When submitting a case with physical impressions, we accept any silicone-based impression material, including PVS, VPS, and polyether material, in disposable trays. For more information on best practices with taking impressions, see the full article here. 

Per our terms and conditions, alginate impressions, stone models, and metal or mesh impression trays will be rejected. These and all other submitted materials become the property of ClearCorrect and will not be returned.

To clarify the reasons for this:

• Alginate dries out and the material itself can shrink or expand depending on environmental factors. This can make the aligner too big or too small, depending on any changes.
• Stone models don’t always survive the shipping process. We usually see some sort of chipping, especially along the cusps/incisal edges. Sometimes this can be a whole tooth, but most of the time it will be something minor that’s hard to detect but can still cause fitting issues.
• Additionally, with stone models, we can’t control the quality of the stone model. The impression can be perfect, but if the pour-up is bad the scan will be compromised. Things like air bubbles can be filled in, but it leaves us guessing at what the shape of the tooth is actually like.
• Metal trays cannot be run through our scanner, thus cannot be used. 
• Mesh trays (sometimes known as "triple trays") are often too shallow to capture an adequate 2-3 mm gingival margin, and incisal detail is often lost as teeth impinge on the mesh. The scanning software also does not recognize multiple arches at once.

Here is some information on bite registrations and why they are not required. 

Digital bite registrations:

• Digital bite registrations are not required and not compatible with our software.
• Buccal digital occlusion is the only portion that is captured with digital bite registrations and we need to see where the teeth fit into the grooves- so the digital bite does not work.

Physical bite registrations:

• Are not required and not scanned unless specifically requested (either in the prescription form or in response to the technician in a setup decline).
• Physical bite registrations are only stored for one month.
• If you submit a revision and ask to use the original bite registration, we may not be able to accommodate.