I am going to quote here from a book by Matthew Crawford called ‘The Case for Working with Your Hands’.
“Some arts reliably attain their object – for example the art of building. If the building falls down , one can expect to say in retrospect that the builder didn’t know what he was doing. But there is another class of arts that Aristotle called ‘stochastic’. An example would be medicine (or in our case dentistry). Mastery of a stochastic art is compatible with failure to achieve its ends (health). As Aristotle writes, “It does not belong to medicine to produce health, but only to promote it as much as possible…”
Fixing things , whether cars or human bodies, is very different from building things from scratch. The mechanic and the doctor deal with failure every day, whereas the builder does not. this is because the things they fix are not of their own making,and are therefore never known in a comprehensive or absolute way.
The vast majority of us are born with a perfect set of teeth crafted by mother nature to last a lifetime. Unfortunatly in many cases the use and abuse of modern life takes its tole on these marvels leading to decay, gum disease, extractions and fillings. What I am trying to get at is that the dentist did not make your teeth for you but has the challenging job of trying to fix the wear and tear they are exposed to. Fixing broken and worn out things can therefore be unpredictable, expensive and time consuming.
So like classic cars its easier to buy and maintain a good example than a rusted barn-find unless you are prepared to spend a lot of time and effort in its restoration, and sometimes its just impossible even when both cars were designed by a Porsche to turn one into the other.