The Prevalence and Anatomical Variations of Bifid Mandibular Canal in the Egyptian Population Using Cone Beam CT (CBCT)
Condition: The Prevalence of Bifid Mandibular Canal
Study type: Observational

Summary: 
      The prevalence of bifid mandibular canal will be detected in a sample of Egyptian
      Population.Anatomical variations of the bifid canal will also be detected.
    

Detailed description: 
      Settings:

      The data collection will be obtained from the data base available at the department of Oral
      and Maxillofacial Radiology, Faculty of Dentistry, Cairo University. CBCT images will be
      obtained from Egyptian patients who were referred to the CBCT unit in oral and maxillofacial
      radiology department for different purposes.

      Variables:

      •Prevalence of bifid canals - Classification and prevalence of observed types - Distance from
      the involved teeth

      Data Sources / Measurements:

        -  Retrospective Data Analysis will be performed after the CBCT images are pooled from the
           computer database.

        -  Exposure parameters of the scans will vary depending on patients' sizes (according to
           the manufacturer's recommendations).

        -  Both images with 0.2 and 0.4 voxel sizes will be reviewed.

        -  For proper visualization of the mandibular canal, the reference lines will be rotated,
           so that it lies perpendicular to the mandibular foramen on the axial cuts. Then,
           scrolling through the corrected sagittal cuts will be performed to review the clearest
           cut of the full course of the mandibular canal. Moreover, corrected coronal cuts will be
           reviewed, to determine the exits of the accessory branches (buccal or lingual) if
           present.

        -  CBCT images will be interpreted by two oral and maxillofacial radiologists (with
           different experiences) independently; blinded from demographic data of the patients and
           from the results of each other.

        -  The classification of Naitoh et al 2009 will be followed for the categorization of the
           accessory branches:

             1. Forward canal: emerging from the superior wall of the main canal.

             2. Bucco-lingual canal: emerging from the buccal or the lingual wall of the main
                canal.

             3. Dental canal: the end of the bifid canal is at the root apex of the molars.

             4. Retromolar canal: emerging from the main canal, opening at the retromolar foramen
                in the retromolar area.

        -  Each radiologist will evaluate the images for presence of bifid canal twice with a time
           lag of two weeks between the two reading sessions. If present, its configuration
           (classification) will be registered. Any disagreement will be solved by consensus
           between the two observers.

        -  If adherence or closeness of the canals to the teeth is detected, then the distance
           between the canal and the involved tooth will be measured using built in measuring tool
           in the software.

        -  The measurements will be carried out by one observer (EE) and will be repeated 2 weeks
           later for intra-observer reliability assessment.

      Bias

      No source of bias.

      Study Size:

      The aim of the study is to assess the prevalence of bifid mandibular canal in Egyptian
      population. Based on the previous paper by Afsa and Rahmati 2017, the prevalence of bifid
      mandibular canal was 31% Using a precision of 5, a design effect set at 1 with 95% CI
      (confidence interval), a total sample size of 329 hemimandibles will be sufficient. The
      sample size was calculated by Epi info 7 software.

      Quantitative Variables:

      Quantitative data: The distance between the canal and involved teeth and will be reported as
      mean and standard deviation.

      Statistical methods:

      Data will be analyzed using SPSS® v. 15 (SPSS Inc., Chicago, IL) software program. Pearson
      Chi square and t-tests was performed for statistical analysis among gender, localization and
      measurements. Categorical data will be described as numbers and percentages. A p value of
      <0.05 will be considered statistically significant.
    

Observational model: Other
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        Egyptian population
      
Keywords: Mandibular canals; bifid canal; cbct; cbct dental.