No abstract available.
Dental Porcelain*

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 Alloys* ; Dental Porcelain*

No abstract available.
Dental Enamel* ; 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

To compare several porcelains made by various manufacturers in shrinkage after firing and investigate the effect of condensation on shrinkage, specimens were prepared and the volume of each body was measured by the phase-shifting profilometry. Baseplate wax was cut by 2.5cmx2cm and cast in nonprecious metal (Verabond, U.S.A.). then any surfaces of specimens were abrased and polished on the SiC abrasing papers, preparing 120 specimens. specimens were divided into six groups according to the porcelain used, and the porcelain used in each group were as follows. Group I : Ceramco dentin porcelain Group II : Creation dentin porcelain Group III : Creation margin porcelain Group IV : Vintage margin porcelain Group V : Vita dentin porcelain Group VI : Vintage dentin porcelain Porcelain was built up on the metal plates using a small spoon and then solution matching to each porcelain was added. The six groups are subdivided into a and b. In subgroup a, only excessive solution was absorbed with tissue and in subgroup b, porcelain was condensed sufficiently. When build-up was completed, the shape was measured using the phase-shifting profilometry. After that, specimens were fired in the furnace programed for each porcelain and then their changed shape were measured again. Using the difference between the two above measurements, the ratio of shrinkage was calculated. Obtained results were as follows ; 1. Regardless of condensation, the volume of fired specimens were not different significantly between the two subgroups a and b in the same group. 2. The ratios of shrinkage were significantly higher in the groups porcelain built-up was condensed than in the groups not condensed. 3. The ratios of shrinkage were in the range of 36.81-27.19% in the groups porcelain built up was condensed and 44.52-37.54% in the other groups not condensed.
Dental Porcelain* ; Dentin ; Fires*

The purpose of this study is to evaluate the color differences that can exist between differnet brands of dentin porcelain having identical shade designations. The instrumental colorimetric technique was used to determine these differences. The three brands of dentin porcelain used were Vita VMK-68, Shofu Vintage, and Ceramco II. The three shades selected were the Vita Lumin shades A2, B2, and C2. The color difference values were compared with each other using L*, a*, b*, three variables of the CIELAB color system, and E. The results of this study were as follows: 1. Corresponding shades of different brands of dentin porcelain produced different L*, a*, b* values. 2. The greatest E value in corresponding shade was found to exist between Ceramco II and Shofu Vintage, followed by between Vita VMK-68 and Ceramco II, and then between Vita VMK-68 and Shofu Vintage. 3. The E values in shade C2 were mainly influenced by L* value ; however none of L*, a*, b* values had greater influence on E values than the others in shade A2, B2. 4. Shofu Vintage had the highest b* value, followed by Vita VMK-68, and then Ceramco II.
Dental Porcelain* ; Dentin*

Dental Porcelain ; Zirconium

No abstract available.
Dental Porcelain* ; Resin Cements*