Maxilläres Advancement und Veränderung des perinasalen Weichgewebes. Eine retrospektive Studie mittels dentaler Volumentomographie.

The nose plays a vital role in the aesthetics of the human face, as a central reference point. The present study investigated the effects on changes in nasal width of maxillary advancement carried out during surgical correction of skeletal Class III anomalies with maxillary retrognathia. The changes were not assessed using photos or direct measurement methods on the patient, as has previously been customary in most cases. Instead, measurement and analysis were carried out using data from three-dimensional cone-beam computed tomography (CBCT) images taken during therapeutic and surgical planning. Following processing, preoperative and postoperative radiographic models were compared directly with computer assistance. The digitally calculated surgical advancement distance on the sagittal plane was analyzed statistically in relation to the changing width of the nose. It was found that the width of the nose increases both at the alar base and also in terms of the interalar distance. On the basis of the results, tables were developed to show percentile values for increases in the width of the alar base and in the interalar distance relative to the advancement distance. The study provided positive findings on the following questions: 1. Are associations observed between hard-tissue andsoft-tissue repositioning after maxillary advancement? It is clearly evident that surgical movement of the bone under the facial skin always affects the soft tissue overlying the bone as well. 2. Does the transverse extent of the external nose increase depending on the sagittal maxillary advancement distance? The transverse extent of the nose increases both in relation to the alar base and also in relation to the interalar distance. This was the case in all of the patients investigated in this study. Tables were developed to show percentile values for increases in the alar base and in the interalar distance relative to the advancement distance. The tables give various percentile values for changes in the width of the alar base and changes in the interalar distance, relative to maxillary advancement distances of 1– 10 mm. 3. Are the values obtained comparable with research results in Asian patients? There have been varying reports from Asian countries in the past regarding the increase in nasal width resulting from maxillary advancement. In view of the scientifically confirmed interethnic difference in nasal mor- phology, however, direct comparison does not appear useful. Due to the extreme scarcity of data, no reliable conclusions can be drawn regarding the ratio between advancement and the resulting effect. 4. Is the method used suitable for metric analysis? The method is suitable for measuring both linear distances and also angles.