Facial soft tissue changes after transverse palatal distraction in adult patients.

This longitudinal study investigated the 3-D facial soft-tissue response to transverse palatal bone-anchored osteodistraction in 18 adult patients. Laser-scanned facial surface data were obtained for all patients before (T(0)), 6 months (T(1)) and 1 year (T(2)) after transverse palatal distraction. The averaged facial morphologies at T(0), T(1) and T(2) were calculated and compared. Sagittal and vertical measurements were obtained from lateral cephalograms to evaluate skeletal and dental movements. Pre- and immediate post-distraction dental casts were used to investigate transverse maxillary movements. Cutaneous changes were mainly observed in the paranasal regions and cheeks, in the range 1-3mm, reflecting the underlying increase in the maxillary width. A significant enlargement of the nasal base was also demonstrated. The absolute magnitude of these facial changes was limited but clinically relevant. Variable skeletal movements were observed. These were of low magnitude and no systematic tendency could be demonstrated statistically. Significant changes were documented only with regard to orthodontic repositioning of the upper and lower incisors. The mean transverse increases in the maxillary dental arch were 6.7mm at the intercanine, 6.8mm at the interpremolar, and 6.1mm at the intermolar levels.