A Meta Analysis: The Morphological Characteristics Of Class Ⅱ Division 2 Malocclusion

Objective.To evaluate the differences in jaw morphological characteristics of Class II division 2 malocclusion with normal occlusion systematically,and to provide the referential basis for orthodontic clnical doctors diagnosing and treating this malocclusion.Method:The PubMed、Medin、Embase、CBM、CNKI、WanFang、 CBM、 VIP were earched for collecting relevant trails in English or Chinese from establishment dates with manual retrieval.The included and excluded criteria is stablished by two authors.Then the two authors select the trails、 extract data and evaluate quality according to the criterias.Agency for Healthcare Research and Quality (AHRQ) recommends the 11 enties for quality evaluation. The software Statal2.0 is used to performe the meta analysis.The funnel plot is used to determine the literature publication bias.WMD(weighted mean difference)is selected for the effective size.Results:There are 13 sudties to be included,and all are control studies between Class Ⅱ division 2 malocclusion and normal occlusion.There are 6 studies about dental arch width.The number of Angle Class Ⅱ division 2 malocclusion are 637 patients,and the number of normal occlusion are 623 patients.1.The results of meta analysis find that there is no statistical significant difference in U33 between Class Ⅱ division 2 malocclusion and normal occlusion.(WMD=0.23,95%CI[-0.33,0.78],P=0.422),but mid heterogeneity is dected(I2=61.6%,p=0.023);there is statistical significant difference in U44 between two groups(WMD=-2.13,95% CI[-2.58,-1.68],P=0.000),and no significant heterogeneity is dected(I2=26.0%,p=0.248);there is no statistical significant difference in U66 between two groups(WMD=-0.54,95%CI[-1.76,0.69],P=0.392),but high heterogeneity isdected(I2=84%,p=0.000);there is no statistical significant difference in L44(WMD=-2.59,95% CI[-6.02,0.84],P=0.000),but high heterogeneity is dected(I2=98.6%,p=0.000);there is statistical significant difference in L66(WMD=-0.96,95%CI[-1.79,-0.14],P=0.000),but high heterogeneity is dected(I2=69.4%,p=0.006).2.The results of meta analysis find that there is statistical significant difference in N-Me between Class Ⅱ division 2 malocclusion and normal occlusion(WMD=-4.69,95%CI[-6.72,-2.65],P=0.000),and no significant heterogeneity is dected(I2=46.3%,p=0.155);there is statistical significant difference in ANS-Me between Class Ⅱ division 2 malocclusion and normal occlusion(WMD=-3.28,95%CI[-5.80,-0.76],P=0.000),but high heterogeneity is dected(I2=80.8%,p=0.001);there is statistical significant difference in Go angle between Class Ⅱ division 2 malocclusion and normal occlusion(WMD=-4.2,95%CI[-6.09,-2.31],P=0.000),but mid heterogeneity is dected(I2=72.6%,p=0.001);there is statistical significant difference in FMA angle between Class Ⅱ division 2 malocclusion and normal occlusion.(WMD=-2.99,95%CI[-4.26,-1.72],P=0.000),and no significant heterogeneity is dected(I2=55.8%,p=0.104).3.The results of meta analysis find that there is no statistical significant difference in SNA angle between Class Ⅱ division 2 malocclusion and normal occlusion.(WMD=0.23,95%CI[-0.33,0.78],P=0.422),and no significant heterogeneity is dected(I2=40.4%,p=0.110);there is statistical significant difference in SNB angle between the two groups(WMD=-2.17,95% CI[-2.92,-1.43],P=0.000),but mid heterogeneity is dected(I2=63.1%,p=0.006);there is statistical significant difference in ANB angle between the two groups(WMD=2.15,95%CI[1.74,2.55],P=0.000),and no heterogeneity is dected(I2=0.0%,p=0.587);there is no statistical significant difference in Go-Me or Go-Gn between the two groups(WMD=-1.61,95%CI[-3.30,0.09],P=0.000),but high heterogeneity is dected(I2=78.0%,p=0.000);there is statistical significant difference in Pog-NB between Class Ⅱ division 2 malocclusion and normal occlusion(WMD=1.04,95%CI[0.60,1.48],P=0.000),but mid heterogeneity is dected(I2=63.0%,p=0.019).Conclusion:1.The meta analysis results show:comparing Class Ⅱ division 2 malocclusion with normal occlusion,U33、U66 and L44 are similar;but U44、L33 and L66 are smaller in Class Ⅱ division 2 malocclusion than in normal occlusion.2.In Class Ⅱ division 2 malocclusion,the low facial height growth is deficient; but the mandibular plane and mandibular angle are also more flat.3.Comparing Class Ⅱ division 2 malocclusion with normal occlusion, there is no obvious difference in maxillary base point and mandiblular body length;but in Class Ⅱ division 2 malocclusion,the mandibular base point and the mandible are more retracted;but the chin is more protruded.