No you cannot use extracted teeth as an implant. A dental implant is usually sterile titanium alloy.
Veneers and crowns are made from similar materials. The main difference is the amount of tooth reduction and therefore the thickness ofyour restorations. By doing one tooth as a crown and the rest of the restorations as veneers you most likely have different levels of opaqueness with the two different types of restorations.
Your existing crowns will not come off with Crest White Strips. As mentioned earlier, it takes quite a bit of force to remove a crown. One thing you do need to be aware of, however, is that existing crowns and other restorations you may have in your mouth will NOT whiten with any whitening products. So, if the crown you are talking about is in a visible place in your mouth, it will look darker, the whiter your other teeth become by whitening.
