Effective tooth-bleaching protocols capable of reducing H(2)O(2) diffusion through enamel and dentine.
OBJECTIVE
To evaluate the effects of experimental protocols on bleaching effectiveness and hydrogen peroxide (HP) diffusion through enamel and dentine.


METHODS
Enamel/dentine discs were subjected to six bleaching sessions, consisting of 1 or 3 applications of 17.5% or 35%-HP gel for 5/15min, or 37% carbamide peroxide (CP) gel for 10/20min. Discs undergoing the regular protocol (35%-HP; 3×15min) constituted the positive control group. Colour change (ΔE) was assessed (CIE L*a*b* system) after each session. HP diffusion was quantified (sessions 1, 3, and 6) in enamel/dentine discs adapted to artificial pulp chambers. Data were analysed by Pillai's Trace and Bonferroni test, or by one-way ANOVA and SNK/Tamhane's test (α=5%).


RESULTS
All tooth-bleaching protocols significantly increased the ΔE values. A reduction in HP diffusion and no significant difference in ΔE compared with the positive control were observed for the following bleaching protocols: 17.5%-HP 3×15min, at the 4th session; and 35%-HP 1×15 and 3×5min, at the 5th session. HP diffusion in the 37%-CP 3×20min bleaching protocol was statistically similar to that in the positive control. The other experimental bleaching protocols significantly decreased HP diffusion through enamel/dentine discs, but the ΔE values were statistically lower than those observed in the positive control, in all sessions.


CONCLUSIONS
Shortening the contact time of a 35%-HP gel or reducing its concentration produces gradual tooth colour change and reduced HP diffusion through enamel and dentine.


CONCLUSIONS
A reduction in HP concentration, from 35% to 17.5%, in a bleaching gel or shortening its application time on enamel provides a significant tooth-bleaching improvement associated with decreased HP diffusion across hard dental tissues. Therefore, these protocols may be an interesting alternative to be tested in the clinical situation.
Department of Dental Materials and Prosthodontics, Araraquara School of Dentistry, Univ Estadual Paulista, Araraquara, SP, Brazil.
Diana G
DG
Soares
Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas - UNICAMP, Piracicaba, SP, Brazil.
Fernanda G
FG
Basso
Department of Dental Materials and Prosthodontics, Araraquara School of Dentistry, Univ Estadual Paulista, Araraquara, SP, Brazil.
Elaine C V
EC
Pontes
Department of Physiology and Pathology, Araraquara School of Dentistry, Univ Estadual Paulista, Araraquara, SP, Brazil.
Lucas da F R
Lda F
Garcia
Department of Orthodontics and Pediatric Dentistry, Araraquara School of Dentistry, Univ Estadual Paulista, Araraquara, SP, Brazil.
Josimeri
J
Hebling
Department of Physiology and Pathology, Araraquara School of Dentistry, Univ Estadual Paulista, Araraquara, SP, Brazil. Electronic address: casouzac@foar.unesp.br.
Carlos A
CA
de Souza Costa
D000818:Animals; D000077463:Carbamide Peroxide; D002417:Cattle; D003116:Color; D003743:Dental Enamel / Q000187:drug effects / Q000378:metabolism*; D003786:Dental Pulp Cavity / Q000378:metabolism; D003804:Dentin / Q000187:drug effects / Q000378:metabolism*; D004058:Diffusion; D005782:Gels; D006861:Hydrogen Peroxide / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008422:Materials Testing; D010545:Peroxides / Q000008:administration & dosage / Q000493:pharmacokinetics; D013053:Spectrophotometry / Q000379:methods; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*; D058205:Tooth Bleaching Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D014075:Tooth Discoloration / Q000188:drug therapy / Q000378:metabolism; D014508:Urea / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000493:pharmacokinetics
D005782:Gels; D010545:Peroxides; D058205:Tooth Bleaching Agents; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide
Dentine; Enamel; Hydrogen peroxide; Tooth bleaching