CUSPAL COVERAGE INDIRECT RESTORATIONS

Question 1

4 indications for a cuspal coverage restoration?

Answer 1

1.** Preserve the integrity of a weakened tooth**.
2. Reinforcement of the tooth.
3. Less cuspal deflection and thus BETTER PROTECTION of remaining tooth tissue.
4. Correct occlusal discrepancies/ part of the restorative reorganisation of the occlusal scheme.

Question 2

What did Aqualino et al say about cuspal coverage in root treated teeth? What type of study was this?

Answer 2

• Endodontically treated teeth not crowned after obturation were lost 6 TIMES GREATER RATE than teeth crowned.
• Retrospective cohort study.

Question 3

4 types of cuspal coverage restorations?

Answer 3

• Onlays.
• Inlays with cuspal coverage.
• 3/4 crowns.
• 7/8 crowns.

Question 4

6 Factors that determine the decision on whether a cuspal coverage vs an intracoronal restoration will be used?

Answer 4

1. Whether the tooth is endodontically treated.
2. The amount and distribution of tooth structure remaining.
3. The type and amount of load applied on the tooth during function.
4. The parafunctional habits of the patient.
5. The aesthetic demands of the tooth.
6. The knowledge and experience of the dentist.

Question 5

What did a systematic review by Afrashtehfar et al find regarding the failure of single unit restorations?

Answer 5

• Failure rates of treatments may depend on the AMOUNT OF REMAINING TOOTH STRUCTURE and TYPE OF TREATMENT.
• Post retained crowns –> more favorable in teeth with 1 to 2 remaining coronal tooth walls.
• Post free crowns –> superior when greater tooth structure was available.
• Restorations in teeth without ferrules had such high failure rates that other Tx options should be considered.

Question 6

What is an inlay?

Answer 6

Intracoronal restoration without cuspal coverage

Question 6

What is an onlay?

Answer 6

Replace tooth tissue including cusps (extracoronal).

Question 7

2 indications for an onlay?

Answer 7

1. Difficulty in achieving correct occlusion, contour and contact point with direct restoration.
2. Repeated fracture of a directly placed restoration.

Question 8

A common indication for an onlay?

Answer 8

Endodontically treated posterior tooth that requires cuspal protection.
- Want to preserve some BUCCAL and LINGUAL tissue to help retain a CORE and avoid the need for a post (crown may lead to this).

Question 9

5 benefits of gold as an onlay?

Answer 9

• High strength.
• Ductile.
• Can be cast accurately.
• Can be highly polished (less abrasive to opposing dentition).
• Need less occlusal and axial reduction

Question 10

4 features/ preparation requirements for a gold inlay?

Answer 10

• Near parallel walls/ NON UNDERCUT walls.
• Cuspal coverage (1mm) with functional cusp bevel.
• Bevel marginal finish.
• Mini shoulder finish buccally in lower arch.

Question 11

What is the method of manufacture for gold inlays and onlays?

Answer 11

Lost wax technique.

Question 12

What do gold restorations gain most of their retention from?

Answer 12

THE CAVITY SHAPE - need NO UNDERCUTS and NEAR PARALLEL PREPARATIONS.

Question 13

What is the major advantage of inlays and onlays?

Answer 13

Preservation of some tooth structure to retain a core.

Question 14

How can we ensure the preparation for a gold inlay is non undercut (2)?

Answer 14

• Use tapered burs.
• Block out undercuts using GIC or composite.

Question 15

5 advantages of 3/4 crown compared to intracoronal and full coverage restorations?

Answer 15

1. Protects the cusps (ct intracoronal).
2. Reduces sound tooth removal (ct Full coverage).
3. Reduced amount of restorative material required, ex. Au (ct full coverage).
4. Easier to inspect margins (ct subgingival full coverage).
5. Potentially better aesthetics buccally (ct. full coverage).

Question 16

3 disadvantages of 3/4 crown compared to intracoronal and full coverage restorations?

Answer 16

1. Complex preparations for clinicians.
2. Complex restorations for technician.
3. Expense (ct intracoronal).

Question 17

How do you prepare tooth for a 3/4 crown?

Answer 17

• Similar to FGC EXCEPT:
• Proximal groove.
• Occlusal offset.
• Buccal Bevel

Question 18

What are the3 functions of the proximal groove in a 3/4 gold crown?

Answer 18

• Retention.
• Resistance.
• Structural durability.

Question 19

What is the function of the occlusal offset in the 3/4 corwn?

Answer 19

Structural durability.

Question 20

What is an occlusal offset?

Answer 20

Occlusal offset groove extends between the mesial and distal grooves.
- Produces ARCH OF THICKENED GOLD BUCCALLY, giving the casting STRENGTH where the 4th (buccal) wall of the crown.

Question 21

What is a luting cement? (what dental material). When is it used? Give 2 named examples.

Answer 21

• Resin modified GIC or GIC.
• Used for ALL METAL-BASED RESTORATIONS unless there is not enough retention and resistance form.
• Rely X luting, Poly F.

Question 22

2 named examples of luting cements?

Answer 22

• Rely X luting.
• Poly F
  (both are RMGIC).

Question 23

What is a bonding cement? (what dental material). When is it used? Give 2 named examples.

Answer 23

• Adhesive resin composite.
• Used for METAL BASED RESTORATIONS when the dentist judges the cavity does not have good retention and resistance.
• Panavia (MDP allows bonding to metal and tooth).

Question 24

Name a bonding cement?

Answer 24

• Panavia
  (adhesive resin composite).

Question 25

What does Panavia contain that makes it advantageous?

Answer 25

MDP monomer allows bonding to metal as well as tooth structure.

Question 26

What is the advantage of an onlay ct a full coverage restoration?

Answer 26

Weakened tooth structure can be protected without further extensive tooth removal.