C-shaped root canals of mandibular second molars in a Korean population: clinical observation andin vitroanalysis

Prevalence of Radix Entomolaris in Mandibular Permanent Molars Analyzed by Cone-Beam CT in the Saudi Population of Ha'il Province

BACKGROUND

The present study aimed to examine the prevalence of radix entomolaris (RE) in the mandibular permanent molar within a specific sub-population in Saudi Arabia.

METHODS

A comprehensive analysis was conducted on 499 cone-beam computed tomography (CBCT) scans of a mandibular molar from a sample of Saudi patients aged between 18 and 65. The primary objective of this study was to investigate the anatomical characteristics of mandibular permanent molars, specifically focusing on the number of roots present. The chi-square test was employed to examine the relationship between various variables.

RESULTS

In the case of mandibular first molars, it was observed that 95.3% of these molars exhibited a bifurcated root structure. In comparison, the remaining 4.7% displayed a triradicular configuration within the sample population under investigation. Although there were some variations, no significant differences in the number of roots were observed between males and females or left and right sides (p > 0.05). In the case of mandibular second molars, it was observed that 96.9% of them exhibited a bifurcated root structure, whereas 2.5% displayed a trifurcated root configuration, and a mere 0.6% possessed a single root. There were no statistically significant variations in the number of roots between males and females or left and right sides (p > 0.05).

CONCLUSIONS

The identification of RE was observed in the mandibular molars. Moreover, the discovered RE roots were predominantly found in the mandibular first molar, displaying a tendency for bilateral occurrence in both male and female individuals.

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.

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.

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.

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).

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.

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.

Deep-learning for predicting C-shaped canals in mandibular second molars on panoramic radiographs

OBJECTIVE

The aim of this study was to evaluate the use of a convolutional neural network (CNN) system for predicting C-shaped canals in mandibular second molars on panoramic radiographs.

METHODS

Panoramic and cone beam CT (CBCT) images obtained from June 2018 to May 2020 were screened and 1020 patients were selected. Our dataset of 2040 sound mandibular second molars comprised 887 C-shaped canals and 1153 non-C-shaped canals. To confirm the presence of a C-shaped canal, CBCT images were analyzed by a radiologist and set as the gold standard. A CNN-based deep-learning model for predicting C-shaped canals was built using Xception. The training and test sets were set to 80 to 20%, respectively. Diagnostic performance was evaluated using accuracy, sensitivity, specificity, and precision. Receiver-operating characteristics (ROC) curves were drawn, and the area under the curve (AUC) values were calculated. Further, gradient-weighted class activation maps (Grad-CAM) were generated to localize the anatomy that contributed to the predictions.

RESULTS

The accuracy, sensitivity, specificity, and precision of the CNN model were 95.1, 92.7, 97.0, and 95.9%, respectively. Grad-CAM analysis showed that the CNN model mainly identified root canal shapes converging into the apex to predict the C-shaped canals, while the root furcation was predominantly used for predicting the non-C-shaped canals.

CONCLUSIONS

The deep-learning system had significant accuracy in predicting C-shaped canals of mandibular second molars on panoramic radiographs.

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.

Knowledge, attitude and practice regarding the use of dental operating microscope in pediatric dentistry in India: An online survey

Background and aim

Literature search shows scarcity of information regarding the use of Dental Operating Microscope (DOM) in children. There are various factors that limit the use of this novel technology by Pediatric Dentists in their practice. The aim of this study is to assess the knowledge, attitude and practice of pediatric dentist regarding DOM use in children.

Method

The present study was a descriptive web based questionnaire study conducted among 363 Pediatric Dentists (PDs) of India. A close-ended questionnaire was prepared to test the KAP regarding microscope use among PDs. Results obtained were analyzed using descriptive analysis in SPSS software and correlation was studied using chi-square test where statistical significance was observed at p ​< ​0.05.

Results

A response rate of 82.1% was observed. Majority (88.9%) of the pediatric dentists were aware of Dental operating Microscope (DOM) usage in their field, however, only 61.4% were aware of its magnification levels. 76.5% participants responded 12^oclock position to be the ideal position. Majority (94.0%) agreed that DOM is helpful in locating canals in deciduous teeth. 70.5% think that DOM can increase apprehension of children. 85.2% believed that DOM can aid in behavior management of children through its live visual output. However, 84.2% of the pediatric dentists hadn't used DOM in their practice.

Conclusion

The knowledge, attitude and practice regarding dental operating microscope among pediatric dentists in India is limited. In the foreseeable future, the use of magnification is likely to become the standard of practice in dentistry.

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.

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.

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.

C-shaped canals in first and second mandibular molars from Brazilian individuals: A prevalence study using cone-beam computed tomography

Introduction

The study aimed to evaluate, through in vivo tomographic analysis, the prevalence of C-shaped canals in mandibular first and second molars of Brazilian individuals, analyzing its frequency by thirds of the roots, and in contralateral teeth.

Methods

Images of 801 mandibular molars (379 first molars and 422 second molars) from 334 Brazilian individuals (142 men and 192 women) were identified through 1544 cone beam computed tomography (CBCT) exams, obtained from a private oral radiologic clinic. The cross-sectional configurations were analyzed to determine the frequency of C-shaped canals at three different axial levels and classified in categories by three experienced endodontists independently.

Results

The incidence of C-shaped canals was 181 (23%). Considering the type of tooth, 91 (24.01%) were identified in the first molars, and 90 (21.32%) were found in the second molars. The incidence was significantly higher in female individuals (P < 0.05) for both first and second molars. The most common C-shaped canal configurations were: C1 (89.01% for first molars and 90% second molars), followed by C2 (8.79% for first molars and 6.66% for second molars) and C4 (2.19% for the first molars and 3.33% for the second molars). Bilateral C-shaped canals were significantly higher than unilateral for both first and second molars (P < 0.01).

Conclusions

The prevalence of C-shaped canals in mandibular molars of the Brazilian individuals was higher than previously reported for both mandibular first (24.01%) and second molars (21.32%). The incidence was significantly higher in female individuals and the coronal portion of the roots. The classic C-shaped format “C1” was the most frequent anatomical configuration. Furthermore, the prevalence of bilateral C-shaped canals was higher for the first molar (61.70%) and lower for the second molar (38.29%).

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.

C-shaped root canals of mandibular second molars in a Korean population: a CBCT analysis

Objectives

The purpose of this study was to investigate the C-shaped root canal anatomy of mandibular second molars in a Korean population.

Materials and Methods

A total of 542 teeth were evaluated using cone-beam computed tomography (CBCT). The canal shapes were classified according to a modified version of Melton's method at the level where the pulp chamber floor became discernible.

Results

Of the 542 mandibular second molars, 215 (39.8%) had C-shaped canals, 330 (53%) had 3 canals, 17 (3.3%) had 2 canals, 12 (2.2%) had 4 canals, and 8 (1.7%) had 1 canal. The prevalence of C-shaped canals was 47.8% in females and 28.4% in males. Seventy-seven percent of the C-shaped canals showed a bilateral appearance. The prevalence of C-shaped canals showed no difference according to age or tooth position. Most teeth with a C-shaped canal system presented Melton's type II (45.6%) and type III (32.1%) configurations.

Conclusions

There was a high prevalence of C-shaped canals in the mandibular second molars of the Korean population studied. CBCT is expected to be useful for endodontic diagnosis and treatment planning of mandibular second molars.

Evaluation of four instruments with different working motion using artificial plastic model with C-shaped single canal

The purpose of this study was to evaluate four instruments with different working motion for preparation of a C-shaped single canal wall using the same artificial plastic models reproduced from a human tooth. One tooth with root canal morphology C1 (the shape is an uninterrupted “C” with no separation or division) was selected among three-dimensional micro-computed tomography (micro-CT) imaging data of extracted human teeth. Imaging data were then converted into STL form data, and twenty-four C-shaped root canal model blocks were manufactured using this STL form data. These blocks were randomly divided into four groups of six blocks each and instrumented as follows: stainless steel K-files (SSK), Self-Adjusting File (SAF), ProTaper NEXT (PTN) and RECIPROC (REC). Micro-CT images taken before and after canal preparation were superimposed, and instrumented canal area, percentage of instrumented canal area, part of instrumented canal area, volume of instrumented canal and time taken for instrumentation were evaluated for each group. The greatest instrumented canal area, percentage of instrumented canal area and volume of instrumented canal were as follows (in decreasing order): SSK > SAF > PTN > REC (P < 0.05). The longest time taken for instrumentation was as follows (in decreasing order): SAF > SSK > PTN > REC (P < 0.05). The conscious shaping of SSK and the lattice structure of SAF were instrumented all root canal walls equally. PTN and REC required less time taken for instrumentation, but showed unequal instrumentation.

Anatomic Features of C-shaped Mandibular Second Molars in a Selected Iranian Population Using CBCT

INTRODUCTION

The aim of this retrospective study was to analyze the frequency of C-shaped root canal configuration and characterize mandibular root canal morphology using cone-beam computed tomography (CBCT) with 3D images in an Iranian population.

METHODS AND MATERIALS

This study consisted of retrospective evaluation of CBCT images from 231 adult patients (153 with bilateral second mandibular molars). Two endodontists examined 384 mandibular second molars of a population in Tabriz, Iran to determine the presence of C-shaped canals and their anatomical characteristics. Root canal configurations were categorized at three different levels. Bilateral or unilateral occurrence of C-shaped canals and their relationship to gender, age and tooth position were examined and statistically analyzed using chi squared test and Fisher's exact test in SPSS 17. The significance level was set at 0.05.

RESULTS

Of 384 mandibular second molars examined, 82 (21.4%) molars from 58 patients had a C-shaped root canal configuration. The prevalence of bilateral C-shaped canals was 15.6% amongst 153 patients with bilateral mandibular second molars. There were no significant differences in the distribution of C-shaped canals with respect to gender or age (P=0.06 and P=0.86, respectively). Only 4 teeth (4.9%) had the same root canal configuration from the orifice to the apex. In the remainder of the teeth, the cross-sectional root canal configuration changed at different levels of the root.

CONCLUSION

There were significant variations in the number of roots and canal morphology in mandibular second molars, which should be considered during debridement and obturation of the root canal system.

Prevalence of C-shaped canals in mandibular second and third molars in a central India population: A cone beam computed tomography analysis

Introduction

To evaluate the prevalence of C-shaped root canals in mandibular molars using cone beam computed tomography (CBCT) in a subpopulation of Central India.

Materials and Methods

CBCT scans of patients from diagnostic imaging center were selected in accordance with the criteria given by Fan et al. (2004) for C-shaped canals. A total of 238 CBCT scans fulfilled the inclusion criteria and thereby divided into two groups: Group 1: Images showing C-shaped canal configuration in mandibular second molars. Group 2: Images showing C-shaped canal configuration in mandibular third molars. The frequency and distribution of canals and their configuration along with the position of lingual/buccal grooves in the images were evaluated, and the data was analyzed.

Results

CBCT evaluation showed that 9.7% of second molars and 8% of third molars had C-shaped canals. A prominent buccal groove was seen in these teeth. The data showed a significant difference (P = 0.038) for the presence of such anatomy on the right side for mandibular third molars.

Conclusion

The study showed a significant prevalence of C-shaped canal configuration in the subpopulation studied.

Healing outcomes of root canal treatment for C-shaped mandibular second molars: a retrospective analysis

Objectives

This study aimed to evaluate the healing rate of non-surgical endodontic treatment between C-shaped and non-C-shaped mandibular second molars.

Materials and Methods

Clinical records and radiological images of patients who had undergone endodontic treatment on mandibular second molars between 2007 and 2014 were screened. The periapical index scoring system was applied to compare healing outcomes. Information about preoperative and postoperative factors as well as the demographic data of the patients was acquired and evaluated using chi-square and multinomial logistic regression tests.

Results

The total healing rate was 68.4%. Healing rates for the mandibular second molar were 70.9% in C-shaped canals (n = 79) and 66.6% in non-C-shaped ones (n = 117). The difference was not statistically significant.

Conclusions

The presence of a C-shaped canal in the mandibular second molar did not have a significantly negative effect on healing after treatment. Instead, proper pulpal diagnosis and final restoration were indicated as having significantly greater influence on the healing outcomes of C-shaped and non-C-shaped canals, respectively.

Differentiation of root canal morphology – a review of the literature

The morphological diversity of the inner anatomy of root canals in human permanent teeth is an issue mainly described in endodontics research. In recent years, it is a relatively new point in anthropological studies because it varies by sex, geographic and ethnic circumstances. An unusual number of root canals or their specific systems can differentiate populations around the world. The multiplicity of available methods for detecting root canal systems helps to better understand their complexity; however, most cannot be applied to anthropology due to limitations that occur in the bioarcheological material. Thorough knowledge of the heterogeneity and internal anatomy of the root canals supplies numerous classification systems proposed and improved over the years by many authors. A limited number of studies in the anthropological literature and future research will shed light onto the internal tooth morphology in historical populations. The aim of this paper is to describe various classification systems of root canals applied in endodontics. However, due to the often poor state of preservation and damage of archaeological derived remains, it seems that the best method is the approach that is the simplest and least complicated.

Analysis of C-shaped root canal configuration in maxillary molars in a Korean population using cone-beam computed tomography

OBJECTIVES

The purpose of this study was to investigate the incidence of root fusion and C-shaped root canals in maxillary molars, and to classify the types of C-shaped canal by analyzing cone-beam computed tomography (CBCT) in a Korean population.

MATERIALS AND METHODS

Digitized CBCT images from 911 subjects were obtained in Chosun University Dental Hospital between February 2010 and July 2012 for orthodontic treatment. Among them, a total of selected 3,553 data of maxillary molars were analyzed retrospectively. Tomography sections in the axial, coronal, and sagittal planes were displayed by PiViewstar and Rapidia MPR software (Infinitt Co.). The incidence and types of root fusion and C-shaped root canals were evaluated and the incidence between the first and the second molar was compared using Chi-square test.

RESULTS

Root fusion was present in 3.2% of the first molars and 19.5% of the second molars, and fusion of mesiobuccal and palatal root was dominant. C-shaped root canals were present in 0.8% of the first molars and 2.7% of the second molars. The frequency of root fusion and C-shaped canal was significantly higher in the second molar than the first molar (p < 0.001).

CONCLUSIONS

In a Korean population, maxillary molars showed total 11.3% of root fusion and 1.8% of C-shaped root canals. Furthermore, root fusion and C-shaped root canals were seen more frequently in the maxillary second molars.

Prevalence and features of distolingual roots in mandibular molars analyzed by cone-beam computed tomography

Purpose

This study evaluated the prevalence of distolingual roots in mandibular molars among Koreans, the root canal system associated with distolingual roots, and the concurrent appearance of a distolingual root in the mandibular first molar and a C-shaped canal in the mandibular second molar.

Materials and Methods

Cone-beam computed tomographic images of 264 patients were screened and examined. Axial sections of 1056 mandibular molars were evaluated to determine the number of roots. The interorifice distances from the distolingual canal to the distobuccal canal were also estimated. Using an image analysis program, the root canal curvature was calculated. Pearson's chi-square test, the paired t-test, one-way analysis of variance, and post-hoc analysis were performed.

Results

Distolingual roots were observed in 26.1% of the subjects. In cases where a distolingual root was observed in the mandibular molar, a significant difference was observed in the root canal curvature between the buccolingual and mesiodistal orientations. The maximum root canal curvature was most commonly observed in the mesiodistal orientation in the coronal portion, but in the apical portion, maximum root canal curvature was most often observed in the buccolingual orientation.

Conclusion

The canal curvature of distolingual roots was found to be very complex, with a different direction in each portion. No correlation was found between the presence of a distolingual root in the mandibular first molar and the presence of a C-shaped canal in the mandibular second molar.

Endodontic management of C-shaped root canal system of mandibular first molar by using a modified technique of self-adjusting file system

AIM

C-shaped canal system is a seldom-found root canal anatomy which displays a challenge in all stages of endodontic treatment. According to the literature, this type of canal morphology is not a common finding in the mandibular first molar teeth.

BACKGROUND

This case report presents endodontic management of a mandibular first molar with a C-shaped canal system.

CASE REPORT

Root canal system was cleaned and shaped by nickel-titanium (NiTi) rotary instruments combined with self-adjusting file (SAF). Obturation was performed using warm, vertical condensation combined with the injection of warm gutta-percha. Follow-up examination 12 months later showed that the tooth was asymptomatic. The radiological findings presented no signs of periapical pathology.

CLINICAL SIGNIFICANCE

The clinician must be aware of the occurence and complexity of C-shaped canals in mandibular first molar teeth to perform a successful root canal treatment. The supplementary use of SAF after application of rotary instruments in C-shaped root canals might be a promising approach in endodontic treatment of this type of canal morphology.

An in vitro assessment of type, position and incidence of isthmus in human permanent molars

Root canal anatomical complexities, such as isthmus, may limit the action of the endodontic instruments, irrigant solutions and intracanal medications, leading to endodontic treatment failure.

Aetiology, incidence and morphology of the C-shaped root canal system and its impact on clinical endodontics

The C-shaped root canal constitutes an unusual root morphology that can be found primarily in mandibular second permanent molars. Due to the complexity of their structure, C-shaped root canal systems may complicate endodontic interventions. A thorough understanding of root canal morphology is therefore imperative for proper diagnosis and successful treatment. This review aims to summarize current knowledge regarding C-shaped roots and root canals, from basic morphology to advanced endodontic procedures. To this end, a systematic search was conducted using the MEDLINE, BIOSIS, Cochrane Library, EMBASE, Google Scholar, Web of Science, PLoS and BioMed Central databases, and many rarely cited articles were included. Furthermore, four interactive 3D models of extracted teeth are introduced that will allow for a better understanding of the complex C-shaped root canal morphology. In addition, the present publication includes an embedded best-practice video showing an exemplary root canal procedure on a tooth with a pronounced C-shaped root canal. The survey of this unusual structure concludes with a number of suggestions concerning future research efforts.

C-shaped root canal configuration: A review of literature

The aim is to review and discuss the etiology, incidence, anatomic features, classification, diagnosis and management of the C-shaped canal configuration. C-shaped canal configuration is a variation that has a racial predilection and is commonly seen in mandibular second molars. The intricacies present in this variation of canal morphology can pose a challenge to the clinician during negotiation, debridement and obturation. Manual and electronic searches of literature were performed from 1979 to 2012, in Pub Med by crossing the keywords: C-shaped canals, mandibular second molar, mandibular first premolar, root canal morphology. Knowledge of the C-shaped canal configuration is essential to achieve success in endodontic therapy. Radiographic and clinical diagnoses can aid in identification and negotiation of the fan-shaped areas and intricacies of the C-shaped anatomy. Effective management of this anomalous canal configuration can be achieved with rotary and hand instrumentation assisted with sonics and ultrasonics. Modifications in the obturation techniques will ensure a 3-dimensional fill of the canal system and chamber retained restorations like amalgam or composites, serve as satisfactory post endodontic restorations.

In-depth morphological study of mesiobuccal root canal systems in maxillary first molars: review

A common failure in endodontic treatment of the permanent maxillary first molars is likely to be caused by an inability to locate, clean, and obturate the second mesiobuccal (MB) canals. Because of the importance of knowledge on these additional canals, there have been numerous studies which investigated the maxillary first molar MB root canal morphology using in vivo and laboratory methods. In this article, the protocols, advantages and disadvantages of various methodologies for in-depth study of maxillary first molar MB root canal morphology were discussed. Furthermore, newly identified configuration types for the establishment of new classification system were suggested based on two image reformatting techniques of micro-computed tomography, which can be useful as a further 'Gold Standard' method for in-depth morphological study of complex root canal systems.

Incidence of C-shaped root canal systems in mandibular second molars in the native Chinese population by analysis of clinical methods

The aims of the study were to investigate the incidence of C-shaped root canal systems in mandibular second molars in a native Chinese population using radiography and clinical examination under microscope and to compare the relative efficacies of these methods. For the recognition of C-shaped root canal system, 1 146 mandibular second molars were selected and examined. Teeth with C-shaped canal systems were categorized by using the radiographic classification criteria and the modified Melton's method. C-shaped canals were identified in 397 (34.64%) mandibular second molars by radiography (type I, 31.23% type II, 38.29% type III, 30.48%). Clinical examination showed that 449 (39.18%) cases exhibited C-shaped canal systems (C1, 22.94% C2, 48.11% C3a, 15.59% C3b, 13.36%). As for the result of the radiographic and clinical combined examination, C-shaped root canals were found in 473 (41.27%) mandibular second molars (C1, 21.78% C2, 45.67% C3a, 16.70% C3b, 15.86%). The incidence of C-shaped root canal diagnosed by radiographic method was statistically different from that by clinical examination and the combined examination (P<0.05). The study indicated a high incidence of C-shaped canal system in a Chinese population. The combination of microscopic and radiographic examination is an effective method in identifying the C-shaped root canal system.

Root canal configuration and the prevalence of C-shaped canals in mandibular second molars in an Iranian population

A total of 139 extracted mandibular second molars were injected with India ink and demineralized. They were made clear and transparent with methyl salicylate, and the anatomy of their canals was studied. It was found that 86.3% of mandibular second molars had two roots, 9.3% had one root, and 4.3% had three roots. Ninety percent of the mesial roots of the mandibular second molars with two roots had two canals (predominantly with a type II or III configuration), and 77.5% of the distal roots of these teeth had one canal (predominantly with a type I configuration). Among the mandibular second molars, 7.2% had C-shaped canals and these configurations were seen mostly in single-rooted mandibular second molars. The results of this study indicate that mandibular second molar teeth have many variations in the number of roots and the morphology of their canals. Therefore it should not be assumed that all mandibular second molar teeth have two roots and three canals.

Root and canal morphology of permanent mandibular molars in a Sudanese population

AIM

To investigate variations in the root canal systems of first and second permanent mandibular molar teeth in a Sudanese population using a clearing technique.

METHODOLOGY

Two hundred extracted first and second permanent mandibular molars from three cities in the state of Khartoum were studied. Access cavities were prepared and pulp tissue was removed by immersion in 5% sodium hypochlorite under ultrasonication; Indian ink was then injected into the root canal systems assisted by a vacuum applied apically. The teeth were rendered clear by demineralization and immersion in methyl salicylate before evaluation. The following observations were made (i) number of roots and their morphology; (ii) number of root canals per tooth; (iii) number of root canals per root and (iv) root canal configuration.

RESULTS

Overall 59% of mandibular first molars had four canals with 3% having a third distolingual root. Seventy-eight per cent of second mandibular molars had two separate flat roots, whilst 10% were C-shaped. The most common canal system configurations were type IV (73%) and type II (14%). Inter-canal communications were more common in the mesial roots. The prevalence of inter-canal communications was 65% in first molars and 49% in second molars.

CONCLUSIONS

In this sample of Sudanese teeth, 59% of the mandibular first permanent molars had four root canals whilst 10% of the mandibular second molars had C-shaped roots/canals.

The C-shaped root canal configuration: a review

Recognition of unusual variations in the canal configuration is critical because it has been established that the root with a single tapering canal and apical foramen is the exception rather than the rule. The early recognition of these configurations facilitates cleaning, shaping, and obturation of the root canal system. "C" configuration, which is an important anatomic variation, presents a thin fin connecting the root canals. Because of the importance of its true diagnosis and treatment, a comprehensive review of published information and investigations about it in addition to approaches for its treatment is necessary.