Treatment Outcomes and Stability in Extraction vs. Non-Extraction Adult Anterior Open Bite Patients

Thesis (Master's)--University of Washington, 2022Introduction: Anterior open bite (AOB) correction is difficult to achieve and more difficult to maintain. Some orthodontists utilize extractions to assist in bite closure. This study aims to explore whether extractions in adult patients with AOB lead to improved treatment outcomes and better long-term stability.Methods: The pre- and post-treatment records of adult orthodontic patients with AOB were previously obtained through the National Dental Practice-Based Research Network (National Dental PBRN) as part of a larger study. These patients were treated with fixed appliances only. The total sample was divided into extraction and non-extraction groups. Frontal intraoral photographs were obtained at a long-term follow up timepoint for some of the patients. The Photographic Openbite Severity Index (POSI) was used to assess treatment success and stability. Skeletal, dental and soft tissue treatment outcomes were evaluated using cephalometric analysis. Results: Pre- and post-treatment records were collected for 115 patients. Among this sample, 33 patients were treated with extractions and 82 were treated without extractions. Pre-treatment differences included a younger extraction group with more crowding and less history of previous orthodontic treatment. Orthodontists had similar success in achieving positive overbite of both central incisors when treating with (97%) or without extractions (92%). No clinically significant differences in skeletal outcomes were observed. The extraction group exhibited more lingual tipping and posterior movement of maxillary and mandibular incisors and less extrusion of mandibular incisors. These dental changes were paired with increased nasolabial angle and lip retraction. The sample size at the long term follow up was not sufficient to draw a significant conclusion regarding stability. Conclusions: In these adult patients, the rate of successful open bite closure was similar, with or without extractions. The extraction group displayed more retraction and lingual tipping of incisors, as well as increased retraction of soft tissues. Based on a limited sample, all patients in the extraction group had a stable result while 90% of patients in the non-extraction group maintained successful AOB correction at a one-year follow up