Cellular Response to Metallic Ions Released from Nickel-Chromium Dental Alloys

Abstract

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 evaluated the release of metal ions from four commercial Ni-Cr alloys, representing a range of compositions, in three-day cell culture tests. Metal ion release, as measured by atomic absorption spectroscopy, was correlated to changes in cellular morphology, viability, and proliferation. The results showed that the test alloys and their corrosion products did not affect cellular morphology or viabilities, but did decrease cellular proliferation. The types and amounts of metal ions released, which corresponded to the alloys' reported surface and corrosion properties, also correlated to observed decreases in cellular proliferation after 72 h. Neptune, which caused the smallest decrease in cellular proliferation as compared with control cells, released the lowest amount of corrosion products, due to its corrosion-resistant, high-Cr-Mo-containing, homogeneous surface oxide. The other test alloys, which were susceptible to accelerated corrosion processes, released higher levels of metal ions that correlated to larger decreases in thymidine incorporation. Metal ion levels increased with test time for all alloys but were not proportional to bulk alloy compositions. Ni ions were released at slightly higher than bulk alloy compositions, while Be was released at from four to six times that of bulk alloy compositions. The elevated release of Be ions was associated with reduced cellular proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)

Ion release from metal-ceramic alloys in three different media

“…Elements such as beryllium (Be), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), palladium (Pd), and vanadium (V) are known to be toxic, allergic, or mutagenic, and they should be used in lower ratios in dental alloys 6) . Several studies have measured the release of metallic ions from dental alloys of different alloy compositions 1,[4][5][6][8][9][10] . For many Ni-based dental casting alloys, Ni was the main element released while other major elements (Cr and molybdenum (Mo)), which are considered less toxic, were released at much lower concentrations 8) .…”

The connective tissue response to Ti, NiCr and AgPd alloys.

“…The nickel ion release that inhibits the synthesis of DNA, RNA, proteins, ATP and glucose-6-phosphate, was observed in surrounding tissues after 24-72 hours from NiCr alloy implantation [23]. The necrosis features were not found around NiCr implants and there were no inflammatory infiltrations in guinea pigs in literature [24]. The introduction of the pure, powdered nickel into the gum of a rat caused necrosis and lymphocyte infiltration in the nickel grain areas [25].…”

In Vitro Cytotoxicity Test and Surface Characterization of CoCrW Alloy in Artificial Saliva Solution for Dental Applications

“…Factors like quantity and quality of saliva, salivary pH, dental plaque, amount of protein, chemical and physical properties of food and fluid intake, and general oral health conditions may influence the metal corrosion in the oral cavity (3). There are two concerns about dental materials in oral environment: the localized effects or systemic damage caused by the release of corrosion products to the body and the effects on the physical properties and clinical performance of the alloy (4-7).…”