Root Of Maxillary First Molar Research Articles

Microcomputed tomography evaluation of contamination with endodontic obturation material remnants in teeth with different root canal anatomy after post space preparation

Statement of problemWhether the amount of the endodontic obturation material remnants in a root canal prepared for a post is related to variations in the anatomic shape of the canal or whether it varies in different parts of the post space is unclear. PurposeThe purpose of this in vitro study was to estimate the extent of root canal contamination with remnants of the obturation material after post space preparation in relation to the anatomic shape of the root canals by means of microcomputed tomography. Material and methodsFifty freshly extracted teeth were divided into 5 test groups with respect to the root anatomy of different tooth types. The root canals were shaped and obturated with gutta percha. The space for the glass fiber post was prepared with standardized drills, and all specimens were scanned by microcomputed tomography. The areas of residual obturation material on the root canal walls in the coronal and apical parts of the prepared post space were estimated by using a 3D visualization software program. Parametric and nonparametric dispersive analysis (analysis of variance and Kruskal-Wallis) and Wilcoxon tests were used for statistical data evaluation (α=.05). ResultsThe estimates of the root canal surface areas contaminated with residual obturation material after post space preparation were significantly larger in premolars (P≤.01), as compared with mandibular incisors and with the palatal roots of maxillary first molars. The contamination areas in different parts of the root canal (apical and coronal) reported significant differences within and between the test groups. ConclusionsThe extent of root canal contamination with remnants of endodontic obturation material after post space preparation was related to the anatomic shape of the roots and varied in the coronal and apical parts of the prepared post space.

Comparison of bone thickness in infrazygomatic crest area at various miniscrew insertion angles in Dravidian population – A cone beam computed tomography study

Infrazygomatic crest miniscrews are an important advancement in the field of orthodontics for anchorage reinforcement. The size of the miniscrews and the site of placement depend on the bone thickness in the infazygomatic crest area. The bone morphology and the thickness vary among different ethnicities of population. To assess the bone thickness in the infrazygomatic crest area around the distobuccal root of the maxillary first molar using cone beam computed tomography and determine the best possible site and angulation for the placement of the miniscrew. Therefore, to determine the size of the implant that will suit the Dravidian population. The infrazygomatic crest bone thickness was evaluated on 10 patients using cone beam computed tomography. The measurements were made along the distobuccal root of maxillary first molar at different angulations ranging from 75° to 40° to the occlusal surface of the molar. The infrazygomatic crest bone thickness was of 4.5mm to 9mm for the Dravidian population, when measured at an angle of 40° to 75° to the maxillary first molar occlusal plane and of 11 to 17mm above the occlusal plane. Student t-test (confidence interval 95%) was done to determine gender variation and compare the bone thickness of right and left side. ANOVA and post-hoc test were done to find the statistical difference between the bone thickness measured at different insertion angles. The best possible site for miniscrew insertion is 12 to 17mm above the occlusal plane at an angle of 65° to 70°, with no injury to the adjacent anatomical structures, no mucosal irritation and adequate stability for the miniscrew. The ideal infrazygomatic crest screw length for Dravidian population is 9 to 11mm.

Root canal isthmi and interorifice distance in human permanent teeth of an Indian subpopulation using cone-beam computed tomography: A retrospective cross-sectional study.

Objective:The aim of the study was to evaluate the prevalence of root canal isthmus (RCI) and measure the interorifice distance (IOD) between the root canals. Additionally to correlate IOD with the RCI in human permanent teeth using conebeam computed tomography (CBCT) in an Indian sub-population (Chennai).Materials and Methods:A total of 5881 teeth from 280 CBCT full mouth scans were analyzed. The presence or absence of complete and incomplete RCI of each tooth was identified using the map-reading strategy. IOD was calculated by measuring the distance between the center of each root canal orifice to that of the center of the adjacent orifice at the level of the cementoenamel junction using the axial and sagittal sections. Chi-square analysis and correlation statistics using Spearman's rank-order test was done (P < 0.05).Results:High prevalence of RCI was found in maxillary first premolars, mesial root of mandibular molars, and mesiobuccal root of maxillary first molars, while its prevalence was low in maxillary canines and mandibular premolars and absent in maxillary incisors. RCI was predominantly seen in the cervical and middle third of the root canal in all the teeth evaluated. A weak negative correlation was established between the IOD and RCI for maxillary premolars, whereas a weak positive correlation was seen in maxillary first molars and mandibular second molars.Conclusion:The prevalence of RCI was high in the posterior teeth in comparison to the anterior teeth in the present study. There was no strong correlation between IOD and RCI in all the teeth evaluated.

CBCT Assisted Endodontic Management of Teeth for Aberrant Roots: Case Series

Cone Beam Computed Tomography (CBCT) is a radiographic imaging technique which provides accurate, high-quality, three-Dimensional (3D) images of various parts of head and neck. They deliver images with a spatial resolution of teeth required for diagnosis, treatment planning and postoperative evaluation. The aim of this case series is to describe the importance of determining the root canal morphology with the help of CBCT. This case series presents the endodontic management of a three rooted maxillary first premolar, maxillary first molar with single palatal root and three canals and mandibular first molar with five canals using CBCT. The axial images from CBCT show Gulabivwala K Type I (3-1) canal pattern in distal root of mandibular first molar (36) and palatal root of maxillary first molar (26) according to Al-Quadah Awawdeh showed Type XXII (3-2-1) canal configuration. Biomechanical preparations of all the teeth were done with hand as well as rotary file systems and lateral compaction obturation technique was used. With the advancing technology in imaging, there are possibilities to detect and treat a number of variations particularly in posterior teeth leading to successful endodontic treatment.

Cone-beam computed tomography study of tooth root and canal morphology of permanent molars in a Serbian population

Background/Aim. For successful endodontic therapy, it is necessary to know root morphology. Therefore, the aim of our study was to analyze root canal morphology and root canal length of permanent molars in a Serbian population, using cone-beam computed tomography (CBCT). Methods. The study included a total of 305 maxillary molars, and 280 mandibular molars receiving cone-beam computed tomography examination and determined root numbers, canal morphology according to Vertucci classification, and canal lengths. Results were correlated with sex and tooth location in the jaw. Results. The mesiobuccal roots of first maxillary molars showed Vertucci type I in 45.7%, followed by type II in 29% of cases. For the second molar, Vertucci type I was found in 60.5% of cases in mesiobuccal canals. Palatal and distobuccal canals mostly presented Vertucci type I configuration. The mesial roots of mandibular molars had the highest frequency of two canals with Vertucci type IV as the most frequent for the first molar, and Vertucci type II for the second molar. Distal roots most commonly had one canal in both molars. Palatal canal length was the highest in maxillary first molars, with the mean value of 20.62 mm, while in second molars, the highest length value was for the mesiobuccal canal (20.09 mm). In both mandibular molars the mesial root canal was the longest one. Differences were found according to sex and tooth location in the jaw. Conclusion. Mesiobuccal roots of maxillary first molars had two canals; it was more frequently compared to second molars. Mesial roots of mandibular molars showed same frequency of two canals, and diversity in Vertucci types. Male patients tended to have higher complexity of root canal morphology compared to that of females. CBCT can improve understanding of the root canal morphology.

Relationship between canal morphology and isthmus in mesio-buccal roots of maxillary first molars in 9- to 12-year-old children: An in-vivo cone-beam computed tomography analysis

ObjectivesThis study aims to analysis the distribution of root canal isthmuses (RCIs), and its relationship with canal morphology in the mesio-buccal roots of maxillary first molars in children aged 9–12 in a Chinese sub-population. Methods494 healthy, untreated maxillary first molars with fully developed mesio-buccal roots were examined. Cone-beam computed tomography (CBCT) scans were acquired as part of diagnosis and treatment plannings unrelated to the present study. The images were evaluated to identify the canal morphology of mesio-buccal roots according to Vertucci’s classification. A map-reading strategy was used to identify RCIs. ResultsIn mesio-buccal roots, the most common canal morphology was type Ⅳ (38.5 %). The frequency of type I (1.6 %) was much lower than adults. RCIs were found in 92.5 % mesio-buccal roots. The RCIs which began in the cervical third and ended in the middle third (CT-MT) (31.0 %) had the highest frequency. In type III, the RCIs which began and ended in the middle third (MT-MT) (30.3 %) were most common. For type V, 30.8 % RCIs began in the cervical third and ended in the apical third (CT-AT). No significant differences were found between sexes and sides (P > 0.05). ConclusionsFor children aged 9–12, the frequency of type I canals was much lower in mesio-buccal roots of maxillary permanent first molars, while the frequency of RCIs was higher than adults, especially in the apical third. The distribution of RCIs had its own characteristics in each canal type, closely related to the structures.

Proximity of Vascular Bone Channel in the Lateral Sinus Wall to Root Apices of Maxillary First Molars: A Cone-beam Computed Tomographic Analysis

IntroductionApical surgery is frequently indicated in maxillary first molars. Occasionally, a vascular anastomosis in the lateral maxillary sinus wall can be observed during surgery. The aim of this study was to examine the distance between the vascular bone channel (VBC) and the root apices of maxillary first molars using cone-beam computed tomographic imaging. MethodsCone-beam computed tomographic images of 104 maxillary first molars were oriented in the coronal plane to evaluate the distance between the roots and the VBC. The measurements were only recorded in relation to the buccal roots. In addition, demographic parameters and further measurements such as the diameter of the VBC and the proximity to the periapical pathology were evaluated. ResultsA total of 210 VBCs were assessed. The mean distance from the VBC to the apices of the buccal roots of the maxillary first molars was 6.18 mm ± 3.84 mm. The VBC was mostly located intrasinusally (74.3%) and only rarely superficially (0.5%). The diameter of the VBC was on average 0.88 ± 0.32 mm. ConclusionsIn this study, the VBC was usually found closer to the mesiobuccal than to the distobuccal root apex. During preparation of the access window, the existence of the VBC should be kept in mind because the mesiobuccal roots of maxillary first molars undergo apical surgery to the buccally positioned roots only.

Efficacy of R-Endo and E3-ReRoot Retreatment Rotary NiTi Systems in Intracanal Filling Material Removal

Aim: To compare the effectiveness of R-Endo and E3-ReRoot retreatment rotary files in filling material removal and operating time.Materials and Methods: Twenty extracted distobuccal roots of maxillary first molars were decoronated to a standard length of 12 mm. Root canal preparations were done using Fanta Blue (Fanta; ShangHai, China) till 0.04/25. Matching gutta percha cones of 0.04/25 were used with Adseal resin sealer (Meta Biomed, Chungcheongbuk-do, Republic of Korea) in warm vertical compaction technique. Teeth were left in an incubator at 37 °C and 100% humidity for 30 days. Cone beam computed tomographic images of all roots were obtained to confirm three-dimensional filling of the root canal space. Roots were divided into two groups according to the file used in retreatment; group A using R-Endo (Micro-Mega, Besancon, France) and group B using E3-ReRoot (IMD; ShangHai, China). Time required to remove the filling material was recorded in seconds. Teeth were then split into two halves using hammer and chisel and remaining filling material was calculated using stereomicroscope at 4X original magnification. Statistical analysis was performed using One-Way ANOVA and significance level was set at 0.05.Results: E3-ReRoot was shown to be significantly more effective than R-Endo in intracanal filling removal. No significant difference was shown between both systems in the time needed to reach the working length. Conclusion: E3-ReRoot was more effective in intracanal filling removal although both systems failed to totally remove gutta percha and sealer remnants from the root canals.

The second mesiobuccal canal in three-rooted maxillary first molar of Karnataka Indian sub-populations: A cone-beam computed tomography study

IntroductionElusive second mesiobuccal canal (MB2) in maxillary first molar are often missed during endodontic therapy and are a major cause of treatment failures. Its prevalence is known to vary among different populations and there is limited information on its prevalence in Indian population. AimThis study investigated the prevalence and location of second mesiobuccal (MB2) canal in mesiobuccal root of maxillary first molar using cone beam computed tomography (CBCT) images in an Indian population. Materials and methodsCBCT images of 598 three rooted maxillary first molars were studied. In each CBCT image, the floor of pulp chamber was located and advanced by 2 mm to standardize the observation for MB2 canal. Its location was determined in relation to mesiobuccal (MB1) and palatal (P) canal. Statistical analysisThe data was analysed using descriptive statistics. The presence of MB2 canal was correlated with age, gender and tooth position using Chi square test. ResultsThe prevalence of MB2 canal in three rooted maxillary first molar was 61.9%. It was seen that the prevalence of MB2 was highest in 20–40years age group (67.4%) followed by > 40 years (57.5%) and lowest in <20 years (50.6%) and the difference was statistically significant (p = 0.005). It is located mesiopalatally; 2.5 mm ± 0.6 mm palatally and 1.0 ± 0.4mmmesially to the MB1 canal or present directly on the line joining the MB1 and palatal canal. ConclusionThere is a high probability of finding MB2 canal in Indian patients. The access cavity must be modified from a triangular shape to rhomboid shape. Troughingmesiopaltally (about 2.5 mm palatally and 1 mm mesially) from MB1 to a depth of about 2 mm from the floor of pulp chamber may be necessary for locating MB2 canal.

Anatomic Analysis of Palatal Roots of Maxillary Molars Using Micro–computed Tomography

IntroductionThe morphology of the palatal root of maxillary first and second molars was analyzed and compared using micro–computed tomographic scanning. MethodsForty-seven extracted maxillary molars were scanned with a micro–computed tomographic device to analyze the palatal radicular dentin dimensions, canal working width, root length, canal curvature, lateral canals, and apical constriction anatomy. Quantitative data were analyzed with mean and standard deviation for first and second molars, respectively. Comparison was made between first and second molars using an unpaired t test. ResultsThe palatal root of maxillary first molars was found to have statistically significantly thinner dentin than second molars on the palatal aspect of the root 8–11 mm from the apex, correlating to the coronal and middle thirds of the root. First molar palatal roots also had a statistically significantly wider canal mesiodistally than second molars at 13–15 mm from the apex, correlating approximately to the level of the cementoenamel junction and pulpal floor. Significant canal curvature was present. These findings suggest the need for conservative coronal flaring and instrumentation. ConclusionsThe absence of an apical constriction in 76.6% of the specimens highlights the importance of creating an apical seat through instrumentation to maintain obturation materials. A minimum master apical file size of 40 is recommended based on preoperative working widths in the apical 0.5–1.0 mm. A root-end resection of 3.5 mm would remove a greater majority of lateral canals.

Apical root canal anatomy in the mesiobuccal root of maxillary first molars: influence of root apical shape and prevalence of apical foramina - a micro-CT study.

To determine whether a relationship exists between the apical shape of roots and root canal system complexity by performing a micro-computed tomography analysis. One hundred extracted permanent maxillary first molars were scanned using a micro-computed tomography device at 19.6μm voxel size. Two groups of mesiobuccal roots were formed according to the root aspect ratio value in the apical 3-mm cross-sectional level ('<2 and≥2.00'). Data were recorded regarding the number and presence of accessory canals and their location, isthmus, presence of the mesiobuccal canal and dentine thickness. Depending on the analysed variable, Mann-Whitney U test and Z-test for proportions were used to compare groups. The significant level was set at 5%. Mesiobuccal roots with an aspect ratio≥2.00 at the apical 3-mm cross-sectional level had higher percentages of accessory canals, apical foramina and MB2 root canals in the apical 3mm. The vertical average distance from the accessory foramina and origin from the anatomic apex was 1.40 and 2.19mm, respectively. Overall, 21.8% of the accessory canals had their origin coronal to a 3-mm root resection line. There was no difference between the groups regarding dentine thickness. The shape of the apical 3mm of maxillary first molar mesiobuccal roots was a predictive factor for the presence of complex root canal systems. Roots with a lower aspect ratio had less complex apical anatomy.

Adaptation of Single-Cone Gutta-Percha in Curved Canals Prepared and Obturated with Protaper and Heroshaper Systems by Using Cone Beam Computed Tomography.

Objective:The aim of this study is to prepare and obturate the curved canals of the mesiobuccal root of maxillary first molar with four different file systems that is protaper hand files, rotary pro taper (RP) files, heroshaper hand files, and rotary hero shapers files and to evaluate the adaptation of their single-cone Gutta-percha by cone beam computed tomography (CBCT).Materials and Methods:Eighty teeth were selected and were divided into two groups (G1A1, G1A2 and G2A1, G2A2 as hand and RP file system, G1A3, G1A4 and G2A3, G2A4 as hand and rotary hero shaper files system) of fourth teeth each. After access opening working length of the mesiobuccal canal was established. The distobuccal and palatal roots of the samples were removed using the diamond disc at the furcation level. “Endoanalyser” software was used to measure Schneider's angle on the preoperative radiograph. This angle was measured by drawing two lines-one parallel to the long axis of the canal, in the coronal third, and the second line from the apical foramen to intersect the point where the first line left the long axis of the canal. The canals of each group were then prepared according to the manufacturer's instructions for protaper hand files, RP files, heroshaper hand files, and rotary hero shapers files systems. Direct digital radiography image of all the samples was obtained. And then, the samples were exposed to CBCT to evaluate their single-cone adaptations. The data were analyzed using SPSS 20, IBM, Armonk, NY, United States of America.Results:The null hypothesis that there will not be any gap area in the adaptation of their single-cone of different file system was rejected. Minimal gap area was seen in rotary hero shapers file system (0.001 mm2) and was maximum in hand protaper (HP) file system (0.015 mm2).Conclusion:CBCT is a useful tool in detecting the gap area after obturation in curved canals. The HP single-cone adaptation showed the maximum gap area and rotary heroshaper single-cone adaptation showed the minimum gap area.

Micro-CT analysis of danger zone thickness in the mesiobuccal roots of maxillary first molars.

To evaluate dentine thickness from both distal ('danger zone') and mesial ('safety zone') aspects of the MB1 and MB2 canals of maxillary first molars at the furcation level using micro-CT imaging. One hundred maxillary first molars with two canals in the MB root were selected from a Brazilian subpopulation and scanned at a resolution of 19.6μm in a micro-CT device. From each specimen, two axial cross-sectioned images were selected at 2 and 3mm apical to the furcation level of the MB root and evaluated for the smallest dentinal thickness. Measurements were made from the outer perimeter of the MB1 and MB2 canals towards the external root surface from both distal (danger zone) and mesial (safety zone) aspects of the root. The influence of an isthmus was also considered in the analysis, and samples were classified according to the presence or absence of an isthmus in the axial sections. Non-parametric Wilcoxon signed-rank tests were used to compare dentinal thickness between MB1 and MB2 canals with a significant level set at 5%. Colour-coded 3D models of dentine thickness throughout the MB root were created and evaluated qualitatively. At both levels, median dentine thickness of the MB2 canal was significantly lower in both distal and mesial aspects of the root in comparison with the MB1 canal (P<0.01). The presence of an isthmus was not a variable that influenced dentinal thickness. Colour-coded models indicated that dentine thickness was dependent on the cross-sectional shape of the MB root. At least 50% of the sample had <1mm of dentine thickness at the danger zone of the MB2 canal. Danger zones in the MB roots of maxillary first molars were not symmetrical. MB2 canals had less dentine thickness on both aspects of the root compared to the MB1 canal.

Association between missed canals and apical periodontitis.

To evaluate the frequency of post-treatment apical periodontitis associated with root filled teeth with at least one untreated root canal. Eight hundred and seven cone beam computed tomography images containing at least one root filled tooth were selected from a collection of 1543 images from Brazilian individuals. Scans were taken using ICAT Classic devices (Imaging Sciences, Hatfield, PA, USA) in a private oral radiology clinic from January to April 2015. All root filled teeth were analysed for the presence of missed canals and apical periodontitis. The chi-square and odds ratio tests were used to verify if there were an association and risk relationship between the occurrence of untreated canals and apical periodontitis. A total of 2294 teeth with evidence of root fillings were identified. Two hundred and eighty-one teeth had at least one untreated missed canal (12%). The frequency of apical periodontitis in teeth with at least one untreated canal was significantly greater in comparison to teeth with all canals treated (274/281, 98% versus 1736/2013, 86%) (P<0.01). The odds for apical periodontitis to be present was 6.25 times greater for teeth with an untreated canal. The mesiobuccal roots of maxillary first molars had the greatest frequency of untreated canals (114/154, 74%), with the second mesiobuccal canal being the most frequently missed (n=106/114, 93%). Root filled teeth with at least one missed canal had a high prevalence of post-treatment apical periodontitis.

An original micro‐CT study and meta‐analysis of the internal and external anatomy of maxillary molars—implications for endodontic treatment

The aim of this work was to conduct a radiological micro-CT study and meta-analysis to determine the morphological features of the root canal anatomy of the maxillary molars. The radiological study included micro-CT scans of 110 maxillary first molars and 98 maxillary second molars. To identify articles eligible for inclusion in our meta-analysis, PubMed, Embase, and Web of Science were search comprehensively. The following data were extracted: study type (cadaveric, intraoperative or imaging), Vertucci types of canal configuration, presence/number of canals, roots, apical foramina, apical deltas, and inter-canal communications. The mesiobuccal root was the most variable with respect to canal configuration, type I being the most common configuration followed by type II and type IV. Type I was the most common canal configuration in the distobuccal and palatal root. Regarding the number of canals in the maxillary first and second molars, one canal was most prevalent in all roots of the three molars, except for the mesiobuccal root of maxillary first molar, in which two canals were most prevalent. The most prevalent number of roots in all maxillary molars was three. Knowledge of endodontic anatomy determines the parameters of root canal treatment and significantly affects the probability of success. It is therefore especially important to know the morphology of the root canal system in order to perform endodontic treatment correctly. Clin. Anat. 31:838-853, 2018. © 2018 Wiley Periodicals, Inc.

ANATOMICAL STUDY OF THE MESIOBUCCAL ROOT IN MAXILLARY FIRST MOLAR WITH DIFFERENT METHODS IN EGYPTIAN POPULATION

Aim: to study the canal anatomy and its variations of mesiobuccal root of maxillary first molar using visual, CT, CBCT, and staining and clearing. Materials and Methods: Three hundred extracted permanent maxillary first molar teeth were selected for this study. Mesio-buccal roots were resected 1 mm coronal to the trifurcation level. The orifices of the canals were located with a size 10 K-type file which was passively advanced into the canals until the tip of the instrument penetrated the apical foramen for visual examination. The number of orifices and apical foramina in each root were recorded. All roots were embedded in a sheet of pink wax with vertical orientation and arranged in their numbers to facilitate three dimensional CT and CBCT scan and the data were stored on a magnetic optical disc. Both, CT and CBCT images were assessed by a calibrated dental radiology specialist blinded to the order of roots using Vitrea 2 V 3.8 imaging software. India ink was injected into the orifices of the root canals with a plastic disposable endodontic irrigating syringe with a 27-G needle with suction tip which was placed at the root apex to draw the ink through the root canal system. All roots were decalcified with 5% hydrochloric acid for three days, dehydrated in ascending concentrations of ethanol (75%, 85%, 96% and 100%) for four hours each, and transparent specimens were obtained by immersing the dehydrated roots in methyl salicylate solution, in which the roots were stored until they were examined. The data regarding root canal morphology of each sample from all evaluation methods were tabulated and compared statistically. Results: There were significant differences between the four methods used for studying the root canal anatomy of mesiobuccal root of first maxillary molars as regarding the number of canals, number of orifices, number of apical foramina, presence of lateral accessory canals and intercanal communications. Roots with three canals and three orifices and opened apically with two foramina showed no significant differences between the four methods. Also, with Kappa test, there was good and fair agreement between CBCT & CT and CBCT & staining and clearing respectively. Conclusion: the most detailed information can be obtained in-vitro by staining and clearing and high resolution CT and CBCT methods which are commonly used as a diagnostic aid in clinical endodontics

A Successful Root Canal Therapy of a Maxillary First Molar With 3 Separate Root Canals in the Mesiobuccal Root: Case Report

Introduction: An important issue in treatment planning and endodontic treatment is to deal with sophisticated internal dental morphology. Deviations from normal anatomy in maxillary molars are usually related to the number of canals in mesiobuccal root. Although unusual anatomy is not uncommon in maxillary molars, the occurrence of 3 separate canals with distinct orifices and apical foramina (as we see in this case) is extremely rare. Getting familiar with this unusual anatomy helps clinicians to treat patients more efficiently with less chance of failure. Case Presentation: This case report describes a successful endodontic management of an uncommon variation of the maxillary first molar with a third mesiobuccal canal. The tooth had a deep carious lesion and the pulp was irreversibly damaged causing pain on the left side of the face. The periodontium was normal. The tooth received root canal treatment and 400 mg ibuprofen was prescribed every 6 hours for 2 to 3 days. The patient remained asymptomatic and the 3-month follow-up radiograph revealed normal periodontium. Conclusions: Inability to identify and treat additional canals that are very common in the MB root of maxillary first molar could lead to treatment failure.

Apically extruded debris in filling removal of curved canals using 3 NiTi systems and hand files.

The aim of this study was to assess the amount of apically extruded debris during filling removal with WaveOne Gold (WOG), ProTaper Universal Retreatment (PTR), D-RaCe Retreatment (DRR) or hand files (HF), to compare the working time during filling removal, and to describe failures of NiTi instruments. Forty mesiobuccal roots of maxillary first molars were prepared with WOG Primary, obturated and divided into 4 groups (n=10), according to the instruments used: WOG, PTR, DRR or HF. Distilled water was used as irrigant and the extruded debris were collected in Eppendorf tubes and dried. The amount of extruded debris was determined by subtracting the final from the initial weight. The time of filling removal for each canal was recorded and the instruments used were analyzed pre and post-operatively by SEM. Kruskal-Wallis and Dunn's test analyzed extruded debris data and ANOVA, followed by Tukey's test, compared the working time data (a=0.05). Instrument deformation and fracture were described. WOG produced significantly less debris compared with HF and DRR (p<0.05), and similar to PTR (p>0.05). HF, PTR and DRR showed no significant difference (p>0.05). Working time in HF group was significantly higher than others (p<0.05). SEM analyses showed, from the 18 instruments evaluated, 3 fractures and 10 deformations. All instruments tested caused debris extrusion. WOG was associated with less extrusion than DRR and HF. Filling removal with HF was slower than with the other instruments. All NiTi systems presented fracture and deformation.

Mesiolingual Canal Prevalence in Maxillary First Molars assessed through Different Methods

Evaluate the prevalence of mesiolingual canal prevalence orifice in mesiobuccal roots of maxillary first molars using five methods of visualization. About 73 first permanent maxillary molars were analyzed. Visual clinical analysis of the presence of the fourth canal was performed using a straight end-odontic exploratory probe (EXDG16®) and a K10 manual file (SybronEndo®). Dental elements that were not located on the fourth canal were analyzed with the aid of a magnifying glass (Zeiss®) with a 2.5-fold increase and those teeth in which the fourth canal was not found went through the examination with clinical surgical microscope (OPTO®) with magnification of 20 times with both the explorer and endodontic file. Next, a periapical radiography of the teeth was performed in the teeth in which the mesiolingual canal was not yet found to observe the presence or absence of the fourth canal. Afterward, the teeth in which the canal was not yet located were scanned using the microtomography equipment (SkyScan®), at 100 kV and 100 μA, with an isotropic resolution of 16 μm. The mesiolingual canal was located in 70 teeth (95.8%) and in only 3 teeth it was not identified. The visual method in the fourth canal search has limitations, whereas the composite magnifying glass, the clinical surgical microscopy, and the computerized microtomography are efficient methods for locating the fourth canal in the upper first molars. The anatomical complexity of the first maxillary molars is one of the factors that leads to high failure rates in the endodontic treatments of this group of teeth. In most clinical situations, the mesiolingual canal goes unnoticed by professionals, since conventional radiographs do not always allow the visualization of all root canals. Determining an effective method for locating the mesiolingual canal is of paramount importance to the success of endodontic treatment.

Maxillary First Molars with 2 Distobuccal Canals: A Case Series

An appreciation of the anatomic complexity of the root canal system is essential at every step of endodontic treatment. Endodontic treatment of teeth with unusual root canal anatomy presents a unique challenge. Eight patients underwent nonsurgical root canal treatment of 3-rooted maxillary first molars in a specialty endodontic private practice. Four cases of Weine type II and 4 cases of Weine type III canal configurations in the distobuccal root of maxillary first molars were presented.This article highlighted an uncommon anatomic variation of 2 canals in the distobuccal root of the maxillary first molar.