This study was designed to compare the smoothness by glazing method with that by polishing method after 48 specimens of Ceramco II block, one of porcelain materials used for PFM, were baked according to the manufacturer's directions. The specimens were roughened with new green stone at 15,000rpm for 30 seconds and sandblasted with 25microliteraluminum oxide for 15 seconds. They were divided into 4 groups at random, and 4 groups were prepared as follows : Group I : specimens were autoglazed and overpolished with polishing system. Group II specimens were polished with only polishing system. Group IIIspecimens were glazed after adding glazing liquid, vitachrom "L"-fluid (vita zahnfabrik co. Germany) to the rough surface Group v : specimens were just autoglazed Using the surface roughness tester, Ra, Rmax, and Rz were estimated 5 times per specimen, and recording process of mean value was repeated 3 times. The results were as follows : 1. The Ra of group I and group IIwas lower than group IIIand group IV (p<001). 2. There was lower value of Rz in group I and group II than group III and group IV (p<001). 3. The Rmax of group I(overpolished with polishing system after autoglazing) and group II(polished with only polishing system) was lower than group III(glazed after adding glazing liquid) and group IV (autoglazed) (p<001). 4. There was not a statistically significant difference between group I and II and between group III and IV (p>001). 5. The roughness was increase in order of group I,II,III,IV in SEM
Dental Porcelain*

The purpose, of this study was to evaluate the effect of surface treatment of porcelain on tensile bond strength. To accomplish this purpose, this study was carried out with 120 samples which were divided into 12 groups with each 10 samples, and the first group was not surface treated, groups 2 through 5 underwent single surface treatment, and groups 6 through 12 underwent compound surface treatment. The results were as follows: 1. In statistic, all the single surface-treated groups showed higher tensile bond strength than the non surface-treated group and the sandblasted group showed the highest tensile bond strength as 10.34+/-2.50MPa. 2. All the compound surface-treated groups showed no noticeable difference in the tensile bond strength(9-11.5MPa). 3. In statistic, no significant difference was found between the sandblasted group and the compound surface-treated groups. 4. There was no fracture of porcelain while testing in this study. Above study demonstrated that compound surface treatment or sandblasing, if used single surface treatment, should be employed to guarantee successful clinical application.
Dental Porcelain*

No abstract available.
Dental Porcelain*

The purpose of this study is to develope new dental color-space system. Twelve kinds of dental composites and one kind of dental porcelain were used in this study. Disk samples (15 mm in diameter, 4 mm in thickness) of used materials were made and sample's CIE L*a*b* value was measured by Spectrocolorimeter (MiniScan XE plus, Model 4000S, diffuse/8degrees viewing mode, 14.3 mm Port diameters, Hunter Lab. USA). The range of measured color distribution was analyzed. All the data were applied in the form of T### which is expression unit in CNU Cons Dental Color Chart. The value of L* lies between 80.40 and 52.70. The value of a* are between 10.60 and 3.60 and b* are between 28.40 and 2.21. The average value of L* is 67.40, and median value is 67.30. The value of a* are 2.89 and 2.91 respectively. And for the b*, 14.30 and 13.90 were obtained. The data were converted to T### that is the unit count system in CNU-Cons Dental Color Chart. The value of L* is converted in the first digit of the numbering system. Each unit is 2.0 measured values. The second digit is the value of a* and is converted new number by 1.0 measured value. For the third digit b* is replaced and it is 2.0 measured unit apart. T555 was set to the value of L* ranging from 66.0 to 68.0, value of a* ranging from 3 to 4 and b* value ranging from 14 to 16.
Dental Materials* ; Dental Porcelain

No abstract available.
Dental Alloys* ; Dental Porcelain*

No abstract available.
Dental Enamel* ; Dental Porcelain*

PURPOSE: This study aimed to evaluate the fit of zirconia ceramics before and after veneering, using 3 different veneering processes (layering, press-over, and CAD-on techniques). MATERIALS AND METHODS: Thirty standardized zirconia CAD/CAM frameworks were constructed and divided into three groups of 10 each. The first group was veneered using the traditional layering technique. Press-over and CAD-on techniques were used to veneer second and third groups. The marginal gap of specimens was measured before and after veneering process at 18 sites on the master die using a digital microscope. Paired t-test was used to evaluate mean marginal gap changes. One-way ANOVA and post hoc tests were also employed for comparison among 3 groups (alpha=.05). RESULTS: Marginal gap of 3 groups was increased after porcelain veneering. The mean marginal gap values after veneering in the layering group (63.06 microm) was higher than press-over (50.64 microm) and CAD-on (51.50 microm) veneered groups (P<.001). CONCLUSION: Three veneering methods altered the marginal fit of zirconia copings. Conventional layering technique increased the marginal gap of zirconia framework more than pressing and CAD-on techniques. All ceramic crowns made through three different veneering methods revealed clinically acceptable marginal fit.
Ceramics ; Crowns ; Dental Porcelain

No abstract available.
Alloys* ; Dental Porcelain*

STATEMENT OF PROBLEMS: Long-term success of esthetic restorations, depends on various factors, especially on color stability of the restorations. The color stability is affected by resin cements beneath the porcelain laminate veneers. PURPOSE: The purpose of this study was to comprehend the color stability of resin cements by comparing with 4 different kinds of resin cements (Choice, Variolink II, Nexus 2, Rely-X). MATERIAL AND METHODS: Porcelain laminate disk samples were luted with resin cements. After thermocycling of each 1000, 2000 and 3000 cycle, specimens were measured by spectrophotometers and the color differences were. RESULTS: 1. After thermocycling of 1000, 2000 and 3000cycle, color difference, (deltaE*) of all specimens were incresed, but were not statiscally significant differences. 2. In the Choice of A1 shade and the Nexus 2 of A3 shade, color difference(deltaE*) after thermocycling of 3000cycle was incre*ased significantly than after thermocycling of 1000cycle. However, other groups did not show any statistically significant differences (P<0.05). 3. After thermocycling of 3000cycle, color difference(deltaE*) between A1 shade and A3 shade of Nexus 2 showed statistically significant difference. However no statistically significant differences were observed in other groups (P<0.05). 4. The mean of color difference(deltaE*) is 1.0-2.06 after 3000 thermocycling and the data were ranked in the ascending order of Variolink II, Nexus 2, Choice and Rely-X in A1 shade group and Choice, Rely-X, Variolink II and Nexus 2 in A3 shade group. CONCLUSION: Above results revealed that, after 3000thermocycing, the color difference (deltaE*) of experimental resin cements was within clinically acceptable ranges. Color stability of 4 different resin cements was comparatively excellent.
Dental Porcelain* ; Resin Cements*

STATEMENT OF PROBLEM: Titanium has many advantages of high biocompatibility, physical properties, low-weight, low price and radiolucency, but it is incompatible with conventional dental porcelain due to titanium's oxidative nature. Many previous studies have shown that they used the method of sandblast for surface treatment prior to porcelain application, the researches are processing about the method of acid etching or surface coating. PURPOSE: The purpose of this research is to study the effect on bond strength of surface roughness between titanium and porcelain with the same surface topography. MATERIAL AND METHOD: In this study, we evaluated the bond strength by using 3-point bending test based on ISO 9693 after classified 8 groups - group P : polished with #1200 grit SiC paper, group S10 : 1.0 micrometer surface roughness with sandblasting, group S15 : 1.5 micrometer surface roughness with sandblasting, group S20 : 2.0 micrometer surface roughness with sandblasting, group S25 : 2.5 micrometer surface roughness with sandblasting, group S30 : 3.0 micrometer surface roughness with sandblasting, group S35 : 3.5 micrometer surface roughness with sandblasting, group E : 1.0 micrometer surface roughness with HCl etching. RESULTS: Within the confines of our research, the following results can be deduced. 1. In the results of 3-point bending test, the bond strength of sandblasting group showed significant differences from one of polishing group, acid etching group(P<.05). 2. The bond strength of sandblasting groups did not show significant differences. 3. After surface treatments, the group treated with sandblasting showed irregular aspect formed many undercuts, in the SEM photographs. The bond strength of sandblasting group was higher than 25 MPa, the requirement of ISO 9693. CONCLUSION: In above results, bond strength of titanium and low-fusing porcelain is influenced more to surface aspect than surface roughness. And titanium has clinically acceptable bond strength below surface roughness of 3.5 micrometer.
Dental Porcelain ; Titanium