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ARMAMENTARIUM:
- Choose a Pro-flex strengthener thickness. Comes in .060, .080 and .100.
- Dental Resources Bulk Reduction Scissors.
- Pro-flex Overlay Resin. Choose shade of choice — four shades available: light, medium, dark and ethnic.
- Normal equipment for processing acrylics — flasks, burs, lathes, etc.
- Pro-form dual-chambered vacuum machine for forming base.
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TECHNIQUE FOR BASE STRENGTHENER
- First, make two accurate duplicate models of the master cast. The first duplicate will be used to fabricate the base strengthener; the second will be the working model for processing the Pro-flex overlay material. The finished appliance will be delivered on the master cast.
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NOTE: Before duplicating the master cast, you will want to —
- add post dams and beads as necessary;
- block out any severe undercuts; and
- check model for desired height of contour.
- Prepare the first model for vacuum forming by reducing its height from the incisal edge to the base and reducing the basal area as much as possible (a horseshoe shape works great for mandibular cases).
- Using a sharp pencil, draw a finishing line on the prepared model. Be accurate, especially around the teeth and clasp abutments because this will be your guide line when trimming base from the model.
- Depending on the amount of desired flex and the size of the partial, choose the appropriate thickness of the Pro-flex strengthener. The .060 is the thinnest and will provide the most flex. The .080 is the medium thickness and is the standard used by the folks at Pro-flex. The .100 is the thickest and will give you the stiffest appliance. The thickness of the strengthener may have to vary from case to case.
- Vacuum form the strengthener onto the first model. Make sure it is adapted completely to the model. Use a cold, wet tissue to help adapt strengthener material to model while vacuum is on.
- Use DR Bulk Reducing Scissors or Wheel Saw to remove the excess strengthener from the stone model. Or you may want to use a large white stone to reduce both the strengthener material and the stone model all at one time. Do not reduce the strengthener all the way to the finishing line. Save this reduced model — it will be used later in the finishing process.
- Working on the model, use a finishing bur to further reduce the strengthener to the finishing line around the teeth and clasp abutments. Remove strengthener from model and complete finishing. The base of the Pro-flex partial (appliance) is now completed. Proceed to the overlay instructions for finishing of the appliance.
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Fit the strengthener you have fabricated onto the second duplicate model.
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Wax up the case onto the base strengthener and provide the doctor with a bite block or try-in as needed. Be sure NOT to wax clasps or areas of the partial that need to flex during the try-in. The wax will break off from these flexed areas.
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After try-in, if the bite is not correct, proceed to finishing. If it does not fit or if the doctor has modified the study case, a new base strengthener will have to be made.
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When the case is ready for final processing and finishing, wax up the final case. Be sure to cover the entire base strengthener with wax. Remember to add extra wax above the clasp areas to ensure the easy removal of the strengthener from the flask
for cleaning purposes (it creates a clear path of removal). Also, care should be taken NOT to wax the case too thin. The waxed Pro-flex partial is now ready to be invested using standard presspacking and flasking techniques.
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Submerge flask in boiling water for five to seven minutes. Open flask, remove strengthener from model and clean both strengthener and inside of flask. Clean thoroughly with detergent and hot water. Rinse with clean boiling water.
Note: If strengthener does lose some of its shape after boiling, place back in the flask and submerge the flask half in clean hot water for about 10 seconds. Then use a clean towel to press the strengthener back into position on the case.
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Although Proflex resin chemically bonds with acrylic teeth, mechanical retention such as diatoric holes should be drilled in teeth to ensure optimum retention. This is due to the flexible nature of the final appliance. It is especially true with IPN and composite teeth.
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Add a bonding agent for maximum bond between NFC resin and teeth.
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Important --- Store NFC resin (both powder and liquid)
in refrigerator and remove JUST prior to mixing and pouring. This will help slow down the reaction
and make the material easier to work with.
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Remove the NFC resin from the refrigerator. Mix two parts of powder to one part of liquid. Use the
clear measuring cup for liquid (1/2 oz.) and add to powder (1 oz.) in the blue measuring cup. Mix
thoroughly as quickly as possible for 10 seconds. Pour small amount of resin into an additional
mixing cup (second container) for later use. Cover both containers with cellophane.
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You are now ready to pack. Remove the strengthener from the model and paint the side receiving the NFC
resin with the NFC liquid, it acts as a bonding agent. Keep the strengthener moist with NFC liquid
during the entire packing procedure. Note: Avoid getting the NFC liquid on the tissue side of the
strengthener.
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The NFC resin will be ready to pack in about 5 minutes. Set an accurate timer and remember the resin
gets to an initial set QUICKLY!!!
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Using cellophane or wet fingers, put all the NFC resin from the first container into the flask. Use
cellophane between the resin and the model and close flask for a quick trial pack. Almost immediately,
open the flask and remove cellophane.
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Put the wet strengthener back on the model. Add the rest of the NFC resin to the flask and close. Note:
On upper cases, add the extra resin from the second container directly into the plate area to avoid
trapping air in the palate.
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Put flask in a clamp and cure for 60 minutes at 125° to 130° F. DO NOT CURE AT TEMPERATURES
ABOVE OR BELOW THIS RANGE.
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After de-flasking, we recommend warming the partial for 15-20 seconds in 160° water. This will help
remove the partial from the model. Finish the partial using standard acrylic burs, stones, disks and
techniques.
Important Helpfull Hints: Returning the partial back to the first duplicate model that was saved, can aid
in finishing the partial around the teeth and clasp abutments.
- Final polish as you would a normal partial. A final high shine can be accomplished with a buffing wheel, light pressure and a little water.
- Check accuracy of the partial on the master model. Note: All Proflex appliances are designed to work best at body temperature and should be warmed before insertion.
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