Maxillary Arch Width and Buccal Corridor Changes Following Extraction and Non-Extraction Fixed Orthodontic Treatment: A Comparative Study

Introduction The effects of premolar extraction on maxillary arch width and buccal corridor size are a debatable topic in orthodontics. It has been suggested that extraction treatment can lead to reduction in dental arch width and more buccal corridor presentation, which can impact smile aesthetics. The aim of this study was to compare the differences in maxillary arch width and buccal corridor dimensions after extraction and non-extraction fixed orthodontic therapy. Materials and methods It was a retrospective study involving pre-treatment and post-treatment records of patients treated with contemporary fixed orthodontic appliances in the Department of Orthodontics and Dentofacial Orthopaedics, Government Dental College, Raipur. A total of 70 patients (35 extraction and 35 non-extraction) were screened initially. After a photographic comparability criterion in terms of intercanthal-to-inter-commissural width ratio was applied, 48 subjects were used in the final analysis (25 extraction and 23 non-extraction). Maxillary inter-canine, inter-premolar, and intermolar widths were measured on the study models using a digital caliper. Buccal corridor dimensions were evaluated from frontal smile photographs using Adobe Photoshop software. Paired Student's t-test was used for intragroup comparisons, and independent Student's t-test was used to compare treatment-induced changes between the extraction and non-extraction groups. Results Significant increases in intercanine and interpremolar widths were observed following treatment in both groups (p<0.05). A significant increase in intermolar width was observed only in the non-extraction group (p=0.008). Intergroup comparison demonstrated a significantly greater intermolar width change in the non-extraction group (p=0.001), whereas intercanine and interpremolar width changes were comparable between the groups. Buccal corridor measurements remained largely unchanged following treatment, with no significant intergroup differences. A statistically significant increase in the IL:SW (interlast visible maxillary teeth distance (IL) and smile width (SW)) ratio was observed in the non-extraction group (p=0.025). Conclusions Both extraction and non-extraction fixed orthodontic treatment were associated with favourable transverse arch changes, while buccal corridor dimensions remained largely stable following treatment. Intergroup comparison demonstrated a significant difference only in intermolar width changes, whereas the remaining transverse and buccal corridor measurements were comparable between the groups. These findings suggest that premolar extraction therapy does not necessarily result in clinically unfavourable narrowing of the maxillary arch or increased buccal corridor dimensions when contemporary fixed orthodontic treatment mechanics are employed.