Effect of different incisor movements on the soft tissue profile measured in reference to a rough-surfaced palatal implant

Introduction: The aim of this study was to evaluate soft tissue profile changes after a wide range of incisor movements in the anterior and posterior directions in nongrowing patients. Identifying baseline values more prone to substantial soft tissue profile changes was of high interest. Methods: For this retrospective study, 47 pairs of lateral cephalograms of nongrowing white patients were superimposed. The cephalograms were taken with the same palatal implant in situ before and after treatment. To increase the accuracy of the measurements, the palatal implants were used as stable reference structures in close relation to the incisors. Results: Horizontal changes of the most anterior point of the maxillary incisor showed a significant correlation to horizontal changes of the upper and lower lips (P < 0.001). For every millimeter of horizontal change of the most anterior point of the maxillary central incisor, a change of 0.59 mm at labrale superior can be expected. Also, the angulations of the upper and lower lips were significantly correlated to the most anterior point of the maxillary incisor. Lip retraction was less pronounced in patients with initially thicker lips than in those with thinner lips. Conclusions: The major contributing factors for predicting the soft tissue profile change during orthodontic treatment are the amount of horizontal movement of the most anterior point of the maxillary incisor, the amount of bite opening, and the initial lip thickness. Although there are significant correlations between dental movements and soft tissue changes in larger samples, predictions for individuals may be inconsistent.