연삭된 지르코니아의 표면 특성

김사학,Kim, Sa-Hak 대한치과기공학회 2011 대한치과기공학회지 Vol.33 No.4

Purpose: This study was conducted to examine the phase transition according to the zirconia surface treatment. Methods: The specimens were divided to four groups. The first group was sintered at $1,500^{\circ}C$ and ground; the second group was sintered at $700^{\circ}C$, ground, and sintered at $1,500^{\circ}C$; the third group was sintered at $1,500^{\circ}C$, ground, and $110{\mu}m$-sandblasted; and the fourth group was sintered at $1,500^{\circ}C$, ground, $110{\mu}m$-sandblasted, treated with 9.5% hydrofluoric acid, and ultrasonic cleaner-washed for two minutes. The monoclinic fractions were measured, and the surface was observed via SEM. Results: The monoclinic fraction was $0.13{\pm}0.19%$ in the control group Zr1, $1.91{\pm}0.15%$ in the experimental group Zr2, $7.71{\pm}0.34%$ in Zr3, and $8.39{\pm}0.25%$ in Zr4. On the surface, the phase transition hardly occurred in the control group Zr1, but it increasingly occurred in the experimental groups Zr3 and Zr4. Conclusion: The monoclinic fraction was high in the experimental groups Zr3 and Zr4. The phase transition did not occur in the control group, but increasingly occurred in the experimental groups.

티타늄 파우더가 금속의 열처리 시 결합강도에 미치는 영향

김사학(Sa-Hak Kim),김욱태(Wook-Tae Kim) 대한턱관절교합학회 2017 구강회복응용과학지 Vol.33 No.2

CS-3500 구강 내 스캐너로 채득된 디지털 인상의 신뢰도 및 정확도 평가

김사학 ( Sa Hak Kim ),김재홍 ( Jae Hong Kim ),김종견 ( Chong Kyen Kim ) 한국치위생과학회 2015 치위생과학회지 Vol.15 No.5

본 연구는 최신 경향의 구강 내 스캐너로 채득된 3차원 디지털 인상의 정확도와 신뢰도를 평가하기 위해 4가지 계측지점을 통하여 분석하였다. 주 모형과 비교하였을 때, 디지털 인상이 작게 계측되는 경향을 나타내었고, 각 계측지점별로 0.06∼0.12 mm 범위의 차이를 보였다. 선행연구의 결과에 의해 임상적으로 오차범위를 허용할 수 있는 것으로 나타났으며, 환자의 진단이나 치아 교정치료 계획 수립 시사용되는 모형에는 큰 영향이 없음을 확인할 수 있었다. 실험에서는 구강 내 상황이나 해부학적 구조를 무시하고 진행하였지만, 실제 임상에서 사용 시에는 구강 내 협소한 공간, 타액 등으로 인한 치아면의 난반사 증가, 혀 등의 해부학적 구조물로 인한 작업 방해 등의 여러 가지 요인이 인상과정에 영향을 줄 수 있을 것이라 판단된다. 추후 실험에서는 가능한 구강 내 상황을 재현한 상태에서 실험을 진행하면 좀더 임상 적용에 도움이 될 것으로 생각된다. The purpose of this study was to evaluate the reliability and accuracy of linear measurements in digital models compared to master model. A master model (ANKA-4; Frasaco GmbH, Tettnang, Germany) with the prepared upper full arch tooth was used. Four linear measurements were recorded between landmarks, directly on the master model and the digital models by a single examiner. Measurements were made with a digital caliper from manual model and with the software from the virtual models. The t-test for paired samples and intraclass correlation coefficient (ICC) were used for statistical analysis. The measurement of two methods showed good reliability. The mean differences between master and digital model were 0.06∼0.12 mm. These in vitro studies show that accuracy and reliability of the digital impression is similar to that of the gold standard. Therefore digital impression was also considered to be a acceptable for placement clinically.

비이온성 계면활성제 첨가에 따른 치과용 초경석고의 특성변화

김사학(Sa-Hak Kim),이상배(Sang-Bae Lee),김경남(Kyoung-Nam Kim),김광만(Kwang-Mahn Kim) 대한치과재료학회 2006 대한치과재료학회지 Vol.33 No.2

치과용 캐드캠 스캔전용 석고와 Type IV 석고로 제작된 작업모형의 표면조도 비교 연구

김사학 ( Sa Hak Kim ),김재홍 ( Jae Hong Kim ) 한국치위생과학회 2014 치위생과학회지 Vol.14 No.4

This study compared the surface roughness and surface characteristics between a type IV stone and scannable stone. Materials used were a type IV stone, two different kind of scannable stone. Ten specimens per experimental group were prepared according to manufacturer.s direction. Surface roughness of specimen was measured using profilometer. The measurement was based on the standard of Japanese Industrial Standards 1994. The mean and standard deviations of each reference point were analyzed using one-way ANOVA and Scheffe post hoc test. The program used to handle statistical analysis was SPSS 20.0 and the significance level was set at 0.05. The difference of surface roughness was statistically significant in order of Scannable Stone 10.07±0.02 μm, Scannable Stone 20.08±0.03 μm, Type IV 0.10±0.04 μm. These results will have to be confirmed in further clinical application researches.

표면 불산처리가 레진시멘트와 지르코니아 하부구조물의 전단결합강도에 미치는 영향

김사학(Sa-Hak Kim),김선문(Sun-Moon Kim),김종견(Chong-Kyen Kim) 한국콘텐츠학회 2018 한국콘텐츠학회논문지 Vol.18 No.10

이 연구의 목적은 불화 수소산 에칭 처리가 안정화된 정방 정계 지르코니아 다결정 (Y-TZP)의 결합 강도에 미치는 영향을 평가하는 것이었다. 4 그룹의 지르코니아 – 수지 시멘트 시편을 준비 하였다. 1) ZGS그룹 (zirconia, no treatment) 2) ZGSH 그룹 (zirconia, hydrofluoric acid etching treatment) 3) H-ZGS그룹 (Hybrid zirconia, no treatment) 4) H-ZGSH 그룹 (Hybrid zirconia, hydrofluoric acid etching treatment). 지르코니아와 도재 사이의 전단 결합 강도는 Instron Universal Testing Machine(ModelBBP-500, Instron Corporation, Kyunggi, Korea)을 사용하여 측정 하였다. 독립표본 t-test와 two-way ANOVA (α = 0.05)를 사용하여 데이터를 통계적으로 분석했다. 세라믹 – 수지 시멘트 결합강도는 불화 수소산 에칭 처리에 영향을 받았다 (p <0.05). 파단 표면의 디지털 현미경 검사는 불화 수소산에칭 처리한 표면처리 된 지르코니아 및 하이브리드 지르코니아 그룹에서 접착성 및 응집성 파절이 동시에 발생하는 결함을 보였다. The purpose of this study was to evaluate the influence of hydrofluoric acid etching treatment on the bonding strength of yttria-stabilized tetragonal zirconia polycrystal(Y-TZP). Four groups of zirconia-resin cement specimens were prepared; 1) ZGS group (zirconia, no treatment), 2) ZGSH group (zirconia, hydrofluoric acid etching treatment) 3) H-ZGS group (Hybrid zirconia, no treatment) 4) H-ZGSH group (Hybrid zirconia, hydrofluoric acid etching treatment). The shear bond strength between zirconia and porcelain was measured using a Instron Universal Testing Machine(Model DBBP-500, Instron Corporation, Kyonggi, Korea). Data were statistically analyzed using independent t-test and two-way ANOVA(α=0.05). The ceramic-resin cement bonding strength was affected by hydrofluoric acid etching treatment(p<0.05). Digital microscope examination of the fracture surface showed mixed failures with adhesive and cohesive types in hydrofluoric acid etching treatment with treated zirconia and hybrid zirconia groups.

분광측정기를 이용한 자연 치아의 색조 비교 분석

김사학(Sa-Hak Kim),황성식(Seong-Sig Hwang),이혜은(Hye-Eun Lee) 한국콘텐츠학회 2016 한국콘텐츠학회논문지 Vol.16 No.2

본 연구는 상악 전치부 색조 선택에 객관적인 기준을 설정하고자 색체계 Shade-Eye NCC를 이용하여 CIE L<SUP><SUP>*</SUP></SUP>, a<SUP>*</SUP>, b<SUP>*</SUP>값으로 측정하여 이 값들을 비교 분석하고 그 의미를 고찰하고자 실시되었다. 치과를 내원하는 환자에게 연구 의도를 설명해 주고 동의를 얻어 111명(남자 50명, 여자 61명)의 3개 치아, 즉 상악 중절치, 상악 측절치, 상악 견치 총 333개의 치아를 측색하였다. 절단부와 치경부의 색차를 비교한 결과 상악견치의 ΔE<SUP>*</SUP>값이 5.81(±2.98)으로 가장 낮았으며, 상악 측절치 6.51(±3.23), 상악 중절치의 7.51(±3.04) 순으로 점차 그 색차가 커지는 것을 알 수 있었다. 중절치와 측절치, 견치 모두 여성이 남성에 비해 명도(L<SUP>*</SUP>)가 높았으며, 황색채도(b<SUP>*</SUP>)는 중절치에서 남성이 여성보다 약간 높게 나타났다(p<0.05). 연령은 중절치의 명도(L<SUP>*</SUP>), 적색채도(a<SUP>*</SUP>), 황색채도(b<SUP>*</SUP>), 측절치와 견치의 명도(L<SUP>*</SUP>), 황색채도(b<SUP>*</SUP>)에 유의미한 영향을 미치는 것으로 나타났다(p<0.05). 흡연은 자연치의 색조에 유의미한 영향을 미치지 못하였으며, 음주는 중절치의 명도(L<SUP>*</SUP>)를 감소시키며, 측절치의 적색채도(a<SUP>*</SUP>)를 감소시키는 경향을 나타냈다(p<0.05). 만성질환은 중절치와 측절치의 명도(L<SUP>*</SUP>)를 감소시키는 경향을 나타냈다(p<0.05). This study is to set the objective criteria on maxillary incisors shade selection by using the colorimetric Shade-Eye NCC as measuring in CIE L<SUP>*</SUP>, a<SUP>*</SUP>, b<SUP>*</SUP> values, and look into the meaning by analyzing its values. We explain the purpose of this study and gotten their agreement from patients visiting the dentist, 111 people’s (men 50, women 61) three teeth, the maxillary central incisor, maxillary lateral incisor, maxillary canines, total of 333 teeth colorimetry. As a result of comparing the differences in colors between cervical margin and incisal edge, ΔE<SUP>*</SUP> of canine is shown as low as 5.81(±2.98), followed by lateral incisor of maxilla as 6.51(±3.23) and central incisor of maxilla 7.51(±3.04). Females show higher luminosity(L<SUP>*</SUP>) than males do in all teeth- central incisor, lateral incisor and canine; in yello chroma(b<SUP>*</SUP>) males’ central incisor is slightly higher than that of females (p<0.05). Age significantly influences the luminosity and red (a<SUP>*</SUP>) and yellow chroma (b<SUP>*</SUP>) of central incisor(L<SUP>*</SUP>); the luminosity(L<SUP>*</SUP>), and yellow chroma(b<SUP>*</SUP>) of lateral incisor and canine (p<0.05). Smoking doesn’t significantly influence the color of natural teeth. Drinking reduces the luminosity of central incisor as well as red chroma of lateral incisor(p<0.05). A chronic illness is likely to reduce the luminosity of central incisor and lateral incisor(p<0.05).

석고계(石膏系) 및 인산염계(燐酸鹽系) 매몰재의 Liquid 온도에 따른 주조체 적합도에 관한 실험적 연구

김사학,Kim, Sa-Hak 대한치과기공학회 1996 대한치과기공학회지 Vol.18 No.1

Among investment for dental casting, we selected 4 kinds of investment(2 Gypsum-bonded and 2 Phosphate-bonded) and prepard 120 specimen by dividing into two cast of using Ring and Ringless case from $0^{\circ}C$ to $30^{\circ}C$ at interval of $10^{\circ}C$ to invest in fluence on the fitness of casting body according to the liquid temperature of Gypsum-bonded and Phosphate-bonded investment. The result was as follows; 1. Gypsum-bonded investment showed best fitness at $30^{\circ}C$ representing difference of singnificance in order of $20^{\circ}C$, $10^{\circ}C$, and $0^{\circ}C$, From the difference of investment, Deguvest was proved superior than Cristobalite. 2. Phosphate-bonded investment showed no severe difference at $10^{\circ}C$ and $20^{\circ}C$, but showed better fitness at $10^{\circ}C$, representing difference of significance in order of $0^{\circ}C$, $30^{\circ}C$, difference of significance was shown between investment also. 3. In Ringless investing method, there were no difference of significance in Deguvest CF and Unovest. 4. When using a Ring with a Sheet of asbestos liner installed, there was some difference of significance representing superiority of Ringless investing method.

도재전장관용 Opaque 도재에 관한 연구 - paste opaque을 중심으로 -

김사학,고대진,이용근,김광만,김경남,Kim, Sa-Hak,Ko, Dae-Jin,Lee, Yong-Keun,Kim, Kwang-Mahn,Kim, Kyoung-Nam 대한치과기공학회 2002 대한치과기공학회지 Vol.23 No.2

The purpose of this study was to analyze the commercial paste opaque products currently available in domestic of foreign as well as domestic, such as Duceram Plus(DU; Ducera Dental GmbH, Germany), VMK 95(VM; Vita Co., Germany), Noritake EX-3(EX; Noritake Co., Japan) and Ceramax(CE; Alphadent Co., Korea). They were characterized in thermal expansion coefficient, particle size distribution, viscosity and solvent using thermomechanical analyzer, particle size analyzer, rheometer and infrared spectrophotometer. Experimental results are as follows; Firstly, thermal expansion coefficients were determined $13.9{\times}10-6/^{\circ}C$ for DU, $14.3{\times}10-6/^{\circ}C$ for VM, $13.3{\times}10-6/^{\circ}C$ for EX, and $14.0{\times}10-6/^{\circ}C$ for CE. Secondly, percent of partice size below $1{\mu}m$ were 12% for DU, VM and CE, and 13% for EX, percent between $1{\mu}m$ and $5{\mu}m$ were 42% for DU, 42% for VM, 38% for EX, and 61 % for CE, percent between $5{\mu}m$ and $10{\mu}m$ were 21 % for DU, 24% for VM, 20% for EX, and 18% for CE, and over $10{\mu}m$ were 25% for DU, 22% for VM, 29% for EX, 9% for CE. Thirdly, the basic composition of the solvent in all of the commercial paste opaques were determined as ethylene glycol from FT-IR investigation. Lastly, measured viscosities were 1798 cp for DU, 536 cp for VM, 1110 cp for EX, and 721 cp for CE.

CEREC^ⓡ system에서 사용하는 세라믹 소재로 가공된 CAD/CAM 전부도재관의 변연간격 비교분석

김재홍,김기백,김사학,Kim, Jae-Hong,Kim, Ki-Baek,Kim, Sa-Hak 대한치과기공학회 2016 대한치과기공학회지 Vol.38 No.3

Purpose: The purpose of this study is to evaluate the marginal gap of all-ceramic crowns fabricated by CEREC$^{(R)}$ in-office CAD/CAM system. Methods: The mandibular first molar was selected as the abutment for the experiments. Thirty working models were prepared. VITA Mark II(VM) and VITA Enamic(VE), LAVA Ultimate(LU) blocks were milled using CEREC MCXL with CEREC 3D system to construct 10 crowns for each groups. To measure marginal gap, milled restorations were examined under digital microscope with scale under 160x magnifications. The results were statistically analyzed using the one-way ANOVA and Tukey's HSD test(${\alpha}=0.05$). Results: There was no significant difference in the marginal gap regarding to ceramic materials(p>0.05). Conclusion: Single crowns fabricated using CEREC in-office CAD/CAM system provided clinically acceptable marginal gap. This confirmed that the type of ceramic material used does not determine the precision of fit of a prosthesis.