Oral Ecology Research Group, Faculty of Dentistry, Université Laval, Quebec City, Quebec, Canada.
Oral Ecology Research Group, Faculty of Dentistry, Université Laval, Quebec City, Quebec, Canada.
Arch Oral Biol. 2017 Nov;83:97-104. doi: 10.1016/j.archoralbio.2017.07.005. Epub 2017 Jul 12.
Halitosis, also known as bad breath or oral malodour, is a condition affecting a large proportion of the population. Solobacterium moorei is a Gram-positive anaerobic bacterium that has been specifically associated with halitosis. In this study, we investigated the effects of essential oils, more particularly cinnamon bark oil, on growth, biofilm formation, eradication and killing, as well as hydrogen sulfide (HS) production by S. moorei.
A broth microdilution assay was used to determine the antibacterial activity of essential oils. Biofilm formation was assessed by a crystal violet staining assay and scanning electron microscopy. The biofilm of S. moorei was characterized by enzymatic treatments. Biofilm killing was determined by a luminescence assay monitoring ATP production. HS production was quantified with a colorimetric assay. The biocompatibility of cinnamon oil was investigated using a gingival keratinocyte cell line.
Among the ten essential oils tested, cinnamon oil was found to be the most powerful against S. moorei with MIC and MBC values of 0.039% and 0.156%, respectively. The biofilm formed by S. moorei was then characterized. The fact that DNase I and to a lesser extent proteinase K significantly reduced biofilm formation by S. moorei and induced its eradication suggests that the extracellular matrix of S. moorei biofilm may be mainly containing a DNA backbone associated with proteins. At concentrations below the MIC, cinnamon oil reduced S. moorei biofilm formation that resulted from an attenuation of bacterial growth. It was also found that treatment of a pre-formed biofilm of S. moorei with cinnamon oil significantly decreased its viability although it did not cause its eradication. Cinnamon oil had an inhibitory effect on the production of HS by S. moorei. Lastly, it was found that at concentrations effective against S. moorei, no significant loss of viability in gingival keratinocytes occurred after a 1-h exposure.
Our study brought evidence that cinnamon oil may be a promising substance to incorporate into oral hygiene products for controlling bad breath by inhibiting growth, killing biofilm, and reducing HS production by S. moorei. Moreover, at the effective concentrations, cinnamon oil was found to have no toxic effects on oral keratinocytes.
口臭，又称口气不佳或口腔异味，是一种影响很大一部分人群的病症。索氏梭杆菌是一种革兰氏阳性厌氧菌，与口臭密切相关。本研究旨在探讨精油，特别是肉桂皮油对索氏梭杆菌生长、生物膜形成、清除和杀灭以及硫化氢（HS）产生的影响。
采用肉汤微量稀释法测定精油的抗菌活性。采用结晶紫染色法和扫描电子显微镜评估生物膜形成。通过酶处理来表征索氏梭杆菌的生物膜。通过监测 ATP 产生的发光测定法来确定生物膜杀灭情况。采用比色法定量测定 HS 产生量。采用牙龈角质细胞系研究肉桂油的生物相容性。
在所测试的 10 种精油中，肉桂油对索氏梭杆菌的抑制作用最强，MIC 和 MBC 值分别为 0.039%和 0.156%。然后对索氏梭杆菌形成的生物膜进行了特征描述。DNase I 和蛋白水解酶在一定程度上显著减少了索氏梭杆菌生物膜的形成并诱导其清除，这表明索氏梭杆菌生物膜的细胞外基质可能主要含有与蛋白质相关的 DNA 骨架。在低于 MIC 的浓度下，肉桂油减少了由细菌生长减弱引起的索氏梭杆菌生物膜形成。还发现，肉桂油处理索氏梭杆菌预先形成的生物膜会显著降低其活力，但不会导致其清除。肉桂油对索氏梭杆菌 HS 的产生有抑制作用。最后，在对索氏梭杆菌有效的浓度下，牙龈角质细胞在 1 小时暴露后没有明显的活力丧失。
本研究表明，肉桂油可能是一种有前途的物质，可以通过抑制生长、杀灭生物膜和减少索氏梭杆菌 HS 的产生来纳入口腔卫生产品中，以控制口臭。此外，在有效浓度下，肉桂油对口腔角质细胞没有毒性作用。
