DMS

Question 1

what does composite consist of

Answer 1

glass filler particles (size alters material)
resin (BIS-GMA)
silane coupling agent (bonds filler and resin)
camphorquinone (light activation)
low weight dimethacrylates (improve viscosity and reaction rate)

Question 2

composite bond strenght

Answer 2

40 MPa (megapascals)

Question 3

what type of composite has the best overall properties
- conventional
- microfine
- hybrid

Answer 3

hybrid
varying particle sizes

(conventional - strong but finishing and staining issues, microfine - better aesthetics but decreased mechanical properties)

Question 4

discuss the advantages and disadvantages of composite as a restorative material

Answer 4

advantages - strong chemical bond to tooth, low thermal conductivity, good aesthetics
disadvantages - thermal expansion coefficient much greater than enamel/dentine, polymerisation shrinkage, must be fully cured to avoid monomer leaching, technique sensitive

Question 5

how is bulk fill possible

Answer 5

includes multiple photoinitiatiors with different absorption spectrums

Question 6

why is zinc not included in modern amalgams

Answer 6

interacts with water and forms hydrogen bubbles
this causes expansion
- downwards pressure - pulpal pain
- upwards pressure - restoration sitting proud

Question 7

what is contained within the powder and liquid used to create amalgam

Answer 7

liquid - mercury
powder - silver, tin, copper, mercury

Question 8

why is copper added to amalgam

Answer 8

decreased creep
increased corrosion resistance
increased strength

Question 9

discuss the advantages and disadvantages of amalgam as a restorative material

Answer 9

advantages - good working time, low cost to patient, longer survival than composite (12-15 years), radiopaque, durable, good wear resistance

disadvantages - poor aesthetics, does not bond to tooth, high thermal diffusivity, cavity prep needs to be retentive, risk of lichenoid lesions, risk of tooth discolouration, concern re mercury toxicity, creep

Question 10

retention form

Answer 10

features that prevent the loss of the restoration via path of insertion

Question 11

name 3 things included in the minamata conventions guidance for amalgam use

Answer 11

must be encapsulated
waste disposal must be separate
not to be used on U15s, pregnant or breastfeeding

Question 12

name 3 materials that may be used as a cavity liner

Answer 12

calcium hydroxide
GIC
RMGIC

Question 13

what are the 3 stages of GIC formation

Answer 13

1 - dissolution - H+ ions attack glass particles
2 - gelation - Ca binds with carboxyl groups on polyacrylic chains
3 - hardening - Aluminium further cross links (takes days)

Question 14

what monomer is used in RMGIC

Answer 14

HEMA

Question 15

what material may be used as a cavity base

Answer 15

zinc oxide cements

Question 16

advantages and disadvantages of conventional GIC

Answer 16

advantages - fluoride release, no setting expansion, thermal expansion similar to tooth
disadvanatges - poor wear resistance, poor mechanical properties, soluble

Question 17

compare conventional GIC to RMGIC

Answer 17

both have fluoride release
RMGIC has better aesthetics, decreased solubility and improved physical properties
however also sees polymerisation contraction shrinkage, exothermic setting reaction and HEMA may see water uptake

Question 18

whats in GIC

Answer 18

powder - fluoro-aluminosilicate glass
liquid - polyacrylic acid, tartaric acid

Question 19

whats in RMGIC

Answer 19

powder - fluoro-aluminosilicate glass
liquid - polyacrylic acid, tartaric acid, HEMA, photoinitiator

Question 20

RMGIC vs composite

Answer 20

RMGIC has poorer mechanical properties, poorer aesthetics, increased solubility however does release fluoride

mechanical properties - compressive strength, tensile strength, wear resistance, hardness

Question 21

creep

Answer 21

repeated stresses over time sees slow and permanent deformation