The Changes in Dentofacial Structures and the Correlation between Soft and Hard Tissue Changes after Orthodontic Treatment with Four Premolars Extraction

Objective To investigate the change in dentofacial structures and the correlation between the soft and hard tissue changes after four premolars extraction and straight wire appliance treatment.Methods The soft and hard tissue changes were measured for 30 four-premolar-extracted patients by cephalometrics,and data were analyzed by multiple regression analysis.Results The soft and hard tissue changes were significantly correlated(P0.05),and the ratio between them was revealed.Conclusion The soft and hard tissue changes were created by permolar-extracted orthodontic treatment and also,the soft tissue changes were correlated with the hard tissue changes.