Some salivary macromolecules penetrate enamel lesions and are adsorbed onto apatite crystal surfaces. Research has shown that removing salivary proteins from enamel lesions with sodium hypochlorite solution enhances crystal growth. At concentrations of 20-35%, H₂O₂, which is the active ingredient of in-office bleaching agents, denatures and/or degrades chromogenic molecules. We hypothesized that in-office bleaching can be used therapeutically to denature macromolecules present in enamel subsurface lesions and thereby enhance remineralization. In this study, we support this hypothesis by demonstrating that exposure to 30 % H₂O₂ solution chemically alters human salivary proteins. Resting whole saliva was collected on ice and clarified by centrifugation for 30 min to precipitate epithelia and other sediments. The saliva samples were divided into two halves. Each sample was mixed with isopropanol to a final concentration of 70% and centrifuged. For H₂O₂ group, 30% H₂O₂ was added to the precipitate, incubated for 30 min, and then mixed with isopropanol to precipitate proteins. Control samples were incubated with water instead of H₂O₂. Finally, the precipitate and supernatant fractions were separated by centrifugation and subjected to SDS-polyacrylamide gel electrophoresis (PAGE) with dithiothreitol. Staining with CBB and Stains-All and Western blotting were performed. Certain salivary proteins changed their characteristics after treatment with 30 % H₂O₂. SDS-PAGE showed that specific proteins were irreversibly oxidized with the 30% H₂O₂ treatment, resulting in different molecular sizes. Furthermore, Western blotting with antibodies against serum albumin and statherin showed that the detected bands changed dramatically and uniquely after H₂O₂ treatment. The reaction to the anti-statherin antibody almost disappeared after H₂O₂ treatment, while the reaction to the anti-albumin antibody increased and protein bands of a much wider molecular range were broadly detected. Our results imply that treatment of enamel subsurface lesions with 20-35% H₂O₂ may enhance remineralization by denaturing disadvantageous macromolecules such as statherin that may be present in the lesion. In-office bleaching, we believe, is therapeutically useful in enhancing remineralization, although further studies are necessary before its application. Salivary proteins in resting whole saliva reacted with 30 % H₂O₂, resulting in fragmentation or covalent association of certain proteins. Deprivation of statherin, which otherwise inhibits mineralization, is potentially useful for treating enamel subsurface lesions.

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Single-step self-etch adhesive systems, which combine the function of a self-etching primer and an adhesive, have been developed to simplify the process of application. Recently, a multi-purpose adhesive system (BeautiBond Multi) comprising a silane coupling agent (BeautiBond Multi PR Plus) has been introduced. The purpose of this study was to evaluate the bonding performance of the multi-purpose adhesive system to ceramics, dental casting alloy, and dental hard tissue. Zirconia, alumina, porcelain, Au-Ag-Pd alloy, bovine enamel and dentin were used as adherends. After surface treatment, a resin composite (Beautifil II) was condensed into the mold and cured for 30 seconds. The specimens were stored for 24 hours, then a shear bond strength test was carried out using a universal testing machine at a crosshead speed of 1.0 mm/min. The fractured resin surfaces were observed by electric scanning microscopy. Shear bond strength was 16.2 MPa for zirconia, 14.8 MPa for alumina, 16.6 MPa for porcelain, 18.1 MPa for Au-Ag-Pd alloy, 15.4 MPa for bovine enamel, and 16.8 MPa for bovine dentin. There were no significant differences except between alumina and Au-Ag-Pd alloy. The newly designed multi-purpose adhesive system showed similar shear bond strengths to all the adherend materials and dental hard tissue. The results suggest that the multi-purpose adhesive system displays good bonding performance for repair restoration.

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Objective: Enamel molecules are believed to regulate cementoblast differentiation and to initiate the formation of acellular extrinsic fiber cementum. However, their precise spatial expression patterns and molecular roles are not clearly understood. Epithelial-mesenchymal interactions are responsible for morphogenesis and cell differentiation during periodontal regeneration. The current study was undertaken to examine the expression of amelogenins, ameloblastin, MMP-20, and KLK4 with respect to interactions between the cells of the epithelial rests of Malassez and fibroblasts from human periodontal ligament. Methods: Explants of human periodontal ligament tissues produced outgrowths containing both epithelial rests of Malassez cells and periodontal ligament fibroblasts after incubation in a modified serum-free medium. The distribution and expression of amelogenin, ameloblastin, MMP-20, and KLK4 were analyzed by in situ hybridization and RT-PCR. Epithelial rests of Malassez cells were cultured separately and used as a control. Results: RT-PCR analysis showed that amelogenin mRNA was expressed when epithelial rests of Malassez cells and periodontal ligament fibroblasts were cultured together. The expression levels of ameloblastin and KLK4 mRNAs were significantly higher when epithelial rests of Malassez cells and periodontal ligament fibroblasts were cultured together than when epithelial rests of Malassez cells were cultured alone. In situ hybridization analysis revealed that epithelial rests of Malassez cells expressed amelogenin mRNA, ameloblastin mRNA, and KLK4 mRNA at the interface between epithelial rests of Malassez cells and periodontal ligament fibroblasts. MMP-20 mRNA was not seen. Conclusion: These findings indicate that the interactions between epithelial rests of Malassez cells and periodontal ligament fibroblasts induce the expression of mRNAs for amelogenin, ameloblastin, and KLK4, suggesting that epithelial-mesenchymal interactions play an important role in maintaining the periodontal ligament space.

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The objective of the present study was to examine the correlation between age, clinical experience, life-style, presence of ocular disease and macula retinae thickness, color discrimination ability. This was conducted in order to investigate the impact to businesses in the dental field caused by age-related ophthalmological changes that influence color vision in the elderly. The subjects of the study were 22 male and female (44 eyes) between the ages of 21 and 64. Each of the subjects underwent an examination by a Japanese Ophthalmological Society-certified ophthalmology specialist. This assessment included corrected visual acuity, intraocular pressure, ocular fundus examination with a non-mydriatic camera, and measurement of macula retinae thickness using optical coherence tomography. We also conducted color discrimination ability testing using a 100-hue arrangement test machine. A fluorescent lamp was used for illumination, and the degree of illumination of the area was set to 1,000 lux. While the number of subjects over 40 years of age presented with cataracts or glaucoma was significant, all were diagnosed as 'early stage', with their vision and central vision acuity being normal, so that a correlation with macula retinae thickness was not discernable. The mean score for the total deviations in the color discrimination test was 81.6 ± 68.6. A negative correlation of r=-0.4 was observed between age and total deviations, while no correlation was observed with the presence of ocular disease. There was also a significant correlation found between the total deviation and the presence of clinical experience. Previous research indicated that color discrimination ability in the red and blue regions is reduced due to ageing. The results of the present study, however, suggest that the impact of age-related ophthalmological and optical stromal changes on color discrimination ability is minimal, and that improvement or maintenance of color discrimination ability may be possible with practice.

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The purpose of this study was to evaluate the clinical effect of a tapered-end toothbrush (Deep Clean®: Kao) on gingiva with mild inflammation. A total of thirty subjects were selected for this study from patients referred to the periodontal clinic in Nagasaki University Hospital for maintenance. The subjects satisfied the following inclusion criteria. 1. They have 3 teeth with more than one periodontal pocket exhibiting a probing depth (PD) of 2-4 mm and bleeding on probing (BoP), within 4-4 of the maxilla and mandible. 2. No unfitting restoration exist at the experimental sites. 3. They had not received antibiotics, anti-inflammatory agents or steroids for a month. We used toothbrush D (Deep Clean®) as the experimental toothbrush and toothbrush S (Dentor Systeme®: Lion) as the control toothbrush, which was already on the market. All subjects were given professional instruction to use either toothbrush (S or D) for 4 weeks at the experimental sites in Bass method, after their usual brushing method. Plaque index (PH), PD and BoP were scored at a base line (BL), and after 2 and 4 weeks. Overall, there was a significant improvement of PlI, PD and BoP in both groups with time. There was no significant difference between both groups at any time, but group D showed a tendency in improvement of BoP and PlI. These results suggested that a tapered-end toothbrush is useful to reduce mild inflammation in gingiva.

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The purpose of this study was to investigate the effectiveness of resin bonding to root canal dentin of a new chemical-cure resin bonding system, compared to the dual-cure resin bonding system. Extracted human premolars were used in this study. Crowns of the teeth were sectioned at the cement-enamel junction using a low-speed diamond saw. Pulpal tissue was removed by using endodontic files, and post spaces were prepared by using post drills in a low-speed handpiece to a depth of 5 or 10 mm and diameter of 1.4 mm. The roots were randomly divided into two groups, and their root canal dentin surfaces treated with one of the following self-etching primers: 1) dualcure system Estelite-Core Quick Bond (DC) or 2) chemical-cure system DBC-510 Trial product (CC). Post holes were filled with a dual-cure composite resin core material, excess resin was removed and resin in the root canal was light-cured. Each root was then cut parallel to the long axis. The resin-dentin interfaces were then observed with a scanning electron microscope (SEM) and surface profile measurement microscope. The other side, specimens of 5 mm depth were classified into upper (rd1) and lower part (rd2), and specimens of 10 mm depth were classified into upper (RD1), upper of middle (RD2), lower of middle (RD3) and lower part (RD4). Then, the bond strength of each part of the specimens was measured by the microtensile bond strength test. The results of surface analysis by SEM and surface profile measurement microscope revealed no gaps at the interface in both specimens of DC and CC. DC provided a higher bond strength than CC, and RD1 of DC provided a higher bond strength than RD4 of DC. CC provided a lower bond strength than DC. However, there was no significant difference in the bond strength between the lower and upper parts. It is suggested that the DBC-510 chemical-cure system (CC) achieves good resin bonding to root canal dentin regardless of the depth of post hole.

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