Profile changes following orthodontic correction of bimaxillary protrusion with a preadjusted edgewise appliance

This study aimed to determine the changes in soft tissue and skeletal profiles following orthodontic correction of bimaxillary protrusion in 50 Chinese adult patients. Treatment involved extractions of four premolars and use of the preadjusted edgewise appliance. The average treatment time was 2.2 years. Cephalometric analysis was carried out on pretreatment and posttreatment cephalograms. The result of treatment was a more harmonious soft tissue profile; with a less acute nasolabial angle (following a 10.55-degree change), 2.75- and 2.09-mm reductions in upper and lower lip protrusions, respectively, and a 3.41-mm decrease in interlabial gap. Effects on dental relationships included a 0.90-mm reduction in incisal show, a reduction of overbite, and an improvement in the inclination of maxillary and mandibular incisors. Therefore, orthodontic correction of bimaxillary protrusion achieved favorable soft tissue changes without causing undesirable effects on the underlying hard tissues.