OPTEC- inlays/onlays/veneers

Question 1

Compare inlays and onlays?

Answer 1

Inlays are lab made intra-coronal restoration (do not cover the cusp tips)

Onlays are extra-coronal restorations (that cover the cusp tips)

Question 2

Why do we use inlays instead of direct restorations?

Answer 2

They can be created using better materials such as gold, ceramic or porcelain.

You can also get better margins with these as they are premade to fit the cavity prep perfectly)

Question 3

How do we prepare a ceramic inlay?

Answer 3

isthmus width-1.5-2mm

Depth 1.5mm

Proximal box -1.5-2mm

Margin- 1mm shoulder or chamfer.

Cavosurface margins- no bevel

Question 4

How do we prepare a gold inlay?

Answer 4

Isthmus width - 1mm

Depth-1.5mm

Proximal box-1mm

margins- 0.5mm chamfer

Cavosurface margin (15-20* beveled at the top 1/3 of the isthmus wall)

Question 5

Name and discuss this type of margin

Answer 5

This is a shoulder margin, it leaves a right angle at the gingival margin.

Question 6

Name and discuss this type of margin?

Answer 6

This is a chamfer margin, it leaves a ski slope at the gingival margin.

Question 7

When would we use an onlay?

Answer 7

When

• There has been occlusal tooth surface loss.
• The remaining tooth surface is weak.
• To replace pre-existing large restorations.
• High strength restorations are needed.
• Significant tooth recontouring is required (this is much easier to do outwith the mouth)

Question 8

How is a porcelain onlay prepared?

Answer 8

Occlusal reduction:

• Non-working cusps (1.5mm)
• working cusps (2mm)

Proximal box- 1.5-2mm

Gingival Margins- 1mm (Shoulder or chamfer)

Cavosurface margin- No bevel.

Question 9

Which cusps have a greater occlusal reduction and why?

Answer 9

The working cusps have a greater occlusal reduction because they are subjected to more force.

Question 10

Compare the material options for a temporary restoration.

Answer 10

GI- this requires removal which could alter the shape of the preparation.

Protemp

Kalzinol- this can affect the bond if you are using the resin based cement for your base.

Question 11

Why is a temporary restoration used after the first appointment?

Answer 11

Because both inlays and onlays need to be sent away to the lab to be made using an impression of the tooth prep.

So a temporary restoration is used until the indirect restoration is produced.

Question 12

What is a veneer?

Answer 12

A thin layer of cast ceramic that is bonded to the labial or palatal surface of the tooth.

Question 13

When would you use a veneer?

Answer 13

To improve aesthetics

Reduce diastemas or proximal spaces

To change the teeth shape or colour

Correction of peg-shaped laterals.

Aligning the labial surfaces of instanding teeth

Masking discoloration.

Question 14

What would contra-indicate the use of veneers?

Answer 14

• Poor oral hygeine
• High caries rate (interproximal caries or unsound restorations )
• Gingival recession
• Root exposure.
• high lip line (the veneer margin would be obvious)
• • Severe discoloration (veneer may not mask it)
• If extensive prep is needed (if >50% of enamel surface is lost- the bonding will not work.)

Question 15

What should you use when preparing the tooth for a veneer?

Answer 15

Putty template, to see how much of a reduction you have made.

Depth cuts- to give us a guide of how far you should be cutting into the tooth.

Question 16

How do you prepare a tooth for a veneer .

Answer 16

Cervical region- 0.3mm reduction & chamfer margin.

Labial surface- 0.5mm reduction (slight bevel towards the incisal edge)

Incisal reduction of 1-1.5mm

Question 17

Why should you not need a temporisation for the veneer?

Answer 17

As the preparation should remain in enamel .

Question 18

How do we prepare a gold Onlay.

Answer 18

Occlusal reduction.

• Non-working cusps- 0.5mm
• Working cusps- 1mm

Proximal box- 1mm

Gingival margin- 0.5mm chamfer

Cavosurface margin- 15-20* on the upper 1/3 of the isthmus wall