Efficacy of intracoronal bleaching techniques with different light activation sources L. D. Carrasco 1 , D. M. Z. Guerisoli 2 , M. J. A. Rocha 1 , J. D. Pe ´ cora 1 & I. C. Fro ¨ ner 1 1 Ribeira ˜o Preto Dental School, University of Sa ˜o Paulo, Ribeira ˜o Preto, SP; and 2 Faculty of Dentistry, Federal University of Mato Grosso do Sul, Campo Grande, MS, Brazil Abstract Carrasco LD, Guerisoli DMZ, Rocha MJA, Pe ´ cora JD, Fro ¨ ner IC. Efficacy of intracoronal bleaching techniques with different light activation sources. International Endodontic Journal, 40, 204–208, 2007. Aim To evaluate ex vivo the efficacy of 35% hydrogen peroxide for intracoronal bleaching when activated by LEDs, halogen lamp or by the walking bleach tech- nique. Methodology Forty extracted human maxillary central incisors had their crowns resected 1 mm below the amelo-cemental junction and were submit- ted to artificial staining in centrifuged rat haemolysed blood. A 2-mm thick glass ionomer cervical plug was placed inside the canal, at the level of the amelo- cemental junction. Samples were divided randomly into five groups: group I received 35% hydrogen peroxide gel activated by LEDs. Group II received 35% hydrogen peroxide gel activated by a halogen lamp- based light curing unit. Group III received 35% hydrogen peroxide gel followed by the walking bleach technique. Group IV was neither artificially stained nor bleached (positive control) and group V was stained, but not bleached (negative control). The shade of the teeth was assessed visually by three independent and calibrated evaluators, before and after bleaching. The results were analysed using Kruskal–Wallis one-way analysis of variance and Dunn’s post-test. Results No statistical differences regarding sample shades were found amongst groups for the tested internal bleaching techniques (P > 0.05). Conclusions Hydrogen peroxide for intracoronal bleaching when activated either by LEDs, halogen lamp or by the walking bleach technique presented similar efficacy. Keywords: halogen lamp, hydrogen peroxide, inter- nal dental bleaching, LED, light activation. Received 20 March 2006; accepted 18 September 2006 Introduction Tooth discolouration is an aesthetic problem that may require treatment based on bleaching (Kaneko et al. 2000). Internal dental bleaching is an established, simple, conservative and cost-effective method of improving the colour of discoloured teeth that have received root canal treatment (Lee et al. 2004, Lim et al. 2004). Many techniques have been used for dental bleach- ing, especially for root-filled teeth. The majority rely on an oxidation reaction in order to reverse the chromatic alteration of the dental tissues (Smigel 1996, Sulieman 2004). Heat sources have been used to accelerate the bleaching process of concentrated hydrogen peroxide. However, activation of the bleaching agent by such means has been questioned, because of its possible deleterious effects on tooth and surrounding tissues (Trope 1997). More recently, the techniques and materials used for dental bleaching rely on methods which are less harmful to the tooth, surrounding tissues and oral mucosa, but still remaining efficient in promoting the desired colour change. The use of Correspondence: Dr Izabel Cristina Fro ¨ner, Professor, Departa- mento de Odontologia Restauradora, Faculdade de Odontolo- gia de Ribeira ˜o Preto, Universidade de Sa ˜o Paulo, 14040-904, Ribeira ˜o Preto, SP, Brazil (Tel.: +55 1 6602 4055; fax: +55 1 6633 0999; e-mail: froner@forp.usp.br). International Endodontic Journal, 40, 204–208, 2007 ª 2007 International Endodontic Journal doi:10.1111/j.1365-2591.2007.01216.x 204