Staining of dentin from amalgam corrosion is induced by demineralization

Abstract

Purpose: To evaluate the effect of artificial demineralization upon color change of dentin in contact with dental amalgam. Methods: Sound human molars (n= 34) were embedded in resin and coronal enamel was removed. Dentin was exposed to artificial caries gel (pH 5.5) at 37ºC for 12 weeks (n= 24). Non-demineralized teeth served as controls (n= the 10). A dispersive high-Cu amalgam or conventional low-Cu amalgam was condensed onto dentin surfaces of all groups. After 10 weeks storage in saline, amalgam was removed and teeth were cut into three slices. Surfaces were inspected under optical microscopy and photographed. Results: Penetration of black pigments was observed in dentin underneath both high-Cu and low-Cu amalgams in demineralized specimens. Black deposits were unevenly distributed and observed predominantly in dentin near to pulp horns. Discoloration was not limited to outer demineralized dentin but extended beyond this zone. Evenly distributed bluish-green discoloration was observed underneath all high-Cu amalgam specimens independent of demineralization.

Clinical significance: Deposition of black corrosion products into dentin was strongly related to dentin demineralization. An evenly distributed bluish-green discoloration from high-Cu amalgam was not related to demineralization. However, as black discoloration extended beyond the demineralized zone, it cannot serve as an indicator for demineralized dentin.