Earticle

Purpose: This study was conducted to investigate alloys spectrophotometrically including yttrium of nickel-chromium (Ni-Cr) alloys, which are used as substitutes for the regulation of beryllium and provide helpful improvements in Ni-Cr alloys. Methods: Four groups of specimens (ZN, ZY, SN and EM) were prepared for analysis. Color parameters were measured with a spectrophotometer, and color difference (ΔE*) was calculated. The t-test and one-way analysis of variance test were used to determine significant difference, and the Tukey test was used to identify where the differences were. To measure the spectroscopic reflectivity, the spectroscopic reflectance was measured and converted into CIE L*, a*, b* color system. Results: The ΔE* value of each metal ceramic group after opaque firing of Ni-Cr alloy with and without yttrium was <2, and the total group color difference (ΔE*) was below 1 in the dentin ceramic all experimental group. However, the a* and b* values of the metal ceramic groups were higher than that in the lithium disilicate all ceramic group, and the chroma was higher than the natural tooth. The brightness of all experimental groups was similar to that of the shade guide sample. Conclusion: Yttrium added to Ni-Cr alloys showed similar CIE L*, a*, b* values to Ni-Cr alloys that did not contain yttrium, indicating that yttrium had no effect on color in metallic ceramic systems.

This paper begins with reviewing the history of archeology in old China, in addition, cherishing the memories of the indelible contribution of foreign archeological pioneers and the utilization of the latest technology from western countries，nowadays some academic studies and appreciated articles from oversea still have more weight on the basis of the foreign impartial and transparent system, instead of the disproportional consequence of bad faith behaviors even unlawful doings in China. Following by some contemporary unimaginable incidents of archeology to argue the credibility without the experimental proof by the international authorized third party and citing Popper's falsification theory to challenge the possibility of falsification, subsequently highlights basic knowledge of archeology and elaborates the embarrassments of the reality and the limitations on identification of ancient ceramic whatever reliant on empirical connoisseurs or by high–tech equipment, alternately addresses relevant abnormal legal issues and the non-applicability of the fundamental legal principles. Finally concludes by enhancing the application of objective technology, integrating theory with practice, balancing the local benefit with the archeological “discoveries” and institutionalization & legalization of this area, nonetheless, it is still vexing to play a euphonysymphony by archeology, appreciation and law.

손상된 도자기는 고대부터 여러 가지 방법과 재료를 사용하여 수리복원 되었다. 도자기 수리복원의 역사는 전통적인 수리방법을 이용해 실생활에서 활용 가능한 재료들을 사용하던 방식에서 새로운 재료의 도입과 다양한 처리기법의 시도 및 사용된 재료의 분석에 이르는 전문적인 분야로까지 그 영역을 넓히며 발전을 거듭하여 왔다. 우리나라의 도자기 수리복원 방법의 변천과정은 출토유물과 문헌자료, 분석 등을 통해 조사한 결과, 동물이나 식물에서 추출된 접착제, 석회와 같은 복원제 등을 사용하여 수리 복원하던 천연재료 사용 시기(고대~일제 강점기 이전)와, 주사비 등 천연재료와 합성수지가 혼합되어 사용되는 시기(일제 강점기~1970년대), 새로운 처리기법과 재료가 도입되고 보존규범에 입각하여 수리복원이 이루어진 합성수지 사용 시기(80년대 이후)로 구분 할 수 있었다.

The damaged ceramics were repaired and restored thru various methods with various materials. The history of Ceramic repair and restoration has developed widening its areas from traditional stage utilizing applicable living material to the specified field that introduces new materials, new process methods and material analysis. Through investigations over the documents, artifacts and analysis, the period could be divided into natural material period in which uses the bonds extracted from the animals, plants and lime (prehistoric to Japanese domination period), Semi-artificial period in which mix natural material and synthetic resins such as "Jusabi"(Japanese domination period to 1970s.) and complete synthetic resin period in which introduces new materials and process methods in accordance with preservation standard (after 1980s).

Purpose: To evaluate how alumina sandblasting (AL), with and without hydrofluoric (HF) acid etching, affects surface roughness and optical properties (ΔE00 and TP) used for laminate veneers. Methods: Thirty A2-shade nano-hybrid ceramic specimens were milled and finished to a thickness of 0.5±0.01 mm and allocated to three groups (n=10): AL, AL+5% HF (AL5), and AL+9.5% HF (AL9.5). Surface roughness (Ra) and optical properties (ΔE00, TP) were evaluated. Data normality and homoscedasticity were assessed, followed by Welch’s analysis of variance (ANOVA) with Dunnett T3 (Ra) and ANOVA with Tukey HSD (ΔE00, TP) at α=0.05. Field-emission scanning electron microscope/energy dispersive X-ray spectroscopy characterized surface and microstructural changes. Results: Mean±SD were as follows. Ra (μm): AL 2.86±0.54, AL5 2.43±0.26, and AL9.5 2.79±0.15 (p<0.05); ΔE00: AL 2.94±0.90, AL5 7.79±0.70, and AL9.5 8.81±0.64 (p<0.001); and TP: AL 28.40±1.00, AL5 23.62±0.86, and AL9.5 22.69±0.72 (p<0.001). Post-hoc analysis revealed that Ra differed only between AL5 and AL9.5. ΔE00 differed among all groups. For TP, differences were present for AL versus AL5 and AL9.5, but not between AL5 and AL9.5. Conclusion: At a veneer thickness of 0.5 mm, the addition of HF etching to AL significantly increases color change and reduces translucency, whereas roughness differences are modest and group-dependent. Increasing HF concentrations induce micro-porosity and silica dissolution that likely drive optical shifts.

본 연구는 기체연료레벨 값에 대한 정밀도를 측정하기 위하여 초음파의 음향매칭에 관한 실험적인 분석을 수행한 것이다. 연구 모델은 송신과 수신에너지를 결정시키는 세라믹 어세이 (Ceramic Assay)의 구성요소에 의하여 설계되었다. 실험 장치로는 12V-DC 전원공급장치, Control T1 Board, 오실로스코프 (DSO1072B), 초음파 프로브 그리고 패턴테이블 (Pattern T)able이 사용되었다. 불감지영역에 대한 분석결과 최대피크지점인 2.9V의 시작점을 기준으로 D (0.180m) < E (0.184m) < B (0.204m) < A (0.234m) < F (0.244m) < C (0.247m) 모델 순으로 점차적으로 불감지폭이 증가되는 특성을 확인할 수 있었다. 실험결과로부터 매칭레이어 (Matching Layer)의 치수가 Ø21*3+2t로 설계된 모델에서 가장 우수한 지향 성 에너지를 생성할 수 있었다.

This work conducted the experimental analysis on ultrasonic acoustic matching in order to measure the accuracy of gaseous fuel level values. The experimental devices were used as 12V-DC supply, control T1 board, oscilloscope (DS01072B), ultrasonic probe and pattern table. The research models were designed by ceramic assay which can determine the transmitting and receiving energies. The result of the ringing area could verify the increased characteristics in the order of D (0.180m) < E (0.184m) < B (0.204m) < A (0.234m) < F (0.244m) < C (0.247m) models based on initial 2.9V of the maximum peak voltage. From the experimental results, the model designed by Ø21*3+2t of the matching layer was notable in that the most outstanding directivity energy could be created.

현재 토기 및 도자기를 보존처리 할 때 사용되고 있는 접착·복원제의 경우 크게 Epoxy계, Cellulose계, Cyanoacrylate계 등이 사용되고 있으나 재료에 따라 심한 수축으로 인한 재탈락, 황변 현상으로 인한 색상 변화, 사용 시 도구와 손에 묻어나오는 불편한 작업성, 비가역성 등 다양한 문제점을 나타내고 있다. 본 연구에서는 도자기 복원용으 로 사용되고 있는 Epoxy resin의 황변 현상과 비가역성의 문제점 해결을 목적으로 저황변, 가역성이 우수한 Urethane계 합성수지를 개발하였다. 개발된 Urethane resin의 접착력은 원액 2.07MPa로 기존 재료인 EPO-TEK301Ⓡ 1.21MPa로 1.5배 이상의 우수한 물성을 지니고 있다. 가공성 측정 결과 Urethane resin(in Talc 50wt%)의 마모율이 1.09%로 기존 재료인 Quick WoodⓇ(1.02%)의 마모율 보다는 다소 높게 측정되었으며, EPO-TEK301Ⓡ(0.41%)와 L30Ⓡ (0.39%)보다 는 2배 이상의 마모율을 보이고 있어 기존의 재료보다 쉽게 성형 과정이 이루어질 수 있는 장점을 지니고 있다. Urethane resin의 장점인 가역성 실험은 Acetone, Ethyl Alcohol 침적 후 12시간 경과 후 Urethane resin과 충전제인 Talc가 분말화 현상을 나타내며 100% 용해되었으며, 기존 Epoxy resin의 가역성이 0%인 것에 비해 매우 우수한 가역성을 지니고 있다. 내구성 평가를 위한 자외선 실험 결과 Urethane resin의 원액 기준 △E*ab 색상 변화 값이 자외선 노출 전·후 2.76로 기존의 Epoxy resin보다 약 7∼20배 정도 줄어 황변 현상으로 인한 이질감의 문제점을 최소화하였다.

In the case of adhesives & restoration agents currently being used for the preservation treatment of ceramics and earthenware, epoxy type, cellulose type and cellulose type are mainly being used. However, they are showing various problems such as re-detachment from severe contraction, color change from yellowing, work inconvenience of staining on tools and hand during usage and irreversibility. For the purpose of solving the issues of yellowing and irreversibility of epoxy resin being used to restore ceramics, urethane synthetic resin with low yellowing excellent reversibility has been developed in this study. The adhesive strength of urethane resin that has been developed has excellent properties with 2.07MPa for undiluted solution, which is 1.5 times higher than that of existing material EPO-TEK301Ⓡ 1.21MPa. The result of workability measurement showed that the wear rate of urethane resin (in Talc 50wt%) was 1.09%, which was somewhat higher than that of existing material Quick WoodⓇ (1.02%). In addition, its wear rate is two times higher than that of EPO-TEK301Ⓡ (0.41%) and L30Ⓡ (0.39%), thereby showing an advantage in its forming process compared to existing materials. As for the advantage of urethane resin of reversibility experiment, 12 hours after acetone, ethyl alcohol deposition, urethane resin and filler talc were dissolved 100% while showing powdering phenomenon. Compared to 0% reversibility of existing epoxy resin, it has much superior reversibility. The result of UV rays experiment to evaluate its durability showed that △E*ab color change value based on undiluted solution of urethane resin was 2.76 before & after UV rays exposure, which was a decrease by about 7-20 times compared to that of existing resin, thereby minimizing the issue of heterogeneity.

토기 및 도자기 유물의 표면 오염물을 제거하기 위해서는 경우에 따라 화학적 세척과정이 필요하며 , 그 과정은 신중하게 이루어져야 한다. 본 연구에서는 화학적 세척제가 토기 및 도자기에 미치는 영향을 평가하기 위해 침적실험을 수행하여 주성분원소의 용출특성에 대해 정량적인 데이터를 제공하고자 하였다. 연질토기는 재질이 약하고 흡수율이 커서 짧은 침적 시간에도 큰 용출특성을 가졌고 강한 산성에 의해서 표면 박락과 색의 변화가 발생했다 . 그러나 이러한 색의 변화는 물리적인 특성에는 영향을 미치지 않았다. 경질토기에서는 용출량이 미비하고 강한 산성에 의한 색차변화와 물리적인 변화가 없는 것으로 확인되어, 세척제에 대해 비교적 안정한 것으로 사료된다. 도자기(청자, 백자, 분청사기)에 서는 용출량이 미비하여 시료의 안정성에는 영향을 미치지 않는 것으로 판단된다. 하지만 도자기 유물에서는 빙렬이 용출특성에 관여하는 것으로 확인되어 분청사기 같은 빙렬이 발달된 유물에 적용할 시에는 주의가 필요하다.

To do conservation for ceramics, sometimes it needs to clean the ceramics chemically to remove stains on the ceramics, which should be performed with caution. This study will provide quantitative data about the extraction characteristics of major elements from ceramics through the soaking test to evaluate the stability of ceramic cleaning agents. As soft textured pottery(fired at 700℃) had high absorption, it showed higher extraction characteristics in short soaking time. Especially the strong acid among chemical cleaning agents caused the expoliation and the color change on the surface of soft textured pottery. But these color change had no effect on the physical characteristics of soft textured pottery. The hard textured pottery(fired at 1,000℃) is relatively stable in the cleaning agent because it is ascertained the extraction of that was not enough and also it had little chromatic and physical change by strong acid. Porcelains(Celadon, Whiteware and Puncheong ware) was safer than the soft textured pottery due to their low extraction. But it should take precautions to clean the porcelains with lots of cracklewares such like Puncheong ware chemically in connection with the extraction characteristics and their cracklewares.

Purpose: This study investigates one production method from several production methods of the CEREC3 system which does not require model production and that can be used without antagonistic relationship and check bite and can provide one-day treatment. Methods: The ceramic inlay was produced using the IPS Empress CAD block of Ivolar Vivadent, which is a glass ceramic block, by applying the information obtained from the optical impression prior to preparation for the maxillary right second premolar and maxillary right first premolar to the optical model constructed after preparation. The optical model was not trimmed in the case of the maxillary right second premolar while parts other than the working tooth were trimmed of their optical model in the case of the maxillary right first premolar. The thin part was reinforced after installing sprue in the maxillary right second premolar, and for the maxillary right first premolar, the thin part in the optical model was reinforced with sprue to produce the ceramic inlay. Results: The processing time for the virtual prosthesis when producing the maxillary right first premolar without trimming of the optical model was slightly delayed. Both maxillary right second premolar and maxillary right first premolar were suitable for ideal prosthesis. The thin parts of the virtual restoration were easily identified through different colors and modification was simple as the thickness was described in numeric values. It took approximately 1 hour from obtaining the optical impression to oral settlement, and production of a temporal restoration was unnecessary due to the short production time. Conclusion: The CEREC3 system enabled quick production of prosthesis due to the provision of an optical impression which enabled omission of impression sampling and model production, and also precise production due to lack of contraction and expansion of materials. In this study, the slight delay in processing time for virtual prosthesis is estimated to have resulted from the size of the optical model in the software, and both prostheses exhibited suitability for ideal prosthesis. Also, treatment was possible through one-time visits which lessened the burden of patients from having to make multiple visits to the dental clinic. Meanwhile, the patients exhibited a high level of satisfaction due to the excellent aesthetics of the ceramic material. However, precision can differ in CEREC3 based on the skills of the operator. Formation of a precise cavity of the abutment tooth, manufacturer°Øs manual, space given for cement by the program, precise use of the contrast spray containing titanium dioxide, and accurate sampling of the optical impression are considered to be important factors.

Ceramic pigments were developed by using 4 kinds of Brass scraps. Each Brass scraps were mixed with same weight-ratio of Husk ash, and fine-ground by Rotate ring mill(RRG-120, Armstech industrial. co. Ltd, Korea) after firing at 900℃, 1000℃ and 1100℃. As a result, analysis of particle size of synthetic pigments by particle size analyser, they are 3μm as average. The resulting pigments were characterized by using XRD, FT-IR, SEM Structure of the crystals are Zn2SiO4,, and ZnO, Cu2O, CuO, and cristobalite are existed and particles' shape are plate or needle. As a result of analysis of chemical composition by XRF, synthetic pigments have high SiO2 and CuO content and have SnO2, ZnO and NiO, too. 1wt%, 3wt% and 5wt% pigments were added in each lime glaze, lime-barium glaze and lime-magnesia glaze, and fired at oxidation and reducing atmosphere to figure hue in glazes out. As a result of analysis of color, chroma and brightness by UV, colors of glazes fired at oxidation atmosphere turned into green from sky blue, and colors of glazes fired at reducing atmosphere turned into pink and red.

Purpose: The purpose of this study is to investigate the effect of lithium disilicate glass ceramic polishing on the strength of the final prosthesis. Methods: Fourteen lithium disilicate glass ceramic specimens were prepared. These were randomly divided into two groups of seven(LPG: low polishing group, HPG: high polishing group). In LPG, SiC paper was sequentially polished using 300, 600, 800, 1000 grit, and the specifications of the test piece were adjusted. HPG was sequentially polished using 300,600, 800, 1000, 1200, 1500, and 2000 grit. Two groups of specimens are executed 3- point bending test. Using the statistical program SPSS 22.0, the average values of the strengths of the two groups were compared in the Mann-Whiteney test. The significance level was set at 0.05. Results: The mean strength value of HPG was measured at 307.14 ± 23.28 MPa significantly higher than LPG(p<0.001). Conclusion : The final polishing of the prosthesis is aesthetically important but has proven to play an important role in the flexural strength, early fracture, and prolongation of the prosthesis.

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: This study aimed to assess the fracture load of anterior crowns fabricated from ceramic–polymer hybrid blocks and lithium disilicate ceramic blocks, both designed for computer-aided design/computer-aided manufacturing wet milling applications. Methods: For fracture load testing, ceramic crown samples were fabricated using lithium disilicate ceramic blocks and ceramic–polymer hybrid blocks (N=15). The ceramic crowns, designed and milled for an abutment manufactured via metal 3D printing, were positioned onto a prepared maxillary right central incisor model (Nissin Dental). The fracture load of the samples was measured using a universal testing machine, and the fracture patterns were examined with a scanning electron microscope (JSM-6701F, Jeol). Differences in fracture load between the two ceramic block types were evaluated using an independent sample t-test (α=0.05). Results: The ceramic–polymer hybrid and all-ceramic materials showed statistically comparable fracture loads (p>0.05). Conclusion: On the basis of the mechanical property evaluations, we can conclude that ceramic– polymer hybrid materials meet clinical standards for use as restorative materials.