ABSTRACT
Ligating between brackets and orthodontic wire is considered one of the important factor affecting the frictional resistance during sliding movements. For these reasons this investigation aimed to compare the friction associating with sliding movement for two types of brackets: self-ligating brackets and conventional brackets ; along stainless steel arch wires. 40 first upper premolar brackets made from stainless steel were tested, 20 of them were self-ligating brackets [Quick brackets] and the rest were conventional [Sprint brackets] with elasting ligature; all of the 40 brackets were tested with two different sizes of stainless steel wires. The frictional resistance was recorded during the tests by instron machine designed specially for this reason. The results showed significant decrease in the magnitude of friction with the self-ligating brackets compared with the conventional one; whatever the orthodontic wire using in the test. This study recommend the importantance of choose the proper type of brackets and the used technique for each orthodontic treatment; and suggest the need of more scientific investigations aiming to know the frictional property of modern types of brackets in the markets
ABSTRACT
The purpose of this study is to evaluate the effects of laceback ligatures on the anteroposterior and vertical position of the upper incisors and the mesial position of the upper first molars during the alignment and leveling stage of orthodontic treatment of Class II Division 1 cases which require extraction of upper first premolars. This study was Randomized controlled trial [RCT]. The sample of this study comprised 44 subjects who showed Class II Division 1 malocclusion, and needed extraction of upper first premolars. Subjects were randomly allocated to two study groups. Patients in the first group received Laceback ligature treatment. In the control group, subjects were treated without the application of Laceback ligature. The insertion of rectangular steel arch wires [0.16x0.16] without an exaggerated curve and without generating excessive forces was considered the end of the alignment and leveling stage. All subjects were followed-up and lateral, anterioposterior cephalometeric x-rays were taken before the treatment and by the end of the alignment and leveling stage to detect any changes in the craniofacial complex. The statistical comparison between the laceback group and the control group revealed the following The angle I
N decreased by [4.66°, 2.66°] in the Laceback and control groups, respectively. The distance from I to A-Pog decreased by [1.39 mm, 1.02mm] respectively. The distance distal 16 to line from distal PTM perpendicular to SN plane increased by [0.27mm, 0.60mm] respectively. The distance of distal 26 to line from distal PTM perpendicular to SN plane increased by [0.17mm, 0.66mm] respectively. As well as the distance from I to SN increased by [0.57mm, 0.57mm] respectively. The outcome of this study could lead to the conclusion that Lacebak ligature causes a slight canine retraction followed by incisors retraction. The use of laceback ligatures conveys no statistical or clinical difference in the loss of posterior anchorage, or vertical position of the upper incisors. The use of laceback ligatures decreases the amount of canine retraction and anchorage at next stages