inlay onlay
DESCRIPTION
Inlay-OnlayTRANSCRIPT
Inaly and Onlay
For singletooth restoration
Onlay : all cusp
Inlay :<all cusp
Inlay
Instead of amalgam
Low caries rate
Small Class II restoration
Contraindication:
MOD – risk of cusp fracture
Onlay
Restoration of a severely worn dentition
Replacement of an MOD amalgam restoration
Contraindication:
Extend beyond facial or lingual line angles
Advantages(gold alloy)
Low creep and corrosion
Esthetic: not lead to tooth discoloration
Onlay : can support cusps, reducing risk of fracture (unlike amalgam and inlay)
Disadvantages
If a too small carious lesion =>additional tooth removal is necessary
Proximal extension =>metal display,gingival encroachment
Cusp fracture due to wedging from the inlay
Armamentarium
Carbide burs are usually used
tapered/round/cylindrical carbide bur
Finishing stones
Chisel/Hatchet/gingival margin trimmers
Class II Inlay preparation
Margins of the restoration should not be too close to a centric contact(<1mm)
Rubber dam application
outline
Penetrate cetral groove 1.8mm with a small round/tapered bur
Perpendicular to line of buccal and lingual cusp
B/L extension as conservative as possible
outline
Proximally: stop at height of contour of marginal ridge
Cevically: to caries lesion
B/L: parallel to the original proximal surface
floor of box:1.0mm (ML)
proximal clearance: 0.6mm
Caries removal
Remove caries with excavator
Place cement base to restore
Groove and bevel
Junction of axial and gingival wall =>groove with gingival margin trimmer
Gingival margin: 45degree:taper bur(finegrit diamond)
Proximal bevels: taper bur
Groove and bevel
Occlusal bevel: chamfer hollowground bevel roundbur or stone
MOD Onlay preparation
Penetrate cetral groove 1.8mm
Incooperating deep buccal lingual grooves
Remove all amalgam restoration
Outline Form
Extend M&L to height of contour of marginal ridge
BOX:gingival B/L→
Clearance: 0.6mm
Sometimes restoration and caries require box extend beyond optimal
If extension beyond line angle crown→
Caries Excavation
Remove caries with excavator(lowspeed round bur)
Place cement base to restore
Adequate sound dentin is present on axial walls to provide retention and resistance
Occlusal reduction
Functional cusp guiding groove: 1.3mm + 0.2mm for smoothing
Bur more horizontal than intended restoration cusp
Noncentric cusp:0.8mm
Bur parallel to cuspal incline
Occlusal reduction
1.0mm centrica cusp ledge with cylindrical bur (provide bulk)
About 1mm apical to the opposing centric contacts
Cannot be too apical resistance form from box →would be lost
Bevel (margin placement)
Gingival bel:45 degree
B/L bevel
Cusp bevel: roundtipped diamond; chamfer bevel