• The korean journal of orthodontics
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• v.30 no.1 s.78
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• pp.83-89
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• 2000

The purposes of this study were to evaluate clinical applicability of resin modified glass ionomer cements and to determine the effect of salivary contamination on the tensile bond strength. Fourty extracted human permanent premolars were prepared lot bonding and standard edgewise brackets were bonded with Ortho-One, Fuji Ortho LC, Vitremer and Advance. Fourty extracted human permanent premolars were contaminated with saliva, dried and bonded with same materials above. The tensile bond strength was tested by Instron testing device aster storage in normal saline at ,$37^{\circ}C$ for 24 hours from bonding. The results were as follows : 1. The tensile bond strength of Ortho-One group was $7.68\pm1.76$, Advance group was $7.87\pm2.80$, Fuji Ortho LC group was $4.99\pm2.53$, Vitremer group was $2.80\pm0.88$ MPa. The tensile bond strength in contaminated condition of Ortho-One group was $4.12\pm1.67$, Advance group was $5.37\pm0.68$, Fuji Ortho LC group was $4.41\pm1.61$, Vitremer group was $2.60\pm1.10$ Mpa. 2. Salivary contamination did not affect the tensile bond strength when compared with the uncontaminated enamel group in Fuji Ortho LC and Vitremer (p>0.05) and there was great significant difference in the tensile bond strength of Ortho-One and Advance. 3. Advance, Ortho-One and Fuji Ortho LC seemed to have clinically a proper bond strength.

• Restorative Dentistry and Endodontics
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• v.33 no.5
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• pp.419-427
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• 2008

This study analyzed the influence of dental adhesive/primer on the bond strength between indirect resin composite and the resin cement. Seventy disc specimens of indirect resin composite (Tescera Dentin, Bisco) were fabricated. And bonding area of all specimens were sandblasted and silane treated for one minute. The resin cements were used with or without application of adhesive/primer to bonding area of indirect resin restoration, Variolink-II (Ivoclar-Vivadent) : Exite DSC, Panavia-F (Kuraray) : ED-Primer, RelyX Unicorn (3M ESPE) Single- Bond, Duolink (Risco) : One-step, Mulitlink (Ivoclar-Vivadent) : Multilinh Primer. Shear bond strength was measured by Instron universal testing machine. Adhesive application improved shear bond strength (p<0.05) But Variolink II and Panavia-F showed no statistically significant difference according to the adhesive application. With the above results, when resin inlay is luted by resin cement it seems that application of dental adhesive/primer is necessary in order to improve the bond strength.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.2
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• pp.112-118
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• 2012

Purpose: The purpose of this study was to evaluate the difference in shear bonding strength between resin cements to dental materials when a universal primer (Monobond plus) was applied in place of a conventional primer. Materials and methods: Four groups of testing materials: gold alloy (Argedent Euro, n = 16), non precious metal (T-4, n = 20), zirconia (Cercon, n = 20) and glass ceramic (IPS e.max press, n = 20), were fabricated into discs, which were embedded in an acrylic resin matrix. The gold alloy specimens were airborne-particle abraded, 8 of the specimens were coated with Metal primer II, while the remaining 8 specimens were coated with Monobond plus. The non precious and zirconia specimen were airborne-particle abraded then, the control group received Alloy primer coating, while the other was coated with Monobond plus. Glass ceramic specimens were etched. 10 specimens were coated with Monobond-S and the remaining specimens were coated using Monobond plus. On top of the surface, Multilink N was polymerized in a disc shape. All of the specimens were thermal cycled before the shear bonding strength was measured. Statistical analysis was done with Two sample $t$-test or Mann-Whitney U test (${\alpha}$=.05). Results: There were no significant differences in bonding strength depending on the type of primer used in the gold alloy and glass ceramic groups ($P$>.05), however, the bonding strengths of resin cements to non precious metal and zirconia groups, were significantly higher when the alloy primer was used ($P$<.05). Conclusion: Within the limitations of this study, improvement of universal primers which can be applied to all types of restorations is recommended to precious metals and zirconia ceramics. But, the bond strengths of non precious metals and zirconia ceramics were significantly lower when compared to a 10-MDP primer. More research is needed to apply universal primers to all types of restorations.

• Korean Journal of Materials Research
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• v.3 no.6
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• pp.668-677
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• 1993

The microstructural and shear tests of STS304/, STS430/ and low-C steel/Cu joints brazed using Cu-P, Cu-P-Sn(four type) and Cu-P-Sn-Ag(three type) filler metals at 1003 and 1033K for 1.2ks in Ar atomsphere were performed. Interfacial microstructures were divided into three type ; first, reaction layer contained cracks second, dispersed layer without cracks third, dispersed layer and reaction layer contained cracks. The joints composed only of dispersed layer without cracks have the high shear strength of above 40-60 MPa and result in failure in copper base metal. Low shear strength and joint failure result from the formation of reaction layer which induced cracks. The reaction layer is a Fe-P compound. This tendency of microstructure and shear strength depends on the existence and/or nonexistence of Sn in filler metals as well as Ni (and Cr) in base metals.

• Journal of Technologic Dentistry
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• v.37 no.4
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• pp.219-227
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• 2015

Purpose: The purpose of this study was to evaluate the effect of the chemical surface treatment on the flexural bond strength of heat curing denture base resin and reliners. Methods: Denture base resin surface was treated with MMA 95% and TEGDMA 5%, MMA 95% and silane coupling agent 5%, heat curing resin monomer. After denture reliners were injected, flexural bond strength was measured. Results: The repair resin of Vertex SC was higher than Lang, hard reliner of Kooliner was higher than Rebase. Soft reliner of Dura base and Coe-soft showed differently according to the surface treatment. The all chemical treatment groups on Vertex SC were significantly higher than control(p<0.05). In Lang group, 5% MPS treated group showed significantly higher flexural bond strength than others(p<0.05). In Kooliner group, all chemical treatment groups showed significantly higher than control(p<0.05). In Rebase group, the 5% MPS and the monomer denture base resin treated groups showed significantly higher than others(p<0.05). In Dura base group, 5% MPS treated group showed significantly higher flexural bond strength than others(p<0.05). In Coe-soft group, all treated groups were significantly higher than control group(p<0.05). Conclusion: TEGDMA, MPS, and the monomer of heat-cured denture base resin were effective to improve the bond strengths between denture base and denture relining materials. Especially, 5% MPS expected to strengthen effectively the bonding property of denture base and denture reliners within the results of this study.

• The Journal of Advanced Prosthodontics
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• v.3 no.4
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• pp.221-228
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• 2011

PURPOSE. Veneering porcelain might be delaminated from underlying zirconia-based ceramics. The aim of this study was the evaluation of the effect of different surface treatments and type of zirconia (white or colored) on shear bond strength (SBS) of zirconia core and its veneering porcelain. MATERIALS AND METHODS. Eighty zirconia disks (40 white and 40 colored; 10 mm in diameter and 4 mm thick) were treated with three different mechanical surface conditioning methods (Sandblasting with $110{\mu}m$ $Al_2O_3$ particle, grinding, sandblasting and liner application). One group had received no treatment. These disks were veneered with 3 mm thick and 5 mm diameter Cercon Ceram Kiss porcelain and SBS test was conducted (cross-head speed = 1 mm/min). Two and one way ANOVA, Tukey's HSD Past hoc, and T- test were selected to analyzed the data (${\alpha}=0.05$). RESULTS. In this study, the factor of different types of zirconia ceramics (P=.462) had no significant effect on SBS, but the factors of different surface modification techniques (P=.005) and interaction effect (P=.018) had a significant effect on SBS. Within colored zirconia group, there were no significant differences in mean SBS among the four surface treatment subgroups (P=0.183). Within white zirconia group, "Ground group" exhibited a significantly lower SBS value than "as milled" or control (P=0.001) and liner (P=.05) groups. CONCLUSION. Type of zirconia did not have any effect on bond strength between zirconia core and veneer ceramic. Surface treatment had different effects on the SBS of the different zirconia types and grinding dramatically decreased the SBS of white zirconia- porcelain.

• The Journal of Advanced Prosthodontics
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• v.10 no.5
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• pp.340-346
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• 2018

PURPOSE. In this study, the shear bond strengths (SBS) of luting cements to fixed superstructure metal surfaces under various seating forces were investigated. MATERIALS AND METHODS. Seven different cements [Polycarboxylate (PCC), Glass-Ionomer (GIC), Zinc phospahate (ZPC), Self-adhesive resin (RXU), Resin (C&B), and Temporary cements ((RXT) and (TCS))] were bonded to a total number of 224 square blocks ($5{\times}5{\times}3mm$) made of one pure metal [Titanium (CP Ti) and two metal alloys [Gold-Platinum (Au-Pt) and Cobalt-Chrome (Co-Cr)] under 10 N and 50 N seating forces. SBS values were determined and data were analyzed with 3-way ANOVA. Pairwise comparisons and interactions among groups were analyzed with Tukey's simultaneous confidence intervals. RESULTS. Overall mean scores indicated that Co-Cr showed the highest SBS values ($1.96{\pm}0.4$) (P<.00), while Au-Pt showed the lowest among all metals tested ($1.57{\pm}0.4$) (P<.00). Except for PCC/CP Ti, RXU/CP Ti, and GIC/Au-Pt factor level combinations (P<.00), the cements tested under 10 N seating force showed no significantly higher SBS values when compared to the values of those tested under 50 N seating force (P>.05). The PCC cement showed the highest mean SBS score ($3.59{\pm}0.07$) among all cements tested (P<.00), while the resin-based temporary luting cement RXT showed the lowest ($0.39{\pm}0.07$) (P<.00). CONCLUSION. Polycarboxylate cement provides reliable bonding performance to metal surfaces. Resin-based temporary luting cements can be used when retrievability is needed. GIC is not suitable for permanent cementation of fixed dental prostheses consisting of CP Ti or Au-Pt substructures.

• Journal of the Korean Chemical Society
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• v.37 no.4
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• pp.408-415
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• 1993

Systematic ab initio SCF calculations have been performed on the hydrogen-bonded dimers of fluoromethanes involving $CH_4,\;CH_3F,\;CH_2F_2\;and\;CHF_3$ with ammonia and water applying basis sets of 9s5p/5s and 9s5p1d/5p1d. Various ground state properties of these stable dimeric complexes have been evaluated. We compared these with corresponding properties of isolated monomers. We report equilibrium geometries, stabilization energies, dipole moments and force constants of intermolecular bonds. The effects arising as a consequence of the non-additive behavior of hydrogen bonding in chain-like oligomers are discussed. Systematic, methodical errors due to the use of the SCF approximation and the basis set dependence of the computed results are pointed out.

• Applied Chemistry for Engineering
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• v.34 no.1
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• pp.57-63
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• 2023

In this study, an organic-inorganic hybrid composite of Abaca nanocellulose and titanium dioxide was prepared. Abaca nanocellulose was prepared by oxidizing Abaca cellulose using TEMPO (2,2,6,6-tetramethyl-piperidine-1-oxyl) as a catalyst. Titanium dioxide nanoparticles were prepared by the sol-gel method, and a composite was prepared by hybridizing them with nanocellulose. As a result of comparing the properties of the composite and its physical properties according to the change in manufacturing pH, the effect of pH was very large when combining nanocellulose and titanium dioxide, and the optimal bonding performance was shown at pH 8 in this experimental condition. In addition, the prepared composite showed photocatalytic properties, and the higher the content of titanium dioxide, the higher the hydrophilicity of the composite according to UV light irradiation.

• Journal of the Korean institute of surface engineering
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• v.56 no.1
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• pp.94-103
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• 2023

The effects of carburizing pressure and gas ratio on vacuum carburizing properties (uniformity and surface characteristics) have been studied through the analyses of carbon concentration, hardness, surface color, surface roughness and type of carbon bonding. AISI 4115 steel specimens were carburized with various pressures (1, 5, and 10 Torr) at different locations (P₁, P₂, P₃, P₄, P₅, and P₆) inside a furnace held at 950 ℃. Since the carburizing pressure represents the density of the carburizing gas, it plays an important role in improving the carburizing uniformity according to locations in the furnace. As the carburizing pressure increased, the carburizing uniformity according to the sample location was improved, but the surface of the carburized specimen was discolored due to the residual acetylene gas, which does not contribute to the carburizing reaction. Therefore, the carburizing uniformity and surface discoloration have been improved by injecting acetylene gas (carburizing gas) and nitrogen gas (non-reactive gas) in a specific ratio.