Difficulty: Moderately Challenging
Things You'll Need:
- Alginate impression material/water and teeth arch tray
- Cotton rolls
- Petroleum jelly
- Self-curing acrylic resin (liquid and powder)
- Mixing container
- Small spatula
- Acrylic-trimming bur/low-speed handpiece
- Pumice paste
- Lathe and sterile white rag wheel
- Zinc oxide-eugenol or intermediate restorative material
- Articulating paper
Make a Temporary Crown
Mix alginate material, fill tray and take an impression of the arch of the patient's tooth needing the temporary crown before the tooth is prepared. Once the dentist prepares the tooth, place cotton rolls around the prepared tooth to maintain moisture control and lightly apply petroleum jelly to the tooth.
Place the liquid of a self-curing acrylic resin in a mixing container--10 drops per unit is recommended. Quickly dispense the appropriate shade of self-curing powder into the liquid until the powder is saturated, and mix with a small spatula.
Set the mix aside for one to two minutes until the resin reaches a doughy consistency. Gently dry the area of the tooth on the alginate impression to receive the temporary crown. Remove the resin from the mixing container with the spatula and place it within the area of the prepared tooth on the alginate impression.
Place the acrylic-loaded impression back into the patient's mouth on the prepared tooth, and remove the tray after about three minutes. Carefully remove the temporary crown from the alginate impression and place it onto the patient's tooth.
Mark the marginal border (edge of the gum surrounding the tooth) and contact points of the temporary crown with a pencil. Trim the acrylic resin crown within 1 mm of the gum shoulder of the prepared tooth with an acrylic bur in a low-speed handpiece.
Check to make sure the temporary crown fits correctly in the patient's mouth, and adjust as necessary. Take the crown to the laboratory, and polish it with a sterile white rag wheel and pumice on a laboratory lathe.
Temporarily cement the crown with zinc oxide-eugenol or intermediate restorative material. Check to make sure the crown fits correctly with articulating paper; if necessary, the dentist will have to reduce the size with an acrylic-trimming bur.
Tips & Warnings
After taking the alginate impression, disinfect it and keep it moist until needed so it won't become dry and distorted.
Don't let the acrylic resin mix cure beyond one to two minutes or else it will become too hard to use.
Cover the liquid self-curing acrylic resin container immediately after using it, as it can evaporate easily and is very explosive.
When trimming and polishing the temporary crown, wear safety goggles.