Oral hygiene in Namibia: A case of chewing sticks

Ethnopharmacological relevance: Chewing sticks have served as the primary form of dental care for rural communities in resource-poor settings for millennia. They are one of the most important under-researched, nontimber forest products in Namibia. This review provides an overview of plants that are used as chewing sticks in Namibia and highlights pharmacological as well as phytochemical studies conducted on them. Aim of the study: This review aims to present a summary of studies that have been done on the ethnomedicinal uses, phytochemistry, biological activity as well as evidence on the scientific validation and geographical distribution of chewing sticks in Namibia. It also highlights research gaps and provides an impetus for the scientific investigations of these plant species. Material and methods: Literature searches using keywords including oral hygiene, chewing sticks, ethnomedicinal uses, phytochemistry, antimicrobial, antioxidants, anti-inflammatory activities and toxicity studies, chewing sticks, and distribution in Namibia on various electronic search engines was conducted. Results: Of the 41 plant species identified, Cordia sinensis Lam., Faidherbia albida (Delile) A.Chev. and Harpagophytum zeyheri Decne. are used for both gargling and as mouthwash. The plant families Fabacae, Ebenaceae, and Burseraceae account for 22.0%, 12.2%, and 7.30% of plant species recorded as chewing sticks in Namibia respectively. This study revealed a significant relationship between plant family and scientific validation. Species belonging to Burseraceae, Apocynaceae, Montiniaceae, and Cucurbitaceae families have only been partially validated. The Kunene region, home to the Ovahimba ethnic group, had the highest proportion (87.8%) of chewing sticks species compared to other regions. Conclusion: This review revealed that most of the plants used as chewing sticks in Namibia require an in-depth pharmacological and phytochemical investigation as deduced from the paucity of literature on the therapeutic methods, mechanisms of action, efficacy, toxicity, and clinical relevance of these species.