On this page I will list the most common problems faced when taking a vinylpolysiloxane impression. Any tips that you may have would be welcomed and added to this page.
Here are some of the problems you may face listed in no particular order.
The retraction cord and hemostatic agents containing ferric sulfate or aluminum chloride poison the catalyst and inhibit the set of the material.
Remove the cord, rinse with water and dry thoroughly.
Unequal amounts of base and catalyst in the final mix.
Bleed one centimeter from the cartridge before placing a new tip.
Hemostatic agent was not completely rinsed from the mouth.
Thoroughly rinse the patients mouth.
Mixing tip was lifted away from the tray while it was being filled.
Keep the mixing tip buried in the material while you are filling the tray.
Air is trapped in the impression material.
Bleed 1 cm of material from the cartridge before placing a new tip.
Poor moisture control.
Rinse and dry the preparation thoroughly after removing the retraction cord.
Apply cotton pellets soaked in hemostatic agent to control excessive bleeding. Rinse and dry thoroughly.
Moisten retraction cord prior to removal.
Replace cotton rolls.
Delay the procedure if the tissue is in poor condition. Make a new qppointment after the tissue has healed.
You have exceeded the working time.
Delay syringing of material until you are completely ready.
Use two Extruders for additional working time.
Make sure that you are using wash material. if you are using medium, try switching to wash material for better flow.
Try using the disposable syringe tips for direct placement in the mouth.
Material is too warm, decreasing the working time.
Store at room temperature (20-23C)
Poor moisture control.
Rinse and dry the preparation thoroughly after removing the retraction cord.
You removed the tray befor the material was completely set.
Allow the material to set for at least 4 minutes.
Time the procedure to allow and extra 1-2 minutes. The tear strength will increase as the material continues to polymerize.
Use Medium for higher tear strength.
Cross contamination of the base and catalyst.
Do not use the original cap. there might be unset material inside. Leave the mixing tip on until the next time you use it.
Bleed 1cm of material before placing a new tip.
Bacteria contamination.
Immerse impression in 2% glutaraldehyde solution for approximately 30 minutes. We recommend the KERR Security System of infection control products sheduled for release in Canada this summer.
The material did not flow and this caused the material to move away from the preparation when using a one step technique.
Insufficient drying time for the adhesive.
Wait 10 minutes before placing material in the tray.
Using another manufacturers adhesive.
Use EXTRUDE adhesive with EXTRUDE material.
Clogged cartridge.
Bleed 1cm of material from the cartridge befor placing a new tip.
You used the wrong tip and pressure built up.
Only use a KERR tip with EXTRUDE material
Hydrogen gas is released from the impression material.
Wait at least 20 minutes before pouring the model in stone.
Unequal amounts of base and catalyst.
Make sure putty scoops are even or cartridges are bled 1cm.
There is a resistance to closure due to the high viscosity of putty creating outward pressure on the sides of the tray. They rebound when the tray is removed.
Use a rigid tray.
The patient closes prematurely befor the tray is in position.
Instruct the patient how to close.
Practice with the patient.
The tray was seated incorrectly causing the patient to bite on the sides or the back of the tray.
Retake the impression.
Use a rigid tray.
Impression tray is held too tightly resulting in rebound when it is removed from the mouth.
Hold the tray motionless until the material is set.
Not enough relief of the prliminary impression if you are using a tw-step putty technique.
Relieve the preliminary impression to allow sufficient room for the wash material.
The impression was moved prematurely before the material fully set.
Allow the material to set for a minimum of 4 minutes before it is removed.
Using mismatched batch codes causes variations in working and setting times.
Check batch codes of base and catalyst. THEY MUST MATCH.
Mixing putty while wearing latex gloves which contain sulfur and inhibits the set.
Wear vinyl gloves or wash hands thoroughly to remove any residue or do not wear gloves while dispensing so there is no contamination.
Contamination from storage with other dental products such as polysulfides or Eugenol. These poison the active ingredient in the catalyst.
Store products in original container, separately from other possible contaminants.
Dispense putty just prior to actual mixing.
Cross contamination of base and catalyst
Dispense putty just prior to actual mixing.
Do not place material back into the jar.
Do not dispense until you are ready to Mix. Vapours can cause contamination.
Incomplete mixing results in streaks in the mixed material.
Mix for a full 30 seconds until it is streak-free.
Out-dated material.
Check manufacturers code dates on the jars.
Mark the boxes when they are received from the dealer.
Rotate your boxes so you use the old material first
Material is too cold.
Store at room temperature(20-23C). DO NOT REFRIGERATE.
Temperature of the material is too high. Perhaps no air-conditioner in the office over the weekend.
Store at room temperature. Refrigerate for approximately 10 minutes to bring it back to room temperature (20-23C)
Mixing putty in the palms of your hands generates too much heat.
Use your fingertips to mix the putty.
Putty is mixed too soon before setting into the tray
Begin mixing just prior to filling and seating the tray.
Using mismatched batch codes.
THE BATCH CODES MUST MATCH.