Earticle

Purpose: This study was to compare adaptations of lithium disilicate CAD/CAM crowns fabricated with different scanning systems. Methods: This study selected the mandibular right first molar as an abutment for experiments and produced 10 working models. Lithium disilicate crowns appropriate for each abutment were produced by using a CEREC CAD/CAM system. The independent t-test was then used to compare and analyze the data obtained from the two groups(a=0.05). Results: Mean(SD) adaptation were 86.93(22.82)um for the InS group, 88.42(26.77)um for the ExS group. They were no statistically significant differences between groups for adaptation(p>0.05). Conclusion: Within the limitations of this study, the results suggest that the accuracy of all investigated optical scanner were satisfactory for clinical use. Further assessment and improvement of the lithium disilicate ceramic for the fabrication of FPDs is evidently still required.

Purpose: This study is to evaluate the effect of modeling liquid on the shear-bond strength between zirconia core and veneering ceramic. Methods: Disk-shaped (diameter: 12.0㎜ ; height: 3.0㎜) zirconia were randomly divided into six groups according to the surface conditioning method and whether modeling liquid is used or not to be applied (N=60, n=10 per group): group 1 - control group with distilled water(ZD); group 2 - control group with modeling liquid(ZM); group 3 - airborne particle abrasion with 110-um Al2O3(AD)with distilled water; group 4 - airborne particle abrasion with 110- Al2O3 with modeling liquid(AM); group 5 - liner with distilled water(LD); group 6£≠liner with modeling liquid(LM). Contact angles were determined by the sessile drop method at room temperature using a contact angle measurement apparatus. The specimens were prepared using dentin veneering ceramics, veneered, 3 high and 2.8 in diameter, over the cores. The shear bond strength test was performed in a Shear bond test machine. Load was applied at a cross-head speed of 0.50㎜ /min until failure. The fractured zirconia surfaces were evaluated by using stereomicroscope ( x 30). Collected data were analyzed using SPSS(Statistical Package for Social Sciences) Win 12.0 statistics program. Results: ZD showed the highest contact angle(50.6 ± 5.4 ) and LD showed the lowest value(6.7 ± 1.3 ). Control groups and zirconia liner groups were significantly higher contact angle than liner groups(p<0.05). LD was the highest shear bond strength(43.9 ± 3.8 ) and ZD was the lowest shear bond strength(24.8 ± 4.9 ). Shear bond strengths of control groups and contact angle of liner groups were not significantly different((p>0.05). Liner groups presented adhesive failures. The others groups showed cohesive and adhesive failures. Conclusion: Modeling liquid groups showed lower contact angles and lower shear bond strength compared to those of distilled water groups.

Purpose: The purpose of this study was evaluate the validity of polyurethane model fabricated by intra oral scanning method. Methods: Ten sam cases of stone models were manufactured from master model, and polyurethane models were made with the intra oral scanning and CNC milling method. One examiner individually measured 6 distances(intercanine distance, intermolar distance, two dental arch lengths(right, left) and two diagonal of dental arch lengths(right, left) on the stone models and the polyurethane models. The Mann-Whitney U test( =0.05) were used for statistical analysis. Results: The mean difference between measurements made directly on the stone models and those made on the polyurethane models was 0.31-0.38 . No statistically differences between the two groups were founded 4 distances(p>0.05), but 2 distances were statistically significant(p<0.05). Conclusion: Stone models showed larger than polyurethane models fabricated by intra oral scanning method.

Purpose: This study was carried out in order to examine the relationship of job satisfaction and social support on the dental technicians and to analyze its influence. Methods: A self-reported questionnaire survey was carried out by having convenience sampling as 220 dental technicians who work in Seoul Metropolis, Gyeonggi-do Province, Daejeon and Chungnam Province. A research tool was used questionnaire that was proved reliability and validity. It was prepared with totally 37 questions such as 12 items for subjects’ general characteristics, 18 items for job satisfaction measurement, and 7 items for social support measurement. An analysis of the collected data was computationally processed by using SPSS Win 17.0 program. An analytical technique was made by using statistical techniques such as frequency & percentage, T-test or One-way ANOVA analysis. The following are the analytical results of the collected materials. Results: As a result of analyzing research subjects’ job satisfaction level, there was significant difference(P<0.05) in items of religion, hobby life, working environment, and rest time out of daily work. The whole mean in job satisfaction was indicated to be relatively high with 3.13. However, job satisfaction with social recognition, salary, and safety was indicated lowly. As a result of analyzing research subjects’ social support level, there was significant difference(P<0.05) in items of age, working environment, and rest time out of daily work. The whole mean in social support was indicated to be relatively high with 3.49. As a result of analyzing correlation between job satisfaction and social support, all variables were indicated to be positive correlation in high significance level, thereby having been indicated that the higher job satisfaction leads to the higher social support. Conclusion: As a result of this study, there is high correlation between social support and job satisfaction. An effort and a support are considered to be necessary for forming positive personal relations among members such as relationship with family member and with fellow employee, for improving the working conditions, and for enhancing dental technicians’ pride and social recognition in order to promote dental technician’s job satisfaction.

Purpose: Production of dental prosthesis by a dental technician causes a loud noise. Thus, we investigated stress of dental technicians due to a noise using a structured questionnaire. Methods: A survey was conducted on working dental technicians across the country from July 2013 to November 2013; among 200 sets of survey distributed, 166 were completed and returned, and excluding the 11 that deemed unsuitable, 155 sets were used for statistics. The program SPSS 19.0 was used to analyze the correlation among the collected data. Results: The stress of noise was found to be 2.83/5 points (2.93/5 for physical stress, 2.72/5 for emotional stress). Recognition of noise was found to be 2.71/5 points (3.39/5 for recognition of noise, 2.64/5 for accidents caused by noise, 2.29/5 for experiencing disability due to noise). For general items, the highest stress were shown for the following catogories: by gender, females (p=.008); by position, chief engineer (p=.033); by monthly pay, 2.51M- 3.0M KRW (p=.023); by interior comfort, ‘very unpleasant’ was the highest recognized (p=.014). For the effect of time exposed to noise, its stress (p=.000) and recognition (p=.000) rose with increase of time. Conclusion: Dental technicians performs tasks in work environments exposed to extreme noise. This research attempts to re-emphasize the necessity for improving the work environment for noise and provide measures of blocking noise and precaution.

Purpose: This study has been carried out to help to enhance the measures of interprofessional collaboration between Dental personnel and dental technicians, and between dental technicians themselves through the analysis of recognition of interprofessional collaboration between dental technicians. Methods: The subjects in this study were 130 dental technicians who were self-written questionnaire. The results were analyzed by SPSS 12.0. The collected data was analyzed by frequency and Correlation. Results: As a result of examining the correlation analysis of each question to explore the factors that affect interprofessional collaboration recognition of dental technicians, the group which received criticism from dental personnel showed negative (-) correlation in the interprofessional collaboration recognition (p <0.05). The following groups showed positive (+) correlations in the recognition of interprofessional collaboration : the group who replied that they can utilize information on the patients associated with the prosthesis production (p <0.01); the group who thinks that they are sharing common goals (P <0.01); and the group who replied that Dental personnel are familiar with patients (p <0.01). The following groups also showed higher positive (+) correlations in the recognition of interprofessional collaboration : the group who replied that they frequently discuss patient’s information with Dental personnel (p <0.01); the group who thinks they have mutual confidence in one another (p <0.01); the group who thinks that cooperation among their colleagues in dental technique laboratories are being done well (p <0.01); and the group that has high job satisfaction (p <0.01). Conclusion: Effective communication and team work between human resources for providing medical service of the facility are essential for safe and high-quality medical service to patients. Further, such elements are directly connected to efficiency of the entire team. The reliability between dental technician and Dental personnel for cooperation should not be neglected therefore continuous interests in inter-cooperative partnership is required.