Background: One frequent late sequel of frontal crowding is the development of gingival recessions manifesting themselves especially at rotated anterior teeth.
Material: This correlation is discussed with regard to the literature and to the authors' own clinical findings and experimental studies.
Results: According to present-day knowledge the following statements can be made: In cases with frontal crowding the tangential stiffening of the anterior teeth is inadequate. Thus translatory and rotational force components resulting from the elastic deformation of the mandible under functional loading effect the movement of rotated front teeth during maximum jaw opening and mandibular protrusion. Also tongue thrusting and frontolateral bruxism lead to force vectors in vestibular direction affecting the delicate periodontal tissues. These statements are confirmed by the authors' own in-vivo experimental studies measuring the amount of tooth displacement during test persons' functional movements. Furthermore, in the long-term anterior crowding will mostly trigger incorrect anterior guidance, i.e. guidance predominantly by the rotated or ectopically positioned front tooth with subsequent overloading of the antagonist.
Conclusion: Orthodontic therapy of frontal crowding is not just an esthetic problem but can be of special importance in the prevention of stress-related reactions in the masticatory system.