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멀론 파절 시험 모델을 이용한 치과용 CAD/CAM왁스 블록의 절삭 가공성 및 가공 정확성 평가
정창섭 대한치과재료학회 2023 대한치과재료학회지 Vol.50 No.3
본 연구는 ISO 18675:2022에 명시된 멀론(Merlon) 파단 시험 모델을 이용하여 치과용 CAD/CAM 왁스 블록의 가공성및 가공 정확성을 평가하였다. 본 연구에서는 3종의 CAD/CAM 왁스 블록(WAX DISK α, CASTING WAX, and MAZIC Wax)을 사용하였다. 멀론 파절 시험 시편을 준비하기 위해 세 가지 두께(0.2 mm, 0.3 mm, 0.4 mm)로 CAD 참조데이터(CRD)를 설계하였다. 밀링 머신을 사용하여 90개의 시편을 제작하였다. 가공된 시편의 가공성 점수는 육안검사를 통해 계산되었다. CAD 참조 데이터와 CAD 시편 데이터를 중첩하고, 중첩된 데이터의 RMS 값을 계산하여가공 정확성을 확인하였다. 결과 값은 one-way ANOVA(α= 0.05)로 평가하였고, 사후 분석은 Tukey HSD test를 이용하였다. 가공성과 가공 정확성 결과에서 치과용 CAD/CAM 왁스 블록은 종류와 관계없이 0.4 mm 두께에서 가장 우수한가공성을 나타내었다. 또한, 0.4 mm 실험군의 가공 정확성은 HCW군(28.74±2.11 µm)과 VMW군(32.23±3.45 µm)이YWD군(36.94±4.31 µm) 보다 우수하였다(P<0.05). 따라서 이러한 결과는 정확한 보철물 제작을 위한 사전 지식과효율적인 가공 방안에 대한 객관적인 지표를 제공할 수 있을 것으로 기대된다. This study evaluated the machinability and machining accuracy of dental CAD/CAM wax blocks using the merlon fracture test model specified in ISO 18675 (2022). Three types of CAD/CAM wax blocks (WAX DISK α, CASTING WAX, and MAZIC Wax) were used in this study. The merlon fracture test specimens were prepared using the CAD reference data with three different thicknesses (0.2 mm, 0.3 mm, and 0.4 mm). Ninety samples were fabricated by using a milling machine. The machinability score of the fabricated sample was counted by visual inspection. The machining accuracy was estimated by overlapping the CAD reference data and the CAD specimen data and calculating the RMS value from the overlapped data. The values of the result were evaluated by one-way ANOVA (α=0.05), and post-hoc analysis was performed using the Tukey HSD test. As a result of machinability and machining accuracy, dental CAD/CAM wax blocks showed the best machinability at a thickness of 0.4 mm regardless of type. Additionally, in the machining accuracy of the 0.4 mm experimental group, the HCW group (28.74±2.11 µm) and the VMW group (32.23±3.45 µm) were superior to the YWD group (36.94±4.31 µm) (P<0.05). Therefore, these results are expected to provide objective indicators for prior knowledge and efficient processing plans for accurate dental prostheses.
치과용 CAD/CAM 전용 세라믹기반 하이브리드 레진 수복물의 변연 적합 연구
정창섭,박종경,Jeong, Chang-Seop,Park, Jong-Kyoung 대한치과기공학회 2020 대한치과기공학회지 Vol.42 No.3
Purpose: This study aimed to assess and compare the marginal fit of ceramic-based hybrid resin restoration (HYB) and zirconia restoration (ZIR) for dental computer-aided design/computer-aided manufacturing systems. Methods: A stainless steel master model was produced. The impression was first made with silicone, and then stone working models were produced. A total of twenty restorations were fabricated with two different materials: ZIR and HYB. The silicone film thickness of the marginal gap was measured using a digital microscope; digital photos were taken at a magnification of ×160, and then analyzed using a measurement software. The values of the result were evaluated with the independent-sample t-test (α=0.05). All statistical analyses were performed with a statistical software. Results: The mean values for the marginal gap was 37.14±2.96 ㎛ for HYB, compared with 40.37±5.26 ㎛ for ZIR. No significant difference was found between ZIR and HYB (p=0.107). Conclusion: As a result, the marginal fit of the restoration fabricated using the hybrid resin was better than that of the restoration fabricated using zirconia. Also, the marginal fit of all groups was below the clinical acceptable range of 120 ㎛. Thus, HYB for dental CAD/CAM system in this study is expected to be suitable for clinical use in dentistry.
Gap Junction Contributions to the Goldfish Electroretinogram at the Photopic Illumination Level
정창섭,김도연 대한약리학회 2012 The Korean Journal of Physiology & Pharmacology Vol.16 No.3
Understanding how the b-wave of the electroretinogram (ERG) is generated by full-field light stimulation is still a challenge in visual neuroscience. To understand more about the origin of the b-wave, we studied the contributions of gap junctions to the ERG b-wave. Many types of retinal neurons are connected to similar and different neighboring neurons through gap junctions. The photopic (cone-dominated) ERG, stimulated by a small light beam, was recorded from goldfish (Carassius auratus) using a corneal electrode. Data were obtained before and after intravitreal injection of agents into the eye under a photopic illumination level. Several agents were used to affect gap junctions, such as dopamine D1 and D2 receptor agonists and antagonists, a nitric oxide (NO) donor, a nitric oxide synthase (NOS) inhibitor, the gap junction blocker meclofenamic acid (MFA), and mixtures of these agents. The ERG b-waves, which were enhanced by MFA, sodium nitroprusside (SNP), SKF 38393, and sulpiride, remained following application of a further injection of a mixture with MFA. The ERG b-waves decreased following NG-nitro-L-arginine methyl ester (L-NAME), SCH 23390, and quinpirole administration but were enhanced by further injection of a mixture with MFA. These results indicate that gap junction activity influences b-waves of the ERG related to NO and dopamine actions.
정창섭,배지명,김정미,박영범,오승한 대한치과재료학회 2018 대한치과재료학회지 Vol.45 No.1
The purpose of this study was to evaluate the shear bond strengths between various hybrid computer-aided design (CAD)/computer-aided manufacturing (CAM) restorative materials and repairing resin. Two resin network-based hybrid (Lava Ultimate and Polyglass), one ceramic framework-based hybrid (Enamic), and one zirconia (Zenotec Zr bridge) CAD/CAM restorative materials were used in this study. The shear bond strength test and failure modes of four experimental groups designated LUS (Lava Ultimate), ENA (Enamic), PGB (Polyglass), and ZBR (zirconia control group) were characterized in this study. The hybrid CAD/CAM restorative materials showed stronger shear bond strengths in the sequence of PGB, LUS, and ENA (P<0.05). The shear bond strengths of PGB and LUS groups showed significantly higher than those of ZBR (P<0.05), while ENA did not show any significant difference from ZBR (P<0.05). The PEG and LUS groups mostly exhibited cohesive failure, but the ENA and ZBR groups predominantly showed adhesive failure. Therefore, resin network-based hybrid CAD/CAM restorative materials such as Lava Ultimate and Polyglass should be more useful for intra-oral repairs.
광 Disc에서 Bump(pit)의 형태가 재생신호에 미치는 영향
정창섭 한국광학회 1993 한국광학회지 Vol.4 No.4
광 disc상의 bump(pit)의 형태가 재생신호에 미치는 영향을 알아보기 위해 스칼라 회절이론을 사용하였다. 이를 위하여 직사각형과 준원추형 그리고 원추형의 bump를 가정하여 신호를 계산한 결과 재생신호는 bump의 형태에 따라 현저한 차이를 보였다. 또한 세가지 bump의 형태중 직사각형 bump에서 가장 좋은 신호를 재생시킬 수 있음을 알 수 있었다. 실제로는 이러한 직사각형의 이상적인 형태의 bump는 제작상 어려움이 있으나 "둥글기" 정도에 따라 만족할 만한 재생 신호를 얻을 수 있다는 것을 보였다. The scalar diffraction theory of the read-out signal in optical disc is described. and numerical results is given. The strength of this signal depends on the shape of bump(pit) which show more or less rounding of the edge because of the photoresist process. It is shown that the ideal shape is the retangular form, with no rounding of edge. This form is not achievable in practise. but the results show that very satisfactory values of the read-out signal can nevertheless be achieved in the presence of the moderate amounts of rounding.unding.