| ObjectiveTo serve as a direction for clinical use of mouthwash, the present study was aimed to the corrosion resistance and surface morphology of dental prosthetic metal in different mouthwash with electrochemical method.MethodsFive kinds of metal sample(Ni-Cr alloy, Co-Cr alloy, Pd-Ag alloy, Frame Co-Cr alloy and CP Ti) were casted,24 for each. And each kind of metal was divided into four groups in random after the same surface pretreatment: Group A(Chlorhexidine mouthwash: p H=6.09,c(F-)=0%),Group B(Listerine mouthwash: p H=4.25,c(F-)=0.02%),Group C(Qinglang mouthwash: p H=6.84, c(F-)=0.1%) and Group D(Artificial saliva control group: p H=6.80, c(F-)=0%). Tafel curves of all the metal samples in different group were measured by electrochemical methods. According to the fitting result of Tafel curves, we could obtain the parameters: self-corrosion potential(Ecorr), self-corrosion current density(Icorr) and the polarization resistance(Rp). The surface morphology change of the test samples before and after the electrochemical corrosion was observed by FESEM. SPSS16.0 was used to analyze the dates.Results1. Tafel curve parameter analysis:( 1) Ecorr: Ni-Cr alloy in Group C was the lowest(P<0.05), and in Group D was the highest(P<0.05), Pd-Ag alloy in Group B and C was lower than in Group A and D(P<0.05), CP Ti Group D was higher than in Group A(P<0.05),and in Group C was the highest(P<0.05). There was no significant difference among the rest groups(P>0.05).(2)Icorr: In Group B was the highest(P<0.05). There was no significant difference between Group A and D(P>0.05). CP Ti in Group C was higher than in Group A and D(P<0.05), but the rest kinds of metal in Group A and D had no significant difference with Group C(P>0.05).(3)Rp: In Group B was the lowest(P<0.05).For frame Co-Cr alloy, Group A and C had no significant difference with Group D(P>0.05),but the rest kinds of metal in Group A and C were lower than in Group D(P<0.05). In Group C, CP Ti was lower than in Group A(P<0.05), the rest kinds of metal in them had no significant difference(P>0.05).2. Compared to the Tafel curves in artificial saliva group: the Tafel curves in Group A and C of all the metal shifted with different degrees except frame Co-Cr alloy; the Tafel curves of all the metal in Group B superimposed significantly.3. FESEM observation result: before corrosion, there was no corrosion could be observed on the surface of all the five kinds of metal. After corrosion: in Group A,small and swallow pitting corrosion could be seen on the surface of frame Co-Cr alloy and CP Ti, but on the rest three kinds of metal the pitting corrosion was swallow but large; in Group B, intensive, shallow but large pitting corrosion could be visible on the surface of CP Ti, and large and deep pitting corrosion could be seen on other kinds of metal; in Group C, the pitting corrosion of frame Co-Cr alloy was small and light,and big and deep pitting corrosion could be visible on the surface of Ni-Cr alloy,Pd-Ag alloy and CP Ti. On the surface of the Co-Cr alloy, the pitting corrosion was large but relative swallow;in Group D, light and small pitting corrosion appeared on the surface of the all the metal.Conclusions1. The corrosion resistance of dental metal was difference in different kinds of mouthwash. The acid fluoride-containing mouthwash did a significance influence on corrosion resistance of the dental metals.2. Excluding the frame Co-Cr alloy, the Qinglang fluoride-containing mouthwash could decrease the corrosion resistance of the detected dental metals; CP Ti was quite sensitive to fluoride.3. The p H of the mouthwash could alter the corrosion resistance of the five kinds of dental metal, but slightly acidic mouthwash had little effect on frame Co-Cr alloy.With the decreasing of p H, the influence of the mouthwash on dental metal increased. |
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