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In the surgical procedures such as osteotomy to be applied to ramus of the mandible, care should be taken not to damage the inferior alveolar nerve (IAN). The safe zone, which is the area above and behind the mandibular foramen (MF), is the ramus of mandible area, where these surgeries can be performed without damaging the inferior alveolar neurovascular bundle. It was aimed to determine the safe zone in the ramus of mandible in the cone-beam computed tomography (CBCT) images of individuals. The CBCT images of 300 Turkish individuals between the ages of 18 to 65 were bilaterally and retrospectively evaluated. Three parameters on the sagittal and two parameters on the axial plane were measured. Additionally, two ratios were calculated which determined the superior and posterior part of the safe zone through the measured parameters. In this study, the safe zone was determined as the area where 55% of the upper part and 49% of the posterior part of the mandibular ramus. Determining the safe zone in surgical procedures to be applied to the ramus of mandible will help protect the neurovascular structures passing through the MF, reduce complications and increase the success rate of the surgical procedure. However, it is seen that there are few studies on this subject in the literature and there are some differences between these studies. The authors think that preoperative CBCT screening will be safer for each patient in the mandibular ramus osteotomies and more studies should be done on different populations to determine standard values.

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Introduction: Variations in the branching pattern of the aortic arch (AA) are common. Modification of intravascular stents should be considered taking into account these AA branching variations. Identification of supra-aortic branching types and frequencies is important for specialists planning surgery in this region. In endovascular interventions to the AA, aortic stent grafts should be modified according to the variations of the branching patterns of the AA. In any surgical intervention to the region where the supraaortic branches are located, ignorance of the variations may cause unwanted injuries or complications.Methods: In this study, 699 computed tomography angiography (CTA) images were reviewed to investigate AA branching variations using the Horos software (an open-source image viewer). Four groups were constructed based on the number of branches emerging from the aortic arch, which were further divided into subtypes.Results: A total of 699 CTA images from 320 males and 379 females were included in this study. The usual AA branching pattern (type 3b1) was found in 68.5% of the patients. The combined prevalence of other eight branching patterns, designated as variations, was 31.5%. Variation types 1b1, 3b2, and 4b5 were identified in one patient each. Overall, types 2b1 and 2b2 had a prevalence of 28.3%. The type 2b3 variation was observed in 1.6% of the patients. The least common variations were type 4b1 (0.7%) and type 3b2 (0.1%). Conclusion:The identification of variations in AA branching patterns by CTA prior to surgical or endovascular interventions involving the aortic arch is important. Thus, specialists planning interventions in this region need to be aware and have knowledge of atypical aortic branching patterns. Higher prevalence rates of AA branching patterns compared to previous studies were identified in the Turkish population in this study and therefore, a comprehensive, multicenter study is needed to determine the cause of this differential finding.

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