title: In vitro enamel demineralization and the marginal gap of simulated cast restorations with three different cements.
abstract: OBJECTIVE
  This study investigated 1) the relationship between marginal gap sizes and enamel demineralization, and 2) the influence of three cements on this enamel demineralization.
  
  
  METHODS
  Horizontal sections of 60 noncarious, freshly extracted human third molars were randomly assigned to one of four groups. Simulated cast restorations were attached to the specimens with 1) zinc phosphate cement, 2) glass ionomer cement, 3) composite resin cement, or 4) no cement (control). The tooth/restoration gaps were controlled at 51, 102, and 204 microns. The specimens were incubated for 16 weeks in buffered lactic acid gelatin to induce demineralization. Photomicrographs were obtained from sections of each sample using a polarized light microscope. Three evaluators measured wall and primary enamel lesion depths allowing for the determination of a demineralization ratio (DR). Data were analyzed by repeated-measures ANOVA (alpha = 0.05).
  
  
  RESULTS
  The between-evaluator effects were not significant. All evaluators agreed that DR was significantly related to cement (p = .0001) but not to marginal gap size. The resin cement had the smallest DR (0.7 +/- 0.3), and the control group had the greatest (4.4 +/- 2.0).
  
  
  CONCLUSIONS
  The presence of any one of the three investigated cements resulted in decreased demineralization. The amount of demineralization was unaffected by marginal gap size.
authors.affiliation: Division of Prosthodontics, University of California, School of Dentistry, San Francisco 94143-0758, USA.
authors.forename: Y H
authors.initials: YH
authors.lastname: Wu
authors.forename: J E
authors.initials: JE
authors.lastname: Hutton
authors.forename: G W
authors.initials: GW
authors.lastname: Marshall
mesh_terms: D000704:Analysis of Variance; D003738:Dental Cements / Q000494:pharmacology*; D003743:Dental Enamel / Q000187:drug effects*; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent; D005720:Gamma Rays; D005899:Glass Ionomer Cements / Q000627:therapeutic use; D006801:Humans; D066298:In Vitro Techniques; D015588:Observer Variation; D011897:Random Allocation; D019279:Resin Cements / Q000627:therapeutic use; D017001:Tooth Demineralization / Q000517:prevention & control*; D015036:Zinc Phosphate Cement / Q000627:therapeutic use
chemical_list: D003738:Dental Cements; D005899:Glass Ionomer Cements; D019279:Resin Cements; D015036:Zinc Phosphate Cement