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目的:采用遗传算法(GAS)优化不同类型错患者矢状向颅面结构关系方程的参数,探讨其是否具有规律性。方法:选取均角型错患者240例,年龄8~18岁,分为安氏Ⅰ类组79例,安氏Ⅱ类组76例,安氏Ⅲ类组85例。每组随机选取10例为检验样本,其余为实验样本,实验样本用于获得GAS优化方程,检验样本用于误差分析。对所有患者的头颅侧位片进行头影测量分析,对各组测量参数[全颅底深度(Ba-N)、面中部深度(Ba-A)、颅底深度(Ba-S)、上颌后部深度(S-Ptm)、上颌骨基骨长度(Ptm-A)、下颌关节相对于颅底的距离(Ba-Ar)、下颌升支长度(Ar-Go)、下颌骨体长度(Go-PoG)、下面部深度(Ba-PoG)及颅底角(N-SAr)]进行独立样本t检验、单因素方差分析和逐步回归分析,识别颅面结构的相关影响因子;采用GAS优化方程参数获得相关方程,将优化方程预测值和实测值进行比较。结果:安氏Ⅰ类、Ⅱ类和Ⅲ类组内比较,不同性别间各参数差异无统计学意义(P>0.05),将同一类型不同性别组合并进行比较,Ba-A、Ptm-A、Ar-Go和Ba-PoG差异有统计学意义(P<0.05)。相关分析,安氏Ⅰ类组,Ba-A与Ba-N呈正相关关系(r=0.683),Ptm-A与Go-PoG呈正相关关系(r=0.738),Ar-Go与Ba-PoG呈正相关关系(r=0.833)、与Go-PoG呈负相关关系(r=-0.560),Ba-PoG与Go-PoG呈正相关关系(r=0.669);安氏Ⅱ类组,Ba-A与Ba-PoG和Ba-N呈正相关关系(r=0.884,r=0.883),Ptm-A与Ba-A呈正相关关系(r=0.742),Ar-Go与Ba-PoG呈正相关关系(r=0.401)、与Go-PoG呈负相关关系(r=-0.317),Ba-PoG与Ba-A和Go-PoG呈正相关关系(r=0.883,r=0.488);安氏Ⅲ类组,Ba-A与Ba-N和Ba-PoG呈正相关关系(r=0.891,r=0.829),Ptm-A与Ba-A呈正相关关系(r=0.807)、与Ba-S呈负相关关系(r=-0.404),Ar-Go与S-Ptm呈正相关关系(r=0.548),Ba-PoG与Ba-A呈正相关关系(r=0.829)。使用GAS建立了不同错类型矢状向颅面结构的关系方程。安氏Ⅰ类,Ba-A(mm)=10.963 9+0.859 8×Ba-N,Ptm-A(mm)=6.897 6+0.557 0×Go-PoG,Ar-Go(mm)=-2.548 2+0.511 8×Ba-PoG-0.527 2×Go-PoG,Ba-PoG(mm)=17.515 6+1.021 3×GO-POG;安氏Ⅱ类,Ba-A(mm)=-2.121 3+0.567 6×Ba-PoG+0.513 2×Ba-N,Ptm-A(mm)=13.788 7+0.349 4×Ba-A,Ar-Go(mm)=2.447 7+0.368 8×Ba-POG-0.427 9×Go-PoG,Ba-PoG(mm)=-7.140 2+0.751 3×Ba-A+0.295 4×Go-PoG;安氏Ⅲ类,Ba-A(mm)=3.281 0+0.545 3×Ba-N+0.394 4×Ba-PoG,Ptm-A(mm)=3.535 8+0.631×Ba-A-0.614 2×Ba-S,Ar-Go(mm)=-9.002 1+1.004 3×S-Ptm,Ba-PoG(mm)=-2.091 2+1.057 5×Ba-A。GAS建立的方程预测值与实测数据比较差异无统计学意义(P>0.05)。结论:采用GAS建立了矢状向错颅面结构的优化关系方程,且其定量具有规律性。
OBJECTIVE: To optimize the parameters of sagittal craniofacial structure equation in patients with different types of malocclusions by genetic algorithm (GAS), and discuss whether they have regularity. Methods: A total of 240 patients with mean angle malocclusion were enrolled in this study. They were aged 8 to 18 years. They were divided into Class Ⅰ group (79 cases), Class Ⅱ group (76 cases) and Class Ⅲ group (85 cases). Each group randomly selected 10 samples for the test, the rest for the experimental sample, the experimental sample was used to obtain GAS optimization equation, the test sample for error analysis. The cephalometric images of all the patients’ cephalometric films were obtained. The measurement parameters such as Ba-N, Ba-A, Ba-S, S-Ptm, Ptm-A, Ba-Ar, Ar-Go, Go- PoG, Ba-PoG and N-SAr] .Through independent t test, one-way ANOVA and stepwise regression analysis, the correlation factors of craniofacial structure were identified. The parameters of GAS optimization equation Obtained the correlation equation, the optimization equation predicted values and measured values were compared. Results: There were no significant differences among different genders in Class Ⅰ, Group Ⅱ and Group Ⅲ (P> 0.05). The genotypes of Ba-A, Ptm-A, The difference between Ar-Go and Ba-PoG was statistically significant (P <0.05). There was a positive correlation between Ba-A and Ba-N (r = 0.683), Ptm-A and Go-PoG (r = 0.738) (R = -0.560). There was a positive correlation between Ba-PoG and Go-PoG (r = 0.669) There was a positive correlation between PoG and Ba-N (r = 0.884, r = 0.883). There was a positive correlation between Ptm-A and Ba-A There was a positive correlation between Ba-PoG and Ba-A and Go-PoG (r = 0.883, r = 0.488) (R = 0.891, r = 0.829). There was a positive correlation between Pt-A and Ba-A (r = 0.807) There was a positive correlation between Ar-Go and S-Ptm (r = 0.548) and a positive correlation between Ba-PoG and Ba-A (r = 0.829). The use of GAS established a different type of wrong type of sagittal craniofacial relationship equation. Class I, Ba-A = 10.963 9 + 0.859 8 × Ba-N, Ptm-A mm = 6.897 6 + 0.557 × Go-PoG, Ar-Go mm = 0.511 8 × Ba-PoG-0.527 2 × Go-PoG, Ba-PoG (mm) = 17.515 6 + 1.021 3 × GO-POG; Ba-PoG + 0.513 2 × Ba-N, Ptm-A (mm) = 13.788 7 + 0.349 4 × Ba-A Ar- Go = 2.447 7 + 0.368 8 × Ba-POG- 0.427 9 × Go- PoG, Ba-PoG (mm) = - 7.140 2 + 0.751 3 × Ba-A + 0.295 4 × Go-PoG; 4 × Ba-PoG, Ptm-A (mm) = 3.535 8 + 0.631 × Ba-A-0.614 2 × Ba-S and Ar-Go (mm) = -9.002 1 + 1.004 3 × S-Ptm, Ba-PoG (mm) = - 2.091 2 + 1.057 5 × Ba-A. The predictive value of the equation established by GAS and the measured data showed no significant difference (P> 0.05). Conclusion: The optimal relationship equation of sagittal craniofacial structure was established by GAS, and its regularity was quantitative.