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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Effect of stress relaxation in two different preactivation methods of beta-titanium T-loops: bends vs. continuous curvature

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Author(s):
Fernandes Rabelo Caldas, Sergei Godeiro [1] ; Martins, Renato Parsekian [2] ; de Araujo, Marcela Emilio [1] ; Galvao, Marilia Regalado [1] ; dos Santos Nunes Reis, Jose Mauricio [3] ; Martins, Lidia Parsekian [4]
Total Authors: 6
Affiliation:
[1] UFRN Fed Univ Rio Grande Norte, Dept Dent, Natal, RN - Brazil
[2] UNESP Univ Estadual Paulista, Araraquara Sch Dent, Orthodont Grad Program, Araraquara, SP - Brazil
[3] UNESP Univ Estadual Paulista, Araraquara Sch Dent, Dept Dent Mat & Prosthesis, Araraquara, SP - Brazil
[4] UNESP Univ Estadual Paulista, Araraquara Sch Dent, Dept Pediat Dent, Araraquara, SP - Brazil
Total Affiliations: 4
Document type: Journal article
Source: JOURNAL OF THE WORLD FEDERATION OF ORTHODONTISTS; v. 6, n. 3, p. 98-104, SEP 2017.
Web of Science Citations: 0
Abstract

Objective: Assess the changes in the force system of T-loop springs (TLSs) preactivated by bends and curvature, when secured in place with a constant strain over time. Materials and Methods: A total of 120 TLSs with dimensions 6 x 10 mm, produced out of 0.017 x 0.025-inch TMA, were randomly divided into two groups of 60 TLSs, each according to what preactivation was going to be used, concentrated bends or gradual curvature. Subgroup 1 was tested immediately and the remaining subgroups were tested after they were secured at 5-mm activation for different periods of time in an interbracket distance of 23mm. Subgroups 2, 3, 4, 5, and 6 were kept activated for 24, 48, and 72 hours, 1 and 2 weeks, respectively. Using a moment transducer coupled to a digital extensometer indicator adapted to a universal testing machine, the amount of horizontal force, moment, and moment-to-force (MF) ratios were recorded. Results: Both groups showed a decrease in force levels over time (P < 0.001 and 0.005 for bend and curvature preactivation, respectively), but with different behaviors. The group preactivated by bends showed a reduction in moments over time (P < 0.001), whereas the group preactivated by curvature did not (P = 0.410). The MF ratio has not changed over time in either group. Conclusions: The stress-relaxation effect is more evident on group preactivated by bends. (C) 2017 World Federation of Orthodontists. (AU)

FAPESP's process: 08/07258-5 - Evaluation of the preativactions stability in the Group B titanium molibdenium T-loop springs along three months
Grantee:Lídia Parsekian Martins
Support Opportunities: Regular Research Grants