Anterior preparation reduction guides are extremely valuable tools which can be used to confirm that there will be adequate space for the restorative material after the teeth are prepped.
The guides are based on the desired definitive form of the final restorations based on a diagnostic wax-up. There are several types of guides that can be used to assist you in designing your preparations:
Palatal: Confirms the length and palatal (lingual) reduction
Labial: Confirms the labial reduction
Window: Confirms both the labial and palatal reduction
Vertical: Confirms 2 phase labial and palatal reduction
The reduction guides should be made from a firm silicone material to minimize distortion when they are inserted into the mouth. The key to using an anterior preparation reduction guide is that there is an accurate diagnostic impression of the teeth and soft tissue as both the teeth and/or tissue will be used to support and stabilize the silicone index.