Antibacterial Activity of Propolis-Embedded Zeolite Nanocomposites for Implant Application.

This study investigates the potential of propolis-embedded zeolite nanocomposites for dental implant application. Propolis-embedded zeolite nanocomposites were fabricated by complexation of propolis and zeolites. Then, they were pelleted with Poly(L-lactide) (PLA)/poly(ε-caprolactone) (PCL) polymer for the fabrication of a dental implant. The chemical properties of propolis were not changed during the fabrication of propolis-embedded zeolite nanocomposites in attenuated total reflection-fourier transform infra-red (ATR FT-IR) spectroscopy measurements. Propolis was continuously released from propolis-embedded zeolite nanocomposites over one month. PLA/PCL pellets containing propolis-embedded zeolite nanocomposites showed longer sustained release behavior compared to propolis-embedded zeolite nanocomposites. Propolis-embedded zeolite nanocomposite powder showed similar antibacterial activity against C. albicans in an agar plate and formed an inhibition zone as well as chlorohexidine (CHX) powder. Eluted propolis solution from PLA/PCL pellets also maintained antibacterial activity as well as CHX solution. Furthermore, eluted propolis solution from PLA/PCL pellets showed significant antibacterial efficacy against C. albicans, S. mutans and S. sobrinus. Dental implants fabricated from PLA/PCl polymer and propolis-embedded zeolite nanocomposites also have antibacterial efficacy and negligible cytotoxicity against normal cells. We suggest that PLA/PCl pellets containing propolis-embedded zeolite nanocomposites are promising candidates for dental implants.

Effect on Cell Viability with the Passage of Time After Atmospheric Plasma Treatment on Titanium Dioxide Surface.

Various attempts to modify the surface of dental implants have been made in order to improve the adhesion of osteocytes. Plasma treatment on dental implants has been suggested to improve osseointegration. This study examined the effect on cell viability with the passage of time after atmospheric plasma treatment. An atmospheric plasma generator (PGS-200 Plasma generator, Expantech Co., Korea) was used and the gas was mixed with the Ar2(99%)/O2(1%) composition and applied to the specimens. The passage of time was set to 7 immediately after treatment, after 30 minutes of treatment, after 60 minutes of treatment, after 90 minutes of treatment, after 24 hours of treatment, and after 48 hours of treatment. Surface property change with the passage of time after plasma treatment were confirmed by FE-SEM, surface roughness and X-ray photoelectron spectroscopy. Cell viability was evaluated by the WST-8 assay. The data were analyzed statistically using a 1-way ANOVA and Tukey's multiple comparisons test (α = .05). It was confirmed that the chemical composition of the surface changes as the passage of time increases after plasma treatment. The viability of L-929 cells was the highest immediately after plasma treatment, and cell viability decreased with increasing the passage of time. As a result of this study, it was confirmed that passage of time is a very important factor for the plasma treated surface.

Effect of Atmospheric Pressure Plasma Treatment on Shear Bond Strength Between Zirconia and Dental Porcelain Veneer.

Various surface treatments on zirconia have been reported for dental porcelain veneer. However, it has not been determined which of these treatments provide the highest bond strength. The purpose of this study is to compare the effect of airborne particle abrasion and atmospheric pressure plasma treatment on the shear bond strength between zirconia and dental porcelain veneer. The groups were divided into four groups according to the surface treatment method: the control group, the atmospheric pressure plasma treated group (group P), the airborne particle abrasion group (group A), the atmospheric pressure plasma treated group after the airborne particle abrasion (group AP). Atmospheric pressure plasma was applied on the specimens using a plasma generator (Plasma JET, POLYBIOTECH Co. Ltd., Gwangju, Korea) and airborne-particle abraded with 110 µm. The characteristics of surface treated zirconia were analyzed by 3D-OP, XRD, XPS and contact angle. The shear bond strength was tested using a universal testing machine. The shear bond strength of group P was significantly increased compared to that of the control group (P < 0.05). The shear bond strength of group AP was significantly increased as compared to group A (P < 0.05). There was no significant difference between the group P and group A (P > 0.05). As a result of this study, the atmospheric pressure plasma treatment showed significantly higher shear bond strength than control group, but similar to the airborne particle abrasion, and the atmospheric pressure plasma treatment after the airborne particle abrasion provided the highest shear bond strength. This study demonstrated that application atmospheric pressure plasma treatment on zirconia may be useful for increasing bond strength between zirconia and dental porcelain veneer.

Assessment of Inhibition of Biofilm Formation on TiO2 Nanotubes According to Non-Thermal Plasma Treatment Conditions and the Elapsed Time in the Atmosphere.

Periimplantitis is an inflammation similar to periodontitis, and is caused by biofilms formed on the surface of dental implants. Application of plasma on biomaterials has been reported to decrease the initial adhesion of microorganism by causing chemical changes without changing the surface morphology. The purpose of this study is to evaluate the effect of inhibition of biofilm formation on the elapsed time after plasma treatment. Non thermal plasma generator (PGS-200 Plasma generator, Expantech Co., Korea) was applied to the specimens. The elapsed time in the atmosphere was set to 5 immediately after treatment, after 30 minutes of treatment, after 60 minutes of treatment, after 90 minutes of treatment. Surface property change with the elapsed time in the atmosphere after plasma treatment were confirmed by X-ray photoelectron spectroscopy and contact angle. Inhibition of biofilm formation was evaluated by the fluorescent nucleic acid staining. It was confirmed that the chemical composition and bonding state of the surface changes as the elapsed time in the atmosphere increases after plasma treatment. The adhesion of Porphyromonas gingivalis was the lowest immediately after plasma treatment, and increased again with increasing elapsed time in the atmosphere after plasma treatment. As a result of this study, it was confirmed that elapsed time in the atmosphere is a very important factor for inhibition of biofilm formation.

Wear Behavior of the Human Enamel Antagonist to Different Glazed Zirconia.

In this study, the wear behavior of glazed zirconia was investigated to the antagonist with human enamel after simulated mastication. Twenty Y-TZP specimens were divided into 4 groups: untreated zirconia (Z), glazed zirconia with IPS e.max Ceram (GZE), glazed zirconia with VITA AKZENT® Plus (GZV), and glazed zirconia with glass (GZG). Glazing glass was mainly composed of SiO2, B2O3, Al2O3, Na2O and K2O (nearly 91 wt%). The surface roughness of the specimens was evaluated using roughness profiler. The maxillary premolar teeth were selected as the antagonist. The wear of human enamel against human enamel was used as a control. Five-disc specimens per group were subjected to chewing stimulation CS-4 (SD Mechatronic GmbH, Germany) for 240,000 cycles against human enamel. The wear loss of antagonistic teeth was calculated using a three-dimensional profiling system and the volume loss of the tooth was scanned using a 3D scanner. 3D data obtained before and after testing were overlapped using 3D software (Dentacian Software, EZplant, Korea). The wear loss of glazed zirconia GZE, GZV and GZG groups showed significantly lower than that of human enamel. Whereas, the zirconia (Z) group exhibits significantly lower volume loss than glazed zirconia and enamel. These results show that the wear of the glazing glass is comparable to other commercial glazing materials. Glazing materials are both more susceptible to wear the antagonist relative to zirconia.