What causes distortions in dental impressions?

Minor distortions may not even be visible to a dentist or dental lab. A case with quality margins, fit and function can only be created utilizing an accurate, distortion-free impression. Learn common ways to adjust the dental impression technique to minimize distortions.

Browse this page to read about common issues and find solutions and tips to eliminate distortions in dental impressions. You can also request to download a PDF of the full guide.

Related Issues

Voids on Margin

Margins not sharp

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Working time exceeded
Tray movement
Tray removal
Separation of material and tray
Tray too flexible
Tray and material don't work well together

Working time exceeded, flowability already impaired

What can you do:

Select material with sufficient working time (i.e. regular set instead of fast set). Make a choice depending on the individual situation and preference of material. Do not exceed working times given in the instructions for use. In case of 3M Oral Care materials follow given intra-oral syringing times for wash materials.

Pay attention to storage temperature. Working times are reduced due to higher temperatures of the product, while intra-oral setting times might be longer if the temperature of the product is lower.

3M™ Impregum™ Soft Polyether Impression Material offers a very long working time with constant flow. And, polyether impression material is less temperature sensitive in its setting reaction
than VPS materials.

3M™ Imprint™ 4 VPS Impression Material offers both a fast and a regular setting material. Select Quick Set for 1 to 2 unit cases and Regular Set for cases that involve 3 or more units. Do not exceed working times given in the instructions for use. In case of 3M Oral Care materials follow given intra-oral syringing times for wash materials

Lack of support/insufficient stabilization of the tray by operator during the initial phase of polymerization

What can you do:

Support tray until impression material is sufficiently set. Stabilize the tray after seating, avoid any movements. When taking an impression of the upper jaw, you can easily find support on the chin or cheek bone of the patient.

With impressions of the lower jaw it is recommended to support the tray on the mandibula. Patients should close their mouth as much as possible without biting down on the tray to avoid deformation of the mandibula and, thus, errors in the impression. Do not try to correct the position of the tray after insertion.

3M™ Imprint™ 4 VPS Impression Material has the fastest intra-oral setting time which means less time for unintended movements.

Distortions during impression removal

What can you do:

Ensure the impression tray is the proper size prior to taking the impression and the material has excellent elastomeric properties.

Remove the impression along the axis of prepared the tooth.

Follow manufacturer ́s instructions for intra-oral setting time and make sure that the impression material has completely set before removal.

Delamination of impression material and tray

What can you do:

Use tray adhesive for all types of impression trays and apply adhesive on bottom and on inner sides of the tray, including gauze of dual-arch trays.

Alternatively use 3M™ Impression Trays: With their integrated self-retentive fleece strip, the application of a tray adhesive is not needed – saving valuable preparation time.

Selected impression tray is too flexible

What can you do:

Use rigid trays. When using dual-arch trays, impression materials with low flexibility and high shore hardness are beneficial to stabilize the impression.

Both 3M™ Impregum™ Polyether Impression Material and 3M™ Imprint™ 4 VPS Impression Material offer heavy-body material options that are suitable to be used with dual-arch trays.

The combination of the tray and impression material is not appropriate

What can you do:

Do not use highly viscous putty materials in combination with flexible plastic trays. Dual-arch trays can be deformed during impression taking.

Not seeing what you need?

Download our comprehensive guide to troubleshooting most common dental impressioning issues, including a bonus section on 10 Golden Rules for Taking Perfect Dental Impressions.

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