7/8- direct and indirect resto

What are direct restorations?

Can be fabricated and completed inside the mouth- don’t need lab

Can do in single appointment with no provisional or temp resto

What are indirect restorations?

To be fabricated inside the mouth- crowns, bridges, implants, inlays/onlays, veneers

Need 2 appointments

What are the disadvantages of direct composite restorations?

Fatigue

Wear

Polymerization shrinkage (indirect composites avoid secondary problems like infiltration, gaps, fracture of enamel, cuspal deflexion)

Biocompatible- pulp and periodontal tissues

Degree of conversion is about 70% (vs indirect is 95%)

Colour changes over time associated with external dyes (can polish indirect better)

Surface roughness of direct composite leads to retention of plaque and abrasion of the antagonist teeth

What are the advantages of using indirect restorations?

Better polymerisation than direct composites- 95% degree of conversion

Better physical and aesthetic properties.

Restoration-tooth discrepancy supplied by cement (better dual cure cement)

Better contact point (avoid food packaging problems)

If fracture can be restored in the clinic with composite

In patients with bruxism we can use this type of material; Ceramic is going to wear less than the resin as it is hard)

What are the disadvantages of using indirect restorations?

Complex prep

Usually 2 visits required (even if 1 visit- longer)

Higher cost to the patient

Indications of using indirect restorations?

Restorations in the posterior sector of large cavities-

MOD of premolars and molars (inlays)

Onlays in premolars and molars

Simultaneous restorations (multiple teeth)

Endodontic teeth reconstruction (recommended to do cuspal coverage here)

Posterior aesthetics

Contraindications of using indirect restorations?

Preparation that exceed the enamel-cement limit→use glass ionomers

Poor oral hygiene

Severe parafunctions (bruxism). Only can't do in severe bruxism. This doesn’t mean you can’t do it

In bruxism patients at all

Short and non-retentive crowns

What are some common radiopaque adhesive systems and some characteristics?

Clearfil universal bond quick- contains fillers, fast application

Optibond universal- increases bond strength and layer thickness

G-Premio bond- better visibility under x ray

Radiolucent adhesive- invisible on x ray- contains nano fillers (silica), could be mistaken for secondary caries

What are the steps of Stratification technique for posterior composites?

1. Isolation and cavity design

2. Etching and adhesive

3. Build proximal wall first- place thin layer of composite against the matrix to create enamel wall- converts in class 1 (layering easier)

4. Layering- use dentin shade composite in 2mm increments

   b. Cusp by cusp build up- better anatomy, less finishing needed, better stress distribution

   c. Final enamel layer- apply more translucent shade, keep thin- natural and wear resistance

5. Occlusal anatomy and finishing- carve primary grooves, triangular ridges, fossae before final cure, after curing- check occlusion

What is the oblique layering technique?

Each increment only touches 1-2 walls, reduces polymerisation stress

Critical in posteriors to prevent marginal leakage and post op sensitivity

What are 5 common mistakes in posterior stratification?

Bulk filling- shrinkage and cuspal deflection

Skipping proximal wall step- poor contact

Flat occlusal surface- bad function

Thick increments- incomplete curing

Ignoring occlusion- post op pain

Why is flowable composite not suitable as a final layer?

Material Properties: Flowable composites have:

. Lower filler content (not strong)

. Lower viscosity (they flow easily)

. Lower mechanical strength

. Higher wear rate

What happens if you use flowable composites as a final layer in posterior teeth (high load)?

Rapid occlusal wear

Loss of anatomy (cusps flatten)

Increased risk of fracture

Poor occlusal stability

What happens if you use flowable composites as a final layer in anterior teeth?

Poor polish retention

Surface becomes rough over time

Staining and discoloration

Inferior translucency control vs enamel composites

Why should you not over etch dentin?

Collagen network collapses

Poor resin infiltration

Leads to weak bond, post op sensitivity

Why are composite resin inlays and onlays a good choice for teeth with wide proximal occlusal cavities?

Aesthetics and high quality function compared to porcelain or direct

Structural- returns nearly all original strength

Abrasion- wear at same rate as natural tooth- but also new ceramic material like E max (ivoclar vivadent) good option too

Conserve tooth structure

Supragingival margins

Chair side repairs

Advantages of porcelain inlays?

Good esthetics– color harmonious with that of tooth structure

Low thermal conductivity

High tolerance of the soft tissues to its presence

Chemically inert and relatively insoluble in oral fluids

A coefficient of thermal expansion close to that of natural tooth

Disadvantages of porcelain inlays

Expensive and timely compared to direct resto

Technique sensitive

Some newer type of ceramic restorations need special and expensive lab equipment

Porcelain is brittle and can fracture- if inadequate thickness- fractures can occur during tryin or post cementation, esp if high forces

High hardness- can cause abrasion of the opposing teeth or restorations

Lack of perfect adaptation to cavity walls exposes the cement line

Why is the use of non eugenol cements like TempBond recommended for Cementation?

Eugenol has plasticising effect on resin cements and bonding agent

What is a flexible cast fabrication?

A completely indirect technique, performed in 1 appointment, doesn’t require a provisional restoration can be accomplished using a flexible cast technique

What are the 6 steps in the clinical technique to make a flexible cast?

Prep same as direct/indirect technique

Make an irreversible hydrocolloid impression to see margins of prep

Inject a firm setting vinyl polysiloxane impression material into the alginate to form a flexible cast

Fabricate inlay using light cured hybrid composite resin

Heat treat resto and place