Three-dimensional CBCT Analysis of Root Volume Changes Following Tooth-bone and Bone-borne Maxillary Expansion: A Pilot Study.

four or two miniscrews insertions using computer-guided minimally-invasive and flapless approach

In the TB group, the tooth-borne hyrax appliance was designed with bands on the maxillary first molars; in the BB4 group, the bone-borne expander was supported by 4 miniscrews inserted both in paramedian and parapalatal position of the palatal vault; in the BB2 group, the bone-borne expander was supported by 2 miniscrews inserted in the paramedian region of the palate. The same type of expansion screw and expansion protocol were used in all groups. Specifically, a 10mm hyrax click screw (Dentaurum, Bologna, Italy) was activated by 4 quarter-turns on the first day and by 3 quarter-turns per day during the active phase of treatment (0.20mm per turn, 0.6mm daily) until an 8mm screw opening was achieved.

"All patients underwent CBCT examinations before the application of the RME device (T0) and post-treatment, after the 6-month retention period (T1). The exposure settings were as follows: 10 mA, 90 kV, total scanning time of 15.0 seconds, effective radiation time of 4.0 seconds, voxel size of 0.2 mm, scanning area of 14 x 16.5 cm, and an effective radiation dose of approximately 524 mGy/cm2.~The CBCT images analyzed in this study were not acquired specifically for this research but were part of an ongoing prospective randomized clinical trial aimed at evaluating the skeletal and dentoalveolar effects of three different orthodontic devices. The imaging protocol was established in accordance with ethical guidelines and was approved by the relevant institutional review board."