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目的分析常州市11~14岁青少年恒磨牙(主要是第二磨牙M2和第三磨牙M3)的影像学表现,横向研究恒磨牙的发育、萌出情况,以及M3、M2的发育关系。方法从常州市口腔医院影像资料中抽取2013年1~10月期间拍摄的11~14岁青少年的全颌曲面断层片共345张,分别观察M3、M2的发育情况并进行发育分期,分析两者的相关性。结果在11~14岁青少年中,M2处于发育G期的比例为43.26%,下颌整体发育早于上颌(Z=-11.69,P<0.001),女性较男性发育早(Z=-3.06,P=0.002);21颗阻生,均为下颌近中倾斜,占下颌M2总数的3.04%。M3处于发育C期的比例为33.26%,女性比男性发育早(Z=-2.06,P=0.040),下颌M3发育早于上颌(Z=-3.42,P=0.001)。经Spearman相关分析,M3与M2存在相关性(r=0.869,P<0.001)。结论青少年中M2与M3的发育密切相关,除去生长因素外、上下颌牙弓后段能否同时容纳、是否容易导致复发等,在正畸治疗时需要充分考虑两者的关系。
Objective To analyze the imaging manifestations of permanent molars (mainly secondary molars M2 and tertiary molars M3) of 11-14-year-old adolescents in Changzhou and to study the development and eruption of permanent molars transversely and the relationship between the development of M3 and M2. Methods From the image data of Changzhou Stomatology Hospital, 345 total length of maxillary curved surfaces of 11 ~ 14-year-old adolescents from January 2013 to October 2013 were collected. The developmental stages of M3 and M2 were observed and the staging was performed. Relevance. Results The proportion of M2 in developmental G stage was 43.26% in 11 to 14-year-old adolescents, and the development of lower jaw was earlier than that in the maxilla (Z = -11.69, P <0.001) 0.002). 21 implants, all of them were moderately inclined, accounting for 3.04% of the total number of mandibular M2. The proportion of M3 in developing C was 33.26%. The development of M3 was earlier in men than in men (Z = -2.06, P = 0.040). The development of mandibular M3 was earlier than that in the maxilla (Z = -3.42, P = 0.001). According to Spearman correlation analysis, there was a correlation between M3 and M2 (r = 0.869, P <0.001). Conclusion M2 and M3 in adolescents are closely related to the development of M3. In addition to the growth factors, the posterior segment of the maxillary and mandibular dental arch can be accommodated at the same time and easily lead to recurrence. In orthodontic treatment, the relationship between M2 and M3 should be fully considered.