西藏那曲地区藏族中小学生恒牙(牙合)期颅面硬组织的结构特征:200例X射线头影测量

背景:颅面硬组织结构在年龄、性别、地区及种族方面存在着差异.已有一些学者对国内一部分城市错(牙合)畸形人群进行了X射线头影测量研究,取得了颅面硬组织结构头影测量正常值,而关于西藏地区藏族恒牙(牙合)期青少年的颅面硬组织结构头影测量的研究较少.目的:观察西藏拉萨地区藏族恒牙胎期青少年颅面硬组织结构特征.设计、时间及地点:分层整群抽样调查,于2008-06/08在西藏那曲地区完成.对象:选择2003年西藏拉萨地区中小学中当地藏族恒牙(牙合)期青少年200名,男女各100名,年龄11-14岁.要求牙齿排列整齐,胎关系中性,上下颌骨形态及关系正常,牙数及覆(牙合)覆盖正常,面部和谐,在调查前无正畸治疗史,处于恒牙(牙合)期.方法:按照同一照射条件和标准对200名藏族恒牙(牙合)期青少年在正中(牙合)位摄取标准头位进行头颅面侧位定位片拍摄,测量常用硬组织X射线头影测量值,并与内地同年龄组正常值对照.主要观察指标:上齿槽座角(SNA角)、下齿槽座角(SNB角)、上下齿槽座角(ANB角)、上中切牙前颅底平面角(1-SN角)、上中切牙鼻根齿槽角(1-NA角)、上中切牙鼻根齿槽距(1-NA)、下中切牙下颌平面角(T-MP角)、蝶颏眼耳平面角(Y轴角)、面角(NP-FH)、颌凸角(NA-PA)、上下中切牙角(1-T)、前颅底下颌平面角(MP-SN)、颏前距(Po-NB)、下中切-牙鼻根齿槽角(T-NB角)、下中切牙鼻根齿槽距(T-NB)、下颌平面角(MP-FH).结果:藏族拉萨地区恒牙(牙合)期青少年SNA角、SNB角、ANB角、1-SN角、1-NA角、1_NA、T-MP角、Y轴角、NP-FH、NA.PA、1-T、MP.SN与内地同龄汉族标准值比较,差异无显著性意义:Po-NB稍大于内地汉族同龄标准值,T-NB角、T-NB 和MP.FH均明显小于内地同龄汉族标准值. 结论:西藏拉萨地区藏族恒牙耠期青少年与内地同年龄组汉族青少年在颅面硬组织结构特征方面存在较大差异:颏部稍向前突,下颌角相对较平,下前牙较直立,而上前牙无明显差异,下颌向上、前旋转,骨面型较直.

Craniofacial hard tissue structures of middle and primary school students from Naqu, Tibet: X-ray cephalometric measures of 200 cases

BACKGROUND: Craniofacial hard tissue structures vary in age, gender, regional and racial differences. Some researchers have conducted X-ray cephalometric measures of malocclusion deformity in some domestic cities, and obtained normal cephalometric measures of craniofacial hard tissue structure. However, little data have been available concerning cephalometric measures of craniofacial hard tissue structure of Tibetan youth in Tibet region. OBJECTIVE: To observe structural features of craniofacial hard tissue of permanent tooth occlusal period in the adolescent of Lhasa. DESIGN, TIME AND SETTING: Stratified cluster sampling survey was performed at Naqu, Tibet from June to August 2008. PARTICIPANTS: A total of 200 adolescents at permanent tooth occlusal period, 100 males and 100 females aged 11-14 years were selected from middle and primary schools of Lhasa in 2003. The inclusion criteria included: teeth in order, neutral occlusal adjustment, normal maxilla and mandible appearance and relationship, normal teeth number and overbite and overjet, concordant face, and no history of orthodontic management. METHODS: According to the requirements and standards for the irradiation, 200 subjects underwent X-ray cephalometric measures, and the results were compared with normal values of the same age. MAIN OUTCOME MEASURES: SNA angle, SNB angle, ANB angle, 1-SA angle, 1-NA angle, 1-NA, T-MP angle, Y axial angle, NP-FH angle, NA-PA angle, 1-T angle, MP-SN angle, Po-NB, T-NB angle, T-NB, and MP-FH angle. RESULTS: No significant differences were found between Lhasa adolescents and normal values in terms of SNA angle, SNB angle, ANB angle, 1-SN angle, 1-NA angle, 1-NA, T-MP angle, Y axial angle, NP-FH, NA-PA, 1-T, and MP-SN. Po-NB was slightly greater than normal value and T-NB angle, T-NB and MP-FH were significantly less than normal values. CONCLUSION: Lhasa adolescents have significantly different craniofacial hard tissue structure from normal values: forward protrusion of mental region, flat mandible angle, straight mandible anterior teeth, upward and forward rotated mandible, and straight face type.