It is generally thought that the teeth rest in a balance position between the soft tissues, which are the lips and cheeks on the outside and the tongue on the inside. Ideally the tongue should rest on the roof of the mouth with lips resting together and the teeth in or near contact. If someones teeth are not well aligned then something has gone wrong with this system. And conversely if upper and lower jaw bones are in the correct position and adequate space has been gained for the tongue to rest and function correctly, the soft tissues should be able to align the teeth. Just in the same way that ancestors from the dawn of time and all the other 5,400 species of mammals manage to achieve near perfect dental alignment without any assistance. Orthotropic therapy aims to achieve the first of these and various methods of Myofunctional therapy or oral myology, with or without appliance, aim to achieve the alignment of the teeth.
The types of therapy vary with the providers. This ranges from individual therapist who provide therapy to companies like MRC (the Myofunctional Research Company) who provide a complete solution and appliances to assist or direct the training.