Antibacterial Activity of Essential Oils and Their Isolated Constituents against Cariogenic Bacteria: A Systematic Review

Irlan Almeida Freires, Carina Denny, Bruna Benso, Severino Matias de Alencar, Pedro Luiz Rosalen, Irlan Almeida Freires, Carina Denny, Bruna Benso, Severino Matias de Alencar, Pedro Luiz Rosalen

Abstract

Dental caries remains the most prevalent and costly oral infectious disease worldwide. Several methods have been employed to prevent this biofilm-dependent disease, including the use of essential oils (EOs). In this systematic review, we discuss the antibacterial activity of EOs and their isolated constituents in view of a potential applicability in novel dental formulations. Seven databases were systematically searched for clinical trials, in situ, in vivo and in vitro studies addressing the topic published up to date. Most of the knowledge in the literature is based on in vitro studies assessing the effects of EOs on caries-related streptococci (mainly Streptococcus mutans) and lactobacilli, and on a limited number of clinical trials. The most promising species with antibacterial potential against cariogenic bacteria are: Achillea ligustica, Baccharis dracunculifolia, Croton cajucara, Cryptomeria japonica, Coriandrum sativum, Eugenia caryophyllata, Lippia sidoides, Ocimum americanum, and Rosmarinus officinalis. In some cases, the major phytochemical compounds determine the biological properties of EOs. Menthol and eugenol were considered outstanding compounds demonstrating an antibacterial potential. Only L. sidoides mouthwash (1%) has shown clinical antimicrobial effects against oral pathogens thus far. This review suggests avenues for further non-clinical and clinical studies with the most promising EOs and their isolated constituents bioprospected worldwide.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Flow diagram of the search strategy comprising the identification of potentially relevant material, and preliminary screening and final selection of the studies included in this review (based on PRISMA guidelines). * The leading reasons for exclusion of articles were: clinical trials—“score lower than 3 in Jadad’s scale” (see Methods); in vitro studies—lack of critical information on chemical profiling, and methodological shortcomings.
Figure 2
Figure 2
Risk-of-bias summary of the clinical trials included in this systematic review. Red (−) stands for high risk of bias, green (+) stands for low risk of bias and yellow (?) stands for unclear risk of bias. Overall, the studies are compliant with the CONSORT guidelines for clinical trials of herbal interventions, showing low risk of bias.
Figure 3
Figure 3
The chemical structure of (‒)-menthol [(1R,2S,5R)-2-isopropyl-5-methylcyclohexanol].
Figure 4
Figure 4
The chemical structure of eugenol [4-Allyl-2-methoxyphenol].

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