Papers by Author: Choong Ho Choi

Abstract: The purpose of this study was to investigate the remineralization effect of Galla Rhois and Psoralea corylifolia extracts with sodium fluoride (NaF), and interaction between the herbal extracts and NaF in dentifrice using the microbiological pH cycling model on artificial caries enamel. For the analysis, Surface hardness score of the enamel lesion on bovine teeth was measured, before and after the microbiological pH cycling sequences for 15 days. It showed that fluoride group was more higher surface hardness score than non fluoride group, and there were no significant differences among test dentifrices in each group. Thus, it is suggested that Galla Rhois and Psoralea corylifolia extracts with NaF have the remineralization effect on tooth surface. And there was no antagonistic interaction between those herbal extarcts and NaF in dentifrice.

Abstract: This study evaluated the combined inhibitory effects of a Curcuma xanthorrhiza extract (CXE) and Xylitol on S. mutans and A. viscosus in vitro. Three series of experiments on S. mutans and A. viscosus were carried out. In the first series, the Minimum inhibitory concentrations (MICs) of CXE, Xylitol, and CXE mixed with Xylitol (CXE+Xylitol) against S. mutans and A. viscosus were determined. Second, the antibacterial effect and the rapid effectiveness of CXE, Xylitol, and CXE+Xylitol against those bacteria was evaluated as contacting for 1, 2, 5, and 10 minutes. Finally, The saccharolytic capability of S. mutans was examined using bovine teeth that had been pretreated with CXE (1%), Xylitol (1%), CXE+Xylitol (1%), chlorhexidine (1%) and distilled water, and rinsed with distilled water. The pretreated bovine teeth were layered with soft agar containing sucrose (5%), S. mutans and phenol red, as a pH indicator, and incubated. The MICs of CXE were 5 ppm on both bacterial species. Xylitol did not inhibit either species. The MICs of CXE+Xylitol were 10 and 5 ppm against S. mutans, A. viscosus, respectively. According to the rapid effectiveness, CXE completely inhibited the growth of bacteria but Xylitol did not. CXE+Xylitol could completely inhibit the growth of bacteria. An evaluation of the saccharolytic capability of S. mutans on bovine teeth revealed that distilled water and Xylitol could not inhibit bacterial fermentation. However, the bovine teeth containing CXE, CXE+Xylitol and chlorhexidine inhibited the fermentation of bacteria. These results show that CXE and CXE+Xylitol have a strong antibacterial effect on S. mutans and A. viscosus in vitro.

Abstract: The purpose of this study was to investigate the effects of Galla Rhois, Psoralea corylifolia, Camellia sinensis, Salvia miltiorrhiza and Platcodon grandiflorum on the inhibition of artificial dental plaque formation and the cytotoxicity of the herbal extracts on human gingival fibroblasts. The analysis was carried out with the measurment of dental plaque weight and the cell survival rate of human gingival fibroblasts. It showed that Galla Rhois, Psoralea corylifolia, Camellia sinensis and Salvia miltiorrhiza inhibited the artificial dental plaque formation and did not reduce the cell viability of human gingival fibroblasts.

Abstract: A previous study reported that many supplements have been added to NaF mouthrinses to improve the remineralization potential. Nano-hydroxyapatite (nano-HA) might also be suitable to this purpose because these nano-size particles can penetrate the enamel pores. Moreover, hydroxyapatite is similar to the inorganic component of teeth and is both bioactive and biocompatible. The aim of this study was to evaluate the combined effects of a nano-HA and fluoride mouthrinse on an early caries lesion in human enamel using an in vitro cycle remineralization and treatment model. Forty-eight human enamel specimens, which had a Vickers Hardness Number (VHN) of 25~45 were artificially demineralized for 48h. There were 8 treatment groups (0%, 1%, 5%, 10% nano-HA in distilled water and the same concentrations of nano-HA in a 0.05% NaF solution). The specimens were incubated in an in vitro remineralization model. After immersing the specimens into the treatment and remineralization solution for 12 hours each, the VHN of each specimen was evaluated for total 24 hours. This step was repeated once again for total 48 hours. The enamel surfaces of all specimens were examined by Confocal Laser Scanning Microscopy (CLSM) and SEM. The statistical significance of the data was identified by one-way ANOVA followed by a Duncan’s studentized range test. A p value < 0.05 was considered significant. The results showed that the degree of remineralization, as revealed by the VHN values, was higher in the NaF groups than in the distilled water groups. The VHNs of the remineralized enamel specimens for 48 hours were higher than after the 24 hours treatment. In addition, the level of remineralization increased with increasing concentration of nano-HA and was more pronounced in the NaF groups than the distilled water groups (p<0.05). The CLSM and SEM images nano-sized particles attached to the enamel in the nano-HA treated groups. Nano-HA might play a synergistic role in remineralization with a fluoride mouthrinse. However, more study will be needed to determine the optimal condition of nano-HA and NaF mouthrinse for human use. In conclusion, nano-HA in a 0.05% NaF mouthrinse can help remineralize an early caries lesion.

Abstract: The process of dental caries is dynamic and continuous, with periods of de- and remineralization of the tooth structure occurring over time. When the remineralization potential is superior to demineralization, the caries process can be stopped and early caries lesions can recover. Moreover, the remineralization potential will be increased if active components are added to a dentifrice. Therefore, the aim of this study was to re-evaluate the remineralizaton potential of a dentifrice containing nano-sized carbonated apatite using pH cycling, which simulates the oral environment. Artificial incipient caries was induced on bovine tooth specimens, which were treated with 4 dentifrices containing several concentrations of nano carbonated apatites with pH cycling. The remineralization effect was evaluated at each step by measuring the Vickers Hardness Number, and obtaining SEM and CLSM images of the enamel surface. The micro hardness of the enamel surface increased after the pH cycling treatment of the dentifrices. The dentifrice containing 5% n-CAPs showed the highest level of remineralization followed by 0%, 15% and 30%. One-way ANOVA indicated a significant difference in remineralization between the dentifrice containing 5% and 30% n-CAPs. SEM and CLSM also demonstrated observable differences in each step. From this study, the fluoride dentifrice containing 5% n-CAPs was effective in remineralizing an artificial incipient caries lesion. In conclusion, the dentifrice containing 5% nano carbonated apatites and 25% silica was the most effective in remineralizing early caries lesion.

Abstract: Several studies have reported the on dental erosive potential of sports drinks with a low pH. Therefore, there is a need for new components that can reduce the erosive potential of a sports drink. Hydroxyapatites (HA) are the major components of dental enamel and bone mineral as biological apatites. In addition, HA contains a significant amount of calcium and phosphate, which can promote remineralization. Hence, some remineralization of the enamel surface can be expected if nano-sized hydroxyapatite (nano-HA) is added to a sports drink. The aim of this study was to evaluate the remineralization effects of sports drinks containing nano-HA in vitro. The crowns of extracted human molars were embedded in acrylic resin and then ground flat and polished. A commercially available sports drink (Powerade, Coca-Cola, South Korea) was purchased from a local supermarket. Nano-HA was added at a concentration of 0.05%, 0.25%, and 0.5%. Deionized water (DW) was used as the negative control. The pH of each solution was measured by a pH-meter at room temperature. The enamel specimens were immersed in each solution for 15 and 30 minutes at 37°C. In order to evaluate remineralization effect, the VHN of the enamel surface was measured at every step by microhardness test (JTTOSHI INC, Japan). CLSM and SEM were utilized to identify the change of enamel surface. The pH of test solutions and VHN of enamel surface increased in proportion to the nano-HA concentrations (P<0.05). The nano-HA could reduce the erosive potential of a sports drink in a concentration dependent manner. These effects were confirmed by the CLSM and SEM images, which showed the remineralization effect of nano-HA. However, more study will be needed to examine the optimal concentration and remineralization mechanism of the nano-HA in sports drinks. In conclusion, the addition of nano-HA to a sports drink can promote enamel remineralization.