Surface discoloration of restorative resins in relation to surface softening and oral hygiene.

Restorative resins are susceptible to softening caused by organic acids produced in plaque. Consequently, plaque-covered resin restorations may be liable to pronounced surface staining. In the clinical part of the study a relationship between surface staining and local oral hygiene was demonstrated. This may be explained by the results from the laboratory part of the study, in which a relationship between surface staining and softening was found.