In young adults fixed functional appliances are a treatment alternative to extraction therapy but to a lesser extent to orthognathic surgery. Because of their limited skeletal effects and minor changes in the profile they are indicated only in patients with a moderately severe Class II malocclusion. Pre-treatment proclined mandibular incisors limit the scope of indications for fixed functional appliances, as they can cause an increase in lower incisor proclination. Significant reductions in profile convexity are achievable only by combined orthodontic and surgical treatment of the malocclusion. When performing camouflage orthodontics in conjunction with maxillary premolar extractions in adults, an increase in the nasolabial angle, which is often esthetically undesirable, has to be discussed as a potential side effect and has to be taken into account when considering the different therapeutic approaches.

Only slight skeletal sagittal effects, which were independent of age, were observed as a result of treatment with fixed functional orthodontic appliances. The younger the patients, the greater any growth-inhibiting effect on the maxilla will be. There is a greater increase in facial height during treatment than would have been expected from growth without any such influence. The compensatory dental effects increase with patient age.

Treatment leads to overjet and molar relationship correction that is mainly caused by significant dentoalveolar changes.

Despite proven differences in skeletal and dental treatment effects, the facial profile has not to be taken into consideration when choosing between FMA and Herbst appliance for class II treatment.