The concern with the hydrogen penetration towards the pulp can be observed on the literature by the great number of papers published on this topic; Those measurements often uses chemical agents to quantify the concentration of the bleaching agent that cross the enamel and dentin. The objective of this work was the quantification of oxygen free radicals by fluorescence that are located in the interface between enamel and dentin. It was used to accomplish our objectives a Ruthenium probe (FOXY R - Ocean Optics) a 405nm LED, a bovine tooth and a portable diagnostic system (Science and support LAB - LAT - IFSC/USP). The fluorescence of the probe is suppressed in presence of oxygen free radicals in function of time. The obtained results
clearly shows that the hydrogen peroxide when not catalyzed should be kept in contact with the tooth for longer periods of time.
Nowadays the real contribution of light on the acceleration of the chemical reaction for
the dental bleaching is under incredulity, mostly because the real mechanisms of its
contribution still are obscure. Objectives: Determine the influence of pigment of three
colored bleaching gels in the light distribution and absorption in the teeth, to accomplish
that, we have used in this experiment bovine teeth and three colored bleaching gels. It is
well Known that the dark molecules absorb light and increase the local temperature
upraising the bleaching rate, these molecules are located in the interface between the
enamel and dentin. Methods: This study was realized using an argon laser with 455nm
with 150mW of intensity and a LED with the same characteristics, three colored gels
(green, blue and red) and to realize the capture of the digital images it was used a CCD
camera connected to a PC. The images were processed in a mathematical environment
(MATHLAB, R12 ®). Results: The obtained results show that the color of the
bleaching gel influences significantly the absorption of light in the specific sites of the
teeth. Conclusions: This poor absorption can be one of the major factors involved with
the incredulity of the light contribution on the process that can be observed in the
literature nowadays.
The dental bleaching is known for many years. Recently a technique employing light has
open up new and exciting possibilities. Besides its vast application there are still many
important points to be understood about teeth photon bleaching. In this work we present an
"in vitro" experiment to explore the main mechanisms involved during the photon action in
tooth whitening. Our results indicated that light at same wavelengths are great absorbed by
pigments creating a local heating which considerably increase the bleaching rate. This
results in a fast reaction without heating the whole dental structure. We discuss details of
our experiment. Work supported by Fapesp and CNPq.
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