# Dental Hydrogels with Essential Oils with Potential Activity in Periodontitis
## 1 Introduction
The attention of many researchers has focused on the antimicrobial properties of traditional medical substances, such as essential oils [10]. Oregano-Origanum vulgare (family Lamiaceae) is a plant found in India, southern Iran, and the Mediterranean region, which has traditionally been used for antiseptic purposes. Scientific reports have shown that oregano oil possesses antimicrobial, antiseptic, and antispasmodic properties due to its bioactive compounds such as the phenolic isomers carvacrol and thymol; the monoterepenes p-cymene and \(\gamma\) terpinene, being effective antimicrobial agents against the pathogen _Enterococcus faecalis_[11]. Cinnamon, which has the scientific name _Cinnamonum zeylanicum_, and the use of the plant, due to its vast medicinal uses, has found a prominent position in traditional medicine, especially in Ayurveda, which is the traditional Indian medicinal system. Cinnamon is used in many cultures to treat a variety of health disorders, including diarrhea, arthritis, spasticity, yeast infections, mouth ulcers, colds, flu, and digestive problems [12]. Clove essential oil is extracted from the clove plant, _Syzygium aromaticum_. This is a good natural analgesic and antiseptic, mainly used in dentistry for its main ingredient, eugenol. The health benefits of the oil can be attributed to its antimicrobial, antifungal, antiseptic, antiviral, aphrodisiac, and stimulant properties. The germicidal properties of the oil make it very effective in relieving toothaches and gum and mouth ulcers. The most important and common use of clove oil is in dental care [13]. _Rosmarinus officinalis_, commonly known as rosemary, is a woody perennial plant native to the Mediterranean region. Rosemary essential oil is also used in oral inflammatory conditions. It is a rich source of antioxidants and anti-inflammatory compounds, which help strengthen the immune system and improve blood circulation. Laboratory studies have shown that rosemary is rich in antioxidants, which play an important role in neutralizing harmful compounds called free radicals [14]. Lemon essential oil has always been used to treat a variety of conditions, such as inflammation, cardiovascular disease, cancer, hepatobilary dysfunction, etc. It is known to possess multiple biological activities, such as antibacterial and fungicidal properties against foodborne pathogens and spoilage bacteria, as well as considerable antioxidant properties. Studies have shown that lemon essential oil exhibited selective antibacterial activity with a greater effect on pathogenic bacteria (_E. coli_) than on beneficial bacteria (_Lactobacillus_). All of this points to the possibility of using this substance as a natural extract to prevent inflammation brought on by oxidative stress [15]. The Eucalyptus globules tree, which is endemic to China, is the source of eucalyptus. The primary active ingredient in eucalyptus essential oil is eucalypt (1,8-cineole), which has been shown to have potent broad-spectrum antibacterial activity against a variety of microorganisms in clinical settings [16]. It also has potent antiseptic, astringent, diaphoretic, deodorant, inhalant, expectorant, and insect repellent. Thus, natural phytochemicals incorporated into hydrogels could provide an effective alternative to the over-administration of antibiotics, antiseptic, and analgesics, and this represents a promising approach in therapeutic strategies seeking to combat dental problems and other oral infections in both humans and animals. Efforts to develop hydrogels enriched with natural extracts for biomedical applications represent one of the most studied fields at the interface of engineering and medicine at the present time [1]. In the beginning, our research team synthesized five gels used as photosensizers containing oregano, methylene blue, Thieves(r), Frankincense(r), arnica oil, and curcumin extract.