How to Avoid the Most Common Dental Impression Errors

January 18, 2022

Dylan Schubert | Blog Author at Pro-Craft

Written by:
Dylan Schubert

How to Avoid Common Impression Errors

Nicole Donnelly • Jan 18, 2022

An accurate impression is the foundation to creating successful bridges, crowns, or dentures. Yet there are multiple factors that can affect accuracy. Here are some solutions to the most common dental impression errors.

One of the most important yet challenging dental procedures is taking the perfect impression. An accurate impression is the foundation to creating successful bridges, crowns, or dentures. Yet there are multiple factors that can affect impression accuracy. Often, errors can be made during simple steps causing underfilling, overfilling or materials not setting in time. These common pitfalls affect patient comfort, time, and overall costs. To avoid repeated mistakes, it’s important to identify the cause of the error in the original impression. This guide reviews some of the most common dental impression errors and how they can be solved. 


Most Common Dental Impression Errors


Marginal Tears


Marginal tears may appear when the wash material has insufficient tear strength. Tear strength of materials can vary between manufacturers and viscosity. The lower in viscosity the material is, the more likely it is to tear. Marginal tearing can also be a result of removing the impression prior to a complete setting of the material.


Solution: Choose a more viscous material that can help improve the quality of the impression.


Internal Bubbles


When moisture, fluid, or air is trapped in impression material it can cause bubbles in the impression. Bubbles that are large enough in size can negatively affect a prosthetic and compromise fit. The typical cause of large ill-defined bubbles in a preparation is usually from fluid buildup, but air entrapment can also be an influence in deep and narrow preparations.


Solution: Ensure there is enough impression material in the tray. Keep the tip of the material gun in the tray as material is expressed, this will force any air out and will decrease entrapment. You can also thoroughly flush and dry the preparation prior to impression taking.


Improper Tray Selection


To capture an area without any distortions, it is important to select the right sized tray. The tray being used should be large enough to cover all teeth without contacting the soft tissues. Once an impression is completed, the results should not demonstrate any show-through of the tray. Show-through implies that the tray used was either too small or arranged improperly.


Solution: It’s best to keep a wide selection of trays in sizes in-stock. Stock trays are supplied in basic sizes, but they may not fit all patients seen in a practice. Metal trays can be adjusted in the posterior regions, but modifications to the anterior can be challenging. Plastic trays are easier to modify. They can be readapted to fit a specific patient with just an alcohol torch used to heat the plastic. 


However, plastic trays can create a rebound effect when removed from the mouth. To eliminate this possibility a metal tray with sufficient support  like Clinicians Choice Quad tray will make your life easy and provide an accurate impression every time.


Choosing Inadequate Impression Material


Choosing the right impression material will have a critical impact on achieving precise and predictable results. It will be essential to know the working time for the material you are using.


Solution: If possible, choose impression material that is more hydrophilic. This will help it adapt to teeth more easily. 

When all is said and done, after tracking impression materials over the years in our lab Aquasil from Dentsply and Impregum from 3M have the least amount of remakes and adjustments.


Poor Margin Detail


Poor margin detail is one of the top complaint’s technicians have when it comes to impressions. And yet it's one of the most crucial aspects of a dental impression. Without accuracy, problems such as open margins or inadequate prosthetic fits are more likely to occur.


Solution: Use improved retraction methods with syringeable hemostatics.


Surface Contamination


Surface contamination can trigger a tacky layer of impression material. This layer can prevent the material from setting correctly.


Solution: Rinse the working area with water or mouthwash and make sure it is thoroughly dried. Clinicians should also wash gloved hands as this will remove any residual powder and surface sulfides. An alternative to prevent putty contamination is to use powder-free or vinyl gloves. 




Creating an impression is the most important and yet technique-sensitive step in fabricating prosthetics. With proper preparation and attention to detail, many impression errors can be avoided. Spending a few minutes to identify and correct potential complications can save clinicians the difficulties of starting over and making a new impression.



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