Overview: This guide explains how to capture a wash impression and perform a 360-degree extraoral scan using a patient's existing denture or wax rim to ensure accurate digital fabrication.
Capture a Wash Impression
Follow these instructions to prepare the existing denture for 360-degree scanning.
Prepare the Denture or Wax Rim
Clean the denture or rim: Thoroughly clean the existing denture or rim to remove all debris or residue.
Apply adhesive (Optional): Apply a small amount of tray adhesive to the denture base to help the impression material adhere to the surface.
Apply Impression Material
Dispense material: Dispense medium or light body impression material onto the surface of the denture base, starting at the posterior region and working forward.
Smooth and extend: Use a dental spatula to smooth the material and extend it to the borders of the denture.
Verify coverage: Ensure the entire surface of the denture base is covered with impression material.
Perform the Wash Impression
Seat the denture: Have the patient bite down into the impression material. Ensure the material is evenly distributed and covers all areas.
Mold the borders: Complete border molding movements with the patient. This allows the designer to assess if the denture border needs extension.
Set the material: Allow the impression material to set according to the manufacturer’s instructions.
Finalize the Impression
Remove and inspect: Remove the denture from the patient's mouth once the material is set. Inspect the impression for bubbles or defects.
Trim excess: Trim any excess wash material that overlaps onto the anatomical landmarks of the denture.
Dry the surface: Thoroughly dry the impression using a clean towel or compressed air.
[!NOTE]
If wash impression material is unavailable, a soft liner may be used as the anatomical reference.
If fit is good, wash impression is unnecessary.
Workflow Sequence for a 360° Extraoral Scan
Follow this specific order to capture all surfaces of the appliance:
Intaglio surface: Tissue-fitting side.
Border: Peripheral edge.
Occlusal surface: For dentures with teeth.
Cameo surface: External face.
Bite: Buccal bite capture for articulation.
Scan order: Intaglio → Border → Occlusal → Cameo → Bite
Step 1: Scan the Intaglio Surface
Position the scanner over the intaglio surface to capture the flange, ridge, and palate.
Move the scanner slowly in overlapping zig-zag passes.
Wiggle the scanner lightly to capture deep undercuts.
Keep overlapping scans inside the green capture box to prevent layering errors.
Note: Intaglio coverage naturally results in higher image counts; prioritize complete capture over low image totals.
Step 2: Scan the Border and Occlusal Surfaces
Transition smoothly from the intaglio surface to the buccal border.
Use a rolling motion (inside to outside) to capture the border edge.
Continue building scan data until you reach the teeth.
Scan the occlusal surface from the back to the front.
Wiggle the scanner over the incisors for better detail.
Sweep toward the palate with overlapping passes until the border ring is unbroken.
Step 3: Scan the Cameo Surface
Start over the occlusal surface and glide the scanner across the buccal, lingual, and palatal areas.
Pay extra attention to sites #8 and #9 for palatal detail.
Continue scanning until the posterior border is reached.
Complete the cameo coverage even if the image meter rises to ensure continuity.
Step 4: Capture the Bite
Capture the buccal bite zones (posterior, mid, and anterior) while the appliance is in occlusion.
For wax rims, ensure midline marks are visible to the scanner.
Minor residual green areas on the scan are acceptable; 100% clearance is not required for a successful bite capture.
360 Scan Strategy Intaglio First Upper Arch
Troubleshooting Common Scanning Issues
| Issue | Cause | Solution |
| Glare or reflective spots | Bright lighting or glossy material | Dim room lights, keep surfaces dry |
| Lost tracking / drift | Large untextured areas or movement | Add reference marks, restart from a textured area |
| Missing or layered data | Fast scanning or poor overlap | Slow down, maintain overlap, use zig‑zag/circular passes |
| Surface misalignment | Incorrect sequence or incomplete border | Follow workflow order, re‑scan connecting borders |
| High image count warning appears late in the scan. | Denture cases naturally require more images; the meter triggers only at ranges that may affect Chairside performance. | Prioritize completing intaglio and border continuity; if needed, pause to let frames render. Proceed if the scan remains stable; the updated meter allows higher counts for quality outcomes. |
| Faded or inconsistent texture | Overexposure or steep angle | Keep mid‑range distance, shallow angle, avoid scanning too close |