Is having two front crowns replaced three times reasonable? How will it affect the tooth structure underneath?

Hi, thanks for write... Of course your own teeth suffer when do you remove your crowns and any moment could broke and your option will be implants. Regards 

Yes, every time the dentist puts a drill on a tooth, it introduces some trauma to the nerve. That said, make sure this time you see the  crowns with a try in paste first. This is the same shade as the actual cement and will allow you to see what the crowns would look like before cementing them in permanently.

Frankly, without an evaluation it’s difficult to give one simple answer. I’ve treated patients whose dental crowns have lasted decades with no pain or problems. But the decision to replace an old crown really depends upon a number of factors, and appearance isn’t the only reason to replace an old crown.Basically, crowns are provided as a restorative option to protect teeth weakened by decay or fracture. Often decay has taken its toll, and a dental filling won’t work because there is not enough natural tooth left to fill. Crowns (also called “caps”) are also useful to restore misshapen, discolored or broken teeth. Procedures like implants, root canaled teeth and teeth that serve as anchors at the ends of a bridge must also have a custom-fitted cap or crown as well. People who grind their teeth or clench their jaws, two very common nighttime activities, will end up with fractures and cracks in their teeth’s enamel and usually require dental crowns more than any other patients I see. In many cases they need to be replaced, sometimes more than once, over the course of a lifetime.