|Year : 2014 | Volume
| Issue : 2 | Page : 83-87
Influence of tea and cola on tooth color after two in-office bleaching applications
Muhammet Karadas1, Erhan Tahan2, Sezer Demirbuga3, Nilgun Seven4
1 Department of Restorative Dentistry, Recep Tayyip Erdogan University, Rize, Turkey
2 Department of Endodontic Treatment, Recep Tayyip Erdogan University, Rize, Turkey
3 Department of Restorative Dentistry, Erciyes University, Kayseri, Turkey
4 Department of Restorative Dentistry, Atatürk Üniversity, Erzurum, Turkey
|Date of Web Publication||11-Jul-2014|
Recep Tayyip Erdo?an Üniversity, Faculty of Dentitsry, Department of Restorative Dentistry, Rize - 53100
Source of Support: None, Conflict of Interest: None
Aim: To evaluate color changes of teeth after immersion in tea and cola following the application of two in-office bleaching products. Materials and Methods: A total of 60 specimens were obtained from 60 extracted sound human maxillary central teeth. The specimens were randomly divided into three groups (n = 20). Group A was the control group (no bleaching). In Group B, the specimens were bleached with Opalescence Xtra Boost (Ultradent), and in Group C, they were bleached with Smartbleach (High Tech Laser). These groups were then divided into two subgroups (n = 10 in each) according to the colorant solution used: tea and cola. Each bleaching agent was applied to the specimens according to the manufacturer's recommendations. After bleaching, the first color of the specimens was determined with a spectrophotometer according to the CIELAB color system (∆E). Following immersion in the staining solutions, the color was determined after 15 min, 6 h (second day), and 36 h (sixth day), and the color change values were calculated. The results were analyzed statistically by two-way analysis of variance (ANOVA) and Tukey's honest significant difference (HSD) test (P < 0.05). Results: The bleached specimens showed more staining than the unbleached specimens (control group). In all the groups, the staining was more severe in the cola solutions than in the tea solutions. There were no statistically differences in staining of the teeth in the control group (P > 0.05). In the specimens bleached with Smartbleach, staining in cola solution was greater than tea solution and this difference was statistically significant (P < 0.05). Conclusions: The staining of the bleached specimens was similar in the tea and cola solutions. The bleached specimens showed more staining than the unbleached specimens. The staining of the specimens in the tea and cola increased at all the time intervals evaluated.
Keywords: Bleaching, colour change, spectrophotometer
|How to cite this article:|
Karadas M, Tahan E, Demirbuga S, Seven N. Influence of tea and cola on tooth color after two in-office bleaching applications. J Res Dent 2014;2:83-7
|How to cite this URL:|
Karadas M, Tahan E, Demirbuga S, Seven N. Influence of tea and cola on tooth color after two in-office bleaching applications. J Res Dent [serial online] 2014 [cited 2020 May 28];2:83-7. Available from: http://www.jresdent.org/text.asp?2014/2/2/83/136643
| Introduction|| |
Cosmetic dentistry has become a significant part of restorative dental treatment. Having whiter and aesthetically pleasing teeth is very important to patients and is often related to the perception of health and fineness. Thus, cosmetic systems have become more desirable as standards of living have developed,  and vital tooth bleaching is rapidly gaining popularity with patients and dentists as a conservative technique to lighten natural teeth.  Bleaching treatments can be administered in-office by dentists using agents containing high concentrations of hydrogen peroxide or carbamide peroxide. They can also be applied in the home by the patient, under the direction of the dentist, using a less concentrated hydrogen peroxide or carbamide peroxide solution. 
There are several in-office techniques for bleaching vital teeth, all based on the use of concentrated hydrogen or carbamide peroxide solution, in order to provide faster and more effective treatment.  For this purpose, some use heat and light to catalyze or speed up the reaction, whereas others do not. A main advantage of using a light source is that it assists in the release of the free radicals in the bleaching agent for a faster bleaching procedure.  The disadvantage of this method is that it increases tooth sensitivity because the use of light and heat sources leads to a higher pulpal temperature. As noted elsewhere, dentists should consider pulp health before rendering office bleaching with light sources on vital teeth. 
The exposure of tooth surfaces to bleaching agents has been shown to sometimes result in microstructural changes in the enamel surface.  Using scanning electron microscopy evaluation, one study found demineralization, surface defects, and degradation of sound enamel.  Other studies found that these alterations may facilitate the recurrence of extrinsic staining  and that there may be a loss of organic components from bleached enamel and dentin surfaces.  Studies have also revealed that changes in the microstructure of teeth may be partly due to the loss, or denaturing, of protein.  Coloring beverages, such as tea, cola and coffee, consumed during the period of a bleaching treatment may lead to staining of bleached and possibly more porous enamel structure.  Therefore, dentists advise patients to reduce the consumption of coffee and tea and to avoid smoking or any other habit that may stain the teeth. 
To the best of our knowledge, there have been no studies investigating the staining effect of tea and cola solutions on tooth color after office bleaching. Thus, this study was performed to investigate the staining effect of tea and cola after the application of in-office bleaching.
| Materials and methods|| |
This study was approved by Ethical Committee of the Atatürk University (200928803). Sixty extracted sound human maxillary central incisors were used within one month of extraction. Excessively dark or light teeth were not included. After extraction, the teeth were stored in 8% thymol solution. The roots were sectioned from the crowns at the dentinoenamel junction using a water-cooled diamond saw (Imptech PC10; Equilam Lab Equip, Diadema, Brazil). Using rectangle moulds, each specimen, with the labial surface exposed, was submerged separately in chemically cured acrylic resin, which allows light to pass through it. Then, the enamel surfaces were polished with a prophylaxis paste, using a polishing brush, and washed. The specimens were randomly divided into three groups (n = 20). Group A was the control group (no bleaching). In Group B, the specimens bleached with Opalescence Xtra Boost, and in Group C, they were bleached with Smartbleach. The groups were then divided into two subgroups according to the colorant solutions used (n = 10, tea and cola). Each bleaching agent was applied to the specimens according to the manufacturer's recommendations. The characteristics of the bleaching products are given in [Table 1].
Opalescence Xtra Boost, the mixture was prepared and a 0.5-1 mm layer of the mixture was applied immediately to the specimens, using a dispenser tip. After 15 min, the bleaching agent was removed from the specimens using cotton, and then rinsed. The procedure was repeated three times at the same sitting, and the process was repeated after 1 week. Smartbleach, 35% hydrogen peroxide gel was prepared shortly before use by mixing about 5 ml of peroxide with the buffering red powder. The gel mixture was applied to the specimen surface; then, using a karium-titanium-phosphoric (KTP) acid light (SmartLite; Deka, Firenze, Italy), each specimen was irradiated with 532 nm wavelength and 1 watt power for 30 s. The bleaching agent was removed after 10 min. This procedure was repeated three times at the same sitting, and the process was repeated after 2 weeks. After the bleaching treatments, the gels were carefully removed with sterile gauze and tap water. Between bleaching intervals, the specimens and control group were maintained in artificial saliva,  which was changed daily, at 37°C.
After bleaching, the specimens in the subgroups were immersed in tea (Yellow Tea, Lipton, Turkey) or cola (Coca-Cola, Turkey). The tea mixture was prepared by leaving a tea bag in 165 ml of boiling water for 5 min. The specimens were immersed in the tea and cola for 15 min on the first day and for 6 h on the second and subsequent days (six successive days). The specimens were removed from the solutions, washed with distilled water for 15 sec, and color measurements were performed. They were then immersed in artificial saliva for the remainder of the day. Staining solutions were renewed daily.
The first color of the specimens was measured by one experienced and qualified examiner using a spectrophotometer (Shadepilot; DeguDent GmbH, Hanau, Germany) after the bleaching. Specimens were washed with distilled water for 15 s after immersion. Immersion color measurements were performed after 15 min, 6 h (second day) and 36 h (sixth day). The color of each specimen was assessed according to the CIELAB color system with the spectrophotometer connected to a personal computer under standard conditions. Each prepared specimen was placed on the table. The suitable mouthpart of the spectrophotometer's camera was later placed at a 90° angle on the specimen surface, which was centered in the yellow target box represented on the computer monitor. The spectrophotometer was calibrated prior to measurement of each color with white and green ceramics provided by the manufacturer. The spectrophotometric documents of each specimen were saved by the same operator on the personal computer. All color measurements were taken three times at different places on the middle third of each specimen surface, using the built-in synchronized image program. The average of the three measurements was taken as the color of each specimen and used for overall document analysis.
In the CIELAB color system, L* represents the value (lightness or darkness), a* is a measure of redness (positive a*) or greenness (negative a*) and positive b* indicates a yellow direction, whereas negative b* indicates a blue direction. Total color differences between the two colors (∆E) were calculated using the following formula: ∆E* = [(∆L*) 2 + (∆a*) 2 + (∆b*) 2 ] 1/2 . When ∆E was 3.7 or less, it was considered clinically acceptable in the study. 
The distribution of the data was checked, and parametric tests were used for homogeneously distributed data. The average values of the color parameters (∆E) were compared using a two-way analysis of variance (ANOVA) and Tukey's honest significant difference (HSD) test (P < 0.05). Statistical analysis was performed using the Statistical Package for Social Sciences program (SPSS, version 16.0, Chicago, IL, USA).
| Results|| |
The mean values and the standard deviations of ∆ E are represented in [Table 2]. The bleached specimens showed more staining than the unbleached specimens (control group) in the tea and cola solutions at all the time intervals evaluated and staining in all the groups was increased. In all the groups, staining in cola solutions was greater than in the tea solutions, but there was no statistically significant difference in the staining between solutions in control group at any of the all time intervals evaluated (P > 0.05). There were no statistically significant differences in the staining between the specimens bleached with Opalescence Xtra Boost after 15 min (P = 0.99), whereas there was a statistically significant difference in the staining at the other time intervals evaluated (P = 0.001). In the specimens bleached with Smartbleach, there were statistically significant differences in staining between the staining solutions at all the time intervals evaluated (P < 0.05).
|Table 2: Mean ΔE and standard deviations (±SD) values for each groups in the solutions|
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Differences in the staining of the bleached and unbleached specimens in the tea solutions were not statistically significant at 15 min or 36 h, whereas the differences in the staining bleached and unbleached specimens in the cola solutions were statistically significant at all the time intervals evaluated. There were no statistically significant differences in the staining between the specimens bleached with Opalescence Xtra Boost and Smartbleach after immersed in the tea or cola at any of the time intervals evaluated. The staining of the specimens in the tea and cola increased at all the time intervals evaluated, and this increase was statistically significant for all groups.
After 15 min immersion in tea and cola solutions, color changes in the specimens were acceptable, with the exception of cola solution in Group C. ∆E values in the bleached specimens were greater than 3.7 after 6 and 36 h immersion. The changes in the L-values (∆L), in the a-values (∆a) and in the b-values (∆b) are depicted in [Figure 1], [Figure 2], [Figure 3], respectively. L values were decreased, whereas a and b values were increased.
|Figure 1: Mean ΔL values for each subgroups in the solutions. T: Tea; C: Cola|
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|Figure 2: Mean Δa values for each subgroups in the solutions. T: Tea; C: Cola|
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|Figure 3: Mean Δb values for each subgroups in the solutions. T: Tea; C: Cola|
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| Discussion|| |
The color change of the bleached teeth stained with tea and cola was evaluated using an objective method, a spectrophotometer. Spectrophotometers provide more reliable results than shade tabs and colorimeters. However, they are difficult to transport, expensive and affected by the tooth structure. In addition, it is difficult to ensure repeatable tooth repositioning, as shown in a previous study.  Changes in tooth color were measured one day after bleaching treatment to avoid the effects of dehydration.
The upper surface of the enamel, called prismless enamel, is of great clinical significance because it is the surface subjected to daily wear and undergoes repeated cycles of demineralization and remineralization.  In some previous studies. ,, SiC abrasive paper was used to flatten the upper surface layer of the enamel to provide a more uniform surface. As reported previously, this procedure will make the specimens more susceptible to staining because the aprismatic layer of the upper enamel surface is usually more highly mineralized than the subsurface and is more resistant to demineralization. 
A previous study observed extensive structural alterations in enamel when a hydrogen peroxide-containing whitening agent and preoperative etching and light irradiation were used.  Another study described morphological changes in the form of increased surface roughness and an etched-like appearance in dental surfaces in contact with highly concentrated peroxide gels.  Using scanning electron microscopy, Miranda et al.,  showed that in-office bleaching agents affected the structure of human enamel. Shannon et al.,  found that the most severe changes in enamel occurred with bleaching agents with a lower pH. Unbleached surfaces were more stain resistant than bleached surfaces. Cola had the lower pH and showed the higher ∆ E* value at all the time intervals evaluated after immersion.
Specimens were stored in artificial saliva throughout the experiment to simulate the remineralization. There is no consensus regarding whether microstructural defects can be repaired by remineralization.  However, it was found that peroxide-containing vital tooth bleaching agents altered enamel surfaces, despite the neutral pH of the agents, which produces a specific effect on enamel.  On the other hand, some studies have shown that the neutrality of bleaching agents plays a significant role in preventing roughening of the enamel surface. , In this study, the staining susceptibility increased after bleaching.
Park et al.,  reported that hydrogen peroxide specifically dissolves organic materials and minerals from teeth and makes the surface of the enamel soft and less compact, although this does not mean that the bleaching agent is unsafe for teeth. Bizhang et al.,  evaluated the mineral loss of bovine enamel after different bleaching treatments (10% carbamide peroxide, 5.3% hydrogen peroxide) or cola beverage (1 h/day) and reported significantly greater mineral loss with the cola beverage. In addition, some studies , have reported that highly pigmented acidic beverages cause both tooth discoloration and dissolution of hard tooth structures. In the present experiment, staining of the bleached specimens was greater in the control group, and the cola caused more staining than did the tea solution. The increased tooth discoloration in the bleached specimens compared with that of the control group might be explained by the dissolution of the tooth structure and acidic beverages causing tooth discoloration because low pH has been associated with increased enamel surface dissolution.  Thus, dentists should advise patients to avoid certain drinks, food containing artificial colorants and acidic beverages in particular to maintain the color stability of teeth after bleaching treatments.
Attin et al.,  examined the effects of tea on intrinsic coloration and reported that the application of tea after bleaching with 10% carbamide peroxide did not significantly affect the outcome of a bleaching treatment. In the present study, the staining in tea after bleaching was increased compared with that of the control group. Although some studies , evaluated the effect of red wine and coffee on teeth color during and after bleaching treatments, they did not examine the effect of tea and cola after bleaching. As reported previously, the color stability after bleaching is strongly linked to the dietary habits of patients.  The choice of materials and bleaching techniques should be based on factors, such as the patient's habits.
| Conclusion|| |
The staining of bleached specimens was almost similar in the tea and cola solutions. The bleached specimens showed more staining than the unbleached specimens. The staining of the specimens in the tea and cola was increased at all the time intervals evaluated. The staining in the cola solutions was greater than in the tea solutions.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]