CBCT acquisition
teeth bite
CBCT images were taken with i-CAT (Imaging Sciences International, Hatfield, PA, USA) at 120kVp, 18.45mAs, 20-second acquisition time, and 16 × 13 cm field of view. The effective radiation dose was 69–87µSv. Each patient was instructed to hold still, maintain her or his head upright and fixed by a headrest, with the teeth bite together in a standing position. The CBCTs were exported in Digital Imaging Communication in Medicine (DICOM) format for analysis.