SỰ THAY ĐỔI VỊ TRÍ RĂNG CỬA VÀ MÔ MỀM TRÊN PHIM SỌ NGHIÊNG TỪ XA CỦA BỆNH NHÂN SAI KHỚP CẮN LOẠI II TIỂU LOẠI 1 CÓ NHỔ BỐN RĂNG HÀM NHỎ

Abstract

Objectives: To    evaluate    the    effects of premolars extraction on incisor position and soft tissue profile in patients with Class II, division 1 malocclusion.  Materials  and  method: Descriptive study by evaluate pre- treatment and post- treatment cephalometric radiography of 31 patients (21 females, 10 males) diagnosed with class II division 1 malocclusion with four premolars extraction in School of Odonto- Stomatology and National Hospital Of Odonto- Stomatology to June 2021 were recruited. Results: The average of age was 18,65 (range in 11 to 34). The SNA and SNB angles changed no significantly during treatment. The inclination of upper incisor in relations with cranial base, palatal plane and NA decreased by 10,19 ± 9,07⁰, 9,84 ± 8,60⁰ and 10,13 ± 7,40⁰ respectively. The inclination of lower incisor in relations with mandible plane and NB decreased by 4,53 ± 7,31⁰ and 6,60 ± 5,25⁰ respectively. Interincisal angle increased by 15,94 ± 12,82⁰. We observed a highly significant increase in the distance between the upper and lower lips and the esthetic line and SnPog’ line. No significant differences were apparent in the nasolabial angle, the lips thickness and chin thickness. Conclusions: Between the start and the end of treatment, class II division 1 malocclusions with four premolars extraction experienced more retruded  upper and lower incisors. The wider interincisal angle showed a decrease of bimaxillary protrusion. The distance between the upper and lower lips and the esthetic line and SnPog’ line decreased dramatically showed positive effects on the facial profile. No significant differences in the nasolabial angle, lip thickness and chin thickness during treatment.