Tooth Preparation and Digital Impressions for a Single Crown

Before preparation

• Confirm the restorative material. If clearance is limited or the preparation is short or dark, discuss the case with the laboratory in advance.
• Select the shade before prolonged tooth dehydration and specify the shade guide system. Record the original anatomy with a scan or matrix if it provides a suitable reference.
• Prepare the scanner, isolation, retraction materials, and provisional restoration. Plan enough appointment time for the complexity of the case.

Tooth preparation and tissue management

Create a clear, continuous preparation margin, round internal line angles, and eliminate unwanted undercuts. The finish line design, amount of reduction, and restoration thickness must comply with the instructions for the specific restorative material.

Select retraction and hemostasis methods according to the tissue condition. Expose the margin for scanning and remove blood, saliva, and residual materials.

Review the scan before the patient leaves

• The margin is visible around the entire preparation, including interproximal areas, and is not obscured by tissue or fluids.
• The preparation and margin are free of missing scan data, duplicate surfaces, and distortions. Inspect the digital model from multiple angles.
• The bite record reflects the clinical situation. Evaluate clearance against the material requirements, using an interocclusal clearance map when available.

If the scan is unclear, address the cause, delete the affected scan area, and rescan according to the scanner’s instructions. Verify that the scan data are correctly aligned. If the margin remains indistinct, obtain a new impression after resolving the clinical cause. Do not ask the technician to reconstruct the margin by making assumptions.

What to send to the technician

Include the dentist’s name and practice; patient identifier; tooth number and numbering system; restorative material; shade guide system and shade; preparation shade (stump shade), when needed; preferences for form, contacts, and occlusion; clinical limitations; scans of the treatment area, opposing arch, and bite; requested completion date; and contact details for any questions.

Include photographs when they help communicate shade or form. For an esthetically significant case, a smile photograph and a close-up with a shade tab and clearly legible shade designation are useful. For a dark preparation, include a photograph of the prepared tooth. Avoid color filters.

Before definitive cementation

• Confirm complete seating, marginal fit, proximal contacts, shade, form, and occlusion.
• Polish the restoration after any adjustments. Tooth and restoration pretreatment and the cementation method must follow the instructions for the restorative material and cement.
• Remove residual cement and all retraction cords, and provide the patient with care instructions.

If the restoration does not seat completely or the fit is unsatisfactory, postpone cementation, determine the cause, and discuss the case with the laboratory.