Abstract: Abstract：　Objective　Through the measurement and analysis of the three-dimensional digital model before and after orthodontic treatment,explore the effect of leveling curve of Spee on the shape of dental arch. Methods　Forty-two patients aged 11 to 13 years old at first diagnosis were selected from the Department of Orthodontics of the Affiliated Stomatological Hospital of Harbin Medical University from 2014 to 2019. According to the depth of the Spee before treatment,the subjects were divided into two groups.Statistical analysis was performed on the measured values before and after treatment in each group.Correlation analysis and regression analysis was done in order to study the related factors of leveling curve of Spee. Results　After the curve of Spee was leveled, the arch width,the arch length and the existing arch length were significantly increased.The deeper the curve of Spee, the more obvious the change.Person correlation analysis showed that the leveling curve of Spee was significantly correlated with the arch width, the arch length and the existing arch length. Conclusions　The levelling curve of Spee will change the shape of the arch,which will increase the width,length and length of the existing arch.The deeper curve of Spee,the more obvious the shape change of the arch.

Key words: curve of Spee, dental arch form, digital model