Avaliação da dureza Knoop de compositos restauradores odontologicos fotoativados por diferentes metodos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Nowadays, the photoactivated composites are the most used esthetic restorative dental materials in dentistry. The advantages of these materials are the control of setting time and esthetic characteristics. Besides that, it?s unnecessary to prepare retentive cavity. Composites shrink during the polymerization reaction and a tension can be induced on restoration/tooth interface. Depending on composite/tooth interface bond strength, gaps can be formed in the restoration margins, leading to the failure of restorative procedure. Besides that, a high degree of conversion is necessary for composites to obtain adequate mechanical properties. The degree of conversion depends on energy density supplied to composites. The effects of energy density in mechanical properties of composites have not been satisfactory proved. In an attempt to improve the knowledge of the photo-activation methods upon the final properties of the restorative composite resins, this research was divided in two works. The first study evaluated the effect of increase on exposure time on Knoop hardness of composites Z250 and Esthet-X, photoactivated using XL2500 halogen light (QTH), Ultrablue Is Light emitting diode (LED) and Apollo 95E plasma arc curing (PAC). The results showed that higher Knoop hardness were produced by the increase on exposure time when LED and PAC were used. For QTH, the increase on exposure time did not produced significant effect. Regarding to light sources, PAC presented lower Knoop hardness than QTH and LED, which did not present significant difference from each other. Knoop hardness at deep layers was lower than superficial layers. The second study verified the influence of irradiance versus exposure time, using the same energy density, on Knoop hardness of Z250 and Esthet-X composites photoactivated using QTH, LED or PAC. The results showed that with intermediate light intensity and exposure times, the highest Knoop hardness were obtained, compared to others photoactivation methods. Composite Z250 presented adequate polymerization (bottom/surface relation above 0.8) up to 2 mm deep using PAC and up to 3 mm using QTH and LED. Esthet-X composite presented adequate polymerization up to 2 mm deep, using LED and PAC and up to 3 mm using QTH

ASSUNTO(S)

composite resins dental materials materiais dentarios resinas compostas

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