No abstract available.
Glass*

For the purpose of quality assurance (QA) of the blood irradiator, QA programs for daily, monthly, and yearly were developed. For daily tests, simple items for basically operating the machine are recommended. For monthly and yearly tests, the measurement of dose to assure the dose delivery system are performed by a dosimetry devices (Glass dosimeter jig) developed in this study. The QA program is practical for clinical environment.
Glass

No abstract available.
Glass*

The purpose of study is to investigate whether glass rod detector (GRD) would be suitable for dosimeter of radiotherapy units. A GRD is used for the measurement of the output factors and x-axis beam profiles from Gamma Knife. The output factors measured with GRD from the 14, 8 and 4 mm collimators relative to the 18 mm collimator are 0.980+/-0.013, 0.949+/-0.013 and 0.872+/-0.012, respectively. The output factors obtained with a GRD are within 1.0% in good agreement with the values recommended by the manufacture. The full width at half maximum (FWHM) of x-axis beam profiles measured with GRD are 5.9 mm at a 4 mm collimator.
Glass* ; Radiotherapy

No abstract available.
Crowns* ; Glass*

OBJECTIVES: This study aimed to evaluate the color stability of bulk-fill and nanohybrid resin-based composites polished with 3 different, multistep, aluminum-oxide impregnated finishing and polishing disks. MATERIALS AND METHODS: Disk-shaped specimens (8 mm in diameter and 4 mm in thickness) were light-cured between two glass slabs using one nanohybid bulk-fill (Tetric EvoCeram, Ivoclar Vivadent), one micro-hybrid bulk-fill (Quixfil, Dentsply), and two nanohybrid incremental-fill (Filtek Ultimate, 3M ESPE; Herculite XRV Ultra, Kerr) resin-based composites, and aged by thermocycling (between 5 - 55℃, 3,000 cycles). Then, they were divided into subgroups according to the polishing procedure as SwissFlex (Coltène/Whaledent), Optidisc (Kerr), and Praxis TDV (TDV Dental) (n = 12 per subgroup). One surface of each specimen was left unpolished. All specimens were immersed in coffee solution at 37℃. The color differences (ΔE) were measured after 1 and 7 days of storage using a colorimeter based on CIE Lab system. The data were analyzed by univariate ANOVA, Mann-Whitney U test, and Friedmann tests (α = 0.05). RESULTS: Univariate ANOVA detected significant interactions between polishing procedure and composite resin and polishing procedure and storage time (p < 0.05). Significant color changes were detected after 1 day storage in coffee solution (p < 0.05), except Quixfil/Optidisc which was color-stable after 7 days (p > 0.05). Polishing reduced the discoloration resistance of Tetric EvoCeram/SwissFlex, Tetric EvoCeram/Praxis TDV, Quixfil-SwissFlex, and all Herculite XRV Ultra groups after 7 days storage (p < 0.05). CONCLUSIONS: Discoloration resistance of bulk-fill resin-based composites can be significantly affected by the polishing procedures.
Coffee ; Glass

No abstract available.
Contrast Media* ; Glass* ; Syringes*

STATEMENT OF PROBLEM: Fracture of composite resin core will be occurred by progress of crack. Bonding interface of different materials has large possibility of starting point of crack line. Therefore, the bond strength of glass fiber post to composite resin core is important for prevention of fracture. Purpose: This in vitrostudy tried to find out how to get the higher strength of glass fiber post to composite resin core through surveying the maximum load that fractures the post and core complex. MATERIALS AND METHODS: 40 specimens made with glass fiber Posts(Style post(R), Metalor, Swiss) and composite resin core(Z-100(R), 3M, USA) were prepared and loaded to failure with push-out type shear-bond strength test in a universal test machine. The maximum fracture load and fracture mode were investigated in the specimens that were restored with four different surface treatments. With the data, ANOVA test was used to validate the significance between the test groups, and Bonferroni method was used to check if there is any significant statistical difference between each test group. Every analysis was approved with 95% reliance. RESULTS: On measuring the maximum fracture load of specimens, both the treatments of sandblasted and acid-etched one statistically showed the strength increase rather than the control group(p<0.005). The scanning electric microscope revealed that sand blasting made more micro-retention form not only on the resin matrix but on the glass fiber, and acid-etching contributed to increase in surface retention form, eliminated the inorganic particles in resin matrix. Specimen fracture modes investigation represented that sand blasted groups showed lower bonding failure than no-sand blasted groups. CONCLUSION: Referring to the values of maximum fracture load of specimens, the bonding strength was increased by sand blasting and acid-etching.
Glass* ; Silicon Dioxide

PURPOSE: The purpose of this study was to evaluate and compare the translucency of shaded zirconia all-ceramic systems. MATERIALS AND METHODS: Translucency of 3 different zirconia all-ceramic systems colored by different techniques was compared with a lithium disilicate glass-ceramic (IPS e.max Press). Square-shaped specimens with 0.5 mm thickness were fabricated from In-Ceram YZ, ICE Zirkon and Katana systems in A1, A2 and A3.5 shades according to Vitapan Classical shade tab (n=11). Specimens were then veneered and glazed with corresponding veneer ceramic recommended by each zirconia system manufacturer and the total thickness was set to 1.5 mm. Translucency measurements were performed with VITA Easyshade Compact spectrophotometer after each stage and translucency parameter was calculated. Data were statistically analyzed with repeated measures ANOVA and Tukey multiple comparison test. RESULTS: The control group was significantly more translucent than the zirconia systems (P<.05). ICE Zirkon cores showed the least translucency; neither In-Ceram YZ nor Katana systems were superior to each other in terms of translucency. Translucency of all specimens was decreased after veneering, and the translucency rankings were changed. CONCLUSION: Coloring technique did not have a significant effect on translucency of zirconia cores. Although zirconia systems were less translucent than lithium disilicate glass ceramic, they had partial translucency and there were translucency differences among the zirconia systems. Chroma affected the translucency of precolored zirconia cores.
Ceramics ; Glass ; Ice ; Lithium

This study was designed to compare the effect of polishing on surface roughness of composite resin. We used Z100(3M) composite resin and placed the composite resin in the hole (4mm thick and 4mm in diameter) of vinyl plate and polymerized it under manufacturer's instructions. Samples were divided into 5 groups by polishing methods. Group 1 was control: resin was polymerized under glass plate, Group 2: resin was polymerized without any polishing procedure, Group 3: resin was polymerized with a polishing procedure of abrasive disc, Group 4: bonding agent was applyed in thin layer an polymerized on the polished polymerized resin surface, Group 5: resin was polymerized under transparent celluloid strip. The surface roughness of each specimen was measured with Sufacoder SEF-30D (Kosaka lab. Ltd) under 0.08mm cut off, 0.05mm/s stylus speed, x40 horizontal magnification, x5000 vertical magnification. The results were as follows : 1. Group 1 showed the most smooth surface in this study. 2. Group 3 showed more rough surface than Group 2. Considering the surface roughness, it would be better to make the shape completely before polymerize the resin. To finish and polish after the polymerization of resin makes less smooth surface. 3. When we use the transparent celluloid strip, minimum finishing procedures are recommended. Any polishing procedure could not recover the smooth resin surface of celluloid strip. 4. Application and polymerization of the thin layer of bonding agent on the polished surface showed the minimum surface smoothing effect.
Glass ; Polymerization ; Polymers