What constitutes good modelling wax technology?

Martyn Young, Dental Technician and Laboratory Owner at Cotswold Dental Laboratory, studies the comparisons between differing standards of modelling wax.

Just over two years ago, our laboratory was introduced to a particular modelling wax sheet that we have continued to use exclusively to this very day. The manufacturer concerned, states that the wax we have been using has similar handling characteristics to their market leading product, but their product offers much greater stability and strength.

Lab Technician using Dental Modelling Wax

Having studied the comparisons, this appears to be true. We use this wax with confidence, as it provides the consistency and control that we desire, enabling our team to produce the high quality products demanded of us. We have also found that unlike some of the other modelling waxes on the market, it does not distort in the patients mouth, or during delivery to the client and back to the laboratory. This could be partly due to the fact that it has a slightly higher primary softening temperature, which is typically 40°C - 43°C as opposed to the manufacturer's standard wax that has a range of 35°C - 41°C.

Constituencies of the wax

Being a specialised prosthetic laboratory, we use the higher end wax for all of our denture cases. We have had excellent results with this product and have even had favourable comments from some of our clients. They too have noticed how stable this wax has been when taking bite registrations and assessing the wax try in of dentures.

Overall, the results have been superb, as the wax does not flake while trimming down for contouring. It also pin flames extremely well taking on a very smooth appearance, this in turn leads to a high quality finish, which you can then buff using cotton wool and cold water for enhancement.

One of the primary reasons for this quality is the hardness and toughness of the wax. This has been achieved by the fact that the manufacturer rolls their sheets to size, which I believe, creates a uniform, dense, and toughened sheet, undoubtedly reinforcing the aforementioned reasons for this quality. It is these qualities that have lead to greater job satisfaction, as the wax is always reliable. Additionally, the wax is also quite competitively priced for this quality of product and represents excellent value for money.

At l.5mm thick, these modelling wax sheets are the industry average. I have found this adequate and I believe it is claimed to be the optimum thickness for the palate of the final denture.

Basic guide to using this advanced modelling wax

  1. In order to fit the sheet to the model, gently warm the wax and then adapt its properties without overheating. Make sure that you do not stretch and thin the sheet too much.
  2. Final fitting to the denture model is generally achieved by slight warming with a pin flame which facilitates enough softness to produce the required finishing touches with a wax knife.
  3. The base ortrial set-up can be polished to a brilliant mirror-like finish using the normal technique of cotton wool and cold water.
  4. I personally use the same manufacturer's straight wax bite blocks, as these can also be easily adapted, especially after being immersed in warm water for a few minutes to soften them.

Modelling wax research

During some research I carried out several years ago, I found that sheet modelling waxes were made in various ways - which of course can lead to very different characteristics and qualities.

For instance, did you know that there is an industry standard for modelling wax? The ISO standard for modelling sheet wax is: ISO 15854:2005.

This standard was designed to test sale wax items in differing situations and at different temperatures. In accordance with EU standards, all modelling waxes on the market should be made to pass these regulations.

At the present time there are three classifacations for Type 2 baseplate wax:

  • Class 1 Soft
  • Class 2 Hard
  • Class 3 Extra Hard

Each manufacturer will decide which category their wax conforms to. This process ensures that they can market a wax that meets the industry standard, but with wide ranging performance. Modelling wax class 1 and 2 are the only relevant products for use in the dental laboratory.

Knowing what the tests are, coupled with how a particular wax performed in the standard ISO test is certainly an indication of how it was likely to perform in practice. I have indicated below the standard flow tests used for these types of wax.

ISO 15854:2005 Tests

This standard tests the waxes properties and performance.

The classification (i.e. Class 1, 2 or 3) of a particular type 2 baseplate wax is determined by its flow properties at different temperatures.

  • Room Temperature (23°C +/-1°C)
  • Mouth Temperature (37°C +/-1°C)
  • Above mouth temperature (45°C +/- 1°C)

Tests are carried out in a temperature controlled water bath using the equipment illustrated on the opposite page.

Naturally it is easy to know what you are purchasing if you are given this type of knowledge in the first place. However most customers find that their manufacturer will not supply this type of technical information, instead they rely on the ISO number as being an adequate source of quality control.

Further to the aforementioned tests, I also use a further series of tests for the evaluation of materials used in my own laboratory. In the case of modelling wax, I use the chart below:

The desirable properties of dental modelling wax could be stated as follows:

  1. High strength and rigidity at mouth temperature.
  2. Wide softening range above mouth temperature.
  3. Easily mouldable in the softened state, without flaking, cracking or tearing.
  4. Low thermal contraction.
  5. Easily carved at room temperature without flaking or chipping.
  6. Little change in properties on melting and re-solidification.
  7. No residue on boiling out.

The list I have produced demonstrates just a few considerations. There are two other factors that you could also consider.

Colour and Cost

So what is the true cost?

Some waxes may be less expensive to buy, but if they deform at mouth temperature, they can end up costing you a lot more in terms of lost time. Therefore, readapting wrong bite registrations to the model together with distortions of wax try in's, are just two problems that may be encountered during this process.

Colour?

Considering the colour of the wax is very subjective. What you might consider as the right colour; someone else could and probably will find completely inappropriate. It is for you and your client to decide what colour is acceptable.

On saying this, it is up to the dental laboratory to evaluate the suitability of a particular modelling wax.

One way of doing this is to complete a series of simple tests as follows:

(a) Soften a wax sheet over a Bunsen flame and observe its characteristics. Compare it with other waxes of a similar style.

Note the result: i.e. is the wax easily mouldable in the softened state, without flaking, cracking or tearing? Is there low thermal contraction of the wax on the model? Did the wax perform in accordance with your expectations for this type of product?

(b) Soften the wax sheet and mould into a block suitable for wax registration. Compare as previous with other waxes.

Once again, note the result: i.e. did the wax mould well and was it easily carved at room temperature without flaking or chipping? Did the wax perform in accordance with your expectations for this type of product?

(c) Carve, trim and pin flame the wax blocks; polish with cold water and cotton wool. As before, compare with other waxes.

Finally, note the result: i.e. did the wax carve and trim easily? Did the wax take a good surface polish?

(d) Set a few teeth into position on the wax.

Did the teeth stay in position after the wax had cooled down? Were the teeth easy to re-position and did the wax carve easily with a good surface finish?

Summary and experiences

Modelling waxes vary in their consistency and strength. It is easy to criticise products just because they don't come up to your expectations. However, we have noticed quite a major difference over many of the waxes we have tried previously. The manufacturer's wax, that we have case studied in this article, has a slightly higher melting point and greater toughness than many other products in the market. I would therefore hope, in addition to the Anutex HS, that the manufacturer also produces an Anutex HS manufactured wax block; this would be an asset, as it would complement the sheet wax we are still using to this very day. (DWS512 - Anutex HS straight bite rims are now available)

All this said, it is worth bearing in mind that manufacturers who have attained ISO status, are without a doubt, the best companies in the market to purchase your waxes from. In this case, the manufacturer concerned, also demonstrated their expertise in this niche market sector, by displaying technical information in the form of comparison graphs. For me, this put the icing on the cake. Our laboratory has continued to use this manufacturer's wax, and will continue to do so. That is until a better product is introduced!