الفهرس 
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Abstract
Summary and Conclusion
Summary
Surgical interventions in the anterior region of the human mandible are associated with many complications. Some anatomical structures like the lingual mandibular canals were discovered in cadaver studies. Such canals may be of great concern that requires cautiousness during mandibular rehabilitation surgeries. This retrospective study was designed to evaluate the presence, the location and the dimensions of the lingual mandibular canal (LMC) in an Egyptian subpopulation by the use of cone beam computed tomography (CBCT).
Three hundred (300) CBCT scans of patients seeking dental treatment (implant, orthognathic surgery, root canal treatment, surgery for removal of impacted third molar, etc.) from the year 2015 to 2019 were included in the study. These scans were collected from two demographic areas in Arab Republic of Egypt, The scans that show pathological condition or edentulous space in the area of interest were excluded. Scans incorporated in the study were performed using i-CAT Next Generation machine, with the following scanning parameters; Tube voltage of 120 kvp, tube Current of 5 mA and 26.9 seconds scanning time. All the patients’ data were anonymous and only the gender and age were known, images were supplied as DICOM files and analyzed by means of On-Demand 3D Cybermed Inc (OnDemand3DApp 1.0.10.7510) software program and the lingual mandibular canals were classified according to their anatomical location in the mandible into median (MLC) and lateral (LLC) lingual canals.
The following measurements were performed on the canals with a diameter of more than 1mm; the diameter of the opening of the canal, the diameter of the end of the lingual canal, the length of the canal, the distance between the end of the canal and the buccal cortical plate, distance from the opening of the lingual foramen to the alveolar crest, distance from the end of lingual foramen to the alveolar crest, distance from the opening of the lingual canal to the inferior border of the mandible, and the distance from the end of the canal to the inferior border of the mandible.
The prevalence of the lingual mandibular canals was (99.0%) for both the median and lateral canals in the total sample, with (98.67%) for the median lingual canal, and (54.67%) for the lateral lingual canals. The prevalence of the median lingual canal in the male scans was higher than the females with a percentage of (100.0%). Also, in the lateral lingual canals, the prevalence was higher in the male scans with a percentage of (56.2%). The majority of the (MLCs) were found above the genial tubercle (supra-spinosum) with a percentage of (94.33%) in the total sample with (91.8%) in the females and (93.4%) in the males. The percentage of the (MLCs) with a diameter larger than 1mm was (28.0%) in the total sample, with (30.73%) in the females and (24.0%) in the males. The mean diameter of the (MLC) opening was (1.68± 1.27mm), and the mean diameter of the end was (0.39 ± 0.17mm). All the measurements of the (MLCs) showed no statistically significant difference between the males and females except for the length from the canal opening to the alveolar crest. The lateral lingual canals (LLCs) showed the majority of the canals located in the premolar region with a percentage of (34.33%) in the total sample, (26.26%) in the females, and (46.3%) in the males. The percentage of the (LLCs) with a diameter larger than 1mm was (1.67%) in the total sample, with (2.23%) in the females and (0.83%) in the males. The mean diameter of the (LLCs) opening was (1.25± 0.14mm), and the mean diameter of the end was (0.52 ± 0.35mm). No comparison could be established between the females and males regarding the (LLCs) due the small sample size of the male group (n=1).
Conclusion
from the current study the following conclusions were drawn:
1. The CBCT was proven to be very accurate in detection of the lingual mandibular canals, as the examined Egyptian sub-population, showed variability in the (MLC) and (LLC) anatomy, increasing the risk of life-threatening situations. The prevalence of the (MLC) was (98.67%) and the supra-spinosum canals were more frequent than the infra-spinosum canals so, thorough analysis should be carried out during surgical planning in the anterior region of the mandible by the use of CBCT scan.
2. Special consideration should be given to the female patients before surgeries in the anterior region, where a close relation of the (MLC) to the alveolar crest was found within the study.
3. Prevalence of the (LLC) in the premolar region was high.
4. The canal opening in the male sample showed a close proximity to the inferior border of the mandible that might increase the tendency of bleeding during orthognathic surgery in the anterior mandible.