Pharmaceutical Industry Technology Development Center

The effects of CO2 laser irradiation of dental enamel were evaluated in enamel demineralization experiments in partially saturated solutions (i.e., solutions containing both calcium and phosphate ions) with and without fluoride ions.

Previous studies had shown that a continuous-wave CO2 laser at an energy density of around 130 J/cm2 may induce an increased acid resistance in human dental enamel as assessed by exposure to severe demineralization conditions (0.1 mol/L acetate buffer, pH 4.5 and ionic strength 0.5 mol/L).

Enamel blocks were irradiated with a continuous-wave CO2 laser at a wavelength of 10.6 microns using energy densities of from 42.5 to 170.0 J/cm2. The blocks were then exposed to a partially saturated demineralizing solution with or without 0.2 ppm fluoride at a temperature of 30 degrees C for 24 hours. The demineralization was examined both qualitatively by light microscopy and quantitatively by microradiography.

A comparison between the lased and the unlased portions of enamel showed increased acid-resistance with increasing laser energy density and, at the highest energy density of 170.0 J/cm2, there was little or no lesion development in the fluoride-free dissolution medium. The demineralization of enamel was reduced dramatically in the presence of 0.2 ppm fluoride for both lased and unlased enamel; there was only modest lesion development observed for unlased enamel and, at an energy density as low as 85.0 J/cm2, the surface of enamel was found to be completely protected.

These findings are consistent with the mechanism that laser irradiation of dental enamel results in significant reduction of the effective solubility of enamel mineral and that there is a significant synergism between laser irradiation and solution fluoride with regard to this effect.

An HPLC method was applied for the simultaneous determination of five marker substances in the traditional Chinese medicine preparation Tzyy-Yun-Gau.These substances included shikonin, deoxyshikonin, β,β-dimethylacrylshikonin, and acetylshikonin in Arnebiae Radix; and ferulic acid in Angelicae Radix.Tzyy-Yun-Gau was partitioned in a mixture of n-hexane and MeOH, and a fraction taken into the MeOH layer was analyzed.The samples were run through an HPLC column (Inertsil ODS-2, 4.6 mm I.D. × 250 mm) at 30° with a mobile phase consisting of MeOH, MeCN and 2% HOAc with linear gradient elution at a flow-rate of 1.0 mL/min.A UV detector was used for detection.The detection wavelength varied with time, which was 325 nm during 0-25 min 525 nm during 25-58.5 min, 440 nm during 58.5-62 min, and 525 nm during 62-80 min.This could be a successful separation method for the simultaneous determination of five marker substances in Tzyy-Yun-Gau.

An HPLC method was applied for the simultaneous determination of six marker substances in the Chinese medicinal preparation "Chai-Hu-Kuei-Chih-Tang".These substances were paeoniflorin in Paeoniae Radix, cinnamic acid in Cinnamomi Ramulus, baicalin, baicalein, wogonin in Scutellariae Radix, and Glycyrrhizin in Glycyrrhizae Radix.Extracted samples were run through the HPLC column (Cosmosil 5 C₁₈-AR, 4.6 mm ϕ × 250 mm) at 30°C and the column was developed with a mixture of 15% acetonitrile-20 mM sodium 1-hexane sulfonate (pH 3.5) and 45% acetonitrile - 20 mM sodium 1-hexane sulfonate ml/min.An UV detector was used for the detection of the marker substances.The detection wavelength varied with time.It was 230 nm during 0 - 15 min, 275 nm during 15 - 38 min, 270 nm during 38 - 60 min, 250 nm during 60 - 68 min, and lastly 275 nm during 68∼75 min.Relative standard deviations of intra- and inter-day anal. were less than 5%.This separation method could be successfully applied for the simultaneous determination of six marker substances in "Chai-Hu-Kuei-Chih-Tang".