This question would be good for /r/askanthropology. The Spirit Cave remains (more than 9,000 BP) is one of the oldest (if not THE oldest) mummified human remains from the Western Hemisphere. He dried naturally in the arid climate of the Northern Great Basin assisted by salts in the cave where his remains rested. He had a horrendous abscess that erupted through the skin above the tooth line of his upper mandible. It may have caused his death. Otherwise, his teeth were in fairly good shape for a 40+ year old man.

Other Great Basin ancient remains generally exhibit good teeth. These include the Wizard's Beach remains that are only slight younger than the Spirit Cave site.