Qualitative photoelastic study of the force system produced by retraction T-springs with different preactivations

Admin Dental Press

Edition V15N04 | Year 2010 | Editorial Article | Pages 103 to 116

Luiz Guilherme Martins Maia , Vanderlei Luiz Gomes , Ary Dos Santos-pinto , Itamar Lopes Júnior , Luiz Gonzaga Gandini Jr

Objective: Evaluate the force system produced by the T-spring used for space closure. Methods: By means of the experimental photoelastic method, we evaluated the Tspring—used for space closure—with two different preactivations on its apical portion, i.e., one with 30° and one with 45º. The springs were fabricated with rectangular 0.017 X 0.025-in titanium-molybdenum alloy (TMA), centered in a 27.0 mm interbracket space and activated at 5.0 mm, at 2.5 mm, and in a neutral position. For more reliable results, tests were repeated on three photoelastic models duplicated and prepared by the same operator. To better understand the results, the fringes seen in the polariscope were photographed and analyzed qualitatively. Results: Through qualitative analysis of the fringes order in the photoelastic model it was noted that at the retraction and anchoring ends the T-spring with 30° apical activation showed a slightly greater accumulation of energy relative to the force system that was generated.

Closing of orthodontic space, T loop, Photoelastic study, Retraction,

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