Objectives: This study assessed the effect of voltage and amperage alterations in cone-beam computed tomography (CBCT) on metal artifact generation in the exomass. Materials and Methods: In this in vitro experimental study, titanium dental implants and teeth with cobalt-chromium (Co-Cr) intracanal post, and amalgam build-up restorations were placed in the exomass in a dry human mandible unilaterally and bilaterally. Ballistic gelatin was used for soft tissue simulation. The mandible was scanned by CS8100 3D-Carestream CBCT scanner with 5 x 5 cm field of view (FOV), 60 and 90 kVp voltage, and 2 and 10 mA amperage. The mean gray value (GV) in the region of interest (ROI) at the center of a polypropylene tube containing dipotassium phosphate was calculated on 10 axial sections using OnDemand software. The mean GV and its standard deviation (SD) represented the amount of generated artifacts. Data were analyzed by R software. Results: Increasing the amperage increased the mean GV and decreased its SD (P<0.05). Increasing the voltage decreased the mean GV and its SD (P<0.05). Metal objects in the exomass significantly decreased the mean GV such that the lowest mean GV and the highest SD was recorded in presence of Co-Cr post followed by titanium implant, and amalgam build-up (P<0.05). Unilateral presence of metal objects had a significantly smaller effect on the mean GV and its SD (P<0.05). Conclusion: Increasing the amperage and voltage decreased metal artifact generation in the exomass. Metal artifacts in the exomass can affect the GV and cause image distortion.

IntroductionDetection of exact location of greater palatine foramen and its anatomical variations are vital prior to posterior maxillary surgeries and gingival grafts. The aim of this study is to determine the anatomical position and size of the greater palatine canal (GPC) and foramen (GPF) using cone beam computed tomography (CBCT) scans.Materials and methodsIn this descriptive-analytic study, CBCT images of 148 patients were assessed. To determine the anatomical foramen position, the posterior maxilla area was divided into five regions on the axial view (A: from the mesial surface of the second molar to the center of the second molar, B: from the center of the second molar to its distal, C: from the mesial surface of the third molar to the center of the third molar, D: from the center of the third molar to the distal of the third molar, E: distal to the third molar.). The length of the canal was investigated on both coronal and sagittal views. Independent and paired T-test were used to analyze the data.ResultsAmong 80 females -68 males, the anatomical position of the GPF was mainly located in region E on the left (55%) and the right (50%), and then, respectively, in region D and region C. The mean diameter of GPF was 4/48 mm on the left and 4/63 mm on the right side (P-value = 0/01). The average length of the canal on the coronal view was 29.46 mm on the left side and 29.75 mm on the right (P-Value = 0/005). The average length of the canal on the sagittal view was 29.62 mm on the left and 30.02 mm on the right (P-value = 0/001).ConclusionThe anatomical position of the GPF was primarily located distal to the third maxillary molar. CBCT is a valuable diagnostic tool for evaluation of vital anatomic landmarks in the maxillofacial region prior to surgeries and interventions.