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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 21, Issue 1 - Jul 1999
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Synthesis and Hardness of Glass Ceramics for Dental Crown Prosthetic Application in the system CaO-MgO-SiO2-P2O5-TiO2
Chung, In-Sung ; Kim, Kap-Jin ; Cheong, HO-Keun ; Lee, Jong-Il ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 5~14
Glass ceramics for dental crown prosthesis were prepared by crystallization of CaO-MgO-SiO2-
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(
) formed by apatite increased until adding up to 9wt%
to base glass composition, then decreased above that. 2. Apatite(
), magnesium tianate(
) and diopside(CaO-MgO-
) crystal phase were precipitated in MgO-CaO-
glass system containing 9wt% and 11wt% of
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
as maximum value. 4. Vickers hardness of samples increased due to precipitation of apatite, whitlockite,
-wollastonite, magnesium titanate, and diopside crystal phases within glass matrix.
Effect of In on Surface Behaviors of Porcelain-Metal Boundary in Low Gold Porcelain Alloys
Nam, S.Y. ; Lee, K.D. ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 15~26
This study was carried out by observing to composition of oxide on the surface of dental porcelain low gold alloy with various Indium additions according to the degassing and analysing the change composition of additional elements In on diffusion behaviors of Porcelain-matal surface. The specimens used were Au-Pd-Ag alloys by small indium addition. These specimens were treated for 10min at
in vacuum condition. To investigate the microsturcture of oxidized alloy surface, SEM and EDAX were used, and EPMA were used to investigate the diffusion behaviors of porcelain-metal surface. X-ray diffraction were used to observe the morphological changes in the oxidation zone. The results of this study were obtained as follows ; 1) The hardness of alloy increased with increasing amount of In addition. 2) The formation of oxidation increased with increasing In content after heat treatment. 3) Diffusion of indium elements increased with increasing In content in metal-porcelain surface after firing. 4) The oxidations of alloy surface were mainly
The Effect of Au Addition on the Hardening Mechanism in Ag-30wt%Pd-10wt%Cu Alloy
Lee, K.D. ; Nam, S.Y. ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 27~41
The Ag-Pd-Cu alloys containing a small amount of Au is commonly used for dental purposes, because this alloy cheaper than Au-base alloys for clinical use. However, the most important characteristic of this alloy is age-hardenability, which is not exhibited by other Ag-base dental alloys. The specimens used were Ag-30Pd-10Cu ternary alloy and Au addition alloy. These alloys were melted and casted by induction electric furnace and centrifugal casting machine in Ar atmosphere. These specimens were solution treated for 2hr at
and were then quenched into iced water, and aged at 350-
Age-hardening characteristic of the small Au-containing Ag-Pd-Cu dental alloys were investigated by means of hardness testing, X-ray diffraction and electron microscope observations, electrical resistance, differential scanning calorimetric, energy dispersed spectra and electron probe microanalysis. Principal results are as follows ; Maximum hardening occured in two co-phases of
+ PdCu In stage II, decomposition of the
solid solution to a PdCu ordered phase(
type) and an Ag-rich
phase occurred and a discontinuous precipitation occurred at the grain boundary. From the electron microscope study, it was concluded that the cause of age-hardening in this alloy is the precipitation of the PdCu redered phase, which has AuCu I type face-centered tetragonal structure. Precipitation procedure was
at Pd/Cu = 3 Pd element of Ag-Pd-Cu alloy is more effective dental alloy on anti-corrosion and is suitable to isothermal ageing at
Effect for Alloy Addition(Ta, Zr, Sn) on Mechanical Properties and Corrosion Resistance of cp-Ti for Dental Implants
Park, H.B. ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 43~53
The mechannical properties and corrosion resistance of alloy added commercially pure titanium for dental implants have been investigated. Ti, To-65Zr, Ti-10.1Ta and Ti-17Sn alloys were melthed in arc furnace and the corrosion resistance of Ti alloys was evaluated by anodic polarization test. The microstructure and mechanical properties of Ti alloy were analysed by optical micrograph. hardness tester and instron. In isothermal test, Ti-10.1Ta and Ti-17Sn alloys exhibited the best oxidation resistance below
. Ti65Zr, Ti-10.1Ta and Ti-17Sn alloys showed better rockwell hardness compared with commercially pure. Ti As the result of the anodic polarization test in 5%HCl, it 5%HCl, it was known knows that Ti-65Zr, alloy showed a rapid decrease in current density at higher potenial in comparision with other Ti alloys.
A Research on Evaluation Methods of Testing Impact of the Strength of Soldering
Kim, Sa-Hak ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 55~65
So far, I Conducted an examination with focus on the type, characteristic, and test methods of impact test. which is a type of mechanical that evaluate materials. As mentioned previously, in testing soldering strength of soldering is the load when the object under experiment is broken down with the result of flexibility test or peel test. In this method, a hevay load is necessary until alloy of parent metal is bended, if the alloy of the parent metal has a large mechanical quality(peel strength or resisting power). Once the alloy of the parent metal is bended, however, it tends to come into pieces abruply form the part where soldered. Therefore, a metal has a high breakdown value if the degree of strength of its parent metal is high even if the result of measurement indicates otherwise. Thus, the result of the test did not correspond to the clinical result. Therefore, this study concludes as the following from a test of strength of soldering by mean of conducting an impact test, which is a type of mechanical evaluation methods : 1. Among various impact tests, a charpy thpe is more appropriate than the izod type in testing strength of soldering. 2. As far as test piece is concerned, to use subsized impact test piece is appropriate in the impact test in that it does not have notch. 3. In the matter of analysis, it is appropriate to measure absorbing energy which results from rupture of test piece.
Fiction Coefficient between Abutment Materials and Clasp Materials and Estimation of Retention Force of Circumferential Clasp
Lim, Dong-Chun ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 67~75
The purpose of this study is to evaluate the friction coefficients between abutment materials and clasp materials, and to an estimation formula for retention force. The coefficients of friction between three clasp materials and four abutment materials were measured under various conditions, polished and sandblasted and wet and dry. The measurement was repeated for each combination up to a total measurement of 1200 times. Estimation formula for retention force is measured as sum of two terms, which the one time is proportional to the product of friction coefficient
and undercut u and the other term is proportional to u-squared. Two proportional coefficient were obtained by least square method. The results are as follows: 1. Friction coefficients were ranged from 0.08 to 0.53 under various conditions. 2. Friction coefficients of non-metal abutment materials are greater in wet conditions than dry conditions. 3. Friction coefficients of sandblasted clasp against abutment are greater than that of polished clasp. 4. Clasp retention force can be estimated with the model as F=
with minor error.
A Study on the Castability of Investing Method and Casting Direction of Chrome-Cobalt Alloy Widely Used in Production of Patial Denture Framework
Chung, Kyung-Pung ; Choi, Un-Jae ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 77~85
When producing partial denture using a Chrome-cobalt alloy being used universally, 45 pattern of them to compare casting characters according to 5 burying methods(special ring method, plastic ring method, general metal ring method) and 5 casting directions(straight, upper, lower, left and right directions) were compared and evaluated. The results were as follows : 1. The comparison of casting characters in accordance with burying type shows that the special ring method to install blind air vent using utility wax was the highest rate of 76.9%, followed by 69.1% of the plastic ring to cast without ring and 61.1% of the metal ring method being used universally respectively. Namely the special ring method was best. The significant level was P<0.05 statistically. 2. The comparison of casting character in accordance with casting directions shows that the straight casting was the highest of 77.9%, and followed by right casting of 74.2%, left casting of 66.7%, upper casting of 63.5%, and lower casting of 62.9% respectively, Namely the straight casting was best.
A Study on the Castability of Base Metal Alloys Which Sprue Shape and materials used in the Production of Dantal Prosdontics
Choi, Un-Jae ; Shin, Moo-Hak ; Kim, Yeong-Soo ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 87~96
In order to examine the influence of sprue(used to make crown supplements) on casting, 3 kinds of sprue materials(wax, wood, plastic) and 3 types of sprue(round, square, triangle) were made and buried and cast, then the comparison and analysis of casting characters among sprue materials and among sprue type show the following results : 1. The comparison of casting characters in accordance with sprue materials shows wax sprue of 83.3%, wood sprue 81.3%, and plastic sprue of 80.7%, Wax sprue was the bast materials for casting, However there was no statistically significant difference of casting characters among was, plastic and wood. 2. The comparison of casting in accordance with sprue types shows square sprue of 94.0%, round sprue of 86.9% and triangle sprue of 84.2%. square sprue had a best casting character. 3. When a ring cast using wood sprue was classified from burying materials. its cutting of casting body and sprue indicated much more than any other sprue material. It seems to be caused by the influence of wood residuals and carbon occurrence.
A Study on the design waxup technique for maxillary molar occlusion
Moon, Hee-Kyung ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 97~114
The first function of occlusion is mastication. Therefore the functional restoration of occlusal surface is very important. The restoration of occlusal surface is three method as wax bite technique, F.G.P. technique, cone technique. Many dental technician is using compound method. I have knew common point on each teeth during I have waxing up wax pattern. So I studied on the design waxup technique for maxillary molar occlusion. The results of the study were as follows ; 1. The dam wax up method can restore axial contour of teeth very easy and make short working time of wax pattern. 2. The height of dam must be same with cusp of adjacent teeth. 3. Automatically the contour of tooth is appeared if the contour of dam is relationship with cuspid line of adjacent teeth. 4. The height of contour of buccal, lingual surface is formed natural curve to add fluid wax by gravitation. 5. The development groove of Maxillary premolar is appeared V form. 6. The development groove of Maxillary molar is appeared W form. 7. The embrasure is formed to carve around contact point area as round convex. It affects to axial form of tooth. 8. I was knew that the lingual groove and stuart's groove of molar runs parallel with oblique ridge. 9. The buccal groove of molar is formed parallel with direction of teeth arrangement.
A Finite Element Analysis of Stress Distribution in the Tooth and Crown According to Design of Esthetic Crown
Lee, Myung-Kon ; Chung, In-Sung ; Kim, Ji-Hwan ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 115~121
This investing was carried out to evaluate the alteration of stress distribution on teeth and esthetic crowns. Analyzing the stress distribution by the two-dimensional finite element methods, a model of lower 1st molar according to the porcelain fused metal crown an the porcelain fused glass ceramic core crown and the all glass ceramic crown. 1. The pattern of stress distribution showed no apparent differences. 2. The greatest von Mises values were concentrated around the central fossa of all esthetic crowns. The greatest Maximum principle value were concentrated around the interface between the base of esthetic crown and the abutment tooth. It was found that the apatite glass ceramic could be applicable for use in dental crown prosthesis.
A Study about the Separation of the materials Used in Refractory Cast Dies For Making All Ceramic Crowns
Shin, Moo-Hak ; Kim, Yeoun-Soo ; Choi, Un-Jea ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 123~130
I attempted to suggest a better method to separate a refractory cast in order to solve the problems caused by bonding between refractory casts and ceramics in the firing-processing of all ceramic crowns as a part of dental prosthodontics. I emphasize the advantages and effectiveness of easy separation after firing by using the separating materials about the refractory cast dies. 1. We must not usse HF(55%) that is used as the chemical separating methods. 2. We decrease such methods as grinding, blasting, bur, and point 3. We can save time, costs and manual labors by using this methods. 4. This method regulates the expansion and constriction of heat because of the chemical reaction of the separating materials. 5. This method contribute to the breaking down without modification by minimizing the chemical and mechanical damages of the marginal and interior parts.
A Study On the Distribution of Malocclusion Patents From Department of Orthodontics, Chong-A Dental Hospital
Kim, Nam-Joong ; Lee, Tae-Jung ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 131~138
As a society has developed, much concern has been put on appearances of people with development of economy. Accordingly malocclusion patients have been increasing. With this trend, it has become very important to investigate patients characteristics so as to cure the patients effectively. This study investigated 724 malocclusion patients who had been examined diagmosed and recorded well at Chong-a Dental Hospital for 5 years from 1994 to 1998. The results are as follows ; 1) The total number of orthodontic patients in 1998 increased about 79% than in 1994, and female orthodontic patients(68.1%) were more than male ones(31.9%). 2) Age distribution has shown more than 19 year-old group being the largest(48.9%) 3) Distributions in the types of malocclusion according to the Angle's classification have shown 42.5% for class I division, 21.5% for class II division, 35.9% for class III division, being class I division the largest. 4) 50.1% of the total patients were from Kang-nam Gu, So-cho Gu, and Song-pa Gu.
Nutritional and Cultural characterizations of microorganism capable of producing antagonistic activity against Streptococcus mutans
Park, Myung-Ho ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 139~144
The optimum culture conditions for an antibiotics from Actinomyces sp. were investigated. The optimum composition of medium for antibiotics production was 1% glucose, 1% soybean meal, 0.5% NaCl, 0.1%
, and the optimum initial pH was 7.0. And the antibiotics showed highest activity when the strain isolated from soil was aerobically cultivated at
for 72hours under the optimum conditions. A production of the antibiotics from Actinomyces sp. begins at the 36th hours and then reached the maximum at the stationary phase developed at the 72th hours under the optimum conditions.
In vitro effects of titanium on oral microorganism
Lee, H.S. ; Bae, B.J. ; Kim, J. ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 145~151
Titanium(Ti) alloys has been mostly concerned with biocompatibility, corrosion resistance, and biofunctionality. However, very little is known, about the biological effects of titanium on microorganism and in particular on the oral flora. So, the effect of titanium on the in vitro growth of oral microorganism forming dental caries was studied under either aerobic or anaerobic condition. In this study, the mostly bacterial species commonly found in dental plaque or gingival sulcus grew well in an aqueous medium containing
of titanium standard solution.
A Study on the educational direction of Dental Technology Department in the 21st century
Park, J.H. ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 153~163
The 21st centurt, the era of change-space, is requesting us to readjust our education system. In other words, we should renew it by looking back into the past cultivate more advanced ideas. As a matter of fact junior colleges have been considered just as miniture of universities in every way such as curriculum, prossor emploment, school affairs, etc. Therefore we should change our existing education system not to be criticized for the next century. May students are trained for industry as dental technicians in our department of college. We should educate experiment and practice substantially as college professors as well as exert ourselves in developing our abilities to adapt to high diverse industrial technique, putting emphasis on practice more than theory. It is mecessary for us to sufficiently teach the technique to good students and make them display their abilities in order to produce high quality goods. Reinvestment ineducation is a condition precedent. Dental laboratories have just employed the students that graduated from our college. However it's time for a change. They should pay attention to our education and assist us in all respects with the thought of equally educating professional dental technicians together with us. The field practice system is subject to reinforcement so that our students have more opporunities of utilizing the tools and materials for practice. Finally we should not only carry out new reserch more deeply no less than dental technicians who are experienced in business for development of education system but endeavor to meet pratical education by adding what is pratically needed in dental laboratories to the existing education system.
A Study on the Improvement of Syllabus for Dental Technology Education
Sung, Hwan-Kyung ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 165~187
We are studied the improvement syllabus of subjects in demtal technological curriculum that those are Tooth Morphology, Science of Dental Materials, Inlay Technology, Occlusal Anatomy and Dental Orthodontic Technology. Those improvement syllabus will be contributed to the achievement of national educational standards and arrangement to the technical performance of medical imaging procedure with the smallest exposure dose and the personal attributes of compassion, courtesy and concern in meeting the needs of the patients, and have a good knowledge of the dental technician professional competence.
A study on The Dept. of Laboratory Dental Technology Students Conclusion of College Life
Kim, Yeoun-Soo ; Shin, Mo-Hak ; Choi, Un-Jae ; Song, Yun-Hee ;
Journal of Korean Acedemy of Dental Technology, volume 21, issue 1, 1999, Pages 189~208
This is a study of view of college life on 1002 students in the dept. of the dental laboratory technology of 8 colleges in the country. Made a question survey on conclusion of college life, such as purpose of entering college and satisfaction, college life and sense of values and relationship to professors and analysed it through statistics. 1. Purpose of entering college and satisfaction of college. Most students motive to enter college was a preparatory step for future job as 73.3% of reponse rate. The dissatisfaction of college after entering was 42.5%, students of the metropolitan area showed 47.1%(p<.01) of response rate and college woman showed 48.2%(p<.05) of response rate. As for the datils of dissatisfaction of college than expected, the absence of romanticism and academic atmosphere was 38.1% and poor practice(facilities) was 32.4%. the students of the metropolitan area showed rater high rate(p<0.1) and sophomore students showed high rate(p<.05) as 40.6% 2. College Life and sense of values. Students showed the greatest interest in employment(27.0%) during attending and in deciding future plan(26.9%) after graduation. They responded a desirable attitude as a college students was a active and autonomous attitude as 34.0%. The best image of a college student was a student helping his/her peers with deep interest as 65.5%. The greatest trouble in college life was still future plan(27.7%). 3. Relationship to professors. Most responded they did not have professors to consult in the department as 72.4%. As a reason for this, insufficient oppartunity to talk with professors was the highest as 29.8%. They wanted any professor with much interest in employment of students as the best image of a professor(40.7%) and wanted to come into close relation with professors(30.9%).