Research Article: In-Vitro Evaluation of The Stain Removal Efficacy Between Two Whitening Dentifrices During Orthodontic Treatment

doi:10.21203/rs.3.rs-4174286/v1

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Research Article

Research Article: In-Vitro Evaluation of The Stain Removal Efficacy Between Two Whitening Dentifrices During Orthodontic Treatment

https://doi.org/10.21203/rs.3.rs-4174286/v1

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Background

This in-vitro study aimed to assess and compare the efficacy of a newly developed whitening dentifrice, Dentaklin White (TG), to Colgate Total® Whitening (CG), utilising a toothbrushing simulator machine.

Methods

Twenty enamel specimens were prepared and randomly divided into CG and TG. Orthodontic brackets were attached to the enamel specimens and were then stained with a mixture of coffee, tea, and chlorhexidine. A short 0.019x0.025” stainless steel (SS) archwire was ligated onto the brackets subsequently. All the specimens were subjected to a toothbrushing simulator for specific duration. The CIE L*a*b* colour change (ΔE) was evaluated using digital image analysis at T1 (2 weeks), T2 (4 weeks), and T3 (12 weeks) compared to T0 (baseline). Archwire roughness was analysed using a profilometer at T4 (2 years) compared to T0.

Results

The results indicated that there was a significant change in tooth colour associated with brushing duration for both CG and TG (p < 0.05) with no significant difference between the two dentifrices (p > 0.05). Both dentifrices notably removed more stains at Site A (p < 0.05) and increased wire surface roughness (p < 0.05) without a statistically difference between them (p > 0.05).

Conclusion

Dentaklin White (TG) demonstrated comparable efficacy to Colgate Total® Whitening (CG).

whitening dentifrice

orthodontic stains

arch-wire roughness

enamel roughness

The global increase in aesthetic dental treatments, including tooth whitening and orthodontic procedures, is evident in Malaysia as well[1, 2]. Dental stains are categorized into extrinsic and intrinsic types. Extrinsic stains are caused by compounds incorporated into the tooth surface, such as from coffee, tea, and tobacco, or by chemical interactions with substances like cationic antiseptics and metal salts[3], particularly on rough and porous enamel. Although professional prophylaxis using paste, pumice, and air polishing can remove extrinsic stains, their development on the labial surface of front teeth can be unpleasant, especially for those undergoing orthodontic treatment.

Progress in research technology has resulted in a rise in the creation and availability of tooth whitening dentifrices with different formulations, such as those containing sodium bicarbonate[4]. These products are marketed to address tooth staining and discoloration. Whitening dentifrices not only mechanically remove stains but also decrease the absorption of new stains. The convenience of use and cost-effectiveness compared to dental visits contribute to the growing popularity of whitening dentifrices in the market.

Apart from its stain removal benefits, sodium bicarbonate also offers additional advantages when used in dentifrices. It can reduce the acidity of dental plaque, leading to a decrease in cavities and aiding in the remineralization of early-stage carious[5]. Moreover, the antibacterial properties of sodium bicarbonate have been extensively studied, showing positive effects on oral pathogens and promoting gingival health[6]. More research is needed on the efficacy of whitening dentifrices with orthodontic brackets and their effects on orthodontic arch wires and enamel surface roughness. In this study, a newly developed whitening dentifrice with sodium bicarbonate (Dentaklin White) is compared to a marketed whitening dentifrice with hydrated silica (Colgate Total® Whitening).

This was an in-vitro study (Ethical approval: JEP-2021-784) that involved the newly developed whitening dentifrice, Dentaklin White (TG) and a control whitening dentifrice, Colgate Total® Whitening (CG) that was conducted on extracted sound human premolar enamel specimens using toothbrushing simulator machine. The specimens were divided into CG and TG group to assess the stains removal efficacy and orthodontic archwire surface roughness. A total of 10 samples were needed in each group based on sample size calculation according to a similar study done by Schwarzbold et al[7].

Preparation of Enamel Specimen

Extracted upper premolar teeth for orthodontic treatment purposes were collected with consent obtained. The crowns of the extracted upper premolars were sectioned and embedded in self-curing orthodontic resin, leaving the labial surface of enamel exposed, forming a block measuring 2cmx2cmx2cm. The specimens were soaked in artificial saliva at 37⁰C for 24 hours and again during the study period except for treatment and measurement periods. Enamel slabs in CG and TG were bonded with an orthodontic metal upper premolar offset bracket (American Orthodontics, MBT prescription, Mini Master 022x028 slot, WI, USA). The enamel surface was etched with 37% phosphoric acid (3M^™ Scotchbond^™ Etchant, Minnesota, USA) for 30 seconds, rinsed and air dried. A uniform layer of primer (Bracepaste^® MTP Primer, WI, USA) was applied to the tooth surfaces, and orthodontic adhesive (Bracepaste^® Adhesive, WI, USA) was applied to the base of the bracket and positioned at the center of the tooth surface. Excess material was removed, and light cured. A 0.019x0.025” SS archwire (American Orthodontics, WI, USA) measuring 20mm was ligated to the brackets with elastomeric modules during toothbrushing to simulate clinical scenario (Fig. 1).

Staining Solution and Prestaining

Staining broth was prepared with a mixture of tea, coffee, and chlorhexidine mouthwash 0.12%. The tea and coffee solution were prepared as described by Schwardzbold et al[7]. To this mixture, 30 ml of Chlorhexidine 0.12% was added. The specimens were immersed in this solution for 1 week, which was renewed every 24 hours and kept at 37⁰C.

Dentifrice Slurry

The dentifrices were used as slurries, prepared by mixing 15 g of test or control dentifrices with 45 ml of deionized water, at a ratio of 1:3 according to the EN ISO 11609:2017 standard (Dentistry-Toothpastes: Requirements, test methods and marking)[8].

Toothbrushing Simulation

A custom-made toothbrushing apparatus, UKM (Universiti Kebangsaan Malaysia) Wear and Toothbrush Simulator (Fig. 2) was used for toothbrushing simulation throughout the study. The commercially available toothbrush (Colgate® SlimSoft Orthodontic Toothbrush) was attached to the toothbrushing machine. Specimens were mounted onto the toothbrushing simulator machine with a brushing force of 150g in an axial movement.

Brushing Regime

The average time taken to brush twice daily by a person was 240 seconds. Based on this estimation, the maximum contact time for one tooth surface per day was 10 seconds. Thus, the total brushing time is calculated to be 60 minutes, which is equivalent to 1 year of brushing[9]. The toothbrush was replaced after 45 days[8] and the dentifrice slurry was changed every 2 minutes of brushing. Data collection and analysis were done at T1 = 140 seconds (equivalent to 2 weeks of brushing), T2 = 280 seconds (4 weeks)[10] and T3 = 14 minutes (3 months) for stains removal assessment, and at T4 = 120 minutes (2 years) for orthodontic archwire roughness assessment.

Colour Analysis and Setup

The stains on enamel specimens were measured by using photography technique to obtain the CIELAB value. The specimens were placed in the photo light box and a DSLR camera (Canon EOS 600D, Macro Lens Tamron 90mm, and YongNuo Macro Ring Lite YN14EX) was used to capture the image of specimens at a fixed distance with the same setting and surrounding (Fig. 3). Measurements were taken on the enamel surface at six sites (Fig. 4): incisal to the bracket slot (Site 1 and Site 2), gingival to the bracket slot (Site 4 and Site 5), and mesial and distal of the bracket slot (Site 3 and Site 6) before and after treatment. The CIE L*a*b* colour scale was gained by using Adobe Photoshop (Version 21.2.4.323) whereby the images at different time points (T0, T1, T2, and T3) for the same sample were overlapped and six different fixed points were selected for reading. Three readings were repeated at each site and overall mean value was obtained. The difference between the pre-test and post-test readings represents the ability of the test products to remove stains. Besides that, the readings on sites 1, 2, 4, and 5 were averaged (Site A) and compared to the mean value of sites 3 and 6 (Site B) to compare the stain removal efficacy at different sites of enamel specimens. The overall change in stains was calculated using the following CIELAB equation, ΔE= {<L_T1/T2/T3 – L_T0>² + < a_T1/T2/T3 – a_T0>² + < b_T1/T2/T3 – b_T0>²}^½

Orthodontic Wire Surface Roughness

The wire roughness was assessed using surface profilometer (Infinite Focus Real 3D Alicona). Three fixed points were selected on each side of the wire at the 0.025” side (Fig. 5), whereby this instrument focused on the surface at the prescribed distance and quantified roughness as Ra value. A total of three readings were gained at each specific point and were averaged to gain the mean value for one wire. The measurement was done before the enamel specimens were subjected to toothbrushing machine (T0) and after the specimens subjected to toothbrushing regime (T4).

Scanning Electron Microscopy (SEM)

The 0.019x0.025” SS archwire were sent for SEM image analysis (Zeiss, Supra 55vp) and elemental analysis to compare the elements on the wire before and after toothbrushing.

Statistical Analysis

The data analysis was done using SPSS version 26. Descriptive data was expressed as mean ± standard deviation (SD) unless otherwise stated. Paired t-test was used to compare the within group result while an independent t-test was used to compare the between-group results. A two-way ANOVA test was conducted to compare the stain removal efficacy at different time points within and between groups. A value of p < 0.05 was considered statistically significant.

Stain Removal Efficacy

The mean and SD for colour changes, ΔE were presented in Table 1. The results of the two-way mixed ANOVA (Table 2) indicated that there was no significant main effect of types of dentifrice on the ΔE, p > 0.05. However, there was a significant main effect of the time of toothbrushing on the ΔE, p < 0.001. Additionally, there was no significant interaction between types of dentifrice and time of toothbrushing regarding ΔE, p > 0.05. The mean and SD for ΔE according to site were presented in Table 3. The results of the two-way repeated measure ANOVA (Table 4) indicate that there was a significant main effect on the site of enamel, p < 0.05, and a significant main effect on the time of toothbrushing, p < 0.001 for the ΔE in both CG and TG. However, there was only significant interaction between the site of enamel and the time of brushing on the ΔE, p < 0.05 in the TG. The differences in ΔE between Site A and Site B were calculated by subtracting ΔE of Site B from ΔE of Site A. The results of the ANOVA show a significant main effect of the types of dentifrice on the differences in colour changes between Site A and Site B, p = 0.003. Hence, independent t-test was carried out to determine if there was a statistical difference between the control and test dentifrice at each timepoint (T1-T0, T2-T0, and T3-T0). Result in Table 5 shows that there was a statistical difference between the CG and TG at T3-T0, whereby the TG recorded a less mean difference of 4.597 between Site A and Site B than the CG, p = 0.015.

Table 1

Mean and SD of ΔE for both TG and CG
Time point	Group	Colour Changes
T1-T0	Control	9.417 (2.385)
T1-T0	Test	10.185 (0.943)
T2-T0	Control	12.909 (3.461)
T2-T0	Test	12.481 (2.226)
T3-T0	Control	15.995 (3.947)
T3-T0	Test	15.158 (2.608)

Table 2

Two-way Mixed ANOVA result for ΔE in TG and CG
	p-value
Group (control vs test)	0.888
Time of toothbrushing	0.000*
Time of toothbrushing x Types of Dentifrice	0.111

Table 3

Mean and SD of ΔE for both TG and CG according to Site
Group		CG	TG
Site of Enamel	Time of Toothbrushing	Mean ΔE	Mean ΔE
Site A	T1-T0	11.050 (3.720)	11.086 (1.609)
	T2-T0	14.756 (4.875)	13.505 (3.274)
	T3-T0	17.422 (4.978)	14.981 (3.331)
Site B	T1-T0	6.148 (1.578)	8.641 (1.294)
	T2-T0	9.216 (2.133)	10.433 (1.652)
	T3-T0	11.665 (2.754)	13.821 (2.081)

Table 4

Tests of within-subjects effects of Site A and Site B according to time of toothbrushing for CG and TG
Group	CG		TG
	F	Sig.	F	Sig.
Site	14.993	0.004*	5.641	0.042*
Time of Toothbrushing	72.253	0.000*	57.830	0.000*
*Site Time of Toothbrushing**	1.079	0.361	5.450	0.014*

Table 5

Independent t-test for differences in colour change by Site between CG and TG according to time of toothbrushing
Time of Toothbrushing	p-value	Mean Difference	Std. Error Difference	95% Confidence Interval of the Difference
				Lower	Upper
T1-T0	0.138	2.457	1.554	-0.903	5.816
T2-T0	0.223	2.468	1.954	-1.637	6.573
T3-T0	0.015*	4.597	1.718	0.987	8.206

Orthodontic Archwire Surface Roughness

The result is shown in Table 6. The difference in orthodontic wire surface roughness for the CG was − 0.021µm, and for the TG was − 0.018µm, indicating that the orthodontic wire became rougher after toothbrushing. The difference was statistically significant for both CG and TG, p < 0.001 and p = 0.001, respectively. Although the CG recorded a higher roughness value compared to TG, this difference was not statistically significant p > 0.05.

Table 6

Result for orthodontic archwire surface roughness
Types of Dentifrice	CG		TG
	Mean difference	p value	Mean difference	p value
Pre-test - Post-test	-0.021 (0.012)	0.004*	-0.018 (0.011)	0.001*
Difference between CG and TG	p = 0.499

SEM Image of Orthodontic Archwire

The surface of a 0.019x0.025" orthodontic SS archwire was analyzed using SEM. The wire exhibited lines and grooves running parallel to the long axis of the wire, with some minor pitting visible at 1000x magnification prior to toothbrushing. After simulating 2 years of toothbrushing, both the CG and TG showed a rougher surface and texture, with visible scratches, grooves, and signs of wear along the wire. The wire surface became more irregular, but there was no residual dentifrice or debris observed on its surface (Fig. 6).

Elemental Analysis of Orthodontic Archwire

The elemental analysis of archwire showed that there is no difference in the archwire elemental pre-brushing and post-brushing, indicating that no obvious deposition of dentifrice elements on the archwire that could affect the surface roughness (Fig. 7).

In our study, we used photography image analysis to assess the amount of stain removal in the enamel specimens. To reduce the error, the enamel specimens were allowed to dry at room temperature for 30 minutes. The images were taken using the same setting and in a dark room to prevent any additional light source that could affect the result. This technique was proven to be effective when used in both lab study[11] and clinical study[12]. The previous study used the magnetic lasso tool in Adobe Photoshop for point selection may result in inaccuracy of result due to different points selection on different images. To ensure high accuracy and consistency of point selection in this study, the image taken at different timepoint were overlapped in Adobe Photoshop at the same angle and location with six points were marked on the image where the L*a*b* value. Other objective measurements of stains removal include the use of spectrophotometer and colorimeter[13]. In our study, the enamel specimens were not polished to produce a flat surface and hence the use of a spectrophotometer can subject to errors due to the natural curvature of the enamel specimens[14].

Our study found that there was no statistical difference between the CG and TG, which was in agreement with study done by Alshara et al[15]. However, study done by Schemehorn et al was in favoured of hydrated silica[16]. While more studies showed that sodium bicarbonate was superior to silica in stains removal[17, 18], our study found no difference between both groups. This can be due to differences in the abrasive particle size, size and possibly the pH the newly developed whitening dentifrice[19]. Besides that, the TG did not have peroxide added to further enhance the whitening effects[19]. Other than that, the insignificant result can be due to a lower concentration of sodium bicarbonate[20] and does not contain sodium lauryl sulfate (SLS) that is responsible for foam production and lowers the stains molecules' surface tension[21].

The stain removal efficacy of CG and TG was further subdivided into Site A and Site B, which is a modification of Ortho-Plaque Index (OPI)[22]. This is due to Site A is easily accessible to the toothbrush and whitening dentifrice in comparison to Site B. This was reflected in our results showing that Site A had significantly more ΔE than Site B in both CG and TG. This could be due to the presence of orthodontic archwire and the horizontal movement of the toothbrush resulting in less diffusion and contact of abrasive agents to the enamel surface underneath the archwire as abrasive materials is only effective in areas that a toothbrush's bristles can access[19]. The lesser differences in ΔE between Site A and Site B indicate that the ΔE between both sites is almost similar, hence a higher ΔE at Site B, which is impeded by the orthodontic wire. The significant result at T3 may be due to sodium bicarbonate having a better penetration compared to the hydrated silica. The result suggested that the use of test dentifrice is better for patients with conventional fixed appliances after the use of 3 months.

The roughness reading was gained from the depth of wire, as this is the site that is in contact with the orthodontic bracket’s slot during sliding mechanics. Hence, any changes to the orthodontic wire’s surface characteristic at this site may result in an alteration of frictional force. Both CG and TG resulted in a significant increase of archwire surface roughness at T4. Elevated surface roughness can lead to a significant rise in frictional forces due to increased contact between the bracket and wire[23]. This can result in a reduction of orthodontic force by 50% or greater, ultimately diminishing the effectiveness of orthodontic treatment and may result in anchorage loss[24]. Nevertheless, the clinical significance of the resulting increased friction force remains uncertain.

From our study, it can be concluded that:

Both CG and TG had the same stain removal efficacy during orthodontic treatment.

The stain removal efficacy was higher at Site A compared to Site B for both CG and TG with a significant difference at T3.

The orthodontic SS archwire became rougher after brushing with CG and TG.

Dentaklin White had equal efficacy with Colgate Total® Whitening for stains removal during orthodontic fixed appliance treatment and maybe more superior in accessing hidden areas after 3 months of use.

Acknowledgement

We would like to express our extreme gratitude to Irma Ariandi Global Sdn Bhd, and Faculty of Dentistry, Universiti Kebangsaan Malaysia for supporting this study.

Author’s contribution

KAMK, MMN, BB contributed to the study conception and design. Material preparation was performed by EYZH. Data collection and analysis was done by EYZH and HR. Writing of original draft by EYZH and KAMK. All authors have read and approved the final manuscript.

Funding

This study was funded by Irma Ariandi Global Sdn Bhd (DD-2022-006), manufacturer of Dentaklin White. The research itself was meticulously executed by a dedicated team from the University Kebangsaan Malaysia, guaranteeing a neutral and unbiased approach throughout the study.

Data Availability

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Ethics approval and consent to participate

The study was approved by the Research Ethical Committee of Universiti Kebangsaan Malaysia (UKM/PPI/111/8/JEP-2021-784). This study was conducted in accordance with the principles of the Declaration of Helsinki, and all patients provided written informed consent prior to enrolment.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

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No competing interests reported.

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Research Article: In-Vitro Evaluation of The Stain Removal Efficacy Between Two Whitening Dentifrices During Orthodontic Treatment

Status:

Version 1

Abstract

Background

Methods

Results

Conclusion

Figures

INTRODUCTION

MATERIALS AND METHODS

Preparation of Enamel Specimen

Staining Solution and Prestaining

Dentifrice Slurry

Toothbrushing Simulation

Brushing Regime

Colour Analysis and Setup

Orthodontic Wire Surface Roughness

Scanning Electron Microscopy (SEM)

Statistical Analysis

RESULTS

Stain Removal Efficacy

Orthodontic Archwire Surface Roughness

SEM Image of Orthodontic Archwire

Elemental Analysis of Orthodontic Archwire

DISCUSSION

CONCLUSION

Declarations

References

Additional Declarations

Status:

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