Resumo

SAMPAIO, Maíra Dias; FREITAS, Anderson Pinheiro de  e  ARAUJO, Roberto Paulo Correia de. Spectrophotometric analysis of internal dental bleaching effect. RGO, Rev. gaúch. odontol. (Online) [online]. 2010, vol.58, n.3, pp. 363-368. ISSN 1981-8637.

OBJECTIVE: The objective of this study was to compare the efficacy of 37% carbamide peroxide and the association between sodium perborate and 35% oxygen peroxide on the internal bleaching of bovine teeth treated endodontically, darkened or not in vitro. METHODS: Eighty bovine incisors were sectioned 3mm below the cement-enamel junction and divided into eight groups. Four groups were experimentally stained with blood for 14 days. After this period, an endodontic treatment was done in all the specimens followed by internal bleaching using the walking bleach technique for three consecutive weeks. Assessment of the bleaching efficacy of the agents used in the middle third of the tooth was determined by comparing the response of the L*, a* and b* factors of the studied groups obtained with a Easyshade-Vita spectrophotometer based on the CIE Lab system. RESULTS: There was statistical difference in luminosity (L*) between group GC2 and the other groups (Figure 2). The same result was found for the comparisons between GC1 and the groups GC2, GT1a, GT1b, GT2a, GT2b and GT2c. L* did not differ statistically when the groups GT1a, GT1b and GT1c were compared (p>0.05). However, GT2c presented a significant statistical difference when compared with the groups GT2a and GT2b (p<0.05) even though the L5 reading did not detect the difference between GT2a and GT2c. CONCLUSION: For the middle third of the unstained teeth, the three bleaching agents presented the same bleaching effect. For darkened teeth, sodium perborate in different vehicles was more effective than 37% carbamide peroxide, especially regarding the residual effect of the bleaching agents. However, when the pastes containing sodium perborate were compared, they presented the same bleaching behavior even when the pulp chamber was stained by blood.

Palavras-chave : tooth bleaching; peroxides; tooth nonvital; pigments biological.