Abstract
Objectives
The objective of this study was to investigate the efficacy of tooth whitening and the effects on satisfaction with whitening treatment and esthetic self-perception of over-the-counter tooth whitening products.
Materials and methods
Fifty-six participants were randomly allocated to three groups based on the whitening product they used (toothpaste, pencil, or a combination of both). In this prospective study, alterations in tooth color were assessed using a spectrophotometer at three distinct time intervals (initial measurement, seven days, and 14 days after commencing the use of the whitening product). Simultaneously, the respondents were given the PIDAQ questionnaire to complete. Patient satisfaction with treatment characteristics (5-point Likert scale), and perception of side effects were assessed at the end of the study.
Results
Participants who used the whitening pen either alone or in combination with whitening toothpaste showed significant improvements in tooth color and whiteness index at seven and 14 days compared to those who used whitening toothpaste alone (p≤0.001). No significant differences were found between products in overall satisfaction with treatment, perception of final tooth color, and treatment comfort. Furthermore, with the exception of the psychological influence factor after 14 days (p≤0.001), there were no significant differences in the PIDAQ questionnaire scores between the whitening products at the different time points. However, many respondents (16.6%) reported oral mucosal sensitivity and a higher percentage (27.8%) reported tooth sensitivity during whitening pen application.
Conclusion
The combination of whitening toothpaste and whitening pen, as well as the whitening pen alone, showed effective objective color change results, but home whitening procedures did not significantly affect participants' self-perceived satisfaction or psychosocial outcomes depending on the product used.
Keywords: MeSH Terms: Tooth Bleaching Agents, Tooth Bleaching, Color, Patient Satisfaction, Toothpastes
Author Keywords: Color Measurement, Patient Satisfaction, Side Effects, Tooth Whitening, Toothpaste, Whitening Pen
Introduction
High esthetic expectations of patients and the desire for white teeth have led to an increasing number of teeth whitening procedures being performed in dental offices. In addition to in-office whitening techniques supervised by dentists, there is a growing market for teeth whitening products that promise quick and convenient whitening at home. Various products are available for home whitening, including toothpastes, rinses, flosses, toothbrushes, gums, trays, strips, and gels (1-7). Toothpaste is the most commonly used commercial product which can contain either various active ingredients such as abrasives, adsorbent particles, peroxides, enzymes, or optical agents. The primary whitening agents in toothpaste are usually abrasives such as CaCO3, SiO2, and Al2O3. Dental floss contains the abrasive silica as a whitening agent and is used to remove pigmentation from between teeth. Rinses usually contain low concentrations of hydrogen peroxide (1.5%). Chewing gums with bleaching effect contain abrasives, and their bleaching effect is attributed to the removal of surface discoloration. However, long-term use of such chewing gums may cause damage to the tooth surface. Another method available on the market is bleaching with universal trays, where the gel is applied in the tray which is worn for two to four hours a day. Some packages come with a small light (LED) that helps activate the gel. Bleaching strips contain low concentrations of hydrogen peroxide (5-14%). Bleaching gels, on the other hand, contain hydrogen peroxide or urea peroxide as bleaching agents and are often available in the form of a pen that is applied to the tooth surface with a small brush (1, 7, 8).
However, the actual efficacy of these over-the-counter tooth whitening agents remains questionable and controversial. Numerous studies have demonstrated the efficacy of whitening toothpastes and pens containing whitening agents compared to conventional toothpastes (1, 9). However, there is a lack of comparative studies showing which preparations, or their combination, are most effective in achieving the desired results (2-6).
Improper use of tooth whitening agents is associated with the occurrence of undesirable effects and sensations, such as excessive wear of dental tissues, irritation of periodontal and soft tissues, tooth sensitivity, cervical root resorption, crown fractures, effects on restorative materials (10). The extent of damage is influenced by factors such as the quality and concentration of the bleaching agent, the duration of application, the individual's response to the procedure, the bleaching technique used, and the presence of pre-existing conditions such as dentin hypersensitivity, abrasion/erosion, cervical caries, and existing dental restorations (10-13).
Quantitative analysis of tooth color changes and stability are essential for assessing the efficacy and effectiveness of the whitening technique (14, 15). Traditional color-measurement instruments such as spectrophotometers and colorimeters, as well as newer digital cameras, are utilized for objective assessment of color changes. These tools enable precise measurement and evaluation of color alterations. In dentistry, the most commonly used formulas for assessing the difference in color and whitening effect are as follows: CIELAB (ΔEab), CIEDE2000 (ΔE00) and Whiteness Index (WID). By employing these formulas, dentists and researchers can objectively measure and compare color changes in dental treatments, particularly teeth whitening procedures, thus ensuring a standardized approach to color evaluation (16-18). However, self-reported outcomes, such as satisfaction with dental esthetics and the impact on self-esteem and social behavior, are also crucial factors to consider. Combining both quantitative and self-reported data provides a comprehensive understanding of the success of the whitening procedure and its overall influence on the patient's well-being (14, 19). So far, few studies have examined the psychosocial effect of bleaching, and it remains unclear whether bleaching can affect patients' psychology or social relationships (15, 19-22).
Therefore, the primary objective of this study was to evaluate the efficacy of different home whitening products and their impact on patients' psychosocial well-being, as measured by the Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ). The second objective of the study was to assess patients' self-perceptions of satisfaction with treatment and all side effects associated with the use of over-the-counter tooth whitening products. The null hypothesis was that home tooth whitening would have no effect on patients' psychosocial well-being or their self-perception of treatment satisfaction and that there would be no whitening effect and no differences in whitening efficacy between the products tested.
Materials and methods
This prospective study was conducted among the patients of the Department for Restorative Dental Medicine and Endodontics, Study of Dental Medicine, University of Split, Croatia, between January and April 2020. The study was carried out in full accordance with ethical principles, including the World Medical Association Declaration of Helsinki (version 2008). It was approved by the Ethical Committee of the University of Split School Of Medicine, Split, Croatia. The study was performed following the Consolidated Standards of Reporting Trials guidelines (CONSORT). Participation was voluntary, anonymous, and without compensation, and all participants were informed about the background and the aim of the study. Prior to inclusion in the investigation, all participants provided their informed consent in writing.
Participants and materials
This study comprised a total of 56 patients, including 18 (32.1%) men and 38 (67.8%) women, with an age range of 20 to 41 years old (mean age: 24.49 ± 5.60). The inclusion criteria were as follows: intact upper anterior sextant teeth (teeth 13, 12, 11, 21, 22, 23), good general and oral health, absence of caries, periodontal disease, or dentinal hypersensitivity.
The study excluded individuals with damage to the oral mucosa, those allergic to specific ingredients of toothpastes and whitening agents, pregnant women, nursing mothers, and minors. Subjects with stained tetracycline teeth, dental fluorosis, and intrinsic causes of tooth discoloration, as well as those with developmental and acquired defects on their teeth, fixed prosthetic works, or orthodontic braces were also excluded. Furthermore, the study did not include subjects who had previously undergone teeth whitening procedures. Comprehensive medical and dental histories were obtained from each participant. Additionally, a structured questionnaire specifically designed for this study was administered, wherein all participants provided responses related to various factors: demographic factors (age and gender), lifestyle habits (smoking habit) and eating habits (consumption of coffee and tea).
By analyzing the power of the dependent t-test (difference in tooth brightness - L* before and after applying the combination of toothpaste and pencil) using the following parameters: significance level α = 0.05, equal number of subjects in all groups, and effect size Cohen's d = 1.19 (based on the obtained results), it was determined that at least 10 subjects per group were required to achieve an 80% power of the test. The sample size was increased to 20 subjects in order to avoid their potential loss during the duration of the study.
Subjects were randomly divided into three groups depending on the tooth whitening agent used following a block randomization procedure using computer software. The first group (n =19) used toothpaste with whitening effect Miradent Mirawhite Whitening Toothpaste Gel (Hager & Werken GmbH & Co. KG, Duisburg, Germany). The second group (n=18) used Miradent Mirawhite Shine Gel – tooth whitening pen (Hager & Werken GmbH & Co. KG, Duisburg, Germany) and a commercial toothpaste without whitening effect Colgate Cavity Protection (Colgate-Palmolive, New York, USA). While the third group (n = 19) used toothpaste and whitening pen at the same time, Miradent Mirawhite Whitening Toothpaste Gel and Miradent Mirawhite Shine Gel (Hager & Werken GmbH & Co. KG, Duisburg, Germany). All subjects used the same toothbrush during the study – Colgate SlimSoft (Colgate-Palmolive, New York, USA). The composition of the preparations used is shown in Table 1.
Table 1. Whitening products used in research.
| Whitening product | Manufacturer | Type | Ingredients |
|---|---|---|---|
| Miradent Mirawhite Whitening Toothpaste Gel | Hager & Werken GmbH & Co. KG, Duisburg, Germany | Toothpaste | Water, Sorbitol, Hydrated Silica, Propylene Glycol, Xylitol, Penta Sodium Triphosphate, Disodium Pyrophosphate, Tetracodium Pyrophosphate, Sodium C14 -16 Olefin Sulfonate, Aroma, Fluidine, Ksinija, CI 42090, CI 77891 |
| Miradent Mira White Shine Gel | Hager & Werken GmbH & Co. KG, Duisburg, Germany | Pen | Water, Glycerin, Silica, Sodium gluconate, Sodium citrate, Sodium chloride, Phthalimido peroxy caproic acid (PAP), Xanthan gum, Sodium methylparaben, Cellulose gum, Aroma |
Each participant received detailed instructions on oral hygiene and how to use the assigned whitening products. They were instructed to use the designated whitening agent and toothbrush for duration of 14 days. The toothpaste was to be used twice daily, in the morning and evening, for three minutes using the Bass method of brushing. The recommended amount of toothpaste was approximately 1 g (≈2 cm). Regarding the whitening pen, participants were instructed to apply it twice daily to a dry tooth surface, in the morning and evening, for 60 seconds. Subsequently, they were advised to rinse the gel off with water. Following the use of the pen, it was strongly advised not to eat or drink anything for the following 30 minutes. Throughout the study, the participants were explicitly instructed not to use any other means of maintaining oral hygiene and whitening agent apart from those products assigned to them for the whitening procedure.
Tooth color measurements
A Vita Easyshade digital spectrophotometer (VITA Easyshade V, Vita Zahnfabrik, Bad Sackingen, Germany) was used to determine tooth color. Color assessment was performed in three time points: (T0) baseline – before the use of the tested teeth whitening agents, (T1) seven and (T2) 14 days after the commencement of using tested whitening. Using the average measurement method, three measurements were performed for each subject and each sampling time on the central and lateral incisors and canines of the upper jaw (13, 12, 11, 21, 22, 23; n = 6) on the middle third of the labial surface of the tooth. The average of these three values was used as a measured value for statistical analysis. Between each measurement, the sensor tip was removed from the tooth surface, calibrated, and repositioned. The color was determined using the CIELab color space (L *, a *, b * values). The color reading was performed in the middle third of the tooth’s labial surface, in the same environment and with the same lighting conditions.
The color change between measurements in each group was estimated using the following values: ∆E∗ab=[(∆L*)2+(∆a*)2+(∆b*)2]1/2, ∆E00=[(ΔL’/KLSL)2+(ΔC’/KCSC)2+(ΔH’/KHSH)2+RT(ΔC’/SC*SH) (ΔH’/SC*SH)]1/2, and WID=0.511L*−2.324a*−1.1b* (22, 23, 17, 18).
Long-term use and monitoring of tooth color change as assessment of tooth color stability after the use of the tested agents could not be performed due to the epidemic of COVID-19 disease.
Assessment of participants' satisfaction with the treatment, esthetic self-perceptions and undesirable and adverse effects
At the end of the study (14 days after starting the use of the whitening agent), the participants completed a questionnaire to assess their satisfaction with the treatment. They rated tooth color, treatment duration, treatment comfort, and overall satisfaction using a Likert scale ranging from 1 to 5 (1 - not satisfied at all, 5 - I am completely satisfied).
Additionally, at the end of the study, the participants provided feedback on the sensations they experienced during the treatment. They were asked about sensations such as burning, irritation, tooth sensitivity, taste, texture, dry mouth, presence of ulcerations (peeling, burning of the mucous membranes), and the perceived whitening effect. The responses to these sensations were categorical (yes, no, I don't know). The questionnaire also included questions about the participants' intentions regarding repeating the treatment and recommending it to their relatives and friends, which were answered categorically (yes, no, I don't know).
Questionnaires on treatment satisfaction and the sensations experienced during the use of whitening agents were adapted from similar research conducted on the topic of teeth whitening and the use of different types of toothpaste (4, 24-26).
To evaluate the psychosocial aspect of the respondents', a questionnaire on the psychosocial impact of dental esthetics (PIDAQ) was used (19, 21). The PIDAQ questionnaire comprised a total of 23 questions, which were divided into four categories: esthetic concerns, social impact, psychological impact, and dental self-confidence. Each item in the PIDAQ questionnaire was rated using the Likert scale, ranging from 0 to 4, with 0 indicating "no impact at all" and 4 indicating "maximum impact." Claims related to dental self-confidence were affirmative, while others were negative. The questionnaires were administered at three time points: at the beginning of the study, after seven days, and after 14 days after the commencement of using the whitening agent.
Statistical data processing
The collected data were entered into a pre-existing Microsoft Excel 2007 table (Microsoft Corporation, Redmond, Washington, USA) and coded for further analysis using the statistical package for social sciences (SPSS, version 26, IBM Corp, Armonk, New York, USA). The initial analysis of the results involved using descriptive statistics. Continuous variables were presented as either the mean and standard deviation or the median and interquartile range, while categorical variables were expressed as numbers and percentages. The Shapiro-Wilks test was used to assess the normality of the distribution of quantitative variables. Differences between groups and within the group were compared using the Kruskal-Wallis one-way analysis of variance (ANOVA) and Friedman two-way ANOVA. Differences between categorical variables were evaluated using the χ2 test and Fisher test as appropriate. Furthermore, a linear regression analysis was performed to examine the relationship between respondents' satisfaction with the treatment and whitening effect and their demographic characteristics, tooth color measures, and aesthetic concerns, social and psychological impact, and dental confidence. All statistical analyses were performed with a significance level set at p<0.05.
Results
The flow diagram of the study with parallel randomized three groups (that is, enrollment, intervention allocation, follow-up, and data analysis) is presented in Figure 1.
Figure 1.
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Flowchart of participant’s recruitment and follow-up
The study involved 56 subjects divided into three groups depending on the agent used. No statistically significant difference in gender (p=0.836) and age (p=0.116) was observed among different groups of respondents (Table 2).
Table 2. Descriptive statistics of life habits and demographic data of respondents.
| Characteristic | Whitening product | ||||
|---|---|---|---|---|---|
| WT | WP | WT + WP | Total | ||
| Number of subjects | 19 (33.9%) | 18 (32.1%) | 19 (33.9%) | 56 (100%) | |
| Age (years) | 25.83±3.59 | 24.56±3.16 | 24.21±3.82 | 24.49±5.60 | |
| Gender | Male | 6 (31.5%) | 5 (27.7%) | 7 (36.9%) | 18 (32.1%) |
| Female | 13 (68.4%) | 13 (68.4%) | 12 (63.1%) | 38 (67.8%) | |
| Values are shown as number and percentage ore mean and standard deviation. Abbreviations: WT – whitening toothpaste, WP – whitening pen, WT + WP – whitening toothpaste and pen. | |||||
Table 3 shows the median values of total shade change (ΔEab and ΔE00) and whiteness index (ΔWID) for each evaluation period and the bleaching agents tested. The resulting change in tooth color (∆E*ab, ΔE00) and change in whiteness index (ΔWID) showed a clinically significant change in tooth color compared to baseline values (p≤0.001) for all bleaching agents tested at the time points evaluated (T1 and T2). A statistically significant increase in overall shade change (ΔE*ab and ΔE00) and whiteness index (ΔWID) for each evaluation time point (T1 and T2) compared to baseline values was confirmed in subjects using a bleaching pen and a combination of bleaching pen and toothpaste compared to those using bleaching toothpaste (p≤0.001).
Table 3. Changes of color by ΔE00, ΔE*ab, and ΔWID by the group in different periods.
| Color measures | Whitening product | p-value | ||
|---|---|---|---|---|
| WT | WP | WT+WP | ||
| ΔEab(T1-T0) | 1.76 (1.00-3.13)a,b,A | 3.73 (2.23-6.00)a,A,C | 3.78 (2.57-5.64)b,A,C | ≤0.001* |
| ΔEab(T2-T0) | 1.97 (1.26-3.15)a,b,A,B | 4.55 (2.49-6.94)a,A,B | 4.27 (2.86-6.19)b,A;B | ≤0.001* |
| ΔEab(T2-T1) | 1.42 (0.81-2.25)B | 1.58 (0.91-2.53)B,C | 1.64 (0.98-2.56)B,C | 0.358 |
| p-value | ≤0.001* | ≤0.001* | ≤0.001* | |
| ΔE00(T1-T0) | 1.10 (0.63-1.99)a,b,A | 2.38 (1.33-4.00)a,A,C | 2.55 (1.61-3.88)b,A,C | ≤0.001* |
| ΔE00(T2-T0) | 1.22 (0.81-2.11)a,b.A,B | 2.88 (1.58-4.41)a,A,B | 2.80 (1.94-3.99)b,A | ≤0.001* |
| ΔE00(T2-T1) | 1.07 (0.57-1.73)B | 1.26 (0.70-1.93)B,C | 1.28 (0.80-2.12)A,C | 0.230 |
| p-value | ≤0.001* | ≤0.001* | ≤0.001* | |
| ΔWID(T1-T0) | 0.25 (-0.62-1.39)a,b,A | 2.80 (1.29-4.80)a,A,C | 2.85 (0.93-4.11)b,A,C | ≤0.001* |
| ΔWID(T2-T0) | 1.17 (-0.12-2.02)a,b,A,B | 3.16 (1.64-4.77)a,A,B | 3.16 (1.61-4.75)b,A,B | ≤0.001* |
| ΔWD(T2-T1) | 0.44 (-0.26-1.76)B | 0.37 (-0.65-1.08)B,C | 0.32 (-0.62-1.53)B,C | 0.362 |
| p-value | ≤0.001* | ≤0.001* | ≤0.001* | |
| Values are shown as median and interquartile range. The same lowercase letter in a row indicates statistical significance between different teeth whitening agents and same capital letters indicate a significant difference among the evaluation periods (p˂0.05). Abbreviations: T0 - before treatment; T1 - 7 days after the commencement of use; T2 -14 days after the commencement of use; WT – whitening toothpaste, WP – whitening pen, WT + WP – whitening toothpaste and pen. | ||||
The median and interquartile ranges of respondents' satisfaction with the whitening procedure are shown in Table 4. The only statistically significant difference was found between the whitening pen and whitening toothpaste groups in length of treatment (p=0.027).
Table 4. Respondents' satisfaction with different characteristics of whitening agent and procedure.
| Characteristics | Whitening product | |||
|---|---|---|---|---|
| WT | WP | WT + WP | p-value | |
| Final tooth color | 4.00 (3.00-4.00) | 4.00 (3.00-4.25) | 4.00 (3.00-4.00) | 0.632 |
| Length of treatment | 4.00 (3.00-4.00)a | 5.00 (3.75-5.00)a | 4.00 (3.00-5.00) | 0.027* |
| Comfort during treatment | 5.00 (4.00-5.00) | 5.00 (4.00-5.00) | 5.00 (3.00-5.00) | 0.541 |
| Overall satisfaction with treatment | 4.00 (3.00-5.00) | 4.50 (4.00-5.00) | 4.00 (3.00-5.00) | 0.103 |
| Values are shown as median and interquartile range. The same lowercase letter in a row indicates statistical significance between different teeth whitening agents (p˂0.05). Abbreviations: T0 - before treatment; T1 - 7 days after the commencement of use; T2 -14 days after the commencement of use; WT – whitening toothpaste, WP – whitening pen, WT + WP – whitening toothpaste and pen. | ||||
Table 5 shows the side effects experienced by the respondents when using the different teeth whitening products. Tooth sensitivity was noted by 27.8% of the respondents who used the whitening pen and by 21.1% of the respondents who used the combination of whitening toothpaste and pen. A change in taste was noted by 16.6% and mucosal inflammation by 11.1% of respondents who used whitening toothpaste. The majority of respondents liked the whitening product used and would be happy to recommend it to others and use it again (84.2% - WT, 89.4% - WT +WP and 94.7% - WP; 84.2% - WT, 89.4% - WT +WP and 94.7% - WP). All subjects who used a whitening pen noticed the whitening effect on their teeth (100%), as well as 94.7% of subjects who used a combination of whitening toothpaste and a pen, while only 63.1% of subjects who used whitening toothpaste noticed the whitening effect.
Table 5. Adverse and undesirable side effects experienced by the respondents.
| Side effects | Whitening product | |||
|---|---|---|---|---|
| WT | WP | WT + WP | p-value | |
| Burn | 1 (5.2%) | 1 (5.8%) | 2 (10.5%) | 0.780 |
| Irritation | 2 (10.5%) | 0 (0%) | 2 (10.5%) | 0.316 |
| Oral mucosa sensitivity | 2 (10.5%) | 3 (16.6%) | 3 (15.7%) | 0.810 |
| Tooth sensitivity | 1 (5.2%) | 5 (27.8%) | 4 (21.1%) | 0.183 |
| Unpleasant taste | 0 (0%) | 0 (0%) | 2 (10.5%) | 0.133 |
| Unpleasant texture (sandy, rough, sticky) | 1 (5.2%) | 0 (0%) | 0 (0%) | 0.371 |
| Peeling, roughness of the oral mucosa (cheek, tongue, lips, gums) | 1 (5.2%) | 0 (0%) | 2 (10.5%) | 0.361 |
| Dry mouth, thirst | 3 (15.7%) | 1 (5.8%) | 1 (5.2%) | 0.435 |
| Ulcers on the oral cavity / wounds | 0 (0%) | 2 (11.1%) | 0 (0%) | 0.112 |
| Itching (cheek, tongue or lips) | 0 (0%) | 0 (0%) | 0 (0%) | n.a. |
| Tingling (cheek, tongue or lips) | 2 (10.5%) | 0 (0%) | 1 (5.2%) | 0.364 |
| Mouth taste change | 1 (5.2%) | 3 (16.6%) | 0 (0%) | 0.134 |
| Values are shown as number and percentage. * Chi-square test or Fisher's test, df=2; p<0.05. Abbreviations: n.a. – non acceptable; WT – whitening toothpaste, WP – whitening pen, WT + WP – whitening toothpaste and pen. | ||||
All tested whitening products showed a statistically significant improvement in the psychological impact factor according to the PIDAQ scale after 14 days of usage (p≤0.001). Additionally, for the whitening pen and the combination of whitening pen and toothpaste, the significance persisted even after seven days of use (p≤0.001). However, no differences were found in the other PIDAQ dimensions when comparing the different times of use for the tested whitening products (Table 6).
Table 6. PIDAQ results at different time points.
| Whitening product | Dimension | Time points | |||
|---|---|---|---|---|---|
| Baseline – T0 | 7 days – T1 | 14 days – T2 | p-value | ||
| WT | Dental Self-Confidence | 15.00 (8.00-18.00) | 15.00 (9.00-18.00) | 16.00 (10.00-21.00) | 0.081 |
| Social impact | 0.00 (0.00-5.00) | 0.00 (0.00-3.00) | 1.00 (0.00-6.00) | 0.081 | |
| Psychological Impact | 5.00 (3.00-9.00)a | 5.00 (4.00-8.00) | 4.00 (3.00-8.00)a | ≤0.001* | |
| Esthetic Concern | 0.00 (0.00-1.00) | 0.00 (0.00-2.00) | 0.00 (0.00-3.00) | 0.693 | |
| WT + WP | Dental Self-Confidence | 12.00 (9.00-18.00) | 13.00 (10.00-18.00) | 12.00 (10.00-20.00) | 0.339 |
| Social impact | 1.00 (0.00-5.00) | 1.00 (0.00-5.00) | 1.00 (0.00-3.00) | 0.985 | |
| Psychological Impact | 5.00 (3.00-8.00)a,b | 4.00 (2.00-7.00)b | 4.00 (2.00-6.00)a,b | ≤0.001* | |
| Esthetic Concern | 2.00 (0.00-4.00) | 2.00 (0.00-3.00) | 2.00 (0.00-3.00) | 0.479 | |
| WP | Dental Self-Confidence | 15.00 (13.00-19.00) | 14.00 (12.00-18.00) | 17.00 (12.00-19.00) | 0.094 |
| Social impact | 2.50 (0.00-4.00) | 2.50 (0.00-6.00) | 2.50 (0.0-7.00) | 0.451 | |
| Psychological Impact | 8.00 (3.00-11.75)a | 6.50 (3.00-9.00)c | 4.00 (2.75-6.75)a.c | ≤0.001* | |
| Esthetic Concern | 0.50 (00-4.75) | 1.50 (0.00-3.00) | 1.00 (0.00-3.75) | 0.784 | |
| Values are shown as median and interquartile range. The same lowercase letter in a row indicates statistical significance between different time points (p˂0.05). Abbreviations: T0 - before treatment; T1 - 7 days after the commencement of use; T2 -14 days after the commencement of use; WT – whitening toothpaste, WP – whitening pen, WT + WP – whitening toothpaste and pen. | |||||
The dependence of satisfaction with the whitening agent (final tooth color, overall satisfaction with the treatment) was determined using the linear regression model and presented in the form of Pareto diagrams (Figure 2). The effects of all observed demographic and lifestyle variables, as well as the PIDAQ variables that appeared as predictor variables, were observed for age (β=-0.089, SE=0.012, p≤0.001), gender-female (β=0.373, SE=0.174, p=0.006), and dental self-confidence (β=-0.024, SE=0.012, p=0.042) on overall satisfaction with treatment. On tooth color satisfaction, age (β=0.109, SE=0.016, p=0.033) and social influence of PIDAQ (β=-0.089, SE=0.012, p≤0.001) have a significant influence.
Figure 2.
_300-315-f2.jpg)
Multiple regression analysis results - the influence of sociodemographic factors, color changes, and PIDAQ variables on satisfaction with treatment and achieved tooth color
Discussion
The use of commercially available whitening products for home use, such as toothpaste, gel, pen, tape, and rinsing liquid, can serve as an alternative for correcting mild tooth stains (1). This study aimed to evaluate and compare the effectiveness of different commercially available teeth whitening over-the -counter agents (toothpaste, pen, and their combination) and to assess the satisfaction of respondents with the treatment and the achieved effect. The subjects who used the pen and a combination of toothpaste and pen experienced a significant color change (ΔE) after seven and 14 days of usage compared to those who used only whitening toothpaste. Based on the results obtained, we can conclude that the initial hypotheses were not confirmed, and the means used proved to be effective with significant differences between them.
Over-the counter whitening products typically contain lower levels of the whitening agent and are applied to the tooth with a brush, tape, or toothbrush, usually requiring application twice a day for up to two weeks. External stains on the tooth surface can be removed with some abrasive agents found in toothpaste, while internal stains can be eliminated through oxidation. The whitening toothpaste used in this study contains abrasive and chemical agents such as pyrophosphate and hydrated silicon. Pyrophosphates have a strong binding affinity and effectively remove components causing tooth color staining (18). Hydrated silicon possesses cleaning abilities and is more effective in removing stains from enamel and dentin compared to other abrasives (1). The pen used in this study contains peroxycaproic acid (PAP), which has a high oxidation potential and is crucial for the whitening process as it neutralizes the double organic bonds responsible for tooth discoloration (27). Additionally, the pen contains the active ingredient sodium chlorite which releases a small amount of chlorine dioxide in the presence of acids (28). Compared to hydrogen peroxide, PAP gel exhibits a similar whitening effect while being less harmful to enamel and oral mucosa (29).
The use of whitening agents resulted in a noticeable change in tooth color (ΔE) after seven and 14 days of use. However, the subjects who used a pen and a combination of pen and toothpaste experienced a higher color change compared to those who used toothpaste alone. Clinically significant tooth color change, as defined by ∆E*ab≥1.2, ΔWID≥0.72, and/or ΔE00≥0.8, can be visibly noticed by human eyes and is essential in evaluating the effectiveness of whitening agents (30). Therefore, after seven days of using all tested whitening products, the changes were visible to the naked eye. However, after 14 days of use, all whitening agents showed a greater color change than that observed after seven days, with significant differences between them. Greater color changes were observed in subjects who used the whitening pen and a combination of products after seven and 14 days of use, compared to those who used whitening toothpaste alone.
The evaluation of the effect of whitening toothpastes and other home whitening agents can be conducted through in vitro studies using extracted teeth or through in vivo clinical trials. However, the available literature presents contradictory efficacy results from in vitro studies. For instance, one study (31) confirmed the whitening effect of several commercially available whitening toothpastes in India after four weeks of use. Similarly, Vaz et al. (32) demonstrated that all whitening toothpastes achieved effective tooth whitening compared to toothpaste without additional whitening agents. According to their findings, the best bleaching effect was achieved with microbeads, followed by hydrogen peroxide and blue covarine. They have also emphasized that continuous use of these products is necessary to achieve a more pronounced and better whitening effect.
It is important to note that while in vitro studies provide valuable insights into the potential effects of whitening agents on extracted teeth, the outcomes might not perfectly mirror real-world situations and clinical effectiveness. Thus, the findings of in vitro studies should be considered in conjunction with results of in vivo clinical trials to obtain a comprehensive understanding of the actual impact of whitening agents on tooth color in practical usage scenarios (33). There have been several clinical studies examining the clinical effect of whitening toothpastes (34-38) and whitening pens (29). Horn et al. (37) observed the whitening effect of four toothpastes after 15 days of use. However, they did not observe that the use of any whitening toothpastes led to a visible change in tooth color. Similarly, Pintado-Palomino et al. (38) found no difference in color change after four weeks of using two toothpastes with a whitening effect compared to conventional toothpaste without any effect. In contrast, other studies in the literature have confirmed the effectiveness of various whitening toothpastes (39, 40). Bizhang et al. (41) evaluated the effect of a gel preparation containing peroxycaproic acid and found a significant effect after only one use. In this study all subjects who used a pen noticed the whitening effect on their teeth (100%), likewise 94.7% of subjects who used a combination of toothpaste and pen. Respondents were more satisfied with the results obtained after using the pen and the combination of pen and toothpaste than with toothpaste alone (p≤0.001).
The most common unfavorable side effects of the use of teeth whitening products are dentinal hypersensitivity and gingival irritation. Fiorillo et al. (42) have stated that teeth whitening procedures should be avoided in patients who already suffer from dental hypersensitivity. Unfortunately, the effect on the hard tissues of the teeth can contribute to the development of hypersensitivity. However, they have also emphasized that the esthetic effect of teeth whitening is always present, whether it is performed at home or by professional treatments. They believe that improving a smile, in this case by teeth whitening, also enhances the quality of life for patients. In this study, 27.8% of respondents who used the pen complained of tooth sensitivity during use. Likewise, 21.1% of respondents who used a combination of toothpaste and pen complained of tooth sensitivity. Only 5.2% of respondents who used toothpaste alone complained of tooth sensitivity. Burning, irritation, and tenderness within the oral cavity were experienced by less than 10% of the subjects, regardless of the materials used. The reported prevalence/incidence of increased tooth hypersensitivity varies between studies, ranging from 0% to 100% (42), although most studies reported a prevalence of 15% to 80% (43). In most cases, tooth hypersensitivity is transient and tends to subside within a few days after completing the whitening treatment (44-46).
The PIDAQ questionnaire was originally developed for use in patients undergoing orthodontic therapy (47). However, the measured dimensions can also be applied to subjects using tooth whitening agents (20, 21). Our research showed that the values of the PIDAQ questionnaire for the most of examined dimensions between means for each examined time did not show significant results. The first factor, "dental self-confidence," showed a positive whitening effect for all tested agents between baseline values and those obtained after seven days of use but it was not statistically significant. Dental self-confidence is a positive dimension of the PIDAQ questionnaire that measures the impact of dental aesthetics on an individual's self-confidence. The appearance of the mouth and smile play a significant role in assessing the attractiveness of the face, contributing to improved self-confidence. PIDAQ measures three additional negative values of the psychosocial impact dimension: social impact, psychological impact, and esthetic concern. Social impact assesses potential problems that an individual may face in social situations due to a subjectively unfavorable tooth appearance. Psychological influence assesses feelings of inferiority or dissatisfaction an individual may experience compared to others. Esthetic concern implies the concern or disapproval that arises when an individual faces a mirror or views photographs and/or videos (21). In this research, a significant reduction in the whitening effect on the psychological impact was observed after 14 days of use for all tested products. However, for the whitening pen and the combination of products, a favorable effect was noticed even after just seven days of use (p≤0.001). This indicates that these specific whitening agents had a quicker and more positive impact on the psychological aspect compared to other tested products, which required longer usage to show similar effects. Bersezio et al. (19) also stated in their study that the total value of the PIDAQ questionnaire did not show significant differences for each time examined. However, their results showed that one week after bleaching, there was a statistically significant difference in all measurement parameters (p<0.03), while after one month, all parameters were statistically significantly higher except social impact (p<0.001). In contrast study, Angel et al. (21), by comparing the efficacy of 6% H2O2 gel and 37.5% H2O2 gel, found significant changes in the value of the PIDAQ questionnaire after whitening compared to baseline. Dental self-confidence significantly improved after one week, one month, and three months compared to baseline (p<0.001). Social impact, psychological impact, and esthetic concerns were significantly reduced (p<0.09; p<0.001; p=0.001). Also, Fernandez et al. (20), who had compared the effect of 6% and 35% H2O2 gel, obtained statistically significant results for all teste the values of the PIDAQ questionnaire for each study time (p<0.001).
In this study, it was undeniably confirmed that the effectiveness of teeth whitening is not necessarily a good indicator of patient satisfaction. While teeth whitening products may produce visible changes in tooth color, patient satisfaction with the treatment can be influenced by various factors beyond the whitening effect alone. Sociodemographic characteristics and life style habits can play significant roles in determining how satisfied patients are with the overall outcome of the teeth whitening procedure (9, 48). In this study, a positive association of satisfaction with the whitening treatment was observed in female gender (β=0.373, SE=0.174, p=0.006). On the other hand, a negative association with age was observed for both examined variables: total satisfaction (β=-0.089, SE=0.012, p≤0.001) and color satisfaction (β=0.109, SE=0.016, p=0.033). Additionally, there was no correlation found between the change in tooth color and satisfaction with the treatment or the achieved tooth color. Similar to our research, Heinisch et al. (49) also did not find a positive correlation between the whitening effect and patient satisfaction. The degree of satisfaction is difficult to predict due to individual preferences and expectations that may not always align with reality. Patients often express satisfaction with the final treatment result in ways that therapists may not expect (50).
This study has several limitations. First, the study was conducted on a relatively small number of subjects, which may limit the generalizability of the results to a larger population. To improve the strength of the study, future research should consider increasing the sample size to obtain more representative results. Second, the study included only a limited number of commercially available bleaching products. To obtain a more comprehensive picture of the effectiveness of different bleaching agents, further studies should include a wider range of commercially available products. In addition, the study observation period was relatively short, and no long-term follow-up was conducted to assess color stability over time. The original plan was to assess tooth color and subject satisfaction one month after discontinuation of bleach use to investigate color stability. However, the study was discontinued due to the pandemic caused by the Covid 19 virus, thus further highlighting the importance of considering some external factors that may impact research timelines and study outcomes.
Conclusions
With the limitations of this in vivo study, it can be concluded that the use of all tested whitening products result in a change in tooth color after 14 days of use. Subjects who used the whitening pen and the combination of whitening toothpaste and pen experienced a significant increase in tooth color compared to those who used toothpaste alone. However, none of the tested products and their combinations had a significant positive impact on participants' satisfaction with the whitening procedure, tooth color, or esthetic perception. It was observed that patients who used the whitening pen reported the greatest number of side effects, thus pointing out the need to adhere to the manufacturer's instructions and limit its use accordingly. In conclusion, over-the-counter products for home use can help maintain the bright color of teeth, but their impact on satisfaction and esthetics may vary among individuals. Further research and considerations of individual factors are needed to optimize teeth whitening procedures and outcomes.
Acknowledgments
Ethical approval: The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Ethics Committee of School of Medicine, University of Split, Split, Croatia (Class: 003-081 20-03 I0005: No: 2 181-198-03-04-20-0067).
Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.Data Availability Statement: The data that support the findings of this study are available upon request from the authors.
Acknowledgments: The authors would like to express their gratitude to Klaudija Primorac, special territory export manager by Hager & Werken Corporation for generously donating the whitening products used in this study. This study was presented at the 4th International Congress of the Department of Endodontics and Restorative Dentistry, School of Dental Medicine, University of Zagreb in cooperation with the Croatian Society for Minimal Interventional Dental Medicine (23–24 October 2020, Zagreb, Croatia) as an oral presentation, and was written from the results of the diploma thesis: Popovic, S. Evaluation of effectiveness for different tooth whitening agents [undergraduate diploma thesis]. Split: University of Split, School of Medicine; 2020.
Footnotes
Conflicts of Interest: The authors declare no conflict of interest.
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