Objective: To study the property of galvanic corrosion of soft magnetic alloy and 4 kinds of dental alloys in simulated oral environment. Methods: 6 samples of Ni Cr, TA 2, Ti75 and 30 of Fe 16Cr 2Mo in the size of d 15 mm?3 mm were prepared and put into artificial saliva. An electrochemical method was used in the measurement of electric potential of corrosion (Ecorr), potential dynamic polarization and galvanic current density of different galvanic couple, the anticorrosive property of four galvanic couples was analyzed statistically. Results: The ecorr value(mV) of Ti75, TA 2, Co Cr,Fe 16Cr 2Mo and Ni Cr was -138.31?2.89, -150.35?1.04, -186.21?3.79, -218.35?0.84 and -240.49?1.73 respectively ( P

0.05);the elongation (%) 470?9.5,560?8.2 and 470?5.8 (SY-1 versus SY-2 or MDX-4-4210,P

Objective: To find out the infinity optical thickness of SY-1 silicone elastomers when color difference(△E) is equal to 1.5 . Methods: Silicone elastomer samples with thickness from 0.5 mm to 10 mm of SY-1 silicone elastomer were measured by CIE-1976-L *a *b * relative to CIE source against a white and a black background by using Minolta colorimeter . Color difference was calculated as △E=[(△L *) 2+( △a *) 2+(△b *) 2] 1/2 . The infinity optical thickness of SY-1 silicone elastomer when △E=1.5 was calculated by regression formulation. Result: When △E was equal to 1.5, the infinity optical thickness of SY-1 silicone elastomer was 7.60 mm. Conclusion: In order to get ideal effect the supports should be treated with colorant when the thickness of silicone elastomer covering the surface of supports in maxillofacial prostheses is thinner than 7.60 mm.

0.05).The elongation at break of SY-1 was stronger than that of MDX4-4210 (P

0.05) respectively. Conclusion: The SY 1 silicon elastomer have suitable physical, mechanical and anti ozone aging properties.

砄bjective:To compare the adherent ability of Candida albicans on the surface of two kinds of silicone elastomer used as prosthodontic materials and to study the factors affecting the adherence.Methods: Candida albicans were cultured on the surface of SY 1 and MDXA 4210 with or without saliva acquired pellicle for 10 min, then the number of the bacteria was counted.Results:With or without saliva acquired pellicle,the number (1?10 3/mm 2) of C.albicans on SY 1 was 24.5?0.88 and 2.0?0.47 respectively( P 0.05 ).Conclusion:There is little difference between the adherent ability of C.albicans on the two kind of silicone elastomer.Saliva acquired pellicle can decrease the adherence.

Objective:To study the effects of ozone aging on the color stability of the SY-1 silicone elastomer. Methods :40 SY-1 silicone elastomer samples were prepared and grouped into 4 with 10 in each group. The samples in each group were painted with gouache color, oil pigment and inorganic salt respectively, one group was used as the control. Then the samples were treated with ?=10 -4 % ozone at 10～16 mm/s for 72 h. The color of the samples were measured by 1976 CIE L *a *b * standards of chromatic aberration before and after ozone treatment. The chromatic aberration was expressed as △E=〔△L *)2+(△a *)2+(△b *)2〕 1/2. Results :After 72 hours of ozone aging, △E of the samples in the groups of control, gouache color, oil pigment and inorganic salt was 0.55?0.11, 3.55 ? 0.09, 1.40 ? 0.11 and 1.57 ? 0.07 respectively ;Conclusion:Under the ozone aging condition, the SY-1 silicone elastomers stained with oil pigment and inorganic salt may have better color stability than that with gouache color.

0.05).Tight integration was found between the two materials in the two groups and there was no distinct interface examined by SEM.Conclusions:GP-084 cellular silicone elastomer and SY-1 silicone elastomer may be adhered completly.

Objective To study the biosafety of colored alumina-glass composite by mucosa irritation test. Methods The colored alumina-glass composite and a non-irritating material were separately fixed to the oral mucosa of a mouse. The contact parts were examined with bare eye, histologically and cytologically. Results No obvious inflammation of the mucosa was detected in the site where colored alumina-glass composite was in contact. Conclusion Alumina-glass composite has good biosafety.

Objective: To evaluate the corrosion resistance of Ni-Cr alloy with different coatings in neutral and acid saliva by electrochemistry method. Methods: Measured the self-corrosion potential (Ecorr) and polarization resistance(Rp) curves of Ni-Cr alloy models with different coatings in neutral and acid artificial salivas. Results: The Ecorr of the Ni-Cr alloys all showed positive values, the electrochemistry corrosion and galvanic corrosion were not detected. Conclusion: Ni-Cr alloy with titanium nitride coating, gold electroplating coating, gold-paste layer and gold-porcelain blended layer have both anti-corrosion and esthetical function without changing its own property.