Inlays And Onlays

Question 1

What is inlays and onlays/ whats it about

Answer 1

. Indirect restorations
• Processed outside of the mouth – require an impression
• Amount of coronal tooth structure removed due to full coverage crown preparation = 60- 70%
- 40% in the case of occlusal onlay preparation

Question 2

What’s the advantages of inlays and onlays

Answer 2

• Improved properties of indirect composite vs direct composite
• Less risk of pulpal damage compared to full crown prep
• Supra-gingival finishing lines = better plaque control
• Retention and resistance form less of a problem
• Improved marginal integrity

Question 3

What are the indications for inlays and onlays

Answer 3

• Volume of tooth needing to be replaced:
ØInlays: small to moderate lesions;
ØOnlays: if already wide isthmus; premolars with no intact marginal ridges; cuspal
replacement/protection

• History of direct restoration failure
• Cuspal protection e.g. following root canal therapy
• Patient preference
• Compliant patient – low caries rate, good OH

Question 4

contraindications/ requirements for inlays and onlays

Answer 4

NOT suitable as partial denture retainer
onlays require intact facial/lingual surfaces

Question 5

Longeivity of inlays and onlays

Answer 5

Ceramic inlays 12.7 years not as good as MOD inlays (20.6) and metal inlays, the MOD and metal similar to crowns

Question 6

Composite (better) inlays vs ceramic inlays/onlays

Answer 6

• Cost
• Aesthetics
• Staining resistance
• Try-in difficulties
• Polishing ability when cemented
• Repair
• Bond strength
• Wear capabilities
• Biocompatibility

Question 7

Preparation principles

Answer 7

• Slightly divergent preparation
• Less retention and resistance form
required – relies on adhesion from luting
cement
• Sharper line angles for gold/metal inlay
or onlay preparations
• Softer line angles for composite or
ceramic inlay or onlay preparations
• Avoid contact of cavo-surface angles
against opposing cusps
• Impression with PVS

Question 8

Metal inlay/onlay preparations

Answer 8

• Usually softer gold alloy, however, etchable base metal alloys may be
used if bonding effect is desired
• Narrow isthmus to minimise stress in the surrounding tooth structure
(1/4 of intercuspal distance)
• Isthmus depth = 1.5mm
• Isthmus should avoid occlusal contact areas
• Inlays for premolars - should have one intact marginal ridge,
otherwise occlusal coverage onlay required
• Inlays result in wedge-effect and risk fracture of unsupported cusp;
also risk cement disruption and microleakage

Question 9

Ceramic and composite inlays/onlays IPS e.max preparations general guidelines

Answer 9

Follow the preparation guidelines and use the minimum layer thickness

Question 10

All ceramic ips emax

Answer 10

No angles or edges
Shoulder preparation with rounded inner edges and/or chamfer preparation

Question 11

CADCAM fabricated restorations ips emax

Answer 11

Incisal edge of preparation should be at least 1mm to allow optimum milling of the incisal area during CADCAM processing

Question 12

Ips emax inlay/onlay

Answer 12

Preparation margins are not in areas of static or dynamic antagonist contacts
Preparation depths at least 1mm and width of isthmus at least 1mm in the tissue area
Proximal box has slightly divergent walls and angle 100-120 degrees between proximal cavity walls and proximal cavity surfaces
Avoid marginal ridge contacts in inlay
Round internal edges in order to prevent stress concentration in the ceramic material
Do not prepare slice cuts or feather edges
At least 1mm space in cusp areas for onlays

Question 13

Steps in prepping onlay/inlay

Answer 13

Open the cavity
Proximal extension
Proximal box preparation
Smooth cavity walls and proximal boxes

Question 14

Temporisation materials

Answer 14

Temphase
Kalzinol
Fuji II/IX

Question 15

• I haven’t inlciuded partial crowns because its not on the LO

Question 16

Haven’t included temporisation techniques because it looks over complicated and a waste of time

Question 17

Failures with inlays and onlays can be … or … and what are they

Answer 17

Biological…
Endodontic complications
Tooth and/or root fracture
Hypersensitivity
Caries

Technician…
Crack/chipping
Core failure
Poor marginal integrity
Loss of retention

Question 18

For ceramic inlays/onlays survival?

Answer 18

Is about 90 percent at 10 years

Question 19

Top reasons for failure of ceramic restorations

Answer 19

fracture of the ceramic
marginal discoloration
endodontic complications

Question 20

General principles for onlay/inlay preparation

Answer 20

Preserve as much useful tooth structure as possible
Protect the tooth structure that remains
Control the loads upon the restoration and tooth

Question 21

Restorations can be

Answer 21

Direct at chairside or indirect ie lab made

Question 22

General considerations for deciding to restore with plastic or indirect restorations

Answer 22

Status of the dental pulp
Nature of the occlusion
Wishes of the patient e.g. financial
Isthmus width

Question 23

Isthmus width…

Answer 23

the width of the cavity in the isthmus is less than 1/3 of the width of the intercuspal distance then the tooth is suitable for a plastic restoration.
if the width is between 1/3 and ½ of the intercuspal distance then the tooth is suitable for either a plastic or indirect restoration.
if the width is greater than 1/2 of the intercuspal distance then an indirect restoration is the treatment of choice.

Question 24

General stuff for inlays and onlays

Answer 24

These are restorations which are processed outside of the mouth prior to fitting intraorally

Historically gold was the material of choice but now modern attitudes for aesthetics have seen preference for tooth coloured materials

Question 25

Differences in preparation for plastic restoration vs indirect onlay/inlay

Answer 25

A plastic filling (such as amalgam) will require a preparation which design features must include resistance and retention form but

An Inlay/onlay is retained within the tooth by use of adhesive cements and therefore the preparation shape will have different features.

Question 26

Indications for onlays/inlays

Answer 26

Low caries rate
Good oral hygiene
Cuspal coverage - onlays
weakened teeth
root filled posterior teeth
previously heavily restored teeth
Repeated fracture of a directly placed restoration
Expected difficulties in achieving an acceptable contour, contact point or occlusion with a direct restoration

Question 27

What’s important structurally?

Answer 27

For dentine to be remaining at the base of the cusps

Question 28

Fitting techniques for onlays/inlays- emax

Answer 28

Prep- see flashcard for this
Then construct a temporary made out of Temphase, Kalzinol or Fuji II or IX
Cementation-
remove the temp and clean tooth with a polishing brush, + (oil and flouride free paste)
Try in permenant restoration, check shade, fit occlusion
Use the Multilink Automix try in paste for esthetic inspection-wash off and dry
Etch with IPS cermic etching gel- wash off and dry
Monobond plus and dry
Isolation with rubber dam and clean with polishing brush and oil free and flouride free cleaning paste
Mulitlink primer disperse with air
Syringe in multilink automix onto restoration and seat onto tooth and apply pressure
Remove excess cement
Use ‘liquid strip’ (Air block) to prevent oxygen inhibition
Light cure all cementation joints
Remove liquid strip
Proximal areas finished and polished
Varnish- Fluor protector and dry.