A Cephalometric Comparison Of Treatment Effects In Patients Of Class ? Division 1 With Overbite Treated With The Step-shaped Vertical Closing Loop

Objective:The aim of this study was to cephalometrically evaluate treatment effects in patients of Class ? Division 1 with deep overbite,treated by the step-shaped vertical closing loop,and to provide reference for clinical application.Method:This study included 28 adult patients of Class ? Division 1 with overbite and designed to extract the four first premolars or the two maxillary first premolars and the two mandibular second premolars,16 patients treated with the step-shaped vertical closing loop,and the others treated with the vertical closing loop.Pre-and posttreatment lateral cephalometric radiographs were collected,and 22 measurements were recorded.Independent t test was used for the pre-and posttreatment comparison among the two Divisions.Paired t tests were used to evaluate the treatment changes within each group.Results:1.There was no significant difference in the soft tissue,the retraction of upper incisors and the position of the maxillary first molars before and after treatment between the two groups(P<0.05).2.After treatment,the changes in the center of resistance of the incisors were(1.73 ± 0.74)mm for group A and(1.04 ± 0.41)mm for group B;the difference between the groups was significant(P <0.05).Conclusions:1.The frontal and profile of the soft tissue could be improved to a great extent after the treatment of the two vertical closing loop.2.Compared with the tradional closing loop,the step-shaped vertical closing loop has a better effect on the maxillary incisor intrusion.