• Journal of Technologic Dentistry
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• v.38 no.4
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• pp.263-272
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• 2016

Purpose: The purpose of this study is to measure and compare a degree of setting expansion of dental stone by time depending on the mixing methods and mixing ratios of dental stone, to compare the surface state of each specimen with the use of an optical camera with microscope, and thereby to provide a fundamental material for making dental prostheses. Methods: The test on setting expansion of dental stone is based on ISO 6873. With two different mixing ratios and three kinds of stone mixing methods, test groups were created, and a total of six types of specimens (N=30) were made. Based on the specimens, the setting expansion rate of each one was measured in each time slot of 24 hours, and the surface of the set stone was measured. Results: According to the analysis on setting expansion rate of stone, the setting expansion of the specimen that was created in the way of vacuum mixing at normal mixing ratio was 0.1944% at 120 minutes; the setting expansion of the specimen that was created in the way of vacuum mixing at the mixing ratio which was 40% higher than normal mixing ratio was 0.195% at 120 minutes; the setting expansion of the specimen that was created in the way of mixing with hands at normal mixing ratio and then removing bubbles in vacuum mixer was 0.196% at 120 minutes. Conclusion: The setting expansion rate of each dental stone specimen was significantly different with the lapse of time up to 24 hours(p<.001).

• Journal of Technologic Dentistry
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• v.39 no.4
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• pp.253-259
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• 2017

목적: 이 실험의 목적은 한국 백삼과 캐나다 백삼의 일반 성분 분석, 항산화력 측정 및 치아 우식 유발균에 미치는 항균 효과를 비교 분석하는데 있다. 방법: 한국 백삼과 캐나다 백삼의 일반 성분은 수분정량, 조지방, 조단백질, 그리고 조회분의 분야에서 측정되었다. 두 백삼을 60% 에탄올에 추출시켜 환원당과 DPPH-scavenging assay를 통해 항산화력을 측정했다. 동일 추출물을 이용, 치아 우식균인 streptococcus mutans에 대해 디스크 확산법과 최소저해농도 측정을 실시해 항균력을 측정 및 비교했다. 결과: 실험 결과, 한국 백삼과 캐나다 백삼은 유사한 조지방, 조단백질, 조회분 성분을 갖고 있었으나 수분정량에서 캐나다백삼이 우세했다. 항산화력 실험에서는 캐나다 백삼이 DPPH- scavenging 능력에서 더 높았으나 환원당 실험과 총 페놀 함량에서는 한국 백삼의 수치가 더 높았다. 디스크 확산법을 통한 항균력 실험에서는 한국 백삼이 캐나다 백삼보다 더 넓은 clearing zone을 형성하고 더 낮은 최소저해농도를 달성해 항균력에서 우세했다. 결론: 한국 백삼과 캐나다 백삼은 비슷한 일반성분과 항산화력을 가졌다. 하지만 한국백삼이 치아 우식 유발균인 streptococcus mutans에 대한 항균력에서 더 우세했다.

• Journal of Technologic Dentistry
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• v.19 no.1
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• pp.13-19
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• 1997

The purpose of this study was carried out by oberserving to composition of an oxide on the surface of Dental porcelain alloy according to the conditions of its heat treatment and analysing the change composition on its surface. Morphological change of the heat treated dental porcelain alloy have been investigated with SEM and EDX. The result of this study is summarized ad follows. The surface indium concentration of specimens increased as the heat treatment temperature and the oxygen partial pressure increased.

• Journal of Technologic Dentistry
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• v.26 no.1
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• pp.49-58
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• 2004

Two diketones, 1-phenyl-1,2-propanedione(PD) and 2,3-butanedione (BD) were investigated as new visible light photosensitizers for a dental resin composite of bis-GMA in order to improve photopolymerization effect. And the photopolymerization efficiency of mixed photosensitizers, PD-CQ and DA-CQ, was studied. Photopolymerization effect of photosensitizers were compared with that of camphorquinone(CQ), the most widely used photosensitizer. The photopolymerization efficiency of bis-GMA containing the photosensitizer increased with irradiation time. The increase was in the order: BD < CQ < PD. The photopolymerization efficiency of this mixture was not so efficient as CQ or PD.

• Journal of Korean society of Dental Hygiene
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• v.12 no.3
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• pp.495-501
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• 2012

Objectives : Today, one of the most basically used procedures to dental patients is scaling for removing tartar. The purpose of this study is the effect of Happycaine during scaling for pain relief. Methods : This study was used self-questionnaire from 202 patients. SPSS 18.0 vision program was used for data analysis. Group A was used Happycaine, but group B wasn't used Happycaine. The degree of pain relief depending on use of Happycaine, was analyzed by Independent-two-sample t-test. Emotion and reaction during scaling was analyzed by mean and standard deviation. The results were as follows. Results : 1. 52.5% participants answered 'require scaling' and 12.9% answered 'required scaling very much'. so 65.4% participants recognized the need of scaling. 2. According to the experience of Happycaine during scaling, differences in pain was by Likert 5 pints scale, Group B's pain was higher than Group A's(p=0.000). 3. According to the experience of Happycaine during scaling, the mean of panic from Group B was a little higher than Group A(p=0.036). In case of cold symptom during scaling, Group B was significantly different(p=0.011). In Group B, pain from dental hygienists was significantly different (p=0.000). Group A was interested in Happycaine use in future scaling(p=0.004). Conclusions : As a result of this study, we recommend Happycaine during scaling in order to decrease mental burden and pain for patients.

• Journal of Technologic Dentistry
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• v.21 no.1
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• pp.5-14
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• 1999

Glass ceramics for dental crown prosthesis were prepared by crystallization of CaO-MgO-SiO2-$P_2O_5-TiO_2$ glasses. Their crystallization behaviors have been investigated as a function of heattreatment temperature, holding time and chemical composition in relation to mechinical properties. Crystallization peak temperatures were determined by differential thermal analysis(DTA). Crystalline phases and mircostructures of heat-treated sample were determined by the means of powder X-ray diffraction(XRD) and scanning electron microscopy(SEM). The final crystalline phase assemblages and the microstructures of the samples were found to be dependent on glass compositions, heattreatment temperature, and holding time. 1st crystallization peak temperature(TP), affected strongly by apatite, was found to be increased or decreased. From the experiment, the following results were obtained : 1. The crystallization peak temperature($T_P$) formed by apatite increased until adding up to 9wt% $TiO_2$ to base glass composition, then decreased above that. 2. Apatite($Ca_{10}P_6O_{25}$), whitlockite(${\beta}-3CaO-P_2O_5$), $\beta$-wollastonite($CaSiO_3$), magnesium tianate($MaTiO_3$) and diopside(CaO-MgO-$2SiO_2$) crystal phase were precipitated in MgO-CaO-$SiO_2-TiO_2-P_2O_5$ glass system containing 9wt% and 11wt% of $TiO_2$ 3. Vickers hardness of samples increased with increasing heat-treatment temperature and Vickers hardness of S415T9 samples heat-treated at 1075 was approxi-mately 813Kg $mm^{-2}$ as maximum value. 4. Vickers hardness of samples increased due to precipitation of apatite, whitlockite, $\beta$-wollastonite, magnesium titanate, and diopside crystal phases within glass matrix.

• Journal of Technologic Dentistry
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• v.8 no.1
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• pp.31-36
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• 1986

This treatise suggests the effective method for the dental laboratory technology teaching plan. It will present concrete practical steps for and audio-visual dental laboratory technology education approach. It will also help students to understand the dental laboratory theory and practice learned in the class and make use of it greatly in the field work. As follows: 1. Instructor should teach interestingly basic dental laboratory technology theory with illustrations and figures on the teaching method. 2. In practical traing class, instructor should teach every step, using audio-visual materials such as slides and video tapes/Instructor and his assist and should show an example to the students. 3. Instructor should make a standard and train the studtnes repeatedly until they come up to it. 4. Students should be skilled in every case through field work during their spare time and vacation. 5. Instructor should also teach job moral and manner to the students so that they can be adapted themselves to the social activities and be successful dental laboratory technician after graduation.

• Journal of Technologic Dentistry
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• v.28 no.1
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• pp.9-17
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• 2006

The purpose of this study was to evaluate the titanium castability with a spin type casting machine(TiCast, Super R, Selec, Osaka. Japan). We tested phosphate bonded investment "Rematitan$^{(R)}$Plus(Dentaurum, Inc., Pforzheim, Germany)"of mesh grid pattern and plate pattern. Four different mold temperatures(room temperature, 200$^{\circ}C$, 400$^{\circ}C$ and 600$^{\circ}C$) were prepared for the present study. In mesh grid pattern with spruing of $\varphi$0.88㎜ dimeter, when the mold temperature increased, high percentage of castability was gained. Mold temperature showed a highly significant(p<0.05) correlation on the castability, In plate pattern, the higher the mold temperature during casting, the greater the adhesive phenomenon between Ti surface and the investment.

• Journal of Technologic Dentistry
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• v.25 no.1
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• pp.119-142
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• 2003

In the present work the knowledge of dental health as well as dental prosthesis has been studied on the basis of analysis of current dental prosthetic treatments for dental diseases prophylaxis and the final decision for dental prosthetic appliance. The results have been analyzed by the current dental health care and the subjective acknowledgement from 700 people of urban as well as rural inhabitance in our country. The results from the present work have been summarized as following: Depending dental status has been shown worse to be in the cases of divorce and bereavement, age and less educated or jobless. It is also interesting to note that the dental status has shown to be even worse than health status. It has been shown that the dental prosthetic treatments have been mainly caused by the oral disease (62.2%) and depend on the age and the educational level. According to the actual status of dental prosthetic treatments, the fixed partial denture was the most case (78.9%) that increased as divorced, bereavement and as less educated, less income, retired and jobless as well as from urban to rural. As a clinic for the dental prosthetic treatments, dental clinics have been most frequent visited as indicated by 59.6%, then the un-licensed dentist (6.5%), then the hospitals (3.7%), then the public health centers (2.2%). Most of those who are older in age, less educated and jobless have been treated by the un-licensed dentists. In point of view on the cost for dental prosthetic treatments, 93.1% have claimed to be too expensive, in as the divorced and the bereaved, the older age, the less educated and the jobless. About satisfaction of dental prosthetic treatments, 51.4% was satisfied, 39.4% was normal and 9.2% was dissatisfied. Most of people experienced increasing levels of satisfaction as their income increase. Most in the age range of 40-60 have wanted to be insured for the dental prosthetic treatments. It is also interesting to note that the older age and the less educated wanted to apply this kind of insurance.

• Journal of Technologic Dentistry
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• v.11 no.1
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• pp.5-22
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• 1989

We investigated 974 male and female students who are in 4th, 5th and 6th year of 8 elementary schools are located win Puan-kun, the farm area of Chollabuk-do, and the results are as follows. 1. Visiting dental clinic in order to be treated for dental caries hold the highest rate as 26.1% of male students and 30.3% of female students. 2. On fear when children visit dental clinic, first, 25.6% of male students and 35.1% of female students mark the highest rate as some what fear. Second, 23.1% of male students represent to be usual and 29.4% of female students represent to be very fear. There fore it speaks for dissimilarity in character between male and female students. 3. On reason of developing dental caries, 62.5% of male students and 55.8% of female students replied that it was developed because they frequently ate the sweet things. 4. Children who pull out decidous teeth alone mark the highest rate as 44.7% of male students and 38.6% of female students. 5. On important thing for ordinary dental health, 56.2% of male students and 58.5% of female students as the highest rate replied that they often brushed their teeth.