Biomechanics of the dental arch and incisal crowding.

During horizontal contact, the dental arch represents a link chain in which two convex articular surfaces are in contact and are tensioned by the dentogingival and dentoalveolar fibrous tissue. Joints composed of convex-convex surfaces are equivalent to stretched dimeric link chains whose links are in a mechanically unstable position under compression. Experiments on plaster models show that the dimensional stability of an articulated (dental) arch is considerably increased when a concave and a convex articular surface are in contact, as these joints are equivalent to an overlapping dimeric link chain whose links are in a mechanically stable position when under compression. In the abraded denture of Stone Age man, horizontal interdental contacts of transversally concave-convex dental surfaces may be found extending even into the incisal region. Increased stability of the dental arch and reduced problems of incisal crowding are to be expected if an overlapping dimeric chain is produced morphologically in each horizontal contact by means of slight interproximal enamel reduction.