改型腭杆压低过长上颌第二磨牙的定量临床研究

目的评价使用改型腭杆辅助压低过长上颌第二磨牙的临床效果。方法选取13名需要压低过长上颌第二磨牙的成年患者，共18颗牙。采集矫治前、后记存模型进行激光扫描，在Rapidform 2006软件中进行三维测量，明确过长牙和支抗牙各牙尖点在三维方向上的移动量，通过曲面断层片观察过长牙与支抗牙压低前后的牙根吸收情况。结果13名患者均完成过长牙的压低，平均疗程为5．5个月。过长后牙各牙尖点（近中颊尖、远中颊尖、近中腭尖、远中腭尖）分别被压低了0．90mm、0．94mm、1．78mm和1．78mm，远中移动了1．06mm、1．06mm、1．03mm、0．92mm，腭向移动了0．95min、0．88iilin、1．10iilin、0．85illn，配对样本t检验显示差异具有极显著统计学意义（P〈0．001）。而支抗牙的移动量不明显。x线片显示被压低的过长牙与支抗牙均未出现明显牙根吸收。结论改型腭杆辅助压低过长上颌第二磨牙是一种有效便捷的正畸治疗手段。

Effects of modified transpalatal arch on intrusion of overerupted maxillary second molars-aquantitive study

Objective To evaluate the clinical effect on intrusion of overerupted upper second molars with modified transpalatal arch. Methods Thirteen adult patients with eighteen overerupted upper second molars were treated with modified transpalatal arch. Record models were taken before and after orthodontic treatment. After models scanning, the movements of overerupted second molars and anchorage teeth were measured three dimensionally by Rapidform 2006 software. The root resorptions were assessed with panoramic radiographs. Results All overerupted upper second molars were intruded successfully. The average treatment time was 5. 5 months. The movement of four cusps of overerupted molars were measured at cusp apex of MB, DB, MP and DP. The intrusion distances were 0. 90 mm, 0. 94 mm, 1. 78 mm, and 1. 78 mm. The distallization distances were 1. 06 mm, 1.06 mm, 1.03 rnm and 0. 92 mm. The palatal movement distances were 0. 95 mm, 0. 88 mm, 1.10 mm and 0. 85mm T-test for paired samples showed a statistically significant difference （P〈0. 001）. The movements of anchorage teeth were not obvious. Conclusions The modified transpalatal arch was an effective and simple method to intrude overerupted upper second molars.