The Effect Of PH And F To The Galvanic Corrosion Which Happened Between Ti Implant And The Dental Alloys

Objective: The purpose of this study was to evaluate the galvanic corrosion behavior between HBIC-Ti implant and Au-Pt alloy,Ni-Cr alloy, Co-Cr alloy,casting pure Ti in artificial saliva with different pH and fluoride contents.It was used for references and basis for selecting suprastructure in dental implantation dental alloys in the clinic.Methods:1 Preparation of alloys specimens: HBIC-Ti implant(Ti-HBIC) of commonly used dental alloys : Ni-Cr alloys (Ni), Co-Cr alloy(Co), casting pure Ti(Ti) were selected.Each type of alloy was cast into 4 samples under the manufacture instruction, all samples were shaped into a cylindrical form, in order to constitute the cap of a rotating disk electrode. With 4mm diameter, 10mm high, cylinders were wedged into PTFE pipage with 3.5mm diameter,the exposed surface of metal was 0.1257cm2. All the samples were ground and polished as follows: the specimens were subjected to waterproof abrasive paper on 220, 400, 600, 800 grit silicon carbide and then to metallographic sandpaper on 400,800,1200 grit silicon carbide and 20-50nm Al2O3,at last they were immersed into artificial saliva for 24 h.2 The preparation of the artificial saliva : Six different artificial saliva:pH6.8(A),pH5.6(B),pH6.8with0.1%F-(C),pH5.6with0.1%F-(D), pH6.8with0.2%F-(E) ,pH 5.6 with0.2%F-(F).3 In A,B,C,D,E,F artificial saliva at 37±0.5℃, the potential in early immersion(E1),the mixed potential(E2),and galvanic current density (Id) which were between HBIC-Ti implant and Ni-Cr alloy, Co-Cr alloy, casting pure titanium were tested by the classic three electrodes system of electrochemical method.4 Surface analysis by SEM. Results:1 The potential in early immersion (E1) of four couples in the same artificial saliva.1.1 The potential in early immersion (E1) of four different couples in the artificial saliva A were E1Au>E1Ti>E1Co>E1Ni, E1Co was bigger than E1Ni (p<0.05) and smaller than E1Ti (p<0.05).1.2 The potential in early immersion (E1) of four different couples in the artificial saliva B were E1Au>E1Co>E1Ti>E1Ni. There was significant difference between any two of the four couples (p<0.05).1.3 The potential in early immersion (E1) of four different couples in the artificial saliva C were E1Au>E1Co>E1Ni>E1Ti. E1Ni was smaller than E1Co and E1Au, E1Ti was smaller than E1Co and E1Au (p<0.05). There were no significant difference between E1Ni and E1Ti (p>0.05).1.4 The potential in early immersion (E1) of four different couples in the artificial saliva D were E1Au>E1Co>E1Ni>E1Ti. There were no significant difference between any two of the four couples except E1Ni and E1Co.1.5 The potential in early immersion (E1) of four different couples in the artificial saliva E were E1Au>E1Co>E1Ni>E1Ti. There was significant difference between any two of the four couples (p<0.05).1.6 The potential in early immersion (E1) of four different couples in the artificial saliva E were E1Au>E1Ni>E1Co>E1Ti. There was significant difference between E1Ti and any one of the other three couples (p<0.05). There were no significant difference between any two of E1Ni, E1Au and E1Co (p>0.05).2 The potential in early immersion (E1) of one couple in the different artificial saliva.2.1 Aurum- platinum alloy The potential in early immersion (E1)of Au-Pt alloy tested by A,B,C,D,E,F artificial saliva respectively were AuA>AuB>AuC>AuD>AuF>AuE.There were no significant difference between AuA and each of the other couples(p>0.05).2.2 Nickel-chromium alloy The potential in early immersion (E1)of Ni-Cr alloy tested by A,B,C,D,E,F artificial saliva respectively were NiF> NiA>NiB>NiD>NiC>NiE,NiF. There was significant difference between NiF and each of the other couples except NiA. There was significant difference between E1B and each of the other couples except NiA.2.3 Cobalt-chromium alloy The potential in early immersion (E1)of Co-Cr alloy tested by A,B,C,D,E,F artificial saliva respectively were CoA>CoB>CoC>CoE>CoD>CoF. There was significant difference between CoA and CoD, and between CoA and CoE (p<0.05). There was significant difference between CoB and CoD (p<0.05).2.4 Casting pure titanium The potential in early immersion (E1)of casting pure Ti alloy tested by A,B,C,D,E,F artificial saliva respectively were TiA>TiB>TiC>TiE>TiD>TiF. There were no significant difference between TiF and TiD, neither between TiF and TiE, TiC and TiE (p>0.05). There was significant difference between any two of the other groups (p<0.05).3 The mixed potential (E2) of four couples in the same artificial saliva.3.1 In the artificial saliva of A, the E2 of four couples were E2Au>E2Ti>E2Co>E2Ni. E2Au was bigger than E2Ni (p<0.05) and there were no significant difference between the two of the other groups (p>0.05).3.2 In the artificial saliva of B, the E2 of four couples were E2Au>E2Co>E2Ni>E2Ti.E2Au was bigger than the potential of the other groups (p<0.05). There was significant difference between E2Ni and E2Ti, and between E2Ni and E2Co (p<0.05).3.3 In the artificial saliva of C, the E2 of four couples were E2Au>E2Co> E2Ni>E2Ti.There were no significant difference between E2Au and E2Co, E2Ni and E2Ti (p>0.05). There was significant difference between any two of the other groups (p<0.05).3.4 In the artificial saliva of D, the E2 of four couples were E2Au>E2Ni> E2Co>E2Ti. There was significant difference between E2Ti and any one of the other three couples (p<0.05). There were no significant difference between any two of E2Ni, E2Au and E2Co (p>0.05).3.5 In the artificial saliva of E, the E2 of four couples were E2Au> E2Co>E2Ni>E2Ti. There was significant difference between any two of the four couples (p<0.05).3.6 In the artificial saliva of F, the E2 of four couples were E2Ni> E2Co>E2Au>E2Ti. There was significant difference between E2Ti and any one of the other three couples (p<0.05).4 The mixed potential (E2) of one couple in the different artificial saliva.4.1 Aurum- platinum alloy The mixed potential (E2) of Au-Pt alloy tested by A,B,C,D,E,F artificial saliva respectively were AuA>AuB>AuC>AuE>AuD>AuF. There was significant difference between AuF and each of the other couples. There were no significant difference between AuA and each of the other couples except AuF. There was significant difference between AuB and AuD, so was AuB and AuE (p<0.05).4.2 Nickel-chromium alloy The mixed potential (E2) of Ni-Cr alloy tested by A,B,C,D,E,F artificial saliva respectively were NiF>NiB>NiD>NiA>NiC>NiE. There was significant difference between NiB and NiD, so was NiB and NiE, NiD and NiE, NiE and NiF (p<0.05). There were no significant difference between the two of the other groups (p>0.05).4.3 Cobalt-chromium alloy The mixed potential (E2) of Co-Cr alloy tested by A,B,C,D,E,F artificial saliva respectively were CoA>CoB>CoC>CoE>CoD>CoF. There was significant difference between CoF and CoA, so was CoF and CoB, CoF and CoC (p<0.05). There were no significant difference between CoF and CoD, CoF and CoE. (p>0.05)4.4 Casting pure titanium The mixed potential (E2) of Casting pure Ti alloy tested by A,B,C,D,E,F artificial saliva respectively were TiA>TiB>TiC>TiE>TiD>TiF. There were no significant difference between TiB and TiC, TiC and TiE. (p>0.05)and there was significant difference between any two of the other groups(p<0.05).5 The galvanic current density (Id) of one couple in the different artificial saliva (μA /cm2)5.1 Aurum- platinum alloy The galvanic current density (Id) of Au-Pt alloy tested by A,B,C,D,E,F artificial saliva respectively were AuA0.05).5.2 Nickel-chromium alloy The galvanic current density (Id) of Ni-Cr alloy tesed by A,B,C,D,E,F artificial saliva respectively were NiD0.05).5.3 Cobalt-chromium alloy The galvanic current density (Id) of Co-Cr alloy tesed by A,B,C,D,E,F artificial saliva respectively were CoA0.05).5.4 Casting pure titanium The galvanic current density (Id) of casting pure Ti alloy tested by A,B,C,D,E,F artificial saliva respectively were TiA0.05).6 The galvanic current density (Id) of different couples in the same artificial saliva (μA /cm2)6.1 In the artificial saliva A, the Id of four couples respectively were IdNi>IdCo>IdTi>IdAu. There were significant difference between Ni and Au, Ni and Ti. There were no significant difference between Ni and Co, Au and Ti.Neither were Co and Ti, Co and Au (p>0.05).In the artificial saliva B, the Id of four couples respectively were IdNi>IdCo>IdAu>IdTi. The Id tested in Ni was bigger than that tested in Co,Au,Ti. (p<0.05) There were no significant difference between any two of Co,Au,Ti(p>0.05).6.2 In the artificial saliva C, there were no significant difference between any two of four couples (p>0.05). In the artificial saliva D,the Id of four couples respectively were IdAu0.05).6.3 In the artificial saliva E, the Id of four couples respectively were IdAu0.05).In the artificial saliva F, the Id of four couples respectively were IdAu casting pure titanium> Co-Cr alloy> Ni-Cr alloys.2 Compared with the neutral artificial saliva, galvanic current density of four kinds of alloys in the acidic artificial saliva of pH = 5.6 has not changed significantly. pH = 5.6 has no significant effect on the mixed potential and early immersion potential of Co-Cr alloy, Ni-Cr alloy, Au-Pt alloy. The early immersion potential and mixed potential were lower than that in neutral artificial saliva, but remained at a high level.3 The galvanic current density(Id) of Au-Pt alloy , Co-Cr alloy and casting pure Ti were promoted by adsition of F- in the acidic pH = 5.6 artificial saliva. Casting pure Ti was more sensitive than other alloys.There was a significant difference with that in pH=6.8 artificial saliva. When the fluoride concentration came to 0.2%, the galvanic current of Ni-Cr alloy oscillations significantly was from -0.4μA to 0.4μA. The clinical environment should try to avoid this.4 Gold alloy and casting pure titanium are reasonable choices of metal for the upper crown of the implant.Decreacing of pH and adsition of F- in the acidic artificial saliva intensified the galvanic corrosion between HBIC implant alloy and crown material, so the patient with pure Ti shoud be avoid the use of the things contained F- .At the same time,keeping oral healthy which retains pH at normal limits is good to decreace the galvanic corrosion.