开颌患者的根冠比与咬合接触丧失和下颌平面角高的关系。
Relationships between the root-crown ratio and the loss of occlusal contact and high mandibular plane angle in patients with open bite.
机构信息
Department of Orthodontics, Field of Developmental Medicine, Health Research Course, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
出版信息
Angle Orthod. 2013 Jan;83(1):36-42. doi: 10.2319/042412-341.1. Epub 2012 Aug 16.
OBJECTIVE
To determine the root-crown (R/C) ratio and dental root length of teeth in patients with open bite and seek any relationships with occlusal contact (OC) and the mandibular plane (Mp) angle.
MATERIALS AND METHODS
Thirty-one patients with open bite with negative overbite of at least four anterior teeth and 31 control patients with clinically normal overjet and overbite were enrolled. R/C ratios, dental root length, OC, and Mp angle were measured using panoramic radiographs, dental casts, and cephalograms, respectively. Mean differences between the groups, and variations between the R/C ratio or root length and Mp angle in patients with open bite were statistically analyzed.
RESULTS
R/C and OC ratios from the incisors to premolars were significantly lower for patients with open bite than for controls, and some teeth had short dental roots. Relationships between low R/C ratio or root length and high Mp angle were significant in patients with open bite.
CONCLUSION
Patients with open bite, especially those with a high Mp angle, have an unfavorable R/C ratio and short dental roots in some teeth, which may be related to the loss of OC.
目的
确定反颌患者的根冠比和牙齿根长，并探讨其与咬合接触（occlusal contact，OC）和下颌平面（mandibular plane，Mp）角度的关系。
材料与方法
选取 31 例反颌伴至少 4 颗前牙覆颌为负的患者和 31 例具有临床正常覆颌和覆盖的对照组患者。分别使用全景片、牙模和头颅侧位片测量根冠比、牙齿根长、OC 和 Mp 角度。采用独立样本 t 检验比较两组间的差异，分析反颌患者根冠比或根长与 Mp 角度之间的变化。
结果
反颌患者的切牙至前磨牙的根冠比和 OC 比值明显低于对照组，部分牙齿的根较短。反颌患者中，低根冠比或根长与高 Mp 角度之间存在显著相关性。
结论
反颌患者，尤其是高 Mp 角度的患者，在一些牙齿中存在不利的根冠比和较短的牙齿根长，这可能与 OC 的丧失有关。
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