Inlays and Onlays Flashcards
Inlay and purpose
Intracoronal restoration strengthen and repair decayed or damaged posterior teeth
Onlay and purpose
Similar but extends over weakened cusps to provide extra protection
Indication for inlay and onlays
alternative to amalgam - toxicity and lichen planus
resin not indicated due to size of cavity/prev failure/aesthetics
Long lasting aesthetic result aim
Indications for inlay
Low caries rate
Small MO/DO cavities in molars premolars
Conservative MOD in molars
Indications for onlay
Teeth with larger restorations and sound buccal and lingual walls
Endo treated teeth due to risk of fracture
Wider MODs
MODs in premolars
Materials for inlays and onlays
Gold
Ceramic
Resin composite
Advantages of gold
Conservative Marginal integrity Good wear Corrosion resistance Easy to handle Excellent physical and mechanical problems Excellent survival rates
Consideration for gold
Cost
Technique Sensitivity
Poor aesthetics
Wedge effects of inlay - creates wedge
Advantages of adhesive technologies
Very aesthetic
Stronger more stable -no wear or discolouration
Less shrinkage as resin composite is used as luting agent
Marginal leakage is minimal
Conservative ceramic restorations
Ceramic considerations
Fragile - handled with care
Can’t make intramural adjustments until bonded
Adjustments can compromise aesthetics
Wearing of luting agents can lead to marginal gaps and secondary caries
Two visits required
Types of ceramic
Feldspathic glass
Leucite reinforced
Lithium disilicate
Indirect resin composite types
Hybrid composite
Ceromers
Ceramic optimised resins
General rules of preparation
Finishing line should extend to composite
Box shaped cavities
Divergent walls to allow path of insertion
No undercuts
limit path of insertion
Resist occlusal forces
Specific guidelines apply for gold or ceramic/composite inlays and onlays
Occlusal isthmus should not exceed 1/4 intercuspal width
Gold inlay
2mm occlusal reduction
Proximal box 1mm width
Isthmus 1/3 of intercuspal width
Gold onlay
IC prep is same as inlay
1.5-2mm cusp reduction
1mm occlusal shoulder
Has arm which extends to support result of structure
Stress distribution
Protection provided over top to equally distribute forces to share stress concentrations
Prep for ceramic inlay
Similar to
Cavity shape
Grooves or slot?
What else to check?
Similar to gold inlay no bevels Box shaped cavity Parallel and divergent walls Round internal line angles to reduce risk of fracturing 90 degree cavo surface angle 2mm occlusal depth
No grooves needed as restoration will be bonded
Bevelled finishing lines can create thin areas liable to fracture
Check occlusal contacts
Outline should AVOID occlusal contacts to avoid unnecessary load –> deterioration of cement and marginal openings
Prep for ceramic onlay
Same as onlay
One or more cusps also prepared
Different prep guidelines for cusp reduction
Block undercuts with GIC, RMGIC, resin composite
Equipment
Burs
Bur kits
Gingivae
Provisional
Basic set up
Burs = medium grit tapered and straight diamond
Give box shaped cavities
Retraction cord and packer/GRP
Provisional material
Temporisation
No eugenol as this will affect setting of resin
Cementation should be done
Under rubber dam as it is sensitive to moisture
Aesthetic cementation
Resin luting > traditional
Can be self cured or dual cured
Compomers contraindicated due to expansion –> fracture
Process of cementing glass ceramic
Surface coated with
Example of cement used
Fitted surface must be treated with HF acid/sandblasting -> expands surface for binding
Fitting surface coated with silane coupling agent
Calibra resin cement
Bond between ceramic and tooth is created
Composite inlay - resin cement for cementation
Composite cement to composite inlay
Roughening of surface is NOT sufficient
Higher rate of failure
Cementation process
What also can be used?
Thickness requirements
High viscosity resin composite can also be used
Thickness of ceramic >2mm compromises curing of material
Colour of inlay can also affect setting
Failure
Bulk fracture - often in areas of cusp coverage and at isthmus
Marginal breakdown - quicker wear
Contraindications for inlay/onlay
Poor OH
Bruxism/excessive occlusal load
Gold cementation
Conventional cement options
Resin cement options
Zinc phosphate/GIC
Panavia/RelyX
