Root canal anatomy of the human permanent teeth

A micro-computed tomographic evaluation of maxillary first molar root canal morphology in Black South Africans

PURPOSE

This study was conducted to investigate the root canal anatomy of maxillary first molars in Black South Africans.

METHODS

Micro-computed tomography was used to investigate 101 maxillary first molars (53 teeth from the right, 48 from the left; 50 male and 51 female teeth). The number of root canals in each tooth was determined, and the relationship between side, sex and age was analyzed using chi-squared test. To determine intra- and inter-observer reliability, Cohen's kappa coefficients were calculated.

RESULTS

Intra- and inter-rater agreements of 96.92% and 98.08% were achieved, respectively. Most teeth contained either three or four canals, but a second, third and fourth mesio-buccal canal was found in 60.39%, 5.94% and 0.99% of teeth, respectively. The disto-buccal and palatal roots contained predominantly single canals, but additional canals were noted in 2.97% and 1.98% of teeth. Four canals were common in females and teeth on the right side often contained a second mesio-buccal canal. However, the prevalence of a third mesio-buccal canal was higher in males than in females.

CONCLUSION

The teeth studied showed diversity and variations between sexes and arch sides. These findings will aid clinicians in endodontic treatment and will be applicable for educational purposes.

Systematic review and meta-analysis of root morphology and canal configuration of permanent premolars using cone-beam computed tomography

INTRODUCTION

The efficacy of root canal treatment is greatly impacted by a thorough understanding of root canal anatomy. This systematic review and meta-analysis aim to thoroughly investigate the root morphology and canal configuration (RMCC) of permanent premolars (PMs).

METHODOLOGY

A comprehensive analysis was conducted following the PRISMA guidelines. Literature exploration was carried out across four electronic databases (PubMed, Embase, Cochrane, and Web of Science). The risk of bias assessment was conducted for the included studies utilizing the Anatomical Quality Assessment (AQUA) tool. Data analysis was performed utilizing SPSS and RevMAN5.3.3. The meta-analysis was applied with a 95% confidence interval to calculate odds ratios (OR).

RESULTS

Among the 82 selected studies, 59 studies exhibited potential bias in domain one (objective(s) and subject characteristics), followed by domain three (methodology characterization). The majority of maxillary PM1s had either single root (46.7%) or double roots (51.9%), while three-rooted variants were uncommon (1.4%). Conversely, most other PMs exhibited a single root. In terms of canal configuration, maxillary PM1s predominantly featured double distinct canals (87.2%), with the majority of maxillary PM2s displaying either a single canal (51.4%) or double canals (48.3%). Mandibular PMs were primarily characterized by single canals, accounting for 78.3% of mandibular PM1s and 90.3% of mandibular PM2s. Subgroup analyses revealed higher incidences of single-rooted and single-canalled PMs among Asians compared to Caucasians. Additionally, women exhibited a higher incidence of single-rooted PMs, while men showed a greater frequency of double-rooted PMs.

CONCLUSIONS

The comprehensive analysis indicated that maxillary PM1s predominantly possess double roots and double canals, whereas maxillary PM2s and mandibular PMs were primarily characterized by single-rooted with a single canal. Notably, single root and single canal were more prevalent among women and Asian samples.

The effect of root canal preparation tapers on planktonic bacteria and biofilm reduction in the apical third: A correlative microtomography and microbiological laboratory study

AIM

To evaluate the influence of different preparation tapers on the reduction in planktonic bacteria and biofilms of Enterococcus faecalis and Candida albicans in the apical third (4 mm) of the mesial roots of mandibular molars, correlating decontamination with canal shape.

METHODOLOGY

After microtomography analysis for morphological standardization of the canals, 48 mandibular molar roots, each containing two canals (96 canals), were contaminated with E. faecalis and C. albicans and divided into four groups (n = 11) for canal instrumentation using ProDesign Logic 2 files with different tapers G (.03): # 25.03; G (.04): # 25.04; G (.05): # 25.05; and G (.06): # 25.06 and irrigation with 2.5% sodium hypochlorite. Four roots were examined under a scanning electron microscope (SEM) to qualitatively assess biofilm formation. Eight roots were used as the negative control group (samples were not contaminated). Bacteriological samples were taken exclusively from the apical third of the roots before and after chemical-mechanical preparation and bacterial counts were determined (CFU/mL). The final micro-CT scan was used to quantify the volume variation and unprepared canal area in the apical third. Statistical analysis was performed using the Kruskal-Wallis, Student-Newman-Keuls and Wilcoxon tests for analysis of microbiological data. anova and the Tukey or Games-Howell test were used for analysis of micro-CT data and Spearman's test for correlations (α = 5%).

RESULTS

All groups showed a significant reduction in bacteria (p < .05), with no statistically significant difference between groups. There was no significant difference in per cent volume increase between groups. The unprepared area (Δ%) was affected by the file used (p = .026) and was significantly lower for G (.06) compared to G (.03). There was no statistically significant correlation among bacterial reduction, volume and unprepared area (p > .05).

CONCLUSION

The different preparation tapers influenced root canal shaping in the apical third but did not improve decontamination in this region.

Is the assessment of the mandibular molar danger zone affected by field of view and voxel size in cone beam computed tomography examinations?

OBJECTIVE

To verify if assessment of the danger zone (DZ) in the mesial root of mandibular molars is affected by field of view (FOV) and voxel sizes in cone beam computed tomography (CBCT) scans.

STUDY DESIGN

Forty mandibular molars were scanned by micro-computed tomography, creating the reference standard. The teeth were then submitted for CBCT scans with FOVs of 10 × 5.5 cm and 5 × 5.5 cm and voxel sizes of 0.4, 0.2, 0.15, and 0.075 mm3. The smallest dentin thickness in the DZ from the mesiobuccal and mesiolingual canals was measured at 2, 4, and 6 mm apical to the root furcation. Descriptive statistics, paired t-tests, and intraclass correlation coefficients were used for statistical analysis with significance established at P < .05.

RESULTS

All CBCT measurements overestimated the DZ dentin thickness (P < .001) compared to the reference standard. The greatest overestimation occurred in the 5 × 5.5 cm FOV with 0.4 mm3 voxels (P = .007). Dentin thickness measured with the 5 × 5.5 cm FOV and 0.075 mm3 voxels was significantly smaller and produced the best ICC value with the reference standard (0.936).

CONCLUSIONS

CBCT overestimates the dentin thickness of the DZ regardless of FOV and voxel sizes. The 5 × 5.5 cm FOV showed the best performance with the 0.075 mm3 voxel size, but it performed poorly with 0.4 mm3 voxels.

Morphology of the Physiological Foramen: II. Maxillary and Mandibular Premolars

INTRODUCTION

Information concerning the anatomy of the physiological foramen is still limited. The aim of this study was to investigate the distance between the physiological and anatomic apex, the shape and diameter of the physiological foramen in maxillary (Mx) and mandibular premolars (Mn).

METHODS

The anatomy of the apex of 229 maxillary (first: MxP1; second: MxP2) and 221 mandibular premolars (first: MnP1; second: MnP2) from a mixed Swiss-German population was investigated by means of microcomputed tomography and 3-dimensional software imaging.

RESULTS

The following results were obtained in the presence of a main physiological foramen. 1. The distance between the physiological and anatomic foramen was 0.29-0.99 mm (MxP1), 0.21-1.03 mm (MxP2), 0.13-0.8 (MnP1), and 0.15-1.41 (MnP2). 2. The mean narrow and wide diameters of the physiological foramen were 0.19-0.33 mm (MxP1), 0.25-0.42 mm (MxP2), 0.28-0.37 (MnP1), and 0.28-0.40 (MnP2). 3. The most common physiological foramen shape was oval (66.7% MxP1, 89.7% MxP2, 91.8% MnP1, 64.4% MnP2).

CONCLUSION

Considering the recommended preparation sizes based on a size corresponding to the friction, that is at the narrowest point in the area of the apical constriction (physiological foramen), and within the limitations of this ex vivo microcomputed tomography study, a final preparation size could be chosen when considering the pertaining morphologic considerations; yet, to a minimum ISO 30 size.

Prevalence and morphology of different root canal systems in mandibular premolars: a cross-sectional observational study

BACKGROUND

This study investigated the prevalence and morphology of C-shaped and non-C-shaped root canal systems in permanent mandibular first (PM1) and second (PM2) premolars using retrospective analysis of cone-beam computed tomography (CBCT) scans, and panoramic radiographs.

METHODS

CBCT scans from 2000 patients were screened for the presence of premolars with C-shaped canals and then assessed at three axial levels to determine the canal classification. The teeth were also assessed for Vertucci configuration, number of roots, and radicular grooves. Pre-existing panoramic radiographs were evaluated to identify features specific to PM1/2 with multiple canals or C-shaped anatomy.

RESULTS

A total of 1576 PM1 and 1424 PM2 from 880 patients were evaluated. The overall prevalence of C-shaped canals was 2.2% (3.3% PM1, 1.0% PM2), with 49 (5.6%) patients presenting with at least one C-shaped mandibular premolar. There were 2.3 ± 0.6 and 2.4 ± 0.5 different classifiable cross-sections per tooth for PM1 and PM2, respectively. The sudden disappearance or bifurcation of a canal on panoramic radiographs was associated with the presence of multiple canals (P < 0.001) or C-shaped anatomy (P = 0.03).

CONCLUSIONS

There was substantial variation in cross-sectional anatomy within and between C-shaped premolars, which will affect endodontic treatment planning. © 2023 Australian Dental Association.

Effect of preset torque setting on torque/force generation, shaping ability and surface changes of nickel titanium rotary instrument in different root canal curvature locations: An ex vivo study

The aim of this study was to evaluate how preset torque settings influence the torque, vertical force, and root canal-centering ability of ProGlider and ProTaper NEXT nickel-titanium rotary instruments in canals with different curvature locations. Based on micro-computed tomography, mesial roots of human mandibular molars (25°-40° curvature) were allocated to the apical curvature (apical 1-5 mm) or the middle curvature (apical 5-9 mm) groups, and mandibular incisors (curvature <5°) to the straight canal group. Each group was subjected to automated instrumentation and torque/force measurement with the preset torque of 1, 2.5, or 5 N•cm. Canal-centering ratios were determined with micro-computed tomography. Instrument fracture occurred only in the 2.5 and 5 N•cm groups in curved canals. The preset torque setting and curvature location did not influence canal shaping ability.

Micro-computed tomographic analysis of the morphology of maxillary lateral incisors

OBJECTIVE

This study aimed to investigate the morphology of maxillary lateral incisors (MxLI) using micro-computed tomography (micro-CT).

MATERIALS AND METHODS

The root canal configurations (RCC) of maxillary lateral incisors (MxLI) of a mixed Swiss-German population were examined using micro-CT, 3D imaging, and a 4-digit system code indicating the main root canal from coronal to apical thirds and the main foramina number.

RESULTS

The most frequently observed RCC of MxLI were 1-1-1/1 (Vertucci I/Ve I, 80.0%), 1-1-2/2 (Ve V, 7.3%), 1-2-1/1 (Ve III, 6.4%), 2-1-1/1 (Ve II, 1.8%), and 1-1-1/2 (1.8%)(n = 110). Three additional RCC were observed less frequently (0.9%). The MxLI showed one physiological foramen in 89.1%, two in 9.1%, and seldom three (1.8%). Most accessory canals were identified in the apical third of a root (20.0%), and no accessory canals in 72.7% of the samples.

CONCLUSIONS

Detailed information on the internal morphology of MxLI of a Swiss-German population is given. The most frequently observed RCC of MxLI is 1-1-1/1 (Ve I). However, accessory canals may occur in all apical thirds, and 20% of all teeth investigated showed a challenging RCC for clinical treatment.

CLINICAL RELEVANCE

This study offers clinicians comprehensive data on MxLI morphology, emphasizing the significance of understanding varied RCC and accessory canal presence for improving root canal treatment outcomes. Over 25% of teeth exhibited complex RCC or accessory canals, influencing decisions during root canal treatment.

A systematic review and meta-analysis of the prevalence and global distribution of middle mesial canals in mandibular molars identified by CBCT

OBJECTIVES

This systematic review and meta-analysis aimed to evaluate the prevalence of middle mesial canal (MMC) in permanent mandibular molars of different populations and regions based on cone-beam computed tomography (CBCT) studies.

MATERIALS AND METHODS

PubMed, Scopus, Embase, Web of Science, and Open-Grey were searched up to October 2023 according to specific keywords. A hand search was conducted on the references of the included studies and articles from three peer-reviewed journals in endodontics. The main variable of interest was the prevalence of MMC. Additional data such as the total number of included cases, age and country of the population, CBCT device information, voxel size, and field of view details were also extracted. Extracted data were analyzed qualitatively with the JBI quality assessment checklist and quantitatively with STATA software.

RESULTS

Of 32,793 studied teeth, the cumulative prevalence of MMC in both mandibular 1st and 2nd molars was 3.11% (95% CI: 2.00-4.44%). The subgroup analysis reveals a prevalence of 4.15% (95% CI: 2.69-5.89%) for mandibular 1st molars and 1.2% (95% CI: 0.2-2.83%) for mandibular 2nd molars. The highest prevalence of MMC in 1st molar was attributed to South Asia (11.24%) and Africa (6.61%).

CONCLUSIONS

The prevalence of MMC varies among regions. Clinicians should be aware of the potential prevalence of MMC, particularly in mandibular first molars, as a missed MMC could result in endodontic failure.

CLINICAL RELEVANCE

The presence of MMCs varies in different geographic regions (0% to 29.7%). Clinicians should always look for MMC when doing an endodontic treatment on mandibular molars, as the presence of this canal is not uncommon. We suggest searching for this canal as if searching for the second mesiobuccal canal of maxillary 1st molars.

Exploring age and gender variations in root canal morphology of maxillary premolars in Saudi sub population: a cross-sectional CBCT study

BACKGROUND

In complex teeth like maxillary premolars, endodontic treatment success depends on a complete comprehension of root canal anatomy. The research on mandibular premolars' root canal anatomy has been extensive and well-documented in existing literature. However, there appears to be a notable gap in available data concerning the root canal anatomy of maxillary premolars. This study aimed to explore the root canal morphology of maxillary premolars using cone-beam computed tomography (CBCT) imaging, considering age and gender variations.

METHODS

From 500 patient CBCT scans, 787 maxillary premolar teeth were evaluated. The sample was divided by gender and age (10-20, 21-30, 31-40, 41-50, 51-60, and 61 years and older). Ahmed et al. classification system was used to record root canal morphology.

RESULTS

The most frequent classifications for right maxillary 1st premolars were 2MPM1 B1 L1 (39.03%) and 1MPM1 (2.81%), while the most frequent classifications for right maxillary 2nd premolars were 2MPM1 B1 L1 (39.08%) and 1MPM1 (17.85%). Most of the premolars typically had two roots (left maxillary first premolars: 81.5%, left maxillary second premolars: 82.7%, right maxillary first premolars: 74.4%, right maxillary second premolars: 75.7%). Left and right maxillary 1st premolars for classes 1MPM1 and 1MPM1-2-1 showed significant gender differences. For classifications 1MPM1 and 1MPM1-2-1, age-related changes were seen in the left and right maxillary first premolars.

CONCLUSION

This study provides novel insights into the root canal anatomy of maxillary premolars within the Saudi population, addressing a notable gap in the literature specific to this demographic. Through CBCT imaging and analysis of large sample sizes, the complex and diverse nature of root canal morphology in these teeth among Saudi individuals is elucidated. The findings underscore the importance of CBCT imaging in precise treatment planning and decision-making tailored to the Saudi population. Consideration of age and gender-related variations further enhances understanding and aids in personalized endodontic interventions within this demographic.

New Frontiers in Endodontics: Tackling the Mesiobuccal 2 (MB2) Canal Challenge in the Maxillary First Molar

Molars have been observed to have a variety of morphological forms. The least understood and most treatable tooth in the posterior region is the upper first molar. The maxillary first molar has a complex anatomy with a wide variation in the number, size, and shape of the root canals. The case documentation highlights the endodontic treatment of the upper first molar with an anomalous position of the mesiobuccal 2 (MB2) canal. Endodontic therapy success is contingent upon the awareness of the dentist about the differences i.e. morphology and outline of the root and its canal.

Flatsonic Ultrasonic Tip Optimizes the Removal of Remaining Filling Material in Flattened Root Canals: A Micro-computed Tomographic Analysis

INTRODUCTION

The aim of this study was to evaluate the effectiveness of the XP-endo Finisher R (XPFR; FKG Dentaire, La Chaux-de-Fonds, Switzerland) or the Flatsonic ultrasonic tip (Helse Ultrasonic, Santa Rosa de Viterbo, SP, Brazil) in removing remaining filling material after the retreatment of flattened root canals using micro-computed tomographic imaging.

METHODS

Twenty-four flattened distal root canals of mandibular molars with a buccolingual diameter 4 or more times larger than the mesiodistal diameter were prepared with Reciproc Blue (RB) R40 (VDW GmbH, Munich, Germany) and filled using the Tagger hybrid technique. All canals were retreated with RB R40, and apical enlargement was performed with RB R50 (VDW GmbH). The specimens were randomly distributed into 2 groups: XPFR or Flatsonic (n = 12). The percentage of remaining filling material after retreatment and centralization ability was evaluated. Data were submitted to Mann-Whitney, Wilcoxon, and unpaired t tests (α = 5%).

RESULTS

Greater capacity to remove remaining filling material in the entire canal and the cervical and middle thirds was observed for the Flatsonic compared with the XPFR (P < .05). However, both supplementary cleaning techniques showed a similar percentage of residual filling material in the apical third (P > .05). No difference was observed in the centralization ability between the techniques (P > .05).

CONCLUSIONS

The Flatsonic promotes greater removal of remaining filling material than the XPFR in the retreatment of flattened root canals. However, both supplementary cleaning approaches were similar in the apical third. The XPFR and Flatsonic were able to maintain root canal centralization.

Endodontic Treatment of a Mandibular Second Molar Featuring Vertucci Type V Configuration in the Distal Root: A Case Report

Successful root canal treatment relies primarily on thorough shaping, cleaning, and filling of the entire root canal system. Neglecting even a single canal can significantly raise the risk of post-treatment apical periodontitis. While the distal root of mandibular second molars typically has one canal, they can also present with anatomical variations, including the presence of a Vertucci Type V configuration. This article discusses a case in which a Vertucci Type V configuration in a mandibular second molar was effectively identified and treated.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Morphometric Analysis of Radix Entomolaris: Implications for Endodontic Access and Treatment

Radix entomolaris (RE) is an anatomical variation that involves the existence of an extra root in lower molars, particularly the first molar. This variant, although less common, has significant clinical implications in endodontic treatment and dental surgeries. Appropriate detection of radix entomolaris is crucial for treatment planning and prognosis. Various diagnostic aids like radiography, cone-beam computed tomography, and intraoperative exploration aid in identifying this anatomical variant.

Micro-CT and histological examination of accessory canals in 34 equine cheek teeth

Accessory canals and apical deltas have been extensively studied in human dentistry. Their clinical role as a difficult to clean reservoir for bacteria during endodontic treatments has been well described. Many papers describe in detail the pulp anatomy of equine dentition but little attention has been given to their apical ramifications. The goal of this paper is to describe the presence and anatomy of these accessory canals and apical deltas in healthy equine cheek teeth and discuss their possible relevance in the light of equine endodontics. To accomplish this, 15 maxillary and 19 mandibular healthy cheek teeth were collected ranging from Triadan 06 s to 11 s with eruption ages from 4 to 9 years. Their root anatomy was documented in detail based on micro computed tomography images. A subset of 3 teeth also underwent histological examination. Accessory canals were found in all but two teeth examined. Up to 44 accessory canals per tooth have been found with locations ranging from the root furcation down to the apex of the root and with highly variable diameters. Apical deltas in different stages of development were found in 84% of the roots. The presence of accessory canals identified on microCT images could be confirmed using histological examination although some of them were obliterated by reparative dentin. Accessory canals can be found in most equine cheek teeth and add complexity to their endodontic anatomy. This could have important implications for their treatment in case of pulp pathology. In humans, failure to remove bacterial biofilm from such canals has been associated with failure of endodontic treatment. Research on diseased equine teeth is required to gain a better understanding of their clinical relevance in horses.

Microcomputed tomography analysis of curved root canal preparation when coronal flaring and glide path files used with heat-treated nickel titanium rotary files

The objective was to evaluate the effect of glide path and coronal flaring on the dentin volume removal and percentage of touched walls in curved canals using two heat-treated rotary files. The mesiobuccal canal of forty-eight, randomly selected, extracted mandibular molars was divided into two groups of 24 each, according to the type of instrument used (RACE EVO and EdgeSequel rotary files). Each group was further divided into three subgroups; Group (A): Control using one file shaped to 04/30, Group (B) with a glide path (EdgeGlidePath (EGP)), and Group (C): with a glide path and coronal flaring (EGP and EdgeTaper Platinum (ETP) SX file respectively). The root canals were then instrumented using the assigned instruments. The assessment was carried out using micro-CT. The comparison of the mean values of the tested groups about dentin volume removal and percentage of untouched walls did not reach statistical significance (p<0.05). Glide path and coronal flaring had an insignificant effect on the dentin volume removal and percentage of untouched walls in curved canals.

Characterization of the root and canal anatomy of maxillary premolar teeth in an Iraqi subpopulation: a cone beam computed tomography study

This study aims to evaluate the number of roots and root canal morphology types of maxillary premolars in relation to a patient's gender and age in an Iraqi population using two classification systems. Cone beam computed tomography (CBCT) scans of 1116 maxillary premolars from 385 patients were evaluated for the number of roots and root canal morphology types according to Vertucci's classification and Ahmed et al. classification systems. Differences in the number of roots and root canal morphology types with regard to tooth type, patients' gender and age groups were evaluated and the degree of bilateral symmetry was determined. Chi-squared test was used for statistical analysis. About 51.1% of the 1st premolars were double rooted. The majority (87.9%) of the 2nd premolars were single rooted. The three-rooted form presented in only 1.2% and 0.7% of the 1st and 2nd premolars, respectively. Vertucci Type IV (Ahmed et al. code 2MaxP B1P1) and Vertucci Type I (Ahmed et al. code 1MaxP1) were the most common canal morphology types in the 1st and 2nd premolars, respectively. Females showed a lower number of roots and a higher prevalence of Vertucci Type I configuration (P < 0.05). Younger age groups showed a higher prevalence of Vertucci Type I configuration (P < 0.05). Bilateral symmetry was seen in more than half of the maxillary premolars. There is a considerable variation in the number of roots and root canal configurations of maxillary premolars in the studied Iraqi population, with a significant difference by gender and age groups. Ahmed et al. classification provided more accurate presentation of the root and canal anatomy in maxillary premolars compared to Vertucci's classification.

Shaping ability of three heat-treated NiTi systems in Vertucci's type III root canals of mandibular incisors: An ex vivo study

Introduction

The anatomical configuration classified as Vertucci's type III is described as the second most prevalent in mandibular incisors.

Methods

Thirty-six Vertucci's type III mandibular incisors were evaluated by micro-computed tomography (micro-CT) and divided into 3 groups (n = 12) according to the root canal preparation protocol (HyFlex CM [HCM], HyFlex EDM [HEDM], and Sequence Rotary File [SRF]). The teeth were scanned before and after performing 0.25 mm and 0.40 mm apical diameter preparations. The canal volume, dentin thickness, percentage of accumulated debris and untouched canal areas, transportation, and centering ability were measured. The data were statistically analyzed by ANOVA, Tukey, Kruskal-Wallis, and Dunn tests (P < 0.05).

Results

The volume increase was more evident in the apical third. After 0.40 mm preparation, the SRF system provided a higher reduction (P < 0.05) in dentin thickness on the buccal surface 1 mm from the apex. There was higher canal transportation in the bucco-lingual direction. The 0.40 mm apical preparation reduced the percentage of untouched canal areas. The apical third had the highest percentage of untouched canal areas. The cervical third had the lowest volume of accumulated debris.

Conclusions

Increasing the apical preparation to a diameter of 0.40 mm with the HCM, HEDM, and SRF systems in Vertucci's type III root canals of mandibular incisors proved to be safe and effective, reducing untouched canal areas.

Clinical relevance

Root flattening can be intense to the point of generating a root canal bifurcation. Despite the decrease in the root canal diameter, a greater enlargement of the apical region is necessary and safe.

Worldwide Anatomic Characteristics of the Mandibular Canine-A Multicenter Cross-Sectional Study with Meta-Analysis

INTRODUCTION

This study aimed to examine the global prevalence of root and root canal morphologies in mandibular canines and analyze potential influences of region, ethnicity, sex, and age on the proportion of a second root and root canal configuration.

METHODS

Observers from 44 countries screened 13,200 canines using cone-beam computed tomographic exams and gathered data on the percentages of 2 root canal morphologies and 2-rooted configurations (primary outcomes), as well as the root canal configurations (secondary outcome). Demographic factors (ethnicity, sex, and age) were collected for each participant. Primary outcomes were represented as odds ratios and untransformed proportions accompanied by 95% confidence interval (CI) forest plots. Meta-analysis compared subgroups and identified sources of heterogeneity. Intra- and inter-rater tests were conducted. Statistical significance was set at 5%.

RESULTS

The worldwide prevalence of a second canal was 7.5% (95% CI, 6.3%-8.7%), ranging from 0.7% in Nigeria to 17.7% in Uruguay. The meta-analysis also revealed significant variations when comparing ethnicity, gender, and age (P < .05). The global prevalence of a second root was 1.9% (95% CI, 1.5%-2.3%), with the highest proportion observed in Spain (6.7%). Caucasian and Indian (south Asian) ethnic groups, females, and older patients exhibited higher proportions of 2 roots (P < .05). Meta-regression excluded side, voxel size, and field of view as sources of heterogeneity (P > .05).

CONCLUSIONS

The prevalence of 2 root canals and 2-rooted configurations in the mandibular canine exhibited variations based on geographic location, ethnicity, sex, and age. The global prevalence of 2 root canals and 2-root configuration was 7.5% and 1.9%, respectively.

Detection, characterisation and management of complex root canal configurations in the mesiobuccal roots of maxillary first molars: A case series

This report presents the detection, characterisation, instrumentation and filling of complex canal configurations in the mesiobuccal (MB) root of maxillary first molars. Three patients were referred for root canal treatment in first maxillary molars. Medical history, age, sex and clinical findings were recorded. Intraoral periapical radiographs and cone beam computed tomography (CBCT) were used for diagnosis and pre-operative assessment. Using Ahmed et al. (2017) classification system, codes 3MaxM MB3-5-4-2 DB1-2-1 P1 (case 1), 3MaxM MB2-5-3-2 DB1 P1 (case 2) and 3MaxM MB1-4-2-1-2 DB1 P1 (case 3) were identified. Using the dental operating microscope, CBCT (if indicated) and troughing up to 3 mm allowed identification of more than three canals in the MB root of maxillary first molars. The coding system proposed by Ahmed et al. (2017) allows the classification of MB roots with highly complex canal configurations.

Expert consensus on difficulty assessment of endodontic therapy

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

Debris and Smear Layer Removal in Curved Root Canals: A Comparative Study of Ultrasonic and Sonic Irrigant Activation Techniques

The aim of this study was to compare the cleaning efficacy of three irrigant activation devices with a control of non-activated syringe and needle irrigation in curved root canals. Sixty human curved roots were endodontically prepared and divided into four groups (n = 15) with similar root curvature distributions. Final irrigation using 4% NaOCl was performed with a syringe and needle (30-G) alone, or with Eddy sonic powered irrigation system (polymeric tip #0.25/0.06), Endosonic ultrasonic activation (polymeric tip #0.25/0.03), or Irrisafe ultrasonic activation (stainless-steel tip, #0.25/0.00). SEM was used to evaluate cleaning efficacy, employing five-score systems for debris and smear layer. While no significant difference in debris removal was observed between Endosonic or Irrisafe activation and non-activated irrigation, Eddy sonic powered irrigation system significantly improved debris removal in the apical third of curved root canals. Smear layer removal was effective in coronal and mid-root sections for all groups but less so in the apical third. Thus, Eddy sonic powered irrigation system demonstrated higher efficacy in removing debris from the apical third of curved root canals compared with non-activated syringe and needle irrigation. However, all three irrigant activation systems exhibited no difference from the non-activated control in smear layer removal.

Prevalence of multiple roots and complex canal morphology in mandibular premolars among a selected Southern Egyptian sub-population: a CBCT-analysis

The mandibular premolars can pose a significant challenge in root canal treatment due to their complex canal system. This study investigated the prevalence of multiple roots and complex canal morphology of mandibular premolars in a selected Egyptian sub-population using cone beam computed tomography (CBCT). 283 CBCT scans (131 males, 152 females, age 18-70) included 1132 mandibular premolars (566 first, and 566 second premolars) were viewed for incidences ofvariation in root numbers and canal configuration according to Vertucci's classification. CBCT images were assessed by two endodontists, data were statistically analyzed using Fisher exact and Chi-square tests. The majority of first premolars (85.7%) exhibited a single root, whereas 14.7% had 2 roots with a significantly higher frequency in males (19.8%) than in females (9.5%) (P < .05). The most prevalent type was type I (57.8%), followed by type V (21.7%), while types II and VII made up only 1%. Types V and III were more prevalent among females, while males had a higher prevalence of types I and IV. In 2.5% of cases, mandibular second premolars were found to have 2 roots, with a higher incidence in males (P < .05). Type I canals were significantly more prevalent (90.8%) than other types, followed by type V (5.3%) (P < .05). A statistically significant gender correlation was found regarding root number and canal configuration. It is not uncommon to find mandibular first premolars with two roots in the southern Egyptian population, particularly in males. These observations may be valuable for dentists who treat Southern Egyptians, in Egypt and other countries.

Principle and antimicrobial efficacy of laser-activated irrigation: A narrative review

In the last two decades, the activation of root canal irrigants with pulsed lasers as an adjunct in root canal treatment has become increasingly popular. This narrative review explains the physical basics and the working mechanism of laser-activated irrigation (LAI), explores the parameters influencing LAI efficacy, considers historical evolutions in the field and summarizes laboratory and clinical evidence with emphasis on the antimicrobial action of LAI. Cavitation is the driving force behind LAI, with growing and imploding vapour bubbles around the laser tip causing various secondary phenomena in the irrigant, leading to intense liquid dynamics throughout the underlying root canal. High-speed imaging research has shown that laser wavelength, pulse energy, pulse length and fibre tip geometry are parameters that influence this cavitation process. Nevertheless, this has not resulted in standardized settings for LAI. Consequently, there is significant variability in studies assessing LAI efficacy, complicating the synthesis of results. Laboratory studies in extracted teeth suggest that, with regard to canal disinfection, LAI is superior to conventional irrigation and there is a trend of higher antimicrobial efficacy of LAI compared to ultrasonic activation. Clinical evidence is limited to trials demonstrating similar postoperative pain levels after LAI versus no activation or ultrasonic activation. Clinical evidence concerning the effect of LAI on healing of apical periodontitis as yet is scarce.

Root canal morphology of anterior permanent teeth in Jordanian population using two classification systems: a cone-beam computed tomography study

BACKGROUND

Adequate knowledge of root canal morphology and its variation is essential for success of root canal treatment and to overcome treatemnt failure. The aim of this study was to investigate the root and canal morphology of mandibular anterior teeth using 2 classification systems.

METHODS

3342 lower anteriors were evaluated from 557 CBCT scans. The images were examined in sagittal, axial and coronal views using a CS 3D imaging software (V3.10.4, Carestream Dental). Demographic data recorded, the number of roots and canal's morphology were described according to Vertucci and Ahmed classifications.

RESULTS

Frequency of Type I configuration was significantly the highest in incisors and canines (76%, N = 2539), followed by Type III (20.6%, N = 687). Type II (1.1%, N = 37), IV (1.1%, N = 37), and V (0.3%, N = 11) were rarely encountered. 0.9% (N = 31) of the teeth could not be classified with the Vertucci System. The frequency of 2 roots (2MA in Ahmed classification) which has no correspondence in the Vertucci classification, was 1.1% (N = 38), it was significantly higher in canines and in females (35 canines and 3 laterals). A moderate correlation in root canal morpology was found between the left and right sides (V > 0.30). 80% (N = 2538) of the teeth did not exhibit any divergence/merging. The bifurcation level occurred mostly in the middle third of the root.

CONCLUSIONS

One fourth of anterior teeth had variation from the simple type I canal configuration and therefore requires attention during treatment. The new classification system offers a more accurate and simplified presentation of canal morphology.

CLINICAL RELEVANCE

The prevalence and mid root bifurcation of second canal in lower anteriors requires attention to ensure adequate quality root canal treatment without compromising the integrity of teeth.

Morphological Variation of Mandibular Molars in Rohilkhand Population: An Original Research

Introduction

In-depth knowledge of common and aberrant pulp morphology is essential for appropriate diagnosis and treatment planning before commencing root canal treatment. The radicular morphology of mandibular molars has been extensively studied. Considerable variation in the number of canals and roots found in these teeth has been reported.

Aim

The purpose of this study is to investigate the root canal morphology of the mandibular molars among the Rohilkhand population using Dentascan.

Materials and Methods

Dentascan images of mandibular molar were taken from 99 extracted teeth that were collected from the Department of Oral Surgery and Maxillofacial Surgery, Institute of Dental Sciences, Bareilly, and private clinics. The examination of root canal systems of the teeth was based on Vertucci's classification.

Results

The mandibular molar (n = 99) were taken. Out of the 99 teeth examined, three canals were seen in 60 (60.6%) teeth, four canals in 39 (39.4%) teeth, 3% had extra distal roots, and 6% with C-shaped canals.

Conclusion

Among mandibular first molars, only 3% had three roots. Mesial roots of the first molar typically present with two canals and two apical foramina with type IV or II canal configuration. Most distal roots of the first molar presented with a type I canal configuration. The remainder were distributed mainly between types II, IV, III, and V. Among 99 mandibular molars, 6% had single C-shaped roots.

Maxillary first molar with two distobuccal root canals and cervical deformity: A case report

The second distobuccal canal in the maxillary first molar is often missed because of the low prevalence rate (0%-4%). The article reports this kind of variation in one case. Promising outcomes have continued up to the present (2-year follow-up).

The Correlation between Intraorifice Distance and the Anatomical Characteristics of the Second Mesiobuccal Canal of Maxillary Molars: A CBCT Study

Introduction

Missing anatomy is one of the main causes of endodontic failures, and accurate knowledge of teeth anatomy is a prerequisite for adequate root canal treatment. The aim of the present cone beam computed tomography (CBCT) study was to describe the anatomical characteristics of the mesiobuccal (MB) root canals of maxillary molars and to understand if a correlation exists between the position of the canal orifices and the anatomical features of the root.

Methods

For the purposes of the study, a total of 100 CBCT scans of maxillary molars with two MB canals were selected and studied. The features of root canal anatomy of the MB root of the same teeth were analyzed and recorded (root length, confluence, and Vertucci classification). The distance between MB1 and MB2 orifices and the palatal orifice were recorded, as well as the distance between the orifices and the line joining the palatal orifice and the others. A statistical analysis was performed by providing descriptive measures, the measure of the correlation between different parameters, and the influence of some of these measures on the presence of a confluence between MB1 and MB2.

Results

It resulted that the most frequent configuration is type II Vertucci. The length measured on the sagittal plane was significantly correlated to the presence of a confluence in the MB root. When the root length was higher than 14.56 mm, the confluence is three times more frequent than when the length is lower (OR = 3.635). The area under the curve (AUC) of the receiver operator characteristic (ROC) curve for length on the sagittal plane was 0.632 (P=0.036).

Conclusions

The presence of a confluence between the MB canals of maxillary molars is correlated to the length of the root that could be measured on the sagittal plane and to the distance between the canal orifices. The relative position of the root canal orifices in relation to anatomic landmarks needs to be further explored.

Can the addition of surfactants to NaOCl irrigation impact on the percentage of voids of root canal filling?

This study evaluated the impact of canal irrigation using surfactants associated to NaOCl on the percentage of voids of root canal filling through micro-computed tomographic (micro-CT) analysis. 27 mandibular mesial roots with Vertucci type II canal configuration with isthmus were selected and scanned in a micro-CT device. The specimens were assigned to three groups (n = 9), according to the irrigation solution during instrumentation: 2.5% NaOCl without additives (control), 2.5% NaOCl with 0.1% Benzalkonium Chloride and 2.5% NaOCl with 0.1% Tween 80. After obturation, the specimens were rescanned, and the percentage of voids were calculated. Data were analysed using one-way ANOVA with a significance level of 5%. The percentage of voids were similar among the groups (p > 0.05). None of the specimens showed completely voids-free areas. The addition of surfactants to NaOCl irrigation did not improve the quality of root canal filling of mandibular mesial root canals.

Microcomputed tomography (micro-CT) analysis of apical mandibular premolar in relation to clinical sign presentation: An in vitro study

Introduction

Variations in anatomic apex and apical foramina of root canals are common in different teeth types. The sophisticated 3D micro-CT aids researchers in investigating the apical morphology, such as the apical foramen (AF) and constriction (AC).

Objectives

To measure the length between the foramen and the apex and the physiological length to the apex, in lower premolar teeth. Furthermore, a measurement was conducted on the average length from the foramen to the apex of the lower premolar teeth with respect to the presence of clinical and non-clinical signs.

Methods

A total of 80 lower premolar teeth were selected based on the inclusion criteria. All samples were scanned using micro-CT ZEISS X-Radia (17 µm), and the datasets were analysed. The root canal AF and AC were reconstructed using Drishti software (V3.0) by utilising a 4-digit system code in millimetres (mm).

Results

More than half of the lower premolars (n = 47, 58.8 %) demonstrated a clinical signs presentation, while the rest had a non-clinical sign (n = 33, 41.3 %). There was a significant difference (p = 0.013) between the non-clinical and clinical groups in the mean length from the apical foramen to the apex (AFA) at 0.59 mm and 0.47 mm, respectively. Meanwhile, the non-clinical and clinical mean length from apical constriction to apex (ACA) were 0.75 mm and 0.73 mm, and the mean length from AF to AC (AFC) was 0.48 mm and 0.53 mm, respectively. Nonetheless, no significant differences were detected between the ACA and AFC of non-clinical and clinical groups.

Conclusion

The clinical signs presentation observed in lower premolars mainly affected the apical morphology, particularly the position and length of the root AF, and less so the AC position and length. Therefore, the information is useful for clinical purposes.

A Computed Tomographic Study of the Premolar Teeth of Babyrousa spp

A photographic and computed tomography (CT) scanning study was carried out on the premolar teeth of 18 adult male Babyrousa babyrussa skulls, 10 skulls of Babyrousa celebensis, including 6 adult males, 1 adult female, 1 subadult male, 1 subadult female, and 1 juvenile male. The occlusal morphology of the permanent maxillary premolar teeth of B. babyrussa was very similar to that of B. celebensis. Almost all the maxillary third premolar teeth (107/207) had 2 roots, whereas maxillary fourth premolar teeth (108/208) had 3 or 4 roots. All of the mesial tooth roots of 107/207 and 108/208 were tapering rod-like structures; each contained a single pulp canal. Almost all distal roots of 107/207 were "C" shaped and contained 2 pulp canals. The 108/208 palatal roots were "C" shaped and contained 2 pulp canals. The mesial and distal roots of the mandibular third premolar teeth (307/407) teeth were uniformly rod-like, as were the mesial roots of the mandibular fourth premolar teeth (308/408) teeth. The distal roots of the 308/408 teeth were "C" shaped. All B. babyrussa 307/407 teeth have a single pulp canal located in each of the mesial and distal roots. The 308/408 mesial tooth root contained 1 pulp canal. In all but 3 of the 36 distal 308/408 roots of B. babyrussa teeth and in 7 of the 14 distal roots of B. celebensis teeth there was a single pulp canal; in the other 7 teeth there were 2 pulp canals. Each of the 3 medial roots contained 1 pulp canal.

Locating and Treating Three Calcified Canals in a Mandibular First Molar With Radix Entomolaris and Five Canals: A Case Report

The success of root canal treatment is highly contingent on the comprehensive shaping, cleaning, and filling of the entire root canal system. Failure to address one or more canals often results in an increased likelihood of post-treatment apical periodontitis. Typically, mandibular first molars feature two roots and three canals, but they may also exhibit anatomical variations, such as a mesial middle canal or radix entomolaris (RE). This article presents a case where three calcified canals in a mandibular first molar with RE and five canals were successfully located and treated.

Morphometric micro-CT study of contralateral mandibular incisors

OBJECTIVES

This study aimed to determine the degree of similarity and symmetry in the anatomy of contralateral mandibular incisors. Three-dimensional (3D) models of extracted teeth were obtained from microtomography (micro-CT) scans. Qualitative and quantitative assessments of the morphology and comparison of contralateral pairs were made. The null hypothesis was that contralateral mandibular incisors could not be considered identical in simple morphometric measurements.

METHODS

Sixty pairs of mandibular incisors were extracted from 30 patients and scanned with micro-CT. Virtual models of the cemento-enamel junction to the root apex were rendered. Parameters such as length, canal width, dentinal thicknesses, tortuosity, centerline length, accessory canals, root canal configurations, and root canal orifice cross-sections were used to compare the teeth. Width and thickness comparisons between paired teeth in the same individual were made by paired t-test (Wilcoxon signed-rank test for variables not normally distributed). An online randomization tool generated randomized pairs (independent of the individual/patient). Subsequently, an unpaired t-test (or Mann-Whitney U test for non-normally distributed parameters) and a correlation analysis were conducted. Canal configurations were classified according to preexisting classification schemes. The number and location of accessory canals and apical foramina were registered and compared.

RESULTS

Utilizing advanced imaging techniques and quantitative analyses, our study establishes that contralateral mandibular incisors exhibit a remarkable degree of symmetry in multiple morphological parameters, including length, canal width, and dentinal thicknesses. The apical third showed a high degree of inter-variability for the contralateral pairs. The rigorous statistical analysis of the normalized parameters by Z-score showed no statistically significant differences between the contralateral mandibular incisors. Comparisons between central and lateral teeth revealed differences in root length but no significant disparity in the distribution of accessory canals. Central teeth, on average, were longer, while accessory canals were distributed relatively evenly between central and lateral teeth.

CONCLUSIONS

The findings of this study further establish the significant similarities between contralateral mandibular incisors, reinforcing their suitability as a reliable substrate for root canal comparison studies.

CLINICAL RELEVANCE

The absence of statistically significant differences between contralateral pairs in normalized parameters underscores their potential as a reliable reference point for root canal comparison studies in clinical dentistry. Furthermore, our findings emphasize the importance of individualized treatment planning, considering the natural symmetry in mandibular incisors to enhance clinical decision-making. This research contributes valuable insights to the field of endodontics, offering a standardized approach to sample selection and enriching the understanding of dental anatomy.

Morphometric relationships in mesio-buccal roots of maxillary first molars in Saudi subpopulation: A CBCT study

This CBCT-based study analysed morphometric relationships in Mesio-Buccal (MB) roots of maxillary first molars (MFM). 133 MFM with two MB canals were assessed and classified using Vertucci's classification. MB roots' length and MB1-MB2 canals inter-orifice distances (IOD) were noted. The data were analysed using SPSS software. The most frequently present canal was type IV (59.4%) followed by type II (40.6%). Mean MB roots' length for canals exhibiting type IV was 9.26 ± 0.21 mm and of those exhibiting type II was 12.8 ± 0.42 mm. Statistically significant relationship was found between MB root length and canal type. Mean IOD for type II and type IV canals was 2.4 ± 0.47 and 3.8 ± 0.21 mm, respectively. Statistically significant relationship was found between IOD and canal type. Length of MB root and IOD had a significant association with canal type present in MFM. This knowledge can enhance clinicians' understanding of canal morphology which can increase predictability and success rate of endodontic treatment.

Critical analysis of a new system to classify root and canal morphology - A systematic review

A novel system to classify root and canal morphology was recently introduced (Ahmed et al. 2017). This systematic review aimed to answer the following research question: Does the Ahmed et al. system provide a more accurate and practical classification of root and canal anatomy compared to other classifications? A literature search was conducted in Google Scholar, Scopus and Wiley Online Library to identify the citation counts for the article entitled 'A new system for classifying root and root canal morphology; doi.org/10.1111/iej.12685'. After removal of duplicates and unrelated articles, 15 studies were included and analysed. All studies compared the Ahmed et al. system with the Vertucci classification. Results revealed that both systems were able to classify simple canal configurations in single-rooted anterior and premolar teeth, disto-buccal and palatal roots of maxillary molars. However, the Ahmed et al. system provided more accurate and comprehensive categorisations of single-rooted teeth with complex canal anatomy, multi-rooted maxillary and mandibular premolars and the mesio-buccal root of maxillary molars. Further evidence on the utility of the Ahmed et al. system is required using other diagnostic devices especially in molars.

Multipopulation evaluation of the internal morphology of mandibular first premolars from different South American countries. A micro-computed tomography study

OBJECTIVE

To evaluate and compare several anatomical parameters of mandibular first premolars from individuals from different Latin American countries using micro-computed tomography.

DESIGN

Five hundred extracted mandibular first premolars from Brazilian, Argentinian, Chilean, Colombian, and Ecuadorian individuals were scanned using micro-computed tomography (n = 100 teeth/country). Root canal configurations were classified according to established parameters. Analyses also included: canal volume and surface area, structure model index, distances from the apical foramen to the root apex or the cementoenamel junction, major/minor apical canal diameters, canal orifice shape, and prevalence of ramifications.

RESULTS

A single root was the most common anatomy in all countries (range, 97%-100%). Vertucci's type-I canal was the most frequent configuration (range, 36%-66%), followed by C-shaped and type-V canals. The oval-shaped canal orifice was the most predominant in all countries (range, 34%-58%), followed by the circular shape (range, 16%-47%). C-shaped canals occurred in all subpopulations (range, 14%-26%), always associated with radicular grooves. Ranges for canal ramifications were as follows: accessory canals, 36%-73%; lateral canals, 4%-12%; and apical delta, 4%-14% of the teeth. Many anatomic parameters differed significantly between countries (P < .05).

CONCLUSIONS

Vertucci's types-I and -V, and C-shaped canals were the most prevalent configurations in the subpopulations investigated. Accessory canals and several complex anatomies were found, with some significantly different frequencies between countries.

Prevalence of middle mesial canal using cone beam computed tomography: A systematic review and meta-analysis

Background

The presence of middle mesial canals in mandibular molars are not commonly encountered in daily practice. However, locating and debriding such anatomical variation during the endodontic therapy is essential to avoid endodontic failure. The aim of this systematic review was to identify the overall prevalence of middle mesial canals (MMC) in mandibular molars using cone-beam computed tomography (CBCT), to assess the influence of different gender on the prevalence of MMCs in mandibular molars and to describe the MMC configurations.

Methods

The review protocol was registered in the PROSPERO database (CRD42021238523). The main electronic databases were searched until February 2022 for prevalence studies on root/canal anatomy in mandibular molars using CBCT imaging, in addition to hand-searched scientific articles in peer-reviewed journals and grey literature. The quality of the included studies was assessed using the Joanna Briggs Institute Critical Appraisal tool. Egger's and Begg's tests and Pearson's chi-square test were used for statistical analysis.

Results

From 523 records, 488 studies were excluded after screening the title and abstract. 35 relevant studies were included for full-text assessment and 28 studies were included in the meta-analysis. The overall prevalence of MMC out of the 19,256 teeth was 5.09% (95% CI: 2.894 to 7.784). The prevalence of MMC was 9.79% (95% CI: 4.296 to 17.224) in males and 13.96% (95% CI: 0.541 to 40.737) in females with a statistically significant difference of 4.16% (95% CI: 2.29 to 6.01). The most MMC configuration found in this review to be confluent with the mesiobuccal canal.

Conclusion

The results showed an overall 5.09% prevalence of MMC in mandibular molars, with a significantly high prevalence in female subjects. Additionally, this canal was found to be confluent with the mesiobuccal canal.

Shaping outcomes of Reciproc Blue and Rotate in roots canals with band-shaped isthmuses: micro-CT study

OBJECTIVE

This study assessed the outcome of shaping the mesial roots of mandibular first molars containing band-shaped isthmuses with an isthmus floor located at the apical third with Reciproc Blue and Rotate instruments in terms of canal transportation, canal aberrations and unprepared apical canals.

MATERIALS AND METHODS

Pair-matched mesial roots of mandibular first molars according to their isthmus location (distance from apical foramina) and size were constructed based on quantitative measurements (length, major and minor diameter at isthmus roof and floor) on preoperative micro-CT scanning (n = 10). The pair-matched specimens were prepared either using Reciproc Blue R25 (25.08v) or Rotate (15.04, 20.05, 25.06) instruments and then subjected to a second micro-CT scanning. Micro-CT scans were analysed to evaluate the canal transportation at the apical foramen and isthmus floor levels and the frequency of procedural errors (separated instruments, artificial canal preparation, cross shaping and unprepared apical canals). Canal transportation values were compared using Mann-Whitney U, and the distribution of procedural errors was compared with chi-square tests with a 5% significance threshold.

RESULTS

Greater transportation values were detected in the apical foramen level compared to the isthmus floor in both groups. No significant difference was detected between Rotate and Reciproc Blue groups in terms of absolute transportation values and the incidence of procedural errors (p > .05).

CONCLUSION

Preparation of mesial root canals containing a band-shaped isthmus at the apical portion with Reciproc Blue and Rotate instruments caused transportation of the original canal position at the isthmus floor and the apical foramen levels and resulted in procedural errors.

CLINICAL RELEVANCE

This ex vivo micro-CT study using controlled pair-matched specimens showed that presence of a band-shaped isthmus complicates canal preparation procedure irrespective of the preparation systems.

Enhancing debris removal in curved canals: a comparative evaluation of XP-endo Finisher and Passive Ultrasonic Irrigation

OBJECTIVES

The study aimed to compare the efficacy of XP-endo Finisher and Passive Ultrasonic Irrigation (PUI) in removing hard tissue debris from curved canals.

MATERIALS AND METHODS

Thirty-four mandibular molars with Vertucci's type II mesial canals were scanned in microcomputed tomography before and after preparation with HyFlex EDM, and accumulated hard tissue debris was quantified. Subsequently, the teeth were randomly divided into two groups according to the supplementary procedure: PUI with the Ultra-X insert or XP-endo Finisher. After the intervention, the specimens underwent another scanning. Two separate analyses were conducted, one for the total canal and another for the isthmus area. Unpaired and paired T-tests were used for inter- and intergroup comparisons, with a significance level set at 5%.

RESULTS

Both supplementary methods reduced the amount of debris compared to the initial volume. Remarkably, the XP-endo Finisher achieved a significantly higher percentage of debris removal (71% for the total canal and 74% for the isthmus areas) compared to PUI (41% for the total canal and 52% for the isthmus area) (P < 0.05).

CONCLUSIONS

Both supplementary approaches reduced the amount of hard tissue debris from canal preparation, still XP-endo Finisher showed a higher reduction compared to PUI (p < 0.05).

CLINICAL RELEVANCE

None of the supplementary methods rendered canals completely free of hard tissue debris. However, the supplementary approach with XP-endo Finisher resulted in lower levels of hard tissue debris than PUI in curved canals with isthmuses.

The Prevalence of Middle Mesial Canals in the Second Mandibular Molars of an Iranian Subpopulation: A Cross-Sectional CBCT Study

Background Missed additional canals are a common reason for the failure of root canal treatments. The prevalence of additional canals in molar teeth can vary because of ethnic differences. Hence, this study aimed to determine the prevalence and distribution of middle mesial canals (MMCs) in the second mandibular molars using cone beam computed tomography (CBCT), for an adult population from Kerman in southeast Iran. Methodology De-identified retrospective provided CBCT scans from three private radiology centers in Kerman were reviewed (131 patients; 58 males (44.3%), 73 females (55.7%); age range: 13 to 54 years, mean age: 33). The presence of MMCs in mandibular second molars (222 teeth; 112 left and 110 right) was recorded, along with the morphology of the distal roots in the same teeth. Frequency data were analyzed using the Chi-square test and Fisher's exact test. Results The overall prevalence of MMC in the second mandibular molars was 2.3%. MMCs were found both unilaterally and bilaterally. More MMCs were found in females than males (2.7% vs. 1.7%), and on the left side (2.7% vs. 1.8%), but these differences were not statistically significant (p=1.0). There was no association between the existence of MMC in the mesial root and a second canal in the distal root of the same tooth. Conclusion Based on CBCT scans, the overall prevalence of MMC in mandibular second molars in this population was just below one in 44. Clinicians performing endodontic treatment on second molars should check for the presence of MMC so that this possible additional canal is not missed.

Internal Morphology of Mandibular Second Premolars Using Micro-Computed Tomography

To examine root canal morphology of mandibular second premolars (Mn2P) of a mixed Swiss-German population by means of micro-computed tomography (micro-CT). Root canal configuration (RCC) of 102 Mn2P were investigated using micro-CT unit (µCT 40; SCANCO Medical AG, Brüttisellen, Switzerland) with 3D software imaging (VGStudio Max 2.2; Volume Graphics GmbH, Heidelberg, Germany), described with a four-digit system code indicating the main root canal from coronal to apical thirds and the number of main foramina. A total of 12 different RCCs were detected. 1-1-1/1 (54.9%) was most frequently observed RCC, followed by 1-1-1/2 (14.7%), 1-1-2/2 (10.8%), 1-2-2/2 (4.9%), 1-1-3/3 (3.9%), 1-1-1/3 (2.9%), 2-1-1/1 (2.9%) and less frequently 1-1-2/3, 1-2-1/2, 2-1-2/2, 1-1-2/5, 1-1-1/4 with each 1.0%. No accessory foramina were present in 35.3%, one in 35.3%, two in 21.6%, three and four in 2.9%, and five in 2.0%. In 55.9% Mn2Ps, accessory root canals were present in apical third and 8.8% in middle third of a root. Connecting canals were observed less frequently (6.9%) in apical and 2.9% in the middle third, no accessory/connecting canals in coronal third. Every tenth tooth showed at least or more than three main foramina. Almost two thirds of the sample showed accessory root canals, predominantly in apical third. The mainly single-rooted sample of Mn2Ps showed less frequent morphological diversifications than Mn1Ps.

In vitro evaluation of filling material removal and apical debris extrusion after retreatment using Reciproc blue, Hyflex EDM and ProTaper retreatment files

OBJECTIVES

To evaluate the amount of remaining filing material and apical debris extrusion after retreatment using Reciproc Blue, Hyflex EDM and ProTaper Retreatment Files.

MATERIALS AND METHODS

Thirty-six extracted permanent mandibular first molars with moderately curved mesial roots were selected. Mesiobuccal canals were prepared using the ProTaper Next system up to size X2 and filled using gutta-percha and Adseal sealer via cold lateral compaction. Teeth were randomly divided into three equal groups (n = 12): Group 1: Reciproc Blue (RB)(VDW, Germany), Group 2: Hyflex EDM (HEDM)(Coltene/Whaledent, Switzerland), Group 3: ProTaper Universal Retreatment file system + ProTaper Next file system (PTUR + PTN)( Dentsply Maillefer, Switzerland). Eppendorf tubes were used to collect the apically extruded debris. Cone-beam computed tomographic scans were taken prior to and after retreatment and the volume of remaining filling material was assessed at the coronal, middle and apical levels. Statistical analysis was performed using the Kruskal-Wallis test, Friedman's test and Wilcoxon Sign Rank test. Significance level was set at p value 0.05.

RESULTS

There were no statistically significant differences among the three groups in the reduction of the volume of the filling material or in the amount of apically extruded debris.

CONCLUSION

All the tested filing systems showed similar efficacy in removing the filling material, however, none of them could achieve its complete removal. Apical extrusion of debris occurred with all the systems used with no significant difference between the three groups.

Efficiency and complications in root canal retreatment using nickel titanium rotary file with continuous rotation, reciprocating, or adaptive motion in curved root canals: a laboratory investigation

BACKGROUND

It is currently unknown whether rotary file motion affects the best outcome of root canal retreatment. This experimental study compared the efficacy, efficiency, and complications of single-use NiTi rotary files using continuous rotation, reciprocating, and adaptive motions in root canal filling removal in curved root canals. Reciproc blue R25 was used with reciprocating motion (RB), VDW.ROTATE retreatment files with continuous rotation (VR), and ProTaper NEXT X2 with continuous rotation (PTNc) or adaptive motion (PTNa).

METHODS

Forty mesial root canals of extracted mandibular first and second molars with an angle of curvature between 20°-40° and a radius of curvature between 5 and 10 mm were collected. The specimens were instrumented and obturated with gutta-percha and AH Plus sealer using the continuous wave of condensation technique. The specimens were randomly divided into 4 retreatment groups (n = 10), RB, VR, PTNc, and PTNa. The percentage of root canal filling removal in each group was analyzed using Micro-Computed Tomography (µCT). The motor running time, total time, root canal complication, and instrument complication were recorded and statistically analyzed (p-value < 0.05).

RESULTS

The pre-operative root canal curvature and root canal filling volume were comparable among groups. The percentage of root canal filling removal from the whole canal in the PTNc, RB, PTNa, and VR group was 98%, 96%, 95%, and 93%, respectively. A significant difference was observed between the PTNc and VR groups for the whole canal and the apical-third part. The motor running time and total time were significantly different between the groups. Instrument fracture was observed at 40% in the VR and 20% in the PTNa group, but none in the RB and PTNc groups.

CONCLUSIONS

The ProTaper NEXT X2 with continuous rotation and RB files can be used with high efficacy and efficiency in curved root canal retreatment. Continuous rotation is more efficacious and efficient than adaptive motion when using the NiTi rotary file. Single file retreatment can be used in small canals with high efficacy, cost-effectiveness, and less time consumption.

Method to determine the root canal spatial geometry using an algorithm of the e-Vol DX CBCT software

This study evaluated a method to determine the spatial geometry of root canal preparation (RCP) using navigation dynamics and a specific algorithm from a new CBCT software (e-Vol DX). CBCT scans of 168 root canals of mandibular molars were acquired before and after RCP, using nickel-titanium (NiTi) instruments (ProTaper Next, BioRace, Reciproc Blue, and WaveOne Gold). The spatial geometry of the root canals and the operative risk of disproportional wear of dentinal walls after RCP were evaluated using a new CBCT software. A 3-point scoring system was used after the measuring of cementum/dentin thickness before and after RCP in all root thirds. The root thirds were distributed into three parts of similar sizes, and the scores were categorized at three levels: 1. mild risk (1/3), 2. moderate risk (2/3), 3. severe risk (3/3). These levels were proposed according to the risk of creating disproportionate shapes, thin walls, or perforations. The data were analyzed statistically by Fischer's exact test (α = 5%). There were no significant differences in operative risk among the NiTi engine-driven systems, for the distal or mesial walls of all the root canal thirds (p>0.05). The spatial geometry method to assess operative risk allows clinical planning for a predictable enlargement of the root canal in all root thirds. Based on using a map-reading strategy on root canals in CBCT scans, NiTi engine-driven instruments did not present an increased operative risk during RCPs.

Internal adaptation and mechanical properties of CAD/CAM glass fiber post-cores in molars: An in vitro study

OBJECTIVE

The purpose of this in vitro study was to evaluate the internal adaptation, fracture resistance, and fracture pattern of the residual roots and crowns of molars restored with computer-aided design/computer-aided manufacturing (CAD/CAM) glass fiber post-cores, and compare them with three other post-core restorations.

MATERIALS AND METHODS

We selected 32 extracted maxillary first molars and divided them into four groups according to the post-core system: traditional casting titanium (Ti) post-cores (TC group); Ti post-cores fabricated with selective laser melting (SLM group); CAD/CAM glass fiber post-cores of the split type (CCS group); and prefabricated glass fiber posts and composite resin cores (PF group). The internal adaptation was analyzed with microcomputed tomography. Teeth were restored with monolithic zirconia crowns and subjected to thermocycling and cyclic loading. A load was applied consistently along the long axis of the tooth until fracture to record the fracture resistance and pattern. For the statistical analysis, one- and two-way analyses of variance, Tukey's post hoc and chi-square tests were performed to compare the differences among the groups.

RESULTS

The CCS, TC, and SLM groups exhibited similar internal adaptations across all sections (P < 0.05). The FP group showed good fit with the root canals in the apical and middle sections but a poor fit with those in the cervical section. The fracture resistance was higher in the CCS, TC, and SLM groups compared to the PF group (P < 0.05). The proportions of restorable fractures in the CCS and PF groups were 62.5% and 50%, respectively. Unrestorable fractures were more frequent in the TC and SLM groups at frequencies of 100% and 87.5%, respectively.

CONCLUSION

The internal adaptation and fracture resistance of the CCS group were similar to those of the TC and SLM groups, and the fracture pattern was mostly restorable, thus meeting the clinical requirements for molar post-core restorations.

CLINICAL SIGNIFICANCE

CCS can be used to restore residual roots and crowns of molars and exhibit high efficacy in terms of adaptability and mechanical properties. More studies are required to evaluate the effectiveness of CCS.

Impact of access cavities on root canal preparation, restorative protocol quality, and fracture resistance of teeth

The survival of endodontically treated teeth depends on the remaining tooth structure. The aim of this study was to evaluate the impact of different access cavities on root canal preparation, restorative protocol, and fracture resistance of endodontically treated teeth. Fifty-six mandibular molars were divided into control (n=8) and experimental (n=16) groups according to access cavity: Traditional, Conservative, and Truss; and redistributed (n=8) according to instrumentation protocols: Reciproc Blue and R-motion. After, teeth were scanned in micro-CT and then filled and redistributed according to composite resin restoration (n=8): Filtek One BulkFill and Filtek Z350. A new micro-CT scan was performed to analyze the restorative material. Then, samples were submitted to fracture resistance testing and the failure pattern was determined. Data were analyzed using paired T-test, ANOVA, Tukey, and chi-square tests (α=0.05). In Truss, R-Motion promoted less transportation in different thirds of root canals. Higher percentages of voids (5.05%) and filling material (11.7%) were observed in Truss. Fracture resistance values were higher for the control group, followed by Truss, Conservative, and Traditional. The predominant failure pattern was type-II. In Truss, reciprocating instruments with smaller taper showed less canal transportation. Also, Truss provided higher values of fracture resistance, although it presented a higher percentage of voids and remaining filling material. Thus, in Truss, reciprocating files with smaller taper showed less canal transportation, and these cavities provided higher values of fracture resistance, although it presented a higher percentage of voids and remaining filling material.

Evaluation of shaping ability of different glide path instruments: a micro-computed tomography study

BACKGROUND

This study aimed to compare the shaping ability of different instruments, TruNatomy Glider (TRN-G), WaveOne Gold Glider (WOG-G), and ProGlider (Pro-G) using micro-computed tomography (micro-CT).

METHODS

The mesial canals of 27 mandibular molars with two separate mesial canals and moderate curvature were included in this study [n = 27 mesiobuccal (MB) and mesiolingual (ML) root canal]. According to the manufacturer's instructions, the glide path was created with TRN-G, WOG-G, and Pro-G glide path instruments (n = 9 MB and ML root canal in each group). Micro-CT scanning was performed before and after preparation. Mesiodistal (MD) and buccolingual (BL) transportation and the centering ratio were measured at three levels within the canal (3, 5 and 7 mm). A three-way robust ANOVA was used to compare the parameters.

RESULTS

TRN-G showed significantly greater transportation in the MD direction than the other instruments throughout the root canal (overall root canal) (p < 0.05). The best centering ability in the BL direction was shown by the WOG-G, regardless of level within the canal and canal distinction (MB vs. ML) (p < 0.05). There was no significant difference between groups according to the level within the canal and canal parameters (p > 0.05). Whether the root canal was MB or ML did not affect centering or transportation (p > 0.05).

CONCLUSIONS

Glide path instruments can be used to shape moderately curved canals with minimal apical transportation and better centering ability. All three tested glide path files can used safely before the shaping file.

Treatment-Related Factors Affecting the Success of Endodontic Microsurgery and the Influence of GTR on Radiographic Healing-A Cone-Beam Computed Tomography Study

The primary objective of this retrospective study was to assess the correlation between treatment-related factors (resection angle, depth of retrograde filling, length of resected root and use of guided tissue regeneration-GTR) evaluated using cone-beam computed tomography (CBCT) scans and the treatment outcomes of endodontic microsurgery (EMS). The secondary purpose of this research was to evaluate the influence of the GTR technique on the radiographic healing state, taking into account the initial parameters of periapical lesions. In 161 cases, the local factors (volume of a lesion, bone destruction pattern, presence/absence of cortical bone destruction) were measured using preoperative CBCT images before undergoing EMS. At least one year after surgery, the outcome of EMS was classified as a success or a failure (based on radiographic and clinical criteria). Using postoperative CBCT, treatment-related factors (resection angle, depth of retrograde filling, and length of resected root) were measured. Additionally, the status of radiographic healing was evaluated (in accordance with modified PENN 3D criteria). Eighteen cases (11.18%) were classified as failures, and 143 were classified as successes (88.82%). Univariate analysis showed that there was no statistically significant influence of treatment-related factors on the healing outcome of EMS. An exact Fischer's test showed the significant impact of GTR on radiographic healing (P < 0.001) in apical lesions (P < 0.001), lesions with a volume between 100 mm3 and 450 mm3 (P < 0.009) and over 450 mm3 (P < 0.001), lesions with the destruction of one plate (P < 0.001), and lesions with the destruction of two plates (through and through) (P = 0.022). The use of GTR in apical lesions, lesions with volumes over 100 mm3, and lesions with the destruction of at least one plate is significantly associated with better radiographic healing.

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.