Earticle

The purpose of this study was to investigate the change of microstructures and mechanical properties of pure titanium casting specimens as a function of mold temperatures. The pure titanium castings were fabricated using the centrifugal vacuum casting method with different mold temperatures of 200~500℃ . The resulting castings were characterized by optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and vicker,s hardness tester. In case of the mold temperatures over 400℃, the porosity, surface crack and large grain size were observed in resulting castings. In this work, The most suitable mold temperature in casting of pure titanium was 300℃.

The aim of this study is to make some basic materials to find retention force difference based on the total height of CAD/CAM zirconia abutment used for implant, retention force difference based on how to regulate the height of the abutment, retention force difference based on the size and retention force difference based on the design group. The retention force was measured by being pulled at the speed of 1mm/min after being combined with zirconia block and abutment using Temp-BOND of Kerr. The experiment was done at the research lab of OSTEM in Busan by useing UNIVERSAL TESTING MACHINE on March 3rd, 2010. The final conclusion was reached as follows through analyzing the amessed results. 1. After analysing the total height and the retention force, p-value had minor difference by 0.01 statistically. Namely, 3㎜, 4㎜, 5㎜ had the retention force difference and we could see retention force difference on 3㎜ and 5㎜ at the post test. 2. After analyzing how to regulate the height and retention force, p-value had minor difference by 0.000 statistically. Namely, 1㎜ and 2㎜ had the retention difference and we could see that 1㎜ and 2㎜ with the total height had retention difference. 3. After analyzing the retention force based on the size, p-value had minor retention force difference by 0.000 statistically. Namely, 7 different size had retention force difference and we could see the size 21.9㎜, 32.9㎜, 32.9㎜, 38.4㎜ , 48.9㎜ and 54.9㎜ had retention force difference. 4. After analyzing the retention force based the design, p-value had retention force difference by 0.000 statistically. Namely 9 different design group had retention difference and we could see that 9 design group with 5.6.7.8 design group and 9 design group with 1.2.3.4. design group had retention force.

Purpose: The purpose of this study was to investigate the correlation between zirconia core thickness and color tone blocking of discolored tooth and metal post. Methods: For this study, we made 20-porcelain sample and 4-metal sample( liechtenstein IPS e.max) bonded to zirconia core of different thickness with cement(Relyx ARC-3M USA)for produce discolored. We measured the color-spectral characteristics, using Shadepilot equipment(Degudent USA).We measured it with Shadepilot equipment set by automated average mode in 3 times And applied the average value obtained from 2 times of measurement in the middle of each sample. Results: As a result of analysing color-spectral characteristics on zirconia core sample, Depending on the thickness of zirconia core, the value of brightness(ΔL :color-spectral characteristic) was increased within limited range, value of Δa, Δb was decrease. Conclusion: Consequently, we obtained the following results : Changes of sample color were observed depending on the thickness of zirconia, but the range of change did not exceed the scope range of shade guide. The case of metal posts, shade guide color D2 were observed in 0.5 of zirconia core thickness. As a result, in case of porcelain, increasing the zirconia thickness of 0.3 or more is unnecessary for color blocking effect, in case of metal post, considering the discolored tooth, thickness of zirconia with at least 0.5 or more is recommended.

Purpose: This study was performed to compare sintering conditions for fabrication of porous Ti implant. Methods: The porous Ti implant samples were fabricated by sintering of spherical Ti powders in vacuum and atmosphere conditions. Surface morphology, composition and phase were analyzed by FE-SEM, EDX and XRD. Results: Sintered Ti implant in the vacuum consisted of particles connected in three dimensions by clear necking without excessive oxide layers. However, sintered Ti implant in atmosphere was formed excessive oxide layers with non-stoichiometric compounds. Conclusion: The porous Ti implant can be sintered in vacuum condition preferably.

Purpose: This study focused on achieving desired shades by combining zirconia core with different thickness porcelain in order to make dental prostheses effectively. Materials: White and colored LAVATM All Ceramic (3M-ESPE, Seefeld, Germany), and Zirkonzahn (Bruneck, Italy) Trans and prettau were used to have Zirconia. LAVATM Ceram (3M-ESPE, Germany) and ICE (Zirkonzahn, Italy) powder were used to have the porcelain. Methods: Before Match: Stand sample each group 1.2 dentin sample L*, a*, b* value in every dentin and core sample Matched experimental groups: Same thickness dentin + different thickness core Same thickness core + different thickness dentin Results: 1. All L , a , b indexes of zirconia core and porcelain veneer in LAVA group and Zirkonzahn group were different. 2. When you combine the white zirconia core of LAVA group with a porcelain veneer, the thickness of the porcelain must be more than 0.5mm to meet the standard target. 3. When all the colored zirconia cores of LAVA group were combined with porcelain veneers, there was no significant difference from the standard target. 4. When the zirconia cores of Zirkonzahn group are combined with porcelain veneers, the thinner thicknesses were closer to the standard tab than thicker thicknesses; however, there was a significant difference in all combinations, with Delta E * value indicating more than 3. Conclusion: When it comes to colored zirconia, which is the most popular, the thicknesses of both a core and a dentin veneer must be more than 0.3 to get an appropriate shade. There is more possibility to get desirable shades when the thicknesses of a white core are thinner; however, they would be vulnerable to the environment and lose their color. When combine a zirconia core with a dentin veneer, using Zirkonzahn group needs more considerations in order to meet the standard target.

Purpose: The purpose of this study was to evaluate the fracture strength between the core and veneering ceramic according to 2 core materials, In-Ceram Alumina and In-Ceram Zirconia, fabricated by electro ceramic layering technique. 2 different fixed partial denture cores of three units were veneered by veneering ceramic(Ceranion, Noritake) (n=10). Methods: The fracture strengths between the core and veneering ceramic were measured through the 3 point bending test. The interfaces between the core and veneering ceramic were observed with the X-ray dot mapping of EPMA. Results: The result of fracture strength was observed that IZP group, In-Ceram Zirconia core, had higher fracture strength. IPA group, In-Ceram Alumina core, had fracture strength of 359.9( 86.2) N. IZP group, In-Ceram Zirconia core, had fracture strength of 823.2( 243.0) N. X-ray dot mapping observation showed that a major element in the core and veneering ceramic of IPA group was alumina and silica, respectively. No binder was observed in interfaces between the core and veneering ceramic, and no ion diffusion or transition was observed between the core and veneering ceramic. However, apparent ion diffusion or transition was observed between the core and veneering ceramic of IZP group. Conclusion: Therefore, IZP group was evaluated to have the excellent mechanical property.

This study was conducted to investigate the wearing dentures status of the elderly and understand the relationship between demographic sociological properties, oral health care habits, lifestyle, and whether they wears dentures or not. In a surveying of 349 elderly who lives in Daegu and Kyung-pook, following results are obtained. 1. Wearing dentures rates of the aged are 58.5%. 2.The more the aged is female(p=0.025), elderly(p=0.000), a low education level(p=0.000), no job(p=0.006), and a solitary person(p=0.016) the higher rate they wears dentures. 3.The more the aged brushes their teeth after each meal(p=0.029) and uses the oral health devices(p=0.000) the lower rate they wears dentures. 4.The more the aged have dinner alone(p=0.009), do not kept up with the exercises(p=0.000), and would like to dine off a soft food(p=0.000) the higher rate they wears dentures. This study showed that an old people’s condition of oral health care who live in Daegu Kyung-pook is very serious. Therefor not only an elderly but other aged people is need of constant and organized education for taking their oral health care habits and changing their lifestyle. Because wearing dentures rates of the aged by demographic sociological properties, oral health care habits, and lifestyle is lower.

Purpose: This study aims to present practical data available for the effective health management and improvement for the dental technicians by exploring the interrelationships between general characteristics of dental technicians and seven health related habits like drinking, smoking, breakfast, and snacks among the others(alameda 7). Methods: Out of the random selection of the registered dental offices of Dental Technicians Association of Korea, 2,000 working dental technicians were asked to fill out the questionnaire from January 19 to April 30, 2009. We collected the 1,502 sheets of the questionnaire and took frequency analysis, crosstabulation, t-test, and analysis of variance using SPSS Win 12.0 program. Results: Among the seven health related habits, 54.9% of the subject answered ‘never do exercise’ in the question of exercise habits, which is the most problematic of all. Hours of sleep and BMI were found to be quite low. Of the general characteristics, sex proved statistically significant to all the seven habits(p<.001). Marital status, job title, and health check-up showed statistical significance in six items among the seven habits. Age, monthly income, job position showed statistical meanings in five items among the seven habits. The frequency of break showed statistical significance in four items among the seven habits. Working environment showed statistical significance only in the item of hours of sleep among the seven habits(p<.05). Conclusion: This study proved that it is vital to educate the dental technicians to learn the right habits for enhancing their health and quality of life and motivate them to practice those habits.

The work of Dental technician which is part of national dental health, is more specialized recently. This research provides fundamental data from analyzing student’s career consciousness according to needs of a career education. Here is the conclusion of the analysis about student’s career consciousness, that is for a right choice of career. 1. There is a meaningful difference in what they want to know about an occupation according to ages. ( < 0.01) All ages are similar to their occupational thinking, however they who are under twenties consider working environment. Most motives of an entrance are similar, there is a meaningful difference. ( < 0.05) 2. According to a grade of college, there is a meaningful difference how to obtain informations of a career. ( <0.05) Sophomores and juniors obtain information from seniors or family, however freshmen obtain from the internet because of an accessibility. 3. There is a meaningful difference of a job meaning between men and women. ( < 0.01) Men are working for a means of living. But women give weight to a self-development. 4. In an analysis of the correlation which is based on the ages & by regional groups: The older they grow, the more they know about their aptitude. Selecting subjects are different choosing time & motive. According to ages and where they are from, there is a meaningful difference how much know about their aptitude. ( < 0.05) Older Students know more than young students. Selecting subjects are different choosing time & motive. 5. In accordance with a grade, ages, and where they are from, there are different degrees about how much know their interests. There is a meaningful difference of a choosing major period and choosing informations. ( < 0.01) And also there is a meaningful difference where they are from and why they enter to College. ( < 0.001) 6. In accordance with a grade, ages, and where they are from, there are different degrees about how much know their aptitude. There is a meaningful difference of a choosing major period. ( < 0.01) And also there is a meaningful difference why they enter to College. ( < 0.001) Although we know that a career education is very important, however lots of students select a career without their aptitude & interest & character. We need to teach a career education systematically; considering students career consciousness, with a proper career guidance, cultivating career consciousness.

Purpose: The purpose of this study was to examine the eyesight and life habits of college students in an attempt to provide some information on the protection of their eyesight. Methods: The subjects in this study were 311 students in the department of dental technology at a college of health, on whom a survey was conducted. A crosstabulation analysis was carried out to show the joint distribution of general characteristics and several variables involving the use of glasses or contact lenses and life habits. Results: 77.5% of the students currently wore glasses due to weak sight. 9.3% took an eye test on a regular basis, and 31.2% did that every six months. As for the length of the length of daily mean reading time, 55.3% spent one hour or less reading books. The most common distance between eyes and books during their reading(44.7%) was 21 to 25 . Concerning a reading posture, the biggest group(54.3%) lay down or lay on their face while they read books. 45.0 % spent less than an hour watching TV per day on average, and 27.0% were on the computer for 30 minutes to less than an hour per day on average. The greatest group(63.0%) made use of basic indoor lighting when they were on the computer at night, and 62.1% saw eye doctors to take an eye test. In relation to how to protect eyesight, the biggest group(50.5%) spent less time being on the computer. Conclusion: As the eyesight of college students fails due to reading, TV, computer, and improper ways and posture of doing or using those things, every college definitely should provide education on eye health as one of general education courses.

Purpose: This study evaluated the manpower planning of dental technicians. Methods: Methods : Survey was conducted regarding subject’s general characteristics, characteristics of dental technician’s occupational view and working conditions, and reason to enter into branches of the public health center. The survey sample consisted of 323 dental technicians (221 male/ 102 female). Survey was conducted for one month from August 1 to September 1 in 2010. Following results were obtained. Results: 1. Regarding general characteristics of the subjects, there was a slight male predilection with 68.4%. Subjects in their 40s occupied the highest proportion of 32.2%. Majority of subjects worked in the big cities (71.5%). Favored working places were dental laboratory (57.6%) and dental hospital or dental clinic (19.5%). Although no position is available in the public sector such as public health center or health care civil servant, 9.3% preferred working in the public health center. Public sector is more favored than 2-year technical colleges or dental supply and equipment companies. In respect to education, 57% of the subjects graduated college. 67.8% were married. Subjects who specialize in the porcelain or all-ceramic were 57.9%. With regard to current position, head of the dental laboratory was most common. 2. Following occupation characteristics were found. Economic reason took the highest proportion when deciding their occupation (39.9%) followed by gaining social experience (36.5%). Majority of the subjects (76.5%) wanted to work as dental technicians until their retirement. 71.5% pursuit to become a manager of the dental laboratory. 76.1% agreed on opening a dental technician position in the public health center. Regarding an authority to lead developing the dental technician position in the public sector, majority of the subject chose ministry of health and welfare (35.6%) and Korean dental technologist association (34.7%). Employment (average, 30%) and turnover rate (average, 36.5%) of dental technology college graduates ranged from 40% to 60%. Most important factors for the employment were practical experience (41.2%) and competency (34.4%). With regard to job satisfaction, so-so was 46.7% and satisfactory was 42.7% 3. In respect to the reason for opening a position in the public health center, ‘It is needed to continue denture program for elderly patients’ obtained the highest score (4.14 point). ‘Institutional devices are required to open a position for dental technicians as a public healthcare provider’ received high score (4.11 point). 4. Concerning the working conditions, ‘professional knowledge is required’ received the highest score (4.23) followed by ‘too short maternity and parental leave’ (4.21). 5. Relationship between general characteristics of the subjects and favor of working in the public health center was investigated. Significant differences were found according to the current and favored working area, favored occupation, education level, marital status, and specialty. Working in the public health center was favored by following subjects: working in mid- or small-sized cities (4.16 point, p<0.05); PhD degree-holder (4.59 point, p<0.01). 6. Among general characteristics of the subjects, significant difference of working conditions was found in the following factors: gender; working areas; favored working areas; favored working positions, and education level. Majority of subjects favored working in big cities and currently work in big cities although satisfaction was comparatively low (3.75 score). 7. Future plan to work in public health center was evaluated according to occupational characteristics. Subject’s intention to work in the public healthcare center was significantly affected by opening of dental technician position, leading authority, average turnover rate, and factors affecting employment. Working in the public health care center was favored by the following subjects: Dental technicians who actively supported opening of the dental technician position (4.34 point, p<0.001); subjects who thought the Korean dental technologist association is responsible for the opening of positions in the public sector (4.26 point, p<0.001); and subjects who thought that attitude and character are important for the employment (p<0.001). 8. Concerning difference of working conditions according to the occupational characteristics, significant difference was demonstrated by factors such as a reason to choose to be a dental technician, work plan, pursuing position, responsible authority, average employment rate, and job satisfaction. High standard of working conditions was required in subjects who selected to be a dental technician for the leisure time after work (s.05 point, p<0.01), who planted to work until their marriage (4.25 point, p<0.001), and who pursuit to be a manager (3.98, p<0.05). 9. In respect to influence of general characteristics on the advancement to public health centers, the coefficient of determination (R2) was 0.068 and age affected the working condition with significant difference according to the pvalue. 10. Regarding influence of general characteristics on the advancement to public health centers, the coefficient of determination (R2) was 0.335 and work plan, opening of dental technician position in the public sector, and responsible authority had significant influence over the subject’s intention to work in the public health center according to the p-value. 11. With regard to the influence of general characteristics on the advancement to public health centers, the coefficient of determination (R2) was 0.091 and reason to choose to be a dental technician, work plan, and responsible authority significantly affected subject’s working conditions. Conclusion: Korean society is becoming a super-aged society according to several statistics. As aged population is rapidly increasing, national health insurance plans to cover denture for senior citizen over 75 years old from 2012. Therefore, dental technicians are urgently needed in the public health centers all over the nation. Many subjects in this study planed to work until their retirement and recognized dental technician’s expertise. Ministry of health and welfare and Korean dental technologist association should co-operate each other to prepare foundation and institutional devices for dental technicians to advance into the public health center. This will improve oral health of the population. This study showed urgency of medical facilities and services which meets increasing number of aged population and welfare of the population.

Many methods have been clinically applied for the occlusal contacts for diagnosis and analysis. However, none of these methods are quantitative. T-Scan system is considered as a computerized device capable to interpret occlusal contacts information quantitatively. This study describes the use of the T-Scan system to record and analyze tooth contact data by calculating strength and frequency of occlusal contacts. T-Scan recording was obtained during maximum intercuspation, edge to edge protrusion, right laterality and left laterality. At each position, the number of contact points and relative ratio of occlusal force were calculated. Because of the rapid and accurate ability of the T-Scan system to identify the distribution of the tooth contacts, it shows great promise as a clinical diagnostic screening device for occlusion.