canals in the mesiobuccal root was higher in laboratory studies (60.5%) compared to clinical studies (54.7%). Less variation was found in the distobuccal and palatal roots and the results were reported from fourteen studies consisting of 2576 teeth. One canal was found in the distobuccal root in 98.3% of teeth whereas the palatal root had one canal in over 99% of the teeth studied.

Levels of Evidence for the Outcome of Nonsurgical Endodontic Treatment

The purpose of this systematic review was (a) to search for clinical articles pertaining to success and failure of nonsurgical root canal therapy, and (b) to assign levels of evidence to these studies. Electronic and manual searches were conducted to identify studies published between January 1966 and September 2004 with information on the success and failure of nonsurgical root canal therapy. Articles were reviewed and graded for strength of level of evidence (LOE) from one (highest level) to five (lowest level). This review resulted in the identification of 306 clinical studies related to this topic area. Six articles were randomized controlled trials (RCTs, LOE 1). This search also identified 12 low-quality RCTs (LOE 2), 14 cohort studies (LOE 2), five case-control and eight cross sectional studies (LOE 3), four low-quality cohort studies (LOE 4), and five low-quality case-control studies (LOE 4). The majority (73) of the often-quoted "success and failure" studies were case series (LOE 4). The rest of the articles were descriptive epidemiological studies (42), case reports (114), expert opinions (18), literature reviews (4), and one meta-analysis. Based on these findings, it appears that a few high-level studies have been published in the past four decades related to the success and failure of nonsurgical root canal therapy. The data generated by this search can be used in future studies to specifically answer questions and test hypotheses relevant to the outcome of nonsurgical root canal treatment.

Three canals in the mesiobuccal root of a maxillary first molar: a case report

This article describes the identification and treatment of a maxillary first molar exhibiting three canals in the mesiobuccal root. An 18-yr-old male patient presented for nonsurgical root canal therapy of tooth #3. After accessing the pulp chamber, and probing with 2.5x magnification, only one canal was located in the mesiobuccal root initially. Subsequent to troughing the groove between the mesiobuccal and palatal canals with a #2 round bur, two additional canals were located. An electronic apex locator was utilized to ensure a perforation of the pulpal floor had not occurred. A working film confirmed the presence of three canals in the mesiobuccal root, and the canals were cleaned, shaped, and obturated.

Apical Anatomy in Mesial and Mesiobuccal Roots of Permanent First Molars

The purpose of this in vitro study was to investigate the canal configuration types, and the prevalence and location of anatomical variations in the mesiobuccal (MB) and mesial roots of permanent maxillary and mandibular first molars after instrumentation. The number and the type of canals were determined before instrumentation using conventional methods. All root canals from the 47 MB roots and 42 mesial roots were then instrumented to size #30 with ProFile .04 taper rotary instruments in a crown-down method and then filled with a single gutta-percha cone and sealer. Transverse 1 mm-thick cross-sections at 2, 3, 4, and 5 mm from the apex were obtained, stained and examined using a stereomicroscope. The canal configuration types and the prevalence and location of isthmi and accessory canals in roots with two canals were evaluated. The prevalence of two canals was 80.8% in the maxillary MB roots and 95.2% in the mandibular mesial roots. There were six types of canal configurations in the instrumented root apices. The prevalence of anatomical variations was highest at the apical 4 mm level, and was more frequent in mandibular first molars, and in roots with Weine type III canal. chi test showed that the prevalence of the anatomical variations was statistically higher in the maxillary MB roots with Weine type III canals than in those with Weine type II canals (p < 0.05). Different canal configurations were often found at different levels in the same root. The results indicate that anatomical variations persist following instrumentation of roots with two canals in first molars. These anatomical variations should be considered during surgical or nonsurgical endodontic procedures of the permanent first molars.

A 5 Yr Clinical Investigation of Second Mesiobuccal Canals in Endodontically Treated and Retreated Maxillary Molars

An examination of 5616 endodontically treated and retreated maxillary first and second molars was made in an attempt to determine the percentage of MB2 canals that could be located routinely, and evaluate if there were any significant differences between initial treatments and retreatments. The teeth examined were 3578 first molars and 2038 second molars treated consecutively over a 5-yr period by six endodontists. Overall the MB2 canal was found in 2133 (60%) first molars, and 712 (35%) second molars. The incidence of a MB2 canal in first molar retreatments was 66% compared to a 58% incidence in initial treatments. Whereas in second molars the retreatment incidence was 40% compared to 34% in initial treatments. The significant difference in the incidence of a MB2 canal between initial treatments and retreatments suggests that failure to find and treat existing MB2 canals will decrease the long-term prognosis.

The benefit of the operating microscope for access cavity preparation by undergraduate students

Although studies show the operating microscope (OM) provides benefits for endodontists, the benefit to undergraduates has not been evaluated as completely as for specialists. The purpose of this study was to determine whether using the OM would improve students' performance in endodontic access cavity preparation and canal identification. Thirty-six dental students prepared access cavities and located canals in extracted maxillary molars, before and after training, which varied according to group. The standard group received a lecture and practice in preparation of access cavities. The microscope group received identical instruction using the OM. The control group received lectures only. All groups received equal content and instruction time (2 hr 20 min). Faculty graded preparations according to a multidimensional 5-point rating scale. Using the OM, the microscope group improved significantly in access cavity preparation (p <0.05) and significantly outperformed both standard and control groups in accuracy of identifying canals (p <0.05).

Nonsurgical retreatment

With all the potential for endodontic success, the fact remains clinicians are confronted with posttreatment endodontic disease. When the elected treatment plan is endodontic nonsurgical retreatment, then the goal is to access the pulp chamber and remove materials from the root canal space and if present, address deficiencies or repair defects that are pathologic or iatrogenic in origin. This article provides a literature review with clinical recommendations for one important group of retreatment issues: the removal of posts and broken instruments.

Detection of the second mesiobuccal canal in mesiobuccal roots of maxillary molar teeth ex vivo

AIM

To assess the effectiveness of magnification and dentine removal (troughing) when locating the second mesiobuccal canal in mesiobuccal roots of maxillary molars.

METHODOLOGY

A total of 208 extracted human maxillary molars were examined. After crown and pulp removal, the MB1 and 2 canals in the mesiobuccal root were located in three stages that were performed by two undergraduate dental students. Stage 1: canals were located with an endodontic explorer; stage 2: additional canals in the same teeth were located under magnification with a digital microscope (VH-8000, Keyence, Japan); stage 3: additional canals in the same teeth were located by removing dentine (troughing) from the pulp chamber floor within 3 mm from MB1 canal towards the palatal canal with an Enac ultrasonic tip (ST 21, Osada, Japan). In each group, the canals were prepared with Gates Glidden burs and K-files. The distal and palatal roots were then removed, and Indian ink was injected into the canal system within the mesio-buccal root. The root surfaces were washed with 6% NaOCl, and then rendered transparent to observe canal morphology. The root canal configurations were classified into five categories following the modified Weine's classification.

RESULTS

More than one canal in the mesio-buccal root was observed in 48% of specimens. Detection rates of multiple canals were 7, 18 and 42% following stages 1, 2 and 3, respectively. There was a significant difference between the stages for detecting the MB2 canal (P < 0.05, Friedman test).

CONCLUSIONS

Both magnification (stage 2) and dentine removal under magnification (stage 3) were effective in detecting the presence of the MB2 canal. However, MB2 canals could not be detected in 13% of the teeth because of canal calcification or branching located more apically.