_Applied_  
_sciences_  
_Article_  
**Essential Oils as Alternatives for Root-Canal Treatment and Infection Control against _Enterococcus faecalis_--A**  
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Footnote 1: [[https://www.mdpi.com/journal/applsci](https://www.mdpi.com/journal/applsci)]([https://www.mdpi.com/journal/applsci](https://www.mdpi.com/journal/applsci))  
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Footnote  
periodontitis is due to some microorganisms [1; 2; 3]. The microorganisms reach the pulp by dentinal tubules especially when there is an open cavity after a coronal fracture and the pulp is in contact with the septic oral environment. Another pathway for the microorganism is the periodontal membrane when they use the lateral channel or the apical foramen [4]. In the oral cavity, nearly 700 species of bacteria can be found, most part of Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria [5]. There are two types of intraradicular infections: primary and secondary, each with specific microbiology. The primary infection of the root canal system results from colonization with a heterogenous group of microbes that have entered the pulp tissue, when exposed during caries or traumas; this group is dominated by Gram-negative oral anaerobic bacteria (_Prerotella_ spp., _Porplyomonas_ spp., _Fusobacterium_ spp., _Veillonella_ spp. ), aside other bacterial species which are also part of the commensal oral microflora: Gram-positive anaerobic bacteria (_Propionibacterium_ spp., _Bifidobacterium_ spp., anaerobic streptococci), trepenemas or _Campylobacter_ spp. [5; 6]. The secondary intraradicular infection appears inside the root canal system, after the treatment of the affected tooth has been initiated. Secondary intraradicular infections harbor a limited number of bacterial species, with predominance of Gram-positive bacteria, namely _Enterococcus faecalis_, oral streptococci, lactobacilli or _Candida albicans_, while Gram-negative bacteria are involved to a lesser extent [6]. The most common microorganism found in asymptomatic, persistent endodontic infections is _E. faecalis_. Its incidence in this type of infection varies from 24% to 77% [6; 7]. _E. faecalis_ possesses enzymes and constitutive structures that are able to suppress the action of lymphocytes and promote inflammation, which contributes to progression of endodontic infections [4]. Also, this microorganism has the ability to attach to dentin due to an inner component which is the collagen-binding protein [8]. The essential oils (EO) extracted from plants have been used for centuries as spices and in medicine for their antibacterial and antifungal properties. These properties depend on their chemical composition, the provenance of the plant, the climatic and growth condition and as well as on distillation process [9]. The genus _Origanum_ L., (Lamiaceae) comprises 38 species most of which grow in the Mediterranean area, North Africa, Europe and Asia. The major constituents are terpen, and the principal terpen are carvacrol, thymol, \(\gamma\)-terpinene and \(p\)-cymene. There is also present linalool, \(\beta\)-myrce, _trans_-sabinene hydrate and \(\beta\)-caryophyllene.