Iron discoloration of acrylic resin exposed to chlorhexidine or tannic acid: a model study

A clinical model was introduced to study the ability of chlorhexidine, tannic acid, and iron to discolor dental plaque formed on acrylic resin surfaces. None of the agents caused discoloration when applied individually five times daily during a 5-day period. However, exposure of the dental plaque to either chlorhexidine or tannic acid before the iron applications produced marked staining. Possible mechanisms, among which denaturation appears to be significant, are discussed. The use of a strong oxidizing agent, peroxymonosulfate, completely bleached the established discolorations.