Full metal crown lost wax technique

Описание: Step 1: Pouring the impression.
a-Mix yellow stone with adequate amount of water in order to obtain the desirable consistency.
b-Yellow stone is poured on an already made A-silicone impression (target: prepared tooth).
c-Vibrator is used in order to get the details, and eliminate air bubbles.

Step 2: Pins placement.
a-The pin is placed at the center of the prepared tooth from the bottom, adequate depth in stone is required.
b-2 other pins: one mesial, and other distal are present for stability of the stone (once placed on gypsum), in addition to a pin on the other side of the stone.
c-All the pins should be parallel.
d-Separating medium (soap solution + water/Vaseline) are placed on the stone.

Step 3: Pouring gypsum in base former, and cast placement.
a-Powder and water should be mixed to obtain adequate consistency (cream like).
b-Shake the base former, to eliminate air bubbles.
c-Place the cast (with pins) on the base former containing the gypsum.
d-Trim the final product.

Step 4: Splitting.
a-Using a suitable saw, then cut proximally to the prepared tooth.
b-cutting should be parallel, with no distortion of finish line on either sides.

Step 5: Ditching.
a-Using appropriate bur, start ditching.
b-Do not touch the finish line, the main target is to expose it, and smoothening the margin.

Step 6: Waxing the prepared tooth.
a-Place separating medium on the die (e.g. Vaseline).
b-Gently, place the wax on the tooth, and start anatomy building.
c-Carving the wax for esthetic, and anatomic considerations.

Step 7: Sprue placement.
a-The main purpose of the sprue is allowing metal passage.
b-Place the sprue, and cover it with wax in order to sustain it in place.

Step 8: Placement in investing ring.
a-Place the sprue attached to the wax, to a rubbery crucible former.
b-Placement of the investing ring before pouring the investment material is crucial.

Step 9: Add investment material.
a-Special type of gypsum is poured slowly within the ring containing the wax, and sprue.

Step 10: Burnout.
a-This step is important in order to melt the wax, and remove it.
b-Centrifugal casting machine: used to melt the wax, and push it in the left cavity (temperature of metal reaches 1400 degree Celsius).
c-Casting: pouring the metal in the left cavity after burnout.

Step 11: Finishing and polishing the crown.
a-Use appropriate burs, and discs for finishing, and rubber wheels for polishing.