OBJECTIVETo measure the magnitude of galvanic currents produced by different occluding metallic contact.

METHODSThe circuits of instantly different metallic contact were simulated in artificial saliva, and electrical potential of every couple and 15 currents of instant contact were then measured. After 8 hours' soaking, 15 currents were obtained in addition.

RESULTSGalvanic currents variation produced hy intermittently metallic contact was ruleless. During early soaking, gold/titanium, gold/high zinc-containing amalgam and low/high zinc-containing amalgam exhibited much higher current, and there was significant difference on currents between titanium/high zinc-containing amalgam and other couples (P < 0.05). There was also significant difference on currents between titanium/high zinc containing amalgam, titanium/low zinc-containing amalgam and gold/titanium, gold/low zinc-containing amalgam and gold/high zinc-containing amalgam after 8 hours' soaking (P < 0.05). In contrast with currents produced by couples before and after 8 hours' soaking, only the currents produced by gold/high zinc-containing amalgam proved to be no significant of difference (P > 0.05), while the currents produced by gold/low zinc-containing amalgam and titanium/high zinc-containing amalgam increased. Potential of high zinc-containing amalgam was more negative than other alloys, and it was always under anodic behavior during the experiment corrupted acceleratedly.

CONCLUSIONDentists can't ignore the case that the patient feels normal at the beginning of wearing different occluding metallic restorations. Either of gold/ titatium, gold/high zinc-containing amalgam and low/high zinc-containing amalgam appearing in oral will do harm to the patients' health. Neither of gold/low zinc-containing amalgam nor titanium/high zinc-containing amalgam can coexist in oral. Zinc-free or low zinc-containing amalgam should be selected instead of high zinc-containing amalgam.