1.The fracture resistance of ceramometal crown with various coping design.
Wan Mo CHUNG ; Jin Keun DONG ; Tai Ho JIN
The Journal of Korean Academy of Prosthodontics 1992;30(1):125-132
No abstract available.
Crowns*
2.A study on fracture strength and color by the design of metal coping in ceramo metal crown.
Myung Ho LEE ; Young Chan JEON
The Journal of Korean Academy of Prosthodontics 1992;30(1):103-124
No abstract available.
Crowns*
3.The effects of surface treatment of fractured metal-ceramic crown on bond strength of repair resin.
The Journal of Korean Academy of Prosthodontics 1991;29(2):117-127
No abstract available.
Crowns*
4.The marginal accuracy of temporary crown with different matrix.
Tae Hun JU ; Hye Won CHO ; Jin Keun DONG
The Journal of Korean Academy of Prosthodontics 1991;29(2):59-66
No abstract available.
Crowns*
5.Axial wall thickness of zirconia abutment in anterior region.
Seung Jin MOON ; Yu Ri HEO ; Gyeong Je LEE ; Hee Jung KIM
The Journal of Korean Academy of Prosthodontics 2015;53(4):345-351
PURPOSE: The purpose of this study was to evaluate the proper axial thickness of zirconia abutment applied to implant in the anterior region. MATERIALS AND METHODS: Zirconia abutments were prepared at different axial wall thickness by processing pre-sintered zirconia blocks via CAD/CAM to obtain equal specimens. The abutments were each produced with a thickness of 0.5 mm (Group 1), 0.8 mm (Group 2), 1.2 mm (Group 3), or 1.5 mm (Group 4). The implant used in this study was a external connection type one (US, Osstem, Pussan, Korea) product and the zirconia abutment was prepared via replication of a cemented abutment. The crowns were prepared via CAM/CAM with a thickness of 1.5 mm and were cemented to the abutments using RelyX(TM) UniCem cement. A universal testing machine was used to apply load at 30 degrees and measure fracture strength of the zirconia abutment. RESULTS: Fracture strength of the abutments for Group 1, Group 2, Group 3, and Group 4 were 236.00 +/- 67.55 N, 599.00 +/- 15.80 N, 588.20 +/- 33.18 N, and 97.83 +/- 98.13 N, respectively. Group 1 showed a significantly lower value, as compared to the other groups (independent Mann-Whitney U-test. P<.05). No significant differences were detected among Group 2, Group 3, and Group 4 (independent Mann-Whitney U-test. P>.05). CONCLUSION: Zirconia abutment requires optimal thickness for fracture resistance. Within the limitation of this study, > 0.8 mm thickness is recommended for zirconia abutment in anterior implants.
Crowns
6.Accuracy of provisional crowns made using stereolithography apparatus and subtractive technique
Seen Young KANG ; Jung Hyun PARK ; Ji Hwan KIM ; Woong Chul KIM
The Journal of Advanced Prosthodontics 2018;10(5):354-360
PURPOSE: To compare and analyze trueness and precision of provisional crowns made using stereolithography apparatus and subtractive technology. MATERIALS AND METHODS: Digital impressions were made using a master model and an intraoral scanner and the crowns were designed with CAD software; in total, 22 crowns were produced. After superimposing CAD design data and scan data using a 3D program, quantitative and qualitative data were obtained for analysis of trueness and precision. Statistical analysis was performed using normality test combined with Levene test for equal variance analysis and independent sample t-test. Type 1 error was set at 0.05. RESULTS: Trueness for the outer and inner surfaces of the SLA crown (SLAC) were 49.6±9.3 µm and 22.5±5.1 µm, respectively, and those of the subtractive crown (SUBC) were 31.8±7.5 µm and 14.6±1.2 µm, respectively. Precision values for the outer and inner surfaces of the SLAC were 18.7±6.2 µm and 26.9±8.5 µm, and those of the SUBC were 25.4±3.1 µm and 13.8±0.6 µm, respectively. Trueness values for the outer and inner surfaces of the SLAC and SUBC showed statistically significant differences (P < .001). Precision for the inner surface showed significance (P < .03), whereas that for the outer surface showed no significance (P < .58). CONCLUSION: The study demonstrates that provisional crowns produced by subtractive technology are superior to crowns fabricated by stereolithography in terms of accuracy.
Crowns
7.A STUDY ON MARGINAL FIDELITY OF CERAMIC METAL COPINGS TREATED BY VARIOUS METHODS.
Bum Mo KOO ; Ju Hwan LIM ; In Ho CHO
The Journal of Korean Academy of Prosthodontics 1997;35(2):265-276
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 coping 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 gab 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.
Ceramics*
;
Crowns
8.A STUDY ON MARGINAL FIDELITY OF CERAMIC METAL COPINGS TREATED BY VARIOUS METHODS.
Bum Mo KOO ; Ju Hwan LIM ; In Ho CHO
The Journal of Korean Academy of Prosthodontics 1997;35(2):265-276
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 coping 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 gab 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.
Ceramics*
;
Crowns
10.Three-dimensional evaluation of the machinability of monolithic CAD/CAM-generated posterior crowns by nano-hybrid ceramic
Korean Journal of Dental Materials 2019;46(2):89-98
The purpose of this study comparatively analyzed the machinability of various dental hybrid blocks manufactured by using the CAD/CAM system. Three hybrid composite blocks (Vita enamic, Lava Ultimate, GC Cerasmart) were used for experimental groups and one conventional ceramic block (Vita Mark II) was used for control. The digital impression of the master model and abutment was taken by using a scanner, and then the CAD software program was used to design restorations. The four-axis milling machine (inLab MCXL; Sirona Dental Systems GmbH, Bensheim, Germany) was used four materials. The digitized data was superimposed with 3D inspection software to quantitatively obtain the machinability of a ceramic crown, and visual differences were confirmed with a color map. The root mean square (RMS) values of ceramic crown group were statistically analyzed with one-way ANOVA (α=0.05). While there was a significant difference in the machinability of the internal surface, among four groups, there was statistically significant difference between conventional (VM group) and hybrid ceramic (VE, LU, GC groups) (p<0.05). Consequently, the machinability of VM is lower than that of other hybrid ceramics, and the machinability of VE is better than that of LU and GC. For ceramics as final restorations, manufacturing of dental restorations using hybrid composite ceramic is recommended.
Ceramics
;
Crowns