Iatrogenic retroposition of the lips sequel after bicuspid extraction-a retrospective study

This study aims to explore the prevalence of Iatrogenic retroposition of the lips sequel (IRLS) after bicuspid extraction, associated dentofacial characteristics and the effectiveness of surgical treatment.

and methods: Patients with bicuspid extraction as part of an orthodontic treatment plan were retrospectively included. IRLS was identified by clinical evaluation and cephalometric Legan and Burstone analysis. Association of demographic and cephalometric variables were assessed. The effectiveness of combined orthodontic-orthognathic correction of the retroposition of the lips was evaluated.

Out of 144 patients with extracted bicuspids, eight Class I patients, nine Class II patients and five Class III patients were seeking treatment because their lips had retruded as a consequence of compensating orthodontic treatment. Lower jaw bicuspid extraction and a decreased vertical facial height in Class II patients correlated significantly more with IRLS development. Postoperative cephalometric analysis of orthodontic-orthognathic treated patients reported improvement in lip projection and naso-labial angle. Only two Class I patients reported postoperative normalization of the lip position according to Legan and Burstone.

The consequence of bicuspid extractions on soft tissue profile differs according to skeletal jaw relation. The impact of orthognathic surgery on IRLS is beneficial, although insufficient to completely correct the facial profile when judged on cephalometric standards.