STUDY OF CORROSION BETWEEN A TITANIUM IMPLANT AND DENTAL ALLOYS

The infiltration of saliva into the multi-metallic structures on titan ium implants brings different types of alloys into temporary or perman ent contact. In this way a galvanic cell is established as a result of their potential difference. The galvanic cell phenomenon is compounde d by another type of corrosion resulting from the geometry of the asse mbly: localized crevice corrosion. Fifteen galvanic couples (Ti/gold-b ased alloys, Ti/palladium-based alloy and Ti/non-precious alloys) were studied. Various electrochemical parameters (E(corr), E(common), E(co uple corr), E(crevice), i(corr), i(couple corr) and Tafel slopes) were analysed. The galvanic currents measured are of the same order of mag nitude (except Ti/stainless steel). They remain low. Application of th e mixed-potential theory shows that titanium in coupling with the allo ys studied will be under either cathodic or anodic control. According to the results obtained, an alloy that is potentially usable for super structures in a galvanic coupling with titanium must fulfil a certain number of parameters: in a coupling, titanium must have a weak anodic polarization; the current generated by the galvanic cell must also be weak; the crevice potential must be markedly higher than the common po tential.