치과용 합금 주조 시 주조링의 계류시간에 따른 보철물의 변연 적합도 실험에 관한 연구

황성식,이상혁,Hwang, Seong-Sig,Lee, Sang-Hyeok 대한치과기공학회 2002 대한치과기공학회지 Vol.23 No.2

With regard to the manufacture of dental prosthesis, all the dental mechanism is of vital significance at the aspect of activating its function by fixing the prosthesis to Patient's oral cavity. However, if there we will take our immediate action without the discretion about its process none the less for the importance of dental mechanism, then we might have a serious problem. Accordingly, there need to pay attention to the dilatability makes up for the shrinkage state occurring by the feature of metal materials and manufacturing process which appeared in the process of dental mechanism, which eventually is expected to playa very important role in casting a dental prosthesis appropriate to one's oral tissue. This study was designed to take into account of the effects on margin consistency of prosthesis according to the continued time of casting-ring in the course of the casting of dental alloy. For this, the researcher made an experiment on the casting of dental alloy, its dilatability, and the change of phase. The results of this study were as follows: First, the researcher could see that the sample which was cast under the condition of $650^{\circ}C/20$ Minutes(the continued time) was far superior to others at the aspect of margin consistency. Second, according to the measurement of expansion coefficient by Dilatometer, the researcher perceived the fact that the expansion-coefficient showed a maximum of $37.1{\mu}m$ considering the sample's length which was cast with ordinary temperature under the condition of $650^{\circ}C/20$ Minutes. Third, from the result of X-ray diffraction under the condition of $650^{\circ}C/20$ Minutes(the continued time), the researcher could find that there's no difference between the change of phase and its intensity. As mentioned above, the researcher could ascertain the fact that its contraction don't give rise to the change of phase.

치과용 아크릴 의치상 레진의 연마 방법에 따른 표면조도와 광택도

황성식(Seong-Sig Hwang),임용운(Yong-Woon Im),김시철(Si-Chul Kim),전수경(Soo-Kyung Jun),이해형(Hae-Hyoung Lee) 대한치과재료학회 2014 대한치과재료학회지 Vol.41 No.4

This study investigated the influence of polishing methods on the surface roughness and gloss of three acrylic denture base resins. Two polishing methods were applied to the resin specimens: high polishing by laboratory lathe with pumice and rouge (HP) and chairside polishing kit with three silicone points (SP). Specimen preparation and surface polishing procedures were conducted to manufacturer’s recommendation. Surface roughness and gloss were measured by a contact type tester and a LED gloss checker with dual measurement mode (20°, 60°), respectively. Data were analyzed by one-way ANOVA and Scheffe’s post hoc test. P<0.05 was considered as significant. Within the limitation of this study, following conclusions were drawn. For all acrylic resins, HP method produced a significantly lower surface roughness (R<SUB>a</SUB>, R<SUB>y</SUB>, R<SUB>z</SUB>) than did SP method (P<0.05). SP procedure of specimens marked a higher surface roughness (R<SUB>a</SUB>) over the threshold roughness minimizing plaque attachment, 0.2 μm. Surface gloss units of specimens at 60° were higher than 20° illumination, but 20° gloss produced materials difference than 60° gloss. A strong negative correlation between all gloss units (8°/20°/60°) and Ra, 60° gloss showed the highest correlation coefficient.

금속의 표면처리가 다양한 치과용 비귀금속 - 세라믹 시스템의 결합강도에 미치는 영향

황성식(Seong-Sig Hwang),이해형(Hea-Hyoung Lee),이중배(Joong-Bae Lee),최기열(Ki-Yeol Choi) 대한치과재료학회 2011 대한치과재료학회지 Vol.38 No.3

The purpose of this study was to investigate the bond strength of Be-free Ni-Cr base metal alloys with dental porcelain in comparing with those of Be-containing base metal alloys. Alloys used in this study were as followings; for Be-containing alloy, Verabond (VB), Rexillium V (RV); for Be-free alloy, Verabond 2V (2V), Bellabond Plus (BP), Super 3 (S3), Tilite P (TP), Tilite S (TS). Before applying dental porcelain, alloy specimens subjected to two different surface treatments; sandblasting and degassing after sandblasting. Metal-ceramic bond strength was determined from ISO 9693 three-point bending test. Elastic modulus of metal substrate was determined from load-displacement curve obtained from subsequent loading after debonding test. Two-way ANOVA test was conducted to analyze the effect of metal alloy and surface treatment on the bond strength and their interaction. Then multiple comparisons test between group under each surface treatment and t-test between surface treatments were conducted. The metal-ceramic bond strength was significantly affected by difference in alloy used and surface treatment, and the interaction of both variances was also significant (P<0.05). These results indicate that the effect of surface treatment on the metal-ceramic bond strength was differed with variance of metal alloy used. Degassing treatment of metal alloy increased the bond strength of group RV, S3 and TP, the others were statistically unchanged. However, the bond strength of group BP decreased significantly after degassing treatment. Overall, there was no significant difference in the metal-ceramic bond strength between Be-free and Be-containing alloys and the mean bond strength values were recorded over the minimum requirement of ISO 9693 (25 MPa), In conclusion, to increase the metal-ceramic bond strength, method of surface treatment for Ni-Cr base metal alloy should be properly selected before layering of dental porcelain.

광경화성 3D 프린팅 레진의 출력각도에 따른 굽힘 특성과 신뢰성 평가

임용운,송두빈,황성식,김사학,한만소,Im, Yong-Woon,Song, Doo-Bin,Hwang, Seong-Sig,Kim, Sa-Hak,Han, Man-So 대한치과기공학회 2021 대한치과기공학회지 Vol.43 No.1

Purpose: This study aimed to compare the flexural properties and perform the Weibull analysis of photo-curing three-dimensional (3D) printing resin. Methods: Photo-curing temporary resin (3D polymer) was used as a printing resin. Specimens (65 × 10 × 3.3 ㎣) were prepared following the ISO 20975-1 guidelines and according to the different printing orientations using a digital light processing 3D printer (D2 120; Dentium). The flexural strength (FS), flexural modulus, and work of fracture (WOF) were measured using a universal testing machine (Instron 3344; Instron) at a crosshead speed of 5 mm/min. Results: In this study, the 0° orientation exhibited higher FS and WOF than the 45° orientation. Significant differences were found among the printing orientations (p<0.05). Specimens printed at the 0° orientation were the most accurate. In the Weibull analysis, 0° showed the greatest Weibull modulus (m), which represents a higher reliability. Conclusion: 3D printing should be selected and used by considering flexural properties, size accuracy, and reliability.

지르코니아 코어의 표면처리 방법에 따른 도재 축성의 전단결합강도

신천호 ( Cheon Ho Sin ),황성식 ( Seong Sig Hwang ),한경순 ( Gyeong Soon Han ) 한국치위생과학회 2013 치위생과학회지 Vol.13 No.4

This study aimed to illuminate the correlatives between the surface processing of Zirconia core and the shear bond strength. The specimens were made by precipitating for two minutes in color liquid and drying to produce a colored Zirconia core following the manufacturer`s instructions. The specimens were divided into 4 subgroups according to the surface treatment-sandblasted+liner treatment, SLT group; sandblasted treatment, ST group; liner treatment, LT group; non treatment (control), NT group. The specimens were put on the device with regard to ISO/TS 11405, then tested the shear bond strength with 1 mm shearing speed per minute using the Instron multi-purpose tester. The collected data was analysed by one way ANOVA and t-test. After applying the liner and sandblast to the Zirconia core, shear bond strength value were SLT (23.19 MPa), ST (21.17 MPa), LT (20.53 MPa) and NT (16.46 MPa) in the order. There was a significant difference in the surface roughness between NT and ST group (p <0.001), and in the compressive shear bond strength between NT and SLT group (p<0.05). Therefore, sandblasted plus liner treatment on pre-sintered substructure increased the bond strength of veneering ceramic, compared with other surface treatments.

심미성 향상을 위한 간접수복용 Gum-Shade 복합레진의 굽힘 특성 평가

임용운 ( Yong Woon Im ),황성식 ( Seong Sig Hwang ) 한국치위생과학회 2015 치위생과학회지 Vol.15 No.4

This study investigated flexural properties of indirect Gum-shade composite resins for esthetic improvement. The material utilized in this study was Crea.lign, Twiny flow and Twiny paste (TP). Ten specimens were fabricated with a dimension of 25×2×2 mm according to the ISO 4049. After fabrications, specimens were stored in the distilled water for 24 hours at the temperature of 37oC. Three-point bending test was performed in universal testing machine (Instron 3344; Instron, USA) at a crosshead speed of 1 mm/min until the failure occurred. TP exhibited a higher flexural strength (FS) and flexural modulus (FM) compared to the flowable materials. There were significant differences among the three materials in FS and FM. However, there was no significant difference in work of fracture (WOF) in all tested materials (p>0.05). In Weibull analysis, TP showed the greatest Weibull modulus which means a higher reliability of the materials. Also, Gum-shade composite resins revealed a strong correlation in all flexural properties. There was a positive correlation in FS-FM (r2=0.99) and a negative correlation between FS-WOF and FM-WOF (r2>0.97). Therefore, this confirmed that flexural property was important for mechanical behavior evaluation and useful information. To addition, this improved among mechanical properties correlation of materials as important factor.

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).

치과용 복합레진의 굽힘 특성과 시험 신뢰도에 미치는 시편 크기의 영향

임용운(Yong-Woon Im),황성식(Seong-sig Hwang),김사학(Sa-hak Kim),이해형(Hae-Hyoung Lee) 대한치과재료학회 2017 대한치과재료학회지 Vol.44 No.3

The aim of the present study was to investigate the effects of specimen dimension on the flexural properties and testing reliability of dental composite resin. The composite resin was prepared experimentally by mixing a resin matrix with silanated micrometer glass filler at 50 vol%. Flexural specimens with various dimension in specimen’s width were fabricated by light curing using a split metal mold; 25×2×2 mm, 25×2×4 mm, 25×2×6 mm in length × height × width. The flexural strength and modulus were determined according to ISO 4049 test protocol at a span length of 20 mm (normal-flexural strength; NFS). Another flexural test was conducted using mini-sized specimens (12×2×2 mm, 12×2×4 mm, 12×2×6 mm) from the broken specimens at a span length of 10 mm (mini-flexural strength; MFS). Data were analyzed with ANOVA and Duncan’s post-hoc test and the test reliability was evaluated by Weibull analysis. Results showed that there are generally no significant difference in flexural strength with the increase in the specimen width in NFS and MFS tests. However, the test reliability of flexural strength based on Weibull analysis was largely changed with the variables in the dimension of width and span length. The flexural modulus of NFS was increased as the dimension of specimens width increased while there was no trend in flexural modulus of MFS test. Overall results recommend that the evaluation of flexural properties and the reliability of dental composite resins should be performed with more than one test method.