1. Anesthetize area.
2. Take preliminary impression.
3. Remove all defective amalgams and caries.
4. Select gingival, body and incisal shades of teeth to be restored (NOTE: Best accomplished after old dark alloy is gone).
5. Prepare teeth as follows:
   • reduce facial, lingual and proximal surfaces a minimum of 1.2 mm (1.5 mm is the minimum necessary for esthetic areas, i.e., the buccal aspect of the preparation).
   • allow for no more than 2.5 mm of occlusal reduction.
   • all line angles should be smooth and rounded.
   • sharp transitions, inner angles, undercuts or feather edges should be avoided.
   • insure there is an adequate path of insertion.
   • all gingival margins should be butt shoulder with rounded axio-cervical line angle. A chamfer preparation is possible as long as a mechanical support is guaranteed, particularly when used with reduced tooth structure (e.g., after repeated crowning).
   • flat chamfers, shoulder preparations with angles greater than 100º, tangential preparations and bevels of the preparation limit are contraindicated.
6. It is necessary to place a proximal box in the preparations adjacent to the edentulous space, to allow bulking of the framework at the axio/occlusal line angle.
7. Use the preliminary impression to fabricate a well-fitting custom temporary restoration.
8. Take final impression with Panasil vinyl polysiloxane or similar impression material.
9. Secure an adequate interocclusal record.
10. Cement temporary restoration.
11. Prepare detailed lab prescription with details of nature of opposing teeth, age of patient, surface occlusal stain required, etc.

Ideal 3-Unit Bridge Preparation

Ideal Posterior Preparation (Full Circumferential Shoulder 90° - 120°)