• The Journal of Korean Academy of Prosthodontics
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• v.59 no.4
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• pp.469-477
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• 2021

For successful restoration of maxillary anterior implants, both pink esthetics and white esthetics must be satisfied. For pink esthetic part, the role of appropriate provisional prosthesis restoration is important, and for white esthetic part, the color and shape of the definitive prosthesis is important. Multilayer zirconia can be used for natural tooth appearance due to the higher transparency of the incisal area compared to the conventional monolithic zirconia. Therefore, in this case, white esthetic part was achieved through multilayer zirconia after recovering function and esthetics through appropriate provisional prosthesis in a patient who lost the maxillary anterior teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.3
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• pp.293-300
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• 2022

Various materials and restorative options have been introduced recently with growing interest in esthetic dental treatment in modern society. Zirconia is especially known for its biocompatibility as well as remarkable toughness and resistance to wear, but it is limited in its use for esthetically focused treatment in anterior region for its white opacity. Lately the development of different kinds of zirconium blocks, such as colored block, clear block, and multi-layered block, allowed more extensive use of zirconia as a treatment option. This report describes a case, in which a prosthetic crown maxillary anterior region was stained with a combination of various coloring liquids before sintering to reproduce natural-looking color scheme in final restoration. The case was reported as the utilization of coloring liquid on monolithic zirconia crown could achieve esthetically satisfying prosthesis for both dentist and patient.

• Journal of Technologic Dentistry
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• v.41 no.3
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• pp.195-201
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• 2019

Purpose: This study was investigated the effect of multilayer zirconia block type and sintering method on fracture strength, micro structure and color of zirconia copings. Methods: Three kinds of multi-layered zirconia blocks were used to identify the effects of the kinds of multi-layered zirconia blocks and sintering methods on fracture strength and color reproducibility of zirconia copings. 60 Zirconia copings were fabricated and fracture strength, micro structure and color reproducibility were compared and evaluated. Results: In all the blocks, the CS group, which refers to the general sintering method had higher fracture strength of zirconia copings than the MS group that refers to the microwave sintering method(MCS/MMS; 2,107.5N/1,930.4N, DCS/DMS; 917.0N/879.1N, UCS/UMS; 2,256.9/2,050.7N). In relation to CIE $L^*$, $a^*$, $b^*$ values of zirconia copings depending on the kinds of multi-layered zirconia blocks and sintering methods, the MS group using the microwave sintering method had lower brightness and chroma than the CS group using the general sintering method. Conclusion: In all the blocks, the CS group(general sintering) had higher fracture strength of zirconia copings than the MS group(microwave sintering). In relation to CIE $L^*$, $a^*$, $b^*$ values of zirconia copings depending on the kinds of multilayered zirconia blocks and sintering methods, the MS group using the microwave sintering method had lower brightness and chroma than the CS group using the general sintering method.

• Journal of Technologic Dentistry
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• v.41 no.3
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• pp.167-175
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• 2019

Purpose: This study was investigated the effect of multi-layer zirconia block type and design location on the mechanical properties of zirconia copings. Methods: Three kinds of multi-layered zirconia blocks (Snow princess multi layered block, Multi cherry, Dental zirconia pre-shaded blank) were used to identify the effects of the kinds of multi-layered zirconia blocks, design locations on mechanical characteristics of zirconia copings. 150 Zirconia copings were fabricated and fracture strength, hardness and microstructure were compared and evaluated. Results: Dental zirconia pre-shaded blank(2,256.9N) had the highest fracture strength of zirconia copings on all the design locations, and it was followed by Snow princess multi layered block(2,107.5N) and Multi cherry(917.0N). Snow princess multi layered block(1,949.7Hv) had the highest hardness of zirconia copings on all the design locations, and it was followed by Dental zirconia pre-shaded blank(1,671.7Hv) and Multi cherry(1,383.7Hv). The cervical layer had the highest fracture strength and hardness of zirconia copings in all the blocks, and it was followed by the cervical+gradation layer, the enamel layer, the enamel+gradation layer, and the gradation layer. Conclusion: It was found that the fracture strength and hardness were different according to the kinds of multilayer zirconia block and design location, and it was confirmed that it is lower than the fracture strength of white zirconia.

• Journal of Technologic Dentistry
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• v.44 no.1
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• pp.1-7
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• 2022

Purpose: The purpose of this in vitro study is to evaluate the clinical acceptability of the marginal discrepancies and internal spacing of multi-layered zirconia prothesis by speed sintering. Methods: The two specimen types come from the same manufacturer but differ in the ingredients in layered zirconia and indication, that is anterior and posterior. The designs of both specimens were full contour crowns, and a total of 20 pieces were repeatedly fabricated, 10 for each group. The specimens were divided into two subgroups (n=10) and sintered with various total times (4 hours, 8 hours) at the maximum temperature (1,530℃). The gap between the two groups of multi-layered zirconia prostheses was measured using a silicone replica technique of 2D analysis method. The independent sample t-test was then used to compare and analyze the data obtained from the two groups (α=0.05). Results: The marginal and internal gap was superior in the 8-hour compared to the 4-hour group, and the results exhibited significant differences (p<0.05). All specimens showed that using the speed sintering schedule does not exceed the clinically permitted value of 120 ㎛, meaning zirconia prothesis using the speed sintering was adequate. Conclusion: The sintering condition is shown to affect the marginal and internal gaps of multi-layered zirconia restoration.