• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.622-636
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• 1997

Glass ionomer cements, which had been developed in 1972, were widely used as an agent for cementation, base, pit and fissure sealant, and esthetic filling material with the advantages of excellent biocompatibility, anti-cariogenic fluoride release. Specimens were made to evaluate the color change of Glass ionomer cement with a newly developed improved Fuji II Le. Specimens for color change study with cement thickness of 1, 2, 3mm were made and those for the study of color shift pattern were made with the assumption that new mid-shade can be made by mixing of equal amount of both shades in 2mm thickness. After 24 hours in a $37^{\circ}C$ incubator, CIELAB color spaces were evaluated with a spectrophotometer. The results were as follows ; 1. All specimens discolored to dark and blue with an increased thickness in all shades (p<0.05). 2. There were significant $a^*$ space (red-green direction) changes in every A, B, C, D shade series except the relationship between 1mm and 2mm thickness groups in B shade series. But the changes were irregular, i.e., each shade series has its own pattern. 3. Each shade series showed its own specific color shift pattern in all $L^*$, $a^*$, $b^*$ spaces. 4. B shade series showed less amont of changes in ${\Delta}{\pm}E$ than those of A and C shade series (p<0.05), but there was no significant difference in ${\Delta}E$ within each shade series.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.1
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• pp.1-9
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• 2015

Purpose: The purpose of this study was to evaluate the mechanical properties of several dual-cure cements by different curing modes. Materials and Methods: One resin-modified glass ionomer cement (FujiCEM 2), two conventional dual-cure resin cements (RelyX ARC, Multilink N), and two dual-cure self-adhesive resin cements (RelyX U200, G-CEM LinkAce) were used. To evaluate the influence of the curing methods, each cements divided into four conditions (n = 20); Condition 1: self-curing for 10 minutes, Condition 2: immediate after 20 seconds light-curing, Condition 3: 24 hours after self-curing, Condition 4: 24 hours after light-curing. The compressive strength and diametral tensile strength were measured with a universal testing machine. All data were statistically analyzed using t-test, one-way ANOVA and Scheffe's test. Results: The results showed the compressive strength and diametral tensile strength after 24 hours in all curing modes were higher than immediate except RelyX ARC light-cured and Multilink N light-cured. The FujiCEM 2 showed lowest values (P < 0.05). Conclusion: The outcome was cement-depend, but there is no significant difference about compressive strength and diametral tensile strength between dual-cure self-adhesive resin cements and conventional resin cements. And this result will be used as a base line data selecting resin cement for favorable long-term prognosis.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.4
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• pp.465-473
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• 1999

Bond strength of luting cements to dentin is a critical consideration for success of complete cast crowns. This study was performed to evaluate the relationship between surface characteristics of teeth prepared for complete cast crowns and retention of cemented restorations. Eighty artificial crowns were cast for standardized complete crown tooth preparations accomplished with the use of a special device on recently extracted human teeth. Coarse diamond(#102R, Shofu) and superfine finishing diamond(#SF102R, Shofu) burs of similar shape were used. Crowns in each group were randomly subdivided into few subgroups of 10 for luting cements selected for this study: zinc phosphate cement (FLECK' S), polycarboxylate cement (Poly-F), rein-forced glass ionomer cement (Fuji PLUS). and adhesive resin cement (Panavia 21). Retention was evaluated by measuring the tensile load required to dislodge the artificial crown from tooth preparations with an Instron testing machine, and analysed by one-way ANOVA and Student's t-test. The obtained results were as follows ; 1. When tooth preparation was done with coarse diamond bur, retentive force was diminished in order of Panavia 21 Fuji PLUS, FLECK'S, and Poly-F. Retentive forces showed the significant difference between Fuji PLUS group and FLECK'S group(p<0.001). 2. When tooth preparation was done with superfine diamond bur, retentive force was diminished in order of Fuji PLUS, Panavia 21, FLECK'S, and Poly-F. Retentive forces showed the significant difference between Panavia 21 group and FLECK'S group(p<0.001). 3. Retentive force in coarse tooth surfaces was significantly higher than that in superfine tooth surface with all luting cements(p<0.001), and cement residues were almost retained with-in the cast crown in all groups.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.1
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• pp.1-12
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• 2009

The objective of this study was to test the effects of crown material, cement type, the direction in which stress is applied and distribution of luting cement that might lead to cement microfracture using 2D Finite Element Method. Twenty three finite element models with a chamfer margin configuration were generated for a mandibular first molar. Crown models exhibited four crown materials: type 3 gold alloy, Ni-Cr alloy, ceramic and composite resin, and two luting cements: zinc phosphate and glass ionomer cements with a thicknesses of $70{\mu}m$. Modeled crowns were loaded axially or obliquely at unit load of 1 N. Areas and levels of stress concentrations within the cement were determined. Stress in the cement layer at the margins of crowns were higher than those in the area away from the margin. Stress under oblique loads were much higher than under axial load. The stiffer crown material produced higher stress and similarly, higher stress were found in cements with the greater Young's modulus.

• The Journal of the Korea Contents Association
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• v.17 no.10
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• pp.300-306
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• 2017

The purpose of this study was to investigate the antibacterial effect of functional multiwall carbon nanotube (MWCNT) on the conventional glass ionomer cement(GIC). The MWCNT was incorporated into a commercial powder at 0.125, 0.25, 0.5 and 1.0 wt%. Specimens for vickers hardness(VHN) disks(Ø$10mm{\times}2mm$) each were prepared. Indention were made using a load of 200 N and 20 s dwell on four specimens for each distilled water storage time 1d, 7d, and 14days. The antibacterial effects using agar diffusion test with S. mutans and S. aureus. The diameters of the inhibition zones produced around the materials were measured. The results revealed that all the vickers hardness values were increase significantly with incubation time(p<0.05). Regarding the antibacterial effect for S. mutans, all the tested groups showed a slightly higher value not significantly with the control group(p<0.05). However S. aureus statistical analysis indicated a significant difference for antibacterial agents between control and MWCNT containing 0.25 wt%(p<0.05). These results of this study provide that the conventional GIC with containing MWCNT show good antibacterial effect against and favorable mechanical properties. Further this study on the efficient functionalization of multiwall carbon nanotube will be needed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4819-4825
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• 2010

In all of dental ceramics, these materials contained the radio-isotopes with natural abundance ratio. After dental treatment, remained dental ceramics in the oral cavity is caused for human internal dose. In this study, the gross beta activity levels were measured in dental materials including 22 dental ceramics, 1 resin, and 2 cements for estimation of human internal dose. In dental ceramic samples, the obtained results showed that the gross beta activity level varied between 1.317 ~ 2.935 Bq/g and the gross beta activity level was 2.379 Bq/g. And the same level for dentine, opacious dentine, translucent and enamel were 2.479 Bq/g, 2.491 Bq/g, 2.470 Bq/g and 2.069 Bq/g, respectively. The gross beta activity level of temporary resin and cements were negligible, compare to the same level of dental ceramics. The high gross beta activity level observed in opacious dentine code OD-A4 is 2.935 Bq/g thus mainly ascribable to 40K. The reduction of the radiation level of natural radio-isotopes and the improvement of the dental ceramic materials should be required for internal dose reduction.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.609-621
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• 1997

The purpose of this study was to evaluate the shear bond strength of three light-cured glass ionomer cements to blood contaminated bovine dentin. The materials used in this study were Fuji II LC, Dyract and Variglass VLC. The dentin conditioners were 10% polyacrylic acid, 10% maleic acid and 10% phosphoric acid. 180 lower anterior bovine teeth were selected in this study. The teeth were embedded in acrylic resin and were grounded with 320 to 600 grit silicon carbide paper to create a flat dentin surface. The teeth were divided into SIX groups. The experimental procedures in six groups were as follows; Group l(GF) : Samples bonded to dentin surface with Fuji II LC after 10% polyacrylic acid treatment. Group 2(BGF) : Samples bonded to dentin surface with Fuji II LC after 10% polyacrylic acid treatment and blood contamination. Group 3(MD) : Samples bonded to dentin surface with Dyract after 10% maleic acid treatment. Group 4(BMD) : Samples bonded to dentin surface with Dyract after 10% maleic acid treatment and blood contamination. Group 5(PV) : Samples bonded to dentin surface with Variglass VLC after 10% phosphoric acid treatment. Group 6(BPV) : Samples bonded-to dentin surface with Variglass VLC after 10% phosphoric acid treatment and blood contamination. Group 1,3 and 5 were classified into the control groups, while group 2,4 and 6 were classified into the experimental groups. Each group contained 30 samples. After 24 hours water storage at $37^{\circ}C$, all smples were subjected to a shear load to fracture at a cross head speed of 1.0 mm/min with Instron universal testing machine(No. 4467). Debonded surfaces were observed under Scanning Electron Microscope(Hitachi S-2300) at 20kvp. The data were evaluated statistically at the 95% confidence level with Student's t-test. The following results obtained; 1. Shear bond strengths were higher in the control groups(1,3,5 group) than in the experimental groups(2,4,6 group). 2. The shear bond strength of group 5(PV) was the highest in the control groups, and the group 5 was significantly higher than the group l(GF) on the shear bond strength. 3. The group 4(BMD) was the highest on the shear bond strength, and the group 2(BGF) was the lowest in the experimental groups. The group 4(BMD) and 6(BPV) showed a significant difference with the group 2 on the shear bond strength. 4. All the groups showed an adhesive-cohesive failure. except the group 2(BGF) showing adhesive failure.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.416-425
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• 1999

The purpose of this study was to evaluate shear bond strength of glass ionomer cements and compomer according to dentin surface treatment method. The materials used in this study were dentin conditioner and cavity conditioner for dentin treatment: Ketacfil, Fuji II LC, and Dyract for restoration. In this study, 90 sound bovine teeth were selected and then the teeth were embeded in improved stone and were grounded with 400 to 600 grit silicon carbide paper to create a flat dentin surfaces. The teeth were divided into nine groups as follows ; Group 1A : Samples bonded to dentin surface with Ketacfil after no treatment Group 1B : Samples bonded to dentin surface with Ketacfil after applicating dentin conditioner Group 1C : Samples bonded to dentin surface with Ketacfil after applicating cavity conditioner Group 2A : Samples bonded to dentin surface with Fuji II LC after no treatment Group 2B : Samples bonded to dentin surface with Fuji II LC after applicating dentin conditioner Group 2C : Samples bonded to dentin surface with Fuji II LC after applicating cavity conditioner Group 3A : Samples bonded to dentin surface with Dyract after no treatment Group 3B : Samples bonded to dentin surface with Dyract after applicating dentin conditioner Group 3C : Samples bonded to dentin surface with Dyract after applicating cavity conditioner Treated dentin surfaces were observed under SEM. After filling of each materials, shear bond strenth was evaluated and then debonded surfaces were observed under SEM. The following results were obtained; 1. The shear bond strengths obtained were decreased as Fuji II LC, Dyract, Ketacfil in that order and there was statistically significant difference(p<0.05). 2. About Group 1. the shear bond strengths were decreased as 1C, 1B and 1A in that order. But there was no significant difference between group 1B and 1C (p<0.05). 3. About Group 2, the shear bond strengths were decreased as group 2B, 2A and 2C in that order. And there was significant difference between group 2B and 2C (p<0.05). 4. About Group 3, the shear bond strengths were decreased as group 3A, 3C and 3B in that order. And there was signicant difference between group 3A and 3B (p<0.05). 5. As a result of observation under SEM, the fracture patterns of Fuji II LC and Dyract were adhesive failures, but those of Ketacfil were cohesive failure of material and mixture of cohesive and adhesive failure.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.832-838
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• 1995

The purpose of this study was to evaluate the amount of marginal microleakage of 2 light curable GI cements(Fuji II LC & VariGlass), which contain some resin components. 4 volunteers kept on acrylic resin plates, which contained dentin disks with cavities filled with test materials for 2 weeks. The time when polishing was done(5 minutes and 24 hours after filling) and the use of protective agents were varied, so 8 groups with each 6 specimens were tested. After having specimens(disks with cavities filled with materials) penetrated with 1% Methylene Blue solution, specimens were stored in 40% nitric acid solution for 4 days to extract adsorbed dye material. Supernatants of centrifuged samples were diluted 5 times and Spectrophotometer was used to determine the degree of absorption. Dye concentration was calculated through the pre-obtained Linear Regression Curve. The results were as follows. 1. The best result was seen in groups (PF24, PV24) which were protected and polished 24 hours later and the opposite phenomenon was seen in groups(NF24, NV24) which were held without protection and polished 24 hours later. Groups polished S minutes later showed moderate leakage pattern. 2. Groups polished 5 minutes later showed similar leakage amount irrespective of using of protective agent. But statistically insignificant lower values were seen in VariGlass than in Fuji II LC groups, So It was considered that VariGlass may be more resistant to early moisture attack than Fuji II LC. 3. In groups polished 24 hours later, there was no significant difference between materials but was definitely significant difference according to the use of protective agent. If the cement in which polishing will be done 24 hours later, Protective agent should be used to cover the surface.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.4
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• pp.335-343
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• 2002

This study investigated the effect of temporary cement and desensitizer on the bond strength of luting cements. Total 96 dentin specimens were divided into two groups with and without temporary cementation. For temporary cement-tread group, specimens were cemented with $Temp-bond^{(R)}$ and all specimens were stored in distilled water at $37^{\circ}C$ for 7 days. Each cup was further divided into 3 subgroups with $Gluma^{(R)},\;One-step^{(R)}$ application and without desensitizer After desensitizer application, Ni-Cr specimens were luted to dentin surface with $Panavia-F^{(R)}$ and $Vitremer^{(R)}$ Specimens were placed in distilled water at $37^{\circ}C$ for 24 hours and shear bond strength between metal and dentin was measured by a universal testing machine. The results were as follows : 1. In $Panavia-F^{(R)}$ cemented groups, the combination of $One-step^{(R)}$ without temporary cement showed the greatest strength. Among the desensitizer types, $One-step^{(R)}$ showed the highest bond strength, followed by No-desensitizer, $Gluma^{(R)}$. 2. In $Vitremer^{(R)}$ cemented groups, the combination of no temporary cement and without desensitizer showed the greatest bond strength. Among the desensitizer types, No-desensitizer group showed the highest bond strength. 3. The use of $Gluma^{(R)}$ significantly reduced the shear bond strength in $Panavia-F^{(R)}$ and $Vitremer^{(R)}$ groups. 4. All temporary cement-treated groups showed a significant lower shear bond strength than without temporary cement groups. 5. Desensitizer application significantly influenced the bond strength of the resin cement and resin modified glass ionomer cement.