目的 讨论正畸临床常用的反映上下颌骨矢状位置的经典头影测量角度能否客观地反映上下颌骨突度的实际改变。方法 对48例错患者治疗前后的头颅侧位片进行计算机头影测量，选择3对反映上颌和下颌突度的角度及线距测量项目进行对比计数。结果 虽然角度测量与线距测量具有极显著意义的相关关系，但对比计数显示该3对测量的不符合率分别达到1014%、2219%和3715%。结论 单纯依据头影测量中的经典角度变化来评价上颌或下颌相对颅底的突度改变是不准确的。

In the Begg Technique, factors controlling the anterior intrusive force provided by the archwire have yet to be fully clarified. The rationale for bite opening with very light forces, the effect of Class II elastics on intrusive Force magnitude and the intrinsic qualioy of "Australian" wire in bite opening are examined in this paper. A formulais is presented which allows the intrusive force that archwir exert in different individuals to be predicted. The values derived from the formula were compared with cose model measurements. it was found that the intrusive force of the archwire was afreeted by the length of th e indi vidual dental arch. The magnitude of this in trusive force was seen to increase gradually during the period of bite opening and appeared to be related to the use of Class II elastics. The study revealed factors which aiffected the magnitude of the intrusive force.

随着计算机、扫描仪、数码像机技术的飞速发展，正畸影像资料的数字化及电子档案管理已完全成为可能，为正畸临床诊断、大型临床科研、医疗质量管理等提供了广阔的应用前景，本文拟介绍我们用Visual Basic开发的在中文windows平台下的数字化正畸影像资料电子档案管理及测量分析系统-IDAS。

Class Helastics are usually employed in the treatment of excessive overbite and overjet with the Beg gtechnique. The effect of Class He last II elastics on bite opening and the extent of such an effect is Uncertain. This article, based on measurements of 3O cases, illust rates that the effect of the vertical component of force from Class He lastics in reducing the intrusive force generated by the a nchor bands in the upper archwire is less than previously be|iew d

The purpose of this study was to compare orthodontic treatment outcomes in Chinese patients with borderline problems treated with and without extractions. Methods: Records of 39 borderline patients treated at the Faculty Clinic of the Peking University Orthodontic Department were evaluated retrospectively by 5 associate professors. Sixteen patients had been treated without extractions, and 23 had 4 first or second premolars extracted. Each judge evaluated the posttreatment records independently for tooth alignment, overbite, overjet, midline symmetry, lateral occlusion, and facial profile, and rated them on a scale from 1 to 5. Results: The only statistically significant difference between the extraction and nonextraction groups was for facial profile, with the judges preferring the extraction profiles. Fifteen soft-tissue cephalometric variables were measured to determine the source of the difference, and 6 showed statistically significant differences. When profile changes from pretreatment to posttreatment were examined, significant differences in treatment-associated changes between extraction and nonextraction groups were all related to the lower lip and chin. Conclusions: In this sample of Chinese borderline orthodontic patients, Chinese clinicians had a statistically significant preference for the facial profiles of the extraction patients, but no statistically significant preferences for tooth alignment, overbite, overjet, midline symmetry, or posterior occlusion. Extraction treatment increases the inclination of the chin and reduces protrusion of the lower lip compared with nonextraction treatment, and this might explain the difference.