• Journal of Technologic Dentistry
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• v.19 no.1
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• pp.5-12
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• 1997

To examine the difference of castability of non -precious porcelain metal according to 2 type of investing method, experiments were carried out using the method of both existing investing method and the investment with spaces to the upper & lower parts of the ring. The following conclusion were obtained from the result. 1. Seperataly using the existing investment and with spaces to the upper & lower parts of the ring, 44 samples resulted in success with the former method and 52 with the latter out of 84 samples. 2. Under the existing investing method, 44 samples out of 56 total resulted in success when the temperature of the ring was $870^{\circ}C$, and all samples failed when the temperature was $800^{\circ}C$. 3. Under the investment that gives space to the ring, when casted with the temperature of the ring fixed at $870^{\circ}C$, 40 samples out of 56 and 17 samples with the temperature fixed at $800^{\circ}C$ resulted in success. 4. Under the existing investing method with the temperaure of the ring fixed at $870^{\circ}C$ and heat soaking time given an hour, 26 out of 28 samples resulted in success and 18 resulted the same with half an hour heat soaking time. 5. Using the investment that gives space to the ring, at ring temperature $870^{\circ}C$ with heat soaking time 1 hour, all of total 28 rusulted insuccess however only 12 smaples succeeded with 30 minutes heat soaking time. 6. Under the existing investing method, samples with heat soaking time 1 hour equally given at ring temperature $870^{\circ}C$, 26 samples out of 28 succeed however at $800^{\circ}C$ all samples failed. 7. In the case of ring's upper and lower parts opened ring temperature is $870^{\circ}C$ and $800^{\circ}C$ and the heat soaking time was fixed at 1 hour, all 28 samples resulted in success and at $800^{\circ}C$ 17 succeed.

• Journal of Technologic Dentistry
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• v.42 no.3
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• pp.213-219
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• 2020

Purpose: This study aimed to identify the impact of physical surface roughing with a polishing tool onto the pre-sintering yttria-stabilized tetragonal zirconia polycrystals (TZP) core and liner treatment for chemical bonding on the bond strength of TZP core and veneering ceramic. Methods: Overall, 80 specimens were classified into two groups (non-liner, NL; and usingliner, UL ) depending on the use of liner, and these two groups were then subclassified into four groups depending on the polishing tool used. (1) Non-liner groups: NS, non-liner+stone point; NC, non-liner+carbide bur; NP, non-liner+paper cone point; NT, non-liner+silicon point. (2) Using-liner groups: US, using-liner+stone point; UC, using-liner+carbide bur; UP, usingliner+paper cone point; UT, using-liner+silicon point. The pre-sintering surface roughing values and shapes were observed, and after burning up the veneering ceramic, the shear bond strength was measured using a universal testing machine. For significance testing, a one-way analysis of variance and Tukey's multiple comparison test were conducted. An optical microscope was used to observe the fracture plane, and the following results were obtained. Results: Surface roughness NP (4.09±0.51 ㎛) represented a higher value than other groups (p<0.001). In shear bond strength, NS (35.21±1.44 MPa) of the NL group showed the highest bond strength (p<0.001). The UL group did not show a statistically significant difference between groups (p=0.612). Conclusion: Our study findings reveal that the bond strength of TZP core and veneering ceramic was improved by pre-sintering physical surface treatment than by chemical bonding with liner surface treatment.

• Journal of Technologic Dentistry
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• v.43 no.2
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• pp.62-68
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• 2021

Purpose: This study examined the correlations between the satisfaction and effectiveness of practical training and theory lectures under two conditions: face-to-face lectures and non-face-to-face online lectures. Methods: A survey of 436 public health student, whereafter SPSS 20.0 (IBM) was used on the data to conduct frequency, descriptive statistics, and exploratory factor analyses. The Cronbach's α value was estimated in a reliability analysis, and a simple regression analysis was conducted to verify the study hypothesis. Results: It was found that the students preferred pre-recorded lectures online for both practical training and theory, claiming that when compared with face-to-face lectures, these non-face-to-face lectures meant a shorter commute and the ability to repeat the content. However, it was admitted that technical issues such as facilities or access difficulties and lower concentration could be a problem. The hypothesis that course satisfaction affects lecture effectiveness was verified, with both the practical training and theory lectures found to have a statistically significant positive (+) effect. The explanatory power of student satisfaction on the effectiveness of the theory component was slightly higher than that of the practical training component, with the students having more positive perceptions on the necessity of face-to-face lectures in practical training than they did for those in theoretical instruction. Conclusion: Providing non-face-to-face online theory courses and face-to-face practical training courses could increase student satisfaction and lecture effectiveness.

• Journal of Microbiology and Biotechnology
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• v.33 no.8
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• pp.1101-1110
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• 2023

Streptococcus mutans is the primary causative agent of caries, which is one of the most common human diseases. Thus, rapid and early detection of cariogenic bacteria is critical for its prevention. This study investigated the combination of loop-mediated isothermal amplification (LAMP) and microfluid technology to quantitatively detect S. mutans. A low-cost, rapid microfluidic chip using LAMP technology was developed to amplify and detect bacteria at 2.2-2.2 × 10⁶ colony-forming units (CFU)/ml and its detection limits were compared to those of standard polymerase chain reaction. A visualization system was established to quantitatively determine the experimental results, and a functional relationship between the bacterial concentration and quantitative results was established. The detection limit of S. mutans using this microfluidic chip was 2.2 CFU/ml, which was lower than that of the standard approach. After quantification, the experimental results showed a good linear relationship with the concentration of S. mutans, thereby confirming the effectiveness and accuracy of the custom-made integrated LAMP microfluidic system for the detection of S. mutans. The microfluidic system described herein may represent a promising simple detection method for the specific and rapid testing of individuals at risk of caries.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3007-3013
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• 2014

The objectives of this study was to evaluate the validity of 3D digital models made from blue LED dental scanner. Twenty same cases of stone models and 3d digital models were manufactured for this study. Intercanine distance, intermolar distance, two dental arch lengths(right, left) and two diagonal of dental arch lengths(right, left) were measured for evaluation of validity. The nonparametric Wilcoxon rank sum test was used for statistical analysis (${\alpha}$=0.05). Although stone models showed larger than digital models in all measured distances(p<0.05), none exceeded the clinically acceptable range.

• Journal of Technologic Dentistry
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• v.35 no.2
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• pp.157-171
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• 2013

Purpose: This study aims to present a database for the development of a healthcare management program based on the survey and analysis of self reported psychosomatic symptoms among the current dental technology students. Methods: Subjects of our study are 480 dental technology major students enrolled in a third year college located Gyeonggi, Chungcheong, and Gangwon province. Using a random sampling, we conducted a self-report survey from August 30, 2011 to October 28, 2011 and 418 reports were collected as feedback and we put an analysis on them. Results: 1. The average physical self symptom was 20.49, which is higher than the average mental self symptom(18.54). Of the subcategories of psychosomatic self symptom, we observed multiple subjective symptoms as the highest one(37.77), and aggression as the lowest(13.77). 2. As to gender, both physical and mental self symptom were statistically significant with the scale score of(p<.001). The scale score of subcategories is as follows; multiple subjective symptoms(I, p<.001), eye and skin(B, p<.001), digestive(C, p<.001), impulsiveness(H, p<.001), lie scale(L, p<.001), mental instability(J, p<.001), depression(K, p<.001), aggression(F, p<.001), irregularity of life(G, p<.001), mouth and anal(D, p<.05), nervousness(E, p<.05). 3. As for obesity, statistical significance was shown with the scale scores of physical self symptom(p<.001), multiple subjective symptoms(I, p<.001), digestive(C, p<.001), aggression(F, p<.001), depression(K, p<.01), irregularity of life(G, p<.01), respiratory(A, p<.05), eye and skin(B, p<.05), impulsiveness(H, p<.05), mental instability(J, p<.05). The scale scores in the environmental quality and life satisfaction were shown as follows; depression(K, p<.001), lie scale(L, p<.01), and irregularity of life(G, p<.05). 4. We employed multiple regression analysis to take account of general factors affecting psychosomatic self symptoms, and drew that the explanatory power of the model was proved with the scales of physical self symptom(4.1%) and mental self-symptom(3.6%). Obesity was a factor that affects physical self symptom with the scale score of(p<.01), and environmental quality and life satisfaction(p<.01) and obesity(p<.05) affect mental self symptom. Conclusion: In this analysis we observed obesity of dental technology students can influence their psychosomatic self symptoms. In this sense, it would be reasonable to develop a healthcare management and education programs that help the students maintain a healthy weight and promote their health.

• Journal of Technologic Dentistry
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• v.27 no.1
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• pp.41-55
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• 2005

This study is to investigate the increasing membership rate against the previous year among the members registered as representative members and general members of the Korea Dental Technician Association from 1990 to 2004. With this study, we aim to provide more systematic data about the current status of each members in the KDTA and reconsider the needs for the practical and distinguishing management of the members. Results of the study are as follows; 1. The increasing rate from 1990 to 2004: whole members; 2.14, representative members; 2.22, general members; 2.11. Average of increasing rate against the previous year: general members; 6.10%, whole members; 5.94%, representative members; 5.91%. 2. The increasing rate in the city branch from 1990 to 2004: whole members; 2.12, representative members; 2.03, general members; 2.15. Average of increasing rate against the previous year: general members; 6.63%, whole members; 6.05%, representative members; 5.23%. 3. The increasing rate in the province branch from 1990 to 2004: whole members; 2.21, representative members; 2.74, general members; 2.01. Average of increasing rate against the previous year: representative members; 7.58%, whole members; 5.99%, whole members; 5.35%. 4. Mean ratio between representative members and general members from 1990 to 2004: 1:2.6 against the whole members, 1:2.8 in the city branch, 1:2.3 in the province branch. The ratio between representative members and general members in the year 2004: 1:3.1 in Kyoungnam province, 1:3.0 in Inchon, 1:2.9 in Kwangju that indicates a high ratio between two members and in the case of Chongbuk, the ratio between two members is rather low as shown in 1:1.1.

• Journal of Technologic Dentistry
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• v.28 no.1
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• pp.53-59
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• 2006

The movement range on the semi adjustable articulator and the movement range in an oral were measured. And then I studied to analyze the gap. I got wax records by the movement on the semi adjustable articulator, the movement in an oral. I measured the distance of the cusp tips that are close to the mesial direction and the distal direction, the buccal direction and the lingual direction then I compared gaps. As I saw results on data, I knew that the semi adjustable articulator represented the range of mandibular movement restrictively. I could find the decisive contradiction that the sliding movement finished on the semi adjustable articulator although it did not finish in an oral. When the sliding movement does not reappear exactly, it brings a fatal failure to the dental prosthesis. In addition it is impossible that the semi adjustable articulator restores the movement in an oral because the lateral condyle inclination and the horizontal condyle inclination are appeared to be straight. Therefore dental prosthesisses were made by the semi adjustable articulator, they will interfere with a mastication. I have obtained the following results; 1. The distance of sliding movement on the semi adjustable articulator showed shorter than the distance of sliding movement in oral. This means the increase of cusp inclination of the dental prosthesis that was made on the semi adjustable articulator. Therefore, when the lateral movement occurs in oral, there is a possibility to become the premature as the increase of cusp inclination. 2. The difference in the range of movement is considered as the gap that is made because the movement only can be occurred as straight in the semi adjustable articulator. 3. When the dental technician understand mandibular movement and articulator deficiencies, they can attain proficiency in use of the articulator and reduce the gap.

• Journal of Technologic Dentistry
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• v.42 no.3
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• pp.220-227
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• 2020

Purpose: This study aims to investigate the cusp variation pattern of the Korean mandibular second premolar and to determine the difference in tooth diameter and surface area using a virtual three-dimensional model. Methods: Dental casts from 69 students were scanned as a virtual dental models with a three-dimensional dental model scanner. Tooth diameter, absolute and relative individual areas, total crown area, the number of lingual cusps and central groove pattern were analyzed using RapidForm 2004. The Mann-Whitney U-test and the Kruskal-Wallis test were performed to verify sexual dimorphism, the difference in tooth diameter and surface according to the cusp variation pattern (α=0.05). Results: There was no significant difference except in buccolingual diameter (p<0.05) and buccolingual diameter at the cervix (p<0.05). The relative surface area of the total clinical crown was 65.76% for the buccal half and 34.24% for the lingual half, with a ratio of 2:1. In the case of the presence of two lingual cusps, the ratio was 21.47% for the mesiolingual half and 14.12% for the distaolingual half, with a ratio of 3:2. The dominant central groove patterns of the second premolar were the H-pattern (42.0%), followed by the Y-pattern (37.7%), then the U-pattern (20.3%). The relative buccal half was largest in the U-pattern central groove and the relative lingual half was largest in the Y-pattern central groove (p<0.05). Conclusion: This study is significant in that it measured quantitative surface areas and the findings could be a meaningful reference to comprehend dental anatomy in Koreans.

• Journal of Technologic Dentistry
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• v.35 no.3
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• pp.243-257
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• 2013

Purpose: This study aims to analyze the factors affecting the dropout intentions of the dental technology students of a college. Methods: The subject of this study was 76 freshmen and 74 sophomores of dental technician major in an anonymous college. Results from the questionnaire called K-vision diagnosis program were computed by means of t-test, One-Way ANOVA, and correlation analysis. Results: 1. Total points of the drop out intention came to 782.14 points. Of the five categories concerned with the drop out intention, complain in college satisfaction(50.12points) was the highest and department satisfaction(47.51points) was the lowest. Of 16 subcategories, complaining in administrative supporting system proved the highest as 50.80 points and Inquiry to Professor the lowest(45.56 points). 2. Among the general characteristic gender (p<. 01), student group (p<.01), and credit (p<.05) made a meaningful statistical difference; no statistical significance was found in grade, admission, and dwellings. 3. Of the five categories, statistical significance was shown as follows; Department satisfaction (p<.01), College satisfaction (p<.05) under gender, Department satisfaction (p<.05) in grade, Academic integration (p<.01), Department satisfaction (p<.01) in credit. No statistical meaning was found in admission and dwellings. 4. Statistical significance was found under 16 subcategories as follows: Career identification(p<.01), Academic support system(p<.01), Social activity II(p<.05) in gender area, Inquiry to professor(p<.01), Learning(p<.05), Understanding learning I(p<.05) in grade area, Learning(p<.001), Career identification(p<.001), Understanding learning I(p<.01), Understanding learning II(p<.01), Inquiry to professor (p<.01), Learning ability (p<.05), Occupation (p<.05), Social Activity II(p<.05), Administrative support system (p<.05) in student group area, Credit (p<.001), Career identification (p<.01), Understanding learning I(p<.05) in credit area; admission and dwellings was statistically meaningless. 5. Of the 5 categories academic integration (r=.766) was most relevant to the dropout intention of the subjects and followed by department satisfaction (r=.735), college satisfaction (r=.554), service acceptability (r=.373), and statistical significance was shown as p<.01. Conclusion: Considering the results of this study, we are in a pressing need for the introduction of policies and programmes aiming at preventing the dropout rates of the dental technician majors at college. In tandem with this, qualitative and viable human resource management of the dental technicians should be implemented.