Fig. 1From: A quantitative three-dimensional comparative study of alveolar bone changes and apical root resorption between clear aligners and fixed orthodontic appliancesReference lines and measurements in sagittal view for upper central incisor. ABT: alveolar bone thickness, LBH: labial bone height, PBH: palatal bone height, UI-PP: upper incisor to the palatal plane angle.Back to article page