Summary Antimicrobial mouthwashes are considered to reduce dental plaque biofilm and therefore have the potential to prevent plaque-induced oral diseases, particularly periodontal diseases. The effectiveness of mouthwashes is related to this antiplaque function , as well as their potential to whiten teeth and their ability to mask or control bad odor (halitosis). There is also growing interest in the use of mouthwashes as an adjunctive measure in post-surgical and post-dental care, while the COVID-19 pandemic has given new life to mouthwashes as an oral antiseptic that may be useful in reducing viral load oral. The mode of action of mouthwashes varies depending on their active ingredients, concentrations, and mode and frequency of use, as well as their potential effectiveness. This article aims to provide a narrative overview of the evidence for the effectiveness of the most commonly used mouthwashes in the management of oral diseases, oral conditions and complementary care functions. |
Background
Antimicrobial mouthwashes aim to reduce dental plaque biofilm and therefore have the potential to mitigate in particular the two main plaque-induced oral diseases: caries and periodontal disease . The effectiveness of mouthwashes is related to this antiplaque function, as well as their potential to whiten teeth and their ability to mask or control bad odor (halitosis). There is growing interest in the use of mouthwashes as an adjunctive measure for post-surgical and post-dental treatment care, and there is a resurgence of interest in the use of pre-procedural mouthwashes, particularly since the emergence of COVID-19.
The mode of action of mouthwashes varies, depending on their active ingredients, concentrations and mode and frequency of use; as well as its potential effectiveness. This article aims to provide a narrative overview of the evidence for the effectiveness of the most commonly used mouthwashes in the management of oral diseases, oral conditions and complementary care functions. In particular, we describe in detail the following six different mouthwashes that contain chlorhexidine, fluoride, essential oils, cetylperidinium chloride, povidone iodine and hydrogen peroxide as main ingredients.
Chlorhexidine
Chlorhexidine glucoronate (CHX) is one of the most frequently evaluated mouthwashes. Findings from a 2017 Cochrane review found “high-certainty evidence” of a large reduction in dental plaque with daily use of chlorhexidine mouthwash as an adjunct to mechanical oral hygiene procedures for 4 to 6 weeks, compared with no mouthwash, placebo mouthwash, or control mouthwash (SMD -1.45; 95% CI -1.00 to -1.90 from an analysis of 12 clinical trials with 950 participants).
Fewer studies have been done on long-term use, but the findings suggest that adjunctive use of chlorhexidine daily for 6 months results in similar “high-certainty evidence” of a large reduction in dental plaque compared to placebo /control mouthwash (SMD - 1.59, 95% CI -1.29 to -1.89 from an analysis of 9 trials with 1933 participants).
There is "high-certainty evidence" that chlorhexidine reduces gingivitis in people with mild gingival inflammation. Evidence from the (same) Cochrane systematic review showed that after 4 to 6 weeks of use of chlorhexidine mouthwash, there was a mean reduction in gingival index scores (on a scale of 0 to 3) of 0.21 ( 95% CI, 0.11 to 0.31) compared with placebo/control mouthwash or no mouthwash (based on analysis of ten trials with 805 participants). This effect was maintained at 6 months, with a mean difference in gingival index scores of 0.20 (95% CI, 0.11 to 0.30) for chlorhexidine mouthwash compared to placebo/mouthwash control or no mouthwash (based on analysis of 13 trials of 2,616 participants).
Chlorhexidine has been defended as an anti-caries agent given its effectiveness in reducing the levels of Streptococcus mutans during and after its use, although there is a clear need for studies of higher quality and longer duration to evaluate whether the results translate into less development of dental caries.
A 2019 Cochrane review concluded that chlorhexidine mouthwash may play a role in reducing levels of halitosis -producing bacteria , although it found “very low-certainty evidence ,” given the quality and quantity of the studies.
Chlorhexidine also has a potential role as an adjunct care measure to promote healing. A 2023 systematic review on the complementary use of mouthwashes on gingival health after surgical procedures found evidence of improved "healing" compared to a negative control. Among the 13 studies that reported the review, the majority related to the use of chlorhexidine mouthwashes (n = 8) of various concentrations. Overall, there was an unclear risk of bias in the majority of clinical trials included in the review, preventing definitive conclusions. A 2022 Cochrane review reported that there is “moderate-certainty evidence” that chlorhexidine mouthwashes (0.12% and 0.2% concentrations), used before and after extraction, reduce the risk of developing dry socket . dry (odds ratio 0.38 (95% CI, 0.25 to 0.58) compared to a placebo mouthwash.
CHX also has a potential role in other environments. A 2020 Cochrane systematic review found that CHX probably ("low-certainty evidence") reduced the incidence of critically ill patients experiencing ventilator-associated pneumonia , from 26% to 18%. There has been renewed interest in pre-procedure mouthwashes, particularly since the emergence of COVID-19. A Cochrane review found a lack of comprehensive studies to report whether mouthwashes given to patients with suspected or confirmed COVID-19 improved patient outcomes. and protected the health care workers who treated them. However, over time, with increased focus of studies, the role of chlorhexidine and indeed that of other mouthwashes will be confirmed for dentistry and other settings.
Fluoride
Mouthwashes containing fluoride have long been recommended for oral health and, in particular, for their role in preventing tooth decay. Sodium fluoride is the most commonly used fluorinated agent in mouthwashes. The concentration of fluoride in parts per million (PPM) in mouthwashes varies; The amount of fluoride in over-the-counter mouthwashes generally ranges between 200 and 1,000 ppm, and prescription fluoride mouthwashes can have fluoride concentrations of several thousand ppm.
In general, over-the-counter fluoride-containing mouthwashes are for daily use and prescription fluoride-containing mouthwashes are used less frequently. While it is recognized that fluoride has an antiplaque role, there is limited specific evidence available on the effectiveness of fluoride mouthwashes on dental plaque levels and, furthermore, evidence is lacking on their effectiveness in relation to gingivitis and periodontal diseases. .
In terms of dental caries , a 2016 Cochrane review of 37 trials involving 15,813 children and adolescents found that fluoride-containing mouthwashes were associated with a large reduction in increases in caries in permanent teeth; this was interpreted as “moderate quality of evidence” . The combined decayed, missing, and filled tooth surfaces due to caries preventive fraction (PF) from 35 trials (15,305 participants) were 27% (95% CI, 23% to 30%; I 2 = 42%). The combined PF D(M)FT of 13 trials was 23% (95% CI, 18% to 29%; I² = 54%). Evidence for the effectiveness of fluoride-containing mouthwashes in preventing and arresting coronal caries in adults is less available and, in particular, there is a lack of evidence regarding their effectiveness in root caries. In other respects, there is a dearth of studies to inform the debate about its potential role.
Essential oils
There are a range of essential oil mouthwashes that contain active ingredients such as eucalyptol, menthol and thymol , among others, and they have various trade names. Its effectiveness is mainly related to its antimicrobial and anti-inflammatory properties. A systematic review evaluating the efficacy of essential oil mouthwashes reported that they are superior to placebo and mechanical plaque control (MPC) for the reduction of plaque and gingival inflammation in patients with gingivitis.
Reductions in plaque and gingivitis were, respectively, 32% and 24% greater with essential oils plus mechanical plaque control (MPC) than with placebo. The weighted mean difference (WMD) was lower for essential oils plus MPC than for placebo plus MP: the Quigley-Hein plaque index (QHI) was -0.86; 95% CI: −1.05 to −0.66; The modified gingival index (MGI) was −0.52; 95% CI: −0.67 to −0.37). High heterogeneity was evident across studies in terms of study designs, monitoring of mouthwashes, provision of oral hygiene instruction, and participant profile.
Regarding the effectiveness of essential oils against dental caries , a systematic review stated that most of the knowledge in the literature is based on in vitro studies evaluating the effects of essential oils on streptococci (mainly Streptococcus mutans ) and lactobacilli related to caries and that there are a limited number of in vivo clinical trials . A narrative review suggests that there is considerable evidence that essential oil mouthwashes are effective in preventing and treating halitosis, although only a few clinical studies have investigated this. Essential oils have also been suggested to have antiviral properties, underlying a potential role as pre-procedural mouthwashes.
Cetylpyridinium chloride
A 2021 systematic review stated that cetylpyridinium chloride (CPC) was effective in controlling both plaque and gingival inflammation at interproximal sites. A meta-analysis of 8 studies using CPC mouthwashes reported that there was a significantly greater reduction in plaque index score (MD; 95% CI, −0.70, −0.83 to −0.57) compared with the placebo groups. Similarly, at interproximal sites, there was a significant reduction in gingival index scores (MD; 95% CI, −0.38, −0.47 to −0.28) when CPC mouthwashes were used compared with the placebo. It is noteworthy that high heterogeneity was evident in both analyzes (I 2 = 89% and I 2 = 98%, respectively).
A previous systematic review (2008) suggested that mouthwashes containing cetylpyridinium chloride (CPC), when used as an adjunct to supervised or unsupervised oral hygiene, provide a small but significant additional benefit in reducing plaque buildup and gingival inflammation. Mouthwashes containing CPC appear to have antimicrobial activity with implications for caries prevention.
However, specific evidence of the effectiveness of CPC in preventing dental caries in vivo is lacking to confirm its role. CPC is known to inhibit the production of volatile sulfur compounds and thus its potential role in the treatment of halitosis , but there is limited evidence from clinical trials. CPC-containing mouthwashes have been suggested to have potential for preprocedural use given their effectiveness in reducing SARS-CoV-2 viral loads, although limited studies and evidence preclude a consensus on the role of mouthwashes. that contain CPC.
Povidone iodine
Povidone -iodine (PVP-I) is a broad-spectrum antiseptic that has long been used in wound care and surgical settings. It has potential efficacy against a wide range of microorganisms, including bacteria, viruses, fungi, and protozoa. Mouthwashes containing povidone-iodine (PVP-I) have also been developed and their role in oral health has been considered.
A 2010 systematic review stated that there is a “small” additional beneficial complementary effect with the use of PVP-I in non-surgical periodontal treatment in terms of greater reduction in probing pocket depth (0.28 mm; CI 95%, 0.08 to 0.48). 20 The potential of mouthwashes containing PVP-I to disinfect cariogenic bacteria and biofilms has been noted , although clinical studies are lacking.
A systematic review claimed evidence supporting PVP-I-containing mouthwashes for the prevention of chemotherapy-induced oral mucositis , although the findings came from a single randomized controlled trial. 22 A 2016 Cochrane review found “very weak evidence” that mouthwash containing PVP-I was more effective than saline/placebo in preventing ventilator-associated pneumonia among critically ill patients (RR, 0.69; CI 95%, 0.50 to 0.95; 3 studies, 356 participants, high risk of bias, I 2 = 74%).
A 2022 systematic review provides evidence of the effectiveness of PVP-I mouthwashes in reducing the number of negative reverse transcription polymerase chain reactions in patients with COVID-19, although additional studies with adequate randomization are required to improve the evidence base. 24
Hydrogen peroxide
Hydrogen peroxide ( H 2 O 2) is a typical “active” ingredient in teeth whitening agents , with a solvent base of water or water with ethanol and excipients including buffers, surfactants and flavorings. Hydrogen peroxide in concentrations of 10% carbamide peroxide (equivalent to 3% hydrogen peroxide) is used for home and in-office teeth whitening. However, hydrogen peroxide can also be used in mouthwashes to whiten teeth using the same mechanism. However, due to concerns about chemical irritation of oral tissues , hydrogen peroxide concentrations are lower in mouthwashes, typically 1.5% w/vol or less.
For the most part, the effectiveness of mouthwash containing hydrogen peroxide for whitening teeth has been based on evidence from laboratory studies, for example, color-changing effects on bovine teeth with extrinsic stains. A 2018 Cochrane review identified a clinical study with 78 participants who used a 1.5% hydrogen peroxide mouthwash and found only “weak evidence” that this improved the shade of their teeth compared to placebo.
A 2011 systematic review concluded that mouthwashes containing hydrogen peroxide do not consistently prevent plaque buildup when used as short-term monotherapy. Regarding periodontal health , a study from the same systematic review stated that mouthwash containing hydrogen peroxide used as a long-term complement to daily oral hygiene can reduce gingival redness.
Hydrogen peroxide has been suggested to have anti-cancer effects and potentially improve remineralization , but overall there is a paucity of clinical studies supporting the effectiveness of mouthwashes containing hydrogen peroxide. There is some evidence of the potential of mouthwashes containing hydrogen peroxide in the treatment of halitosis .
A 2020 systematic review found a lack of studies related to the virucidal effects of mouthwash containing hydrogen peroxide. However, as with other mouthwashes, those containing hydrogen peroxide have been suggested as a potential type of mitigation against SARS-CoV-2 infection.
Final comments and other considerations
In summary, regardless of the mouthwash used, there appears to be strong evidence for its effectiveness in reducing plaque, and this is an important consideration given that most oral diseases are related to plaque. Currently, most evidence supports the use of chlorhexidine . In particular, there is also considerable evidence on the effectiveness of mouthwashes as a complement to conventional oral hygiene regimens in preventing and improving gingival health.
Given the role of mouthwashes in gingivitis , it is assumed that they have a role in preventing periodontitis and improving periodontal health, but the evidence for their role and their effectiveness at this stage of gum disease is less available in terms of quantity and quality of evidence.
Regarding their effectiveness in preventing dental caries , apart from fluoride-containing mouthwashes, the evidence mostly relates to the effects of mouthwashes on cariogenic plaque in vitro , rather than the status of dental caries. in vivo , and therefore, further studies of high-quality mouthwashes are needed in relation to caries in the human host.
For fluoride -containing mouthwashes , there is moderate-quality evidence for their effectiveness with adjunctive use in preventing coronal caries among children and adolescents . There is also less evidence, in terms of quality, on the effectiveness of mouthwashes in preventing root caries in adults . This is important to consider, given the differences that exist in terms of risk factors and progression of root caries compared to coronal caries, as well as the increasing challenge of root caries in aging populations that increasingly retain natural teeth. .
In terms of halitosis management , it again appears that mouthwashes may play a role in masking or controlling halitosis, although managing the underlying cause of halitosis through non-surgical periodontal care is key to success.
Mouthwashes may play a role in teeth whitening , and specifically mouthwashes containing peroxide, but studies are limited and the evidence mostly relates to in vitro studies. Such laboratory studies may not consider the effects of dilution and inactivation by saliva and therefore overestimate the effects compared to clinical bleaching. Limitations inherent to the use of whitening mouthwashes include a short contact time with teeth and that low pH mouthwashes potentially “soften” enamel and cause increased tooth wear, especially if used before brushing.
Other areas to consider using mouthwashes effectively include postsurgical healing, chemotherapy-induced mucositis, and treatment of alveolar osteitis (dry socket). To date, the quantity and quality of evidence for their use in these areas is limited, but is promising for the future if mouthwashes are used as part of a complementary management approach to oral health care. It remains to be seen, among the many agents described, which mouthwash would be “most effective” , and this is not addressed here. There has also been great interest in the antiviral properties of mouthwashes since the start of the global COVID-19 pandemic, and this remains of great interest, with further in vivo research required.
Overall, for the most part, the evidence for the effectiveness of mouthwashes is based on the literature related to widely available over-the-counter commercial products , with these being the most studied products. The more products are studied, the more abundant literature will be available to confirm or refute their effectiveness. Therefore, this review focused on the active ingredients of the most commonly available over-the-counter mouthwashes globally. It is recognized that there is evidence of other less frequently used mouthwashes, and also promising evidence, but their inclusion is beyond the scope of this narrative review and therefore this will be addressed in another article.
There is strong evidence that many OTC mouthwashes appear to be effective as adjuncts in some areas of oral health care, but evidence of the effectiveness of mouthwashes in many areas continues to emerge, with implications for perioperative oral care in the dental environment and beyond.
Money
The authors have not received any commercial sponsorship directly or indirectly for this review. The narrative review reflects the authors’ opinions based on the evidence considered for the active ingredients of the most widely available mouthwashes. The opinions of the authors should not necessarily be construed as the opinions of their colleges, universities, or associated organizations.
