Transcript of "Comparative analysis of accessory mesial canal identification in mandibular first molars by using four different diagnostic methods"
Clinical ResearchComparative Analysis of Accessory Mesial CanalIdentiﬁcation in Mandibular First Molarsby Using Four Different Diagnostic MethodsK^nia Maria Pereira Soares de Toubes, MS, Maria Ilma de Souza C^rtes, PhD, e oMaria Alice de Abreu Valadares, MS, Luciana Cardoso Fonseca, PhD, Eduardo Nunes, PhD,and Frank Ferreira Silveira, PhDAbstractIntroduction: The objective of the present in vitrostudy was to compare 4 diagnostic methods to identifyaccessory mesial canals (AMCs) in lower ﬁrst molars. T he morphology of the lower ﬁrst molar has been assessed by using many different diagnostic methods, with very variable results (1–17). This tooth presents a high rate of intercanals and anastomosis, mainly in the apical 5 mm, which presentsMethods: Forty-four lower ﬁrst molars were selected a clinical challenge in terms of cleaning and disinfection (16, 17). There isfor assessment with cone-beam computed tomography increasing interest in evaluating methods for identifying the accessory mesial canal(CBCT), digital radiography (DR), clinical inspection (AMC) of the lower ﬁrst molar. Various studies have reported that the prevalence of(CI), and dental operating microscope (DOM). Initially, AMCs ranges from 1%–18% (1, 4, 6, 12, 14). However, some methods were unableaxial images were obtained by using CBCT, and radio- to identify the presence of such canals (10). It has been hypothesized that the spacegraphs were taken in ortho, mesial, and distal angula- between the mesiobuccal (MB) and mesiolingual (ML) canals is an isthmus that cantions. The images were assessed by 2 independent be cleaned and shaped (8, 12).groups of examiners, and all of the results obtained re- Clinical inspection (CI) and digital radiography (DR) are the traditional methodsmained undisclosed until the end of the experiment. used to identify root canals (18). However, the efﬁcacy of CI is directly dependent on theSubsequently, root canal access was prepared, and the examiner’s knowledge and skills (19, 20), whereas radiography is limited by technicalmesial subpulpal groove was located by using sharp factors such as contrast and angulation (18). Each method has its own unique limita-endodontic explorers. The roots were examined with tions, which contribute to a relatively high rate of unidentiﬁed canals, particularly whenDOM, and all identiﬁed canals were negotiated and in- canal location and number are atypical (19).strumented by using a ProTaper Rotary System. The A higher-magniﬁcation view of the straight segment of the root canal by usingresults were tabulated and statistically analyzed by either magnifying glasses or an operating microscope (DOM) particularly enhancesnonparametric McNemar tests. Results: Twelve AMCs the ability to detect canals that could not normally be observed by CI alone. This has(27.0%) were identiﬁed by CBCT, and 58.0% were in- increased the number of published case reports showing unsuccessful endodonticstrumented. No AMCs were visualized in any DR exam- treatment because AMCs are not always visible without the aid of magniﬁcationined. Fifteen potential AMCs (34%) were identiﬁed by (1–3, 5, 8).CI, but only 47.0% were conﬁrmed after instrumenta- Cone-beam computed tomography (CBCT) presents a new technologicaltion. Thirteen AMCs (30.0%) were identiﬁed by DOM, approach that is noninvasive and overcomes many of the disadvantages of CI, DR,and 84.0% could be negotiated and instrumented. and DOM because the operator can visualize the morphologic characteristics of theConclusions: There were statistically signiﬁcant differ- sample in 3-dimensional slices without destroying the specimen (21–24). Despiteences between the 4 types of assessments for AMC the limitations imposed by biological, technical, and economic factors, CBCT hasidentiﬁcation. There was good agreement between been implemented in dental practice and is suggested as an auxiliary means ofDOM and CBCT, whereas DR and CI were not as precise identifying and diagnosing canals and isthmuses.as either of the other 2 diagnostic methods. (J Endod Relevant comparative studies that use CBCT for the identiﬁcation of AMCs in the2012;38:436–441) literature are scarce (25). One study compared CBCT with DR in determining the number of canals in anterior and premolar teeth (26). By using CBCT, Baratto et alKey Words (27) evaluated the presence of MB2 canals in upper molars, and Wang et al (14) eval-Accessory canals, cone beam computed tomography, uated the morphology of the mandibular ﬁrst molar in the Chinese population. An i-CATdental operating microscope, mandibular ﬁrst molars device was used to identify the MB2 canal in the upper molars, and the results compared with periapical radiography and transverse clinical sectioning (28). Carvalho and Zuolo (6) determined the number of canals in lower molars with the naked eye and compared From the Department of Dentistry, Pontiﬁcial Catholic University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil. Address requests for reprints to Dr Maria Ilma de Souza C^rtes, Pontif Universidade Catlica de Minas Gerais, Departamento de Odontologia, Rua Goncalves Dias, o ıcia o ¸142 –Sala 502, Bairro Funcionrios, Belo Horizonte, MG, Brasil, CEP 30140-090. E-mail address: firstname.lastname@example.org a0099-2399/$ - see front matter Copyright ª 2012 American Association of Endodontists.doi:10.1016/j.joen.2011.12.035436 Soares de Toubes et al. JOE — Volume 38, Number 4, April 2012
Clinical ResearchFigure 1. Acrylic template containing 9 holes for CBCT examination (A). Platform of the tomography apparatus with template positioned on it (B). Tomographyapparatus (C). Axial image obtained from CBCT with the XoranCat software (D).this with the number determined by using DOM, but they did not use DR molars, as well as in determining their frequency, location, apicalor CBCT. Yoshida et al (7) compared a visual method, magnifying end, and amenability to negotiation and instrumentation.glasses, and DOM in identifying canals in a sample of 260 teeth butdid not report the presence of AMCs. The effectiveness of DOM andmagnifying glasses was recently compared for the identiﬁcation of Materials and MethodsAMCs in lower molars, including the frequency, location, and amena- Tooth Selection and Preparationbility to exploration (12). However, CBCT was not used, and instrumen- A set of 125 extracted mandibular ﬁrst molars was collectedtation was not performed. randomly from the Dental Department human tooth bank and then The objective of this in vitro study was to compare CBCT with CI, exposed to digital periapical radiography in the buccolingual direction.DR, and DOM methods in the identiﬁcation of AMCs in lower ﬁrst Patient age, gender, and race were not considered. Only teeth withFigure 2. Acrylic template for DR in the mesial (A), ortho (B), and distal (C) positions; teeth positioned on the template (D–F) and digital radiograph (G–I).JOE — Volume 38, Number 4, April 2012 Comparative Analysis of AMC Identiﬁcation in Mandibular First Molars 437
Clinical Research TABLE 1. Comparison of Results of Different Diagnostic Methods, Obtained by McNemar Test Diagnostic methods Value of diagnostic methods P .05 CI Â CBCT 8.25 P .010 CI Â DOM 7.5 P .010Figure 3. Image of some sections of a tooth scanned from crown to apex, CBCT Â DOM 9.25 P .010identifying dentin interposition between the canals (arrows).complete root formation and 2 canals in the mesial root were included.Teeth that had been subjected to previous endodontic treatment or dis- highly skilled endodontist and 1 imaging expert who worked together.played aberrant curve anatomy, calciﬁed canals, or internal root The groups of examiners were trained and calibrated in a pilot study byresorption were excluded. After careful examination, 44 ﬁrst molars using images of ﬁrst molars designed speciﬁcally for this study and bywere selected for experiments and stored in 0.01% thymol solution until using identical methodologies. The evaluation criteria for the identiﬁca-use. tion of the AMCs through DR and CBCT were established during the pilot study. An interexaminer kappa test was performed to evaluate the coherence between the 2 examiner pairs.CBCT Five plates of methylmethacrylate monomer (UNIGEL, S~o Paulo, aBrazil), measuring 7.5 cm in width, 7.5 cm in length, and 3.0 cm in CBCT Image Readingheight, were prepared by drilling nine 1.5-cm diameter holes CBCT examination was conducted in a dark room, and the ideal(Fig. 1A). The holes were ﬁlled with Adsil silicone (Vigodente, Rio de image contrast had a 12-bit grayscale resolution for a maximum timeJaneiro, Brazil), and the teeth were individually inserted into the sili- of 10 minutes per tooth. The samples were coded, and the codescone at the level of the cementoenamel junction, which had been previ- were kept undisclosed so that the examiners could not identify theously delimited to ensure the stabilization and parallelism of each samples. Images were read in the axial section from the pulp chamberspecimen as well as standardization of the CBCT examination. After ﬂoor to serve as a sample reference point for the examiners. In the anal-the material was set, the acrylic template was positioned on the platform ysis of the tomographic sections, the presence of 3 canals was taken intoof the tomography apparatus (i-CAT; Imaging Sciences International, account only when the 3 radiolucent oriﬁces were observed to be inde-Hatﬁeld, PA) (Fig. 1B), which was operated at a ﬁeld of view of pendent and presented a radiopaque structure, regardless of their loca-6 cm, voxel size of 0.2 mm, and exposure time of 40 seconds, to digitize tion along the root (Fig. 3).the teeth from crown to apex. Image acquisition and analysis were per-formed by using XoranCat software, version 3.0.34 (Xoran Technolo-gies, Ann Arbor, MI) (Fig. 1C). The number of canals in the mesial DR Image Readingroot of the lower ﬁrst molar was determined by navigation of the axial During the radiographic evaluation, the same groups of examinerstomographic sections (Fig. 1D). observed the DR, following the same methodologic protocol and nondisclosure of the specimen codes. The examiners were instructedDR to consider one canal present only if 75% of the radiolucent structure could be visualized from the pulp chamber ﬂoor to the apex. The images Three plates of methylmethacrylate monomer (UNIGEL) were were treated with different ﬁlters to improve canal identiﬁcation. Bothmade for the standardization of the radiographic view in the same angu- groups of examiners used the same ﬁlters.lations. These plates measured exactly the size of the digital radio- Data collected during the examinations (CBCT and DR) were tabu-graphic ﬁlm, with angles of –30 for mesioangulation (Fig. 2A), lated and sent for statistical analysis, while remaining undisclosed to the0 for orthoangulation (Fig. 2B), and +30 for distoangulation 2 groups of examiners and the investigator.(Fig. 2C), respectively. One template of Adsil silicone was made foreach pair of teeth and standardized in accordance with the innermeasurements of the methacrylate plate. The teeth were positioned CIon this template, and a digital ﬁlm was placed below it. The set (meth- To simulate CI, each sample was positioned and individuallyacrylate plate, digital ﬁlm, silicone template, and teeth) was exposed at attached to a bench vise (Somar, Joinville, Brazil) for stabilization.–30 (Fig. 2D), 0 (Fig. 2E), and +30 (Fig. 2F) horizontal angula- Conventional endodontic access cavities were completed by nakedtions, and the x-ray unit was at 65 kVp and 8 mA for 0.44 seconds eye and under abundant irrigation by using a 5.2% sodium hypochlorite(Dabi Atlante, S~o Paulo, Brazil). The resulting images were digitized a solution (Lenza Farmac^utica, Belo Horizonte, Brazil) to optimize visi- eby using the Digora Optime System (Soredex, Helsinki, Finland) in bility. The mesial subpulpal groove was explored with sharp endodonticthe mesial (Fig. 2G), ortho (Fig. 2H), and distal (Fig. 2I) positions. explorers (DG 16; Hu-Friedy, Chicago, IL) under illumination from a reﬂector (Dabi Atlante). When the tip of the explorer became attachedImage Reading to any groove suggesting a canal, it was considered a possible AMC. The tomographic and radiographic images were evaluated by 2 Otherwise, the exploration was ﬁnished so that the sample could remainpairs of examiners working independently. Each pair consisted of 1 intact for the next examination. The data are reported.TABLE 2. Number of AMCs Identiﬁed by Each Diagnostic Method Agreement between diagnostic methods No. of teeth No. of identiﬁed AMCs 1 11 CI, n = 6 CBCT, n = 2 DOM, n = 3 2 7 CI Â CBCT, n = 2 CI Â DOM, n = 2 DOM Â CBCT, n = 3 3 5 CI Â CBCT Â DOM, n = 5438 Soares de Toubes et al. JOE — Volume 38, Number 4, April 2012
Clinical ResearchTABLE 3. Identiﬁcation Frequency of Possible AMCs Identiﬁed and Instrumented in the Mesial Root of Lower First Molars, Including Frequency by DiagnosticMethod Diagnostic No. of possible Relative frequency of Conﬁdence No. of instrumented Relative frequency of method AMCs identiﬁed (n) AMC identiﬁcation (%) interval AMCs (n) instrumented AMCs (%) CBCT 12 27 13.5–40.9 7 58 DR 0 0 0 0 0 CI 15 34 19.5–48.7 7 47 DOM 13 30 15.5–43.6 11 85DOM The result of the interexaminer kappa test for the identiﬁcation of A DOM (DOM M900; DF Vasconcelos, S~o Paulo, Brazil) at 13Â a AMCs by CBCT was 0.82 (P .001).magniﬁcation was used to investigate the mesial subpulpal groove ac- As shown in Table 3, 12 AMCs (27%) were identiﬁed by CBCT, andcording to the same criteria used in the CI. The data obtained were re- 58% (n = 7) of these were instrumented. It was not possible to identifycorded. Photographs were taken with a digital camera (NIKON D60; any AMCs by DR. Fifteen possible AMCs (34%) were identiﬁed by CI, butNikon, Tokyo, Japan) mounted on the optical microscope by means only 47% (n = 7) were instrumented. On examination with DOM, 13of an adapter (DF Vasconcelos), which also assisted in the visual docu- AMC canals (30%) were identiﬁed, and 85% (n = 11) of these canalsmentation. Subsequently, the excess dentin along the subpulpal groove were fully instrumented.was selectively removed by using an ultrasonic tip (TU17; Triniti, S~oa The AMCs identiﬁed were located in the isthmus between the MBPaulo, Brazil) that had been mounted on an ENAC ultrasonic device and ML canals, close to the MB (46%), at the center (23%), or close to(Osada, Inc, Tokyo, Japan) at low strength. After isthmus preparation, the ML (31%) (Table 4, Fig. 4). Of the 13 AMCs identiﬁed by DOM, 7the mesial root was mapped again, and the results were recorded in canals (54%) were connected to the MB (Fig. 4D), 5 (38%) were con-a table. The AMCs identiﬁed were passively emptied according to the nected to the ML (Fig. 4E), and 1 (8%) ended in an independentcrown-down technique until #10 K-ﬁle (Dentsply Maillefer, Ballaigues, foramen (Fig. 4F), as shown in Figure 4G.Switzerland) reached patency. A new radiographic examination wasperformed at ortho, mesial, and distal angulations, with the teeth re- Discussionmaining in their respective templates and the ﬁles positioned in their Although the identiﬁcation of AMCs is a technical challengerespective canals. This procedure allowed for the determination of because of the difﬁculty in locating and visualizing these features withpreparation length and the assessment of the apical end of all identiﬁed the naked eye, CI without magniﬁcation is still widely used. Adequatecanals. The specimens were instrumented with ProTaper rotary ﬁles coronary access and the use of DOM are both crucial to overcoming(Dentsply Maillefer) according to the technique recommended by the this challenge (6, 7, 12, 29, 30). In addition, the use of ultrasonicmanufacturer until the F1 ﬁle reached as far apically as possible. tips to clean the cervical isthmus is very important to enable the A kappa test was performed to assess the agreement of DR and identiﬁcation of the majority of AMCs (3, 5, 6, 12).CBCT results between the 2 groups of examiners, revealing 95% overall Notably, although Corcoran et al (20) reported that the ability toagreement for both studies. Agreement between diagnostic methods was locate root canals depends on the operator’s skills and experience, thealso determined by using kappa as an estimator. The nonparametric present study showed that CI for the identiﬁcation of AMCs was less reli-McNemar test (Stata, version 11.1; Stata Corporation, College Station, able than DOM or CBCT, even when performed by an experiencedTX) was used to statistically determine the best method of AMC identi- professional. In the present study, many grooves suggestive of AMCﬁcation. were found to be simple spaces in the isthmus after instrumentation. Friedman (31) concluded that the reading of radiographic images can vary because of differences in angulation and contrast as well as the Results examiner’s interpretation. DR was used with the expectation that it Table 1 summarizes the results of the McNemar test comparing the would overcome these inconsistencies and biased radiographic inter-4 proposed diagnostic methods. There was a statistically signiﬁcant pretations without compromising the results (32, 33), but 2 teams ofdifference between the diagnostic methods used (P .01). experienced endodontists and dentists specializing in imaging did not As shown in Table 2, AMCs were identiﬁed by only one diagnostic identify any AMCs by using DR, with the kappa test showing 100%method in 11 specimens (25%). Matching results from 2 and 3 diag- inter-rater agreement. Therefore, it can be concluded from this studynostic methods were observed in 7 (16%) and 5 (11%) specimens, that DR was not an efﬁcient method for the identiﬁcation of AMCs,respectively. In 21 teeth (48%), it was not possible to identify AMCs even when radiographs were taken at different angulations (34).by any diagnostic method. However, although it cannot be used to identify AMCs, the value of The interexaminer agreement between the 2 groups was 100% for DR should not be underestimated.DR examinations. None of the examiners identiﬁed AMCs by using DR, In the present study, CBCT allowed the visualization of thedespite varying the angulations. morphology of the mesial root of the lower ﬁrst molars, with theTABLE 4. Frequency Distribution of AMC Locations from DOM and Apical Terminus from DR After Instrumentation Variable Frequency Relative frequency Variable Frequency Relative frequency AMC location (N) (%) AMC apical terminus (N) (%) Closer to MB 6 46 Cervical 7 54 Closer to ML 4 31 Mid-apical 5 38 Between MB and ML 3 23 Apical 1 8 Total 13 100 Total 13 100JOE — Volume 38, Number 4, April 2012 Comparative Analysis of AMC Identiﬁcation in Mandibular First Molars 439
Clinical ResearchFigure 4. Possible locations of AMC: close to ML (A); at the center, between MB and ML canals (B); and close to MB (C). Digital radiographs showing the end of AMCclose to MB (D) and ML (E) canals as well as at an independent foramen (F). Beginning and apical end of AMC in 3 independent foramina (arrows) (G and H).2-mm-thick sections observed from the coronary third to the apex; was that it allowed the morphologic visualization of the canal trajectory,this provided a high-resolution image without compromising the mainly in the mid and apical thirds of the roots, whereas visualizationpreservation of the specimens and was considered the gold standard with DOM was limited to the straight portion of the canal. However,in this study (28). The inter-rater concordance (kappa values) Nance et al (35) stated that not all canals can be identiﬁed withbetween the examiners when using CBCT was 0.82. This high kappa CBCT, and they also indicated that CBCT should be used as an auxiliaryvalue shows that the examiners were well-trained in reading the method in identiﬁcation, rather than as a replacement for careful clin-images, thus eliminating individual experience as an interference ical examination.factor. The AMC was considered a canal when it was the one entirely According to Mortman and Ahn (8) and Karapinar-Kazandag et alsurrounded by dentin (17). It was identiﬁed in 12 specimens (12), this ﬁnding suggests that the AMC is not actually a canal but an(27.0%) by using CBCT, greater than the number reported by Nav- isthmus with sufﬁcient space to be explored, cleaned, and shaped. Byarro et al (9) (14.81%), probably because of methodologic differ- using CBCT images, it was possible to prove this assertion; it was notences. When comparing CBCT with other diagnostic methods (CI possible to identify any AMC that was totally independent from theÂ DR Â DOM), the results from CBCT were most similar to those cervical to apical thirds in any of the specimens. In one specimen,from DOM. the AMC end was totally independent, but it presented in the foramen In the present study, of the 13 canals identiﬁed by DOM, 7 (54%) located inside an isthmus between the MB and ML root, rather thanwere connected to either the MB or ML before the mid-third of the root, in the apex.whereas 5 other canals were connected between the mid-third and the Under the conditions of the present study, there were signiﬁcantapex. One specimen had an AMC with an independent foramen, a rare differences between the 4 methods for the identiﬁcation of AMCs inﬁnding in the literature (3, 6). These ﬁndings corroborate studies by the mesial roots of lower ﬁrst molars. DOM alone could have identiﬁedPomeranz et al (1) and Karapinar-Kazandag et al (12). Furthermore, all instrumentable AMCs. CBCT was the next most effective method, andCarvalho and Zuolo (8) and Karapinar-Kazandag et al reported an the other methods were less valuable.increased number of AMCs identiﬁed in their studies (7.1% and18%, respectively). However, in this study, AMCs were identiﬁed in Acknowledgments30% of the specimens, probably because all canals identiﬁed were in- The authors deny any conﬂicts of interest related to this study.strumented, regardless of their location. In fact, 4 AMCs were foundduring the specimen cleaning and shaping procedures in the presentstudy. This ﬁnding conﬁrms that instrumentation is an important step References 1. Pomeranz H, Eidelman D, Goldberg M. Treatment considerations of the middlein identifying AMCs. mesial canal of mandibular ﬁrst and second molars. J Endod 1981;7:565–8. The results of this study show that CBCT had a lower AMC identi- 2. Fabra-Campos H. Unusual root anatomy of mandibular ﬁrst molars. J Endod 1985;ﬁcation rate compared with DOM. However, the great advantage of CBCT 11:568–72.440 Soares de Toubes et al. JOE — Volume 38, Number 4, April 2012
Clinical Research 3. Martinez-Berna A, Badanelli P. Mandibular ﬁrst molars with six root canals. J Endod 19. Vande Voorde HE, Odendahl D, Davis J. Molar 4th canals: frequent cause of 1985;11:348–52. endodontic failure? ILL Dent J 1975;44:779–86. 4. Goel N, Gill K, Taneja J. Study of root canals conﬁguration in mandibular ﬁrst 20. Corcoran J, Apicella MJ, Mines P. The effect of operator experience in locating addi- permanent molar. J Indian Soc Pedod Prev Dent 1991;8:12–4. tional canals in maxillary molars. J Endod 2007;33:15–7. 5. Jacobsen E, Dick K, Bodell R. Mandibular ﬁrst molars with multiple mesial canals. 21. Patel S, Dawood A, Ford T, Whaites E. The potential applications of cone beam J Endod 1994;20:610–3. computed tomography in the management of endodontic problems. Int Endod J 6. De Carvalho M, Zuolo M. Oriﬁce locating with a microscope. J Endod 2000;26: 2007;40:818–30. 532–4. 22. Cotton T, Geisler T, Holden D, Schwartz S, Schindler W. Endodontic applications of 7. Yoshioka T, Kobayashi C, Suda H. Detection rate of root canal oriﬁces with a micro- cone-beam volumetric tomography. J Endod 2007;33:1121–32. scope. J Endod 2002;28:452–3. 23. Mannocci F, Peru M, Sherriff M, Cook R, Pitt Ford T. The isthmuses of the mesial 8. Mortman RE, Ahn S. Mandibular ﬁrst molars with three mesial canals. Gen Dent root of mandibular molars: a micro-computed tomographic study. Int Endod J 2003;51:549–51. 2005;38:558–63. 9. Navarro LF, Luzi A, Garc AA, Garc AH. Third canal in the mesial root of perma- ıa ıa 24. Sour E, Baksi BG, Gr€ndahl HG. Imaging of root canal ﬁllings: a comparison of g o nent mandibular ﬁrst molars: review of the literature and presentation of 3 clinical subjective image quality between limited cone-beam CT, storage phosphor and reports and 2 in vitro studies. Med Oral Patol Oral Cir Bucal 2007;12:E605–9. ﬁlm radiography. Int Endod J 2007;40:179–85.10. Reuben J, Velmurugan N, Kandaswamy D. The evaluation of root canal morphology 25. La SH, Jung DH, Kim EC, Min KS. Identiﬁcation of independent middle mesial canal of the mandibular ﬁrst molar in an Indian population using spiral computed tomog- in mandibular ﬁrst molar using cone-beam computed tomography imaging. J Endod raphy scan: an in vitro study. J Endod 2008;34:212–5. 2010;36:542–5.11. Gu Y, Lu Q, Wang H, Ding Y, Wang P, Ni L. Root canal morphology of permanent 26. Matherne R, Angelopoulos C, Kulild J, Tira D. Use of cone-beam computed tomog- three-rooted mandibular ﬁrst molars: part I—pulp ﬂoor and root canal system. raphy to identify root canal systems in vitro. J Endod 2008;34:87–9. J Endod 2010;36:990–4. 27. Baratto Filho F, Zaitter S, Haragushiku GA, de Campos EA, Abuabara A, Correr GM.12. Karapinar-Kazandag M, Basrani BR, Friedman S. The operating microscope Analysis of the internal anatomy of maxillary ﬁrst molars by using different methods. enhances detection and negotiation of accessory mesial canals in mandibular J Endod 2009;35:337–42. molars. J Endod 2010;36:1289–94. 28. Blattner TC, George N, Lee CC, Kumar V, Yelton CD. Efﬁcacy of cone-beam computed13. Krithikadatta J, Kottoor J, Karumaran CS, Rajan G. Mandibular ﬁrst molar having an tomography as a modality to accurately identify the presence of second mesiobuccal unusual mesial root canal morphology with contradictory cone-beam computed canals in maxillary ﬁrst and second molars: a pilot study. J Endod 2010;36:867–70. tomography ﬁndings: a case report. J Endod 2010;36:1712–6. 29. Saunders W, Saunders E. Conventional endodontics and the operating microscope.14. Wang W, Zheng Q, Zhou X, et al. Evaluation of the root and canal morphology of Dent Clin North Am 1997;41:415–28. mandibular ﬁrst permanent molars in a western Chinese population by cone- 30. Buhrley LJ, Barrows MJ, BeGole EA, Wenckus CS. Effect of magniﬁcation on locating beam computed tomography. J Endod 2010;11:1786–9. the MB2 canal in maxillary molars. J Endod 2002;28:324–7. 15. Pablo O, Estevez R, Snches M, Heibon C, Cohenca N. Root anatomy and canal a 31. Friedman S. Prognosis of initial endodontic therapy. Endodontic Topics 2002;2:59–88. conﬁguration of the permanent mandibular ﬁrst molar: a systematic review. 32. Naoum HJ, Chandler NP, Love RM. Conventional versus storage phosphor-plate J Endod 2010;12:1919–31. digital images to visualize the root canal system contrasted with a radiopaque16. Hsu Y, Kim S. The resected root surface: the issue of canal isthmuses. Dent Clin medium. J Endod 2003;29:349–52. North Am 1997;41:529–40. 33. Nair M, Nair U. Digital and advanced imaging in endodontics: a review. J Endod17. Gu L, Wei X, Ling J, Huang X. A microcomputed tomographic study of canal isth- 2007;33:1–6. muses in the mesial root of mandibular ﬁrst molars in a Chinese population. 34. Reit C, Hollender L. Radiographic evaluation of endodontic therapy and the inﬂu- J Endod 2009;35:353–6. ence of observer variation. Scand J Dent Res 1983;91:205–12.18. Hession RW. Endodontic morphology: II—a radiographic analysis. Oral Surg Oral 35. Nance R, Tyndall D, Levin LG, Trope M. Identiﬁcation of root canals in molars by Med Oral Pathol 1977;44:610–20. tuned-aperture computed tomography. Int Endod J 2000;33:392–6.JOE — Volume 38, Number 4, April 2012 Comparative Analysis of AMC Identiﬁcation in Mandibular First Molars 441