The Journal of Contemporary Dental Practice

Register      Login



Volume / Issue

Online First

Related articles

VOLUME 18 , ISSUE 11 ( November, 2017 ) > List of Articles


Effects of the Ratio between Pigment and Bleaching Gel on the Fracture Resistance and Dentin Microhardness of endodontically treated Teeth

Matheus Coelho Bandeca, Milton C Kuga, Keren CF Jordão-Basso, Mateus R Tonetto, Marina OG Galloza, Samuel O Costa, Fabio C Tirintan, Kátia C Keine

Citation Information : Bandeca MC, Kuga MC, Jordão-Basso KC, Tonetto MR, Galloza MO, Costa SO, Tirintan FC, Keine KC. Effects of the Ratio between Pigment and Bleaching Gel on the Fracture Resistance and Dentin Microhardness of endodontically treated Teeth. J Contemp Dent Pract 2017; 18 (11):1051-1055.

DOI: 10.5005/jp-journals-10024-2174

Published Online: 01-09-2016

Copyright Statement:  Copyright © 2017; The Author(s).



The aim of this study was to evaluate the effects of bleaching gel using 35% hydrogen peroxide (HP), associated with red carmine pigment (RC), in the 3:1 or 1:1 ratio, on fracture resistance and dentin microhardness of endodontically treated teeth.

Materials and methods

A total of 40 lower incisors were endodontically treated and divided into four groups (n = 10), according to the bleaching protocol: G1 (HP3), 35% HP + RC (3:1); G2 (HP1), 35% HP + RC (1:1); G3 (positive), 38% HP; and G4 (negative), unbleached. Four dental bleaching sessions were performed. The dental crowns were restored after the last session and submitted to the fracture resistance test. Totally, 60 specimens from the endodontically treated lower incisor crowns were prepared to evaluate the effects on dentin microhardness. The analysis was measured (in Knoop) prior to and after the last dental bleaching session using similar bleaching protocols.


G2 presented the lowest fracture resistance (p < 0.05). The other groups were similar to each other (p > 0.05). No difference was observed in the reduction of dentin microhardness among the groups (p > 0.05).


A 1:1 ratio (bleaching gel:pigment) caused a significant fracture resistance reduction in relation to the other protocols. No effect on the dentin microhardness reduction was observed.

Clinical significance

The pigment addition to the bleaching agent accelerates the bleaching chemical reaction. However, no studies have evaluated the ideal proportion to optimize tooth bleaching.

How to cite this article

Galloza MOG, Jordão-Basso KCF, Bandeca MC, Costa SO, Borges AH, Tonetto MR, Tirintan FC, Keine KC, Kuga MC. Effects of the Ratio between Pigment and Bleaching Gel on the Fracture Resistance and Dentin Microhardness of endodontically treated Teeth. J Contemp Dent Pract 2017;18(11):1051-1055.

PDF Share
  1. Review of the current status of tooth whitening with the walking bleach technique. Int Endod J 2003 May;36(5):313-329.
  2. Nonvital tooth bleaching: a review of the literature and clinical procedures. J Endod 2008 Apr;34(4):394-407.
  3. Fracture resistance of teeth submitted to several internal bleaching protocols. J Contemp Dent Pract 2014 Mar;15(2):186-189.
  4. Effects of alpha-tocopherol on fracture resistance after endodontic treatment, bleaching and restoration. Braz Oral Res 2016 May;30(1). pii: S1806-83242016000100258.
  5. Fracture strength of incisor crowns after intracoronal bleaching with sodium percarbonate. Dent Traumatol 2012 Jun;28(3):238-242.
  6. Can a bleaching toothpaste containing blue covarine demonstrate the same bleaching as conventional techniques? An in vitro, randomized and blinded study. J Appl Oral Sci 2015 Dec;23(6):609-613.
  7. Influence of the quantity of coloring agent in bleaching gels activated with LED/laser appliances on bleaching efficiency. Eur J Esthet Dent 2009 Summer;4(2):178-186.
  8. Effect of light energy on peroxide tooth bleaching. J Am Dent Assoc 2004 Feb;135(2):194-201.
  9. Effect of traditional and alternative intracoronal bleaching agents on microhardness of human dentine. J Oral Rehabil 2004 Aug;31(8):811-816.
  10. Influence of the number of bleaching sessions on fracture resistance and dentin microhardness of endodontically treated teeth. World J Dent 2017 Jan;8(1):5-9.
  11. Effect of final irrigation protocols on microhardness and erosion of root canal dentin. Microsc Res Tech 2013 Oct;76(10):1079-1083.
  12. Stability of hydrogen peroxide as a bleaching agent. Gen Dent 1985 Mar-Apr;33(2):121-122.
  13. Decomposition rate of hydrogen peroxide bleaching agents under various chemical and physical conditions. J Prosthet Dent 1993 Jan;69(1):46-48.
  14. Peroxide bleaching agent effects on enamel surface microhardness, roughness and morphology. Braz Oral Res 2004 Oct-Dec;18(4):306-311.
  15. Effects of the residues from the endodontic sealers on the longevity of esthetic restorations. J Contemp Dent Pract 2016 Aug;17(8):615-617.
  16. Fracture resistance of teeth subjected to internal bleaching and restored with different procedures. Braz Dent J 2011;22(2):117-121.
  17. Effect of different restorative procedures on the fracture resistance of teeth submitted to internal bleaching. Braz Oral Res 2012 Jan-Feb;26(2):77-82.
  18. Bleaching agents with varying concentrations of carbamide and/or hydrogen peroxides: effect on dental microhardness and roughness. J Esthet Restor Dent 2008;20(6):395-402.
  19. Microhardness of intracoronal dentin exposed to bleaching and fluoride treatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011 Nov;112(5):e1-e5.
  20. The microhardness of bleached dentine and its bond strength to a dentine bonding agent. Eur J Prosthodont Restor Dent 2007 Sep;15(3):131-134.
  21. The effect of 24h non-stop hydrogen peroxide concentration on bovine enamel and dentine mineral content and microhardness. J Dent 2007 Nov;35(11):845-850.
  22. Influence of the coloring agent concentration on bleaching gel and pulp chamber temperatures during dental bleaching. Gen Dent 2010 Jan-Feb;58(1):e36-e41.
  23. Depth of penetration of four resin sealers into radicular dentinal tubules: a confocal microscopic study. J Endod 2012 Oct;38(10):1412-1416.
  24. Evaluation of the physicochemical properties and push-out bond strength of MTA-based root canal cement. J Contemp Dent Pract 2013 Nov;14(5):1094-1099.
  25. The effect of final irrigation on the penetrability of an epoxy resin-based sealer into dentinal tubules: a confocal microscopy study. Clin Oral Investig 2016 Jan;20(1):117-123.
PDF Share
PDF Share

© Jaypee Brothers Medical Publishers (P) LTD.