The smile: a challenge in the treatment of class III

Abstract

The smile poses a challenge in the treatment of class III. Untreated, the class III patient presents excessive maxillary torque and a predominant display of the mandibular incisors, a sign that becomes more visible with age. Functional orthopedics restores the aesthetic appearance of the smile by maxillary protraction (sometimes temporarily because 20% of cases will still need surgery). Depending on the initial severity of the case (-4.5 mm AoBo would be the threshold value), the options are compensation or surgical correction. In both cases, the profile is improved but without normalising the cephalometric values. In recent years, the number of published cases treated by compensations (often using skeletal anchorage) has multiplied with broader indications, particularly for Asian patients in whom Le Fort I surgery gives questionable aesthetic results. Attention must be focused on the occlusal plane rotation which alters the smile by displaying the mandibular incisors. Nevertheless, surgery can handle the most severe cases with a greater degree of improvement. The aim of this article is to determine the cephalometric cut-off values for an acceptable smile in Class III patients. We performed a search on Pubmed using the following keywords: Class III, anterior cross bite, smile, camouflage, orthognathic surgery; then secondarily, using references supplied by the articles found. We then analysed the data. The ortho-surgical protocol associated with extractions of maxillary first premolars appears to be the way to obtain the best results in terms of the smile (versus surgery without extractions and versus orthodontic compensations) because it is, in fact, the only way to restore the normal position and torque of the maxillary incisors, thus increasing their display during smiling.