| Objective:This study chose the patients with functional anterior crossbites before growth peak.Then these patients were randomly divided into three groups treated with maxillary protraction and FRⅢand"2×4"appliance separately,compared with self-control and between any two groups.The study analyzed the changes of dental and skeletal before and after treatment to probe their treatment mechanisms and to provide theoretical basis for clinical treatment.Methods:60 patients with anterior crossbites selected from these offered orthodontics treatment in orthodontics department of dental hospital Hebei Medical College,those who were treated with maxillary protraction,FRⅢand"2×4"appliance separately,were randomly divided into three groups,20 per one group. Lateral cephalometric films taken at the beginning (T0),the end of treatment(T1),were analyzed with traditional analysis and Pancherz analysis and SPSS13.0 statistical software.Results:After effective treatment, the abnormal molar relationship and anterior crossbites were corrected. Cephalometric analysis showed that 1 In maxillary protraction group, OJ improved 5.04mm (p<0.001),with 28% skeletal changes and 72% dental changes.Mr improved 3.32mm (p<0.001),with 43% skeletal changes and 57% dental changes.point A moved forward 2.89mm(p<0.001),point P moved forward 1.47mm (p<0.001), palatal plane exhibited counterclockwise rotation of 1.51°(p<0.01), mandibular plane angle increased 0.76°(p<0.05), lower facial height incresed 3.45mm(p<0.001).2 In FRⅢgroup, OJ improves 6.26mm(p<0.001),with 18% skeletal changes and 82% dental changes.Mr increased 1.88mm(p<0.001),with 60% skeletal changes and 40% dental changes.point A moved forward 1.53mm(p<0.001), point P moved forward 0.28mm (p>0.05),palatal plane exhibited clockwise rotation of 0.17°(p>0.05),mandibular plane angle increased 0.57°(p>0.05), lower facial height increased 2.59mm(p<0.001).3 In"2×4"appliance group,OJ improved 5.35mm (p<0.001), with 14%skeletal changes and 86% dental changes. Mr improved 1.23mm(p<0.001),with 63% skeletal changes and 37% dental changes.Point A moved forward 1.96mm (p<0.001),point P moved forward 1.19mm (p<0.001), lower facial height increased 2.27mm(p<0.001).4 The results of cephalometric values of three groups analyzed by S-N-K statistic method4.1 conventional measurement itemThe amount of increase in SNA of maxillary protraction group is greater than that of the other two groups. And there is no statistic difference exhibited between FRⅢgroup and"2×4"appliance group(P<0.001). There are no statistic differences exhibited between any two groups in SNB. The amount of increase in ANB of"2×4"appliance group is greater than that of the other two groups. And there is no statistic difference exhibited between FRⅢgroup and maxillary protraction group(P<0.001). There are no statistic differences exhibited between any two groups in the changes of mandibular plane angle and occlusal plane angle.The amount of labial inclination of maxillary incisor in maxillary protraction group is less than the other two groups(P<0.05),and there is no statistic differences exhibited between the other two groups.4.2 Pancherz measurement item4.2.1 The respect of OJComparison of OJ among there groups(P<0.01),the changes of OJ in FRⅢgroup is greater than that in maxillary protraction group,and there are no statistic differences exhibited between"2×4"appliance group and the other two groups.A in maxillary protraction group move most greater in there groups(P<0.001), there is no statistic difference exhibited the other two groups. P in FRⅢgroup move backward less than other two groups(P<0.01),and there is no statistic difference exhibited the other two groups.Maxillary incisor move forward most greater than other two groups(P<0.05), and there is no statistic difference exhibited the other two groups. 4.2.2 The respect of molar relationComparison of improvement of Mr among there groups(P<0.001),the sequence for the changes of Mr is maxillary protraction group > FRⅢgroup >"2×4"appliance group.and comparison of improvement of maxillary molar is similar with that of Mr. Comparison of amount of mandibular molar forward moving(P<0.001),mandibular molar move forward most greater than other two groups,and there is no statistic difference exhibited the other two groups.4.2.3 Vertical measurement itemThere are no statistic differences among there groups. Conclusion:1 Maxillary protraction, FRⅢand"2×4"appliance can effectively improve the OJ and Mr of functional anterior crossbites.2 In the skeletal changes contribution to the improvement of OJ, order for the three groups is maxillary protraction group >FRⅢgroup>"2×4"appliance group. In the skeletal changes contribution to the improvement of Mr, FRⅢgroup is similar with"2×4"appliance group,and skeletal changes of these two groups is greater than which of maxillary protraction group.The significant improvement of maxillary exhibited in the Maxillary protraction group. The ratio of skeletal changes in overjet correction showed like Maxillary protraction group> FRⅢgroup>"2×4"appliance group.In FRⅢgroup and"2×4"appliance group,Mr correction improved mainly by the skeletal changes, but in Maxillary protraction group the skeletal changes and the dental changes are similarly the same.3 In the clinical treatment, according to the actual situation of patients, we can choose the appropriate therapy for the correction of functional anterior crossbites.
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