Facial profile of patients with congenitally missing 2 mandibular incisors and changes of facial profile before and after orthodontic treatment by extraction of 2 maxillary premolars / 吉林大学学报(医学版)

ABSTRACT

Objective: To analyze the facial profile of the patients with congenitally missing 2 mandibular incisors, and to investigate the changes of facial profile of the patients before and after orthodontic treatment by extraction of 2 maxillary premolars. Methods: The cephalometrics of 64 patients with congenitally missing 2 mandibular incisors were collected. The initial cephalometrics of 64 patients were used to characterize the facial profile. A total of 38 cases among all the 64 patients underwent the orthodontic treatment by extraction of 2 maxillary premolars, and the initial and final cephalometrics were used to compare the changes of facial profile before and after treatment. The cephalometric measurement (including hard tissue and soft tissue items) was performed and the results were analyzed statistically. Results: Compared with the normal values, the overjet, overbite, ANB, U1-NA angle, face angle, Y axis, Pg-NB, face convexity, soft tissue facial angle, H angle, and men to labial sulcus to H-Line in the patients with congenitally missing 2 mandibular incisors were increase d, SNB, L1-NB angle, L1-NB distance, L1-MP, occlusal plane angle, mentolabial sulcus angle were decreased, and the differences were statistically significant (P<0. 05). After orthodontic extraction treatment, the overjet, overbite, U1-NA angle, U1-NA distance, U1-SN, H angle, and subnasale to H-Line of the patients were decreased, the L1-NB angle, L1-NB distance, L1-MP, occlusal plane angle, Pg-NB, and mentolabial sulcus angle were increased; the differences were statistically significant (P<0. 05). Conclusion: The mandibular development is insufficient but the chin development is adequate in the patients with congenitally missing 2 mandibular incisors, with larger overjet and overbite, lingually inclined mandibular incisors, deeper and sharper mentolabial sulcus. After treatment by extraction of 2 maxillary premolars, the overall appearance of the lateral profile of the patients remains unchanged, but the occlusion of anterior teeth is significantly improved.