Mesial Canals Research Articles

Comparative Evaluation of Different Irrigant Agitating Devices for Debris Removal from the Mesial Roots of Mandibular Molars: An In Vitro Study.

To evaluate the efficiency of debris removal from the mesial root canals and isthmus of mesial roots of mandibular molars after final irrigant agitation with XP-endo Shaper, EndoVac (EV), plastic finishing file, and conventional needle irrigation. Forty extracted human mandibular first molar teeth with the isthmus between the mesial roots were selected, access cavities were prepared and distal roots were decoronated. All the mesial root specimens were mounted in acrylic, sectioned at the coronal, middle, and apical thirds, along with the resin block, and examined for debris in the canals and isthmus before the start of the procedure using a stereomicroscope and were mounted back in a custom-made jig. After determination of the working length, they were allocated to the following four different irrigant activation groups (n = 10): Group I-XP-endo Finisher; group II-EndoVac; group III-plastic finishing file; and group IV-standard needle irrigation. After biomechanical preparation (BMP) till F3, final agitation was done for debris removal with the respective agitating devices, and all the samples were examined under a stereomicroscope for the amount of debris in the canal after final agitation. Of all the irrigation devices used, the XP-endo Finisher and EV showed more debris removal when compared to other groups (p < 0.05). The plastic finishing file in continuous rotation was more efficient in cleaning debris compared with conventional needle irrigation (p < 0.05). The XP-endo Finisher and EV showed a significant difference in cleaning efficacy than the plastic finishing files. So, these can be used as adjunctive for agitating the final irrigant. The irrigant agitation devices promote the penetration of irrigants into the intricate root canal anatomy and increase their antibacterial and tissue-dissolving effectiveness thereby improving the success rate and treatment outcome.

To flat or not to flat? Exploring the impact of flat-side design on rotary instruments using a comprehensive multimethod investigation.

To assess the influence of a flat-side design on the geometry, metallurgy, mechanical performance and shaping ability of a novel nickel-titanium rotary instrument. Sixty-five new 25-mm flat-side rotary instruments (size 25, taper 0.04) and their nonflat-side prototypes (n = 65) were assessed for major deformations and examined regarding macroscopic and microscopic design, determination of nickel and titanium elements ratio, measurement of phase transformation temperature and evaluation of mechanical performance parameters including time/cycles to fracture, maximum torque, angle of rotation, maximum bending and buckling strengths and cutting ability. Additionally, unprepared canal areas, volume of hard tissue debris and percentage reduction of dentine thickness were calculated for each tested instrument after preparing mesial canals of mandibular molars (n = 12), using micro-CT imaging. Statistical analyses were performed using the U-Mann-Whitney test and independent Student t-test (α = 5%). The number of spirals (n = 8) and blade direction (clockwise) were similar between both flat and nonflat instruments, whilst the helical angles were equivalent (⁓25°). Flat-instruments showed inconsistencies in the homogeneity of the gold colour on the flat-side surface, blade discontinuity, and incomplete and variable S-shaped cross-sections. The titanium-to-nickel ratios were equivalent, but significant differences in the R-phase finish and austenitic start phase transformation temperatures were observed between the flat and nonflat-side instruments. The flat-side instruments demonstrated superior cutting ability compared to the nonflat instruments, as well as, significantly lower values for time to fracture, rotation to fracture and maximum torque to fracture (p < .001). No statistical difference was observed between tested instruments regarding angle of rotation (p = .437), maximum bending (p = .152) and buckling load (p = .411). Preparation protocols using flat and nonflat instruments did not show any statistically significant differences (p > .05). All flat-side instruments exhibited deformation after shaping procedures. The flat-side instrument showcased enhanced cutting ability compared to its nonflat counterpart. However, it exhibited inferior performance in terms of time, rotation and maximum torque to fracture, along with distinct phase transformation temperatures. No differences were observed in the titanium-to-nickel ratios, angle of rotation, maximum bending, buckling load, preparation time, percentage of untouched canal walls, volume of hard tissue debris and percentage reduction of dentine thickness.

Follow-up of Non-Surgical Endodontic Treatment of Permanent Mandibular First Molars with Middle Mesial Root Canals –Four Clinical Case Series Report with a Mini Literature Review

Introduction: Root canal treatment’s long-term favorable prognosis is dependent on a good pulpal-periapical diagnosis and periodontium health, clear preoperative radiographs, an adequate understanding of complex root canal anatomy and endodontic pathology, proper treatment protocol that involves careful examination of root anatomy, identifying unusual root canal anatomy, access modification, negotiation of all the canals, complete debridement by shaping and chemical disinfection of all the portals of entry and exit within the root canal system, hermetic three- dimensional obturation of root canal space with an inert filling material followed by a fluid-tight tooth coronal seal. Clinicians are challenged with aberrations in the root canal anatomy of permanent mandibular molars especially when this anatomy is difficult to visualize from radiographs. The presence of a middle mesial root canal in permanent mandibular molars has been reported. Extensive exploration of the groove between mesiobuccal and mesiolingual orifices in mandibular permanent molars may reveal the presence of additional middle mesial canal orifice. Objectives: This clinical case series discusses the Follow-up of non-surgical endodontic management of four mandibular permanent first molars with an additional Middle Mesial (MM) canal in the mesial root. A mini literature review of this anatomical anomaly is also presented. Materials and Methods: The four mandibular molars with middle mesial canal endodontic cases done at Endodontics Clinic, Primary Health Care Corporation (PHCC), Qatar by the author in the year 2021 were reviewed with follow-up in the year 2023, address the endodontic management from identification of additional canals to complete obturation and follow up. Results: Clinical follow-up post endodontic treatment demonstrated that the treated molars with extra canals were asymptomatic with no sensitivity to percussion or palpation, no swelling or tooth mobility, and normal periodontal ....

Prevalence and Morphology of the Middle Mesial Canal in the First and Second Mandibular Molars Using Cone-Beam Computed Tomography

Introduction: Understanding of the normal anatomy of the teeth as well as the anatomical variations of each tooth and between different teeth is a prerequisite for successful endodontic treatment, and errors in this area can lead to treatment failures .The aim of this study was to determine the prevalence and morphology of the middle mesial canal in the first and second mandibular molars using Cone-Beam Computed Tomography (CBCT) in the population of Isfahan City and its relationship with the distance between the orifice canals. Methods: This retrospective descriptive study examined 180 reconstructed CBCT radiographs in modified axial, coronal, and sagittal sections, and evaluated the number, location, and morphology of the canals and the spacing of the orifices. Results: 47.5% of participants had left-side first molars with three canals and 48% had right-side first molars with three canals.46.1% had a second molar on left-side with three canals and 46% had a right-side three canal second molar. 1% of participants had four canals in the left-side first molars and 1% had four canals in the right-side first molars. Conclusion: The middle mesial canal is more likely to be near the mesiobuccal and mesiolingual canals. The highest prevalence is in the right-side first molar of women and the lowest is in the left-side second molar of men. Due to the low probability of the presence of this additional canal, careful examination of the patient's molar teeth before starting endodontic treatment is recommended.

Effectiveness of Removal of Hard Tissue Debris from the Mesial Root Canal System of Mandibular Molars using Different Supplementary Irrigation Protocols: An Original Study.

An instrumented and endodontically treated tooth may sometimes impede disinfection by trapping hard tissue as well as the other canal contents at the isthmus level of the canal. Thus, the current in vitro study was piloted to assess the competence of two irrigating systems. Twenty mandibular with two mesial canals convergent into a single foramen and joined by an isthmus of the human permanent teeth were compared for the two irrigation systems of continuous and intermittent ultrasonic (US) motions of the irrigation. The teeth were prepared by a single rotary system and were imaged using the "Scanning electronic microscopy-SCM". The parameters were compared before and after the irrigation of the canal with the intended US systems for the removal of hard tissue debris. The appropriate statistical tools were used to find the significance, the value of which was kept at P < 0.05. Significant percentage reduction of the hard tissue debris was achieved after the application of the supplemental irrigation protocols (P < 0.05). However between the groups, there was no significant difference. Comparable removal of the hard tissue debris was obtained in both the irrigation systems. Though not significant, the GentleWave performed better than the Irrisafe.

A microcomputed tomographic analysis of the morphological variabilities and incidence of extra canals in mandibular first molar teeth in an Egyptian subpopulation

A well-protected microbial habitat may be present in the root and canal morphology, which is varied and complicated. Before initiating effective root canal treatment, a detailed knowledge of the root and canal anatomical variances in each tooth is a must. This study aimed to investigate the root canal configuration, apical constriction anatomy, location of the apical foramen, dentine thickness, and prevalence of accessory canals in mandibular molar teeth in an Egyptian subpopulation using micro-computed tomography (microCT). A total of 96 mandibular first molars were scanned using microCT, and 3D reconstruction was performed using Mimics software. The root canal configurations of each of the mesial and distal root were classified with two different classification systems. The prevalence and dentin thickness around middle mesial and middle distal canals were investigated. The number, location and anatomy of major apical foramina and the apical constriction anatomy analysed. The number and location of accessory canals were identified. Our findings showed that two separate canals (15%) and one single canal (65%) were the most common configuration in the mesial and distal roots, respectively. More than half of the mesial roots had complex canal configurations and 51% had middle mesial canals. The single apical constriction anatomy was the most common for both canals followed by the parallel anatomy. Disto-lingual and distal locations of the apical foramen are the most common location for both roots. Mandibular molars in Egyptians show a wide range of variations in root canal anatomy with high prevalence of middle mesial canals. Clinicians should be aware of such anatomical variations for successful root canal treatment procedures. A specific access refinement protocol and appropriate shaping parameters should be designated for each case to fulfil the mechanical and biological objectives of root canal treatment without compromising the longevity of treated teeth.

Incidence of missed middle mesial canal in endodontically treated mandibular molar teeth: A cone-beam computed tomography study.

In endodontic treatment, the aim is to completely determine, shape, and fill all root canals in a three-dimensional way. Missed canals lead to treatment failure. In mandibular molars, there may be an extra canal called the middle mesial canal between the mesiobuccal and mesiolingual canals. The aim of this study was to evaluate the prevalence of missed middle mesial canals in root canal-treated mandibular molar teeth. In this study, cone-beam computed tomography (CBCT) images of 1054 patients were analyzed. We identified 121 endodontically treated mandibular molars and evaluated the prevalence of missed canals. Although 33.05% of the root canal-treated teeth did not have a middle mesial canal, this canal was detected in the other 66.94%; 97.53% of teeth with a middle mesial canal could not be detected by clinicians. Clinicians performing endodontic treatment of mandibular molar teeth should not ignore the presence of the middle mesial canal. Thus, it is very important for clinicians to have sufficient information about the localization, morphology, and variations of the middle mesial canal.

Root and canal anatomy of mandibular first molars using micro-computed tomography: a systematic review

BackgroundA thorough understanding of root and canal anatomy is crucial for successful root canal treatment outcomes. This systematic review aims to explore the published micro-CT studies investigated the anatomy of root and canal system in permanent mandibular first molars.MethodAn electronic search was performed on Web of science, PubMed, and Scopus. Micro-CT journal studies investigated the root and canal anatomy of permanent double-rooted mandibular first molars were included. Data on study characteristics, objectives of interest, specifications of the studies, and micro-CT specifications were extracted. Risk of bias assessment (ROB) of the included studies was performed using Anatomical Quality Assessment (AQUA) tool. The extracted data were presented in tables and figures to present and synthesise the results. A meta-analysis was performed for the studies related to the prevalence of Vertucci's canal configurations, middle mesial canal (MMC) configurations, and Fan's isthmus types.ResultsAmongst 1358 identified studies, thirty met the inclusion criteria. In terms of the objectives, the selected studies showed high anatomical variability in mandibular first molars. Twenty-two (73%), 25 (83%), and 12 (40%) of the studies reported the population/ethnicity, micro-CT specifications, and ethical approval, respectively. 28 (93%) studies did not disclose the method of sample size estimation. In only 6 (20%) of the studies, the authors had calibrated the assessment approaches. Mostly, a potential ROB was reported in domain 1 (objective(s) and subject characteristics) and domain 3 (methodology characterization). Whilst, low risk was reported in domains 2 (study design), 4 (descriptive anatomy), and 5 (reporting of results). The overall ROB was reported to be ''moderate'' in the vast majority of the studies (27/30). Meta-analysis results showed high levels of heterogeneity among the studies related to MMCs (I2 = 86%) and Fan's isthmus (I2 = 87%). As for the root canal configuration, pooled prevalence showed that Vertucci type IV and type I were the most prevalent in mesial and distal root canals, respectively.ConclusionBased on moderate risk of bias level of evidence, micro-CT studies have shown wide range of qualitative and quantitative data presentations of the roots and canals in mandibular first molars.Protocol and registration.The protocol of this systematic review was prospectively registered in the Open Science Framework database (https://osf.io) on 2022–06-20 with the registration number 10.17605/OSF.IO/EZP7K.

A New Criteria to Assess Quality of Obturation in Primary Teeth: KEDOO Classification.

The success of the pulpectomy depends on adequate access, cleaning, shaping, and good-quality obturation. Evaluating the quality of obturation is the major tool that determines the success of the procedure. The present study aimed to assess the quality of obturation in all the canals of primary teeth and suggest a new classification. A total of 1,000 radiographs of the pulpectomy procedure performed in primary molars were evaluated. The quality of obturation was assessed for each canal using the criteria given by Coll and Sandrian. The prevalence of each obturation criterion in every canal was represented in the form of a percentage. It was observed that among the mandibular primary molars, most of the mesial canals were underfilled, and in the distal canal, most of the canals were overfilled. Among the maxillary primary molars, most of the mesial canals were overfilled, more distal canals were underfilled, and with respect to palatal canals, optimal obturation was seen. The pitfalls of the previous classification were revised, and a new classification for assessing the quality of obturation was proposed, which is arch, segment, and canal specific. The new classification will give a more precise assessment for the evaluation of various techniques and materials used for pulpectomy in primary teeth. Jeevanandan G, Govindaraju L, Kotian N, et al. A New Criteria to Assess Quality of Obturation in Primary Teeth: KEDOO Classification. Int J Clin Pediatr Dent 2023;16(2):376-379.

Removal of Thermafil Obturators Using 2 Different Techniques: A Comparative Ex Vivo Study

IntroductionThe aim of this ex vivo study was to compare 2 techniques for removal of Thermafil obturators from curved root canals in mandibular molars. MethodsSixty mesial root canals in extracted mandibular molars were distributed into matched pairs according to degree and radius of curvature and were prepared to size 35/.04 and obturated with Thermafil obturators size 35. Each tooth was embedded in resin, mounted in a mannequin head, and isolated with rubber dam to simulate clinical conditions.Removal of obturators was undertaken under a dental operating microscope by an experienced endodontist using either the FragRemover loop device, or reciprocating NiTi instruments. Pre- and postoperative micro-CT scans were taken to compare the amount of remaining filling material and of removed dentin. Eventual problems during removal attempts were recorded. ResultsUsing Reciproc, 24 carriers (80%) were removed, 16 in one piece, 8 in small pieces, and in 6 cases removal failed. The FragRemover removed 12 carriers (40%), all of these completely, but in 18 cases removal failed (P < .05). Reciproc left less remaining filling material than the FragRemover (P < .05) but removed significantly more dentin in the apical part of the root canal (P < .01). There was no significant difference concerning the total amount of removed dentin (P > .05) between both groups.Seven complications occurred in the Reciproc group. In 5 teeth, working length could not be reached; in 2 teeth, a Reciproc file R25 fractured. With the FragRemover, 64 complications occurred, in 36 cases, including second removal attempts, the loop slipped over the carrier, in 24 cases the top of the carrier was sheared off. In 9 cases, separation of the core occurred too far apically, not allowing further use of the FragRemover. In 4 cases, the wire loop tore. ConclusionsReciproc was more effective in removal of Thermafil carriers, whereas when using the FragRemover less dentin was removed in the apical part of the root canal and more obturation material was left.

Shaping ability of WaveOne Gold and OneReci by using two apical sizes: a micro-computed tomographic assessment.

OneReci (MicroMega, Besançon, France) is a recently introduced single-file reciprocating system with scarce information revealed on its shaping ability. This study aimed to compare the shaping abilities of OneReci and a well-documented single-file reciprocating system WaveOne Gold (WOG; Dentsply Maillefer, Ballaigues, Switzerland) and evaluate the effect of increased apical enlargement on the preparation quality, using micro-computed tomography (micro-CT). After an initial micro-CT scanning, twenty mesial root canals of mandibular molars were anatomically matched. The canals were assigned to two experimental groups (n=10), using OneReci or WOG in different canals of the same root. The glide paths were created, and root canals were prepared twice, using size 25 and 35 instruments of the systems, respectively. The specimens were scanned with micro-CT after each preparation. The increase in canal volume, amount of dentin removal, unprepared root canal surface, canal transportation, centering ratio and preparation times were assessed. The data were analysed with independent sample t-tests, variance analyses, Friedman and Mann-Whitney U tests. The significance level was set at 5%. Each preparation increased the canal volume and dentin removal while decreasing the unprepared root surface. The difference between the systems became significant after preparation with size 35 instruments (p<0.05). Regarding canal transportation and centering ratio, the difference was insignificant (p>0.05). The first preparation step (glide path + size 25 instrument) was significantly faster in the OneReci group (p<0.05). Preparation with size 25 instruments of the systems appeared to be safe with similar shaping performances. Larger apical preparation promoted significantly higher dentin removal, volume increase, and prepared surface area in WOG.

Multimethod analysis of three rotary instruments produced by electric discharge machining technology.

This study aimed to compare three rotary instruments produced by the EDM process with the heat-treated ProTaper Gold system regarding design, metallurgy, mechanical properties and shaping ability. HyFlex EDM (25/~), Neoniti (25/.06), EDMax (25/.06) and ProTaper Gold (25/.08v) instruments (n = 58 per group) were compared regarding design, metallurgy and mechanical performance. Unprepared canal areas were calculated for each system after preparation of mesiobuccal, mesiolingual and distal canals of mandibular molars (15 canals per group) using micro-CT technology. Statistical analyses were performed using One-way anova post-hoc Tukey and Kruskal-Wallis post-hoc Dunn's tests (α = 5%). All instruments had asymmetrical blades, no radial lands, no major defects and almost equiatomic nickel/titanium ratios, but different cross-section designs, tip geometries and surface appearances. Although instruments had distinct transformation temperature curves, they showed crystallographic martensitic arrangement at 21°C and mixed austenite plus R-phase at body temperature. Neoniti and HyFlex EDM showed similar results in all mechanical tests (p > .05), while EDMax and ProTaper Gold had similar time to fracture (p = .841), maximum bending load (p = .729), and cutting ability (p = .985). ProTaper Gold showed the highest torque to failure (p < .001) and HyFlex EDM had the lowest buckling resistance (p < .001). Mean percentages of unprepared canal areas ranged from 20.4% to 25.7% in the mesial canals, and from 20.8% to 26.2% in the distal canal, with no statistical differences among systems (p > .05). Instruments' geometry and phase transformation temperatures influenced the results of the mechanical tests, but not their shaping ability.

Calcium Silicate–based Sealer Extrusion into the Mandibular Canal: 3 Different Recovery Outcomes—A Report of 3 Cases

The use of calcium silicate–based sealers (CSSs) is increasing in dentistry as a result of their favorable properties. The inadvertent extrusion of these sealers into the mandibular canal (MC) can result in temporary or permanent neurosensory alterations. Three different recovery outcomes of CSS extrusion into the MC after endodontic treatment of mandibular molars confirmed by cone-beam computed tomographic imaging are described. In Case 1, CSS from the mesiolingual canal of tooth #31 was extruded into the MC during obturation. The patient reported paresthesia. The symptoms of paresthesia were completely resolved by 9 months. In Case 2, CSS from the mesial canals of tooth #30 was extruded into the MC during obturation. A “plasmalike spreading pattern” of the extruded sealer was observed on the radiographs. The patient reported paresthesia and dysesthesia. In addition, the patient complained of hyperalgesia with heat and mechanical allodynia. The symptoms continued to persist during follow-up. At 22 months, the patient still reported persistent paresthesia, hyperalgesia, and mechanical allodynia, affecting the ability to eat. In Case 3, CSS from the distal canal of tooth #31 was extruded into the MC during obturation. The patient did not report any paresthesia or dysesthesia. All 3 patients elected a follow-up approach and monitoring rather than surgical intervention. These cases illustrate the need for the development of guidelines for the management of iatrogenic CSS extrusion into the MC because such an occurrence may result in permanent, temporary, or no neurosensory alterations.

Prediction of root canal lengths and pulp volume of the maxillary permanent first molar based on stature, crown diameters, and facial morphometry.

This study purposed to develop statistical models to predict palatal (PRL), mesial (MRL), and distal (DRL) root canal length and pulp volume (PV) of the maxillary first permanent molar using stature, gender, mesiodistal (MD), and buccopalatal (BP) crown diameters and some facial morphometries. 57 individuals were included in the study. Cone beam computed tomography was used to measure root canal lengths and PV. The PV calculation was carried out using the software ITK-SNAP 3.4.0. PRL was positively correlated with BP, stature, middle facial height, interalar distance, and bicommissural distance (BCD) (p < 0.05). DRL was positively correlated with BP, MD, and stature (p < 0.05). MRL was positively correlated with BP, MD, stature, lower face height, bizygomatic distance, and BCD (p < 0.05). PV was negatively correlated with age and BCD (p < 0.05). Although all models have significant predictive power for the root lengths and PV, no model could explain variances greater than 30%. The highest and lowest predictive ability was obtained for PRL and DRL, respectively. While the most significant predictor was BP for PRL and DRL, it was the age for PV.

Shaping ability of Procodile and R6 Reziflow nickel-titanium reciprocating instruments in curved mesial root canals of mandibular molars: A MicroCT study.

To compare the shaping ability of Procodile and R6 Reziflow instruments used in reciprocating motion in severely curved root canals, assessed with micro-computed tomography (μCT). Fourteen extracted human mandibular first molars were randomly assigned to two instrumentation techniques (n = 14 mesial root canals): Procodile or R6 Reziflow. For both groups, root canals were prepared to the working length up to a size 25, .06 taper. Molars were virtually divided into apical, middle and coronal thirds and μCT was used to scan all samples pre- and post-root canal. Canal transportation, centring ability, volume, surface area and unprepared area were evaluated. Geometrical parameter changes were compared with preoperative values (one-way analyses of variance and Tukey multiple comparison post-hoc test) between groups and Student t-test within groups (α = 0.05) Significantly less transportation was observed associated with the Procodile technique in the molar's coronal third compared to the R6 Reziflow technique (p < .05). No significant differences in root canal centring ability, volume, surface area and unprepared area were observed. Procodile showed a lower percentage increase of surface area compared to R6 Reziflow (p < .05). The Procodile and R6 Reziflow techniques applied to first molar root canal performed similarly except for the less transportation observed in the coronal third using Procodile. RESEARCH HIGHLIGHTS: MicroCT analysis of canal geometry before and after instrumentation revealed that Procodile and R6 Reziflow showed a similar shaping ability to shape curved root canals without substantially modifications of the original tooth anatomy.

Root and root canal morphology of permanent mandibular first and second molars in a Kuwaiti population: A retrospective cone-beam computed tomography study

AimEndodontic diseases typically affect the mandibular molars. Understanding the complex morphology of the root canal system and its variations is necessary for successful endodontic treatment. The aim of this study was to evaluate the morphology of roots and root canals of mandibular first and second permanent molar teeth in a Kuwaiti population using cone-beam computed tomography (CBCT). Materials and methodsCBCT images of 651 mandibular first and second molar teeth were obtained from specialist government dental centers. The age, sex, root canal configuration, and number and type of roots were recorded. The data were statistically analyzed. ResultsThe most common canal configuration in the mandibular first and second molars was type II (65.6% and 54.4%, respectively), with no significant difference seen between the sexes (p = 0.234). The canal configuration was significantly different between the mandibular first and second molars (p < 0.001). Most teeth had two roots (94.5%); split roots were common (92.6%) and the number thereof varied significantly. Radicular grooves were most common on the lingual side (4.9%). C-shaped canals were present in 43 (6.60%) teeth. Additionally, one tooth had a confluent middle mesial canal and nine (1.4%) had radix entomolaris. ConclusionMandibular molars in our Kuwaiti population typically had two split roots with type II and IV canal configurations. The prevalence rates of C-shaped canals, middle mesial canals, and radix entomolaris were remarkably low.

Optimum Shaping Parameters of the Middle Mesial Canal in Mandibular First Molars: A Finite Element Analysis Study

IntroductionThis study investigated the effect of shaping parameters of 2 different configurations of middle mesial canals (MMCs) on the biomechanical behavior and life span of a mandibular first molar using finite element analysis (FEA). MethodsA mandibular molar with an independent MMC and another with a confluent MMC were scanned via micro-computed tomography, and FEA models were produced. For each tooth, an intact model and 5 experimental models were produced that differed by parameters of how the MMC was shaped: unshaped MMC, 25/.04, 25/.06, 30/.04, and 30/.06. Cyclic loading of 50 N was applied on the occlusal surface in vertical and oblique scenarios, and the number of cycles until failure (NCF) was compared with the intact models. In addition, mathematical analyses evaluated the stress distribution patterns and calculated maximum von Mises and maximum principal stresses. ResultsFor both the independent and confluent MMC models, shaping the MMC reduced the NCF. The lifelog percentage of models was inversely proportional with radicular shaping parameters during the vertical and oblique loading scenarios. The shaping size of 30/.06 resulted in lower lifelog percentage than the cases with shaping size of 25/.04 in both of the independent and confluent MMC models. For all models, oblique loading reduced NCF more than vertical loading. ConclusionShaping the MMC should be kept as conservative as 25/.04. Also, whether the MMC is independent or confluent is a deciding factor in whether to increase the apical diameter or the root canal taper when larger shaping parameters are needed.

Bir Türk Alt Popülasyonunda Kalıcı Üst Azı Dişlerinin Kök Kanal Konfigürasyonunun Değerlendirilmesi: Konik Işınlı Bilgisayarlı Tomografi Çalışması

Objective: Maxillary molars may be challenging for root canal treatment due to their complex canal anatomy and additional root canals, especially in the mesiobuccal root. The current study aimed to investigate the prevalence of root and root canal numbers of maxillary molar in a selected Turkish population. Materials and Methods: A total of 905 first and second maxillary molars were evaluated using cone-beam computed tomography (CBCT) images. The number of roots and canals was recorded and the mesiobuccal canal was further evaluated with the Vertucci classification. Results: A total of 394 teeth had a second mesiobuccal (MB2) canal (43.5%). While 90.4% of all maxillary molars had three roots, 44% had four root canals. The most common root canal anatomy of mesiobuccal root canals was Type II (42.6%) followed by Type IV (31.5%) and Type III (22.1%). Conclusions: It is clear that the second mesial root canal in permanent maxillary molars should be carefully searched for the long-term success of root canal treatments. It is seen that CBCT sections will be beneficial in diagnosis and treatment in better understanding the anatomical structure of the teeth and determining possible anatomical deviations.

Assessment of the Prevalence of Middle Mesial Canal in Mandibular First Molar: A Multinational Cross-sectional Study with Meta-analysis

BackgroundAn additional canal found in the mandibular first molar (M1M) is the middle mesial canal (MMC), which is often missed during root canal treatment. In this study, the prevalence of MMC in M1M on cone-beam computed tomography (CBCT) images was evaluated in 15 countries, along with the effect of some demographic factors on its prevalence. MethodsDeidentified CBCT images were scanned retrospectively, and the ones including bilateral M1Ms were included in the study. A written and video instruction program explaining the protocol to be followed step-by-step was provided to all observers to calibrate them. The CBCT imaging screening procedure consisted of evaluating three planes (coronal, sagittal, and axial) after a 3-dimensional alignment of the long axis of the root(s). The presence of an MMC in M1Ms (yes/no) was identified and recorded. ResultsIn total, 6304 CBCTs, representing 12,608 M1Ms, were evaluated. A significant difference was found between countries (P < .05). MMC prevalence ranged from 1% to 23%, and the overall prevalence was 7% (95% confidence interval [CI]: 5%–9%). No significant differences were found between the left and right M1M (odds ratio = 1.09, 95% CI: 0.93, 1.27; P > .05) or between genders (odds ratio= 1.07, 95% CI: 0.91, 1.27; P > .05). As for the age groups, no significant differences were found (P > .05). ConclusionsThe prevalence of MMC varies by ethnicity, but it is generally estimated at 7% worldwide. Physicians must pay close attention to the presence of MMC in M1M, especially for opposite M1Ms, due to the prevalence of MMC being significantly bilateral.

Middle Mesial Canals Prevalence percentage and Its Configuration type with "Egyptian subpopulation" by CBCT

The Aims of This Study: were to detect the middle mesial canals (MMCs) prevalence in mandibular 1st molars, its configuration type, and its percentage of incidence with age by Cone-Beam Computed Tomography (CBCT) analysis. Methods: CBCT scan of 1650 patients were observed between January 2021 to February 2022 were collected using the CBCT imaging system from the database of the department of oral radiology, faculty of dental medicine, Al-Azhar University - Assiut branch. CBCT scan images were analyzed by Sidexis software. CBCT images were examined to detect the following: (1) The percentage of incidence frequency of the MMCs, (2) MMCs classification, and (3) Frequency of occurrence of MMCs according to age. Results: The incidence frequency percentage of the presence of MMCs among the Egyptian population was 10.79 % (208/1926) with no statistically significant due to gender, While MMCs configuration types showed 77% (160/208) confluent anatomy merging with either the mesio buccal or mesio lingual canals, 16.3% (34/208) fin anatomy and only 6.7% (14/208) showed independent MMCs with separate orifices and apical foramen. lastly the incidence frequency percentage of the presence of MMCs decreases with age. Conclusions: The MMCs prevalence in mandibular 1st molars among some Egyptian population was 10.79%, and CBCT scan is helpful way to detect the presence of MMCs.