Antimicrobial Efficacy of Essential Oils and Their Combination Against Microorganisms Associated With Postradiation Therapy in Patients With Head and Neck Cancer: An In Vitro Study

Background Head and neck cancer ranks as the sixth most common cancer globally. Reduced saliva production brought on by postradiation therapy upsets the delicate balance between bacterial load and a weakened immune system. Oral hygiene is commonly neglected in patients who have undergone radiotherapy and they often develop dry mouth, mucositis due to radiation therapy, etc., as side effects. Despite being a part of the current standard, chlorhexidine carries numerous disadvantages such as taste alteration, teeth staining, and dry mouth. An extensive review of the literature demonstrates the antibacterial properties of essential oils (EOs) derived from plant materials, which may be able to prevent the development of such opportunistic microorganisms in the oral cavity. Methodology The cinnamon bark EO and Cajeput EO were procured and checked for their solubility. The final ratio at which the oils were found to be soluble was the 1:1 (w/v) ratio. The minimum inhibitory concentration (MIC) of cinnamon bark oil (Cinnamomum verum) and Cajeput oil (Melaleuca leucadendron) against Staphylococcus aureus, Enterococcus faecalis, and Candida albicans was determined by serial dilution method using Resazurin dye, and the minimum bactericidal concentration (MBC) was done by a spread plating method. The polyherbal mouthwash was subjected to cytotoxicity assay against human gingival fibroblasts. All the experiments were performed in triplicates. Results The overall results showed that cinnamon bark EO had the strongest efficacy against S. aureus (0.33 ± 0.14 mg/mL) and E. faecalis (0.41 ± 0.14 mg/mL), but not against C. albicans (2.85 ± 2.11 mg/mL). Cajeput EO showed the least efficacy against all the groups; whereas the combination of EOs proved to be the most efficacious and showed good antimicrobial activity against these most commonly encountered microorganisms in head and neck cancer postradiotherapy. Conclusions Cinnamon and Cajeput EOs in combination proved to be effective in this in vitro study against the most common microorganisms encountered in patients with head and neck cancer postradiotherapy and are comparable to 0.2% chlorhexidine.