A three-dimensional method for evaluating changes in lip morphology following correction of functional anterior crossbite

Abstract Purpose The purpose of the present study was to present a three-dimensional method for evaluating changes in lip morphology and to apply the method to the therapy evaluation following the correction of functional anterior crossbite. Materials and methods Twenty-five Japanese patients (age: 6 years and 10 months to 10 years and 9 months) with anterior crossbite and premature contact of at least one central incisor were included. Anterior crossbite was treated with labial movement of the upper anterior teeth using a fixed or removable appliance. Treatment was completed within 6 months. The 3D morphology of the facial soft tissue was recorded using a 3D surface imaging device before and immediately after correction of anterior crossbite. The differences in lip morphology variables were statistically analyzed. Results At post-treatment, the upper lip was positioned anteriorly and was proclined on the mid-sagittal plane, and anteriorly and superiorly on the plane apart from the midline. The lower lip was positioned posteriorly not only on the mid-sagittal plane but also on the plane apart from the midline. The lower lip was retroclined on the mid-sagittal plane. The submental region was positioned posteriorly and inferiorly. Conclusions Post-treatment imaging showed forward movement of the upper lip, backward movement of the lower lip, and backward rotation of the soft tissue in the submental region. The three-dimensional method described in the present study improves the evaluation of facial morphology and provides insight into the changes in the lip morphology of preadolescent patients.