Objectives: To compare the root length of maxillary and mandibular anterior teeth between open bite patients and normal overbite patients via cone-beam computed tomography (CBCT) as well as the root length of anterior teeth in different degree of open bite patients, and to analyze the correlation between the degree of open bite and root length.
Methods: A total of 106 untreated patients were enrolled retrospectively (53 anterior open bite patients and 53 normal overbite patients).Three-dimensional position of the CBCT image for the patient's teeth was performed using Dolphin software. The median sagittal plane of the tooth was used as the measurement plane, and the line connecting the apical point and the midpoint between the labial and lingual cementoenamel junctions was defined as the root length. Independent t-test was used to compare the difference of anterior root length between the open bite group and normal overbite group, mild open bite group and moderate-severe open bite group. Pearson correlation analysis was used to explore the correlation between the degree of open bite and the root length of anterior teeth.
Results: Significant differences were found in the root length of maxillary and mandibular anterior teeth between the open bite group and the normal overbite group (P<0.001), and there was significant difference in root length of mandibular central incisor between mild open bite group and moderate-severe open bite group (P=0.039). Pearson correlation analysis showed that maxillary anterior teeth were correlated with root length of anterior teeth (all P<0.05).
Conclusions: The root length of maxillary and mandibular anterior teeth in the open bite patients is shorter than that in the normal overbite patients, and the severer the degree of open bite, the shorter the root length of the mandibular central incisor tends to be. There is a certain relationship between maxillary anterior teeth and the root length of anterior teeth.
目的: 运用锥形束CT(cone-beam computed tomography，CBCT)比较前牙开 与正常覆 患者上下颌前牙根长的差异，对开 组内不同程度的开 牙根长度进行对比，分析开 程度与前牙根长的相关性。方法: 筛选106例治疗前患者(前牙开 53例、正常覆 53例)作为研究对象，运用Dolphin软件对CBCT数据前牙区进行三维定位，以牙齿的正中矢状面作为测量平面，以唇舌向釉牙骨质连线中点和根尖点的连线作为牙根长度，测量上下颌前牙根长。采用两独立样本t检验分别比较开 组与正常覆 组、轻度开 组与中重度开 组患者前牙根长的差异，采用Pearson相关分析研究开 程度与前牙根长的相关性。结果: 开 组与正常覆 组各同名上下颌前牙牙根长度之间差异均有统计学意义(P<0.001)，轻度开 组与中重度开 组下颌中切牙根长差异存在统计学意义(P=0.039)，Pearson相关分析结果显示前牙覆 与各前牙根长均呈正相关(均P<0.05)。结论: 开 患者的上下颌前牙牙根长度均较正常覆 者短，且开 程度越重，其下颌中切牙根长越短，前牙覆 与前牙根长之间存在正相关关系。.
Keywords: anterior open bite; cone-beam CT; root length; root resorption.