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Background: The success of root canal therapy in endodontics is heavily dependent on identifying a second mesiobuccal canal (MB2) in permanent maxillary molars. A comprehensive understanding of internal anatomy, particularly the recognition of MB2, is crucial for the effective treatment of this commonly encountered tooth. This study aimed to investigate the prevalence and occurrence of the second mesiobuccal canal in permanent maxillary first and second molars. Methods: This cross-sectional study that was conducted at the Department of Conservative Dentistry & Endodontics, Military Dental Centre Dhaka, Bangladesh from January 2018 to December 2018. The analysis involved a total of 200 maxillary first molars and 200 maxillary second molars. In the initial phase for both groups, teeth were examined with the naked eye followed by microscopic assessment. Data analysis was conducted with MS Office tools. Results: In naked eye observation, the frequency of MB2 canals in the first molar teeth was found 64%, and in the second molar teeth it was found 56%. On the other hand, by microscopic assessment, the frequency of MB2 canals in the first molar teeth was found 96%, and in the second molar teeth, it was found 84%. Conclusion: The occurrence of the second mesiobuccal canal (MB2) in permanent maxillary first molars is more common than in the second molars. Microscopic assessment proves to be more effective than naked eye assessment for detecting the presence of MB2 in both maxillary first and second molars. [ABSTRACT FROM AUTHOR]

Objectives: To determine the frequency of second mesiobuccal canal (MB2) in a sample of 223 extracted maxillary permanent 1st molars. Study Design: In-vitro Cross-sectional study. Setting: Department of Endodontic at Peshawar Dental Hospital. Period: June 2019- Nov 2019. Material & Methods: The samples were processed with application of the Clearing Technique which includes demineralization with nitric acid, dehydration with ethanol and clearing with methyl salicylate. The samples were classified according to Weine's system of root canal classification. Results: Among the 223 samples, 30% were found to have Weine's type1 root canal in the mesiobuccal root (second mesiobuccal canal absent). Second mesiobuccal canal was present in majority of the samples (70%) with Weines type2 (2-1) predominant with 23.32%, Weines type3 (2-2) present in 15.7% and Weines type 4 (1-2) present in 21% of the samples. 9% of the samples could not fit into Weines classification so they were placed in Vertuccis classification for root canal system type 6 (2-1-2). Conclusion: The present study concludes that the second mesiobuccal canal is more frequently found in maxillary permanent 1st molar teeth than our textbooks report, irrespective of quadrant and gender. Therefore, time should be given to evaluation of its anatomy by the clinician before starting the root canal treatment for the greater good of the community. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the prevalence of MB2 canals in permanent maxillary molars utilising CBCT; in patients attending a university hospital. A total of 200 patient scans, (100 female and 100 male patients), were enrolled in the study. In total, 800 teeth were analysed, and teeth with additional canals in their MB roots (MB2) were identified. First maxillary molar teeth exhibited the highest prevalence of MB2 canals, 92% and 87%, for teeth 16 and 26, respectively. Second maxillary molar teeth showed a lower prevalence of MB2 canals, 69% and 65%, for the 17 and 27, respectively. There were no associations of significance between the prevalence of MB2 canals and patient age or gender. Root morphology and anatomy of permanent maxillary first and second molar teeth was found to be highly variable. The prevalence of additional canals in the MB roots is a frequent finding which has previously been underreported. [ABSTRACT FROM AUTHOR]

Aim: The targets of the endodontic therapy are damaged tissue and bacteria removal from the canals and dentinal tubules and the prevention of recontamination after the treatment. Introduction: Correct endodontic treatment has to follow several parameters: proper diagnosis, isolation of operating field, full chemo-mechanical preparation of the complex endodontic system, three-dimensional obturation of the root canals, post endodontic restoration. Respecting all these parameters short and long term success can be achieved. Materials and methods: In this article an orthograde retreatment of maxillary first molar has been described, which showed at pre-operative X-ray, an incongruous endodontic therapy, the failed finding of the fourth canal and the presence of periapical lesions. Discussion: A high percentage of failures is due to missed root canals and therefore not cleansed, shaped and it is essential to use modern technologies to achieve safe and reproducible results. Conclusions: The endodontic retreatment of this right maxillary first molar was performed with the proper protocols and sophisticated tools, with which we can achieve success in the short- and long-term treatments.

Aim To determine whether a CBCT volume can aid in the location of MB2 canals in maxillary molars. Methodology This prospective clinical study involved 50 patients that needed RCT on a maxillary molar. The teeth where the MB2 was located upon access with the dental operating microscope received routine root canal treatment, and teeth where MB2 was not located had a CBCT volume made after instrumenting the located canals. At the second appointment, the clinician used the aid of the CBCT volume and troughing to attempt to locate MB2. Results The clinicians located MB2 upon initial access in 70% ( n = 35) of teeth. In the remaining 15 teeth, CBCT and troughing located MB2 53% of the time in that group (8/15 teeth). Overall, MB2 was located in 86% of the 50 first and second maxillary molars (maxillary first molars 90% and maxillary second molars 73%). A total of 15 CBCT volumes were made, and of these teeth, 33% of MB2 canals (5/15 teeth) were visualized on the CBCT volume. Conclusions This prospective clinical study showed that the effectiveness of using CBCT to locate additional MB2 canals in maxillary molars appears limited. The use of the dental operating microscope in conjunction with selective troughing and CBCT imaging allowed clinicians to locate 90% (maxillary first molars) and 73% (maxillary second molars) of MB2 canals. [ABSTRACT FROM AUTHOR]

Background: MB2 is a novel Plasmodium falciparum antigen of unknown function expressed in pre-erythrocytic and blood stages of infection in the human host. Interferon-gamma (IFN-γ) and interleukin (IL)-10 responses to other P. falciparum antigens have been associated with protection from clinical malaria, but these responses have not been studied for MB2. The present study was undertaken to characterize IFN-γ and IL-10 responses to P. falciparum MB2 antigen in adults living in areas of differing malaria transmission in Western Kenya. Materials and Methods: Cytokine responses to two 9-mer MB2 peptides predicted to be human leukocyte antigen (HLA) class I restricted T-cell epitopes were measured by enzyme-linked immunosorbent assay (ELISA) (IFN-γ and IL-10) and enzyme-linked immunosorbent spot (ELISPOT) (IFN-γ) in adults (n = 228) in areas of unstable and stable malaria transmission. HLA class I restriction of responses was assessed in a sub-group of the study population. Results: IFN-γ and IL-10 responses to MB2 peptides by ELISA were observed in both sites with no significant difference in prevalence (IFN-γ, unstable transmission area, 18.8%, stable transmission area, 27.5%, P = 0.33; IL-10, unstable transmission area, 22.5%, stable transmission area, 25.0%, P = 0.78). Prevalence of IFN-γ responses by ELISPOT was also similar in both areas (unstable, 10.8%, stable, 10.9%, P = 0.98). Neither IFN-γ nor IL-10 responses showed evidence of HLA class I restriction. Conclusions: MB2 induces IFN-γ and IL-10 responses in adults living in both stable and unstable malaria transmission areas. Future studies should assess if these responses are associated with protection from clinical malaria.

The aim of this study was to assess the morphology of the mesial root canal system of maxillary molars and the frequency of MB2 canals using cone-beam computed tomography (CBCT). A total of 1374 teeth, first maxillary (1MS, n= 802) and second maxillary molars (2SM, n= 572) of 508 Chilean patients between 8 to 77 years were evaluated through CBCT. The mesiobuccal root was evaluated in all three thirds. Root canal morphology was classified according to Vertucci's method. Data were analyzed by Pearson's Chi-square and Cuzick trend tests. MB2 canal frequency in 1MS was 73.44% and in 2MS 42.48%. The most frequent morphology in 1MS and 2MS were Vertucci type II and I, respectively. No statistically significant association was found between frequencies and side or according to gender (P>0.05). A positive association was found as the age increased in both 1MS and 2MS (P<0.001 and P= 0.023, respectively). Given the anatomical complexity of the mesiobuccal root and the frequent presence of the MB2 canal, the clinician must assume the existence of two canals in this root. CBCT scanning is a good way to initially identify this canal in the different root thirds. [ABSTRACT FROM AUTHOR]

In the present study, we develop a Steam-generator Thermohydraulics Analysis code based on Fluent (STAF) for predicting the three-dimensional localized thermal–hydraulic characteristics in the primary and secondary sides of steam generator. STAF code is developed based on the porous media model in Fluent. The flow resistances caused by the tubes, support plates, downcomer and separators are introduced to the momentum equation as additional source terms of shell side fluid; the heat transfer from primary to secondary side fluid is considered as the source term of energy equation of secondary side fluid. The flow and heat transfer in primary side, as well as the tube-to-shell-side heat transfer are solved by the user-defined functions in Fluent. STAF is used to simulate the Westinghouse MB2 test, and localized thermohydraulics parameters are obtained. The numerical results show good agreement with experimental results, demonstrating the ability of STAF to model the three-dimensional flow and heat transfer characteristics in primary and secondary side of steam generator. Besides, parameters associated with flow-induced vibration are also analyzed. [ABSTRACT FROM AUTHOR]

Occurrence of the second mesiobuccal canal (MB2) is a frequent finding. Literary reports have shown it to be found more in the cases of the maxillary first molar. However the maxillary second molars have also been found with this variation in a number of canals. This paper presents a case report on the occurrence of a second mesiobuccal canal or the MB2 in the maxillary second molar.

Objectives. To measure the co-ordinates of the root canal orifices and to determine the incidence of mesiobuccal-2 (MB2) in maxillary first molars in a Turkish sub-population. Materials and methods. Standard digital photographs were taken under a stereomicroscope from the occlusal aspect of each tooth ( n = 176) before and after crown removal. Canal orifices were negotiated under moderate magnification using dental loupes. The coordinates of the orifices and the distances of each from the central fossa were measured by using geographic software. Intensity maps of the orifice locations were created by using the co-ordinates of all canal orifices. A representative map was drawn using the mean values of orifice locations and access projection area. Results. In the right maxillary first molars, the mean values for the (X, Y) co-ordinates were (0.67, 2.68) for mesiobuccal-1 (MB1), (0.81, 0.84) for MB2, (−1.12, 1.26) for distobuccal-1 (D1), (−0.89, 0.23) for distobuccal-2 (D2) and (0, −2.50) for palatinal (P); the corresponding mean values in the left maxillary first molars were (−0.78, 2.56), (−0.98, 0.90), (0.99, 1.18), (0.69, 0.78) and (0.00, −2.53), respectively. The average MB1-MB2 distance was 1.97 mm. Distobuccalcanal orifices were localized at the distal side of the center in 98.3% of teeth. The incidence of MB2 was 46.02%. Conclusions. The distobuccal canal orifice is mostly located on the distal side of the central fossa. Thus, it should be considered that the access cavity of the maxillary molars may not be always limited mesially. The incidence of MB2 in this sub-population was 46.02%, which is of great importance clinically. [ABSTRACT FROM AUTHOR]

Background: MB2 is a novel Plasmodium falciparum antigen of unknown function expressed in pre-erythrocytic and blood stages of infection in the human host. Interferon-gamma (IFN-γ) and interleukin (IL)-10 responses to other P. falciparum antigens have been associated with protection from clinical malaria, but these responses have not been studied for MB2. The present study was undertaken to characterize IFN-γ and IL-10 responses to P. falciparum MB2 antigen in adults living in areas of differing malaria transmission in Western Kenya. Materials and Methods: Cytokine responses to two 9-mer MB2 peptides predicted to be human leukocyte antigen (HLA) class I restricted T-cell epitopes were measured by enzyme-linked immunosorbent assay (ELISA) (IFN-γ and IL-10) and enzyme-linked immunosorbent spot (ELISPOT) (IFN-γ) in adults (n = 228) in areas of unstable and stable malaria transmission. HLA class I restriction of responses was assessed in a sub-group of the study population. Results: IFN-γ and IL-10 responses to MB2 peptides by ELISA were observed in both sites with no significant difference in prevalence (IFN-γ, unstable transmission area, 18.8%, stable transmission area, 27.5%, P = 0.33; IL-10, unstable transmission area, 22.5%, stable transmission area, 25.0%, P = 0.78). Prevalence of IFN-γ responses by ELISPOT was also similar in both areas (unstable, 10.8%, stable, 10.9%, P = 0.98). Neither IFN-γ nor IL-10 responses showed evidence of HLA class I restriction. Conclusions: MB2 induces IFN-γ and IL-10 responses in adults living in both stable and unstable malaria transmission areas. Future studies should assess if these responses are associated with protection from clinical malaria. [ABSTRACT FROM AUTHOR]

To present an endodontically managed maxillary second molar with a second mesiobuccal canal diagnosed with a cone beam computed tomography (CBCT) scanning. This report also highlights the role of CBCT as an objective method to confirm the three-dimensional (3D) anatomy of teeth which will aid in identifying presence of additional root canals. The CBCT proved to be relevant in providing important information on the root canal system for the planning of endodontic treatment in cases of persistent infection due to untreated root canals. [ABSTRACT FROM AUTHOR]

Aim To investigate variations in root canal configuration in the maxillary permanent molar teeth of a Chinese subpopulation using cone-beam computed tomography (CBCT). Methodology A total of 269 patients with healthy, untreated, well-developed maxillary molars were enrolled, including those suffering facial trauma, and those who required a pre-operative assessment for implants. Radiographic examination by CBCT was conducted as part of their routine examination, diagnosis and treatment planning. Overall, 299 maxillary first and 210 maxillary second molar teeth were examined in vivo by CBCT. The number of roots, the number of canals per root, the canal configuration and the presence of additional mesiobuccal canals were recorded. Vertucci's classification for root-canal configurations was utilized. Results All maxillary first molars had three separate roots; however, 52% of mesiobuccal (MB) roots had two canals with the remainder having one. All distobuccal and palatal roots had Vertucci Type I canal configurations. When the MB2 canal was present, 14, 69 and 16% of MB roots had Type II, IV and V canal configurations, respectively. The root canal system of the maxillary first molar teeth could be categorized into two variants: one with three separate roots with one canal in each of the distobuccal and palatal roots and two canals in the MB root, and the other with three separate roots with one canal in each root. Of 210 maxillary second molars, 10% had one root, 8% two roots and 81% three roots. Of the MB roots, 22% had two canals with the remainder having one. When the MB2 canal was present, 18%, 58%, 10% and 3% of MB roots had type II, IV, V and VI canal configurations, respectively. The root canal system of the maxillary second molar could be categorized into eight variants. Conclusions Mesiobucccal roots of maxillary molar teeth had more variation in their canal system than the distobuccal or palatal roots. The root canal configuration of the maxillary second molars was more variable than that of the first molars. CBCT can enhance detection and mapping of the mesiobuccal root-canal system with the potential to improve the quality of root canal treatment. [ABSTRACT FROM AUTHOR]

The maxillary second molar (2 MM) has the most complex root canal system, and a high percentage of treatment failures is due to the impossibility of locating, instrumenting and obturating the second mesiobuccal canal (MB2). The aim of this study was to describe in vivo the prevalence and location of the MB2 canal in the mesiobuccal root of the permanent maxillary second molar through CBCT image analysis. Two hundred twenty five CBCT images of 2 MM were studied. In the presence of the MB2 canal, the floor of the coronal cavity was located and advanced every 1 mm apically to standardize observation. The geometric location in relation to the primary mesiobuccal (MB1) and palatal (P) canals was done by locating the central points of the canal and projecting a line between them, together with a perpendicular line between MB1-P (point T). The data were analyzed using descriptive statistics, with a value of P < 0.05 being statistically significant. The MB2 canal was identified in 48% of the cases. It was located 2.2 ± 0.54 mm palatally and 0.98 ± 0.35 mesially to the MB1 canal. The average age of the subjects where it was found was 26.36 ± 10.85 years. Its location was more frequent in men (63%), and no differences were observed in its appearance in the hemi-arch. It is necessary to know the high probability of finding the MB2 canal in the maxillary second molar, and the CBCT is a good diagnostic tool for its detection and exploration.

Objective: Aim of the study was to determined by microcomputed tomography (µCT) the horizontal distance between the main (MB1) and the second mesiobuccal canal (MB2) orifices, the vertical distance between the MB1 and MB2 orifices planes, and the distance between the anatomic apex and major apical foramen (AF). Furthermore, we characterized the entire internal and external anatomy of the MB, distalbuccal (DB) and palatal (P) maxillary first molars roots., Materials and Methods: Twenty-two intact extracted first maxillary molars were scanned by X-ray computed transaxial µCT and then 2D and 3D images were processed and analyzed., Results: The results showed that 77.27% of the mesiobuccal (MB) roots presented a second MB canal, and 29.41% of the MB2 were independent from the MB1 canals. In 15 teeth, there were three root canal orifices on the chamber floor, and 10 of these teeth presented MB2 canals. The mean vertical distance between the MB1 and MB2 planes was 1.68 ± 0.83 mm. Seven teeth had four orifices. The mean horizontal interorificial distance between the MB1 and MB2 orifices was 1.21 ± 0.5 mm. Accessory canals were observed in 33.33% of the roots, loops in 6.06%, while isthmuses were found in 15 of the 22 MB roots. Of the total roots, 74.24% presented one foramen, while all of the roots showed a major apical foramen that was not coincident with the anatomic apex., Conclusions: Our µCT analysis provided interesting features on the horizontal and vertical distance between the MB1 and MB2 orifices and on the distance of AF and anatomic apex., Clinical Relevance: These results have an important clinical value because might support the endodontist in the recruitment, negotiation and obturation of maxillary first molar canal system.