• Journal of Technologic Dentistry
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• v.39 no.2
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• pp.83-91
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• 2017

Purpose: The objective of this study was to evaluate influence of mechanical properties of gingival shade composite resins(GSCRs) according to thermocycling treatment. Methods: The material utilized in this study was Crea.lign(CGR), Twiny flow(TGF) and Twiny(TGP). Total sixty specimens were fabricated with a dimension of $25{\times}2{\times}2mm$ according to the ISO 4049. After fabrications, specimens of before and after thermocycling(to $55^{\circ}C$ from $5^{\circ}C$) were stored in the distilled water for 24 hours at the $37^{\circ}C$. Three-point flexural test was performed in universal testing machine(Instron 5966, USA) at a crosshead speed of 1 mm/min. Flexural strength, flexural modulus and work of fracture according to the thermocycling were analyzed using a one-way ANOVA analysis. Surface analysis of GSCRs after thermocycling evaluated using the scanning electron microscope. Results: : The highest FS was measured in TGP group of NTC group and lowest in CGR group after TC. After TC, FS and FM decreased in CGR and TGP groups, but TGF increased. There was a statistically significant difference between FS and WOF in GSCRs(p<0.05). But FM did not show any significant difference after TC (p>0.05). The strength of the characteristic exceeded the flexural strength required by ISO 4049(> 80 MPa). Weibull modulus(m) showed the highest reliability in the TGP group (m = 14.22), and the reliability of the TGF and TGP groups after TC decreased. Conclusion: Thermocycling treatment is important factor influence of mechanical properties with gingival shade composite resins. Therefore, we recommended that mechanical properties need to get useful information and accuracy for life-span expectancy according to the thermocycling treatment.

• Journal of the Korean Society for Heat Treatment
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• v.9 no.3
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• pp.187-197
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• 1996

In this study, the properties of coil spring made by Cu-Zn-Al and B added shape memory alloys are investigated. The measurement of recovery displacement and energy with increasing weight, and thermocycling properties have been studied using displacement measuring device. Transformation temperature and phase change by thermocycling have been also investigated by DSC and X-ray diffractometer. Grain size of the alloy is refined from 1.2mm to $400{\mu}m$ by 0.06wt% of B addition. The maximum recovery energy of the coil spring for B added alloy is larger than that of no B added alloy, it is because of grain refinement. And shape memory ability of the coil spring by thermocycling decrease with increasing thermocycling after thermocycle under load. The degradation of shape memory properties of coil spring by thermocycling is improved by B addition.

• The Journal of Advanced Prosthodontics
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• v.7 no.1
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• pp.1-7
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• 2015

PURPOSE. This study was performed to evaluate shear bond strength (SBS) between three dual-cured resin cements and silica coated zirconia, before and after thermocycling treatment. MATERIALS AND METHODS. Sixty specimens were cut in $15{\times}2.75mm$ discs using zirconia. After air blasting of $50{\mu}m$ alumina, samples were prepared by tribochemical silica coating with $Rocatec^{TM}$ plus. The specimens were divided into three groups according to the dual-cure resin cement used: (1) Calibra silane+$Calibra^{(R)}$, (2) Monobond S+$Multilink^{(R)}$ N and (3) ESPN sil+$RelyX^{TM}$ Unicem Clicker. After the resin cement was bonded to the zirconia using a Teflon mold, photopolymerization was carried out. Only 10 specimens in each group were thermocycled 6,000 times. Depending on thermocycling treatment, each group was divided into two subgroups (n=10) and SBS was measured by applying force at the speed of 1 mm/min using a universal testing machine. To find out the differences in SBS according to the types of cements and thermocycling using the SPSS, two-way ANOVA was conducted and post-hoc analysis was performed by Turkey's test. RESULTS. In non-thermal aged groups, SBS of Multilink group (M1) was higher than that of Calibra (C1) and Unicem (U1) group (P<.05). Moreover, even after thermocycling treatment, SBS of Multilink group (M2) was higher than the other groups (C2 and U2). All three cements showed lower SBS after the thermocycling than before the treatments. But Multilink and Unicem had a significant difference (P<.05). CONCLUSION. In this experiment, Multilink showed the highest SBS before and after thermocycling. Also, bond strengths of all three cements decreased after thermocycling.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.2
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• pp.255-263
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• 2000

The purpose of this study was to compare the microleakage of the composite resin cores according to surface treatment, dentin bonding agents, and thermocycling. For this study, 120 extracted premolar teeth were used. Flat occlusal surfaces were prepared with diamond disk, and treated with air-abrasion, acid-etching, combination. The composite resin core was built with Z-100 after application of Scotchbond Multi-Purpose and All-Bond 2. Prepared specimens were thermocycled for 2,000 cycles. Specimens were immersed in 1% methylene blue solution for 24hours at $37^{\circ}C$. The microleakage was measured with a inverted metallurgical microscope(BHS313, Olympus, Japan). The following conclusions were drawn from this study: 1. The microleakages in the groups treated with air-abrasion and with acid etching were greater than that of the groups treated with combination method before thermocycling(p<0.05), the microleakages of the groups treated with air-abrasion were greater than that of the groups treated with acid-etching and combination method after thermocycling(p<0.05) 2. There were no significant difference between groups using Scotchbond Multi-Purpose and the groups using All-Bond 2. 3. Thermocycling didn't affect the change of microleakage in all cases.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.2
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• pp.265-276
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• 1997

The effect of thermocycling and surface finishing on the marginal fidelity of copings for a metal ceramic crown was examined. Methods for minimizing the loss of marginal fidelity were evaluated. The results were as follows ; 1. Thermocycling of ceramic metal copings resulted in increased marginal gap. 2. The greatest marginal gap occurred during the first thermocycling of the copings. 3. No additional distortion of marginal fidelity occurred when surface finishing and second thermocycling were completed after initial thermocycling. 4. The gap increases according to various treatment methods showed group 1 to be the highest values. 5. There was no significant difference between group 2 and group 3(p>0.05) 6. There was significant difference between group 1 and group 2, 3(p<0.05). 7. There was no significant difference among the measurement sites.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.1
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• pp.255-264
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• 1991

The purpose of this study was to evaluate the effect of the shear bond strength between porcelain laminate veneer and enamel according to the surface treatment and thermocycling. Group I, as a control group, was sandblasted only; group II was sandblasted and etched; group III was sandblasted and silane treated; and group IV was sandblasted, etched and silane treated. A porcelain block was placed onto the etched enamel under a 150g static load and the bonded site was light-cured from 4 directions for 1 minute each. The 72 bonded specimens were stored in water at $37^{\circ}C$ for 1 day. Half of each group were thermocycled at $4^{\circ}C$ and $60^{\circ}C$ for 100 cycles with a dwelling time in each bath of 1 min. Following thermocycling, the specimens were installed in an Instron universal testing machine and the shear bond strength was measured. After the specimens were fractured, the fractured surfaces were examined with SEM. The obtained results were as follows : 1. The shear bond strength of the sandblasted and etched and silane treated group(Group IV) was the strongest of all, and the shear bond strengths between the sandblasted group(Group I) and the sandblasted and silane treated group(Group III) were not statistically different(p>0.05). 2. When the shear bond strength was measured after thermocycling, only the sandblasted, etched and silane treated group(Group IV) was statistically different(p<0.05). 3. The scanning electron microscopic views of the fractured surfaces show more irregularities and more resin fragments in the etched group than in the unetched group. 4. The scanning electron microscopic views of the fractured surfaces show a more delicate surface after thermocycling and after silane treatment than before thermocycling and before silane treatment.

• The Journal of Advanced Prosthodontics
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• v.8 no.4
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• pp.259-266
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• 2016

PURPOSE. The purpose of this study was to assess the effect of surface treatments on shear bond strength of resin composite bonded to thermocycled and non-thermocycled CAD/CAM resin-ceramic hybrid materials. MATERIALS AND METHODS. 120 specimens ($10{\times}10{\times}2mm$) from each material were divided into 12 groups according to different surface treatments in combination with thermal aging procedures. Surface treatment methods were airborne-particle abrasion (abraded with 50 micron alumina particles), dry grinding (grinded with $125{\mu}m$ grain size bur), and hydrofluoric acid (9%) and silane application. According to the thermocycling procedure, the groups were assigned as non-thermocycled, thermocycled after packing composites, and thermocycled before packing composites. The average surface roughness of the non-thermocycled specimens were measured after surface treatments. After packing composites and thermocycling procedures, shear bond strength (SBS) of the specimens were tested. The results of surface roughness were statistically analyzed by 2-way Analysis of Variance (ANOVA), and SBS results were statistically analyzed by 3-way ANOVA. RESULTS. Surface roughness of GC were significantly lower than that of LU and VE (P<.05). The highest surface roughness was observed for dry grinding group, followed by airborne particle abraded group (P<.05). Comparing the materials within the same surface treatment method revealed that untreated surfaces generally showed lower SBS values. The values of untreated LU specimens showed significantly different SBS values compared to those of other surface treatment groups (P<.05). CONCLUSION. SBS was affected by surface treatments. Thermocycling did not have any effect on the SBS of the materials except acid and silane applied GC specimens, which were subjected to thermocycling before packing of the composite resin.

• The korean journal of orthodontics
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• v.45 no.4
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• pp.164-170
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• 2015

Objective: The aim of this study was to compare the shear bond strength (SBS) of orthodontic brackets bonded to zirconia surfaces using three different zirconia primers and one silane primer, and subjected to thermocycling. Methods: We designed 10 experimental groups following the surface treatment and thermocycling. The surface was treated with one of the following method: no-primer (NP), Porcelain Conditioner (PC), Z-PRIME Plus (ZP), Monobond Plus (MP) and Zirconia Liner Premium (ZL) (n=20). Then each group was subdivided to non-thermocycled and thermocycled groups (NPT, PC, ZPT, MPT, ZLT) (n=10). Orthodontic brackets were bonded to the specimens using $Transbond^{TM}$ XT Paste and light cured for 15 s at $1,100mW/cm^2$. The SBS was measured at a 1 mm/min crosshead speed. The failure mode was assessed by examination with a stereomicroscope and the amount of bonding resin remaining on the zirconia surface was scored using the modified adhesive remnant index (ARI). Results: The SBS of all experimental groups decreased after thermocycling. Before thermocycling, the SBS was ZL, $ZP{\geq}MP{\geq}PC>NP$ but after thermocycling, the SBS was $ZLT{\geq}MPT{\geq}ZPT>PCT=NPT$ (p > 0.05). For the ARI score, both of the groups lacking primer (NP and NPT) displayed adhesive failure modes, but the groups with zirconia primers (ZP, ZPT, MP, MPT, ZL, and ZLT) were associated with mixed failure modes. Conclusions: Surface treatment with a zirconia primer increases the SBS relative to no-primer or silane primer application between orthodontic brackets and zirconia prostheses.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.4
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• pp.354-363
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• 2016

Purpose: The aim of this study was to investigate whether the application of nano-structured alumina coating to the surface of Y-TZP could enhance the bond strength with resin cement. Materials and methods: A total of 80 zirconia plates were prepared and divided into four groups. : 1) airborne particle abrasion treatment (A) : 2) Rocatec treatment after airborne particle abrasion (R) : 3) nano-structured alumina coating treatment after polishing (PC) and 4) nano-structured alumina coating after airborne particle abrasion (AC). Alumina coating was formed by the hydrolysis of aluminium nitride (AlN) powder and heat treatment at $900^{\circ}C$. Coating patterns were observed with FE-SEM. Resin block was bonded to treated zirconia ceramics using resin cement. The shear bond strengths were measured before and after thermocycling. Results: The FE-SEM images show a dense and uniform nano-structured alumina coating structure, which enhances shear bond strength by increasing micro mechanical interlocking to resin cement. PC and AC groups showed higher shear bond strengths than A and R groups before and after thermocycling. A and R groups displayed significant drops in shear bond strength after thermocycling. However, PC and AC groups did not show any meaningful decreases in shear bond strength after thermocycling. Conclusion: Treatment of Y-TZP ceramics with nano-structured alumina coating could significantly increase their shear bond strength.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.1
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• pp.73-84
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• 2000

Dental porcelain should have adequate strength and similar esthetics as natural teeth. Recently esthetics has become a high priority in clinical dentistry. Thus the evaluation of color stability of dental porcelain has become an important part in dental research. The purpose of this study was to evaluate the difference in color stability of 3 types of porcelain(Vintage, VMK 95, CERAMCO II). The porcelain were divided into groups by 2 types of treatment(glazing or non-glazing and thermocycling or non-thermocycling). The porcelain were dyed with methylene blue and distilled water, and then the color stability was evaluated with a spectrophotometer The results were as follows; 1. The color change of porcelain increased in the order of VMK 95, Vintage, CERAMCO II. But there was no significant difference. 2. The color change decreased in the glazing group compared to the non-glazing group(p<0.05). 3. The color change increased after thermocycling But there was no significant difference. 4. The color change according to dye method was significantly larger with methylene blue copared to distilled water(p<0.05).