Abstract
Bad breath or halitosis is an oral condition caused by volatile sulfur compounds (VSC) produced by bacteria found in the dental and tongue biofilms. Fusobacterium nucleatum is a Gram-negative anaerobic bacterium that has been strongly associated with halitosis. In this study, essential oils (EO) from three plants, Labrador tea (Rhododendron groenlandicum [Oeder] Kron & Judd), peppermint (Mentha x piperita L.), and winter savory (Satureja montana L.), were investigated for their effects on growth, biofilm formation and killing, and VSC production by F. nucleatum. Moreover, their biocompatibility with oral keratinocytes was investigated. Using a broth microdilution assay, winter savory EO and to a lesser extent Labrador tea and peppermint EO showed antibacterial activity against F. nucleatum. A treatment of pre-formed biofilms of F. nucleatum with EO also significantly decreased bacterial viability as determined by a luminescence assay monitoring adenosine triphosphate production. The EO were found to permeabilize the bacterial cell membrane, suggesting that it represents the target of the tested EO. The three EO under investigation were able to dose-dependently reduce VSC production by F. nucleatum. Lastly, no significant loss of cell viability was observed when oral keratinocytes were treated with the EO at concentrations effective against F. nucleatum. This study supports the potential of Labrador tea, peppermint, and winter savory EO as promising agents to control halitosis and promote oral health.
Highlights
Bad breath or oral malodor emanating from the oral cavity is commonly known as halitosis and it is considered a multifactorial disease
Among the major substances related to oral halitosis, volatile sulfur compounds (VSC), including hydrogen sulfide (H2 S) and methyl mercaptan (CH3 SH), have been reported to be end-products of protein metabolism in oral bacteria [4]
Many bacterial species within the oral microbiota are involved in the complex process of halitosis
Summary
Bad breath or oral malodor emanating from the oral cavity is commonly known as halitosis and it is considered a multifactorial disease. The main oral sources of halitosis are usually related to tongue coating and periodontal diseases [1,2]. Extra-oral sources of halitosis such as disturbances of the upper and lower respiratory tracts, systematic diseases, as well as metabolic changes and renal insufficiencies, have been reported [3]. Among the major substances related to oral halitosis, volatile sulfur compounds (VSC), including hydrogen sulfide (H2 S) and methyl mercaptan (CH3 SH), have been reported to be end-products of protein metabolism in oral bacteria [4]. In addition to playing a role in periodontal disease, F. nucleatum has been associated with clinical infections, including appendicitis, Antibiotics 2020, 9, 794; doi:10.3390/antibiotics9110794 www.mdpi.com/journal/antibiotics
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