The Effect of Newly Developed Home Bleaching Gels on Tooth Colour and Mineral Alteration

doi:10.21203/rs.3.rs-2972546/v1

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The Effect of Newly Developed Home Bleaching Gels on Tooth Colour and Mineral Alteration

https://doi.org/10.21203/rs.3.rs-2972546/v1

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Objectives This study aimed to compare tooth mineralization and colour changes achieved with two newly developed experimental bleaching gels containing 16% CP or 6% HP with the FGM Whiteness Perfect (16% CP) and BioWhiten ProHome (6% HP) at-home bleaching systems.

Material and methods:Ninety-six maxillary central teeth extracted for periodontal reasons without defects, cracks, or caries were included. All samples were standardized for enamel-dentin thickness by cone-beam computed tomography (CBCT). The samples were divided into 2 groups for colour (n=48) and mineral (n=48) change evaluations. These groups were then further divided into 4 subgroups according to the bleaching agent to be applied (n=12). Mineral analysis was performed with the SEM-EDX (SEM, Zeiss Gemini) device before the bleaching treatment, at the end of the treatment, and 2 weeks after the treatment ended to assess changes. Colour measurement was performed with a spectrophotometer device (VITA EasyShade, Zahnfabrik) before the bleaching treatment, on the 7th day of treatment, 24 hours after the final treatment, and 2 weeks after the treatment ended. Colour change values were calculated with the CIEDE2000 formula. Paired t tests/Wilcoxon signed-rank tests and ANOVA/Kruskal–Wallis tests were used for the statistical analysis. p < 0.05 was considered to indicate significance.

Results: Effective bleaching was achieved in all groups in the study. No significant difference among the groups was found in the colour change (p>0.05), while mineralization differed significantly (p<0.05).

Conclusions: The colour and mineral change assessment revealed that the ideal bleaching agent was ECP (Group 1).

Clinical Relevance: With the increased demand for conservative aesthetic treatments, dental bleaching technologies have become increasingly popular. However, bleaching agents lead to the formation of reactive oxygen species, which have genotoxic effects. The use of theobromineand chitosan can provide clinicians with positive results for bleaching treatments, such as the ability to use lower HP concentrations and avoid side effects.

Carbamide peroxide

hydrogen peroxide

chitosan

theobromine

colour change

SEM-EDX

Many studies have compared different tooth bleaching procedures in terms of treatment effectiveness, continuity of effectiveness, tooth sensitivity, and general patient satisfaction by evaluating numerous criteria, such as the application method, the agent used, the concentration of the agent, and the duration of the treatment. Agents containing hydrogen peroxide (HP) and carbamide peroxide (CP) are preferred in bleaching applications. Pereira et al. investigated the effect of office and home bleaching applications on tooth colour changes and reported that the colour relapse after 6 months is greater with home bleaching applications [1]. Another study assessed office bleaching agents (38% HP) and home bleaching agents (10% CP) in terms of the agent, method, sensitivity, and patient satisfaction and revealed greater tooth colour changes, reduced sensitivity, and better patient satisfaction with home bleaching applications [2]. A third study assessed the effectiveness of home (10% and 20% CP) and office (35% and 38% HP) bleaching agents, including tooth sensitivity, and revealed that sensitivity was highest after applying the 20% CP treatment and lowest after applying the office bleaching treatments, with no difference in efficacy or the final colour results [3]. The literature reveals discrepancies in the effectiveness, sensitivity, and patient satisfaction levels regarding office and home bleaching methods, and each method has advantages and disadvantages [1,2,4].

HP produces free radicals that can damage tissues due to their high oxidizing properties [5,6]. Many studies have revealed the undesirable effects of HP after bleaching applications, including changes in tooth structure [7,8], pulpal tissues [9,10], and oral mucosa [11]. Cytotoxic effects have been observed after bleaching with agents containing high levels of HP; for example, Lilaj et al. emphasized that cytotoxic effects increase as the HP concentration in bleaching applications increases in a study comparing low and high HP concentrations [12]. The 2011/84/EU European Directive indicates that a maximum HP concentration of 6% is safe in tooth bleaching agents [13]. Due to the side effects of numerous HP applications and in line with this directive, we developed a bleaching gel containing a low HP concentration.

CP releases HP and urea during the reaction process and is typically used at 10–20% concentrations in home bleaching treatments [14]. One study compared 4 different home bleaching agents containing 10% or 15% CP and 7.5% or 9.5% HP and observed a similar efficacy across all groups [15]. Another group compared two bleaching agents, one containing 9% HP and one containing 20% CP, and found that 9% HP provided more effective bleaching than 20% CP [16]. Another study assessed the colour change achieved with 6% HP and 16% CP agents, and 16% CP was found to be more effective [1].

Chitosan is natural, biocompatible, and non-toxic and is one of the most abundant biopolymers in the world [17,18]. Chitosan contributes to oral tissue wound healing [19] and reduces enamel demineralization, caries formation, and acid-induced erosion [20, 21], along with preventing dental plaque formation [22]. Chitosan also exerts antimicrobial effects on oral pathogens [23]. Thus, chitosan is extensively applied in dentistry [24]. We added chitosan to our experimental gels as a carrier and thickening agent, obtaining additional benefits from its remineralizing effects and bioadhesive properties [25].

Theobromine is an alkaloid found in chocolate and cocoa [26]. Theobromine is thought to contribute to the remineralization of dental hard tissues due to its demineralization prevention and remineralizing effects [27]. Theobromine and fluorine have been shown to contribute to remineralization, achieving similar levels of apatite formation and enamel surface hardening [28,29]. Thus, numerous studies have been conducted to investigate the caries-prevention effects of theobromine, and it was found to reduce Streptococcus mutans [30,31]. Due to the advantages mentioned above, theobromine is an attractive enamel remineralization material and was added to our experimental gels to obtain remineralizing and antikaryostatic effects.

Thus, we have developed an experimental home bleaching gel containing chitosan and theobromine to reduce the side effects of bleaching treatments while obtaining effective bleaching results. To ensure standardization, we selected gels containing 6% HP, 16% CP, or an equivalent concentration of the active agent (HP) for comparison with the new home bleaching gels.

In our study, the newly developed experimental bleaching gels were compared with the BioWhiten ProHome (6% HP) and FGM Whiteness Perfect (16% CP) home bleaching systems, and their effects on enamel mineral and tooth colour changes were evaluated. Mineral changes were evaluated with a scanning electron microscope-energy dispersive X-ray (SEM-EDX) device, and colour changes were evaluated with a spectrophotometry device. In addition, cone-beam computed tomography (CBCT) was used to determine the enamel thickness of all samples for standardization.

The null hypotheses were as follows:

Adding theobromine to bleaching gels does not adversely affect tooth colour changes or mineralization.

Adding chitosan to bleaching gels does not adversely affect tooth colour changes or mineralization.

The XXX University Ethics Committee approved this study (report number 2022/309).

Preparation of Samples

A power analysis was performed before the start of the study to determine the number of samples required (G* Power 3.1.9.4). The minimum sample size was calculated as 48 with an effect size of 0.78 and a power of 95% (1-β) with a 5% (α) confidence interval for the mineral variation analysis. Likewise, for repeated colour change measurements, the minimum sample size was 48 with an effect size of 0.81 and a power of 80% (1-β) with a 5% (α) confidence interval. The study protocol is shown in Fig. 1.

Selection of Teeth Used in the Study and Formation of Groups

Ninety-six central maxillary teeth without defects, cracks, or caries were included in the study. All samples were standardized in terms of enamel-dentin thickness by CBCT (Promax 3D; Planmeca, Helsinki, Finland) and subsequently divided into 2 groups for the colour determination (n = 48) and mineral change (n = 48) analyses. These 2 groups were then divided into 4 subgroups according to the whitening agent to be applied, as shown in Fig. 2. No significant differences between the initial colour measurements and mineral values were observed (n = 12).

Colour Measurement with a Spectrophotometer Device

Colour determination was performed with a VITA EasyShade Advance 4.0 (Zahnfabrik, Bad Sackingen, Germany) spectrophotometer device. Per the manufacturer's instructions, measurements were made under D65 daylight on a grey background, with the device's tip touching the centre of the middle third of the tooth at the buccal surface. These measurements were repeated four times as follows: before the initiation of the bleaching treatment, on the 7th day of the treatment, 24 hours after the end of the treatment, and 14 days after the end of the treatment. Holes with a diameter of 6 mm were drilled into 0.040 inch (1.5 mm) thick hard plates to ensure standardization during colour measurements. Each measurement was made three times through these holes, and the average of the obtained values was recorded. The colour change was calculated using the CIEDE 2000 formula as follows; ΔE₀₀= [(ΔL/K_LS_L)² + (ΔC/K_CS_C)² + (ΔH/K_HS_H)² + R.T(ΔC/K_CS_C)(ΔH/K_HS_H)]^1/2 [32]. The parametric factors suggested by CIE (H_R=1 K_C=1 K_L=1) were used [33]. Perceptible and acceptable colour changes (50–50%) were accepted as 0.8 and 1.8, with reference to the values used in the study by Paravina et al. [34].

ΔL, ΔC, and ΔH in the formula represent lightness, chroma, and tonal differences, respectively. S_L, S_C, and S_H are weighting functions for the lightness, chroma, and tonal differences components, respectively. RT represents the interaction between hue and colour differences in the blue region. K_L, K_C and K_H are parameterized factors for changes in operating conditions [35].

SEM-EDX Analysis

A SEM-EDX (SEM, Zeiss Gemini SEM 300, Oberkochen, Germany) device was used in our study, which analyses the elemental nature of objects and existing surface defects using X-rays. Calcium (Ca) and phosphorus (P) levels were examined before the bleaching gel was applied, immediately after the bleaching procedure was completed, and 14 days after the treatment. In addition, 1 tooth was selected from each group, and the enamel surface was examined by SEM (ZEISS Gemini SEM 300, Oberkochen, Germany) at ×600, ×1000, and ×2500 magnification. Mineral contents were examined by calibrating the device spectrum at 20 Kv, ×100 magnification, a 5 nm spot size, a 35^o departure angle, and a count of 100 sec.

Preparation of the Experimental Bleaching Gel

Chitosan (2 g, Sigma Aldrich Chemical, St. Louis, USA) was weighed on a precision balance (Sartorius, TE 214 S) and added to 100 ml water; 1% acetic acid was added to dissolve the chitosan with the help of a magnetic stirrer (FAITHFUL SH-2). Then 0.05 g of theobromine (Sigma Aldrich Chemical, St. Louis, USA) was added. The prepared solution was then mixed with 30% HP (Sigma Aldrich Chemical, St. Louis, USA) at the determined ratios or a 6% HP gel and 97% CP (Sigma Aldrich Chemical, St. Louis, USA) at the determined ratios to obtain a 16% CP gel.

Artificial Saliva Preparation

The prepared synthetic saliva solution comprised 4380 mg sodium bicarbonate, 2540 mg potassium phosphate, 1640 mg potassium chloride, 882 mg calcium chloride, 9 mg sodium fluoride, 250 mg magnesium chloride, 20 mg nipagin, 200 mg nipazole, 48 mg sorbitol, 16 mg carboxymethylcellulose, and 2000 ml distilled water (pH 7.0). This artificial saliva solution was changed daily throughout the study.

Application of the Bleaching Procedure

The teeth were embedded in heavy-body silicone impression material (Optosil, Heraeus-Kulzer, Hanau, Germany) 2 mm above the enamel cement boundary, with the crowns exposed. A border was created along the enamel-cement margin of the teeth with 1 mm light-body silicone impression material to prevent gel leakage and determine the gingival border. (Optosil, Heraeus-Kulzer, Hanau, Germany). Then, the mould was measured using a suitable tray, and hard plaster was poured into alginate (Cavex CA37, Cavex Holland BV, RW Haarlem, The Netherlands). One millimetre resin blocks (LC Block-Out Resin, Ultradent, South Jordan, USA) were placed on the buccal surfaces of all teeth 1.5 mm from the determined gingival border to create a reservoir. The model was then polymerized with a wireless Valo Led (Ultradent Products, South Jordan, USA) device, and a 0.035 inch (0.9 mm) bleaching plate was printed using a vacuum machine (Vacuum Forming Machine model no: 202, Keystone Industries, Myerstown, USA). The borders of the plates were placed 1 mm below the anatomical enamel-cementum border of the teeth (at the determined gingival border). Bleaching gels were applied using this plate in a sterilization bag and a metal tub with a small amount of artificial saliva at the bottom at 37ºC in an oven. Bleaching applications were made without rinsing the artificial saliva from the teeth. After each bleaching application, all samples were washed with distilled water for 30 seconds, cleaned for 20 seconds with a soft toothbrush, and then kept in artificial saliva in an oven (Sanyo MOV-112S, Sanyo Electric Biomedical Co., Ltd., Osaka, Japan) at 37º C for 14 days.

Statistical Analysis

The Shapiro–Wilk test was used to determine whether the numerical variables were normally distributed. ANOVA and post hoc least significant difference (LSD) tests were used to compare groups for normally distributed variables. A paired t test was used for in-group comparisons. Dunn and Kruskal–Wallis multiple comparison tests were used for the intergroup comparison of non-normally distributed variables, and the Wilcoxon signed-rank test was used for within-group comparisons. Analyses were performed using IBM SPSS 22.0 (IBM Corp., Armonk, New York, USA), and p < 0.05 was considered to indicate significance.

Analysis of Colour Change Values

Colour change values were calculated using the CIEDE2000 formula.

ΔE₀₀₁: Colour change values from pre-application to 7 days after the start of application.

ΔE₀₀₂: Colour change values from pre-application to 15 days after the start of application

ΔE₀₀₃: Colour change values from pre-application to 14 days after the end of application (end of 28th day)

The comparisons of ΔE₀₀ colour change values within and between groups are shown in Table 1.

Table 1

Standard deviation and mean ΔE₀₀ change values of all groups (ΔE ± sd)
	Group 1(ECP)	Group 2(EHP)	Group 3(6HP)	Group 4 (16CP)
ΔE₀₀₁	5,60 ± 2,27^Aa	5,27 ± 2,49^Aa	4,10 ± 1,51^Aa	6,59 ± 2,31^Aa
ΔE₀₀₂	8,66 ± 4,22^Ba	8,39 ± 4,37^Ba	8,19 ± 4,16^Ba	9,03 ± 4,63^Ba
ΔE₀₀₃	8,81 ± 3,35^Ba	8,55 ± 3,49^Ba	8,22 ± 3,62^Ba	8,55 ± 3,70^Ba
Letters in rows and columns indicate a statistically significant difference. Capital letters indicate statistical difference within the same column, lower case letters indicate statistical difference within the same row.

No significant differences were observed in the ΔE₀₀₁, ΔE_002, and ΔE₀₀₃ values in the between-groups comparison (p > 0.05).

In the group comparison, while a significant increase was observed in the ΔE_001, ΔE₀₀₂, and ΔE₀₀₃ values across groups (p < 0.05), there was no significant difference between the ΔE₀₀₂ and ΔE₀₀₃ values (p > 0.05).

Analysis of Mineral Changes

Statistical analyses were performed by specifying the mineral content values of all groups as Ca₁, P₁ (SEM-EDX analyses performed before the bleaching applications), Ca₂, P₂ (after the bleaching applications), and Ca₃, P₃ (14 days after the end of the bleaching applications).

Calcium Mineral Findings

The mean values (± sd) of Ca in all groups are shown in Table 2.

Table 2

Standard deviation and mean (%) values of Ca mineral for all groups (Ca ± sd)
	Group 1 (ECP)	Group 2 (EHP)	Group 3 (6HP)	Group 4 (16CP)
Ca₁	33,85 ± 1,79^Aa	34,17 ± 2,11^Aa	32,07 ± 2,34^Aa	31,86 ± 2,64^Aa
Ca₂	34,46 ± 1,54^Aa	34,57 ± 1,90^Aa	26,60 ± 3,55^Bb	29,42 ± 3,95^Bb
Ca₃	34,57 ± 2,32^Aa	34,77 ± 2,35^Aa	28,89 ± 3,32^Bb	29,61 ± 4,18^Bb
Letters in rows and columns indicate a statistically significant difference. Capital letters indicate statistical difference within the same column, lower case letters indicate statistical difference within the same row.

No significant difference was observed in Ca₁ values in the between-groups comparison (p > 0.05). However, Ca₂ and Ca₃ values differed significantly among Groups 1–4 (p < 0.05).

In the group comparison, no significant difference in any Ca values was observed between Groups 1 and 2 (p > 0.05). However, a significant difference was observed between the Ca₁ value and the Ca₂ and Ca₃ values in Groups 3 and 4 (p < 0.05).

The Ca values were increased in Groups 1 and 2 after bleaching but decreased in Groups 3 and 4.

Phosphorus Mineral Findings

The mean values (± sd) of P in all groups are shown in Table 3.

Table 3

Standard deviation and mean (%) values of P mineral for all groups (P ± sd)
	Grup 1 (ECP)	Grup 2 (EHP)	Grup 3 (6HP)	Grup 4 (16CP)
P₁	18,85 ± 1,14^Aa	16,55 ± 1,42^Aa	16,23 ± 2,17^Aa	13,83 ± 1,45^Aa
P₂	18,37 ± 1,55^Aa	16,21 ± 1,79^Aa	15,48 ± 2,40^Ba	12,47 ± 1,44^Ba
P₃	18,43 ± 1,82^Aa	16,32 ± 1,63^Aa	15,59 ± 1,97^Ba	12,51 ± 1,35^Ba
Letters in rows and columns indicate a statistically significant difference. Capital letters indicate statistical difference within the same column, lower case letters indicate statistical difference within the same row.

No significant differences in the P₁, P_2, and P₃ values were found in the between-groups comparison (p > 0.05).

In the group comparison, no significant differences in P₁, P₂, P₃ values were observed in Groups 1 and 2 (p > 0.05); however, a significant difference was found between the P₁ value and the P₂ and P₃ values in Groups 3 and 4 (p < 0.05).

Our hypotheses were accepted:

Adding theobromine to bleaching gels does not adversely affect tooth colour changes or mineralization.

Adding chitosan to bleaching gels does not adversely affect tooth colour changes or mineralization.

Mineral Analysis

Urea and free oxygen molecules form through oxidation and reduction reactions, which constitute the mechanism of action of bleaching agents, and cause erosion and an increase in enamel roughness. In addition, the intermediate products formed during these reactions can affect the interprismatic area by denaturing proteins in the organic enamel content [36, 37]. Amorphous calcium and fluoride ions have been added to bleaching agents to reduce the mineral exchange in the enamel tissue during bleaching. It has been reported that adding these molecules to bleaching agents reduces mineral loss from the enamel [38,39,40].

Measuring P and Ca on the enamel surface provides information about the demineralization–remineralization process [41]. P and Ca are lost during bleaching applications due to the dissolution of hydroxyapatite crystals [42]. Remineralization resumes when sufficient P and Ca levels are present in the saliva and when the salivary pH is neutral.

In our study, the SEM-EDX evaluation performed after bleaching revealed a decrease in the Ca and Ca/P ratios in the groups treated with FGM Whiteness Perfect (Group 4) and BioWhiten ProHome (Group 3). The Ca and Ca/P ratios increased in the groups treated with the experimentally prepared agents containing 6% HP (Group 2) and 16% CP (Group 1) with theobromine and chitosan. P is another indicator of the demineralization–remineralization balance and was decreased in all groups in the intragroup comparison.

Soares et al. [43] reported decreased Ca and P concentrations in teeth treated with home bleaching agents containing 10% or 16% CP (FGM Whiteness Perfect). Consistently, in our study, Ca and P values decreased significantly after FGM Whiteness Perfect gel application.

Orilisi et al. [44] reported that BioWhiten bleaching gel containing 6% HP and nanohydroxyapatite applied for 50 minutes a day for 7 days resulted in a non-significant decrease in Ca and P levels, and the Ca/P ratio remained constant. Conversely, in our study, the Ca and P values decreased significantly with BioWhiten, potentially because we applied the agent for 14 days instead of 7 days.

Cakir et al. [45] used agents containing 10%, 20%, or 35% CP in an in vitro study on 60 extracted teeth, and the mineral content evaluation revealed that all three bleaching systems reduced the Ca levels. Consistently, in our study, a decrease in the Ca value was observed after bleaching treatment with FGM gel.

Vilhena et al. [46] used a SEM-EDX device to evaluate enamel Ca and P mineral concentration changes after three bleaching applications with a 10% CP. They observed a non-significant increase in Ca and a decrease in P in all groups after bleaching. This result is similar to the Ca and P changes observed with the ECP gel in our study.

Botelho et al. [47] evaluated the effect of home and office bleaching applications on enamel Ca and P after using agents containing 10% and 20% CP and those containing 35% and 38% HP. No significant changes in post-treatment measurements were present across all 4 gels in terms of the Ca concentration; however, the lowest Ca concentration was observed in the gel containing 38% HP at 14 days after the start of the treatment. Consistently, in our study, the agents containing HP caused the greatest decrease in Ca concentration in the between-groups comparison.

Cavalli et al. [48] reported that bleaching agents containing HP alone could not prevent demineralization by reducing the Ca/P ratio, while agents containing F or Ca prevented demineralization. These results are compatible with the knowledge that Ca and F reduce enamel demineralization [49, 50, 51]. In our study, the increased Ca/P ratio in the experimental gel–treated groups is likely due to the addition of chitosan and the natural remineralizing agent theobromine.

Musanje et al. [52] reported that using artificial saliva promotes remineralization and increases Ca and P concentrations. In addition, keeping the teeth in artificial saliva may decrease microhardness values after bleaching applications, and Ca and P values may increase after ion exchange with saliva [8, 53]. Consistent with this information, in our study, Ca₂–Ca₃ and P₂–P₃ values increased in all groups.

Colour Analysis

Colour evaluations were conducted using the CIEDE 2000 system, and an effective and perceptible colour change occurred in all groups. A visible change occurred in all groups within the first 7 days. The intergroup evaluation revealed no significant differences across the groups pre-application, at 7 days, or at 15 and 28 days after the beginning of the treatment.

Pavesi-Pini et al. [54] evaluated the effects of adding chitosan to bleaching gels containing 35% HP on tooth properties and bleaching efficiency and reported that bleaching efficiency was similar in all groups; however, slight surface changes were observed in all groups in the SEM images. They reported that the chitosan-containing gels resulted in a reduced surface density change. Thus, it was thought that chitosan-enriched HP gels could reduce the negative effects of bleaching on the teeth without affecting the bleaching efficacy.

Li et al. [55] reported that 0.05–0.2% chitosan added to bleaching gels increased the release time of free radicals and the brightness value of the colour by preventing the removal of hydroxyl radicals and the decomposition of HP. Sürmelioğlu et al. [13] compared two experimental bleaching gels (6% HP + titanium dioxide and 6% HP + titanium dioxide + chitosan) with a 35% HP-containing bleaching agent and evaluated the colour changes after two bleaching treatments. After the first and second sessions, the agent containing 35% HP was superior to the others, and after 14 days, the colour change in the 6% HP + titanium dioxide + chitosan gel group reached a level similar to that of the 35% HP group. Similarly, in our study, colour measurements were taken 14 days after the completion of the bleaching treatment and 1 day after the bleaching applications. The colour changes in the groups treated with chitosan-containing agents increased, nearing that observed in Group 4, which demonstrated the highest ΔE₀₀₂ value at 1 day; 14 days after the bleaching applications, the colour change values were similar or higher in the chitosan gel–treated groups. Chitosan increases the hydrophilicity of the agents, decreasing the contact angle and increasing the wettability [56]. Additionally, chitosan stabilizes HP and increases the penetration of HP into the tooth due to its mucoadhesive properties [57]. Thus, we hypothesize that chitosan enhanced the colour change effect of the experimental gels in comparison with the commercial gels with the same CP or HP content.

Delfino et al. [58] applied 3 different bleaching agents (10%, 16% CP, and 6.5% HP); the colour change obtained with the 16% CP gel at 21 days was similar to that obtained with the 10% CP gel and significantly higher than obtained with 6.5% HP. In addition, the colour changes on the 21st day were superior to those on the 7th day and similar to those on the 14th day. Another study evaluating home bleaching applications for 14 days revealed that 20% CP application induced a greater colour change than 7.5% HP; however, after 10 weeks, no differences in the colour change results were observed between the two treatments [59].

Almeida et al. [60] evaluated colour changes with a home bleaching gel containing 10% CP for 3 and 1.5 hours and one containing 6% HP for 1.5 hours and 45 minutes. The most effective treatment was achieved with 10% HP for 3 hours, while the smallest colour change occurred with 6% HP for 45 minutes. Similarly, we found that gels containing 16% CP provided more colour change than those containing 6% HP.

While theobromine and chitosan are widely used in medicine and dentistry, their combined use in tooth bleaching has not been previously reported. This present study is the first on this subject.

Theobromine and chitosan are presented as an alternative to the synthetic polymers added to bleaching gels in the market. Theobromine has been described recently as an alternative to the highly remineralizing fluorine, which is avoided due to toxicity. Chitosan can be used as a thickening agent and carrier, with bioadhesive, antioxidant, and antimicrobial effects.

Within the limitations of our study, it has been demonstrated that home bleaching gels containing chitosan and theobramine can be used to eliminate the negative effects of bleaching agents and increase bleaching efficiency.

One limitation of our study is the inability to fully mimic in vivo conditions, although the teeth were kept in an artificial saliva solution in an oven at 37°C during the bleaching process.

All bleaching applications were effective across all groups in our study. After bleaching, an insignificant increase was observed in the Ca concentration in groups treated with the experimental gels containing chitosan and theobromine. In contrast, a significant decrease in Ca was observed in groups treated with the BioWhiten Prohome (Group 3) and FGM Whiteness Perfect (Group 4) gels. Regarding the P concentration, a non-significant decrease was observed in the groups treated with the experimental gels. In contrast, a significant decrease was found in the groups treated with the BioWhiten Prohome (Group 3) and FGM Whiteness Perfect (Group 4) gels. Thus, regarding the colour and mineral changes, the best results were obtained in the group treated with the ECP gel (Group 1).

Ethics approval and consent to participate: XXX University Faculty of Dentistry Local Ethics Committee (decision 2022/309). Written informed consent was obtained from the participant.

Consent for publication: All authors agree and consent to the publication

Availability of data and material: We have all the survey data available

Competing interests: There is no conflict of interest

Funding: BAP project

Authors' contributions: Conceptualization: Gürsel Sürmelioğlu; Acquisition of data: Gürsel Sürmelioğlu; Analysis and interpretation of data: Gürsel Sürmelioğlu, Görkem Kervancıoğlu; Methodology: Gürsel Sürmelioğlu ; Project administration: Gürsel Sürmelioğlu, Görkem Kervancıoğlu; Resources: Gürsel Sürmelioğlu, Görkem Kervancıoğlu; Supervision: Gürsel Sürmelioğlu; Writing (original draft): Gürsel Sürmelioğlu, Görkem Kervancıoğlu; Writing (review/editing): Gürsel Sürmelioğlu. All authors read and approved the final manuscript.

CRediT Author Statement

Görkem Kervancıoğlu: Methodology, Resources, Writing - Original Draft, Investigation. Derya Surmelioglu: Conceptualization, Methodology, Formal analysis, Writing - Original Draft, Writing - Review & Editing, Supervision, Investigation.

There is no conflict of interest

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The Effect of Newly Developed Home Bleaching Gels on Tooth Colour and Mineral Alteration

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Abstract

Figures

INTRODUCTION

MATERIALS AND METHODS

Preparation of Samples

Selection of Teeth Used in the Study and Formation of Groups

Colour Measurement with a Spectrophotometer Device

SEM-EDX Analysis

Preparation of the Experimental Bleaching Gel

Artificial Saliva Preparation

Application of the Bleaching Procedure

Statistical Analysis

RESULTS

Analysis of Colour Change Values

Analysis of Mineral Changes

Calcium Mineral Findings

Phosphorus Mineral Findings

DISCUSSION

Mineral Analysis

Colour Analysis

CONCLUSION

Declarations

References

Additional Declarations

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