Assessment of the nasolabial angle after orthodontic treatment with and without extraction of the first premolars

Flávio Marcos de ALMEIDA, Iara Souza NEVES, Tarcísio Junqueira PEREIRA, Vânia Célia Vieira de SIQUEIRA

Aim: To cephalometrically evaluate the changes in the nasolabial angle of the patients submitted to orthodontic treatment with and without extractions and correlate them with upper incisor inclination, upper lip position and the base of the nose. Methods: The sample was composed of pre and posttreatment lateral cephalometric records of 30 female patients with Class II division 1 malocclusion. Fifteen were treated with irst premolars extractions and the other ifteen without extractions. The following parameters were measured: nasolabial angle; upper incisor inclination (Is.SN7º angle), upper lip position (Ls-PCm.SN7º angle) and base of the nose (PCm.SN7º angle). Results: The upper incisor inclination and the upper lip position showed a statistically signiicant increase from T0 to T1 in the extraction group. No statistically signiicant differences were found for the other parameters in both groups. The correlations between upper lip position, base of the nose and the nasolabial angle were positive. Conclusion: 1) There was a signiicant increase in the nasolabial angle in the extraction group and it was mainly due to changes in the upper lip position; 2) nasal growth during the study period did not contributed to the nasolabial angle increase; 3) all measurements were not statistically different between the 2 groups at T0 and T1, and 4) a positive correlation was found between the nasolabial angle, lip position and base of the nose in both groups.

Keywords: Class II division 1. Nasolabial angle. Premolar extraction. Facial profile.

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