Earticle

Purpose: This study provided the basic data for selection the zirconia block and CAM by means of marginal fitness observations, flexural strength test and hardness test. Methods: Three dental zirconia blocks(ABCera, NaturaZ, ST98) and two dental milling machines(CAD/CAM MS, DWX-50) were used in this study. Metal abutment(diameter 10 mm, height 5 mm, inclined angle 3° taper, 1 mm chamfer margin) was fabricated by Ti customized abutment, and then zirconia copings were fabricated for each ten specimens. Silicone replica technique was used to observe the marginal fitness of cross-sections with a stereomicroscope at ×50 magnification. The dental zirconia blocks was cut into 10 pieces each having a size of 25 mm × 5 mm × 1 mm, and fabricated according to the manufacturer's instructions, and flexural strength was measured using a universal testing machine. For hardness test, a micro Vickers hardness tester was used as it was in the flexural strength test. Statistical analysis was performed by one way ANOVA and post-test was performed by Scheffe test. Results: For marginal fitness of bucco-lingual axial, ZU group(59.7±10.3 ㎛) was the lowest, followed by RA, ZA, ZD, RD, RU. For marginal fitness of mesio-distal axial, ZU group(59.3±10.2 ㎛) was the lowest, followed by RA, ZA, RD, ZD, RU. One-way ANOVA showed statistically significant difference between groups(p<0.05). For flexural strength, ABCera block(718.0±57.2 MPa) was the highest, followed by NaturaZ, ST98. For hardness, ABCera block(1550.3±19.8 Hv) was the highest, followed by ST98, NaturaZ. There was no significant difference in flexural strength and hardness between blocks(p>0.05). Conclusion: Based on the results of this study, the type of dental zirconia block did influence the marginal fitness, and all dental zirconia blocks are expected to be suitable for clinical application. The highest flexural strength and hardness were ABCera block, and no statistically significant difference was observed.

Purpose: The objective of this study was to evaluate influence of mechanical properties of gingival shade composite resins(GSCRs) according to thermocycling treatment. Methods: The material utilized in this study was Crea.lign(CGR), Twiny flow(TGF) and Twiny(TGP). Total sixty specimens were fabricated with a dimension of 25×2×2mm according to the ISO 4049. After fabrications, specimens of before and after thermocycling(to 55℃ from 5℃) were stored in the distilled water for 24 hours at the 37℃. Three-point flexural test was performed in universal testing machine(Instron 5966, USA) at a crosshead speed of 1 mm/min. Flexural strength, flexural modulus and work of fracture according to the thermocycling were analyzed using a one-way ANOVA analysis. Surface analysis of GSCRs after thermocycling evaluated using the scanning electron microscope. Results: : The highest FS was measured in TGP group of NTC group and lowest in CGR group after TC. After TC, FS and FM decreased in CGR and TGP groups, but TGF increased. There was a statistically significant difference between FS and WOF in GSCRs(p <0.05). But FM did not show any significant difference after TC (p> 0.05).The strength of the characteristic exceeded the flexural strength required by ISO 4049(> 80 MPa). Weibull modulus(m) showed the highest reliability in the TGP group (m = 14.22), and the reliability of the TGF and TGP groups after TC decreased. Conclusion: Thermocycling treatment is important factor influence of mechanical properties with gingival shade composite resins. Therefore, we recommended that mechanical properties need to get useful information and accuracy for life-span expectancy according to the thermocycling treatment.

Purpose: With the development of digital dental technology, we are manufacturing prosthetic crown in various ways. However, the wax-up method that makes existing prosthetic crown is also used steadily. Thus, we will compare the shape of the crown designed with wax-up and the crown designed with CAD. Methods: Sculpt the crown with wax-up on the model to 10 dental technicians. The same model was used to design the crown CAD. Measure the size of the sculpted crown. The shapes were compared in three dimensions. Results: As a result, we could observe a difference in size and shape in crown designed with wax - up crown and crown. Conclusion: These results suggest that there are differences according to the method of carving crown and the method of processing.

Purpose: The purpose of this study was to compare the shear bond strength of the metal-heat pressed glass ceramic bilayer structure. Methods: Metal framework specimens were prepared and surface is spreaded opaque(IPS InLine system opaque, IvoclarVivadent, Liechtenstein). There were 10 specimens for each bilayer dental ceramic group. The first group was porcelain fused metal, Press on metal IPS Inline press group, and press on metal HASS prototype group. Specimens measured for the shear bond strength on Schwickerath test by Instron universal testing machine(Instron3345, Instron Corp., USA). Mean average bond strength values of each specimen group were analyzed using a one-way ANOVA analysis of variance Saphiro-wilk’s test. Statistical analysis were performed using IBM SPSS 23.0(IBM Co., Armonk, USA) Results: RMS±SD The highest mean average HASS POM showed a bond strength value (47.55± 12.80 Mpa). The lowest mean average values Porcelain fused metal (33.30 ± 2.00 Mpa). Independent t-test was conduct to analysis the significant difference (p<0.05) (Table 3). Conclusion: Three kinds of Metal/ glass bilayer dental ceramics bond strength were clinical acceptability. Especially, as lithium disilicate containing represents higher bond strength.

Purpose: The study aims to evaluate satisfaction of toothpaste adding natural materials extracted from Zanthoxylum schinifolium and various herbs (Pine, Lemongrass, Spearmint). Methods: We performed the first survey to collect basic data for the development of natural herbal toothpaste. Participants were the general public in Jeonju and Iksan of Jeollabuk-do, and a total of 273 questionnaires were analyzed for the study. By adding anthoxylum schinifolium and herbal extracts (Pine, Lemongrass, Spearmint) to the toothpaste, four kinds of natural herbal toothpaste prototypes were manufactured. The second survey was conducted to assess the satisfaction one week after using the natural herbal toothpaste prototypes. Results: Satisfaction with current toothpaste was 3.52. The most important criterion of toothpaste was the prevention of tooth caries. 55.3% participants obtained toothpaste information through advertising. The survey indicated the most worrisome ingredient of toothpaste was surfactant, showing 55.3%. The overall satisfaction of natural herbal toothpaste was 3.99; among the four natural herbal toothpaste, toothpaste 2 (Zanthoxylum schinifolium, Lemongrass) showed the highest satisfaction as 3.99; and toothpaste 3 (Zanthoxylum schinifolium, Spearmint) showed the lowest satisfaction as 3.56. Conclusion: Four kinds of natural herbal toothpaste showed higher satisfaction as 3.99. In particular, the toothpaste adding Zanthoxylum schinifolium and Lemongrass extracts

Purpose: In order to increase competitiveness for the growth and development of the dental laboratory industry, we plan to develop the dental laboratory industry. Methods: A total of 547 questionnaires were used as the final analysis data for the dental technicians from all over country participated in the 51st Korea Dental Technology Expo & Scientific Conference of the Korean Dental Technologist Association held in KINTEX from July 18 to 19, 2015. The questionnaire items consisted of 28 items in terms of general characteristics, questions about the methods to be pursued for the development of the dental laboratory industry, and recognition about the methods to be pursued to develop the dental laboratory industry. The collected data were analyzed by SPSS Ver. 21.0 for windows. Results: To improve the dental laboratory industry, actualization of dental laboratory products fee(41.2%) had the highest, followed by improving treatment of dental technician, standardization of dental laboratory products, direct bill of medical insurance, regulation of contract management on huge capital, and etc. The recognition of the measures to be pursued for the development of the dental laboratory industry was that dental laboratory products fee required to receive more than 20% of the dental prosthesis fee highest(4.62±0.76). And to enlarge dental laboratories through M&A between dental laboratories is the lowest(3.39±1.26). Conclusion: As a means to pursue the development of the dental laboratory industry, the actualization of dental laboratory products fee was proposed. Recognition also showed that dental laboratory products fee required to receive more than 20% of dental prosthesis fee was the highest. It is important to propose a reasonable dental laboratory products fee because it recognizes that it is necessary to promote economic growth in both development plan and awareness.