• Restorative Dentistry and Endodontics
• /
• v.31 no.6
• /
• pp.452-459
• /
• 2006

Competition will usually develop between the opposing walls as the restorative resin shrinks during polymerization. Magnitude of this phenomenon may be depended upon cavity configuration and volume. The purpose of this sturdy was to evaluate the effect of cavity configuration and volume on microleakage of composite resin restoration that has margins on the enamel site only. The labial enamel of forty bovine teeth was ground using a model trimmer to expose a flat enamel surface. Four groups with cylindrical cavities were defined, according to volume and configuration factor(Depth x Diameter / C-factor) - Group I : 1.5 mm ${\times}$ 2.0 mm / 4.0, Group II : 1.5 mm ${\times}$ 6.0 mm / 2.0, Group III : 2.Omm ${\times}$ 1.72 mm / 5.62, Group IV : 2.0 mm ${\times}$ 5.23 mm / 2.54. After treating with fifth-generation one-bottle adhesive - BC Plus$^{TM}$ (Vericom, AnYang, Korea), cavities were bulk flted with microhybrid composite resin - Denfill$^{TM}$ (Vericom). Teeth were stored in distilled water for one day at room temperature and were finished and polished with Sof-Lex system. Specimens were thermocycled 500 times between 5$^{\circ}$C and 55$^{\circ}$C for 30 second at each temperature. Teeth were isolated with two layers of nail varnish except the restoration surface and 1 mm surrounding margins. Electrical conductivity (${\mu}$A) was recorded in distilled water by electrochemical method. Microleakage scores were compared and analyzed using two-way ANOVA at 95% level. The results were as follows: 1. Small cavity volume showed lower microleakage score than large one, however, there was no statistically significant difference. 2. There was no relationship between cavity configuration and microleakage. Factors of cavity configuration and volume did not affect on microleakage of resin restorations with enamel margins only.

• Restorative Dentistry and Endodontics
• /
• v.24 no.4
• /
• pp.560-569
• /
• 1999

Blood supply rather than nerve supply implies pulp vitality. To evaluate pulp vitality clinically, electric pulp test and thermal test which are based on sensory nerve response have been used in addition to many auxiliary data such as past dental history, visual inspection, radiographic examination, percussion, palpation and transillumination test. However, reactivity of the nerves to the stimulation is not synonymous with normalcy. Therefore measurement of pulpal blood flow using a laser Doppler flowmeter became a new trial to test the pulp vitality. The purpose of the present study was to evaluate normal pulpal blood flow level of maxillary teeth in adult to provide a guideline in determining the vitality of dental pulp. Pulpal blood flow was measured in maxillary central and lateral incisors, canines, first and second premolars and first molars of seventy nine adults of 22 - 30 years old using a laser Doppler flowmeter (PeriFlux 4001, Perimed Co., Stockholm, Sweden, 780 nm infrared laser, 1mW). For directly-made splints, silicone rubber impressions were taken directly from the mouth. For indirectly-made splints, alginate impressions were taken from the mouth and stone cast were made. After making depressions on the buccal surfaces of the cast teeth to indicate the hole positions, second impressions with vinyl polysyloxane putty were taken from the cast. Holes for the laser probes were made at the putty impressions 4mm above the gingival level. Laser probe (PF416 dental probe, 1.5mm) was inserted in the prepared hole and the splint was set in the mouth. After 10 minutes of patient relaxing, pulpal blood flow was recorded for 5 minutes on each tooth. The recorded flow was saved in the computer and calculated with a software 'Perisoft' version 5.1. Pulpal blood flow was also recorded in six teeth of five individuals with no response to electric pulp test and cold test, with periapical radiolucency, or with history of root canal treatment to compare with nonvital teeth. The difference between the mean flow values of each group of teeth were analyzed using one-way ANOVA and Duncan's Multiple Range test. The results were as follows: 1. The average pulpal blood flow values of all the tested teeth of each location were between 9 - 16 Perfusion Unit. Pulpal blood flow value was highest in maxillary lateral incisors, followed by first premolars, second premolars, canines, central incisors, and then first molars (p<0.01). 2. In six anterior teeth, indirectly-made splint group showed higher pulpal blood flow values than directly-made splint group (p<0.01). In posterior teeth, however, there was no significant flow value difference between directly-made splint group and indirectly-made splint one (p>0.05). 3. Teeth with vital pulps showed higher signal values than teeth with nonvital pulps (p<0.01), and the flow photographs showed heartbeat-synchronous fluctuations and vasomotions, while those were absent in non vital tooth.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.27 no.4
• /
• pp.505-516
• /
• 2000

Chloral hydrate is one of the most widely used sedative agents to control the difficult-to-treat young age group in the dental clinic. We are often frustrated to see the patient still awake and cry with agitation even after far more than the normal onset time of Chloral hydrate. In such a case, the patient has to be rescheduled for another sedation visit with different agents and/or routes which greatly disappoints the guardians. This study was designed to test the efficacy of one sedative regimen that can possibly help the clinician complete scheduled treatment without postponement. We have tried sleep induction with mixed gas of Enflurane(2vol%) and $N_2O(50%)-O_2(50%)$ for $60\sim120$ seconds to 35 patients of those who failed to respond properly to the dose(70mg/kg)of oral Chloral hydrate. The Result of this regimen was compare to those of two oral regimen of Chloral hydrate/Hydroxyzine and Chloral hydrate only Analyses of result on vital signs and behavior pattern were performed. The outcome of the study suggest that sleep induction by a short inhalation of low dose of $Enflurane/N_2O-O_2$ provide dentist with suitable condition for the completion of scheduled treatment in the patient who failed to oral Chloral hydrate. Evidence of adverse effect was not detected or reported during and/or after the procedures.

• Tuberculosis and Respiratory Diseases
• /
• v.45 no.1
• /
• pp.68-76
• /
• 1998

Background: Patients with centrally recurred bronchogenic carcinoma make a complaint of many symptoms like hemoptysis, cough & dyspnea. At these conditions, the goal of treatment is only to relieve their symptoms. High dose rate brachytherapy(HDR-BT) is the palliative treatment modality of centrally located endobronchial tumor regardless of previous external irradiation(XRT) on the same site in symptomatic patients. Methods: We studied the effects of HDR-BT in 26 patients with symptomatic recurrent lung cancer. Patients(male: 24, mean age: 54yrs)were treated with HDR-BT underwent bronchoscopic placement of $^{192}Ir$ HDR after loading unit(Gammamed$^{(T)}$, Germany) to deliver 500cGY intraluminal irradiation at a depth of 1cm every lwk on 3 occasions. Evaluation at base line and 4wks after HDR brachytherapy included chest X-ray, bronchscopy, symptoms (Standadized Scale for dyspnea,cough,hemoptysis), and Karnofsky performance scale. Results: Endobronchial obstruction was improved in 11/26 patients(37%). Atelectasis in chest X-ray was improved in 5/15 patients(33%). Hemoptysis, dyspnea & cough were improved in 5/10 patients (50%), 5/8 patients (62%) & 10/18 patients (56%) respectively. Karnofsky performance status was changed from 76.4 scores in pretreatment to 77.6 scores after treatment. During HDR-BT, massive hemoptysis (2 patients) and pneumothorax(1 patient) were occurred as complications. Conclusion: We concluded that HDR-BT gave additional benefits for the control of symptoms and general performance and endobronchial obstruction & atelectasis. And HDR-BT will be an additional treatment for the recurrent and endobronchial obstructive lung cancer.

• Proceedings of the KSCN Conference
• /
• 2003.11a
• /
• pp.1058-1059
• /
• 2003

학동기(만 6-12세)에 좋은 영양 공급은 일생의 성장 발육의 기초를 조성하여 지적, 사회적, 정서적 능력을 향상시킬 수 있다. 이에 초등학생의 영양문제와 식습관을 해결하는 방안의 하나로 최근 대두되고 있는 아침결식률을 낮추기 위한 ‘아침 안 거르기’ 사업을 학교와 연계 개발하여 프로그램을 진행하고 그 효과를 평가하였다. 이 연구는 서울시 강북구 관내에 위치한 4개 초등학교 5학년 학생 1026명(실험군 451명, 대조군 675명)을 대상으로 4∼9월까지 6개월간 5단계로 실시되었다. 프로그램의 효과평가를 위해 사전(실험군-학생 428명, 부모 416명, 대조군-학생 656명, 부모 589명), 사후(실험군-학생 427명, 부모 368명, 대조군-학생 608명, 부모 558명) 설문조사를 2회 실시하여 행동과 인식률 변화를 측정하였다. 프로그램은 매월 1회 담임교사가 진행하였고, 교육자료 및 홍보물은 아침먹기 캐릭터 가방걸이와 학부모의 참여를 높이고자 가정통신문과 교육내용을 함께 삽입하여 제작한 알림장, 아침먹기와 일찍자기를 실천할 실천스티커를 배포하였고 프로그램 종료 후 아침 먹기 실천달력을 제공하였다. 또 아동들 자신의 식생활을 바르게 꾸려 나갈 수 있도록 가공식품의 ‘영양표시’에 관한 교육을 함께 교육하였고, 설문조사를 통해 영양표시제에 관한 인식변화와 행동변화율을 측정하였다. 학생들의 아침식사 실천율은 매일 먹는 그룹이 실험군은 62.9%에서 69.6%로 7% 상승하였고, 전혀 먹지 않는 그룹은 11.2%에서 6.4%로 4.8% 감소하였다(p<0.001) 대조군의 경우 매일 먹는 그룹은 70.4%에서 70.2%로, 전혀 먹지 않는 그룹은 6.9%에서 6.5%로 나타났다(p<0.001). 아침식사가 건강에 미치는 영향에 대한 인식률 변화는 큰 영향이 있다고 답한 그룹이 실험군은 60.1%에서 64.8% (p<0.001)로, 대조군은 64.8%에서 57.2% (p<0.001)로 각각 변화하였다. 일찍 자기가 건강에 미치는 영향에 대한 인식률은 큰 영향이 있다고 답한 그룹이 실험군은 52.5%에서 70.7%(p<0.001), 대조군은 55.3%에서 60.2%로(p<0.001), 일찍 자기 실천에 대한 의지 변화는 11시 이전에 잘 계획이라는 그룹이 실험군은 31.9%에서 43.9%(p<0.001), 대조군은 35.5%에서 36.8%로 나타났다(p<0.001). 영양 표시에 관한 문항에서는 식품구매시 영양표시를 보고 구매한 경험이 없다는 군이 실험군에서는 58.2%에서 40.4%로 감소하였고(p<0.001), 대조군은 64%에서 53.6% (P<0.001)로 감소하였다. 영양소에 관한 지식 평가에서 짜지 않은 간식을 선택할 때 유의할 성분을 나트륨이라고 답한 그룹은 실험군은 31.7%에서 56.3%로, 대조군은 15.9%에서 23.0%로 나타나 그룹간 큰 차이를 보였다. 아침식사로 좋아하는 음식은 김치, 김치찌개, 밥, 피자, 고기, 빵, 된장찌개, 김, 햄, 계란후라이 순이었으며 싫어하는 아침음식은 피망, 고추, 양파, 김치, 시금치, 마늘, 콩, 파, 피자, 나물순으로 나타났다. 아침식사로 혼자서도 준비할 수 있는 음식은 밥, 라면, 계란후라이, 김치, 반찬, 볶음밥, 계란, 국, 햄, 씨리얼 순으로 나타났다. 부모의 인식률 변화는 가정내에 컴퓨터 설치장소로 적합하다고 생각되는 장소로 실험군의 경우 학생 방은 28.0%에서 21.6%로 6.4%감소하였고, 마루나 거실은 61.3%에서 66.0%로 5%증가하였다(p<0.001). 반면 대조군의 경우 학생 방은 28.8%에서 24.9%로 3.9% 감소, 마루나 거실은 63.4%에서 65.9%로 2.5%증가하여 실험군과 큰 차이를 보였다(p<0.001) 자녀의 늦은 취침시간과 아침식사에 관한 인식률 변화는 아침식사에 영향이 있다는 군은 실험군의 경우 78.1%에서 82.7%로 4.2% 증가하였고(p<0.05), 대조군의 경우 82.2%에서 80.5%로 감소하여 나타났다.(P<0.001) 연구결과 실험군의 경우 일주일 동안 아침을 전혀 먹지 않는 학생이 감소하고 매일 아침을 먹는 학생이 유의적으로 증가하여 아동의 아침식사 행동변화와 인식률 변화에 도움이 된 것으로 나타났다.

• Progress in Medical Physics
• /
• v.3 no.2
• /
• pp.1-12
• /
• 1992

For intraoperative radiation therapy using electron beams, a cone system to deliver a large dose to the tumor during surgical operation and to save the surrounding normal tissue should be developed and dosimetry for the cone system is necessary to find proper X-ray collimator setting as well as to get useful data for clinical use. We developed a docking type of a cone system consisting of two parts made of aluminum: holder and cone. The cones which range from 4cm to 9cm with 1cm step at 100cm SSD of photon beam are 28cm long circular tubular cylinders. The system has two 26cm long holders: one for the cones larger than or equal to 7cm diamter and another for the smaller ones than 7cm. On the side of the holder is an aperture for insertion of a lamp and mirror to observe treatment field. Depth dose curve. dose profile and output factor at dept of dose maximum. and dose distribution in water for each cone size were measured with a p-type silicone detector controlled by a linear scanner for several extra opening of X-ray collimators. For a combination of electron energy and cone size, the opening of the X-ray collimator was caused to the surface dose, depths of dose maximum and 80%, dose profile and output factor. The variation of the output factor was the most remarkable. The output factors of 9MeV electron, as an example, range from 0.637 to 1.549. The opening of X-ray collimators would cause the quantity of scattered electrons coming to the IORT cone system. which in turn would change the dose distribution as well as the output factor. Dosimetry for an IORT cone system is inevitable to minimize uncertainty in the clinical use.

• Progress in Medical Physics
• /
• v.17 no.1
• /
• pp.1-5
• /
• 2006

A parallel plate detector containing PTFE films in FEP film for relative dosimetry was designed to measure the response of detectors to S and 10 MV X-rays from a medical linear accelerator through different thicknesses of lead. The dielectric materials were 100 m thick. The set-up conditions for measurements with this detector were as follows: SSD=100 cm the test detector was at a depth of 5 cm and the reference chamber was at a depth of 10 cm from the phantom surface for 6 and 10 MV X-rays. Lead blocks were designed to cover the irradiated field. They were added to the tray to increase thickness sequentially. We found that the detector response decreased exponentially with the thickness of lead added. The linear attenuation coefficients of the test detector and reference chamber were 0.1414 and 0.541, respectively, for 6 MV X-rays and 0.1358 and 0.5279 for 10 MV X-rays. The test detector response was greater than that of the reference chamber. The response function was calculated from the measured values of the test detector and reference chamber using optimization. These optimized constants for the detector response function were independent of theenergy. As a result of optimizing the response function between detectors, the use of a relative dosimeter was validated, because the response of the test detector was 1% for 6 MV X-rays and 4% for 10 MV X-rays.

• Progress in Medical Physics
• /
• v.23 no.4
• /
• pp.269-278
• /
• 2012

Aquaplast Thermoplastic (AT) is a tissue-equivalent oral compensator that has been developed to improve dose uniformity at the common boundary and around the treated area during radiotherapy in patients with head and neck cancer. In order to assess the usefulness of AT, the degree of improvement in dose distribution and physical properties were compared to those of oral compensators made using paraffin, alginate, and putty, which are materials conventionally used in dental imprinting. To assess the physical properties, strength evaluations (compression and drop evaluations) and natural deformation evaluations (volume change over time) were performed; a Gafchromic EBT2 film and a glass dosimeter inserted into a developed phantom for dose verification were used to measure the common boundary dose and the beam profile to assess the dose delivery. When the natural deformation of the oral compensators was assessed over a two-month period, alginate exhibited a maximum of 80% change in volume from moisture evaporation, while the remaining tissue-equivalent properties, including those of AT, showed a change in volume that was less than 3%. In a free-fall test at a height of 1.5 m (repeated 5 times as a strength evaluation), paraffin was easily damaged by the impact, but AT exhibited no damage from the fall. In compressive strength testing, AT was not destroyed even at 8 times the force needed for paraffin. In dose verification using a glass dosimeter, the results showed that in a single test, the tissue-equivalent (about 80 Hounsfield Units [HU]) AT delivered about 4.9% lower surface dose in terms of delivery of an output coefficient (monitor unit), which was 4% lower than putty and exhibited a value of about 1,000 HU or higher during a dose delivery of the same formulation. In addition, when the incident direction of the beam was used as a reference, the uniformity of the dose, as assessed from the beam profile at the boundary after passing through the oral compensators, was 11.41, 3.98, and 4.30 for air, AT, and putty, respectively. The AT oral compensator had a higher strength and lower probability of material transformation than the oral compensators conventionally used as a tissue-equivalent material, and a uniform dose distribution was successfully formed at the boundary and surrounding area including the mouth. It was also possible to deliver a uniformly formulated dose and reduce the skin dose delivery.

• Progress in Medical Physics
• /
• v.23 no.4
• /
• pp.279-284
• /
• 2012

The X ray has been widely used in both diagnosis and treatment. Recently, a miniature X ray tube has been developed for radiotherapy. The miniature X ray tube is directly inserted into the body irradiated, so that X rays can be guided to a target at various incident angles according to collimator geometry and, thus, minimize patient dose. If such features of the miniature X ray tube can be applied to development of X ray imaging as well as radiation treatment, it is expected to open a new chapter in the field of diagnostic X ray. However, the miniature X ray tube requires an added filter and a collimator for diagnostic purpose because it was designed for radiotherapy. Therefore, a collimator and an added filter were manufactured for the miniature X ray tube, and mounted on. In this study, we evaluated beam characteristics of the miniature X ray tube for diagnostic X ray system and accuracy of measuring the HVL. We used the Si PIN Photodiode type Piranha detector (Piranha, RTI, Sweden) and estimated the HVL of the miniature X ray tube with added filter and without added filter. Through an another measurement using Al filter, we evaluated the accuracy of the HVL obtained from a direct measurement using the automatic HVL calculation function provided by the Piranha detector. As a result, the HVL of the miniature X ray tube was increased around 1.9 times with the added filter mounted on. So we demonstrated that the HVL was suitable for diagnostic X ray system. In the case that the added filter was not mounted on, the HVL obtained from use of the automatic HVL calculation function provided by Piranha detector was 50% higher than the HVL estimated using Al filter. Therefore, the HVL automatic measurement from the Piranha detector cannot be used for the HVL calculation. However, when the added filter was mounted on, the HVL automatic measurement value using the Piranha detector was approximately 15% lower than the estimated value using Al filter. It implies that the HVL automatic measurement can be used to estimate the HVL of the miniature X ray tube with the added filter mounted on without a more complicated measurement method using Al filter. It is expected that the automatic HVL measurement provided by the Piranha detector enables to make kV-X ray characterization easier.

• Clean Technology
• /
• v.24 no.1
• /
• pp.77-84
• /
• 2018

In this study, $Li_4Ti_5O_{12}$ anode materials for lithium ion battery were synthesized by dry ball-mill method. Polyvinyl chloride (PVC) as a carbon source was added to improve electrochemical properties. When the PVC was added after $Li_4Ti_5O_{12}$ formation, the spinel structure was well synthesized and it was confirmed by X-ray diffraction (XRD) experiments. When the carbon material was added before the synthesis and the heat treatment was performed, it was confirmed that a material having a different crystal structure was synthesized even when a small amount of carbon material was added. In the case of $Li_4Ti_5O_{12}$ without the carbon material, the electrical conductivity value was about $10{\mu}S\;m^{-1}$, which was very small and similar to that of the nonconductor. As the carbon was added, the electrical conductivity was greatly improved and increased up to 10,000 times. Electrochemical impedance spectroscopy (EIS) analysis showed that the size of semicircle corresponding to the resistance decreased with the carbon addition. This indicates that the resistance inside the electrode is reduced. According to the Cyclic voltammetry (CV) analysis, the potential difference between the oxidation peak and the reduction peak was reduced with carbon addition. This means that the rate of lithium ion insertion and deinsertion was increased. $Li_4Ti_5O_{12}$ with 9.5 wt% PVC added sample showed the best properties in rate capabilities of $180mA\;h\;g^{-1}$ at 0.2 C-rate, $165mA\;h\;g^{-1}$ at 0.5 C-rate, and $95.8mA\;h\;g^{-1}$ at 5 C-rate.