Functional orthodontics (FKO) is an orthodontic treatment concept that aims to functionally stimulate the soft and hard tissues of the masticatory system through the use of appliances that are inherently passive in the oral cavity, so that they change their muscular functional patterns and respond with adaptation and growth.
The theoretical approach is to view the craniomandibular system (CMS; stomatognathic system) as a functional unit of hard tissues such as the cranial, cervical, and maxillary bones and the soft tissues attached to them such as the shoulder, lip, cheek, and tongue muscles.
Indications (areas of application)
While active orthodontic appliances act specifically on teeth and bone structures, functional orthodontic appliances (FKO appliances) lie almost passively and without pressure in the mouth and act without exerting force themselves: Every time the jaw closes, e.g. when swallowing, an FKO appliance steers the lower jaw into the desired final bite position via the movement of the lower jaw by means of its design, which is adapted to the anomaly to be corrected in each case, and at the same time retrains the musculature involved. By changing the muscular functional pattern, the functional balance targeted by the treatment is stabilized in a natural way. Holding off the soft tissues of the lips, cheeks and tongue causes traction on the underlying periosteum (bone skin), thereby providing growth stimuli in the bone.
The procedures
The elimination of muscular dysfunction and promotion of structures conducive to natural dentition development is not tied to a specific FKO appliance; rather, a variety of modifications exist to the first appliance, the so-called activator, which dates back to Andresen and Häupl. Essentially, FKO appliances can be divided into three groups. What they all have in common is that they serve as “gymnastics devices” for CMS:
- Bimaxillary appliances: the maxilla and mandible are grasped by a single appliance. One example among many is the activator according to Andresen and Häupl, the function regulator according to Fränkel, and the bionator according to Baltors;
- Double plate systems: they influence the movements and position of the mandible as well as the tongue by means of special advancing or retracting elements; as an example, the double advancing plate (DVP);
- Devices based on the principle of the oral vestibular plate: they keep lip and cheek muscles away from the teeth and tooth-bearing bone structures, provide growth stimuli by stretching and prevent muscular permanent pressure on the hard tissues. Ultimately, the muscular functional pattern is restructured. Soft tissues, which can inhibit healthy dentition development, are thus themselves inhibited in their function.
Crucial to the success of the therapy is the cooperation of the young patient, but also the motivating support of parents, because a FKO device must be worn 16 hours a day. Especially in the difficult initial period of therapy, when the patient is struggling with strong salivation and speech problems, all are required. It is highly recommended to keep a wearing chart, with which the patient himself can control his wearing behavior. If acceptance is not sufficient, alternative treatments must be sought.
