What are the retromolar and bifid/trifid mandibular canals as seen on cone-beam computed tomography? Revisiting classic gross anatomy of the inferior alveolar nerve and correcting terminology

Impact of articles written in non-alphabet languages

Nowadays, English is the lingua franca of science, and the reference lists in most English articles are dominated by other English articles. Publications in languages other than English are most often in French, Italian, Spanish, or German. The minority written languages, that is, non-alphabet languages, have often not been included in reference lists in the scientific literature. However, to accord with the "diversity, equity, and inclusion" concept, non-alphabet languages should be included and discussed. Failure to cite articles in non-alphabet or non-standard languages ignores knowledge that could be useful to both the author and the reader. We hope the present article will promote more discussion of this often-overlooked topic.

Critical analysis of anatomy and classification of retromolar canal: an observational CBCT study

BACKGROUND

The retromolar canal (RMC) is an anatomical structure of the mandibular bone located distal to the last molar. The frequency of anatomical variation in human anatomy is approximately 30-35%. This study aimed to evaluate the prevalence of the retromolar canal in a population subjected to cone beam computed tomography (CBCT).

METHODS

The radiographic images belonged to 200 patients (100 males and 100 females; older than 13 years old) were examined following a strict protocol. Four hundred hemi-mandibles of 100 male and 100 female patients were examined between 2019 and 2022.

RESULTS

The collected data showed 136 patients presented the RMC, bilateral in 72 cases (68%) and unilateral in the other 64 cases (32%). Gender variation did not yield statistically significant differences, with 76 male (56%) and 60 female (44%) patients affected (P>0.05). A statistically significant difference was observed for side predilection, with unilateral RMC more prevalent on the right side in 24 cases (37.5%) and on the left side in 40 cases (62.5%) (P<0.05).

CONCLUSIONS

Based on the results obtained and other anatomical considerations, this study proposes a new classification for RMC.

Prevalence and topography of bifid and trifid mandibular canal in Turkish Western Anatolia Population: evaluation of the inferior alveolar canal with CBCT

PURPOSE

Various anatomical variations of the inferior alveolar canal increase the incidence of surgical complications; Therefore, this study aimed to evaluate the frequency and configuration of bifid and trifid mandibular canals using cone beam computed tomography (CBCT) in the Turkish subpopulation.

METHODS

The inferior alveolar canal was evaluated on 1014 hemi-mandibles in the CBCT (I-CAT 3D Imaging System) images of 513 patients. The frequency and configuration of the bifid and trifid mandibular canal (MC) were examined. The relationship between bifid MC configuration and dental status and age groups was analyzed. The distance of the accessory canal to the buccal and lingual walls and the alveolar crest was measured. The diameter of the main canal and accessory canal was measured and its relationship with dental status and age groups was evaluated.

RESULTS

Bifid MC was found in 266 hemi-mandibles (24.7%) and 212 (41.3%) of 513 patients. The most common type of bifid MC was the retromolar canal (87 sides), followed by the forward canal without confluence (41; 4%) and the dental canal (34; 3.4%). 10 of the dental canals were opening to the 1st molar, 14 of the 2nd molars, and 10 of the 3rd molars. The number of retromolar foramina was 1 on 56 sides, 2 on 15 sides, and 3 on 4 sides. Forward canal without confluence was more common in edentulous patients than in dentulous patients, while the dental canal was more common in dentulous patients. The main canal diameter was 3.53 ± 0.97 mm and the bifid MC diameter was 1.82 ± 0.70 mm. Distance of the bifid MC to the lingual wall was higher in the > 64 years group than in the 18-39 years group (p = 0.022). Distance of the bifid MC to the alveolar crest was lower in the > 64 years group compared to the 18-39 years group and 40-64 years group (p = 0.015). The main canal diameter was higher in the 40-64 years group than in the 18-39 years group (p = 0.012).

CONCLUSION

Bifid MC has a high prevalence, occurring in almost one in two patients. Dental and retromolar types, which are close to the teeth, are more common, and this increases the possibility of complications. CBCT is the most accurate imaging technique used to detect and define these variations.

The alveolar canals and foramina in the first edition of Terminologia Oroanatomica: a preview

Anatomy was initially developed out of necessity to decrease surgery complications. Over time, anatomists and surgeons have sometimes used different terms for the same anatomical structures, thus resulting in numerous discrepancies in terminology between anatomy and surgery. To avoid any confusion or misunderstanding and to better elucidate the oral anatomy terms, the Federative International Programme for Anatomical Terminology (FIPAT) organized a group of specialists on oral anatomy, Terminologia Oroanatomica (ToA) working group, composed of dentists, anatomy researchers, anatomy educators, oral and maxillofacial surgeons, and oral and maxillofacial radiologists. Within the ToA working group, major anatomical structures in the mandible, such as the mandibular canal, were focused and discussed to determine the most appropriate term, i.e., inferior alveolar canal. Although yet to be approved by the International Federation of Associations of Anatomists (IFAA), this article will preview some changes suggested by the ToA.

A histology guide for performing human cadaveric studies: SQIP 2024 what to look for with light microscopy

Histological observation under light microscopy has long been used in human cadaveric studies. However, it can distort the interpretations of findings if not used appropriately; there is no guide for its proper use. The aim of this article is to revisit and discuss the correct use of histology in human cadaveric studies, following discussions with experts in multiple fields of medicine, and to create the first guide for such usage. We reached a consensus with the experts, agreeing that when this principle (structure, quantification, interaction, position: SQIP) is applied to histological observations, the findings will be interpreted correctly. Appropriate use of this recommendation can make human cadaveric studies more accurate and informative. This is the first histology guide for human cadaveric studies.

Identifying the Anatomical Variations of the Inferior Alveolar Nerve with Magnetic Resonance Imaging

BACKGROUND

The inferior alveolar nerve (IAN) is located in the mandibular canal (MC). It is critical to evaluate the position of the MC during treatment planning to prevent intra or postoperative complications.

AIMS

This retrospective study aimed to identify the anatomy and anatomical variations of the IAN using soft tissue imaging (pulse sequence magnetic resonance imaging [MRI]).

MATERIALS AND METHODS

This study was designed as a retrospective Consolidated Standards of Reporting Trials (CONSORT) study. In total, 220 MR images were obtained. Nutrient canals (NCs) were classified as intraosseous and dental NCs, while bifid MCs (BMCs) were classified as forward, retromolar, and buccolingual canals. IBM SPSS Statistics 22 was used. Kolmogorov-Smirnov and Shapiro-Wilk tests, descriptive statistical methods (means, standard deviations, and frequencies), and the Chi-square test were used. Statistical significance was set at P < 0.05.

RESULTS

In total, 220 patients (172 females and 48 males) were evaluated. NCs were present in 92.3% of all MCs and were significantly higher in patients aged <25 years. BMCs were observed in 106 patients (24.1%). The most common BMC of MC/IAN was in the forward canal (14.4%), followed by the retromolar canal (7.5%).

CONCLUSION

Although previously, the dental canal was considered as an anatomical variation, this study revisited the classification and suggested that dental canals are anatomical structures.

An evaluation of mandibular canal variations: a systematic review and meta-analysis

The inferior alveolar nerve and vessels are carried via the mandibular canal, which extends bilaterally from the inferior alveolar foramen to the mental foramen. Bifid and trifid mandibular canals result from abnormal fusions of nerve canals. The purpose of this study was to provide an up-to-date and comprehensive analysis of the prevalence of mandibular canal variations among healthy adults, and to identify any potential ethnic, sex, or laterality predilections. The prevalence of the bifid mandibular canal was 18.87% and that of the trifid canal 1.3%. Unilateral variants were three times commoner than bilateral. Each mandibular half had four canals emanating from separate openings on the lingual surface of the mandibular ramus. Retromolar and forward canals were the predominant subtypes, followed by dental; buccolingual were the least frequent. The mean length and diameter of the bifid mandibular canal were 13.62 mm and 1.63 mm, respectively. The possibility of a bifid mandibular canal is a crucial consideration in dental medicine. Because anatomical variations of the mandibular canal are fairly common, awareness of them is essential for anatomy teachers and for surgeons who operate in the oromaxillofacial region.

A Case of a Previously Unreported Drainage of the Maxillary Vein

Due to the importance of venous drainage of the head and neck in various pathological conditions, knowledge of anatomical variations is important to the clinician. Here we report a case of an unusual drainage pattern of the maxillary vein. A tributary of the left maxillary vein was found in a female cadaver (72 years old at the time of death) to travel through the medial aspect of the ramus of the mandible via an accessory mandibular foramen, which drains into the ipsilateral facial vein slightly proximal to the point where the anterior branch of the retromandibular and facial veins merged to form the left common facial vein. The diameter of the variant vein at the junction with the maxillary vein and at the junction with the facial vein was 1.0 mm and 1.1 mm, respectively. We report a previously unreported variant of the maxillary vein bypassing the retromandibular vein and draining directly into the facial vein. Knowledge of such a variant might help explain various complications such as hemorrhage and might prevent iatrogenic injury of the blood vessels during surgery in this region.

Prevalence and Characteristics of Accessory Mandibular Canals: A Cone-Beam Computed Tomography Study in a European Adult Population

The purpose of this observational study is to evaluate the prevalence and main characteristics of bifid canals within a European adult population, analyzing cone-beam-computed tomography (CBCT). The population study examined 300 subjects. The CBCTs were performed between 2012 and 2019, using PaX-Zenith3D with a standard protocol of acquisition. The parameters analyzed were the presence and lengths of the bifid mandibular canals. The sample included 49% male and 51% female participants. The mean age of the patients was 47.07 ± 17.7 years. Anatomical variants of the mandibular canal were identified in 28.8% of the sides and 50.3% of the patients. In 7.3% of the subjects, the anatomical variants were present bilaterally. The most frequently encountered bifid canal was Type 3 (40.5%), followed by the Type 1 canal (39.3%), the Type 2 canal (14.5%), and the Type 4 canal (5.9%), 40% on the right side and 60% on the left side. The average length of the bifid canals located on the right side of the mandible was 11.96 ± 5.57 mm, compared to 11.38 ± 4.89 mm for those measured on the left side. The bifid mandibular canal is a common anatomical variation of the mandibular canal. It is fundamental to performing an accurate preoperative evaluation using CBCT analysis to avoid and/or reduce intraoperative and postoperative complications.