Potential Use of Propolis as Endodontic Irrigant

Objective of this work was to review the use of propolis as an endodontic irrigant. For this, keywords were searched in the PubMed database, from April to October 2022. There are many chemical compounds in propolis from different geographic regions; Flavonoids are one of the most important agents that have anti-inflammatory, anti-viral, anti-allergic, anti-cancer, anti-bacterial and antioxidant effects. According to the mentioned properties, propolis can be used as a canal irrigation solution, as well as intracanal medicine in endodontic treatments. The results described in the literature are practically unanimous in showing the antibacterial and antifungal effects of different propolis extracts at different concentrations. In addition to flavonoids, other components of propolis such as resin, pollen, vitamins and phenols, indicate that propolis can be used not only as an intracanal irrigation solution, but for various purposes, with a promising role in endodontics as well as dentistry.

In endodontics, the objective of biomechanical preparation is to perform cleaning and disinfection of the root canal system (RCS) [1]. The presence of microorganisms in the root canal system is the main cause of endodontic infections and their viability depends on the redox potential, the availability of nutrients and the host's defense system. The identification of the predominant microorganisms in the infections makes it possible to adopt measures aimed at their elimination inside the canal. It is known that instrumentation, alone, does not guarantee the complete removal or inactivation of pathogens in infected canals, irrigation and medication are important, associating mechanical cleaning with the use of antibacterial agents, to improve the effectiveness of the treatment [2]. Irrigating solutions are used in endodontic treatment in order to eliminate bacteria from root canals. Several studies have been carried out in the search for irrigants that combine better properties, including antimicrobial activity, low or no toxicity to periapical tissues, solubility and ability to dissolve organic matter [3,4]. Intracanal medications are used as adjuvants in endodontic treatment, with the aim of moderating pain, reducing remaining bacteria and their metabolites, and accelerating the healing process [5]. In this context, propolis appears as an alternative of interest to complement treatment. Propolis is a resinous complex produced by the bees Apis mellifera L. whose variety of pharmacological properties results from the complexity of its composition [6,7,8]. It is composed of resin and balms (50-60%), pollen (5-10%), and other constituents such as amino acids, minerals, vitamins A and B complex, flavonoids, phenols, and aromatic compounds [9]. In general, propolis has been used as an anesthetic, anti-inflammatory, antibacterial, antiviral, antifungal, antioxidant, anticancer, antidiabetes, immunomodulator, tumoricide, among others. In dentistry, propolis has been used experimentally in the areas of endodontics, cariology, oral surgery, periodontics and oral pathology, among others [1,10]. Propolis extracts are commonly obtained from continuous immersion in various solvents, but there are other methods, including ultrasound and microwaves [11]. Because it is natural, non-toxic, low cost, does not cause microbial resistance and has a variety of therapeutic activities, propolis It is a product with good prospects for use in the dental field, including expansion of its field of applicability. There is evidence that it can be used as an alternative in the control and prevention of oral diseases. The results found in the literature are promising, so research involving propolis has been increasing both in quantity and complexity [12,13]. The present study aimed to review the literature about the potential use of propolis as an endodontic irrigant.

From April to October 2022, a bibliographic search was carried out to locate articles published on the use of propolis as an endodontic irrigant. An electronic search was performed in the PubMed database using the following combinations of keywords: propolis and endodontics (124), propolis and endodontic irrigants (38), propolis and root canal irrigant (47) and propolis as intracanal medicament (32). Articles were included in full, published in English from the year 2000 onwards, describing in vitro or in vivo experiments showing the use of propolis as an intracanal irrigant.

Among the 241 articles obtained, only specific full-length articles in English were used. Duplicate, non-specific articles that did not mention the pharmaceutical form and/or concentration of propolis used were excluded. Finally, 24 articles were included in the present study (Table 1).

The information contained in the selected articles is summarized in Table 2.

RMGIC Resin-modified glass ionomer cements; HDPF Human dental pulp fibroblast.

Table 1: Number and characteristics of selected articles.

Irrigation of the root canal system must be carried out simultaneously with instrumentation for the correct elimination of microorganisms through the antimicrobial action of the applied substances. These substances must have a potent antimicrobial action to combat the microbiota present in endodontic infections [1,3,5]. The antimicrobial action of propolis in relation to the oral microbiota has been demonstrated over the years [13,17,21,28,34]. Until the late 1990s and early 2000s, formocresol and its like were often used as intracanal drugs, but such chemicals used as bactericides have been shown to diffuse throughout the body from the root apex, resulting in cases of undesirable effects, including allergies. Furthermore, as these drugs are potent carcinogens, there is no indication for these chemicals in modern endodontic treatment. Today, biocompatibility and stability are essential properties for intracanal drugs.36 Propolis has been demonstrated as a bioactive, biocompatible and non-toxic product [27,30].

The gold standard irrigant is sodium hypochlorite solution (NaOCl), normally 2.5%, due to its strong antimicrobial action and its dissolution of organic tissue. Its effectiveness is proportional to the concentration used, however, the higher it is, the greater the toxic effect on the periapical tissues and the more serious the complications arising from contact with the periradicular tissues [37]. Noites et al. [38] and Borrin et al. [39] report the complications that may arise during the use of sodium hypochlorite in endodontic treatment. Depending on the concentration of the solution used, bruising, pain, damage to vital tissues such as ulceration, necrosis, inhibition of neutrophil migration, damage to endothelial and fibroblastic cells may occur. Teixeira et al. [40] and Böhle et al. [41] also reported toxic effects of 2.5% NaCl solution for fibroblasts. No reports of propolis-based irrigating solution toxicity were found. Dentistry has been carrying out several studies regarding natural products that have pharmacological activity, reduced toxicity and biocompatibility, so that they are more accessible to the population. The usual indications for these products are associated with the treatment of infections, inflammation, toothache, scarring processes, maintaining good oral health through natural products [42]. Propolis, being a natural product, of plant origin and non-toxic, does not cause tissue damage and has a wide range of therapeutic properties, allowing its use in toothpastes, rinses, varnishes and irrigants, being a good natural product for the therapy of the oral microbiota [1,42]. Propolis is a powerful natural product, resulting from the combination of numerous chemical assets such as fatty acids, alcohols, amino acids, vitamins and mineral salts, with flavonoids being the main components. Propolis is an efficient alternative for the treatment and prevention of several oral problems such as dental caries, mucositis and endodontic treatment, due to its therapeutic diversity, its low toxicity, low cost and proven applicability [43,44]. According to Pinto et al. [12], propolis has low innate toxicity because flavonoids, its main constituents, have very low toxicity. The chemical composition of propolis is very complex and its content varies greatly depending on location, climate, year and season [6]. Despite the popularity of propolis over time, it is not considered a conventional therapeutic agent due to restrictions to regulate chemical composition and biological activity [45]. This standardization is indispensable for acceptance in the health system. Under these circumstances, the characterization of different types of propolis, according to their plant origin and chemical profile, becomes necessary [46]. Prospective studies in intellectual property databases are important to increase market competitiveness and thus generate new products in different areas of research [8].

Propolis and its phenolic and flavonoid constituents have many therapeutic uses in dentistry and oral health. Wide therapeutic uses due to its antibacterial, antiviral, antifungal, anti-inflammatory and anticancer properties have been demonstrated in several in vitro and in vivo studies, as well as in human clinical trials. As intracanal irritants, the different extracts used, in different concentrations, proved to be effective against some of the main intracanal contaminants. However, there is a great need to standardize the content of phenolics and flavonoids in propolis to obtain the best therapeutic benefits in dentistry and oral health.