Rheological characterization of thermoplasticized injectable gutta percha and resilon

장주혜,백승호,이인복 大韓齒科保存學會 2011 Restorative Dentistry & Endodontics Vol.36 No.5

연구목적: 본 연구의 목적은 열연화주입형 gutta percha와 resilon의 온도 변화에 따른 점탄성 변화를 관찰하고 조작성을 비교하기 위함이다. 연구 재료 및 방법: Obtura-II 시스템을 이용하여 세 종류의 gutta percha와 resilon을 와 로 가열한 후 사출 온도를 측정하였다. 점도계를 이용하여 온도 변화에 따른 재료들의 점탄성 특성(전단탄성계수, G'; 전단점성계수, G"; 손실 탄젠트, tan; 복소점도, )을 관찰하였다. 점도계와 차동주사열측정기(DSC)로 재료들의 상전이 온도를 측정하였고 가압법으로 와 에서 재료들의 점조도를 비교하였다. 결과: 세 종의 gutta perchas는 온도에 따라 서로 다른 점탄성 특성을 나타냈다. 에서 연화된 재료의 고체화 상변이가 일어났고, 점도계와 DSC로 측정된 상변이 시작 온도는 유사하였다. 상변이 시작 온도와 가압 시 점조도는 재료들마다 차이를 보였다(p < 0.05). Resilon은 gutta percha와 비슷한 유변학적 특성을 보였다. 결론: 열연화된 근관충전재는 냉각과정 동안 유변학적 특성의 변화를 나타냈고 재료들마다 서로 다른 점탄성 특성은 근관 내주입 시와 충전 시 서로 다른 조작성을 보임을 알 수 있다. Objectives: The purpose of this study was to observe the change in the viscoelastic properties of thermoplasticized injectable root canal filling materials as a function of temperature and to compare the handling characteristics of these materials. Materials and Methods: Three commercial gutta perchas and Resilon (Pentron Clinical Technologies) in a pellet form were heated in the Obtura-II system (Obtura Spartan) at and , and the extrusion temperature of the thermoplasticized materials was measured. The viscoelastic properties of the materials as a function of temperature were evaluated using a rheometer. The elastic modulus G', viscous modulus G", loss tangent tan, and complex viscosity were determined. The phase transition temperature was determined by both the rheometer and a differential scanning calorimeter (DSC). The consistency of the materials was compared under compacting pressure at and by a squeeze test. Results: The three gutta perchas had dissimilar profiles in viscoelastic properties with varying temperature. The phase transition of softened materials into solidification occurred at to , and the onset temperatures obtained by a rheometer and a DSC were similar to each other. The onset temperature of phase transition and the consistency upon compaction pressure were different among the materials (p < 0.05). Resilon had a rheologically similar pattern to the gutta perchas, and was featured between high and low-flow gutta perchas. Conclusions: The rheological characteristics of the thermoplasticized root canal filling materials changed under a cooling process. The dissimilar viscoelastic properties among the materials require different handling characteristics during an injecting and compacting procedure.

[치료영역별 진료 지침] 근관치료 및 치료 후 수복

장주혜 Asia association of Disability and Oral health 2012 International Journal of Disability and Oral Healt Vol.8 No.2

QUANTITATIVE COMPARISON OF PERMEABILITY IN THE ADHESIVE INTERFACE OF FOUR ADHESIVE SYSTEMS

장주혜,이기욱,김혜영,이인복,조병훈,손호현 대한치과보존학회 2009 Restorative Dentistry & Endodontics Vol.34 No.1

본 연구는 현재 시판 되고 있는 여러 개의 상아질 접착제를 임상 술식에서와 같은 방법으로 사용한 다음 열순환 후 접착계면의 변화를 관찰 비교하고자 했다. 발거 한 지 한 달 이내인 대구치 28개의 교합 면 상아질 표면에 4종의 상아질 접착제 (OptiBond FL [OP], AdheSE [AD], Clearfil SE Bond [CL], Xeno Ⅲ [KE] 중 하나를 적용한 뒤 복합 레진 (Premisa, Kerr)을 1mm두께로 올린 후 광중합 하였다. 4℃ 증류수에서 6일간 보관한 뒤 치아의 정중선으로부터 수직으로 절단하여 그 중 절반의 치아에서 2mm 두께의 시편을 얻은 다음 남은 반쪽의 치아는 10.000회의 열순환을 가한 뒤 (5˚-55˚, 침지 시간 25초 대기 시간 5초) 같은 방법으로 2 mm 두께의 시편을 얻었다. 연마한 시편을 24시간 동안 50% ammoniacal silver nitrate solution에 담근 다응 photo-developing solution에서 8시간 동안 환원시켰다. 계면을 가로지르는 5개의 line 상에서 wavelength dispersive spectrometry (WDS) detector를 이용하여 주사선상에 있는 원소들의 중량비를 계산하였다 또한 열순환 전과 후의 시편에서 얻어진 5개의 silver 측정치를 서로 비교하였다. 열순환 전의 접착제층(adhesive layer)에서는 OP에서 가장 적은 silver의 투과가 관찰되었으며 (P<0.0001), CL. AD, XE 순으로 투과 량이 중가함을 보였다. 혼성층 (Hybrid layer) 에서는 CL의 투과량이 가장 적었다 (p=0.0039) 열순환 후에 접착제층과 혼성층에서 silver의 투과량은 증가하지는 않았다. Scanning electron microscopy(SEM) 사진을 통하여 각 시편의 접착 계면에서 접착제에 따른 특이적인 silver의 투과상을 관찰할 수 있었다. 전반적으로 OP와 CL의 접착계면이 열순환 과정 중에도 온전히 유지됨을 볼 수 있었다. 접착 계면에서의 수분 투과 양상은 각 접착제예 따라 다른 형태를 보였으며 열 순환에 의해 유의할 만한 변화를 야기하지는 않았다. The purpose of this study was to perform quantitative comparisons of water permeable zones in both the adhesive and the hybrid layer before and after thermocycling in order to assess the integrity of the bonding interface. Twenty eight flat dentin surfaces were bonded with a light-cured composite resin using one of four commercial adhesives [OptiBond FL (OP), AdheSE (AD), Clearfil SE Bond (CL), and Xeno Ⅲ (XE)]. These were sectioned into halves and subsequently cut to yield 2-mm thick specimens: one specimen for control and the other subjected to thermocycling for 10,000 cycles. After specimens were immersed in ammoniacal silver nitrate for 24 h and exposed to a photo developing solution for 8 h. the bonded interface was analyzed by scanning election microscopy (SEM) and wavelength dispersive spectrometry (WDS) at five locations per specimen Immediately after bonding thc adhesive layer of OP showed the lowest silver uptake followed by CL, AD, and XE in ascending order (p< 0.0001) the hybrid layer of CL had the lowest silver content among the groups (p=0.0039) After thermocycling none of the adhesives manifested a significant increase of silver in either the adhesive or the hybrid layer. SEM demonstrated the characteristic silver penetrated patterns within the interface. It was observed that integrity of bonding was well maintained in OP and CL throughout the thermocycling process. Adhesive-tooth interfaces are vulnrable to hydrolytic degradation and its permeability varies in different adhesive systems, which may be clinically related to the restoration longevity.

Stator-Rotor gap을 통한 냉각유동이 터빈 유동손실에 미치는 영향에 대한 CFD 연구

장주혜(Juhye Jang),주원구(Wongu-Joo) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.12

To improve the efficiency, turbine inlet temperature has been raised and the temperature exceeds melting points of materials constituting turbine. To protect disk cavities from hot gases, purge flows are injected into mainstream through rim seals. The interaction between purge flows and mainstream induces aerodynamic losses and decrease of efficiency, so proper rim seal geometry is essential. Using CFD numerical analysis, this paper aims to understand the effect of cooling flow on the endwall flow and turbine loss with alteration of distances between rim seal plates and mass flow rate of cooling air. The result of numerical analysis showed that there was a difference in the degree of reverse flow of the interface according to alteration of rim seal geometries. It is found that the rim seal geometry with narrow upper gap and wide lower gap showed the smallest aerodynamic loss.

중증 지적 장애인을 위한 효과적인 치과치료

장주혜(Juhea Chang) 대한치과의사협회 2011 대한치과의사협회지 Vol.49 No.12

Patients with severe mental challenges are often subjected to extensive dental problems. Their impaired communication and lack of cooperation unable to receive timely dental treatments, which deteriorates their adverse oral conditions. In spite of a limited time frame, well-planned comprehensive treatments can be delivered in an one-day operation setting under general anesthesia. This ultidisciplinary treatment regimen primarily comprises of single-visit endodontics, direct bonded restoration, periodontal treatment, and surgical extraction. Further, one or two additional visits for prosthetic procedures are able to accomplish functional reestablishment and esthetic enhancement. This article discusses on clinical managements for severely mentally challenged patients under a single-day operation.

전신 마취 하 장애인 치과치료에 대한 임상적 고찰

장주혜(Juhea Chang) Asia association of Disability and Oral health 2014 International Journal of Disability and Oral Healt Vol.10 No.2

The aim of this study was to analyze the clinical characteristics of patients with cognitive and behavioral impairments receiving dental treatment under general anesthesia (GA-dental treatment). From August 2007 to April 2014, information was collected from 475 patients who received GA-dental treatment at the Clinic for Persons with Disabilities, Seoul National University Dental Hospital. The demographic factors (gender, age, disability, medication, GA history, residency type, caregiver, meal type, oral hygiene maintenance, and cooperation level) and dental status (operating duration, DMFT, malocclusion, periodontal disease, tooth defect, and treatment protocol) of the patients were evaluated. DMFT and malocclusion levels were compared among the patients with ANOVA and Sheffe’s post-hoc test, and chi-square test, respectively. The correlation between the demographic characteristics and dental status of the patients were analyzed with the Pearson’s correction test. The mean age of the patients was 27.1 (7 - 83) years and they had intellectual disabilities (55.4%), developmental disorders (17.9%), brain disorders (16.6%), neurocognitive disorders (4.6%), or others (5.5%). The mean DMFT (DT) was 8.6 (5.2) with a significant difference among the disability types (p<0.05). The incidence of malocclusion was higher in patients with intellectual disabilities and brain disorders than in the other types (p<0.05). The operation time (191.4 ± 91.2 min) was correlated with decayed or endodontically-treated teeth (p<0.05). Special needs patients requiring GA-dental treatment showed unfavorable oral conditions. Dental practitioners experience time restrictions and additional costs under a GA setting. Treatment planning and decision-making can be efficiently facilitated by evaluating the clinical characteristics of the patients.

장애인 구강진료 접근성 제약 - Part 2. 장애인 환자 보호자 측면에서의 고찰

장주혜(Juhea Chang) Asia association of Disability and Oral health 2019 International Journal of Disability and Oral Healt Vol.15 No.1

The aim of this study was to determine the factors contributing to the barrier of dental treatment for special needs patients perceived by the main caregivers of the patients. A questionnaire was developed with three parts: patient-related factors, caregiver-related factors, and factors for treatment barriers. Patient- and caregiver-related factors were analyzed for correlations with the barrier factors. Fisher’s exact test and Chi-square test were used at the level of 0.05. A total of 52 caregivers (mean age [SD]=50.2 [11.5] years) for the patients with intellectual and cognitive disabilities (mean age [SD]=38.9 [21.3]) responded to the questionnaires. Oral hygiene status, need for assistance in tooth brushing, and cooperation for tooth brushing were correlated with the level of treatment cooperation of the patients (p<0.05). The above three factors were also correlated with the treatment barrier despite patients presenting oral symptoms (p<0.05). Two thirds of the caregivers felt the treatment cost as severe or a considerable financial burden. For patients, insurance types and need for assistance in tooth brushing, and for caregivers, education levels and financial status were significant factors contributing to financial burden (p<0.05). There were background factors of the patients and their caregivers associated with access to dental treatment for special needs patients. Deficient cooperative skills and financial burdens were the main obstacles to treatment access. Tooth brushing skills and oral hygiene status can be proxy measures to cooperative ability for dental treatment.

치과적 중증 장애인 환자를 위한 치료 계획 수립

장주혜(Juhea Chang) 대한치과의사협회 2015 대한치과의사협회지 Vol.53 No.11

This article discusses how to conduct treatment planning and decision making in special needs dentistry. Special needs patients often lack cooperative ability during dental treatment and have a deteriorated oral health status. To overcome the limitation in communication with special needs patients and solve their complicated dental problems, dentists need to have extensive preoperative information about the patients and their caregivers. Treatment procedures should be organized in a patient-centered and cost-effective manner. Additionally, clinical outcomes need to be predicted taking into consideration of the patients" condition. The clinical experience of committed dentists is another factor that enhances the benefits of extensive treatment in special needs patients with many limitations. The insightful treatment decision-making of dentists will contribute to improving the oral health of special needs patients despite the various obstacles.

Comparison of the elastic modulus among three dentin adhesives before and after thermocycling

Chang, Juhea,Lee, In Bog,Cho, Byeong Hoon,Kim, Hae-Young,Son, Ho Hyun 大韓齒科保存學會 2008 Restorative Dentistry & Endodontics Vol.33 No.1

본 연구는 현재 시판 되고 있는 여러 개의 상아질 접착제를 임상 술식에서와 같은 방법으로 사용한 후 열 시효처리를 통해 노화 과정을 재현한 다음 접착 계면의 탄성계수를 측정함으로써 가수분해에 따른 물성변화를 관찰 비교하고자 했다. 발거 한 지 2 주일 이내인 영구 대구치 21 개의 상아질 표면이 노출되도록 삭제하였다. 각각 7개의 치아에 시판되고 있는 3가지 상아질 접착제 (OptiBond FL, Clearfil SE, Xeno III)를 적용한 뒤 광중합 복합 레진(Premisa, Kerr, Orange, CA, USA)를 1mm 두께로 쌓아 올렸다. 각 치아를 이등분하여 절반 시편은 100,000회의 열 시효 처리를 가하도록 했다. Nanoindentation test를 통하여 각 시편의 adhesive layer와 hybrid layer의 탄성계수를 측정, 비교하였다. 열시효 처리 후 Xeno III군의 탄성계수가 통계학적으로 유의할 만한 감소를 보였다 (p < 0.05). Hydrophilic monomer를 많이 함유한 one-step self-etch adhesive system은 다른 제품에 비해 가수분해에 취약하여 이에 따른 물성 변화를 보이는 것으로 추정되며, 궁극적으로 수복물의 내구성에 영향을 미칠 것으로 여겨진다. The purpose of this study was to determine the effects on the elastic moduli of the adhesive and the hybrid layer from thermocycling. Twenty one human molars were used to create flat dentin surfaces. Each specimen was bonded with a light-cured composite using one of three commercial adhesives (OptiBond FL [OP), Clearfil SE Bond [CL], and Xeno III [XE]). These were sectioned into two halves and subsequently cut to yield 2-㎜ thickness specimens; one specimen for immediate bonding test without thermocycling and the other subjected to 10,000 times of thermocycling. Nanoindentation test was performed to measure the modulus of elasticity of the adhesive and the hybrid layer, respectively, using an atomic force microscope. After thermocycling, XE showed a significant decrease of the modulus in the adhesive layer (p < 0.05). Adhesives containing hydrophilic monomers are prone to hydrolytic degradation. It may result in the reduced modulus of elasticity, which leads to the mechanically weakened bonding interface.

COMPARISON OF OPERATIVE TECHNIQUES BETWEEN FEMALE AND MALE DENTISTS IN CLASS 2 AND CLASS 5 RESIN COMPOSITE RESTORATIONS

Chang, Juhea,Kim, Hae-Young,Son, Ho-Hyun 大韓齒科保存學會 2010 Restorative Dentistry & Endodontics Vol.35 No.2

This study aimed to assess whether the gender of the dental practitioner affects operative techniques in class 2 and class 5 resin composite restorations. In 2008, a nationwide survey was given to Korean dentists. Total 12,193 e-mails were distributed, 2,632 were opened by recipients, and 840 responses were collected. Of the respondents, 78.9% were male and 21.1% were female. The gender distribution in the age groups between respondents and the total population did not differ (p > 0.05). A chi-square test was used to compare technical differences between female and male dentists. A multiple logistic regression analysis was performed to assess the association between gender and operative techniques in resin composite restoration. For class 2 resin composite restoration, female dentists were 1.87 times more likely than male dentists to do multiple incremental fillings (four layers or more) and 2.72 times more likely than males to spend 30 minutes or more for the treatment (p < 0.05). For class 5 resin composite restoration, female dentists were 2.69 times more likely than their male counterparts to use a cavity base or liner, 1.83 times more likely to do multiple incremental fillings (four layers or more) and 1.63 times more likely to spend 20 minutes or more for the procedure (p < 0.05). The gender factor was influential to individual operative techniques in restorative treatment. 본 연구에서는 복합 레진을 이용한 2급/5급 와동의 직접수복에 있어서 치과의사의 성별에 따른 술식의 차이를 비교하였다. 2008년 대한치과의사협회에 등록된 치과의사 12,193명을 대상으로 이 메일을 통한 설문조사를 실시하였다. 이 메일 수신이 확인된 2,632명 중 840명이 응답하였으며 응답자의 남녀 비율은(남 78.9%, 여 21.1%) 전체 치과의사의 남녀 비율과 유의한 차이를 보이지 않았다(p > 0.05). Chi-square test 와 multiple logistic regression analysis 를 이용하여 남녀간 술식의 차이를 검증하였다. 2급 와동 수복에서 여자치과의사는 4회 이상의 적층 분할 수복을 하는 경향이 남자치과의사에 비해 1.87배 높았으며, 술식 당 30분 이상 소요하는 경향은 2.72배 높았다(p < 0.05). 5급 와동 수복에서 여자치과의사는 베이스를 사용하는 경향이 1.83배 높았으며, 술식 당 20분 이상 소요하는 경향은 1.63배 높았다(p < 0.05). 본 설문조사에 따르면 남녀 성별에 따라 복합 레진 수복 술식의 차이가 존재하는 것으로 나타났다.