Background and Aim. This study aimed to assess the effect of the size of the field of view (FOV) on cone-beam computed tomography (CBCT) artifacts caused by metal objects in the exomass. Materials and Methods. In this in vitro experimental study, titanium implants, teeth with cobalt-chromium (Co-Cr) intracanal posts, and teeth with mesio-occluso-distal (MOD) amalgam restorations were placed in an empty socket of the extracted third molar of a human mandible. These metallic materials were differently arranged in the exomass (zone outside of the FOV). A polypropylene tube containing dipotassium phosphate was placed in the empty socket of the right canine tooth in a dry human mandible. CBCT scans were taken with a NewTom VGI (Verona, Italy) scanner using a 6 × 6 cm and an 8 × 8 cm FOV. The histogram tool of OnDemand software (Cybermed, Seoul, Korea) was used to select circles with a 1.5 mm diameter as the (ROI) at the center of the homogenous solution of dipotassium phosphate tube on the axial plane. The mean gray value (GV) and its standard deviation (SD) in the region of interest (ROI) were calculated ( P > 0.05 ). The data were analyzed by SPSS 26. Results. The reduction in the size of the FOV significantly decreased the mean GV ( P < 0.001 ). Metal objects in the exomass significantly decreased the mean GV ( P < 0.001 ), and minimum mean GV and maximum SD were recorded for amalgam, followed by Co-Cr intracanal posts, and titanium implants. The unilateral presence of a metal object was associated with a higher mean GV and lower SD ( P < 0.001 ). Conclusion. Using a smaller FOV increases the size of the exomass, which may negatively affect the image quality. Metal objects in the exomass decrease the GV of CBCT scans and adversely affect the image quality.

Background: Determining the exact location of mandibular foramen is an important factor prior to Inferior Alveolar Nerve (IAN) block injection. The aim of this study is to assess the position of Mandibular Foramen (MF) and its variations using Cone-Beam Computed Tomography (CBCT). Methods: This study was conducted on CBCT images of 80 females and 80 males (18 to 68 years). The distance between the MF and the anterior border of ramus (A), inferior border of mandible (B), superior border of mandible (C), and occlusal plane was measured. Data were analyzed by the student t-test, bivariate correlation analysis, paired sample t-test, and Pearson’s correlation coefficient. Results: The mean amount of A, B and C distances, and the mean distance from the occlusal plane to the center of MF were 13.76, 24.24, 12.32, and 7.59 mm, respectively, with no significant difference between the right and left sides (p>0.05). The mean B and C distances were significantly smaller in females than males (p<0.05). The mean size of the measured angle was 43.2°. Significant correlations were noted between aging and decreased A distance, and reduction in the angle between the contralateral premolars and MF (p<0.05). Conclusion: Knowledge about the position of MF can enhance the surgical procedures in this region. Using a 21-25 mm needle would be associated with lower risk of needle fracture during IAN block injection. Also, needle insertion angle <45-degrees is optimal for the samples assessed in this study.

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Objectives: Dental implant is a commonly used treatment modality for replacement of the missing teeth. The aim of the present study was to evaluate a number of bone-related factors at the implant site preoperatively by conebeam computed tomography (CBCT). Materials and Methods:A total of 400 implant sites were evaluated on CBCT images. The height, width, angle of residual ridge, thickness of cortical bone crest, and the ridge concavity were evaluated on cross sectional images at four regions: the anterior maxilla, anterior mandible, posterior maxilla, and posterior mandible. Results:The highest thickness of cortical bone was observed in posterior mandible followed by anterior mandible, anterior maxilla, and posterior maxilla. In the mandible, the mean buccal concavity was higher in the anterior than in the posterior region (P = 0.0094). The measurements indicated that in both the maxilla (P = 0.0256) and mandible (P < 0.0001), the residual ridge width was lower in the anterior than in the posterior region; while the height of the residual ridge was higher in the anterior than in the posterior region in the mandible (P < 0.0001). In the maxilla, the remaining ridge angle in the anterior region was greater than that in the posterior region (P < 0.0001). Conclusion:Anatomical variations detected on CBCT results in personalized treatment planning considering best site and the best fixture in terms of size and position prior to implant fixture insertion.