CELLULAR-RESPONSE TO METALLIC-IONS RELEASED FROM NICKEL-CHROMIUM DENTAL ALLOYS

Concerns exist over the potential release of elevated levels of metal ions such as Ni and Be from Ni-Cr dental casting alloys, due to their susceptibility to accelerated corrosion. In this investigation, we eva luated the release of metal ions from four commercial Ni-Cr alloys, re presenting a range of compositions, in three-day cell culture tests. M etal ion release, as measured by atomic absorption spectroscopy, was c orrelated to changes in cellular morphology, viability, and proliferat ion. The results showed that the test alloys and their corrosion produ cts did not affect cellular morphology or viabilities, but did decreas e cellular proliferation. The types and amounts of metal ions released , which corresponded to the alloys' reported surface and corrosion pro perties, also correlated to observed decreases in cellular proliferati on after 72 h. Neptune, which caused the smallest decrease in cellular proliferation as compared with control cells, released the lowest amo unt of corrosion products, due to its corrosion-resistant, high-Cr-Mo- containing, homogeneous surface oxide. The other test alloys, which we re susceptible to accelerated corrosion processes, released higher lev els of metal ions that correlated to larger decreases in thymidine inc orporation. Metal ion levels increased with test time for all alloys b ut were not proportional to bulk alloy compositions. Ni ions were rele ased at slightly higher than bulk alloy compositions, while Be was rel eased at from four to six times that of bulk alloy compositions. The e levated release of Be ions was associated with reduced cellular prolif eration. Other alloying elements were released at levels similar to or lower than bulk levels. Further research is needed to evaluate possib le synergistic effects of released metal ions, especially Ni and Be io ns, on cellular activities and functions.