The popularity of Ni-Cr-Mo based metal alloys for metal-ceramic crown have increased recently because of low price, superior yield strength and rigidity. the use of these alloys give them the potential advantage of thinner copping with the required rigidity for long span bridges. The purpose of this study was to assess the microstructures and mechanical properties of Ni-Cr-Mo-(Si,Al,Nb,Zr,Ti.Cu,Mm) based Alloys not containing beryllium(Be) related toxic effects. The abtained results indicated that as-cast these specimen alloys showed compositional and microstructural differences, and mechanical properties values of Ni69Cr20Mo5Si2Al4 alloy among these specimen alloys was found to be superior to those of commercial Ni-Cr based alloy using in market place today.

Free-end partial dentures, which are supported by teeth surrounded by dental root membranes and elastic mucous membrane tissues, may cause stress to the abutment teeth due to external force imposed on the denture base, increase the mobility of the abutment teeth, and bring about a change in the periodontal tissue. General retainers used in partial dentures are categorized into clasp, attachment, and Konus crown. Stress imposed on the abutment teeth and mobility of the denture base have relations with the lifetime of a crown and abutment teeth, and have direct relations with the chewing ability. Thus, a need arises to make a comparative analysis of stress of the three direct retainers on the abutment teeth and interpret the mobility of the denture base. This study designed three kinds of removable partial dentures (one kind of attachment partial denture, one kind of Konus crown partial denture, and one kind of clasp partial denture), and fabricated Dentiforms of bilateral partial dentures (Kennedy Class I) with lower left 1st premolar and lower right 1st and 2nd premolars being as the abutment teeth. A strain gauge was installed in the mesial and distal surface of the lowerr left 1st premolar (No. 34) of the fabricated dentiform and in the lower part of the denture base, and installed were a clasp partial denture, an attachment partial denture, and a Konus crown partial denture. Then, the vertical static load of 5kgf and 7.5kgf at the occlusion surface of the lower left No. 6 molar was generated for a total of 20 frequencies of load each using a push-full gauge, and thus a change in the output of the strain gauge was measured. With the respective application of Konus crown, attachment and RPI clasp in the free-end partial denture, surveyed was the distribution of stress imposed on the abutment teeth and the denture base according to the location of occlusion force load so as to come up with the following results. 1. Konus crown and attachment partial dentures generated much stress, and more stress on the abutment teeth than RPI clasp dentures did. Attachment dentures tended to further intensify stress on the abutment teeth than Konus crown dentures did. 2. Attachment dentures and Konus dentures imposed less stress on the denture base than RPI clasp dentures did. There was no stress difference between Attachment and Konus crown dentures. 3. Dentures that were designed with the application of retainers using sturdy linkage methods tended to be less mobile.

The Purpose of this study was to compare the distribution of implant fixtures according to length and diameter between screw-retained and cement-retained implant-supported fixed prosthesis and to asses whether prosthesis retained types affected the selection of size of implant fixtures. This study presents a follow-up 2,416 implant-supported fixed type prosthesis that have been screw retained or cemented retained for about 10 years in 14 dental clinics. Included in the study were 458 men and 397 women and implant fixtures used in this study were screw retained type 1,057 and 1,359 of cemented retained type. The statistical results among the diameter types of fixture by prosthesis retained type was no significant difference noted (P= 0.809) and there was significant differences was enough to among the lengths of fixture by prosthesis retained type (P= 0.020). However there were no significant difference among the fixture diameter types and length by prosthesis retained type (P= 0.486). So there was not affected to prostheis fixation mechanism for the size of implant fixtures.

The purpose of this study was to determine if repeated casting has a detrimental effect on the corrosion behavior of nickel-chrome casting alloys. The X-ray diffraction analysis, vickers hardness test, SEM, EDX and corrosion test were performed to determine the effects of recasting on chemical composition, microstructure, physical property, castability and corrosion behavior of nickel-chrome casting alloys. The X-ray diffraction analysis results for the cast and recast specimens of the VeraBond and the Rexillium V showed that major crystal phase contained nickel-chrome compounds, Nickel carbide and Chrome carbide. Microstructure analysis results for the cast and recast specimens of the VeraBond and the Rexillium V showed recasting has no effect on microstructure. EDX analysis results indicated the percentage of the main component nickel(Ni) in the specimens of the VeraBond showed a tendency to increase with recasting, but those of other components Carbon(C) showed a tendency to decrease with recasting, Chrome(Cr), Silicon(Si), Aluminium(Al) and molybdenum(Mo) showed no changes in the percentage. The percentage of the main component nickel(Ni) in the specimens of the Rexillium V showed a tendency to increase with recasting, but those of other components silicon(Si), carbon(C) and molybdenum(Mo) showed a tendency to decrease with recasting, chrome(Cr) and aluminium(Al) showed no changes in the percentage. The vickers hardness results for the cast and recast specimens of the VeraBond and the Rexillium V showed a tendency to decrease with recasting, but the differences for the first to fifth cast were not statistically significant. The castability results for the cast and recast specimens of the VeraBond and the Rexillium V showed a tendency to decrease with recasting, but the differences for the first to fifth cast were not statistically significant. The cast and recast specimens of the VeraBond and the Rexillium V showed no differences in the corrosion resistance. The results indicate that the VeraBond and the Rexillium V can be safely recast.

This study was performed to observe the flow change of the inlay waxes at various temperatures. The flow of inlay waxes was tested according to the treatment conditions, for 10 minutes at 40$^{\circ}C$, 41$^{\circ}C$, 42$^{\circ}C$, 43$^{\circ}C$, 44$^{\circ}C$, and 45$^{\circ}C$ The flow of inlay waxes at various temperatures was measured with an electro dial gauge. The results were as fellows: 1. The flow change of the inlay waxes at various temperatures was shown to increase in the order of wax A, B, D, C. 2. Wax A was close to ADA specification with 3% flow at 40$^{\circ}C$ and 71% flow at 45$^{\circ}C$, but wax B and D did not reach up to ADA specification with 40% flow at 45$^{\circ}C$. 3. Wax C came up with 3% flow at 40$^{\circ}C$ and 7% flow at 45$^{\circ}C$, and it revealed a very low flow change at 5$^{\circ}C$.

The main purposes of this thesis are to examine the job satisfaction of dental technicians, to explore the factors which have impacts on the job satisfaction of the dental technicians, and finally to address some suggestions for dental technicians in order to improve their job satisfaction. This study is based on the survey data which were conducted among dental technicians engaged in the dental technical places in Daegu area from March 1, 2003, to March 31, 2003. Three hundreds and twenty questionnaires were distributed and 304 of them were collected. Among them 293 questionnaires were eventually used for the statistical analysis. Descriptive and regression analysis were introduced, and in which 12 independent variables and one dependent variable were included. The results of this study are as follows: Approximately 50 percent of the dental technicians in Daegu expressed that they were satisfied with their job, while about 20 percent of them were not satisfied with their job. According to the multiple regression analysis, work environment($\beta$,=0.216), human relationship($\beta$,=0.405), and self-esteem($\beta$,=0.156) have statistically significant positive effects on job satisfaction. On the other hand, conflicts caused in the process of carrying out their jobs have statistically a significant negative effect($\beta$,=-0.166) on job satisfaction. Among 12 independent variables, human relationship has the strongest effect($\beta$,=0.405) on job-satisfaction and 12 independent variables explains approximately 35 percent of variance in the job-satisfaction of dental technicians in Daegu. In conclusion, with regard to the improvement for the job-satisfaction of dental technicians, the association of dental technicians' active concern and long-term plans are necessary. Finally, some suggestions for the increase of the level of job satisfaction of dental technicians are introduced and discussed.

This research collected the curriculum for Dental Technology from a total of 20 schools-eighteen 3-year colleges and two 4-year colleges all in Korea. We divided 4 groups as regions from 20 colleges, and we compared the credit of university students who finished all the required courses and want to apply for a national examination and the credit to be had from another educational institution. As a result of this analysis, we get the conclusion below: 1. In the curriculum, average credit are shown like this order: Science of Dental materials 5.45 Orthodontics Technology 4.10 Dental Morphology 3.80 Oral Anatomy 3.05 Dental Health Science 2.45 Public Health Science 2.40 These show that the credit of fundamental studies, which is in order to take Dental Prosthetics, is increased. 2. In the curriculum, average credit are shown like this order: Crown and Bridge Technology 7.25 Removable Partial Dentures Technology 6.55 Complete Dentures Technology 6.40 Dental Ceramics 4.95 Inlay Technology 2.30 3. In the curriculum, average credit are shown like this order: Crown and Bridge Technology(Lab) 5.90 Removable Partial Dentures Technology(Lab) 5.35 Complete Dentures Technology(Lab) 5.30 Dental Ceramics(Lab) 4.35 Average points between regions in the subject of a national written exam are mostly similar, but the deviation among Science of Dental Materials, Crown and Bridge Technology, Removable Partial Dentures Technology, and Complete Dentures Technology is large. And in the practical technique exam, the deviation among Crown and Bridge Technology(Lab), Removable Partial Dentures Technology(Lab), and Complete Dentures Technology(Lab) is great.

The purpose of this study is to provide basic information about oral health behavior of dental technology department students. Questionnaire surveys were conducted for 925 dental technology department student. Their knowledge and attitude towards oral health and health education services utilization were surveyed. The results obtained were as follows; 1. Ever thought most of the students recognized that oral health was an important health issue, there were more subjects who lowly regarded the level of the perceived self-oral health knowledge than who regarded highly. Female students were negative on the state of their oral health than male students. 2. On the water fluoridation program, 52.2% of the respondents replied that they do know well about the program and 44.1% of them supported the execution of the program. Female students approved of fluoridation program than male students. 3. Number of mean tooth brushing was 2.71 times a day, the most frequently exhibited time of doing tooth brushing was after taking a breakfast or before going to bed. 4. The students who had experiences of visiting dental clinics for the past 1 year were 47.7% and the purpose of visiting dental clinics for the last time was to conduct caries treatment.