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Objective To investigate and analyze the root and root canal morphology of mandibular first molars (MFMs) in the Tibetan population using cone-beam computed tomography (CBCT) and to provide references for clinical root canal treatment in the Tibetan population. Methods This study was reviewed and approved by the Ethics Committee, and informed consent was obtained from the patients. CBCT imaging data of 300 mandibular first molars from 300 Tibetan patients were included. Patient age, the number of roots in mandibular first molars were recorded. The morphology and incidence of mesial root and mesial root canals and the morphology and incidence of distal root and distal root canals were statistically analyzed by Vertucci classification. Results There were 198 double-root teeth and 102 three-root teeth in the 300 mandibular first permanent molars. Among the three-rooted molars, 1 case had mesiolingual roots, and the rest had distolingual roots. The incidence rate of the distolingual root was 33.7%(101/300). The most common root canal configuration was Vertucci Ⅳ 65.7% (197/300), followed by Vertucci Ⅱ 20.3% (61/300) in the mesial roots. The overall incidence of middle mesial canals (MMCs) was 6% (18/300), with the highest incidence of MMCs in the 20-40 year-old group at 9% (9/100). The distal roots canals of single-distal-rooted mandibular first molars were mainly Vertucci Ⅰ 66.8% (133/199), followed by Vertucci Ⅱ 14.6% (29/199) and Vertucci Ⅳ 11.6% (23/199). For the mandibular first permanent molars with two distal roots, 96% (97/101) of the distal buccal roots and 100% (101/101) of the distal lingual roots were Vertucci Ⅰ root canals. Conclusion The root and root canal morphology of mandibular first permanent molars in a Tibetan population is complex and variable. Approximately one-third of patients have distolingual roots, and clinicians should carefully explore the root canals under the guidance of CBCT.

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Objective: In recent years attention has been given to the presence of the middle mesial canal (MMC) in mandibular molars. This attention has caused a proliferation of case reports and even some systematic reviews. However, little attention has been paid to the actual presence of a 'separate canal', as opposed to the presence of an anastomosis that is patent or partially calcified that allows the penetration of an instrument. Furthermore, due to the complexity of this anatomical entity, even less has been addressed regarding the thorough management of this challenge and its potential impact on procedural outcomes. The aim of this review was to address the latter issues in an attempt to clarify and provide clinical directives. Materials and methods: Case reports and series published on MMCs were included and relevant data was extracted. They were analysed and interpreted to address the aim of the review. Other pertinent published data regarding true MMCs versus anastomoses were also reviewed. Results: Published case reports and series were majorly on true MMCs. However, evidence showed that the majority of MMCs were anastomoses. The clinical importance of managing anastomoses is emphasised. This paper also identifies areas that require more research and evidence regarding the management of MMCs. [ABSTRACT FROM AUTHOR]

The primary objective of endodontic therapy is to achieve a three-dimensional obturation of the root canal space after adequate preparation of the canal space to remove the tissue debris, microorganisms, and their byproducts. Anatomical variations have frequently been encountered in endodontic practice and have to be adequately managed by the clinician. Missed roots and canals are a major reason for failure of therapy. Technological advances have given the clinician ample opportunity to identify and treat these aberrations successfully. The present report describes a left mandibular second permanent molar requiring root canal treatment, found to have three separate canals in the mesial root. This case demonstrates a rare anatomical configuration and emphasizes the need for the clinician to be aware of and look out for such variations and use adequate diagnostic methodologies prior to and during therapy to detect such variations. The possibility of additional canals, whenever in doubt, should be explored with the assistance of technologies such as those of magnification and illumination and various diagnostic aids. Operator experience has also shown to be a key factor in negotiation and management of these aberrant canal configurations.

Introduction The objective of the present study was to measure the orifice depth of middle mesial canals (MMCs) and evaluate the detectability of orifices using troughing preparation. Methods For this study, 85 mandibular molar teeth with MMCs were selected from the scanned micro–computed tomographic images. The MMCs were categorized, and the distances between the MMC orifices and the cementoenamel junctions (CEJ) were recorded as the depth of the orifice. Data were evaluated with frequency analysis and a chi-square test using SPSS (SPSS Inc, Chicago, IL), and the results indicated a 5% significance level. Results It was found that 77.41% of the MMC orifices were at the CEJ level, whereas 5.38% and 9.69% of the MMC orifices were detectable within 1-mm and 2-mm depths from the CEJ, respectively. Of the specimens, 7.52% had MMC orifices deeper than 2 mm from the CEJ. Confluent anatomy was the most frequent configuration. No significant relation was detected between the orifice depth and MMC configuration ( P > .05). Conclusions It was concluded that 77.41% of the specimens did not require troughing preparation, the remaining 15.07% would require troughing, and 7.52% could not be accessed even with the troughing preparation. [ABSTRACT FROM AUTHOR]

The primary objective of endodontic therapy is to achieve a three-dimensional obturation of the root canal space after adequate preparation of the canal space to remove the tissue debris, microorganisms, and their byproducts. Anatomical variations have frequently been encountered in endodontic practice and have to be adequately managed by the clinician. Missed roots and canals are a major reason for failure of therapy. Technological advances have given the clinician ample opportunity to identify and treat these aberrations successfully. The present report describes a left mandibular second permanent molar requiring root canal treatment, found to have three separate canals in the mesial root. This case demonstrates a rare anatomical configuration and emphasizes the need for the clinician to be aware of and look out for such variations and use adequate diagnostic methodologies prior to and during therapy to detect such variations. The possibility of additional canals, whenever in doubt, should be explored with the assistance of technologies such as those of magnification and illumination and various diagnostic aids. Operator experience has also shown to be a key factor in negotiation and management of these aberrant canal configurations. [ABSTRACT FROM AUTHOR]

Objective: To investigate mesial root canal curvatures of human mandibular first molars using cone-beam computed tomography (CBCT)., Methods: CBCT was performed for scanning the mandibular first molars of 1600 Chinese subjects, among whom the subjects identified to have middle mesial canals were divided into 5 age groups, namely group A (18-29 years), group B (30-39 years), group C (40-49 years), group D (50-59 years), and group E (60-80 years) for further analysis. All the CBCT images were reconstructed using Planmeca Romexis CBCT image reconstruction system, and the curvature of the mesial root was measured using the Schneider method., Results: A total of 2856 CBCT images were obtained from the 1600 subjects, among whom 168 (5.88%) were found to have middle mesial canals in the mandibular first molars. The prevalence of middle mesial canals was 37.50% in group A, 17.80% in group B, 14.88% in group C, 19.64% in group D, and 10.12% in group E. The moderate of the curvature in the mesiodistal direction was significantly higher in group A than in the other groups ( P < 0.05); the curvature in mesiodistal direction differed significantly among the 5 groups ( P < 0.05), and was the greatest in group A followed by group C and group D, and was the smallest in group E. The curvature in the buccolingual direction was similar among the 5 groups. The incidence of mesiodistal and buccolingual curvature of the middle mesial canals was significantly higher in the middle 1/3 of the root canal than in the upper 1/3 and apical 1/3 of the root canal., Conclusions: The incidence of middle mesial canals in the mesial root of the mandibular first molars decreases with age. The middle mesial canal system of the mandibular first molar is complex and variable, and most of the first molars have obvious curvature in the mesiodistal and buccolingual directions. CBCT can provide reference for clinical treatment to reduce the treatment failure rate.