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Table of Contents
Year : 2020  |  Volume : 4  |  Issue : 1  |  Page : 6-10

The effect of carbamide peroxide on surface enamel structural changes and streptococcus mutans attachment

1 Undergraduate Student, Faculty of Dentistry, Trisakti University, West Jakarta, Java, Indonesia
2 Department of Dental Material, Faculty of Dentistry, Trisakti University, West Jakarta, Java, Indonesia
3 Department of Microbiology, Faculty of Dentistry, Trisakti University, West Jakarta, Java, Indonesia

Date of Submission09-Sep-2019
Date of Acceptance09-Jan-2020
Date of Web Publication7-Feb-2020

Correspondence Address:
Dr. Deviyanti Pratiwi
Department of Dental Material, Faculty of Dentistry, Trisakti University, West Jakarta, Java
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/SDJ.SDJ_29_19

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Background: Home bleaching with carbamide peroxide is commonly used due to its high success rate and minimum side effects. Although home bleaching is safe, it causes structural changes in surface enamel, thereby facilitating Streptococcus mutans attachment on the enamel surface. Objectives: This study aimed to determine the effect of carbamide peroxide concentration on surface enamel structural changes and S. mutans attachment. Methods: Healthy, caries-free, and calculus-free upper first premolars were divided into 10%, 15%, and 35% carbamide peroxide concentration groups, with five samples in each group. Structural changes in the surface enamel of the teeth before and after the bleaching procedure were assessed subjectively based on observations using a stereomicroscope at × 40. The samples were inoculated in S. mutans culture and incubated for 24 h (37°C) in anaerobic conditions. The samples were then washed with phosphate-buffered saline, and bacterial attachment was released by vortexing for 1 min. Bacterial attachment was assessed using a turbidimetry test and total plate count test. Result: Structural changes in enamel were observed in the samples exposed to carbamide peroxide 35%. The results of an analysis of variance test revealed a significant difference (P < 0.05) in the bacterial attachment test. The samples exposed to carbamide peroxide 35% exhibited the highest amount of bacterial attachment (3 × 10[6] CFU/mL, optical density: 0.06). Conclusion: The concentration of carbamide peroxide plays a role in structural changes in enamel and S. mutans attachment.

Keywords: Carbamide peroxide, home bleaching, Streptococcus mutans attachment, structural changes in enamel

How to cite this article:
Anggakusuma KN, Pratiwi D, Widyarman AS. The effect of carbamide peroxide on surface enamel structural changes and streptococcus mutans attachment. Sci Dent J 2020;4:6-10

How to cite this URL:
Anggakusuma KN, Pratiwi D, Widyarman AS. The effect of carbamide peroxide on surface enamel structural changes and streptococcus mutans attachment. Sci Dent J [serial online] 2020 [cited 2023 Jun 4];4:6-10. Available from: https://www.scidentj.com/text.asp?2020/4/1/6/277874

  Background Top

Tooth discoloration is the main reason why patients undergo bleaching treatment. The principal ingredient in bleaching agents is hydrogen peroxide or carbamide peroxide.[1] Home bleaching with carbamide peroxide is commonly used because of its high success rate and minimum side effects.[2] Although home bleaching is safe, it has adverse effects such as inducing structural changes in tooth enamel.[3] These changes increase the roughness of the enamel surface, thereby facilitating Streptococcus mutans attachment, the main bacterium responsible for dental caries.[4]S. mutans has the ability to metabolize carbohydrates or sugars into glucan, facilitate the attachment of other cariogenic bacteria, and produce acid. As a result, the acidity of the oral environment drops to pH 5.5, and tooth demineralization occurs.[5]

In home bleaching, individual trays are used; thus, the agent remains in contact with the teeth for a period of time.[6],[7] Carbamide peroxide contains two main ingredients: urea and hydrogen peroxide. Urea is used to stabilize the agent, and hydrogen peroxide produces free radicals called perhydroxyls, which oxidize the tooth, leading to tooth whitening.[8] The duration of carbamide peroxide use depends on the concentration of the substance. Carbamide peroxide 10% is used for 8 h a day, whereas carbamide peroxide with concentrations of 15%–20% and 35%–37% are used for 3–4 h and 15 min a day, respectively.[9] Besides carbamide peroxide, bleaching agents contain other ingredients, such as carbopol, a slow-release oxygen agent, as well as a flavoring agent, desensitizer (potassium nitrate), and fluoride, which have antimicrobial and anticariogenic effects.[10],[11],[12]

Previous research showed that the oxidation ingredient in bleaching agent was associated with structural changes in tooth enamel because of tooth demineralization.[13],[14] Such structural changes in tooth morphology facilitate bacterial attachment to the enamel surface and lead to biofilm formation.[15],[16] The aim of the present study is to investigate the effect of different concentrations of carbamide peroxide on structural changes in the enamel surface and S. mutans attachment.

  Materials and Methods Top

Sample preparation

Healthy, caries-free, and calculus-free upper first premolars were used in this study. The teeth were cut until the cervical edge, and the cut surface was pained with red nail polish. The samples were then placed in modeling wax with the buccal surface facing upward. Before stereomicroscopic observations, the samples were washed under running water and dried. The buccal surface of each sample was then observed at × 40.

The samples were divided into four groups, with each group containing five samples. Group 1 was a negative control, Group 2 was treated with 10% carbamide peroxide for 8 h, Group 3 was treated with 15% carbamide peroxide for 4 h, and Group 4 was treated with 35% carbamide peroxide for 15 min. After the respective treatments, the samples were rinsed in running water and dried. The procedure was repeated each day for 2 weeks without brushing the teeth. Subsequently, the buccal surfaces of the samples were observed under a stereomicroscope at × 40. The samples were then autoclaved for 15 min, and bacterial attachment was assessed.

Bacterial cultured and bacterial attachment test

S. mutans was cultured in 35 ml of liquid brain–heart infusion broth media for 24 h at 37°C under anaerobic conditions. S. mutans was diluted according to a 0.5 McFarland standard (optical density [OD] 0.1) by a turbidity test. The teeth samples were inserted into a 24-well plate according to its group. The S. mutans suspension (1.5 ml) was then added to each well plate and incubated for 24 h at 37°C. Subsequently, the samples were rinsed with phosphate-buffered saline (PBS) and transferred to a microtube containing 1 ml of sterile PBS. The samples were then vortexed for 30 s to dislodge S. mutans attached to the samples.

Turbidity test and total plate count test

S. mutans number after vortexed was calculated using turbidity test method using a microplate reader (Safas, Monaco). 200 μl bacterial solution was added to 96-well microplate, and the wavelength was 600 nm.[17] After turbidimetry, S. mutans was diluted to 10−2, and 10 μl of the suspension was removed and added to brain–heart infusion agar medium in a  Petri dish More Details. The suspension was flattened using a spreader and incubated for 24 h at 37°C after incubation; the number of S. mutans colonies was counted using the total plate count (TPC) test.

  Results Top

Results showed that there were structural changes in the buccal surfaces of the samples [Table 1]. The results of observation using the stereomicroscope revealed structural changes (i.e., scratches) on the surface enamel of the samples in Groups 2, 3, and 4. However, in Group 4, they have more scratches observed compared to the other groups.
Table 1: Buccal surfaces of the samples

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The S. mutans number was increased in accordance with the scratches level of each group. The results of turbidimetry and TPC test are shown in [Figure 1] and [Figure 2]. A one-way analysis of variance test revealed a significant difference on treatment group compared to the control group on turbidity test (P = 0.04) and TPC test (P = 0.00). Based on the turbidimetry and TPC test results, high numbers of S. mutans were attached to the samples in Group 4 (35% carbamide peroxide treatment).
Figure 1: Streptococcus mutans attachment on enamel surface using turbidity test (optical density)

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Figure 2: Streptococcus mutans attachment on enamel surface using total plate count method (CFU/ml)

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  Discussion Top

Home bleaching is a common practice. In home bleaching, a low concentration of carbamide peroxide is applied to the teeth using a customized tray every night for at least 2 weeks.[18] Previous research described the effectiveness of home bleaching techniques using 10% carbamide peroxide.[9] Many manufacturers have introduced higher concentrations of carbamide peroxide, which is recommended to be used for shorter periods.

Dental practitioners have to consider two aspects in relation to bleaching agents: effectiveness of the agent and side effects. According to some clinical studies, the most common side effect of tooth bleaching was tooth sensitivity.[19] Bruzell et al. reported that the higher the bleaching agent concentration, the higher the risk of tooth sensitivity caused by changes in the enamel surface.[20] They compared side effects among patients using home bleaching (10% and 20% carbamide peroxide) agents and in-office bleaching (25% and 35% hydrogen peroxide). In their study, 50.3% of the patients using the home bleaching agent and 39.3% of the patients using in-office bleaching complained of sensitive teeth.

Previous research by Goldberg et al. confirmed the presence of structural changes in surface enamel caused by tooth bleaching.[21] In their review study, bleaching led to supragingival and subgingival plaque formation, and S. mutans attachment increased on the enamel surface. In the present study, structural changes in the enamel surface of the teeth were most obvious in the samples treated with carbamide peroxide 35% as compared with those in the other groups (i.e., 10% and 15% carbamide peroxide). The findings of this study are in agreement with those of de Geus et al., who reviewed 17 related studies and concluded that side effects, such as structural changes in surface enamel of teeth, were caused using a higher concentration of carbamide peroxide.[22] However, the findings are not in accordance with those of other research. Using scanning electron microscope and noncontact profilometry, Cadenaro et al. assessed the morphology and surface enamel roughness of the teeth treated with 38% hydrogen peroxide and 35% carbamide peroxide for 4 weeks.[23] Machado et al. evaluated the surface roughness of tooth enamel following treatment with carbamide peroxide 10% and hydrogen peroxide 38% using a scanning electron microscope and an optical interferometer. Neither study detected structural or morphological changes in surface enamel after the carbamide peroxide treatments.[24]

In the present study, the turbidimetry results and those of the TPC test revealed high numbers of S. mutans attached to the surface of the teeth treated with carbamide peroxide. High numbers of S. mutans were detected on the surface of the teeth treated with carbamide peroxide 35%, (3,034,000 CFU/ml, OD: 0.06). This result showed that carbamide peroxide altered the structure of the enamel surface and that increased surface roughness facilitated S. mutans attachment. The findings on bacterial attachment were in agreement with those of Gursoy et al., who compared plaque accumulation on bleached tooth surfaces and unbleached tooth surfaces.[25] They were also in accordance with those of a study by Al-Jubori et al., who compared the number of S. mutans colonies on teeth bleached with 7.5% hydrogen peroxide and 16% carbamide peroxide as compared with the number on unbleached tooth. These structural changes (i.e., increased surface roughness) may play an important role in S. mutans attachment on surface enamel.[26]

  Conclusion Top

Carbamide peroxide induced structural changes in surface enamel of teeth, with a higher concentration of carbamide peroxide associated with greater changes in terms of surface roughness. Increased surface roughness facilitated the S. mutans attachment. A further study is still needed to confirm with the other oral bacteria.

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Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Figure 1], [Figure 2]

  [Table 1]

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