Second mesiobuccal root canal in maxillary molars—A systematic review and meta-analysis of prevalence studies using cone beam computed tomography

Assessment of Anatomical Dentin Thickness in Mandibular First Molar: An In Vivo Cone-Beam Computed Tomographic Study

Aim

To determine the minimum dentin thickness in the mesial and distal walls of the mesiobuccal (MB) and mesiolingual (ML) canals of the mandibular first molars using cone-beam computed tomography (CBCT).

Materials and Methods

CBCT examinations of 624 mandibular first molars from an Indian subpopulation were analyzed. The mesial and distal minimum dentin thickness was evaluated in 1 mm intervals apical to the furcation area. Independent t-test was used to analyze the data (α = 0.05). Using Cohen's kappa coefficient, the interexaminer and intraexaminer reliability was evaluated.

Results

The mesial dentin thickness was significantly higher than the distal dentin thickness for MB and ML canals (P=0.01). The average dentin thickness in the distal and mesial plane of the MB canal was 1.15 ± 0.15 mm and 1.52 ± 0.19 mm at the 1 mm level and 0.83 ± 0.13 and 1.08 ± 0.18 at the 5 mm level, respectively. For the ML canal, the average dentin thickness in the distal plane and the mesial plane was 1.24 ± 0.18 mm and 1.44 ± 0.21 at the 1 mm level and 0.91 ± 0.16 and 1.01 ± 0.17 at the 5 mm level, respectively. Statistical analysis between the MB and ML canals showed significant differences in the dentin thickness at 4 and 5 mm levels in both the distal and the mesial planes (P=0.01). In more than 85% of the cases, the minimum dentin thickness was seen at the 5 mm level in both the distal and mesial planes in MB and ML canals.

Conclusion

The distal planes of the mesiolingual and mesiobuccal canals were thinner in most cases, making the distal surface more prone to iatrogenic perforations. Considerably, at 4 and 5 mm from the furcation, the distal wall was significantly thinner than the mesial walls. Understanding the anatomy of the danger zone in the mesial roots of the mandibular first molars may serve to minimize the risk of endodontic mishaps such as strip perforations.

Second mesiobuccal canal segmentation with YOLOv5 architecture using cone beam computed tomography images

The objective of this study is to use a deep-learning model based on CNN architecture to detect the second mesiobuccal (MB2) canals, which are seen as a variation in maxillary molars root canals. In the current study, 922 axial sections from 153 patients' cone beam computed tomography (CBCT) images were used. The segmentation method was employed to identify the MB2 canals in maxillary molars that had not previously had endodontic treatment. Labeled images were divided into training (80%), validation (10%) and testing (10%) groups. The artificial intelligence (AI) model was trained using the You Only Look Once v5 (YOLOv5x) architecture with 500 epochs and a learning rate of 0.01. Confusion matrix and receiver-operating characteristic (ROC) analysis were used in the statistical evaluation of the results. The sensitivity of the MB2 canal segmentation model was 0.92, the precision was 0.83, and the F1 score value was 0.87. The area under the curve (AUC) in the ROC graph of the model was 0.84. The mAP value at 0.5 inter-over union (IoU) was found as 0.88. The deep-learning algorithm used showed a high success in the detection of the MB2 canal. The success of the endodontic treatment can be increased and clinicians' time can be preserved using the newly created artificial intelligence-based models to identify variations in root canal anatomy before the treatment.

Relationship between apical periodontitis and missed canals in mesio-buccal roots of maxillary molars: CBCT study

Objectives

The objectives of this study were to: (1) assess the frequency of missed canals in the mesiobuccal root (MB) of endodontically treated maxillary molars and its association with apical periodontitis (AP); (2) examine the correlation between the presence of a confluent or separate missed MB2 canal and the prevalence of AP; and (3) examine the correlation between the technical quality of endodontic treatment in the MB1 canal and the prevalence of AP.

Methods

We obtained and examined 800 cone-beam computed tomography (CBCT) scans from 800 patient records over 6 months. The parameters noted for each tooth included the tooth number; presence of missed canals in the MB root; configuration of missed MB2 canals (confluent or separate); technical acceptability of root canal treatment (RCT) of treated MB1 canals; and the CBCT periapical index score. Data were analyzed in SPSS version 24.

Results

A total of 203 maxillary molars from 148 CBCT scans were included. The MB2 canal prevalence was 88.2% in maxillary first molars and 62.7% in maxillary second molars. MB2 was found in 164 endodontically treated maxillary molars. During treatment, MB2 was missed in 150 (91.5%) and treated in 14 (8.5%) teeth. A total of 103 teeth (50.73%) had AP, which was observed in 67.3% of teeth with a missed MB2 canal but only 14.3% of teeth with a treated MB2 canal. The prevalence of AP was 43.7% in teeth with confluent MB2 canals and 80.9% in teeth with separate MB2 canals.

Conclusion

The MB2 canal frequency was significantly higher in the examined maxillary first molars than the maxillary second molars. The MB2 canal was missed in most teeth that underwent endodontic treatment. The AP prevalence was relatively higher in endodontically treated maxillary molars with missed MB2 canals.

Upper First and Second Molar Pulp Chamber Endodontic Anatomy Evaluation According to a Recent Classification: A Cone Beam Computed Tomography Study

(1) The possibility of knowing information about the anatomy in advance, in particular the arrangement of the endodontic system, is crucial for successful treatment and for avoiding complications during endodontic therapy; the aim was to find a correlation between a minimally invasive and less stressful endodontic access on Ni-Ti rotary instruments, but which allows correct vision and identification of anatomical reference points, simplifying the typologies based on the shape of the pulp chamber in coronal three-dimensional exam views. (2) Based on the inclusion criteria, 104 maxillary molars (52 maxillary first molars and 52 maxillary second molars) were included in the study after 26 Cone Beam Computed Tomography (CBCT) acquisitions (from 15 males and 11 females). And linear measurements were taken with the CBCT-dedicated software for subsequent analysis. (3) The results of the present study show data similar to those already published about this topic. Pawar and Singh's simplified classification actually seems to offer a schematic way of classification that includes almost all of the cases that have been analyzed. (4) The use of a diagnostic examination with a wide Field of View (FOV) and low radiation dose represents an exam capable of obtaining a lot of clinical information for endodontic treatment. Nevertheless, the endodontic anatomy of the upper second molar represents a major challenge for the clinician due to its complexity both in canal shape and in ramification.

Cone-Beam Computed Tomography Assessment of Prevalence of Procedural Errors in Maxillary Posterior Teeth

A range of procedural errors can occur when performing endodontic treatment on posterior teeth. These errors may decrease the success rate in endodontic practice. This study assessed the prevalence of procedural errors and the quality of endodontic treatments in maxillary molars and premolars using cone-beam computed tomography (CBCT). CBCT scans from two private radiology centers were assessed retrospectively to ensure the same calculated sample size of 327 teeth for each of the four maxillary posterior tooth types (a total of 1,308 endodontically treated teeth). Image sets were evaluated for procedural errors categorized as follows: obturation length (overfilling or underfilling by >2 mm short of the root apex), missed canals, perforations, strip perforations (with extrusion of material into the furcation area), separated instruments in the root canal space, and root fracture. Data were analyzed with SPSS version 20 (SPSS Inc., Chicago, IL, USA), and frequency data was assessed using the Monte Carlo test at the 0.05 level of significance. The procedural errors most commonly reported in the present study were from most frequent to least frequent: underfilled canals (50.0%), missed canals (27.5%), overfilled canals (12.5%), apical perforations (5.0%), separated instruments (3.1%), and root fractures (1.9%). No strip perforations (with extrusion of material into the furcation area) were seen in the study (0%). Underfilled and missed root canals were the most frequent procedural errors identified in the present study. These findings underline the importance of more consideration of critical working length management during all stages of root canal treatment, greater awareness of root canal anatomy, and the use of imaging and diagnostic devices that enhance the ability to identify and treat root canals both safely and effectively.

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.

Concurrency of additional canals in mandibular incisors and second mesiobuccal canal in maxillary first molars: A cone-beam computed tomography investigation

This study investigated the concurrency of additional canals in mandibular incisors and the second mesiobuccal canal in maxillary first molars among the Chinese population. In total, 8644 cone-beam computed tomography images from 8644 patients with bilateral mandibular incisors and maxillary first molars were examined. The data were analysed using Chi-square test, binary logistic regression analysis and receiver operating characteristic curve. Among the patients with additional canals in mandibular central and lateral incisors, 96.2% and 95.5% of them had second mesiobuccal canal in maxillary first molars, respectively. Additional canals of mandibular incisors and second mesiobuccal canal in maxillary first molars exhibited a concurrent relationship. The prevalence of second mesiobuccal canal in maxillary first molars increased with the number of mandibular incisors with additional canals. Moreover, when there was at least one mandibular incisor with additional canals, the presence of the second mesiobuccal canal in maxillary first molars could be highly expected.

A comparison of online and face-to-face modalities in endodontic preclinical education: A retrospective study

PURPOSE

The aim of this study was to evaluate the competency of undergraduate students in following the principles of access cavity preparation and the radiographic quality of root canal filling in maxillary molar teeth in either online or face-to-face education courses during the novel coronavirus disease 2019 (COVID-19) pandemic.

METHODS

A total of 178 extracted maxillary molar teeth that underwent endodontic dental treatment by undergraduate students who completed the endodontic preclinical practice course online or face-to-face during the COVID-19 pandemic were retrospectively analyzed. A visual access cavity examination determined the form, width of the cavity, deroofing of the pulp chamber, and the presence of a perforation. Root canal fillings were examined radiographically on periapical radiographs for length, homogeneity, taper, and the presence of iatrogenic defects. Statistical analysis was performed using the chi-square test.

RESULTS

The incidence of incorrect form, wide cavities, and perforation was statistically higher in the online group than in the face-to-face group (p < 0.05). It was determined that root filling length and homogeneity were more successful in the face-to-face group (p < 0.05). When evaluated for iatrogenic errors, the presence of broken instruments was found to be significantly higher in the online group (p < 0.05). There was no significant difference between the groups in other iatrogenic errors and the taper of the root canal filling (p > 0.05).

CONCLUSION

The students who underwent face-to-face education were more successful in accessing cavity preparation and root canal fillings than the students who undertook online education.

Cone beam computed tomography analysis of the root and canal morphology of the maxillary second molars in a Hail province of the Saudi population

Background

The goal of the present research was to employ CBCT imaging to assess the root and canal anatomy of maxillary second molars in a population from the Hail province of Saudi. The effects of gender and side were taken into account.

Methods

The investigation included a sample size of 499 completely developed right and left untreated maxillary second molars obtained from 250 Saudi people. The root morphology of each tooth was evaluated. The examination also included an analysis of the canal morphology for each tooth, utilizing Vertucci's categorization. The effect of genders as well as sides was recorded. Results were analyzed using the Chi-square test.

Results

464 teeth had three roots (93.0%), whereas 20 teeth (4.0%) had two roots. One root was recorded in 7 (1.4%) of the study sample, whilst 8 (1.6%) had four roots. Although there were no significant differences between the left and right sides (p = .075), gender had a significant influence on the number of roots (p = .030). 240 M (48.1%) had three canal orifices, and 247 (49.5%) had four root canal orifices. Eight molars (1.6%) had two canal orifices, while one and five canal orifices were found in 3 (0.6%) and one (0.2%), respectively. Gender had a significant impact on the number of root canal orifices (p = .039). The observed differences in the orifices of the root canals between the left and right sides were not statistically significant (p = .059). The prevalence of MB2 in maxillary second molars was found to be 49.7%. In the mesiobuccal root, the Vertucci type I configuration had the highest canal frequency (50.3%), followed by the Vertucci types II (14.4%), IV (13.8%), V (12.0%), and III (7.6%), and VI (1.8%). The prevalence of Vertucci type I canal configurations was found to be higher in the distobuccal root (99.4%) and palatal root (98.2%) of maxillary second molars.

Conclusions

Significant variations in root canal anatomy were observed within the Saudi population. The majority of the subjects from Saudi Arabia in this study exhibited the presence of maxillary second molars with three roots. Approximately half of the sample under investigation exhibited the presence of the four canals.

Variation in location of the distobuccal root canal in a permanent maxillary second molar: A case report

Key Clinical Message

Clinicians should be aware of the variations in the number of roots and root canals and the peculiar or eccentric location of root canals. An intraoperative CBCT can be very useful in improved visualization of the anatomical variations.

Abstract

This case report describes the unusual location of the distobuccal root canal in a maxillary second molar with root fusion. On access opening, three distinct root canal orifices, the mesiobuccal canal, palatal canal, and a third orifice closer to the palatal canal, were seen, giving an illusion of an additional palatal canal. An attempt was made to search for the distobuccal canal in its usual position, leading to the gouging of the pulp chamber floor. An intraoperative limited field of view cone-beam computed tomography (CBCT) revealed the root orifice adjacent to the palatal canal was the distobuccal canal. CBCT also revealed fusion of both the buccal and palatal roots in the root's coronal and middle third region, but they were not fused apically.

Non-surgical Root Canal Treatment of an Upper First Molar With an Unusual Morphology: A Case Report

This paper presents the unusual morphology of an upper right first molar with two roots, each containing a single canal, in a patient seeking emergency endodontic treatment. Clinical and radiographic examinations revealed the unusual root canal morphology of the tooth, which required further investigation using cone beam computed tomography (CBCT) imaging, which confirmed this unusual anatomical structure. It was also noted that the upper right first molar was asymmetrical to the upper left first molar, which had the normal three-root morphology. The buccal and palatal canals were instrumented using ProTaper Next Ni-Ti rotary instruments and enlarged to ISO size 30, with a taper of 0.7; irrigated with 2.5% NaOCl; filled with gutta-percha using the warm-vertical-compaction technique, with the aid of a dental operating microscope (DOM); and then confirmed via periapical radiograph. The DOM and CBCT are valuable aids that helped us to confirm the endodontic diagnosis and treatment of this unusual morphology.

Location of the Second Mesiobuccal Canal of Maxillary Molars in a Brazilian Subpopulation: Analyzing Using Cone-beam Computed Tomography

AIM

This study aimed to evaluate the spatial location of the second mesiobuccal canal (MB2) of maxillary molars (MMs), using cone-beam computed tomography (CBCT), in a Brazilian subpopulation.

MATERIALS AND METHODS

The CBCT examination of 250 patients performed on the Eagle 3D device was analyzed, totaling 787 MMs. Using the Radiant Dicom Viewer software, measurements were made of the distances, in millimeters (mm), between the first mesiobuccal canal (MB1), MB2, and palatal (P) canal inputs, from the axial sections. The Image J software evaluated the angle formed by the lines. The data obtained were analyzed statistically by Fisher's exact and Chi-square tests with a significance of 5%.

RESULTS

The prevalence of MB2 canals observed was 76.44 and 41.73% in the first and second molars (1MMs and 2MMs), respectively (p < 0.05). The average of the distances and angles performed, for the location of the MB2 canals of the analyzed teeth, were MB1-P = 5.83 mm, MB1-MB2 = 2.31 mm, and MB2 for the intersection of the connecting distance from MB2-T = 0.90 mm. The average angle formed between the MB1-P and MB1-MB2 distances was 25.89° and 19.68° for the 1MMs and 2MMs, respectively. It was also observed that 91.4 and 75.4% of the maxillary 1MMs and 2MMs, respectively, presented the MB2 canals mesially located at the line connecting the MB1-P canals (p < 0.0001).

CONCLUSION

The MB2 canals were located mesially to the MB1 canal with an average distance of 2 mm between the canals.

CLINICAL SIGNIFICANCE

The anatomical knowledge of the spatial location of the MB2 canal in different ethnicities is important for the planning and execution of endodontic treatment.

Anatomic Comparison of Contralateral Maxillary Second Molars Using High-Resolution Micro-CT

The present study aimed to measure and compare anatomic parameters in contralateral maxillary second molars. A total of 18 intact maxillary second molar pairs (n = 36) extracted from 18 patients were scanned with micro-computed tomography (micro-CT) and then reconstructed. Axial, sagittal, and cross-sectional slices were used to analyze the parameters (lengths, widths, and thicknesses) and evaluate the symmetry of the right and left sides. The number of root canals and their internal patterns were classified following Vertucci’s classification. The number of lateral canals and their locations were also noted. Contralateral second molar pairs demonstrated a high degree of similarity in terms of the linear measurements (lengths, widths, and thicknesses). The root canal anatomy configuration symmetry of mesiobuccal, distobuccal, and palatal roots according to Vertucci’s classification were 41.1%, 88.2%, and 94.4%, respectively. In total, 41.6% of mesiobuccal roots, 2.7% of distobuccal roots, and 30.6% of palatal roots had at least one lateral canal. The apical third (38.7%) was the most frequent location of lateral canals, followed by the middle third (32.3%) of the root. This study provides insight into the anatomy of the root canals of contralateral maxillary second molars, which is valuable for both practitioners and researchers.

Can the detection of second mesiobuccal canals be enhanced based on the volume of adjacent canals?

OBJECTIVES

The purpose of this study was to evaluate whether the presence of the second mesiobuccal (MB2) canal is related to volumetric differences on the adjacent canals of maxillary molars.

DESIGN

Forty-seven maxillary first and second molars with and without the MB2 canal were individually scanned using microcomputed tomography (micro-CT). The volume of each canal was measured by an evaluator with experience in micro-CT analysis. The intraclass correlation coefficient (ICC) was obtained. Multiple logistic regression and odds ratio was calculated. To compare the volume of canals in molars with and without MB2, the Mann-Whitney test was applied (α = 0.05).

RESULTS

The intra-examiner reproducibility was almost perfect (ICC=0.97). Multiple logistic regression demonstrated that the volume of the mesiobuccal (MB1) canal can possibly act as a predictor of the presence of the MB2 canal. It was also found that the MB1 canal volume is larger in molars without the MB2 canal (p = 0.01). No statistically significant difference was observed in the adjacent canals (p > 0.05).

CONCLUSIONS

Despite the challenging detection of the presence of MB2 canals, clinicians should be aware that MB1 canals of reduced volume are highly suggestive of their presence.

Negotiating the second mesiobuccal canal: A comparison of nickel titanium files through the experience of undergraduate dental students

OBJECTIVES

The aim of this study was to compare the ability of undergraduate students to reach working length (WL) in second mesiobuccal root canals (MB2) of maxillary first molars (n = 210) by using Reciproc Blue without glide path preparation, and One Curve with glide path preparation.

METHODS

The students (n = 105) attended theoretical and practical courses. The first group (n = 53) shaped MB2 root canals using the One Curve system and then Reciproc Blue; the second group (n = 52) shaped MB2 root canals following the reverse sequence. Participants completed a questionnaire. The chi-square and Mann-Whitney U test were used for statistical analysis using significance of p < 0.05.

RESULTS

The full WL was reached and shaping procedures were completed without complications in Reciproc Blue and One Curve groups at rates of 86.67% and 82.85%, respectively (p > 0.05). Treatment time was shorter in Reciproc Blue (p < 0.05). More (62.9%) students felt the One Curve system safer, while 61% felt the Reciproc Blue system faster.

CONCLUSIONS

Within the limitations of this study, instrument kinematics and glide path preparation did not interfere with undergraduate students' ability to achieve the WL in MB2 root canals.

Cone-beam computed tomography study of the incidence and characteristics of the second mesiobuccal canal in maxillary permanent molars

Objective: This study aimed to review the characteristics of the second mesiobuccal canal (MB2) in the maxillary first and second permanent molars of 500 patients to analyze the incidence of MB2 and its connection with gender, age, tooth position, and mesiobuccal (MB) root length. The study also aimed to investigate the distribution of the root canal orifice on the pulp chamber floor to obtain an imaging reference for clinical practices related to maxillary molars in Fujian, China. Methods: In accordance with the enrollment criteria, cone-beam computed tomography images of the maxillofacial area were collected from 500 patients, including 1,000 maxillary first molars and 1,000 maxillary second molars. The patients were grouped according to gender and tooth position. The incidence of MB2 was observed, and the MB root length and distribution angle of the mesiobuccal-palatal-distobuccal root canal orifices were measured for statistical analysis. Results: The overall incidence of MB2 in maxillary first and second molars was 51.1% and 32.9%, respectively. The incidence of MB2 in maxillary molars was 50% in male patients and 35.45% in female patients, with a significant difference (p < 0.05). The incidence of MB2 in maxillary molars was significantly higher in subjects aged below 50 (especially in male patients) than those aged 50 and above. The MB root length of maxillary first and second molars with MB2 was longer than that without MB2, and the difference was statistically significant. An association was identified between the incidences of MB2 in contralateral molars of the same type and in ipsilateral adjacent molars. When MB2 occurred in the MB root of maxillary molars, the root canals were mostly classified as type IV, followed by type II. The angle formed by the MB-P-DB orifices on the pulp chamber floor in the maxillary first and second molars was (25.23 ± 5.20) and (20.17 ± 10.88)°respectively. Conclusion: The incidence of MB2 in maxillary molars is high in Fujian, China. The occurrence of MB2 is affected by gender, age, and length of MB root, and it occurs symmetrically in adjacent molars and in contralateral molars of the same type. In addition, the distribution law of the main root canal orifice at the pulp chamber floor is conducive to locating MB2, thereby guiding clinical operations.

Prevalence of mesiobuccal-2 canals in maxillary first and second molars among the Bruneian population—CBCT analysis

Introduction

Identification of the second mesiobuccal canal (MB-2) in maxillary molars is considered an endodontic concern of many practitioners due to its complex morphology. The use of Cone-beam Computed Tomography (CBCT) is a necessity for easier location of this elusive canal during endodontic treatment.

Aim

To study the prevalence of the MB-2 canal in the maxillary first and second molars amongst the Bruneian population.

Materials and methods

A retrospective study involving a review of scans taken from a CBCT scanner (J Morita; Veraviewepocs 3D R100 Panoramic/Cephalometric) over a 5-year period, from May 2016 to May 2021 was carried out. A total of 342 maxillary molars were evaluated independently by two observers. Any contradicting outcomes were discussed by both observers until a consensus was reached. In addition, the correlation of MB-2 canals with gender and age were calculated using the chi-squared test.

Results

The prevalence of MB-2 canal in the maxillary first and second molars are 51.3% and 29.8% respectively. Both males and females have a similar prevalence of MB-2 canals in the maxillary first and second molars. The incidence of MB-2 canals in both maxillary first and second molars significantly decreases with increasing age. No significant correlation between the prevalence of MB-2 canals with different gender groups in the population.

Conclusions

It is crucial for clinicians to identify the presence of MB-2 canals when performing endodontic treatment of the maxillary first and second molars. Varying prevalence has been reported for different populations. Recognising this wide-ranging prevalence amongst different populations will allow for greater predictability in ensuring endodontic treatment success.

Endodontic treatment of the maxillary first molar with palatal canal variations: A case report and review of literature

BACKGROUND

Root canal variations frequently occur in maxillary first molars, which greatly affects the success of its treatment. The second mesiobuccal (MB) root canal is the most common root canal variation. However, only a few studies have been conducted on palatal root canal variations. Herein, we report the presence of two separate root canals in a palatal root of the maxillary first molar.

CASE SUMMARY

A 39-year-old woman complained of pain in the maxillary right region for 1 year, which recently worsened. Clinical examination revealed a poorly restored right maxillary first molar and caries detected at the filling marginal. Cold and heat test results indicated severe pain in the right maxillary first molar. The patient was diagnosed with irreversible pulpitis, and subsequently, root canal treatment (RCT) was performed. In total, five root canals were found in the maxillary first molar, including two separate root canals in the palatal root. RCT was successfully performed using an endodontic microscope and cone-beam computed tomography (CBCT). The CBCT image revealed a vertucci type I canal morphology in the distobuccal root, while the MB and palatal root canals were type Ⅳ. At the 1-mo follow-up, the maxillary first molar was completely asymptomatic, and the X-ray results indicated a successful RCT. Finally, the ceramic crown restoration was performed.

CONCLUSION

An endodontic microscope and CBCT are useful in effectively identifying and treating root canal variations.

In Vitro Diagnostic Accuracy and Agreement of Dental Microscope and Cone-Beam Computed Tomography in Comparison with Microcomputed Tomography for Detection of the Second Mesiobuccal Canal of Maxillary First Molars

OBJECTIVES

The percentage of failure of endodontically treated maxillary molars is relatively high; one main reason is that the second mesiobuccal canal (MB2) is missing. Some techniques have been proposed for detection of the MB2. This study was aimed at assessing the diagnostic accuracy and agreement of the dental microscope and cone-beam computed tomography (CBCT) in comparison with microcomputed tomography (micro-CT) for detection of the MB2 of maxillary first molars in vitro.

MATERIALS AND METHODS

This in vitro, experimental study evaluated 71 permanent maxillary first molars that were stored in 100% humidity at room temperature. The teeth were mounted in 9 silicone dental arches to the level of their cementoenamel junction (8 teeth in each arch). The blocks underwent CBCT in a XG3D scanner. Access cavity was then prepared, and the teeth were inspected by a surgical microscope for negotiation of the MB2. Also, micro-CT images were obtained from the teeth to serve as the gold standard. CBCT and micro-CT images were observed by two examiners twice with a 2-week interval.

RESULTS

The frequency of the MB2 detected by dental microscope was significantly lower than micro-CT (P < 0.001) and CBCT (P = 0.008); no significant difference existed between micro-CT and CBCT in this respect. The sensitivity, specificity, positive predictive value, and negative predictive value of CBCT for detection of MB2 were 92.6%, 100%, 100%, and 81%, respectively.

CONCLUSION

CBCT is superior to the dental microscope for detection of the MB2 of maxillary first molars and can be used for this purpose in the clinical setting with adequate accuracy.

Association between second mesiobuccal canal and apical periodontitis in retrospective cone‐beam computed tomographic images

This retrospective cone-beam computed tomography study aimed to investigate the possible associations of apical periodontitis (AP) with missed/unmissed second mesiobuccal (MB2) canals. MB2 canals and AP were investigated in 257 endodontically treated and 673 untreated maxillary molars, and the former were analyzed regarding missed/unmissed MB2 canals. The chi-squared test and odds ratio (OR) were used for statistics. The prevalence of MB2 canals in maxillary first molars was higher than that in second molars (p = 0.001). MB2 canals were 1.751 times more common in males than in females (OR: 1.751; 95% CI: 1.334-2.297), with a significant difference in the 18-39 age groups (p = 0.005). The risk for AP was 5.5 times greater in endodontically treated maxillary molars with missed MB2 canals than in those with unmissed MB2 canals (p = 0.012) (OR: 5.5, 95% CI: 1.549-19.527). The findings of this study reveal that the likelihood of the MB2 canal is higher in the maxillary first molars of young adult males.

Validity of the dental operating microscope and selective dentin removal with ultrasonic tips for locating the second mesiobuccal canal (MB2) in maxillary first molars: An in vivo study

Background

Several investigations have determined whether the use of a dental operating microscope (DOM) in combination with selective dentine removal with ultrasonic tips increases the percentage of location of the Mesiobuccal 2 (MB2) root canal in maxillary first molars (MFM). However, these studies did not report the performance of in vivo measurements with the comparison with a gold standard. The aim of this study was to determine the validity of the DOM and selective dentin removal with ultrasonic tips to locate the MB2 root canal in MFM using Cone Beam Computed Tomography (CBCT) as the gold standard.

Material and Methods

The initial sample size was 91 patients, but 7 were excluded, so the sample size was 84 patients who signed the informed consent. Inclusion criteria: MFM indicated for root canal treatment. An expert blinded observer identified the MB2 in the CBCT. Two standardized examiners (Kappa=91%) performed the clinical assessment in three stages: Stage 1, canal location with an endodontic explorer and a mirror; Stage 2, use of DOM and Stage 3, use of DOM plus selective dentine removal with ultrasonic tips. The validity of each stage was calculated.

Results

The prevalence of MB2 using CBCT was 79%, by clinical location was 68%. Sensitivity was 79%, 82%, 86% for stage 1, 2 and 3, respectively. Specificity and Positive Predictive Values were 100% for all methods. Negative Predictive Value was 56%, 60%, 67%, respectively. Positive Likelihood Ratio tends to infinity for all methods, Negative Likelihood Ratio= 0.21, 0.18 and 0.14 and Accuracy= 83%, 86% and 89%, respectively.

Conclusions

The use of DOM with selective dentine removal with ultrasonic tips is the most valid method for locating MB2 canal in MFM. There was an increase in the location of the MB2 root canal with the DOM and ultrasonic tips, which definitely help the clinician. Key words:Cone beam computed tomography, microscopy, second mesiobuccal canal, sensitivity and specificity, validity.

Evaluation of the band-shaped isthmuses in the mesiobuccal root canal system using micro-computed tomography

OBJECTIVES

This micro-computed tomography (micro-CT) study analyzed band-shaped isthmuses having their floor at the apical third of the mesiobuccal roots of maxillary molars in terms of 2D and 3D morphological parameters.

MATERIALS AND METHODS

A total of 199 maxillary first molars were scanned with micro-CT. Twenty-seven specimens, confirmed to have a band-shaped isthmus, were further examined in terms of the isthmus length, volume, structure model index (SMI), and surface area. The distance of apical foramina of mesial canals from the isthmus floor and major-minor diameters, roundness, perimeter, and area of the isthmus roof and floor were compared. Statistical analyses were performed with descriptive statistics and t-test with a 5% significance threshold.

RESULTS

The band-shaped isthmus frequency was 13.5% and its length reached up to 5.5 mm. The distances of the apical foramina of mesiobuccal canals (MB1 and MB2) from the isthmus floor were similar (p > .05). Isthmus roof and floor showed significant differences in terms of their major diameter and area (p < .05), whereas their minor diameter, roundness, and perimeter values were similar (p > .05).

CONCLUSION

The band-shaped isthmuses are not rare and can reach through the half of the root length with oval cross-sections in the floor and roof anatomy. The distance between the isthmus floor and apical foramina did not differ between MB1 and MB2.

CLINICAL RELEVANCE

The band-shaped isthmus morphology contributes to the complexity of the apical anatomy of maxillary first molar teeth with various lengths and diameters.

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.

Anatomical Evaluation of Root and Root Canal Configuration of Permanent Maxillary Dentition in the Population of the Kingdom of Saudi Arabia

AIM

This study is aimed at combining the sample sizes of all studies on permanent maxillary teeth conducted in different regions of the Kingdom of Saudi Arabia (KSA) to obtain a large sample size that represents the population of the KSA. The outcome of these combined studies is compared with international studies in terms of the number of roots, number of canals, and canal configurations on the basis of Vertucci's classification. Methodology. The studies were systematically reviewed using the Preferred Reporting Items for Systematic Review and Meta-analysis chart. Studies were included in the analysis if they were conducted in the KSA, involved permanent human maxillary teeth, and had a sample of more than 10 teeth (power). By contrast, studies were excluded if they involved deciduous teeth in the sample size, investigated nonhuman teeth, were not conducted in the KSA, and were case reports, case series, review studies, and anomalies. Relevant literature was searched from PubMed, Scopus, Web of Science, Embase, Cochrane, and Direct Science by two calibrated teams, starting in August 2020, without time limits or language restrictions.

RESULTS

The database searches and cross-referencing identified a total of 19 relevant studies. All maxillary canines (N = 1,018) had one root, whereas 98.4% had one canal and 98.3% had Vertucci type I. Moreover, 63.2% of the maxillary first premolars had two roots, and 91.4% had two canals. The most common Vertucci root canal configuration was type IV (64.6%). The maxillary second premolars mostly had one root (84.4%) and one canal (50.4%). The most common canal configuration was Vertucci type I (47.1%). The majority of maxillary first molars had three roots (98.9%), 48.7% of which had three canals, and 46.4% had four canals. The most prevalent feature of the canal morphology of mesiobuccal roots was Vertucci type II (35.3%). The investigated maxillary second molars had three roots, 88.0% of which had three canals.

CONCLUSION

This systematic review represents the Saudi population since samples were combined from different studies from different regions of the country. Variations in findings were observed in the same group of teeth from different regions and the same region, while the overall combined samples results fell within the range of other international studies.

Worldwide Assessment of the Mandibular First Molar Second Distal Root and Root Canal: A Cross-sectional Study with Meta-analysis

INTRODUCTION

This study assessed the prevalence of radix entomolaris and 2 canals at the distal aspect of mandibular first molars among different geographic regions by means of cone-beam computed tomographic imaging.

METHODS

Precalibrated observers from 23 worldwide geographic locations followed a standardized screening protocol to assess 5750 cone-beam computed tomographic images of mandibular first molars (250 per region), gathering demographic data and recording the presence of radix entomolaris and a second canal at the distal aspect of teeth. Intra- and interrater reliability tests were conducted and comparisons among groups were performed using proportions and odds ratio forest plots. The significance level was set at 5%.

RESULTS

The results of intra- and interrater tests were above 0.79. The prevalence of radix entomolaris varied from 0.9% in Venezuela (95% confidence interval [CI], 0%-1.9%) to 22.4% in China (95% CI, 17.2%-27.6%). Regarding the proportion of a second distal canal, it ranged from 16.4% in Venezuela (95% CI, 11.8%-21.0%) to 60.0% in Egypt (95% CI, 53.9%-66.1%). The East Asia subgroup was associated with a significantly higher prevalence of an extra distolingual root, whereas the American subgroup, the American native ethnic group, and elderly patients were linked to significantly lower percentages of a second canal at the distal aspect of teeth. No significant differences were noted between male or female patients.

CONCLUSIONS

The overall worldwide prevalence rates of radix entomolaris and a second canal at the distal aspect of the mandibular first molar were 5.6% and 36.9%, respectively. The East Asia geographic region and Asian ethnic group had a higher prevalence of a second distal root.

Shaping ability of four single-file systems in the instrumentation of second mesiobuccal canals of three-dimensional printed maxillary first molars

Background

This study evaluated and compared the shaping ability of four advanced single-file nickel-titanium (NiTi) systems during the preparation of curved second mesiobuccal (MB2) canals in maxillary first molar replicas fabricated by three-dimensional (3D) printing via micro-computed tomography (Micro-CT) imaging.

Methods

A total of 60 3D-printed maxillary first molar replicas were constructed from one extracted tooth, with an angle of curvature ranging from 15° to 25°. The MB2 canals from these 60 replicas were divided into 4 groups of 15 replicas according to the canal instrumentation system used, namely, Waveone gold (WOG), Reciproc blue (RCB), XP-endo shaper (XPS) and M3-L. The specimens were scanned before and after preparation using Micro-CT. The pre- and post-instrumentation images of each specimen were superimposed, and the amount of resin removed, the change in surface area, the canal transportation, and centering ability were assessed using the Mimics software. Instrumentation time was also recorded. One-way analysis of variance and least significant difference (LSD) tests were used to statistically compare the groups. The significance level was set at 5%.

Results

Instrumentation time with M3-L was significantly longer than the other systems (P<0.05). The amount of resin removed and the change in surface area generated by the 4 systems were different at the apical, middle, and coronal thirds, and the total canal (P<0.05). Overall, WOG and XPS resulted in the less change than RCB and M3-L. There was no significant difference among the groups at the middle third regarding canal transportation and centering ability (P>0.05). However, a significant difference was found at the apical level (P<0.05), where RCB showed the poorest centering ability and the highest canal transportation (P<0.05). In addition, XPS resulted in the least canal transportation (P<0.05) at the coronal level, while there was no significant difference between the four groups in terms of centering ability.

Conclusions

The M3-L instrument required more time to prepare the curved MB2 canals compared with the other systems. Overall, WOG and XPS showed the least resin removal and surface area change. M3-L, XPS, and WOG instruments respected the original canal curvature better than RCB files.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The Scientific Investigation Committee of the American Academy of Restorative Dentistry offers this review of the 2020 professional literature in restorative dentistry to inform busy dentists regarding noteworthy scientific and clinical progress over the past year. Each member of the committee brings discipline-specific expertise to this work to cover this broad topic. Specific subject areas addressed include prosthodontics; periodontics, alveolar bone, and peri-implant tissues; implant dentistry; dental materials and therapeutics; occlusion and temporomandibular disorders (TMDs); sleep-related breathing disorders; oral medicine and oral and maxillofacial surgery; and dental caries and cariology. The authors focused their efforts on reporting information likely to influence day-to-day dental treatment decisions with a keen eye on future trends in the profession. With the tremendous volume of dentistry and related literature being published today, this review cannot possibly be comprehensive. The purpose is to update interested readers and provide important resource material for those interested in pursuing greater detail. It remains our intent to assist colleagues in navigating the extensive volume of important information being published annually. It is our hope that readers find this work useful in successfully managing the dental patients they encounter.

Evaluation of new endodontic tooth models in clinical education from the perspective of students and demonstrators

BACKGROUND

The quality of root canal treatments performed by undergraduate students is often unsatisfactory questioning the current methods of teaching. Based on treatment errors made by students participating the endodontic courses at RWTH Aachen University (Germany), new radiopaque artificial root canal treatment models (DRSK RCT; incisor, premolar, molar) were designed and developed. The aim of the study was to evaluate these models by groups of students and demonstrators.

METHODS

A total number of 60 students and seven demonstrators from a single institution (RWTH Aachen) participated in this study. They performed endodontic treatments on either initial versions of the DRSK RCT or modified versions. The initial versions were evaluated by students (n = 25) and demonstrators (n = 7). The obtained questionnaire was conducted as 7-point Likert-Scale covering the topics material properties, feeling while performing exercises and perception of its closeness to reality via 19 items (students) and 21 items (demonstrators). According to the evaluations several alterations were applied to the DRSK RCT, the whole study was repeated and evaluated by different students (n = 35) and the same demonstrators (n = 7). Additionally, the demonstrators blindly evaluated the quality of root canal treatments performed by the students (n = 35) on the modified DRSK RCT. Comparisons between the initial versions and the modified versions were calculated using Chi-squared tests.

RESULTS

Students as well as demonstrators positively evaluated both variants of the DRSK RCT with especially high ratings in the overall evaluation. Students' rating of the pulp anatomy significantly increased from 5.4 ± 1.1 (mean ± SD) to 5.9 ± 0.9 (mean ± SD; p < 0.05) for the modified model. Likewise, students felt that the ability to flare root canals improved after alterations have been applied. Ratings significantly increased from 4.8 ± 1.6 (mean ± SD) to 5.6 ± 1.0 (mean ± SD; p < 0.05).

CONCLUSION

The results indicate that the DRSK RCT is a promising candidate to be used as an alternative to extracted teeth or as an additional tool for improving dental education. However, some limitations of our analysis have to be considered.

Endodontic treatment of various palatal root in maxillary molars: Case series and clinical experience

BACKGROUND AND OVERVIEW

The purpose of this article is to present the variations in maxillary molar palatal root canals and provide a reference for the possible variations in root canal treatment.

CASE DESCRIPTION

Five rare cases with palatal canal variation presented in this case series received nonsurgical endodontic treatment successfully. These case reports highlight that understanding and managing the different types of canal configurations in palatal roots of maxillary molars is essential to successful root canal treatment. We tried 2 methods of examining the palatal canal variation to provide examples for clinicians in diagnosing and treating similar cases.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The outline form of the access cavity and the shape of the pulp chamber floor are important factors for identifying variations in root canal number. Moreover, cone-beam computed tomography can help in detecting variations in root canals.

Influence of Voxel Size and Filter Application in Detecting Second Mesiobuccal Canals in Cone-beam Computed Tomographic Images

INTRODUCTION

This study assessed the influence of voxel size and filter application in detecting second mesiobuccal (MB2) canals in cone-beam computed tomographic (CBCT) images.

METHODS

Using the OP300 CBCT system (Instrumentarium, Tuusula, Finland) and 3 voxel size protocols (80 μm, 125 μm, and 200 μm), we scanned 40 first molars: 20 with an MB2 canal and 20 without. All molars received silver palladium pins on the palatal root, whereas the non-MB2 molars were also filled with gutta-percha. Five oral radiologists assessed the presence of an MB2 canal under 3 filter application conditions: without filter, with sharpen 1 × filter, and with sharpen 2 × filter. Intra- and interobserver reproducibility was evaluated using the weighted kappa index. We compared the area under the receiver operating characteristic curves with SPSS Statistics v.20.0 (IBM Corp, Armonk, NY) using 2-way analysis of variance and the Tukey post hoc test with 5% significance level.

RESULTS

Our analysis found median intra- and interobserver agreement values of 0.70 and 0.56, respectively. The 80-μm voxel with sharpen 1 × filter image group had the highest sensitivity, accuracy, and negative predictive values. As for specificity and positive predictive, the 80-μm voxel group without filter application presented the highest values. The areas under the receiver operating characteristic curve were higher in the 80-μm groups than in the 125-μm and 200-μm voxel size groups (P < .05). We found no differences among the filters used (P = .22) or for the filter-voxel size interactions (P = .88).

CONCLUSIONS

A smaller voxel size increased the accuracy in detecting MB2 canals, whereas the enhancement filters did not.

Four-Rooted Maxillary First Molars: A Systematic Review and Meta-Analysis

Objectives

The majority of human maxillary first molars is usually described as having three roots, but different morphologies were documented in several studies and case reports. One very rare and less investigated anatomical anomaly is the occurrence of four radicular structures in the upper first molars. This communication aimed to define the prevalence of four-rooted maxillary first molars on a meta-analytical basis. The external and internal morphology of these teeth was described by the collection of published case reports.

Materials and Methods

Six electronic databases were accessed to collect case reports dealing with four-rooted maxillary first molars, as well as population-based cone-beam computed tomography (CBCT) studies. Afterward, the publications were selected according to predefined inclusion/exclusion criteria and evaluated using the Joanna Briggs Institute Critical Appraisal tool. The teeth of the chosen case reports were then independently analyzed by two dental professionals according to different dental classifications. Furthermore, the population studies were meta-analyzed to calculate the global and regional prevalence of four-rooted maxillary molars.

Results

Included were forty-nine population-based CBCT studies containing 26663 maxillary first molars. Upon these data, the global incidence of four-rooted maxillary molars was meta-analytically determined as 0.047% (95%-CI:0.011-0.103%). In combination with the case reports, it was pointed out that this anomaly is distributed worldwide. Furthermore, forty-eight case reports were included containing fifty-three maxillary molars with four roots. The analyzed teeth exhibited Versiani´s pulpal chamber floor Types A and B. The majority of four-rooted maxillary first molars were classified as Type I regarding Christie's configuration. But, also 7.54% of the altered teeth could not be described by this classification. 62.34% exhibited four root canals, but also variations with five, six, or seven canals were identified. Furthermore, a significant difference was found in the occurrence rate between male and female patients.

Conclusion

Due to the worldwide occurrence, dental professionals should be aware of this rare anomaly to avoid treatment errors, especially during endodontic or surgical therapies.

Mesiobuccal and Palatal Interorifice Distance May Predict the Presence of the Second Mesiobuccal Canal in Maxillary Second Molars with Fused Roots

INTRODUCTION

The aim of this study was to evaluate if the configuration of canal orifices can predict the presence of a second mesiobuccal canal (MB2) in maxillary second molars with fused roots.

METHODS

Maxillary second molars with fused roots (N = 150) were scanned in a micro-computed tomographic device (pixel size = 9 μm) and evaluated regarding the root fusion type and the incidence of the MB2 canal. The centers of the canal orifices were connected, and the angles formed by the intersection of these lines as well as their distances were measured and statistically compared (1-way analysis of variance). Specimens were then assigned to 2 groups according to the presence (n = 65) or absence (n = 50) of the MB2 canal and compared regarding the angles and interorifice distances using the Welch t test. A binary logistic regression model estimated the association between the interorifice distance, the fusion type, and the presence of the MB2 canal, whereas receiver operating characteristic curve analysis was performed to evaluate the diagnostic abilities of significant variables. The significance level was set at 5%.

RESULTS

The most common fusion types were 1 and 6, and MB2 canal incidence was 47.3%. No statistical difference was observed in the angles or interorifice distances among teeth with different fusion types (P > .05). Distances from the mesiobuccal (MB) to the distobuccal and palatal (P) canal orifices as well as the MB and P angles were significantly higher in the presence of an MB2 canal (P < .05). A binary logistic regression model revealed that MB-distobuccal and MB-P distances were significant in the presence of an MB2 canal (P < .05). Receiver operating characteristic analysis indicated that MB-P distance had acceptable diagnostic accuracy for the prediction of MB2 canal presence. Sensitivity (specificity) calculated from the MB-P distances of 4.0, 4.5, and 5.0 mm were 89.2% (36.5%), 76.9% (58.4%), and 44.4% (71.4%), respectively.

CONCLUSIONS

MB-P interorifice distance is a strong predictor of the presence of the MB2 canal in maxillary second molars with fused roots.

Comparison of Dentinal Wall Thickness in the Furcation Area (Danger Zone) in the First and Second Mesiobuccal Canals in the Maxillary First and Second Molars Using Cone-Beam Computed Tomography

Objective:

Differences in the morphology of the root canal system might result in favorable or adverse treatment outcomes. The present study compared the thickness of the dentinal wall in the danger zone (furcation area) of the first and second mesiobuccal canals in the maxillary first and second molars using cone beam computed tomography.

Methods:

In this cross-sectional study, 50 CBCT images of maxillary first and second molars were evaluated from one of the specialized radiology centers in Kerman, Iran. The images were prepared by a Planmeca Promax 3D Max machine (Planmeca, Helsinki, Finland), with a field of view (FOV) of 8×8 cm and a resolution of 0.1 mm and analyzed with Romexis Viewer software version 3.1.1 (Planmeca, Helsinki, Finland). In the 0.1-mm-thick axial cross-sections with a distance of 1 mm, the distances from the center of the MB1 and MB2 root canals to the furcation area were measured in three areas: A) furcation area, B) 2 mm below the furcation area, and C) 4 mm below the furcation area (at a magnification of ×10). The data were then analyzed with paired t-test.

Results:

The thickness of the dentinal wall in the MB2 root canal was significantly less than that in the MB1 root canal in all the specimens (P<0.05). In both maxillary first and second molars, the thicknesses of the MB1 and MB2 root canals were significantly different in the furcation area and 4 mm below the furcation area (P=0.001). There was no significant difference between the maxillary first and second molars 2 mm below the furcation area; however, the difference was marginal (P=0.07).

Conclusion:

Considering the low thickness of the dentinal wall in the MB2 root canal compared with the MB1 root canal in the maxillary first and second molars, the anti-curvature techniques away from the furcation should be used to prepare this root canal to reduce the risk of strip perforation. On the other hand, it might indicate that highly tapered instruments and other aggressive instruments, such as Gates-Glidden drills, should be used with caution in these root canals.

The frequency of the second mesiobuccal canal in maxillary first molars among a sample of the Kurdistan Region-Iraq population - A retrospective cone-beam computed tomography evaluation

Background/purpose

One of the most complexes in root and canal anatomy is the maxillary first permanent molar. This study aimed to analyze the frequency of mesiobuccal (MB2) canal and its apical portals of exit, in patients belonging to different gender-age groups and determine the possible relation with sex and age.

Materials and methods

A CBCT scan images were accessed from a documented database of 343 patients (178 male, 165 female), who had an oral and maxillofacial examination. The age of the patients ranging from 12 to 63 years. The frequency of the MB2 canal and its portals of exit apically were observed. Age and gender correlation were calculated using the χ2 test. P < 0.05 was considered significant.

Results

A total of 634 maxillary first molars (335 male, 299 female) were included. The MB2 canal was found in 53.78% of the cases. A significantly higher incidence of the MB2 canal was detected in males than in females. No correlation in the presence and/or absence of the MB2 canal in terms of age. When MB2 canal present, a single apical foramen was observed in 66.28% of the cases, two apical foramina were present in 33.72% of the cases.

Conclusion

MB2 canals may be present in approximately half of the cases, from which one third of the cases have their own apical portal of exit.

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.