No abstract available.
Glass*

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

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

The authors analysed the interpupillary distance, the distance between optical centers and the distance from the upper margin of the lens to the optical center in 297 spectacles wearers. The results were as follows: 1. Among the 297 glasses wearers, myopic glasses wearers accounted for 226 persons(76.09%), and hyperopic glasses wearers for 71 persons(23.91%). 2. Among the 297 glasses wearers, the distance between optical centers coincided with the interpupillary distance in 51 persons(17.17%), and was incongruous in 246 persons(82.83%). 3. Among the 297 glasses wearers, the distance from the upper margin of the lens to the optical center was the same in both eyes in 152 persons(51.19%), and was incongruous in 145 persons(48.81%). 4. Among the 246 persons in whom the distance between optical centers of their glasses did not coincide with the interpupillary distance, the horizontal prismatic effects of both eyes overpassed the aberration of tolerance of ophthalmic dispensing in 46 persons(18.70%), and the maximum horizontal prismatic effect of one eye was 5.85 prism diopters. 5. Among the 145 persons in whom the distance from the upper margin of the lens to the optical center of their glasses did not coincide in both eyes, the vertical prismatic effects overpassed the aberration of tolerance of ophthalmic dispensing in 48 persons(33.10%), and the maximum vertical prismatic effect was 2.47 prism diopters.
Eyeglasses* ; Glass ; Humans

OBJECTIVES: This study aimed to evaluate the relationship between the cyclic fatigue of a K3 file and internal stress intentionally induced until the activation of the auto-stop function of the torque-controlled motor. MATERIALS AND METHODS: K3 (Sybron Endo) .04 and .06 taper, size 25, 30, 35, 40 and 45 were used in this study. To give the internal stress, the K3 files were put into the .02 taper Endo-Training-Bloc (Dentsply Maillefer) until the activation of the auto-stop function of the torque-controlled motor. The rotation speed was 300 rpm and torque value was 1.0 N.cm. K3 were grouped by the number of induced internal stress and randomly distributed to 4 experimental groups (n = 10, Stress 0 [control], Stress 1, Stress 2 and Stress 3). For measuring the cyclic fatigue failure, the K3 files were worked against a sloped glass block and time for file separation was recorded. Data was statistically analyzed Statistical analyses were performed using two-way ANOVA and Duncan post-hoc test at p < 0.05 level. RESULTS: Except .04 taper size 30 in Stress 1 group, there were statistically significant differences in time for file separation between control and all experimental groups. K3 with .04 taper showed higher cyclic fatigue resistance than those of .06 taper. CONCLUSION: In the limitation of this study, the cyclic fatigue of the K3 file was influenced by the accumulated internal stress from use until the auto-stop function was activated by the torque-controlled motor. Therefore, clinicians should avoid the reuse of the K3 file that has undergone auto-stops.
Fatigue ; Glass ; Intention ; Torque

No abstract available.
Adhesives* ; Dentin* ; Glass*

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