The comparison of space closure rate between conventional and passive self-ligating system using elastomeric chain in maxilla

The effectiveness of orthodontic treatment during en-masse space closure is investigated between passive self-ligating system and conventional system. prospective randomized controlled clinical trial with a split mouth design is carried out for 11 months. eleven subjects (3 men and 8 women with age minimum of 15 year old) with extraction of first premolars,who have completed leveling and aligning stage,are included in this study. each subject is bonded with conventional bracket on one side of the arch and with passive self - ligating on the other side,which has determined randomly,and is given a force of 150 g with power chain on .019 x .025 ss wire. the measurement of en-masse space closure rate and amount of anchorage loss are performed at t0,t1 (4 weeks),and t2 (8 weeks). a pair student's t-test and a wilcoxon test are carried out to analyze the data statistically. there is significant difference of the average rate of closing space between passive self-ligating system and conventional system group (p = 0.01),for which a group of passive self-ligating system has a greater speed compare to conventional group,though there is no difference of the anchorage demands between the two groups. the passive self-ligating system has more rapid space closure rate,which might relate to shorter duration of orthodontic treatment.