ABSTRACT
Objective@# By analyzing changes of dental arch width and length during the aligning and leveling period (non-extraction case) with two kinds of self-locking bracket, compare the difference between the active self-locking bracket with the passive bracket.@*Methods@#The data of dental arch perimeter change amount and dental arch width and length change amount (WU/L3, WU/L4, WU/L5, WU/L6, U/LL) were statistically analyzed using the correlation and regression method by comparing active and passive brackets for the correction of dental arch variations. Two different brackets for the correction of the measured values of the dental arch variations was analyzed by t-test. Results There were statistical relationships between the amount of arch perimeter increase and the amount of width and length increase. The regression equation was statistically significant (P < 0.05), It was greater impacted arch width increase to arch perimeter in the self-locking. The t-test results showed WU3, WL3, WL6, LR 4 measured values (P < 0.05) statistically significant in the active self-locking group and passive group. @*Results @#There were statistical relationships between the amount of arch perimeter increase and the amount of width and length increase. The regression equation was statistically significant (P < 0.05), It was greater impacted arch width increase to arch perimeter in the self-locking. The t-test results showed WU3, WL3, WL6, LR 4 measured values (P < 0.05) statistically significant in the active self-locking group and passive group. @*Conclusin @#Active and passive self-locking bracket have good arch expansion effecting. The active self-locking bracket is slightly dominant than the passive bracket in the expansion of the canine width whereas the active self-locking bracket is better than the passive in the expansion of the mandibular first molar and arch perimeter which should be widely applied to the appropriate cases.