Effect of vital tooth bleaching on solubility and roughness of dental cements.
BACKGROUND
Vital tooth bleaching may affect properties of dental cements used for fixed prostheses.


OBJECTIVE
The purpose of this study was to examine the effect of a combined in-office and at-home bleaching regimen on changes in surface roughness and depth loss of a variety of commercially available dental cements.


METHODS
Five cement classifications were tested: glass ionomer, resin-modified glass ionomer, resin,self-adhesive resin cement, and zinc phosphate. Cements were placed in multiple wells in plastic blocks. After setting,the surface profile of each block was determined, and average roughness and vertical height of cement surface from the specimen holder were recorded. Blocks were water stored (control) or subjected to in-office and at-home bleaching(n=12). Surfaces were rescanned and pre- and posttest parameter changes were calculated. Statistical analysis consisted of Mann-Whitney-Wilcoxon Rank Sum and Student t tests applied to control and bleaching parameterc hanges within the same cements. A family-wise alpha of .05 was maintained by using a Bonferroni-adjusted level of significance preset to .01 per test.


RESULTS
Zinc phosphate showed the only significant depth increase (P=.004) from bleaching: 0.9 +/- 0.7 microm deeper than the water-control group. Only resin-modified glass ionomer showed a significant (P=.004) increase in roughness from bleaching; values increased by 0.05 +/- 0.03 microm over the water-control group.


CONCLUSIONS
In-office and at-home bleaching significantly increased depth loss of zinc phosphate and increased resinmodified glass ionomer roughness. However, the absolute values of differences observed, as compared to the wateronly control, were considered to be clinically insignificant. (J Prosthet Dent 2009;102:148-154)
Londono
Jimmy
J
Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia and School of Graduate Studies, Medical College of Georgia, Augusta, Ga, USA.
Abreu
Amara
A
Nelson
Steve
S
Hernandez
Jorge
J
Torres
Carlos
C
Mettenburg
Donald
D
Looney
Stephen
S
Rueggeberg
Frederick
F
D000077463:Carbamide Peroxide; D003738:Dental Cements / Q000737:chemistry*; D003763:Dental Leakage / Q000139:chemically induced; D018772:Dental Marginal Adaptation; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent; D004338:Drug Combinations; D006801:Humans; D016877:Oxidants / Q000009:adverse effects / Q000737:chemistry*; D010545:Peroxides / Q000009:adverse effects / Q000737:chemistry*; D018709:Statistics, Nonparametric; D013499:Surface Properties; D014073:Tooth Bleaching / Q000379:methods*; D014508:Urea / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000737:chemistry
D003738:Dental Cements; D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D000077463:Carbamide Peroxide; D014508:Urea