Earticle

Purpose: The purpose of this study is to analyze the fitness of heat - pressed ceramic laminate veneers fabricated using the additive manufacturing. Methods: Impression was replicated by using light body silicone and heavy body silicone on the custom tray, and it was fabricated using Type Ⅳ Stone. The test specimens were prepared by using a dental scanner, a laminating veneer using a dental design program, and a specimen with a 3D printer . The control specimens were prepared by the lost wax technique and heat - pressed to fabricate the specimens. The data of the specimens were measured by the RMS value of the internal fitness a using a 3-dimensional measurement program. Results: The Stereolithography laminate veneer group was measured at 78.10(4.09) μm and the LWV group was measured at 31.50(5.10) μm. There is a significant difference between the two groups (p<0.001) Conclusion : Evaluation of fitness laminate veneers was fabricated by additive manufacturing showed the difference statistically significantly and clinically acceptable result.

Purpose: This study sought to identify changes in the mechanical characteristics and color of zirconia according to different sintering temperatures of the substance. Methods: This study processed some specimens of zirconia into those of 8 ㎜(H)×10 ㎜(W)×50 ㎜(L)±0.1 each, and sintered them at 1450~1600℃ on a 50℃-interval basis in order to examine how their mechanical characteristics and color are changed. Each specimen sintered using the spectral colorimetric apparatus (Easyshade, VITA, Germany) was observed for each of the color change by sintering temperature. Results: When those specimens were sintered at 1450~1600℃, they were 0% in absorption ratio and porosity, 20% in shrinkage ratio and 6.10g/㎤ in specific gravity. Absorption ration, porosity, shrinkage ratio and specific gravity all didn’t vary depending on the sintering temperature. The fracture strength of the specimens was highest or 1037㎫ at the sintering temperature of 1550℃ and a little lower or 989㎫ at that of 1600℃. No variation in L* value was found depending on the sintering temperature of the specimens, while c* value was highest at that of 1450℃. In addition, h* value was highest when the specimens was sintered at 1550℃. Conclusion: This study could determine how zirconia shows changes in mechanical characteristics and color in accordance with different temperatures of its sintering. It is necessary to supplement the physical data of colored transparent zirconia block which is expected to be widely used in clinical practice.

Purpose: In this study, a corresponding porcelain coating material was applied to dental Co-Cr metal among PFM. Methods: The bonding strength of the fired specimens was measured by a three-point flexural rigidity test. SEM/EDS was used to observe the surface component of specimens. Results: First, All groups were higher than the minimum bonding strength of 25 MPa specified in ISO 9693 for dental metal-ceramics specimens. Second, The bonding strength of control group(WO) is 44.64 MPa. Experimental group DM was 35.45 MPa and DP was 31.82 MPa(P<0.05). Tukey's HSD tests results have shown that the bonding strength in control group(WO) is higher than that of experimental group(DM, DP). Third, In the case of metal - porcelain bonding strength, the application of opaque porcelain and firing were higher than those of the group treated with degassing process. Conclusion: The bonding strength was higher when the powder opaque porcelain was applied than the paste opaque porcelain.

Purpose: We compare the bond strength of heat-cured PMMA of Lucitone 199 and QC-20 and Tokuyama Rebase Resin of self-cured resin, which are widely used and well accepted in clinical practice. In order to test the mechanical bonding and chemical bonding, we will compare the bond strength between EstheShot Bright, Smiletone, Repair and Rebase resins. Methods: The denture base resin used in this study was PMMA heat-cured QC-20 and Lucitone 199, polyamide resin EstheShot Bright, Smiletone. And Two types of self-curing Rapid Repair and Tokuyama Rebase were used as resection resins. To measure the bond strength, the denture specimens were fabricated in the size of 10×64×3.5 mm as instructed by the manufacturer. A surface treatment agent was applied to the cut surfaces of each denture specimen, and the specimens were placed in a preformed silicone mold, and autoclaved excimer resins were prepared. The bending strength of the fabricated specimens was measured using a universal testing machine (STM-5, United Calibration Co., U.S.A.) to measure the three-point bending strength. Results: In both polycarbonate and polyacetal resin, a special resin surface treatment agent showed higher bonding strength than the resin surface treatment agent(p<0.05). Regardless of the type of surface treatment, polycarbonate showed higher bond strength than polyacetal resin(p<0.05). Conclusion: It is considered desirable to use a special surface treating agent for the thermoplastic denture base resin such as polycarbonate and polyacetal resin.

Purpose: The purpose of the study is to analyze the effects that Flipped Learning Method has on a college student’s self directed learning ability, critical thinking disposition, learning motivation, and learning satisfaction, and determine its effectiveness as a new pedagogical approach. Methods: The survey was conducted on dental technology students. The collected data was analyzed by the statistical program SPSS 21.0. The results were analyzed by reliability, frequency, t-test. To test for significance on each item, p<0.05 has been decided as a standard. Results: According to the analysis, the student who attended a class that utilized Flipped Learning Method was found to have higher levels of self directed learning ability, critical thinking disposition, learning motivation, and learning satisfaction than a student who attended a class that did not utilize such a method. Conclusion: The study results show that, in order to enhance students’ self directed learning ability, critical thinking disposition, learning motivation, and learning satisfaction and to improve the quality of class instruction, it may be necessary that Flipped Learning Method be adopted more widely and recommended more strongly. Such changes will promote a long term improvement in educational environments and play a major role in strengthening students’ abilities.

Purpose: It is intended to raise awareness of importance of protective equipment and necessity of safety education by examining the actual condition of measures to deal with accident, occurrence of injury, whether safety education is received or not, the actual condition of wearing protective equipment, and working environment of dental lab and dental technician. Methods: A self-administered survey was conducted for a total of 150 dental technologists. A chi-squared test and independent-samples t-test was carried out by using SPSS WIN Program (version 12.0) in order to analyze the actual condition of safety education according to work experience and position and whether injury occurred according to whether to wear protective equipment. Significance level was 0.05. Results: With regard to whether injury occurred according to whether safety education was received, there was ‘receiving the safety education-injured (71.8%)’, ‘not receiving the safety education-injured (79.7%)’, ‘receiving the safety education-not injured (28.2%)’, and ‘not receiving the safety education-not injured (20.3%)’. The statistical results of injury occurrence according to safety education were not significant. With regard to whether to be injured according work experience, there was ‘less than 10 years-injured (68.4%)’, ‘less than 10 years- not injured (31.6%)’, ‘10 years or above-injured (89.1%)’, and ’10 years or above-not injured (10.9%)’. The statistical results of injury occurrence according to work experience were significant (p<0.001). Conclusion: Dental lab and specialized agencies should continue to be interested in periodic safety training, recommending wearing protective equipment and personal protective equipment support and so on.

Purpose: The purpose of this study was to investigate the factors contributing to temporomandibular joint disorder symptoms. Methods: The survey was conducted from May 1 to June 10 2017 against college students(120 males and 123 females) in Daejeon and Gangwon who understood the purpose of this study and agreed to participate. Results: First, The most frequent symptom of temporomandibular joint disorders is noises from the joint (male 45%, female 61.8%), followed by headache or neck pain (male 25.8%, female 52.8%). There was shown a significant difference by gender in all items except for jaw dropping, poor alignment of teeth and trauma(p<0.05). Second, Looking into the correlation between stress and subjective symptoms of Temporomandibular joint disorders, The stress of Temporomandibular joint disorders showed more significant relation with realistic issues such as academic task, economic burden (e.g., treatment cost), future career, and life values rather than aspect of social relationship(p<0.01). Conclusion: As a result of analyzing variables to understand the influence of stress on temporomandibular joint disorders, the accumulated number of bad habits, stress and temporomandibular joint disorders showed a significantly positive correlation with one another (p<0.05). In other words, the higher the stress level the severe the temporomandibular joint disorders; the more the bad habits the severe the temporomandibular joint disorders;

Purpose: This study aims to discover the degree of department of dental technology students' oral health recognition and to find out the differences of oral health beliefs depending on oral health behaviors. Method: The subjects in this study were the students who attended department of dental technology in Daejon, Daegu, Iksan. After a survey was conducted, the collected data were analyzed with SPSS 23.0. An analysis of frequency, independent t-test, one-way ANOVA, correlation was used. Result: Among the general things related to oral health behaviors was the statistical significant differences(p<0.05) in the area of oral health belief depending on the opportunity of oral health education, attendance of oral health course, self-aware of oral health, the number of times of teeth brushing, teeth brushing status, experience and the degree of smoking. There was a positive correlation between the degree of susceptibility and that of response to severity, barrier, salience and benefit. Severity also showed the positive correlation with barrier. Higher barrier susceptibility meant higher salience and higher benefit. So was the correlation between benefit and salience. Conclusion: This study showed that college education should focus on the students' possible behaviors in order to convey the effective oral health knowledge.

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.