Exploration of Metal Ion Release from Nickel-Chromium Denture Material: The Role of Saliva pH and Immersion Duration

Abstract

Nickel chromium (NiCr) is a fixed denture material. Nickel has good physical, and mechanical properties, cheap, but it has low corrosion resistance. One way to increase corrosion resistance is to modify the metal surface by silver plating using the electroplating method. This study examines the effect of saliva pH and immersion time of NiCr metal with silver plating on the release of nickel, chromium, and silver ions. Laboratory experimental studies were 27 samples of NiCr with silver plating (Ø= 10 x 10 x 2 mm) immersed in saliva and divided into 9 groups (n=3): group I (pH 5 for 5 days), group II (pH 7 for 5 days), group III (pH 9 for 5 days), group IV (pH 5 for 10 days), group V (pH 7 for 10 days), group VI (pH 9 for 10 days), group VII (pH 5 for 15 days), group VIII (pH 7 for 15 days), group IX (pH 9 for 15 days). Nickel, chromium, and silver ions release was measured using atomic absorption spectrophotometry. The data obtained were analyzed using two-way ANOVA and post hoc LSD with a 95% confidence level (α =0.05). The results showed a significant difference between salivary pH and immersion time on the ion release (p<0.05). The release of nickel and silver ions increases at acidic pH, while the release of chromium ions increases at alkaline pH. Prolonged immersion (for 15 days) in saliva increases the release of nickel and chromium ions but decreases the release of silver ions.