External Validation of the Effect of the Combined Use of Object Detection for the Classification of the C-Shaped Canal Configuration of the Mandibular Second Molar in Panoramic Radiographs: A Multicenter Study

INTRODUCTION

The purposes of this study were to evaluate the effect of the combined use of object detection for the classification of the C-shaped canal anatomy of the mandibular second molar in panoramic radiographs and to perform an external validation on a multicenter dataset.

METHODS

The panoramic radiographs of 805 patients were collected from 4 institutes across two countries. The CBCT data of the same patients were used as "Ground-truth". Five datasets were generated: one for training and validation, and 4 as external validation datasets. Workflow 1 used manual cropping to prepare the image patches of mandibular second molars, and then classification was performed using EfficientNet. Workflow 2 used two combined methods with a preceding object detection (YOLOv7) performed for automated image patch formation, followed by classification using EfficientNet. Workflow 3 directly classified the root canal anatomy from the panoramic radiographs using the YOLOv7 prediction outcomes. The classification performance of the 3 workflows was evaluated and compared across 4 external validation datasets.

RESULTS

For Workflows 1, 2, and 3, the area under the receiver operating characteristic curve (AUC) values were 0.863, 0.861, and 0.876, respectively, for the AGU dataset; 0.935, 0.945, and 0.863, respectively, for the ASU dataset; 0.854, 0.857, and 0.849, respectively, for the ODU dataset; and 0.821, 0.797, and 0.831, respectively, for the ODU low-resolution dataset. No significant differences existed between the AUC values of Workflows 1, 2, and 3 across the 4 datasets.

CONCLUSIONS

The deep learning systems of the 3 workflows achieved significant accuracy in predicting the C-shaped canal in mandibular second molars across all test datasets.

Assessment of the root and canal morphology in the permanent dentition of Saudi Arabian population using cone beam computed and micro-computed tomography - a systematic review

INTRODUCTION

Root canal treatment procedures require a thorough understanding of root and canal anatomy. The purpose of this systematic review was to examine the morphological differences of teeth root and their canals assessed using cone-beam computed and micro-computed tomography in Saudi Arabian population.

METHODOLOGY

An electronic search was conducted in PubMed / Medline, Scopus, Google Scholar, and Web of Science databases until January 2023 to retrieve related studies. "Root canal morphology," "Saudi Arabia," "Micro-CT," and "cone-beam computed tomography" were used as keywords. A modified version of previously published risk of bias assessment tool was used to determine the quality assessment of included studies.

RESULTS

The literature search revealed 47 studies that matched the criteria for inclusion, out of which 44 studies used cone beam computed tomography (CBCT) and three were micro-computed tomography (micro-CT) studies. According to the modified version of risk of bias assessment tool, the studies were categorized as low, moderate, and high risk of bias. A total of 47,612 samples were included which comprised of either maxillary teeth (5,412), or mandibular teeth (20,572), and mixed teeth (21,327). 265 samples were used in micro-CT studies while 47,347 teeth samples were used in CBCT studies. Among the CBCT studies, except for three, all the studies were retrospective studies. Frequently used imaging machine and software were 3D Accuitomo 170 and Morita's i-Dixel 3D imaging software respectively. Minimum and maximum voxel sizes were 75 and 300 μm, Vertucci's classification was mostly used to classify the root canal morphology of the teeth. The included micro-CT studies were in-vitro studies where SkyScan 1172 X-ray scanner was the imaging machine with pixel size ranging between 13.4 and 27.4 μm. Vertucci, Ahmed et al. and Pomeranz et al. classifications were applied to classify the root canal morphology.

CONCLUSION

This systematic review revealed wide variations in root and canal morphology of Saudi population using high resolution imaging techniques. Clinicians should be aware of the common and unusual root and canal anatomy before commencing root canal treatment. Future micro-CT studies are needed to provide additional qualitative and quantitative data presentations.

Expert consensus on difficulty assessment of endodontic therapy

Endodontic diseases are a kind of chronic infectious oral disease. Common endodontic treatment concepts are based on the removal of inflamed or necrotic pulp tissue and the replacement by gutta-percha. However, it is very essential for endodontic treatment to debride the root canal system and prevent the root canal system from bacterial reinfection after root canal therapy (RCT). Recent research, encompassing bacterial etiology and advanced imaging techniques, contributes to our understanding of the root canal system's anatomy intricacies and the technique sensitivity of RCT. Success in RCT hinges on factors like patients, infection severity, root canal anatomy, and treatment techniques. Therefore, improving disease management is a key issue to combat endodontic diseases and cure periapical lesions. The clinical difficulty assessment system of RCT is established based on patient conditions, tooth conditions, root canal configuration, and root canal needing retreatment, and emphasizes pre-treatment risk assessment for optimal outcomes. The findings suggest that the presence of risk factors may correlate with the challenge of achieving the high standard required for RCT. These insights contribute not only to improve education but also aid practitioners in treatment planning and referral decision-making within the field of endodontics.

Internal and external morphological analysis of fused-rooted mandibular second molars in the Chinese population: A micro-computed tomographic study

This study investigated the root canal morphology of fused-rooted mandibular second molars based on the pulp chamber floor (PCF) and analysed the correlation between the external morphology of the radicular groove, and the internal morphology of the PCF and root canal configuration. A total of 291 fused-rooted teeth collected from the Chinese population were scanned using micro-computed tomography and a dental operating microscope was used for observing the PCFs. The classification of the PCF and root canal configuration were identified according to modified Min et al.'s and Gao et al.'s classifications, respectively. Additionally, a new radicular groove classification was proposed. The correlation among these morphological characteristics was investigated using the chi-square test and Fisher's exact test (p < 0.05). The results showed that 74.2% of teeth had C-shaped PCFs, while 21.0% had non-C-shaped PCFs. As for the root canal configurations, 37.5% of teeth were merging type, 40.9% were symmetrical type, and 14.8% were asymmetrical type. Statistical analysis revealed a significant correlation between the PCF types and the root canal configurations (p < 0.001). The dominant root canal types for teeth with C-shaped PCFs were merging and symmetrical types, while the asymmetrical type was not identified in non-C-shaped PCFs. In addition, significant morphological association between the root canals and radicular grooves was also revealed (p < 0.001). Teeth with different PCF morphologies exhibit specific patterns of root canal category distribution. Understanding the morphological nuances of the root canal based on the PCF can assist clinicians in predicting and identifying the canal configuration beneath the visible orifice.

Predictor factors of 1-rooted mandibular second molars on complicated root and canal anatomies of other mandibular teeth

Objectives

This study aimed to determine the effects of 1-rooted mandibular second molar (MnSM) teeth on root canal anatomy complexities of the mandibular central incisor (MnCI), mandibular lateral incisor (MnLI), mandibular canine (MnCn), mandibular first premolar (MnFP), mandibular second premolar (MnSP), and mandibular first molar (MnFM) teeth.

Materials and Methods

Cone-beam computed tomography images of 600 patients with full lower dentition were examined. Individuals with 1-rooted MnSMs were determined, and the complexity of root canal anatomy of other teeth was compared with individuals without 1-rooted MnSMs (Group-1; subjects with at least one 1-rooted MnSM, Group-2; subjects with more than a single root in both MnSMs). A second canal in MnCIs, MnLIs, MnCns, MnFPs, and MnSPs indicated a complicated root canal. The presence of a third root in MnFMs was recorded as complicated.

Results

The prevalence of 1-rooted MnSMs was 12.2%, with the C-shaped root type being the most prevalent (9%). There were fewer complicated root canals in MnCIs (p = 0.02), MnLIs (p < 0.001), and MnFPs (p < 0.001) in Group 1. The other teeth showed no difference between the groups (p > 0.05). According to logistic regression analysis, 1-rooted right MnSMs had a negative effect on having complex canal systems of MnLIs and MnFPs. Left MnSMs were explanatory variables on left MnLIs and both MnFPs.

Conclusions

In individuals with single-rooted MnSMs, a less complicated root canal system was observed in all teeth except the MnFMs.

Micro-computed tomography analysis of calcium hydroxide delivery efficacy in C-shaped canal system of mandibular second molars

BACKGROUND

Calcium hydroxide [Ca(OH)2] is widely accepted as a biocompatible interappointment intracanal medicament. This study aimed to analyze the efficacy of Ca(OH)2 placement into the C-shaped canal system of mandibular second molars using the syringe method with and without lentulo spiral utilizing micro-computed tomography (micro-CT).

METHODS

Twenty-four extracted mandibular second molars were instrumented and classified into C-shaped floors (n = 12) and non-C-shaped floors (n = 12). Both groups were placed with Ca(OH)2 using the syringe system, then all teeth were scanned and cleaned, and placed with Ca(OH)2 again but with the syringe system followed by lentulo spiral and rescanned. The specimens were scanned using micro-CT to analyze the volume, volume percentage, uncontacted surface area, and uncontacted surface area percentage of Ca(OH)2 with the two delivery methods in the entire canal and at the apical 4 mm of the canal. Mann-Whitney test and Wilcoxon signed-rank test were used to determine the statistical differences among the groups.

RESULTS

Syringe administration used in conjunction with lentulo spiral presented lower uncontacted surface area, a lower percentage of uncontacted surface area, larger volume, and a higher percentage of volume than syringe without lentulo spiral (P < 0.05). There was no significant difference between the C-shaped floor group and the non-C-shaped floor group (P > 0.05) in the Ca(OH)2 uncontacted surface area, volume, and percentages at different regions of canals and among different delivery techniques groups.

CONCLUSIONS

The lentulo spiral and syringe technique combination can increase the volume and contacted surface area of Ca(OH)2 in the C-shaped canal system of mandibular second molars.

Assessment of the root filling volume in C-shaped root canal on cone-beam CT and micro-CT in relation to nano-CT

AIM

To assess the observed volume of filled C-shaped root canals from different CBCT and micro-CT having nano-CT as a reference.

MATERIALS AND METHODS

Twelve extracted mandibular molars with C-shaped root canals were endodontically treated using Reciproc Blue R25 (VDW GMBH, Munich, Germany) in a reciprocating system and filled with gutta-percha (Dentsply Maillefer) and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany). CBCT scans were performed using 3 units-3D Accuitomo 170 (J. Morita, Kyoto, Japan), ProMax 3D Max (Planmeca, Helsinki, Finland), and NewTom VGi EVO (Cefla QR, Verona, Italy)-at two resolution modes: standard and high. Micro-CT and nano-CT scans were also obtained. The volume of all filled C-shaped root canals was obtained using CTAn software (Bruker, Kontich, Belgium), and the blooming artifact, in relation to nano-CT volume, was calculated. The data were evaluated by the Bland-Altman plots and ANOVA two-way for repeated measures (α = 0.05).

RESULTS

All CBCT units and micro-CT showed significantly larger observed volume of root canal filling when compared to nano-CT. The blooming artifact of root canal filling in standard resolution was significantly larger than that in high resolution (p < 0.05) in all CBCT units.

CONCLUSIONS

Endodontic filling material with AH Plus sealer causes blooming artifacts in CBCT units and micro-CT.

CLINICAL RELEVANCE

Considering the anatomical complexity of C-shaped root canals and the challenges associated with endodontic treatment, CBCT is frequently recommended for follow-up evaluations. However, the presence of endodontic filling material can result in blooming artifacts that may potentially impact the accurate diagnosis of endodontic complications.

Prevalence and Morphology of C-Shaped Canals in Mandibular First and Second Molars of an Iranian Population: A Cone-Beam Computed Tomography Assessment

Objectives

The complex anatomy of C-shaped canals poses challenges for clinicians compared to teeth with normal root canal anatomy. This study is aimed at evaluating the frequency and morphology of C-shaped canals in the mandibular first and second molars among an Iranian population using cone-beam computed tomography (CBCT).

Materials and Methods

This cross-sectional study evaluated 369 CBCT scans from the archives of a radiology clinic in Ardabil, Iran. The sample included 248 mandibular first molars and 478 mandibular second molars. The presence of C-shaped canals and their classification, according to Fan et al., were evaluated at four levels: orifice, coronal, middle, and apical. Prevalence based on gender and tooth type was also assessed.

Results

A total of 199 (53.9%) males and 170 (46.1%) females were evaluated. C-shaped canals were found in 11 (8 males/3 females) out of 248 (4.4%) first molars and in 20 (11 males/9 females) out of 478 (3.7%) second molars. The C2 configuration was most prevalent in the orifice, coronal, and middle levels of both molar types, while C3 and C4 morphologies were most commonly found apically in the second and first molars, respectively. A significant difference in configuration was found only at the coronal level between molar types. A significant association between gender and configuration was observed only at the orifice level of the second molars. No other significant differences were found (P > 0.05).

Conclusion

C-shaped canal configurations should be expected in 4.4% of mandibular first molars and 3.7% of the second molars in this Iranian population, with a predominance of the C2 configuration in the orifice, coronal, and middle levels.

Prevalence of C-shaped canals and three-rooted mandibular molars in the Iranian population by using cone-beam computed tomography

OBJECTIVES

This study aimed to evaluate the prevalence of C-shaped canals and three-rooted mandibular molars in the Iranian population using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

This study evaluated mandibular teeth on 292 CBCT scans of patients referred to the Department of Radiology, Faculty of Dentistry, Islamic Azad University, Isfahan, Iran. All CBCT scans were obtained with the same three-dimensional CBCT scanner, and sections were reconstructed in all three planes (sagittal, axial, and coronal) with 1 mm slice thickness. A total of 291,402, and 200 first, second, and third molars, respectively, were evaluated. Data were analyzed using SPSS software (version 26.0).

RESULTS

Of 291 mandibular first molars, 0.7% were single-rooted, 96.6% were two-rooted, and 2.7% were three-rooted. The prevalence of C-shaped canals was 1.7% in mandibular first molars. Of 402 mandibular second molars, 8.5% were single-rooted, 90.5% were two-rooted, and 1% were three-rooted. The prevalence of C-shaped canals was 2% in mandibular second molars. Of 200 mandibular third molars, 21.5% were single-rooted, 77.5% were two-rooted, and 1% were three-rooted. The prevalence of C-shaped canals was 2% in mandibular third molars.

CONCLUSION

In the present study, the majority of mandibular molars were two-rooted, and three-rooted mandibular molars were less common. The third and second mandibular molars both had an increased prevalence of C-shaped canals. Mandibular first molars had the highest prevalence of three-rooted molars.

Investigation of mandibular second molar root and canal morphology in a Black South African population using cone-beam computed tomography and two classification systems

PURPOSE

To investigate the root and canal morphology of mandibular second molars, including anatomical variations, in a Black South African population using two classification systems.

METHODS

Cone-beam computed tomography images of 386 teeth were evaluated. The number of roots and canal configurations were categorized using the classifications of Vertucci (with modifications by Sert and Bayirli) and Ahmed et al. (including the modified Melton classification). Relationships between variables were assessed using Fisher's exact test (P < 0.05).

RESULTS

Mandibular second molars were predominantly two-rooted (91.7%). The majority of teeth had three canals including Type IV mesial (41.2%) and Type I (75.1%) distal (Ahmed et al. configuration: 2MDM M2 D1). Three or more canals were present in almost one-fifth of mesial (n = 72/386, 18.6%) and a small number of distal (n = 21/386, 5.4%) roots. Males displayed additional canals more frequently in the distal root (P = 0.02). C-shaped anatomy was found in 5.7%. Among the C-shapes, the most common was Melton's Type III in the coronal (50%), middle (81%) and apical (72%) thirds.

CONCLUSION

In this population, mandibular second molar teeth exhibited diverse morphology, which would have clinical significance for endodontic practitioners. The Ahmed et al. classification provided a better description than the Vertucci classification.

Microcomputed tomography analysis of the radicular residual dentin thickness in mandibular second molars after virtual fiber post placement: Identification of danger zones

STATEMENT OF PROBLEM

Mandibular second molars have variable root, pulp chamber floor, and radicular groove morphologies, potentially affecting residual dentin thickness and post placement suitability. However, an identification of the danger zones is lacking.

PURPOSE

The purpose of this in vitro study was to investigate the residual dentin thickness in the danger zone of mandibular second molars after virtual fiber post placement by using a simulation method based on microcomputed tomography (μCT).

MATERIAL AND METHODS

A total of 84 extracted mandibular second molars were scanned using μCT and classified according to root morphology (separate or fused) and pulp chamber floor morphologies (C-shaped, non-C-shaped, or no pulp chamber floor). Fused-root mandibular second molars were further classified based on the radicular groove type (V-, U-, or Ω-shaped). All specimens were accessed, instrumented, and rescanned with μCT. Two types of commercial fiber posts were also scanned. Clinical fiber post placement was simulated in all prepared canals by using a multifunctional software program. The minimum residual dentin thickness of each root canal was measured and analyzed by using nonparametric tests to identify the danger zone. Perforation rates were calculated and recorded.

RESULTS

Larger fiber posts decreased minimum residual dentin thickness (P<.05) and increased perforation rate. In regard to mandibular second molars with separate roots, the distal root canal exhibited a significantly higher minimum residual dentin thickness than the mesiobuccal and mesiolingual root canals (P<.05). However, no significant difference in minimum residual dentin thickness was found between the different canals in fused-root mandibular second molars with C-shaped pulp chamber floors (P<.05). Fused-root mandibular second molars with Ω-shaped radicular grooves had a lower minimum residual dentin thickness than those with V-shaped radicular grooves (P<.05) and demonstrated the highest perforation rate.

CONCLUSIONS

The morphologies of the root, pulp chamber floor, and radicular groove were correlated with residual dentin thickness distribution in mandibular second molars after fiber post placement. A comprehensive understanding of mandibular second molar morphology is essential for determining the suitability of post-and-core crown restorations after endodontic treatment.

Root and canal morphology of mandibular second molars in an Egyptian subpopulation: a cone-beam computed tomography study

BACKGROUND

This study was using Cone beam computed tomography (CBCT) to examine the anatomical variations in mandibular second molars in an Egyptian sub-population.

METHODS

A total of 350 CBCT images (215 females and 135 males, aged 15-65 years) of mandibular second molars were evaluated. Samples were evaluated in terms of: number of roots, number of root canals, roots' cross section as well as prevalence and configurations of C-shaped canals. Statistical analysis was done to highlight differences between different categories and their prevalence among genders (significance level was set at p < 0.05). Data were presented as frequency and percentage values and were analyzed using chi square test followed by pairwise comparisons utilizing multiple Fisher's exact tests with Bonferroni correction. The significance level was set at p < 0.05 within all tests.

RESULTS

Of the 350 mandibular second molars evaluated, 87.2% were non-C-shaped while 12.8% were C-shaped with no gender-based statistically significant differences (χ2 = 0.19, p = 0.656). Most samples had three root canals (80%) followed by two (16%), then one (3.2%), and finally four (0.8%) root canals. Among the non-C-shaped molars, presence of two roots was most common (83.4%) followed by presence of a single root (16.2%), and only one sample (0.2%) had three roots, and this had no correlation with gender (χ2 = 1.86, p = 0.431). In the mesial roots Type IV Vertucci was the most common configuration found (68.8%), while Type I was the most prevalent in the distal roots (91.8%). The long oval configuration was the most commonly found cross section in mesial roots while "oval" was the most prevalent in distal roots.

CONCLUSION

Egyptian sub-population shows highly variable morphological features in mandibular second molars, hence, CBCT is highly recommended on case-to-case conditions.

Prevalence and correlation of C-shaped root canals of mandibular premolars and molars in Eastern Chinese individuals

The aim of this study was to investigate the prevalence, correlation, and differences of C-shaped root canals (CSRCs) morphology in permanent mandibular premolars and molars in Eastern Chinese individuals using cone-beam computed tomography (CBCT). A total of 8000 mandibular first premolars (MFPs), mandibular second premolars (MSPs), mandibular first molars (MFMs), and mandibular second molars (MSMs) CBCT images from 1000 patients (692 females and 308 males) were collected. The prevalence, correlation, bilateral/unilateral presence, the morphology of CSRCs, level of canal bifurcation, gender differences, and location of radicular grooves (RGs) were evaluated. The prevalence of CSRCs in MFPs, MSPs, MFMs and MSMs were 10.25%, 0.25%, 0.55% and 47.05%, respectively. The prevalence of CSRCs in MFPs of males was higher than that in females, while the prevalence of CSRCs in MSMs of females was higher than that in males (P < 0.05). The bilateral symmetry presence of CSRCs in MSMs was significant but not in MFPs, MSPs, and MFMs. RGs were predominantly found on the mesiolingual (ML) surface of premolars and the lingual surface of molars. There was a high prevalence of CSRCs in MFPs and MSMs in the Eastern Chinese population, but there was no correlation. The prevalence of CSRCs in MFPs and MSMs differ significantly by gender (P < 0.05).

A CBCT based cross sectional study on the prevalence and anatomical feature of C shaped molar among Jordanian

The prevalence and anatomical features of C-Shaped Mandibular Second Molars (MSMs) are rarely studied in Jordanian sub-population. This study then took a part to evaluate the prevalence of C-shaped in MSMs using cone-beam computed tomography (CBCT) in the Jordanian sub-population. It used a cross-sectional design and three thousand scans collected over eight years between 2011 and 2019. The data were then reviewed for whether they were fully formed of MSMs. A total of 2037 cases that had 2845 MSMs were evaluated to identify C-shaped canals at coronal, middle, and apical sites. An oblique slicing module perpendicular to the long axis of MSMs was used to evaluate the teeth. The type and frequency of C-shaped canals, as well as the correlations between sex and side (right/left) and between sex and groove direction (buccal/lingual) were measured using the chi-square test on SPSS software at the significance level of 95%. A total of 342 teeth of 243 patients were C-shaped molars, which comprised 12% of the patient's teeth and 99 of them as a bilateral C-shaped canal with mean age of 40 years and sex ratio of 2:1 between female and male. With the limitations of this study, the lingual groove and type 3 were the most common properties of MSM. Besides, the Jordanian population mostly had C-shaped canals.

Variations of root and canal morphology of mandibular second molars in Chinese individuals: a cone-beam computed tomography study

BACKGROUND

The mandibular second molars demonstrate variations on root and canal morphology. The aim of this study was to investigate all the root canal morphology of mandibular second molars and analyze the morphological variations in patients by gender and age in a Chinese population use CBCT imaging.

METHODS

Cone-beam computed tomographic images of 1200 bilateral mandibular second molars were obtained from 600 patients (300 females and 300 males) who required a preoperative assessment for implant surgery, surgical removal of impacted teeth, orthodontic treatment, surgery of maxillofacial tumour and cysts or LeFort I osteotomy. CBCT images were divided into 5 groups according to age: "15-24 years", "25-34 years", "35-44 years", "45-54 years" and "≥ 55 years"; and 2 groups by gender: "females" and "males". The following information were recorded: the number of roots and canals and their morphology, the frequency and configuration of C-shaped canals by gender, age and position (left and right). The chi-square test was used to analyse differences between groups. P value of < 0.05 was considered statistically significant.

RESULTS

Of the 1200 teeth, 61% had two separate roots located mesiodistally, 35.6% had one C-shaped root. The 45.3% teeth had three canals in two-rooted mandibular second molars. The mesial root showed a Vertucci type II configuration in 28.9% cases followed by type IV(24.4%). While the distal root showed a significant higher prevalence of type I configuration in 95.6%. In the examined 1200 teeth, 430 teeth (35.8%) had C-shaped root canals. The prevalence of C-shaped root canal systems was significantly higher in females (42.5%) than in males (29.1%) (P = 0.000), and did not differ with age (P = 0.126). The 80.4% C-shaped canals were bilateral (P = 0.000) and did not differ with side (left and right) (P = 0.758).

CONCLUSIONS

The most commonly observed root morphology for the mandibular second molars was 2 separate roots with three canals.The prevalence of C-shaped root canal is 35.8% and is more higher in females than in males.

Comprehensive evaluation of root and root canal morphology of mandibular second molars in a Saudi subpopulation evaluated by cone-beam computed tomography

BACKGROUND

The study's goal was to use Cone Beam Computed Tomography (CBCT) to assess the root and root canal anatomy of mandibular second molars with C-shaped root canal configurations in residents of the Hail district. The impact of gender and side on the frequency of root canal morphology was considered.

METHODS

The sample size for this study was 304 untreated mandibular second molars with completely developed roots on the right and left sides. Using CBCT on the teeth, the root form and canal morphology for each root are based on Vertucci's classification. The occurrence of canals in the shape of a C. The prevalence and resemblance of the left and right sides or men and females were investigated. The Chi-square test was performed to evaluate the findings.

RESULTS

Of the 304 mandibular second molars studied, 286 teeth had two roots (94.1%), whilst 13 (4.3%) were C-shaped root canal systems. 77 molars (25.3%) had two canal orifices, 219 (72.0%) had three canal orifices, and six (2.0%) and one (0.3%) had four and five root canal orifices, respectively. Type IV was the most common for mesial root, accounting for 57.7% of the sample (n = 176). For distal root, the most common occurrence was type I, which occurred 282 times (96.60%). The most prevalent root canal morphology was the presence of two canals in the mesial root and one canal in the distal root of teeth with two distinct roots (variant 3). (69.4%). The overall prevalence of C-shaped root canal systems is (4.3%) (n = 13).

CONCLUSIONS

The patient's race is an undeniable factor that influences root canal anatomy. The root canal morphology of mandibular second molars revealed significant differences between Saudi subpopulations. The majority of mandibular second molars had two roots and three root canals. When treating these molars, the presence of a C-shaped root canal system must be taken into account.

Observation of mandibular second molar roots and root canal morphology using dental cone-beam computed tomography

The mandibular second molars show various morphological features in the roots and root canal, and a gutter-shaped root (GSR) caused by fusion of the mesial and distal roots is frequently encountered. In this study the number of the roots associated with mandibular second molars were observed using dental cone-beam computed tomography (CBCT). For those with a GSR, determination of root morphology and root canal classification were performed. CBCT image data from 173 Japanese mandibular second molars were obtained. Using sliced images, the number of the roots and root morphology were determined. In cases with a GSR, the ratio for the fused roots was determined and root canal morphology features were classified. A GSR was found in 61 (35.3%), with greater prevalence in females. In addition, the overall ratio of the fused part to root thickness in those with a GSR was 48.7%, with no significant difference related to sex. Furthermore, a C-shaped root canal morphology was commonly observed in both males and females with a GSR. In the present cohort examined in Japanese, most of the mandibular second molar were found to have two roots, with a GSR noted in 35.5%. While a GSR was more often observed in females, a C-shaped root canal was the most common root canal morphology in both sexs. It is considered that assessment using CBCT findings is helpful for precise determination of root canal morphology and presence of a GSR in mandibular second molars.

Prevalence and morphology of C-shaped and non-C-shaped root canal systems in mandibular second molars

BACKGROUND

There are no cone-beam computed tomography (CBCT)-based data on the anatomy of mandibular second molars in an Australian population. This study investigated the prevalence and descending morphology of mandibular second molars with and without C-shaped canals using retrospective analysis of CBCT scans.

METHODS

Scans from 715 patients were screened for the presence of C-shaped canals and assessed for cross-sectional configuration at 5 axial levels. Non-C-shaped molars were assessed for other morphological characteristics. Data were modelled against patient, tooth and CBCT scan characteristics.

RESULTS

A total of 1278 teeth from 657 patients were evaluated. The overall prevalence of C-shaped canals was 13%. Cross-sectional configuration of C-shaped canals was variable, with an average of 2.8 unique cross-sections per tooth. Non-C-shaped teeth were predominantly Vertucci Type II (60%) and Type IV (29%) configurations in mesial roots, and Type I (91%) in distal roots. Additional roots occurred in 4.3% of teeth and there was a significant association between radix paramolaris and distal root bifurcation (P < 0.001).

CONCLUSIONS

Cross-sectional analysis confirmed the complexity and variability of C-shaped canals. Clinicians should be cognisant of the prevalence and variability of C-shaped root canal morphology and how this may affect endodontic treatment. © 2022 Australian Dental Association.

Radiographic Investigation of Root Canal Morphology of Permanent Mandibular Molars in Makkah Population (Saudi Arabia) Using Cone-Beam Computed Tomography

Objectives

This study aimed to analyze the root canal morphology of first and second permanent mandibular molars among Makkah population by using cone-beam computed tomography (CBCT).

Materials and Methods

CBCT images of two hundred eight patients were obtained from the Faculty of Dentistry, Umm Al-Qura University, Makkah, Saudi Arabia. In all images, mandibular first and second molars were evaluated for the number of roots and their morphology, number of root canals, canal configuration in each root according to Vertucci's classification, and the presence of a C-shaped canal.

Results

Most of the mandibular first molars had two roots (96.5%) and three root canals (77.7%). Type IV canal configuration prevailed (75.6%) in the mesial roots, and type I canal configuration prevailed (71.7%) in the distal roots. For the mandibular second molars, the majority had two roots (96.3%) and three root canals (82.7%). Type IV canal configuration prevailed (48%) in the mesial roots and type I (99.1%) in the distal roots. C-shaped canals were detected in 5.7% of the mandibular first molars and 4% of the mandibular second molars. There was no statistical difference between the mandibular first and second molars (P > 0.05) in the shape of the roots and the presence of the C-shaped canals.

Conclusion

Most of the mandibular molars in Makkah population presented with two roots and three root canals. The incidence of three-rooted mandibular molars was low, and it was higher in the first molars than second molars. The type IV root canal system prevailed in mesial roots and type I in distal roots.

The C-shaped Canal System in Mandibular Molars of a Saudi Arabian Population: Prevalence and Root Canal Configurations Using Cone-Beam Computed Tomography

Objectives: This retrospective study aimed to assess the prevalence of the C-shaped canal system in mandibular first and second molars in a Saudi Arabian population using cone-beam computed tomography (CBCT).

Materials and Methods: The sample included 300 CBCT images from adults aged 18 to 80 years (38.7 ± 17.9) (150 females and 150 males). All images were analyzed to detect the C-shaped root canal according to Fan’s criteria. We also categorized our findings according to the gender and direction of the longitudinal groove. Data were reported as frequencies and percentages. The Chi-squared test was used to analyze proportional differences, with the significance level set at ≤0.05.

Results: The C-shaped canals were observed in 146 mandibular first molars (24.33%) and 182 second molars (30.33%). Male patients had a significantly higher prevalence of C-shaped canals in mandibular second molars than females (P=0.003). The longitudinal groove was most typically detected on the root's lingual surface (53.35%).

Conclusion: The incidence of the C-shaped canal in a Saudi Arabian population was 27.33% in the mandibular molars. The longitudinal groove was mostly on the lingual surface. Males showed a higher prevalence of the C-shaped canal than females.

Root and Root Canal Configuration Characterization Using Microcomputed Tomography: A Systematic Review

This systematic review’s objective was to conduct a complete analysis of the literature on the root canal morphology using advanced micro-computed tomography. The electronic web databases PubMed, Scopus, and Cochrane were examined for research papers concerning the chosen keywords, evaluating the root canal morphology using Micro-CT, published up to 2021. The articles were searched using MeSH keywords and searched digitally on four specialty journal websites. DARE2 extended (Database of Attributes of Reviews of Effects) was used to assess bias risk. The information was gathered from 18 published studies that strictly met the criteria for inclusion. In the included studies, a total of 6696 samples were studied. The studies were conducted on either maxillary (n-2222) or mandibular teeth (n-3760), permanent anteriors (n-625), and Third molars (n-89). To scan samples, a Scanco Medical machine in was used in 10 studies, Bruker Micro-CT in 34, and seven other machines were utilized in the rest. Bruker Micro-CT software from Kontich, Belgium, VG-Studio Max 2.2 software from Volume Graphics, Heidelberg, Germany, was the most commonly used software. The minimum Voxel size (resolution) adopted in the included studies was 11.6 µm. However, 60 µm was the maximum. Most studies classified the root canal morphology using Vertucci’s classification system (n-16) and the four-digit system (n-6).

Assessment of C-Shaped Canal Morphology in Mandibular and Maxillary Second Molars in an Iraqi Subpopulation Using Cone-Beam Computed Tomography

Endodontic treatment is basically dependent on knowledge of the root canal anatomy. The goal of this study was to use cone-beam computed tomography (CBCT) imaging to examine the C-shaped canal configuration of mandibular and maxillary second molars in an Iraqi subpopulation. The prevalence and configurations of C-shaped canals were evaluated in 368 mandibular second molars and 369 maxillary second molars using CBCT scans. The effects of gender, age, and unilateral/bilateral on the presence of C-shaped canals were investigated. Chi-square and Fisher's exact tests were used to determine the level of significance (p ≤ 0.05), and kappa value was used to check reliability of results of the research. In mandibular second molars, the prevalence of C-shaped canals was 17.4%. The prevalence was significantly higher in females (23%) than males (10.4%) using the chi-square test. There is no significant difference in the prevalence of C-shaped canal depending on age and tooth position. The C2 type was the most common (56.3%). This prevalence did not differ with gender, age, or tooth position. In maxillary second molars, C-shaped canals were present in 7.9%. Type I (subtype C) (fusion of 2 root canals MB-DB) was the most common type of fused root (65.5%). There is no significant difference in the prevalence of C-shaped canal depending on the type of fused root, age, and tooth position. The majority of C-shaped canals in mandibular second molars were bilateral in both genders, but unilateral presence was more common in maxillary second molars in both genders. Within the limits of this study, C-shaped canals were found to be more common in mandibular second molars than in maxillary second molars in an Iraqi subpopulation.

Prevalence of C-shaped canal and related variations in maxillary and mandibular second molars in the Indian Subpopulation: A cone-beam computed tomography analysis

Aim

The aim of this study was to evaluate the prevalence and anatomical configuration of the C-shaped canal in permanent maxillary and mandibular second molars in the Greater Noida population by compiling the results of data that used cone-beam computed tomography (CBCT) analysis.

Subjects and Methods

CBCT images were taken from the archive in the department of oral medicine and radiology taken for diagnostic purposes referred by other departments in the dental college. Five hundred CBCT records of patients, between the age group of 15-40 years, containing maxillary second molars and mandibular second molars were selected and reviewed.

Statistical Analysis

Statistical analysis was done using the Chi-square test to find out the most common configuration of the C-shaped canal between maxillary and mandibular second molars.

Results

Hundred and ten out of 500 patients had C-shaped canals (22%). Among them, 58 teeth (52.7%) were continuous C-shaped canals, 41 teeth (37.3%) were semicolon-shaped canals and 11 teeth (10%) had separated canals. (Chi-square test value = 8.26, P = 0.024). Statistically significant difference was found in configuration types. Among the jaw type, 62 maxillary second molar presented with C-shaped canal (25.1%) and 48 mandibular second molar presented with C-shaped canal (18.9%) (Chi-square test value = 3.87, P = 0.276). However, the difference was statistically insignificant in relation to the jaw type.

Conclusions

Within the limitation of the study, we can conclude that the overall prevalence of C-shaped canals was 22% and the most common C-shaped canal configuration type was continuous (52.7%). However, no statistically significant difference was found in relation to jaw type.

The C-shaped root canal systems in mandibular second molars in an Emirati population

Our study aimed to describe the root and canal morphology of mandibular second molars in Emirati population and to study the prevalence and types of morphological change in C-shaped canal configuration along the root length in an effort to describe C-shaped molars as a unit. Cone beam computed tomography (CBCT) scans of Emirati patients were analyzed in multiple plans and root and canal configuration of mandibular second molars were evaluated. Moreover, specific types of morphological change in C-shaped canal configuration along root length were studied and reconstructed using 3D reconstruction software. A total of 508 mandibular second molars were evaluated. Among the non-C-shaped mandibular second molars, two separate roots were the most prevalent root morphology (78.3%). The mesial root's most common root canal configuration was Vertucci Type II (46.5%), and in the distal root, Vertucci Type I (90.5%). The prevalence of C-shaped mandibular second molars was 17.9% and was significantly prevalent (P < 0.001) in females. Specific types of morphological change in C-shaped molars along the root length were observed and described for the first time, in which the most common types of morphological change were C1-C2-C3d (18%), C1-C3c-C3d (15.4%), C4-C3c-C3d (7.7%), and C3c-C3c-C3d (7.7%). This study showed wide variations in the root and canal morphology in mandibular second molars in Emirati population with a relatively high prevalence of C-shaped canal configuration (17.9%). Moreover, specific types of morphological change in C-shaped configuration were detected and described for the first time in this population.

A novel system for classifying tooth root phenotypes

Human root and canal number and morphology are highly variable, and internal root canal form and count does not necessarily co-vary directly with external morphology. While several typologies and classifications have been developed to address individual components of teeth, there is a need for a comprehensive system, that captures internal and external root features across all teeth. Using CT scans, the external and internal root morphologies of a global sample of humans are analysed (n = 945). From this analysis a method of classification that captures external and internal root morphology in a way that is intuitive, reproducible, and defines the human phenotypic set is developed. Results provide a robust definition of modern human tooth root phenotypic diversity. The method is modular in nature, allowing for incorporation of past and future classification systems. Additionally, it provides a basis for analysing hominin root morphology in evolutionary, ecological, genetic, and developmental contexts.

Root canal morphology and variations in mandibular second molars: an in vivo cone-beam computed tomography analysis

BACKGROUND

The purpose of this study was to determine the anatomical variations of the root canal system of mandibular second molars using cone-beam computed tomography (CBCT).

METHODS

190 mandibular second molars cone-beam computed tomography images were reviewed. The evaluation was performed by a radiologist with endodontic experience and two endodontists trained with CBCT technology. Tooth position, number of root and root canals, C-shaped root canal system configuration, presence of extra root (radix), and radicular grooves were assessed. Data was statistically analyzed using The Chi-square test (α = 0,05) to determine any significant difference between gender and the total number of root and root canals, and any significant difference between gender and root canal anatomical variation.

RESULTS

Overall, 85.5% showed two separated roots, 12.1% a single root, 2.6% three roots or radix. 87.7% showed three root canals, 12.1% two root canals, 2.6% four root canals, and 1.6% a single root canal. 10% showed a single foramen, 75.3% two foramina, 13.6% three foramina and 1% showed four foramina.19.5% showed C-shaped anatomical variation, 51.4% in male patients, 48.6% in female patients. According to Fan classification: C1 13.6% in cervical third, C2 10% in the middle third, C3 17.3% in middle third, 15.5% in apical third, and C4 12.7% in the apical third. Root canals number in these samples were 5.4% a single canal, 21.6% two canals, 70.3% three canals, and 2.7% four canals. The root showed 46% with one foramen, 46% two foramina, and 8% three foramina. Radicular grooves 83.3% were found in the lingual area and 16.2% towards the buccal area.

CONCLUSIONS

The most prevalent anatomic presentation of the evaluated sample was a mandibular second molars with two roots, three root canals, and two apical foramina. Their variation was C-shaped root canals and Radix Paramolaris.

Evaluation of C-shaped canals in mandibular second molars of a selected patient group using cone beam computed tomography: prevalence, configuration and radicular groove types

The aim of the present study was to examine the prevalence, symmetry and configurations of C-shaped canals and radicular groove types in mandibular second molars according to age and sex in a Turkish sub-population using cone beam computed tomography (CBCT). In total, 674 CBCT images (368 females and 306 males, aged 18-76 years) of 1348 mandibular second molars were evaluated. The symmetry, configuration of C-shaped root canals, radicular groove types with age and sex were noted. One sample chi-square test and chi-square test were used to determine statistically significant differences. The statistical significance level was set at p < 0.05. Of the 1348 mandibular second molars evaluated, 10.7% had C-shaped root canals. C-shaped root canals appeared to be significantly more common in females than in males (p < 0.05). C1 (44.4%) was the most frequent configuration in the coronal third, and C2 (44.4%), and C4 (31.9%) were the most frequent configurations in middle and apical thirds, respectively. Type 2 (45.1%) was the most common radicular groove type (p < 0.05). The frequency of C-shaped root canals in mandibular second molars in a Turkish sub-population was considerably high (10.7%). CBCT can aid the detection of C-shaped canals and their configurations. Dentists should consider the possibility of C-shaped canals in root canal treatment of mandibular second molars, as these configurations have implications for biomechanical preparation and filling methods.

Effectiveness of various endodontic systems in treating teeth with C-shaped root canals

Introduction — C-shaped configuration is amongst the most complicated root canal varieties requiring additional effort for successful endodontic treatment. The goal of this study was the laboratory comparison of the endodontic treatment efficiencies via XP-endo vs. Gentlefile systems for the teeth with C-shaped root canals. Material and Methods — In laboratory settings, 36 teeth with established C-shaped configuration, extracted for medical reasons (24 mandibular premolars and 12 mandibular second molars), underwent the root canal treatment by XP-endo (XP) and Gentlefile (GF) systems. Treatment quality was evaluated on the basis of dye penetration tests and examination of root dentinal surface with a scanning electron microscope. The significance of differences between the groups was assessed via Mann-Whitney U test. Results — For GF instruments, the average size of stained area in the apical third of teeth was 3.33±2.73%, while in the coronal third it amounted to 13.49±13.58%. The results of using the XP instruments demonstrated the average size of stained area in the apical third equal to 15.45±12.48%, while in the coronal third it was 37.30±14.06%. The scanning electron microscopy revealed a rougher surface of dentin and the remnants of stained layer in root canals treated with GF system. Conclusion — Thus, XP instruments exhibited a better treatment quality compared with GF system. The obtained data may justify the choice of instruments for endodontic teeth treatment in case of an intricate root canal system.

Root dentine thickness in C-shaped lower second molars after instrumentation: A CBCT and micro-CT study

Stripping perforation is a possible complication in instrumentation of C-shaped canals. This study evaluated the minimum thickness of the root canal wall in C-shaped teeth after instrumentation. Twelve extracted C-shaped mandibular second molars (four teeth of type I, II and III each) were examined by CBCT (voxel size 90 μm) before and after instrumentation with WOG primary file. Micro-CT scans (voxel size 30 μm) were obtained after instrumentation. Percentage of canal wall area touched by the file and minimum thickness of dentine were measured and compared between CBCT and micro-CT. In type I C-shape canals, less than 10% of the canal wall area was touched by the instrument. In ten teeth, the shortest distance to root surface was from the instrumented area; no perforations occurred. CBCT and micro-CT measurements were in good agreement in ten cases; in two teeth, micro-CT revealed considerably shorter distance to root surface. The two shortest distances were 0.27 and 0.41 mm.

Root canal morphology of South Asian Indian mandibular first, second, and third molar: A dye penetration and clearing study

Context:

Studying in detail the root canal morphology specific to the Indian mandibular molars will help discern whether the root canal anatomy patterns resemble those reported internationally or are different from it.

Aim:

The aim is to study the root canal anatomy of Indian permanent mandibular first, second, and third molar teeth using a tooth clearing technique.

Methods:

The root canals of a total of 300 extracted Indian mandibular molars consisting of 100 first, second, and third molars each were accessed and injected with India ink, after which they were subjected to the clearing technique.

Statistical Analysis:

Data was analyzed using descriptive statistics for the computation of percentages using SPSS version 21.

Results:

Of the hundred first molars, 90% of teeth were two rooted with three canals, 79% had two apical foramina. 70% mesial roots of the three-rooted type showed Type I, whereas 100% distal roots and distolingual roots showed Type I Vertucci’s anatomy. About 70% mesial roots of two roots showed Type II and 90% distal canals showed Type I configuration. Among the second molars, five (5%) were single-rooted, ninety-one (91%) teeth were two rooted and four (4%) had three roots. Among the mandibular third molars, fifteen (15%) teeth had one root, sixty-three (63%) teeth had two roots, eighteen (18%) teeth had three roots, and four (4%) teeth had four roots.

Conclusions:

The root canal anatomic features of mandibular molars showed differences in the frequency of particular anatomic types as compared to mandibular molars from other racial backgrounds. Further comparative studies on inter-racial anatomic characteristics from various geographic locations would be beneficial.

Root and Canal Morphology of Mandibular Second Molars in a Yemeni Population: A Cone-beam Computed Tomography

Objective:

This study aimed to identify and characterize root and canal morphology and the prevalence of C-shaped canals of mandibular second molars (MSMs) in a Yemeni population using cone-beam computed tomography (CBCT).

Methods:

Three-dimensional digital images of 500 MSMs with mature roots were taken from 250 Yemeni individuals and analyzed for the following features: number of roots, shape and type of roots, type of canal configuration in each root, prevalence of C-shaped canal, and primary variations in the morphology of root and canal systems. Chi square and Fisher’s exact tests were employed for statistical analysis.

Results:

89.6% of MSMs had two separate roots, 9% had two fused roots, 0.6% had three separate roots and 0.8% had one root. Mesial root was mostly ribbon-shaped (60.5%) and distal root was mostly kidney-shaped (50.7%). Type II and Type I canal configurations were the most frequent in mesial (56.9%) and distal (91.3%) roots, respectively. C-shaped canals were found in 9%. Six variants were found with variant 3 being the most common (71%).

Conclusion:

Yemeni MSMs are mainly two-rooted. The prevalence of three- and one-rooted MSMs was relatively low. Various canals configurations were found in MSMs among this sample of Yemeni population. The clinicians should consider C-shaped roots and canals when treating Yemeni MSMs and should be aware of their morphological variations to ensure successful root canal treatment. Although bilateral similarity of many anatomical features of MSMs was found, individual evaluation of each MSM is necessary while performing endodontic treatment on both sides.

Prevalence and Morphology of C-Shaped Canals: A CBCT Analysis in a Korean Population

This retrospective study of roots with C-shaped canals investigated their prevalence, configuration type, and lingual wall thickness, as well as the panoramic radiographic features of roots in permanent mandibular second molars confirmed to have C-shaped canals on cone-beam computed tomography (CBCT) in a Korean population. In total, 1884 CBCT images of mandibular second molars were examined by two endodontists to analyze the presence of C-shaped canals according to age and sex. The bilateral occurrence of C-shaped roots and their morphology on panoramic radiography were assessed and statistically analyzed using the chi-square test. The classification of Fan et al. was applied to categorize the configurations of C-shaped canals. The lingual wall thickness was calculated in the mesial, middle, and distal areas at the orifice and at 5 mm from the apex. The Mann-Whitney U test was used to analyze the mean difference of lingual wall thickness between the apex and orifice level. A P value of 0.05 was considered to indicate statistical significance in the statistical analyses. Of 2508 mandibular second molars, 924 (36.8%) had C-shaped root canals. The prevalence was significantly lower in the over 61 age group (24.08%) than in the 21-30-year age group (40.02%) and was higher in women (42.32%). Most cases were bilateral (85.9%). The C1 type was the most common (35.3%). The prevalence of C1 type canals decreased, while that of C3b type canals increased with age. In 75.2% of teeth having C-shaped root canals on CBCT, fused roots were observed on panoramic views. The difference in the lingual wall thickness at the orifice and 5 mm from the apex was significant in the middle area in all configurations of C-shaped root canals. When performing nonsurgical or surgical endodontic procedures of the mandibular second molars, clinicians should consider age, sex, ethnicity, and anatomical variations.

Disinfecting and Shaping Type I C-shaped Root Canals: A Correlative Micro-computed Tomographic and Molecular Microbiology Study

INTRODUCTION

This ex vivo study compared the disinfection and shaping abilities of 2 preparation protocols in C-shaped canals.

METHODS

Mandibular second molars with type I C-shaped canals were pair matched based on micro-computed tomographic (micro-CT) analysis and distributed into 2 groups. The canals were contaminated with a mixed bacterial culture and prepared using 2 protocols, both with 2.5% sodium hypochlorite irrigation: XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland) supplemented with XP-endo Finisher (FKG Dentaire) (XP-E) and BioRaCe (FKG Dentaire) supplemented with a Hedström file (Dentsply/Sirona, Tulsa, OK) (BR-Hed). Micro-CT scans and intracanal bacteriologic samples were taken before (scan #1 and sample 1) and after preparation (scan #2 and sample 2) and after the supplementary step (scan #3 and sample 3). Canal shaping was evaluated by micro-CT imaging, and disinfection was assessed by quantitative polymerase chain reaction.

RESULTS

Micro-CT data from the XP-E (n = 21) and BR-Hed (n = 23) protocols revealed no significant differences between groups regarding shaping parameters (canal volume, surface area, structure model index, and prepared walls) after preparation and after the supplementary step (P > .05). All these parameters significantly increased after each preparation step (P < .05), except for structure model index changes after the XP-endo Finisher (P > .05). Bacteriologic data from the XP-E (n = 21) and BR-Hed (n = 22) groups showed that 14 (66.7%) and 10 (45.5%) S2 samples still had detectable bacteria, respectively. The corresponding figures for supplementary steps with the XP-endo Finisher and Hedström file were 11 (52.4%) and 10 (45.5%), respectively. Bacterial counts in sample 1 significantly decreased in samples 2 and 3 in both groups (P < .01). Intragroup comparison between sample 2 and sample 3 showed a 66% reduction in counts after using the Hedström file and 18% after using the XP-endo Finisher (P > .05 for both groups). The quantitative bacterial reduction was not different between groups (P > .05).

CONCLUSIONS

The XP-endo Shaper and BioRaCe systems have similar disinfecting and shaping abilities in C-shaped canals. Supplementary steps with the Hedström file and the XP-endo Finisher were similarly effective in improving shaping, but this was not sufficient to enhance disinfection. About half of the cases, in both groups, still harbored detectable amounts of bacteria.

Cone-beam computed tomography classification of the mandibular second molar root morphology and its relationship to panoramic radiographic appearance

OBJECTIVES

This study aimed to clarify the relationship between the panoramic radiographic appearance and the longitudinal cone-beam computed tomography (CBCT) classification of root configurations of the mandibular second molar.

METHODS

Panoramic radiographs of 1058 mandibular second molars were classified into five types according to the number and configuration of the roots. These molars were also examined with CBCT at four levels between the pulp chamber and the root apex, and axial images perpendicular to the root axis were categorized into three patterns: single (fused root with small grooves on both buccal and lingual sides or a round root with one canal); double (two separate roots with a trabecular appearance between them); and C-shaped (root with a deep groove opening only on the lingual or buccal side relative to the opposite side). Based on these patterns and their scan levels, the CBCT root morphology appearance in each tooth unit was classified into seven groups. Relationships were investigated between these seven CBCT groups and the five panoramic root types.

RESULTS

In panoramic types 1 and 2 (with separate roots), 85% had roots with a double pattern (groups II and III) on the CBCT images. In panoramic types 3 and 4 (with fused roots), 85% had C-shaped CBCT patterns at the lower scan levels.

CONCLUSIONS

When panoramic images show fused root types, CBCT examinations should be planned to clarify the root canal configuration.

Mandibular molar C-shaped root canals in 5th millennium BC China

OBJECTIVE

The aim of this study was to analyze the occurrence and variations in C-shaped canals in ancient Chinese teeth and compare the differences of these features between ancient and age-matched modern populations.

DESIGN

Approximately 5000-year-old craniofacial bone remains were collected from the fossils of 38 individuals (total: 68 mandibular second molars) excavated from the Jiaojia site. The control group comprised of an equal number of randomly selected modern samples. We used cone-beam computed tomography to scan the mandible along the apex-crown axis and analyzed the canal morphology, based on Fan's categorization criterion, at 2 mm, 5 mm, and 8 mm to the apical level. Grooves on the lingual and buccal sides were also recorded.

RESULTS

The proportion of C-shaped roots among ancient samples on the left and right sides were 48.57 % (17/35 teeth) and 54.55 % (18/33 teeth), respectively, and 51.47 % (35/68 teeth) in the total sample. Conversely, in the control group, 44.12 % (15/34) and 38.24 % (13/34) occurred on the left and right sides, respectively, and 41.18 % (28/68) in the total sample. Among the C-shaped canals from the Jiaojia site samples, the classification type changed between two adjacent levels in 84.31 % of samples. Approximately 35 (51.5 %) teeth had a fused root, 20 (29.41 %) had one shallow buccal and one deep lingual groove. The occurrence of C-shape variation was not significantly correlated with time (p＞0.05).

CONCLUSIONS

This study identified a high rate of C-shaped root canals among individuals of Jiaojia who lived approximately 5000 years ago.

C-shaped canals in mandibular molars of a Brazilian subpopulation: prevalence and root canal configuration using cone-beam computed tomography

OBJECTIVES

To assess C-shaped root canal configuration by identifying its prevalence and each configuration type proportion, according to tooth (mandibular first or second molar) and demographic characteristics in a Brazilian population, using cone-beam computed tomography (CBCT). Moreover, it was verified if there is a relationship between root canal configuration observed in two-dimensional reconstructions of CBCT and presence of C-shape.

METHODS

Mandibular jaw CBCT scans (184 males and 220 females, aged 15 to 80 years), which presented 1464 mandibular molars (710 first molars and 754 second molars), were assessed. Teeth were evaluated for the presence and type of C-shaped root canals by observing the roots at five levels in CBCT axial reconstructions. Root canal configuration was assessed in panoramic reconstructions. Data were statistically analyzed at a significance level of 5%.

RESULTS

Of the 1464 mandibular molars, 125 (8.5%) were classified as C-shaped. This variation was more prevalent in females (n = 107, 85.6%) and in second molars (n = 108, 86.4%). C1 (uninterrupted C-shaped canal) was the most prevalent type of C-shaped configuration (41.76%), while C5 (no canal lumen) was the least prevalent type (0.96%). Single root with single canal in panoramic reconstructions was the most predominant configuration for C-shaped teeth (n = 54, 43.2%). Fused roots presented 17.2 higher odds of being associated with C-shaped root canals than non-fused roots.

CONCLUSIONS

C-shaped root canals were more prevalent in mandibular second molars and in females. Additionally, clinicians should bear in mind the greater possibility of C-shaped configuration in mandibular molars with fused roots.

CLINICAL RELEVANCE

Mandibular molars with C-shaped canals present a clinical challenge. A higher C-shaped proportion was noted in radiographic fused root types, which had 17.2 higher odds of presenting such anatomy when compared to radiographic non-fused roots. Root radiographic features may help in diagnosis of complex C-shaped morphologies.

Comparison of continuous wave and cold lateral condensation filling techniques in 3D printed simulated C-shape canals instrumented with Reciproc Blue or Hyflex EDM

Aim

To compare the efficiency of continuous wave obturation and cold lateral condensation techniques and filling time in C-shape canals of 3-dimensional (3D)-printed resin teeth shaped with Reciproc Blue (VDW) or Hyflex EDM (Coltene/Whaledent).

Methodology

One tooth with C1-type orifice and root canal morphology and one with C2-type orifice and C2-C3 root canal morphology were selected based on CBCT. Two replicas of selected teeth were manufactured with a 3D-printer and their canals were instrumented with Reciproc Blue or Hyflex EDM. These 4 instrumented replicas were scanned with CBCT. Identical 10 replicas of each group (total of 40) were produced using a 3D-printer and randomly divided into 2 groups (n = 5), root filled with either continuous wave obturation (CW) or cold lateral condensation (LC). Horizontal cross-sections of C1-type were made at 2, 4, 6, 8 mm and C2-type at 2, 4, 6 mm from the apical foramen. Gutta-percha, sealer and void areas were evaluated with image analysis sofware. Data were analysed using nonparametric Kruskal-Wallis and Mann Whitney-U tests and the Factorial ANOVA was used for interaction effects. Time required to fill canals was evaluated using the Mann-Whitney U test.

Results

For C1-type, LC had more gutta-percha and less sealer compared to CW in 2-mm sections (p<0.05). CW had greater percentages of gutta-percha and lower percentages of sealer compared with LC group in 4, 6, 8 mm sections and total area (p<0.05). LC group had higher percentages of voids compared to CW group in 2 and 4 mm sections (p<0.05). For C2-type, CW had more gutta-percha and less sealer versus LC group in all sections and total area (p<0.05). LC had the least gutta-percha and greatest sealer percentages at 6-mm sections (p<0.05). There was no statistically significant difference in the percentages of voids at any level of sections between the filling techniques (p>0.05). In both C-types, there was no significant difference in the percentages of gutta-percha, sealer and voids between Reciproc Blue and Hyflex EDM-shaped groups at any level (p>0.05). Time spent for the LC technique and filling C1-type was significantly longer than when using the CW technique and filling C2-type (p<0.05).

Conclusions

Continuous wave obturation was more effective than lateral condensation in both C1- and C2-type, except for the apical 2 mm section of C1-type, suggesting the need for a modified CW technique.

Analysis of root canal system of maxillary first and second molars and their correlations by cone beam computed tomography

BACKGROUND/PURPOSE

Understanding the root canal systems of molars and the association of root canal system in adjacent or contralateral molars is important for dental practice. This study aimed to use cone-beam computed tomography (CBCT) to analyze the morphology similarity of root canal systems in the maxillary first and second molars.

METHODS

CBCT images of 1741 maxillary molars in a total of 519 patients were blindly examined to analyze the correlation of root canal systems between maxillary first and second molars as well as the bilateral first and second molars.

RESULTS

The most common type in maxillary first molars is 3R4C (3 roots/4 canals), whereas in maxillary second molars is 3R3C.The symmetry in type of root canals in bilateral maxillary first and second molars were 87.36% and 79.85%, respectively. The similarities of root canal system in adjacent maxillary first and second molars were 53.07% (right side) and 52.58% (left side). The concurrence of MB2 canal in bilateral maxillary first molars is 77.8%, and 35.97% in maxillary second molars. In the 110 patients with MB2 canal in bilateral maxillary second molars, the chance of bilateral MB2 canals in their maxillary first molar is almost 100%.

CONCLUSION

Maxillary first molars have higher prevalence of 3R4C than second molars. The symmetry in bilateral maxillary molars is higher than the similarity in adjacent maxillary first and second molars. Application of CBCT analysis of root canal system can improve endodontic treatment outcomes. The correlation of root canal system between teeth is useful for genetic linkage.

Prevalence of C-shaped mandibular molars in the Portuguese population evaluated by cone-beam computed tomography

Objective:

The purpose of this study was to evaluate the prevalence of first and second C-shaped mandibular molars in a Western European population of Portuguese Caucasians.

Materials and Methods:

Patients having both routine panoramic radiograph and presurgical cone-beam computed tomography (CBCT) exams were selected. The CBCT examination was performed at five different axial levels and the mandibular molars were classified as C-shape according to the Fan criteria. Differences between genders, age groups, left and right side, type of tooth, and root concavity side were determined. The molars were classified as nonfused roots (NFRI–II), FRI–III, or single root with single canal (SS) groups, using the panoramic radiograph. The prevalence of C-shaped anatomy was calculated to each group.

Results:

A total of 1783 teeth (695 first molars and 1088 second molars) from 792 patients were included in the study. The prevalence of C-shaped configurations was 0.6% and 8.5% to mandibular first and second molars, respectively. The differences between gender, teeth, and root concavity direction were considered statistically significant (P < 0.05). The FR had a significantly higher rate of C-shapes when compared to NFR (P < 0.05). Intrarater reliability was 93.6%.

Conclusions:

The FR radiographic appearance may be considered a predictor of this anatomy. Second mandibular molars and females had a higher incidence ratio. Apparently, the mandibular C-shaped anatomy is more common in the population of this study than that has been previously reported for the European population.

Investigation using cone beam computed tomography analysis, of radicular grooves and canal configurations of mandibular premolars in a Turkish subpopulation

OBJECTIVE

To conduct an in vivo evaluation of prevalence of root canal configurations, lengths of C-shaped canals, prevalence and depths of radicular grooves (RGs), in mandibular first and second premolars in a Turkish subpopulation using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

CBCT images of 327 first and 264 second premolars were included. Canal configurations, locations, lengths, and types of C-shaped canals, and RGs were evaluated on CBCT images. Data were statistically analyzed (P < 0.05).

RESULTS

First and second premolars were classified as follows: type I, (83.8%, 97.72%); type V, (12.22%, 0.76%); type III, (3.06%, 0.76%); and other types. RGs were exhibited by 14.68% of first and 2.27% of second premolars (P < 0.05). Incidence of complex canals (types III, V and other types, 89.8%) in first premolars with RGs was significantly higher versuswithout RGs (P < 0.05). C-shaped configuration was exhibited by 4.58% of first (80% semilunar-type), and 1.13% of second premolars (P < 0.05). All first premolars with C-shaped canals showed RGs and complex canals.

CONCLUSIONS

Complex canals and RGs frequently co-exist in mandibular premolars. C-shaped canals are not common in mandibular premolars, and mostly located in middle thirds. Type V is the most prevalent complex canal configuration in first premolars, and frequently associated with a C-shaped semilunar-type anatomy.

Evaluation of Root and Root Canal Morphology of Mandibular First and Second Molars in a Greek Population: A CBCT Study

Objective:

Τo study the number of roots, canal configurations, and frequency of morphological variations in mandibular first and second molars in a Greek population.

Methods:

This study examined 478 mandibular first molars and 524 mandibular second molars using a high-resolution cone-beam computed tomography (CBCT). The number of roots was recorded and the root canal configuration was categorized based on the classification by Vertucci. The presence and configuration of C-shaped root canals were recorded and they were classified according to the Fan classification. The symmetry between the right and the left side was also evaluated.

Results:

Among the mandibular first molars, 0.2% teeth were single-rooted, 96.4% were two-rooted, and 3.3% were three-rooted. In the mandibular second molars, 12.2%, 82.8%, and 4.9% were single-rooted, two-rooted, and three-rooted, respectively. In two-rooted mandibular first and second molars, the most frequent root canal pattern observed was Vertucci’s type II in the mesial root (69.8% and 64.1%, respectively) and Vertucci’s type I in the distal root (81.7% and 97.7%, respectively). Three-rooted molars showed one oval-shaped mesial root and two distal roots (56.2% in first molars, 65.4% in second molars), where each distal root contained a single root canal (type I), and the mesial root presented either type II (53.3%), IV (26.6%), I (13.3%), or V (6.6%) canal configurations. C-shaped canals were only detected in mandibular second molars (5.3% of teeth, 10.8% of individuals), and bilateral occurrence was observed in 24.5% patients. The most frequent root canal pattern was Fan’s C1 type at the orifice, followed by C3a and C3b in the coronal and middle third, which joined into a single canal (C4) apically.

Conclusion:

The characteristics of the root and root canal anatomy of the mandibular first and second molars of Greek individuals were similar to those observed in Caucasians. However, the higher incidence of third roots in mandibular molars in Greek individuals compared to Caucasians requires absolute clinical awareness.

Root canal morphology of permanent teeth in a Malaysian subpopulation using cone-beam computed tomography

Background

To determine the root canal morphology of human permanent maxillary and mandibular teeth in a Malaysian subpopulation using cone-beam computed tomography (CBCT).

Methods

A total of 208 CBCT images were examined retrospectively. Prevalence of an extra root/canal and internal morphology based on Vertucci’s classification were observed in human maxillary and mandibular permanent teeth. Variations in the external and internal morphology were compared in relation to gender and tooth side (left vs right) using Pearson Chi-square and Fisher’s exact tests with significance level set at p < 0.05.

Results

In the maxillary arch, the prevalence of three canals were observed in 0.3% of first premolars and two canals in 46.5% of second premolars. Males displayed significantly higher prevalence of two canals in maxillary second premolars than females (p < 0.05). The prevalence of a second mesiobuccal canal in maxillary first and second molars were 36.3 and 8.5%, respectively. Males displayed significantly higher prevalence of a second mesiobuccal canal in maxillary second molars than females (p < 0.05). The prevalence of a second palatal canal in maxillary first and second molars were 0.9 and 0.6%, respectively. In the mandibular arch, the prevalence of two canals were observed in 5.1% of central incisors, 12.3% of lateral incisors, 6.1% of canines, 18.7% of first premolars and 0.5% of second premolars. The prevalence of a middle mesial canal, second distal canal and extra root (radix entomolaris) were detected in 1.9, 19.5 and 21.4% of mandibular first molars, respectively. The prevalence of a C-shaped canal was observed in 48.7% of mandibular second molars. Females displayed significantly higher prevalence of a C-shaped canal in the right mandibular second molars than males (p < 0.05). No other statistically significant differences in root anatomy and root canal morphology were observed in relation to gender and tooth side.

Conclusions

Wide variations in the root canal morphology exist among Malaysians. CBCT is a clinically useful tool in the identification of external and internal morphological variations in the human teeth.

Racial predilection of C-shaped canal configuration in the mandibular second molar

Aim:

The purpose of this article is to determine the racial predilection of C-shaped canal configuration in a mandibular second molar.

Background:

Unusual root canal anatomy always poses a diagnostic and treatment challenge. Identification of such variation is important for the success of root canal treatment outcome. C-shaped canal configuration is such an aberrant morphology of molar teeth that vary in different population and is commonly seen in a mandibular second molar. Thus, knowledge of racial predilection of C-shaped canal configuration in different population for early diagnosis is obligatory.

Materials and Methods:

An exhaustive search was undertaken to identify published research articles related to C-shaped canal configuration in mandibular second molars. Forty-three research articles were analyzed which included 12,481 mandibular second molars. Chi-square test using value of P < 0.05 was performed to assess the statistical significance of this anomalous anatomic variation among the different population.

Results:

Statistical test revealed a significant variation between the Asian and nonAsian population. The highest incidence of racial predilection was observed in China (Asia) with 93.1%, and the minimum was observed in America with 2.7%.

Conclusion:

This research reported that racial predilection of C-shaped canal configuration in mandibular second molar varies significantly.