PURPOSE: It is difficult to exactly determine the surface dose and the dose distribution in buildup region of high energy X-rays by using the conventional ion chamber. The aim of this study is to evaluate the accuracy of widely used dosimetry systems to measure the surface dose and the depth of maximum dose (dmax). MATERIALS AND METHODS: We measured the percent depth dose (PDD) from the surface to the dmax in either a water phantom or in a solid water phantom using TLD-100 chips, thimble type ion chamber, diode detector, diamond detector and Markus parallel plate ion chamber for 6 MV and 15 MV X-rays, 10 10 cm2, at SSD=100 cm. We analysed the surface dose and the dmax. In order to verify the accuracy of the TLD data, we executed the Monte Carlo simulation for 6 MV X-ray beams. RESULTS: The surface doses in 6 MV and 15 MV X-rays were 29.31% and 23.36% for Markus parallel plate ion chamber, 37.17% and 24.01% for TLD, 34.87% and 24.06% for diamond detector, 38.13% and 27.8% for diode detector, and 47.92% and 36.01% for thimble type ion chamber, respectively. In Monte Carlo simulation for 6 MV X-rays, the surface dose was 36.22%, which is similar to the 37.17% of the TLD measurement data. The dmax in 6 MV and 15 MV X-rays was 14~16 mm and 27~29 mm, respectively. There was no significant difference in the dmax among the detectors. CONCLUSION: There was a remarkable difference in the surface dose among the detectors. The Markus parallel plate chamber showed the most accurate result. The surface dose of the thimble ion chamber was 10% higher than that of other detectors. We suggest that the correction should be made when the surface dose of the thimble ion chamber is used for the treatment planning for the superficial tumors. All the detectors used in our study showed no difference in the dmax.
Diamond ; Water

The effect of surface roughness of ceramic-polymer CAD/CAM blocks on the mechanical properties was investigated in this study. Commercially available Polyglass (Vericom, Korea) and Enamic (Vita, Germany) were selected for this purpose. They were cut into either (4.0×2.1×17.0) mm and (3.0×4.0×17.0) mm, followed by grinding, and polished sequentially with 6 µm and 1 µm diamond paste. Flexural strength, fracture toughness, and Weibull analysis were determined according to ISO 6872 Dentistry-Ceramic materials. The elastic moduli were calculated from a stress-strain curves under flexural loading. The statistical significances of the mechanical properties between the products and surface roughness were analyzed with ANOVA and pared t-test at a significance level of 0.05. After grinding with 6 µm diamond paste after cutting by observing with an atomic force microscope, the arithmetic average roughness decreased to 47~49% and the maximum roughness decreased to 68~69%. When polishing with 1 µm diamond paste, The average roughness decreased to 13~22% and the maximum roughness decreased to 16~19%. When the flexural load was applied, stress increased linearly and fractured without plastic deformation both Polyglass and Enamic. As the surface roughness decreased, the mechanical properties were increased both Polyglass and Enamic. However, the mechanical properties of Polyglass increased up to P3, while Enamic showed almost maximal values at E2, after that there was no significant differences between E2 and E3. It could be due to the different microstructure between two blocks used in this experiment.
Diamond ; Plastics

STATEMENT OF PROBLEM: It is difficult about assessing the loosening tendency of conical connection type implant after cyclic loading with diamond like carbon coating one-piece abutments, and also about the retightening effect. PURPOSE: This study was performed to investigate the influence of one-piece abutment screw retightening after 5.0X10(4) cyclic loading and Diamond like coating MATERIAL AND METHODS: Thirty two ITI implant were divided to 4 groups. Group 1,3-titanium abutment, group 2,4 - diamond like carbon coated abutment. Group 1,2 - 20.0X10(4) cyclic loading after 5.0X10(4) cyclic loading, Group 3,4- after 20.0X10(4) Cyclic loading. After cyclic loading, periotest values were taken and removal torque values of abutments were measured with a digital torque gauge. RESULTS: 1. The removal torque of group 2 after 5.0X10(4) cyclic loading is slightly greater than the other groups but not significantly higher than others (P>0.05). 2. The final removal torque values after 20.0X10(4) cyclic loading of group 1 is bigger than group 3, and group 2 is bigger than group 4, but not significantly higher (P>0.05). 3. The final removal torque values after 20.0X10(4) cyclic loading of all groups are not significantly different (P>0.05).
Carbon ; Diamond ; Torque

This study was performed to investigate the retrievability of the cementation type implant abutments. The cements used in this study were Cavitec, Tembond and Zine Phosphate Cement. The types of surface conditioning were no treatment, 50 microne sandblasting, 250 microne sandblasting, fine diamond finishing point and coarse diamond point. The retention of cast crown was measured with Instron University Testing Machine(Instron Engineering Co., U.S.A.) The results were as follows: 1. The Maximium retention was obtained by the group of Z.P.C. cementation and Coarse diamond point surface conditioning. 2. Z.P.C. shows maximum retention, and reduced in orders Tembond, Cavitec, No cement. 3. The value of retention of surface condition was highest in coarse diamond point, lowest in no tretment. 4. The similar results were obtained between fine diamond point and 50 microne sandblasting, coarse diamond point and 250 microne sandblasting. 5. The were no direct corelation between mechanical retetnion and cementation retention.
Cementation* ; Crowns ; Diamond

The purpose of this study was to evaluate the effect of multiple application of all-in-one dentin adhesive system on microtensile bond strength using confocal laser scanning microscope and microtensile bond strength test. Flat occlusal dentin surfaces were prepared using low-speed diamond saw. In group I, Scotchbond Multipurpose (SM) was applied by manufacturer's recommendation. In group II, after Adper Prompt L-Pop was applied for 15s and light cured for 10s, the second coat was re-applied and light-cured. In group III, after light-curing the second layer, the third coat was re-applied and light-cured. Specimens bonded with a resin-composite were sectioned into resin-dentin stick for measuring the adhesive layer thickness by confocal laser scanning microscope and evaluating micro-tensile bond strength. The adhesive layers of three-step dentin adhesive system, 3 coats of Adper Prompt L-Pop had significantly thicker than SM, 2 coats of Adper Prompt L-Pop (p < 0.05). However, there was no significant differences in bond strengths between SM and 3 coats of Adper Prompt L-Pop (p > 0.05). And SM, 3 coats of Adper Prompt L-Pop had significantly higher than 2 coats of Adper Prompt L-Pop in bond strengths (p < 0.05).
Adhesives* ; Dentin* ; Diamond

OBJECTIVEThe aim of this study was to observed the influence of deposition time on chromatics during nitrogen-doped diamond like carbon coating (N-DLC) on pure titanium by multi impulse are plasma plating machine.

METHODSApplying multi impulse are plasma plating machine to produce TiN coatings on pure titanium in nitrogen atmosphere, then filming with nitrogen-doped DLC on TiN in methane (10-80 min in every 5 min). The colors of N-DLC were evaluated in the CIE1976 L*a*b* uniform color scale and Mussell notation. The surface morphology of every specimen was analyzed using scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS).

RESULTSWhen changing the time of N-DLC coating deposition, N-DLC surface showed different color. Golden yellow was presented when deposition time was 30 min. SEM showed that crystallization was found in N-DLC coatings, the structure changed from stable to clutter by varying the deposition time.

CONCLUSIONThe chromatics of N-DLC coatings on pure titanium could get golden yellow when deposition time was 30 min, then the crystallized structure was stable.

The purposes of this study were to evaluate the effect of adhesive property on microtensile bond strength and to determine the failure mode. Flat occlusal dentin surfaces were prepared using low-speed diamond saw. The dentin was etched with 37% phosphoric acid. The following adhesives were applied to the etched dentin to manufacturer's directions; Scotchbond Multi-Purpose in group SM, Prime&Bond NT in group NT, Scotchbond Multi-Purpose followed by Tetric-flow in group TR. After adhesive application, a cylinder of resin-based composite was built up on the occlusal surface. Each tooth was sectioned vertically to obtain the 1 x 1mm2 "sticks". Microtensile bond strength were determined. Each specimen was observed under stereomicroscope and scanning electron microscope (SEM) to examine the failure mode. Data were analyzed using one way ANOVA. The results of this study were as follows; 1. The microtensile bond strength value were; group SM (18.98 +/- 3.01MPa), group NT (16.01 +/- 4.82MPa) and group TR (17.56 +/- 3.22MPa). No significant statistical differences were observed among the groups (P>0.05). 2. Most of specimens showed mixed failure. In group TR, there was a higher number of specimens showing areas of cohesive failure in resin.
Adhesives* ; Dentin* ; Diamond ; Humans* ; Tooth

This study was performed to investigate the surface roughness of the Cerec Vita Mark II polished by various polishing techniques, compare with that of the Vintage enamel porcelain glazed by high temperature glazing technique. All of the Cerec specimen were finished with sequential use of high speed diamond burs(grit 45, 30 and 15microneter). The groups were divided into 5 groups : Group I : Cerec Vita Mark II block specimens polished with Sof-lex discs. Group II : Cerce Vita Mark II block specimens polished with Two Striper MPS. Group III: Cerce Vita Mark II block specimens polished with Enhance. Group IV: Cerce Vita Mark II block specimens polished with Porcelain laminate polishing FG kit. Group V: Vintage enamel porcelain glazed by high temperature glazing Technique. Each group was consisted of 10 specimens. The surfaces produced were examined quantitatively using a laser specular reflectance machine(Perthen RM600-s, Feinpruf Perthen GmbH., Germany) and qualitatively under SEM(JSM-5400, JEOL, Japan). The Results were as follows : 1. The arithmetic mean roughness value(Ra) in groups 1, 2, 3 and 4 was higher than that of group5. There was statistically significant difference(P<0.05). 2. The arithmetic mean roughness value(Ra) decreased in the following orders : group 1, group 2, group 4, group 3 and there was no statistically significant difference between group 1 and group 2, group 3, and group 4. There was statistically significant difference among group 1, 2, and group 3, 4 and group 5(P<0.05). 3. The maximum individual peak-to-valley-height(Rmax) decreased in the following orders : group 2, group 1, group 4, group 3, group 5 and there was no statistically significant difference between group 1 and 2, group 1 and group 4, group 3 and group 5. There was statistically significant difference among group 1, 2, and group 1, 4 and group 3, 5(P<0.05). 4. The treated surfaces of group 5 had smoother surface than that of groups 1, 2, 3, 4 with SEM.
Dental Enamel ; Dental Porcelain ; Diamond

PURPOSE: The aim of this study was to investigate effect of specimen preparation method on the microtensile bond strength of veneering ceramic to zirconia core. MATERIALS AND METHODS: Cylindrical Lava zirconia block (3M ESPE, Seefeld, Germany) was cut into discs using a diamond disc. After sintering, the core specimens were placed in an adjustable mold and veneered with Lava ceram (3M ESPE, Seefeld, Germany). The disc shaped specimen of group 1 was cut into microbars (1x1x7 mm3) using a low speed diamond disc under water cooling (n = 15). The specimen of group 2 was cut into microbars (1.2x1.2x7 mm3) in the same way. Whereafter the microbars were trimmed (1x1x7 mm3) using a thick diamond disc under water cooling (n = 15). The microtensile bond strength was tested in a microtensile tester (Instron 8848, Instro(R) Co., Norwood, USA). Fractured microtensile specimens were analyzed under a stereomicroscope (MZ6, Leica Microsystems GmbH, Wetzlar, Germany) at magnification x30. RESULTS: The microtensile bond strength of group 1 (28.8 +/- 7.0 MPa) was significantly higher than group 2 (11.0 +/- 3.3 MPa) (P=.00). CONCLUSION: It appears advisable to avoid the trimming action, especially high strength ceramic specimens.
Ceramics ; Diamond ; Fungi ; Water ; Zirconium

The purpose of this study was to compare the fitness of the IPS Empress ceramic crowns according to margin type such as bevel, shoulder, rounded shoulder, shoulder with bevel, rounded shoulder with bevel and grooved bevel. After 10 experimental dies were constructed for each group, the IPS Empress ceramic crowns were fabricated on the dies, cemented with resin cement(Bistite resin cement, Tokuyama Soda Co. Ltd., Japan) and embeded in clear epoxy resin. Each specimen was sectioned with a low speed diamond saw in both the faciopalatal and the mesiodistal direction. The cement film thickness was measured with a measuring microscope. The obtained results were as follows : 1. The fitness at the external margin was good in the following order: rounded shoulder(28.99), shoulder with bevel(31.33), grooved bevel(31.79), rounded shoulder with bevel(34.65), bevel(35.02) and shoulder(35.08). However there is no significant statistical difference. 2. The fitness at the internal margin of bevel(25.75), rounded shoulder(31.24), shoulder with bevel(32.07) and rounded shoulder with bevel(34.45) was better than that of shoulder(47.98). 3. The fitness at the axial surface of bevel(26.58) was better than that of shoulder(49.59). 4. The fitness at the central fossa was good in the following order: shoulder with bevel(38.88), grooved bevel(40.46) rounded shoulder with shoulder(46.29), shoulder(48.91), bevel(49.47) and rounded bevel(52.07). However there is no significant statistical difference. 5. Overall fitness of bevel(29.71), rounded shoulder(32.49) and shoulder with bevel(34.47) was better than that of shoulder(44.73).
Ceramics* ; Crowns* ; Diamond ; Resin Cements ; Shoulder