There is evidence of dental work being done in the Indus valley around 7000BC, though there have been older archaeological finds of teeth that have had work done upon them, one dating back to 12000 BC. Ancient civilizations believed that decay was caused by a ‘tooth worm’, a legend found in Sumer in 5000 BC, but also believed in Egypt, India, Japan, China and ancient Greece, at least in the writings of Homer. This belief in a worm causing decay was possibly the best understanding possible in the days before the discovery of bacteria and germs; the belief persisted until at least the 14th century. Cures for tooth worm ranged from magic charms to hot needles, all without modern anaesthetics .
There have been tooth extractions since Ancient Greece, being written about in Hippocrates (the father of medicine) and Aristotle, though the practice probably extends back to many centuries BC. Though primitive dental fillings have occasionally been found, one dating back to 4500 years ago, these have been quite rare, even amongst the wealth aristocracy. The technology of the time probably did not make tooth fillings very effective. Extractions were the only real option for seriously damaged teeth. Lest we forget that without treatment a particularity bad tooth can form an abscess, which is life threatening. The loss of several teeth was probably seen as inevitable through much of history.
Amalgam dental filling have been documented in China in the 659 AD, relatively late compared to extractions and other dental procedures. Earlier use of beeswax for cavity fillings have been discovered, but the softness of the material could not have been practical; they do not seen to have been popular, or else they simply did not survive. Prosthetic teeth have been found as far back as the ancient Egyptians, and been discovered on pacific islands where pieces of seashell were forced into the jaws. It is possible that these artificial teeth were part of the burial preparation and not fitted while a person was alive.
Modern dentists benefit from knowledge that provides an early diagnoses and prevents many once serious issues from becoming life threatening. Patients also benefit from many preventative treatments. Understanding the impact of sugars and the importance of cleaning are factors that were not understood throughout most of history, even as they prevent almost all dental problems.