ORCID Profile
0000-0002-1757-4524
Current Organisation
Instituto Superior de Engenharia de Lisboa
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Publisher: Springer Science and Business Media LLC
Date: 03-08-2006
DOI: 10.1007/S10103-006-0391-0
Abstract: In the present paper, the influence of tubule orientation on surface texture development was studied. Specimens of dentin with a wide range of tubule orientations were extracted from caries-free human teeth, processed using KrF laser radiation, and analyzed by scanning electron microscopy. When a transverse cross section of dentin cut perpendicularly to the tooth axis is processed with KrF laser radiation, a cone-like topography develops in the inner dentin where tubules are parallel to the laser beam. When laser processing is carried out in the outer dentin, because tubules are significantly tilted with respect to the laser beam, flat surfaces are achieved. The surface texture after laser processing depends effectively on the angle between the tubules and the laser beam. The dependency of cone growth on tubule orientation was confirmed using a simple differential ablation model.
Publisher: Inderscience Publishers
Date: 2010
Publisher: AIP Publishing
Date: 15-11-2006
DOI: 10.1063/1.2369633
Abstract: A cone-shaped texture is observed when a transverse cross section of human dentin cut perpendicularly to the tooth axis is processed with KrF excimer laser radiation using appropriate processing parameters. In the present paper, a mathematical model describing the kinetics of cone growth as a function of the number of laser pulses is presented. It is shown that the fractional area occupied by cones is adequately described by a modified Johnson-Mehl-Avrami-Kolmogorov equation and that the boundary lines between cones define a Voronoi tessellation generated from the corresponding initial tubule location. This model allows the surface texture evolution in dentin to be predicted from the initial tubule distribution.
Publisher: SPIE
Date: 08-02-2007
DOI: 10.1117/12.697198
Publisher: Laser Institute of America
Date: 11-2006
DOI: 10.2351/1.2355528
Abstract: Exposure of dentinal tubules is a common cause of dental hypersensitivity to thermal, mechanical, or chemical stimuli. Treatment for this syndrome should be fast, painless on application, and long lasting, but most treatments presently available are ineffective or relatively short lived. The aim of the present investigation was to evaluate the potential of excimer laser treatment as a method to seal tubules, thus reducing sensitivity. The laser treatment was performed on s les with a wide range of orientations of the tubules in relation to the s les surfaces extracted from caries-free human teeth by cross-sectional cutting and on noncarious lesions. The s les were processed using 248 nm wavelength pulsed laser radiation with a pulse duration of 30 ns and fluences in the range 0.5–2 J/cm2. Irrespective of their orientation in relation to the laser beam, tubules may be sealed by laser processing if adequate parameters are used. Tubule sealing is either due to the formation of cone-like features around in idual tubules or because the entire surface is covered by a thin layer of resolidified material. The results achieved both on flat s les and in noncarious lesions are reproducible, suggesting that this method is potentially useful for dental hypersensitivity treatment.
Publisher: Laser Institute of America
Date: 23-07-2009
DOI: 10.2351/1.3184431
Abstract: The aim of this work was to study the bond strength of resin composite bonded to dentin surfaces treated with KrF excimer laser radiation, untreated surfaces, and acid-etched surfaces using a single-plane shear method. Dentin specimens cut from freshly extracted permanent molar teeth were subjected to laser treatment with a KrF excimer laser (248 nm) using a fluence of 1 J/cm2. The bond strength was greater for acid-etched specimens than for laser treated or untreated specimens. The low strength of the bond to laser treated surfaces is probably due to a shift from a mixed to a cohesive rupture mechanism. It was concluded from this study that surface treatment of dentin surfaces with KrF excimer laser under the conditions described does not significantly improve the shear bond strength to composites.
No related grants have been discovered for Vitor Oliveira.