onlays Flashcards
onlay indications
tooth wear - increase OVD
fractured cusps
restore RCT teeth - cuspal coverage
replace failed direct Rxs
sufficient occlusal tooth substance loss
remaining tooth substance weakened
- caries
- pre-existing large Rx - MOD with large isthmus
cast metal inlays/onlays preferable to amalgam when:
- higher strength needed
- significant tooth recontouring required
onlay contraindications
active caries and PDD
time
cost
onlay conventional clinical stages
preparation
temporisation
impressions and occlusal records
cementation
onlay types
composite
gold
porcelain
onlay definition
extracoronal Rxs made in lab with cuspal coverage
onlay ceramic/composite prep
margins clear of occlusal contact points 4-6 degree tapered walls - no UCs flat pulpal floor - even depth, perpendicular to PofI proximal box (if required): 1mm width (supragingival) shoulder or chamfer margins: 1mm rounded internal line angles occlusal reductions - non-working cusp: 1.5mm - working cusp: 2mm clear of adjacent tooth contact points
onlay gold prep
margins clear of occlusal contact points
4-6 degree tapered walls - no UCs
flat pulpal floor - even depth, perpendicular to PofI
proximal box (if required): 1mm width
(supragingival) shoulder or chamfer margins: 0.5mm
rounded internal line angles
occlusal reductions
- non-working cusp: 0.5mm
- working cusp: 1mm
clear of adjacent tooth contact points
avoid cutting sound tooth tissue - use composites to block out undercuts
onlay temporisation and impression
make temp Rx
take impressions and occ records
- to lab
cement temp
onlay lab prescription
pour impressions mount casts on articulator - waxbite/occ record - facebow construct Rx - tooth - material - thickness - shade - characteristics
onlay cementation
ceramic onlays
- weak when not cemented - don’t check occlusion as may fracture
- adhesive systems: resin cement
gold onlays
- GI, resin cement
place matrix strips IP or PTFE tape over adjacent teeth
onlay alternatives
large direct Rx - amalgam, composite, GI crowns - 3/4 gold, full extraction
inlays/onlays 1st appt
LA (if no RCT) make putty index imp for temp tooth prep make temp impressions, bite reg and record shade cement temp
inlays/onlays 2nd appt
remove temp isolate, clean and dry prepared tooth try in, assess fit, adaptation, occlusion etc if happy cement minor occlusal adjustments (if needed)
