Inlays and Onlays Flashcards
What are the types of materials used for inlays and onlays?
Ceramic
Metal
Indirect composite resin
Survival rate is similar and deterioration is in the order of Gold < Ceramic < Composite
What are the indications for inlays and onlays?
Class II (OD, MO, MOD)
Reestablish an adequate contact point
Severely worn tooth but minimal damage
Replacement of an MOD amalgam with aesthetic indirect restoration
One or more cusps have been lost or require overlays to protect weakened tooth structure
What are the contraindications for inlays and onlays?
Severely damaged tooth
Insufficient bulk to provide resistance and retention form
MOD inlays*
Retainers of FPD
What are the advantages and disadvantages to inlays and onlays?
Advantages
More durable than direct restorations (composite)
Easier to reestablish contact points compared to direct restorations
More conservative than complete crowns (extracoronal restorations)
Onlay - cusp protection
Disadvantages:
Less conservative than direct restorations
Risk of cusp fracture especially with inlay
Higher cost and chair time than direct restorations
When is an onlay indicated instead of an inlay?
When the width of an intracoronal cavity exceeds 1/2 the distance of the cusp tips, an onlay or crown is probably more suitable
Cuspal coverage is needed
Root-treated tooth
What are the features of inlay and onlay preparation?
All cavosurface angles need to be sharp (90 degrees)
No sharp internal line angles or points only curved transitions
The prep extension depends on the extension the previous restoration or the caries lesion
Opposing walls should be divergent
Avoid complex internal geometry to the preparation
Transition of material thickness should be gradual not abrupt
No acute angles within preparation
No additional retention features
No tooth structure without support
No aspect of the margin should be located in an undercut
How should preparation be finished?
Finishing of preparation should be with a bur with a grit size of no more 50 microns
What are the indications for a partial coverage crown?
Restore posterior teeth that lost moderate tooth structure with intact buccal wall
Reestablish the occlusal surface contour with metal alloy without compromising aesthetic (e.g. increase of vertical dimension)
Teeth with sufficient bulk to accommodate the necessary retentive features
Retainer of Resin Bonded Bridges
What are the contraindications for a partial coverage crown?
Short clinical crowns
Extensive crown destruction
Retainers for long-span FDPs
Endodontically treated teeth
Patients with high demand for aesthetics
What are the advantages and disadvantages of partial coverage crowns?
Advantage:
Tooth structure preservations
Better access for oral hygiene
Less soft tissue damage as less margin is placed near the gingival margin
Easier to verify seating and to remove cement
Disadvantage:
Less retention and resistance
Technically more difficult
