Anti-gingivitis and Anti-plaque Efficacy of an Oral Hygiene System: Results From a 12-Week Randomized Controlled Trial

Periodontal disease is a widespread global health problem affecting individuals across age groups.¹ The earliest presentation of periodontal disease is gingivitis, an inflammation of the gingiva that results in bleeding and swelling.^1,2 While preventable and reversible, gingivitis increases susceptibility to periodontitis, a serious gingival infection that can lead to tooth loss and reduced quality of life.¹ The primary cause of gingivitis is plaque accumulation at the gingival margin and interproximally^2,3; thus, plaque removal and control are key to prevention.³ Optimal plaque control can be accomplished through a daily oral hygiene routine comprising both mechanical plaque removal and chemotherapeutics.^3,4

Electric toothbrushes have consistently demonstrated greater plaque removal efficacy than manual brushes.^5,6 In particular, electric brushes employing oscillating-rotating (O-R) technology have been highlighted in systematic reviews and meta-analyses as offering advantages for plaque removal and gingival health improvements relative to various manual and electric toothbrush models.^7-9 While studies evaluating the efficacy of interdental plaque removal methods are somewhat limited,¹⁰ a randomized, controlled study in twins found significantly decreased gingival bleeding after 2 weeks with toothbrushing and flossing compared to toothbrushing alone.¹¹

Chemotherapeutic dentifrices and mouthrinses supplement mechanical plaque removal by addressing the microbial etiology of periodontal disease. In particular, stabilized stannous fluoride (SnF₂) dentifrice formulations provide the anti-caries benefits typical of other fluoridated dentifrices, but also inhibit plaque regrowth due to the antimicrobial properties of stannous.¹² Recent systematic reviews and meta-analyses support the use of SnF₂ dentifrice formulations over fluoridated dentifrices without SnF₂ for a range of outcomes, including reduction of gingivitis and plaque.^4,13,14 Additionally, studies of mouthrinse containing cetylpyridinium chloride (CPC), a broad-spectrum antimicrobial agent, have demonstrated reductions in gingivitis, gingival bleeding, and plaque compared with placebo.^15,16

The objective of this study was to evaluate the antigingivitis and antiplaque efficacy of a novel smart-connected O-R electric toothbrush with micro-vibrations (Oral-B^® iO, Procter & Gamble, dentalcare.com)¹⁷ used with stabilized SnF₂ dentifrice, CPC rinse, and floss versus a manual toothbrush control regimen.

This single-center, randomized, examiner-blind, two-treatment, 12-week parallel group study compared the antigingivitis and antiplaque efficacy of an oral hygiene system to a control regimen. Eligible subjects were at least 18 years of age, typically used a manual toothbrush, were in good general health, had evidence of gingivitis (baseline pre-brushing modified gingival index [MGI]¹⁸ score of 1.75 to 2.5, 20 to 90 bleeding sites, and a score of 1 or 2 on the gingival bleeding index [GBI]¹⁹) and plaque (baseline pre-brushing Rustogi modified navy plaque index [RMNPI]²⁰ score >0.5), and possessed a minimum of 16 natural teeth with facial and lingual scorable surfaces. Subjects were required to have a compatible smartphone for the Oral-B app (Android 7.0 to 10.0 or iPhone iOS 12.0 to 14.0) and agreed to download the toothbrushing app from the manufacturer (Procter & Gamble). Subjects who had fixed orthodontic appliances or removable partial dentures, self-reported nursing/pregnancy, had any condition that could interfere with study participation, had used antibiotics, chlorhexidine mouthrinse, or anti-inflammatory medications within 2 weeks prior to study initiation, and/or had undergone oral or periodontal surgery within 2 months prior to study initiation were excluded.

Enrolled subjects were not permitted to participate in other oral care studies, receive elective dentistry including prophylaxis, or use antibiotics or chlorhexidine mouthrinse. Participants in violation of pre-visit food/drink restrictions (no eating, drinking, breath mints, or tobacco use for 4 hours prior to their scheduled visit, except for small sips of water up to 45 minutes before the appointment) and oral hygiene restrictions (no oral hygiene for 12 hours prior to their scheduled visit) or who developed any condition expected to interfere with participation were subject to exclusion from the data analysis or the study. The subject consent form and the study protocol were reviewed by and approved prior to study inception by Veritas IRB Inc. (Ref: 16474-10:47:2815-11-2019) and subjects were required to provide written informed consent before enrolling. The study was registered in the ISRCTN clinical trials registry (ISRCTN99297838).

At the Baseline visit, medical history was obtained, and each potential subject received an oral examination followed by pre-brushing MGI and GBI evaluations. After the gingival assessments, a plaque-disclosing solution (Chrom-O-Red erythrosine FD&C red 3; Germiphene Corp., germiphene.com) was applied on all teeth and an examiner conducted pre-brushing RMNPI assessments. Subjects meeting all eligibility requirements were stratified based on MGI score (≤2.1 versus >2.1), whole-mouth mean RMNPI (≤0.60 versus >0.60), number of bleeding sites (≤25 versus >25), and tobacco use (present or absent) and randomized using an encoded program supplied by the sponsor to one of two groups: (1) oral hygiene system (test group): Oral-B iO O-R electric rechargeable toothbrush with micro-vibrations and Ultimate Clean brush head (M7/OR015) (Procter & Gamble), 0.454% stabilized SnF₂ dentifrice (Crest Gum Detoxify, Procter & Gamble), 0.07% CPC rinse (Crest Pro-Health Multi-Protection Rinse, Procter & Gamble), and Oral-B Glide Pro-Health Advanced Floss (Procter & Gamble); or (2) control regimen: Oral-B Indicator 35 soft manual toothbrush (Procter & Gamble), 0.243% sodium fluoride dentifrice (Crest Cavity Protection; Procter & Gamble).

Subjects received their test products and proceeded to a protected area to ensure examiner blinding. All subjects were given detailed written and verbal oral hygiene and product usage instructions. Subjects randomized to the test group were aided in downloading a toothbrush app (Oral-B Professional App 1.0) and in connecting their toothbrush to the app. Subjects brushed using the assigned products under supervision, aided by a mirror. Subjects in the test group were directed to brush twice daily for 2 minutes per the manufacturer's instructions using the app, and to floss the whole mouth once daily for the duration of the study. Additionally, subjects in the test group were instructed to rinse with water after brushing and then to rinse with 20 mL of mouthrinse for 30 seconds. Subjects in the control group were instructed to brush their teeth with the assigned products twice daily in their customary manner, to rinse with water after brushing, and to continue using floss in their customary manner if that was part of their normal oral care routine. Subjects were not permitted to add or change any other oral hygiene products. All subjects were instructed to use their assigned products following the provided usage instructions for approximately 12 weeks. The on-site practice brushing at the Baseline visit was considered as one of the two daily brushings. Subjects received post-brushing oral examinations followed by post-brushing RMNPI assessments and were instructed to abstain from any oral hygiene for 12 hours prior to all visits.

Approximately 1 week (±2 days) and 12 weeks (±3 days) after the Baseline visit, subjects returned to the study site and continuance criteria were assessed. Subjects received a pre-brushing oral exam, followed by MGI and GBI assessments (in that order). Next, the disclosing solution was applied, and a clinical examiner conducted pre-brushing RMNPI examinations. The same blinded examiner conducted all gingivitis and plaque assessments throughout the study.

Gingivitis was scored using the MGI (buccal and lingual marginal gingival and interdental papilla) and GBI. Those sites with GBI scores of 1 (bleeding observed after 30 seconds) or 2 (immediate bleeding observed) were summed to give the total number of bleeding sites. Plaque was assessed using the RMNPI on up to 28 teeth.

Statistical analyses for gingivitis efficacy were based on whole-mouth average MGI and GBI change from baseline scores, as well as change from baseline in number of bleeding site scores at Weeks 1 and 12. An analysis of covariance (ANCOVA) was performed to determine treatment differences on the whole-mouth average gingivitis reduction with the respective baseline gingivitis score as the covariate and treatment and pre-brushing score by treatment interaction (if significant at the 10% level) as factors for each week separately. Separate analyses were performed for each gingivitis endpoint, with MGI being the primary endpoint. Additionally, the Week 12 timepoint was of highest importance.

Within-treatment differences from baseline gingivitis scores (MGI, GBI, and number of bleeding sites) were tested versus zero using paired-difference t-tests. Additionally, the percentage of subjects whose gingivitis status was classified as "localized or generalized gingivitis" (≥10% bleeding sites) or "healthy" (<10% bleeding sites) per American Academy of Periodontology and European Federation of Periodontology criteria²¹ at each visit was computed and compared between treatment groups using a chi-square test. The odds ratio of transitioning from "localized or generalized gingivitis" to "healthy" was calculated at Weeks 1 and 12.

At the Baseline visit, subjects' whole-mouth single brushing plaque reduction (pre-brushing minus post-brushing) was analyzed for treatment differences using an ANCOVA with the pre-brushing whole-mouth RMNPI score as the covariate and treatment and pre-brushing by treatment interaction (if significant at the 10% level) as factors. Similar analyses were carried out for gingival margin and interproximal RMNPI. At each post-Baseline visit, statistical analyses for plaque efficacy were based on average pre-brushing whole-mouth RMNPI change from Baseline score (Baseline pre-brushing minus Week 1 and Baseline pre-brushing minus Week 12). The 1-week and 12-week plaque reductions were analyzed for treatment differences using an ANCOVA with Baseline pre-brushing whole-mouth RMNPI score as the covariate and treatment and pre-brushing by treatment interaction (if significant at the 10% level) as factors. Similar analyses were carried out for gingival margin and interproximal RMNPI.

Sixty subjects were enrolled and randomized to one of the two groups. One subject assigned to the test group discontinued after the Baseline visit due to scheduling issues. Fifty-nine subjects completed the trial with fully evaluable data. Mean age was 47 years (range, 19 to 71 years). Forty-five subjects (75%) were female. Twenty-seven (45%) were Caucasian, 15 (25%) were Black or African American, 14 (23%) were Asian, and four (7%) were other. There were no significant differences between groups at Baseline (P≥ .078) for age, race, or sex.

There were no significant Baseline group differences (P≥ .834) in GBI, number of bleeding sites, or MGI. Both groups demonstrated statistically significant reductions from Baseline (P< .001) for all three gingivitis endpoints at Weeks 1 and 12.

The test group demonstrated statistically significantly lower (P< .001) adjusted mean scores for all three gingivitis parameters relative to the control group at Weeks 1 and 12. See Table 1 and Figure 1. At Week 12 compared to baseline, the test group demonstrated a 91.9% reduction in adjusted mean number of bleeding sites, a 92.7% reduction in adjusted mean GBI score, and a 66.5% reduction in adjusted mean MGI score compared to reductions of 21.7%, 24.1%, and 8.31%, respectively, for the control group (P< .001). The ratios of adjusted mean reduction scores in favor of the test group over the control group at Weeks 1 and 12, respectively, were: 5.5 and 3.9 for GBI, 5.4 and 4.2 for number of bleeding sites, and 4.9 and 8.0 for MGI.

By Week 12, 100% (n = 29) of subjects in the test group transitioned to "healthy" gingivitis case status compared with 7% (n = 2) of subjects in the control group (Figure 2).

There were no significant Baseline group differences (P≥ .468) in whole-mouth, interproximal, or gingival margin RMNPI. Both groups demonstrated statistically significant reductions from Baseline (P≤ .0369) for whole-mouth, interproximal, and gingival margin RMNPI after a Baseline single brushing and at Weeks 1 and 12.

Group comparisons for adjusted mean changes from Baseline for whole-mouth, interproximal, and gingival margin RMNPI at Weeks 1 and 12 are shown in Table 2 and Figure 2 (whole mouth). The test group demonstrated statistically significantly lower (P< .001) adjusted mean scores for all three RMNPI assessments relative to the control group after a single brushing and at Weeks 1 and 12. The ratios of adjusted mean reduction scores in favor of the test group over the control group at Weeks 1 and 12, respectively, were: 3.4 and 4.2 for whole-mouth RMNPI, 3.7 and 3.4 for interproximal RMNPI, and 7.8 and 32.4 for gingival margin RMNPI.

No adverse events were reported or observed.

This 12-week, randomized, parallel group study demonstrated greater antigingivitis and antiplaque efficacy of an oral hygiene system involving a novel O-R electric toothbrush with micro-vibrations, stabilized SnF₂ dentifrice, CPC rinse, and floss compared to a control regimen involving a manual toothbrush and NaF dentifrice. Gingivitis assessments, including gingival bleeding, showed significant reductions by Week 1 in the test group compared with the control group, and effects increased throughout the study. Similarly, all three plaque measures showed greater improvements by Week 1 in the test group relative to the control group, and effects increased at Week 12.

Notably, by the end of the study, all participants in the test group had a gingivitis case classification of "healthy" compared with only 7% of participants in the control group. This is important given that all subjects presented with localized or generalized gingivitis at Baseline and improved to a healthy status irrespective of their initial level of disease, which ranged from 20 to 86 bleeding sites.  While the majority of patients who brushed with the Oral-B iO toothbrush in a previous randomized study transitioned to gingival health,²² the finding that all participants who used the oral hygiene system had a gingivitis status of "healthy" by the end of this study underscores the importance of combined mechanical plaque removal and chemotherapeutics formulated to reduce plaque regrowth and maintain gingival health.

The Oral-B iO has advanced interactive features and an app with Bluetooth connectivity. The brush provides users with live brushing guidance, feedback on the appropriate amount of pressure, and ongoing motivation to increase brushing time.¹⁷ Previous studies in adolescents with earlier models of smart-connected O-R electric toothbrushes have demonstrated that interactive features increase plaque removal and improve brushing behavior.^23,24

One limitation of the current study is that determinations cannot be made about the individual contributions of each product in reducing gingivitis and plaque. Results reflect the cumulative effect of mechanical plaque removal from the O-R electric toothbrush and floss and chemical plaque control from the SnF₂ dentifrice and CPC rinse. Discerning the impact of individual products would require a different study objective and trial design. However, results are consistent with systematic reviews, meta-analyses, and randomized controlled studies demonstrating the gingival health benefits for each component of the oral hygiene system.^{4,7,8,11,13,14,15,16,22,25} Future studies could assess the efficacy of the oral hygiene system evaluated here among special populations, such as those with orthodontic appliances or dental implants.

A system involving a novel smart-connected O-R electric toothbrush, stabilized SnF₂ dentifrice, CPC rinse, and floss provided significant reductions in gingivitis and plaque compared to a control regimen over 12 weeks in adults with evidence of gingivitis and plaque at Baseline. These results show that this O-R electric toothbrush, along with interdental cleaning (eg, flossing), provides highly effective plaque removal for preventive home care. SnF₂ dentifrice and CPC rinse augment mechanical plaque removal and can be readily incorporated into an oral hygiene routine.

The authors thank Malgorzata Klukowska, DDS, PhD, for input to study design, and Liz Phipps, PhD, CMPP, for assistance with manuscript development.

This study was funded by Procter & Gamble. RA and HT are employees of Procter & Gamble Service GmbH, and JG is an employee of The Procter & Gamble Company. JQ and CRG declare no conflicts of interest.

Ralf Adam, PhD
Research Fellow, Procter & Gamble Service GmbH, Kronberg, Germany

Julie Grender, PhD
Research Fellow Statistician, The Procter & Gamble Company, Mason, Ohio

Hans Timm, PhD
Clinical Trial Manager, Procter & Gamble Service GmbH, Kronberg, Germany

Jimmy Qaqish, BSc
Vice President, Clinical Operations, All Sum Research Center Ltd, Mississauga, Ontario, Canada

C. Ram Goyal, DDS
Principal Investigator, All Sum Research Center Ltd, Mississauga, Ontario, Canada