SUBJECTS AND METHODS

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Design. Healthy adult volunteers, aged 18 to 65 years, with preexisting supragingival plaque and gingivitis (but without moderate or advanced periodontitis) from the communities in and around Mississauga, Ontario, entered this six-month study conducted according to the above-mentioned guidelines.¹ Subjects were required to have at least 20 sound, natural teeth and a Modified Gingival Index,¹⁶ or MGI, and Plaque Index,¹⁷ or PI, of 1.75 or greater (that is, slight to moderate).

After providing informed consent, all subjects received a baseline intraoral examination and scoring of MGI, Bleeding Index, or BI,¹⁸ and PI. They were then given a dental prophylaxis to remove all supragingival plaque, stain and calculus. Subjects were randomly assigned to one of three groups: L group (control toothpaste [Colgate MFP, Colgate-Palmolive]/Listerine Antiseptic rinse), T group (Colgate Total fluoride toothpaste/ control rinse [hydroalcohol flavored rinse]) or the negative control group P (Colgate MFP/control rinse). On the same day as the prophylaxis, subjects began brushing with their assigned dentifrice for 60 seconds, followed by rinsing for 30 seconds with 20 milliliters of their assigned mouthrinse, twice daily, unsupervised at home for six months.

Subjects received additional mouthrinse and dentifrice supplies periodically throughout the study and maintained a diary of brushings and rinsings and any medications used. During the study, subjects followed their usual dietary habits, but were instructed to refrain from using any other commercial mouthrinses or dentifrices.

On examination days, subjects did not brush or rinse for at least eight hours before the examination to preclude any bias that could occur from residual product odor.

Examinations. To minimize potential bias, the subjects, examiner and recorder were not aware of the treatment code, and personnel dispensing the test materials did not participate in the examination of subjects. In addition, on examination days, subjects did not brush or rinse for at least eight hours before the examination to preclude any bias that could occur from residual product odor in the mouth.

At baseline, three months and six months, the study examiner performed a complete intraoral examination. Presence of supragingival calculus and extrinsic tooth stain was noted, and gingivitis, bleeding and plaque indexes were scored. Reexaminations to determine examiner repeatability for gingivitis (that is, MGI) and plaque scoring were conducted for 15 subjects at each examination.

Below is a description of the clinical indexes:

Gingivitis was scored according to the MGI¹⁶ on the buccal and lingual marginal gingivae and on the interdental papillae of all scorable teeth (that is, teeth with no gross caries, marginal or extensive restorations, crowns or orthodontic bands):

– 0: absence of inflammation;

– 1: mild inflammation—slight change in color, little change in texture of any portion of but not the entire marginal or papillary gingival unit;

– 2: mild inflammation—criteria as above but involving the entire marginal or papillary gingival unit;

– 3: moderate inflammation—glazing, redness, edema and/or hypertrophy of the marginal or papillary gingival unit;

– 4: severe inflammation—marked redness, edema and/or hypertrophy of the marginal or papillary gingival unit, spontaneous bleeding, congestion or ulceration.

We calculated a Gingivitis Severity Index,¹⁹ or GSI, for each subject. The mean index provides a method of assessing the effect of treatment on the more severely diseased sites by dividing the number of gingival sites that received a score of 3 or 4 by the number of gingival sites scored within the subject’s mouth.

Bleeding was assessed according to the gingival BI, as defined by Saxton and van der Ouderaa.¹⁸ A periodontal probe with a 0.5-millimeter-diameter tip was inserted into the gingival crevice and swept from the distal aspect to the mesial aspect of the tooth at a depth of about 1 mm and at an angle of about 60 degrees, while in contact with the sulcular epithelium. We assessed each of three gingival areas or units (that is, buccal, mesiobuccal and lingual) of the teeth in this manner, waiting approximately 30 seconds before recording the number of gingival units that bled, according to the following scale:

– 0: absence of bleeding after 30 seconds;

– 1: bleeding observed after 30 seconds;

– 2: immediate bleeding observed.

Plaque area was scored according to the Turesky modification of the Quigley-Hein PI¹⁷ on six surfaces (that is, distobuccal, midbuccal, mesiobuccal, distolingual, midlingual and mesiolingual) of all scorable teeth after application of disclosing solution:

– 0: no plaque;

– 1: separate flecks or a discontinuous band of plaque at the gingival (cervical) margin;

– 2: thin (up to 1 mm) continuous band of plaque at the gingival margin;

– 3: band of plaque wider than 1 mm but less than one-third of the surface;

– 4: plaque covering one-third or more of the surface, but less than two-thirds of the surface;

– 5: plaque covering two-thirds or more of the surface.

We calculated a Plaque Severity Index,¹⁹ or PSI, to evaluate sites that had the heaviest accumulation of plaque within the subject’s mouth. The mean index was calculated by dividing the number of sites that received a PI score of 3, 4 or 5 by the total number of sites scored within the mouth.

	STATISTICAL METHODS

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The planned sample size of 300 subjects (100 per treatment group) provides at least 90 percent power to detect a difference of 0.15 in MGI between two treatment groups. This calculation was based on a two-sided test at the .05 level and a standard deviation of 0.19.

At six months, subjects in both active treatment groups had statistically significantly lower whole-mouth mean Modified Gingival Index scores than did subjects in the control group.

The treatment groups were compared with respect to age and baseline variables by means of a one-way analysis of variance, or ANOVA, with treatment as the factor; with respect to sex and smoking status by means of a ² test; and with respect to race by means of Fisher exact test. The primary efficacy variable was MGI, and the secondary efficacy variables were BI, PI, GSI¹⁹ and PSI.¹⁹

Although treatments were compared after three and six months, the primary time point of interest was six months. Between-treatment comparisons with respect to the efficacy variables were made using a one-way analysis of covariance, with treatment as the factor and the corresponding baseline value as the covariate. The treatment-by-baseline interaction was examined for equality of slopes, and the interaction term was removed from the model if not statistically significant at the .05 level.

We performed the following comparisons for mean MGI:

– L group vs. control group;

– T group vs. control group;

– L group vs. T group.

The study would be considered valid if the mean MGIs for the L and T groups were statistically significantly lower than the mean MGI for the control group.

Because the first two comparisons were for study validation, and the third was the primary comparison, no multiple-comparisons adjustment was made. All comparisons between treatment groups were two-sided and made at the .05 significance level. The same between-treatment and within-treatment comparisons were performed for the secondary variables of PI and BI, GSI and PSI.

To investigate examiner repeatability with respect to plaque and gingivitis, we selected and re-evaluated separate sets of 15 subjects at the baseline, three-month and six-month examinations. Reliability was assessed by means of the intraclass correlation coefficient (R), which is defined from an ANOVA with subject as a factor. The intraclass correlation coefficient R was calculated by dividing the difference of the between-and within-subject mean squares by the sum of their mean squares.²⁰

	RESULTS

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Three hundred sixteen subjects entered the study, with 105 in the P group, 105 in the L group and 106 in the T group. At six months (the primary time point of interest), 303 subjects made up the study population (100 in the P group, 101 in the L group and 102 in the T group). No statistically significant differences were seen among the three groups with respect to demographic or baseline variables (Table 1).

Gingivitis severity index. The GSI¹⁹ has been reported in studies investigating Colgate Total, and we also calculated the GSI for all subjects (Table 2). The GSI was lower for subjects in both the L and T groups than for subjects in the control group (P). Although Listerine Antiseptic was significantly more effective than Colgate Total in regard to GSI at three months (P < .001), statistical analysis was not performed at six months; since most subjects in both treatment groups had a mean GSI score of 0 (that is, no sites scoring 3 or 4 for MGI), statistical analysis would not have been meaningful. The mean GSI score was 0 for 85 percent of subjects in the L group, 0 for 83 percent of subjects in the T group and 0 for 27 percent of subjects in the P group, denoting the substantial improvement in both active treatment groups.

Bleeding index at six months. At six months, subjects in both the L and T groups had statistically significantly lower whole-mouth mean BI than subjects in the control group (P < .001), with differences of 70 and 58 percent, respectively. Although the L group had a statistically significantly lower (28.6 percent) six-month whole-mouth mean BI than the T group (P = .033), the magnitude of this difference was small.

Percentage of bleeding sites. The mean percentage of bleeding sites at six months was 10.5 percent, 3.5 percent and 4.3 percent for the P, L and T groups, respectively, indicating a clinically meaningful benefit for both the L and T groups compared with the P group. By comparison, the mean percentage of sites that bled at baseline for subjects who completed the study was 11.4 percent, 11.7 percent and 10.4 percent for the P, L and T groups, respectively.

BI at three months. At three months, subjects in the L and T groups had statistically significantly lower whole-mouth mean BI than subjects in the control group (P < .001). The difference in mean BI between the L and T groups did not reach statistical significance (P = .080). Three- and six-month BI was lower than baseline BI for all groups.

Results from this invasive BI measure of gingivitis as well as from the noninvasive MGI measure demonstrated clinical improvement in both of the active treatment groups.

Plaque index. At six months, subjects in the L and T groups had a statistically significantly lower whole-mouth mean PI than subjects in the control group (P < .001), with 56.1 percent and 22.1 percent differences, respectively. The L group had a statistically significantly lower six-month whole-mouth mean PI score than the T group (P < .001), with a difference of 43.6 percent. Subjects in both the L and T groups had statistically significantly lower three-month whole-mouth mean PI scores than subjects in the control group (P < .001), with 35.4 percent and 12.1 percent differences, respectively. The L group had a statistically significantly lower three-month whole-mouth mean PI score than the T group (P < .001), with a difference of 26.5 percent.

Plaque severity index. We calculated the PSI for all subjects. At six months, subjects in the L and T groups had reductions of 85.9 and 44.6 percent, respectively (P < .001), compared with the control group. The L group demonstrated a 74.6 percent reduction compared with the T group (P < .001).

Examiner repeatability. The intraclass correlation coefficients for mean MGI and mean PI were at least 0.990 during the course of the study, which is evidence of excellent repeatability.

Safety. No product-related adverse events were reported or observed during this study. The presence of extrinsic tooth stain and supragingival calculus was noted during the oral examination; however, there was no difference among the groups. Examiner comments indicated that stain observed was found primarily on the lingual aspect of the mandibular teeth. No subjects complained of stain or calculus.

	DISCUSSION

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Many independent double-blind, long-term studies have demonstrated the antiplaque and antigingivitis efficacy of commercially available Listerine Antiseptic mouthrinse and Colgate Total toothpaste. These studies were conducted according to the 1986 American Dental Association Council on Dental Therapeutics guidelines.¹ Reductions in plaque during the study periods ranged from 12 to 59 percent for Colgate Total²¹ and from 14 to 36 percent for Listerine.²² Gingivitis reductions ranged from 19 to 30 percent for Colgate Total and from 11 to 36 percent for Listerine. The magnitude of the reductions in our study is consistent with these findings.

This clinical study, conducted in a population of generally healthy adults with slight-to-moderate levels of gingival inflammation and dental plaque, and with no evidence of severe periodontal disease, demonstrated that twice daily use of a chemotherapeutic mouthrinse containing essential oils (Listerine Antiseptic) or a chemotherapeutic dentifrice containing triclosan and copolymer (Colgate Total) provided clinically and statistically significant reductions in supra-gingival plaque and gingivitis, compared with a control regimen (standard fluoride toothpaste and inactive mouthrinse). In addition, Listerine Antiseptic, when used in conjunction with a fluoride toothpaste and usual oral hygiene, provided a 43.6 percent greater benefit in reducing plaque than Colgate Total used with a placebo mouthrinse.

	CONCLUSION

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This clinical trial demonstrated clinically and statistically significant reductions in gingivitis and plaque when Listerine Antiseptic or Colgate Total was used in conjunction with usual oral hygiene for six months. Although similar reductions in gingivitis and bleeding were observed with the two products, Listerine Antiseptic produced a significantly greater benefit in reducing plaque. Therefore, when recommending an antiplaque/antigingivitis product to patients, dental professionals can consider use of Listerine Antiseptic, in conjunction with usual oral hygiene, if more rigorous plaque control is desired.