INLAYS AND ONLAYS Flashcards
inlay
intracoronal restoration made indirectly to strengthen and repair decayed or damaged posterior teeth
onlay
similar but extends over weakened cusps to provide extra protection
crown
provides full coverage over tooth
onlay only provides cuspal protection
indications for inlays and onlays
1) As an alternative to amalgam
- concerns for amalgam toxicity
- lichen planus (can be due to the amalgam)
2) When composite isn’t indicated
- eg size of cavity
- previous failed composite restorations
- aesthetics considerations
3) when a long lasting aesthetic result is aimed
4) a conservative type of indirect restoration
indications for onlays
teeth with larger restorations but sound buccal and lingual walls
endo treated teeth
wider MODs
MODs in premolars
indications for inlays
small MO or DO in molars/pre
conservative MOD molar
contraindicaitons of inlays/onlya
patients with poor OH
not sutible for pts with excessive occlusal loading
materials
gold
ceramic
resin composite
gold ad and dis
ad - conservative marginal integrity good wear characteristics corrosion resistance relative ease of handling excellent phyical and mechanical characteristics
dis - cost technique sensitive poor aesthetics wedge effect of inlay
ceramic ad and dis
ad
- aesthetic
- stronger and more stable material ( no wear; discoluratiom)
- resin composite luting agent
- marginal leakage due to polymerisation shrinkage is minimal
- conservative ceramic restoration
dis
- sensitive technique (intraoral adjustment is contra indicated until the restoration is bonded, after bonding adjustments can compromise aesthetics)
- wear of the luting agents can lead to marginal gaps and secondary caries
- longer treatment: indirect restorations – 2 visits are required unless chairside CAD/CAM used
- cost
common ceramics used
feldspathic glass ceramic
leuctie reinforced glass ceramic
lithium disilicate glass ceramic
fabrication technique for each material for inlay/onlay
1) gold
- lab made , lost wax or casting
2) composite
- CAD/CAM chairside
- labmade
3) ceramic
- conventional – pressable, refractory, casting
- CAD/CAM – chairside or lab
gold inlay measurements
1.5mm occlusal reduction
proximal box 1mm width
isthmus 1/3 intercuspal width
gold onlay
intracoronal prep as inlay
1.5-2mm cuspal reduction
1mm occlusal shoulder
onlays and occlusal force
biting forces pushed through long axis of tooth
cusps are protected
stress distribution for inlays
occlusal forces are placed which spread occlusally and laterally
overtime can break the buccal cusp
prep for ceramic inlay
similar to gold inlay but no bevels (bevels would thin the enamel and be liable to fracture)
- box shaped cavity
- parallel and slightly divergent walls
- rounded interal line angles (to prevent stress concentrations)
- 90 degree cavosurface angle (to prevent any unsupported enamel or thins of ceramic)
- 2mm deep occlusally
no grooves or slots
prep for ceramic onlay
- Same as inlay
- addition of one or more cusps also prepared
- Provide 1.5mm occlusal reduction
- Cusp reduction 2mm
direct temporarys for inlays
- composite based temporary material
- mainly for inlays
- shape with flat plastic instruments within the cavity
- no impression required
- no temp cement needed
- check occlusion and adjust as necessary
indirect temporary
- pre operative impression required
or lab made vacuform shell - composite based material
- temp bond NE to cement, no eugenol based material
what cements are preferred
resin luting agents over traiditonal (GIC) as they provide adhesive bond to tooth structure
how to cement glass ceramic
fitting surface treated with HF acid
coat fitting surface with sialine coupling agent
resin cement for cementation
failure or the inlay or onlay
bulk fracture - often in areas of cuspal coverage esp if ceramic material less than 2mm thick marginal breakdown - resin cement not heavily filled wear more quiclly
