|
KMID : 0361920150450040198
|
|
Korean Journal of Orthodontics
2015 Volume.45 No. 4 p.198 ~ p.208
|
|
|
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
|
|
|
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.
|
|
|
KEYWORD
|
|
|
Neutral position, Preactivation, T-loop
|
|
|
FullTexts / Linksout information
|
|
  
|
|
|
Listed journal information
|
|
  
|
|