198 Cambridge Rd, Kingston Upon Thames, KT1 3LF info@simplycrownandbridge.co.uk 020 8549 4836

Impression advice

We use the latest digital technology to elevate the patient experience and ensure all our restorations are highly accurate and precise. Sometimes, however, impressions are still needed, so we have collated our advice and recommendations for quality impression-taking here.

How can dentists help?

Here are our recommendations for consistent high quality impression taking.

1. Impressions need to be taken in full arch trays. The trays must be of a high quality and extremely rigid. These can be plastic or metal. The standard blue plastic tray is not structurally solid enough, and regularly distorts.

2. High quality impression materials should be used. Our personal favourite is Honigum available from Henry Schein.

3. Always use a good tray adhesive. So many perfectly good impressions are invisibly distorted because they have pulled slightly away from the inside of the tray. A good tray should also have excellent retentive properties, not just holes.

4. Take your time. You shouldn’t need to rush. A good quality impression material will always give time to work and will be easy to mix.

, Impression advice
, Impression advice

5. Retraction cord. This is a must when working privately. You really don’t want us guessing where the edge of your preparation is. Remember you can see the contrast of tooth and gum. We get no such help to pick out the margin.

6. We recommend a one stage technique. Two stage techniques allow for the compression of an already set material against a flowing material. If the correct pressure relief has not been provided, distortion will occur. To sum up. Two stage techniques are considerably more technique sensitive. A good one stage technique would be as follows:

– Syringe the soft body around the preparation.
– Place the putty in the tray around the whole arch.
– Prepare a deep indent in the putty giving space for the teeth. This helps to relieve pressure when the impression is placed.
– Syringe the remaining soft body into the prepared indent. This must also go around the whole arch.
– Place the tray and use an even, sustained pressure. Allow no movement while setting.

7. We always recommend using the same silicon impression materials and techniques for the opposing arch. Alginate distorts over time, absorbing or losing moisture if not kept in perfect conditions. By the time your alginate has sat in the surgery for half a day, been with a courier or in the post for several hours, then waited to slot into the laboratory’s work schedule, it will not have the integrity it had when it first came out of the mouth. Remember, an accurate opposing impression is just as important as an accurate working impression. Technicians cannot always tell if an opposing arch is distorted. We can be working in the belief that we have a 2mm gap when the reality is we only have 1mm.

8. When taking the bite please throw away the wax. It doesn’t work. You need to syringe a good quality silicon bite material into the area of the preparation. If you are preparing more than one tooth and are concerned about losing the bite, then we recommend that you prepare a few teeth first, evenly spaced around the arch. Leave enough teeth for the patient to easily find centric and then syringe your bite material into these localised areas. Then continue your preparation. The accuracy of the silicon sections enables us to easily locate the patient’s preoperative position.

9. In the lab, we carefully trim the silicon bite material cutting through the area of the preparation, enabling us to accurately see if the silicon is in place. There should be no gaps around the preparation or the opposing teeth. When this has been established, we know we must have the same space on the model as you had in the mouth. If any gaps are visible, we know something is distorted. At least with a bite taken like this, the additional information can help us compensate for this distortion.

10. We don’t recommend the use of triple trays for private work, but if you do wish to use them, please download “Triple Tray Distortion“.

, Impression advice

Let’s get your journey started

Whether you’re a patient or a dentist, we’re happy to chat. We accept referrals and self-referrals.

If you have any questions or want to know more about how we can create naturally beautiful smiles, simply get in touch.