indirect composites and luting cements

Question 1

use of indirect composites

Answer 1

inlays
onlays
veneers
etc

Question 2

steps to produce indirect composites

Answer 2

1. impressions
2. labs
3. technician creates inlay/onlay
4. cemented in by dentist

only 2 appts

Question 3

advantages

Answer 3

Full depth of cure
Higher degree of polymerisation (so less shrinkage)
Improved physical properties
Not as abrasive to opposing teeth compared with ceramic
Can be repaired in mouth

Question 4

disadvantages

Answer 4

Need a luting cement (can cause gingival irritation)
Microleakage can occur
Highly technique sensitive

Question 5

classification of luting cements

Answer 5

water based
- zinc phosphate
- zinc polycarboxylate
- glass ionomer
- resin modified glass ionomer

resin based
- composite
- compomer
- resin modified glass ionomer

temp cemenets
- ZOE
- zoe non eugonel

Question 6

describe the handling, biocompatibility, mechanical properties, solubility of zinc phosphate cement

Answer 6

Handling -> difficult to mix and has a short working time.

Biocompatibility -> can induce a inflammatory response, low pH when freshly mixed and this is slow to neutralise

Mechanical properties -> sufficient compressive strength for luting, brittle, similar elastic modulus to dentine, adequate film thickness

Solubility -> low water solubility when fully set, susceptible to acid attack from lactic acid

Question 7

describe the handling, biocompatibility, mechanical properties, solubility, adhesion of glass ionomer cement

Answer 7

Handling -> requires some force to mix, short working time

Biocompatibility -> burst of fluoride release on setting and then long-term release at lower level

Mechanical properties -> increases with age, lower film thickness than zinc phosphate

Solubility -> lower water solubility than zinc phosphate/polycarboxylate.

Adhesion -> bonds better to base metal alloys, no bond to precious metal alloys, bond can exceed the cohesive strength of cement

Question 8

describe the handling, biocompatibility, mechanical properties, solubility, adhesion of zinc polycarboxlate cement

Answer 8

Handling -> difficult, timing is critical (too soon means marginal seal compromised, too late and cement will have bonded)

Biocompatibility -> neutralises pH rapidly, mild pulp response, resistant to bacterial ingress, addition of stannous fluoride

Mechanical properties -> adequate strength, adequate film thickness

Solubility -> susceptible to acid attack, higher water solubility for those containing stannous fluoride.

Adhesion -> bonds better to base metal alloys, no bond to precious metal alloys, bond can be such that it exceeds the cohesive strength of cement

Question 9

types of composite resin cements and their properties

Answer 9

Composite resin cements – aesthetic resin and adhesive resin

Aesthetic resin cements are the same as composite restoratives.

Adhesive resin cements contain an adhesion promoting resin. They have no direct bond to precious metals, sometimes need a primer to bond to the tooth.

Properties -> high strength, high bond strength, insoluble, high film thickness, free monomer (so maybe bad biocompatibility)

Question 10

properties of ZOE and its non eugonel form

Answer 10

Zinc oxide eugenol or non-eugenol cements

Properties -> obtundent (blunts pain) and easy to handle, low strength, relatively high solubility, eugenol inhibits composite cure so if used as a temporary you must remove it all before a permanent cement