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- Glass transition and degree of conversion of a light-cured orthodontic composite
- Universidade Estadual Paulista (UNESP)
- Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
- Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
- Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
- Objective: This study evaluated the glass transition temperature (T(g)) and degree of conversion (DC) of a light-cured (Fill Magic) versus a chemically cured (Concise) orthodontic composite. Material and Methods: Anelastic relaxation spectroscopy was used for the first time to determine the T(g) of a dental composite, while the DC was evaluated by infrared spectroscopy. The light-cured composite specimens were irradiated with a commercial LED light-curing unit using different exposure times (40, 90 and 120 s). Results: Fill Magic presented lower T(g) than Concise (35-84 degrees C versus 135 degrees C), but reached a higher DC. Conclusions: The results of this study suggest that Fill Magic has lower T(g) than Concise due to its higher organic phase content, and that when this light-cured composite is used to bond orthodontic brackets, a minimum energy density of 7.8 J/cm(2) is necessary to reach adequate conversion level and obtain satisfactory adhesion.
- Journal of Applied Oral Science. Bauru-sp: Univ São Paulo Fac Odontologia Bauru, v. 17, n. 6, p. 570-573, 2009.
- Universidade de São Paulo (USP), Faculdade de Odontologia de Bauru
- Orthodontic composite
- Glass transition temperature
- Degree of conversion
- Mechanical spectroscopy
- Infra-red spectroscopy
- Acesso aberto
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