Abstract
To compare hysteresis, activation and deactivation forces produced by first-order deformation of Contour 0.014-in NiTi wire (Aditek, Brazil) in four brands of self-ligating brackets: Damon MX, Easy Clip, Smart Clip and In-Ovation. Activation and deactivation forces were measured in an Instron universal tensile machine at 3 mm/minute speed to a total displacement of 4 mm. Tests were repeated eight times for each bracket/wire combination. Statistical analysis comprised ANOVA and Tukey's multiple comparisons test. Using a 4-mm deformation, mean activation forces increased in the following order: Damon = 222 gf, Easy Clip = 228 gf, In-Ovation = 240 gf and Smart Clip = 306 gf. The same order was observed for mean hysteresis values, i.e., 128 gf, 140 gf, 150 gf and 206 gf, respectively. The respective values of deactivation forces for the Damon, Easy Clip, In-Ovation and Smart Clip brackets were 94 gf, 88 gf, 90 gf and 100 gf. Brackets with higher activation forces were accompanied by higher hysteresis values, which resulted in clinically similar deactivation forces, regardless of the type of self-ligating brackets used.
Highlights
MATERIAL AND METHODS A device attached to the Instron universal tensile machine comprising five 0.022 x 0.028-in brackets was used to compare the activation and deactivation forces produced by four types of self-ligating brackets: Damon MX (Ormco), Easy Clip (Aditek), In-Ovation (GAC) and Smart Clip (3M/Unitek)
A previous study[14] found that a 4 mm horizontal deformation of the Contour 0.014-in NiTi wire produced significantly different friction forces between self-ligating brackets, with values increasing in the following order: Damon, Easy Clip, In-Ovation and Smart Clip
When subjected to 4 mm standardized horizontal deformations, the Contour 0.014-in NiTi archwire exhibited increasing activation forces in the same sequence found for friction forces between self-ligating brackets: Damon, Easy Clip, In-Ovation and Smart Clip
Summary
A device attached to the Instron universal tensile machine comprising five 0.022 x 0.028-in brackets (central incisor, lateral incisor, canine, first and second premolars in the upper left quadrant) was used to compare the activation and deactivation forces produced by four types of self-ligating brackets: Damon MX (Ormco), Easy Clip (Aditek), In-Ovation (GAC) and Smart Clip (3M/Unitek).Rino Neto J, Queiroz GV, Paiva JB, Ballester RYThe canine bracket was bonded with light-curing resin in the following order (Fig 3):» Insertion of 0.021 x 0.025-in rectangular stainless-steel wire into the bracket slot and stabilization with conventional elastomeric ligatures.» Insertion of the same rectangular wire into the previously bonded brackets with the canine bracket at an equidistant position to the adjacent brackets (Fig 3A).» Application of composite resin to the support attached to the Instron machine (Fig 3B).» The support was raised until it touched the bracket, proceeding with curing of composite resin (Fig 3C).This procedure sequence ensured parallelism between the slot of the canine bracket, attached directly to the Instron machine, and the slots of the four brackets bonded to the cylinders.A straight segment of Contour NiTi wire (Aditek) with round 0.014-in cross-section and 12 cm length was employed in all mechanical tests. The canine bracket was bonded with light-curing resin in the following order (Fig 3):. » Application of composite resin to the support attached to the Instron machine (Fig 3B). » The support was raised until it touched the bracket, proceeding with curing of composite resin (Fig 3C). This procedure sequence ensured parallelism between the slot of the canine bracket, attached directly to the Instron machine, and the slots of the four brackets bonded to the cylinders. The superelastic Contour NiTi wire, classified as active austenitic, was stabilized inside the slots by means of the lids or clips (ligation device) of the self-ligating brackets. A comparison between activation and deactivation forces performed at 4 mm deformation during inferior displacement of the canine bracket, which simulated a lingual canine placement and a first order deformation
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