[Anterior tooth intrusion with the base arch: preactivation by tip-back bending or curvature?].

Burstone's intrusion mechanics has been found to be effective in the treatment of a deep bite due to intrusion of the anterior teeth. The pre-activation of the intrusion arch by a tip-back bending shows a shortening in the activation. Measurements objectified the extent of the shortening and the resulting horizontal forces for TMA arches of a dimension of 0.017 x 0.025 inch relating to different distances between molars and anterior teeth and pre-activation by means of tip-back bending or curvature. The change of the vertical force in connection with a simulated intrusion of 5 mm was also registered. Clinical consequences of the therapy are discussed.