• The Journal of Advanced Prosthodontics
• /
• v.12 no.2
• /
• pp.67-74
• /
• 2020

PURPOSE. This study evaluated the influence of prosthesis weight and number of implants on the bone tissue microstrain. MATERIALS AND METHODS. Fifteen (15) fixed full-arch implant-supported prosthesis designs were created using a modeling software with different numbers of implants (4, 6, or 8) and prosthesis weights (10, 15, 20, 40, or 60 g). Each solid was imported to the computer aided engineering software and tetrahedral elements formed the mesh. The material properties were assigned to each solid with isotropic and homogeneous behavior. The friction coefficient was set as 0.3 between all the metallic interfaces, 0.65 for the cortical bone-implant interface, and 0.77 for the cancellous bone-implant interface. The standard earth gravity was defined along the Z-axis and the bone was fixed. The resulting equivalent strain was assumed as failure criteria. RESULTS. The prosthesis weight was related to the bone strain. The more implants installed, the less the amount of strain generated in the bone. The most critical situation was the use of a 60 g prosthesis supported by 4 implants with the largest calculated magnitude of 39.9 mm/mm, thereby suggesting that there was no group able to induce bone remodeling simply due to the prosthesis weight. CONCLUSION. Heavier prostheses under the effect of gravity force are related to more strain being generated around the implants. Installing more implants to support the prosthesis enables attenuating the effects observed in the bone. The simulated prostheses were not able to generate harmful values of peri-implant bone strain.

• Journal of Technologic Dentistry
• /
• v.39 no.3
• /
• pp.205-218
• /
• 2017

Purpose: The current education curriculum centering on the national examination can not train the human resources needed for the clinic. Therefore, we would like to develop a curriculum for practical education and cultivate talented people capable of working in clinical practice at the same time. Methods: This study investigates the importance and utilization of the subjects by using qualitative and quantitative mixed research methods through interviews with FGI and structured questionnaires for grades 2,3,4. Results: In order to carry out the related work, all the subjects need more practical training, and the curriculum that can learn the latest prostheses such as CAD / CAM, implant, 3D printer, Conclusion: In order to carry out the related tasks immediately after graduation, practical education through improvement of curriculum is needed.

• Journal of Technologic Dentistry
• /
• v.34 no.4
• /
• pp.381-390
• /
• 2012

Purpose: The goal of this study is to investigate the correlation of orthodontic treatment with self-esteem and how orthodontic treatment has an effect on university student's self-esteems by investigating and analyzing the difference in self-esteem of each general characteristic and the difference in self-esteem according to the existence or nonexistence of malocclusion and orthodontic treatment for adult university students. Methods: This study conduced a survey for 420 university students including dental related department, department of health and department of non-dental health in two universities located in Taegu, Gyeongbuk-do province from May 15, 2012 to May 30, 2012, and in 420 questionnaires of the investigated 420 target students, total 400(95.2%) questionnaires except for the questionnaires with falsely or erroneous responses were used for study analysis. Results: In the relations of general characteristic with self-esteem, for self-esteem by each gender, male student showed higher, for self-esteem by residential area, the university student residing at metropolitan area showed higher, for self-esteem by financial status, high class and middle class students in home financial status showed higher, for self-esteem by face shape, the student with triangular face shape showed higher, and in the relation of self-esteem with orthodontic treatment, the university student who is getting orthodontic treatment showed higher self-esteem statistically significantly. Conclusion: For gender, male university student, for residential area, the university student residing at metropolitan area, the high class university student in financial status, the university student with triangular face shape, and the university student who is getting orthodontic treatment showed statistically significantly higher self-esteem.

• Journal of Technologic Dentistry
• /
• v.41 no.4
• /
• pp.279-285
• /
• 2019

Purpose: The dental CAD / CAM system has been popular with the development of the digital dental industry. Zirconia is a typical material in dental CAD / CAM systems. Zirconia crowns are classified into single layer and double layer. This study is about the double layer crown of zirconia. The surface roughness, bond strength and fracture patterns of the zirconia surface were observed. Methods: Zirconia blocks were cut using a low speed cutter. Sintered to form a plate shape (6mm × 6mm × 3mm). The prepared specimens were surface treated in four ways. Surface roughness and bond strength were measured. And the fracture pattern was observed. Results: Result of surface treatment of zirconia. The surface roughness test results were as ET 2.87 ㎛, ST 2.67 ㎛, LT 2.44 ㎛, AT 2.41 ㎛, CN 2.08 ㎛ order. Bond Strength results were as LT 25.09 MPa, AT 23.27 MPa, ST 21.27 MPa, ET 21.09 MPa, CN 16.12 MPa order. Fracture patterns showed cohesive failure of 25-50% of the bond area. Conclusion: Surface roughness, bond strength and fracture pattern of the zirconia surface were observed. Etching the surface treatment of zirconia materials has been shown to affect the surface roughness. Zirconia special binder treatment has been shown to affect the bond strength improvement.

• Journal of Technologic Dentistry
• /
• v.42 no.3
• /
• pp.262-271
• /
• 2020

Purpose: This study aimed to provide the basic data for improving patient satisfaction and dental services by examining the satisfaction of implant patients who have become important customers of dental treatment due to the increased demand for implants and identifying the factors affecting satisfaction. Methods: Out of 145 questionnaires, excluding 15 questionnaires that were unfaithfully responded to or difficult to analyze, 130 questionnaires were used for the analysis of the satisfaction of the dental patients with implant treatment in 19 dental hospitals and clinics in Gyeonggi-do, South Korea. Results: Implant satisfaction was as high as 3.20 (±0.56) for masticatory function satisfaction, 3.19 for psychological function satisfaction (±0.59), and 3.01 (±0.58) for social function satisfaction. Conclusion: Consistent patient care is important because an implant is not a one-shot cure but ends over a period of several months to several years. It is meaningful in that this study measured the satisfaction of implant prostheses evaluated from a patient's point of view and examined various factors and needs affecting patient satisfaction to provide the basic data for research that can contribute to improving the satisfaction of implant patients.

• Journal of Technologic Dentistry
• /
• v.39 no.1
• /
• pp.1-7
• /
• 2017

Purpose: The purpose of this in vitro study compared to evaluation of repeatability of scanning abutment tooth stone model and impression applied CAD/CAM ISO standard in dentistry. Methods: To evaluate repeatability of scanning abutment tooth stone model, were repeatedly scanned to obtain 11 data via 3D stereolithography (STL) files. 10 data (STL files) were compared with the first 3D data (STL file), and the error sizes were measured by using 3D superimposing software(n=10). Also, the repeatability of scanning abutment tooth impression was evaluated with the same procedure. Independent t test was performed to evaluate the repeatability of scanning abutment tooth stone model versus impression through root mean square(RMS) and standard deviation(SD)(${\alpha}=0.05$). Results: $RMS{\pm}SD$ with regard to repeatability were $14.7{\pm}2.5{\mu}m$, $17.1{\pm}4.0{\mu}m$, respectively, with scanning abutment tooth stone model and impression(p=0.129). Conclusion: This study results showed a little different repeatability of scanning abutment tooth stone model and impression applied CAD/CAM ISO standard in dentistry, will suggest futures good studies and clinical advantages.

• Biomedical Science Letters
• /
• v.13 no.4
• /
• pp.341-347
• /
• 2007

Streptococcus mutans, one of a major causal agents of dental caries, is component of the dental plaque and produces various organic acids such as lactic acid as the end-product of glycolysis. In this study, we isolated S. mutans from Korean children with caries and also investigated the expression of protein under acid stress. S. mutans was identified at the species level using a 16S ribosomal DNA sequencing comparison method. The primer specificity was tested on eleven S. mutans strains isolated from Korean children with caries. The data showed that eleven strains are S. mutans. At treatment of concentration of 20 mM lactic acid in the mid-log phage, K-7 exhibited the highest maximum culture OD compared with those of other groups. As a consequence, we examined the expression of protein under 20 mM lactic acid stress using S. mutans K-7. The results of 2D gel electrophoresis by image analysis showed that thirteen proteins are up-regulated under the stress. Further study is being focused on amino acid analysis by mass spectrometry in order to analyze those spots.

• Journal of Technologic Dentistry
• /
• v.37 no.4
• /
• pp.199-203
• /
• 2015

Purpose: The purpose of this in vitro study was to evaluation the effect of shade on all ceramic restoration based zirconia according to cooling rate on Firing. Methods: 10 specimens applied to the dentin porcelain were made on the zirconia. After 5 specimens of the first group were burned in the furnace, these were put out rapidly. And after 5 specimens of the second group were burned in the furnace, these were put out slowly later 15 min. All specimens were measured $L^*$, $a^*$, $b^*$ using spectrophotometer, there were calculated 10 mean(SD) of descriptive statistics with SPSS program. These data were used for ${\Delta}E^*$ with color difference equation. Independent t tests were performed between 2 groups. Results: $L^*$, $a^*$, $b^*$ of 2 groups was statistically significant respectively (p<0.001), ${\Delta}E^*$ was 4.55 value. Conclusion: This study showed effect of shade on all ceramic restoration based zirconia according to cooling rate on Firing.

• Journal of Technologic Dentistry
• /
• v.34 no.4
• /
• pp.337-344
• /
• 2012

Purpose: This study examined the corrosion level by alloy type and pH, and used the corrosion levels as the dental health data. The study utilized one Ni-Cr alloy for the full and removable partial denture metal frameworks and two Ni-Cr alloys for porcelain-fused-to-metal crown, among the non-beryllium dental casting non-precious Ni-Cr alloys. Methods: The alloy specimens were manufactured in $10cm^2$ and stored in the corrosive solution(pH 2.2-4.4) in the electrical water bath($37^{\circ}C$) for seven days. Afterwards, the metal ions were quantitatively analyzed using the ICP. Results: Of the three metal alloys, Bellabond-Plus$^{(R)}$alloy and SOLIBOND N$^{(R)}$alloy, with 22% or higher chrome chemical contents, had higher corrosion resistance than Jdium-100$^{(R)}$alloy with 20% chrome chemical content. In all three alloys, the corrosion of Ni was highest, and metal ion corrosion was higher in the pH 2.2 corrosive solution. Conclusion: Although Ni-Cr alloy was not very corrosive, a Ni-allergic patient should not have Ni-Cr alloy prosthesis. The Ni-Cr alloy for porcelain-fused-to-metal crown should be designed for the dental porcelain to cover the whole crown.

• Journal of Technologic Dentistry
• /
• v.12 no.1
• /
• pp.67-72
• /
• 1990

The purpose of this study was to find job maturity of dental technology students in Taegu area. In order to accomplish the objectives stated above, the following research methods were utilized : 1. The related literatures including previous studies and journal were reviewed to develop the questionnaire for this purpose. 2. Field survey and questionnaire survey were conducted to collect data from 360 students sampled and analyzed by frequency percentage $X^2$-score. In consquence of analysis of the responses, the finding were as follows : 1. The job maturity of students was shown high. The grade point of 98.6 percent students as a whole was above three point. 2. As compared by academic year of sophomore students was higher than that of freshmen's, and male students were shown greater score than female students.