Here's an article that summarizes the history of nail cuttings. In short, nails would be pared with a sharp knife, like the skin of an apple, rather than cut or trimmed.
As for dental hygiene, here's a review that describes dental hygiene as outlined in the Indian medical system of ayurveda (~200 BCE).
- Tongue scraping: scraping the tongue with a gold, silver, or copper tool is recommended. The choice of metal is determined by your ayurvedic constitution.
- Chewing sticks: it's recommended to use chewing sticks in the morning, and after every meal. Ayurveda insists on herbal brushes, approximately 9 inches long, and the thickness of the little finger. These herb sticks should be either ‘Kashaya’ (astringent), ‘Katu (acrid), or ‘Tikta’ (bitter) in taste. The method of use is to crush one end, chew it, and eat it slowly. Based on the individual's 'dosha' or constitution, different plants are recommended. These include neem (Azadirachta indica), liquorice (Glycyrrhiza glabra) and black catechu or the cutch tree (Acacia catechu).
- Oil pulling: swishing and gargling for a few minutes with warm sesame oil, which is then spit out. The oil helps disrupt hydrophobically attached bacterial biofilms.
- Chewing spices: it's recommended to chew aromatic spices like cardamom and cloves after meals to freshen the breath.