Functional regulator therapy in treatment of skeletal open-bite.

A study was performed on the functional regulator, Fränkel appliance (FR4) in order to test its efficiency in the treatment of patients with skeletal open-bite. Pretreatment and post-treatment cephalometric evaluation was done on 11 patients and 10 untreated patients with skeletal open-bite. The results showed that the FR4 appliance was mainly effective on changes in dentoalveolar structures and produced no significant skeletal changes. The degree of anterior open-bite was decreased significantly in the treatment group in comparison with the controls (p < 0.01), due to vertical eruption of upper and lower incisors and retraction of maxillary incisors.