Haruki T, Little R M
Dept. of Oral and Maxillofacial Radiology, Okayama University Dental School, Japan.
Angle Orthod. 1998 Feb;68(1):61-8. doi: 10.1043/0003-3219(1998)068<0061:EVLTOC>2.3.CO;2.
The purpose of this study was to evaluate the differences in the long-term stability of orthodontically induced changes in arch form between patients who receive early orthodontic treatment (Hellman's dental age III B, mixed dentition, n = 36) and those who are treated later (Hellman's dental age III C or after, permanent dentition, n = 47). Dental casts were evaluated before treatment, after treatment, and at a minimum of 10 years after retention. All patients had received routine edgewise orthodontic treatment that included maxillary and mandibular first premolar extraction. There were no significant differences between these groups at pretreatment and posttreatment. In the majority of cases, some degree of mandibular crowding occurred during the postretention period. There was a significant difference in the mandibular irregularity index at postretention between these groups. Regarding the deviation of the midline of the central incisors, there were no significant differences between these groups at pretreatment and posttreatment, but there was a significant difference at postretention. At the postretention stage, the late treatment group had greater mandibular anterior irregularity and deviation of the midline.
本研究的目的是评估接受早期正畸治疗的患者（赫尔曼牙龄III B期，混合牙列，n = 36）与较晚接受治疗的患者（赫尔曼牙龄III C期或之后，恒牙列，n = 47）在正畸诱导的牙弓形态变化的长期稳定性方面的差异。在治疗前、治疗后以及保持至少10年后对石膏模型进行评估。所有患者均接受了包括拔除上颌和下颌第一前磨牙的常规方丝弓正畸治疗。这些组在治疗前和治疗后没有显著差异。在大多数情况下，保持期后出现了一定程度的下颌拥挤。这些组在保持后下颌不规则指数存在显著差异。关于中切牙中线的偏差，这些组在治疗前和治疗后没有显著差异，但在保持后存在显著差异。在保持阶段，晚期治疗组的下颌前部不规则和中线偏差更大。
