Top tips for a perfect traditional impression
Featured Products Promotional FeaturesPosted by: Dental Design 18th November 2022
Intraoral scanning technology has given clinicians more options, but there are still plenty of situations where a conventional impression material can be utilised to great effect.
For instance, intraoral scanners are not always able to easily access all areas of the oral cavity, especially when it comes to capturing subgingival detail. Plus, excess moisture or space constraints can mean that using an intraoral scanner isn’t viable for a particular case.
So, what are the golden rules for taking an excellent impression with traditional materials?
- The right tools for the job
It’s essential to be mindful about tray selection and choose the correct size and type for the case at hand. Trays should be customised with stops and supports for a better fit where necessary. For wash materials it’s all about pinpointing the properties that a material possesses and what impact these will have on the final detail reproduction.
Both Vinyl Polysiloxane (VPS) materials and Polyether materials have their benefits, but as Polyether materials boast excellent hydrophilicity, universal applicability, constantly flowability and rigidity they tend to be a superior choice. However, VPS materials are often faster and easier to remove from the oral cavity.
One good rule to remember is that the deeper the margin is, the more flowable the wash material should be in order to reach those difficult areas.
- Adequate retraction
Capturing marginal detail is fundamental for a well-fitting, aesthetic final restoration. Professionals should find a retraction method that works best for them, whether this is using retraction paste, a single retraction cord method or a double retraction cord method. The goal is to achieve consistent retraction and haemostasis.
A good rule here is to remember that the higher consistency of wash material, the more gingival retraction space needed – the preparation margin should be clearly visible before impressioning commences.
- Use tray adhesive
Tray adhesive should be thoroughly applied to help reduce the chance of detachment. The type of adhesive you use will depend on whether you’ve chosen a VPS or Polyether impression material, as these products are especially formulated to work with these different products. Clinicians need to ensure the adhesive has dried properly before the material is added to the tray. Although not essential, not using tray adhesive may lead to invisible failures, so it’s definitely worth taking that extra step to help guarantee outstanding results.
- Achieve a uniform and homogeneous mix
Hand mixing materials is time-consuming and prone to error. Automatic mixing machines should therefore be utilised where possible, as this will ensure that your material is homogeneous and will provide all of the features promised by the manufacturer, such as the appropriate setting time, flowability etc.
Mixing machines speed up the mixing process, prevent cross-contamination and are often as simple to use as pushing a button.
- Glove selection
It goes without saying that wearing gloves is essential. However, the material of your gloves matters more than you would think. For example, hand mixing VPS impression materials while wearing latex gloves can inhibit them from setting.
- Keep the tip immersed
Air bubbles in material can cause defects. One simple way to avoid these is to keep the tip immersed during material application – this is true for both gun-based materials and those from an automatic mixing machine – remember, air is not your friend!
- Careful tray insertion
The manner you insert loaded tray into a patient’s mouth can have a big impact on the final impression. Inserting the tray at an angle may cause the material to shift, which could impact the accuracy of the final impression. The tray should be slowly inserted parallel to the long axes of the prepared teeth and then held in place without applying any pressure while the material sets.
To help ensure accuracy, the patient should never be told to hold or bite down on the tray.
- Tray removal
Improper tray removal can result in permanent deformation of the impression. To avoid this, the impression should be removed exactly in the direction of the tooth axis of the prepared tooth. For optimal removal in the upper jaw, the tray should be loosened on the opposite side. On the lower jaw, optimal removal starts with loosening at the prep side.
- Check preparation margins
Once the impression has been removed, it’s important to check the preparation margins for defects. This includes any voids, tears and distortions, as these will indicate the need for a retake.
- Disinfection
Disinfecting the impression properly before sending it to your dental laboratory is an important step. The impression should be rinsed with water before and after disinfection, and dried before being sent to the lab. There are multiple options available for disinfection.
Excellent first impressions
3M Oral Care provides a range of impression materials, single-use trays and retraction products that ensure you can take an outstanding traditional impression. From Impregum Polyether Impression Material from 3M to Imprint 4 VPS Polyether Impression Material from 3M, 3M has solutions for every scenario.
For more information, call 08705 360 036 or visit www.3M.co.uk/Dental
3M, Impregum and Imprint 4 are trademarks of the 3M Company.
