lab finals

Why is ZOE contraindicated under composite restorations?

Eugenol interferes with the polymerization of composite resin.

Can ZOE be used under amalgam restorations?

Yes.

Why is a mixing pad used instead of a glass slab for GI?

To avoid scratches on the glass, prevent color contamination, and because mixing pads are more compatible with GI.

What may happen if GI is mixed on a scratched glass slab?

The consistency and appearance of the GI may be affected.

Why is cocoa butter or petroleum jelly applied on GI restorations?

To prevent dehydration and chalky appearance.

What happens when GI becomes dehydrated?

It becomes chalky.

What are the two forms of amalgam alloy?

Pellet form and capsule form.

Which amalgam form is premeasured?

Capsule form.

Which amalgam form requires estimation of mercury?

Pellet form.

What does a powdery amalgam mixture indicate?

More mercury is needed.

What is used to remove excess mercury from amalgam?

Squeeze cloth.

What indicates that the amalgam mixture is properly triturated?

The amalgam sticks together and adheres to the capsule wall.

What is mulling?

Kneading or rolling amalgam into a cohesive ball.

Why is amalgam overfilled during condensation?

To remove the mercury-rich surface during carving.

What type of condenser tip is preferred for amalgam condensation?

Serrated tip.

Name two amalgam carvers.

Discoid-cleoid carver and diamond amalgam carver.

In a matrix band, where should the open portion face?

Toward the gingiva.

In a matrix band, where should the base be positioned?

Toward the gingiva.

In a matrix band, where should the apex be positioned?

Toward the contact area.

Name different types of matrix bands.

Boomerang, end-slot, and side-slot matrices.

What is the deepest area marked on the cast?

Mucobuccal fold.

Which tissue areas should be relieved on the cast?

Tissue attachments.

What landmark is located posterior to the maxillary tuberosity?

Hamular notch.

Which papillae should not be marked directly on the cast?

Incisive papillae.

What are the two small depressions near the vibrating line called?

Fovea palatinae.

Where is the vibrating line located?

At the junction of the hard and soft palate.

How far from the fovea palatinae is the vibrating line located?

Approximately 2 mm anterior.

What may happen if the denture base is overextended posteriorly?

The denture may become dislodged.

What type of tray is used for border molding?

Individual tray.

What material is commonly used for border molding?

Green stick compound.

How far from the outer line should the final impression tray be outlined?

About 1 mm short of the outer line.

What is placed within the inner line of the cast?

Pink wax spacer.

At what angle should the tray handle be positioned?

Approximately 45 degrees.

How can retention be provided in an individual tray?

By using green stick or creating retention holes.

How large should retention holes be?

Small but sufficient to retain the impression material.

What is the purpose of the double line on the cast?

To guide fabrication of the individual tray.

What are the two types of acrylic resin according to curing method?

Self-cured and heat-cured acrylic resin.

Which acrylic resin is activated chemically?

Self-cured acrylic resin.

Which acrylic resin requires heat for polymerization?

Heat-cured acrylic resin.

In what type of container is acrylic usually mixed?

Opaque or amber-colored jar.

During which stage should acrylic resin be manipulated?

Sticky stage.

What device is used to process denture bases during flasking?

Bantam flask and pressor.

What is the purpose of a separating medium?

To prevent acrylic from adhering to plaster.

What sheet is placed during trial closure?

Cellophane sheet.

Why is cellophane used during packing?

To facilitate removal of excess acrylic.

Why should some excess acrylic be left after trial closure?

For subsequent grinding and finishing.

Approximately how long does plaster take to set?

About 30 minutes.

Why should protruding plaster not be removed immediately?

It serves as an indicator that the plaster has set.

What happens to an indelible pencil mark when wetted?

It turns into ink.

How is the vibrating line clinically identified?

The patient is asked to say "Ah."

What technique is commonly used when adding self-cure acrylic?

Salt and pepper technique.

What should be practiced at home for the practical examination?

Fabrication of an upper individual tray with double lines.