Effectiveness of propolis in maintaining oral health: a scoping review

Abstract

Background:

Research has revealed that periodontal diseases are caused by inflammation that results from a dysbiosis of the oral microbiome where oral bacteria multiply into larger communities referred to as dental biofilm. To help control this overgrowth of bacteria, a variety of toothpastes, dentifrices, and mouthwashes have been developed. Although not as common in North American toothpastes, propolis as an active ingredient in dentifrices has begun to emerge, as laboratory studies have suggested it has anti-inflammatory, immunomodulatory, antioxidant, antimicrobial, and antidiabetic properties. The purpose of this scoping review was to explore the literature on the effectiveness of propolis in maintaining oral health.

Methods:

This review used the following criteria: Population: studies involving healthy humans; Intervention: propolis in the form of toothpaste, dentifrice, and mouthwash; Comparison: fluoride, chlorohexidine, and placebo; Outcomes: plaque and gingival indices, improvement in oral hygiene, and inhibition of bacteria. Relevant research articles were selected from Web of Science, PubMed, MEDLINE, and Scopus databases using the search parameter “propolis[tw] AND (toothpaste*[tw] OR dentifrice*[tw] OR mouthwash*[tw])”. Only original articles published after 2009 and written in the English language were included.

Results:

A total of 19 original papers met the criteria and showed varying levels of success achieved with the use of propolis. It was responsible for a significant lowering of specific plaque and gingival indices, inhibited the growth of bacteria, reduced oral flora diversity, and consistently improved periodontal condition, oral hygiene, and oral health.

Conclusion:

Propolis may play a role in initiating, sustaining, and maintaining oral health as its desirable properties have the potential to improve various oral hygiene related indices.

INTRODUCTION

In recent years, there has been much interest in oral health education programs, with the main aim of increasing the adoption of favourable oral health behaviours that are expected to translate to better oral health. ¹ At the same time, there has been an increase in demand for evidence that can help both policymakers and individuals make better choices regarding oral health. ¹ Since many individuals are now aware of and concerned about improving their oral health, there is sustained support for the development of new products and substances to keep the oral cavity clean and healthy. ² Some of these products have emerged as a result of extensive research aimed at finding the best ingredients to sustain oral health with few or no side effects. Understanding the role of dental biofilm is important to the development of new anticariogenic and antigingivitis/periodontitis products. Biofilms commonly comprise both Gram-positive and Gram-negative microbes which, when out of balance, can lead to dental caries and periodontal disease. ³ Dental biofilm has been shown to be a soft, non-mineralized bacterial deposit that adheres to the hard surfaces of the oral cavity when adequate oral hygiene is not sustained. ⁴

Poor oral hygiene is one of the factors leading to the imbalance of the oral microbiome, referred to as dysbiosis. Studies have shown that only a limited quantity of pathogenic bacteria are present at a healthy site in a host, which suggests, therefore, that oral diseases are caused by dysbiosis. ⁵ When microbial dysbiosis occurs, an overgrowth of pathogenic bacteria creates a community of microbes in the form of a biofilm. ⁶ Since dysbiosis results in biofilm formation, the rational thing is to destroy or reduce the population of these bacteria in the mouth, either by mechanical or chemical means, such as the use of toothpastes and mouthwashes. ^3,7 Toothpastes and mouthwashes have gained wide acceptance because of their perceived benefits, and especially because of sustained advertising and marketing. ^3,7,8 Their popularity reflects the tendency among consumers to seek food or pharmaceutical products that can help them achieve healthier lives. ⁹ Unfortunately, many people purchase and use these products without verifying their efficacy; marketing campaigns may not be a guarantee of efficacy or antibacterial activity in the case of toothpastes. ¹⁰

There are varying compositions, consistencies, and types of toothpastes and mouthwashes available in the North American market. One of the most commonly used ingredients is stannous fluoride, which has undergone years of research and has shown effective antibacterial properties. More recently, herbal products containing natural compounds such as mentha, guarana, eucalyptus extract, mastic, Arab acacia, and miswak, all of which also have significant antibacterial properties, have been introduced. One of these natural compounds is propolis, which has been used in many toothpastes, mouthwashes, and dentifrices as an important natural product in preventing oral diseases. ^8,11-13

Propolis, also known as bee glue, is a dark-coloured, dense, and adhesive combination of resin and wax, consisting of active natural ingredients such as volatile oils, plant balsams, phenolic acids, flavonoids, aromatic alcohols, fatty acids, mineral salts, and vitamins. ¹⁴ It is collected by honeybees from trees, buds, flowers, and other botanical products. ^15,16 It is well established from laboratory-based st,udies that propolis has antibacterial, anti-inflammatory, antioxidant, antiviral, antifungal, antitumour, and hepatoprotective properties. ^12,13,16,17 The chemical composition of propolis is 50% to 60% resin, 30% to 40% wax, 5% to 10% essential oils, 5% pollen, along with some microelements. ^13,18,19

To demonstrate the health benefits of propolis, some studies have shown that its application can heal oral ulcers and gingivitis in many clients. ^16,20,21 It has activity against Streptococcus mutans , facultative anaerobes, and Gram-positive cocci within the oral cavity. In addition, multiple studies have shown that the ability of propolis to kill periodontal pathogens may be of significant clinical value. ^22-24 To harness this huge potential, many companies have added propolis to their toothpaste and mouthwash products with the aim of preventing tooth decay and gingivitis. ¹³ The use of varying types of toothpastes, dentifrices, and mouthwashes containing propolis has been shown to have excellent anti-inflammatory effects in addition to facilitating biofilm removal and prevention. ²⁵

It is important to evaluate the specific roles of propolis in the oral cavity, given various studies that have reported clinical outcomes regarding its potential benefits. Therefore, this study aimed to review and evaluate the literature on the role of propolis in achieving and maintaining oral health.

METHODOLOGY

This review included studies involving healthy humans, with an intervention based on the use of propolis in the form of toothpaste, dentifrice, and mouthwash. A comparison was made with other oral hygiene maintaining agents such as fluoride, chlorhexidine, and placebo. The studies reporting outcomes on plaque and gingival indices, impact on oral hygiene, and changes in bacterial load were included. Relevant research articles were sought and selected from Web of Science, PubMed, MEDLINE, and Scopus databases. The following search parameter was entered into the search engine: “propolis[tw] AND (toothpaste*[tw] OR dentifrice*[tw] OR mouthwash*[tw])”. This search parameter was based on 4 major keywords: propolis, toothpaste, dentifrice, and mouthwash. Articles were selected based on originality (primary research papers), the use of toothpastes and/or dentifrices and/or mouthwashes containing propolis in the study, and follow-up periods of 2 weeks or more. In addition, only randomized, non-randomized, and cohort clinical studies published from 2009 to 2020 and written in English, utilizing green or red propolis, were included in the review. Narrative reviews and case–control studies were excluded. Studies involving subjects with denture-based stomatitis, tumours or those undergoing chemotherapy were excluded.

Assessment of the quality of the studies was based on the study design, the methodologies adopted, and the outcomes. Data were extracted using tables that identified the characteristics of each study’s participants, type of intervention (propolis alone, propolis versus placebo, propolis versus other agents), and the outcomes of the study.

RESULTS

The parameters produced a total of 237 citations. Of those 237 studies, 94 were duplicate studies and 40 studies were discarded because they were written in a language other than English and were older than 2009. An additional 23 articles were discarded because they were not clinical studies (including a review article, an editorial, a conference paper, and an erratum). The full text of the remaining 80 articles was examined in greater detail, from which 61 were either in vitro studies or did not fulfil the inclusion criteria. A total of 19 studies with methodologies and outcomes matching the focus of this review were included (Figure 1).

Plaque and gingival indices

Twelve studies evaluated plaque and gingival indices. The results of these studies revealed significant improvements in plaque accumulation and reduction in sulcular or papillary gingival bleeding when propolis was used compared to agents without propolis (Table 1).

Impact on oral hygiene

Five studies evaluated the impact of propolis-containing agents on oral hygiene. The outcomes showed that propolis-containing agents produced significant improvements in oral health (Table 2).

Figure 1.

Flowchart for identification, screening, and selection of studies

Source: http://prisma-statement.org/PRISMAStatement/FlowDiagram.aspx

Table 1.

Clinical studies showing the effect of propolis on plaque and gingival indices

No.	Author and year	Origin of propolis	Type of study and no. of subjects	Type of intervention	Results a	Outcomes
1	Furtado Junior et al. 2020 22	Brazil	Randomized clinical trial (n = 92)	Fluoride dentifrice with propolis incorporated vs fluoride dentifrice	Both groups significantly reduced the GBI	Dentifrice containing propolis demonstrated similar clinical activity to dentifrice containing fluoride only
2	Sparabombe et al. 2019 43	Italy	Randomized controlled clinical trial (n = 34)	Mouthwash containing propolis vs placebo	A statistically significant decrease in BS and PS compared with the placebo group	Propolis mouthwash in clients with moderate or severe periodontitis is effective in reducing BS and PS, after 3 months, compared with placebo
3	Dehghani et al. 2019 44	Undisclosed	Randomized clinical trial (n = 37)	Propolis mouthwash vs chlorhexidine mouthwash	Improvement in the plaque, gingival, and periodontal indices before and after administration of the experimental mouthwashes	There was no statistically significant difference between 2 mouthwash groups
4	Piekarz et al. 2017 45	Poland	Randomized clinical trial (n = 51)	Toothpaste with tea tree oil (TTO) and extracts of propolis (EEP) vs normal toothpaste	A statistically significant reduction of approximal PI and sulcular BI was observed after 7 and 28 days of using the toothpaste with TTO and EEP, as compared to the value upon the initial visit	The use of a toothpaste containing TTO and EEP helps to maintain gingival health The findings of the study do not specify whether the results were affected by the addition of TTO or EEP
5	Machorowska-Pieniazek et al. 2016 33	Brazil	Randomized clinical trial (n = 96)	Propolis vs placebo	A statistically significant reduction in GI and PI was recorded in the propolis group compared to placebo	Propolis may be an effective agent in improving gingival health
6	Ercan et al. 2015 12	Undisclosed	Randomized clinical trial (n = 10)	Propolis mouthwash vs propolis chewing gum	Significantly lower PI and GI were recorded in the propolis mouthwash group than in the propolis chewing gum group	Propolis mouthwashes are necessary for improved oral hygiene and reduced dental biofilm
7	Bhat et al. 2015 17	Undisclosed	Randomized clinical trial (n = 20)	Propolis vs miswak vs Colgate® Total	Propolis resulted in a consistently and significantly lower modified gingival marginal plaque index mean scores compared to Colgate® Total and miswak toothpastes.	Propolis is safe and effective in lowering biofilm accumulation
8	Fereidooni et al. 2014 46	Undisclosed	Randomized clinical trial (n = 40)	Toothpastes containing propolis vs normal toothpaste	The PI scores in propolis toothpaste was 28.8±6.1% and in regular toothpaste was 39.7±6.3%	Both toothpastes reduced PI, however reduction was greater in propolis toothpaste than regular toothpaste
9	Bretz et al. 2014 47	Brazil	Randomized controlled trial (n = 38)	Propolis mouthrinse vs 0.05% sodium fluoride plus 0.05% cetylpyridinium chloride mouth rinse	Propolis and control groups did not differ significantly for average papillary BS	Propolis rinse was equivalent to a positive control rinse during a 21-day no-hygiene period
10	Skaba et al. 2013 13	Brazil	Clinical cohort study (n = 64)	Propolis vs placebo	There was a decrease in approximal PI, OHI & sulcular BI when propolis was used compared to placebo	Propolis supports removal of dental biofilm and improves state of marginal periodontium
11	Machorowska-Pieniazek et al. 2013 14	Brazil	Randomized clinical trial (n = 41)	Propolis vs placebo	There was a statistically significant decrease in oral PI, GI, and the compared with baseline in propolis group subjects	Propolis is responsible for improved oral health in subjects
12	Pereira et al. 2011 48	Brazil	Prospective clinical trial (n = 25)	Propolis mouthwash alone	24% reduction in approximal PI and GI after 45 days and 40% reduction in approximal PI and GI after 90 days use of propolis mouthwash	Propolis mouthwash showed evidence of its efficacy in reducing PI and GI The study did not compare propolis with another agent, therefore, superiority of propolis over other agents cannot be suggested

^a GBI: Gingival Bleeding Index; BS: Bleeding Score; PS: Plaque Score; PI: Plaque Index; GI: Gingival Index; OHI: Oral Hygiene Index

Table 2.

Clinical studies showing the role of propolis in improving oral health

No.	Author and year	Origin of propolis	Type of study and no. of subjects	Type of intervention	Results a	Outcomes
1	Peycheva et al. 2019 49	Bulgaria	Randomized clinical trial (n = 70)	Marketed toothpastes vs toothpaste incorporating 10 drops of propolis extract	The cytokine levels in toothpaste incorporating propolis showed significantly lower levels of IL-1β and IL-18 when compared to the other group	The addition of propolis to the toothpaste resulted in a reduction of the gingival inflammation in adolescents with moderate gingivitis
2	Piekarz et al. 2017 45	Poland	Randomized clinical trial (n = 51)	Toothpaste with tea tree oil (TTO) and extracts of propolis (EEP) vs normal toothpaste	A statistically significant improvement in OHI value was observed after 28 days of using the toothpaste with TTO and EEP, as compared to the value upon the initial visit	The use of a toothpaste containing TTO and EEP helps improve oral hygiene The findings of the study do not specify whether the results were affected by the addition of TTO or EEP
3	Wiatrak et al. 2017 26	Poland	Randomized clinical trial (n = 37)	Propolis vs placebo	In the propolis group, there was a decrease in the number of isolated microorganisms, improvements in hygiene & condition of periodontium, & a reduction in oral flora diversity after 4 weeks of active toothpaste use as against the control group	Propolis improves oral hygiene and condition of the periodontium
4	Morawiec et al. 2013 25	Brazil	Randomized cohort study (n = 16)	Propolis vs placebo	Propolis-containing toothpaste was distinctively effective in improving oral health and the occurrence of gingivitis triggered by dental biofilm	Positive effect of propolis-containing toothpaste on oral hygiene
5	Tanasiewicz et al. 2012 50	Brazil	Randomized clinical trial (n = 80)	Toothpaste and gel containing propolis vs toothpaste and gel without propolis	Toothpaste and gel containing propolis showed effective results in improving OHI without causing pathological changes to the periodontium	The OHI improved after the use of toothpaste and gel containing propolis

^a GBI: Gingival Bleeding Index; BS: Bleeding Score; PS: Plaque Score; PI: Plaque Index; GI: Gingival Index; OHI: Oral Hygiene Index

Table 3.

Clinical studies showing the role of propolis in altering the pathogenic bacterial load

No.	Author and year	Origin of propolis	Type of study and no. of subjects	Type of intervention	Resultsa	Outcomes
1	Furtado Junior et al. 2020 22	Brazil	Randomized clinical trial (n = 92)	Fluoride dentifrice with propolis incorporated vs fluoride dentifrice	Fluoride dentifrice with propolis incorporated reduced Gram-negative and Streptococcus mutans bacteria significantly compared to fluoride dentifrice only	Dentifrice containing propolis demonstrated better microbiological activity compared to fluoride dentifrice only
2	Peycheva et al. 2019 51	Bulgaria	Randomized clinical trial (n = 70)	Marketed toothpastes vs toothpaste incorporating 10 drops of propolis extract	The addition of propolis resulted in the complete eradication of Streptococcus mutans, Candida albicans, Fusobacterium varium, Gram-negative cocci, Gram-positive rods, Porphyromonas asaccharolyticus, Prevotella bivia, Prevotella intermedia, Prevotella melani, and Streptococcus intermedius	The addition of propolis to the toothpaste resulted in a reduction of gingival inflammation in adolescents with moderate gingivitis
3	Mohsin et al. 2015 27	South Korea	Clinical-microbiological prospective study (n = 367)	Propolis alone	The mean Streptococcus mutans count at first and fourth weeks showed significant reduction, compared to baseline scores. Statistically significant difference was found between baseline & first week, third week & fourth week follow up	Propolis dentifrice reduced in vivo microbial load The study did not compare propolis with another agent, therefore, superiority of propolis over other agents cannot be suggested
4	Skaba et al. 2013 13	Brazil	Clinical cohort study (n = 64)	Propolis vs placebo	There was a time-dependent microbial action of propolis at 50 mg/L concentration, with antimicrobial activity against Gram-positive bacteria	Propolis improves the state of marginal periodontium
5	Netto et al. 2013 11	Brazil	Randomized clinical trial (n = 60)	Propolis mouthrinse vs 0.12% chlorhexidine mouthrinse vs placebo mouthrinse	Propolis was superior to chlorhexidine at 14-day and 28-day visits in suppressing the salivary levels of S. mutans Propolis was significantly superior to chlorhexidine in suppressing the levels of salivary lactobacilli at the 28-day visit	Propolis mouthwash was superior to chlorhexidine and placebo mouthwash at 28-day
6	Machorowska-Pieniazek et al. 2013 14	Brazil	Randomized clinical trial (n = 41)	Propolis vs placebo	There was a statistically significant decrease in the percentage of the Actinomyces spp. and Capnocytophaga spp. compared with baseline in propolis group subjects	Propolis is responsible for improved oral health in subjects
7	Morawiec et al. 2013 25	Brazil	Randomized cohort study (n = 16)	Propolis vs placebo	Propolis-containing toothpaste triggered qualitative & quantitative changes in oral bacteria spectrum	Positive biological activity of propolis-containing toothpaste on oral microbial flora

^aGBI: Gingival Bleeding Index; BS: Bleeding Score; PS: Plaque Score; PI: Plaque Index; GI: Gingival Index; OHI: Oral Hygiene Index

Changes in pathogenic bacterial load

Seven studies reported the effectiveness of propolis in altering the bacterial load. The outcomes suggested that propolis helped reduce the pathogenic bacterial load compared to other agents without propolis or placebo (Table 3).

DISCUSSION

From the results of the studies presented in the tables, it is evident that propolis has significant positive effects on gingival health, oral hygiene, and the reduction of pathogenic bacteria. It has been argued that the diverse chemical content inherent in propolis is responsible for its many useful properties. ⁸ Studies have shown that propolis has effective antibacterial activity against a range of oral pathogens. A study conducted by Yoshimasu et al. ²⁴ reported that certain compounds derived from propolis have bacteriostatic activities while other compounds have bacteriocidal properties against various oral species including Porphyromonas gingivalis. Considering its antibacterial, anti-inflammatory, antifungal, antiviral, anticancer, and immunomodulation abilities, it is easy to understand why propolis is useful for maintaining oral health. ²

Plaque index, gingival indices, and oral hygiene

The study by Bhat et al. ¹⁷ showed the effect of propolis in reducing the accumulation of dental biofilm. Among the group of 30 healthy students split into 3 groups, the Forever Bright (propolis-containing) tooth gel group had the lowest mean modified gingival marginal plaque index (MGMPI) score, which was significantly different from the other 2 groups. This double-blind randomized study demonstrated the ability of propolis-containing tooth gels or toothpastes to reduce the rate of biofilm accumulation, which is one of the major risk factors for poor oral health. ^13,17,26 This finding by Bhat et al. ¹⁷ is similar to results obtained in studies conducted by Ercan et al. ¹² and Skaba et al. ¹³

It can be argued that a confounding factor, which might have been responsible for the slow rate of biofilm accumulation in the Bhat et al. study, was the oral prophylaxis conducted before the start of the experiment. ¹⁷ The point of the oral prophylaxis was to remove calculus, as calculus on its own can promote the rate of formation of biofilm due to the rough surface that it provides. ¹⁷ However, by removing the calculus, all the subjects were rendered the same at baseline, which makes subsequent statistical deductions more precise and accurate. This procedure was also done in the study by Ercan et al. ¹² but not by Skaba et al., ¹³ even though they both recorded significant biofilm reduction with the use of propolis-containing agents. The study by Skaba et al., which did not perform oral prophylaxis before the experiment, corrected for this by focussing on the progressive reduction in plaque indices on subsequent visits of the study participants; the differences between the indices before and after the intervention were found to be significant. ¹³ Nevertheless, the results of the study by Skaba et al. raise a question of reliability as the lack of oral prophylaxis may make the results less generalizable and comparable to similar studies. ¹³

Similarly, the results of another study on 96 clients with orthodontic appliances showed a statistically significant reduction in the gingival index and plaque index among those who used Brazilian propolis toothpaste against the control. ¹⁴

Dentures are another potential source for providing a favourable environment for the growth of bacteria and dental biofilm, and worsening periodontal health. ²⁶ For clients with dentures and other prosthetic appliances, it is equally important to maintain optimal oral hygiene through use of products that can help prevent periodontopathy. Wiatrak et al. ²⁶ showed that propolis ,can achieve this result. In their randomized cohort study on 37 clients with acrylic partial dentures, they observed statistically significant reductions in the approximate plaque index, simplified Greene-Vermilion hygiene index, and gingival bleeding index after 7 to 28 days of application of propolis toothpaste. ²⁶

Changes in pathogenic bacterial load

In addition to biofilm reduction, propolis was also found to inhibit the growth of specific organisms. Mohsin et al. ²⁷ conducted a study investigating the effect of a dentifrice containing propolis on Streptococcus mutans. Study results revealed a statistically significant reduction in S. mutans by the third and fourth weeks. Although these findings provide some evidence to support the use of propolis in controlling bacterial biofilms, the study sample was small and not generalizable as the 30 male participants were between 7 and 12 years of age. Skaba et al. ¹³ also reported similar findings from a sample size (n = 32) of 15 male and 17 female clients. They reported the ability of propolis to inhibit the glucosyltransferase activity of Streptococcus mutans,Streptococcus sobrinus, and Streptococcus cricetus both in vivo and in vitro. ¹³

Other pathogens that have been found to be susceptible to the action of propolis include Lactobacillus rhamnosus, ²⁸ Actinomyces spp. and Capnocytophaga spp., ¹⁷ and Candida spp. ^13,14,25 Of particular interest are findings from a study conducted by Machorowska-Pieniazek et al. ¹⁴ who reported that 2 facultative anaerobic bacteria ( Actinomyces spp. and Capnocytophaga spp. ) in their samples were responsive to propolis, which significantly reduced their count. It is important to note that Streptococcus mutans was not found in this study, which is unusual. Previous studies have suggested that Streptococcus spp. and Actinomyces spp. coexist and are crucial in the early phases of the formation of dental caries. ^29,30 However, it is possible that the type of study population was responsible for this finding since all 41 non-syndromic cleft lip and palate subjects in the study had fixed orthodontic appliances. ¹⁴ It has been established that the presence of orthodontic appliances alters the oral environment, resulting in the presence of atypical flora. ^31,32 Nonetheless, propolis reduced this bacterial flora.

To further corroborate, another study by Machorowska-Pieniazek et al. in 2016 also reported the effectiveness of propolis in reducing the presence of Actinomyces spp. and Capnocytophaga spp., and many other isolated species in the oral cavity of denture wearers. ³³ However, the study by Wiatrak et al. ²⁶ observed the presence of Streptococcus mutans, which was absent in the study by Machorowska-Pieniazek et al. ³³

Other potential roles of propolis

Most of the studies reviewed focused on the influence of propolis in reducing the formation of biofilm and growth of microorganisms generated in vivo. However, it has been suggested that toothbrushes contaminated with microorganisms may also cause oral infections through their bristles. ^34-36 Even after eradicating those within the oral cavity, the use of the already contaminated toothbrush can reintroduce bacteria into the mouth, and the cycle begins again. This was the focus of the study by Bertolini et al. ³⁴ who compared the ability of Aloe vera and propolis to reduce the contamination of toothbrush bristles by Streptococcus mutans. Even though there was no significant difference between the effects of the 2, it is evident that propolis still retains some in vitro activity, being able to reduce the contamination of bristles by Streptococcus mutans.

Opportunistic infections can arise from the colonization of microflora which adhere to various surfaces in the oral cavity. ³⁷ The incidence of these opportunistic infections is usually due to the imbalance between the commensal and pathogenic bacteria caused by the poor immune response of the host or other health conditions affecting the oral environment. ³⁸ Individuals with such conditions who do not maintain adequate oral hygiene are the most susceptible to developing such opportunistic infections. It has been suggested that propolis helps in the suppression of bacterial peptides. ³⁹ Moreover, a study conducted by Dalenberg et al. ⁴⁰ reported that propolis can help improve microbial colony health by changing the microbiome in favour of commensal bacterial, which outcompete pathogenic bacteria.

Furthermore, propolis has been shown to play a positive role in maintaining the oral health of clients with inflammatory oral conditions such as recurrent aphthous stomatitis or chemotherapy-induced stomatitis. ^41,42 A study conducted by Samet et al. ⁴² reported a significant reduction in the recurrence of ulcer formation and improved quality of life in clients who received 500 mg of propolis, compared to the placebo group. Moreover, another study by Piredda et al. ⁴¹ reported propolis was well tolerated and effective in reducing the frequency of oral mucositis in clients receiving chemotherapy.

Limitations and gaps in the literature

Despite the evidence supporting the clinical efficacy of propolis in maintaining oral health, certain shortcomings in the literature must be noted. One of the concerns is the difference in study methodology, with previous studies utilizing follow-up periods ranging from 2 weeks to 3 months, making it difficult to compare study outcomes. In addition, some individuals experienced adverse effects from propolis, such as edema of the mucous membranes, swelling of the conjunctiva, hypotension, and/or cardiac arrhythmias. ¹³ These adverse effects have not been sufficiently studied.

In light of these limitations, future randomized clinical trials should use longer follow-up periods with a homogenous model. Studies should also compare propolis products with traditional ingredients such as stannous fluoride and chlorhexidine. Moreover, future studies must investigate the safety issues as well as the dose-benefit relationship, with emphasis on the therapeutic dose necessary to eliminate target microbes with the fewest possible side effects.

CONCLUSION

The literature explored in this scoping review demonstrates that propolis, with its established bactericidal and bacteriostatic properties, may have a positive role to play in initiating, sustaining, and maintaining oral health. Current gaps in the literature highlight the need for studies with larger sample sizes and longer follow-up periods, comparative studies with other traditional products, and further exploration of the side effects of propolis.

CONFLICTS OF INTEREST

This research did not receive any specific grants from funding agencies in the public, commercial or not-for-profit sectors. The authors have declared no conflicts of interest.