OBJECTIVE: Different methods have been utilized to prevent enamel demineralization and other complications during orthodontic treatment. However, none of these methods can offer long-lasting and effective prevention of orthodontic complications or interventions after complications occur. Considering the photocatalytic effect of TiO2 on organic compounds, we hoped to synthesize a novel bracket with a TiO2 thin film to develop a photocatalytic antimicrobial effect. METHODS: The sol-gel dip coating method was used to prepare TiO2 thin films on ceramic bracket surfaces. Twenty groups of samples were composed according to the experimental parameters. Crystalline structure and surface morphology were characterized by X-ray diffraction and scanning electron microscopy, respectively; film thickness was examined with a surface ellipsometer. The photocatalytic properties under ultraviolet (UV) light irradiation were analyzed by evaluating the degradation ratio of methylene blue (MB) at a certain time. Antibacterial activities of selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. RESULTS: Films with 5 coating layers annealed at 700℃ showed the greatest photocatalytic activity in terms of MB decomposition under UV light irradiation. TiO2 thin films with 5 coating layers annealed at 700℃ exhibited the greatest antimicrobial activity under UV-A light irradiation. CONCLUSIONS: These results provide promising guidance in prevention of demineralization by increasing antimicrobial activities of film coated brackets.
Candida albicans ; Ceramics* ; Crystallins ; Dental Enamel ; Esthetics ; Hope ; Lactobacillus acidophilus ; Methods ; Methylene Blue ; Microscopy, Electron, Scanning ; Ultraviolet Rays ; X-Ray Diffraction

OBJECTIVETo modify biomacromolecules, such as chitosan and collagen, to synthesize a mineralized template that will induce self-growing remineralization of tooth enamel.

METHODSNatural polycation polysaccharide chitosan was modified through phosphorylation to synthesize the polyanion derivative ofphosphorylated chitosan. Parent hydrogels com- bined with chitosan and collagen I were built through peptide binding reaction using genipin as a crosslinker. The gels self- assembled on the tooth's inert surface, which was stimulated by ultraviolet radiation. The bionic saliva provided mineralized ion, and then the hydroxyapatite assembled and grew in situ on the tooth.

RESULTSThe functional group P04(3-) (3,446 cm(-1)) was grafted on chitosan as confirmed by the Fourier transform infrared spectroscopy. The porous polyelectrolyte complex hydrogel formed by the interaction between the polycation chitosan and the polyanion phosphorylated chitosan could induce hydroxyapatite crystal nucleation and growth on the hydrogel fiber surfaces. The neonatal crystal was hydroxyapatite as confirmed by X-ray diffraction and was tightly connected to the tooth. A continuous structure of column crystals with sizes ranging from 30 nm to 60 nm was observed. The structure was in parallel direction similar to the direction of the enamel rod, and its hardness was close to dentin.

CONCLUSIONThe parent hydrogels that were easily obtained and controlled could mimic the template of the enamel mineralization and induce a self-growing hydroxyapatite, which is an important step in the structural bionics of enamel.

Biocompatible Materials ; Chitosan ; Collagen ; Dental Enamel ; Durapatite ; Microscopy, Electron, Scanning ; Polymers ; Spectroscopy, Fourier Transform Infrared ; Tooth ; Tooth Remineralization ; Ultraviolet Rays ; X-Ray Diffraction

OBJECTIVETo study the effects of ultraviolet (UV) light-treatment on the physicochemical properties and bioactivity of micro-arc oxidation (MAO) titanium surfaces in vitro.

METHODSThe pure titanium were prepared using MAO. MAO titanium samples were treated with 15 W bactericidal lamp UVC [λ = (250 ± 20) nm] or 15 W mercury lamp [λ = (360 ± 20) nm] for 24 h under ambient conditions. Three sample groups were prepared: MAO, UVA treated after MAO (MAO + UVA), UVC treated after MAO (MAO + UVC). The surface physicochemical properties were evaluated using scanning electron microscopy (SEM), contact angle measuring device, energy dispersive X-ray spectrometer (EDX), and X-ray diffraction (XRD). Bicinchoninic acid (BCA) based colorimetric detection was used to quantify the percentage of albumin adsorption after 2 h, 6 h, and 24 h incubation on the titanium surfaces. The rates of MG-63 cells attached to each group titanium surfaces were calculated by nucleus immunofluorescence using Hoechst 33342 after 1 h, 2 h, and 4 h incubation. SEM was used to observe cell morphology on titanium surfaces in each group.

RESULTSNo obvious differences in surface topography, TiO(2) crystal and elemental composition were detected on titanium surfaces with or without UV treatment. Statistically significant difference in contact angles among MAO + UVC group (65.34 ± 1.16)°, MAO + UVA group (44.64 ± 1.28)°, and MAO group (3.41 ± 0.48)° were found (P < 0.001). The percentage of albumin adsorption reached the plateau after 2 h incubation on MAO + UVC titanium surfaces (48.16 ± 1.24)%, which was higher than those in MAO [(8.22 ± 2.99)%] and MAO + UVA groups [(5.29 ± 2.27)%, P < 0.001]. The rates of cells attached to the surfaces of MAO + UVC titanium was greater than that on MAO surfaces and MAO + UVA surfaces after 1 h [(40.71 ± 4.08)%], 2 h [(53.72 ± 2.38)%], 4 h [(70.32 ± 2.85)%] incubation (P < 0.05). The MAO + UVC surfaces remarkably enhanced the spread of MG-63 cells, however, there was no significant difference between the group of MAO and MAO + UVA.

CONCLUSIONSPretreatment of micro-arc oxidation titanium with UVC light considerably improved the surface bioactivity to MG-63 cells, which showed an increase in cellular attachment and spread.

Absorption ; Albumins ; metabolism ; Cell Adhesion ; Cell Line, Tumor ; Humans ; Microscopy, Electron, Scanning ; Osteosarcoma ; pathology ; Oxidation-Reduction ; Spectrometry, X-Ray Emission ; Surface Properties ; Titanium ; chemistry ; radiation effects ; Ultraviolet Rays ; X-Ray Diffraction

The purpose of this study was to examine the mRNA levels of TNF-alpha and IL-6 in the cell lines of normal oral keratocyte and oral squamous cell carcinoma. Total RNA was extracted from these cell lines, observed under UV light, developed by radiographic films of PCR products via reverse transcriptase polymerase chain reaction (RT-PCR) amplication, and measured with densitometer. Each mRNA level of these cell lines divided by beta-actin mRNA level was compared to that of normal control group. The results were as follows : 1. Higher mRNA expression of TNF-alpha than IL-6 in the normal oral epithelial cell line. 2. In general, expression of mRNA of IL-6 appeared 3-4 times more in tumor cell lines than in control group. 3. mRNA expression of TNF-alpha showed variable expression in tumor cell lines, unlike normal cell line. 4. There are no special connections between differentiation of oral cancer cell lines and mRNA expression of TNF-alpha and IL-6. From the above results, expression of mRNA of IL-6 in the cell lines of squamous cell carcinoma used in this study has higher than the normal oral epithelial cell line, but there are no relationship between the differentiation of oral cancer cell lines and the expression of mRNA of TNF-alpha and IL-6.
Actins ; Carcinoma, Squamous Cell* ; Cell Line* ; Cell Line, Tumor ; Epithelial Cells ; Interleukin-6* ; Mouth Neoplasms ; Polymerase Chain Reaction ; Reverse Transcriptase Polymerase Chain Reaction ; RNA ; RNA, Messenger* ; Tumor Necrosis Factor-alpha* ; Ultraviolet Rays ; X-Ray Film

No abstract available.
Ultraviolet Rays*

The human Gadd45 protein family plays critical roles in DNA repair, negative growth control, genomic stability, cell cycle checkpoints and apoptosis. Here we report the crystal structure of human Gadd45γ [corrected], revealing a unique dimer formed via a bundle of four parallel helices, involving the most conserved residues among the Gadd45 isoforms. Mutational analysis of human Gadd45γ [corrected] identified a conserved, highly acidic patch in the central region of the dimer for interaction with the proliferating cell nuclear antigen (PCNA), p21 and cdc2, suggesting that the parallel dimer is the active form for the interaction. Cellular assays indicate that: (1) dimerization of Gadd45γ [corrected] is necessary for apoptosis as well as growth inhibition, and that cell growth inhibition is caused by both cell cycle arrest and apoptosis; (2) a conserved and highly acidic patch on the dimer surface, including the important residues Glu87 and Asp89, is a putative interface for binding proteins related to the cell cycle, DNA repair and apoptosis. These results reveal the mechanism of self-association by Gadd45 proteins and the importance of this self-association for their biological function.
Amino Acid Motifs ; Animals ; Apoptosis ; radiation effects ; CDC2 Protein Kinase ; Cell Cycle ; Cell Survival ; Crystallography, X-Ray ; Cyclin B ; metabolism ; Cyclin-Dependent Kinase Inhibitor p21 ; metabolism ; Cyclin-Dependent Kinases ; HeLa Cells ; Humans ; Intracellular Signaling Peptides and Proteins ; chemistry ; genetics ; metabolism ; Mice ; Mutagenesis, Site-Directed ; Mutation, Missense ; Proliferating Cell Nuclear Antigen ; metabolism ; Protein Binding ; Protein Interaction Domains and Motifs ; Protein Multimerization ; Protein Structure, Quaternary ; Ultraviolet Rays

No abstract available.
Autoradiography* ; DNA* ; Ultraviolet Rays*

No abstract available.
Animals ; Mice* ; Ultraviolet Rays*

OBJECTIVESolar ultraviolet (UV) radiation is an important environmental factor that affects human health. The understanding of diurnal variations of UV radiation at anatomical sites may be helpful in developing ways to protect humans from the harmful effects of UV radiation.

METHODSIn order to characterize the diurnal variations, the UV exposure values were measured at 30 min intervals by using Solar-UV Sensors and a rotating manikin in Shenyang city of China (41 degrees 51'N, 123 degrees 27'E). Measurement data for four representative days (in each of the four seasons respectively) were analyzed.

RESULTSThe diurnal variations in solar UV radiation at the shoulder, the forehead and the chest were similar to those associated with a horizontal control measurement. However, the diurnal variations at the eye and the cheek exhibited bimodal distributions with two peaks in spring, summer and autumn, and a unimodal distribution in winter. The UV exposure peaks at the eye and the cheek were measured at solar elevation angles (SEA) of about 30 degrees and 40 degrees , respectively.

CONCLUSIONThe protection of some anatomical sites such as the eye from high UV exposure should not be focused solely on the periods before and after noon, especially in the places and seasons with high SEA.

Circadian Rhythm ; Ultraviolet Rays

Having studied in vitro the effect of UVR on the two species of microorganisms which are most common as agents of surgical infection, we realized the closer the distance from the irradiation lamp and the longer the irradiation time, the stronger the bactericidal effect of UVR. When UVR is applied for air disinfection within the distance of more than 2 meters from the sunlamp irradiation, it can also reduce significantly the number of microorganisms in the air. It is due to the fact that there is a continuous air exchange between the upper and the lower part of the room. Previous studies and the experiments on petri dishes show that the use of UVR for cleaning infected wounds and preventing infection is an effective, simple and safe measure
Ultraviolet Rays ; Blood Bactericidal Activity