The aim of this in vitro study was to assess quantitatively dentin permeability of
pulpless teeth after intracoronal bleaching
therapy with three different agents. Twenty-four maxillary central incisors were randomly assigned to four groups according to the
bleaching agent used: I--non-bleached control; II--37%
carbamide peroxide; III--
sodium perborate/20%
hydrogen peroxide paste; IV--27%
carbamide peroxide. After standard access and
root-canal preparation the access opening, biomechanical preparation and root-canal filling, a cervical
glass ionomer plug was prepared and intracoronal bleaching procedures were carried out in a standardized fashion. The access cavities were opened and the teeth were externally sealed and immersed in
a 10%
copper sulfate aqueous
solution for 30 min, in vacuum for the first 5 min. Then, samples were removed, dried with absorbing paper and immersed in a 1% rubianic
acid alcohol
solution, for the same above-mentioned period in
solution and in vacuum.
Copper ion penetration was indicated by the rubianic
acid staining. Mean values and SD for the experimental groups were: I--7.88% (+/-1.33), II--16.94% (+/-5.72); III--11.45% (+/-3.90) and IV--8.98% (+/-4.19). Data were submitted to one-way anova. The results showed that the 37%
carbamide peroxide provided the highest increase in dentin permeability, followed by
sodium perborate with 20%
hydrogen peroxide. The 27%
carbamide peroxide provided the lowest results and showed statistical similarity to the control group. On basis of these findings, it may be concluded that, among the tested intracoronal
bleaching agents, 37%
carbamide peroxide presented an optimized overall performance in increasing dentinal permeability.