Evaluation of the Antiplaque Efficacy of Chlorhexidine Mouthwash immediately and 30 min after Brushing with Fluoride Toothpaste - A pilot study

INTRODUCTION

Various chemotherapeutic agents have been used as adjuncts to the mechanical control of plaque, and among them, chlorhexidine (CHX) has earned its eponym of the gold standard.¹ It has been widely used as an antiseptic agent for skin and mucous membrane disinfection. In dentistry, chlorhexidine is used in various forms, such as mouth rinses, oral irrigations, and slow-release devices. Chlorhexidine molecule is a cationic compound composed of two symmetrical structures with four chlorophenyl rings and two biguanide groups linked by a central hexamethylene bridge. CHX binds non-specifically to negatively-charged membrane phospholipids of bacteria. At low concentrations, CHX affects the change in the osmotic balance of the bacteria cell which leads to the release of potassium, phosphorus, and other low weight molecules.²

CHX is known for its substantivity lasting for 8-12 hours after a single rinse³ , but it also has a propensity to react with anionic surfactants and other anionic compounds, thereby affecting its activity.^4,5 Most of the Toothpastes contains anions like fluorides and sodium lauryl sulfate, which interacts with chlorhexidine and form salts of low solubility.6–8 Combinations of chlorhexidine and Monofluorophosphate (MFP)have been shown to provide reduced amounts of both ions.⁶ Considering these interactions with the components of dentifrices, appropriate interval between toothbrushing and rinsing with CHX is proposed to be more than 30 minutes, cautiously close to 2 hours after brushing.⁵ Although many in-vitro studies have been conducted evaluating these interactions, the effects on clinical parameters have been poorly studied. The purpose of the present study was to compare the antiplaque efficacy of chlorhexidine mouth wash immediately and 30 minutes after brushing with fluoride toothpaste.

Materials and methods:

Periodontally healthy subjectswith in the age group of 18-50 years and with a complete set of dentition,who came to the department of periodontics, GSL dental college were selected. Subjects with systemic diseases, Patients taking any medication, especially antibiotics, patients having orthodontic appliances or prostheses, were excluded from the study. Forty subjects were selected and randomized into test and control group.

Following a clinical examination,Oral hygiene index (OHI), and Gingival index (GI) were recorded. Plaque index (PI) was recorded by using disclosing solution (GC Tri Plaque ID Gel™, USA)whichwas gently applied with a swab, micro brush, or cotton pellet. Both groups received thorough dental prophylaxis at the beginning of the test period.

The control group (n=20) was advised to use CHX mouth wash 30 min after brushing with fluoridated toothpaste (Colgate® caries protection, Colgate-Palmolive Co), and the test group (n=20)was advised to use CHX mouth wash immediately after brushing with fluoridated toothpaste. All the participants were provided with the same dentifrice, mouthwash, and toothbrush (Colgate® Slim soft toothbrush, Colgate-Palmolive Co). Both groups were instructed to use 10 ml, 0.2% chlorhexidine gluconate (Hexidine® ICPA) for 60 sec. Patients were asked not to brush teeth, or not to eat and drink immediately after using Chlorhexidine gluconate oral rinse.

Plaque index (PI), Oral hygiene index (OHI), and Gingival index (GI) were again recordedat the end of 14 days for both the groups.

Results

Intra-group comparisons were made to assess the difference of Plaque index, gingival index, OHI-S at baseline, and 14 days in both test and control groups using the paired t-test. Intergroup comparison was made with an independent sample t-test to assess the difference in the Plaque index, gingival index, OHI-S.

Statistically significant differences were observed in all the parameters in Intra-group comparisons but not in Inter-group comparison

Discussion

CHX is recognized as the standard criterion drug for plaque and gingivitis control in periodontitis.⁹ At the end of a single rinse with CHX mouthwash, around 33% of the active ingredient remains on the oral mucosa.³ Using 0.12-0.2% concentrations of CHX in mouthwashes results in a significant reduction of gingival inflammation and plaque indexes.¹⁰ Several studies, systematic reviews, and meta-analysis have confirmed the efficacy of Chlorhexidine on inhibition of plaque accumulation and gingivitis.^11–14 The present study is also in tandem with these studies and showed a statistically significant reduction in PI, GI, and OHI scores both in control as well as test groups.

Even though CHX is a very effective antiseptic agent, its efficacy is thought to reduce due to its interaction with various ingredients of dentifrices. Some studies postulate that the efficiency of CHX could be inhibited by certain anionic surfactants, particularly sodium lauryl sulfate (SLS) and the monofluoride phosphate present in commercial toothpaste, supposedly due to the multiple chemical reactions between these compounds. Sodium lauryl sulfate (SLS) is the most commonly used surfactant to enhance the foaming action of a dentifrice. SLS has been reported to interfere with the antiplaque potential of CHX through the formation of low-solubility salts.¹⁵ Other studies suggested that an SLS-based mouthwash can deactivate CHX for up to 30 minutes after its use.^5,7,16 Fluoride is another agent used in dentifrices for its anti-caries action. Ionic reactions between fluoride and chlorhexidine may result in a decreased concentration of chlorhexidine.¹⁷ It is thought that the first two compounds (being negatively charged) bind with CHX, thereby reducing its activity, and these ingredients may also compete for the binding sites of CHX, thus causing an accelerated clearance of the molecule from oral tissues.¹⁶Hence, it was proposed that time (at least 30 minutes) should elapse between brushing performed at home and the use of CHX mouthwash.

More recent randomized clinical trials, however, have shown that the anti-plaque activity of CHX is not altered by using chlorhexidine rinse before or after brushing with a toothpaste containing SLS.^18,19 The most recent findings, therefore, do not suggest a reduced efficacy of CHX when used as a mouthwash in combination with a commercial toothpaste as part of a regular oral hygiene routine. On the contrary, brushing (with or without toothpaste) is essential to breaking up and removing the oral biofilm, exposing the bacteria to the antibacterial agent, and making the tooth surface more favourable to CHX adhesion. Plaque removal before rinsing leads to increased efficacy of CHX mouthwash and a reduction in its local adverse effects.²⁰ This uncertainty has raised speculations and has created a topic for debate.

In the present study, the dentifrice used consists of Sodium monofluorophosphate 0.76% (0.15% w/v fluoride ion) and the surfactant sodium lauryl sulfate 1–5 % (Colgate® caries protection, Colgate-Palmolive Co.).

In the present study, no statistically significant difference was observed in PI, GI, OHI-S in patients who are using mouth wash immediately and 30 min after tooth brushing, suggesting there is no decrease in efficiency of chlorhexidine clinically. This is in tandem with recent studies. The Limitation of this study includes the possibility of Hawthorne Effect. Further studies are required with microbial analysis, and more sample size and varying concentrations of chlorhexidine to validate the findings.

Conclusion

Literature relating to this interaction is limited; more controlled microbiologic and clinical studies are needed to certify the accuracy of this modality of administration. As per the present study, CHX mouthwash may be recommended in combination with a dentifrice without any interference.