A cone-beam computed tomography study of canalis sinuosus and its accessory canals in a South African population.

OBJECTIVES: Canalis sinuosus (CS) is a clinically relevant structure in the anterior maxilla. The present study aimed to determine the prevalence and distribution of CS and its accessory canals (ACs) in the South African population and describe its anatomical variations. METHODS: In total, 500 cone-beam computed tomography (CBCT) scans of the anterior maxilla were assessed for prevalence, sidedness, diameter, and distribution of CS. The frequency, number, diameter, configuration, and point of termination of ACs were also recorded. Statistical analysis was performed using analysis of variance, Kruskal-Wallis, chi-squared, and Fisher Exact tests with P < 0.05. RESULTS: CS was present in most cases (99.6%), and commonly occurred bilaterally (98.8%). The mean diameter of CS was 1.08 mm (range: 0.50 mm-2.39 mm). Sex, population group, and age had no significant effect on the prevalence or sidedness of CS. Additionally, 535 ACs were observed in 58.8% of the sample, with 42.9% of ACs found bilaterally and 57.1% unilaterally. The mean diameter of the ACs was 0.86 mm on the left and 0.87 mm on the right (range; 0.50 mm-1.52 mm). The majority of ACs maintained a straight vertical configuration (72.3%). ACs most commonly terminated in the anterior palatal region of the maxilla (57.2%). No significant differences were found in any groups mentioned (P > 0.05). CONCLUSIONS: A high prevalence of CS as well as ACs were observed in the sample population. Due to their clinical significance, surgical planning with the aid of high quality CBCT scans of the anterior maxilla is advisable.

Ex vivo detection of mandibular incisors' root canal morphology using cone-beam computed tomography with 4 different voxel sizes and micro-computed tomography.

BACKGROUND: In recent years, cone-beam computed tomography (CBCT) has been widely used to evaluate patients' root canal anatomy due to its high resolution and noninvasive nature. As voxel size is one of the most important parameters affecting CBCT image quality, the current study evaluated the diagnostic potential of CBCT with 4 different voxel sizes in the detection of double root canal systems and accessory canals (ACs) in permanent mandibular incisors. METHODS: A total of 106 extracted mandibular permanent incisors were collected from the dental clinics, and then were scanned by using micro-CT with a voxel size of 9 µm. The teeth were then fixed in the tooth sockets of human dry mandibles and scanned by using a CBCT device with 4 different voxel sizes (300, 200, 250, and 125 µm). Four observers detected in blind the root canal morphology of the teeth according to the CBCT images, and the presence or absence of a double root canal system, and the presence or absence of ACs, were scored according to a 5-point scale, respectively. Receiver operating characteristic (ROC) analysis was performed, and DeLong test was used to compare the area under the curve (AUC) values and the micro-CT data was taken as a gold standard. RESULTS: Among 106 sample teeth, 25 specimens with a double root canal system were identified by the micro-CT. ROC curve analysis of the data obtained by the four observers showed that in the detection of double root canal systems, the AUC values ranged from 0.765 to 0.889 for 300 µm voxel size, from 0.877 to 0.926 for 250 µm voxel size, from 0.893 to 0.967 for 200 µm voxel size, and from 0.914 to 0.967 for 125 µm voxel size (all p < 0.01). In general, we observed a trend that the AUC values, sensitivity, and specialty increased with the decrease in the voxel size, and significantly higher AUC values were detected in 125 µm voxel size images. In the detection of ACs, ROC curve analysis showed that among the four observers, the AUC values ranged from 0.554 to 0.639 for 300 µm voxel size, from 0.532 to 0.654 for 250 µm voxel size, from 0.567 to 0.626 for 200 µm voxel size, and from 0.638 to 0.678 for 125 µm voxel size. CBCT images at a voxel size of 125 µm had a weak diagnostic potential (AUC: 0.5-0.7, all p < 0.05) in the detection of AC, with a lower sensitivity ranging from 36.8 to 57.9% and a higher specialty ranging from 73.6 to 98.8%. CONCLUSIONS: CBCT with 300 µm voxel size could only provide moderate diagnostic accuracy in the detection of a double canal system in mandibular incisors. CBCT with a voxel size of 125 µm exhibited high diagnostic value in the detection of double canal systems, while showing low but statistically significant value in the detection of ACs.

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.

A new classification system of trifid mandibular canal derived from Malaysian population.

BACKGROUND: The purpose of this study was to identify and classify the anatomic variation of mandibular canal among Malaysians of three ethnicities. MATERIALS AND METHODS: The courses of the mandibular canal in 202 cone-beam computed tomography scanned images of healthy Malaysians were evaluated, and trifid mandibular canal (TMC) when present, were recorded and studied in detail by categorizing them to a new classification (comprising of 12 types). The diameter and length of canals were also measured, and their shape determined. RESULTS: Trifid mandibular canals were observed in 12 (5.9%) subjects or 16 (4.0%) hemi-mandibles. There were 10 obvious categories out the 12 types of TMCs listed. All TMCs (except one) were observed in patients older than 30 years. The prevalence according to ethnicity was 6 in Malays, 5 in Chinese and 1 in Indian. Four (33.3%) patients had bilateral TMCs, which was not seen in the Indian subject. More than half (56.3%) of the accessory canals were located above the main mandibular canal. Their mean diameter was 1.32 mm and 1.26 mm for the first and second accessory canal, and the corresponding lengths were 20.42 mm and 21.60 mm, respectively. Most (62.5%) canals had irregularly shaped lumen; there were more irregularly shaped canals in the second accessory canal than the first branch. None of the second accessory canal was oval (in shape). CONCLUSIONS: This new classification can be applied for the variations in the branching pattern, length and shape of TMCs for better clinical description.

Prevalence, Radiographic Features and Clinical Relevancy of Accessory Canals of the Canalis Sinuosus in Cypriot Population: A Retrospective Cone-Beam Computed Tomography (CBCT) Study.

Background and Objectives: This retrospective study aims to evaluate the prevalence, radiographic features, and clinical relevancy of the accessory canals (AC) of the canalis sinuosus (CS) in patients referred for implant surgery. Materials and Methods: Cone-beam computed tomography (CBCT) images of the patients were collected and ACs were evaluated. Age, sex, bilateral distribution, localization, diameter, distance to the buccal cortical plate, distance to the crest of the alveolar ridge, terminal ending localization, and the presence of tooth or implant were recorded. Ninety-one patients who were eligible for this study were enrolled. Results: A total of 188 ACs were found in 91 patients with 86 bilateral and 5 unilateral distributions. The mean age of the patients was 45.39. All ACs had a terminal ending at the palatal cortical border. All parameters showed a non-normal distribution; thus, the Mann-Whitney U test was preferred. Bilateral AC distribution (p = 0.761), AC distance to the crest of the alveolar ridge (p = 0.614), AC distance to the buccal cortical plate (p = 0.105), and AC diameter (p = 0.423) showed no significant difference between females and males. According to our study, a CS might be an anatomical structure rather than an anatomical variation, as all patients had at least one AC of the CS. It can be inferred that the detection of ACs will be achievable once clinicians are aware of these structures with continuous regular anatomy reworks and with small voxel-sized CBCT devices. Conclusion: This study was conducted to find the features and prevalence of the CS, and it was found that the CS is an anatomical structure rather than an anatomical variation. This argument is in line with the information on the CS in Gray's Anatomy, 42nd Edition. Impaired healings and complications of the CS can be avoided if clinicians follow the American Academy of Oral and Maxillofacial Radiology guidelines regarding pre-operative implant examination. Otherwise, avertible complications may cause significant impairments in quality of life.

Multidisciplinary management of a type III palatoradicular groove: an atypical presentation.

The palatoradicular groove is an endodontic anomaly that complicates diagnosis, treatment planning, and prognosis. The extent of this developmental defect dictates the treatment plan. Treatment approaches may vary from simple restoration of the groove to surgical exploration. A palatoradicular groove may lead to pulpoperiodontal complications if not treated precisely. This case report describes a rare presentation of a type III palatoradicular groove in a maxillary lateral incisor that also had an accessory root and periodontal complications.

Morphological and Morphometric Characteristics of Anterior Maxilla Accessory Canals and Relationship with Nasopalatine Canal Type-A CBCT Study.

This study aimed to evaluate principal morphological and morphometric characteristics of accessory canals (ACs) of the anterior maxilla, as well as to analyze the relationship with nasopalatine canal (NPC) type. The results of our study showed that ACs were observed in almost 50% of participants. They were mostly presented bilaterally and in a curved shape, with a palatal foramen position. The morphometric characteristics of ACs were significantly influenced by NPC type. NPC type had the strongest impact on the distance between the NPC and AC, as well as on the distance between the AC and the facial aspect of buccal bone wall, in inferior parts of the alveolar ridge. On the other hand, the distance between the AC and central incisors was not significantly influenced by NPC shape in the lower region of the anterior maxilla. However, the participants with the banana-type of the NPC expressed the reduction in distance from the AC to the central incisor at the upper part in comparison with the subjects with the cylindrical-type of the NPC. On the basis of the results of this study, the simultaneous estimation of ACs and the NPC seems reasonable, as this approach may be useful in the prevention of complications which could occur during implant surgery interventions.

Anatomical study of the canalis sinuosus in Chilean individuals by cone-beam computed tomography / Estudio anatómico del canal sinuoso en individuos chilenos mediante tomografía computarizada cone-beam

SUMMARY: The canalis sinuosus (CS) is a double-curved bone canal in the anterior region of the maxilla. The CS contains a vasculo-nervous bundle consisting of the anterior superior alveolar nerve and its corresponding arteries and veins. The CS and its accessory canals (AC) have been little described in the literature and are often omitted in imaging evaluations before procedures in the region. The object of the present study was to evaluate the frequency of the CS and its AC in Chilean individuals, and to carry out a morphometric analysis of these anatomical structures by cone-beam computed tomography (CBCT) by sex, side and age range. CBCT examinations of 28 patients were studied, evaluating the presence, diameter and terminal portion of the CS. We also evaluated the presence and number of AC, and their terminal portion. The diameter of the AC was classified as greater or smaller than 1.0 mm. Non-parametric tests were used for quantitative variables and chi-squared for qualitative variables. The SPSS v.27.0 software was used, with a significance threshold of 5 %. The CS was present in all the samples analysed, generally presenting a diameter greater than 1.0 mm. Alterations were found, and the diameter could be greater depending on the segment evaluated, however it was not affected by sex, side or age range. The terminal portion of the CS is usually located adjacent to the region of the nasal cavity. The frequency of AC was very high, and the most common location was in the region of the upper central incisor; in 61.3 % of cases their diameter ?1.0 mm. The high frequency of CS and AC shows the importance of carrying out a detailed imaging study before invasive procedures in the anterior region of the maxilla.

RESUMEN: El canal sinuoso (CS) es un canal óseo que presenta doble curvatura, ubicado en la región anterior de maxila. El CS contiene un paquete vásculonervioso formado por nervio alveolar superior anterior, arterias y venas correspondientes. El CS y sus canales accesorios (CA) han sido poco descritos en la literatura y muchas veces son omitidos en evaluaciones imagenológicas previas a procedimientos en la región. El objetivo del presente estudio fue evaluar la frecuencia del CS y de sus CA en individuos Chilenos, bien como realizar un análisis morfométrico de estas estructuras anatómicas mediante tomografía computarizada cone-beam (TCCB) según sexo, lado y rangos etarios. Fueron evaluados exámenes de TCCB de 28 pacientes. Se evaluó la presencia, diámetro y porción terminal del CS. Se evaluó la presencia del CA, cantidad y porción terminal. El diámetro del CA fue clasificado en mayor o menor a 1,0 mm. Se utilizaron pruebas no paramétricas para variables cuantitativas y chi-cuadrado para variables cualitativas. Se utilizó el software SPSS 27.0, considerándose umbral de significación de 5 %. El CS estuvo presente en todas las muestras analizadas, presentando en general un diámetro mayor a 1,0 mm. El diámetro del CS sufre alteraciones pudiendo ser mayor dependiendo de la región evaluada, sin embargo no se ve afectado por sexo, lado o rangos etarios. La porción terminal de CS suele ubicarse adyacente a la región de cavidad nasal. La frecuencia de CA es muy alta, en un 61,3 % presentan diámetro ?1,0 mm, siendo la región de incisivo central superior su ubicación más común. La alta frecuencia de CS y de CA demuestra la importancia de realizarse un detallado estudio imagenológico previo a procedimientos invasivos en región anterior de la maxila.

An in vitro endodontic model to quantify the accessory canal filling potential of the vertical and lateral condensation techniques.

The purpose of this study was to determine the accessory canal filling potential of vertical and lateral condensation techniques in simulated root canals. A total of 130 prepared transparent, straight-simulated root canals with nine accessory canals (0.02 mm), prepared at different levels from the apical, were obturated with vertical (n = 100) and 30 lateral condensation (n = 30) techniques. 50.33% of the accessory canals obturated with vertical condensation were completely filled with gutta-percha; 37.78% completely filled with gutta-percha and sealer. 61.11% of the accessory canals were completely filled with sealer only using the lateral condensation technique. The vertical condensation technique filled the accessory canals more frequently than the lateral condensation techniques. The lateral condensation technique was not capable of delivering gutta-percha to any of the accessory canals. The apical third showed the lowest accessory canal filling frequency with both techniques.

To assess the occurrence of middle mesial canal using cone-beam computed tomography and dental operating microscope: An in vitro study.

INTRODUCTION: Failures of root canal treatments are mainly attributed to missed canals and ignorance about the complex anatomy of the root canal system. One such example of anatomic variation is the middle mesial canal (MMC) in mandibular molars which is often missed, and literature on methods for identifying them is limited. AIM: This in vitro study aimed to assess the occurrence of MMCs with cone-beam computed tomography (CBCT) and then under magnification in the mandibular first and second molars. MATERIALS AND METHODOLOGY: A total of 120 extracted intact human permanent mandibular first and second molars were selected. These were subjected to CBCT imaging and magnification for the detection of MMCs. The percentage of incidence in the detection of MMC was compared between these two methods. RESULTS: The incidence of MMC detected in mandibular molars using CBCT was 13.33% (16 of 120 teeth), while using a dental operating microscope, the incidence was 18.33% (22 of 120 teeth) and the comparison between the two methods was statistically not significant. The MMCs were classified based on the Pomeranz Classification. The most prevalent canal configuration was a confluent type which was found to be in 72% cases (16 of 22), followed by fin type which was 22.7% (5 of 22) and independent type was only 4.54% (1 of 22). The incidence of the location of MMC orifice was studied. In 50% of the cases, orifice was located closer to the mesiolingual canal, whereas in 27% of the cases, it was closer to the mesiobuccal canal and in 4.95% of the cases, it was detected midway. CONCLUSIONS: Since the incidence of MMC was higher with the use of a microscope, it is preferred to use simpler, chairside aids like magnification and ultrasonic troughing. On the other hand, one should be judicious while subjecting a case to preoperative CBCT evaluation owing to its ionizing radiation.

Surgical Sealing of Laterally Localized Accessory Root Canal with Resin Containing S-PRG Filler in Combination with Non-Surgical Endodontic Treatment: A Case Report.

The spread of root canal infection to surrounding periodontal tissue through accessory root canals reduces the success rate of endodontic treatment. In this case, cone-beam computed tomography revealed a lesion (4 mm from the apex) resulting from an accessory root canal of the maxillary left central incisor. First, non-surgical endodontic treatment was conducted but the sinus tract remained. Surgical preparation of the root cavity was then conducted to remove potentially infected dentin surrounding the accessory root canal. The cavity was filled and the foramen was sealed with resin containing bioactive surface pre-reacted glass (S-PRG) filler. The photopolymerized resin was then contoured and polished. In combination with subsequent supportive non-surgical endodontic treatment, a good clinical outcome with the disappearance of the sinus tract and clinical symptoms such as discomfort and pressure pain and the regeneration of the alveolar bone hanging over the cavity was obtained. In this case, the good clinical outcome may have been due to the dentin-adhesive property and durability of the pre-adhesive system and composite resin. The better biocompatibility of S-PRG fillers presumably facilitated periodontal tissue healing.

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

INTRODUCTION: The present study used high-resolution micro-computed tomographic imaging to investigate the prevalence, distribution, and morphologic features of accessory canals (ACs) in the Chinese population. METHODS: Scanning was performed on 1400 extracted permanent teeth using 15-µm resolution. The prevalence and distribution of the ACs in those teeth were analyzed. The number of ACs was calculated based on the following morphologic features: patent ACs without branching, obstructed ACs without branching, and branched ACs. Patent ACs were virtually segmented for measurements of their length and tortuosity. RESULTS: ACs were identified in 735 teeth (401 upper and 334 lower teeth). The incidences of ACs in the mesiobuccal and mesial roots were higher in the upper and lower molars. Of the 1611 ACs detected, 1182 were patent ACs without branching, 291 were obstructed ACs without branching, and 138 were branched ACs. In those branched ACs, 114 were type 1-2, 20 were type 2-1, and 4 were type 1-2-1. Most ACs were located in the apical third of the canal space (86.5%), with a median length of 880.9 µm. The length of ACs in the apical third was significantly shorter than those in the middle and coronal thirds of the canal space (P < .05). CONCLUSIONS: For the Chinese population, most ACs are located in the apical third, with lengths that are considerably shorter than those in the coronal and middle thirds of the canal space. Because ACs are more prevalent in premolars and molars, attention should be paid to their morphologic features during root canal treatment.

Detectability of middle mesial canal in mandibular molar after troughing using ultrasonics and magnification: an ex vivo study

Abstract The aim of this study was to evaluate the frequency of the identification of middle mesial (MM) canals in extracted permanent first and second mandibular molars before and after executing a troughing technique with high magnification. Sample consisted of 105 mandibular molars. After gaining access to the pulp chamber and cleaning the chamber floor, root canals were detected in three different stages. The initial location was performed under direct viewing without magnification. In the second stage, a dental operating microscope was employed at 12 magnification. If the MM canal was not observed, a standardized troughing technique was executed with the use of an ultrasonic tip between the mesiobuccal and mesiolingual canals under magnification. Statistical differences in the frequency of MM canals before and after troughing were determined using McNemar's test, with the significance level set at 5%. No significant increase in the identification of the MM canal was found when comparing observations before (9.52%) and after (12.38%) the troughing technique under high magnification. However, viewing under magnification and the execution of troughing significantly increased the location of the MM canal (12.38%) when compared to viewing without magnification (3.81%) (p<0.01). The troughing technique with the aid of a dental operating microscope significantly improved the identification of MM canals compared to viewing without magnification. Troughing is a safe, minimally invasive procedure that benefits the treatment of mandibular molars.

Resumo O objetivo deste estudo foi avaliar a frequência de identificação do canal médio-mesial (MM) antes e após a execução da técnica de troughing sob ampliação microscópica em primeiros e segundos molares inferiores permanentes extraídos. A amostra foi composta por 105 molares inferiores. Após abertura coronária e limpeza do assoalho pulpar, os canais radiculares foram detectados em três etapas diferentes. A localização inicial foi realizada sob visão direta, sem ampliação microscópica. Na segunda visualização, foi empregado um microscópio óptico com um aumento de ´12. Se o canal MM não foi observado, uma técnica padronizada de troughing foi realizada com o uso de pontas ultrassônicas entre os canais mésio-vestibular e mésio-lingual sob ampliação microscópica. Diferenças estatísticas na frequência dos canais MM antes e após o troughing foram determinadas usando o teste de McNemar, com um nível de significância de 5%. Não houve um aumento estatisticamente significativo na identificação do canal MM quando comparadas as visualizações antes (9,52%) e depois (12,38%) da técnica do troughing utilizando o microscópio óptico. Porém, a visualização com microscópio e a execução do troughing aumentaram significativamente a localização do canal MM (12,38%) quando comparada à visão prévia sem aumento (3,81%) (p<0,01). A técnica do troughing com o auxílio do microscópio óptico aumentou significativamente a identificação do canal MM quando comparada à visualização sem magnificação. Troughing é um técnica segura, minimamente invasiva e traz benefícios ao tratamento de molares inferiores.

Radicular Groove Accessory Canal Morphology in Mandibular First Premolars: Micro-computed Tomographic Study.

INTRODUCTION: The purpose of this study was to investigate the morphologic features of radicular groove accessory canals (RGACs) in mandibular first premolars and their relationship to root anatomy by micro-computed tomographic imaging. METHODS: A total of 154 single-rooted mandibular first premolars with radicular grooves were selected. The teeth were scanned by micro-computed tomographic imaging, and the following parameters were recorded: (1) the presence of RGACs, (2) the origin of RGACs, (3) the position of the RGAC foramen in the groove in relation to root length, (4) the foramen diameter, (5) the type of groove present according to the Arizona State University dental anthropology scoring system (ASUDAS), and (6) the type of anatomy present according to Vertucci's classification. The data were recorded and statistically analyzed using the chi-square test (P < .05). RESULTS: The incidence of RGACs in the teeth was 49.9%. The average distance from the cementoenamel junction plane to the RGAC foramen was 8.83 ± 2.53 mm, and the majority of the RGAC foramina were located in the middle third. Regarding the severity of the groove, the presence of RGACs was significantly higher for groups ASUDAS 3 and 4 compared with ASUDAS 1 and 2 (85.7% and 14.3%, respectively). The presence of at least 1 RGAC was greatest for Vertucci type V (46%) and for more complex types (46%) when compared with Vertucci types I and III. CONCLUSIONS: Mandibular first premolars with radicular grooves often present with RGACs. An association between the internal and external anatomy and the presence of RGACs was detected in this study.

Micro-computed tomography-based anatomical study of the branch canals in mandibular anterior teeth in a Chinese population.

OBJECTIVES: To analyze the incidence and distribution of branch canals in mandibular anterior teeth. MATERIALS AND METHODS: Three hundred mandibular anterior teeth, comprising 100 central incisors, 100 lateral incisors, and 100 canines, were scanned using a micro-computed tomography (micro-CT) system. Three-dimensional (3-D) visualization reconstruction of the root canal system and its branch canals was performed on each specimen. Data regarding the number of branch canals, the distance from the anatomical apex to the branch canal, and the orientation of each branch orifice were collected and analyzed. RESULTS: One hundred and fifty-three primary branch canals and 35 secondary branch canals were detected in the specimens overall. The incidence of branch canals in mandibular anterior teeth was 34%, with the highest incidence (50%) exhibited in mandibular canines, followed by lateral incisors (29%). Of the 153 primary branch canals found in the mandibular anterior tooth samples investigated, 82.35% appeared within 3 mm of the apical region, while 71.90% were labial and lingual canals. CONCLUSIONS: There was regularity in the distribution and orientation of branch canals in mandibular anterior teeth. CLINICAL RELEVANCE: This knowledge may be employed as a guide in clinical endodontic therapy.

A new system for classifying accessory canal morphology.

Thorough knowledge of anatomical complexities of the root canal system has a direct impact on the effectiveness of canal preparation and filling, and is an essential prerequisite for successful root canal treatment. A wide range of complex variations in root canal anatomy exists, including root canal configuration type, developmental anomalies and minor canal morphology such as accessory canals and apical deltas. Accessory canals and apical deltas have been associated with pulp disease, primary canal infection, canal reinfection and post-treatment disease. The current definitions of accessory canal anatomy are not standardized and potentially confusing. Given their role in endodontic disease and their impact on treatment outcomes, there is a need to have a simple classification of their anatomy to provide an accurate description of their position and path from the canal to the external surface of the root. The purpose of this article is to introduce a new system for classifying accessory canal morphology for use in research, clinical practice and training.

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.