Earticle

Purpose: This study was to evaluate the shear bond strength of the ceramic fused to Ni-Cr alloy(Bellabond plus) and Co-Cr alloy(Wirobond C) by heat treatment. Methods: Metal specimens were divided into 5 groups for each alloy according to heat treatment conditions prior to porcelain application. Fifteen specimens from each group were subjected to a shear load a universal testing machine using a 0.1㎜/min cross-head speed and one specimen from each group was observed with EDX line profile. Results: The diffusion of metal oxide observed far in the specimen heat treated than no heat treated in the opaque layer. The shear bond strength measured highest to BP3(50.50㎫), WC2(50.49㎫) groups and measured lowest from BP1(35.19㎫a), WC1(39.66㎫) groups which were not treated with heat, and there was a significant difference (p<0.05). Conclusion: The shear bond strength of Ni-Cr alloy(Bellabond plus) and Co-Cr alloy(Wirobond C) measured similar 5 groups all.

the bond strength and flexural strength of ceramic veneered zirconia. Methods: 3Y-TZP specimens(KaVo Zr, 25㎜×3㎜×1㎜)were prepared by five pre-treatment methods and divided into seven groups including control two groups, subsequently the specimens veneered with the E-MAX ceram according to manufacturer’s information(total specimen thickness 1.5㎜). Two groups from ceramic-zirconia specimens(n=105, n=15 per group)were assigned into two experimental fatigue conditions, namely storage in an autoclave at 134℃ for 5h, thermo-cycling(3,000cycles, between 5 and 55℃, dwell time 45s, transfer time 2s). A flexural strength test was performed in a universal testing machine(crosshead speed: 0.5㎜/min). Data were statistically analyzed using one-way ANOVA and Tukey’s test(α=0.05). Results: The ceramic-zirconia bond strength value for liner application group(LLW, 27.3±3.8) were significantly lower than those of the pre-treatment groups(30.72±5.3). The ceramic-zirconia bond strength and zirconia flexural strength was not affected by thermo-cycling(p>0.05), whereas it was affected by storage in an autoclave at 134℃ for 5h(p<0.05). Conclusion: The results indicated that the ceramic-zirconia bond strength and zirconia flexural strength was affected by low temperature degradation.

Purpose: The purpose of this study was to compare color correspondence of different sizes of Vita Mark Ⅱ􄠶 and TriLuxe􄠶 Feldspar blocks. Methods: The three commercially available shades(1M2, 2M2, 3M2) of Mark Ⅱ& TriLuxe blocks for the CEREC􄠶 CAD/CAM system were examined. For each of three colors, three different sizes were tested, 5 blocks each. The measurements were made using a spectrophotometer equipped with an integrating sphere using the CIE L*, a*, b* colorimetric system. Results: The L*, a*, b* value of Vita Mark Ⅱ􄠶 ceramic block showed significantly higher than TriLuxe􄠶 ceramic block(p<0.05). In comparing the Vita Mark Ⅱ􄠶 specimen of the three different shade, color differences between materials(ΔE*) showed the lowest value of 2.09, and the highest was 2.24. ΔE* values of the materials of Vita Mark Ⅱ􄠶 were higher than 2. As the size of ceramic block differed, the color correspondence of Vita Mark Ⅱ􄠶 showed statistically significant difference but, this result is clinically acceptable. Conclusion: All the different sizes of the different shades of Vita TriLuxe􄠶 blocks for the CEREC􄠶 system showed the high degree of color correspondence necessary in industrially prefabricated CAD/CAM blocks. The results of the present study suggested that it would be necessary to establish the reproducible and constant color specification system for an esthetic restoration.

Purpose: The purpose of the study was a quantitative evaluation of common errors in digital impression procedure using CEREC􄠶 AC system. Methods: Two-hundreds digital impression data comprising 174 inlays, 26 onlays by CEREC􄠶 AC in-office CAD/CAM system were obtained from a dental clinic. One evaluator assessed errors of the digital impression data and divided into five categories of errors: inappropriate scanner positioning (ISP), improper handling with a scanner (IHS), irregular powder arrangement (IPA), improper cavity preparation (ICP), and insufficient scanned data (ISD). Results: The most common errors were IPA(21%), and ISP and ISD were followed by 17% respectively. IHS was found in 14.5% of all digital impression data. ICP comprising only 6.5% was the rarest. Conclusion: Most errors were due to inaccurate manipulation with an intraoral scanner or improper cavity preparation for scanning. A deliberate manipulation to prevent common errors mentioned may deliver an optimal result in the digital impression procedure.

Purpose: The current study focused on investigating color change of dental zirconia block with respect to the block coloring time. Methods: Three types of dental zirconia blocks(Zirtooth, Pearl-HT, D-Max) were tinted with coloring agent under four different time condition (0 minutes, 1 minutes, 10 minutes, 30 minutes). The quantitative evaluation of the tinted dental zirconia blocks was conducted with spectrophotometer. Results: The Zirtooth and D-Max blocks showed lower H value. The Pearl-HT blocks showed poor reflectivity(L value). Conclusion: The study of color change of zirconia block, which consists the substructure of all ceramic Crown, is applicable for deciding appropriate coloring condition when fabricating one layer ceramic Crown or double layer ceramic Crown.

Purpose: The purpose of this study was to reduce the remake rate of dental prosthesis. We examined remake cause and major factor of dental prosthesis to determine methods for raising dental prosthesis satisfaction. Methods: Subjects included dental technicians in the metropolitan areas of the cities of Daegu and Gyeong-buk. Surveys were filled out by consenting dental technicians. Statistical analysis was done using SPSS version 19.0 for Windows. We determined frequencies and percentage, calculating means, and standard deviations, and determining statistical significance using t-tests, analysis of variance. Results: Impression or material transform is high among remake cause and margin is high among remake major factor. Crown class showed differences in General characteristics associated with age, number of employees, and number of connection dental. Porcelain class showed differences in General characteristics associated with age, number of employees, and number of connection dental. Denture class showed differences in General characteristics associated with age, monthly salaray, and career. Implant class showed differences in General characteristics associated with age, education, and career. Conclusion: In order to reduce remake rate of dental prosthesis, communication of dentist, dental technician, and the patient are require and correct information of patient and dental prosthesis are need.

Purpose: This study investigates dental health and chewing ability of patients hospitalized in geriatric hospital, and compares the chewing ability for each factor that can be used as data for dental healthcare of senior citizens and basic data for denture insurance for the elderly. Methods: The 101 subjects of this study were selected from 178 patients hospitalized in a geriatric hospital located in Daegu Metropolitan City, excluding 77 patients who were being treated in the intensive care unit and who were unable to communicate. The chewing ability of the patients were measured using an evaluation scale based on foods consisting of 10 different hardnesses. Results: Patients with less than 21 teeth, those with dentures and patients who were less than satisfied with their dental conditions had difficulties in chewing hard food such as dried squid and radish kimchi, and the Chewing ability increased proportionally to the number of remaining teeth(p<0.001), appropriateness of the maxillary and mandibular dentures(p<0.005) and the level of dental satisfaction(p<0.001). Conclusion: This study is limited as the subjects were selected from a single hospital and the authors estimate that various studies will be necessary to investigate the Chewing ability of patients hospitalized in long-term hospitals. The subjects of this study did not receive any dental treatment while staying in the hospital and many of the subjects had bad fit denture or didn’t have dentures or did not use dentures, although they have dentures, which calls for denture construction and prosthetics through dental treatment.

Purpose: The purpose of this survey research was to investigate the Perception level of CAD/CAM of dental techique. Methods: This survey was carried out in the metropolitan areas of the cities of Daegu and Gyeong-buk. Surveys were filled out by consenting dental technicians. Statistical analysis was done using the Statistical Package for Social Sciences (SPSS) version 17.0 for Windows. As for the analysis methods, the study used the frequency analysis, Ttest, F-test. Results: Perception of CAD/CAM showed differences in General characteristics associated with education level, monthly salary. Perception of CAD/CAM showed differences in professional characteristics associated with working area, working part. Perception of CAD/CAM showed differences in understanding of CAD/CAM associated with CAD/CAM operating experience, CAD/CAM educational experience. Conclusion: In order to improve the Perception level of CAD/CAM of dental technician, A variety education and follow-up research is need.