Background: Recently, three-dimensional (3D) printing has been hailed as a disruptive technology in dentistry. Among 3D printers, a digital light processing (DLP) 3D printer has certain advantages, such as high precision and relatively low cost. Therefore, the latest trend in resin crown manufacturing is the use of DLP 3D printers. However, studies on the internal fitness of such resin crowns are insufficient. The recently introduced 3D evaluation method makes it possible to visually evaluate the error of the desired area. The purpose of this study is to evaluate the internal fitness of resin crowns fabricated a by DLP 3D printer using the 3D evaluation method. Methods: The working model was chosen as the maxillary molar implant model. A total of 20 resin crowns were manufactured by dividing these into two groups. One group was manufactured by subtractive manufacturing system (PMMA), while the other group was manufactured by additive manufacturing system, which uses a DLP 3D printer. Resin crowns data were measured using a 3D evaluation program. Internal fitness was calculated by root mean square (RMS). The RMS was calculated using the Geomagic Verify software, and the mean and standard deviation (SD) were measured. For statistical analysis, IBM SPSS Statistics for Windows ver. 22.0 (IBM Corp., USA) was used. Then, independent t-test was performed between the two groups. Results: The mean±SD of the RMS were 41.51±1.51 and 43.09±2.32 for PMMA and DLP, respectively. There was no statistically significant difference between PMMA and DLP. Conclusion: Evaluation of internal fitness of the resin crown made using a DLP 3D printer and subtractive manufacturing system showed no statistically significant differences, and clinically acceptable results were obtained.

Objectives:The purpose of the study was to investigate the effect of CAD/CAM ceramic thickness on shade. Methods: 24 disk-shaped ceramic specimens (E.Max CAD & Empress CAD, 12 mm × 12 mm) were prepared and divided into 4 groups (n=6). Ceramic specimens in 2 thicknesses (0.8 mm, 1.0 mm) were made low translucency(LT) shade A2. All specimens were measured as L*, a*, b* using spectrophotometer. The color differences(∆E values) between the specimen and a control target block (12 × 12 × 1.2 mm) were calculated. Two-way ANOVA performed between 2 groups(material and thickness). Results: As the thickness increased, the L* (for all groups) and b* value (for all groups) increased and the a* value(for LR group) decreased. The mean color differences caused by thickness was acceptible (ΔE > 2) for group LD1. But the mean color differences by thickness were not selected (ΔE < 2) for group LD2, LR1, LR2. Conclusions: The different thickness can influence the final color of CAD/CAM ceramic.

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Purpose: This study is to analyse the job seeking stress, to see the relationship Between Job Seeking Stress and career decision-making self-efficacy in students of department of dental technology.Method: For this, the students of department of dental technology in daegu and daejeon and wonkwang university selected at May 2016. A question investigation was used in a entry method of self-estimation. Furthermore a total of 151 person was used as final analysis data. Statical analysis was performed with SPSS 22.0. An analysis of frequency, two sample t-test, one-way ANOVA, Multiple regression was used.Results: Firstly, personal expenses affected beneficially statistically the Job Seeking Stress(p<.05). Secondly, sex, Score, Major satisfaction, personal expenses affected beneficially statistically the career decision-making selfefficacy(p<.05). Thirdly, University environment and academic stress in the Job Seeking Stress affected beneficially statistically the career decision-making self-efficacy(choice target). Conclusion:The study found out that there was significant effect when increased to university environment and academic stress in Job Seeking Stress, the career decision-making self-efficacy was decreased. So the study proved that when helping students facing difficulties due to the career decision-making self-efficacy, it is important to decreased their university environment and academic stress.

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