What is the purpose of a wax spacer in custom tray fabrication?

[rsweeney]

I have yet to find an explanation.

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[Yah-E]

to create a space for impression materials.

 

[rsweeney]

to create a space for impression materials.

Why do we want to create space for impression materials. Even without the spacer it seems that there is still enough space for impression materials. Why not put impression material directly in the tray?

Thank you

 

[aphistis]

Why do we want to create space for impression materials. Even without the spacer it seems that there is still enough space for impression materials. Why not put impression material directly in the tray?

Thank you

You *do* put impression material straight in the tray, but you need to have room for it. Putting wax over the cast (or creating tissue stops on the tray itself) gives you 2-3mm of space between the tissues & the impression tray, and that space is where the impression is created.

 

[seablaster]

We've been taught that this is all part of the selective pressure technique. The places on the cast that act as the primary stress bearing areas aren't relieved. For example, in an edentulous maxilla, the premaxilla area and part of the midline are relieved with baseplate wax. We then border mold, remove the relief wax, and then drill holes in the relieved areas of the tray for pvs to escape.

 

[aaram]

so basically one needs to achieve an accurate impression in terms of detail reproduction and dimensional stability.this can be achieved by taking impression with a uniform layer of an impression material which will prevent any distortion in the impression as well as prevent nonuniform and unwanted pressure areas to develop.a spacer is basically given to maintain a uniform layer of impression with accuracy in detail.the material used for the final or wash impression shud have the properties of being able to produce details in a thin layer thatis why called wash.so spacer is used .in selective pressure tech we remove wax or any other kind of spacer fronm the specific( relief )areas.but now a days monophase materials in elastic impression materials are used for one step impressions.

 

[aaram]

If the preliminary impression is accurate no need to take final wash.but thats not the case generally becos very few materials have the property of accuracy.also there is a tech where there is no spacer required.the primary impression is scraped off directly and no custom tray made instead wash imp is taken on the primary impression itself.hope this helps

 

[aaram]

can refer to dental clinics of north america- i think it was impressions chapter in one of the prostho sections

 

[adamlc18]

sweeny,

read seablaster's post. He said what we have been taught.

 

[rsweeney]

sweeny,

read seablaster's post. He said what we have been taught.

Thanks to everyone for their replies 🙂

 

[ItsGavinC]

Ahh, custom trays. You guys are so old school. 😀

Lately I've been using Accu-gel/Accu-dent, which eliminates the need for a custom tray. Pretty good stuff if the art of taking the impression can be mastered.

 

[Dr. Dai Phan]

Ahh, custom trays. You guys are so old school. 😀

Lately I've been using Accu-gel/Accu-dent, which eliminates the need for a custom tray. Pretty good stuff if the art of taking the impression can be mastered.

Hello,

This is my take on the custom tray. You although do not need to have one but surely it WILL minimize the chance of something goes wrong if you do. You will notice that with custom tray, it is far harder to remove from the mouth when compared with stock tray. Why? That is because the impression material is forced to go into nooks and cranies while with stock trays, there are too many "escape" routes for the material. With that being said, you have much less chance to have a bubble or void. I believe that five minutes to fabricate a tray is worth it. Regrading the Acudent system, the main drawback is the proper extension of the trays that are supplied. Too often, either the trays are too long or they are too short. True, they give all the details but more often than not, the impression is far too extended. I personally will not use it as it is very difficult to achieve proper border extension in such. DP

 

[shraz]

Each impression material has a minumum thickness, and less than that thickness, will affect it's accuracy. So, by making the spacer and the stops, you gurantee that the thickness of the material will not be less than the thickness of the spacer.
For example: using ZOE , you should make a spacer for 0.5 mm. Alginat 2 mm at least.
There is debat on this issue, some dentist belive that without spacer is the same with a spacer, some belive that you need the spacer only in the upper...!!!
This is what I learned in Jordan Uny of Science & Tech.... 😛