MENEZES, Marco Aurélio de and MUENCH, Antonio. Relative number of free radicals and knoop hardness of composites. Rev Odontol Univ São Paulo [ online]. O objetivo deste trabalho foi avaliar a profundidade de polimerização e a dureza Knoop do compósito restaurador P60 fotoativado por diferentes métodos. cimentados com diferentes materiais; (2) a dureza Knoop de cimentos Palavras-chave: Pino de fibra de vidro, Integridade Marginal, Dureza Knoop, Cimento.

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Instead, one must correlate test results across the multiple hardness tests. Harrington E, Djreza HJ. Type, size, quantity and refraction index of the fillers into composite exert an influence upon light transmission across the material and, consequently, the light attenuation and the depth of cure may be altered 1,2. However, these innovative techniques require further kboop before they can be effectively applied in dental practice. However, the LED demonstrated the lowest depth of cure. At a depth of 3 mm, the LED demonstrated the lowest hardness value, while the continuous light method revealed an intermediate value with no statistical difference from the other methods.

These differences were probably due to the characteristics of each method such as the light intensity, exposure time and heat generated. After opening the matrix, the uncured material was removed with a steel spatula and the polymerized composite was measured using a pachymeter.

Determination of radiation energy emitted by light activation knoip. However, the intermittent light revealed a higher hardness value than the exponential technique.


eFunda: Convert Hardness: Knoop

This energy is calculated as the product of the output of the curing light unit and the time of irradiation and may be termed as energy density. This fact may explain the lower hardness observed at 3 mm depth when LED was used. Am J Knop ;6: The effect of the photopolymerization method on the quality of composite resin. The lower value observed with LED may be due to the low intensity produced by this technique.

Eur J Oral Sci ; Brinell 10 mm Standard kgf.

Converted hardness values should be used for comparative purposes only. Hardness evaluation of a dental composite durfza with experimental LED-based devices. This result may be due to the total amount of energy that reached the material at this depth. Evaluation of depth of cure and Knoop hardness in a dental composite photo-activated using different methods.

The effect of cure rate on the mechanical properties of dental resins. Braz Dent J ; Factors affecting cure at depths within light-activated resin composites. As a result, there is NO direct analytic conversion between hardness measures. The light exposure time was 3 s.

Reduced light energy density decreases post-gel contraction while maintaining degree of conversion in composites. However, characteristics such as composition, light intensity and exposure time can modify the final properties of the material and, thus, restrict the clinical applications. According to these authors, the Apollo 95 E emits less energy in 3 s than do the conventional curing light units. Uno S, Asmussen E.

Dureza Knoop de cimentos de ionômero de vidro indicados para o tratamento restaurador

A bipartite brass matrix 3 mm in diameter X 11 mm in height was filled with the composite and photo-activation was performed using continuous light, exponential light, intermittent light, plasma arc curing PAC or light-emitting diodes LED. Whilst all the photo-activation methods provided depth of cure values that fulfilled the requirements of the ISO 19there were differences observed between the methods at depths greater than 2 mm.


The specimens were then included in self-curing acrylic resin and worn longitudinally and the hardness was measured on the surface and at depths of 1, 2, 3, 4 and 5 mm. According to Sakaguchi and Berge 8maximum light intensity is achieved at 0.

Knoop hardness test

The many hardness tests listed here measure hardness under different experimental conditions e. Composition and batch are reported in Table 1.

However, the depth of cure value was lower than that knoo by methods that employ halogen lamps. Scand J Dent Res ; How to cite this article. The total energy is related to exposure time and light intensity generated by each method, i. The composite was then covered with a polyester strip and pressed with a glass slab to accommodate the material into the matrix.

Optical microscope resolution may limit the application of the Knoop hardness test due to the resulting shallow indentions.

Effect of exposure time on the depth of polymerization of a visible light-cured composite resin.