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Effect of activation and preactivation on the mechanical behavior and neutral position of stainless steel and beta-titanium T-loops.

de Castro SM, Moreira R, Braga AC, Ferreira AP, Pollmann MC - Korean J Orthod (2015)

Bottom Line: 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.Depending on the preactivation distribution, displacement of uprights is higher or lower than the activation, which is a factor to consider in clinical practice.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthodontics, Faculty of Dental Medicine, University of Porto, Porto, Portugal.

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 (0°, 20°, and 40°), gingival distribution (20°), and occlusal-gingival distribution (40°). 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.

No MeSH data available.


Mean moment to force (M/F) ratio values and 95% confidence intervals (CI) according to activation and preactivation in each material (beta-titanium [TMA] and stainless steel [SS]).
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Figure 5: Mean moment to force (M/F) ratio values and 95% confidence intervals (CI) according to activation and preactivation in each material (beta-titanium [TMA] and stainless steel [SS]).

Mentions: The mean M/F ratio values and their respective 95% confidence intervals are illustrated in Figure 5.


Effect of activation and preactivation on the mechanical behavior and neutral position of stainless steel and beta-titanium T-loops.

de Castro SM, Moreira R, Braga AC, Ferreira AP, Pollmann MC - Korean J Orthod (2015)

Mean moment to force (M/F) ratio values and 95% confidence intervals (CI) according to activation and preactivation in each material (beta-titanium [TMA] and stainless steel [SS]).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4524959&req=5

Figure 5: Mean moment to force (M/F) ratio values and 95% confidence intervals (CI) according to activation and preactivation in each material (beta-titanium [TMA] and stainless steel [SS]).
Mentions: The mean M/F ratio values and their respective 95% confidence intervals are illustrated in Figure 5.

Bottom Line: 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.Depending on the preactivation distribution, displacement of uprights is higher or lower than the activation, which is a factor to consider in clinical practice.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthodontics, Faculty of Dental Medicine, University of Porto, Porto, Portugal.

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 (0°, 20°, and 40°), gingival distribution (20°), and occlusal-gingival distribution (40°). 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.

No MeSH data available.