RESUMO
OBJECTIVES: Researchers have conducted extensive studies regarding dentoalveolar factors that affect anterior dental aesthetics; however, there is no consensus regarding how these factors affect orthodontic treatment decisions. Only a few studies have included multiple factors simultaneously. Therefore, the objective was to investigate if there are identifiable dentofacial and perioral aesthetic factors that bias laypeople towards discontinuing treatment after a phase I treatment with this fixed class II corrector. METHODS: An analysis of photos and dental casts of 60 children (23 males, 37 females) having received phase I orthodontic treatment with the Xbow appliance was conducted. Variables considered were incisor height and width measurements, incisor proportions, incisor angulations, vertical lip thickness, gingival/incisal display, smile width per cent, diastema, midline deviation, smile arc, gender, and use of a 2×4. A principal component analysis and a logistic regression were used to determine which factors related to a patient's likelihood of receiving further orthodontic treatment. RESULTS: Only the angulation of the right maxillary incisors was significantly related to a patient's likelihood (odds ratio 1.886 (1.004-3.466); P = 0.049) to proceed to phase II orthodontic treatment following phase I orthodontic treatment with the Xbow appliance. The odds of proceeding to phase II treatment were 86.6% greater with a one standard deviation increase in the angulation of the right central and lateral incisors. Other factors demonstrated trends but were not statistically significant. LIMITATIONS: Sample in subgroups was small, excluded smiles that did not expose the upper incisor crowns significantly, smiles in real life are observed three-dimensionally, other factors outside the aesthetic measurements were not considered in the analysis. CONCLUSIONS: In this sample, the angulation of the maxillary right incisors was the most significant factor influencing the decision to undergo an orthodontic phase II.