Extraction of maxillary first permanent molars in patients with Class II Division 1 malocclusion

Our objectives were to assess treatment outcomes in Class II Division 1 patients who were treated orthodontically with extraction of the maxillary first permanent molars and to describe the changes in their facial profiles.

This was a prospective, longitudinal, 1-group outcome analysis in a private practice, with outcome evaluation by independent observers at an academic clinic. One hundred consecutively treated patients were enrolled prospectively and treated by 1 orthodontist. The inclusion criteria were white, Class II Division 1, sagittal overjet of > or =4 mm, extraction of maxillary first permanent molars, no missing teeth or agenesis, maxillary third molars present, and 1-stage full fixed appliance treatment. Standardized lateral cephalometric radiographs were made before and after active treatment. Occlusal outcome was scored on dental casts by comparing pretreatment and posttreatment casts with the peer assessment rating (PAR) index. Backward regression analysis was used to explain the soft-tissue changes on the basis of dental changes and the soft-tissue characteristics.

The mean reduction in weighted PAR score was 89.9% (SD, 0.9). During treatment, the lower lip retruded 1.6 mm (SD, 1.7) relative to the esthetic line. The nasolabial angle became 2.1 degrees (SD, 7.0) more obtuse during treatment. Overjet reduction and initial upper lip thickness could explain 15% of the variation in upper lip position. The changes in the position of the mandibular incisor relative to the Point A-pogonion line and initial lower lip thickness could explain 23% of the variation of lower lip position.

Orthodontic treatment involving extraction of the maxillary first permanent molars has a good treatment outcome. Extraction of the maxillary first permanent molars has only a small effect on the soft-tissue profile.