Preparing the tooth for veneers: myths and realities

Due to 'somewhat misleading' advertising in the dental sector in recent years, many patients insist in the dental office on "no-face veneers", i.e. the ultimate aesthetic treatment for the smile: veneers with which the tooth does not need to be treated at all to give a radical 180-degree turn to our smile.

Of course, all this advertising information is mostly untrue, as only a few exceptional cases are candidates for these 'non-prep' or non-grinding veneers, which do exist.

Today I am going to explain why:

What is veneer grinding and what is it really for?

Why is good tooth preparation (including minimal grinding) necessary in the vast majority of cases for efficient veneer placement? Because of three factors:

  1.  Margins. Veneers need a defined margin that limits them, that is to say, the prosthetist who manufactures them must be clear about where the margins of each veneer end in order to achieve a perfect fit. If the margins are not marked by correct grinding, the veneer will never be perfect and there will be a risk of leakage and failure in the long term.
  2. Colour. One of the most sought-after functions of veneers is to enhance the colour of the teeth, camouflaging the original colour once they are placed on the tooth. For this to happen effectively, we need a veneer with a certain thickness, because if it is too thin, the colour (usually dark or yellowish, and therefore 'stronger' than white) underneath would be transparent. This point is directly related to the next one.
  3. Volume. Finally, and related to thickness, we must talk about volume. Think that if our teeth already have a correct position with respect to the lip, which would be ideal, placing veneers on top of them without making enough space can result in a 'horse teeth' appearance, that is, teeth that protrude excessively and can even change the volume of the lip. When the volume of our teeth and the veneer are added together, our facial harmony changes.

How should the carving be done?

The preparation required in most cases is minimal, but essential. We are talking about 0.3 to 1 millimetre depending on the case, so that the patient sometimes cannot even appreciate the 'carving'. In addition, the technique of carving on mockup (the aesthetic test to show the design to the patient), allows us to carve in a guided and conservative way, as it prevents us from going beyond what is strictly necessary. By making pencil marks on the mock-up, we manage to eliminate the enamel necessary to create the space where our veneers will be placed.

Therefore, we can conclude that non-prep veneers will only be viable in a minority of cases where the substrate (the tooth) has a suitable colour that does not need to be camouflaged, cases where there are interdental spaces (diastemas) that allow a veneer to be seated at that level and cases where the teeth have a negative torque allowing the addition of vestibular thickness without compromising aesthetics, as we will not need to generate prosthetic space.

In all other cases, it is unfeasible to produce veneers without grinding efficiently and with the results expected by the patient.