Effect of atmospheric pressure cold plasma on tooth bleaching and enamel surface roughness

The aim of the present study was to investigate the combinational effect of atmospheric pressure cold plasma and hydrogen Peroxide bleaching agents on external tooth bleaching. Teeth were randomly divided into three groups: 15% hydrogen peroxide＋Air flow plasma (Air plasma), 15% hydrogen peroxide＋Nitrogen plasma (Nitrogen plasma) and 15% hydrogen peroxide only (control). The color change of the teeth was evaluated before treatment) 10 min and 20 min after treatment using a spectrophotometer. Surface roughness(Ra) was measured by profilometer at before and after 20 min treatment. There was significant differences in color change between the plasma treated groups and control (p＜0.05), there being no significant difference between the two plasma groups (p＞0.05). There were no significant differences in surface roughness among all group (p＞0.05). Hence, we conclude that the atmospheric pressure cold plasma treatment may accelerates the teeth bleaching process no matter which kind of gases (Air plasma and Nitrogen plasma) is used.ope

Effects of a Non-Thermal Atmospheric Pressure Plasma Jet with Different Gas Sources and Modes of Treatment on the Fate of Human Mesenchymal Stem Cells

Despite numerous attempts to use human mesenchymal stem cells (hMSCs) in the field of tissue engineering, the control of their differentiation remains challenging. Here, we investigated possible applications of a non-thermal atmospheric pressure plasma jet (NTAPPJ) to control the differentiation of hMSCs. An air- or nitrogen-based NTAPPJ was applied to hMSCs in culture media, either directly or by media treatment in which the cells were plated after the medium was exposed to the NTAPPJ. The durations of exposure were 1, 2, and 4 min, and the control was not exposed to the NTAPPJ. The initial attachment of the cells was assessed by a water-soluble tetrazolium assay, and the gene expression in the cells was assessed through reverse-transcription polymerase chain reaction and immunofluorescence staining. The results showed that the gene expression in the hMSCs was generally increased by the NTAPPJ exposure, but the enhancement was dependent on the conditions of the exposure, such as the source of the gas and the treatment method used. These results were attributed to the chemicals in the extracellular environment and the reactive oxygen species generated by the plasma. Hence, it was concluded that by applying the best conditions for the NTAPPJ exposure of hMSCs, the control of hMSC differentiation was possible, and therefore, exposure to an NTAPPJ is a promising method for tissue engineering.ope

온열요법을 위한 실리카가 코팅된 골드 코어-쉘 나노입자의 합성 및 평가

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Survey study on the using state of dentin bonding systems in Korea

Dentin bonding systems are unique dental materials which are rapidly evolute and essential materials for bonding of restorative materials to dentin. Now, 4th generation, 5th generation, 6th generation and 7th generation of dentin bonding systems are used in clinic. We investigated the frequency, motivation of choosing dentin bonding systems and satisfaction of them by survey in 2014. 5th generation of dentin bonding systems are mostly used in Korea and young dentist have tendency to choose newly developed dentin bonding systems.ope

칼슘 포스페이트 골 시멘트에서의 테트라사이클린 방출 거동

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Evaluation of Physical Properties of Titanium Specimen Fabricated by 3D Printing Technique

The interest of the additive manufacturing technology, commonly called 3D printing, is rapidly increasing. Selective laser sintering (SLS) is the one of the method for 3D printing that has potential to produce metallic prostheses in dentistry. The purpose of this study was to evaluate physical properties of titanium specimen fabricated by SLS for dental implant system. Specimens were fabricated from Ti6Al4V alloy powder with median particle size (D50) of 34 μm. The SLS 3D printing was carried out using YAG laser with wavelength of 1075 nm with power of 190 W, and thickness of each layer was 30 μm. Machined specimens with sandblasting treatment were used as control group. Density, porosity, yield strength (30o compression), elastic modulus and fatigue limit were estimated. Density measurement and microCT analysis gave valuable informations about impurity inclusions and manufacturing defects. Yield strength and elastic modulus of 3D printing dense specimen showed similar value with the machined specimens. However, fatigue limit of 3D printing dense specimens was significantly lower than the machined specimen. 3D printing porous specimen showed lower yield strength and elastic modulus than the 3D printing dense specimens. Before 3D printing porous dental prosthesis application in clinic, fatigue limit should be evaluated carefully.ope

In Vitro Effects of Cyclic Dislodgement on Retentive Properties of Various Titanium-Based Dental Implant Overdentures Attachment System

The purpose of this study was to evaluate the change in the retentive forces of four different titanium-based implant attachment systems during the simulation of insert-removal cycles in an artificial oral environment. Five types of titanium-based dental implant attachment systems (Locator, Kerator, O-ring, EZ-Lock, and Magnetic) were studied (n = 10). The specimens underwent insert-removal cycles in artificial saliva, and the retentive force was measured following 0, 750, 1500, and 2250 cycles. Significant retention loss was observed in all attachment systems, except the magnetic attachments, upon completion of 2250 insertion and removal cycles, compared to the initial retentive force (p < 0.05). A comparison of the initial retentive forces revealed the highest value for Locator, followed by the Kerator, O-ring, EZ-Lock, and Magnetic attachments. Furthermore, Kerator demonstrated the highest retentive loss, followed by Locator, O-ring, EZ-Lock, and Magnetic attachments after 2250 cycles (p < 0.05). In addition, the Locator and Kerator systems revealed significant decrease in retentive forces at all measurement points (p < 0.05). The retention force according to the insert-removal cycles were significantly different according to the types of dental implant attachment systems.ope

A Study on the Fluoride Release, Microhardness and Cytotoxicity of Fluoride Releasing Restorative Materials

The objective of this study was to examine fluoride release, microhardness and cytotoxicity of three different types of restorative materials; giomer (Beautifil Ⅱ), composite resin (FiltekTM Z250) and glass ionomer (Fuji Filling LC). Samples were prepared as disk-shaped specimens with diameter of 10 mm and thickness of 1 mm. Fluoride release was measured using pH meter (920A, Orion, Boston, USA) every 24 hours for the first 7 days followed by measurement every week until the 28th day. The Vickers hardness measurement was carried out for the microhardness, while in vitro cytotoxicity test of agar diffusion test was carried out according to ISO 10993-5 and ISO 7405. The results showed that microhardness of FiltekTM Z250 was the highest, followed by Beautifil Ⅱ, and Fuji Filling LC, in order. All groups, except FiltekTM Z250 released most amount of fluoride during first 24 hours and the release level was decreased over time. Cytotoxicity test indicated that all experimental materials were mildly toxicity. This study confirmed the variability of fluoride release, microhardness and cytotoxicity in these restorative materials and therefore such features should be considered in clinical application.ope

Enamel Demineralization Resistance and Remineralization by Various Fluoride-Releasing Dental Restorative Materials

The aim of this study is to investigate the resistance of various fluoride-releasing restorative materials against the demineralization and remineralization of enamel surfaces, including those that have been recently introduced to the market. Three different fluoride-releasing restorative materials were considered: glass ionomer (FI), resin-modified glass ionomer (RL), and an alkasite restorative material (CN). The acid neutralization ability was investigated using pH measurement, and the concentrations of released fluoride and calcium ions were measured. Finally, the demineralization resistance and remineralization effects of enamel were observed using a microhardness tester and SEM. CN showed an initial substantial increase in pH followed by a steady increase, with values higher than those of the other groups (p < 0.05). All three groups released fluoride ions, and the CN group released more calcium ions than the other groups (p < 0.05). In the acid resistance test, from the microhardness and SEM images, the CN group showed effective resistance to demineralization. In the remineralization test, the microhardness results showed that the FI and CN groups recovered the microhardness from the values of the demineralized enamel surface (p < 0.05). This was confirmed by the SEM images from remineralization tests; the CN group showed a recovered demineralized surface when immersed in artificial saliva for 7 days. In conclusion, alkasite restorative material can be an effective material when used in cariogenic environments.ope

The Effect of 15% Carbamide Peroxide on the Surface Roughness and Staining of Esthetic Restoratives

The purpose of this study was to evaluate the surface change after 15% carbamide peroxide home bleaching to various restorative materials (composite resin [CR], resin modified glass ionomer [RMGI] and glass ionomer [GI]) and to observe the effect of surface condition of the materials on re-staining. Three esthetic restorative materials (Filtek Z250, 3M, USA; Fuji II LC, GC, Japan; Fuji II, GC, Japan) were used in this study. Twenty specimens per material group were made and divided into two groups (bleached and control). The specimens were immersed in coffee after applying bleaching agent. The color change and surface roughness were measured before and after bleaching and after immersion in coffee. The data were analyzed with SPSS 18.0. The results were as follows: 1. The color of all experiment groups was significantly changed after bleaching (p＜0.05). RMGI was the greatest value of ∆E* and ∆L*. GI and CR groups were in ordering (p＜0.05). The ∆a* value was decreased GI, RMGI and CR. RMGI was only significantly decreased in ∆b* value (p＜0.05). 2. The surface roughness before and after bleaching was significantly different on CR, RMGI and GI (p＜0.05). 3. After staining with coffee, the value of ∆E* was increased in GI, RMGI and CR, furthermore GI and RMGI showed significant difference in the bleaching groups (p＜0.05). The ∆L* value of GI and RMGI was significantly decreased. 4. The change of surface roughness after staining was not significantly different in all groups (p＞0.05). The maintenance of color stability in esthetic restorations is one of the most important properties. Tooth whitening is for the aesthetic. Therefore, dental professionals should notice to patients about re-staining after tooth whitening. They should give an instruction that how to prevent and which kinds of agents could be stained.ope