In Nepal in 1982, they gnawed on branches of the poinsettia bush to brush their teeth.
I always thought that was poisonous...
I was remembering decades ago when at a health food store I bought some Myrrh powder to use for tooth brushing. I could not remember how to spell myrrh, so looked up Frankincense and Myrrh (Google kindly spelled it for me), and discovered a treasure trove of herbal tooth products, including some instructions for making your own. Dozens of articles, tidbits of info, and available products for sale.
https://www.google.com/search?q=frankincense+and+myrrh+for+tooth+cleaning&sca_esv=6480816f92634337&sca_upv=1&rlz=1CAJCUZ_enUS847&sxsrf=ACQVn0_c8ekCnVHkXSGxMDmUwFzpmzjcIQ%3A17127616 54838&ei=NqsWZurXMteg5NoPpPengAk&ved=0ahUKEwjqypWw9reFAxVXEFkFHaT7CZAQ4dUDCBA&oq=frankincense+and+myrrh+for+tooth+cleaning&gs_lp=Egxnd3Mtd2l6LXNlcnAiKWZyYW5raW5jZW5zZSBhbmQgbXlycmggZm9yIHRvb3RoIGNsZWFuaW5nMgcQIRgKGKABMgcQIRgKGKABMgcQIRgKGKABMgcQIRgKGKABMgcQIRgKGKABMgUQIRifBUi3ogFQrCpY5HNwAXgBkAEAmAG9AaAB0xGqAQQyLjE3uAEMyAEA-AEBmAIUoAL3FMICChAAGEcY1gQYsAPCAg0QABiABBiKBRhDGLADwgIKEAAYgAQYFBiHAsICChAAGIAEGIoFGEPCAgUQABiABMICBhAAGBYYHsICCBAAGBYYHhgPwgILEAAYgAQYigUYhgPCAggQABiABBiiBMICBRAhGKABmAMAiAYBkAYKkgcGMS4xOC4xoAeJbg&sclient=gws-wiz-serp#ip=1