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ortho - the international C.E. magazine of orthodontics

I 09ortho 1_2014 C.E. article_ self-ligating systems I The efficiency of an interactive system of self- ligating brackets is directly related to the uniformity and continuity of the spring clip activity over time. Excessive loss of force brings clinical difficulties duringthetreatmentphasesthatrequiretheutiliza- tion of rectangular-geometry archwires, such as the space closure and the finishing stage. Therefore,fromtheclinicalpointofview,themost important data is the difference between the aver- ages of steps Nos. 1 and 3 of the test (Table 4). Through the test T at the level of significance of 5 percent, we can verify that for the majority of the groups, the means scores M1 were significantly big- ger than M3, which means that there is always some lack of effectiveness of the spring clips, regardless of brand. When the calculated p value (minimum signifi- cance level) allowed rejection of the nullity hypoth- esis,anasterisk(*)wasusedtodenotethis.Thenullity hypothesis was rejected only on the In-Ovation C group, which showed no statistical difference between M1 and M3. This situation reflects a better mechanical stability of its spring clips. Among the metallic self-ligating brackets, the mean score for step No. 3 (M3) was the highest for theIn-OvationRgroup.ThegroupEmpowersuffered the greatest loss of tension, generating the lowest strength. The BioQuick group performed intermedi- ate values at the end of the third moment of the test (M3).Inthechart(Table5),itispossibletoobserveand comparethemeanscoresforstepsNos.1and3ofthe test for each group of brackets. ConsideringthedifferencesingF(gramsofforce) between the moments M1 and M3 (Table 6), the highest loss in terms of force magnitude between the metallic accessories after a 20 N load during two hours was shown by the BioQuick group (82.5 gF), quitesimilartotheEmpowergroup(80.9gF).Thebest performance(lowestlackofstrength)waspresented by the In-Ovation R group (33.6 gF). Among the esthetic brackets, the highest loss of magnitude of force was shown by the QuickKlear group (77.8 gF), while the group In-Ovation C pre- sented the lowest (27.5 gF). _Conclusion Fromtheaboveresults,wecandrawthefollowing three conclusions: • It’s important for clinicians to understand that the main component of an interactive self-ligation systemisthespringclip,whichissupposedtoprovide flexibility and resilience along the treatment time. Therefore, the choice among the different brands offered by the current market should be focused on this point. • The spring clips of the interactive self-ligating brackets are not free from loss of force exertion Table 6_The magnitude of force loss for each of the brackets. Table 6

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