DENTAL Materials

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DENTAL Materials

• Lesson 5 Hydrocolloid

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1. INGREDIENTS

• Water- 80-85
• Agar-agar- Seaweed- 15
• Borax- sm amt for strength and inhibit set
• Potassium sulfate- 2, compitable with stone
• Fillers and coloring agents

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2. Uses and Advantages

• Final impression for removable prosthesis
• Impression for fixed castings
• To duplicate models

• ACCURATE
• Inexpensive
• Hydrocolloid changes physical state from a solid
  (gel) to a liquid (sol) and back with temperature
  changes.REVERSIBLE
• No CHEMICAL REACTION

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3. Forms

• Tubes of heavy or regular body for tray
• Carpules of syringe material

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4. Supplies

• Tray material
• Syringe material and syringe
• 2x2 to wipe smear layer on tray
• Water cooled tray and hose
• Hydrocolloid conditioning unit

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5. Conditioning unit

• 1.Boil- 212F for 10 minutes, can reboil 4 times
• 2.Store- 150F 5 days
• 3.Temper- tray material only, 115F for 5 min
• In mouth in water cooled tray for 5 min

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6. Gingival Tissue

• A retraction cord or ring, often soaked in a
  hemostatic agent, is packed into the sulcus with
  a gingival retraction instrument, prior to taking
  the impression. One or two cords may be used.

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7. Syringe Material

• The syringe material is not tempered. When the 5
  minutes is up for tempering the tray material,
  the syringe material is loaded into a syringe and
  passed to Dr. just before wiping smear layer,
  connecting hose and passing the tray.

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8. The Tray

• The tray is removed from the tempering bath after
  5 minutes. Wipe the top smear layer with a 2X2 so
  that the syringe material will adhere to the tray
  material. This also removes excess water. Hook
  the water hoses to the tray and insert. Flip
  water switch on to begin the cooling once the
  tray is seated.

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9. Remove the tray

• A snap technique, just like alginate, is used
  to remove the tray. Always protect the teeth of
  the opposing arch with your other hand.

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1011. Pour UP

• Pour up ASAP with Die Stone (22/100) or wrap in
  wet towel for a short time. Syneresis (drying
  out) or Imbibition (swell with fluid) can occur
  if not handled correctly.
• Separate when set so that the surface of the
  gypsum is not chalky and weak.

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THE END