Morphology and classification of the second mesiobuccal canal in maxillary first molars: a cone-beam computed tomography analysis in a Chinese population.

BACKGROUND: Understanding the tooth anatomy is crucial for ensuring effective endodontic treatment. This study investigated the root canal morphology of the second mesiobuccal (MB2) canal in maxillary first molars (MFMs) in a Chinese population using cone-beam computed tomography (CBCT). METHODS: This study evaluated 486 MFMs with MB2 canals from 285 participants undergoing CBCT examination and determined the Vertucci's classification and position of the MB2 canal orifice. The prevalence of the MB2 canal was correlated with the sex, age, and tooth side. The correlations between the prevalence of the MB2 canal and sex and tooth side were assessed using the Fisher's exact test. The chi-square test was used for evaluating the correlation between the prevalence of the MB2 canal and age. RESULTS: The number of type II, III, IV, V, VI, VII, and other root canals in the MFMs was 30.9%, 0.6%, 65.0%, 1.2%, 1.2%, 0.4%, and 0.6%, respectively. Among the 201 cases with bilateral inclusion, 87.6% showed consistent canal configuration. Results of the first clear apparent position (FCAP) of the MB2 canals showed that 434, 44, and 3 teeth had FCAP at the upper, middle, and bottom one-third of the root, respectively. The FCAPs of the MB2 canal in the MFMs with types II, IV, and VI, as well as types III and V canals showed significant differences (p<0.05). The horizontal distance between the MB1 and MB2 canal orifices in the type II canals of MFMs was significantly lesser than those in the type IV canals of MFMs (p < 0.01). The longitudinal distance between the pulp chamber floor plane and MB2 canal orifice significantly correlated with age (p < 0.05). CONCLUSIONS: The morphology of the mesiobuccal root canal in the MFMs is complex. Complete understanding of the anatomical morphology of the root canal combined with the CBCT and dental operating microscope is necessary for the accurate detection of the MB2 canal and consequently improved success rate of root canal treatment. Our study findings can help endodontists improve endodontic treatment outcomes.

Morphology of the Second Mesiobuccal Canal in the Maxillary Second Molar / Morfología del Segundo Canal Mesiovestibular en el Segundo Molar Maxilar

SUMMARY: Failure to locate a complete canal system affects the prognosis of root canal treatment. A missed root canal is one of the most common reasons for failed root canal treatment. The prevalence of the second mesiobuccal canal in the maxillary second molar is relatively high and has a variety of configurations. Therefore, knowledge of its morphology is required in clinical endodontics. This review presented the canal in terms of its prevalence, classification, anatomical features, and the method for locating the second mesiobuccal canal in the maxillary second molar. Root canal treatment requires knowledge of tooth morphology, appropriate access preparation, and a thorough examination of the tooth's interior. Thus, clinicians should carefully employ various methods for assessing the anatomy of the entire root canal system to prevent failure in locating the second mesiobuccal canal. This canal can be located by modifying the access cavity design and utilizing specific instruments to improve the second mesiobuccal canal system visualization.

La falta de localización de un sistema completo de canal afecta el pronóstico del tratamiento de éste. La omisión de un tratamiento de canal es uno de los motivos más frecuentes por las que el tratamiento de canal fracasa. La prevalencia del segundo canal mesiovestibular en el segundo molar superior es relativamente alta y tiene una variedad de configuraciones. Por tanto, el conocimiento de su morfología es necesario en endodoncia clínica. Esta revisión presentó el canal en términos de su prevalencia, clasificación, características anatómicas y el método para localizar el segundo canal mesiovestibular en el segundo molar superior. El tratamiento de canal requiere conocimiento de la morfología del diente, una preparación adecuada del acceso y un examen exhaustivo del interior del diente. Por lo tanto, los dentistas deben emplear cuidadosamente varios métodos para evaluar la anatomía de todo el sistema de canales radiculares para evitar fallas en la localización del segundo canal mesiovestibular. Este canal se puede localizar modificando el diseño de la cavidad de acceso y utilizando instrumentos específicos para mejorar la visualización del sistema del segundo canal mesiovestibular.

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.

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.

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.

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.

Maxillary molar root and canal morphology of Neolithic and modern Chinese.

OBJECTIVE: This study aimed to characterize Neolithic human maxillary molars from archeological remains at the Jiaojia site, Shandong, China, and compare their ultrastructural features with sex and age-matched modern locals. DESIGN: Maxillary first (n = 86) and second (n = 80) molars in 5000-year-old individuals (n = 50) from the Jiaojia site were scanned by cone-beam computed tomography (CBCT). Sex and age-matched control groups were assigned from oral surgical patients at Shandong University. Images were analyzed for crown size, root length, root morphology, canal inter-orifice distances, mesiobuccal canal morphology, and second mesiobuccal (MB2) canal prevalence and location. Neolithic and modern values were compared statistically using Chi-squared and Mann-Whitney test at p < .05. RESULTS: Crown and root size were smaller, and canal inter-orifice distances were shorter in Neolithic maxillary molars than their modern counterparts. For mesiobuccal roots, Weine's Type I single canals were the most prevalent in Neolithic and modern first and second molars. MB2 canal prevalence were not significantly different (p > .05) in Neolithic (53.3%) or modern (60.5%) first molars, and Neolithic (11.3%) or modern (21.3%) second molars. But, MB2 prevalence was significantly higher for modern than ancient male first (p = .032) and second (p = .005) molars. Additionally, MB2 were located more mesially and closer to MB1 in Neolithic than modern molars. CONCLUSIONS: Maxillary molar root and canal morphology of ancient 5000-year-old remains at the Jiaojia site resemble that of local patients. A trend towards larger tooth size, and more dispersed MB2 canals over this short evolutionary period warrants additional investigation.

A Comparison of Endodontic Treatment Factors, Operator Difficulties, and Perceived Oral Health-related Quality of Life between Elderly and Young Patients.

INTRODUCTION: The purpose of this study was to compare endodontic treatment factors, treatment difficulties, and oral health-related quality of life (OHRQOL) between elderly and young patients. METHODS: A total of 150 adults, 75 elderly (≥65 years) and 75 young patients (18-64 years), were recruited. Operators enumerated difficulties associated with communication, diagnosis, rubber dam application, access cavity preparation, canal localization, working length determination, instrumentation, and obturation after root canal treatment. The number of treatment visits, maxillary first molars with a second mesiobuccal canal, and the technical quality of the root filling were registered. Patients filled out questionnaires on pain, attendance of regular dental visits, esthetics, and masticatory function and the Oral Health Impact Profile-14. RESULTS: Significantly more elderly had necrotic pulp (P < .001) and needed root canal treatment on teeth with full-coverage crown/bridge abutment (P < .001). It was significantly difficult to perform access cavity preparation and localize root canals on the elderly and on teeth with a full-coverage crown/bridge abutment. In regression analysis, the elderly presented with difficulties only during canal localization (P < .05). Second mesiobuccal canals were obturated in 43.5% of the young patients and 23.1% of the elderly patients. There were no significant differences in the number of treatment visits or the technical quality of root filling between the 2 groups. There were no significant differences in pain sensation, esthetics, masticatory function, or regular dental visits between the 2 groups. Elderly patients reported a significantly better OHRQOL (P < .05). Patients experiencing pain, patients needing treatment on anteriors/premolars, and females reported a significantly poorer OHRQOL (P < .05). CONCLUSIONS: The elderly presented with treatment difficulty during canal localization and had better OHRQOL compared with young patients.

Assessment of the presence of a second mesiobuccal canal in maxillary first molars according to the location of the main mesiobuccal canal-a micro-computed tomographic study.

OBJECTIVES: To investigate the root canal morphology of mesiobuccal (MB) roots in maxillary first molars, and to assess the presence of a second mesiobuccal canal (MB2) according to the location of the main MB canal. MATERIALS AND METHODS: A total of 72 extracted permanent maxillary first molars were collected from dental clinics and were scanned with micro-CT and reconstructed three-dimensionally. The root canal systems were recorded according to Vertucci's classification, and the occurrence of accessory canals was also recorded. The root canal dimensions were measured at the coronal (furcation plane), middle, and apical root levels. The long (D) and short (d) diameters as well as the palatal (P) and buccal (B) distances from the center of the first mesiobuccal canal (MB1) to the root surface were measured, and the ratios of D/d and P/B were calculated. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic accuracy of using the ratio of P/B for predicting the presence of an MB2 canal. The best cut-off point was determined according to the sensitivity and specificity. RESULTS: The MB roots most frequently had a type 2-2 root canal with an incidence of 37.5% (27/72), followed by the type 1-1 (23.6%, 17/72) and type 2-1 (16.7%, 12/72) canal forms. Type 1-2 canals were detected only in 5 molars (6.9%), and type 2-1-2 canals were detected in 6 molars (8.3%). The other 5 cases included 1 case of type 1-2-1 canal and 4 cases of triple canals. MB2 canals were detected in 76.4% (55/72) of the total sample teeth. The incidence of accessory canals was 56.9% (41/72). The mean ratio of D/d was generally "greatest to least": coronal level > middle level > apical level for different root levels and MB single > MB1 > MB2 for different canals, which reflected a trend from a flat to a circular cross-sectional shape. ROC curve analysis showed that at the coronal and middle root levels, areas under the ROC curve (AUC) were greater than 0.99 (P < 0.01), and the best cut-off point was 1.58 and 1.55, respectively; at the apical level, the AUC was 0.94 (P < 0.01), and the best cut-off point was 1.77. CONCLUSIONS: The MB2 canals may be present in the MB roots of maxillary first molars with a high occurrence rate at various levels, and the P/B ratio of the MB1 is a good index for predicting the presence of an MB2. However, since all the sample teeth were collected from a Chinese population, clinicians have to be cautious while trying to apply the conclusions on teeth of other ethnic populations. CLINICAL RELEVANCE: By calculating the P/B ratio, an index reflecting the buccal deviation of the MB1, clinicians can predict the presence of an invisible MB2 in cone-beam computed tomography images with inadequate resolution.

Comparing image qualities of dental cone-beam computed tomography with different scanning parameters for detecting root canals.

BACKGROUND/PURPOSE: Cone-beam computed tomography (CBCT) is a useful device in creating 3-dimensional images in the examining area of dentistry and is one of the most common clinical methods in detecting second mesiobuccal (MB2) canals in maxillary molars. The aim of this in vitro study was to compare the image quality of the small field of view (FOV) CBCT with different rotation arcs and scanning speeds in the use of detecting root canals. METHODS: A dentate human skull was scanned in Morita 3D Accuitomo 170 with 4 × 4 cm FOV under 5 mA and 90 kVp. Two different rotation arcs (360° and 180°) and three different scanning modes (slow-speed mode, standard mode and high-speed mode) combined into six different groups. Five different levels of axial sections were selected from each group. Five endodontic specialists rated the image quality by focusing on the sharpness of the MB2 canal of the upper right first molar and the surrounding structures. RESULTS: Despite the rotation arcs, all the observers gave excellent ratings to images taken with slow-speed mode. The high-speed mode taken with 360° and 180° got the second lowest and the lowest ratings, respectively. Under the same scanning speed, the rotation arc did not have a significant difference in image quality. CONCLUSION: Slow-speed mode is inevitable in maintaining adequate image quality during taking CBCT. However, endodontists can use the half rotation mode to significantly reduce radiation dose, exposure time, and still maintain sufficient image quality for root canal anatomy assessment.

Impact of dental operating microscope, selective dentin removal and cone beam computed tomography on detection of second mesiobuccal canal in maxillary molars: A clinical study.

INTRODUCTION: Maxillary molars may frequently require root canal therapy and can have complex anatomy. It is important to locate and treat the second mesiobuccal canal to significantly improve prognosis. AIM OF THE STUDY: The purpose of this study was to evaluate direct vision, dental operating microscope (DOM), selective dentin removal under DOM, and cone beam computed tomography (CBCT) in clinical detection of second mesiobuccal root canal (MB2) in maxillary molars. MATERIALS AND METHODS: A total of 122 maxillary first and second molars indicated for root canal treatment were included in our study. Following access cavity preparation, the presence of MB2 canal orifice was assessed in four stages. Stage I: with direct vision. Stage II: under DOM, Stage III: after selective dentin removal under DOM and Stage IV: teeth in which MB2 canal was not identified by Stage III were further investigated with CBCT. The number of canals identified during each stage was analyzed statistically. RESULTS: Clinical detection of MB2 canal in our study was 90%, with 93% in maxillary first molar and 86% in maxillary second molar. 64% MB2 canals were located at Stage I (direct vision) which improved to 84% at Stage II (under DOM) and 90% at Stage III (selective dentin removal under DOM). CBCT investigation (Stage IV) further improved the identification of MB2 canal leading to overall prevalence of 93%. CONCLUSION: The results of our study demonstrated that MB2 canal can be clinically detected in up to 90% of maxillary molars by the use of DOM and selective dentin removal. CBCT investigation is indicated when MB2 canals are not clinically detected.

Evaluation of root and canal morphology of maxillary permanent first molars in an Emirati population; a cone-beam computed tomography study.

BACKGROUND: The aim of this study was to analyze the root and canal morphology of the maxillary permanent first molars in an Emirati population using cone-beam computed tomography (CBCT). METHODS: Two hundred and sixty-one CBCT scans were acquired. The data were extracted and anonymized to remove all patient identifiers. Two observers (an endodontic resident and an endodontist) evaluated all scans on diagnostic quality monitors. RESULTS: The prevalence of a second mesiobuccal canal (MB2) was 80.1% in all examined samples. Type II Vertucci classification, was the most common canal configuration (59%) in the mesiobuccal root, followed by Types I (19.9%) and IV (15.3%), while Type III was the least common (5.7%). Types I, II, and IV were significantly more common in the 21-40-year age group (P < 0.001), while Type III was observed significantly more often in the < 20-year age group (P < 0.001). No significant effect of gender on the prevalence of Vertucci classification in the mesiobuccal root of maxillary first molars (P = 0.74) was found. Analysis of bilateral symmetry showed that 80% teeth had perfect bilateral symmetry, whereas 20% were asymmetrical. Type II canal configuration showed the highest prevalence of bilateral symmetry (48.7%), followed by Type I (15%) and Type IV (10%), while Type III showed the least prevalence of symmetry (3%). CONCLUSIONS: This was the first study to analyze the prevalence of MB2 canal in an Emirati population. Our results indicate high prevalence of MB2 (80.1%) and emphasize the importance of using advanced techniques to locate the MB2 canal.

Canal mesiovestibular 2 (MV2): como vencer as dificuldades durante seu tratamento / Second mesiobuccal canal (MB2): how to overcome the difficulties in treating it

Os canais radiculares, quando não tratados, podem ter um impacto direto na previsibilidade do tratamento endodôntico. Hoje, já se sabe que o canal mesiovestibular 2 (MV2) é o mais esquecido sem tratamento durante a terapia endodôntica e, quando isso acontece, a probabilidade de aparecimento de doença inflamatória na região periapical é de 4,5 a 6,5 vezes maior do que em dentes que tiveram todos os canais tratados. Sendo assim, o clínico deve conhecer informações importantes relacionadas às complexidades anatômicas que dificultam o acesso e exploração desse canal, bem como conhecer manobras que facilitam o seu tratamento, uma vez que localizar e negociar o MV2 sempre foi um grande desafio. O objetivo do presente estudo é mostrar os principais obstáculos enfrentados para localizar e tratar o canal MV2, e orientar como essas dificuldades podem ser superadas no dia a dia da clínica endodôntica (AU).

When not treated, root canals may affect the predictability of endodontic treatments directly. The second mesiobuccal root canal (2MB) is the canal most often missed and left untreated during endodontic treatments. The probability of inflammatory disease in the periapical region in these cases is 4.5 to 6.5 times greater than in teeth that have all canals treated. Therefore, clinical dentists should know the anatomical complexities that may complicate root canal access and exploration. As 2MB detection and negotiation are a great challenge, they should also be familiar with the procedures that facilitate treatment. This study describes the main obstacles to the location and treatment of the 2MB canal and discusses how these obstacles may be overcome in routine endodontic practice (AU).

Morphological measurements of two separate mesiobuccal canals in maxillary first molars using micro-computed tomography.

OBJECTIVES: To obtain radicular measurements of two separate mesiobuccal (MB) root canals in maxillary first molars using micro-computed tomography (µCT) with customized software. MATERIALS AND METHODS: Human maxillary first molar MB roots (N = 36) with two separate canals (MB1, MB2) and apical foramina were scanned by µCT and analyzed with Kappa2 software to reconstruct three-dimensional (3D) surface models of roots and canals. These models were sectioned at 0.1 mm intervals perpendicular to the central axis of each canal. Canal widths, 3D curvatures, and surrounding dentine thicknesses were measured concurrently on each section. Dentine thicknesses were analyzed statistically for differences between each direction and the different levels of both canals. RESULTS: Dentine walls around MB1 were thicker than MB2 (p < 0.05). Thinnest dentine was most often located at disto-inside direction in both canals. Canal widths were significantly smaller in MB2 than MB1 (p < 0.01). Apical constrictions were smaller (p < 0.05) and further (p < 0.05) from the apex in MB2 than MB1. Canal curvatures were greatest in the apical third of both canals (p < 0.001), and they were greater in MB2 than MB1 (p < 0.05). CONCLUSIONS: MB2 canals had shorter lengths, smaller widths, and more severe curvatures and were surrounded by thinner dentine walls. In MB2, apical constrictions were between 1 and 2 mm from the apex, compared to about 1 mm for MB1. CLINICAL RELEVANCE: These detailed measurements and in-depth 3D analyses of maxillary first molar MB roots with two separate canals and apical foramina provide morphologic references for root canal therapy.

An In Vivo Study: Location and Instrumentation of the Second Mesiobuccal Canal of the Maxillary Second Molar.

AIM: The first purpose of this retrospective observational in vivo study was to determine the incidence of the second mesiobuccal canal (MB2) in maxillary second molars. The second purpose was to propose a modern shaping procedure able to transform a difficult canal, like MB2, into a normal canal. MATERIALS AND METHODS: This study was led from September 2016 to December 2017, for 15 months. It was conducted on fifty-seven successive cases of root canal therapy on maxillary second molars. All procedures were done in conformity with the current state of the art practices in endodontics. These included rigorous clinical and radiographic pre-access analysis, appropriate tooth restoration to ensure watertight rubber dam installation, surgical microscopic manipulations for precision, the systematic use of ultrasonic endodontic tips to manage the access cavity preparation, and a modern step down technique to shape MB2. RESULTS: Fifty-seven maxillary second molars were treated: 3.5% had one canal, 7.0% two canals, 24.6% three canals; 64.9% four canals (MB2 presence). Weine's method was used to classify mesiobuccal root canal morphology: 27.4% had a type I canal configuration, 35.3% type II, 37.2% type III canal configuration. CONCLUSION: The perfect knowledge of endodontic anatomy, a painstaking pre-access analysis of the preoperative radiographs, the systematic identification of the CEJ, using a periodontal probe, the use of surgical microscope coupled with the use of specific endodontic ultrasonic tips and the use of a modern step-down technique allows a high accuracy of the access cavity preparation, canal localization and instrumentation. CLINICAL SIGNIFICANCE: The rate of MB2 localization and instrumentation on maxillary second molars by our surgical protocol is high. The clinician should take the necessary time to locate and negotiate the MB2. The lack of its location can provoke the failure of endodontic treatment.

Negotiation, Centering Ability and Transportation of Three Glide Path Files in Second Mesiobuccal Canals of Maxillary Molars: A CBCT Assessment.

Introduction: The aim of this study was to compare negotiation, centering ability and transportation of three path finder rotary instruments (ProGlider, ScoutRace and M3 Pro-Gold Path File) to create glide path in second mesiobuccal (MB2) canals of maxillary molars with cone-beam computed tomography (CBCT). Methods and Materials: In this in vitro study, 66 maxillary molars with separate second MB2 canals were selected with the following criteria: having 18-21 mm root length, without any resorption or calcification in radiography, without previous treatment and 20-40º curve according to Schneider's method. Then MB2 canals were randomly divided into three groups (n=22). CBCT scan before and after root canal negotiation was taken. A #10 K-file for determination of working length was inserted into all canals. In group1; ProGlider file, group2; ScoutRace file and in group 3; M3 Pro-Gold Path file was implemented. The calculated data from CBCT based on reaching full working length (RFWL) or not (NRFWL) were analyzed using the Pearson Chi-square test. Centering ability was calculated by Fisher's exact test and amount of transportation was determined with the Pearson Chi-square test in SPSS software. Results: ProGlider file had the least RFWL and ScoutRace was the best, but the results were not statistically significant (P>0.05). Regarding the centering ability and transportation, all 3 groups showed no significant differences (P>0.05), except at level of 2 mm from the apex in buccopalatal direction for ProGlider and ScoutRace files (P<0.05). Conclusion: In spite of insignificantly different results, ScoutRace file was better than other groups in negotiating and centering ability in mesiodistal direction of the MB2 canal in maxillary molars. Also, ProGlider file was significantly better than ScoutRace regarding transportation at level of 2 mm from apex in buccopalatal direction.

Endodontic Retreatment of an Upper First Molar with Bifurcated Palatal Canal Using Preoperative Cone-beam Computed Tomography: A Case Report.

BACKGROUND: Anatomic variations in palatal canal morphology in maxillary first molars (MFMs) are relatively rare occurrences. Therefore, omission is common unless clinicians recognize their presence. CASE REPORT: The aim of this report is to point out new signs that can be viewed as indicators of the existence of additional canals in the palatal root (PR) in this upper first molar endodontic retreatment case. Moreover, the role of preoperative cone-beam computed tomography (CBCT) in both discovering and determining the location of those additional canals will also be discussed. CONCLUSION: Besides formerly discussed signs that indicate the existence of this canal, clinicians should also pay attention to other signals on periapical radiograph, including the aberrant divergence of a palatal canal at apical third and an unusual lesion occurring laterally in the periapical area of palatal root.

The Incidence of Second Mesiobuccal Canals Located in Maxillary Molars with the Aid of Cone-beam Computed Tomography.

INTRODUCTION: Many endodontic treatment failures in maxillary molars result from missed second mesiobuccal (MB2) canals. An MB2 canal orifice is present in as many as 95% of maxillary molars, but these canals are not always located during endodontic procedures. Additional tools, such as cone-beam computed tomographic (CBCT) imaging, may be needed to locate these canals in maxillary molars. Hence, the aims of this study were to investigate the frequency of use of CBCT imaging during the treatment of maxillary molars and to evaluate the influence of its use on the detection of MB2 canals. METHODS: Endodontic treatment records, digital intraoral radiographs (when present), and CBCT images from all maxillary first and second molars treated at the University of Washington, Seattle, WA, between 2010 and 2014 (N = 886) were reviewed. Statistical analysis was performed to assess differences between the groups. RESULTS: Overall, an MB2 canal was found in 55.8% of the maxillary molars studied, and CBCT imaging assisted in detecting 11.7% of these canals. CBCT imaging was used in 16.5% of the cases treated and was used significantly more for retreatment cases. CBCT imaging was used preoperatively in 5.6% of cases, and the data show that significantly more MB2 canals were located when a preoperative CBCT image was available. More MB2 canals were located in first molars without full-coverage crowns. CONCLUSIONS: The data show that CBCT imaging is a valuable tool in locating MB2 canals. Based on the results of his study, the use of CBCT imaging could be warranted when treating maxillary molars.

Prevalence of Second Mesiobuccal Canals in Maxillary First Molars Detected Using Cone-beam Computed Tomography, Direct Occlusal Access, and Coronal Plane Grinding.

INTRODUCTION: The purpose of this study was to determine the prevalence of the second mesiobuccal canal (MB2) in 100 maxillary first molars using 3 independent methods and a combination method. METHODS: One hundred extracted human maxillary first molars were collected. The teeth were mounted in the maxillary first molar extraction sockets of a human cadaver head. A cone-beam computed tomographic (CBCT) scan was taken of each tooth. Two radiology faculty independently evaluated the CBCT volume for the presence of an MB2 canal. Additionally, teeth were accessed. If a canal was not found, a preoperative CBCT scan was viewed followed by a second attempt to locate an MB2 canal. Lastly, the mesiobuccal root was dissected by grinding in a coronal plane. RESULTS: A review of CBCT volumes found the presence of an MB2 canal 69% of the time. Accessing the tooth led to an MB2 detection of 78%. When a CBCT scan was viewed, this brought the access detection rate up to 87%. Coronal plane root grinding had an MB2 canal detection rate of 92%. Differences between each method were statistically significant. CONCLUSIONS: The results of this study show that an MB2 canal is present up to 92% of the time. Direct access of teeth found statistically significant more MB2 canals than viewing CBCT volumes alone (P = .032). Therefore, exposing every patient to a preoperative CBCT scan may not be appropriate. However, taking a CBCT scan when an MB2 canal is not found clinically can significantly increase the chances of finding an MB2 canal (P < .001).

Clinical study of root canal numbers in maxillary second primary molars / 口腔疾病防治

Objective@#To investigate the root canal numbers of maxillary second primary molars.@*Methods @#216 max illary second primary molars from 204 children aged 3-8 years old were selected. All the teeth need to do the root canal therapy. After opening the pulp chamber, the root canal were examined and determined with small size K file and 17％ethylene diaminetetraacetic acid (EDTA). Hand instruments were used for root canal preparation and then zinc-oxide iodoform paste was used for filling. @*Results @#216 maxillary second p rimary molars, 122 teeth had three root canals(56.5%), and 94 teeth had four root canals (43.5%). The incidence of second mesiobuccal canal (MB2) was 41.2%. There was no correlation between the incidence of the MB2 canal and gender and tooth position. @*Conclusion@# The root canals of maxillary second primary molars had more variations, and there was a high incidence of the second mesiobuccal canal.