Effect of activation and preactivation on the mechanical behavior and neutral position of stainless steel and beta-titanium T-loops
Castro Saul Matos de, Moreira Rui, Braga Ana Cristina, Ferreira Afonso Pinhao, Pollmann Maria Cristina,
소속 상세정보
( Castro Saul Matos de ) - University of Porto Faculty of Dental Medicine Department of Orthodontics
( Moreira Rui ) - University of Aveiro Department of Mechanical Engineering
( Braga Ana Cristina ) - University of Minho School of Engineering Department of Production and Systems Engineering
( Ferreira Afonso Pinhao ) - University of Porto Faculty of Dental Medicine Department of Orthodontics
( Pollmann Maria Cristina ) - University of Porto Faculty of Dental Medicine Department of Orthodontics
KMID : 0361920150450040198
Abstract
Objective: To quantify, for each activation, the effect of preactivations of differing distribution and intensity on the neutral position of T-loops (7-mm height), specifically the horizontal force, moment to force (M/F) ratio, and load to deflection ratio.
Methods: A total 100 loops measuring 0.017 × 0.025 inches in cross-section were divided into two groups (n = 50 each) according to composition, either stainless steel or beta-titanium. The two groups were further divided into five subgroups, 10 loops each, corresponding to the five preactivations tested: preactivations with occlusal distribution (0o, 20o, and 40o), gingival distribution (20o), and occlusal-gingival distribution (40o). The loops were subjected to a total activation of 6-mm with 0.5-mm iterations. Statistical analysis was performed using comprised ANOVA and Bonferoni multiple comparison tests, with a significance level of 5%.
Results: The location and intensity of preactivation influenced the force intensity. For the M/F ratio, the highest value achieved without preactivation was lower than the height of the loop. Without preactivation, the M/F ratio increased with activation, while the opposite effect was observed with preactivation. The increase in the M/F ratio was greater when the preactivation distribution was partially or fully gingival.
Conclusions: Depending on the preactivation distribution, displacement of uprights is higher or lower than the activation, which is a factor to consider in clinical practice.
키워드
Neutral position; Preactivation; T-loop
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