Effects of a 10% carbamide peroxide bleaching agent on roughness and microhardness of packable composite resins.
OBJECTIVE
Bleaching agents containing 10% carbamide peroxide may be applied to the surface of preexisting packable resin-based composite restorations. The aim of this in vitro study was to evaluate the effect of a 10% carbamide peroxide bleaching agent (Review, SS White, Rio de Janeiro, Brazil) on surface roughness and microhardness of three packable resin-based composites (Fill Magic condensable, Vigodent, Rio de Janeiro, Brazil; Alert, Jeneric Pentron, Wallingford, CT, USA; Definite, Degussa, Hanau, Germany).


METHODS
For the control (no bleaching) and experimental (bleaching treatment) groups, 12 specimens of each material were prepared in cylindrical acrylic molds. The experimental specimens were exposed to the bleaching agent for 6 hours a day for 3 weeks. During the remaining time (18 h), they were stored in artificial saliva. The control specimens remained immersed in artificial saliva throughout the experiment. Surface roughness and microhardness measurements were performed on the top surface of each specimen.


RESULTS
Analysis of variance and the Tukey test showed no significant differences in roughness among the packable composites evaluated (p = .18), but those submitted to the treatment with a 10% carbamide peroxide bleaching agent displayed significantly higher mean surface roughness than did the corresponding control group for each material. For the microhardness tests, there were significant differences among materials (p < .0001). Alert showed the highest microhardness values followed by Definite and Fill Magic condensable.


CONCLUSIONS
Ten percent carbamide peroxide bleaching agents may change the surface roughness of packable composites, but they do not alter their microhardness.


CONCLUSIONS
Under the conditions of this study, a 3-week bleaching regimen with 10% carbamide peroxide agents affected the roughness of packable composites. Nevertheless, the surface microhardness was not affected, although there were differences among the materials evaluated inherent to their composition.
Basting
Roberta Tarkany
RT
Dentistry Research Center, São Leopoldo Mandic, Campinas, SP, Brazil. rbasting@yahoo.com
Fernandéz Y Fernandez
Camila
C
Ambrosano
Glaucia Maria Bovi
GM
de Campos
Inger Teixeira
IT
D000077463:Carbamide Peroxide; D003188:Composite Resins / Q000737:chemistry; D004338:Drug Combinations; D006244:Hardness; D016877:Oxidants; D010545:Peroxides; D012833:Siloxanes / Q000737:chemistry; D013499:Surface Properties; D013729:Terpenes / Q000737:chemistry; D014073:Tooth Bleaching; D014508:Urea / Q000031:analogs & derivatives*
C406265:Alert composite resin; D003188:Composite Resins; C421785:Definite composite resin; D004338:Drug Combinations; C481898:Fill Magic; D016877:Oxidants; D010545:Peroxides; C506184:Review (bleaching agent); D012833:Siloxanes; D013729:Terpenes; D000077463:Carbamide Peroxide; D014508:Urea