• Journal of Technologic Dentistry
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• v.20 no.1
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• pp.121-138
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• 1998

With 1002 students around 8 colleges nationwide joining, the survey was on their knowledge before entering their school, and thereafer, the degree of their satisfaction in their major and professors & lectures. 1. When they chose their major, the most influential was their parents and relatives, the largest number of 435(43.5%) replied, About the motivation for selection their jajor, 454(45.4%) answered the most it seemed to be a bright future specialty. On that question, more freshmen(51.0%) answered theyu expected good trend than sophomores and juniors and more women students(48.8%) did so than men ones.(P<.05) 2. While 619(61.8%) were familiar with major before applying, only 68(6.85%) knew their major very well at that time. More freshmen(62.5%) applied in the state of well-knowing what their major is than sophomores and juniors did.(P<.01) More women students(40.9%) applied not knowing it than the counterpart. About the time for choice, 795(79.5%) answered the most one of application days. More women students(81.0%) chose their major during the application time(P<.01) 3. The satisfaction survey shows 438(43.8%) are satisfied and 165(16.5%) are not. More men students(47.2%) are satisfied.(P<.01) The factor their satisfaction is their major come together with aptitude(44.7%), 196ppl), and the dissatisfaction factor is the difficulty of the theory and practice.(30.8%, 171ppl) 4. If they could change their major, 454(46.6%) wouldn't do so, while 541(54.4%) would shift their major to other fields. More freshmen(49.5%) wouldn't change than sophomores and juniors. Neither did more men students(4938%) than women. Within the same grade, there's no meaninful difference.(P<.01) 5. On the satisfaction in the lectures of the professors of their major, 464(46.5%) said the lecutres are excellent, 102(10.2%), they are not. About the lectures of the liberal subjects, 193(19.4%) said are excellent, 365(36.6%) are not.

• Journal of Technologic Dentistry
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• v.15 no.1
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• pp.89-94
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• 1993

The tooth size and shape of the permanent incisor teeth have been studied and analyzed about the mean size, S.D, S.E, etcs and percentage from stone model of 100 Korean male and 74 Korean female. The results were as follows. 1. The crown length of permanent incisor teeth were longer in males than in females statistical differences of males and female were not found. 2. the mesio-distal diameters of permanent incisor teeth were larger in males than in females and statistical differences of males and females were found in mandibular lateral incisor and the bigest were max. central incisor, 2nd max. lateral incisor, 3rd man. lateral incisor and the smallest were man. central incisor. 3. The square form in max. central incisor was the greatest percentage and the tapering form in max. lateral incisor and man, incisor was the greatest percentage but tapering form and ovoid form and other shape were found in max. lateral at the same ratio. 4. Concerning the labial developmental groove "midium" was the greatest percentage in the max. central incisor and "low" was the greatest percentage in the man incisor. Concerning the incisal line, straight line was the greatest percentage in the max, incisor and man, incisor and concerning the lingual tubercle "none" was the greatest percentage in the max. incisor. 5. In comparison between left side and right side of incisor, the ratio of same shape ware 22.4%-36.2% but similar or dissimilar cases were more frequently found.

• Journal of Technologic Dentistry
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• v.35 no.1
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• pp.19-27
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• 2013

Purpose: The aim of this research was to evaluate the shear bond strength of different zirconia veneering ceramics with and without liner glass materials to yttria partially-stabilized tetragonal zirconia polycrystalline(Y-TZP). Methods: Five co mmercial zirconia veneering ceramics were used in this study, E-Max(EM), Creation ZI(CR), Cercon ceram kiss(CE), Triceram(TR) and Zirkonzahn ICE(ZI). All samples were prepared according to manufacturer's instructions. Experimental industrially manufactured Y-TZP ceramic blocks(diameter: 2.7 mm; height: 13.5 mm) were used in this study. Shear bond strength between zirconia ceramic coping and zirconia veneering ceramics were evaluated by the push-shear bond test. The fracture load data were analyzed using ANOVA and Scheffe's test(${\alpha}$=0.05). The fractured surfaces of zirconia core ceraimc and zirconia veneering ceramics were observed using a scanning electron microscope(SEM). Results: The mean shear bond strengths ranged from 20 MPa ($20.12{\pm}6.34$ MPa) to 66.6 MPa ($66.62{\pm}10.01$ MPa). The Triceram(TRG) showed the highest value and Creation ZI(CR) showed the lowest value. In all groups, Zirconia liner and glass material groups was significantly higher shear bond strength than without liner(P<0.05), with the exception of Cercon ceram kiss(CE)groups. Conclusion: Zirconia bonding materials may have the advantage of improved bond strength between zirconia ceramic core and veneering ceramics.

• Journal of Technologic Dentistry
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• v.37 no.2
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• pp.69-76
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• 2015

Purpose: In this study, the marginal fitness of ceramic Co-Cr metal crown made by precision casting, milling, and selective laser melting method were compared. Methods: The ceramic Co-Cr metal crown manufactured by precision casting used the lost wax(LC specimen) method. The abutment were scanned and then made by milling(CM specimen), selective laser melting(CS specimen) method. The specimen were cut bucco-lingual and mesio-distal, and absolute marginal discrepancy and marginal gap were measured using a digital microscope. The surface roughness of the crown was also observed. Results: On the bucco-lingual axial, absolute marginal discrepancy was the LC specimen $31.72({\pm}4.58){\mu}m$, the CM specimen $78.29({\pm}3.28){\mu}m$ and the CS specimen $143.13({\pm}3.83){\mu}m$, respectively. On the bucco-lingual axial, marginal gap was the LC specimen $22.70({\pm}1.46){\mu}m$, the CM specimen $22.70({\pm}1.49){\mu}m$ and CS specimen $99.60({\pm}1.57){\mu}m$, respectively. Conclusion: For ceramic Co-Cr metal crowns, LC specimen was superior for absolute marginal discrepancy and marginal gap. The surface of metal crowns by selective laser melting were the roughest.

• Journal of the Korea Convergence Society
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• v.9 no.12
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• pp.365-372
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• 2018

This study aimed to investigate the perception on dental hygienists and convergence factors to affect social requirements on their roles so as to utilize them as the fundamental data to assist the common people to understand the occupation and roles of dental hygienists and expand their positive perception further. Upon the multiple regression analysis from 235 final analysis subjects who underwent survey from August 1st to 25th 2017 among 270 adults in Busan and Gyeongnam areas, the awareness level on the dental hygienists was higher as the education level was lower and quality of life was more positive. Requirements were increased more as the education level was lower, quality of life related to oral health was more positive, quality of life was more positive, and awareness level on the roles and knowledge of dental hygienists was increased more. Further programs and promotional plans should be continuously activated to establish the career roles and expand the awareness in every field including dental clinic practices, dental hygiene training, related groups, and so on.

• Journal of Technologic Dentistry
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• v.18 no.1
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• pp.73-94
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• 1996

This study was aimed for evaluating the validity of relative-productivity index on the basis of working hour(RPHW index) designed by author as new productivity index and drawing up a plan of bettering productivity to cope with financial difficulty of dental laboratories. Fortyeight dental laboratories extracted by cluster-sampling method form all the dental laboratories in Seoul were subjected for this study. And in each of them, the term of establishment which was divied into three group as short-term, mid-term and long-term group, the scale of dental laboratory which as divided into two group by number of dental technician as small-scale group and large-scale group, the salary system which was composed of salary criteria, pay according to ablility criteria and collectiveagree, the salary level, simple labor productivity index(SLP index), relative-productivity index on the basis of worker number(ROWN) and relative-productivity index on the basis of working hour(RPWH index) were surveyed through the self-administractive questionaires. The results as follows : Most of dental laboratories(93.6%) were managed by non-professional managers. The establishment rate per year of dental laboratory was the increase. The mean number of employees of dental laboratories was $7.00{\pm}3.90$ person. The ratio of smallscale group(under the 5 employees) was 42.6% and as the term of establishment was shorter, the ratio of small-scale group was higher. The mean establishment area of dental laboratories was $24.49{\pm}10.97$ unit and the mean establishment area per head of dental laboratories was $4.05{\pm}3.90$ unit. The estabilshment area and area per head were not significantly associted with the term of establishment, but as the term of establishment was shorter, the estabkishment area per head was slightly wider. The establishment area per head in small-scale group was significantly wider than large-scale group(over the 6 emplayees) The salary criteria(54.4%), pay according to ability(79.2)m ability criteria(77.1%) and collectiveagree(79.2%) as salary systems were used in the most of all dnetal laboratoies. The all salary systems were not significantly associated with the term of establishment and the scale of dental laboratories. The monthly mean salary level of dental laboratoies was $125.64{\pm}31.06$ milion won. The monthly salary level was not significantly associated with the term of establishment and the scale of dental laboratores. But the monthly salary level in the short-term group and the small-scale group were slightly lower than others. The SLP index, the RPWN index and the RPWH index of dental laboratories were $132.16{\pm}48.41$, $382.41{\pm}128.76$ and $76.06{\pm}25.11$, respectively. The SLP, the RPWN and the RPWH of dental laboratories were not significantly associated with the term SLP, the RPWN and the RPWH of dental laboratories were significantly associated with the area of dental laboratory and the salary level. Except for only the association salary criteria among salary system with RPWH of dental laboratories, all other salary system were not associated with the SLP, the RPWN and the RPWH of dental laboratories.

• The Journal of the Korean dental association
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• v.11 no.1
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• pp.41-44
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• 1973

The experiment consisted of cementing full veneer crown of extracted teeth and a standardized cylindrical metal dies (6mm diameter, 6mm height, 1mm shoulder) and then measuring the tensile strength required to remove the cemented restoratoins by the Instron testing machine in the Korea Institude of Science and Technology. The Instron machine was operated at a rate of loading of 0.2cm per minute. From the experiments, the following results obtained. 1. The tension of zinc phosphate and alumina EBA cements were highest all of the cements. 2. The tension of Fynal and the addition of eugenol to zinc Phosphate cements were similar. The addition of eugenol to zinc phosphate cement was half stength and Fynal cement was on third strength than zinc phosphate cement. 3. The tension of zinc oxide-eugenol cement was lowest all of the cements.

• Journal of Korean society of Dental Hygiene
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• v.10 no.6
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• pp.955-963
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• 2010

Objectives : The purpose of this study was to examine effect of the application of different types of coffee on teeth stain during home bleaching. Methods : Twenty five premolars that were extracted within the past month and healthy without any signs of dental caries or restorations were collected and divided into five groups. The teeth of a control group were bleached everyday for two weeks, and the teeth of four experimental groups were bleached everyday for two weeks and then deposited respectively in four different types of coffee solution: brewed coffee, black coffee, coffee with sugar, and coffee with sugar and cream. Afterwards, the color of the teeth of the four experimental groups was checked by a shade pilot. Results : As a result, there were significant differences in the change of lightness and color according to the blending type with the lapse of time during home bleaching. Concerning changes in lightness and hue, there were the largest differences in the control group and the experimental group deposited in coffee with sugar and cream, followed by coffee with sugar, black coffee and brewed coffee. When the extent of change in lightness and hue was investigated after home bleaching, the experimental group deposited in coffee with sugar and cream was stained the least, and the experimental group deposited in brewed coffee was stained the most. Conclusions : In conclusion, the intake of coffee that is the cause of stain should be reduced during bleaching, and in case of having a cup of coffee, it's advisable to have coffee with cream.

• Journal of Technologic Dentistry
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• v.22 no.1
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• pp.57-67
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• 2000

The 2 key bridge system has been developed to make crownless bridges without damaging sound teeth. Strong bridge work of single or multiple pontics is possible for replacing both anterior and posterior teeth. It is incresingly considerde to be unacceptable, by dentists as well as patients, to fully grind down healthy elements in order fit a conventional bridges. Because this technique uses a combination of hole and adhesive fitting, it has a number of adventages over etched bridges and conventional bridges: - In comparison with conventional bridges, hardly and healthy dental tissue is sacrificed - Due to the lack of crown edges there is no periodontal pressure, as is the case with conventional bridges - The treatment procedure is straight forward and involves less time than conventional bridges. - The treatment is largely resiverable and repairable

• Journal of The Korean Society of Integrative Medicine
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• v.6 no.3
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• pp.73-81
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• 2018

Purpose : This study identified knowledge, attitudes and behavior for radiation safety management of dental hygiene student. And to provide basic data for the development of effective education program for safety management for radiation protection. Methods : A questionnaire survey of questionnaires was conducted on the second and third grade dental hygiene students at three - year college in 'A' area of Gyeongnam province. The questionnaire of 37 items was used to investigate knowledge and attitude about radiation protection. The collected data were analyzed using frequency analysis, mean, standard deviation, t-test, ANOVA and pearson's correlation Analysis using the SPSS 21.0 program. Result : Results obtained from this study are as follows. 1. Knowledge level of radiation safety management by general characteristics showed statistically significant difference. 2. Radiation safety education knowledge score was higher in the case of radiation safety education(t=1.660, p<.05). 3. The radiation safety management attitude score was a statistically significant difference between the groups according to 'achievement' (F=1.660, p<.001). In the case of 'radiation protection facilities', there was a statistically significant difference between groups according to the recognition of radiation protection facilities (F=6.001, p<.001). 4. As a result of investigating the relationship between radiation safety management knowledge and attitude, the higher the knowledge level of radiation safety management, the higher the attitude(p<.001). Conclusion : Therefore, radiation safety management education should be organized systematically and it is required to improve not only safety management knowledge, attitude level but also action level.