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SP16- Operative > Inlay/Onlay Preparation > Flashcards

Inlay/Onlay Preparation Flashcards

1
Q

What is the difference between an inlay and an onlay?

A 
Inlay = no cusp missing
Onlay = covers cusp
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2
Q

What are the two types of inlays/onlays?

A
  1. metal

2. esthetic (composite or ceramic)

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3
Q

What are the indications for METAL inlay/onlays? (6)

A
  1. Large restorations
  2. endodontically treated teeth (posterior in particular)
  3. Teeth at risk for fracture (craze lines)
  4. Dental Rehabilitation (rebuilding entire occlusion)
  5. Diastema Closure/Occlusal Plane Correction
  6. Removable Prosthodontic Abutment (rest seat stability)
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4
Q

What are the contraindications for METAL inlay/onlays? (4)

A
  1. High Caries Rate (get them under control first)
  2. Young Patients (large pulp, still growing)
  3. Esthetics
  4. Small Restoration (conservative approach)
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5
Q

The advantages of METAL inlay/onlays include: strength, Low wear, _______, and control of ______.

A

biocompatibility

control contours/contacts (easier)

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6
Q

Why is “chair time/number of appointments” a disadvantage to using METAL inlays/onlays?

A

can’t make gold chairside…need for a temporary restoration

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7
Q

Why is “cost” an issue with METAL inlay/onlays?

A

lab bills

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8
Q

True or False: METAL inlay/onlays are very technique sensitive because you must bevel all the way around the preparation margins.

A

True

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9
Q

Why are “splitting forces” an important consideration with METAL INLAYS?

A

The path of insertion is slightly divergent…could act as a wedge and break off the cusp

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10
Q

What is the conventional degree of divergence for a METAL inlay preparation?

A

4 degrees

6 to 8 would be fine, just make SURE it is NOT converging

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11
Q

What is the preparation depth and width for a METAL inlay?

A
  1. 5 - 2.0 mm wide
  2. 5 mm deep

*do NOT weaken the marginal ridge

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12
Q

What is the purpose of a 40-45 degree Sweep Bevel?

A

reduce microgap leakage

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13
Q

What is the occlusal reduction for a METAL ONLAY preparation?

A

Functional Cusp: 1.2 - 1.5 mm

NonFunctional: 1.0 mm

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14
Q

True or False: Axial wall defects are acceptable for inlay/onlay preparations because they will be filled with cement.

A

FALSE, the creation of an undercut to fill the void would cause the restoration not to seat

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15
Q

What does it mean to “hood” a cusp?

A

to extend the onlay up the ridge to the tip of a cusp without fully encompassing the entire cusp = hold the onlay/tooth together

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16
Q

What are the indications for indirect TOOTH-COLORED inlay/onlays? (3)

A
  1. Esthetics
  2. Large Defects (less shrinkage than direct filling)
  3. Large Previous Restorations
17
Q

What are the contraindications for indirect TOOTH-COLORED inlay/onlays? (3)

A
  1. Heavy Occlusal Forces (bruxism/clenching)
  2. Inability to maintain a dry field (needed for bonding)
  3. Deep subgingival preparations
18
Q

What are the advantages of indirect TOOTH COLORED inlay/onlays?

A
  • improved physical properties
  • variety of materials/techniques available
  • wear resistance
  • reduced polymerization shrinkage (cement still shrinks)
  • support of remaining tooth structure
  • more precise control of contours/contacts
  • biocompatibility and good tissue response
  • increased auxillary support (EFDA can design it)
19
Q

What are the disadvantages to indirect TOOTH-COLORED inlay/onlays?

A
  • increased cost and time
  • technique sensitivity
  • difficult try-in and delivery
  • brittleness of ceramics
  • wear of opposing dentition and restorations
  • short clinical track record
  • low potential for repair (you would have to etch with acid…in their mouth)
20
Q

What are five types of tooth-colored inlay/onlays?

A
  1. Feldspathic porcelain
  2. Pressed Glass-ceramics
  3. Lithium Disillicate
  4. CAD/CAM Leucite Reinforced Glass
  5. Composite Restorations
21
Q

How does a ceramic inlay preparation differ from metal preparation?

A

deeper (2 mm functional, 2 mm central, 1.5 mm nonfxnl)
more rounded
no bevels

22
Q

True or False: Ceramic Inlay/Onlay preparations should exit at a 45 degree angle.

A

False, 90 degrees for strength

23
Q

Why are all internal and external line angles rounded for Ceramic Inlays?

A
  • prevent stress points

- ease of placement/fit

24
Q

What type of rotary instrument is typically used for ceramic inlay or onlay tooth preparations?

A

diamond

(for example: there is a diamond bur that measures 1.5mm wide and 2.0mm tall which gives perfect dimensions when used in the central groove)

25
Q

True or False: Ceramic Inlays & Onlays are more conservative than metal.

A

False, need a bulk of ceramic material for strength!

26
Q

Why must exit angles for Ceramic inlays/onlays be close to 90 degrees?

A

ensures bulk of ceramic at the margins

27
Q

True or False: A ferrule margin must be placed for adequate retention of Ceramic onlays.

A

False, avoid ferrule margins

28
Q

What is the ideal wall taper for ceramic inlays/onlays?

A

6-8 degrees

metal inlays ~4

29
Q

Why must you avoid over-tapering the occlusal walls?

A

leads to thinner occlusal margins and increased margin stress as the margin approaches the cusp

30
Q

True or False: Ceramic inlays & onlays should have bevels at the margin.

A

False, should have “rollercoaster margins” that smoothly transitions

31
Q

The occlusal preparation for ceramic inlays & onlays should be smooth with broad rounded corners that are ______ in diameter.

A

1 mm

32
Q

The box should be a minimum reduction of ______ axially and _______ facial lingually.

A

1.5 mm

2 mm

33
Q

True or False: Always onlay cusps that are at risk for fracture.

A

True

34
Q

What is the desired ceramic thickness?

A

2 mm

35
Q

After excavating the caries, how is it determined whether or not a cusp is preserved?

A
  • thickness of axial wall
  • internal stress cracks(?)
  • location of crack
  • color
  • holding cusp (?)
  • Excursive interferences (?)
36
Q

True or False: If a functional cusp is undermined, it must be onlayed.

A

True

37
Q

True or False: If a nonfunctional cusp is undermined, it must be onlayed.

A

False, could place GI

SP16- Operative (8 decks)

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