Module 4 Crowns and Bridges Part II

What are the two appointments for crown and bridge procedures?

Preparation & final impression, and final cementation.

What are guidelines for selecting a shade?

Teeth must be wet, use natural light, moisten shade guide, and record shade ID.

What is included in pre-op impressions (preliminary)

• Provisional template,

• bite registration,

• opposing arch impression

When are bite registration and opposing arch impressions not needed in prelim?

When using a triple tray.

What are the steps in tooth preparation?

• Remove decay,

• reduce height/contour,

• place meds if needed,

• place retention aids (core buildup, retention pins/post)

• Finish prep with rotary instruments.

What are chamfer margins? (type of prep)

A tapered finish line at the cervical area of the prep.

What are shoulder margins? (type of prep)

A flat, wide margin used for cast restorations.

What is a beveled margin?(type of prep)

A margin with an angled cut inside the prep for better retention.

What is a core buildup used for? (BU)

Restores missing tooth structure to support a cast crown and improve cementation retention.

What materials can be used for core buildup?

Light-cured composite, reinforced glass ionomer, existing amalgam.

When is a core buildup needed?

When vital teeth have little crown structure remaining.

When are retention pins used?

To add strength to core build-ups when significant structure is missing.

When are retention pins placed?

Before the core buildup material. Goes into dentin

What determines pinhole location?

Pulp location and crown design.

When is a post and core used?

When a tooth is non-vital and has had a root canal.

What materials are posts made of?

Titanium or titanium alloys; cast posts may be used (acrylic).

How is a post cemented?

Deeply into the nerve canal before core buildup BEFORE buildup.

What is gingival retraction used for?

• Temporarily displacing/moving tissue,

• widening sulcus,

• controlling bleeding,

• exposing margins for accurate impressions.

What are the types of gingival retraction?

Mechanical, chemical, and surgical.

What is mechanical retraction?

Non-impregnated cord physically retracting gingiva.

What is chemical retraction?

Hemostatic solutions or impregnated cord causing tissue shrinkage and bleeding control.

What agents are used for chemical retraction?

Hemostatic solutions, aluminum chloride, and Expasyl.

What is surgical retraction?

Removal of gingival tissue with a blade or laser.

What are the types of packing cord?

• Plain (untwisted) ,

• twisted, and

• braided;

all in multiple thicknesses.

What is impregnated cord?

Cord containing astringent vasoconstrictor like epinephrine.

Who cannot receive epinephrine-impregnated cord?

Patients with heart disease, hypertension, hyperthyroidism, or diabetes.

Who can perform gingival retraction in Arizona?

Only the dentist; assistants are NOT obligated to place retraction cord.

What is required for a final conventional impression?

• Dry tooth,

• light-body material placed by dentist,

• assistant loads tray with heavy-body,

• dentist seats tray.

What is required for a digital final impression?

Digital scanner; dental assistants in AZ may take digital final impressions.

What is provisional coverage?

Protective temporary crown placed after prep and final impressions.

What is the purpose of a provisional?

Restores and maintains function and esthetics until the final crown is placed.

What is a lab prescription?

A detailed written form sent with impressions to the dental lab.

What must be included in a lab prescription?

• Patient name,

• prosthesis type,

• shade,

• alloy,

• pontic type (if bridge),

• date needed,

• special instructions,

• dentist info & signature.

What does the lab technician do?

Fabricates the casting based on the lab prescription.

What happens at the delivery appointment?

• Review the returned case from lab the day before

• Provide anesthesia if needed

• Remove temporary, clean tooth,

• try-in crown,

• adjust occlusion and contacts, polish,

• cement,

• take final X-ray.

Why is an X-ray taken after cementation?

To ensure complete seating and no excess cement remains.

What oral hygiene is recommended after fixed prosthetics?

Brush and floss daily; for bridges, use floss threaders to clean under pontic.