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INTRODUCTION: The anatomical variations of the mandibular canal have been described according to the number of additional branches it presents, bifid and trifid. Within the bifids we can also find subtypes of variations such as the retromolar mandibular canal. These anatomical variations can have important clinical implications for the work of dental professionals. METHODS: A systematic search of the literature was carried out in different databases that met the following criteria: articles published between 2000 and 2020, and articles that established a clinical correlation with variations in the mandibular canal. RESULTS: After applying inclusion and exclusion criteria, 32 articles were obtained, in which the variations of the mandibular canal were identified, their prevalence and incidence, which was very varied between the different articles, it was also found that the CBCT was the main technique to identify the anatomical variations of the mandibular canal. Lastly, the anatomical variations of the mandibular canal have a direct clinical correlation with pre-surgical, intra-surgical and postsurgical complications in pathologies that require surgical intervention. CONCLUSIONS: The anatomical variations of the mandibular canal have a high incidence, so knowing them is of vital importance both for clinicians and anatomy professors who provide morphological training. We believe that research should focus on describing and diagnosing the causes of these anatomical variations. That said, there is also a continuous challenge for all health professionals to learn about the different anatomical variations that the human body presents and how these can affect clinical practice.

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BACKGROUND: Morphological variations of the mandibular canal (MC) have been described in literature, so the clinician must be able to recognise them and adapt their treatment accordingly. The aim of this study was to determine the prevalence of morphological variations of the MC using digital panoramic radiographs (DPR) of Chilean patients. MATERIALS AND METHODS: A retrospective study in which 1400 DPR were analysed to identify cases of bifid, trifid and retromolar MC. The radiographs were analysed independently by two examiners who had previously been trained by a specialist in oral and maxillofacial radiology. Inclusion and exclusion criteria were applied to reach a final sample. RESULTS: Nine hundred and twenty-five radiographs were included (599 female, 326 male; mean age 36.1 ± 15.54 years). The prevalence of bifid MC was 11% (n = 102), with no significant differences by sex (p = 0.069). Proportion of bifid MC was higher among younger patients (p = 0.038). Prevalence of morphologi- cal variations of type 1 bifid MC was 7.4% (n = 69), type 2 was 2.3% (n = 23), type 3 was 0% (n = 0) and type 4 was 1.1% (n = 10). Prevalence of retromolar canal was 0.9% (n = 8), with no significant differences by sex (p = 0.893) or age (p = 0.371); of these, 2 (0.2%) cases were forward type and 6 (0.6%) cases were retromolar type. No cases of trifid MC were found. CONCLUSIONS: Digital panoramic radiographs are useful for detecting morphological variations of the MC; we were able to identify three types of bifid MC as well as retromolar canals. Proper identification of these variations by an easily accessible examination is important for avoiding possible complications in clinical-surgical practice.

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The mandibular canal (MC) originates in the mandibular foramen and runs bilaterally through the mandibular ramus and body, ending in the mental foramen. One of the most common anatomical variations is bifid MC, the configurations of which have been classified into four categories and sub-categories. The prevalence of these variations depends on the imaging method used. Studies carried out in panoramic X-rays and cone beam computed tomography (CBCT) show prevalences varying between 1% and 20%. In this case report we present the finding of a bilateral bifid MC by CBCT examination; we describe its location and morphological characteristics. The variation found was a type 1 bilateral bifid MC, which consists in an accessory canal originating from a single mandibular foramen and extending to the third molar or its immediate surroundings. In this report we discuss the importance of detecting these anatomical variations, as well as their implications in clinical practice.

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As cirurgias odontológicas que envolvem estruturas adjacentes ao canal mandibular requerem exato conhecimento do curso intraósseo dessa estrutura anatômica e suas variações, reduzindo os riscos de injúrias a esse local. Esta pesquisa teve como objetivo verificar a prevalência e classificação das alterações do canal mandibular por meio da análise de imagens de TCFC. A amostra foi composta por 300 tomografias obtidas no banco de dados da Faculdade São Leopoldo Mandic, Campinas-SP. Dos 300 pacientes pesquisados, 90 apresentaram alterações no canal mandibular, ou seja, nos 39 do gênero masculino e nas 51 do gênero feminino, estes somaram 129 condutos acessórios. Em (66,7%), o direcionamento era para mesial ou anterior (classe B), enquanto em (19,4%), a trajetória era no sentido retromolar (classe D). Por outro lado, as classificações E (sentido lingual) e F (sentido para inferior ou base da mandíbula) foram observadas, respectivamente, em (4,6%) e (9,3%) dos casos. Em nenhum caso, foi notada a presença de canais bífidos classificados como classe A (sentido vestibular) ou C (sentido alveolar ou superior). De acordo com os resultados obtidos nesse estudo, encontrou-se uma prevalência de 30% de canais mandibulares bífidos; o tipo de canal bífido mais prevalente foi classe B para mesial ou anterior, e a maior ocorrência dos canais mandibulares bífidos foi bilateral.

The dental surgery involving structures adjacent to the mandibular canal, require accurate knowledge of intraosseous course of this anatomical structure and its variations, reducing the risk of injuries to this site. This research aimed to determine the prevalence of mandibular bifidus channels through analysis (CBCT). The sample comprised 300 CT scans obtained in the database of Radiology and Imaging Department of the Faculty São LeopoldoMandic, Campinas- SP. Was drawn a cutting plane accompanying the bone edge of each patient to obtain the cross section. Of the 300 patients surveyed, 188 (62.7%) were female and 112 gender (37.3%) were male. The age range of patients was comprised of 13 to 87 years of age Changes in the mandibular canal were observed in 90 patients representing (30.0%) of the sample, this total met 51 women (56.7%) and 39 men (43.3%). Regarding side affected by the change, it was found the following percentages right sides 32.2%, left 24.5% and bilateral occurrence were found in 43.3% of cases. According to the results obtained in this study, we found a prevalence of 30% of bifid mandibular canals, bifid canal type most prevalent was class B mesial or earlier and the higher incidence of mandibular bifidus canals was bilateral.

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