第三磨牙先天缺失与颅颌面结构相关性的研究

Relationship between congenital absence of third molars and craniomaxillofacial structure

目的通过对第三磨牙先天缺失患者的缺失位置、数目与颅颌面部的头影测量指标进行研究,分析第三磨牙先天缺失与颅颌面结构的相关性。方法共纳入123例患者,其中无第三磨牙先天缺失的患者纳入对照组,共64例;有至少一颗第三磨牙缺失纳入缺失组,共59例。对纳入患者的头颅侧位片进行头影测量和统计学分析,测量指标包括FMA、IMPA、Ar-Go、GoGn-SN、Co-A、Co-Gn、ANS-Me、SN-MP、Ar-Go-Me、SNA、SNB、ANB、Y轴角、Y轴长度、Ar-Go、Go-Me、MP-OP、FH-PP、FH-OP共18项骨组织指标,U1-SN、U1-L1、U1-NA、L1-NB、U1-APo、L1-APo共6项牙性指标,UL-EP、LL-EP、鼻唇角共3项软组织指标,分析第三磨牙先天缺失与颅颌面结构的相关性。结果第三磨牙最常见缺失位置发生于上颌且最常见的缺失数目为一颗。对照组患者Ar-Go-Me和SN-MP更大(P<0.05),U1-SN、U1-NA、L1-NB、UL-EP、LL-EP更大(P<0.05),U1-L1更小(P<0.01),对照组患者Ar-Go和Go-Me与缺失组之间的差异没有统计学意义(P>0.05)。结论四颗第三磨牙均存在的患者相比有第三磨牙缺失的患者,下颌骨更易向后下旋转且更容易发育成凸面型,与高角面型、凸面型具有较高的相关性。

Objective To analyze the correlation between third molar agenesis and craniofacial morphology by studying the location and number of congenital missing third molars and results of craniofacial cephalometric measurement.Methods A total of 123 patients were included,including 64 patients in the control group without congenital third molar absence and 59 patients in the absence group with at least one third molar absent.Cephalometric measurements included FMA,IMPA,AR-Go,GoGn-Sn,Co-A,Co-Gn,ANS-Me,Go-Me,SN-MP,Ar-Go-Me,SNA,SNB,ANB,Y-axis angle,Y-axis length,Ar-Go,Go-Me,MP-OP,FH-PP,FH-OP,a total of 18 bone tissue indicators,U1-SN,U1-L1,U1-NA,L1-NB,U1-APo and L1-APo,a total of 6 dental indicators,and UL-EP,LL-EP and nasolabial angle,a total of 3 soft tissue indicators.The correlation between congenital agenesis of third molars and craniofacial morphology was analyzed.Results The most common missing location of the third molar occured in the upper jaw and the most common number of missing teeth was one.In control group,Ar-Go-Me and SN-MP were larger(P<0.05),U1-SN,U1-NA,L1-NB,UL-EP and LL-EP were larger(P<0.05),and U1-L1 was smaller(P<0.01).There were no significant differences in Ar-Go and Go-Me between the two groups(P>0.05).Conclusion Patients with four third molars are more likely to have backward and downward rotation of the mandible and are more likely to develop into a convex facial type than patients with missing third molars,which has a higher correlation with hyperdivergent growth pattern and convex facial type.