Glass transition and degree of conversion of a light-cured orthodontic composite
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Data
2009-11-01
Autores
Sostena, Michela M. D. S. [UNESP]
Nogueira, Renata A. [UNESP]
Grandini, Carlos Roberto [UNESP]
Moraes, João Carlos Silos [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade de São Paulo (USP), Faculdade de Odontologia de Bauru
Resumo
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.
Descrição
Palavras-chave
Orthodontic composite, Glass transition temperature, Degree of conversion, Mechanical spectroscopy, Infra-red spectroscopy
Como citar
Journal of Applied Oral Science. Bauru-sp: Univ São Paulo Fac Odontologia Bauru, v. 17, n. 6, p. 570-573, 2009.