Accessory Canals Research Articles

Determining the optimal dose of 1940-nm thulium fiber laser for assisting the endodontic treatment.

Insufficient cleaning, the complex anatomy of the root canal system, inaccessible accessory canals, and inadequate penetration of irrigants through dentinal tubules minimizes the success of the conventional endodontic treatment. Laser-assisted endodontic treatment enhances the quality of conventional treatment, but each laser wavelength has its own its own limitations. The optimal parameters for the antibacterial efficiency of a new wavelength, 1940-nm Thulium Fiber Laser, were firstly investigated in this study. This paper comprises of two preliminary analyses and one main experimental study, presents data about thermal effects of 1940-nm laser application on root canal tissue, effective sterilization parameters for bacteria, Enterococcus faecalis, and finally the antibacterial effectiveness of this 1940-nm Thulium Fiber Laser irradiation in single root canal. Based on these results, the optimal parameter range for safe laser-assisted root canal treatment was investigated in the main experiments. Comparing the antibacterial effects of four laser powers on an E. faecalis bacteria culture in vitro in 96-well plates showed that the most effective group was the one irradiated with 1W of laser power (antibacterial effect corresponding to a log kill of 3). After the optimal laser power was determined, varying irradiation durations (15, 30, and 60s) were compared in disinfecting E. faecalis. Laser application caused significant reduction in colony-forming unit values (CFU) compared with control samples in the 17% ethylenediaminetetraacetic acid (EDTA) group. The results of bacteria counts showed that 1W with 30s of irradiation with a 1940-nm thulium fiber laser was the optimal dose for safely achieving maximal bactericidal effect.

Micro-CT assessment of internal morphology and root canal configuration of non C-shaped mandibular second molars

The root canal system morphology of the mandibular second molar was investigated by means of micro-computed tomography (μCT). The root canal configuration (RCC), foramina and accessory canals frequency of 93 mandibular second molars of an Egyptian sample were investigated by μCT scans. The RCC and main foramina number (MFN) are described by means of a four-digit system from coronal to apical. The most frequently observed RCCs in the mesial root were 2-2-1/1 (32.3%), 2-2-2/2 (28.0%), 1-1-1/1 (6.5%) and 2-1-1/1 (6.5%); an additional twelve different RCCs were also found here. In the distal root, the RCC 1-1-1/1 was observed in 81.7%; another ten different RCCs with a frequency of less than 5% were also observed in this root. Anastomoses be-tween the mesiobuccal and mesiolingual canals in the mesial root were witnessed in the coronal (20.5%), middle (19.4%) and apical (10.8%) thirds. Accessory canals were found in the coronal (mesiobuccal 15.0%, mesiolingual 12.9%, distobuccal 1.1%), middle (mesiobuccal 7.5%, mesiolingual 10.8%, distolingual 3.3%) and apical (mesiobuccal 19.3%, mesiolingual 16.2%, distolingual 10.8%, distobuccal 2.2%) thirds. The RCC of mandibular second molars showed a great variety. When compared with the first mandibular molar in a historical control from the same sample, the mandibular second molar presented less morphological diversifications. Yet, the mesial root canalsystem of the mandibular second molar showed more RCC variations, connecting and accessory canals than the distal root.

Micro-CT assessment of internal morphology and root canal configuration of non C-shaped mandibular second molars

The root canal system morphology of the mandibular second molar was investigated by means of micro-computed tomography (μCT). The root canal configuration (RCC), foramina and accessory canals frequency of 93 mandibular second molars of an Egyptian sample were investigated by μCT scans. The RCC and main foramina number (MFN) are described by means of a four-digit system from coronal to apical. The most frequently observed RCCs in the mesial root were 2-2-1/1 (32.3%), 2-2-2/2 (28.0%), 1-1-1/1 (6.5%) and 2-1-1/1 (6.5%); an additional twelve different RCCs were also found here. In the distal root, the RCC 1-1-1/1 was observed in 81.7%; another ten different RCCs with a frequency of less than 5% were also observed in this root. Anastomoses be-tween the mesiobuccal and mesiolingual canals in the mesial root were witnessed in the coronal (20.5%), middle (19.4%) and apical (10.8%) thirds. Accessory canals were found in the coronal (mesiobuccal 15.0%, mesiolingual 12.9%, distobuccal 1.1%), middle (mesiobuccal 7.5%, mesiolingual 10.8%, distolingual 3.3%) and apical (mesiobuccal 19.3%, mesiolingual 16.2%, distolingual 10.8%, distobuccal 2.2%) thirds. The RCC of mandibular second molars showed a great variety. When compared with the first mandibular molar in a historical control from the same sample, the mandibular second molar presented less morphological diversifications. Yet, the mesial root canalsystem of the mandibular second molar showed more RCC variations, connecting and accessory canals than the distal root.

Micro-CT assessment of internal morphology and root canal configuration of non C-shaped mandibular second molars

The root canal system morphology of the mandibular second molar was investigated by means of micro-computed tomography (μCT). The root canal configuration (RCC), foramina and accessory canals frequency of 93 mandibular second molars of an Egyptian sample were investigated by μCT scans. The RCC and main foramina number (MFN) are described by means of a four-digit system from coronal to apical. The most frequently observed RCCs in the mesial root were 2-2-1/1 (32.3%), 2-2-2/2 (28.0%), 1-1-1/1 (6.5%) and 2-1-1/1 (6.5%); an additional twelve different RCCs were also found here. In the distal root, the RCC 1-1-1/1 was observed in 81.7%; another ten different RCCs with a frequency of less than 5% were also observed in this root. Anastomoses be-tween the mesiobuccal and mesiolingual canals in the mesial root were witnessed in the coronal (20.5%), middle (19.4%) and apical (10.8%) thirds. Accessory canals were found in the coronal (mesiobuccal 15.0%, mesiolingual 12.9%, distobuccal 1.1%), middle (mesiobuccal 7.5%, mesiolingual 10.8%, distolingual 3.3%) and apical (mesiobuccal 19.3%, mesiolingual 16.2%, distolingual 10.8%, distobuccal 2.2%) thirds. The RCC of mandibular second molars showed a great variety. When compared with the first mandibular molar in a historical control from the same sample, the mandibular second molar presented less morphological diversifications. Yet, the mesial root canalsystem of the mandibular second molar showed more RCC variations, connecting and accessory canals than the distal root.

Anatomical analysis of the pulp chamber of artificial teeth

The anatomy of root canals is very variable, with the presence of ramifications, side canals, accessory canals, and interconnections. Therefore, the knowledge of the internal tooth morphology has a fundamental importance for the localization and treatment of root canals, thus achieving success in endodontic treatment. In Endodontics, the preclinical teaching requires human teeth, but because of the current difficulty in obtaining them, the students have used artificial dental elements. Objective: This study aimed to evaluate the anatomy of the pulp chamber of artificial teeth, used in practical activities in Endodontics. Material and methods: Therefore, the artificial teeth were X-rayed through the digital system and the internal anatomy of the pulp chamber was measured through the Image Tool software. Results: The height of the mandibular pulp chamber: mandibular molar = 1.8 mm and maxillary molar = 1.32 mm; distance from the furcation to the pulp chamber floor: mandibular molar = 5.89 mm and maxillary molar = 7.24 mm; distance from the furcation to the pulp chamber’s roof: mandibular molar = 7.61 mm and maxillary molar = 8.59 mm; distance from the tip of the buccal cusps to the furcation: mandibular molar = 14 mm and maxillary molar = 15 mm; distance from the tip of the buccal cusps to the pulp chamber’s floor: mandibular molar = 7.9 mm and maxillary molar = 8.1 mm; distance from the tip of the buccal cusps to the pulp chamber’s roof: mandibular molar = 6.2 mm and maxillary molar = 6.4 mm. The measures were homogeneous with maximum percentage variation of 26.5%. Also, the artificial teeth were similar to natural teeth, except for the relationship between the pulp chamber’s roof and cementum-enamel junction. Thus, it is recommended the use artificial teeth with caution in preclinical teaching of Endodo ntics.

Anatomic Comparison of Contralateral Premolars

IntroductionThe comparative anatomy of contralateral premolars has not been previously studied. The purpose of this micro–computed tomography investigation was to qualitatively and quantitatively assess and compare the morphology of contralateral premolars in terms of length, canal width, dentinal thicknesses, accessory canals, root canal configurations, isthmi, C-shapes, root canal orifices, and apical foramina. The null hypothesis (H0) is that contralateral premolars are more morphologically similar than randomly assigned pairs for simple morphometric measurements (lengths, canal widths, and dentinal thickness). MethodsForty-one intact premolar pairs (n = 82) extracted from 28 patients were scanned with micro–computed tomography and reconstructed. Quantitative comparative assessment of measurements was performed by pairwise statistical analysis of contralateral and random pairs with Student t test and one-sample t test. All measured parameters (lengths, widths, and thicknesses) were normalized by Z score so that they could all be compared on a common scale. A correlation study was also performed. Canal configurations and isthmi were classified according to preexisting classification schemes. The number and location of accessory canals and apical foramina were registered and compared. Results/ConclusionsContralateral premolar pairs demonstrated a high degree of similarity in terms of the linear measurements (lengths, widths, and thicknesses). The apical portion (foramina, C-shapes, and accessory canals) did not demonstrate bilateral symmetry. The comprehensive statistical analysis of the normalized parameters by Z score showed no statistically significant differences between the contralateral premolar pairs. The null hypothesis (H0) was accepted.

Incidence and characteristics of mandibular accessory canals: A radiographic investigation.

The aim of the present study was to explore, through tridimensional reconstructions of cone-beam computed tomography (CBCT) scans, the presence and the characteristics of mandibular accessory canals. For each included participant, the presence of accessory canals was recorded. The diameter of the canal, as well as the distance between the canal walls and the walls of the mandibular bone (lingual, buccal, cranial and caudal), were measured and recorded. Mandibular accessory canals could be found in 8.8% of participants. Retromolar canals were the most frequently found accessory mandibular canals. Accessory mandibular canals were found in a relatively high number of participants through the examination of CBCT scans and tridimensional reconstruction. The presence of such structures should be considered cautiously when planning and performing surgical interventions in mandibular area.

Cone beam computed tomography evaluation of bifid mandibular canals in the adult population in Sichuan Province

To investigate the incidence of bifid mandibular canals (BMC), and analyze the types, courses, and anatomic features of the variant canals in the adult population in Sichuan Province. Five hundred patients (1 000 hemimandibles) underwent cone beam computed tomography (CBCT) were included in this study. The incidence, bifurcate types and courses of the BMC were evaluated. The incidence of BMC was 13.8% (69/500) in the study, 9.2% in terms of total hemimandibles. The most frequently type was retromolar canals, followed by the dental and buccolingual type, meanwhile the lowest was the forward type. The mean diameter of the accessory canals was 0.90 mm and the mean length was 9.39 mm. CBCT used in this study has shown that the incidence of BMC assessed by CBCT was significantly higher than panoramic radiography. Furthermore, CBCT can depict the position, course, size and the branches of the mandibular canals. .

Root canal morphology and configuration of 123 maxillary second molars by means of micro-CT

The aim of this study was to investigate the root canal configuration, accessory canals and number of main foramina of 123 maxillary second molars by means of micro-computed tomography. The teeth were scanned and reproduced with 3D software imaging. The root canal configuration and number of main foramina were evaluated by means of a four-digit system. The morphological complexity of human maxillary second molars is depicted by the number of accessory and connecting canals. The most frequently observed root canal configurations in the mesiobuccal root were 2-2-2/2 (19.5%), 2-2-1/1 (14.6%) and 2-1-1/1 (13.0%). A 1-1-1/1 configuration was observed in 93.5% and in 96.7% in the distobuccal and palatal roots, respectively. The MB1 root canal had one accessory canal (18.7%), and 8.9% of the MB2 root canal had one or two accessory canals. The distobuccal (11.3%) and palatal (14.6%) root canals had at least one accessory canal, and connecting canals were observed in 16.3% of mesiobuccal roots. The MB1, MB2, distobuccal and palatal root canals had one main foramen in 99.2%, 43.1%, 98.4% and 99.2% of samples, respectively. In the mesiobuccal root, one accessory foramen was detected in 14.6%, two were detected in 7.3%, and three were detected in 5.7%. The distobuccal root showed one or two accessory foramina in 9.1% of samples. The root canal configuration of maxillary second molars is quite heterogeneous; the mesiobuccal root has predominantly two root canal entrances (58.4%, 1 in 41.1%) with one main foramen (54.4%). Two main foramina were observed in 43.0%. Morphological variations, connecting and accessory canals were observed in all apical thirds.

Evaluation of the morphology of the canalis sinuosus using cone-beam computed tomography in patients with maxillary impacted canines.

PurposeThe nasopalatine canal is a well-known, important anatomical structure in the anterior maxilla, but this region contains many accessory canals. The canalis sinuosus (CS) is one of these canals; it contains the anterior superior alveolar nerve, along with veins and arteries. The purpose of this study was to evaluate the CS using conebeam computed tomography (CBCT) in patients with maxillary impacted canines.Materials and MethodsA total of 111 patients admitted to the Istanbul Medipol University School of Dentistry for the exposure, orthodontic treatment, and/or extraction of an impacted canine were included in this study. CBCT images were obtained for these patients under standard conditions. Axial, coronal, and sagittal sections were evaluated to assess the prevalence of CS, the direction and diameter of the canal, its relation with the impacted canine, and its distance from the alveolar crest. Further, possible correlations with patient gender and age were analyzed.ResultsThe CS could be detected bilaterally in all the evaluated tomography images. The mean canal diameter was significantly larger in males than in females (P=.001). The CS ran significantly closer to the impacted canine when the canal was located horizontally (P=.03). Variations of the canal, such as accessory canals, were identified in 6 patients.ConclusionCS is an anatomical entity that may resemble periapical lesions and other anatomical structures. Evaluation with CBCT prior to surgical procedures in the anterior maxilla will help to prevent overlooking such anatomical structures and to decrease possible surgical complications.

Cone-beam computed tomography as advanced diagnostic aid in endodontic treatment of molars with multiple canals: Two case reports.

The purpose of these case reports is to emphasize the importance of knowledge regarding the root canal morphology and current diagnostic aids one should have as both of these important factors going to affect the prognosis of the endodontic treatment. These two case reports describe the maxillary and mandibular first molars with multiple canals. After clinical and radiographic diagnosis, additional help of cone-beam computed tomography (CBCT) of mandibular molar has been taken to evaluate the morphology and canal pattern; while maxillary molar was evaluated using CBCT scan to evaluate the canal configuration and obturation. In CBCT evaluation, the mandibular molar was diagnosed with six separated canals with three mesial and three distal canals and with radix paramolaris and radix entomolaris. The maxillary molar had five canals with three mesiobuccal (MB) canals. Both molars were instrumented with conventional hand and rotary file systems and obturated by conventional lateral compaction method. The axial images from CBCT show Vertucci Type VIII canal pattern in both roots of first mandibular molars and in MB root of maxillary first molar Sert and Bayirli Type XVIII canal configuration and no accessory canal in distobuccal and palatal root. With the recent innovations in diagnostic and operating aids, we can come across many variations in the root canal morphology of both mandibular and maxillary teeth, especially multi-rooted one (i.e., molars), and the knowledge of which leads to successful endodontic treatment with an excellent prognosis.

Endo-perio lesions-the problem and the solutions

Periodontium is anatomically interrelated with the pulp through different pathways like dentinal tubules, lateral and accessory canals and apical foramen. The simultaneous existence of pulpal problems and periodontal disease can complicate diagnosis and treatment planning. When examining and treating the combined or individual lesion in endodontics and periodontics, the clinician must bear in mind that successful treatment depends on a correct diagnosis. This case series gives an insight into the various diagnostic modalities and treatment procedures that can be applied for the resolution of the endo-perio lesions.

A morphological study of the foramina of the mandible in the Japanese macaque by cone-beam computed tomography.

The mandibular canal (MC) contains vessels and nerves in the mandible of the Japanese macaque (JM). The inferior alveolar nerves and vessels of the mandible insert from the mandibular foramen and then run through the MC, the mental foramen and spinal foramen to the outside of the mandible. However, the detailed morphological properties of multiple canals, such as the accessory canal (AC) of the mandible, are unknown in JMs. The purpose of this study was to describe the multiple canals of JMs and to determine the location and analyse the measurements of the JM mandible. In this study, we also showed the course of the lingual foramen in 17 JMs (male: n = 8; female: n = 9) using cone-beam computed tomography (CBCT). In our results, we classified multiple mental foramina and multiple lingual foramina found on the mandibular body at the premolar or molar region. However, there was no significance between the formation of mandibular properties and the lingual foramen. These multiple foramina contain nerves and blood vessels have a few branched canals; these branches run downward and connect with the inferior mandibular nerve and artery. These morphological features may provide useful information about surgical treatment of the alveolus in a human model.

Comparative study of substance P and neurokinin A in gingival crevicular fluid of healthy and painful carious permanent teeth.

It is shown that neuropeptides can be transported from pulp chamber to periodontal ligament through apical foramen and accessory canals. Therefore, clinical pulpal pain leads to expression of preinflammatory neuropeptides such as substance P (SP) and neurokinin A (NKA) in gingival crevicular fluid (GCF). This study aimed to evaluate levels of SP and NKA in GCF of carious and healthy permanent teeth, comparatively. This cross-sectional study was performed on twenty children referred to Department of Pediatric Dentistry, Tehran University of Medical Sciences, who had a painful permanent first molar. Sampling was done by sterile paper cone from GCF of the mentioned teeth and the intact tooth of the other side of the jaw in the same patient. Values of SP and NKA were measured by ELISA test. The mean concentration of SP in GCF of painful carious and healthy teeth was 2.65 ± 0.56 and 1.83 ± 0.65 pcgr/ml, respectively. This value was 2.29 ± 0.29 and 1.61 ± 0.35 pcgr/ml for NKA concentration in carious and healthy teeth as well. Significant higher levels of both SP and NKA in GCF of painful carious teeth were observed, which is in line with previous studies' findings.

Cone Beam Computed Tomography Evaluation of Root Canal Anatomy in Primary Molars: An in vitro Study

ABSTRACT Introduction Endodontic treatment requires knowledge of root canal morphology and its commonly occurring variation. The utility and relevance of cone beam computed tomography (CBCT) to the practice of endodontics is reported with increasing frequency in the field of endodontics for successful procedures. Therefore, the present study is undertaken to assess the variation in number and morphology of the root canals of primary molars. Materials and methods Extracted primary molars with at least two-thirds of intact root, and 7 to 12 mm length were cleaned in water and stored in 0.5% sodium hypochlorite for 1 week. Thereafter, the anatomy of the root canals of these primary molars was assessed through CBCT. Results In the present study, the majority of canals were ribbon shaped. Accessory canals were few and maximum number was found to be present in mesiobuccal root of maxillary first molar and the least in mesiobuccal root of mandibular second molar. Conclusion The CBCT proved to be as accurate as the gold standard in studying the presence of accessory canals with clinical applicability. This study highlights the usefulness of CBCT imaging for accurate diagnosis of the unusual canal morphology. How to cite this article Joshi N, Deshpande A, Poonacha KS, Bargale S, Naik K, Mehta D. Cone Beam Computed Tomography Evaluation of Root Canal Anatomy in Primary Molars: An in vitro Study. Int J Clin Dent Res 2017;1(1):15-19.

Micro-CT study of the root canal anatomy of maxillary canines.

BackgroundThis study aimed to describe the anatomy of maxillary canines from a Western Mexican sub-population using micro-computed tomography (micro-CT).Material and MethodsMaxillary canines (n=32) were scanned at 19.6µm voxel resolution. Number and location of canals, the distance between the cemento-enamel junction and apex, occurrence of accessory and lateral canals, presence of oval canals, number of foraminas as well as two- (area, perimeter, roundness, aspect ratio, major and minor diameters) and three-dimensional (volume, surface area, and SMI) analysis were performed. Data of two-dimensional analyses at 5 different apical levels was statistically compared using Kruskal-Wallis tests (α=0.05).ResultsOverall, 31 specimens had one root with a main canal (Vertucci type I). Mean distance from the apex to the cemento-enamel junction was 16.32±2.27. Apical foraminas were present in 14 specimens (43.75%). No statistical differences were found in the two-dimensional analyses between the foramen and the 1 and 2mm apical levels (P >0.05).ConclusionsMaxillary canines presenting one root canal were present in a high percentage of cases (96%). The prevalence of long oval canals was <12% at the apical third and at least 37% of the sample showed more than one point of exit in the last apical 3mm. Key words:Maxillary canine, micro-computed tomography, root canal anatomy.

Assessment of accessory canals of the canalis sinuosus: a study of 1000 cone beam computed tomography examinations

The aim of this study was to verify the presence, spatial location, and calibre of the accessory canals (AC) of the canalis sinuosus by cone beam computed tomography, and their relationship to the anterior maxilla. This retrospective analysis included the scans of 1000 subjects. Parameters registered were sex, age, number of AC, presence or absence of AC with a diameter <1.0mm, AC diameter (only for AC with a diameter >1.0mm), and AC location in relation to the adjacent teeth. Males showed a statistically higher frequency of AC than females. The difference in age distribution was not statistically significant. Twenty percent of all AC presented a diameter of a least 1.0mm. The end of the AC trajectory was most frequently located palatal to the anterior maxillary teeth. All relationships analyzed here were very weak (age vs. number of AC, age vs. AC diameter, number of AC vs. sex). Overall, the results of this study showed that AC of the canalis sinuosus are a common anatomical structure in the anterior maxilla, regardless of age and sex.

Evaluation of root canal morphology of maxillary second premolars in a Saudi Arabian sub-population: An in vitro microcomputed tomography study.

AimTo investigate the root canal morphology of maxillary second premolars in a Saudi Arabian subpopulation using microcomputed tomography (micro-CT).MethodologyMicro-CT analysis was performed on 100 maxillary second premolars. The anatomy of each tooth (number of roots, canals, orifices, and apical foramina, and the presence of apical deltas and accessory canals) was analyzed from reconstructed three-dimensional images.ResultsThe most common morphology was a single root (67%), followed by two roots (30%), and three roots (3%). Regarding the canal morphology, most teeth (65%) contained two canals, followed by 30% with one canal, and 5% with three canals. One orifice was observed in 55% of teeth, and two orifices were detected in 45% of teeth. According to the Vertucci classification, the most common canal types were IV and V (both found in 23% of teeth), followed by type I (17%), type III (9%), type II (7%), and type VII (2%). Additional types that were inconsistent with the Vertucci classification were recorded in 19% of teeth.ConclusionThe root canal morphology of maxillary second premolars in the Saudi Arabian subpopulation is complex and requires cautious evaluation prior to endodontic treatment.

Prevalence and morphometric analysis of three-rooted mandibular first molars in a Brazilian subpopulation.

ABSTRACTThe knowledge of the internal anatomy of three-rooted mandibular molars may help clinicians to diagnose and plan the root canal treatment in order to provide adequate therapy when this variation is present.Objectives:To determine the prevalence of three-rooted mandibular molars in a Brazilian population using cone beam computed tomography (CBCT) and to analyze the anatomy of mandibular first molars with three roots through micro-CT.Material and Methods:CBCT images of 116 patients were reviewed to determine the prevalence of three-rooted first mandibular molars in a Brazilian subpopulation. Furthermore, with the use of micro-CT, 55 extracted three-rooted mandibular first molars were scanned and reconstructed to assess root length, distance between canal orifices, apical diameter, Vertucci's classification, presence of apical delta, number of foramina and furcations, lateral and accessory canals. The distance between the orifice on the pulp chamber floor and the beginning of the curvature and the angle of canal curvature were analyzed in the distolingual root. Data were compared using the Kruskal-Wallis test (α=0.05).Results:The prevalence of three-rooted mandibular first molars was of 2.58%. Mesial roots showed complex distribution of the root canal system in comparison to the distal roots. The median of major diameters of mesiobuccal, mesiolingual and single mesial canals were: 0.34, 0.41 and 0.60 mm, respectively. The higher values of major diameters were found in the distobuccal canals (0.56 mm) and the lower diameters in the distolingual canals (0.29 mm). The lowest orifice distance was found between the mesial canals (MB-ML) and the highest distance between the distal root canals (DB-DL). Almost all distal roots had one root canal and one apical foramen with few accessory canals.Conclusions:Distolingual root generally has short length, severe curvature and a single root canal with low apical diameter.

Evaluation by dental cone-beam computed tomography of the incidence and sites of branches of the inferior dental canal that supply mandibular third molars

Our aim was to assess the incidence and anatomical site of branches of the inferior dental canal that supply mandibular third molars using dental cone-beam computed tomography (CT). We evaluated the incidence and diameter of branches of the inferior dental canal using 272 cone-beam CT mandibular scans from 172 patients referred for imaging before the extraction of impacted mandibular third molars. We found three typical branching patterns from the inferior dental canal in the third molar region: the retromolar canal (in the retromolar triangle), the dental canal (that courses directly beneath the socket of the third molar), and the accessory canal (that courses through the socket and leads from the inferior dental canal to a bony ridge). The incidences of retromolar, dental, and accessory canals were 75 (28%), 223 (82%), and 21 (8%), respectively, with mean diameters of 0.9 (0.4), 0.7 (0.5), and 1.1 (0.4) mm, respectively. Operative injury to the neurovascular contents within the branches of the inferior dental canal can lead to excessive bleeding and postoperative paraesthesia, so identification of its branches on preoperative cone-beam CT images may prove useful during extraction of impacted mandibular third molars or when harvesting bone blocks from the region of mandibular third molars. We also describe two cases of branches detected on panoramic and cone-beam CT images that prompted this research.