第二恒磨牙生长萌出位置和发育阶段与不同矢状骨面型的相关性研究

Correlation study of the eruption and development of the second molars in patients with different sagittal skeletal patterns

目的通过评价11岁牙龄儿童不同矢状骨面型患者第二恒磨牙的萌出位置和发育阶段,分析其与不同矢状骨面型的相关关系。方法选取牙龄11岁错畸形患者74例(根据Becker牙龄评价标准确定牙龄)。根据患者矫治前数字头颅侧位X线片,测量3组患者的SNA角、SNB角、ANB角以及APDI值,依据测量值将其分为骨性Ⅰ类组、下颌骨骨性Ⅱ类组和上颌骨骨性Ⅲ类组。同时根据头颅侧位X线片和数字化曲面断层X线片,测量第二磨牙的萌出高度、角度和发育阶段。采用SPSS16.0软件包进行统计学分析,P<0.05差异具有统计学意义。结果 11岁牙龄儿童在不同矢状骨面型中,上下颌第二恒磨牙萌出高度、角度和发育阶段均未见显著差异(P>0.05);PP长度与上颌第二恒磨牙的萌出高度及发育阶段呈正相关性(P<0.01),与萌出角度呈负相关性(P<0.05);GM长度与上下颌第二恒磨牙的发育阶段呈正相关性(P<0.01),但与下颌第二磨牙的萌出高度和角度无相关性(P>0.05)。结论通过11岁牙龄组的第二恒磨牙萌出高度、角度、发育阶段与不同矢状骨面型相关性分析可推断,11岁牙龄组儿童上颌骨长度越长,上颌第二磨牙萌出高度越高,萌出角度越小,发育时间越早;下颌体长度越长,上下颌第二磨牙发育越早。

Objective To estimate the correlations of the eruption and development of the second molars in patients with different sagittal skeletal patterns at the 11th dental age.Methods Pretreatment records of 74 patients with a mean dental age of 11 years（according to the Becker′s method）were evaluated for the study,which were divided into skeletal Class Ⅰ,skeletal Class Ⅱof mandible and skeletal Class Ⅲ of maxilla groups according to their ANB,SNA,SNB angles and APDI on digital lateral cephalograms before treatment.The eruptional height,eruptional angle and developmental stages of the second molars were assessed from digital X-ray panoramic radiographs and the lateral cephalograms.SPSS16.0 package was used to analyze and process the data.Significant difference was identified with P0.05.Results There was no significant difference in the eruptional height,eruptional angle and developmental stages of the maxillary or mandibular second molars among different sagittal skeletal patterns in patients with a mean dental age of 11 years（P0.05）.The length of PP had a positive correlation with the eruptional height and developmental stages of the maxillary second molars（P0.01）,but had a negative correlation with the eruptional angle of the maxillary second molars（P0.05）.The length of GM had a positive correlation with the developmental stages of the maxillary and mandibular second molars（P0.01）,but had no correlation with the eruptional height and eruptional angle of the mandibular second molars（P0.05）.Conclusion According to the correlative assessment,in children of 11 years dental age,the greater the maxillary length,the higher eruptional height of the maxillary second molars and the smaller the eruptional angle,the earlier the development of the second permanent molar of maxillary and mandible.The greater the mandibular length,the earlier the development of the second permanent molar of maxilla and mandible.