Morphologic changes in the transverse dimension using the Fränkel appliance.

Anthropologic studies have shown that the incidence of malocclusion increases as societies become urbanized. Crowding seems to be one of the most common findings. Possible explanations for this have been heredity, dietary changes, poor eruption patterns, and mouth breathing, among others. Many clinicians begin treatment early in order to minimize this maldevelopment. Various early-treatment approaches have included serial extraction, lingual holding arches, palatal expansion, functional appliances, partial fixed appliances, and headgear. Expansion with the functional regulator offers one solution to crowding. If this expansion can be shown to be significant in amount and stable, then the Fränkel appliance merits consideration regardless of the clinician's choice of fixed appliances. Fifty patients treated with the Fränkel appliance from the private practice of the author were analyzed to evaluate changes in the transverse dimension. The ages ranged from 5.9 to 13.8 years, with the average age 9.6 years (+/- 1.54). Twenty-nine patients were girls and twenty-one were boys. The Angle molar relationships were distributed as follows: Class I-21 patients; Class II-27 patients; and Class III-2 patients. All patients were Caucasians and were selected for treatment on the basis of the presence of crowding, excessive overjet or overbite, or excessive open-bite. The presence of crowding was determined by a study model and Panorex analysis. All patients reported in this study were considered cooperative and wore their appliances for approximately 20 hours per day. Five cephalometric measurements were taken: nasal cavity width, maxillary width, mandibular width, intercanine width, and intermolar width. All cephalograms were originally traced by the same technician at Rocky Mountain Data Systems, Inc. When there was a discrepancy between the RMDS tracing and the author's tracing, the author's tracing was used. Data to serve as controls were provided by Rocky Mountain Data Systems, Inc. The sample is based on forty children measured over a 5-year period between the ages of 8 and 13 years. Twenty patients had an Angle Class I molar relationship, and twenty patients had an Angle Class II molar relationship. Two Student's t statistics were used to evaluate these measurements. Means, standard deviations, and standard errors are shown. The Bonferroni inequality method is used to determine if these five measurements are significant, and all five measurements were simultaneously significant at the 0.05 level. From the statistical results as well as the cephalometric descriptive analyses, it appears that the Fränkel appliance precipitates a limited but potentially significant increase in arch length which will benefit the patient if the results are stable.