From what I know "acidity of undiluted apple cider vinegar may destroy tooth enamel when sipped orally" and this is exactly what happened to me. Maybe for someone it works, but not for everybody. People like me that have thin teeth do not have a very big tooth enamel cover and it affects it very fast.
Dental Enamel Issues
Hi. I absolutely LOVE the benefits of apple cider vinegar. However, I must warn people about drinking it straight. You must use a straw. I have been drinking it for about a year and my teeth are starting to wear down. I even have a hole in my front bottom tooth. Really weird. The dentist told me it was from Apple Cider Vinegar. So please use a straw if you drink it!