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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The intermittent light demonstrated the highest depth of cure 6. Effect of light intensity and exposure duration on cure of resin composite. The PAC method employs a different technology in which the light is produced by two electrodes that are placed very close to each other, emitting light when a high voltage is applied rather than by heating a tungsten khoop as a halogen lamp The composite was placed in a bipartite brass matrix that presented a central opening of 3 mm in diameter and 11 mm in height.

It seems that the intermittent method was able to provide a higher amount of energy at this depth, probably due to intermittence itself, where the maximum intensity is achieved at 0. The resulting indentation is shaped like the diamond tool, with a long-to-short axis ratio of 7: At this depth, the continuous light method presented an intermediate value and was no different from the intermittent and exponential methods.

The Knoop hardness test showed that, up to a depth of 2 mm, all photo-activation methods provided similar values. Effect of light wavelength on polymerization of light-cured resins. Optical microscope resolution may limit the application of the Knoop hardness test due to the resulting shallow indentions. However, the depth of cure value was lower than that obtained by methods that employ jnoop lamps. At a depth of 5 mm, the LED and the PAC methods could not be evaluated since they did not achieve a depth of fureza of 5 mm.

At this depth, the continuous light method presented an intermediate value with no statistical difference from the other methods. The aim of this study was to evaluate the depth of cure and Knoop hardness in the P60 composite resin photo-activated using different methods. 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.


Dent Mater J ; This result demonstrates that despite the particular characteristics of each method, the light intensity and the exposure time were enough to adequately polymerize this thickness of composite. Evaluation of depth of cure and Knoop hardness in a dental composite photo-activated using different methods.

Brinell 10 mm Tungsten kgf. Polymerization contraction and conversion of light curing Bis-GMA-based methacrylate resins. The calculator curve-fits multiple hardness data onto a common polynomial basis and then performs an analytic conversion.

However, these innovative techniques require further investigation before they can be effectively applied in dyreza practice. Cordless Dreza curing unit. Furthermore, the continuous light method demonstrated no difference from exponential light and PAC methods.

Reduced light energy density decreases post-gel contraction while maintaining degree of conversion in composites. Determination of radiation energy emitted by light activation units. At 3 mm, the LED method presented the lowest value and the continuous light technique demonstrated an intermediate value and was statistically similar to the other methods.

Influence of light intensity on polymerization shrinkage and integrity of restoration-cavity interface. Before these methods can be clinically applied, the final properties of the photo-activated composites must be evaluated. Conversely, the intermittent light method employs 2 s of light exposure followed by 2 s without knoop, meaning that the maximum light intensity peak is achieved every time that the light is emitted.

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, mnoop 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. With respect to the organic matrix, the nature of the involved monomer molecules and the degree of conversion obtained in composite resin has an important effect upon mechanical properties 3where the higher degrees of cure will improve the final properties of the material.


Knoop hardness test

Knoop indentations are about 2. Brinell 10 mm Standard kgf. This fact may explain the lower hardness observed at 3 mm depth when LED was used.

Scand J Dent Res ; The intermittent light method had the highest depth of cure 6. Effect of the photo-activation method on polymerization shrinkage of restorative composites.

Despite this scattering and absorbance of light, all other methods supplied higher amounts of energy to the composite and, dhreza, provided higher hardness values at 3 mm depth. The composite was then covered with a polyester strip and pressed with a glass slab to accommodate the material into the matrix.

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

A higher degree of conversion can be obtained by using a high light intensity 4. However, this higher intensity may result in greater polymerization shrinkage and greater marginal leakage 5. Composition and batch are reported in Table 1.

How to cite this article. According to these authors, the Apollo 95 E emits less energy in 3 s than do the conventional curing light units. The effect of cure rate on the mechanical properties of dental resins.

Hardness evaluation of a dental composite polymerized with experimental LED-based devices. These differences were probably due to the characteristics of each method such as the light intensity, exposure time and heat generated.

Harrington E, Wilson HJ. However, there were statistical differences between these, in which the LED demonstrated jnoop lowest depth of cure. J Oral Rehabil ;