Control of Established Gingivitis and Dental Plaque Using a 1450 ppm Fluoride/Zinc-based Dentifrice: A Randomized Clinical Study Y. Zhong

X. Li

D.Y. Hu

West China College of Stomatology, Sichuan University Chengdu, China L.R. Mateo LRM Consulting West Orange, NJ, USA B.M. Morrison, Jr

E. Delgado

Y.P. Zhang

Colgate-Palmolive Technology Center Piscataway, NJ, USA Abstract • Purpose: To investigate the clinical efficacy in controlling established gingivitis and dental plaque of a 1450 ppm fluoride as sodium monofluorophosphate (SMFP)/zinc-based dentifrice, as compared to a zinc-free dentifrice with 1450 ppm fluoride as SMFP after six months product use. • Methods: A six-month clinical study, with eighty-six (86) subjects, was conducted in Chengdu, China, using a double-blind, randomized, parallel-group treatment design. After a baseline evaluation, study subjects were randomly assigned to one of the two study treatments: 1) 1450 ppm fluoride as SMFP/zinc-based dentifrice (Test) or 2) 1450 ppm fluoride as SMFP/zinc-free dentifrice (Negative Control). Subjects were provided with a soft bristle toothbrush and brushed their teeth twice daily (morning and evening) for one minute with their assigned dentifrice. After three months, and again after six months of product use, subjects returned to the testing facility for their followup gingivitis and plaque examinations. Statistical analyses were performed separately for the gingivitis assessments and dental plaque assessments using the appropriate statistical methods. All statistical tests of hypotheses were two-sided, and employed a level of significance of a = 0.05. • Results: After three and six months of product use, subjects assigned to the Test treatment exhibited statistically significant (p < 0.001) reductions in gingival index and plaque index scores as compared to subjects assigned to the Negative Control treatment. • Conclusion: The results of this single-center, double-blind, parallel-group and randomized clinical study support the conclusion that a 1450 ppm fluoride as SMFP/zinc-based dentifrice provides clinically meaningful and statistically significant reductions in gingivitis (23.8%) and dental plaque (22.5%) as compared to a 1450 ppm fluoride as SMFP/zinc-free dentifrice over a six-month period of twicedaily product use. (J Clin Dent 2015;26:104–108)

Introduction Brushing with a toothbrush and dentifrice remains one of the most common methods to mechanically remove plaque from teeth.1-3 Unproductive tooth brushing leads to the accumulation of plaque at the gingival margins and causes gingivitis.1,4 Oral hygiene formulations containing agents with antimicrobial activity have played an essential role in mitigating the consequences of dental plaque.4 Thus, when used in combination with tooth brushing, dentifrices are ideal delivery systems for these active ingredients that are used as oral health preventive measures.5 Zinc is naturally present in saliva and teeth and is pervasive throughout the body.6 Prior to tooth eruption, zinc is incorporated into the enamel and the surface concentration of zinc increases further after tooth eruption.6 This increase in concentration is probably assisted by sub-clinical events in which repeated demineralizing and remineralizing challenges impact the outermost enamel layer.6 Zinc, when added to dentifrices and mouthrinses, has a variety

of functions. It can act as an antibacterial agent to help control plaque. It also reduces oral malodor. Finally it reduces the formation of calculus through crystal-growth modification⁄inhibition.6 In order to have all these effects, zinc must be present for a sufficient amount of time and at an effective concentration.6 Following use of a zinc-containing oral care product, relatively large amounts of zinc can be retained in the mouth, with amounts up to 40% reported in the literature.6 This high concentration will rapidly dissipate within 60 minutes of application, after which a lower concentration, which is still higher than baseline, may persist for many hours.6 This bi-modal clearance suggests that the looselybound zinc clears first, with the more tightly-bound taking much longer. In addition, zinc concentrations in plaque will increase as a result of repeated applications. 6 Zinc has several favorable properties, such as not causing dental staining, and, along with its low toxicity, makes it an excellent choice for inclusion in oral care products.7 For example, denti104

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frices containing an antimicrobial agent in combination with a zinc salt suppress both plaque accumulation and gingivitis development.8 The present study investigates the clinical efficacy of a 1450 ppm fluoride as SMFP/zinc-based dentifrice in controlling established gingivitis and dental plaque in comparison to a commercially available fluoride dentifrice without zinc, after six months of product use.

Materials and Methods The study design was double-blind, two-cell, parallel-group, and randomized. It was conducted according to Good Clinical Practices (GCP) and all study subjects signed an informed consent. The clinical protocol and related documents were reviewed and approved by a local ethics committee (Institutional Review Board). Inclusion Criteria Study participants from the Chengdu, China area were enrolled in the study based upon the following criteria: 1. In generally good health and between the ages of 18 and 70 years (inclusive). 2. Available for the duration of the study (six months). 3. Possess at least 20 uncrowned, permanent natural teeth (with the exception of third molars). 4. Mean Gingival Index score of at least 1.0 (Löe-Silness Gingival Index) and a mean Plaque Index score of at least 1.5 (Turesky modification of the Quigley-Hein Plaque Index). Exclusion Criteria Study participants were excluded from the study based upon the following criteria: 1. Presence of advanced periodontal disease (purulent exudate, tooth mobility, and/or extensive loss of periodontal attachment or alveolar bone), five or more decayed carious lesions requiring immediate restorative treatment, or tumor(s) of the soft or hard tissues of the oral cavity, or partial removable dentures or orthodontic bands. 2. Use of any prescribed medications that may interfere with the study outcome, or use of antibiotics within one month prior to the start of the study, or if they started taking them during the course of the study or received a dental prophylaxis in the past two weeks prior to the baseline examination. 3. Pregnant or lactating women, individuals who were participating in any other clinical study or who had participated in a study or test panel within one month prior to enrollment of study, or individuals with a history of alcohol or drug abuse. 4. History of allergies to the test products, or allergies to oral care/personal care consumer products or their ingredients, or the presence of existing medical conditions which prohibits them from eating and drinking for periods up to four hours were also excluded from the study. Potential subjects reported to the clinical facility for their baseline gingivitis and plaque evaluations. They needed to have refrained for the past 12 hours from all oral hygiene procedures, and for four hours prior to their baseline visit, they must have refrained from eating, drinking or smoking. The oral hard and soft tissue of each subject was also examined at baseline.

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Baseline gingival index and plaque index scores were used to randomize qualifying subjects into two balanced treatment groups. The treatments were: • Test: 1450 ppm fluoride as SMFP/zinc-based dentifrice (Colgate-Palmolive Company, New York, NY, USA); and • Negative Control: 1450 ppm fluoride as SMFP/zinc-free dentifrice (Colgate-Palmolive Company, New York, NY, USA). Following treatment assignment, a soft bristle toothbrush and a 6.0 oz tube of dentifrice were provided to the subjects for home use. All dentifrices were overwrapped in their original package to maintain the double-blind study design. The study subjects were instructed to brush their teeth at home with their assigned dentifrice twice daily (morning and evening) for one minute. They were instructed to only use the treatment products assigned to them during the course of the study, but were not restricted regarding diet or smoking habits. After three months and six months of product use, participants returned to the clinical facility for gingivitis and plaque examinations. Subjects returned their used tubes at these time points. The tubes were evaluated by the clinical staff to ensure dentifrice usage and compliance. Additionally, at each examination, all subjects received an evaluation of their oral hard and soft tissues and were questioned for the occurrence of any adverse events. Dental Plaque Assessment Dental plaque was revealed through the use of a disclosing solution. Plaque was scored at six surfaces on each tooth (the disto-, mid-, mesio-buccal and the disto-, mid-, mesio-lingual) according to the modified Quigley and Hein Index criteria.9,10 The criteria of the Turesky modification of the Quigley & Hein index system, (QHI) are: 0 = No plaque; 1 = Separate flecks of plaque at the cervical margin; 2 = A thin, continuous band of plaque (up to 1 mm) at the cervical margin; 3 = A band of plaque wider than 1 mm, but covering less than 1/3 of the side of the crown of the tooth; 4 = Plaque covering at least 1/3, but less than 2/3 of the side of the crown of the tooth; 5 = Plaque covering 2/3 or more of the side of the crown of the tooth. Gingivitis Assessment Gingival inflammation was scored at six surfaces of each tooth (disto-, mid-, mesio-buccal and disto-, mid-, mesio-lingual) according to the criteria of the Löe-Silness Gingival Index system, which are: 0 = Absence of inflammation; 1 = Mild inflammation – slight change in color and little change in texture; 2 = Moderate inflammation – moderate glazing, redness, edema and hypertrophy; 3 = Severe inflammation – marked redness and hypertrophy. Tendency for spontaneous bleeding. Subject-wise scores were calculated separately for plaque and for gingivitis by summing all scores for all sites and dividing by the total number of sites scored. The Löe-Silness and the Turesky modification of the Quigley &

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Hein Index are well known and utilized frequently within the research community. All measurements of gingivitis and dental plaque were made by the same examiner who had been previously trained and calibrated and who was highly experienced in the clinical scoring procedures. Oral Soft and Hard Tissue Assessment The oral cavity and peri-oral area were visually examined with the aid of a dental light and dental mirror. This examination included an evaluation of the soft and hard palate, gingival mucosa, buccal mucosa, mucogingival fold areas, tongue, sublingual and submandibular areas, salivary glands, tonsilar and pharyngeal areas, and the teeth. Adverse Events Adverse events were obtained from an interview with the subject and from a dental examination by the examiner. Statistics Statistical analyses were performed separately for the gingivitis assessments and dental plaque assessments. Comparisons of the treatment groups with respect to gender were performed using a Chi-Square analysis, and to age were performed using an analysis

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of variance (ANOVA). Comparisons of the treatment groups with respect to baseline gingival index scores and plaque index scores were performed using an ANOVA. Within-treatment comparisons of the baseline versus follow-up gingival index and plaque index scores were performed using paired t-tests. At the follow-up examinations, comparisons of the treatment groups with respect to baseline-adjusted gingival index and plaque index scores were performed using analyses of covariance (ANCOVA). In particular, the differences between the products at each time point are expressed as a percentage of the three-month mean for the Negative Control dentifrice. Thus, a positive value indicates a reduction for the particular index score for the Test dentifrice relative to the Negative Control dentifrice. All statistical tests of hypotheses were two-sided, and employed a level of significance of a = 0.05.

Results Of the one hundred twelve (112) individuals who were assessed for study eligibility; twenty-two (22) were excluded from the study as they did not meet the inclusion criteria; and ninety (90) were randomized into the study (Figure 1). A total of eighty-six (86) subjects complied with the requirements of the protocol and completed the six-month clinical study. Table I summarizes the demographics of the population who completed the study. Treatment

Assessed for eligibility (n = 112)

22 Did not meet inclusion criteria

Randomized (n = 90)

Allocation Test Dentifrice (n = 45) •Received allocated intervention (n = 45)

Negative Control Dentifrice (n = 45) •Received allocated intervention (n = 45)

3-Month Follow-up Test Dentifrice (n = 43) •Discontinued (n = 2) - Traveling

Negative Control Dentifrice (n = 45)

6-Month Analysis Analyzed (n = 42) •Discontinued (n = 1) - Moved from area

Figure 1. CONSORT flow diagram.

Analyzed (n = 44) •Discontinued (n = 1) - Traveling

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Table I Summary of Age and Gender for Subjects Who Completed the Six-Month Clinical Study Treatment

Number of Subjects Male Female Total1

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percent changes from baseline were 27.7% for subjects in the Test group and 9.0% for the Negative Control group, both of which were statistically significant (p < 0.001). Relative to subjects assigned to the Negative Control group, subjects assigned to the Test group exhibited a statistically significant (p < 0.001) reduction of 20.5% in gingival index scores after three months of product use. Plaque Index. Table III also summarizes the baseline-adjusted mean plaque index scores measured after three months of product use, which were 2.07 for subjects assigned to the Test group and 2.48 for subjects assigned to the Negative Control group. The percent changes from baseline were 23.9% for subjects in the Test group and 8.8% for the Negative Control group, both of which were statistically significant (p < 0.001). Relative to subjects assigned to the Negative Control group, subjects assigned to the Test group exhibited a statistically significant (p < 0.001) reduction of 16.5% in plaque index scores after three months of product use.

Age1 Mean Range

Test Dentifrice 15 27 42 52.6 32–65 Negative Control Dentifrice 17 27 44 51.4 35–65 1 No statistically significant difference was indicated between the treatment groups with respect to either gender or age.

groups did not differ statistically significantly (p > 0.05) from each other with respect to either gender or age. No adverse effects on the oral hard or soft tissues were reported by the study subjects upon questioning or noted by the examiner. In addition, there were no differences in product usage or in panelist compliance with the test methodology. The mean gingival index and plaque index scores as measured at baseline and after three months and six months of product use for those subjects who completed the study are summarized in Table II. For gingival index, the mean baseline gingival index scores were 1.66 for subjects in the Test group and 1.66 for the Negative Control group. For plaque index, the mean baseline plaque index scores were 2.72 for subjects in the Test group and 2.71 for the Negative Control group. No statistically significantly (p > 0.05) difference was indicated between the treatment groups with respect to these baseline scores.

Six-Month Data Gingival Index. The baseline-adjusted mean gingival index scores measured after six months of product use are summarized in Table IV, which were 1.15 for subjects assigned to the Test group and 1.51 for subjects assigned to the Negative Control group. The percent changes from baseline were 30.7% for the Test group and 9.0% for the Negative Control group, both of which were statistically significant (p < 0.001). Relative to subjects assigned to the Negative Control group, subjects assigned to the Test group exhibited a statistically significant (p < 0.001) reduction of 23.8% in gingival index scores after six months of product use. Plaque Index. The baseline-adjusted mean plaque index scores measured after six months of product use are summarized in Table

Three-Month Data Gingival Index. The baseline-adjusted mean gingival index scores as measured after three months of product use are summarized in Table III, which were 1.20 for subjects assigned to the Test group and 1.51 for subjects assigned to the Negative Control group. The

Table II Mean Gingival and Plaque Index Scores at Baseline, Three Months, and Six Months for Subjects Who Completed the Six-Month Clinical Study Parameter

Treatment

N

Baseline Summary1 (Mean ± SD)

Three-Month Summary (Mean ± SD)

Six-Month Summary (Mean ± SD)

Gingival Index

Test Dentifrice Negative Control Dentifrice

42 44

1.66 ± 0.24 1.66 ± 0.13

1.20 ± 0.23 1.51 ± 0.11

1.15 ± 0.19 1.51 ± 0.11

Test Dentifrice 42 2.72 ± 0.25 2.07 ± 0.32 Plaque Negative Control Dentifrice 44 2.71 ± 0.16 2.48 ± 0.22 Index 1 No statistically significant difference was indicated between the treatment groups at baseline with respect to either plaque or gingival indices.

1.69 ± 0.31 2.18 ± 0.22

Table III Baseline-Adjusted Subject Mean Gingival Index and Plaque Index Scores at Three Months for Subjects Who Completed the Six-Month Clinical Study

Index

Within-Treatment Analysis Percent Reduction1 Sig.2

Between-Treatment Comparison vs Negative Control Dentifrice Percent Difference3 Sig.4

Treatment

n

Three-Month Summary (Mean ± SE)

Gingival Index

Test Dentifrice Negative Control Dentifrice

42 44

1.20 ± 0.01 1.51 ± 0.01

27.7% 9.0%

p < 0.001 p < 0.001

20.5%

p < 0.001

Plaque Index

Test Dentifrice Negative Control Dentifrice

42 44

2.07 ± 0.04 2.48 ± 0.04

23.9% 8.8%

p < 0.001 p < 0.001

16.5%

p < 0.001

1

Percent reduction exhibited by the three-month mean relative to the baseline mean. A positive value indicates a reduction in index scores at the three-month examination. Significance of paired t-test comparing the baseline and three-month examinations. 3 Difference between the three-month means expressed as a percentage of the three-month mean for the Negative Control Dentifrice. A positive value indicates a reduction in index scores for the Test Dentifrice relative to the Negative Control Dentifrice. 4 Significance of ANCOVA comparison of baseline-adjusted means. 2

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Table IV Baseline-Adjusted Subject Mean Gingival Index and Plaque Index Scores at Six Months for Subjects Who Completed the Six-Month Clinical Study

Index

Within-Treatment Analysis Percent Reduction1 Sig.2

Between-Treatment Comparison vs Negative Control Dentifrice Percent Difference3 Sig.4

Treatment

n

Three-Month Summary (Mean ± SE)

Gingival Index

Test Dentifrice Negative Control Dentifrice

42 44

1.15 ± 0.01 1.51 ± 0.01

30.7% 9.0%

p < 0.001 p < 0.001

23.8%

p < 0.001

Plaque Index

Test Dentifrice Negative Control Dentifrice

42 44

1.69 ± 0.04 2.18 ± 0.04

37.9% 19.9%

p < 0.001 p < 0.001

22.5%

p < 0.001

1

Percent reduction exhibited by the six-month mean relative to the baseline mean. A positive value indicates a reduction in index scores at the six-month reexamination. Significance of paired t-test comparing the baseline and six-month examinations. 3 Difference between the six-month means expressed as a percentage of the six-month mean for the Negative Control Dentifrice. A positive value indicates reduction in index scores for the Test Dentifrice relative to the Negative Control Dentifrice. 4 Significance of ANCOVA comparison of baseline-adjusted means. 2

IV, which were 1.69 for subjects assigned to the Test group and 2.18 for subjects assigned to the Negative Control group. The percent changes from baseline were 37.9% for the Test group and 19.9% for the Negative Control group, both of which were statistically significant (p < 0.001). Relative to subjects assigned to the Negative Control group, subjects assigned to the Test group exhibited a statistically significant (p < 0.001) reduction of 22.5% in plaque index scores after six months of product use.

Discussion Oral hygiene products used for chemical plaque control have been categorized according to their mechanism of action as: a) antimicrobial agents, when demonstrating a bacteriostatic or bactericidal effect in vitro; b) plaque-reducing/inhibitory agents, when demonstrating an in vivo significant quantitative or qualitative effect on plaque levels, which may not have a significant effect on gingivitis and/or caries; c) antiplaque agents, when demonstrating a significant in vivo effect on plaque levels sufficient to achieve a significant benefit in terms of gingivitis and/or caries control; and d) antigingivitis agents, when demonstrating a significant in vivo reduction in gingival inflammation without, necessarily, reducing dental plaque levels.5 Zinc salts have been recommended for chemical plaque control based on a variety of favorable antimicrobial effects that the zinc ion delivers.12 Various commercially available products contain zinc, either alone or together with other active agents, such as antimicrobials. These products are often used as part of a good oral hygiene regime to effectively remove plaque.7 This double-blind and randomized clinical study provided an investigative comparison of the clinical efficacy of a 1450 ppm fluoride as SMFP/zinc-based dentifrice as compared to a 1450 ppm fluoride as SMFP/zinc-free dentifrice with respect to controlling gingivitis and dental plaque over a six-month period. After three months and six months of product use, the Test dentifrice exhibited significant reductions in gingival index scores of 20.5% and 23.6%, respectively, as compared to the Negative Control dentifrice. In addition, after three months and six months of product use, the Test dentifrice exhibited, significant reductions in plaque index scores of 16.5% and 22.5% as compared to the Negative Control dentifrice. The results of this single-center, double-blind, parallel-group and randomized clinical study support the conclusion that a 1450 ppm

fluoride as SMFP/zinc-based dentifrice provides significantly greater reductions in gingivitis and dental plaque as compared to a 1450 ppm fluoride as SMFP/zinc-free dentifrice over a six-month period of twice-daily product use. Furthermore, there is a clinically meaningful difference between the products at six months for both gingivitis and dental plaque. Acknowledgment: This clinical study was sponsored by the Colgate-Palmolive Company.

For correspondence with the authors of this paper, contact Dr. Yun Po Zhang – [email protected].

References 1. Saxton CA, Svatun B, Lloyd AM. Antiplaque effects and mode of action of a combination of zinc citrate and a nonionic antimicrobial agent. Scand J Dent Res 1988;93:212-7. 2. Jones CL, Ritchie JA, Marsh PD, van der Ouderaa F. The effect of longterm use of a dentifrice containing zinc citrate and non-ionic agent on the oral flora. J Dent Res 1988;67:46-50. 3. Saxton CA, Lane RM, van der Ouderaa F. The effects of a dentifrice containing a zinc salt and a non-cationic antimicrobial agent on plaque and gingivitis. J Clin Periodontol 1987;14:144-8. 4. Sreenivasan PK, Furgang D, Markowitz K, Mckiernan M, Tischio-Bereski D, DeVizio W, Fine D. Clinical anti-microbial efficacy of a new zinc citrate dentifrice. Clin Oral Invest 2009;13:195-202. 5. Sanz M, Serrano J, Iniesta M, Santa Cruz IS. Antiplaque and antigingivitis toothpastes. Monogr Oral Sci 2013;23:27-44. 6. Lynch RJM. Zinc in the mouth, its interactions with dental enamel and possible effects on caries; a review of the literature. Int Dent J 2011;61:46-54. 7. Young A, Jonski G. Effect of a single brushing with two Zn-containing toothpastes on VSC in morning breath: a 12 h, randomized double-blind, crossover clinical study. J Breath Res 2011;5:1-8. 8. Svatun B, Saxton CA, van der Ouderaa F, Rölla G. The influence of a dentifrice containing a zinc salt and a nonionic antimicrobial agent on the maintenance of gingival health. J Clin Periodontol 1987;14:457-61. 9. Turesky S, Gilmore ND, Glickman I. Reduced plaque formation by the chloromethyl analogue of victamine C. J Periodontol 1970;41:41-3. 10. Quigley GA, Hein JW. Comparative cleaning efficiency of manual and power brushing. J Am Dent Assoc 1962;65:26-9. 11. Löe H, Silness J. Periodontal disease in pregnancy. I. Prevalence and severity. Acta Odontol Scand 1963;21:533-51. 12. Pizzey RL, Marquis RE, Bradshaw DJ. Antimicrobial effects of o-cymen5-ol and zinc, alone & in combination in simple solutions and toothpaste formulations. Int Dent J 2011;61:33-40. 13. Panagakos FS, Volpe AR, Petrone JD, Morrison, Jr BM, DeVizio W, Proskin HM. Advanced oral antibacterial/anti-inflammatory technology: A comprehensive review of the clinical benefits of a triclosan/copolymer/fluoride toothpaste. J Clin Dent 2014;25(Suppl):S1-30.