치과주조용 Ag-Pd-Zn-Sn-In 합금의 시효경화 특성

이재호,김명진,이희경,김형일,설효정 大韓齒科器材學會 2004 대한치과재료학회지 Vol.31 No.1

Cu가 첨가되어 있지 않고, 대신에 상대적으로 많은 양의 Zn 그리고 소량의 Sn과 In이 첨가된 치과주조용 Ag-Pd-Zn-Sn-In 합금의 시효경화 특성을 경도 시험, X선회절 실험, 주사전자현미경 관찰, 전자탐침 미소분석법으로 조사하여, 다음과 같은 결과를 얻었다. 1. 950℃에서 용체화처리된 시편을 500℃와 550℃에서 등온시효처리하면, 시효 초기에 경도가 완만히 상승하여 최고 경도에 도달하였고 최고 경도를 일정 기간 유지하고 나서 서서히 하강하였다. 2. 용체화처리된 시편은 Pd 원자가 고용된 Ag-rich α1상, Pd3Sn인 α2상, Pd2Zn인 α3상의 3상 공존이었고, 등온시효처리함에 따라 Ag-rich α1상에서 Pd-rich 상으로 추정되는 β상이 석출하였다. 3. 시효 초기의 경화는 Ag-rich 기지에서 Pd-rich 상의 석출로 인한 격자변형에 기인하는 것으로 추정된다. 4. 시효처리 시간을 연장함에 따른 과시효 연화는 입계에 Ag-rich α1상과 Pd-rich β상으로 된 층상조직의 석출과 조대화에 기인하였다. 5. Pd3Sn인 α2상과 Pd2Zn인 α3상은 시효경화에 기여하지 않았다. Age-hardening characteristics of a dental casting Ag-Pd-Zn-Sn-In alloy without copper (52.0 wt% Ag - 39.9 wt% Pd - 4.0 wt% Zn - 2.0 wt% Sn - 2.0 wt% In - 0.1 wt% Ir) was investigated by means of hardness test, X-ray diffraction study, scanning electron microscopic observations and electron probe microanalysis. The specimen solution-treated at 950℃ was three phases of the Ag-rich α1 phase containing Pd element, the α2 phase based on Pd3Sn and the α3 phase based on Pd2Zn, and the Pd-rich β phase was precipitated from the Ag-rich α1 phase by the isothermal ageing,. The initial hardening seemed to be attributed to coherency strains which were formed in the Ag-rich matrix by the precipitation of Pd-rich phase. Overageing with softening was due to the formation and coarsening of the lamella precipitates at grain boundaries, which were composed of the Ag-rich α1 and Pd-rich β phases. The α2 phase based on Pd3Sn and the α3 phase based on Pd2Zn did not contribute to the age-hardening of this alloy.

출생 시 발생한 특발성 치은섬유종증

이효설,최형준,최병재,손홍규,이제호 大韓小兒齒科學會 2008 大韓小兒齒科學會誌 Vol.35 No.4

치은섬유종증(Gingival fibromaotsis)은 치은조직의 섬유성 증식을 나타내는 드문 구강질환이다. 원인은 명확히 규명되지 않았으나 상염색체 우성 또는 열성의 유전성이거나 특발성일수 있다. 주로 영구치 맹출 시기에 나타나기 시작하나, 드물게 유치열기나 출생시부터 이환되는 경우도 있다. 치은은 서서히 증식하여 치아의 해부학적 치관부위를 덮거나 구개 변이를 일으켜 혀 운동장애를 야기하거나 입술 폐쇄를 방해하기도 한다. 이 증례의 환아는 14개월 된 여아로 출생 시부터 계속딘 치은증식을 주소로 내원하였다. 특별한 가족력이나 의학적 병력은 없었고, 임상 유전검사 결과 알려진 어떤 증후군으로 진단되지 않았으나, 신체발달이 지연되어 있었다. 펀치 생검을 하였으며, 조직검사명은 치은섬유유종증이었다. 가족력이 없어 특발성 치은섬유종증으로 진단하였다. 환아의 연령 및 전신 상태를 고려해 치은 절제술 등의 외과적 치료는 연기하기로 하였다. Gingival fibromatosis is a rare condition characterized by varying degrees of gingival hyperplasia. Gingival fibromatosis usually occurs as an isolated disorder or can be associated with a variety of other syndromes. It usually appears at the time of eruption of permanent dentition but, can develop at the time of eruption of the primary dentition and rarely at birth. It may deform palatal contour and subsequently restrict the tongue movement, resulting in interference during speech and mastication. In addition, it incapacitates maintenance of normal lip closure. A 14-month-old girl visited the department of pediatric dentistry, Yonsei University Dental Hospital, for the congenital gingival overgrowth. There was no one in the family, who showed similar pattern of gingival growth. The intraoral clinical examination revealed generalized severe enlargement throughout the maxillary and the mandibular arches. Enlarged gingival tissue was pink and had firm consistency. She was referred for chromosomal analysis, which confirmed absence of any known syndrome. Under local anesthesia, "Punch-biopsy" was performed on the labial area, and the specimen was histologically diagnosed as gingival fibromatosis. For she did not have any medical problem nor familiar history, she was diagnosed as having idiopathic gingival fibromatosis. Regarding her age and behavior, close follow-up was decided.

(AgCu)_0.43-Au_0.54Pd_0.03 합금의 시효경화 특성

배동화,설효정,이희경,김형일,김교한 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.3

팔라디움이 함유된, 시효경화성 치과주조용 고금합금의 연구를 위한 기초자료를 얻기 위하여, 4원계 □ 합금의 등온시효경화 거동과 상변태를 경도 시험, X선회절 실험으로 조사하여, 다음과 같은 결과를 얻었다. 본 합금을 250~350℃에서 등온시효처리하면, 면심정방구조를 갖는 준안정상 AuCu Ⅰ'형 규칙상이 면심정방구조를 갖는 AuCu Ⅰ형 규칙상과 면심입방구조를 갖는 Ag-rich a₁상이 생성되기 전에 생성되었다. 본 합금은 시효처리 온도에 따라 다른 시효경화 거동을 보여주었다. 350℃에서 시효처리를 하면, 경도는 시효 초기에 상승하지 않았고, 최고 경도에 도달하여 유지되고나서 시효시간을 연장함에 따라 경도가 급격히 저하하였다. 250℃에서 시효처리를 하면, 경도는 시효 초기부터 뚜렷히 상승하기 시작하였다. 그 후, 약간의 경도 하강을 보이고나서 경도는 다시 서서히 상승을 지속하였다. 350℃에서 경화는 준안정상 AuCu Ⅰ'형 규칙상의 균일핵생성에 기인하였다. 낮은 시효온도에서의 초기 경화는 다른 상변태에 의해 초래되었고, 이어서 일어나는 경화는 준안정상 AuCu Ⅰ'형 규칙상의 생성에 기인하였다. 시효시간을 연장함에 따라 생기는 과시효 연화는 평형상 AuCu Ⅰ형 규칙상의 생성에 기인하는 것으로 생각된다.

치과용 고카라트 금합금의 시효경화와 상변태 과정

배동화,설효정,이희경,김형일 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.1

The hardening behavior and phase transformation process of a dental high carat gold alloy by isothermal ageing treatment were investigated by means of hardness testing, X-ray diffraction study and scanning electron microscopic observations. The following results were obtained. The a single phase with a face centered cubic structure was finally transformed into the coexistence of the Ag-rich α₁phase with a face centered cubic structure and the AuCu I' type ordered phase with a face centered tetragonal superlattice structure by ageing of the solution-treated specimen at 400℃ and 500℃. By ageing at 500℃, the metastable Ag-rich α₁' and AuCu I' type ordered phases were formed prior to the final formation of the equilibrium Ag-rich α₁ and AuCu I type ordered phases . The hardening effect was more significant and the overageing with softening was slower by ageing at 400℃ than 500℃. By ageing at 500℃, the hardening was attributed to the formation of the metastable AuCu I' type ordered phases from the a phase, the overageing with softening was due to the formation of the AuCu I type ordered phase from the metastable Ag-rich α₁' and AuCu I' type ordered phases. By ageing at 500℃, the incubation period which limited the beginning of the hardening in the early stage of ageing existed, and the formation and growth of the precipitates which contributed the overageing with softening were observed concurrently at the grain boundaries and within grains. By ageing at 400℃, the hardening was attributed to the formation of the AuCu I type ordered phase from the a phase, the overageing with softening was due to the growth of the grain boundary precipitates of the lamellar structure composed of the Ag-rich α₁and AuCu I type ordered phases into the grain interior.

소아에서의 Nd : YAG Laser를 이용한 치은착색제거술 YAG Laser in children

모경희,박헌동,박종휘,김효석,정현구,설재헌,이병채 조선대학교 구강생물학연구소 2003 口腔生物學硏究 Vol.27 No.1

Melanin is normally found in the skin of all people, and normal pigmentation of the intraoral tissues is a relative frequent finding. Gingival hyperpigmentation may cause esthetic problems and embarrassment, especially in patients with a gummy smile. Melanin pigmentation is related to etiologic factor such as hormon, systemic factor, drug, smoking and gingival inflamation. Depigmentation procedure can be Performed by gingival epithelium removing procedure, gingivectomy, free gingival graft, laser therapy, dry ice, Vitamin C and phenol-alcohol method. We could obtain favorable esthetic results by procedures such as Nd: YAG laser. The Nd:YAG laser was set at 4 watt, 50mJ, 80 pulse per second. The procedures were performed with contact mode in all pigmented areas by using a handpiece with a 320㎛ diameter fiber optic. Ablation of the gingival hyperpigmented gingiva appeared healthy, pink, and firm. No recurrence of hyperpigmentation had been found in 6 months of follow-up.

Recent advances in topical anesthesia

Lee, Hyo-Seol The Korean Dental Society of Anesthsiology 2016 Journal of Dental Anesthesia and Pain Medicine Vol.16 No.4

Topical anesthetics act on the peripheral nerves and reduce the sensation of pain at the site of application. In dentistry, they are used to control local pain caused by needling, placement of orthodontic bands, the vomiting reflex, oral mucositis, and rubber-dam clamp placement. Traditional topical anesthetics contain lidocaine or benzocaine as active ingredients and are used in the form of solutions, creams, gels, and sprays. Eutectic mixtures of local anesthesia cream, a mixture of various topical anesthetics, has been reported to be more potent than other anesthetics. Recently, new products with modified ingredients and application methods have been introduced into the market. These products may be used for mild pain during periodontal treatment, such as scaling. Dentists should be aware that topical anesthetics, although rare, might induce allergic reactions or side effects as a result of an overdose. Topical anesthetics are useful aids during dental treatment, as they reduce dental phobia, especially in children, by mitigating discomfort and pain.

The Mobile Oral Health Survey of the Disabled in Facilities in Seoul

Hyo-Seol Lee,Hye-Jung Kim,Sun-Hei Nam,Min-Sun Kim,Hye-Sun You Asia association of Disability and Oral health 2012 대한장애인치과학회지 Vol.8 No.1

Synthesis and Characterization of Silicon/Reduced Graphene Oxide Composites as Anodes for Lithium Secondary Batteries

Lee, Sang-Hoon,Kim, Yong-Jae,Nam, Ye-Seol,Park, Seong-Hyo,Lee, Hochun,Hyun, Yura,Lee, Chang-Seop American Scientific Publishers 2018 Journal of Nanoscience and Nanotechnology Vol.18 No.7

<P>Silicon (Si) is one of the most attractive anode materials for lithium secondary batteries because of its large theoretical capacity, high safety, low cost and environmental benignity. However, Si-based anode material needs to overcome the structural change of the solid-electrolyte interphase due to the large volume change during cycling. To resolve these problems of composites by exploiting the superior conductivity, large specific surface area and flexibility of graphene, we have synthesized reduced graphene oxide (rGO)/Si composite electrode via a simple dip-coating method. Nickel foam is used as a current collector and template for the electrode fabrication. At 0.03 wt%, Si concentration, the rGO/Si composite anode presented the excellent cycle performance with large reversible capacity (778 mAh g(-1) after 100 cycles). The characteristics of the rGO/Si composites were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman and X-ray photoelectron spectroscopy (XPS). The improved anode performance of the rGO/Si composite anode is ascribed to the rGO serving as a buffer layer, thereby preventing the volume expansion of Si nanoparticles, and provide facile electron pathways.</P>

Prediction of Residual Axillary Nodal Metastasis Following Neoadjuvant Chemotherapy for Breast Cancer: Radiomics Analysis Based on Chest Computed Tomography

Lee Hyo-jae,Nguyen Anh-Tien,Song Myung Won,Lee Jong Eun,Park Seol Bin,Jeong Won Gi,박민호,Lee Ji Shin,Park Ilwoo,임효순 대한영상의학회 2023 Korean Journal of Radiology Vol.24 No.6

Objective: To evaluate the diagnostic performance of chest computed tomography (CT)-based qualitative and radiomics models for predicting residual axillary nodal metastasis after neoadjuvant chemotherapy (NAC) for patients with clinically node-positive breast cancer. Materials and Methods: This retrospective study included 226 women (mean age, 51.4 years) with clinically node-positive breast cancer treated with NAC followed by surgery between January 2015 and July 2021. Patients were randomly divided into the training and test sets (4:1 ratio). The following predictive models were built: a qualitative CT feature model using logistic regression based on qualitative imaging features of axillary nodes from the pooled data obtained using the visual interpretations of three radiologists; three radiomics models using radiomics features from three (intranodal, perinodal, and combined) different regions of interest (ROIs) delineated on pre-NAC CT and post-NAC CT using a gradient-boosting classifier; and fusion models integrating clinicopathologic factors with the qualitative CT feature model (referred to as clinical-qualitative CT feature models) or with the combined ROI radiomics model (referred to as clinical-radiomics models). The area under the curve (AUC) was used to assess and compare the model performance. Results: Clinical N stage, biological subtype, and primary tumor response indicated by imaging were associated with residual nodal metastasis during the multivariable analysis (all P < 0.05). The AUCs of the qualitative CT feature model and radiomics models (intranodal, perinodal, and combined ROI models) according to post-NAC CT were 0.642, 0.812, 0.762, and 0.832, respectively. The AUCs of the clinical-qualitative CT feature model and clinical-radiomics model according to post-NAC CT were 0.740 and 0.866, respectively. Conclusion: CT-based predictive models showed good diagnostic performance for predicting residual nodal metastasis after NAC. Quantitative radiomics analysis may provide a higher level of performance than qualitative CT features models. Larger multicenter studies should be conducted to confirm their performance.

장애인전문치과와 일반치과 의료진들의 장애인에 대한 태도 비교

이효설(Hyo-Seol Lee),김영재(Young-Jae Kim),이제호(Jae-Ho Lee) Asia association of Disability and Oral health 2013 International Journal of Disability and Oral Healt Vol.9 No.2

The aim of this research is to compare the attitude toward the special needs of dental staffs between the special dental clinic (SDC) and the general dental clinic (GDC). Surveys were done on 21 dental staffs (7 dentists and 14 dental hygienists) of SDC and 47 dental staffs (10 dentists and 37 dental hygienists) of GDC. Attitudes were rated on a questionnaire with the five-point Likert scale. Mann-Whitney test was utilized for statistical analysis. In SDC, more female dentists and dental staffs who have relatives with disability were working. Dental staffs of SDC showed that the more experience they had, the more positive attitudes toward the communication with the patients with special needs (p<0.05). Dental staffs of SDC represented more active attitudes toward the oral health promotion, treatment, research and volunteering (p<0.05). In conclusion, dental staffs who have personal motivation were working in SDC and the experience of dental treatment to the patients with special needs influenced the dental staffs` attitudes toward them. In future, a research about the attitude toward the disabled with more exact scale should be followed.