MB2 Canal Research Articles

Morphological characteristics of the mesiobuccal root in the presence of a second mesiobuccal canal: a micro-CT study.

ObjectivesThis study investigated the internal morphology of mesiobuccal (MB) roots of maxillary molars with a second mesiobuccal (MB2) canal.Materials and MethodsForty-seven maxillary first or second molars from Brazilians were scanned using micro-computed tomography. The following measurements were obtained from the MB roots: root thickness, root width, and dentin thickness of the buccal aspect of the first mesiobuccal (MB1) canal, between the MB1 and MB2 canals, and the palatal aspect of the MB2 and MB1 canals at 3 mm from the root apex and in the furcation region. For statistical analysis, the Student’s t-test and analysis of variance with the post-hoc Tukey test were used (α = 0.05).ResultsIn maxillary molars with an MB2 canal, MB roots were significantly thicker (p = 0.0014) and narrower (p = 0.0016) than in maxillary molars without an MB2 canal. The dentin thickness of the palatal aspect of the MB1 canal was also significantly greater than that of MB roots without an MB2 canal at 3 mm from the root apex (p = 0.0007) and in the furcation region (p < 0.0001). In the furcation region of maxillary molars with an MB2 canal, the dentin thickness between the MB1 and MB2 canals was significantly smaller than that in the buccal and palatal aspects (p < 0.0001).ConclusionsThe internal morphology of MB roots of maxillary molars with an MB2 canal revealed differences in dentin thickness, root diameter, and distance between the canals when compared with maxillary molars without an MB2 canal.

Apical periodontitis in mesiobuccal roots of maxillary molars: influence of anatomy and quality of root canal treatment, a CBCT study.

This study aimed to evaluate the prevalence of apical periodontitis (AP) in the mesiobuccal roots of root canal-treated maxillary molars. One thousand cone-beam computed tomography images of the teeth were examined by 2 dental specialists in oral radiology and endodontics. The internal anatomy of the roots, Vertucci's classification, quality of root canal treatment, and presence of missed canals were evaluated; additionally, the correlation between these variables and AP was ascertained. A total of 1,000 roots (692 first molars and 308 second molars) encompassing 1,549 canals were assessed, and the quality of the root canal filling in the majority (56.9%) of the canals was satisfactory. AP was observed in 54.4% of the teeth. A mesiolingual canal in the mesiobuccal root (MB2 canal) was observed in 54.9% of the images, and the majority (83.5%) of these canals were not filled. Significant associations were observed between the presence of an MB2 canal and the quality of the root canal filling and the presence of AP. AP was detected in more than half of the images. The MB2 canals were frequently missed or poorly filled.

Cone-Beam Computed Tomographic Evaluation of Canal Morphology of Mesiobuccal Root of Maxillary Molars in Saudi Subpopulation.

Introduction:The purpose of this study was to analyze the canal configuration of mesiobuccal root (MBR) of the maxillary molars in the Saudi subpopulation using cone-beam computed tomography (CBCT) and to compare if there is any gender and arch variation.Methodology:In this cross-sectional retrospective evaluation study, analysis of CBCT scans of MBRs of 400 maxillary first and second molars was done that has undergone CBCT scanning for diagnostic/treatment purposes in the private clinic of Jeddah, KSA. Statistical analysis was performed using Student's t-test and Chi-square test.Results:Type I, II, and III canal configurations have been reported to be the most common morphologies in the MBR in both first and second molars, with the incidence of 20.25% (81), 17.25% (69), and 17.25% (69), respectively. Type I canals were significantly (P < 0.001) more common in tooth #17 and #27, Type II canals were significantly (P < 0.001) more seen in tooth #26, Type 3 canals were more seen in tooth #27, but there is no statistically significant association. Supplemental canal configurations which were classified by Gulabivala as Type I, Type II, and Type IV were also seen. Furthermore, 93 additional unclassified canal configurations were also found.Conclusion:The data indicate high prevalence of MB2 canals with varying canal configurations. Preoperative CBCT imaging should always be done in tooth-like maxillary molars, to understand the complex configurations and variations and to achieve higher success while performing root canal treatment.

Dentine Thickness of Second Mesibuccal Canals in First Maxillary Molars Prepared with Rotary Instruments.

The purpose of this study was to evaluate the thickness of the remaining dentine wall in the danger zone of the second mesiobuccal (MB2) canals using cone-beam computed tomography (CBCT) in maxillary first molars following preparation by means of HERO 642 rotary instruments with different tapers. The study samples included twenty-five mesiobuccal roots of maxillary first molars. A two-step method was employed to prepare the MB2 canals applying HERO 642 instruments: using a 0.02 taper (step 1), and a 0.04 taper (step 2). The roots were scanned before preparation, and after each step. The thickness of the dentine wall was recorded at the CEJ level, as well as 2 mm and 4 mm below the CEJ. The repeated-measures ANOVA in conjunction with the Cochran tests were used to compare the changes in the thickness of the root canal wall. There was no area with dentine thickness of <0.5 mm before preparation. A significant reduction in dentine thickness occurred following the preparation with both 0.02 and 0.04 files at all three levels compared with the pre-instrumentation values (P< 0.05). However, areas with dentine thickness of < 0.5 mm after preparation using 0.04 files were significantly more than those resulting from the application of 0.02 files both at the CEJ and 2 mm-below-CEJ points, but the differences were not significant at the 4mm-below-CEJ level. Within the limitations of the present in vitro study, the use of larger taper instruments in MB2 root canals of maxillary first molars increased the quantity of samples with dentine thickness less than 0.5 millimeter at the coronal level of the root canal. It was concluded that instruments with large tapers, should be used with caution in troughing or preparing such root canals to reduce the risk of strip perforation.

AN IN VITRO COMPARATIVE STUDY FOR PREVALENCE OF SECOND MESIOBUCCAL CANAL IN MAXILLARY FIRST MOLAR

Introduction: The root canal structure must be properly cleaned, shaped, and obturated for endodontic therapy to be successful. Clinicians need to be well-versed on root canal morphology to do this. The advent of visual enhancement in endodontics, along with the use of operating microscope has enhanced clinician’s ability to locate all the canals.&#x0D; Objective: The present research aims to evaluate the best method of detection of MB2 canals amongst direct vision (DV), Dental Operating Microscope (DOM) and Cone Beam Computed Tomography (CBCT).&#x0D; Methods: Around 90 human maxillary first molar were used in this study, which were extracted due to caries or had to be extracted due to periodontally weakened condition, were collected from the department of Oral and Maxillofacial surgery, School of dental science, KIMSDU, Karad. Samples were made free of debris and calculus by scaling. All the samples were stored in 0.9% saline before use.&#x0D; Results: In the present study, the detection of second mesiobuccal (MB2) canal was done using three different methods. The prevalence of MB2 by directed vision showed 33.33% cases. The use of operating microscope showed 56.67% presence of MB2 canals in maxillary first molar and use of Cone Beam Computed Tomography (CBCT) showed 86.67% MB2 canals. The prevalence of MB2 by directed vision showed 33.33% cases. Use of operating microscope showed 56.67% presence of MB2 canals in maxillary first molar and use of CBCT showed 86.67% MB2 canals. The present study showed the presence of MB2 was 56.67%.&#x0D; Conclusion: On the bases of the present study one can conclude that CBCT is a promising modality to detect MB2 canals.

Prevalence of Untreated Mesio-Buccal 2 Canal in Maxillary First Molars Reported in KSA Since 2010: A Systematic Review

Several aspects are involved in the success of an endodontic therapy. Because root canal treatment is so complicated, it can't be evaluated using two-dimensional radiographs. Endodontic failure can occur if any section of the canal is overlooked and left untreated. The root canals of the first and second molars are the most complicated of all the maxillary teeth. Locating the mesio buccal (mb2) canal in the maxillary teeth for endodontic treatment is difficult. The mb2 canals are located utilizing three-dimensional technology and cone beam computed tomography (CBCT). The primary goal of this research is to conduct a systematic evaluation of publications that have reported on the occurrence of mb2 canal in maxillary first molars. Many studies in Saudi Arabia have found that the incidence of mb2 in maxillary first molars ranges from 23.3 percent to 70.6 percent, and that the incidence in maxillary second molars is about 19.8%. A few studies also found that direct viewing of the root, followed by troughing, was used to find an mb2 canal that was not visible on a CBCT scan.

Comparative evaluation of the efficiency of cone-beam computed tomography, clinical analysis, and dental loupes in detecting the MB2 canal in maxillary first molars. An in-vitro study

The success of an Endodontic treatment relies on the position and morphology of root canals. It is important for a clinician to be familiar with the canal morphology to negotiate and thereby filling the canals with an inert material. But, the possibility of negotiating the canals with the use of conventional technique alone is difficult. Hence, careful examination with the use of advanced techniques to enhance vision is required to minimize the rate of treatment failures. To compare the efficiency of three methods Cone-Beam computed Tomography (CBCT), clinical analysis, AND Dental Loupes in detecting the MB2 canal in maxillary first molars.One hundred and fifty extracted intact permanent molars were collected. Two examiners i.e., one Endodontist and a Radiologist examined CBCT images of teeth for the number and position of root canals. The first stage included unaided examination using an explorer and K- files. While those teeth that were failed to locate the canals were examined using dental loupes for better magnification. The results were analyzed by McNemar's tests with Bonferroni correction, and Chi-square test using SPSS software v21.Among 150 extracted teeth that were compared,MB2 was detected using CBCT in around 68% of the teeth, while with the use of naked eye and dental loupes, it was found to be around 30% and 66% respectively and the difference in the detection rates was statistically significant.With the view of the parameter under consideration, CBCT has high detection rates followed by dental loupes and naked eye vision. The efficiency of CBCT scans and dental loupes in detecting a second mesio-buccal canal, thus making it more likely to be treated by the clinician.

An In-vitro study to compare the effect of four moisture contaminants on the shear bond strength of composite resin

The success of an Endodontic treatment relies on the position and morphology of root canals. It is important for a clinician to be familiar with the canal morphology to negotiate and thereby filling the canals with an inert material. But, the possibility of negotiating the canals with the use of conventional technique alone is difficult. Hence, careful examination with the use of advanced techniques to enhance vision is required to minimize the rate of treatment failures. To compare the efficiency of three methods Cone-Beam computed Tomography (CBCT), clinical analysis, AND Dental Loupes in detecting the MB2 canal in maxillary first molars.One hundred and fifty extracted intact permanent molars were collected. Two examiners i.e., one Endodontist and a Radiologist examined CBCT images of teeth for the number and position of root canals. The first stage included unaided examination using an explorer and K- files. While those teeth that were failed to locate the canals were examined using dental loupes for better magnification. The results were analyzed by McNemar's tests with Bonferroni correction, and Chi-square test using SPSS software v21.Among 150 extracted teeth that were compared,MB2 was detected using CBCT in around 68% of the teeth, while with the use of naked eye and dental loupes, it was found to be around 30% and 66% respectively and the difference in the detection rates was statistically significant.With the view of the parameter under consideration, CBCT has high detection rates followed by dental loupes and naked eye vision. The efficiency of CBCT scans and dental loupes in detecting a second mesio-buccal canal, Thus making it more likely to be treated by the clinician.

METHODS TO STUDY ROOT CANAL ANATOMY: A SYSTEMATIC REVIEW

Introduction: A variety of methods has been used to study the root canal anatomy. Before radiography became rmly established in dental practice, techniques such as injection-moulded models, diaphanization, and sectioning were used to study the internal anatomy of teeth. Twodimensional radiography was a convenient method to study the root canal anatomy, but it provided limited information due to distortion, superimposition, and lack of 3-dimensional information. Cone beam computed tomography, and more recently micro-CT have been used in most of the recent studies on root canal anatomy as they are non-invasive and provide multiplanar data. Each of these methods has its own merits and knowing when to choose which method whilst planning a study is important. Methods: The systematic review was registered in PROSPERO. Three electronic databases were accessed, and a hand search was performed in peer-reviewed journals in endodontics. Studies that met the pre-dened inclusion and exclusion criteria were selected or rejected, respectively. The screened articles were subjected to Risk of Bias (ROB) assessment for evaluation of their scientic merit. Results: The selected studies included data from at least 288478 teeth studied, of which, 206270 teeth were studied by CBCT, 30980 teeth were studied by clearing technique, 3616 teeth were studied by sectioning, 9027 teeth were studied by Micro CT, and 1191 teeth were studied by resin or plastic inltration. The commonest parameters studied were canal morphology, presence as well as morphology of MB2 canals in maxillary molars, C-shaped canal morphology in mandibular molars, presence of extra roots and canals, isthmuses, and racial characterisation of the study population. Conclusion: With the advent of 3-dimensional radiographic techniques such as CBCT and micro-CT, these methods have become the mainstay of root canal anatomy studies, especially as these techniques have become less expensive and more widely available. Certain techniques such as clearing are relevant even today as they provide excellent details on the intricacies of the canal system. Depending on the study characteristic to be studied, the appropriate method must be employed.

Comparison of second mesiobuccal canal prevalence of maxillary molar teeth by gender and age in a Turkish subpopulation: A cone-beam computed tomography study

Aim: The purpose of this study is to examine the distribution of second mesiobuccal (MB2) canal frequency according to age and gender in the maxillary molars of individuals in South-eastern Anatolia, Turkey, using cone-beam computed tomography (CBCT). It also seeks to inform dentists who perform root canal treatments about the prevalence of additional canals that affect the success of treatments. Methods: 300 patients who had already had CBCT images taken were grouped by gender and age. A total of 1,034 maxillary molar teeth were evaluated in the axial section. The chi-square test was used to evaluate the morphological differences between different age groups and genders. Results: The total frequency of MB2 canals was found to be 44.4% in 300 people (42.5% in women; 47.2% in men). In addition, the frequency of MB2 canals was 59.2% (n = 506) in maxillary first molars and 30.4% (n = 528) in maxillary second molars. On the basis of the right and left jaws, the incidence of MB2 canals was 44.2% in the right jaw and 44.9% in the left jaw. No statistically significant differences were found between gender and age. Conclusion: It is concluded that using CBCT will increase the detection of the presence of additional canals, increasing dentists’ success rates in performing root canal treatments. Furthermore, it has been observed that using new technologies and spending more time in the detection of MB2 canals will increase the success of root canal treatments in maxillary molar teeth. How to cite this article: Akay A, Öz H, Adıgüzel Ö, Erkan Akay S. Comparison of second mesiobuccal canal prevalence of maxillary molar teeth by gender and age in a Turkish subpopulation: A cone-beam computed tomography study. J Med Dent Invest 2021;2:e211062. https://doi.org/10.5577/jomdi.e211062 Linguistic revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English. Checked for plagiarism: Yes

Occurrence and Morphology of MB2 Canals in Maxillary First Molars in an Indian Subpopulation: A Cone Beam Computed Tomography Study

AbstractIntroduction Molars have been known to display varied morphologies. Maxillary first molar is the tooth with the largest volume and most complex root and root canal anatomy; also, possibly the most treated and least understood posterior tooth. The present study aimed to investigate the occurrence and morphology of MB2 canals in maxillary first molars in an Indian subpopulation (Dakshina kannada) using cone beam CT (CBCT) imaging.Materials and Methods A total of 330 maxillary molars were placed on “U-” shaped modelling wax template, mimicking the natural arch and digitally scanned, of which 196 scans met the inclusion criteria and were analyzed for unusual root canal anatomy by CBCT. To analyze the occurrence and morphology of the canals, the acquired data was examined by two endodontists and discussed till an agreement was reached.Results The results were subjected to descriptive analysis. The majority of patients 103 (52.6%) teeth showed the presence of MB2 canals. As much as 83.5% of teeth depicted Vertucci's type II morphology, and 16.5% teeth presented with Vertucci's type IV morphology.Conclusion CBCT overcomes the limitations of conventional radiography. However, the decision to use CBCT in the management of endodontic problems must be based on a case-by-case basis and only when sufficient diagnostic information is not obtained from diagnostic tests.

Influence of access cavity preparation on the dentine thickness of mesial canals of mandibular molars prepared with reciprocating instruments

To evaluate the influence of traditional and conservative access cavity preparations on the remaining dentine thickness in the coronal third of mesial canals of extracted mandibular molars prepared with reciprocating instruments using micro-computed tomography as the analytical tool. Seventy extracted mandibular molars were scanned at a pixel size of 19μm. From this initial sample, 20 teeth were selected, pair-matched and distributed into two groups (n=10) according to the access cavity preparation: traditional (TradAC) or conservative (ConsAC). The root canals were sequentially enlarged with Reciproc Blue R25 (size 25, 0.08v taper) and R40 (size 40, 0.06v taper) instruments. A new scan was performed and the postoperative stacks were coregistered with their respective preoperative datasets. A colour-coded cross sections of the roots were created and used to identify and measure the smallest dentine thickness related to both MB and ML canals at 1.0-mm intervals from the furcation level of up to 5mm in the apical direction, in both mesial and distal aspects of the roots, before and after preparation. The statistical analyses were performed with paired-samples t-test, independent-samples Student T-test and Chi-Square test with a significance level of 5%. At all levels of both groups, dentine thickness before preparation was greater than after preparation (p<.05). No difference in the percentage of dentine reduction was observed between TradAC and ConsAC groups (p>.05), but a significantly greater reduction was observed to the distal aspect of the roots (p<.05). After root canal preparation, dentine thinner than 0.5mm was observed mostly along the distal aspect of the root (10% to 15%) of the MB and ML canals, with no influence of the access cavity type on its incidence to either mesial (X2 =1.66; p=.2) or distal (X2 =0.40; p=.5) directions. In the TradAC group, dentine thickness in most slices was greater than 1.0mm after preparation (n=124) whilst, in the ConsAC, it ranged from 0.5 to 1.0mm (n=136). Traditional or conservative access cavity preparation in extracted mandibular molars did not influence the remaining dentine thickness in the coronal third of mesial canals enlarged with thermomechanically treated nickel-titanium reciprocating instruments.

The Examination of Root Morphology of the Maxillary First and Second Molars Using Cone Beam Computed Tomography

Introduction: Maxillary molars usually have three roots, four canals and the extra canal often exists in the mesiobuccal root. This study aimed to investigate the root morphology of maxillary first and second molars using CBCT. Materials &amp; Methods: In this descriptive-analytical study, CBCT samples of 200 patients referred to maxillofacial radiology centers were selected and evaluated. Two-dimensional images in panoramic, cross-sectional, and transverse axial planes and three-dimensional images of the maxilla building that were reconstructed by a computer were examined. Analyzed data using one-way ANOVA and t-test (p value &lt; 0.05) Results: The highest number of roots in the first molar was 3 (89.5%) and, the highest number of the second molar was 3 (90%). The maximum number of root canals in the first molar was 4 (65%) and, the highest number of root canals in the second molar was 3 (68%). The MB2 canal of maxillary first molars was 67.5% and the MB2 canal of maxillary second molars was absent at 71.5%. The presence of MB2 canal of maxillary first and second molars had no significant difference (p value &gt; 0.05), but the presence of MB2 canal of maxillary first and second molars was significant (p value &lt; 0.001). Conclusion: There is a significant relationship between being unilateral and bilateral with the presence of the mesiobuccal canal. Most of the first maxillary molars and, maxillary second molars had three separate roots. Also, there was no significant relationship between gender and side of study with the presence of mesiobuccal canal.

Maxillary molar root and canal morphology of Neolithic and modern Chinese

ObjectiveThis 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. DesignMaxillary 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. ResultsCrown 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. ConclusionsMaxillary 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.

Shaping ability of four single-file systems in the instrumentation of second mesiobuccal canals of three-dimensional printed maxillary first molars.

BackgroundThis study evaluated and compared the shaping ability of four advanced single-file nickel-titanium (NiTi) systems during the preparation of curved second mesiobuccal (MB2) canals in maxillary first molar replicas fabricated by three-dimensional (3D) printing via micro-computed tomography (Micro-CT) imaging.MethodsA total of 60 3D-printed maxillary first molar replicas were constructed from one extracted tooth, with an angle of curvature ranging from 15° to 25°. The MB2 canals from these 60 replicas were divided into 4 groups of 15 replicas according to the canal instrumentation system used, namely, Waveone gold (WOG), Reciproc blue (RCB), XP-endo shaper (XPS) and M3-L. The specimens were scanned before and after preparation using Micro-CT. The pre- and post-instrumentation images of each specimen were superimposed, and the amount of resin removed, the change in surface area, the canal transportation, and centering ability were assessed using the Mimics software. Instrumentation time was also recorded. One-way analysis of variance and least significant difference (LSD) tests were used to statistically compare the groups. The significance level was set at 5%.ResultsInstrumentation time with M3-L was significantly longer than the other systems (P<0.05). The amount of resin removed and the change in surface area generated by the 4 systems were different at the apical, middle, and coronal thirds, and the total canal (P<0.05). Overall, WOG and XPS resulted in the less change than RCB and M3-L. There was no significant difference among the groups at the middle third regarding canal transportation and centering ability (P>0.05). However, a significant difference was found at the apical level (P<0.05), where RCB showed the poorest centering ability and the highest canal transportation (P<0.05). In addition, XPS resulted in the least canal transportation (P<0.05) at the coronal level, while there was no significant difference between the four groups in terms of centering ability.ConclusionsThe M3-L instrument required more time to prepare the curved MB2 canals compared with the other systems. Overall, WOG and XPS showed the least resin removal and surface area change. M3-L, XPS, and WOG instruments respected the original canal curvature better than RCB files.

Micro-CT assessment of radicular pulp calcifications in extracted maxillary first molar teeth.

The present study aimed to evaluate the frequency, position, and length of radicular pulp calcifications in three-rooted maxillary first molars using micro-computed tomography. Two hundred three-rooted maxillary first molars were scanned at a pixel size of 10µm and reconstructed using similar parameters. Three-dimensional models of the mesiobuccal (MB1, MB2, MB3), distobuccal (DB), and palatal (P) canals were qualitatively evaluated for discontinuity in the canal path. Transaxial and sagittal cross-sectional images of the roots were further screened, and the complete obliteration of the canal lumen by pulp calcification was identified when the canal had similar radiodensity to the surrounding dentine. Then, the number, position, and length of the calcifications were recorded for each root. Intra-observer agreement was performed using Cohen's kappa test, while one-way ANOVA and Duncan tests compared the lengths of calcifications among the canals, with α = 5%. Intra-observer agreement was perfect for identification of pulp calcifications (ĸ = 1.0; p = 0.000). MB2 and MB3 canals accounted for the highest percentage frequency of calcifications distributed throughout the canal path. In the MB1, DB, and P canals, they occurred mainly at the apical third. Lengths of calcifications were greater in the MB3 (0.89 ± 0.81mm) and MB2 (0.82 ± 0.93mm) canals than in the MB1 (0.39 ± 0.32mm), DB (0.34 ± 0.22mm), and P (0.28 ± 0.22mm) canals (p < 0.05). MB2 and MB3 canals accounted for the highest frequency and length of radicular pulp calcifications. In the MB1, DB, and P canals, calcifications occurred mostly at the apical third, while in the MB2 and MB3, most of calcifications were observed at the orifice level and along the canal path. In maxillary first molars, radicular pulp calcifications are mainly located at the apical third of the MB1, DB, and P canals, while in the MB2 and MB3 canals, most of them are at the orifice level or along the canal path.

The effect of rotary instrumentation on dentin thickness in the danger zone of the MB2 canal of maxillary first molars.

The aim of this study was to measure the initial and remaining dentin thickness in the danger zone of the second mesiobuccal (MB2) canal of maxillary first molars after rotary instrumentation using cone beam computed tomography (CBCT) imaging. After determining initial dentin thickness, each sample was subjected to a standardized protocol of rotary instrumentation files: ProTaper Gold Sx Orifice Opener (maximum depth of 7 mm); Vortex Blue 15.04, 20.04, 25.04, ProTaper Gold S1, S2, F1, F2, and finally Vortex Blue 30.06. Subsequent CBCT measurements were made to compare changes in remaining dentin thickness in comparison to initial presentation. Preoperative dentin thickness in the danger zone had a mean of 0.82 ± 0.17mm. Significant levels of dentin removal in the danger zone were noted after all instrumentation groups when compared to the pre-instrumentation mean (Sx P < 0.001, 25.04 P < 0.0006, F2 P < 0.0001, 30.06 P < 0.0001). It was concluded that a thin area of dentin exists along the distal wall of the MB2 (danger zone) from the furcation to 4 mm apically.

Prevalence of Second Mesio-Buccal (Mb2) Canal in Permanent Maxillary First Molar

Objective: The aim of this study is to determine the prevalence of second mesio-buccal canal in permanent maxillary first molars. Study Design: Cross sectional study. Place and Duration: Dr Ishrat ul Ebad Khan Institute of Oral Health Sciences, Karachi during the period from February 2020 to January 2021 Patients and Methods: Three hundred and fifty cases of both genders were presented in this study. Patients were aged between 18-60years. Patients’ detailed demographics including age, sex and body mass index were recorded after taking written consent. Local anesthesia was given for isolation of rubber dam. The pulp chamber floor was clearly visualized and the access cavity was ready. The location of the MB2 channel in three phases was done. Complete data was analyzed by SPSS 22.0 version. Results: Mean age of the patients were 30.14±17.47 years with mean BMI 25.61±8.25 kg/m2. Among 350 cases, Majority of the patients 225 (64.3%) were male while the rest 125 (35.7%) were females. Majority of the patients were from age group 20-30 years and less patients were between 51-60 years old. Frequency of second mesiobuccal canal was found in 280 (80%) patients. Conclusion: We concluded in this study that prevalence of MB2 channel was reported in 80% in the initially permanent maxillary molars. Most MB2 canal apertures are distal from the main MB channel and most MB2 apertures are palatal. Key words: Permanent maxillary first molar, MB2 canals, Frequency

Influence of Voxel Size and Filter Application in Detecting Second Mesiobuccal Canals in Cone-beam Computed Tomographic Images

IntroductionThis study assessed the influence of voxel size and filter application in detecting second mesiobuccal (MB2) canals in cone-beam computed tomographic (CBCT) images. MethodsUsing the OP300 CBCT system (Instrumentarium, Tuusula, Finland) and 3 voxel size protocols (80 μm, 125 μm, and 200 μm), we scanned 40 first molars: 20 with an MB2 canal and 20 without. All molars received silver palladium pins on the palatal root, whereas the non-MB2 molars were also filled with gutta-percha. Five oral radiologists assessed the presence of an MB2 canal under 3 filter application conditions: without filter, with sharpen 1 × filter, and with sharpen 2 × filter. Intra- and interobserver reproducibility was evaluated using the weighted kappa index. We compared the area under the receiver operating characteristic curves with SPSS Statistics v.20.0 (IBM Corp, Armonk, NY) using 2-way analysis of variance and the Tukey post hoc test with 5% significance level. ResultsOur analysis found median intra- and interobserver agreement values of 0.70 and 0.56, respectively. The 80-μm voxel with sharpen 1 × filter image group had the highest sensitivity, accuracy, and negative predictive values. As for specificity and positive predictive, the 80-μm voxel group without filter application presented the highest values. The areas under the receiver operating characteristic curve were higher in the 80-μm groups than in the 125-μm and 200-μm voxel size groups (P < .05). We found no differences among the filters used (P = .22) or for the filter–voxel size interactions (P = .88). ConclusionsA smaller voxel size increased the accuracy in detecting MB2 canals, whereas the enhancement filters did not.

Influence of ultraconservative access cavities on instrumentation efficacy with XP-endo Shaper and Reciproc, filling ability and load capacity of mandibular molars subjected to thermomechanical cycling.

To evaluate the influence of ultraconservative access cavities (UltraAC) on canal shaping and filling ability and load capacity of mandibular molars after root canal preparation with XP-endo Shaper (XP) or Reciproc (RC), under simulated clinical conditions. Traditional access cavities (TradAC) were used for comparison. Forty extracted mandibular molars were scanned by micro-computed tomographic and, based on similar anatomical features, were divided into four groups (n=10), according to the type of access cavity and canal instrumentation protocol: TradAC/RC, TradAC/XP, UltraAC/RC and UltraAC/XP. All root canal procedures were performed with the teeth placed in a dental mannequin. Teeth were scanned after root canal instrumentation and filling. Unprepared canal area, dentine removed, accumulated hard tissue debris (AHTD), canal transportation, presence of voids and filling material remnants within the pulp chamber were analysed. After restorative procedures, the teeth were subjected to thermomechanical cycling and to a load capacity test. Statistical analyses were performed using two-way anova test, considering the randomized blocks design (P<0.05). The percentage of unprepared canal area was significantly lower in TradAC groups when compared to UltraAC groups (P<0.05), regardless of the instrument used. The UltraAC/XP group had significantly lower percentage of root dentine removed when compared to other groups (P<0.05). UltraAC/XP and TradAC/XP groups had significantly lower percentages of AHTD than UltraAC/RC and TradAC/RC groups (P<0.05). Regarding canal transportation, in the MB root canals, the TradAC/XP group had significantly lower values than other groups (P<0.05). In general, in ML and distal root canals, TradAC/XP and UltraAC/XP groups had significantly lower values of canal transportation when compared to other groups (P<0.05). Moreover, the UltraAC/RC had the greatest canal transportation values in MB and distal canals. The UltraAC groups had significantly greater percentages of voids and volume of remaining root filling material within the pulp chamber after cleaning procedures than TradAC groups (P<0.05). There was no difference in the load capacity amongst groups (P<0.05). The UltraAC/XP and UltraAC/RC groups had significantly greater areas of unprepared canal walls, significantly more voids and volume of root filling material remnants within the pulp chamber after canal filling. UltraAC/XP was associated with significantly less root dentine removal and significantly more AHTD whilst TradAC/XP had overall significantly less canal transportation. No differences were observed in the load capacity amongst groups.