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Year : 2015  |  Volume : 5  |  Issue : 1  |  Page : 33-37

A comparative evaluation of efficacy of commercially available bleaching agents in non-vital teeth: An in vitro study

Department of Conservative Dentistry and Endodontics, Sudha Rustagi College of Dental Sciences and Research, Faridabad, Haryana, India

Date of Web Publication12-Jan-2015

Correspondence Address:
Ashima Garg Sood
L 12, Kailash Colony, New Delhi
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1658-5984.149084

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Aim : The aim of the study was to evaluate and compare the efficacy of commercially available three bleaching agents when used internally or by internal-external method in non-vital teeth. Materials and Methods: Seventy extracted single-rooted premolars were artificially stained with whole blood in centrifugal machine. Teeth were divided into six experimental groups (Group I-VI) and one control group (Group VII). Bleaching was carried out in all the experimental groups using either of three commercially available bleaching agents: In Group I and group IV, 35% carbamide peroxide was used. In group II and V, 21% carbamide peroxide was used. Teeth in Group III and VI were bleached using 35% hydrogen peroxide (H 2 O 2 ). In the first three experimental groups (Group I, II, III), internal bleaching was done and in other three groups (Group IV, V, VI), both internal and external application was done. The evaluation was done at 0, 7, and 14 days using VITA shade guide. Statistical Analysis: The results obtained were statistically analyzed using ANOVA, Paired t-test, and ANOVA with post hoc Tukey's modification to evaluate the significant change and efficacy of the groups tested. Results: All bleaching agents showed effective shade reduction. The effects of 35% H 2 O 2 and 35% carbamide peroxide were statistically similar. The least reduction was seen with 21% carbamide peroxide groups. There was no difference between internal bleaching and internal-external methods. Conclusions: Within the limitation of the study, it could be concluded that 35% carbamide peroxide is an effective intracoronal bleaching agent similar to that of 35% H 2 O 2 .

Keywords: Carbamide peroxide, hydrogen peroxide, intracoronal bleaching

How to cite this article:
Mittal R, Sood AG, Singla MG, Dhawan D. A comparative evaluation of efficacy of commercially available bleaching agents in non-vital teeth: An in vitro study. Saudi Endod J 2015;5:33-7

How to cite this URL:
Mittal R, Sood AG, Singla MG, Dhawan D. A comparative evaluation of efficacy of commercially available bleaching agents in non-vital teeth: An in vitro study. Saudi Endod J [serial online] 2015 [cited 2021 Dec 7];5:33-7. Available from: https://www.saudiendodj.com/text.asp?2015/5/1/33/149084

  Introduction Top

Pulpless teeth often show crown discoloration due to by-products from pulpal hemorrhage after trauma or incomplete removal of pulp tissue during endodontic therapy. [1],[2] Blood vessels rupture with diffusion of blood and breakdown of erythrocytes into the dentinal tubules causing discoloration. [3] Intracoronal bleaching is considered to be a conservative, economic, and effective method for the treatment of these non-vital discolored teeth. [4],[5] The efficacy of bleaching depends on the type of stain and its etiology. [6] It also depends upon type of the bleaching agent, its concentration and the duration of application. [6] Bleaching agents that can be used are sodium perborate, hydrogen peroxide (H 2 O 2 ) (30%, 35%), carbamide peroxide (CP) (10%, 20%, 35%). [7],[8],[9],[10] H 2 O 2 is a strong oxidizer that can penetrate dentine and release oxygen that breaks the double bond of organic and inorganic compounds inside the dentinal tubules causing decolorization of stains .[7] Its use has been associated with few undesirable consequences such as external cervical root resorption .[11] This has been attributed to excessive peroxide diffusing into the periradicular tissues, possibly through cemental defects. [12] Sodium perborate is one of the commonly used intracoronal bleaching agents, which can be used alone with distilled water or in combination with H 2 O 2 . [7],[13] Though its use with distilled water produces no side effects, it may take longer time to produce appreciable color change. [13] CP in different concentrations has been used extensively in bleaching. [5],[8],[13],[14],[15] Studies have shown significant color change with intracoronal use of CP. [9],[10],[13],[14] It carries less risk of post-bleaching external root resorption than HP-SP bleaching agents because of lower level of peroxide penetration to the external surface. [14]

Since there are various formulations of bleaching agents available commercially in different concentrations, it would be desirable to find out an agent with a lower peroxide concentration causing least complications and providing acceptable aesthetic outcome. Therefore, the aim of the present study was to evaluate and compare the efficacy of various bleaching agents when used internally or by internal-external method in non-vital teeth.

  Materials and Methods Top

Seventy single-rooted premolars extracted for orthodontic reasons were selected. A gauze soaked with a solution of 2.25% sodium hypochlorite was used to remove any soft tissue covering the root surface. Any debris and calculus was removed using ultrasonic scaler. The teeth were stored in distilled water. Standard access cavities were prepared using no. 2 round carbide bur in a high speed handpiece, and the cervical thirds of the canals were widened with Gates-Glidden drill no. 2. Roots were resected between the coronal and middle thirds (1 mm apical to the cementoenamel junction) using carborundum disk mounted on a straight handpiece. The crowns were immersed in 17% Ethylene Diamine Tetraacetic Acid (EDTA) for 5 minutes to remove smear layer. The teeth were washed with distilled water.

Staining of teeth was done using Freccia and Peters [16] method in which the teeth were immersed in whole human blood without the serum and centrifuged [R-8C BL Centrifuge machine REMI, (India)] at 3200 rpm for 20 minutes twice daily over three days to enhance penetration of the hemolysed red blood cells into the dentinal tubules. The precipitate was removed, and the teeth were immersed in the remaining hemoglobin-rich hemolysate for a further 3 days. Centrifuging was carried out twice daily as previously described. The resultant discolored teeth were washed in distilled water.

Cervical plugs of glass ionomer cement (Glass Ionomer Cement universal Restorative. SHOFU INC, Japan) of 2-mm thickness was placed extending 1 mm below the cementoenamel junction to obtain the apical seal. Baseline color for the teeth was evaluated using a VITA Classical shade guide (VITA Zahnfabrik, Germany) before they were bleached. The shade guide was arranged by value order from lightest to darkest as determined by the manufacturer and a score was assigned [Table 1]. [10],[12]
Table 1: The VITA Classic shade guide arranged in order of value and the assigned score

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Teeth were divided randomly into six experimental groups and one control group. Further, all experimental specimens were sub-grouped into A and B. Teeth in Subgroup A were subjected to only internal bleaching and in teeth in subgroup B both internal and external bleaching was performed. Three different bleaching agents used were 35% CP (Ultrawhite professional tooth whitening system, Ammdent, India), 21% CP (Perfecta take home tooth whitening system, Premier U.S.A), and 35% H 2 O 2 (Pola office SDI Australia.) The tested bleaching agents were applied on the subgroups as follows:

Subgroup A

Group I : 35% CP-Internal Bleaching

Group II : 21% CP-Internal Bleaching

Group III :

35% H 2 O 2 -Internal Bleaching.

Subgroup B

Group IV :

35% CP - Internal and External Bleaching

Group V :

21% CP - Internal and External Bleaching

Group VI :

35% H 2 O 2 -Internal and External Bleaching

Group VII (Control):

Teeth treated with distilled water.

In Group I to III, the respective bleaching agent was syringed into the access cavity of the teeth and sealed with Cavit. In Group IV to VI, the corresponding bleaching agent was syringed into the access cavity of the teeth. The access was sealed with Cavit and the same bleaching agent was applied externally on the buccal surface of the respective teeth for half an hour. The teeth were then washed with distilled water. The color of each tooth was evaluated using the VITA shade guide according to assigned score under day light. Evaluation was performed by two examiners working independently at day 0 before the application of bleaching agent and at 7 and 14 days after the application of bleaching agent. At 7 days, after color determination, the original bleaching agent was washed out with water and the bleaching agent was syringed again and sealed. The next color evaluation was performed at 14 days. The teeth were wrapped in gauze soaked with distilled water and kept in an incubator at 37°C throughout the experiment. In Group VII (control group), only distilled water was placed in the access chamber and then sealed with Cavit.

  Statistic Analysis Top

ANOVA test was used to calculate the level of significance among the tested groups. Intragroup comparison was done using Paired t-test to see the significant change in bleaching at 0, 7, and 14 days for each group. The intergroup comparison was done using one way ANOVA with post hoc Tukey's modification to see efficacy of the groups tested. A comparison was done to check the reliability of results between both the examiners using the kappa reliability test.

  Results Top

The mean of the shade values [Table 2] and the difference between the mean values [Table 3] were calculated (according to assigned score) for all the groups at various time intervals of 0, 7, and 14 days. The mean of score given by both the examiners were taken, as there was 94% agreement between the two examiners according to inter-examiner kappa reliability test.
Table 2: Mean of the shade values (according to the assigned score) for all the groups

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Table 3: Difference in the mean of the shade values

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[Table 2] shows a statistically significant shade change at 7 and 14 days in all the experimental groups (Groups I-VI) (P < 0.001) with maximum shade change at first 7 days. Intergroup comparison according to the mean difference value [Table 3] at 14 days showed maximum bleaching efficacy with Group III and VI with approximately shift of 8 shade tabs. Groups I and IV had a approximate shift of 7 shade tabs, but statistical analysis showed no significant difference between Groups I and IV, and Groups III and VI [Table 4]. Least shade change among the tested specimens was seen in Groups II and V with shift of approximately 5 positions only. The control group (Group VII) showed no difference in color change.
Table 4: Intergroup comparison

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The comparison of two bleaching techniques showed that there was statistically no significant difference in the two subgroups A and B [Table 5].
Table 5: Comparison of internal bleaching v/s internal-external bleaching techniques

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  Discussion Top

The present study was conducted using three different commercially available bleaching agents to compare and evaluate their efficacy. As already many studies have been conducted to prove the efficacy of sodium perborate [10],[13],[14],[17] and it is considered to have lesser side effects, it was not taken in comparison. In all the tested specimens, the access cavities were prepared first and then stained to simulate the condition of traumatized tooth in which penetration of blood from pulp chamber to the dentinal tubules occurs. The shade guide was arranged in order of value from highest to lowest, and visual evaluation was done as it is a commonly used assessment tool. [13],[18] The results of our study showed statistically similar shade change in both 35% H 2 O 2 (Groups II and V) and in Groups I and IV in which 35% CP was used. The results of this comparative study are in concurrence with a study by Lim [13] who reported equal effectiveness of 35% H 2 O 2 and 35% CP gel as intracoronal bleaching agent. They attributed the equal efficacy of both despite of only 12% release of H 2 O 2 from 35% CP to the presence of excess of active ingredient in 35% H 2 O 2 , which simply diffuses unreacted through the root tissue. [13] Another reason for effective results of 35% CP could be because of its ability to increase the dentin permeability and to penetrate deeper, which allows the reversal of chromatic alteration of the dental tissue by oxidation reaction. [19] In a study by Carrasco et al. in 2003, 37% CP had a high increase in dentin permeability as compared to sodium perborate associated with 20% H 2 O 2 and 27% CP. [4]

pH plays an important role in determining the bleaching efficacy. [20] The greater efficacy of CP relates to the relationship between pH and rate of reaction of the bleaching reaction. The pH of CP gel is more as the by-product urea decomposes into CO 2 and ammonia, which raises the pH value of the bleaching agent. [21] Higher the pH, the more free radicals are available for bleaching [20] ; therefore, CP gel may have approximately the equivalent quantity of free radicals as 35% H 2 O 2 gel available for bleaching. [13] Also, CP traverses dentin more slowly [22] and acts as a depot for slow release of CP. [20] Thus, it may remain within dentine where it can break down the chromogens more efficiently as opposed to H 2 O 2 that penetrates dentine more readily .[23]

Earlier studies have shown a higher extra-radicular pH [20],[21] and lower H 2 O 2 penetration from CP when compared with H 2 O 2 . [20],[24] In the present study, it was seen that a lower concentration bleaching agents, i.e. 21% CP showed a less significant shade change as compared to 35% H 2 O 2 and 35% CP. As in our study, shade evaluation was done only till 14 days, it could be postulated that an extended bleaching time [15] with a lower peroxide concentration would yield similar results as that of a higher concentration CP.

In this study, two bleaching techniques were used, i.e. internal and internal-external technique. The inside/outside bleaching was first described by Settembrini et al. [25] As the name implies, the idea is to apply bleaching agent both on the external and internal surfaces of the tooth. This technique may be indicated where simultaneous bleaching of non-vital and vital teeth is required. [26] In our study, the external application of the bleaching agent was performed to evaluate additional whitening effect on teeth or whether it could hasten the bleaching. The application was done externally for half an hour as it is an average recommended time by most manufacturers (21% CP Perfecta premier, 35% CP, Ultrawhite system, Ammdent) and it simulates the clinical in office application time of bleaching agents. However, no difference between the two techniques was observed. This could be possible as staining was done internally, i.e. the teeth were stained after the access opening was prepared; therefore, an external application did not have any additional benefit in lightening the shade of discolored teeth.

  Conclusion Top

Within the limitations of our study, it can be concluded that:

  1. 35% CP was equally effective as 35% H 2 O 2 when the tooth has been artificially discolored with chromogens from the breakdown of blood products
  2. There was no statistically significant difference between the two bleaching techniques: internal and internal-external bleaching techniques; thus, an additional external application of the bleaching agent in a non-vital tooth is not recommended
  3. In our study, 21% CP showed considerable shade reduction but its reported values were less than the other tested bleaching agents.

  References Top

Abbott P, Heah SY. Internal bleaching of teeth: An analysis of 255 teeth. Aust Dent J 2009;54:326-33.  Back to cited text no. 1
Hattab FN, Qudeimat MA, al-Rimawi HS. Dental discoloration: An overview. J Esthet Dent 1999;11:291-310.  Back to cited text no. 2
Sheets CG, Paquette JM. Tooth-whitening modalities for pulpless and discoloured teeth. In: Cohen S, Burns RC. Pathways of the Pulp. 8 th ed. London: Mosby; 2002. p. 749.  Back to cited text no. 3
Carrasco LD, Froner IC, Corona SA, Pecora JD. Effect of internal bleaching agents on the dentinal permeability of non vital teeth: Quantitative assessment. Dent Traumatol 2003;19:85-9.  Back to cited text no. 4
Teixeira EC, Hara AT, Serra MC. Use of 37% carbamide peroxide in the walking bleach technique: A case report. Quintessence Int 2004;35:97-102.  Back to cited text no. 5
Haywood VB, Berry TG. Natural tooth bleaching. In: Summitt JB, Robbins JW. Fundamental of Operative Dentistry: A Contemporary Approach. 3 rd ed. Ch 15. Quintessence Publishing; 2006. p. 438-40.  Back to cited text no. 6
Bleaching of Discoloured Teeth. In: Chandra BS, Krishna VG, editors. Grossmans Endodontic Practice. 12 th ed. Ch 14. New Delhi: Wolters Kluwer; 2010. p. 342.  Back to cited text no. 7
Vachon C, Vanek P, Friedman S. Internal bleaching with 10% carbamide peroxide in vitro. Pract Periodont Aesthet Dent 1998;10:1145-8.  Back to cited text no. 8
Perrine GA, Reichl RB, Baisden MK, Hondrum SO. Comparison of 10% carbamide peroxide and sodium perborate for intracoronal bleaching. Gen Dent 2000;48:264-70.  Back to cited text no. 9
Yui KC, Rodrigues JR, Mancini MN, Balducci I, Gonclaves SE. Ex vivo evaluation of the effectiveness of bleaching agents on the shade alteration of blood stained teeth. Int Endod J 2008;41:485-92.  Back to cited text no. 10
Al-Nazhan S. External root resorption after bleaching: A case report. Oral Surg Oral Med Oral Pathol 1991;72:607-9.  Back to cited text no. 11
Rotstein I, Zalkind M, Mor C, Tarabeah A, Friedman S. In vitro efficacy of sodium perborate preperations used for intracoronal bleaching of discolored non-vital teeth. Endod Dent Traumatol 1991;7:177-80.  Back to cited text no. 12
Lim MY, Lum SO, Poh RS, Lee GP, Lim KC. An in vitro comparison of the bleaching efficacy of 35% carbamide peroxide with established intracoronal bleaching agents. Int Endod J 2004;37:483-8.  Back to cited text no. 13
Gökay O, Zýraman, F, Çali Asal A, Saka OM. Radicular peroxide penetration from carbamide peroxide gels during intracoronal bleaching. Int Endod J 2008;41:556-60.  Back to cited text no. 14
Leonard RH, Sharma A, Haywood VB. Use of different concentrations of carbamide peroxide for bleaching teeth: An in vitro study. Quintessence Int 1998;29:503-7.  Back to cited text no. 15
Freccia WF, Peters DD, Lorton L, Bernier WE. An in vitro comparison of non-vital bleaching techniques in the discolored tooth. J Endod 1982;8:70-7.  Back to cited text no. 16
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Lee GP, Lee MY, Lum SO, Poh RS, Lim KC. Extraradicular diffusion of hydrogen peroxide and pH changes associated with intracoronal bleaching of discoloured teeth using different bleaching agents. J Endod 2004;37:500-6.  Back to cited text no. 20
Price RB, Sedarous M, Hiltz GS. The pH of tooth whitening products. J Can Dent Assoc 2000;66:421-6.  Back to cited text no. 21
Sun G. The role of lasers in cosmetic dentistry. Dent Clin North Am 2000;44:831-50.  Back to cited text no. 22
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Madhu KS, Hegde S, Mathew S, Lata D, Bhandi SH, Shruthi N. Comparison of radicular peroxide leakage from four commonly used bleaching agents following intracoronal bleaching in endodontically treated teeth: An in vitro study. J Int Oral Health 2013;5:49-55.  Back to cited text no. 24
Settembrini L, Gultz J, Kaim J, Scherer J. A technique for bleaching nonvital teeth: Inside/outside bleaching. J Am Dent Assoc 1997;128:1283-4.  Back to cited text no. 25
Carrillo A, Arredondo Trevino MV, Haywood VB. Simultaneous bleaching of vital teeth and an open-chamber nonvital tooth with 10% carbamide peroxide. Quintessence Int 1998;29:643-8.  Back to cited text no. 26


  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]

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