Anatomical and histological features of C-shaped canals in mandibular second molars

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.

Uncovering the Enigma of the C-shaped Root Canal Morphology

A C-shaped canal describes an anatomical configuration of a tooth's root canal that resembles the alphabet C when viewed occlusally in a prepared access cavity. In the second molar of the maxillary arch, the root canals unite into a single, continuous, extensive root canal morphology to form a C-shaped canal. The natural crevices found in tooth roots where blood vessels and nerves are housed are called root canals. The frequently referred etiology resulting in the development of the C-shaped canal arrangement is the inability of Hertwig's epithelial root sheath to undergo fusion. The occurrence of the C-shaped canal anatomic variation varies among populations, with the majority of cases occurring in mandibular second molars. C-shaped canals pose several challenges in endodontic treatment such as in their diagnosis, biomechanical preparation, debridement, and obturation. Nevertheless, the desired result can be achieved with relative ease if one has a solid grasp of the different root canal configurations and uses the relevant clinical expertise. Therefore, three-dimensional radiography is utilized to help identify and negotiate C-shaped canals by enabling three-dimensional reconstruction of the root canal system. Efficient C-shaped canal configuration treatment may be attained using hand-driven and rotary instruments assisted by sonic or ultrasonic hand-pieces. Four alternative gutta-percha filling methods are used in C-shaped canals: core-carrier, ultrasonic compaction, cold lateral compaction, and single cone with injectable gutta-percha. The core-carrier technique is the most efficient obturation technique in the C-shaped canal. Calcium silicate materials (CSMs) are also used for the obturation of C-shaped canals. The most frequently used CSMs are mineral trioxide aggregate and biodentine.

The Assessment of C-shaped Canal Prevalence in Mandibular Second Molars Using Endodontic Microscopy and Cone Beam Computed Tomography: An In Vivo Investigation

Background Understanding root canal anatomy variations, particularly C-shaped canals, is crucial for successful endodontic treatment. This study used clinical and radiographic methods to assess the prevalence and characteristics of C-shaped canals in mandibular second molars in Western Maharashtra. Materials and methods This prospective study was conducted in the western region of Maharashtra, India. The samples included patients requiring endodontic treatment for mandibular second molars. Clinical evaluation was conducted using a surgical endodontic microscope and cone beam computed tomography (CBCT) imaging. Inclusion and exclusion criteria ensured the selection of a focused and homogeneous sample. Data analysis included assessment of unilateral/bilateral occurrence, canal distribution, and cross-sectional characteristics. Results Out of 200 mandibular second molars, 7.5% exhibited C-shaped root canals, with no significant gender differences. Canal distribution varied across coronal, middle, and apical levels, with prevalent configurations being C1, C2, C3, and C4. No significant differences were observed in canal distribution based on root levels. No significant gender differences were found in the presence of grooves on the root surfaces. Conclusion This study provides valuable insights into the prevalence and characteristics of C-shaped canals in mandibular second molars in Western Maharashtra. Further research into histological and genetic aspects can enhance our understanding, leading to improved treatment strategies for complex root canal anatomy variations.

Factors Influencing Non-Surgical Root Canal Treatment Outcomes in Mandibular Second Molars: A Retrospective Cone-Beam Computed Tomography Analysis

Background/Objectives: This study aimed to investigate the influence of the root canal morphology and various treatment variables on the outcomes of root canal treatments (RCTs) in mandibular second molars, assessed through cone-beam computed tomography (CBCT) imaging. Methods: A total of 150 CBCT images were examined, comprising 100 cases of persistent endodontic infections and 50 of previously treated root canals with normal apices in the mandibular second molars. CBCT was utilized to evaluate the root canal configuration, the radiographic quality of coronal restorations and treated canal systems, and the presence of periapical lesions. Statistical analyses were performed to explore the correlations between these factors. Results: The presence of a C-shaped root canal configuration did not demonstrate a significant correlation with periapical lesions (p = 0.05). Factors influencing endodontic treatment outcomes included missing canals (p = 0.018), underfilling or overfilling (p = 0.045), and inadequate coronal restoration (p = 0.006). Missing a canal was identified as the variable most significantly associated with periapical lesions (OR = 3.103). Inhomogeneous root canal obturation was more commonly observed in C-shaped root canals (p < 0.001). Conclusions: Regardless of the root canal morphology of mandibular second molars, successful RCT depends on thorough disinfection to eliminate any untreated canals, precise three-dimensional filling of the canals at the correct working length, and a securely sealed coronal restoration to prevent leakage.

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.

A New Methodology to Determine the Orifice for Root Canal Configurations in First Permanent Molar Root and Canal Morphologies Using Micro-Computed Tomography

BACKGROUND

The distinction between where the pulp chamber ends and the root canal system begins is poorly defined within the existing literature.

METHODS

This paper aimed to describe a range of accurate methods to define the transition from pulp chamber to root canal in different first molar root morphologies using micro-focus computed tomography (micro-CT).

METHODS

The sample consisted of 86 mandibular and 101 maxillary first molars from the skeletal collections housed in the Department of Anatomy and Histology of the Sefako Makgatho Health Sciences University and the Pretoria Bone Collection. A stepwise approach using the cemento-enamel junction (CEJ) and dedicated landmarks was followed to create an automated cross-sectional slice.

RESULTS

Transition from pulp chamber to root canal could be accurately determined on maxillary and mandibular teeth. The occurrence of two separate roots in mandibular molars was 97.7%, with the remaining 2.3% having an additional disto-lingual root, with no mandibular molars displaying fused roots. In the maxillary molars, 92.1% had three separate roots and 7.9% displayed root fusion. Within this group, one tooth displayed a C-shaped root canal configuration and one a mesotaurodont-type morphology.

CONCLUSION

The suggested methodology to determine orifice location was found to be appropriate in all morphological types.

Association of root morphology of mandibular second molars on panoramic-like and axial views of cone-beam computed tomography

BACKGROUND

Knowledge about the anatomy and morphology of the root canal system is essential for successful surgical and non-surgical root canal treatments. However, precise assessment of the root morphology and anatomy is not often possible on two-dimensional radiographs. This study aimed to investigate the association of root morphology of mandibular second molars on panoramic-like and axial views of cone-beam computed tomography (CBCT).

METHODS

This cross-sectional study evaluated 1,231 CBCT scans of mandibular second molars obtained between October 2018 and February 2022 that were retrieved from the archives of a private radiology clinic. Panoramic-like images were reconstructed from the CBCT scans. The root morphology of mandibular second molars was classified on panoramic-like images as type 1, 2, 3, 4, or 5. The root pattern on axial CBCT images was classified into three types of single, double and C-shaped. The association of root morphology on panoramic-like and axial CBCT views was analyzed by the Chi-square test and Fisher's exact test at 0.05 level of significance.

RESULTS

Of all, 62.7% of mandibular second molars were type 1; out of which, 97.3% had a double-root pattern on axial CBCT images. Also, 28.6% of them were type 2; of which, 92.6% had a double-root pattern. Moreover, 3.9% were type 3; of which, 47.9% had a C-shaped pattern; 0.9% were type 4, and 45.5% of them showed a single-root pattern; 3.8% were type 5 with 76.6% of them showing a single-root pattern. The prevalence of C-shaped canals was higher in females, and most C-shaped canals had a C3 pattern.

CONCLUSION

Root morphology on panoramic-like CBCT views had a strong association with the root canal pattern on axial CBCT views. According to the results, mandibular second molars with a type 3 morphology on panoramic-like CBCT images are highly probable to have a C-shaped canal.

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.

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.

Root and root canal morphology of mandibular second permanent molars in the Gansu province population: A CBCT study

To study the anatomical characteristics of the root and root canal system of the mandibular second molars in the population of Gansu province, and to provide theoretical and clinical references for improving the success rate of root canal therapy (RCT) of mandibular second molars. The number of roots and root canals, root canal type and pulp chamber height of mandibular second molars were determined by observing cone-beam computed tomography (CBCT) images of people living in Gansu. The most common type of mandibular second molars in the Gansu province population was a double root with three root canals (47.55%), followed by a C-shaped root (35.56%). There were more females than males with a C-shaped root (p < 0.05). The most common root canal subtype of the C-type root was C3 (13.91%). Most of the population (77.11%) had bilateral mandibular second molars with symmetrical root canal morphology. With an increase in age, the height of the pulp chamber decreased significantly. The incidence of root canal variation of the mandibular second molars is relatively high in the population of Gansu province. Preoperative examination with CBCT is essential for mandibular second molars that need RCT to avoid root canal treatment failure and decrease the occurrence of postoperative pain as much as possible.

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.

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.

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.

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.

Detection of the internal anatomy of lower anterior teeth using cone-beam computed tomography

Morphology study of root canal systems is essential for a correct diagnosis, therapy and prognosis of root canal treatment. This study aimed to analyse the dental anatomy of the lower anterior teeth, using cone-beam computed tomography (CBCT). Lower anterior teeth were classified in terms of type, number and location of root canals, evaluating the bilaterality of anatomical occurrences and determining whether the gender and age influence the findings. We analysed 749 CBCT of patients attending the School of Dentistry for different reasons. Spearman's correlations and Wilcoxon signed-rank test were used to analyse data (α = 0.05). There was no significant correlation between gender (male and female) and anatomy of the canals 33 (P = 0.162), 32 (P = 0.815), 31 (P = 0.708), 41 (P = 0.422), 42 (P = 0.382) and 43 (P = 0.063). There was a significant correlation between age and anatomy of the canals 33 (P = 0.045), 32 (P = 0.033), 31 (P = 0.022), 41 (P = 0.000), 42 (P = 0.037) and 43 (P = 0.037). There was no significant correlation between gender and patients' age (P = 0.325). There was no anatomical difference between the bilateral pairs (right and left homologous teeth) (P > 0.05). The most common anatomical configuration was single-canal teeth (85.29%), followed by the configuration in which one canal leaves the chamber, divides into two and unite again (12.88%). Anatomy of the lateral incisors and lower canines does not change with the gender of patients. However, as age rises, single canals and the incidence of division into two canals ending in a single foramen also increases.

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.

The efficacy of five different techniques in identifying C-shaped canals in mandibular molars

Information regarding the canal anatomy especially in complex cases such as C-shaped canals is essential for a successful treatment. In this study, five different methods for identification of C-shaped canal configuration were compared. 108 extracted mandibular molars with fused roots were studied. Radiographic evaluation was carried out using periapical radiography and CBCT. After access cavity preparation, all specimens were evaluated by direct visual examination and then under dental operating microscope. Finally, the actual anatomy of each sample was determined by preparing horizontal cross sections of the roots (1 mm thick) and examining them under stereomicroscope as the gold standard. Among the techniques used, high-resolution CBCT manifested the highest accuracy, whereas periapical radiography had the lowest. All approaches can be useful in reaching a correct diagnosis. CBCT, especially the low-resolution modality, is an effective technique in the diagnosis of C-shaped anatomy.

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.

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.

Fused roots of maxillary molars: characterization and prevalence in a Latin American sub-population: a cone beam computed tomography study

Objectives

The upper molars generally have three roots; therefore, different combinations of fusion can occur, increasing the possibility of finding more complex root canal systems. The purpose of this study was to evaluate the prevalence and characterization of fused roots in first and second maxillary molars using cone-beam computed tomography (CBCT) in a Colombian population.

Materials and Methods

A total of 1274 teeth were evaluated, of which 534 were maxillary first molars and 740 were maxillary second molars. Axial sections were made at the cervical, middle, and apical levels to determine the prevalence of root fusion and the types of fusion.

Results

Overall, 43% of the molars (n = 551) presented some type of fused root. Root fusion was present in 23.4% of the maxillary first molars. The most frequent type of fused root was type 3 (distobuccal-palatal; DB-P) (58.9%). Root fusion was observed in 57.6% of the maxillary second molars, and the most prevalent type of fused root was type 6 (cone-shaped) (45.2%). Of the maxillary molars, 12.5% were classified as C-shaped.

Conclusion

Within the limitations of this study, there was a high prevalence of fused roots in maxillary molars in the Colombian population, mainly in the maxillary second molars. In first molars, the most common type of fused root was type 3 (DB-P) and in second molars, the most common type was type 6 (cone-shaped). Additionally, molars with root fusion presented variation at different levels of the radicular portion, with implications for treatment quality.

Analysis of Cause of Endodontic Failure of C-Shaped Root Canals

The purpose of this study was to analyze various characteristics and classification of C-shaped root canals and evaluate the causes of endodontic failure of C-shaped root canals by examining the resected root surface with an endodontic microscope and a scanning electron microscope (SEM). Forty-two teeth with C-shaped root canals were included in this study and had undergone intentional replantation surgery. Before surgery, periapical radiography and cone-beam computed tomography were taken. The root canal configuration was analyzed and classified according to Melton's classification at coronal and apical level. After injection of 1 : 100,000 epinephrine with 2% lidocaine, the tooth was carefully extracted. After the root-end resection, the resected root surface was examined using an operating microscope and SEM. Mandibular second molars were most frequently involved teeth (90.4%). The most frequently observed root canal configurations were C1 at the coronal level (45.2%) and C3 at the apical 3 mm level (45.2%). The most common cause of failure for a C-shaped root canal treatment was a leaky canal (45.2%), followed by an isthmus (23.8%), missing canal, overfilling, and iatrogenic problems. In conclusion, C-shaped root canals were most frequently found in mandibular second molars. The most common cause of failure was a leaky canal and isthmus.

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.

Prevalence of C-shaped canal system in mandibular first and second molars in a Saudi population assessed via cone beam computed tomography: a retrospective study

OBJECTIVES

The purpose of this study was to determine the prevalence of the C-shaped root canal configuration, location of the longitudinal groove, sex differences, and unilateral/bilateral presence in mandibular first and second molars in a Saudi population using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

CBCT images for the mandibular first and second molars of 487 patients (a total of 529 first molars and 681 s molars) were evaluated. The teeth were assessed for the presence of C-shaped root canals according to Fan criteria. Subdivisions were also made according to sex, direction of the longitudinal groove, and unilateral/bilateral presence.

RESULTS

Only one C-shaped mandibular first molar was observed (0.19%), whereas 62 second molars (9.1%) exhibited C-shaped anatomy. Unilateral presence of the C-shaped root canal system was more common (53.85%). Female patients had a higher prevalence than males. Longitudinal grooves were most commonly found on the root lingual surface (58.1%).

CONCLUSIONS

The prevalence of the C-shaped canal configuration in a Saudi Arabian population was 0.19% in the mandibular first molar and 9.1% in the mandibular second molar. Longitudinal groove prevalence was highest on the lingual surface. Women had a significantly higher prevalence of the C-shaped canal configuration than men. Patients with unilateral presence of the C-shaped canal configuration were more common than those with bilateral presence.

CLINICAL RELEVANCE

Tooth type, patient sex, and ethnicity can help clinicians predict the prevalence of the C-shaped canal system in mandibular 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.

Evaluation of Different Techniques for Filling Simulated C-shaped Canals of 3-dimensional Printed Resin Teeth

INTRODUCTION

The purpose of this study was to compare the ability of different root canal filling methods on the C1 root canal anatomy using 3-dimensional (3D) printer technology.

METHODS

Mandibular molars were scanned with cone-beam computed tomographic (CBCT) imaging. A mandibular molar tooth with a C1 root canal configuration was selected according to images obtained from CBCT technology. The root canals were shaped with ProTaper Universal rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland) and hand files. After the root canal shaping procedure, the tooth was scanned with micro-computed tomographic imaging, and 80 replicas of the tooth were produced with a 3D printer. Replicas were assigned into 4 groups (n = 20) and were filled using one of the following techniques: a core carrier system (GuttaCore [GC]; Dentsply Tulsa Dental Specialties, Tulsa, OK), a continuous wave obturation system (Elements Free [CW]; Kerr/SybronEndo, Orange, CA), a cold lateral compaction technique (CLC), or the injectable cold filling method (GuttaFlow Bioseal [GFB]; Coltène/Whaledent AG, Altstatten, Switzerland). All specimens were sectioned horizontally at 2, 4, 6, 8, and 10 mm from the apices of the specimens. The sections were examined at 32× magnification under a stereomicroscope, and the percentage areas of gutta-percha, sealer, and voids were measured. Statistical analysis of data was performed using multivariate analysis of variance and Tukey honestly significant difference tests (P < .05).

RESULTS

The CW group had the highest mean percentages for void and the least mean percentages for gutta-percha at 2-mm sections (P < .05). A pairwise comparison between the groups showed significantly less void in the CLC and GFB groups and more void in the CW and GC groups at 2 mm (P < .05). In the total area, the CLC and GFB groups showed a significantly lower percentage of gutta-percha and more sealer compared with the other groups (P < .05), and there was no significant difference between the CLC and GFB groups (P > .05).

CONCLUSIONS

At the apical part of the canal, the cold lateral compaction and cold injectable filling techniques were more successful compared with the warm gutta-percha filling techniques in C1 root canal configuration.

Retrospective Assessment of Healing Outcome of Endodontic Treatment for Mandibular Molars with C-shaped Root Canal

INTRODUCTION

A thorough knowledge of the anatomic morphology of the root canal system is necessary for the long-term success of the root canal therapy. The occurrence of C-shaped root canal configuration is one such variation. Achievement of favorable prognosis after commencing root canal therapy in such teeth is one of the challenges imposed on the endodontist. Hence, we evaluated the healing occurring after endodontic therapy in patients with C-shaped root canals in mandibular molars.

MATERIALS AND METHODS

The present study was conducted in the Department of Conservative Dentistry of the institution and included assessment of all the patients who underwent root canal treatment of the mandibular first and second molars. Endodontic therapy was performed in all the cases by experienced endodontist. Final postoperative radiographs were taken. Recording of the data of the personal and clinical details of a total of 250 patients was done. All the clinical and radiographic details of the patients, such as tooth location in the jaw, presence or absence of C-shaped canals, status of the pulp tissue, presence or absence of the fractures, and other details of the patients were recorded. Radiographic and clinical examination of the tooth of the patients was done during the baseline visit and further during the follow-up visits. The presence of C-shaped root canals was confirmed using the radiographs. Periapical index (PI) scoring system was used. Categories defined for enlisting the healing after the root canal treatment with the assessment of the PI score. All the results were analyzed by Statistical Package for the Social Sciences software.

RESULTS

Vital pulp tissue was encountered in majority of the cases. C-shaped root canal configuration was observed in 40% of the cases included in the present study. After completion of the endodontic therapy, complete crown placement was done in only 22% of the cases. In cases of vital teeth with C-shaped root canals configuration, most of the teeth showed complete healing. Significant results were obtained while comparing the complete coverage crown parameter in relation to the healing process in teeth with C-shaped root canals.

CONCLUSION

In the present study, no significant effect of the C-shaped root canal configuration was found on the healing rate of the endodontic therapy in mandibular molars.

CLINICAL SIGNIFICANCE

Meticulous endodontic therapy with special techniques should be done while preparing teeth with C-shaped root canals.

Effect of Deep Cryogenic Treatment on Cyclic Fatigue of Endodontic Rotary Nickel Titanium Instruments

Introduction:

Cyclic fatigue is the common reason for breakage of rotary instruments. This study was conducted to evaluate the effect of cryogenic treatment (CT) in improving the resistance to cyclic fatigue of endodontic rotary instruments.

Methods and Materials:

In this in vitro study, 20 RaCe and 20 Mtwo files were randomly divided into two groups of negative control and CT. CT files were stored in liquid nitrogen at -196^°C for 24 h, and then were gradually warmed to the room temperature. All files were used (at torques and speeds recommended by their manufacturers) in a simulated canal with a 45^° curvature until breakage. The time to fail (TF) was recorded and used to calculate the number of cycle to fail (NCF). Groups were compared using independent-samples t-test.

Results:

Mean NCFs were 1248.2±68.1, 1281.6±78.6, 4126.0±179.2, and 4175.4±190.1 cycles, for the Mtwo-control, Mtwo-CT, RaCe-control, and RaCe-CT, respectively. The difference between the controls and their respective CT groups were not significant (P>0.3). The difference between the systems was significant.

Conclusion:

Deep CT did not improve resistance to cyclic fatigue of the evaluated rotary files.

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.

C-shaped canals-prevalence and root canal configuration by cone beam computed tomography evaluation in first and second mandibular molars-a cross-sectional study

OBJECTIVES

C-shaped root canal configuration is an unusual root canal morphology and one of the most often anatomical variations in root canal systems of second mandibular molars. The purpose of this study was to assess the prevalence, symmetry and configuration of C-shaped canals in first and second mandibular molars in an Israeli population using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

One thousand twenty Israel patients' CBCT scans were screened and evaluated. First and second mandibular molars with C-shaped canals were identified. Prevalence configuration along the root and symmetry were analyzed, and new radicular groove classification was proposed.

RESULTS

Total of 1465 mandibular second molars and 1229 mandibular first molars were evaluated. The overall prevalence of C-shaped canals in first and second mandibular molars was 0.16 and 4.6%, respectively. No significant difference was found by gender or side of occurrence. The unilateral prevalence of C-shaped canals in mandibular second molars was 55%. C-shaped canal configuration changed along the root in 63% of the cases.

CONCLUSIONS

The prevalence of C-shaped canals in first and second mandibular molars in the Israeli population is low in comparison to other subpopulations. Clinicians should be aware of the possible asymmetry, different configuration along the root, and the location of danger zone of this anatomic variation during clinical work.

CLINICAL RELEVANCE

CBCT is an efficient three dimensional radiographic examination for evaluation of C-shape root canal configuration. CBCT may help the clinicians during clinical work for considering appropriate cleaning, shaping, and obturation technique according to the characteristic of C-shape root canal configuration.

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 Characteristics of the Maxillary C-shaped Molar

INTRODUCTION

The anatomy of the maxillary C-shaped molar has been the subject of several case reports although no true prevalence research has ever been conducted. The aim of this observational study was to evaluate and characterize the incidence of these morphologies using cone-beam computed tomographic (CBCT) technology.

METHODS

Patients having presurgical CBCT examination were selected. CBCT analysis was performed at 5 different axial levels, and the teeth were classified as maxillary molar C shapes according to the inclusion criteria for the present investigation. The prevalence of C-shaped anatomy was calculated. The z test for proportions in independent groups was used to analyze the differences between proportions. Intrarater reliability was also tested.

RESULTS

A total of 2227 teeth (928 upper first molars and 1299 upper second molars) from 895 patients were included in this research. Five different types of C-shaped molars were found, which included fusion between mesiobuccal and palatal roots (type A), mesiobuccal and distobuccal roots (type B), distobuccal and palatal roots (type C), 2 possible palatal roots (type D), and mesiobuccal and palatal roots connecting with an independent distobuccal root canal at apical or between distobuccal and palatal roots connecting with an independent mesiobuccal root canal at apical (type E). The global prevalence was 1.1% for first molars and 3.8% for second molars. Differences were observed between sex, teeth, and some types of C shapes at P < .05.

CONCLUSIONS

Maxillary C-shaped molars have low prevalence but high anatomic complexity. An understanding of their anatomic configuration and variations is important in ensuring that they are treated properly. Distinct differences exist between C-shaped configurations of upper and lower molars.