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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korean Acedemy of Dental Technology
Journal Basic Information
Journal DOI :
Korean Academy of Dental Technology
Editor in Chief :
Volume & Issues
Volume 22, Issue 1 - Dec 2000
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A Study on the Suitability of Cervical Margin According to Die Materials Used in Crown Prosthesis
Lee, In-Kyu ; Choi, Un-Jae ; Chung, Hee-Sun ;
Journal of Korean Acedemy of Dental Technology, volume 22, issue 1, 2000, Pages 5~12
The gaps between the die margin worked and the casting body were measured with an optical microscope and compared after making crown prosthetic materials using three kinds of die material - dental stone, extra hard stone, epoxy resin - used in crown prosthesis. The results are as follows : 1. All the gaps between the cast cervical margin and the casting bodies were relatively good regardless of die materials used with the gaps under
, the allowable limit. 2. The cervical margin suitability of epoxy resin die was the highest among the three kinds of die material with the suitability value of
. 3. Among the four surfaces(buccal, lingual, mesial, distal) of all the casting bodies, buccal surface was the highest in the cervical margin suitability with the value of
An Experiment on How the Length and the Diameter of the sprue Effects the Size of the porosity, that is Created During the Moduling Process
Hwang, Seung-Sig ;
Journal of Korean Acedemy of Dental Technology, volume 22, issue 1, 2000, Pages 13~20
This experiment was done to find out how the length and the diameter of the sprue effects the porosity created during the moduling process, which is caused by the metal's shrinking and stretching action. the experiment was done in two groups(A and B), using experimental gold, and made 10 copings for both groups. 1. In group A, The length of the sprues were given the same, but the diameter of the sprue were 6, 8, 10, 12, 18 gauge. As a result, the porosity came out big with 12 and 18 gauge and for 10, 8, 6 gauge, the porosity was hardly seen or none was noticeable. 2. In group B, the diameter was given the sam for the sprues, but the length of the sprues were 5, 10, 15, 20, 25mm. As a result, the porosity came out big with 25, 20, 15mm the porosity was hardly seen or none was noticeable. 3. The diameter needs to be big and the length, short. 4. The appropriate sized sprue must be chosen for each individual tooth, according to it's shape and size.
Construction of Frankel Functional Regulator II
Lee, Gyu-Sun ;
Journal of Korean Acedemy of Dental Technology, volume 22, issue 1, 2000, Pages 21~38
functional regulator have a complicated design and are of a big bulk. This makes not only the construction of appliance but also the adaption of a patient to the appliance very difficult. Therefore, orthodontic laboratory technicians should be well acquainted with the sequential fabrication procedures involved in the construction of Frankel functional regulators and construct a type most suitable for a specific patient of malocclusion. There are various types of Frankel appliances. Detailed construction procedures of FR II are described here below, which can also be applied for other types for FR appliances.
An Experimental Study on Effect on Debonding Strength of Metal-porcelain by Painting Method of Opaque Porcelain
Kim, Sa-Hak ;
Journal of Korean Acedemy of Dental Technology, volume 22, issue 1, 2000, Pages 39~47
This study is the know the difference bond strength according to painting method of Opaque porcelain. Among Porcelain powder for Porcelain, Noritake powder, Bonding agent 1 class and metal are selected as Base metal alloy. And painting method of Opaque porcelain is divided by 4 groups : PG, WG, NG and DG. Also it is to manufacture 24 sheets of Specimen by 6 each every method and to measure Crack-initiation Strength of Metal-porcelain and it is to observe it by Scanning electron microscope. I come to get a conclusion as follows. 1. As for Debonding strength of every experiment groups, it showed that WS group which executed Wash bake had highest value, 44.25MPa and NG group which used Normal powder had value, 42.11MPa and DG group which used Bonding agent had value, 35.88MPa and PG group which used Paste opaque had value, 35.39MPa. 2. In four painting methods of Opaque porcelain, PG group, WG group, NG group and DG group, there is no significant difference statistically in Crack-initiation Strength. 3. As a result of observing fracture surface with Scanning electron microscope, it was showde that PG group remained a lot of particle of porcelain on the surface of metal than WG group, NG group and DG group.
A Study on All Ceramic Crown Manufactured Using Gold Plating Upon Refractory Cast Die
Shin, Moo-Hak ; Kim, Yeoun-Soo ; Chung, Hee-Sun ;
Journal of Korean Acedemy of Dental Technology, volume 22, issue 1, 2000, Pages 49~55
In manufacturing the all-ceramic crown whick look close to natural teeth, the effectiveness of the improved technique is expectected the technique of the heat treatment of gold plating coating die was experimented of a refractory cast model. The following results were obtainde 1. An advantage of build up on east die with out manufacturing veneer, crown, core, or masking(reduction of technical process, and retrenchment of time and money) 2. Esthetically more close to natural teeth than other technique 3. Easy to remove a refractors cast die 4. In manufacturing ceramo-metal crown the enomous effectiveness was obtainde on applying in the areas of cervical margin, the metal surface, and in the treatment of pinhole.
A Study on the 2 Key Bridge
Park, Jong-Hee ;
Journal of Korean Acedemy of Dental Technology, volume 22, issue 1, 2000, Pages 57~67
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
The Effect of Burn-out Temperature and Cooling Rate on the Microstructure and Corrosion Behavior of Dental Casting Gold Alloy
Lee, Sang-Hyeok ; Ham, Duck-Sun ; Kim, Hak-Kwan ; Jang, Ju-Woong ; Kim, Myung-Ho ;
Journal of Korean Acedemy of Dental Technology, volume 22, issue 1, 2000, Pages 69~78
The microstructure and corrosion behavior of commercially dental casting gold alloys were investigated to clarify the effect of burn-out temperature and cooling rate. In the case of water quenching after casting, only the αphase, which is typical dendritic microstructure of golda alloy, was detected. However, the precipitates along the grain boundary were detected only at the slow cooling rate and they increased inversely proportional to the burn-out temperature. This might be due to the time difference which solute atom could diffuse. EPMA and SEM results also demonstrated that the precipitate should be lamellar structure consisted of Ag rich phase(
) and Cu rich phase (
). In terms of corrosion, the galvanic coupling was formed due to the difference of composition between precipitates and matrix at the slow cooling rate. In the case of water quenching, the critical current density(
) which indicate the degree of corrosion was lowest at
and below the burnout temperature,
increased with it because of the effect of grain boundary segregation. But above the temperature,
increased with it. This may be due to the strain field effect by residual thermal stress.
Finite Element Analysis on Stress Distribution in Base Metal-Ceramic Crown Margin Designs
Lee, Myung-Kon ; Shin, Jung-Woog ; Kim, Myung-Duk ;
Journal of Korean Acedemy of Dental Technology, volume 22, issue 1, 2000, Pages 79~88
The objective of this finite element method study was to analyze the stress distribution induced in a maxillary central incisor Ni-Cr base metal coping ceramic crowns with various margin design. Margin designs of crown in this experiment were knife-edge metal margin on chamfer finishing line of tooth preparation(M1), butt metal margin on shoulder finishing line(M2), reinforced butt metal margin on shoulder finishing line(M3), beveled metal margin on bevelde shoulder finishing line(M4). Two- dimensional finite element models of crown designs were subjected to a simulated biting force of 100N which was forced over porcelain near the lingual incisal edge. Base on plane stress analysis, the maxium von Miss stresses(Mpa) in porcelain venner was 0.432, in metal coping was 0.579, in dentin abutment was 0.324 for M1 model, and M2 model revealed in porcelain was 0.556, in metal coping was 0.511, in dentin was 0.339, and M3 model revealed in porcelain was 0.556, in metal coping was 0.794, in dentin was 0.383 for M4 model. All values of each material in metal-ceramic crown were much below the critical failure values.
Subhective Symptoms and Work-related Health Risk Factors in Korean Dental Laboratory Technicians
Kim, Woong-Chul ; Lee, Se-Hoon ;
Journal of Korean Acedemy of Dental Technology, volume 22, issue 1, 2000, Pages 89~112
Although dental laboratory technicians are prone to be exposed to various work-related health hazardous materials such as dusts, chemicals, etc., the prevalence and nature of work-related health problems of them have not been a matter of great concern in the field of occupational health service in Korea. The purpose of the present investigation was to describe a collected profile of subjective health symptoms and their attributable factors in Korean dental laboratory technicians. A questionnaire listing five groups of health symptoms and five health symptom-related factors was mailed to randomly selected 1,900 dental laboratory technicians. Among them, 1,344 dental laboratory technicians filled out the questionnaires and returnde them. Five groups of health symptoms included musculoskeletal symptom, dermal symptoms, respiratory symptoms, eys symptoms, and ear symptoms. Five health symptom-related factors were occupational environment-related health risk factors, work history, health related habits and status, use of personal protective equipment and general characteristics. Detailed parameters of health risk factors were work posture, vibration, and chemical or physical hazards such as dust, fume, vapor, solvent, light, and noise for occupational environment-related factors; work place, area, number of employees, work hours, career, work part, and work load for work history; Broca's index, hours of sleep, eating, smoking, alcohol, exercise, health examination, and self assessed health status for health habits and status; face masks, goggles, and so on for use of personal protective equipment, and; age, sex, marital status, and education for general characteristics. Before the start of main survey, a pilot survey was carried out for validity and reliability tests of the questionnaire. All the data obtained were coded and analyzed with PC/SAS 6.12 program. The prevalence of health symptoms was the highest in musculoskelton (87.3%), and followde by eyes (78.9%), respiratory organs (64.3%), ears (57.8%), and skin (52.2%) in descending order. Statistically significant risk factors by multiple logistic regression analyses were sex, health examination, self assessed health status, and hand/finger posture in musculoskeletal symptoms; sex, self assessed health status, career, acid gas, and hand contact with resin mixture in deraml symptoms; Broka's smoking, exercise, self assessed health status, and face mask in respiratory symptoms; sex, hours of sleep, self assessed health status, work hours, work load, plaster dust, inadequate lighting, and goggle in eys symptoms, and eating, smoking, self assessed health status, and work load in ear symptoms. With the above considerations in mind, prevalence of subjective symptoms among Korean dental laboratory technicians was relatively high, and they were attributable to most of the occupational environment-related factors, work history, use of personal protective equipment, health habits and status, and general characteristics. Particularly, it is suggested that health promotion programs for promoting self- assessed health status and smoking cessation, preventive measures for protection of the female technicians’health, and reducing work load be necessary, since those factors were associated with more than one subjective symptom.
A Study on the Health Management of Dental Technicians and Their Awareness of the Same
Choi, Un-Jae ;
Journal of Korean Acedemy of Dental Technology, volume 22, issue 1, 2000, Pages 113~128
The purpose of this study was to serve as a basis for the development of dental technology and for creating a condition that dental technicians could work with pride and right values, by examining what problems there were in their health care, what they thought about them, and how the problems could be solved, The findings of this study were as below: 1. The most serious and harmful element in dental technology workshop was a dust(57.5%) and a noise(33.3%). 2. Approximately 99.0% of the dental technicians investigated made a complain of air pollution caused by noise. Their opinion on a possible measure to remove noise air pollution was that the noise-generating machine should be replaced(64.1%) or that it should be isolated(28.8%). 3. 76.0% complained air pollution cause by dust deteriorates their working efficiency. As a way to eliminate it, they suggested a dust chamber(35.3%) or an air cleaner(27.5%) should be installde. 4. About 80% made a complain of gas air pollution. The most common related symptom was a headache(56.9%). They thought that gas-generating machine should be isolated(39.9%) or that an air purifier should be prepared(33.3%). 5. The largest impact of heat and light on their body was weakening their eyesight(56.9%). 47.1% got burn once though four times, and 34.3% did five times or more. The way to prevent them was to install an automatic casting machine(66.0%) or use protective glasses(28.1%). 6. Approximately 47.7% were considering a change of occupation, and the most common reason was heavy work(23.5%), followed by poor prospect(21.6%) and working environment(19.0%) in the order named. 7. 88.9% responded they were likely to have an occupational disease. Their idea about the proper frequency of regular health examination was once a year(53.6%), or once per every six months(41.8%). 8. The field they were most interested in was health care(39.2%), followed by academic research activities(31.4%). This fact indicated it's most urgently required to improve their working environment.
Dental Patient's Satisfaction Degree Factors -Concerned with installation of dental clinics -
Kim, Nam-Joong ; Hwang, Kyung-Sook ;
Journal of Korean Acedemy of Dental Technology, volume 22, issue 1, 2000, Pages 129~143
With increasing number of dental patients, it is also increasing patient's desire to get better medical service. As the concern for improvement of dental medical service quality is growing, satisfaction degree of dental patients is becoming very important. This study was to investigate difference of patients' satisfaction degree concerned with installation of dental labs and the reason. The data for this study were collected through Self-Administered Questionnaires from 284 patients who had visited dental clinics more than two times. The results are as follows: Female respondents ratio was as twice much as male ones. And 54.2% of the respondents were found out to have completed university education. Dental clinics with dental labs scored higher than others in patients' satisfaction and recommendation willingness degree. Dental clinics without dental labs scored higher in patients' revisiting willingness degree. With simple Correlation Analyses it was found out that the most influential variable concerned with patients' general satisfaction degree was medical facility in dental clinics with dental labs, dentist ability to cure in dental clinics without dental labs. There were some discrepancies with other subordinate variables. Through Stepwise Multiful Regression Analyses it was found out that the most influential variable with patients' general satisfaction degree was dentist ability to cure in total and dental clinics without dental labs and medical facility in dental clinics with dental labs. There were also some discrepancies with other subordinate variables.
Isolation of Methylotrophic Actionmycetes Capable of Producing Antagonistic Activity Against Oral Resident Bacteria and Screening of Mutants
Park, Myoung-Ho ; Lee, Hwa-Sik ; Bae, Bong-Jin ; Kim, Joung ;
Journal of Korean Acedemy of Dental Technology, volume 22, issue 1, 2000, Pages 145~152
In order to select an effective antibiotic substance against oral resident bacteria, we were isolated from soil and texonomically analyzed. Seven hundred and eighteen strains were isolated on humic acid- vitamin agar(HV agar) and 220 strains were on methanol medium from three each paddy forest, field and riverside soil samples. So, during the screening of antibiotics from soil, we isolated microorganisms showing powerful antagonistic activity against oral resident bacteria. Microorganism was tested against 25 strains of bacteria, yeast and fungi. Among them, No. 248 strain exhibited the most strongly growth inhibition. So, the taxonomical analysis the isolated strain was found to be unknown Actinomyces sp. and was named No 248. A production of the antibiotics from No. 248 begins at the early exponential phase developed at the 72th hour under the optinum conditions. The property of No. 248 antimicrobial compound was very stable under acid(pH 3.0) and alkali(pH 10.0) treatment, but it was instable in heat treatment at
. For the improvement of antibiotic activity, two mutants were isolated from strain No. 248 by the treatment of mutagenic agents, NTG and hydroxylamine. As a result, the mutant strains excreted the potent antibiotics to inhibit the growth of Candida albicans.
Comparison Analysis of a Cost Price for Dental Prosthetic Restoration
Park, Myoung-Ho ; Lee, Sang-Rak ;
Journal of Korean Acedemy of Dental Technology, volume 22, issue 1, 2000, Pages 153~178
Dental prosthetic restoration shows a big difference of cost per itemized unit depending on the size of dental labs, facility standard, manpower, and performance. Even the same dental labs have distinctive cost according to manufacturing performance, inflation, and the number of workers. However, in apite of such a change of circumstances, it appears to be quite stable in the relative cost per itemized unit unless the manufacturing trend of particular item changes dramatically. Therefore, if the relative number of cost per itemized unit, which is produced by costing, is indicated, we are able to utilize it effectively as a standard wage estimate. If the wage of dental prosthetic restoration is determined on the basis of cost, it is desirable that the relative value of cost and that of wage are identical. But, by means of comparative analysis, since the relative value of wage reveals mostly lower than that of cost depending on an item, it is considered that the wage is not reflecting the cost approproately. Due to the subdivision and the profession of medical technology, the new development of wage items for dental prosthetic restoration is required. This means that the need for the establishment of new wage items should be presented as the general concept of dental prothetic restroation changes and the level of pathologic technology increases. The current wage structure has differences in the degree of difficulty accroding to unit items and in the cost factors. Nevertheless, the differences are not reflected enough to the wage, so there is potential to lower the medical quality through the use of low-proce materials to avoid the increase of cost and the work process which skips a manufacturing step. The new items of dental prosthetic restoration also increases, but the development of proper numerical value system is not supported. Thus, the right proce is set mostly by applying to the wage of a similar item. Since most wages are established by an individual agreement between the dental clinic institute and the dental labs, the propriety of wage level lacks. Therefore, it is urgent to provide and promote the system of a fair work charge by a standard cost which can be applied to all medical institute.
A Study on the Continuing Education of Dental Technicians
Moon, Je-Hyuk ;
Journal of Korean Acedemy of Dental Technology, volume 22, issue 1, 2000, Pages 179~198
Since dental prosthesis is made possible only when dental technicians give themselves to the study of knowledge and the acquisition of updated skills, continuing education is of great importance in that it makes up for the efforts of dental technicians. Accordingly, continuing education relates to a system designed to contribute to the enhancement of the talents of dental technicians and the dental health of the nation. Specialized knowledge and information may work as the best weapon to preserve their jbs. This is true of this modern society where no one can expecth to survive without acquiring knowledge and information constantly for work is getting more classified and more divirsifide. This paper is dedicated to take a look at the current condition of the continuing education of dental technicians and to come up with measure to make general evaluation and to improve continuing education. This research resorts to 609 questionnaires among 6433 copies save unfaithfully responded 34 copos with 6.431 dental technicians as the subjects enrolled in the Dental technician Association. The collected questionnaires consist of 365 dental technicians living in Seoul and of 244 ones, Which account for 11.8 percent of dental technicians enrolled in the association. Because dental technicians live more in local areas than Seoul, the generalization of this survey leaves something to be desired. I have come up with the following findings. 1. 6,431 dental technicians, or 36.3 percent of an total of 14,956 licensed dental technicians, were admitted as numbers of the Dental Tachnician Association as of October 31, 1999. In the '98 continuing education. 4,141 dental technicians among 4,711 dental technicians got relevant training, and in the '99 continuing education, 4,075 technicians, or 75.9 percent of 5,365 technicians got relevant training while 1,290 technicians or 24.2 percent, fail to get relevant training. 2. The survey has it that 38.1 percent of dental technicians are ignorant of the laws on continuing education, and that technicians staying in local communities(146 persons, or 61.6%) take more part in education than those living in the capital of Korea(159 persons, or 146%), and that the older they are, the more money they earn, the more carrer they have, the higher position they hold, the more part they take in education 3. According to the survey, those who have the experience of getting training more than three times account for 52 persons(16.8%) in Seoul and 47 persons(22.4%) in local districts(p<0.01). In terms of sanctions in relation to continuing education, 26 dental technicians(4.6%) say that they have ever gotten sanctions, and 533 dental technicians(95.4%) say that they haven't. And those who were absent from continuing education(72 technicians : 13.51%) didn't get any sanction. 4. In terms of the degree of understanding continuing education, local technicians(46.8% : 110 persons) have a higher understanding of continuing education than their countparts staying in Seoul(36.0% : 130). Continuing education is not the ultimate goal itself. It should be changed to motivate those who get education to be willing to take part in contunuing education, and to help dental technicians in a practical and specific way. And the branch societies should be developde to engage in more specialized and classified expert fields. Of course, the curriculum should be so selected that the conceptions of dental technicians may be reflected to the maximum extent, and the ultimate effores should be made to effect diversity in the ways of educational methods and to perfect the preparation of continuing education on the part of instructors. Regulations should be established in relation to continuing education with a veiew to enhancing the participation of continuing education and its effectiveness. The supervision of the Ministry of Health and Welfare is of great importance in this context. The regulation of continuing education is not administrative regulation, but the expression of national will to guarantee the medical service of the nation at highest level. Therefore, it is necessary that the Ministry of Health and Welfare should change their understanding of the needs for the continuing education of dental experts, and that the expertise of government employees in charge of continuing education should be expanded. It goes without saying that the government should suppory continuing education in a financial way so as to supply the person in charge of public welfare and control the quality of national medicine.