Effect of over-the-counter teeth whitening products available on an e-market portal: an in-vitro study

doi:10.21203/rs.3.rs-4018969/v1

Objectives: This study aimed to compile and evaluate over-the-counter (OTC) toothwhitening products from a prominent e-marketplace, assessing their bleaching effectiveness and impact on enamel.

Methodology: Thirty-eight intact tooth sections were randomly divided into three groups: Group I, the positive control, was treated with a dentist-prescribed bleaching agent (DPA) (Opalescence, Ultradent, USA); Groups II and III were treated with the lowest-rated (LRA) and highest-rated (HRA) e-market bleaching agents, respectively. Ten samples per group were subjected to spectrophotometric analysis for bleaching efficacy, ten for postbleaching microhardness, and two per group for morphological evaluation through scanning electron microscopy (SEM). Statistical analyses included one-way ANOVA, post hoc tests, and Student’s t tests, maintaining a significance level of P <0.05.

Results: The e-commerce search revealed 15 e-market products out of which most of them lacked usage instructions and comprehensive composition information. DPA exhibited superior tooth whitening, in contrast with the poorly rated online agent, which showed asignificantly lower degree of color change (P=0.007). Microhardness was significantly lower in the LRA treatment group (14.2%) than in the control and HRA treatment groups (8.84% and 7.26%, respectively) (P >0.05). Furthermore, LRA caused severe topographical alterations to the enamel.

Conclusion: e-portal OTC teeth whitening products lackvital information, while dentist-prescribed products outperform LRA products in terms of efficacy and enamel preservation.

Clinical relevance: Patients’ inclination toward easily accessible online products, particularly from platforms such asAmazon, may result in overuse and consequential deleterious effects on dental tissues.

Whitening

Online portal

Enamel

Tooth bleaching

Microhardness

The color of one's teeth has been demonstrated to be a significant factor influencing an individual’s happiness and self-esteem [1]. The discoloration of teeth is one of the chief complaints expressed by many patients. Because of the growing need for better dental aesthetics, whitening products have been developed, that provide a noninvasive alternative for better tooth coloration [2]. Tooth-whitening products usually include chemicals that can disintegrate chromogens. However, these chemical agents can affect the mechanical and physical characteristics of dental hard tissues [1]. These bleaching agents can be dentist-applied, dentist-prescribed or "over the counter" (OTC) products [2, 3]. Due to the ease of purchase and lower cost, the use of these OTC bleaching agents in the form of gels, paints, and strips has become popular. The main concern with these OTC products is their use without professional diagnosis or recommendation and even overuse or abuse of these products [1].

Apart from drugstores and supermarkets, these OTC tooth whitening agents are available online through various e-Market websites. Few studies have been found in the literature regarding the products available or safety concerns. It has been shown that favorable online ratings are related to higher sales and bad reviews are associated with lower sales of experiential products such as books and movies [4]. As a result, some people attempt to manipulate or post phony reviews to sway buyers. Customers can have better knowledge of the product or service they wish to purchase by reading online reviews. Ease ordering, false advertisements, and dependence on ratings to buy these e-portal "over the counter" (OTC) bleaching products can result in the abusive use of teeth whitening agents [5].

Therefore, the purpose of this study was to determine the characteristics of the bleaching agents available in a prominent e-marketplace. This study also aimed to determine the effectiveness of bleaching as well as its impact on dental qualities, particularly hardness, a predictor of enamel mineral content loss, and topographical changes in OTC bleaching agents available online and selected based on customer ratings.

Study approval and design

This in-vitro study commenced after ethical approval was obtained from the Institutional Ethics Committee (IEC reference number: 22091)

Sample size

Based on the key article by Al-Angari et al. [6], the expected standard deviation was 3.7. With an alpha error of 1%, a power of 95%, and maintaining an effective difference to demonstrate a clinically significant difference of 5, the number of samples required in each group was calculated to be ten.

Selection of the experimental bleaching agents

A comprehensive internet search was undertaken to identify teeth whitening products available on a popular e-portal (amazon.com). The investigation employed specific keywords, including gels, strips, light-activating products, and teeth whitening, on an e-commerce platform. Information was meticulously collected and cataloged, encompassing particulars such as product name/brand, manufacturer, formulation, indications, pricing, and supplementary data such as customer ratings and reviews [7].The search was performed on November 2, 2023.

Web scraping tools such as Instant Data Scraper and Web Automation (www.webautomation.io) were employed to conduct an extensive data collection process, which included resolving duplicate and kit entries for a total of 134 products. By combining data from both scraping methodsa list of 20 products was curated [8]. Bleaching agents with zero reviews were eliminated. In the case of duplicate products with varying reviews, the one with the highest rating was selected [9] resulting in a dataset consisting of 15 distinct products. Additional information on the product form, primary ingredients, ratings, usage instructions, and stamp of approvals were manually added (Table 1). Finally, the ratings for each product were calculated using the below mentioned formula that utilized customer evaluations and ratings [10]:

[N is the total number of reviews for product x, Review Rating denotes the overall assessment given for the product on Amazon and ThumbUp represents the count of ratings falling within the three to five-star range].

The tooth bleaching agent with the lowest rating (LRA) and the highest rating (HRA) was selected for this study.

Sample selection and storage

Teeth that exhibited any visible cracks, staining, decay, demineralization, enamel imperfections, fluorosis, hypoplastic defects, or dental restorations were excluded from the study. A total of thirty-eight freshly extracted, intact anterior human teeth were stored at room temperature in distilled water solution in preparation for the testing phase.

Sample Preparation

The roots of the teeth were sectioned 2 mm apical to the cemento-enamel junction using diamond discs (Frank Dental, Germany). The coronal portion of the teeth was embedded in acrylic, with the buccal surface facing outward. Next, a 400-grit silicon carbide abrasive paper was employed for grinding, followed by the use of 600 and 1200-grit aluminum oxide papers for polishing to achieve a circular area measuring 5 mm in diameter.

Staining procedure

The samples were artificially stained through the preparation of a coffee extract solution, which was generated by dissolving 5.5 grams of instant coffee powder (Bru instant coffee powder, India) in 80 ml of boiling water at 100°C [11]. Subsequently, the samples were immersed in a coffee solution and subjected to ultrasonication to attain a shade matching A3 or higher, as per the Vita classical shade guide arranged in a value-based format.

Grouping

The groups studied were as follows;

Group I: Positive control group – Dentist-prescribed at-home bleaching agent (20% carbamide peroxide, Opalescence, Ultradent, USA) (DPA) containing carbamide peroxide with potassium nitrate and fluoride.

The bleaching agent was applied to the tooth surface, achieving a thickness ranging between 1 and 2 millimeters. This formulation was left in situ for a duration of four hours, adhering to a regimen extending over the course of one week.

Group II: Experimental group– lowest rated bleaching agent in the digital e-market (LRA)

The liquid solution was meticulously applied to the tooth surface utilizing a cotton swab as the dispensing medium. This solution was left undisturbed for a period of twenty minutes, and was carried out at a frequency of 3 times over a period of one week, as mentioned in the usage instructions of the product.

Group III: Experimental group– Highest-rated bleaching agent in the digital e-market (HRA)

Affixation of a strip onto the tooth surface, wherein it remained for a duration of one hour per day. This process was for fourteen treatments over one week, as per the instructions for the whitening strips.

All the samples before and after the bleaching step were stored in distilled water.

Color measurement

The tooth shade analysis involved recording the shade of thirty anterior teeth (10 in each group) using a hand-held digital spectrophotometer (VITA Easyshade V, VITA Zahnfabrik H. Rauter GmbH & Co. KG, Germany) in VITA classical A1–D4 shade mode. The measurement focused on the middle-third of the labial surface of the anterior maxillary teeth, following the guidelines of the American Dental Association (ADA) [12]. The shade of the tooth was represented as a shade guide unit (SGU) based on the value-based arrangement of the Vita Classical scale, where the 16 tabs of the shade guide were arranged from the highest (B1) to the lowest (C4) value [13]. Although this scale is not strictly linear, for the purpose of analysis, it was considered as continuous and approximately linear in ranking. The SGU was measured pre-bleaching and post-bleaching, and the overall shade change was represented as ΔSGU.

Microhardness measurements

The Vickers hardness number (VHN) for each pellet was evaluated using a surface microhardness tester (Shimatzu HMV-2000, Germany). Vickers hardness measurements were taken for each test specimen at three different locations, applying a 25-gram load for 20 seconds. The average of the three measurements was considered [14].

Scanning electron microscopy (SEM)

The enamel surface topography was assessed on two samples not subjected to bleaching and on two samples from each group one week after bleaching. The micro topographical evaluation was performed using scanning electron microscopy (SEM) with a Carl Zeiss Model Number – EVO18 Special Edition (Carl Zeiss, Cambridge, UK) after sputtering.

pH evaluation

The pH of the bleaching agents was assessed using a digital pH meter (Manti Lab Solutions Panchkula, India). Before measurement, each bleaching agent underwent dilution in distilled water to ensure uniformity. Measurements were conducted in triplicate for each bleaching agent, and the average pH value was considered.

Statistical Analysis

The data were tabulated and analyzed using statistical software (SPSS Version 20, IL, USA). Intergroup comparisons of shade and microhardness were assessed through one-way ANOVA with subsequent Tukey's post hoc test for HSD. Intragroup comparisons of pre and postbleaching shade and microhardness were evaluated using paired t-tests. A statistical significance level of P <0.05 was applied.

Bleaching products in e-portal

A comprehensive search of the Amazon e-portal for teeth whitening products was performed, resulting in a list of approximately 3000 products. Of these products, based on inclusion and exclusion criteria, the products were narrowed down to 15 with Amazon ratings ranging from 2.3 to 4.3 out of 5 and prices ranging from Rs 254 (approximately US$3) to Rs 2782 (approximately US$33.48). These included 5 gels, 6 strips, 3 liquids, and 1 mousse.

Out of the 15 products, 13 were accompanied by comprehensive usage instructions ensuring clarity in their application. Additionally, 6 of these products displayed a discernible distinction by featuring a stamp of approval. Based on the criteria and formula outlined in the methodology section, the best and worst products were identified. The top-performing product, with a rating of 2.06, was a strip. Conversely, the least satisfying product, with a rating of 0.67, was a liquid (Table 1).

Alterations in shade

According to the analysis of prebleaching and postbleaching shade changes, significant changes were observed within the three designated groups (Group I, Group II, and Group III) (Table 2). The maximum change in shade (ΔSGU) was identified in Group I, indicating the most noticeable shift in shade postbleaching. Conversely, the group with the least observed shade alteration was Group II, indicating a relatively minimal color change. A statistically significant difference was seen in Group I (8.9 ± 3.64) and Group II (3.8 ± 3.12) (Table 3). The P-value was 0.007.

Alterations in microhardness

A substantial intragroup difference was observed in Groups I and II, revealing significant alterations in postbleaching microhardness (P= 0.014). However, in Group III, the decrease in postbleaching microhardness did not reach statistical significance (P= 0.001) (Table 2).

The overall difference in microhardness was most pronounced in Group II, with the least difference occurring in Group I. Similarly, Group II had the highest percentage difference values, while Group III had the lowest. However, these changes did not reach statistical significance (Table 4).

Alterations in enamel surface morphology

Scanning electron microscopy (SEM) evaluation of the enamel surfaces revealed morphological changes in all the samples after bleaching. SEM can provide a 2D view of the enamel surface. (Fig. 1 a-d) SEM analysis of the prebleaching samples (magnification= 10³x) revealed that they exhibited smoother surfaces but also a few discolored and uneven areas (Fig. 1a). In the control group, 20% CP was utilized, which was subjected to SEM and demonstrated mild pitting along with mild surface irregularities on the enamel surface (Fig. 1b). In Group II, the least-rated product, SEM demonstrated severe pitting on the enamel surface (Fig. 1c). The Group III best-rated online product demonstrated a smooth enamel surface (Fig. 1d).

pH

The pH evaluation of the bleaching agents was conducted using a digital pH meter, revealing noticeable differences among all three products. In the control group, after triple measurements, the average pH was noted to be 7.21, while for the highest-rated product (HRA) and lowest-rated product (LRA), it was 7.44 and 4.11, respectively

Tooth bleaching has gained popularity in recent years as a convenient, noninvasive, and cost-effective solution for fulfilling the aesthetic desires of patients, granting them confidence in a brighter and more attractive smile [15].The surge in demand for tooth bleaching treatments in recent years mirrors the growing emphasis on enhancing dental aesthetics and ensuring patient satisfaction. This evolving trend has prompted our study, aimed at evaluating the effectiveness and safety of various tooth bleaching agents available in the e-market.

The decision to focus the study on teeth whitening products available in Amazon, India, was driven by careful consideration. With its substantial reach and influence among the Indian populace, Amazon India, stands out for its expansive product inventory, competitive pricing, and user-friendly shopping interface, dominating the Indian market [16]. The platform grants customers the capability to thoroughly compare products, access and assess customer feedback and reviews, and identify cost-efficient offerings. Moreover, Amazon India is distinguished by its commitment to transparent return policies, verified product authenticity, and a spectrum of flexible delivery options, collectively enhancing its reputation for reliability and convenience. These attributes make Amazon India an optimal choice for sourcing teeth whitening products, ensuring comprehensive and representative selection for our research study.

Using Amazon, comprehensive data collection was conducted for tooth whitening products via a multistep approach. Web data scraping, a well-established method for extracting online content, displays its continued relevance and versatility in various bioinformatics applications. It serves as a fundamental data retrieval tool and supports advanced online meta-servers, offering valuable services in the field of bioinformatics [17]. As a result, this method was employed to refine the product list.

The ratings for the products were derived from the formula mentioned in the article by Sarkar and Ahmad [10] to select the best and worst products. The best-rated product was a strip, and the worst-rated product was in liquid form. The control group was treated with 20% carbamide peroxide solution. This selection was made due to the widespread utilization and prescription of carbamide peroxide by dental professionals [18,19].The prepared enamel samples randomly allocated to the three groups were immersed and stored in distilled water to safeguard against potential dehydration, before and after the bleaching process. In the present study, artificial saliva was not utilized because it can interfere with the effects of the bleaching agent used [20]. Therefore, to eliminate confounding factors and to understand the effect of the tooth whitening agent exclusively on enamel, the samples were stored in deionized water.

Shade parameters, including shade guidance units (SGUs) and shade change (ΔSGU), were recorded. Teeth shade was measured using a VITA Easyshade V with few research studies demonstrating the consistent and precise color measurement capabilities of the device. This is evidenced by its reliable assessment of tooth shades in various contexts [21,22]. In the present work, significant changes in prebleaching and postbleaching shade were observed within the three designated groups. The maximum shade change (ΔSGU) value, indicating the most noticeable shift in shade postbleaching, was identified in Group I, the control group, attributed to the potent oxidizing properties of carbamide peroxide, which comprises urea and hydrogen peroxide. These properties enable the effective breakdown of discoloration-causing molecules [23]. Conversely, Group II, the worst-rated product, exhibited a relatively minimal ΔSGU value, possibly due to the absence of peroxides in its composition. Intergroup comparison revealed significant differences between Group I and Group II.

The Vickers hardness number (VHN) for each sample was evaluated using a surface microhardness tester. This method evaluates tooth structure hardness, offering insight into the mineral content and tissue integrity, including enamel and dentin. The concentration, application time, and content of the bleaching agent have been shown to affect the microhardness [14].The overall difference in microhardness was most pronounced in Group II, which was the worst-rated group. This difference may be attributed to the lack of clarity in the composition of the product, the presence of elements such as hydrogenated castor oil, or the pH of the product as shown in the study. Conversely, the smallest difference was observed in group I, which was the control group. Similarly, Group II had the highest percentage difference values, while Group III had the lowest. However, these changes did not reach statistical significance.

Topographical changes in the enamel were observed through scanning electron microscopy (SEM), which is commonly used to assess the effects of bleaching agents on dental hard tissue surfaces [24,25].A qualitative evaluation of the scanning electron microscopy image in Figure 1a of a prebleached sample revealed smoother surfaces but also a few discolored and uneven areas. The blotched areas in the SEM images could be due to the debris that accumulated during polishing and was not removed because the surfaces of the samples were not treated with any chemicals. After bleaching, in the control group, Figure 1b revealed intermittent depressions along with mild surface irregularities on the enamel surface. White et al. concluded that the application of 20% carbamide peroxide for bleaching did not result in significant alterations in the microstructural surface of enamel. indicating minimal changes in the ultrastructural surface of the enamel [26]. Conversely, the sample bleached with the worst-rated product, as shown in Figure 1c, exhibited severe pitting. This could be attributed to the unclear composition and pH as shown that caused these outcomes. Figure 1d shows a smooth surface of the enamel, likely influenced by the presence of a low concentration of hydrogen peroxide in the strips of the best-rated product.

This study's limitations include using only one e-commerce platform for product selection, which may limit generalizability. Additionally, incomplete product composition data may have interfered with the precise interpretation of the results. Furthermore, as this was an in vitro study, it did not consider the dynamic oral environment, such as the influence of saliva, oral microflora, and temperature on the effects of bleaching agents on tooth substrates.

Within the limitations of the present study, the following conclusion can be drawn:

The teeth whitening products accessible through the e-market portal lacked detailed information about their formulation and proper usage. This could be a concern because it could impact product safety and reliability.
The dentist-prescribed product tested proved more effective at tooth whitening than the poorly rated online tooth whitening agent.
The reduction in enamel microhardness after bleaching was greatest for the lowest-rated online tooth whitening agent.
Surface morphological changes, as observed through SEM, were most prominent in the case of the poorly rated whitening agent and least pronounced when the highest-rated agent available online was used.

Conflict of interest: The authors declare no conflicts of interest.

Ethics Approval and Consent to Participate: Ethical clearance to conduct the study was obtained from the Institutional Ethics Committee (Protocol Ref No: 22091) to conduct this in-vitro study.

Funding: Partially funded by the Indian Dental Association- Dakshina Kannada Branch as Student Research Grant, 2022-23.

Data availability statement: The datasets supporting the findings of this study are not publicly accessible; however, those interested may obtain them by contacting the corresponding author [M.S.T,] upon request.

AUTHOR CONTRIBUTIONS

R.A., N.P., M.S.T, and S.N. made substantial contributions to the conception or design of the work;

R.A., N.V., U.S.M., A.S., and S.N. carried out experimentation and figure preparation;

R.A., N.V., and M.S.T contributed to the literature search and preparation of the initial manuscript draft;

U.S.M., N.P., and S.N. thoroughly reviewed and contributed to the final draft.

All the authors approved the version to be published and agreed to be accountable for all the aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work were appropriately investigated and resolved.

Naidu AS, Bennani V, Brunton JMAP et al (2020) Over-the-Counter Tooth Whitening Agents: A Review of Literature. Braz Dent J 31:221–235. https://doi.org/10.1590/0103-6440202003227
Santana Jorge O, Noronha Ferraz de Arruda C, Tonani Torrieri R et al (2022) Over-the-counter bleaching agents can help with tooth whitening maintenance. J Esthet Restor Dent 34:328–334. https://doi.org/10.1111/jerd.12617
Bakul JS (2016). An overview of vital teeth bleaching. J Interdiscipl Dent 6:3-13. https://doi.org/10.4103/2229-5194.188155
Hendrawan RA, Suryani E, Oktavia R (2017) Evaluation of E-Commerce Product Reviews Based on Structural, Metadata, and Readability Characteristics. Procedia Computer Science 124:280-286. https://doi.org/10.1016/j.procs.2017.12.157
Dantas AA, Bortolatto JF, Roncolato Á et al (2015) Can a bleaching toothpaste containing Blue Covarine demonstrate the same bleaching as conventional techniques? An in vitro, randomized and blinded study. J Appl Oral Sci 23:609–613. https://doi.org/10.1590/1678-775720150268
Al-Angari SS, Eckert GJ, Sabrah AHA (2021) Color stability, Roughness, and Microhardness of Enamel and Composites Submitted to Staining/Bleaching Cycles. Saudi Dent J 33:215-221. https://doi.org/10.1016/j.sdentj.2020.08.003
Askalidis G, Malthouse EC (2016) The Value of Online Customer Reviews. In Proceedings of the 10th ACM Conference on Recommender Systems (RecSys '16). Association for Computing Machinery, New York, NY, USA, 155–158. https://doi.org/10.1145/2959100.2959181
Web scrapping- https://www.webautomation.io/account/lgi/?next=/account/start/t/. Accessed July 2023
Amazon India- teeth whitening agents list. https://www.amazon.in/s?k=teeth+whitening+products&i=hpc&rh=n%3A1374640031%2Cp_n_feature_browse-bin%3A28289533031%7C28289534031%7C2828953803. Accessed in June 2023
Sarkar AR., Ahmad S (2021) A new approach to expert reviewer detection and product rating derivation from online experiential product reviews. Heliyon, 7: e07409. https://doi.org/10.1016/j.heliyon.2021.e07409
Bazzi JZ, Bindo MJ, Rached RN et al (2012) The effect of at-home bleaching and toothbrushing on removal of coffee and cigarette smoke stains and color stability of enamel. J Am Dent Assoc 143:e1–e7. https://doi.org/10.14219/jada.archive.2012.0188
Browning WD (2003) Use of shade guides for color measurement in tooth-bleaching studies. J Esthet Restor Dent 15:S13–S20. https://doi.org/10.1111/j.1708-8240.2003.tb00314.x
Chemin K, Rezende M, Loguercio AD et al (2018) Effectiveness of and Dental Sensitivity to At-home Bleaching With 4% and 10% Hydrogen Peroxide: A Randomized, Triple-blind Clinical Trial. Oper Dent 43: 232–240. https://doi.org/10.2341/16-260-C
Roopa KB, Basappa N, Prabhakar AR et al (2016) Effect of whitening dentifrice on micro hardness, colour stability and surface roughness of aesthetic restorative materials. J Clin Diagn Res 10:ZC06–ZC11. https://doi.org/10.7860/JCDR/2016/15700.7350
Kolsuz Ozcetin H, Surmelioglu D (2020) Effects of bleaching gel containing TiO₂ and chitosan on tooth surface roughness, microhardness and colour. Aust Dent J 65:269–277. https://doi.org/10.1111/adj.12786
Wadhwa B, Vashisht A, Sohi D (2017) Business model of Amazon India – a case study. Int J Adv Res 5:1426-1433. http://dx.doi.org/10.21474/IJAR01/5200
Glez-Peña D, Lourenço A, López-Fernández H, et al (2014) Web scraping technologies in an API world. Brief Bioinform 15:788–797. https://doi.org/10.1093/bib/bbt026
Alqahtani MQ (2014) Tooth-bleaching procedures and their controversial effects: A literature review. Saudi Dent J 26: 33-46. doi:10.1016/j.sdentj.2014.02.002
Favaro JC, Geha O, Guiraldo RD et al (2019) Evaluation of the effects of whitening mouth rinses combined with conventional tooth bleaching treatments. Restor Dent Endod 44:e6. https://doi.org/10.5395/rde.2019.44.e6
Zekonis R, Matis BA, Cochran MA et al (2003) Clinical evaluation of in-office and at-home bleaching treatments. Oper Dent 28:114–121.
Klotz AL, Habibi Y, Hassel AJ et al (2020) How reliable and accurate is the shade determination of premolars by spectrophotometry?. Clin Oral Investig 24:1439–1444. https://doi.org/10.1007/s00784-019-03162-x
Klotz AL, Habibi Y, Corcodel N et al (2022) Laboratory and clinical reliability of two spectrophotometers. J Esthet Restor Dent 34:, 369–373. https://doi.org/10.1111/jerd.12452
Okonogi S, Kaewpinta A, Rades T et al (2020) Enhancing Stability and Tooth Bleaching Activity of Carbamide Peroxide by Electrospun Nanofibrous Film. Pharmaceuticals (Basel) 13:381. https://doi.org/10.3390/ph13110381
Jacob SE, Varghese JO, Singh S et al (2023) Effect of bleaching on color and surface topography of teeth with enamel caries treated with resin infiltration (ICON^®) and remineralization (casein phosphopeptide-amorphous calcium phosphate). J Conserv Dent Endod 26:377–382. https://doi.org/10.4103/jcd.jcd_129_23
Karimi Z, Saoui H, Sakout M et al (2021). Effect of Vital Bleaching on Micromorphology of Enamel Surface: an in Vitro Study. Prim Dent J 10:126–131. https://doi.org/10.1177/2050168420980966
White DJ, Kozak KM, Zoladz JR et al (2002) Peroxide interactions with hard tissues: effects on surface hardness and surface/subsurface ultrastructural properties. Compend Contin Educ Dent 23:42–50.

Table 1: List of over-the-counter teeth whitening products available on an e-portal obtained via web scraping

Description	Form	No. of ratings	Amazon rating	Rating from the formula	Price (in rupees)	Primary ingredient	Instruction of use	Stamp of approval
Perfora Teeth Whitening Pen Peroxide Free	Gel	357	4.1 out of 5 stars	1.84	499	Phthalimidoperoxycaproic Acid(PAP) Nano Hydroxyapatite	Present	Present
Daybreak Teeth Whitening Pen	Gel	46	3.7 out of 5 stars	1.5	479	PAP, Hydroxyapatite	Present	Absent
Daybreak Teeth Whitening Strips	Strip	43	3.8 out of 5 stars	1.6	1,099	PAP, Hydroxyapatite	Present	Absent
Protouch Pearl White Teeth Whitening Pen	Gel	795	3.3 out of 5 stars	1.3	549	Citrus Lemon Peel Extract, Turmeric Root Extract, Spearmint Leaf Oil,other details N.A.	Present	Present
Teeth Whitening Serum Gel	Liquid	51	2.3 out of 5 stars	0.67	499	Teeth Whitening Serum, other details N.A.	Present	Absent
Teeth-a-bit Teeth Whitening Snow White Gel	Gel	29	3.7 out of 5 stars	1.5	498	Papain (Carica Papaya), Bromelain (Ananas comosus)	Present	Present
Agaro Dazzle Instant Teeth Whitening Strips	Strip	14	3.9 out of 5 stars	1.78	1,389	Mint, other details N.A.	Present	Absent
Bonayu Teeth Whitening Strips	Strip	78	2.9 out of 5 stars	1.16	350	Activated Charcoal, Coconut oil, other details N.A.	Present	Present
Lanbena Teeth Whitening Essence Serum	Liquid	133	3.4 out of 5 stars	1.38	685	Hydrated Silica, other details N.A.	Present	Absent
Techworld Portable Advanced Professional Teeth Whitening Strips	Strip	13	3.6 out of 5 stars	1.64	857	Triethanolamine, Glycerin, Carbomer, Peppermint Oil	Present	Absent
Lovely Smile Premium Line Professional	Strip	2963	4.3 out of 5 stars	2.06	2,782	mint flavor, other details N.A.	Absent	Absent
Park Daniel Teeth Lightening Foam	Mousse	78	2.4 out of 5 stars	0.69	254	Mint Extract, other details N.A.	Present	Absent
SmiloShine Teeth Whitening Charcoal Gel	Gel	31	3.3 out of 5 stars	1.27	790	Activated charcoal, menthol	Present	Present
Oral Essentials Teeth Whitening Mouthwash	Liquid	3317	4.2 out of 5 stars	1.97	2785	Coconut oil, lemon, other details N.A.	Absent	Present
Yeesport teeth whitening strip	Strip	134	3.1 out of 5 stars	1.23	590	PVP, Glycerin, Water, Polysorbate-80, Flavor Citric Acid, Maltodextrin, Cellacefate	Present	Absent

N.A- Not available

Table 2: Intragroup comparison of shade and microhardness changes after bleaching

Groups	Evaluation criteria	N	Mean ± SD	Mean difference ± SD	t	P-value
Group I (DPA)	Prebleaching shade	10	12.4±2.22	8.9±3.64	7.74	<0.001
	Postbleaching shade	10	3.5±1.96
	Prebleaching microhardness	10	183.97±28.37	16.88±17.46	3.06	0.014
	Postbleaching microhardness	10	167.09±26.65
Group II (LRA)	Prebleaching shade	10	9.6±3.98	3.8±3.12	3.85	0.004
	Postbleaching shade	10	5.8±3.29
	Prebleaching microhardness	10	209.33±39.8	29.62±20.18	4.64	0.001
	Postbleaching microhardness	10	179.71±42.01
Group III (HRA)	Prebleaching shade	10	10.8±3.05	6.9±3.54	6.16	<0.001
	Postbleaching shade	10	3.9 ± 1.2
	Prebleaching microhardness	10	223.49±48.67	27.55±68.23	1.28	0.234
	Postbleaching microhardness	10	195.94±39.87

Table 3: Differences in shade postbleaching based on shade guide units (SGUs)

	Group I (N=10) Mean ± SD	Group II (N=10) Mean ± SD	Group III (N=10) Mean ± SD	P value
Prebleaching shade	12.4 ± 2.22	9.6 ± 3.98	10.8 ± 3.05	0.159
Postbleaching shade	3.5 ± 1.96	5.8 ± 3.29	3.9 ± 1.2	0.202
Delta SGU Pre-Post*	8.9 ± 3.64^a	3.8 ± 3.12^b	6.9 ± 3.54^ab	0.009

* If two values share a letter, they are not significantly different. Group I vs Group II has significant difference (P value= 0.007)

Table 4: Differences in postbleaching microhardness based on the Vickers hardness number (VHN)

Hardness evaluation	Group I (N=10) Mean ± SD	Group II (N=10) Mean ± SD	Group III (N=10) Mean ± SD	P-value
Prebleaching microhardness	183.97 ± 28.37	209.33 ± 39.8	223.49 ± 48.67	0.099
Postbleaching microhardness	167.09 ± 26.65	179.71 ± 42.01	195.94 ± 39.87	0.232
Overall difference	16.88 ± 17.46	29.62 ± 20.18	27.55 ± 68.23	0.35
Percent difference	8.84 ± 8.65	14.2 ± 9.16	7.26 ± 30.83	0.407

N- sample size

No competing interests reported.

Effect of over-the-counter teeth whitening products available on an e-market portal: an in-vitro study

Status:

Version 1

Abstract

Figures

INTRODUCTION

METHODOLOGY

RESULTS

DISCUSSION

CONCLUSION

Declarations

References

Tables

Additional Declarations

Status:

Version 1