5- indirect restorations

What materials do you use in direct vs indirect- partial vs total?

Resin

Inlay/onlays- cast metals, composite, ceramics

Crowns- metal, ceramics 

What is an inlay?

Preparations do not cover any cusp of tooth

Can be MOD or occlusal-vestibular

What is an onlay?

Preparations cover any cusp of tooth

Restoration option after RCT

What is an overlay?

Preparations cover entire occlusal surface 

What are indications of indirect restorations?

Give strength to weak tooth

If widespread destruction 

Pillar for fixed prostho 

Correct malocclusions and abrasions

Restore teeth with RCT

Very large class 1 or 2

Subgingival restorations

When are indirect restorations contraindicated?

Small defects

High caries activity

Inadequate retention

Short clinical crown

Young teeth (large pulp chambers)

Deciduous teeth

What are the advantages of indirect restorations?

Save tooth structure

Colour stability- porcelain doesn’t change colour

Visible accessible margins for cleaning

Reduce periodontal irritation

Materials have less tendency to wear and stress

Reproduce anatomy

Lower rate of volumetric changes

What are disadvantages of indirect restorations?

Retention by adhesive cements- may allow micro leakage

Cementation complex- etch, prime, bone, cure

Higher cost

More invasive cavity prep

Less retention than full crowns

How is an inlay prepared?

Tapered flat-head diamond with rounded tip

Outline & Extension-

Start from occlusal groove

Extend into proximal/free surfaces to form proximal box

Remove contact with adjacent tooth.

Dimensions-

Occlusal depth- 1.5 mm (perpendicular to insertion path)

Isthmus width- 1.5–2 mm

Proximal axial depth- 1 mm

BL width: ~2 mm in larger boxes

Divergent walls (10–15°) toward occlusal

How do you prepare an onlay?

Conical diamond burs with rounded tip

Axial reduction with conical flat head and round end bur0] to make chamfer 

No contact between cavity margin and adjacent tooth or sharp angles

Can how can we prepare overlays?

In lab or using cad/cam

What provisional filling is used for inlays?

Fermit- temp filling cement- cheap, don’t need impression before 

What provisional filling is used for onlays?

Protemp

Take impression before using alginage or putty silicone 

Use a non Eugenol temp cement- temp-bond NEC- inhibit polymerisation of resin adhesives 

What does the first clinical session consist of?

X-ray, impressions for provisionals, remove caries and prep tooth

Silicone impression, wax occlusal register, cement provisional, lab

What does the second lab session consist of?

Remove provisional and clean tooth 

Insertion and cement resto

Consider contact points, marginal adjustment, stability

How do we complete absolute isolation before Cementation?

Apply a resin barrier (the same type used in tooth whitening) to protect the gums

cure for 20 seconds

Use Teflon tape on adjacent teeth to stop them from bonding

Different ceramics need different etching times and acids- what is used for the inner side of ceramic vs silicate porcelain?

9.6% (yellow) hydrofluoric acid for 2 minutes.

4.9% (red) hydrofluoric acid for 20 seconds.

After HF etching-  etch with orthophosphoric acid for 30 seconds, apply silane for 1 minute

What does the total etching consist of and the adhesive application?

Etch enamel with 37% phosphoric acid for 30 seconds, etch dentin for 20 seconds, rinse and gently air dry

Apply dual adhesive on tooth and restoration on inner surface- light cure partially

How do you conduct bonding of an indirect restoration?

Fill tooth and restoration with dual cement 

Place tooth with pressure occlusally 

Polymerise for 5 secs to remove excess cement then 1 minute