Indirect Restorations

Indications

Aesthetics

As part of treatment plan to help with construction of other prosthesis

Loss of tooth tissue

Patient factors

Medical history

Mouth opening

Mobility and manual dexterity

Finance

Oral hygiene and motivation

Tooth factors

Periodontal status

Endodontic status

Remaining structure

Remaining cuspal structure

Location of margins

Marginal ridges

Furcation

Clinical attachment loss

Pulp-capping (Barthel 2000)

45% fail in 5 years

80% fail in 10 years

Must endo before crown if pulp has been exposed

Papers

Bandish et al 2006

Reeh and Messer 1989

McDonald 2005

Gonzalez-lopez et al 2005

Loss of proprioception leading to overloading (Randow and Glantz 1986)

Location of remaining dentine is important: palatal wall plays major role in resistance to fracture (Ibrahim 2006)

Preparation

Materials

Shillingburg's principles

Preserve tooth structure

Create acceptable finish line

Reduction results in retentive restoration (NO LONGER ACCEPTED)

Encourage favourable tissue response

Rosenstiel's principles (examples)

Mechanical

Aesthetic

Biological

Retention form

Resistance form

Protect against fracture

Conserve tooth tissue

Minimal display of metal

Porcelain occlusal surfaces

Tooth structure removal (Edelhoff and Sorensen 2002)

PFM 20% more destructive than full gold crown

All ceramic less destructive than PFM

PFM 14 times more tooth removal than inlay

Inlays: least destructive

Retention

Resistance

Prevents removal of the restoration along the path of displacement

Prevents removal of the restoration in an oblique direction

Taper: Relationship of one wall of a preparation to the long axis of that prep

Ideal 3 degrees taper/6 degrees total occlusal convergence

Clinically achievable: 10-22 degrees total occlusal convergence

Path of placement

the specific direction in which a prosthesis is placed on the residual alveolar ridge,abutment teeth, dental implant abutment(s), or attachments

Posterior 3/4 crown: parallel to long axis of tooth

Anterior 3/4 crown: parallel to mid-third of labial surface

Longer prep improve resistance

Interfere with arc of casting

In short prep, grooves in axial walls improve resistance

Prep should follow anatomy

Choice

Porcelain fused to metal

Porcelain

Metal

Ceramics

Composite

Problems with evidence

Heterogeneity of methods

Technology advances faster than research

Survival of materials at 5 years (Pjetursson 2007)

Anterior teeth

Posterior teeth

All ceramic = PFM

PFM = Densely sintered alumina crowns = Reinforced glass cermamics

Slightly lower survival: InCeram, Glass ceramics