| Objective: This retrospective study aimed to put Discrepancy Index(DI)into use to evaluate the early orthodontic treatment outcome of malocclusions in mixed dentition quantificationally,and to analyze the results in detail.Materials and Methods: This clinical analysis was performed at the Department of Stomatology,Children's Hospital affiliated to Zhejiang University School of Medicine.32 patients(21 boys,11 girls,the initial average age is 7.91±1.44)diagnosed as malocclusion in mixed dentition were included in this study,from March 2015 to March 2020.All their models,panoramic radiographs and cephalometric radiographs before and after the treatment were analyzed using DI.A total of 87 children with malocclusion in mixed dentition were diagnosed at the Department of Stomatology,Children's Hospital affiliated to Zhejiang University School of Medicine from March 2015 to March 2020.According to the inclusion criteria,32 patients(21 boys and 11 girls,the initial average age is 7.91 ±1.44)were included.DI index was used to measure and analyze the oral model,panoramic radiographs and cephalometric radiographs of these patients at the first visit and at the end of orthodontics.And the differences before and after orthodontic treatment were compared.Results:1?The average DI after early orthodontic treatment was significantly lower than that before by 3.94 points(P<0.0001).Among them,the overjet scores,crowding scores and other scores after treatment were significantly reduced by 1.72 points(P<0.0001),0.63 points(P<0.5)and 0.68 points(P<0.05)respectively.However,there were no statistically significant changes among the scores of overbite,anterior open bite,lateral open bite,occlusal relationship,posterior lingual crossbite,posterior buccal crossbite,ANB,SN-MP and IMPA before and after the treatment.2?After early orthodontic treatment,the measured value of SN-MP increased by 0.72°(P<0.05),and the measured value of IMPA decreased by 3.38 °(P<0.01).However,there was no statistical difference in the measured values of ANB before and after treatment.3?After early orthodontic treatment,the average DI index of Angle Class I malocclusion decreased by 3.22 points(P < 0.05),and the overjet score decreased by 2.00 points(P<0.01).4?After early orthodontic treatment,the average DI index of Angle Class ? malocclusion decreased by 4.09 points(P<0.05),and the score of occlusal relationship decreased by 1.46 points(P<0.05).5?After early orthodontic treatment,the average DI index of Angle Class ? malocclusion decreased by 4.33 points(P < 0.05),and the overjet score decreased by 2.33 points(P<0.05).Conclusions:1?Generally speaking,early orthodontic treatment in mixed dentition can improve the malocclusion to some extent,and the overjet is more obvious.It can also effectively improve the vertical relationship of the jaws and the inclination of the long axis of the lower incisors.2?Early orthodontic treatment has different effects on the improvement of Angle classification malocclusion,in which the overjet of Angle Class ? malocclusion and Angle Class ? malocclusion is improved obviously,and the occlusal relationship of Angle Class ? malocclusion is improved obviously.Among them,the improvement of Angle Class III malocclusion is the most significant,which can reduce the difficulty of follow-up treatment.3?DI index can be used as an evaluation method for early orthodontic treatment of malocclusion in mixed dentition,and provide a reference for the selection of types of malocclusion in early orthodontic treatment. |
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