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Objective:To evaluate the effects of magnetron-sputtered ZrSiN/ZrO2 gradient coating on the bonding strength of commercially pure titanium to porcelain.Methods:50 cast titanium specimens were prepared according to the ISO 9693 standard,and divided into 2 groups(n =25).The ZrSiN/ZrO2 gradient coating was deposited on specimens by magnetron sputtering technique,and subsequently a low-fusing porcelain was applied for the samples in the expermental group,the samples in the control group were treated by surface sandblasting.The roughness and surface energy of the samples were measured(n =10).The bonding strength of titanium-porcelain specimens was analyzed by three-point bending test (n =10).Scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDS) were employed to examine the properties of the delaminated and cross-sectioned surfaces.The results were analyzed by paired t-test (α =0.05) with SPSS 1 1.0 software.Results:The roughness of the experimantal group was lower(P ＜ 0.05) and the contact angle was larger(P ＜ 0.05) than those in the control group.The titanium-porcelain bond strength of gradient-coated group was greater than that of control group(P ＜0.05).The SEM and EDS examination results of delaminated and cross-sectioned surfaces also indicated that the gradient-coated group showed more porcelain residues.Conclusion:The bonding strength of porcelain-fused-to-titanium can be improved by magnetron sputtered ZrSiN/ZrO2 gradient coating.
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Objective:To study the effects of different ratios between adhesive and solidification agent on the investment of titanium and to investigate the physical properties of the adhesive on different time intervals.Methods:Mixed adhesive with solidification agent according to different ratio:14∶1,14.5∶1,15∶1.Twelve wax sheet patterns(10 mm?10 mm?0.8 mm)were invested,and then the castings were fabricated.Manipulation performance,appearance of the casting mold,and color of the castings as well as their integrity and edge clarity were observed.The more ideal proportion was selected and determined.Dynamic viscosity,density and pH value of the adhesive were measured on different days(1,3,5 and 7 days).Results:With a adhesive or solidification agent ratio of 14∶1,the solidified time was comparatively short and unable to operate,while with a ratio of 15∶1,the solidified time was too long to solidify and led to the distorted castings.In group with a ratio of 14.5∶1,the primary gel time,intact mold and cast gate were appropriate.The surface of the castings showed bright,metal color after sand blasting.Dynamic viscosity,consistency and pH value of different days for the adhesive had no significant difference.Conclusion:Favorable casting can be fabricated for adhesive mixing with solidification agent when the ratio was 14.5∶1.The adhesive has steady capability in 7 days in practical condition.
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Objective:To study the technical operation of self-developed investment (FUS-invest) for titanium crown and bridge. Methods:Orthogonal design was done. Four factors were taken into account, i.e. water/powder ratio, adhesive/hardener ratio, fine powder proportion in refractory and agitation time. And each factor was ranked into three levels. Slurry fluidity, initial setting time and setting time of every experiment group were studied. Grain size graduation of the best group was measured.Results:Fluidity, initial setting time and setting time were most greatly affected by water/powder ratio and secondly by fine powder proportion in refractory. When water/powder ratio was 7.5∶1 and the content of fine powder was 35%, slurry fluidity was better and initial setting time and setting time were appropriate. When the content of fine powder of AFS fineness number 300 was 31.31%, fineness number 100 was (40.09%), fineness number 70 was 18.05% and adhesive/hardness ratio was 200∶1, the perfect titanium castings could be fabricated. Conclution:The best rules of technical operation for perfect titanium castings are water/powder ratio (7.5)∶1, the content of fine powder 35% and adhesive/hardener ratio 200∶1.
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Objective: To develop a new denture grinding machine to replace the manually grinding procedure for metallic denture parts. Methods: Two hexagonal barrels were symmetrically fixed on a round plate. The direction of rotation and revolution of the barrels were reversed. The denture parts that were put into the barrels together with grinding materials and solution were ground by centrifugal force caused by rotation and revolution of the barrels. Results: The surface roughness of pure titanium castings went down from 1.060 ?m to 0.3113 ?m after ground with the automatic grinding machine using different shapes of grinding materials in series. Conclusion: The automatic grinding machine is competent for grinding the metallic denture parts.
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Objective: To measure and compare the color of a new and a conventional Vita shade guide(VITAPAN 3D-Master and LUMIN RVACUUM-Farbskala) in order to provide the references for clinical application.Methods: Color in the two shade guides was measured with Minolta colorimeter CR-321 under the light of D 65 and reported in CIE1976L*a*b* color system. Each tab was detected 3 times in the same dimensions at the middle facial surface. Mean values were calculated as the shade of the tab.Results: The range of color value in VITAPAN 3D-Master was larger than that in LUMIN R VACUUM-Farbaskala because the lower value tab was added. The distrbution of a* deviated to the red color , while the green color was relatively deficient. The yellow color could cover the color space of Chinese teeth, and the blue was not enough, although the distribution of b* was enlarged. The tabs of the two shade guides did not match with each other. Only a few tabs could not tell in shade by naked eyes. Conclusion: VITAPAN 3D -Master shade guide can not cover the color of Chinese teeth although it has 10 tabs added and color space enlarged.
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Objective: To study the influences of electrolytic voltages on chromatics of anodized titanium. Methods:Titanium specimens were anodized in 0.5 mol/L sulfuric acid and 0.2 mol/L phosphate acid electrolyte using different voltages. The colors of anodized titanium were measured with a computer controlled spectrophotometer, and then evaluated in the CIE1976L*a*b* uniform color scale and Mussell notation. Result: One given volt created one distinguished color. The chromatic values expressed in L*a*b* were fluctuated in different voltage conditions. The hues in Mussell notation were distributed widely within R,Y,G,P of 5 basic colors and YR,GY,BG,PB of 5 interspace colors in the range of 5 to 80 volts. Anodizing with 10 or 45 volts, the specimen's colors appeared two kinds of brilliant goldish yellow, the former reddish slightly and latter greenish a little. The spectrums of the two colors were in the range of wavelengths of yellow to red. Conclusion: The color of the anodized titanium is dependent upon the volts applied. The goldish yellow may be used to improve the esthetics of titanium dentures.
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Objective:To evaluate the effect of preoxidation on the bonding strength of titanium to porcelain.Method:12 titanium plates(25 mm?3 mm?0.5 mm) were pre-oxidated according to usual preoxidation procedure and 12 without preoxidation were used as the controls.The samples(6 in each group) were then bonded with bonding porcelain,opaque porcelain,dentin porcelain and glaze of Duceratin(Degussa) or Vita titankeramik(Vita) respectively.The bonding strength of Ti/porcelain was evaluated using three-point bending test according to ISO 9693 1990 standard. The interface of Ti/porcelain bonding was observed by SEM.Results:Bonding strength(MPa) of Ti/Duceratin preoxided group and the corresponding control was 41.910?2.778 and 33.097?5.297(P0.05),respectively.SEM observation showed inter-lock and tight bonding of Ti/porcelain in pre-oxidated interface,more cracks and gaps between Ti and porcelain in non-pre-oxidated interface.Conclusion:Pre-oxidation may improve bonding strength of Ti/Duceratin system, while has no significant effect on bonding strength of Ti/Vita titankeramik system.
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Objective:To study the feasibility of microarc oxide treatment on the enhancement of titanium-ceramic bonding strength. Method:Titanium samples in the size of 25 mm?3 mm?0.5 mm were prepared with smooth surface(group 1),rough surface(group 2) and microacrc oxide treated surface(group 3). Nickel-chromium alloy samples in the same size were prepared (group 4). The surface of the samples was observed by scanning electron microscope(SEM) and dispersive spectrometry analysis. Then, the samples were bonded to porcelain. The bonding interface was observed by SEM. The bonding strength of the samples was measured by a three-point bending test according to ISO 9693.Results:Microarc oxide treated surface was rough and porous. The interface of microarc oxide treated surface bonded to porcelain was compact. The bonding strength(MPa) of the samples of group 1,2,3 and 4 to porcelain was 30.79?1.3,36.12?3.03,45.84?3.15 and 48.35?3.06 respectively(group 3 vs group 1 or 2 P0.05). Conclusion:The microarc oxide treatment on titanium can increase the titanium-ceramic bond strength.
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0.05 ;Ti milled/VITA vs Ni Cr/VITA P
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0.05),while there was significant difference among other groups(P
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Objective:To investigate the effects of oxidation of titanium on bonding strength of titanium and porcelain. Methods: 24 specimens with a size of 28 mm ?3 mm?0.5 mm were cast from pure titanium and divided into 4 groups, 6 specimens each group. Group 2, 3 and 4 were degassed at 750, 800 and 900 ℃ respectively, group 1 not degassed as negative control, then a uniform thickness of 1mm of Noritake super porcelain Ti-22 was veneered on 8 mm?3 mm in the central portion of each specimen. The specimens were subjected to a three-point bending test on a load-test machine with a span of 20 mm, and the failure loads were recorded and analyzed statistically. The opposite side of specimens of each group were observed by thin-film X-ray diffraction. Results: The failure loads (N) of group 1, 2, 3 and 4 were 10.33, 9.98, 5.53, 3.37. The oxide of group 1 was Ti6O only, the oxide of the gropu 2, 3, and 4 were Ti6O and TiO2 and the amount of TiO2 increased significantly as the temperature iss increasing. Conclusion: The oxide adherence strength value for pure titanium decreased while the oxide temperature is increasing. The higher of the degassed temperature of the specimens, the more TiO2 can be found in the oxide film and the smaller the failure load is, which indicats that oxidation of titanium has a negative effect on the bonding strength of porcelain and titanium.
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typeⅢgold alloy. Candida albicans could be found on acrylic resin ,but there was little on the other 4 dental metals. Conclusion: From the perspective of reserving periodontal tissue, pure-Ti and typeⅢgold alloy seem to be the first choice, Co-Cr alloy and Ni-Cr alloy are the second.