Samareh Mortazavi - Oral & Maxillofacial Diseases Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.

Background: Since Cone-Beam Computed Tomography (CBCT) software programs allow the determination of slice thickness, this study was designed to evaluate the effect of different slice thicknesses on the accuracy of linear measurements in CBCT. Method: In this cross-sectional study, ۷ human skulls of unknown age and sex were selected. Vertical and buccolingual dimensions were measured in the anterior, middle and posterior regions of the right and left sides of the maxilla and mandible. Measurements were repeated at different slice thicknesses (۱-, ۲-, ۳-, ۴-, and ۵-mm) in each area and compared. repeated measures ANOVA and Friedman tests were used as statistical methods. Results: In all areas except the anterior maxilla, smaller slice thicknesses (۱- and ۲- mm) were associated with the lowest buccolingual dimensions, while larger slice thicknesses (۵-mm) were associated with the highest buccolingual dimensions.  For most areas, larger slice thicknesses (۴- and ۵-mm) resulted in the lowest vertical dimension, whereas smaller slice thicknesses (۱- and ۲- mm) provided the highest vertical dimension.  The most accurate dimensions were obtained using the ۱- and ۲- mm slice thickness. The observed differences between slice thicknesses in horizontal measurements (buccolingual dimension) were mostly significant, but not in vertical measurements. Conclusion: The difference in vertical and buccolingual dimensions when changing slice thickness from ۱ to ۵ mm using the Planmeca CBCT device is estimated to be less than ۰.۵ mm.  This difference is clinically insignificant, meaning that the change in slice thickness does not affect the clinical accuracy of linear measurements in the maxillary or mandibular region.

Cone-Beam Computed Tomography, slice thickness, accuracy, linear measurement.