Thermo Grip Overdentures



VERSACRYL Thermo Grips fashioned over 3 mm Bicon Implant Balls (orig.: Boston
University)

This application requires caution and some experience with VERSACRYL, simply because the material is polymerized intra-orally and does not permit a large degree of error. Depending on the amount of undercut present on the male attachments, the depth of the female cavities and the amount or area of attachment, the ratio of the Hardener and Softener is very critical. To be foolproof, a test should be done, either by the laboratory or in the operatory on a duplicate model, containing analog attachments, to determine the correct A-B ratio of the mixture ahead of time.

The finished overdenture will have empty mushroom-shaped cavities, where the male attachments protrude into the denture. These cavities have to be filled with the correct VERSACRYL mixture to fashion the female retentive grip over the male attachments. Once that ratio has been established, you are ready to call in the patient and finalize the procedure.

  1. Try-in the overdenture as is, to make sure everything fits as it should.
  2. Clean and dry the denture and roughen the insides of the cavities
  3. Prime them with monomer
  4. In a small mixing cup: prepare the liquid mixture, using the correct Softener and Hardener ratio. Stir the liquids for 10 seconds
  5. Slowly add VERSACRYL polymer powder, while stirring, until a very light creamy consistency is reached (approx. 1,5 part powder to 1 part liquid)
  6. Vibrate the thin mixture to free of any air bubbles
  7. Immediately, fill the cavities about halfway with VERSACRYL material, while vibrating
  8. Wait for a short while and monitor the left-over material in the mixing cup
  9. Once it has gelled, so it does not run out any longer, insert the overdenture in the patient's mouth, check the bite, have the patient clench gently and let the material polymerize at body temperature for at least 20 minutes.
  10. Then, have the patient rinse the areas with the warmest water possible, for a few times consecutively. The denture can now be removed, as the VERSACRYL grips have softened.
  11. Cool the denture in cold water and use a large round burr to remove the excess flash.
  12. Warm the denture in a bath of medium warmth (about midway between body temperature and hot tap water, but for sure lower than what the patient is going to use daily), for at least 1 minute.

Quickly insert and remove the overdenture a few times to test the amount of retention, more specifically the amount of resistance necessary to remove the denture while still warm.

The amount of retention can now also be adjusted by removing small amounts from the sharp edges, by sloping the insertion path slightly.

In case the denture is stuck and cannot be removed, drill away the pink denture acrylic covering up the VERSACRYL grips, this way they will be easier to soften with warm water.

Security for the patient: the overdenture should not loosen by regular tongue pressure, coughing or sneezing, only on command: rinse with warm water to activate the VERSACRYL grips and remove the denture.

Important note: in this application, do not attempt to use VERSACRYL so soft, that the denture can be easily removed at body temperature and without the use of warm water.

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