Quite often people ask for “No Prep Veneers”. When the case allows, the results can be fantastic.
However, most cases do not allow this. Most people have teeth that overlap to a certain degree, or are flared out and would need to be brought in. If tooth structure is located in an area where none should be, then it would need to be removed to create the ideal appearance. This eliminates the case from “No Prep” consideration.
This is not a bad thing. “Prep” veneers do not weaken teeth, and usually are stronger than if the teeth were not restored at all. The result is both beautiful AND strong.