Damage of dental amalgam and resin-matrix composite surfaces after exposure to bleaching agents: an integrative review

The aim of this study was to perform an integrative systematic review on the damage of dental resin-matrix composite and amalgam surfaces after exposure to bleaching agents composed of hydrogen or urea (carbamide) peroxide. An electronic search on PubMed was carried out using the following selected terms: amalgam” OR “resin composite” AND “bleaching treatment” AND “corrosion” OR “erosion”, “roughness” OR “AFM” OR “profilometry” OR “SEM”. The search identified 127 articles, of which 32 were considered relevant to this study. The results revealed a significant increase in roughness values of the dental amalgam within a micro-scale damage after contact with the bleaching agents. The roughness of the resin–matrix composites was altered at a lower extent that was dependent on their organic matrix content and time of exposure to the bleaching agents. As a consequence of the morphological changes, a release of Hg, Ag, and Cu ions was measured after contact of the amalgam with bleaching agents that can promote localized and systemic toxicity. The degradation products of the organic matrix of the resin-matrix composites consisted in methacrylate monomers which can also be toxic to the surrounding cells and tissues. The findings showed evidences of the degradation of dental amalgam and resin–matrix composite surfaces after contact with bleaching agents. Degradation was severe for amalgam and the consequent release of ions can induce localized and systemic adverse biological response to the patients.