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Spectrophotometric evaluation of color alterations with a new dental bleaching product in patients wearing orthodontic appliances
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Spectrophotometric evaluation of color alterations with a new dental bleaching product in patients wearing orthodontic appliances Enrique Jadad,a Jaime Montoya,b Gonzalo Arana,c Luis Alfonso Arana Gordillo,d Renato Miotto Palo,e and Alessandro D. Loguerciof Barranquilla and Cali, Colombia, and Ponta Grossa, Paran a, and Indaiatuba, S~ ao Paulo, Brazil
Introduction: Our objective was to assess the effectiveness of a new bleaching agent (8% hydrogen peroxide) used in patients wearing fixed orthodontic appliances. Methods: Six anterior maxillary teeth of 40 patients aged 18 to 40 years were assessed. The patients were divided into 2 groups (20 in each group): in group A, the patients used the bleaching agent during orthodontic treatment; in group B, the patients used the bleaching agent after orthodontic treatment. For each group, a record of the initial tooth shade was taken with a polyvinyl siloxane matrix and a spectrophotometer. The groups had bleaching treatments with an 8% hydrogen peroxide product (Opalescence Treswhite Ortho, Ultradent, Opal Orthodontics, South Jordan, Utah) for 10 days in 45-minute sessions. For group A, the treatment was performed 10 days before finishing orthodontic treatment; at the end of the treatment, a new tooth shade record was taken with the polyvinyl siloxane matrix and a spectrophotometer. The subjects in group B had the same bleaching protocol after their brackets were removed. Results: It was observed that, for the group without brackets, the color alteration ranged from 3 to 12 (mean, 8; median, 8.3); for the group with brackets, the range was between 4 and 13 (mean, 9; median, 8.5), indicating significant tooth bleaching in both groups with and without brackets (P .0.05). Conclusions: Opalescence Treswhite Ortho was shown to be an efficient bleaching agent in patients wearing fixed orthodontic appliances. (Am J Orthod Dentofacial Orthop 2011;140:e43-e47)
T
he popularity of dental bleaching has increased since 1989, and it is now frequently used in most dental procedures.1,2 This procedure consists of the application of hydrogen peroxide-based gel, first described by Kingsbury3 in 1861, and carbamide peroxide. Bleaching treatments in healthy teeth can be performed at home or at dental offices under professional supervision, and their popularity can be explained by the many bleaching products on the market.4 Because it is easy to perform more conservative treatments to a Private practice, prosthodontics, occlusion, and osteointegrated implants, Barranquilla, Colombia. b Private practice, orthodontics, Barranquilla, Colombia. c Professor, Department of Restorative Dentistry, School of Dentistry, University Santiago de Cali, Cali, Colombia. d Resident, Department of Restorative Dentistry, School of Dentistry, University Estadual de Ponta Grossa, Ponta Grossa, Parana, Brazil. e Private practice, esthetic dentistry, Indaiatuba, S~ao Paulo, Brazil. f Professor, Department of Restorative Dentistry, School of Dentistry, University Estadual de Ponta Grossa, Ponta Grossa, Parana, Brazil. The authors report no commercial, proprietary, or financial interest in the products or companies described in this article. Reprint requests to: Enrique Jadad, Cra. 50 # 82 - 168 Cons. 902. Barranquilla Colombia 08001000, Colombia; e-mail, [email protected]. Submitted, July 2010; revised and accepted, November 2010. 0889-5406/$36.00 Copyright Ó 2011 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2010.11.021
lighten teeth, bleaching offers patients a minimally invasive treatment with excellent esthetic results.5,6 Many young and adult patients are reluctant to wear fixed orthodontic appliances on their teeth because of the unattractive appearance when these treatments are performed. In addition to this phenomenon, patients who suffer color alterations of their teeth because of difficulty in performing oral hygiene are more likely to reject these treatments.6 It has been reported that tooth-whitening products can be used before or after orthodontic treatment; however, in a previous study, the use of bleaching agents before adhesive procedures with resin materials, such as those used to bond orthodontic appliances, was questioned.7 Because most patients wearing orthodontic appliances perceive alterations in the shade of their teeth once treatment is interrupted and they attribute these stains to the treatment, it is important to provide them with orthodontic appliances for esthetic satisfaction and the possibility that their teeth will have a socially acceptable color during treatment. Hydrogen peroxide whitens the teeth poly-directionally, even in areas covered by orthodontic appliances; this makes it possible to achieve a whitening effect under the appliances.2 e43
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Fig 1. A, Silicone matrix with 5-mm openings in the middle third; B, color recording with the VITA Easyshade spectrophotometer.
To fulfill the esthetic needs of patients wearing orthodontic appliances, a product called Opalescence Treswhite Ortho (Ultradent, Opal Orthodontics, South Jordan, Utah) has been developed. Treswhite Ortho is presented with a semirigid external tray and a second highly flexible tray for home or in-office use, easily adaptable to the topography of the teeth and the brackets. This preloaded flexible tray contains 8% hydrogen peroxide, fluoride, and potassium nitrate, which must be kept on the brackets for about 45 minutes to achieve adequate contact time between the whitening gel, the teeth, and the brackets. After each 45-minute daily session, the flexible tray is easily removed from the mouth and discarded. After that, the patient can remove any remaining gel by brushing the teeth. Although previous studies have already investigated similar products as used in this study, no clinical studies assessing this material were found in the literature.8-11 Based on the above-mentioned explanation, the aim of this study was to clinically assess the effectiveness of this new 8% hydrogen peroxide-based bleaching agent in patients wearing fixed orthodontic appliances. The null hypothesis was that the bleaching agent would have the same effect with or without the brackets. MATERIAL AND METHODS
The study was approved by the Ethics Research Committee of the Universidad Santiago de Cali, in Cali, Colombia. Before enrollment, each subject received an informed consent form containing all the information regarding the risks and benefits of treatment. All participants signed the consent form. A total of 6 anterior maxillary teeth of 40 patients referred for orthodontic treatment, aged between 18 and 40 years, who were not pregnant or breast feeding, and were nonsmokers, were assessed, totaling 240 teeth without caries, restorations, pigmentations, stains, or periodontal disease. The 40 patients were divided into 2 groups (n 5 20). In group
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A, the patients used the bleaching agent during orthodontic treatment; in group B, the patients used the bleaching agent after orthodontic treatment. For both groups, color measurements were made with a VITA Easyshade spectrophotometer (Easyshade, Vident, Brea, Calif) before applying the bleaching agent. The measurements were made by 1 operator (E.J.) using a preestablished matrix made of high-viscosity silicone (Zetalabor, Zhermack, Polesine Badia, Italy). This matrix was made individually for each patient. In the matrix, there was a circular opening located on the central part of the buccal or oral surface of tooth to be measured; it was configured with the help of a circular metal cutting device measuring 5 mm in diameter. This matrix served as the standardized guide to measure the color with the spectrophotometer12 (Fig 1). For the calibration procedure, an experienced clinician and a technician performed the color measurement and bleaching procedure to identify all of the steps involved in the use of the EasyShade. Then the operator used the device under the direct supervision of the experienced clinician. All problems during this procedure were shown to the operator before starting the study. Only after that, the operator was considered calibrated to perform the bleaching procedure. For group A, the initial color of the teeth was recorded by using the VITA Easyshade spectrophotometer (Fig 1, B), before bonding the brackets. Once the brackets were bonded, the new bleaching agent with 8% hydrogen peroxide (Opalescence Treswhite Ortho) was applied (Fig 2), for 10 consecutive days in 45-minute daily sessions, 10 days before finishing orthodontic treatment. After the brackets were removed (Fig 3), the enamel surfaces were adequately cleaned, and the final color was measured again with the VITA Easyshade spectrophotometer. For Group B, after finishing orthodontic therapy, the brackets were removed, the enamel surfaces were adequately cleaned, and the initial color of the teeth was
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Fig 2. A, Opalescence Treswhite Ortho tray in the maxillary arch; B, after removing the external bleaching tray, the internal tray stays in place.
Fig 3. A, Enamel surface before cement removal; B, color measurement after polishing the enamel surface.
B1 1
A1 2
B2 3
D2 4
A2 5
C1 6
C2 7
D4 8
A3 9
D3 10
B3 11
A3,5 12
B4 13
C3 14
A4 15
C4 16
Fig 4. Color equivalence of the shade guide according to the ascending numeric scale. The shade guide's 16 tabs are arranged from the highest (B1) to the lowest (C4) value. Although this scale is not linear in the truest sense, we treated the changes as representing a continuous and approximately linear ranking for the purpose of analysis.
recorded with the VITA Easyshade spectrophotometer. Then the same bleaching agent was used. This was used for 10 consecutive days in 45-minute daily sessions; on day 10, the color was measured again with the spectrophotometer. Because it is a new product on the market and to prevent patients from interrupting its use, as could happen at home, this study was carried out under professional supervision in a dental office. For both groups, the bleaching processes and the color records during the 15-month study period were standardized and performed by 1 operator (G.A.). The data obtained with the VITA Easyshade spectrophotometer in the 2 groups were recorded, based on the colors of the shade guide VITA Classic Scale (VITA, Zahnfabrik, Bad Sackingen, Germany). To facilitate the statistical procedures, the colors of the shade guide
were organized from the highest to the lowest values (Fig 4). Each shade was represented by a numeric value in a continuous scale from 1 to 16. Statistical analysis
At each color appointment, 3 color measurements were made for each tooth, and these values were averaged for statistical purposes. Two types of statistical tests were used to analyze the data. The first consisted of comparison of the mean color of each tooth (maxillary left and right central and lateral incisors, and canines) at each time (before and after bleaching) with the Wilcoxon nonparametric test. The second one consisted of comparison of the mean color in each group (with and without brackets) after bleaching treatment with the Mann-Whitney nonparametric test. A level of significance of P \0.05 was used for all the tests.
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Table I. Comparison of the medians between the study groups (Wilcoxon nonparametric test) Group without brackets Maxillary tooth Right canine Right lateral incisor Right central incisor Left central incisor Left lateral incisor Left canine
Initial color (median) 13 11 10 10 11 13
Group with brackets
Final color (median) 5 2 2 2 2 5
P value 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001
Initial color (median) 14 10 11 11 10 14
Final color (median) 4.5 3 2 2 2.5 5
P value 0.0003 0.0001 0.0001 0.0001 0.0001 0.0001
Table II. Mean reduction in color for the 2 groups after bleaching treatment (Mann-Whitney nonparametric test) Group With brackets Without brackets
Different scale of value (median/mean of the group ) 9/8.5
Minimum value 4
Maximum value 13
Interquartile degree (7.3-12)
8/8.3
3
12
(6.5-10.5)
RESULTS
The average period between the first and last assessments of color was 13.5 months for the orthodontic group (group A) and 12.5 months for the group without orthodontic treatment (group B). The results were summarized in the Table I. In each appointment, there was no difference between the 3 color measurements obtained for each tooth (data not shown). When analyzing the data obtained with the Wilcoxon nonparametric statistical test, the differences were all statistically significant (P \0.05) (Table I). A statistically significant difference was found between the mean values of color equivalence at the beginning and end of treatment, showing lower values in the VITA Classic Scale; ie, there was a higher degree of bleaching for all the teeth measured in both groups, proving the effectiveness of the bleaching agent. From the differences obtained in the scale of color values at the beginning and end of treatment, the medians and means of the differences for the 2 groups were obtained, showing that, for the group without brackets, the change in the scale of color values ranged from 3 to 12 (mean, 8; median, 8.3) and, for the group with brackets, the values were between 4 and 13 (mean, 9; median, 8.5), indicating greater change (bleaching) in the group with brackets, but with no statistically significant difference according to the Mann-Whitney test (P .0.05) (Table II). DISCUSSION
In this study, a new 8% hydrogen peroxide-based bleaching product was used; it has been proposed for
July 2011 Vol 140 Issue 1
P value – 0.56 –
in-office dental bleaching during orthodontic treatment. Our results showed that this product provides significant bleaching according to the Vita color scale, in a manner similar to previous studies.8,13-15 In 2009, Dietschi et al8 assessed the effectiveness of 7 bleaching products of different brands with various concentration percentages, among them, hydrogen peroxide at a concentration of 9% (Opalescence Treswhite Ultradent) with a tray-type application, similar to the one used in this study (8% hydrogen peroxide). When applied on bovine dentin and enamel disks, hydrogen peroxide-based tray systems were shown to be effective and fast bleaching agents. In 2004, Gerlach and Barker15 also showed the effectiveness and safety of 10% hydrogen peroxide in a double-blind controlled clinical trial. In their study, 39 patients participated, and the bleaching agent was applied with a system of adhesive strips (Crest Whitestrips Premium). The strips were used twice a day for 30 minutes for 7 days with no supervision. The results of their study were similar to those of ours, showing that, after treatment, 10% peroxide hydrogen showed significant bleaching compared with the initial record, and the effect was more evident in the last color record on the seventh day. Although the percentage concentration of hydrogen peroxide in Opalescence Treswhite Ortho can be considered low when compared with other dental bleaching products used in the office, it could be considered safer because of its lower concentration. However, the low percentage of hydrogen peroxide did not affect its clinical effectiveness because, at the end of the study, significant dental bleaching occurred in both groups. Based on the
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study of Joiner,16 concentration and time are key factors that affect the efficiency of peroxide-based bleaching treatments. However, in general, high concentrations work faster than low concentrations, but these can be as efficient as high concentrations if treatment time is longer. As discussed above, Opalescence Treswhite Ortho was shown to be effective even in the group with orthodontic appliances. The null hypotheses of the study was accepted that the bleaching agent would have no significant difference with or without brackets. Based on our data, it was shown that Opalescence Treswhite Ortho is an effective dental bleaching agent for teeth with or without brackets. This can be explained by the permeability of the tooth structure and the molecular weight of 34 mg per mole of hydrogen peroxide.17 This penetration capacity makes free radicals generated by hydrogen peroxide act poly-directionally, reaching even under the brackets and adhesives of the cementation resins of orthodontic appliances. Sulieman et al18 observed that the active agent of the bleaching treatment did not penetrate the entire dentin thickness and concluded that bleaching occurs in the dentin area immediately below the enamel, contributing again to our hypotheses that a low concentration with less penetration power bleaches effectively, as discussed above. Also, the commercial presentation of Opalescence Treswhite Ortho gel might have contributed to the satisfactory results obtained in this study, since most gels for these products often contain polymers, components that help improve their rheologic properties, preventing excessive swallowing of the material, controlling the release of oxygen by the bleaching agent, contributing to the cohesion of the product on the tooth surface, and, in the case of orthodontic appliances, maximizing the efficiency of the Opalescence Treswhite Ortho bleaching agent.19 Although several articles have shown the effectiveness of various dental bleaching agents in vitro, few studies have evaluated bleaching agents for domestic and professional use. The absence of in-vivo studies with larger samples and statistically significant results on dental bleaching in patients wearing fixed orthodontic appliances limits clinical comparisons and the validation of these studies. Our results are quite clear in concluding that Opalescence Treswhite Ortho is effective with or without brackets, providing an innovative application for bleaching products. However, more clinical studies should be performed to evaluate the hypotheses tested in this study.
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We thank Ultradent for donating the products for this study. REFERENCES 1. Luo W, Westland S, Brunton P, Ellwood R, Pretty IA, Mohan N. Comparison of the ability of different colour indices to assess changes in tooth whiteness. J Dent 2007;35:109-16. 2. Haywood VB, Heymann HO. Nightguard vital bleaching: how safe is it? Quintessence Int 1991;22:515-23. 3. Kingsbury CA. Discoloration of dentine. Dent Cosmos 1861;3:57-60. 4. Barghi N. Making a clinical decision for vital tooth bleaching: at-home or in-office? Compend Contin Educ Dent 1998;19: 831-8. 5. Bistey T, Nagy IP, Sim o A, Hegedus C. In vitro FT-IR study of the effects of hydrogen peroxide on superficial tooth enamel. J Dent 2007;35:325-30. 6. Bulut H, Turkun M, Kaya AD. Effect of an antioxidizing agent on the shear bond strength of brackets bonded to bleached human enamel. Am J Orthod Dentofacial Orthop 2006;129:266-72. 7. Sulieman M. An overview of bleaching techniques: I. History, chemistry, safety and legal aspects. Dent Update 2004;31: 608-10, 612-4, 616. 8. Dietschi D, Benbachir N, Krejci I. In vitro colorimetric evaluation of the efficacy of home bleaching and over-the-counter bleaching products. Quintessence Int 2010;41:505-16. 9. Dietrich AM, English J, McGrory K, Ontiveros J, Powers JM, Bussa HI Jr, et al. A comparison of shear bond strengths on bleached and unbleached bovine enamel. Tex Dent J 2010;127: 285-91. 10. Grobler SR, Majeed A, Moola MH. Effect of various tooth-whitening products on enamel microhardness. SADJ 2009;64:474-9. 11. Majeed A, Grobler SR, Moola MH, Rossouw RJ, van Kotze TJ. Effect of four different opalescence tooth-whitening products on enamel microhardness. SADJ 2008;63:282-4, 286. 12. Marson FC, Sensi LG, Vieira LC, Ara ujo E. Clinical evaluation of in-office dental bleaching treatments with and without the use of light-activation sources. Oper Dent 2008;33:15-22. 13. Shahidi H, Barker ML, Sagel PA, Gerlach RW. Randomized controlled trial of 10% hydrogen peroxide whitening strips. J Clin Dent 2005;16:91-5. 14. Swift EJ Jr, Heymann HO, Wilder AD Jr, Barker ML, Gerlach RW. Effects of duration of whitening strip treatment on tooth color: a randomized, placebo-controlled clinical trial. J Dent 2009; 37:Suppl 1:e51-6. 15. Gerlach RW, Barker ML. Clinical response of three direct-to-consumer whitening products: strips, paint-on gel, and dentifrice. Compend Contin Educ Dent 2003;24:458, 461-4. 16. Joiner A. The bleaching of teeth: a review of the literature. J Dent 2006;34:412-9. 17. Kugel G, Petkevis J, Gurgan S, Doherty E. Separate whitening effects on enamel and dentin after fourteen days. J Endod 2007; 33:34-7. 18. Sulieman M, Addy M, Rees JS. Development and evaluation of a method in vitro to study the effectiveness of tooth bleaching. J Dent 2003;31:415-22. 19. Wille T, Combe EC, Pesun IJ, Giles DW. Rheological characteristics of tooth bleaching materials. J Oral Rehabil 2000;27:1060-3.
American Journal of Orthodontics and Dentofacial Orthopedics
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Spectrophotometric evaluation of color alterations with a new dental bleaching product in patients wearing orthodontic appliances Enrique Jadad,a Jaime Montoya,b Gonzalo Arana,c Luis Alfonso Arana Gordillo,d Renato Miotto Palo,e and Alessandro D. Loguerciof Barranquilla and Cali, Colombia, and Ponta Grossa, Paran a, and Indaiatuba, S~ ao Paulo, Brazil
Introduction: Our objective was to assess the effectiveness of a new bleaching agent (8% hydrogen peroxide) used in patients wearing fixed orthodontic appliances. Methods: Six anterior maxillary teeth of 40 patients aged 18 to 40 years were assessed. The patients were divided into 2 groups (20 in each group): in group A, the patients used the bleaching agent during orthodontic treatment; in group B, the patients used the bleaching agent after orthodontic treatment. For each group, a record of the initial tooth shade was taken with a polyvinyl siloxane matrix and a spectrophotometer. The groups had bleaching treatments with an 8% hydrogen peroxide product (Opalescence Treswhite Ortho, Ultradent, Opal Orthodontics, South Jordan, Utah) for 10 days in 45-minute sessions. For group A, the treatment was performed 10 days before finishing orthodontic treatment; at the end of the treatment, a new tooth shade record was taken with the polyvinyl siloxane matrix and a spectrophotometer. The subjects in group B had the same bleaching protocol after their brackets were removed. Results: It was observed that, for the group without brackets, the color alteration ranged from 3 to 12 (mean, 8; median, 8.3); for the group with brackets, the range was between 4 and 13 (mean, 9; median, 8.5), indicating significant tooth bleaching in both groups with and without brackets (P .0.05). Conclusions: Opalescence Treswhite Ortho was shown to be an efficient bleaching agent in patients wearing fixed orthodontic appliances. (Am J Orthod Dentofacial Orthop 2011;140:e43-e47)
T
he popularity of dental bleaching has increased since 1989, and it is now frequently used in most dental procedures.1,2 This procedure consists of the application of hydrogen peroxide-based gel, first described by Kingsbury3 in 1861, and carbamide peroxide. Bleaching treatments in healthy teeth can be performed at home or at dental offices under professional supervision, and their popularity can be explained by the many bleaching products on the market.4 Because it is easy to perform more conservative treatments to a Private practice, prosthodontics, occlusion, and osteointegrated implants, Barranquilla, Colombia. b Private practice, orthodontics, Barranquilla, Colombia. c Professor, Department of Restorative Dentistry, School of Dentistry, University Santiago de Cali, Cali, Colombia. d Resident, Department of Restorative Dentistry, School of Dentistry, University Estadual de Ponta Grossa, Ponta Grossa, Parana, Brazil. e Private practice, esthetic dentistry, Indaiatuba, S~ao Paulo, Brazil. f Professor, Department of Restorative Dentistry, School of Dentistry, University Estadual de Ponta Grossa, Ponta Grossa, Parana, Brazil. The authors report no commercial, proprietary, or financial interest in the products or companies described in this article. Reprint requests to: Enrique Jadad, Cra. 50 # 82 - 168 Cons. 902. Barranquilla Colombia 08001000, Colombia; e-mail, [email protected]. Submitted, July 2010; revised and accepted, November 2010. 0889-5406/$36.00 Copyright Ó 2011 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2010.11.021
lighten teeth, bleaching offers patients a minimally invasive treatment with excellent esthetic results.5,6 Many young and adult patients are reluctant to wear fixed orthodontic appliances on their teeth because of the unattractive appearance when these treatments are performed. In addition to this phenomenon, patients who suffer color alterations of their teeth because of difficulty in performing oral hygiene are more likely to reject these treatments.6 It has been reported that tooth-whitening products can be used before or after orthodontic treatment; however, in a previous study, the use of bleaching agents before adhesive procedures with resin materials, such as those used to bond orthodontic appliances, was questioned.7 Because most patients wearing orthodontic appliances perceive alterations in the shade of their teeth once treatment is interrupted and they attribute these stains to the treatment, it is important to provide them with orthodontic appliances for esthetic satisfaction and the possibility that their teeth will have a socially acceptable color during treatment. Hydrogen peroxide whitens the teeth poly-directionally, even in areas covered by orthodontic appliances; this makes it possible to achieve a whitening effect under the appliances.2 e43
Jadad et al
e44
Fig 1. A, Silicone matrix with 5-mm openings in the middle third; B, color recording with the VITA Easyshade spectrophotometer.
To fulfill the esthetic needs of patients wearing orthodontic appliances, a product called Opalescence Treswhite Ortho (Ultradent, Opal Orthodontics, South Jordan, Utah) has been developed. Treswhite Ortho is presented with a semirigid external tray and a second highly flexible tray for home or in-office use, easily adaptable to the topography of the teeth and the brackets. This preloaded flexible tray contains 8% hydrogen peroxide, fluoride, and potassium nitrate, which must be kept on the brackets for about 45 minutes to achieve adequate contact time between the whitening gel, the teeth, and the brackets. After each 45-minute daily session, the flexible tray is easily removed from the mouth and discarded. After that, the patient can remove any remaining gel by brushing the teeth. Although previous studies have already investigated similar products as used in this study, no clinical studies assessing this material were found in the literature.8-11 Based on the above-mentioned explanation, the aim of this study was to clinically assess the effectiveness of this new 8% hydrogen peroxide-based bleaching agent in patients wearing fixed orthodontic appliances. The null hypothesis was that the bleaching agent would have the same effect with or without the brackets. MATERIAL AND METHODS
The study was approved by the Ethics Research Committee of the Universidad Santiago de Cali, in Cali, Colombia. Before enrollment, each subject received an informed consent form containing all the information regarding the risks and benefits of treatment. All participants signed the consent form. A total of 6 anterior maxillary teeth of 40 patients referred for orthodontic treatment, aged between 18 and 40 years, who were not pregnant or breast feeding, and were nonsmokers, were assessed, totaling 240 teeth without caries, restorations, pigmentations, stains, or periodontal disease. The 40 patients were divided into 2 groups (n 5 20). In group
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A, the patients used the bleaching agent during orthodontic treatment; in group B, the patients used the bleaching agent after orthodontic treatment. For both groups, color measurements were made with a VITA Easyshade spectrophotometer (Easyshade, Vident, Brea, Calif) before applying the bleaching agent. The measurements were made by 1 operator (E.J.) using a preestablished matrix made of high-viscosity silicone (Zetalabor, Zhermack, Polesine Badia, Italy). This matrix was made individually for each patient. In the matrix, there was a circular opening located on the central part of the buccal or oral surface of tooth to be measured; it was configured with the help of a circular metal cutting device measuring 5 mm in diameter. This matrix served as the standardized guide to measure the color with the spectrophotometer12 (Fig 1). For the calibration procedure, an experienced clinician and a technician performed the color measurement and bleaching procedure to identify all of the steps involved in the use of the EasyShade. Then the operator used the device under the direct supervision of the experienced clinician. All problems during this procedure were shown to the operator before starting the study. Only after that, the operator was considered calibrated to perform the bleaching procedure. For group A, the initial color of the teeth was recorded by using the VITA Easyshade spectrophotometer (Fig 1, B), before bonding the brackets. Once the brackets were bonded, the new bleaching agent with 8% hydrogen peroxide (Opalescence Treswhite Ortho) was applied (Fig 2), for 10 consecutive days in 45-minute daily sessions, 10 days before finishing orthodontic treatment. After the brackets were removed (Fig 3), the enamel surfaces were adequately cleaned, and the final color was measured again with the VITA Easyshade spectrophotometer. For Group B, after finishing orthodontic therapy, the brackets were removed, the enamel surfaces were adequately cleaned, and the initial color of the teeth was
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Fig 2. A, Opalescence Treswhite Ortho tray in the maxillary arch; B, after removing the external bleaching tray, the internal tray stays in place.
Fig 3. A, Enamel surface before cement removal; B, color measurement after polishing the enamel surface.
B1 1
A1 2
B2 3
D2 4
A2 5
C1 6
C2 7
D4 8
A3 9
D3 10
B3 11
A3,5 12
B4 13
C3 14
A4 15
C4 16
Fig 4. Color equivalence of the shade guide according to the ascending numeric scale. The shade guide's 16 tabs are arranged from the highest (B1) to the lowest (C4) value. Although this scale is not linear in the truest sense, we treated the changes as representing a continuous and approximately linear ranking for the purpose of analysis.
recorded with the VITA Easyshade spectrophotometer. Then the same bleaching agent was used. This was used for 10 consecutive days in 45-minute daily sessions; on day 10, the color was measured again with the spectrophotometer. Because it is a new product on the market and to prevent patients from interrupting its use, as could happen at home, this study was carried out under professional supervision in a dental office. For both groups, the bleaching processes and the color records during the 15-month study period were standardized and performed by 1 operator (G.A.). The data obtained with the VITA Easyshade spectrophotometer in the 2 groups were recorded, based on the colors of the shade guide VITA Classic Scale (VITA, Zahnfabrik, Bad Sackingen, Germany). To facilitate the statistical procedures, the colors of the shade guide
were organized from the highest to the lowest values (Fig 4). Each shade was represented by a numeric value in a continuous scale from 1 to 16. Statistical analysis
At each color appointment, 3 color measurements were made for each tooth, and these values were averaged for statistical purposes. Two types of statistical tests were used to analyze the data. The first consisted of comparison of the mean color of each tooth (maxillary left and right central and lateral incisors, and canines) at each time (before and after bleaching) with the Wilcoxon nonparametric test. The second one consisted of comparison of the mean color in each group (with and without brackets) after bleaching treatment with the Mann-Whitney nonparametric test. A level of significance of P \0.05 was used for all the tests.
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Table I. Comparison of the medians between the study groups (Wilcoxon nonparametric test) Group without brackets Maxillary tooth Right canine Right lateral incisor Right central incisor Left central incisor Left lateral incisor Left canine
Initial color (median) 13 11 10 10 11 13
Group with brackets
Final color (median) 5 2 2 2 2 5
P value 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001
Initial color (median) 14 10 11 11 10 14
Final color (median) 4.5 3 2 2 2.5 5
P value 0.0003 0.0001 0.0001 0.0001 0.0001 0.0001
Table II. Mean reduction in color for the 2 groups after bleaching treatment (Mann-Whitney nonparametric test) Group With brackets Without brackets
Different scale of value (median/mean of the group ) 9/8.5
Minimum value 4
Maximum value 13
Interquartile degree (7.3-12)
8/8.3
3
12
(6.5-10.5)
RESULTS
The average period between the first and last assessments of color was 13.5 months for the orthodontic group (group A) and 12.5 months for the group without orthodontic treatment (group B). The results were summarized in the Table I. In each appointment, there was no difference between the 3 color measurements obtained for each tooth (data not shown). When analyzing the data obtained with the Wilcoxon nonparametric statistical test, the differences were all statistically significant (P \0.05) (Table I). A statistically significant difference was found between the mean values of color equivalence at the beginning and end of treatment, showing lower values in the VITA Classic Scale; ie, there was a higher degree of bleaching for all the teeth measured in both groups, proving the effectiveness of the bleaching agent. From the differences obtained in the scale of color values at the beginning and end of treatment, the medians and means of the differences for the 2 groups were obtained, showing that, for the group without brackets, the change in the scale of color values ranged from 3 to 12 (mean, 8; median, 8.3) and, for the group with brackets, the values were between 4 and 13 (mean, 9; median, 8.5), indicating greater change (bleaching) in the group with brackets, but with no statistically significant difference according to the Mann-Whitney test (P .0.05) (Table II). DISCUSSION
In this study, a new 8% hydrogen peroxide-based bleaching product was used; it has been proposed for
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P value – 0.56 –
in-office dental bleaching during orthodontic treatment. Our results showed that this product provides significant bleaching according to the Vita color scale, in a manner similar to previous studies.8,13-15 In 2009, Dietschi et al8 assessed the effectiveness of 7 bleaching products of different brands with various concentration percentages, among them, hydrogen peroxide at a concentration of 9% (Opalescence Treswhite Ultradent) with a tray-type application, similar to the one used in this study (8% hydrogen peroxide). When applied on bovine dentin and enamel disks, hydrogen peroxide-based tray systems were shown to be effective and fast bleaching agents. In 2004, Gerlach and Barker15 also showed the effectiveness and safety of 10% hydrogen peroxide in a double-blind controlled clinical trial. In their study, 39 patients participated, and the bleaching agent was applied with a system of adhesive strips (Crest Whitestrips Premium). The strips were used twice a day for 30 minutes for 7 days with no supervision. The results of their study were similar to those of ours, showing that, after treatment, 10% peroxide hydrogen showed significant bleaching compared with the initial record, and the effect was more evident in the last color record on the seventh day. Although the percentage concentration of hydrogen peroxide in Opalescence Treswhite Ortho can be considered low when compared with other dental bleaching products used in the office, it could be considered safer because of its lower concentration. However, the low percentage of hydrogen peroxide did not affect its clinical effectiveness because, at the end of the study, significant dental bleaching occurred in both groups. Based on the
American Journal of Orthodontics and Dentofacial Orthopedics
Jadad et al
study of Joiner,16 concentration and time are key factors that affect the efficiency of peroxide-based bleaching treatments. However, in general, high concentrations work faster than low concentrations, but these can be as efficient as high concentrations if treatment time is longer. As discussed above, Opalescence Treswhite Ortho was shown to be effective even in the group with orthodontic appliances. The null hypotheses of the study was accepted that the bleaching agent would have no significant difference with or without brackets. Based on our data, it was shown that Opalescence Treswhite Ortho is an effective dental bleaching agent for teeth with or without brackets. This can be explained by the permeability of the tooth structure and the molecular weight of 34 mg per mole of hydrogen peroxide.17 This penetration capacity makes free radicals generated by hydrogen peroxide act poly-directionally, reaching even under the brackets and adhesives of the cementation resins of orthodontic appliances. Sulieman et al18 observed that the active agent of the bleaching treatment did not penetrate the entire dentin thickness and concluded that bleaching occurs in the dentin area immediately below the enamel, contributing again to our hypotheses that a low concentration with less penetration power bleaches effectively, as discussed above. Also, the commercial presentation of Opalescence Treswhite Ortho gel might have contributed to the satisfactory results obtained in this study, since most gels for these products often contain polymers, components that help improve their rheologic properties, preventing excessive swallowing of the material, controlling the release of oxygen by the bleaching agent, contributing to the cohesion of the product on the tooth surface, and, in the case of orthodontic appliances, maximizing the efficiency of the Opalescence Treswhite Ortho bleaching agent.19 Although several articles have shown the effectiveness of various dental bleaching agents in vitro, few studies have evaluated bleaching agents for domestic and professional use. The absence of in-vivo studies with larger samples and statistically significant results on dental bleaching in patients wearing fixed orthodontic appliances limits clinical comparisons and the validation of these studies. Our results are quite clear in concluding that Opalescence Treswhite Ortho is effective with or without brackets, providing an innovative application for bleaching products. However, more clinical studies should be performed to evaluate the hypotheses tested in this study.
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We thank Ultradent for donating the products for this study. REFERENCES 1. Luo W, Westland S, Brunton P, Ellwood R, Pretty IA, Mohan N. Comparison of the ability of different colour indices to assess changes in tooth whiteness. J Dent 2007;35:109-16. 2. Haywood VB, Heymann HO. Nightguard vital bleaching: how safe is it? Quintessence Int 1991;22:515-23. 3. Kingsbury CA. Discoloration of dentine. Dent Cosmos 1861;3:57-60. 4. Barghi N. Making a clinical decision for vital tooth bleaching: at-home or in-office? Compend Contin Educ Dent 1998;19: 831-8. 5. Bistey T, Nagy IP, Sim o A, Hegedus C. In vitro FT-IR study of the effects of hydrogen peroxide on superficial tooth enamel. J Dent 2007;35:325-30. 6. Bulut H, Turkun M, Kaya AD. Effect of an antioxidizing agent on the shear bond strength of brackets bonded to bleached human enamel. Am J Orthod Dentofacial Orthop 2006;129:266-72. 7. Sulieman M. An overview of bleaching techniques: I. History, chemistry, safety and legal aspects. Dent Update 2004;31: 608-10, 612-4, 616. 8. Dietschi D, Benbachir N, Krejci I. In vitro colorimetric evaluation of the efficacy of home bleaching and over-the-counter bleaching products. Quintessence Int 2010;41:505-16. 9. Dietrich AM, English J, McGrory K, Ontiveros J, Powers JM, Bussa HI Jr, et al. A comparison of shear bond strengths on bleached and unbleached bovine enamel. Tex Dent J 2010;127: 285-91. 10. Grobler SR, Majeed A, Moola MH. Effect of various tooth-whitening products on enamel microhardness. SADJ 2009;64:474-9. 11. Majeed A, Grobler SR, Moola MH, Rossouw RJ, van Kotze TJ. Effect of four different opalescence tooth-whitening products on enamel microhardness. SADJ 2008;63:282-4, 286. 12. Marson FC, Sensi LG, Vieira LC, Ara ujo E. Clinical evaluation of in-office dental bleaching treatments with and without the use of light-activation sources. Oper Dent 2008;33:15-22. 13. Shahidi H, Barker ML, Sagel PA, Gerlach RW. Randomized controlled trial of 10% hydrogen peroxide whitening strips. J Clin Dent 2005;16:91-5. 14. Swift EJ Jr, Heymann HO, Wilder AD Jr, Barker ML, Gerlach RW. Effects of duration of whitening strip treatment on tooth color: a randomized, placebo-controlled clinical trial. J Dent 2009; 37:Suppl 1:e51-6. 15. Gerlach RW, Barker ML. Clinical response of three direct-to-consumer whitening products: strips, paint-on gel, and dentifrice. Compend Contin Educ Dent 2003;24:458, 461-4. 16. Joiner A. The bleaching of teeth: a review of the literature. J Dent 2006;34:412-9. 17. Kugel G, Petkevis J, Gurgan S, Doherty E. Separate whitening effects on enamel and dentin after fourteen days. J Endod 2007; 33:34-7. 18. Sulieman M, Addy M, Rees JS. Development and evaluation of a method in vitro to study the effectiveness of tooth bleaching. J Dent 2003;31:415-22. 19. Wille T, Combe EC, Pesun IJ, Giles DW. Rheological characteristics of tooth bleaching materials. J Oral Rehabil 2000;27:1060-3.
American Journal of Orthodontics and Dentofacial Orthopedics
July 2011 Vol 140 Issue 1