Propolis in Dentistry

Abstract

Propolis is a product derived from bees and consists of a dark coloured sticky material, which is collected from various plants and mixed with wax. Propolis is found coating a thin layer of this substance on the inner walls of their hives in order to repair or protect the hive from invaders. In dentistry, consideration should be given to the large number of medicinal plants and other natural products, including those from the animal kingdom such as propolis, which can make an important contribution to the area of health and be willing to scientifically study their therapeutic properties, so that after verifying their value, they can be introduced more constantly in dental treatments and in some cases replaced definitively due to their properties, especially their biocompatibility, with the aim of massively increasing their application.

1. Introduction

Propolis is a product derived from bees and consists of a dark coloured sticky material, which is collected from various plants and mixed with wax. Propolis is found coating a thin layer of this substance on the inner walls of their hives in order to repair or protect the hive from invaders.

2. Propolis in dentistry

Dentistry is a branch of health sciences that deals with the study, diagnosis, treatment and prevention of diseases affecting the stomatognathic apparatus composed of the teeth, oral cavity, jaws, muscles, covering tissues (skin and mucous membranes), vessels and nerves of this part of the body. The most common conditions of dental patients are dental caries and periodontal diseases. The pain, inflammation and infection that accompany these pathologies have been studied and treated by stomatologists throughout human history [1].

Propolis is a product derived from bees and consists of a dark coloured sticky material, which is collected from various plants and mixed with wax. Propolis is found coating a thin layer of this substance on the inner walls of their hives in order to repair or protect the hive from invaders; it is an embalming substance, which is responsible for the low incidence of bacteria inside the hive [2].

Propolis is a substance that has the advantage of being a natural and inexpensive product, which makes it available to everyone. Despite this, there is little evidence on the use of propolis in various oral conditions. Due to the scarcity of information on propolis in the different dental disciplines, the aim of this study was to conduct a literature review on the properties and uses of propolis in dentistry [3].

The mechanism of the antimicrobial activity of propolis is complex and can be attributed to synergism between some of its compounds, such as flavonoids, aromatic acids, fatty acids, esters, hydroxy acids, sesquiterpenes and other phenolic compounds present in its composition. In general, the antimicrobial activity of this compound is more active against Gram-positive bacteria than against Gram-negative bacteria; however, its inhibitory character has been demonstrated against Gram-negative oral microorganisms involved in cariogenic and periodontopathogenic processes such as Streptococcus mutans, Prevotella intermedia/Prevotella nigrescens, Porphyromonas gingivalis, and even yeasts such as Candida albicans [3]. Its anti-inflammatory potential has been attributed to its ability to stimulate cellular immunity by promoting phagocytic activity and inhibiting the synthesis of prostanglandins, which mediate this process [4].

The chemical composition of propolis is extremely complex and is not fully known because it depends on the flora of the region where it is collected; this influences the way it is used within the hive as it can serve as an embalming substance or as a coating for the hive. This means that different parts of the hive will have different propolis composition, so it will be very difficult to find two hives producing identical propolis even if they are located in the same geographical area, as they elaborate it according to their needs and available raw material sources [5].

A higher percentage of phenolic compounds have been found in the propolis that coats the combs than in the propolis intended to reduce the entry of foreign agents into the hive. More than 160 compounds have also been identified in propolis, 50% of them phenolics, to which pharmacological action has been attributed [6].

The differences in composition are mainly determined by the flora of the ecological area, the evolutionary cycles of the resin-supplying plants that condition changes in the concentrations of these, micro-organisms present in the geographical environment, climatological factors, as well as the macroscopic and organoleptic characteristics of the propolis and the technique used to obtain it. However, qualitatively speaking, there are numerous substances that are found in propolis in a constant and relatively stable way [7].

Propolis has some components that make it up as can be seen below, where resins and balsams predominate in the highest percentage and wax, these two components give the shape and structure of propolis, see Table 1.

Resins and balsams	50–55%
Wax	30–40%
Aromatic volatile oils	05–10%
Pollen	05%
Organic and mineral substances	05%

Table 1.

Components of propolis.

The wax and some other components present in propolis are considered to have no proven therapeutic activity and normally constitute about 40–50% of the total mass in a propolis sample; the rest corresponds to the biologically active part. The fraction related to the polyphenols of aromatic acids constitutes 2/3 of this amount, to which the pharmacological action is attributed [8].

Among the organic substances contained in propolis, although it makes up only five percent, when in fact it shares some of the main characteristics for the therapeutic properties used, the following is a description of the organic substances contained in propolis:

• Organic acids: benzoic acid and derivatives (hydroxy-4 benzoic acid, methoxy-4 benzoic acid, protocatechic acid and gallic acid).

• Phenolic acids: caffeic acid, phenylic acid, isophenylic acid.

• Aromatic aldehydes: vanillin, isovainillin.

• Unsaturated aromatic acids: cinnamic acid and derivatives p. coumaric acid, ferulic acid (4-hydroxy-3-methoxybenzaldehyde) and isoferulic acid.

• Coumarins: esculethol, scopolethol.

• Flavonoids: ecacetin, yellow chrysin, pectolinarigenin, tectochrysin, galangin 3,5,7-trihydrixiflavone, isalpinin, rhamnocitrin, isorhamnetin, quercetin, quemferido, butelenol, ermanin, pinobanksin and apigenin, 5,7-dioxy-3,4-dimethoxyflavon; 3,5-dioxy-7,4-dimethoxyflavone and 5-oxi-7,4-dimethoxyflavone.

• Flavonones: pinostrobin, sakuranetin.

• Quercetin derivatives: alpha-acetoxybetulenol [9].

Up to now and based on propolis characterisation processes up to twelve different types have been described, but it is type six that has shown the highest inhibition against GTF-B and GTF-C enzyme activity. The possible active biological component that modulates the GTF inhibitory activity is unknown, but it is thought that it may be due to the action of non-polar chloroform, ethanolic extract of propolis, and especially the hexane fractions that compose it; it is also suggested that flavonoids present in propolis may be involved in the enzymatic inhibition [4].

3. Preventive dentistry

Propolis has anti-cariogenic properties, so its use in preventive dentistry is mainly to reduce the incidence of caries and prevent the accumulation of dental plaque in vitro and in vivo. The antimicrobial effectiveness of the extracts depends on the solvent used, although the solvent used is not definitive as it is the actual substances or elements contained in the propolis, the origin of the propolis and the microbial species evaluated, with ethanolic extracts of propolis being the most effective, contents such as apigenin (flavonoid) and t-farnesol (terpenoid) have been shown to have the strongest antimicrobial properties against Streptococcus mutans micro-organisms, based mainly on their ability to inhibit glycosyltransferases and their bactericidal effect [10].

The fatty acids in propolis have been shown to provide a cariostatic effect by decreasing acid production. It has been proven that one of the most widely used preventive products is the use of rinses, with propolis being used as the main substance in mouthwashes with an aqueous solvent or carrier, compared to a chlorhexidine (CHX) rinse or others containing an alcohol solvent or carrier, which are among the most commonly used types of rinses, those with a chlorhexidine-based substance being one of the most recommended by periodontists, due to its capacity to eliminate a large number of microorganisms, but it has some side effects such as altering the sense of taste, its prolonged use can damage the oral microbiota because the elimination of microorganisms is not specific but eliminates indiscriminately, something that would not be a problem with propolis which is a biocompatible substance and that its prolonged use has no side effects [11].

In the case of mouthwashes in which the vehicle is alcohol, they are contraindicated because they cause high oral sensitivity, as well as when there are lesions in the mucosa due to their caustic and astringent effect, although propolis can be used in this vehicle, due to these characteristics, it is recommended to use it in an aqueous vehicle. Propolis has proven to be more effective against the following bacteria: Staphylococcus aureus, Streptococcus mutans, Lactobacillus acidophilus and Enterococcus faecalis, which are the most common bacteria for oral diseases such as caries and gingivitis [12].

4. Endodontics

In the field of endodontics, propolis has been shown to have biocompatibility as well as antimicrobial properties compared to one of the most commonly used substances in endodontic treatments, calcium hydroxide as an intra-canal medication. In addition, studies have been conducted comparing and evaluating the antimicrobial activity of calcium hydroxide. Another substance or medication is the use of triantibiotic mixture (TAM), as opposed to ethanol extract of propolis as intracanal medication in root canals infected with Enterococcus faecalis (microorganism present in most endodontic complications), propolis was more effective than the triantibiotic mixture against E. faecalis and, at seven days, both were equally effective, reducing the healing time [13].

Propolis and calcium hydroxide show synergistic effects with other antibiotics such as ciprofloxacin against E. faecalis. Another use of propolis in endodontics is as a solution to irrigate and disinfect the canals, as is the case with sodium hypochlorite as a solution, being just as effective as the latter; with the advantage that propolis acts against periapical inflammation and protects periodontal cells due to its antibacterial properties, unlike sodium hypochlorite, which only cleans and eliminates organic tissue but does not have antibacterial properties [14].

5. Periodontics

In the treatment of periodontal diseases, propolis has demonstrated antibacterial, anti-inflammatory, anaesthetic and healing activity in certain lesions such as chronic ulcers or in various types of periodontitis. The action of propolis is directly against supragingival plaque due to its stimulating action on tissue recovery, which is due to the biocompatibility of propolis, acting against Gram-positive microorganisms and its anti-inflammatory property, which allows for a better local immune response. As an anti-inflammatory, propolis inhibits the synthesis of prostaglandins and helps the immune system by promoting phagocytosis and stimulating cellular immunity. Another property of propolis is that it is an adjuvant in the healing process, which in the case of chronic gingivitis and recurrent and non-specific mouth ulcers, is very useful for promoting the process in the gum and accelerating the healing process [15].

Propolis for the treatment of periodontal diseases has been used in many different forms, such as patches that continuously release propolis in the gum area affected by periodontitis, favouring the recovery of the tissue due to the prolonged and constant release of propolis in the gingival area with the pathology [16]. Another of the most commonly used presentations is as an irrigant prior to periodontal treatment, with good results being observed. Propolis has also been used for the treatment of herpes simplex virus in a solution form, which slows down the progression of the virus and is reflected in the skin changes that occur at the onset of the disease [17].

Propolis tincture is another presentation that has been used, 0.12% being the most common, after the initial phase of periodontal treatment and also in periodontal surgery in cases of periodontal disease, gingival enlargement and high frenulum insertion. After the initial phase of periodontal treatment, cotton swabs soaked in propolis tincture were administered and the procedure was repeated 24 and 48 h after the intervention [18]. Propolis, which has a healing property, makes the gingival tissue have a faster and more successful postoperative period, reducing the time of evolution, improving haemostasis and adequate tissue healing. Propolis as a paste and mouthwash were shown to have the ability to inhibit the growth of supragingival biofilm, representing an approximate reduction of 80–88% [19].

Chronic periodontitis (CP) is one of the most common types of periodontal disease. It presents clinically as an infectious inflammation that affects the supporting tissues of the tooth, causing loss of attachment and alveolar bone. It is asymptomatic, which means that it progresses silently and for this reason it cannot be diagnosed early and it cannot be treated in the early stages of the disease, which is why the clinical manifestations are more severe [20]. It is initiated by bacteria present in the biofilm; however, specific immune response and inflammation play an important role in the development of the disease [21]. Assessment of the periodontal status should be made by observing the degrees of inflammation of the periodontal, supporting and surrounding tissues of the tooth. This is reflected by a reddish discolouration, bleeding, sometimes with a crepitant sensation and tissue that does not appear to be firmly attached to the bone [22].

6. Surgery

Regarding the participation of propolis in oral surgery, it has been used in post-operative treatment, due to the healing property that is used in the majority of dental surgical treatments, improving the process of alveolar closure, using the presentation of propolis in the form of 5% propolis tincture. This has led to a remission of symptoms and a shortening of the evolution period [23].

Propolis has been administered topically in combination with drugs such as dexamethasone directly to oral surgical wounds, with concentrations of 30% ethanolic extract of propolis (EEP) and 0.1% dexamethasone being the most recommended for topical treatment with orabase gel. From this, they found that ethanolic extract of propolis generated greater anti-inflammatory effect and reduced wound healing time compared to dexamethasone gel alone [24].

7. Prosthodontics

In prosthodontics, where patients using removable partial prostheses or total prostheses have soft tissue damage due to inflammation or poor hygiene that causes some opportunistic microorganisms to appear, including fungi such as Candida albicans [25]. Some propolis-based products such as ointments or rinses are used, as they have great antifungal properties, especially on Candida albicans, which is why, once again, propolis can be of great use in prosthodontics [26]. Oral candidiasis is an infection of the mucosa of the oral cavity caused by yeasts of the Candida genus in populations that use removable dentures [27].

One of the most common diseases for older adults is prosthetic stomatitis, which is a chronic form of infection by the fungus C. albicans that affects the mucosa of patients with removable total and partial prostheses. Albicans fungus that affects the mucosa of those patients who wear removable total and partial prosthesis, the reasons can be discomfort caused by the prosthesis, it is poorly adjusted, it means that in some part of the prosthesis there is an excess or surplus of acrylic and that hurts the patient’s mucosa, another of the reasons may be null or poor hygiene, as well as the patient carries the prosthesis all day even at bedtime, when it must remain out of the mouth at night to clean it [28]. The treatment normally used is with antifungal agents such as nystatin suspension or miconazole gel, with favourable results for the pathology in question. However, despite this, there have been failures in antifungal therapy, which is why biocompatible options are needed, with propolis being one of the best natural products for treating prosthetic stomatitis [29].

8. Pulpal therapies

One of the concerns in paediatric dentistry is the preservation of the pulp of primary teeth, whose main objective is to maintain the space of the dental arches, but also to allow the permanent teeth to erupt when the primary tooth is exfoliated. One of the pulp therapies in which propolis has been successful is pulpotomy, which is a pulp therapy that is performed when the dental pulp is exposed and therefore the inflamed coronal pulp tissue has to be removed leaving only the root pulp [30].

For a long time there has been a search for the ideal medicine, treatment or substance to carry out pulp therapy for pulpotomy, which must be antimicrobial, biocompatible, have the capacity to heal the inflamed pulp tissue, and not affect the resorption process of the teeth. The most commonly used substance or medicine has been formocresol, which is a substance that has the capacity to mummify the pulp tissue, preventing the pulp tissue from becoming infected [31]. The problem with the use of this substance is that it has carcinogenic and mutagenic properties, which has led to its use being banned in some countries, and in others it continues to be used but with certain restrictions and vigilance, hence the importance of using a different substance or medicine [32].

One of the advantages demonstrated by the use of propolis as an alternative in the treatment of pulpotomy is that it is easy to handle, biocompatible and does not mummify the tissues, allowing a more natural recovery [33].

9. Conclusions

In dentistry, consideration should be given to the large number of medicinal plants and other natural products, including those from the animal kingdom such as propolis, which can make an important contribution to the area of health and be willing to scientifically study their therapeutic properties, so that after verifying their value, they can be introduced more constantly in dental treatments and in some cases replaced definitively due to their properties, especially their biocompatibility, with the aim of massively increasing their application.

Propolis is a medicine based on knowledge of herbal and holistic medicine with therapeutic properties, because it has components with analgesic and antibiotic characteristics, and due to these properties, its usefulness in dental materials is the subject of research. It is a natural resin with diverse biological properties developed by bees of the Apis millifera species that is responsible for protecting the hive and also has antifungal activity, so it has been used for the therapeutic management of fungal infections.

The results of this research must be corroborated by subsequent studies because the results presented cannot be considered conclusive. The more clinical evidence there is of these natural products, the more confidence there will be in their application in patients.

The great difficulty in the use of propolis in general medicine and dentistry lies in the difference of the components that this antimicrobial action yields depending on geographical location, harvesting season, and method of extraction.