title: Can chemical softening agents minimize cavity enlargement during removal of failed anterior resin composite restorations?
abstract: This in-vitro investigation sought to identify the most effective softening agents for three commercial anterior resin composites (Prisma APH, Brilliant and Blend-a-Lux) from four potential agents (75% ethanol, polyacrylic acid, acetone and acetic acid), selected as having close solubility parameter values to BIS-GMA. The Vickers microhardness test was applied to samples before and following a 180 s application of each agent. In addition, the degree of cavity enlargement following removal of resin composite restorations, aged by thermocycling, was assessed by image analysis. Using the same method the influence of both colour match and the 180 s application of softening agents, in the optimum chemical/material combinations, upon this was determined. Analyses of variance revealed that significant (P < 0-01) reductions in surface microhardness occurred when 75% ethanol was applied to Prisma-APH and acetic acid to Blend-a-Lux. Removal of restorations of all materials resulted in highly significant (P < 0.001) increases in cavity size. Application of either 75% ethanol to Prisma-APH restorations or acetic acid to Blend-a-Lux did not alter this result. Thermocycling only produced a significant (P < 0.01) (McNemar Test) deterioration in shade match of the Prisma APH restorations but analyses of variance, for all materials, revealed that the observed changes in colour match had no significant (P < 0.05) effect upon the degree of cavity size enlargement. It is concluded that the application of softening agents to reduce cavity enlargement is not a viable clinical option.
authors.affiliation: Department of Conservative Dentistry, The Dental School, University of Dundee, Scotland, UK.
authors.forename: E J
authors.initials: EJ
authors.lastname: Cruickshank
authors.forename: R G
authors.initials: RG
authors.lastname: Chadwick
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D000096:Acetone / Q000737:chemistry; D000180:Acrylic Resins / Q000737:chemistry; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003116:Color; D003188:Composite Resins / Q000737:chemistry*; D003737:Dental Cavity Preparation; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent; D000431:Ethanol / Q000737:chemistry; D005899:Glass Ionomer Cements / Q000737:chemistry; D006244:Hardness; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008422:Materials Testing; D019279:Resin Cements / Q000737:chemistry; D012995:Solubility; D012997:Solvents / Q000737:chemistry*; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D000180:Acrylic Resins; C075707:Brilliant Enamel; D003188:Composite Resins; D005899:Glass Ionomer Cements; D019279:Resin Cements; D012997:Solvents; C098567:blend-a-lux; C073466:Prisma APH; D000096:Acetone; D000431:Ethanol; D017438:Bisphenol A-Glycidyl Methacrylate; C006903:carbopol 940; D019342:Acetic Acid