Study of the extent of torque, protrusion and intrusion of the incisors in the context of Class II, division 2 treatment in adults.

Abstract

The aim of this study was to analyze the relative contribution of torque and protrusion to the change in incisor inclination in the treatment of Class II, Division 2 malocclusion with fixed appliances. Furthermore, the extent of incisor intrusion was to be evaluated. The second part of the study was aimed at documenting the stability of the therapeutic outcome in terms of inclination and intrusion within the framework of a follow-up examination. The study sample comprised 25 adult patients, and the follow-up sample eleven patients. The intrusion and change in inclination of the incisors as well as their stability were analyzed by evaluating and superimposing lateral cephalograms taken before and after treatment as well as after retention. Although the mean value of inclination at the end of the therapy was in accordance with the standard value (102 degrees), there was a marked interindividual variation. In the maxilla, the mean torque component was 58%, and the mean protrusion component 42%. In the mandible, the torque: protrusion ratio was 37%:63%. The mean intrusion was 1 mm in both dental arches. The follow-up examination showed that the intrusion was relatively stable. In cases where the change in inclination relapsed, the ratio of protrusion to torque was almost equal to that previously used to induce the change during the course of treatment. It is concluded that therapy with torque movement and intrusion offers a more stable result in adults than protrusion movement alone.