An Anatomic Investigation of the Mandibular First Molar Using Micro–Computed Tomography

Published:September 06, 2013DOI:



      The mandibular first molar is the most frequently endodontically treated tooth and is extremely anatomically challenging. The purpose of this micro–computed tomographic evaluation was to quantitatively investigate the morphology of the mandibular first molar to improve both orthograde and retrograde treatment.


      Twenty-two mandibular first molars were scanned, reconstructed, and subjected to various linear measurements. The average, standard deviation, and standard error of the mean of each linear measurement were calculated, and the mode for each nominal data category was determined.


      The furcal aspect of the entire mesial root should be considered a “danger zone.” Mesial canals were found to be much more variable than distal canals in morphology, whereas the relative position of the orifices of the mesial canals was relatively consistent at 1.5 mm from the pulpal floor. Root-end resection of 3 mm would remove the majority of lateral canals and apical ramifications.

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        • Hull T.E.
        • Robertson P.B.
        • Steiner J.C.
        • et al.
        Patterns of endodontic care for a Washington state population.
        J Endod. 2003; 29: 553-556
        • Wayman B.E.
        • Patten J.A.
        • Dazey S.E.
        Relative frequency of teeth needing endodontic treatment in 3350 consecutive endodontic patients.
        J Endod. 1994; 20: 399-401
        • De Deus Q.D.
        Frequency, location, and direction of the lateral, secondary, and accessory canals.
        J Endod. 1975; 1: 361-366
        • Fabra-Campos H.
        Three canals in the mesial root of mandibular first permanent molars: a clinical study.
        Int Endod J. 1989; 22: 39-43
        • Hsu Y.Y.
        • Kim S.
        The resected root surface. The issue of canal isthmuses.
        Dent Clin North Am. 1997; 41: 529-540
        • Abou-Rass M.
        • Frank A.L.
        • Glick D.H.
        The anticurvature filing method to prepare the curved root canal.
        J Am Dent Assoc. 1980; 101: 792-794
        • Berutti E.
        • Fedon G.
        Thickness of cementum/dentin in mesial roots of mandibular first molars.
        J Endod. 1992; 18: 545-548
        • Bramante C.M.
        • Berbert A.
        • Borges R.P.
        A methodology for evaluation of root canal instrumentation.
        J Endod. 1987; 13: 243-245
        • Gilles J.
        • Reader A.
        An SEM investigation of the mesiolingual canal in human maxillary first and second molars.
        Oral Surg Oral Med Oral Pathol. 1990; 70: 638-643
        • Hartwell G.
        • Bellizzi R.
        Clinical investigation of in vivo endodontically treated mandibular and maxillary molars.
        J Endod. 1982; 8: 555-557
        • Pineda F.
        Roentgenographic investigation of the mesiobuccal root of the maxillary first molar.
        Oral Surg Oral Med Oral Pathol. 1973; 36: 253-260
        • Skidmore A.E.
        • Bjorndal A.M.
        Root canal morphology of the human mandibular first molar.
        Oral Surg Oral Med Oral Pathol. 1971; 32: 778-784
        • Vertucci F.J.
        Root canal anatomy of the human permanent teeth.
        Oral Surg Oral Med Oral Pathol. 1984; 58: 589-599
        • Kerekes K.
        • Tronstad L.
        Morphometric observations on the root canals of human molars.
        J Endod. 1977; 3: 114-118
        • Krasner P.
        • Rankow H.J.
        Anatomy of the pulp-chamber floor.
        J Endod. 2004; 30: 5-16
        • Kim S.
        • Pecora G.
        • Rubinstein R.A.
        • et al.
        The resected root surface and isthmus.
        in: Kim S. Pecora G. Rubinstein R. Color Atlas of Microsurgery in Endodontics. Saunders, Philadelphia2001: 95-104
        • de Pablo O.V.
        • Estevez R.
        • Péix Sánchez M.
        • et al.
        Root anatomy and canal configuration of the permanent mandibular first molar: a systematic review.
        J Endod. 2010; 36: 1919-1931
        • Green D.
        Double canals in single roots.
        Oral Surg Oral Med Oral Pathol. 1973; 35: 689-696
        • Lim S.S.
        • Stock C.J.R.
        The risk of perforation in the curved canal: anticurvature filing compared with the stepback technique.
        Int Endod J. 1987; 20: 33-39
        • von Arx T.
        Frequency and type of canal isthmuses in first molars detected by endoscopic inspection during periradicular surgery.
        Int Endod J. 2005; 38: 160-168
        • Mannocci F.
        • Peru M.
        • Sherriff M.
        • et al.
        The isthmuses of the mesial root of mandibular molars: a micro-computed tomographic study.
        Int Endod J. 2005; 38: 558-563