Instructions to Construct a VERSACRYL Internal Clasp
A VERSACRYL Internal clasp incorporated into an upper denture
Each VERSACRYL Laboratory kit contains:
- VERSACRYL Softener monomer
- VERSACRYL Hardener monomer
- VERSACRYL clear and pink polymer powders
The two rigidities are prepared simultaneously:
- In 2
small jars, first mix monomer liquids and stir for 10 seconds. The recommended
proportion for the soft cushion retention is: 80% Softener to 20% Hardener.
The bracing clasps are mixed with 35% Softener to 65% Hardener. In the
instructions, the ratios are expressed in 'drops' of each liquid.
- For each
rigidity, just before using, slowly add the VERSACRYL powder while stirring,
until the consistency is light creamy (approx. 1.5 parts powder to 1
part liquid). Wait until the mixture slightly gels and can be securely
applied in the proper area.
- Two methods to construct a VERSACRYL Internal clasp:
- Double-pack
heat-cure into a new denture: flask, remove wax and pack denture with
pink acrylic using a polyvinyl sheet. Press and re-open flask. Cut away
the area, around the abutment tooth, creating a void where the clasp
assembly was determined.
Pack with the softest VERSACRYL mixture directly into the undercuts; then with the harder mixture, fill the bracing areas and link the clasp to the pink denture base. Close flask, final press and process as usual.
- Self-cure onto a new or existing denture: cut back and prepare the surfaces by roughening and priming with Hardener using a brush. Apply the softest VERSACRYL mixture directly into the undercuts, then with the harder mixture, form the bracing areas and link the clasp to the pink denture base. Process as usual in a pressure cooker.
Using this
method of clasping, often the result is too much retention! A sure way
of controlling the amount of retention is to add it only after the partial
denture is finished and can be fitted on a duplicate model: with a round
burr, cut a small hole in the interproximal areas of the partial; then,
prime the area and fill the holes with the softer mixture, allowing the
material to bulge out and form a plunger. Without using the duplicate
model, place the partial in a pressure vessel and polymerize thoroughly
(20 min.).
Carefully check and adjust the final amount of retention on the duplicate
model, using warm water (not hot!) to ensure the appliance can be removed
without too much resistance at first try-in.
Note:
when finishing an internal clasp, always make sure to relieve the tissue
area around the abutment tooth, with a large round burr, from the inside
of the partial denture, so there is no impingement on the gingival area.
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