SOFT-TISSUE AND DENTOSKELETAL PROFILE CHANGES ASSOCIATED WITH MAXILLARY EXPANSION AND PROTRACTION HEADGEAR TREATMENT

One of the goals of early treatment of Class III malocclusion with max illary expansion and protraction headgear is to significantly improve the dentofacial profile. The objectives of the present study were to d etermine (1) the interrelationships of the soft tissue and dentoskelet al profiles after maxillary expansion and protraction headgear treatme nt and (2) which cephalometric variables could contribute to an accura te prediction of the protraction effect on the soft tissue profile. La teral cephalometric radiographs of 20 consecutively treated Class III patients (10 males, 10 females) by protraction headgear were included in this study. Their ages at the start of protraction headgear treatme nt ranged from 6 to 11 years, with an average of 8.1 +/- 2.1 years. No ne of the patients had previous orthodontic treatment. For each patien t, the first lateral cephalogram was taken 6 months before the initiat ion of headgear treatment (T-0), and the second radiograph at the star t of treatment (T-1). Therefore (T-1 - T-0) represented 6 months of gr owth with no treatment. A third radiograph was taken 6 months after st art of treatment (T-2). In this way, (T-2 - T-1) - (T-1 - T-0) represe nted the effect the result of appliance therapy alone and each subject served as his/her own control. A computerized cephalometric analysis was used including variables assessing sagittal and vertical relations hips of skeletal and soft tissue profiles, incisal relationships, soft tissue thickness, and lip structure. Data were analyzed by means of p aired t tests, Pearson's product-moment coefficient correlation, and m ultiple regression analyses. The results showed significant improvemen ts in dentofacial profile after 6 months of maxillary protraction. The skeletal and soft tissue facial profiles were straightened and the po sture of the lips was improved. The normal incisal relationship (overj et) that was achieved had a significant impact on the soft tissues ove rlying both upper and lower incisors resulting in better lip competenc e and posture. Significant correlations were found between changes in the sagittal relationships of skeletal and soft tissue profiles in bot h the maxilla and the mandible (p < 0.05). The forward movement of the maxilla was accompanied by a corresponding forward movement of the so ft tissue profile at 50% to 79% of the hard tissue. In the mandible, t he downward and backward movements of the soft tissues were equivalent to 71% to 81% of the corresponding hard tissues. The lack of high r s quare values in the multiple regression analyses reflected a low predi ction value for the maxillary variables, but moderately high predictio n value for the mandibular variables that could be used in preorthoped ic treatment planning. This study showed that significant dentoskeleta l changes and improvements in dentofacial profile resulted from 6 mont hs of treatment with maxillary expansion and protraction.