Extractions in the setting of facial harmony in adolescents with bimaxillary protrusion: a retrospective cohort study

ABSTRACT Purpose The objective of this study was to assess the importance of orthodontic extractions in the setting of facial harmony to adolescents with bimaxillary protrusion. Material and methods: The orthodontic files of 73 adolescents with incisors protrusion treated with or without premolar extractions were studied on pre- and post-treatment facial photographs in a retrospective cohort study, while dental casts of 69 were assessed. The best-fit template of normal proportions was superimposed to the photograph and the facial harmony scores were obtained, while the DAI (dental aesthetic index) was studied in the models. Intra- and intergroup statistical comparisons and the index of improvement were determined. Results: The groups demonstrated significant change of lips positioning, though extraction group reached relative higher index of improvement. There was significant improvement in the labiomental groove position only for the extraction group in a profile view. Generally, a high success rate of dental relationships was found in the DAI. Conclusions: Both treatment protocols reached significant improvement of facial harmony. Orthodontic extractions of premolars might be related to establishing normal occlusion in cases with bimaxillary protrusion, while preventing worse hyperactive mental muscle when the arch discrepancy is negative. Abbreviations: 1-NA: Upper incisors cephalometric protrusion in millimetres; 1-NB: Lower incisors cephalometric protrusion in millimetres; AIR: Alare at right side; Al: Alare; AlL: Alare at left side; Ch: Cheillion; ChL: Cheillion at left side; ChR: Cheillion at right side; DAI: Dental Aesthetic Index; Ex: Exocanthion, posterior contour of the Orbitale; G: Glabela; Li: Inferior Lip; Ls: Superior Lip; Me: Menton; Msw: Midpoint of the craniofacial depth; OA: Anterior contour of the Orbitale; Ocp: Occipital; OL: Lower contour of the Orbitale; OU: Upper contour of the Orbitale; PLL: Pupil at left side; PLR: Pupil at right side; Pog: Pogonion; Sm: Labio-mental sulcus; Sn: Subnasale; Tr: Trichion; V: Vertex; ZyL: Zygion at left side; ZyR: Zygion at right side