• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.1
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• pp.69-79
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• 2013

The aim of this study was to evaluate the effect of surface conditioning on the shear bond strength of zirconium-oxide ceramic to resin cement. A total of 120 disk-shaped zirconium-oxide ceramic blocks(3-TZP, Kyoritsu, Tokyo, Japan) were treated as follows: (1) no treatment; (2) sandblasting with 110 ${\mu}m$ aluminum-oxide(Al2O3); (3) particles tribochemical silica coating(RocatecTM, 3M ESPE). Then zirconium-oxide ceramic blocks were divided into six groups(10 for each group) and bonded with resin cement(Rely X U-200, 3M ESPE). (1) No treatment / No treatment (2) No treatment / Sandblasting with 110 ${\mu}m$ aluminum-oxide particles (3) No treatment / Silica coating (4) Sandblasting with 110 ${\mu}m$ aluminum-oxide particles / Sandblasting with 110 ${\mu}m$ aluminum-oxide particles (5) Sandblasting with 110 ${\mu}m$ aluminum-oxide particles / Silica coating (6) Silica coating / Silica coating. Each group was tested in shear bond strengths by UTM. Data analysis included one-way analysis of variance(ANOVA) and the Tukey Honestly Significant Difference test (P=0.05). Group that bonded two silica coated specimen showed a highest bond strength(P<0.05). Two silica coated surface conditioning group and air-abrasion and silica coated surface conditioning group showed significantly difference with other groups(P<0.05). Other groups had no significantly difference each other. Within the limitation of this study, Surface conditioning with Rocatec treatment to each side of specimen provided the highest bond strength.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.2
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• pp.80-87
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• 2017

Purpose: The aim of this study was to assess the physical properties of a novel resin-based endodontic sealer, Any-Seal, in comparison with AH Plus Jet. Materials and Methods: Flow, radiopacity and compressive strength were examined according to ISO 6876/2001. For flow test, 0.05 mL of sealer was placed between glass plate and 100 g weight were applied. Ten minutes after mixing the sealers, the load was removed and the diameters of the compressed sealer discs were measured. For radiopacity, 10 mm diameter and 1 mm thickness sample were fabricated and took radiograph with an aluminum step-wedge and analyzed using imaging program. For compressive strength test, $4mm{\times}6mm$ cylindrical specimen was fabricated and tested after 24 hours and 1 week using Universal testing machine. Results: Both tested sealers were consistent with ISO 6876/2001 in the flow and radiopacity test. The flow values of both sealers were not significantly different (P > 0.05). AH Plus Jet had significantly higher radiopacity (P < 0.05). AH Plus Jet showed higher compressive strength at both time intervals (P < 0.05). Conclusion: Any-Seal showed low compressive strength until after 1 week, so its physical and biological aspect should be evaluated more before clinical use.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.2
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• pp.102-111
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• 2014

Purpose: Surface damage and bonding strength difference after micromechanical treatment of zirconia surface are to be studied yet. The aim of this study was to evaluate the difference of fracture resistance and bonding strength between more surface-damaged group from higher air-blasting particle size and pressure, and less damaged group. Materials and Methods: Disk shape zirconia ($LAVA^{TM}$) was sintered and air-blasted with $30{\mu}m$ particle size (Cojet), under 2.8 bar for 15 seconds, $110{\mu}m$ particle size (Rocatec), under 2.8 bar for 15 seconds, and $110{\mu}m$ particle size (Rocatec), under 3.8 bar for 30 seconds respectively. Biaxial flexure test and bonding failure load test were performed serially (n = 10 per group). For bonding test, specimens were bonded on the base material having similar modulus of elasticity of dentin with $200{\mu}m$-thick resin cement for tension of surface damage. Failure load of bonding was detected with acoustic emission (AE) sensor. Results: There were no significant differences both in the biaxial flexure test and bonding failure load test between groups (P > 0.05). Sub-surface cracks were all radial cracks except for two specimens. Conclusion: Within the limitations of no aging under monotonic load test, surface damage from higher air-blasting particle size and pressure was not significant. Evaluations of failure load with bonded zirconia disks was clinically relevant modality for surface damage and bonding strength, simultaneously.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.3
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• pp.194-201
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• 2016

Purpose: The purpose of this study was to evaluate of Zirconium Nitride (ZrN) coating on shear bond strength with denture base resin in Co-Cr and Ti-6Al-4V alloy. Materials and Methods: Co-Cr and Ti-6Al-4V alloy disks (10 mm in diameter, 2.5 mm in thickness; each other: n = 14) were prepared and divided with 2 groups each other by ZrN coating. After primer was applied to disks surface, denture base resin with diameter 6 mm, height 5 mm was bonded on metal disk surface. After surface roughness was measured by Profiler, shear bond strength was determined with Universal testing machine and analyzed with two-way ANOVA. The specimen surfaces and failure mode were examined using a scanning electron microscope. Results: ZrN coated groups showed significantly higher rough surface than non-coated groups (P < 0.05). Irrespective of alloy materials, shear bond strength of ZrN coated groups were lower than non-coated groups (P < 0.001). The scanning electron microscope (SEM) of ZrN coated groups showed mixed and adhesive fractures. Conclusion: ZrN coating weakened bonding strength between denture base resin and Co-Cr, Ti-6Al-4V alloy.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.4
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• pp.361-369
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• 2008

The purpose of this study is to make porous oxide film on the surfaces of pure Ti through anodic spark discharge in electrolytic solution containing calcium and phosphate ions, to improve osseointergration by treating fluoride agent. In addition, it is to evaluate the fluoride modified effect on the surface. Commercial pure Ti plate with $20{\times}10{\times}2mm$ and Ti wire with a diameter of 1.5mm and a total length of 15mm were used. After making titanium oxide films converted by anodic spark discharge, anodizing was performed. Fluoride was spreaded to titanium laboratory plate and maintained for 30 minutes after anodizing breakdown. Fluoride ion discharge amount was measured per 24 hours after dipping titanium plate into saline (10ml) and sustaining 90rpm in a pyrostat. Some plates and wires were dipped in Hanks solutions for a month to examine biocompatibility using SEM and XRD. $TiO_2$ film formed by anodic discharge technique showed great roughness and uniform pores which were $1{\sim}3{\mu}m$ in a diameter. Roughness of the films treated with anodic discharge after blasting were higher than the turned ones(P<0.05). Rapid surface activity was observed in the samples treated with $TiF_3$ agent, which immersed in Hanks solution for 30 days. Taking the results into consideration, the fluoride modified implant with anodic discharge demonstrates that it makes uniformly porous oxide film on the surface of implant and properly increase roughness for osseointegration. The implants will achieve greater bone integration after short healing time by improving surface activity.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.3
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• pp.111-122
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• 2021

Purpose: The purpose of this in vitro study was to investigate the flexural strength and translucency of three layers in 5Y-ZP and to assess the effect of additional firings on these properties. Materials and Methods: Sintered zirconia blocks were sectioned according to three layers : incisal, transition, and body. Disc-shaped specimens were fabricated from each layer. The diameter of specimens was 15.0 mm and each thickness of specimens for biaxial flexural strength test and translucency was 1.2 mm and 1.0 mm. The specimens were classified into subgroups according to the number of firing (0, 1, and 3 times; n = 10/subgroup) and the additional firings were performed under 900℃ using a furnace. Biaxial flexural strength and translucency was measured using universal testing machine and uv-vis spectrophotometer. X-ray diffraction (XRD) analysis was used for measurement of the phase identification. One-way ANOVA, Tukey HSD test were performed (α = 0.05). Results: There was no significant difference in flexural strength between the three layers (P > 0.05), while there was significant difference in translucency between different layers (P < 0.05). The flexural strength of incisal and transition layer was decreased by the single additional firing, and the three additional firings significantly decreased the flexural strength of three layers. The translucency of layer was decreased by additional firings except the body layer. The XRD patterns of all groups were similar. Conclusion: Three layers of 5Y-ZP were different only in translucency. Additional firings affected the flexural strength and translucency differently depending on the layers but crystalline phases were not changed.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.3
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• pp.123-129
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• 2021

Purpose: The purpose of this study was to investigate antifungal activity of shiitake mushroom yeast and hyphal type of Candida albicans. Materials and Methods: The extract from shiitake mushroom was collected by drying the supernatant after soaking shiitake mushrooms in water or ethanol. The antifungal activity of the extracts against yeast type of C. albicans was investigated by the susceptibility assay using microplate. C. albicans biofilm was formed on 12-well plate using Ham's F-12 medium in CO₂ incubator and treated with the ethanol extract. Furthermore, C. albicans biofilm was formed on denture base resin disk and treated with or without the ethanol extract in the presence of denture cleanser. Live C. albicans in biofilm was counted by cultured colony forming unit value after inoculated on agar plate. Results: Ethanol extract from shiitake mushroom showed stronger antifungal activity against yeast type of C. albicans compared to its water extract. The ethanol extract significantly reduced count of C. albicans in hyphal biofilm (P < 0.05). Also, the ethanol extract showed synergistically antifungal effect with denture cleanser on candidal biofilm on denture base resin disk (P < 0.05). Conclusion: The ethanol extract of shiitake mushroom may be a candidate for preventing candidal stomatitis as well as denture-related stomatitis.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.4
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• pp.361-374
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• 2009

For successful osteogenesis around the implants, interaction between implant surface and surrounding tissue is important. Biomechanical bonding and biochemical bonding are considered to influence the response of adherent cells. But the focus has shifted surface chemistry. The purpose of this study is to evaluate the MC3T3-E1 osteoblast like cell responses of magnesium (Mg) ion implanted titanium surface produced using a plasma source ion implantation method. Commercially pure titanium disc was used as substrates. The discs were prepared to produce four different surface, A: Machine turned surface, B: Mg implanted surface, C: sandblasted surface, D: sandblasted and Mg implanted surface. MC3T3 El osteoblastic like cells were cultured on the disc specimens. Cell adhesion, proliferation, differentiation, and synthesis of extracellular matrix were evaluated. The cell adhesion morphology was evaluated by SEM. RT PCR assay was used for assessment of cell adhesion, proliferation and differentiation. ALP activity was measured for cell differentiation. The results of this study were as follows: 1. SEM showed that cell on Mg ion groups was more proliferative than that of non Mg ion groups. On the machine turned surface, cell showed some degree of contact guidance in aligning with the machining grooves. 2. In RT PCR analysis, osteonectin and c-fos mRNA were more expressed on sandblasted and Mg ion implanted group. 3. ALP activity was not significantly different among all groups. Within the limitations of this study, the following conclusions were drawn: It might indicate Mg ion implanted titanium surface induce better bone response than non Mg ion groups.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.2
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• pp.83-94
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• 2009

The aim of this study was to investigate the shear bond strength between zirconia ceramic and resin cement according to various surface treatments. The surface of each zirconia ceramic was subjected to one of the following treatments and then bonded Rely X Unicem or Rely X ARC resin cement; (1) Rocatec system and $50{\mu}m$ surface polishing, (2) No treatment and $50{\mu}m$ surface polishing, (3) Rocatec system and $1{\mu}m$ surface polishing, (4) No treatment and $1{\mu}m$ surface polishing. Each of eight bonding group was tested in shear bond strengths by universal testing machine(Z020, Zwick, Ulm, Germany) with crosshead speed of 1mm/min. The results were as follows; 1. Rocatec treatment groups showed greater bonding strengths than No Rocatec groups. There was significant difference of among groups(P<0.001) 2. For Rocatec groups, $50{\mu}m$ surface roughness groups showed greater bonding strengths than $1{\mu}m$ surface roughness groups.(P<0.001) But for No Rocatec groups, There was no significant difference of among groups(P>0.05) 3. Rely X Unicem groups showed greater bonding strengths than Rely X ARC groups. There was significant difference of among groups(P<0.01) Within the conditions of this study, Rocatec treatment was an effective way of increasing zirconia bonds to a resin cement, even in the case of self-adhesive resin cement.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.1
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• pp.18-25
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• 2022

Purpose: This study aimed to evaluate the color stability and antibacterial properties of the surface of polyethyl methacrylate (PEMA) resin with zirconia nanoparticles added. Materials and Methods: The control group was pure PEMA resin, and the experiment group was PEMA resin 15 mm in diameter and 2.5 mm in thickness disk-shaped specimens with 2, 4 and 8 w/v% of zirconia nanoparticles added, which were respectively divided into Group Z2, Group Z4, and Group Z8. After analyzing the surface roughness and color stability of the specimens, their antibacterial properties were evaluated using Porphyromonas gingivalis (P. gingivalis). The Statistical analysis was performed using when normality was met in the Shapiro-Wilk test, one-way ANOVA was used to test parameters, and Tukey's test was used as a post hoc test. When normality was not met, the Kruskal-Wallis test, a non-parametric test was used (P < 0.05). Results: The surface roughness measurement found that there was no significant difference between the experimental and control groups. The color stability evaluation showed that the Z2, Z4, and Z8 groups were within the color range of natural teeth. The adhesion of P. gingivalis was evaluated to be significantly reduced in Group Z2 compared to the control group (P < 0.05). In the Z2 group, Z4 group, and Z8 group, dead cells bacteria than the control group were observed. Conclusion: In conclusion, PEMA resin with zirconia nanoparticles added was within the range of natural teeth in color and reduced the adhesion of P. gingivalis.