Efficacy of a Novel Stannous Fluoride Toothpaste Stabilized With Nitrate and Phosphates (SNaP) in Extrinsic Tooth Stain Removal: A Randomized Controlled Trial

Augusto R. Elías-Boneta, DMD, MSD; Luis R. Mateo, MA; Robert D’Ambrogio, BS; Guofeng Xu, PhD; Carl P. Myers, PhD; Yun-Po Zhang, PhD, DDS (Hon); and Bayardo García-Godoy, DMD, MSc

Stannous fluoride (SnF₂) dentifrices have shown an ability to reduce gingival inflammation, control plaque bacteria, and contribute to whole-mouth health.^1-3 However, despite being appreciated for their multifunctional benefits, SnF₂dentifrices have been associated with a higher incidence of extrinsic tooth staining compared to sodium fluoride formulations,⁴ which can effectively deliver fluoride for caries prevention without the cosmetic issues observed with stannous fluoride. Tooth color depends on both the intrinsic color of the teeth and any extrinsic stains that may develop on the tooth surface.⁵ Intrinsic stains are caused during the formation of teeth. Extrinsic staining can result from smoking, consumption of colored food and drinks, aging, or exposure to metallic cations that can form colored compounds upon exposure to sulfur-containing compounds found naturally in the mouth, such as stannous ions, which is a risk associated with SnF₂ dentifrices.^6-8 To overcome this risk, different formulation methodologies for stannous fluoride have been utilized, and recent studies and advances in dentifrice formulations have demonstrated that a dentifrice containing stabilized SnF₂offers stain prevention and removal benefits³ in addition to prevention of caries, plaque bacteria, gingivitis, and dentin hypersensitivity.^6,7

Smile esthetics can help motivate effective oral care routines.⁹ Whitening procedures and the use of whitening products have shown to improve oral care routines and oral health.^10,11 An increasing number of oral care products focus on teeth whitening in addition to the prevention of caries and gingivitis. The whitening agents commonly used include abrasives for the mechanical removal of stains,^12,13 anti-redeposition agents to prevent the deposition of chromophores,^2,13 colorants that impart white color,^2,13 proteases for degradation of proteins,^2,13 peroxides for oxidation of organic chromophores,^13,14 and surfactants for removal of hydrophobic compounds from tooth surface.¹⁵

Colgate has developed a formula, a novel stannous fluoride toothpaste stabilized with nitrate and phosphates (SNaP)¹⁶ to help prevent tooth staining and remove extrinsic stains. The new SNaP dentifrice is a promising option for effective whitening of teeth while offering protection from caries, gingivitis, and dentin hypersensitivity as well as consumer preferred flavor.^17-19

The SNaP formula is designed to prevent stains and whiten in three ways. The stabilized formula preserves the active stannous fluoride and does not oxidize to help prevent stain occurrences; it features a polyphosphate system to prevent stain buildup without compromising the active system; and a high cleaning silica system works to safely remove extrinsic stains from enamel. In the present study, the differences between SNaP and regular fluoride toothpaste for extrinsic stain removal efficiency were measured via the Lobene stain index.²⁰

Study Design

A phase III, randomized, single-center, two-cell, double-blind, parallel-group, and 1:1 allocation ratio clinical study was conducted to evaluate the extrinsic tooth stain removal efficacy of the SNaP (test) toothpaste (Colgate-Palmolive Co., colgatepalmolive.com) versus a negative control, commercially available fluoride toothpaste containing 0.76% sodium monofluorophosphate (Colgate-Palmolive Co.) in adults after 3 and 6 weeks of product use.

Ethics

This protocol was reviewed and approved by the U.S. Investigational Review Board, Inc. (U.S. IRB, Inc.^®), 6400 SW 72 Court, Miami, Florida 33143. All study participants signed an informed consent form.

Participant Inclusion and Exclusion Criteria

Healthy patients were screened to take part in the study. Eligible participants signed an informed consent form, were in good general health, were male and female individuals aged 21 to 70 (inclusive), presented 12 scorable natural anterior teeth, had a minimum mean composite Lobene index score of 1 or greater, were available for the duration of the study, and illustrated clinical evidence of a tendency to form extrinsic stain on anterior teeth.

Participants were excluded from the study if they met any of the following conditions: presence of orthodontic bands or partial removable dentures; presence of tumors of the soft or hard tissues of the oral cavity; presence of advanced periodontal disease, characterized by purulent exudate, tooth mobility, and/or extensive loss of periodontal attachment or alveolar bone; presence of five or more carious lesions requiring immediate restorative treatment; use of antibiotics or stain-inducing medications at any time during the month prior to entry into the study; participation in any other clinical study or test panel within the month prior to entry into the study; self-reported pregnancy or breastfeeding; received a dental prophylaxis in the 4 weeks prior to the baseline examination; history of allergies to oral care/personal care consumer products or their ingredients, including hydrogen peroxide; current use of any prescription medications that might interfere with the study outcome; history of alcohol and/or drug abuse; or exposure to a tooth whitening procedure in the last 3 months.

Setting

The study period was from July 27, 2020, to September 15, 2020. The study was conducted in Trujillo Alto, San Juan Metropolitan Area, Puerto Rico.

Procedures

Qualifying participants were randomly assigned to treatment groups using a computer-generated randomization list. Qualifying individuals and all clinical study site personnel were blinded to product assignment. Toothpastes (test and control) were covered with a white adhesive label overwrap to conceal product identity. The label information on each tube consisted of a toothpaste code (ie, study group code), instructions for at-home use, and safety information, including emergency contact information. No at-home instructions were provided as to the method of brushing other than to brush twice a day for 2 minutes each time.

Data Collection

Participants were sequentially recruited at a dental office in Trujillo Alto, Puerto Rico. An experienced examiner (Dr. Arturo Elías-Boneta) collected their data from July 27, 2020, to September 15, 2020. Following baseline assessments of stain and safety, participants were randomized to one of two treatment groups: (1) SNaP toothpaste or (2) a negative control, commercially available fluoride toothpaste containing 0.76% sodium monofluorophosphate. Colgate-Palmolive Co. provided the allocation list of the product codes, which was concealed in a white envelope. All office personnel and the examiner were blinded, except for the person in charge of product distribution.

Participants were instructed to brush with their assigned product twice daily for the duration of the study (6 weeks). They were required to bring their product kit boxes to each visit, where the toothpaste tubes were weighed in a calibrated balance by the site staff to monitor and record compliance.

Sample Size

The sample size of 80 participants (40 per group) was determined based on a standard deviation for the response measure of 0.51, a significance level of α = 0.05, a 10% attrition rate, and an 80% power level. The study was powered to detect a minimal statistically significant difference between the study group means of 20%.

Assessment

The primary outcome was a mean reduction of extrinsic tooth stain via the Lobene composite stain index, stain area index, and stain intensity index after unsupervised brushing two times daily (morning and evening) for a period of 6 weeks. An experienced dental examiner blinded to product allocation codes used the Lobene stain index to evaluate extrinsic stain and soft- and hard-tissue safety at baseline, week 3, and week 6 to assess product efficacy.

Using a standard method described by Lobene,²⁰ each tooth was scored separately using a four-point area and intensity scale range as follows: Stain Area: 0 = no stain detected, 1 = stain up to one third of the region, 2 = stain up to two thirds of the region, and 3 = stain over more than two thirds of the region. Stain Intensity: 0 = no stain, 1 = light stain (yellow tan), 2 = moderate stain (medium brown), and 3 = heavy stain (dark brown/black).

Each participant's mean Lobene composite stain index score, comprising stain intensity and stain area, was calculated. The sum of the product (Area*Intensity) scores was divided by all sites assessed.

Statistical Analysis

Statistical analyses were performed on the Lobene composite stain index, Lobene stain area index, and Lobene stain intensity index scores. Comparisons of the treatment groups were performed using a chi-square analysis for gender and an independent t-test for age. Comparisons of the treatment groups with respect to baseline Lobene composite stain index, Lobene stain area index, and Lobene stain intensity index scores were performed using an independent t-test.

Within-treatment comparisons of the baseline versus follow-up Lobene composite stain index, Lobene stain area index, and Lobene stain intensity index scores were performed using paired t-tests. Comparisons of the treatment groups concerning baseline-adjusted Lobene composite stain index, Lobene stain area index, and Lobene stain intensity index scores at the follow-up examinations were performed using analysis of covariance (ANCOVA). All statistical tests of hypotheses were two-sided and employed a level of significance of α = 0.05.

Eighty (n = 80) participants entered the clinical study, 78 individuals completed it. The recruitment period was July 27, 2020, to August 2, 2020. As stated earlier, the study period was from July 27, 2020, to September 15, 2020. The trial stopped at the end of the study period. Figure 1 shows the enrolled study population presented as a Consolidated Standards of Reporting Trials (CONSORT) flow diagram. The reasons for not completing the study were not product related, with one participant failing to keep a study appointment, while a second one relocated. Table 1 presents a summary of the age and gender of the study population.

Participant mean Lobene composite stain, stain area, and stain intensity index scores at baseline are shown in Table 2. The per protocol population was analyzed, and observations at 3 weeks and 6 weeks are presented in Table 3 and Table 4, respectively. During the 6-week study period, 100% of the patients in the test group experienced a reduction in stain (composite stain index), while 95% in the negative control group experienced an increase in stain.

Baseline

No statistically significant difference was indicated between the two treatment groups with respect to either gender (P = .241) or age (P = .985) characteristics (Table 1). No statistically significant difference was indicated between the treatment groups with respect to the mean Lobene composite stain index (P = .615), Lobene stain area index (P = .396), and Lobene stain intensity index (P = .817) (Table 2).

Results at 3 Weeks

After 3 weeks of product use, the percent reductions in Lobene composite stain index scores from baseline were 24.4% for the test group and 0.5% for the negative control group (Table 3). The percent reduction from baseline observed for the test group was statistically significant (P < .001). However, the percent reduction from baseline observed for the negative control group was not statistically significant (P = .813). Relative to participants in the negative control group, participants in the test group exhibited a statistically significant (P < .001) reduction in extrinsic tooth stain of 24.3% (Figure 2).

Percent reductions in Lobene stain area index and Lobene stain intensity index from baseline were also significant for the test group: 17.4% and 22.5%, respectively (P < .001). However, for the negative control group, changes were not statistically significant from baseline in either index (Table 3).

As measured by the Lobene stain area index, relative to participants in the negative control group, those in the test group exhibited a statistically significant (P < .001) reduction in extrinsic tooth stain of 17.7% after 3 weeks of product use. As measured by the Lobene stain intensity index, relative to participants in the negative control group, individuals in the test group exhibited a statistically significant (P < .001) reduction in extrinsic tooth stain of 22.7% after 3 weeks of product use.

Results at 6 Weeks

After 6 weeks of product use, the percent reductions in Lobene composite stain index scores from baseline were 35.6% for the test group, while the negative control group exhibited an increase from baseline of 5.8% (Table 4). The percent reduction from baseline observed for the test group was statistically significant (P < .001). However, the percent increase from baseline observed for the negative control group was not statistically significant (P = .212). Relative to participants in the negative control group, those in the test group exhibited a statistically significant (P < .001) reduction in extrinsic tooth stain of 39.1% as measured by the Lobene composite stain index after 6 weeks of product use (Figure 2).

Percent reductions in Lobene stain area index and Lobene stain intensity index from baseline were also significant for the test group: 27.5% and 34.2%, respectively (P < .001). However, for the negative control group, changes were not statistically significant from baseline in either index (Table 4).

As measured by the Lobene stain area index, relative to participants in the negative control group, those in the test group exhibited a statistically significant (P < .001) reduction in extrinsic tooth stain of 31.1% after 6 weeks of product use. As measured by the Lobene stain intensity index, relative to participants in the negative control group, individuals in the test group exhibited a statistically significant (P < .001) reduction in extrinsic tooth stain of 35.5% after 6 weeks of product use.

Safety Results

No adverse effects of the hard or soft oral tissues were observed by clinical investigators or reported by the trial participants.

This study compared the stain removal benefit of the SNaP toothpaste to regular fluoride toothpaste and demonstrated significant clinical efficacy. Participants in the SNaP test group had a statistically significant extrinsic stain reduction from baseline, 3 weeks, and 6 weeks, whereas those in the negative control group did not. Relative to participants in the negative control group, participants in the test group exhibited statistically significant (P < .001) reductions in extrinsic tooth stain of 24.3% and 39.1% after 3 and 6 weeks, respectively, as measured by the Lobene composite stain index, indicating a positive result for participants using SNaP.

The randomized trial was well controlled and utilized double-blinding methodology. While the inclusion/exclusion criteria outlined in the study aimed to encompass all potentially eligible participants, it is worth mentioning that the research was conducted at a single center, rather than employing a multi-center design.

Stannous fluoride has been extensively studied and is recognized for its anticaries and antigingivitis efficacy. However, patient compliance with ideal oral hygiene practices is partly driven by consumer preferences, including the desire for tooth whitening.^10,11 The formulation of SNaP is designed to prevent the oxidation of stannous ions, thereby reducing the staining typically associated with them and maintaining their efficacy. Future research should investigate the long-term whitening efficacy of SNaP to determine whether there is potential for further tooth whitening after more than 6 weeks of use. As has been measured with other whitening procedures and products,^10,11,13 future studies should also examine the relationship between the whitening benefits of SNaP, sustained adherence to oral hygiene routines, and, consequently, improved overall oral health.

This study demonstrates the extrinsic stain removal efficacy of the SNaP dentifrice as measured by the Lobene stain index. This stannous fluoride formula stabilized with nitrate and phosphates provides significantly better extrinsic stain removal compared to a regular fluoride toothpaste, resulting in better whitening efficacy.

Technical writing was provided by Abhijit Surwade, MBBS, and Cynthia Drake Morrow, PhD, MA. The author contributions were as follows: AE: investigation, methodology, resources; LM: formal analysis; RD, GX, and CM: resources; YZ: conceptualization, funding acquisition; BG: conceptualization, supervision. All authors contributed to writing, review, and editing.

This clinical trial was supported by funding from the Colgate-Palmolive Company. ClinicalTrials.gov: NCT06242769. The study was reviewed and approved by the U.S. Investigational Review Board, Inc. (U.S. IRB, Inc^®), 6400 SW 72 Court, Miami, Florida 33143. The authors RD, GX, CM, YZ, and BG are employees of Colgate-Palmolive Co. CM and GX have patents #US10918580B2 and #US11723846B2 issued to Colgate-Palmolive Co.

The documents containing the results of the research herein described are confidential. The authors confirm that the data supporting the findings of this study are available within the article and/or its supplementary materials.

Augusto R. Elías-Boneta, DMD, MSD
Assistant Dean for Research, University of Puerto Rico, School of Dental Medicine, San Juan, Puerto Rico; Principal Investigator, Dental Research Associates, Inc., San Juan, Puerto Rico

Luis R. Mateo, MA
President, LRM Statistical Consulting LLC, West Orange, New Jersey

Robert D'Ambrogio, BS
Senior Principal Scientist Research and Development (R&D), Colgate-Palmolive Co., Piscataway, New Jersey

Guofeng Xu, PhD
Senior Director R&D, Colgate-Palmolive Co., Piscataway, New Jersey

Carl P. Myers, PhD
Director R&D, Colgate-Palmolive Co., Piscataway, New Jersey

Yun-Po Zhang, PhD, DDS (Hon)
Senior Vice President and Distinguished Fellow, Clinical Research, Colgate-Palmolive Co., Piscataway, New Jersey

Bayardo García-Godoy, DMD, MSc
Director Clinical Research, Colgate-Palmolive Co., Piscataway, New Jersey

Figures and Images

Figure 1

Figure 2

Table 1

Table 2

Table 3

Table 4

Figure 1

Fig 1. Consolidated Standards of Reporting Trials (CONSORT) flow diagram of the study population for the 6-week extrinsic tooth stain removal clinical study.

Figure 2

Fig 2. Stain score comparison between test groups over time. Baseline-adjusted subject mean Lobene composite stain index scores and percentage change from negative control group at baseline, 3-week, and 6-week examinations.

Table 1

Table 2

Table 3

Table 4