Effectiveness of dental bleaching in depth after using different bleaching agents.
OBJECTIVE
This study evaluated the effectiveness of low- and high-concentration bleaching agents on enamel and deep dentin.


METHODS
Stained bovine incisors fragments were randomized placed into 10 groups (n=5), according to the sample thicknesses (2.0 mm or 3.5 mm) and bleaching agent: 10% carbamide peroxide (CP) (4 h a day/21 days); 6% hydrogen peroxide (HP) with calcium (1:30 h a day/21 days); HP 20% with calcium (50 min a day/3 sessions with a 7-day interval); HP 35% (3 x 15 min a day/3 sessions with a 7-day interval); HP 35% with calcium (40 min a day/3 sessions with a 7-day interval). The samples were stored in artificial saliva during the experiment. The color change was evaluated using a spectrophotometer at the initial analysis, after artificially staining with black tea and after each of the bleaching weeks, and data was expressed in CIE Lab System values. The L* coordinate data was submitted to analysis of variance and Tukey-Kramer test and the ?E values data was submitted for analysis of variance in a split-plot ANOVA and Tukey's test (?=0.05).


RESULTS
None of the bleaching agents tested differed from the reflectance values on the enamel surface. For deep dentin HP 20% and HP 35%, both with calcium, showed the lowest reflectance values, which differed from CP 10%.


CONCLUSIONS
It is concluded that high concentration hydrogen peroxide with calcium was less effective in deep dentin than 10% carbamide peroxide. Key words:Dental bleaching; hydrogen peroxide; carbamide peroxide; dental staining.
DDS, MS, PhD Student. Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas-UNICAMP, Piracicaba, SP, Brazil.
Maria B F
MB
D'Arce
DDS, MS, PhD, Assistant Professor. Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas-UNICAMP, Piracicaba, SP, Brazil.
Débora A N L
DA
Lima
DDS, MS, PhD, Assistant Professor. Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas-UNICAMP, Piracicaba, SP, Brazil.
Flávio H B
FH
Aguiar
DDS, MS, PhD Student. Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas-UNICAMP, Piracicaba, SP, Brazil.
Carlos E S
CE
Bertoldo
PhD, Assistant Professor. Department of Social Dentistry/Statistics, Piracicaba Dental School, University of Campinas-UNICAMP, Piracicaba, SP, Brazil.
Gláucia M B
GM
Ambrosano
DDS, MS, PhD, Full Professor. Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas-UNICAMP, Piracicaba, SP, Brazil.
José R
JR
Lovadino