Papers by Author: B.I. Kim

Abstract: Carbonate apatite has a similar structure to the inorganic component of teeth and bone. Although carbonate apatite is widely used as a bone substitute, there are no reports on its use as a desensitizing dentifrice. This in vitro study evaluated the relative abrasivity of the dentifrice containing nano-sized carbonated apatite (n-CAPs) using a Surface Profile Method (SPM). The dentin specimens were made from the root of extracted human molars. The cervical part of the teeth was sectioned with a diamond wheel disk. The teeth were embedded into an epoxy resin mold and the surface was gradually polished using silicone carbide paper. After grinding, the degree of surface roughness was examined within the range of 2 mm with tapping. The British Standard Institution reference dentifrice (BSI: CaCO3 40%) and the experimental dentifrices (group 1: n-CAPs 30%, group 2: n-CAPs 15% and silica 15%, group 3: n-CAPs 5% and silica 25%, group 4: silica 30%, group 5: CaCO3 10% and SrCl2 10%) were compared. The dentifrice slurries were prepared by mixing 24 grams of the dentifrice in 12 ml distilled water. Each tooth specimen was brushed 1,000 times with the dentifrice slurries using a back-and-forth stroke. The relative abrasivity of each dentifrice was evaluated by determining the ratio of the BSI standard dentifrice to each experiment. The results were analyzed using one-way ANOVA and Tukey’s multiple comparisons using Window SPSS (Statistical analysis system) 12.0. According to the results, Group 1 (3.2), which contained only n-CAPs appeared to have the lowest abrasivity than the BSI dentifrice (100). However, Groups 2 (124.2), 3 (137.9) and 4 (178.1), which contained n-CAPs and silica, appeared to have a higher abrasivity than the BSI dentifrice (p>0.05). The relative abrasivity of group 5 (38), which was a commercial desensitizing dentifrice, was relatively lower. It appears that the higher abrasivity of the experimental is due to the shape and size of the silica component. Therefore, n-CAPs itself has no influence on the abrasivity of the dentifrice. The main reason for the low abrasivity of n-CAPs is believed to be its small particle size (range 50-90nm).

Abstract: The main objective of this study was to manufacture an oral rinse using the natural antibacterial agent (phytosphingosine, Doosan, Korea) for the prevention of periodontal disease and dental caries. Phytosphingosine is known to inhibit the growth of bacterial strains and induce apoptotic cell death in human cancer lines. In this study, antibacterial activity and cytotoxicity of oral rinses were performed with an experimental group containing phytosphingosine(PS) in vitro. Control groups consist of two Korean products and two American products containing chlorhexidine and cetylpyridinium chloride, respectively. There was no significant difference between experimental and control groups in the antibacterial activity and cytotoxicity except for Chika Chika Liq (p<0.05). According to the results, antibacterial activity of oral rinse containing PS was 99.62%, the strongest contact inhibition of Streptococcus mutans strain among tested groups. In the cytotoxicity test of oral rinses, PS had a weaker cytotoxicity than control groups in mouse and human normal cell lines and showed the strongest cytotoxicity in human oral cancer cell lines (KB cell). From the results, PS may be widely used as an oral rinse for the healthy and the patients with oral cancers in the near future.

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: Exposed dentine with patent tubules allows the movement of the tubule fluid leading to dentine sensitivity. An occlusion of patent dentinal tubules can effectively reduce the state of dentine hypersensitivity. Strontium chloride (SrCl2) has been known as a representative component of a desensitizing dentifrice. Recently, a desensitizing dentifrice containing nano-sized Carbonated Apatites (n-CAPs) was released onto the market. The aim of this in vitro study was to evaluate the occlusion effects of dentinal tubules in dentifrices containing several concentrations of the n-CAPs. One hundred human dentine specimens were embedded into a Teflon mold and ground with silicone carbide papers to expose the dentin surface. The dentin surface was etched with 37% phosphoric acid for 60 seconds and washed ultrasonically for 1 hour. The dentifrices were classified into five groups: experimental dentifrices Group 1: n-CAPs 5%, group 2: n-CAPs 15%, group 3: n- CAPs 0% and group 4: n-CAPs 30%, and the control dentifrice group 5: SrCl2 10%. The dentifrice slurries were prepared as 20 grams of dentifrice in 80 ml of distilled water. Fifty specimens were brushed with the dentifrice slurries using a V8 Cross Brushing Machine. Tooth brushing was performed 5,000 times using a back-and–forth stroke. Images showing the sizes of the dentinal tubules were taken by scanning electron microscopy (×3000) and the changes in the tubule sizes were analyzed using a digital analyzer. The n-CAPs used in this study had a high solubility and affinity to bone minerals. In addition, the n-CAPs were well deposited on patent dentinal tubules. The group 1 dentifrice (n-CAPs 5% and silica 25%) showed the highest dentinal tubule occlusion, and there was a statistically significant difference between group 4 and the control (p<0.05). Overall, the dentifrice containing 5% nano carbonated apatite and 25% silica is the most effective in occluding dentinal tubules.

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: Exposed dentine with patent tubules allows the movement of tubule fluid leading to dentine sensitivity. Occlusion of patent dentinal tubules effectively reduces the state of dentine hypersensitivity. Strontium chloride (SrCl2) has been well known as a component of desensitizing dentifrice. Recently, new dentifrice containing sodium metasilicate was on the market for desensitizing dentifrice. The aim of this in vitro study was to compare the occlusion effect of dentinal tubule between the sodium metasilicate and the existing desensitizing dentifrices. Sixtyfour human dentine specimens were embedded into a Teflon mold and were grinded with the use of silicone carbide papers to expose the surface of dentin. The dentin surface was etched with 37% phosphoric acid for 60 seconds and was treated with ultrasonic washing for 1 hour. The dentifrices used in the study are classified into four groups: G1-dentifrice containing Sodium metasilicate, G2- dentifrice containing Strontium chloride, G3-dentifrice containing Hydroxyapatite and G4-BSI reference dentifrice (control group). Toothpaste slurries were prepared as 20 gram of toothpaste in 80 ml of distilled water. Thirty-two specimens were brushed with the toothpaste slurries using V8 Cross Brushing Machine. Tooth-brushing was performed 5,000 times using a back-and–forth stroke. The pictures of the sizes of dentinal tubules were taken by scanning electron microscopy (×3000) and changes of tubule sizes were analyzed by digital analysis. The results showed that the difference of tubule size in descending order: G1-3.30±1.80, G2-2.82±1.73, G3-1.49±1.14, G4- 1.04±0.94. The dentifrice containing Sodium metasilicate (22.5%) showed the highest dentinal tubule occlusion. Moreover, the dentifrice containing Sodium metasilicate statistically significantly increased occlusion of dentinal tubule as compared to BSI reference dentifrice (p<0.05). Thus, new desensitizing dentifrice containing sodium metasilicate was more effective than existing desensitizing dentifrice on occlusion of dentin tubules.

Abstract: This in vitro study compared the abrasivity of commercial desensitizing dentifrices with a sodium metasilicate (Na2SiO3) dentifrice using a Surface Profile Method. Dentin specimens were made from the root of extracted human molars. The cervical part of the teeth was sectioned with a diamond wheel disk. The teeth were embedded into an epoxy resin mold and the surface was gradually polished by silicone carbide paper. After grinding, the degree of surface roughness was tested within the range of 2 mm with tapping. The British Standard Institution reference dentifrice (BSI: CaCO3 40%) and experimental dentifrices (group 1: Na2SiO3 25%, CaCO3 10% and SiO2 10%, group 2: CaCO3 10% and SiO2 10%, group 3: CaCO3 10% and SrCl2 10%, group 4: Colloidal Silica 2-3% and Hydroxyapatite 10-20%) were evaluated. The dentifrice slurries were prepared by mixing 24 grams of the dentifrice in 12 ml distilled water. Each tooth specimen was brushed with the dentifrice slurries 1,000 times. The relative abrasivity of each dentifrice was evaluated from the ratio of the BSI standard dentifrice to each experiment. The results were analyzed by one-way ANOVA and Tukey’s multiple comparisons using Window SPSS (Statistical analysis system) 12.0. Groups 1 (71), 2 (74.2), 3 (38) and 4 (7.8) showed a lower abrasivity than the BSI dentifrice (100) (p<0.05). The relative abrasivity of groups 3 (38) and 4 (7.8) was the lowest compared with the BSI dentifrice (100). However, group 1 (71) containing Na2SiO3 showed a similar abrasivity to group 2 (74.2), which did not contain Na2SiO3 (p>0.05). Therefore, Na2SiO3 had no influence on the abrasivity of the dentifrice. In conclusion, the dentifrice containing Na2SiO3 had a lower abrasivity than the BSI reference dentifrice, but showed a significantly higher abrasivity than the existing commercial desensitizing dentifrices. Overall, the relatively high abrasivity of Na2SiO3 dentifrice is believed to be the result of other components in the abrasive system.

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.