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    Efficiency of tooth bleaching agent on staining and discoloration characteristics of nicotine stained dental enamel model
    (2020-08-10)
    Lertsukprasert, Nattha
    ;
    Locharoenrat, Kitsakorn
    Background: Surface staining and deeper discoloration characteristics of peroxide-based bleaching agents in the nicotine stain in dental enamel model were evaluated in the present study. Methods: Nicotine stained dental enamel fragments (n = 36) were prepared and were subjected to the bleaching ingredients for a fixed treatment time of 30 min. The bleaching agents were composed of limonene, coconut diethanolamide, and carbamide peroxide served as solvent, nonionic surfactant, and oxidizer, respectively. Optical analysis was carried out considering color stability via colorimeter and UV-Vis spectrometer. Results: Degrees of color variations were significantly influenced by nicotine content and bleaching ingredient factors. They varied in the range of approximately 3.00 and 5.00 units for all tooth-bleaching agents. The most prominent degrees of color variation elevations were obtained in the tooth bleaching formulae set #2 (1.0% limonene + 20% coconut diethanolamide) in the stained tooth model in comparison to set #1 (0.5% limonene + 10% coconut diethanolamide) and set #3 (1.5% limonene + 30% coconut diethanolamide), partly due to the perceptible color changes. The lowest degree of color variation under a dose limitation was found in the tooth bleaching formulae set #2 + 10% carbamide peroxide formulation. Absorbance spectra were also evaluated after the interaction of bleaching treatment. They confirmed a relationship between nicotine content and discoloration characteristics of the tooth bleaching formulae set #2 + 10% carbamide peroxide. Conclusions: Carbamide peroxide is considered as generator of free radicals. It converts the color of stains to clear by oxidizing the organic compounds in the stained dental enamel model, achieving whiteness enhancement.
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    Linear equation method for Hematocrit monitoring by optical transmittance
    (2007-01-01)
    Phonphruksa, Phimon
    ;
    Chaichanyut, M.
    ;
    Potejanasaja, I.
    ;
    Naktawan, A.
    ;
    Tungjitkusolmun, S.
    The objective of the present study is to investigate an optical transmittance system for prediction of hematocrit level by linear equation from the wavelength in the range of 426 nm to 950 nm. We constructed a simplified system with a light detecting finger clip probe to determine the transmittance spectra. We compared the results from our simplified measurement system with the hematocrit levels measured with the centrifuge using blood sample drawn from patients. From the analysis, we discovered that wavelengths between 525 nm to 610 nm, and between 700 to 950 nm are potential optimal choices for use to predict the hematocrit value. Then, four LEDs (525 nm, 585 nm, 875, and 950 nm) were used as the source which shone light through a finger, while the photodiode was placed at the opposite side of the finger for light transmission detection. We calibrated our system with the 117 sample hematocrit levels measured clinically by the centrifuge to obtain the linear equation model. We compared the results of our linear equation model for predicting the hematocrit levels with measured hematocrit levels from the centrifuge. From our analysis, the error obtained from the linear equation was less than 25% in more than 90% of the 117 collected data from patients.