Distolingual Root Research Articles

Investigation of the furcation morphology of permanent mandibular first molars by using micro-computed tomography

BackgroundTo investigate the anatomic features of the root furcation of permanent mandibular first molars.MethodsA total of 50 extracted mandibular first molars (25 two-rooted and 25 three-rooted) were collected and scanned using micro-computed tomography. The digital models of teeth and root canal systems were reconstructed three-dimensionally. The tooth models were displayed in parallel projection mode from buccal and distal views. Screenshots were captured and subsequently analyzed using Image-Pro Plus 6.0 software after calibration. The furcation angle, root trunk length, maximum depth and level of distal root concaves of mesial roots, and length of enamel projections were measured, and the furcation types (classified into type V, type U and type W) were detected. Statistical analysis was performed using the Shapiro-Wilk’s test, one-way analysis of variance, Student’s t-test and Chi-square test.ResultsThe mean furcation angle between the distobuccal (DB) and distolingual (DL) roots (in distal view) was the greatest (59.2°), whereas the furcation angle between the mesial and DL roots (in buccal view) was the smallest (25.4°) among the four furcation angles (all p < 0.05). Regarding the furcation types, bucco-lingual root trunk length, maximum depth and site of the distal root concavities, and enamel projection length, no significant differences were detected between the three- and two-rooted molar groups (all p > 0.05). The frequency of type V was the highest (54.0%), followed by type U (26.0%), and type W had the lowest occurrence rate (20.0%). The mean length of distal root trunk in the three-rooted mandibular molars was significantly greater than that of the buccal/lingual one (3.7 mm vs. 3.0 mm, p < 0.01). The maximum depth of the distal concavities of the mesial roots was on average 0.66 ± 0.19 mm, and the site was located at an average of 2.8 ± 1.3 mm below furcation. The mean length of buccal enamel projections was significantly longer than that of lingual ones (3.1 mm vs. 0.7 mm, p < 0.01).ConclusionsThe furcation anatomy of the mandibular first molar is complex, and the presence of the DL root may further complicate its topography. A thorough understanding of these anatomic features is essential for successful periodontal treatment.

CBCT Analysis of Radix Entomolaris: Anatomical and Endodontic Implication

This paper aims to provide examples of mandibular first molars that have an extra distolingual root and discuss how to manage them with the right tools and methods. Mandibular molars occasionally exhibit radix entomolaris, a variant in which the tooth has an additional root fixed to its lingual aspect. If this extra root is misdiagnosed or treated improperly, it could make endodontic management of the tooth more difficult. Thus, Understanding the variances in tooth/canal architecture and distinguishing traits is essential since it can help with canal location, negotiation, and management. Mandibular molars with this root shape have a different prognosis depending on the precise diagnosis and appropriate use of clinical endodontic competence.

Comprehensive Analysis of Mandibular First Molar Root and Canal Morphology in Saudi Patients Using Cone Beam Computed Tomography (CBCT).

BACKGROUND The goal of conventional endodontic therapy is to clean the root canal system thoroughly, restore tooth function, and prevent re-infection. Success depends on understanding root canal morphology, resolving apical periodontitis, and using proper techniques. Studies highlight variations in root canal anatomy, with cone-beam computed tomography (CBCT) being crucial for accurate diagnosis despite its high cost and limited availability. MATERIAL AND METHODS This retrospective study reviewed CBCT images of 1820 (907 male, 913 female) patients aged 18 to 78 years. Analysis included 2081 mandibular first molars for variations in root and canal morphology and right- and left-side symmetry. Inter-orifice distance was measured, along with distance from the cementoenamel junction (CEJ) to the level of canal bifurcation. RESULTS In this study, 96.01% of teeth had 2 roots and 3.89% had 3 roots. The percentages of canal configuration were 77.70% for 3 canals, 21.58% for 4 canals, 0.67% for 2 canals, and 0.05% for 1 canal. The inter-orifice distance was 2.07 mm for 2 canals in 1 root and 2.86 mm for 2 canals in separate distal roots. Distance from the CEJ to canal bifurcation varied significantly between 2 canals within 1 distal root (3.35 mm), 2 canals in separate distal roots (1.60 mm), as well as between distal (3.35 mm) and mesial roots (1.10 mm). CONCLUSIONS In mandibular first molars, only 3.89% have additional distolingual roots. Sex and ethnicity showed no influence on number of roots and canals. Distal canals showed a deeper bifurcation and greater inter-orifice distance than did mesial canals.

Clinical relevance of distolingual roots and periodontal status in mandibular first molars: a cross-sectional study employing CBCT analysis.

OBJECTIVES: Distolingual root of the permanent mandibular first molar (PMFM-DLR) has been frequently reported, which may complicate the treatment of periodontitis. This study aimed to assess the morphological features of PMFM-DLR and investigate the correlation between the morphological features of PMFM-DLR and periodontal status in patients with Eastern Chinese ethnic background. MATERIALS AND METHODS: A total of 836 cone beam computed tomography (CBCT) images with 1497 mandibular first molars were analyzed to observe the prevalence of PMFM-DLR at the patients and tooth levels in Eastern China. Among them, complete periodontal charts were available for 69 Chinese patients with 103 teeth. Correlation and regression analyses were used to evaluate the correlation between the morphological features of DLR, bone loss, and periodontal clinical parameters, including clinical attachment loss (CAL), probing pocket depth (PPD), gingival recession (GR), and furcation involvement (FI). RESULTS: The patient-level prevalence and tooth-level prevalence of DLR in mandibular first molars were 29.4% and 26.3%, respectively. Multiple linear regression analysis suggested that bone loss at the lingual site and CAL were negatively affected by the angle of separation between distolingual and mesial roots in the transverse section, while they were significantly influenced by age and the angle of separation between distobuccal and mesial roots in the coronal section. CONCLUSIONS: The prevalence of PMFM-DLR in Eastern China was relatively high in our cohort. The morphological features of DLR were correlated with the periodontal status of mandibular first molars. This study provides critical information on the morphological features of DLR for improved diagnosis and treatment options of mandibular molars with DLR.

Distolingual root prevalence in mandibular first molar and complex root canal morphology in incisors: a CBCT analysis in Indian population

Cone-beam computed tomography was used to understand the possible correlation between the prevalence of distolingual root (DLR) in permanent mandibular first molars (MFMs) and the associated complicated mandibular incisor’s root canal morphology (MIs) in an Indian population. A total of 400 scans were evaluated for MFMs and MIs. The prevalence of DLRs and root canal anatomy of MIs were assessed based on Vertucci’s classification, and then the sample were grouped according to age, sex and side. Statistical analysis was used to evaluate the possible correlation between the presence of DLRs in the first molar and root canal morphology of incisors. Chi square test was used to evaluate the correlation between the root canal configurations of MIs with the existence of DLRs in MFMs. There was no statistically significant difference between sexes or ages for the prevalence of DLRs in the first molars (p > 0.05), which was 6.62%, with the right side having a greater frequency of DLRs (7.8%) than the left (5.5%). Vertucci Type I canal configuration was most common for the mandibular central (66.75%) and lateral incisors (58.62%). Vertucci Type III was the most common complicated canal morphology, followed by Types V, II, and IV for MIs, with no statistically significant difference in the studied sample's age and sex. (p < 0.05). No association was observed between the presence of DLRs in first molars and complicated root canal configurations in MIs. Taken together, the possibility of complicated root canal configuration in MIs was lesser in the presence of DLRs in MFMs among the Indian population.

A New Methodology to Determine the Orifice for Root Canal Configurations in First Permanent Molar Root and Canal Morphologies Using Micro-Computed Tomography.

The distinction between where the pulp chamber ends and the root canal system begins is poorly defined within the existing literature. This paper aimed to describe a range of accurate methods to define the transition from pulp chamber to root canal in different first molar root morphologies using micro-focus computed tomography (micro-CT). The sample consisted of 86 mandibular and 101 maxillary first molars from the skeletal collections housed in the Department of Anatomy and Histology of the Sefako Makgatho Health Sciences University and the Pretoria Bone Collection. A stepwise approach using the cemento-enamel junction (CEJ) and dedicated landmarks was followed to create an automated cross-sectional slice. Transition from pulp chamber to root canal could be accurately determined on maxillary and mandibular teeth. The occurrence of two separate roots in mandibular molars was 97.7%, with the remaining 2.3% having an additional disto-lingual root, with no mandibular molars displaying fused roots. In the maxillary molars, 92.1% had three separate roots and 7.9% displayed root fusion. Within this group, one tooth displayed a C-shaped root canal configuration and one a mesotaurodont-type morphology. The suggested methodology to determine orifice location was found to be appropriate in all morphological types.

Investigation of Morphological Variations of Canal and Root of First Mandibular Molar in Tomographic Images Computer with Cone Beam in Patients of Arak City

Introduction: Being the first teeth to erupt, first molars have the most complex root system and canal morphology and are among the most susceptible teeth to decay and destruction. The aim of this study is to determine the frequency of morphological variations of the canal and root of the mandibular first molar in cbct images so that appropriate treatment can be performed with a better understanding of the anatomy of the root and canal of the molar tooth.Materials &amp; Methods: In this descriptive cross-sectional study, the morphological variation of the mandibular first molar canal and root was investigated in 170 cbct radiology image samples. In this study, the age and gender of the individual, the number of roots and canals of the mandibular first molar, the morphology of the canal in each root, the presence of the midmesial canal and the presence of the distolingual root were also investigated. In the end, frequency and percentage indicators were used to analyze data and chi-square test was used to compare frequencies.Results: The average age of the subjects studied was 39.2 years. The subjects included 86 women and 84 men. The most seen sample was a molar tooth with two roots and three canals. In terms of canal morphology in the mesial root, the most common canal morphology was type 4 and then type 2. In terms of canal morphology in the distal root, the most common canal morphology was type 1. In the studied samples, midmesial canal was not found in 99.4% of cases and distolingual root was not found in 94.7% of cases.Conclusion: Two-rooted and three-channel molar without midmesial canal and without distolingual root was the most common case found in this study. The most common canal morphology in the mesial root was type 4 and the most common canal morphology in the distal root was type 1.

The Extra Root Story–Radix Entomolaris: A Case Report

Root canal anatomy is considered highly unpredictable and complex. For a dental practice to be successful comprehending the external and internal anatomy of the tooth is crucial. Mandibular first molars are susceptible to anatomical abnormalities just like any other teeth. Extra root distolingually is one such anatomical variant. The term for this distolingual root is radix entomolaris RE. Endodontic treatment may be complicated by an additional root. Thus it is important to identify such anatomical variations for efficient endodontic management. This case report covered the treatment of a radix entomolaris case along with further details on the conditions etiology morphology incidence and prevalence.

Overview, Scouting and Treatment of Mesio-buccal Root Second Canal (MB2) of Maxillary Molar, Disto-lingual Root Canal (DL) and Middle Mesial Root Canal (MM) of Mandibular Molar

Overview, Scouting and Treatment of Mesio-buccal Root Second Canal (MB2) of Maxillary Molar, Disto-lingual Root Canal (DL) and Middle Mesial Root Canal (MM) of Mandibular Molar

CBCT Imaging of a Rare Case of Radix Entomolaris in Mandibular Second Molar

The presence of an additional supernumerary distolingual root in the mandibular molar is termed Radix Entomolaris (RE). It is common in the mandibular first molar, but its occurrence in the mandibular second molar is scarcely reported in the literature. Two-dimensional imaging can diagnose anatomical root canal variations when taken with different horizontal angulations. With the recent innovations in three-dimensional diagnostic imaging, cone beam computed tomography (CBCT) can aid in unfolding the complexities of the root canal system. Accurate diagnosis by CBCT leads to the success of endodontic treatment. A rare case of radix entomolaris in the mandibular second molar in an Indian female is reported here with three of its CBCT findings. Imaging in all three dimensions, oblique sections and volume rendering by CBCT proved to be of additional help to understand the complex anatomy and root canal morphology of the tooth.

Dilacerated distolingual root of mandibular first molar mimicking cementoblastoma: case report by radiographic findings

Objectives: This case report aimed to report an extra root number of mandibular first molars that are mimicking benign cementoblastoma in the periapical radiograph and clarified using cone beam computed tomography (CBCT) examination.&#x0D; Case Report: A 22-year-old female patient was referred from private clinic to Radiology Department of Universitas Padjadjaran Dental Hospital for a CBCT examination of the left mandibular first molar with benign cementoblastoma as the provisional diagnosis.&#x0D; Conclusion: It is necessary to consider CBCT examination in order to obtain accurate diagnosis of the presence of distolingual root.

Anatomical variations and bilateral symmetry of roots and root canal systems of mandibular first permanent molars in a Saudi Arabian population utilizing cone beam computed tomography

<h3>Objective</h3> To evaluate the anatomical variations of the roots and root canal systems and to determine the symmetry between right and left mandibular first permanent molars in a Saudi Arabian population using images derived from cone beam computed tomography (CBCT) scans. <h3>Methods</h3> CBCT scans (with exposure parameters 90 kVp, 5–8 mA, 17.5 s exposure time, and 0.25 mm voxel size with a 170 × 120 mm FOV) were retrieved from the database and axial, coronal, and sagittal sections of the mandibular first molars were examined. The number of roots, number of canals, and type of canal configuration based on Vertucci's classification were recorded. Bilateral symmetry between right and left sides of the same individuals and differences between genders were investigated. <h3>Results</h3> Out of 174 mandibular first molars, 97.1% were two rooted and 2.9% were three rooted (with a distolingual root). In regards to the number of canals, 73% had three, 25.3% had four and 1.7% had two root canals. In teeth with four root canals, 90.9% of the extra canals were in the distal root, while 9.1% were in the extra distolingual root. The most common canal configurations in the mesial and distal roots were type IV (64.9%) and type I (77%), respectively. Symmetrical analysis revealed 100% symmetry in number of roots and 56.4% in number of canals between right and left teeth in the same individual. <h3>Conclusion</h3> An extra root was seen in few cases of mandibular first molars of the studied population. A wide range of canal configurations was noted, with high prevalence of type IV in the mesial root and type I in the distal root. No associations between gender and root anatomy and canal morphology were discovered. Although high bilateral symmetry was found in numbers of roots, it varied with regards to numbers of canals and canal configurations in the same individuals. <b>Statement of Ethical Review</b> Human/Animal subjects were used and this study was approved by an institutional ethics panel

Investigation of three-rooted deciduous mandibular second molars in a Chinese population using cone-beam computed tomography

BackgroundTo investigate the anatomic features of three-rooted deciduous mandibular second molars (DMSMs) in Chinese children by using cone-beam computed tomography (CBCT).MethodsA total of 247 CBCT scans of Chinese children were selected and retrospectively analyzed. The occurrence, gender and side predilection of three-rooted DMSMs were examined. The pattern of concurrence of bilateral three-rooted DMSMs, and concurrence of three-rooted DMSM and three-rooted permanent mandibular first molar (PMFM) was analyzed by the concurrence rate and Spearman’s rank correlation test. The geometric parameters of the disto-buccal (DB) and disto-lingual (DL) roots, including the vertical root length, level and angle of distal root furcation, angle of root curvature (by Schneider technique) and the spreading angle, were measured and compared to the three-rooted PMFMs (n = 42) from 100 randomly selected adult subjects.ResultsThe occurrence of three-rooted DMSMs was 24.0% (54/225) calculated by individual, and 18.6% (88/472) by tooth. A significant right-side predilection was detected (23.0% vs 14.2%, p < 0.05), while gender predilection was not detected (p > 0.05). The bilateral concurrence rate was 49.0%, and Spearman’s correlation test indicated a significant relationship between the antimetric teeth (rho = 0.609, p < 0.01); whereas a weak but significant co-relationship was detected between the three-rooted DMSM and three-rooted PMFM (right side: concurrence rate = 31.6%, rho = 0.325, p < 0.01; left side: concurrence rate = 23.0%, rho = 0.260, p < 0.01). The length of DL roots in the DMSMs was 7.4 ± 1.5 mm, and the curvature angle was 16.4 ± 11.3 degrees, which was significantly (both p < 0.01) lower than that of the three-rooted PMFMs (root length = 11.0 ± 1.3 mm; degrees of curvature = 34.2 ± 16.1 degrees), whereas the spreading angle of the DL root in DMSMs (34.6 ± 8.4 degrees) was significantly (p < 0.01) greater than in the PMFMs (26.8 ± 6.5 degrees).ConclusionsThree-rooted DMSMs have a high occurrence rate in the Chinese children with a right-side predilection, and they have a weak but statistically significant correlation with three-rooted PMFMs. The DL roots of DMSMs are shorter, less curved, and spreading more widely as compared with those in the three-rooted PMFMs.

Mandibular incisors with two canals are associated with the presence of the distolingual root in mandibular first molars: a cone-beam computed tomographic study

BackgroundThis study aimed to evaluate the root canal configurations and the association between mandibular first molars and distolingual root (DLR) and mandibular incisors using cone-beam computed tomography (CBCT).MethodsMandibular first molars and incisors were evaluated using CBCT images of 150 patients. Mandibular first molars were classified according to the presence or absence of DLR. The curvature of the DLR was evaluated using Schneider’s method in buccolingual and mesiodistal orientations. The angle of the mesiolingual–distolingual–distobuccal canal orifices (ML–DL–DB) was evaluated at the pulpal floor level. The mandibular central and lateral incisors were classified as either single canal or two canals. The association between the root canal system of the mandibular first molar and mandibular incisors was evaluated. Data were analyzed using the Chi-square test, Student’s t-test, and odds ratios from binary logistic regression. The significance level was set at 5%.ResultsThe frequency of mandibular first molars with DLR was 27.0% and that of mandibular incisors with two canals was 25.8%. The curvature of the DLR was 37.1° in the buccolingual orientation and 10.4° in the mesiodistal orientation. The angle of ML–DL–DB was 79.0°. The presence of two canal systems in mandibular incisors was associated with the presence of DLR in the mandibular first molar (left central incisors: p = 0.001, odds ratio = 4.25; left lateral incisors: p < 0.001, odds ratio = 3.8; right central incisors: p = 0.003, odds ratio = 3.86; right lateral incisors: p = 0.001, odds ratio = 3.44) but not with the curvature of the DLR or angle of the ML–DL–DB orifice (p > 0.05).ConclusionsThe mandibular first molar showed a high incidence of separate DLRs. It was confirmed that DLR in the mandibular first molar is highly associated with the presence of two-canal system in the mandibular incisors. This association can aid clinicians in successful endodontic treatments.

Vertucci\u2019s root canal configuration of 11,376 mandibular anteriors and its relationship with distolingual roots in mandibular first molars in a Cantonese population: a cone-beam computed tomography study

BackgroundCone-beam computed tomography (CBCT) was used to study the root canal system of mandibular anteriors (MAs) in a Cantonese population and to evaluate the correlation between the complicated root canal configurations of mandibular lateral incisors (MLIs) and the presence of distolingual roots (DLRs) in mandibular first molars (MFMs).MethodsA total of 11,376 mandibular anterior teeth were scanned by CBCT. Those whose images met the inclusion criteria were first analysed according to Vertucci's root canal configuration and then grouped based on gender, age, and side, and their effects on root canal morphology were analysed. Finally, statistical analysis was used to evaluate the correlation between the complicated root canal configurations of MLIs and the existence of DLRs in MFMs. All statistical analyses were performed by using SPSS 25.0 software. Quantitative data are presented as the mean ± standard deviation. Student’s t tests were used to calculate statistical significance. P < 0.05 was considered statistically significant.ResultsIn MAs in the Cantonese population, all mandibular central incisors (MCIs) and MLIs had one root, and 0.37% of mandibular canines (MCs) had two roots. The most common Vertucci's root canal configuration was Vertucci I followed by Vertucci III. A total of 30.91% of MLIs and approximately 8% of MCIs and MCs have complicated root canal configurations. There were no significant differences in the prevalence of DLRs in MFMs and the incidence of complicated root canal configurations of MLIs between males and females or between the right and left teeth. However, a significant difference was found in different age groups of root canal configurations in MLIs. Moreover, significant ipsilateral and contralateral correlations between MFMs with DLRs and MLIs with complicated root canal configurations were observed on both sides.ConclusionIn Cantonese population, the possibility of complicated root canal configuration in MLIs was higher, when DLR appeared in MFMs.

Correlations between additional roots in maxillary second molars, maxillary first premolars, mandibular first molars and mandibular first premolars: a retrospective cone-beam computed tomography analysis.

This study aimed to determine the prevalence of additional roots in maxillary second molar (MSM), maxillary first premolar (MxFP), mandibular first molar (MnFM) and mandibular first premolar (MnFP) teeth and evaluate the correlations between the number of roots for these teeth. Images of 630 Turkish patients, in which all dental groups examined in the study were present bilaterally, were analyzed using cone-beam computed tomography. The images for the presence of the fourth root in MSMs, third root in MxFPs, distolingual root in MnFMs and complicated-root structure in MnFPs were assessed and divided additional roots into subgroups. The Chi-square test was used for categorical variables such as sex and tooth position. Logistic regression analysis was performed to understand the predictor variability of other teeth in teeth with extra roots. A p < 0.05 was considered statistically significant. Prevalence of the fourth root in MSMs was 1.75%, third root in MxFPs was 6.35%, third root in MnFMs was 3.57%, and complicated root in MnFPs was 21.9%. Positive correlations were observed between MSM, MxFP and MnFP teeth for increasing root numbers (P < 0.05). There was no significant correlation between root numbers of MnFM teeth and other tooth groups (P > 0.05) In the tooth groups examined, there was at least one explanatory variable (except for the right MnFM) tooth in addition to the contralateral tooth for the presence of additional roots.

MANAGEMENT OF RADIX ENTOMOLARIS WITH THE MIDDLE MESIAL CANAL – A CASE REPORT

Mandibular rst molars are frequently encountered with variations in their internal anatomy; among those is the presence of an extra canal in the mesial root called the middle mesial canal, and the presence of an additional distolingual root known as the radix entomolaris. The proper application of the magnication, such as the microscopes, loupes, and cone-beam computed tomography (CBCT), together with the usage of heattreated exible NiTi les augments the accomplishment in the endodontics while dealing with such rare cases. This case report describes the management of the mandibular rst molar with unusual morphology having Radix entomolaris along with the middle mesial canal in a 32 years old female patient. The treatment approach included root canal treatment without the assistance of any magnication devices.

Frequency of Multiple Canals in Mandibular Premolars and its Correlation with Other Anatomical Variants (C Shaped Canals in Mandibular Second Molars): A Retrospective and Cross-sectional Study

Introduction: Recognition of variations in molar root morphology is critically important for dental procedures such as root canal treatment and apical surgery. Usage of CBCT enables systemic evaluation of teeth including the number of roots and canals, location of roots, etc. The aim of this study was to determine the frequency of multiple canals in mandibular first and second premolars and to evaluate correlations between other anatomical variants using Cone beam computed tomography (CBCT).&#x0D; Methodology: The protocol of this retrospective, cross-sectional study was approved by the Ethics Committee of Saveetha Dental Hospital, Chennai, India. Images of mandibular premolars were obtained from patients who had undergone CBCT scanning at the hospital between January 2018 and November 2020.Cross-sectional images in the axial, coronal, and sagittal planes were reconstructed using GALILEOS ComfortPLUS ( Sirona 3D)is an advanced CBCT that provides seamless workflow integration. Serial axial, coronal and sagittal-plane CBCT images were closely examined at 1.0-mm intervals from the canal orifice to the apex.&#x0D; Results: Using SPSS software (ver. 21; SPSS, Inc., Chicago, IL, USA), chi-squared test was performed for analyses of different parameters involved. Various anatomical variants such as distolingual roots of first molars, C shaped canals of second molars are highly correlated with different canal configurations of mandibular premolars.&#x0D; Conclusion: This retrospective study showed that different configurations of mandibular premolars canals was significantly correlated with the presence of Distolingual root (DLRs) in first molars, and C shaped canals in second molars. Understanding and identifying anatomical variants is important in comprehensive success of endodontic treatment.

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

IntroductionThis 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. MethodsPrecalibrated 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%. ResultsThe 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. ConclusionsThe 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.

Geometric Analysis of the Distolingual Root and Canal in Mandibular First Molars: A Micro–computed Tomographic Study

IntroductionThe purpose of this study was to comprehensively assess by micro–computed tomographic imaging the anatomic features of distolingual (DL) roots and canals in mandibular first molars collected from 1 population. MethodsOne hundred two specimens were examined for the location and initial direction of the DL canal and the relationship between the distance of apical deviation and the angle of root curvature. ResultsAll DL roots had only 1 canal. A new 7-category classification system is proposed for the DL roots of mandibular first molars. Most DL roots were type IV (28 teeth), type III (26 teeth), and type V (25 teeth). The average canal curvature in all root types was over 25°. There was a positive correlation between the angles of root and canal curvature for types II, IV, and V (P < .05) but not for types I and III (P > .05). In the buccolingual view, most DL roots were straight, whereas in the mesiodistal view the root curvature was close to the maximum value. The orifice of the DL canal was 4 times further from the line that bisects a line between the mesiobuccal and mesiolingual canal orifices than the distobuccal canal. The angle between the mesiobuccal-mesiolingual line and the horizontal projection of the coronal third of the DL canal on the pulp floor was 8.1° ± 10.0° and 6.1° ± 8.2° for teeth from the left and right side, respectively. The angle between the inserted simulated file and the cementoenamel junction was 57.9° ± 6.3°. Seventy-three percent of the DL canals had no constriction in the apical area. The DL canals were narrow and had a conical frustum-like shape with a 0.04 taper at the apical portion. ConclusionsThe novel classification of the DL roots helps to better understand the clinically challenging anatomy of the root and canal.