Sintering behavior and mechanical properties of zirconia compacts fabricated by uniaxial press forming

Gye-Jeong Oh,Kwi-Dug Yun,Kwang-Min Lee,Hyun-Pil Lim,Sang-Won Park 대한치과보철학회 2010 The Journal of Advanced Prosthodontics Vol.2 No.3

PURPOSE. The purpose of this study was to compare the linear sintering behavior of presintered zirconia blocks of various densities. The mechanical properties of the resulting sintered zirconia blocks were then analyzed. MATERIALS AND METHODS. Three experimental groups of dental zirconia blocks, with a different presintering density each, were designed in the present study. Kavo Everest(R). ZS blanks (Kavo, Biberach, Germany) were used as a control group. The experimental group blocks were fabricated from commercial yttria-stabilized tetragonal zirconia powder (KZ-3YF (SD) Type A, KCM. Corporation, Nagoya, Japan). The biaxial flexural strengths, microhardnesses, and microstructures of the sintered blocks were then investigated. The linear sintering shrinkages of blocks were calculated and compared. RESULTS. Despite their different presintered densities, the sintered blocks of the control and experimental groups showed similar mechanical properties. However, the sintered block had different linear sintering shrinkage rate depending on the density of the presintered block. As the density of the presintered block increased, the linear sintering shrinkage decreased. In the experimental blocks, the three sectioned pieces of each block showed the different linear shrinkage depending on the area. The tops of the experimental blocks showed the lowest linear sintering shrinkage, whereas the bottoms of the experimental blocks showed the highest linear sintering shrinkage. CONCLUSION. Within the limitations of this study, the density difference of the presintered zirconia block did not affect the mechanical properties of the sintered zirconia block, but affected the linear sintering shrinkage of the zirconia block.

다층 지르코니아 블록 종류와 설계위치에 따른 지르코니아 코핑의 기계적 특성 비교

강재민,김원영,정인성,전병욱 대한치과기공학회 2019 대한치과기공학회지 Vol.41 No.3

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.

Full Zirconia Crown용으로 사용되는 block의 제조사의 굴곡강도와 임상작업후의 굴곡강도에 관한 연구

정효경,곽동주,Jung, Hyo-Kyung,Kwak, Dong-Ju 대한치과기공학회 2011 대한치과기공학회지 Vol.33 No.4

Purpose: The purpose of this study was to evaluate flexural strength of full zirconia crown using block after clinical work. Methods: The three point bending test was used to measure the flexural strength of zirconia block. Statistical analysis was done using the Statistical Package for Social Sciences version 19.0 for Windows. As for the analysis methods, the study used analysis of variance, Tukey's test. Results: The ave Rage value of flexural strengths of WIELAND, Zirkonzahn, Hass, D-MAX were 516.2 MPa, 612.6MPa, 566.2MPa, 744.6MPa. The ave Rage value of Surface Roughness of WIELAND, Zirkonzahn, Hass, D-MAX were 0.39Ra, 0.33Ra, 0.33Ra, 0.47Ra. Conclusion: Flexural strength of zirconia block decreased after clinical work. Flexural strength of zirconia block is equal to or higher than flexural strength of dental metal, so zirconia block can be used as dental material.

Merlon 파절 시험 모형을 이용한 CAM용 세라믹 블록의 절삭가공성 평가

이희정(Heejung Lee),배지명(Ji-Myung Bae),오승한(Seunghan Oh) 대한치과재료학회 2022 대한치과재료학회지 Vol.49 No.1

In this study, the machinability of two silica-based and two zirconia-based ceramic blocks was evaluated by using the Merlon fracture test model in accordance with the International Standard “ISO/DIS 18675 Dentistry — Machinable ceramic blanks (2020)”. The two silica-based blocks of Vitablocs Mark II (VM) and IPS e.max CAD LT (IC) were machined with Cerec inLab MC ×5 (Dentsply Sirona, Bensheim, Germany), and the two zirconia-based blocks of Katana Zirconia HT (HT) and Katana Zirconia STML (ST) were machined with DWX-51D (Roland, Sydney, NSW, Australia). For the evaluation of the machinability of the prepared specimens, one Merlon wall was subdivided into 10, and the intact surface was counted among the ten divided surfaces. Each sample having four Merlon walls was rated out of 40. The surface roughness of the prepared specimens was measured using a surface probe microscope. The machinability of the prepared specimens in 0.4 mm group (32.00±3.82) showed the highest score values compared to other groups (P<0.05). Also, the machinability decreased in proportion to the machined thickness of the specimens. A comparative test of the machinability of silica-based and zirconia-based blocks showed that the machinability scores of two zirconia-based blocks were significantly higher than those of silica-based blocks (P<0.05). From the result of surface roughness measurement, two silica-based blocks (VM and IC) showed a rough surface in the bottom area and a smooth region in the Merlon area. On the contrary, two zirconia-based blocks (HT and ST) showed a smooth surface in the bottom area and a rough surface in the Merlon area. These results confirmed that the material for used for computer aided milling (CAM), the block pre-treatment process, and the insertion direction of the milling bur seemed to affect the machinability of the block for CAM. Therefore, within the limitation of this study, we can expect that additional research considering external factors such as various block materials, cutting machines, and milling burs would be necessary.

지르코니아 블록 종류에 따른 전부도재관의 기계적 특성 비교

김원영,정인성,전병욱 대한치과기공학회 2015 대한치과기공학회지 Vol.37 No.3

Purpose: This study provided the basic data for selecting the zirconia blocks by comparing the mechanical properties of the all ceramic crown between the domestic, import, translucent and shade blocks that were used in clinically. Methods: Currently, the most commercial block of five types(one import and two domestic block which is the translucent and shade) were used. It were elucidated by means of three point bending test, hardness test, FE-SEM observations and EDX analysis. The results were analyzed using a one-way ANOVA and Scheffe post hoc test for significant findings. Results: For flexural strength, LT specimen was the highest as 733.1 ㎫, followed by JT specimen(712.0 ㎫), ZT specimen(646.0 ㎫), LS specimen(553.1 ㎫), JS specimen(429.0 ㎫). One-way ANOVA showed statistically significant difference between groups for flexural strength(p<0.05). For hardness, ZT specimen was the highest as 1556.5 Hv, followed by JT specimen(1540.3 Hv), LT specimen(1512.3 Hv), JS specimen(1472.0 Hv), LS specimen(1353.3 Hv). One-way ANOVA showed statistically significant difference between groups for hardness(p<0.05). Conclusion: Domestic block was higher than import block for flexural strength, and translucent block was higher than shade block for flexural strength. However, all blocks showed clinically acceptable range. There was no significant difference in hardness between domestic and import blocks. And significant difference was observed in translucent and shade blocks.

지르코니아 CAD/CAM block의 강도에 관한 연구

이정수 대한치과기공학회 2008 대한치과기공학회지 Vol.30 No.2

Recently, zirconia is widely used in the field of dental ceramics thanks to the proliferation of CAD/CAM systems. Accordingly, different types of zirconia block are being solid in the market. However, there are no precise, objective standards for properties of zirconia. This study concerns the flexural strength of zirconia ceramic for CAD/CAM block. The test specimens used for this study were ZirBlank(Acucera), ZirBlank shade(Acucera), VITA, Cercon(Densply) and Cerasys. The test results suggest that ZirBlank shade block shows the highest flexural strength and density among the zirconia blocks tested. Its flexural strength was 971 58 and its density was 99.89%. On the other hand, Cerasys block shows the lowest flexural strength of 576 36 and the lowest density of 94.85%. Given all, the density of the specimens is found to be directly proportional to strength and inversely to grain size.

구강인기방법과 블록 종류에 따른 지르코니아 코핑의 변연적합도 비교

정인성(In-Sung Chung),전병욱(Byung-Wook Jeon),김원영(Won-Young Kim) 한국콘텐츠학회 2016 한국콘텐츠학회논문지 Vol.16 No.1

구강인기방법과 지르코니아 블록 종류에 따른 지르코니아 코핑의 변연적합도 변화를 관찰하기 위해 2종의 고무인상재와 1종의 구강스캐너를 사용한 구강인기방법과 3종의 지르코니아 블록을 사용하여 지르코니아 코핑을 10개씩 제작하여 표면 거칠기와 변연적합도를 측정하였다. 표면 거칠기는 LUXEN Smile(2.3±0.9㎛) 블록이 가장 우수하였다. 그리고 협측 변연간격은 HL시편(26.5±2.1㎛), 설측 변연간격은 HL시편(27.2±2.1㎛), 근심 변연간격은 HJ시편(29.6±4.0㎛), 원심 변연간격은 HJ시편(29.0±3.0㎛)이 가장 낮게 나타났으며, 통계학적으로 유의차가 있었다(p<0.05). 이 결과, 구강인기방법과 지르코니아 블록 종류가 변연적합도에 영향을 준 것으로 나타났으며, 변연간격은 모든 군에서 임상적 허용 범위 내에 속했다. The purpose of this study was to compare of marginal fitness of zirconia copings according to impression techniques and zirconia blocks. For the conventional impression, two types of rubber impression materials were used and digital impression was made by using an intraoral scanner. Zirconia copings were manufactured from three types of blocks. With each of ten zirconia copings was determined by surface roughness and marginal fitness. For surface roughness, LUXEN Smile(2.3±0.9㎛) block was superior. And the lowest mean values and standard deviations of marginal gap for the HL specimens were 26.5±2.1㎛ for buccal, 27.2±2.1㎛ for lingual, and that of the HJ specimens 29.6±4.0㎛ for mesial, 29.0±3.0㎛ for distal. One-way ANOVA showed statistically significant difference between groups for marginal fitness(p<0.05). From the above results, the impression techniques and zirconia blocks had influence on marginal fit of the zirconia copings. Also the marginal fitness of all groups showed clinically acceptable range.

치과용 디스크 블록 조립체

지병찬,원유섭,유희성,신수민,임수정,방재철 순천향대학교 부설 산업기술연구소 2021 순천향 산업기술연구소논문집 Vol.27 No.2

Artificial teeth are manufactured through a CAD/CAM technology for disc blocks using zirconia powder, which has excellent aesthetics, strength, and biocompatibility. The milling (CAM) process of the ceramic disc block generally requires two steps as follows; a step processing for forming steps for fixing jigs on the upper and lower outer peripheral surfaces of the disk block, and a vertical surface processing for flatness of the upper and lower surfaces. The above two processes require additional processing and waiting time, and cause material loss and lower quality due to various impact, which ultimately leads to an increase in manufacturing costs. In this study, a research was conducted to exclude the above additional process by mounting a resin assembly to a disk block. The assembly was manufactured using 3D printing equipment and found to be easily combined during the milling process using the so-called Lego method and the ring-groove method, enabling an automated process. By skipping the aforementioned two process steps, effects such as shortening manufacturing time, reducing material loss, improving processability and durability, increasing productivity, and finally reducing manufacturing cost were confirmed.

치과용 지르코니아 착색 후 건조시간에 따른 반투명도의 차이

이주희(Joo-Hee Lee),박진영(Jin-Young Park),김동연(Dong-Yeon Kim) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.4

치과보철물의 심미적 결과를 조절하는 중요한 요인은 반투명도이며, 지르코니아 착색제의 건조 정도가 반투명도에 어떠한 영향을 미치는지 알아보고자 한다. 실험을 위해서 지르코니아 블록별로 원형 시편을 총 90개 제작하였다. 그 다음 지르코니아 시편을 착색제로 180초 침적 후 미건조(0초), 중간건조(30초), 완전건조(30분)의 건조시간(Dry time)을 부여한 후 지르코니아 소결로를 이용하여 원형 시편을 소결하였다. 분광광도계(Spectrophotometer CM-3600A, Konica Minolta, Japan)를 이용하여 흑색표준타일과 백색표준타일 위에 시편을 놓고, 표준광원 D65의 조건에서 정반사광 제거방식으로 지르코니아 원형 시편을 각각 측정하였다. 시편당 총 3번씩 반복측정하였다. 지르코니아의 건조시간에 따른 반투명도를 비교 분석하기 위하여 One-way ANOVA를 시행하였다. 지르코니아 종류별, 착색제에 따라 반투명도는 통계적으로 차이가 있었고(P < 0.001), 건조시간에 따라서는 통계적으로 차이는 없었다(P > 0.922). 그러나, 완전건조인 상태일 때, 반투명도 값이 작은 것으로 나타나 건조가 잘 될수록 지르코니아 색상이 투명하다는 것을 알 수 있었다. Dental prosthesis translucency importantly contributes to aesthetic outcomes. The purpose of this study was to investigate the effect of drying time and zirconia coloring agent type on translucency. For the experiment, 90 circular specimens were fabricated for each zirconia block. Then, zirconia specimens were treated with a coloring agent for 180 seconds and dried for 0 seconds (undried), 30 seconds (intermediate dry), or 30 minutes (complete dry). Then, a specimen was placed on a black standard tile or a white standard tile, and using a standard D65 light source reflected was measured using the light removal method. A total of three repeated measurements were obtained per specimen. One-way ANOVA was used to compare and analyze the relationship between zirconia translucency and drying time. Zirconia and coloring liquid types were significantly associated with translucency (P < 0.001). Although no significant difference was observed with respect to drying time (P > 0.922), zirconia in the completely dried (30 minutes) state was more translucent.

치과용 생체보철물 제작을 위한 TZP 단일구조 전부도재관 블럭의 물성과 저온열화 후 굴곡강도에 관한 연구

이종화,박천만,송재상,임시덕,김재도,김병식,황인환,이성국 대한치과기공학회 2012 대한치과기공학회지 Vol.34 No.2