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Using a nickel-chrome casting alloy called 'Rexillium V' which is also available as base metalalloy for dental ceramic crown, 4 types of mixtures(A, B, C, D) with old and new metal wereprepared for cyclic casting. The results of cyclic casting can be outlined as follows: 1. For Vickers hardness after casting, specimen A and D tended to have lower hardness in thecourse of cyclic casting, while specimen B and C tended to higher hardness. 2. The results of X-ray diffraction analysis showed that major crystal phase contained nickel-chrome compounds and carbide. 3. The observation results of SEM photographs after cyclic casting show that there was asignificant tendency to have similar structures among experimental groups. 4. The results of EDX analysis after cyclic casting showed that there were little differences inchemical composition between parent metal and base metal alloy.Although industrial nickel-chrome cast alloy did not show any significant change in materialproperties even through cyclic casting over several times, it is recommended that more there bemore in-depth studies on how to detect any potential corrosion, discoloration and toxication ofdental ceramic crown implanted in patient's oral cavity.

The purpose of this study was to process bio-active glass ceramic composite, reinforced withsapphire fibers, by hot press. Also to study the interface of the matrix and the sapphire fiber, andthe mechanical properties.Glass raw materials melted in Pt crucible at 1300during 3.5 hours. The melt was crushed inball mill and then crushed material, ground and sieved to <40ß. Sapphire fibers cut (30) andaligned.Powder and fibers hot pressed.The micrographs show good bonding between the matrix and the fiber and no porosity in theglass matrix. This means ideal fracture phenomena. Glass is fractured before the fiber. This isindication of good fracture strength.EDXS showing aluminum rich phase and crystalline phase. Bright field image of the matrixshowing crystalline phase.Also diffraction pattern of TEM showing the crystalline phase and more than one phase.Strength of the samples was determined by 3 point bend testing. Strength of the 10vol% samplewas approximately 69MPa, while strength of the control sample is 35MPa.Conclusions through this study as follow: 1. Micrographs show no porosity in the glass matrix and the interface. 2. The interface between the fiber and the glass matrix show no gaps. 3. Fracture of the glass indicates characteristic fiber-matrix separation. 4. Presence of crystalline phase at high processing temperature. 5. Sapphire is compatible with bioactive glass.

This study was aimed to verify a comparison by dental alloys upon the marginal fitness of dentalprosthesis. Firstly, we waxed up on 45 epoxy resin dies, pressed the margin with hands, andidentified the marginal fitness with microscope. And we made a single direct spruing system typeof sprue by 3 dental alloys - metal crown alloys, PFM crown alloys, and gold crown alloys - each15, total 45 waxing up, adjusting W/P ratio and invested the cast ring. Then, we made the dentalprosthesis using the electric casting machine. In these processes we followed the manufacturer'sinstructions, in order to maintain the other conditions from the inner and outer, which includedinvestment and burning out. After we tried on the dental prosthesis on epoxy resin dies, we havegot the means of marginal gap at 9 points with same distances, around the cervical line which waschecked already, using microscope(300). The results of this study were as follows :1. Metal crown alloys showed 2.9% better in marginal fitness than PFM crown alloys, and thedifference was not statistically significant(P=0.497). 2. Gold crown alloys showed 31.3% better in marginal fitness than Metal crown alloys, and thedifference was statistically significant(P=0.004).3. Gold crown alloys showed 32.4% better in marginal fitness than PFM crown alloys, and thedifference was statistically significant(P=0.002).4. We saw that Gold crown alloys was the best dental alloys in the marginal fitness among thethree.(P=0.049).

In this research, we manufactured the paste opaque porcelains using Propylene Glycol (PG) andButhylene Glycol (BG) as a solvent, and compared the composition of solvents, the coefficient ofthermal expansion, the particle size distribution, the viscosity and bonding strength to metal, andthe tone with those of the commercial products(Duceram Plus, Duceram GmbH; VMK 95, VitaCo.; Noritake EX-3, Noritake Co.)used in the clinical field. The results of the research were as follows: 1. The result of solvent analysis indicated that the solvents included in the paste opaqueporcelains of the control group were mainly composed of Glycols.2. From the Coefficient of thermal expansion measurement, we drew out the following results;testing group: 14.010-6/, Duceram Plus: 13.910-6/, VMK 95: 14.310-6/, and NoritakeEX-3: 13.310-6/.3. Seen from the result of particle size distribution measurement, the experimental group was similar to the control group in 1㎛below, but the experimental group marked the highestdistribution of 61% in the case of between 1㎛and 5㎛. Between 5㎛and 10㎛, they showedrelatively similar distribution, and Noritake EX-3 was turned out the highest distribution of 29% in10㎛above.4. From the result of viscosity measurement, Duceram plus showed the highest viscositythroughout all the measurements followed by Noritake Ex-3, experimental group and VMK 95 indecreasing order.5. The result of bonding strength measurement was EX 35.53 ßÁ, DU 40.88 ßÁ, VM 39.43 ßÁ,and NO 35.39 ßÁ, and no significant difference was found between the experimental group and thecontrol groups(P>0.05).6. The measurement of the tone indicated that the L* value of the experimental group was 86.890.63 in average, which is higher than the control group in its brightness. In the case of the a* value,Duceram Plus, VMK 95 and EX-3 showed positive value, whereas the testing group was turned outnegative value. In b* value, Duceram Plus proved the highest. From the results of this research, the paste opaque porcelains using Propylene Glycol (PG) andButhylene Glycol (BG) as a solvent did not make differences from the commercial products thatare actually used in the clinical fields. Therefore, it is possible to utilize Propylene Glycol (PG) andButhylene Glycol (BG) for the paste opaque porcelains of P.F.M crown. It is also recommendedthat further researches concerning the compositions and forms of powder, the types of organicsolvent components and the ratio of mixture proceeded in order to improve the level of productivityin the future.

The microstructure and hardness of a porcelain fused Au-Pt-Cu-In alloy was investigated usingoptical microscopy, secondary electron microscopy, electron probe microanalyzer, transmissionelectron microscope, and vickers hardness. The hardness of the heat-treated Au-Pt-Cu-Inquartenary alloy reached a maximum value in 30 min at 550in the range of 150 to 950. In theaged Au-Pt-Cu-0.5In alloy at 550, the hardness of the alloy rapidly increased until 30min withincreasing aging time and after that it was remained nearly constant value. Based on above results, glazing and final aging of the porcelain fused Au-Pt-Cu-0.5In alloy wereperformed at 920 and 550, respectively. The hardness of Au-Pt-Cu-0.5In alloy glazed at 920was 90 Hvand that of the alloy aged for 30 min at 550increased to 160 Hv. This indicates that aceramic-metal crown with high strength can be manufactured using the glazing at 920andfollowed final aging at 550for 30 min.

The purpose of this study was to investigate bond strength of denture base resin repairedaccording to contamination. One commercial denture base resin and two different kinds of relinesresin were tested; Lusiton 199(denture base resin), Vertex(reline resin) and TokusoRebase(repairresin). The specimens were processed according to the manufacturer's instructions to cured denturebase resin(polymethylmethacrylate; PMMA) and reline resin. Bond strengths were examined byuse of a three-point transverse flexural strength test. Data were analyzed with two-factor analysis ofvariance and Duncan's post-hoc test at =0.05. Generally, the bondstrength of heat-curedresin(Lusiton 199) was higher than the other resins. The contaminations produced an decrease inbond strength. Therefore the contamination, such as saliva or water must be avoided during thelaboratory repair procedures.

Ti-20%Zr-X%Cr(X=0,5) based alloys not containing hamful Al and V were newly designed inorder to reveal their possibility for dental casting alloys, and melted in argon-arc casting machine.The mechanical properties were evaluated by using universal testing machine. The tensile strengthand %elongaton of the alloys markedly increased with Cr content. The Ti-20%Zr-5%Cr alloyshowed a similar tendency with Ti-6%Al-4%V alloy in tensile strength, but surpassed in%elongation. From these results, it was concluded that new alloys for successful dental castingmaterials should be designed as Ti-Zr-Cr based alloys.

The use of titanium alloys as biomaterials is increasing due to their superior biocompatibility andenhanced corrosion resistance compared to conventional stainless steels and cobalt-based alloys.Ti-6Al-4V (+type) alloy instead of pure titanium (type) is being widely used as biomaterialshas some characteristics such as high fatigue strength, tensile strength and corrosion resistance. Italso has similar characteristics to Ti in inducing bony ingrowth. But it has been reported recentlythat the vanadium element expresses cytotoxicity and carcinogenicity and the aluminium element isrelated with dementia of Alzheimer type and neurotoxicity. In order to overcome their detrimentaleffects, -phase stabilizer Nb was chosen in the present study. CP-Ti(ASTM grade 2), Ti-3wt.%Nb(type), Ti-20wt.%Nb (+type) and Ti-40 wt.%Nb(type)alloys were melted by vacuum arc furnace. Biocompatibility of Ti-Nb alloys was evaluated bycytotoxicity test.The results can be summarized as follows:1. For the cytotoxicity test, Ti-Nb alloys showed excellent biocompatibility compared to CPTi(ASTM grade 2), 316L STS and Co-Cr alloys.

The purpose of this study was to show occlusion on the simple hinge articulator optionallymounted. Modelling of upper-lower jaw and simple hinge articulator were developed. This modelling ofupper-lower jaw inserting wax bite was mounted imaginary on the modelling of simple hingearticulator by use of the computer simulation. From changes of THA(transverse horizontal axis)-incisor distance, Balkwill angle and THA deviation, eight types were mounted respectively. Afterremoval of wax bite, upper-lower jaw position changing were compared with centric jaw relation. The results were as follows:1. The change of THA-incisor distance had influence on mostly a vertical shift of upper jaw.2. The change of Balkwill angle had influence on mostly a horizontal shift of upper jaw.3. Inferior type in the THA deviations was the least shift of upper jaw.The above results suggest that the simple hinge articulator optionally mounted effect a shift ofupper jaw.

The purpose of this study is to ensure natural restoration of gingiva's form by making effectiveuse of materials in a bid to improve the technique of festooning for denture base.1. The improved technique is expected to prevent the degradation and deformation of cavitystructure and restore it.2. The improved technique is expected to prevent the change of facial appearance from estheticviewpoint and restore it.3. The improved technique is expected to impress again the deformed part on wax denture foradditional festooning.

I measured the movement range on the hinge articulator and the movement range in an oral. Andthen I studied to analyze the gap. I got wax records by the movement on the hinge articulator, themovement in an oral and the movement on the hand articulating. I measured the distance of thecusp tips that are close to the mesial direction and the distal direction, the buccal direction and thelingual direction then I compared gaps.As I saw results on data, I knew that the hinge articulator represented the range of mandibularmovement restrictively. I could find the decisive contradiction that the sliding movement finishedon the hinge articulator although it did not finish in an oral. If the sliding movement does notreappear exactly, it brings a fatal failure to the dental prosthesis. In addition it is impossible that thehinge articulator restores the movement in an oral because the lateral condyle inclination and thehorizontal condyle inclination are fixed previously. Therefore dental prosthesisses were made bythe hinge articulator, they will interfere with a mastication.I have obtained the following results;1. The distance of sliding movement on the hinge articulator showed shorter than the distance ofsliding movement in oral. This means the increase of cusp inclination of the dental prosthesis thatwas made on the hinge articulator. Therefore, when the lateral movement occurs in oral, there is apossibility to become the premature as the increase of cusp inclination. 2. The results that were impressed records in oral and impressed records on the hand articulatinghave many congruities. I think that the simple crown etc. that were made by the hand articulatingmethod except the long span bridge and the free end case that can not measure the verticaldimension exactly can represent similarly the mandibular movement.3. If we want to represent the mandibular movement similarly, we have to use the articulator thatcan adjust the horizontal condyle inclination and the lateral condyle inclination at least.

In the present work the knowledge of dental health as well as dental prosthesis has been studiedon the basis of analysis of current dental prosthetic treatments for dental diseases prophylaxis andthe final decision for dental prosthetic appliance. The results have been analyzed by the currentdental health care and the subjective acknowledgement from 700 people of urban as well as ruralinhabitance 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 beeven worse than health status. It has been shown that the dental prosthetic treatments have been mainly caused by the oraldisease (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 themost 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 frequenly visited asindicated 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 beentreated by the un-licensed dentists. In point of view on the cost for dental prosthetic treatments, 93.1% have claimed to be tooexpensive, 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 and9.2% was dissatisfied. Most of people experienced increasing levels of satisfaction as their incomeincrease. Most in the age range of 40-60 have wanted to be insured for the dental prosthetic treatments. Itis alos interesting to note that the older age and the less educated wanted to apply this kind ofinsurance.

In this study, the data and the Statistical Annual Report of the Korean Dental TechnologyAssociation and the yearbook of Health-Welfare Ministry from 1990 to 2002 were surveyed tostudy and analyze the yearly increase rate and regional distribution rate of the national dentallaboratories and dental clinics, the rate of dental laboratories to dental clinics. The purpose of thethesis is to help dental technicians to open the rational and effective dental laboratory whichconsiders the regional condition and the distribution of dental clinics. The result of the study is asfollows; 1) The yearly increase rate of overall dental laboratories is 2.01 times to 2002 by the criteria of1990. The most laboratories was increased in 1995(+94) but the least laboratories was increased in2000(+13). According to the regional increase rate, Kyounggi Association showed the highestincrease rate (7.00 times) but Woolsan Association showed the least increase rate (1.45 times) forthe past 5 years. Busan Association had increased by 1.47 times by the criteria of 1990.2) According to the regional distribution rate of dental laboratories, Seoul area showed thehighest distribution rate from the minimum 26.72%(in 2002) to the maximum 35.23%(in 1990)every year, and before 1993, Busan area showed the high distribution rate of 12.49% and Daeguarea 12.38%.3) In the case of the national increase rate, dental clinics had increased by 2.01 times to 2001 bythe criteria of 1990 and dental laboratories, whose number was 1,482 in 2002, had increased by2.01 times to that year. The rate of the national dental laboratories to dental clinics went up an average of 1: 7.57 for 12years. In 1994, the rate showed the highest 1:7.91 and in 1990, the rate showed the least 1:7.17. 4) The metropolitan rate of dental laboratories to dental clinics showed the average of 1:6.70 for12 years, and the rate was highest in 1992(1:7.15) and the rate lowest in 1999(1:6.33). 5) The rate of dental laboratories to dental clinics in other areas was 1:9.53, the average of 12years and was highest in 1991(1:9.97) and was lowest in 1990(1:8.79).(6) The rate of the Korean dental laboratories to dental clinics was 1:7.37 in 2001, themetropolitan rate was 1:6.53 and the rate in other areas was 1:9.10. According to the regionaldistribution rate, the rate of Kyounggi was highest (1:15.58) and the rate of Daegu waslowest(1:3.03)

The purpose of this study is to examine the effect of parents knowledge on oral health status toward their children.This study was carried out to investigate and analyze the cognitive degree of dental subjects andgeneral public who have an experience to be treated for their dental knowledge, operative dentistry,and dental prothesis in the oral health care through the questionnaires.The results are as follows : 1 : In questioning the frequency in the visitation of dental clinic, 68.8% usually go to see dentists,if children’s teeth have trouble. It was the reason that economical standard and educational levelwere enhanced as before. 57.6% took a kind of medical measures.2 : In surveying the preference of dentists’age or gender, 56.9% preferred younger dentists toolder or female dentists. On the contrary, 56.9% children want younger dentists, and 64.8% children want female dentist doctor. As a conclusion, the preference of dentists’age or gender is relevant with a view to remove bighorror, which can be evoked by dental measures.3 : In questioning the possession amount of decayed teeth, 45.8% have more than four. Usually those parents who have children filled their decayed teeth with artificial or installed with dentalprosthesis.As a conclusion, age is relevant in this study in p〈0.05 level.4 : In asking for efficient starting-year of tooth brushing, 42.6% said that 2 or 3 year age is themost efficient, and especially 80.6% teach children to learn brushing themselves. (P〈0.05)As a conclusion, the voluntary brushing can be good behaviour for good dental health.5 : In surveying the way they obtained dental information, 38.9% were given form mass media,but 90% were once not delivered with the education of dental health. Because parents have beenknown narrow and deficient information of dental health through mass media, experts in dentalhealth have to deliver help their parents to be delivered with systematical dental information.The conclusion of this study can be summarized that parents' role is very important to theirchildren's tooth health and the education program for systematical dental information should bedelivered to their parents.

This study mainly intends to determine the factors for which dental technicians are satisfied withtheir jobs and how much the resulting job transfer rate is and thus to identify the correlationbetween them.For these purpose, 200 subjects were sampled out of dental technicians in Seoul and Incheon, andthe survey was performed from July 19, 2002 to August 15 (for 25 days) with self-administeredquestionnaire. Out of all collected questionnaires, 131 pieces(65.5%) were addressed for this study. As for the tools for this study, the structured questionnaire was used with its proven reliabilityand feasibility, and the contents of questionnaire consisted of 32 questions on the basis of relatedreferences. The contents of questionnaire were categorized into 3 sections: General attribute of subjects;Factors for which dental technicians are satisfied with their jobs; and their intention of job transfer.The questionnaire consisted of total 32 questions which included general attribute of subjects(10questions), factors of their satisfaction with jobs(17 questions) and intention of job transfer(5questions). The data analysis was processed by computerized system with SPSS(Statistical Package forSocial Sciences). Statistical analysis techniques included frequency, percentage, T-test, F-testanalysis and regression analysis. As a result of those analyses, the conclusion can be summarized as follows: 1. As a result of analyzing the factors for which the subjects were satisfied with their jobs, it wasfound that there were significant differences in career and job title out of question items(P<0.001).It was also shown that the factors of subjects' satisfaction averaged 3.43, which was considerablyhigher value than I expected. It was found that job and management factors were major jobsatisfaction factors. 2. As a result of analyzing the intention of subjects to decide their job transfer, it was found thatthere were significant differences in job title and marital status out of question items(P〈0.001).It was shown that the total average of the intention of their job transfer amounted to 3.06. It wasshown that dental technicians have relatively higher intention of job transfer from their currentwork place. 3. It was found that there was inverse correlation between the factors of subjects' satisfaction withtheir jobs and their intention of job transfer(r=-0.490, P〈0.05). Likewise, it was also found thatthere was inverse correlation mostly between the evaluation value for each independent variableregion in term of each factor of job satisfaction and the value for the intention of job transfer. Inview of these correlations, it was concluded that higher job satisfaction likely led to lower jobtransfer. 4. As a result of regression analysis so as to determine the influences of job satisfaction factorson the intention of job transfer, it was found that the highest influential factor was managementfactor. And it was shown that the test values of model were statistically significant and itsexplanatory power amounted to 54.6%.

The purpose of this study was to investigate the relationship of empowerment, self-efficacy andturnover intention of dental technicians. The subjects of this study were selected by haphazardsampling and the size was 142 of the dental technician. The results were analyzed with spss/pc+ and the conclusion is as follows ;1. The mean of dental technicians empowerment was 3.24, Self-efficacy was 3.51, and theirturnover intention was 2.72.2. In characteristics of subjects, turnover experience and position are significantly different inempowerment.3. In characteristics of subjects, a working experience, income, position, marriage and turnoverexperience are significantly different in self-efficacy.4. In characteristics of subjects, a position and a working experience are significantly different inturnover intention.5. Empowerment showed a positive correlation with self-efficacy and a negative correlation withturnover intention.The above results is different from other empowerment studys which empowerment is relatedwith self-efficacy and turnover intention. The study on empowerment is important in the aspect ofstratege for increasement of work performance.

The 3 year graduate school course of the dental technician, which has been enforced since 1994till the present date, differs from the currently existing 2 year graduate course because of an 8weeks clinical field training course being newly executed and an imposed curriculum aboutmanufacturing specialized prosthetics like all-ceramic, double prosthetic technology, attachment,and implant. Even though nearly 10 years have passed, the education program of the 18 collegeshave still not been standardized and the subjects differing a little, while some are still not followingthe 3 years graduate course.The goal of this research is to emphasize the qualities of the 3 years graduate program andenable the dental technician to handle clinical models in the dental technical clinic right aftergraduation by adding clinical field training in the dental technician education program of the 18colleges. Also in accordance to a national and international increase in esthetical prosthetics,credits, weekly study hours, education practice time of specialized prosthetic dental technology canbe analyzed as follows.1. In the year 2003, currently colleges start clinical practice education starting from the 1stsemester of the 2nd year junior year, to the 2nd semester of 3rd year the varying in time withadequate class time, and credits. The average credit is 9.56, and weekly average class time is 18.00 hours. later clinical trainee education will be adjusted to the 3 year graduate school course to 10credits and 20 hours and the adequate education period should be the 2nd semester of 3rd gradewhen most basic clinical education has been covered.2. Currently in the year 2003, all-ceramic education has an average credit of 8.01 in 17 collegeswith an exception of Ma-san college. The weekly average theoretical education is 4.94 hours,weekly clinical education of 7.88 hours and currently in 14 colleges porcelain technical classusually starts in the 1st semester of the 2nd year. All-ceramic education is thought to have adequatecredits, timing, and weekly study hours.3. Currently in 2003 implant education is enforced in 11 colleges including Bu-san Catholicuniversity and the education period is usually in the 3rd year. Out of the 11 colleges, only Bu-sanCatholic univ., Ma-san and Shinheung college have practice training classes. We knew that Shingu,Dongu, Mokpo science colleges have practice training as a curriculum, namely specific prostheticslaboratory. Out of the 9 colleges enforcing implant education the average credits taken are 2.56,and the average hours of weekly theory education is 2.14, but with the exception of Shinheungcollege which has an implant practice training course theory and practice classes are not divided.Therefore implant education is thought to start in the 3rd year as a 3 credit course with 3 hours oftheory and practice each.4. Currently in 2003, theoretical attachment education is given in 15 colleges and includingpractical training it is given in 10 colleges. The education starts 1st semester of the 2nd year till the2nd semester of the 3rd year. The average credit of attachment theory education in the 15 collegeswas 3.64, the average weekly theoretical education was 2.64, and the average weekly practicetraining out of the schools teaching it was 3.20. Later attachment education is thought to start the1st semester of the 3rd year as a 3 credit course with 2 hours of theory class and 3 hours of practicetraining. 5. Double prosthetic technology is currently carried out in Dae-jon Health Science college(2ndyear 2nd semester, 2 credits, theory 2hours), Gimcheon college (1 credit, 2 hours of practicaltraining), Bu-san Catholic university (4th year 2nd semester, 4 hours of theory. practice). When the3 year course is enforced, education will start 1st semester of the 3rd year with 2hours of theoryand practice each. 6. The newly installed programs of the 3 year education is clinical field training, and specializedprosthetic manufacturing practice like all-ceramic, double prosthetic technology, attachment, andimplant. If such education is to be effectively managed, a primary precursor as systemic basicclinical education is thought to be important. 7. Nationally in the 18 colleges of dental technology the currently executed curriculum coursehad varying subjects, class time according to the subject, and credits by each college. Thecurriculum difference between the colleges must be settled.