Micro–computed Tomographic Evaluation of the Prevalence, Distribution, and Morphologic Features of Accessory Canals in Chinese Permanent Teeth

Micro-computed tomographic evaluation of root and canal anatomy of maxillary first premolars in Iraqi sub-population

Successful root canal treatment requires a thorough understanding of root canal morphology. This study investigated the root canal morphology and the fine anatomical characteristics of maxillary first premolars in an Iraqi sub-population using micro-computed tomography (micro-CT) and classified using Vertucci and Ahmed et al. systems. A total of 151 extracted maxillary first premolars were collected, cleaned and disinfected. The collected teeth were scanned using a micro-CT system. The images were segmented and three-dimensionally (3D) reconstructed using Mimics research software, for the evaluation of root canal morphology, isthmuses and accessory canals. The data were analysed using the Monte Carlo simulations for Chi-Square test with a significance level of 0.05. Results showed that out of the 151 maxillary first premolars, 82 (54.3%) were double-rooted and 69 (45.7%) were single-rooted. The most common root canal configuration in the single-rooted teeth was Vertucci Type VII (Ahmed et al. code 1MaxP1-2-1-2), and Vertucci Type IV (Ahmed et al. code 2MaxP B1P1) was the most common type in the double-rooted teeth. About 15.2% of the samples could not be classified by Vertucci system and were classified using Ahmed et al. system. Isthmuses were observed in 28.5% of the samples with the middle root third was the most common location. Isthmus prevalence was significantly higher in single-rooted teeth (50.7%) compared to the double-rooted teeth (9.8%) (P < 0.001). The accessory canals were found in 77.5% of the samples, mostly in the apical third of the root, as classified by Ahmed et al. coding system for accessory canals. Accessory canal location varied more in the buccal root compared to the palatal root and single-rooted teeth (P < 0.05). Maxillary first premolars showed wide variations in root canal morphology and fine anatomical features such as isthmuses and accessory canals in the studied Iraqi population. Ahmed et al. system appeared to be more reliable in characterizing the root canal morphology compared to Vertucci classification. Clinicians need to consider utilising advanced imaging techniques, such as CBCT, to provide a clearer visualization of root canals. This allows them to plan disinfection protocols, ensuring thorough cleaning of the entire canal system.

A Micro-Computed Tomographic Evaluation of Root Canal Morphology of Mandibular First Molars in a Black South African Subpopulation

Background: This study evaluates the root canal anatomy (main and accessory canals) of mandibular first molars in Black South Africans using micro-computed tomography. The effect of sex, arch side, and age are also investigated. Methods: The number of root canals in each tooth and individual roots (including an observation of the middle-mesial and middle-distal canals), the number of accessory canals, accessory canal type, root canal thirds, and the prevalence of apical deltas were recorded. A chi-squared test of association (p < 0.05) was used to report on variables (sex, arch sides, and age). Results: In most teeth, either three (55.81%) or four canalled (24.42%) configurations were present. The middle-mesial canal was found in 18.6% of teeth (males and females), with a higher prevalence among females (23.68%). The middle-distal canal was found in 3.49% of teeth. Chamber canals were identified in 4.7% of teeth. Accessory canals most likely located in the apical third were found in approximately 84.9% and 86.1% of mesial roots and distal roots, respectively. Apical deltas were identified in 15.12% of mesial and 20.93% of distal roots. Conclusion: Root canal anatomy in this population is diverse and includes differences in arch sides between the sexes.

A micro-computed tomographic evaluation of maxillary first molar accessory root canal morphology in a Black South African subpopulation

PURPOSE

The aim of this study was to investigate the accessory root canal morphology of maxillary first molars in a Black South African subpopulation.

METHODS

Micro-computed tomography was used to investigate 101 maxillary first molars (from 50 male and 51 female teeth, right 53 teeth, left 48 teeth). The prevalence of chamber canals, and the number, type and location (root third) of accessory canals were recorded. The relationships between arch side, sex and age were examined using chi-squared tests of association. Intra- and inter-observer reliability were assessed using Cohen's kappa test.

RESULTS

Intra- and inter-rater agreement was 96.9% and 98.1%, respectively. Variations in accessory root canal anatomy according to side, sex and age were evident. Chamber canals were identified in 10.9% of teeth. Accessory canals were found mainly in the apical third of most teeth in the sample, and distributed predominantly in the mesio-buccal root. Apical deltas were most prevalent in the mesio-buccal root, and their frequency decreased in the palatal and then finally the disto-buccal root.

CONCLUSION

Accessory root canals were common in this population, and showed a diverse range of anatomy. The present findings will be of assistance to clinicians during endodontic treatment and will also be valuable for educational purposes.

Effects of the Irrigation Needle Design on Root Canal Disinfection and Cleaning

INTRODUCTION

This ex vivo study evaluated the disinfecting and cleaning effects of root canal preparation using sodium hypochlorite irrigation with 3 different needle designs.

METHODS

Mesial roots from extracted mandibular molars with Vertucci class II configuration were anatomically matched based on micro-computed tomography (micro-CT) analyses and distributed into 3 groups (n = 18/group). The canals were contaminated with a mixed bacterial culture for 30 days and then subjected to preparation using 2.5% sodium hypochlorite irrigation with open-ended flat needle (3 mm short of the working length - WL), closed-ended side-vented irrigation needle (1 mm short of the WL), or a closed-ended plastic needle with 2 lateral outlets (TruNatomy) (1 mm short of the WL). Bacteriological samples were taken from the canals before (S1) and after preparation (S2). After another micro-CT scan, the roots were sectioned and samples were also taken from the apical canal segment (S3). Bacterial reduction was assessed by quantitative real-time polymerase chain reaction. The amount of accumulated hard tissue debris was evaluated by micro-CT.

RESULTS

A substantial reduction in bacterial counts was observed in all 3 groups when comparing S1 with S2 (99.95%, 98.93%, and 98.90% in the open-ended, closed-ended, and TruNatomy needle groups, respectively) (P < .01). No significant differences were observed between groups for bacterial reduction in the full and apical canal (P > .05). There were no intergroup differences in the amount of accumulated hard tissue debris either (P > .05). The open-ended needle group showed significantly more specimens with quantitative real-time polymerase chain reaction negative results for bacteria in S3 than TruNatomy (P < .05).

CONCLUSION

When used up to an appropriate insertion depth, the 3 needle types result in similar antibacterial and cleaning performance, provided variables such as needle size and irrigant type, volume and flow rate are controlled. Exclusive analysis of the apical segment, including the isthmus, revealed that the open-ended needle yielded more cases negative for bacteria.

Effectiveness of supplementary antimicrobial procedures in disinfecting lateral canals as evaluated by a novel ex vivo analytical approach

This ex vivo study devised an analytical ex vivo method for infection/disinfection of simulated lateral canals located in the middle and apical segments of the root. The antibacterial effects of supplementary approaches were tested in this model. Extracted mandibular premolars had their main root canals enlarged and then two lateral canals (100 μm in diameter) were created in the root, one in the apical and the other in the middle portion. Micro-computed tomography was used for specimen selection and to confirm the quality of the simulated ramifications. The specimens were contaminated with a mixed bacterial culture from subgingival bacterial biofilm added to pure Enterococcus faecalis strain ATCC 29212 grown overnight, using special strategies to facilitate culture medium penetration within the lateral canals. The following procedures were tested for disinfection: NaOCl/passive ultrasonic irrigation (PUI), NaOCl/XP-endo Finisher, ozonated water/continuous ultrasonic irrigation (CUI), and NaOCl/conventional irrigation with 30-G needles (control). Bacteriological samples were taken from the main canal before (S1) and after (S2) each supplementary protocol, and also from each lateral canal after treatment (S3). DNA extracted from the samples was subjected to quantitative real-time polymerase chain reaction. All S1 main canal samples were positive for bacterial presence. Bacterial counts in the main root canal substantially decreased by 99.2% after PUI, 99.1% after ozone/CUI, 99% after XP-endo Finisher, and 96% in the control group (P < 0.01 for all groups). There were no significant differences between groups (P > 0.05). The same was observed when comparing the effects of the supplementary approaches in the apical and middle lateral canals (P > 0.05). Only a few lateral canals showed no detectable bacteria. The method proposed here proved effective for ex vivo infection/disinfection studies. All supplementary approaches induced a substantial bacterial reduction in the main canal, with no significant differences between them. However, in terms of lateral canal disinfection, none of the tested approaches showed significant effects when compared to the control group.

Assessment of Practitioners' Knowledge of the Diagnostic and Therapeutic Approach to Endo-Periodontal Lesions in Saudi Arabia

INTRODUCTION

Endodontic-periodontal diseases frequently pose significant challenges for clinicians in terms of diagnosis, management, and prognosis. Practitioners' knowledge of endo-periodontal lesion (EPL) diagnosis is essential for formulating appropriate treatment plans. This study aimed to evaluate the knowledge of diagnostic and therapeutic approaches to EPLs among dental practitioners in Saudi Arabia.

METHODS

The study used a cross-sectional survey among Saudi Arabian dental practitioners using a self-administered questionnaire. The statistical methods used included descriptive analysis, Pearson's chi-square test, Fisher's exact test, and binary logistic regression.  Results: The study included 312 respondents, with 95 (30.4%) females and 217 (69.6%) males. The majority were aged 25 to 30 (n = 155, 49.7%). Significant associations were found between participant knowledge and the following variables: age (P < 0.001), organization (P = 0.005), employment (P = 0.001), professional experience (P < 0.001), postgraduate degree (P = 0.002), specialty (P < 0.001), Saudi Commission for Health Specialities (SCHS) rank (P = 0.004), and continuing training (P = 0.043). Additionally, individuals aged 36-40 were 4.3 times more likely to have good knowledge compared to those aged 25-30 (adjusted odds ratio [AOR] = 4.27, P = 0.020), and lecturers were 4.4 times more likely to have good knowledge compared to interns (AOR = 4.40, P = 0.054).

CONCLUSION

This indicates that the practitioners' overall knowledge was above average and that they possess a fundamental understanding of EPLs. These findings have valuable effects on clinical practice, suggesting that evidence-based guidelines and targeted educational programs can enhance the practitioners' diagnostic accuracy and treatment strategies for EPLs, ultimately improving patient outcomes and clinical efficacy.

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.

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.

Morphological variation of gubernacular tracts for permanent mandibular canines in eruption: a three-dimensional analysis

OBJECTIVES

This study aims to evaluate the morphological features of gubernacular tract (GT) for erupting permanent mandibular canines at different ages from 5 to 9 years old with a three-dimensional (3D) measurement method.

METHODS

The cone-beam CT images of 50 patients were divided into five age groups. The 3D models of the GT for mandibular canines were reconstructed and analysed. The characteristics of the GT, including length, diameter, ellipticity, tortuosity, superficial area, volume, and the angle between the canine and GT, were evaluated using a centreline fitting algorithm.

RESULTS

Among the 100 GTs that were examined, the length of the GT for mandibular canines decreased between the ages of 5 and 9 years, while the diameter increased until the age of 7 years. Additionally, the ellipticity and tortuosity of the GT decreased as age advanced. The superficial area and volume exhibited a trend of initially increasing and then decreasing. The morphological variations of the GT displayed heterogeneous changes during different periods.

CONCLUSIONS

The 3D measurement method effectively portrayed the morphological attributes of the GT for mandibular canines. The morphological characteristics of the GT during the eruption process exhibited significant variations. The variations in morphological changes may indicate different stages of mandibular canine eruption.

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

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

Prediction of accessory canals on the apical third of mandibular second molar based on micro-computed tomography

OBJECTIVE

The aim of this study was to investigate the anatomical factors influencing the incidence of accessory canals (ACs) in the apical third of the mandibular second molar in Chinese population.

METHODS

Micro-CT was performed on 86 root canals. The five possible factors influencing the incidence of ACs in the apical third were named X1 to X5. These factors were the canal length of the apical third, fused roots, location of apical foramen, curvature of the root canals, and complexity of the canals. Statistical analysis was performed by the least absolute shrinkage and selection operator, receiver operating characteristic curve, and the χ2 test (α = 0.05).

RESULTS

The selected variables in the least absolute shrinkage and selection operator regression model were fused roots and complex root canals. The area under the curve was 0.737, indicating that the model had a certain predictive ability. ACs were mainly distributed in the buccal wall and mesial wall of root canals in the apical third of molars (p < 0.05).

CONCLUSIONS

For Chinese population, fused roots and complex root canals are anatomical factors influencing ACs in the apical one-third of mandibular second molars, and the ACs mainly occur in the buccal wall and mesial wall of the root canal.

The Preventive Effect of A Magnetic Nanoparticle-Modified Root Canal Sealer on Persistent Apical Periodontitis

Persistent apical periodontitis is a critical challenge for endodontists. Developing root canal filling materials with continuous antibacterial effects and tightly sealed root canals are essential strategies to avoid the failure of root canal therapy and prevent persistent apical periodontitis. We modified the EndoREZ root canal sealer with the antibacterial material dimethylaminododecyl methacrylate (DMADDM) and magnetic nanoparticles (MNPs). The mechanical properties of the modified root canal sealer were tested. The biocompatibility of this sealer was verified in vitro and in vivo. Multispecies biofilms were constructed to assess the antibacterial effects of the modified root canal sealer. We applied magnetic fields and examined the extent of root canal sealer penetration in vitro and in vivo. The results showed that EndoREZ sealer containing 2.5% DMADDM and 1% MNP had biological safety and apical sealing ability. In addition, the modified sealer could increase the sealer penetration range and exert significant antibacterial effects on multispecies biofilms under an external magnetic field. According to the in vivo study, the apices of the root canals with the sealer containing 2.5% DMADDM and 1% MNP showed no significant resorption and exhibited only a slight increase in the periodontal ligament space, with a good inhibitory effect on persistent apical periodontitis.

Micro-computed tomography analysis of root canal morphology and thickness of crown and root of mandibular incisors in Chinese population

OBJECTIVES

The aim of this study was to investigate the root canal morphology and the thickness of crown and root of mandibular incisors in a Chinese subpopulation by micro-computed tomography (micro-CT).

METHODS

In total, 208 mandibular incisors were scanned using micro-CT. The anatomical features of the canals (canal configuration, apical constriction, foramen-to-apex distance, accessory canal vertical distribution, and canal geometrical parameters) and the thickness of the crown and root 2/3 were evaluated.

RESULTS

Three canal categories, labeled as Single (77.88%), Merged (15.87%), and Separated (6.25%), were summarized. The most frequent constriction type in main foramina was single constriction (42.53%). Wide and narrow diameters in a single main foramen were 0.37 ± 0.14 mm and 0.26 ± 0.07 mm, respectively. The distance from the anatomical foramen to the physiological foramen and the anatomical apex was 0.49 ± 0.20 mm and 0.36 ± 0.28 mm, respectively. During the virtual root-end resection, 97.12% of roots underwent successful resection at the 2-mm level, with the foramina visible on the resection surface. During 2-D cross-sectional analyses, the shape parameters of the root and canal showed significant positive correlation (P < 0.05). The thickest and thinnest walls were the incisal and proximal walls (P < 0.05) of the crown, respectively. The buccal walls were significantly thicker than the lingual walls on the crown (P < 0.05), whereas the lingual walls were thicker on the root 2/3 (P < 0.05).

CONCLUSIONS

This study provides detailed information about the root canal morphology and thickness of the crown and root of mandibular incisors in a Chinese population. An understanding of morphology can benefit endodontic treatment.

CLINICAL RELEVANCE

Adequate knowledge of the crown, root, and canal morphology, as well as the thickness distribution of the crown and root, is essential for successful root canal therapy and prevention of complications.

Application of a new system for classifying root and canal anatomy in studies involving micro-computed tomography and cone beam computed tomography: Explanation and elaboration

Adequate knowledge and accurate characterization of root and canal anatomy is an essential prerequisite for successful root canal treatment and endodontic surgery. Over the years, an ever-increasing body of knowledge related to root and canal anatomy of the human dentition has accumulated. To correct deficiencies in existing systems, a new coding system for classifying root and canal morphology, accessory canals and anomalies has been introduced. In recent years, micro-computed tomography (micro-CT) and cone beam computed tomography (CBCT) have been used extensively to study the details of root and canal anatomy in extracted teeth and within clinical settings. This review aims to discuss the application of the new coding system in studies using micro-CT and CBCT, provide a detailed guide for appropriate characterization of root and canal anatomy and to discuss several controversial issues that may appear as potential limitations for proper characterization of roots and canals.

Temperature and time variations during apical resection

OBJECTIVE

The aim of this study was to investigate temperature and time variations during root-end resection.

MATERIAL AND METHODS

Sixty human premolars were selected. The root canals were enlarged up to ProTaper X3 rotary instrument. A thermocouple was placed into the root canal 1 mm behind the resection line. The teeth were randomly divided into six groups according to the apical resection method: steel bur, tungsten carbide bur, Lindeman bur, diamond bur, laser and ultrasonic surgical piezo with a diamond tip. The root ends were resected 3 mm away from the root apex. The temperature of the root dentine during resection was recorded as maximum temperature, mean temperature and temperature change. The time required for apicectomy was recorded for each group. The Kruskal-Wallis method was used to analyse the differences between temperature changes during apical resections. The significance level was set at 5%.

RESULTS

There was no significant difference between bur groups in terms of temperature increase. The maximum temperature in piezo surgery was significantly higher than the Lindeman, tungsten and steel burs (p < .001). In addition, the maximum temperature in laser surgery was higher than the Lindeman bur (p < .05). An increase in the temperature was mostly seen in piezo surgery and the least temperature change occurred in the Lindeman bur. Mean time stayed under 1 min in each group.

CONCLUSIONS

Although piezo caused the highest temperature increase, the measured temperature increase was within physiological limits in all tested techniques.

Assessment of Ramifications in the Apical Region of Root Canals: A Micro-CT Study in a Brazilian Population

The present study used microcomputed tomography (micro-CT) images to assess the prevalence, number, and location of apical ramifications (ARs) in the root canals of different dental groups in a Brazilian population. Three hundred and sixty-seven extracted human teeth, totaling 475 roots, were scanned by micro-CT at 19.6 µm spatial resolution. The obtained images were evaluated by two observers in consensus, and a descriptive analysis was performed to verify the prevalence, number, and location of ARs in each dental group. Chi-square test was used to compare the prevalence of ARs in different types of roots, and one-way analysis of variance compared the number of ARs in the apical 1 mm, 2 mm, and 3 mm of the root. Significance level was established at 5% (α=0.05). ARs were present in 253 (53.3%) of the 475 roots evaluated. A total of 607 ARs were detected, with the vast majority (530) located at one and two millimeters from the main foramen. The highest prevalence of ARs was observed in maxillary canines (65%); maxillary premolars - single-rooted (83.3%), buccal root (80%), and palatine root (73.3%); mandibular premolars (64.2%); mesiobuccal root of maxillary molars (76.6%); and mesial root of mandibular molars (66.6%). For the Brazilian population, most of the ARs are located in the apical 1 and 2 mm of the root, with greater prevalence in the posterior teeth and maxillary canines. These findings suggest the need for additional attention while planning endodontic treatments, including strategies to effectively clean and fill the apical region.

The MB3 canal in maxillary molars: a micro-CT study

OBJECTIVES

To assess the internal and external morphologies of the mesiobuccal (MB) root of maxillary molars presenting a third root canal (MB3), using micro-computed tomography (micro-CT).

MATERIAL AND METHODS

Two-hundred and sixty-five extracted maxillary first and second molars with different root configurations were imaged in a micro-CT scanner at 19.6-μm pixel size. Sixteen teeth presenting MB3 canal were selected and evaluated regarding root configuration, minimal dentine thickness 2 mm under the furcation area, canal configuration of the MB root, MB3 canal morphology (location, independent or confluent orifice, and anatomy types), and the apical anatomy (aspect ratio, number of accessory canals and foramina, presence of isthmus, and independent MB3 foramen).

RESULTS

Overall, a high variability in canal configuration was detected in the MB root. MB3 canal was observed in 10 maxillary first molars and 6 maxillary second molars (n = 16). Minimal dentine thickness related to the MB3 canal at the coronal third was smaller than that of the MB1 canal. A complex internal anatomy comprising 13 different root canal configurations was observed. A high number of independent MB3 orifices at the pulp chamber floor was observed in the first molars (7 out of 10 teeth), while most of the specimens (n = 14) showed a confluent anatomy of the MB3 canal. A varied number of accessory canals and foramina were observed. At the apical third, isthmus could be observed in 6 specimens, while an independent MB3 foramen was present in 37.5% of the MB roots.

CONCLUSIONS

MB3 canal is a rare anatomical variation present in maxillary first and second molars. Its presence can be associated to a complex internal anatomy of the MB root which includes the presence of isthmuses and multiple accessory canals and foramina at the apical third, but also a thin dentine thickness at the coronal third and a confluent anatomy of the MB3 with the other main canals.

Micro-computed tomographic assessment of the variability and morphological features of root canal system and their ramifications

Objectives

This study assessed the incidence and variability features of root canals system (RCS) and their ramifications according to Pucci & Reig (PR) (1944) and the American Association of Endodontists (AAE) (2017) by micro-computed tomography (μCT).

Methodology

500 representative extracted human teeth of each tooth group (n=50) (maxillary/mandibular central and lateral incisors, canines, first and second premolars and molars) were scanned by μCT with a resolution of 26.70 μm. The reconstructed cross-sections images and the visualization of the continuous slices in the transversal axis were performed using DataViewer software. RCS were classified according to Pucci & Reig (main canal, collateral canal, lateral canal, secondary canal, accessory canal, intercanal, recurrent canal) and AAE (main canal, accessory canal, lateral canal). The apical deltas were assessed for both classifications. The prevalence of apical deltas was evaluated using the Chi-squared test (p<0.05).

Results

According to PR, a higher incidence of lateral canals was observed in maxillary canines (10%), central incisors (8%) and first premolars (6%). Using AAE, the highest incidence of lateral canals was observed in the mandibular first premolars (85%), first and second molars (84%), lateral incisors (67%), canines (59%), and in maxillary first premolars (52%). Regarding accessory canals, the PR showed a frequency in 2% of the maxillary lateral incisors and maxillary and mandibular first premolars and 3% of mandibular first and second molars. On the other hand, the AAE showed the highest incidence of accessory canals in 86% of the maxillary first premolars, 71% in mandibular lateral incisors, 69% in mandibular first premolars, 65% in mandibular canines, and 56% in maxillary canines. The PR showed the lowest incidence of apical deltas for all dental groups when compared with AAE (p=0.004). Interestingly, distal canals in maxillary molars showed a significant discrepancy between classifications (p=0.027).

Conclusions

μCT enabled accurately describing the RC system and related ramifications, adding to the PR and AAE classifications, with some discrepancies reported for maxillary molars. Clinical Relevance This μCT study enabled a thorough description of the variability among root canals and their ramifications, including clinically relevant details on the presence and location of lateral canals and accessories in all human tooth groups, beyond the currently existing classification systems.