Evaluation of orthodontic results of Angle Class I malocclusion with first premolar extraction

Tóm tắt

Objective: To evaluate the change of hard tissue and soft tissue after treatment of dental and skeletal bimaxillary protrusion in Angle Class I malocclusion patient by extraction of 4 premolars. Subject and method: The uncontrolled clinical trial of 45 patients with skeletal bimaxillary protrusion at Dental Department - 108 Military Central Hospital, from January of 2015 to May of 2018. Result and conclusion: Changes in hard tissue and soft tissue after treatment: Pre-treatment PAR index of malocclusion was 17.2 points, uneven anterior teeth has the highest index of 11.5; then uneven posterior teeth was 3.5. After treatment: Uneven anterior teeth, uneven posterior teeth, posterior teeth bite and overjet change were statistically significantly reduced (p<0.001), 88.2% of patients with PAR index decreased (> 70%); no patients with PAR changes < 40%. The protrusion of patient’s profile improved significantly after treatment. Angle of convexity changed -2.7 ± 1.46⁰ with p<0.001 so that the surface reduced convexity. Reduce the protrusion of the upper and lower lip compared to the horizontal plane, respectively, those was 2.6 ± 2.41mm and 3.2 ± 2.81mm (p<0.001). The protrusion of the upper and lower lips compared to the esthetic line E after treatment was 0.8 ± 1.29mm and 3.0 ± 1.83mm, respectively, 2.3 ± 1.26mm and 3.2 ± 1.72 with p<0.001. The protrusion of upper lip and lower lip compared with SnPog’ plane after treatment was 7.4 ± 1.64mm and 7.0 ± 2.11mm respectively, decreased 2.0 ± 1.38 and 3.0 ± 1.89mm respectively. VAS score was 7.0 ± 1.05 points.