General types and application range
There are 4 different original types of the Functional Regulator according to Fraenkel. The labeling occurs in Arabic numbers.
The Functional Regulators according to Fraenkel FR-1 and FR-2 are used to correct a retraction of the lower jaw with an enhanced overjet (Angle class II/1). The FR-3 is used to correct anomalies of the mandibular protrusion particularly combined with an underdevelopment of the upper jaw. The former application range of the FR-4 – the therapy of a skeletal hyper-divergency associated with an anterior open bite – will be corrected nowadays with a modified FR-1.
Functional Regulator according to Fraenkel Type FR-2