12- interim restorations

Why do we use interim restorations?

Needs to function for extended period- can be weeks or months- must be adequate to maintain health

Lab delays

Patient unavailable

Delay placing definitive restoration due to TMJ disorder factors or perio disease

What are the biological requirements

Protect pulp

Maintain periodontal health- facilitate plaque removal, good marginal fit, contours, smooth surface 

Provide occlusal compatibility

Maintain tooth position 

Protect against fracture 

what are mechanical requirements 

Resists functional loads, removal forces 

Maintain interabutement alignment- don’t want abutments to move

Condense slides 10, 11 about function

How do we prevent tooth displacement after prepping tooth?

Referent interim resto quickly 

Small space between them- luting agent has lower strength then regular cements- cannot withstand added force if big space 

Removal of reuse

What are aesthetic requirements?

Easily contourable

Colour compatibility and stability overtime 

Translucency 

Material matches colour of adjacent teeth, interim restoration is a guide to know what they want- specific feedback

What are indications of fiber-reinforced interim restorations?

Long span posterior FDP

Long treatment time

Can’t avoid excessive forces on prosthesis

High masticatory muscle strength 

Freq breakage history

Models used in making interim restorations consist of…

External surface form (esf)- 2 catergoirss- custom, preformed

Tissue surface form (tsf)- divided into indirect, direct and indirect-direct procedure

Slide 19 

What is a custom ESF?

Negative reproduction of either patients teeth before prop or modified diagnostic cast 

Obtain from impression- mouldable putty popular- can trim easily for accurate reseating 

Use thermoplastic sheets 

Fill in with autopolymerising resin or acrylic

Indirect procedure of indirect procedure (prpepared outside mouth)- adva

Impression of prepared teeth- pour it with quick setting material

No contact of free monomer- can cause allergic reaction or damage gingiva or tooth

Teeth aren’t effected by heat from polymerising resin

Can be retained for multiple uses

Won’t shrink

Direct procedure disadvs

Tissues trauma from polymerising resin and poor marginal fit

Indirect- direct procedure

Condense slide 31

Advantages vs disadvantage of indirect-direct procedure?

Low chair time

Less heat generated in mouth- less resin used during lining

Minimal contact of resin monomer and tissues

Need to constantly adjust to seat shell completely in prepared tooth 

Ideal properties of interim restorative materials

Good working time, easy moulding, rapid setting time

Biocompatible 

Dimensional stability- during solidification

Easy to add to or repair 

Custom indirect method- best

Impression of teeth

Lab wax up

Form final interim procedure

Not done with patient- easier

What is useful for making interim restorations in single anterior teeth and premolars?

Polycarboxylate crown 

How can we provide interradicular retention for a tooth with no sound structure?

Cast metal post and core restoration

Place wire in post space and fill down with interim resin 

What is the primary function and characteristics of interim luting agents?

Provide seal, prevents marginal leakage and pulp irritation

Low strength

Luting agents seals margin, easy to clean