Distortions

Working time exceeded, flowability already impaired. +

Select material with sufficient working time and 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.

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

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.

Distortion during impression removal. +

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 the prepared 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. +

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.

Selected impression tray is too flexible. +

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

The combination of the tray and impression material is not appropriate. +

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

Delamination of tray and wash material (2-step technique). +

Clean the initial impression with plenty of water (or alcohol) and air. During this procedure, saliva has to be removed completely from the impression. Dry thoroughly before taking the second impression. Do not forget to clean and dry after try-in of first impression.

A high viscosity was material can displace the tray material which has already set (2-step technique). +

Use low viscosity wash materials which are able to form very thin layers. Carve the first impression with tray material properly before applying wash material.

Tray material used is too flexible and distortion occurs during second impression (2-step technique). +

Use a material with low flexibility and high hardness after set.

Local distortions due to insufficient carving (2-step technique). +

Carve the tray material properly. Check repositioning prior to taking the second impression. Apply controlled pressure by slow and straight tray insertion.

Detachment of tray material from tray during carving (2-step technique). +

Apply adhesive on bottom and on inner sides of the tray. Use a sharp carving instrument to minimize stress at the interface of tray material and tray Otherwise, tray material could detach from the tray unnoticed and causes deformation.