This document discusses the specifications and properties of dental composite materials according to ADA specification no. 27. It outlines the major and minor constituents of composites including the resin matrix, filler particles, and coupling agents. It also describes the advantages and disadvantages of composites, their mechanical properties, modes of curing, and factors that affect properties such as polymerization shrinkage, thermal expansion, water sorption, and radiopacity.

1. ADA specification no. 27
R.K.Haritha

3. Silicate cements
Polymethylmethacrylate (PMMA)
Filler particles principally containing silica
Bisphenol A glycidyl methacrylate (bis-
GMA)

4. Direct and indirect esthetic restorative
material
Splinting of mobile teeth
Luting agents and root canal sealers
Chemical cure and dual cure resins – core
buildup
Pit and fissure sealants and in preventive
resin restorations (PRR)
Bonding of orthodontic brackets

5. Major constituents Minor constituents
Resin matrix Color modifiers
Filler particles Inhibitors
Coupling agent
Activator – initiator – accelerator
system

6. Chemically active component
Aromatic or aliphatic diacrylates. Most
commonly bis-GMA --- Bowen’s resin
Lower polymerisation shrinkage
Extensive cross linking
Other difunctional molecules – Urethane
dimethacrylate (UDMA), and triethylene
glycol dimethacrylate (TEGDMA)
Other diluent monomers – MMA, EGDMA

7. Quartz (silica dioxide/silica) – chemically
inert and extremely hard to grind.
Size range – 0.1 – 100 mu mg
0.06 – 0.1 mu mg produced by pyrolytic or
precipitation process.

8. Decrease polymerisation shrinkage
Decrease the coefficient of thermal
expansion
Water sorption is less
Improve the mechanical properties
Radiopacity
Ideal means of controlling color,
translucency and flurescence.

9. Organic silicone compound called silane.
Most commonly used is gamma –
methacryloxypropyl trimethoxysilane.

10. Chemical cure composites –
benzoyl peroxide initiator and catalyst
paste tertiary amine activator,
N,N-dimethyl-p-toluidine.
Light cure composites –
single paste containing the photosensitizer
camphoroquinone and an amine activator.

11. INHIBITORS – butylated hydroxytoulene
in concentrations of 0.01%
COLOR MODIFIERS – titanium dioxide
and aluminium oxide (0.001 – 0.007wt%)
Darker shades placed in thinner layers or
cured for a longer time.

12. ADVANTAGES DISADVANTAGES
1. Esthetics
2. Conservative cavity
preparation
3. Reparability
4. Low coefficient of thermal
conductivity
1. Technique sensitive
2. Proper contact and contour
3. Isolation
4. Nonantimicrobial
5. Polymerisation shrinkage

13.  Addition and condensation
 Curing lights
1. QTH curing light
2. LED curing light
3. PAC curing light
4. Argon laser curing light
 Modes of curing
1. Soft start
2. Pulse delay
3. Ramped cure
 Oxygen inhibition

14. QTH
LLED
Plasma
arc
(PAC)
Argon
laser

15. Based on resin matrix used
Bis-GMA based
UDMA based
Silorane based
Based on type of curing
Chemical cure
UV light cured
Visible light cured
Dual cure
Tri cure
Heat and pressure cured
Based on filler particle size
(Lutz and Philip)
Conventional
Microfilled
Small particle
Hybrid
Based on mode of curing
a. Instant cure
b. Soft cure
1. Ramped cure
2. Stepped cure
3. Oscillating cure
4. Delayed cure

16. Working time – no less than 90 seconds
Setting time – 3 minutes to 5 minutes
Polymerisation shrinkage –
Composites with higher filler 1.0 – 1.7%
lower filler content – 2 – 4%
Coefficient of thermal expansion –
Ranges b/w 25 – 38*10-6/degreeC and 55
– 68*10-6/degree C

17.  Water sorption – microfilled composites – 26-
30 mu mg/mm3; hybrid composites – 5-17 mu
mg/mm3
ADA specfication – less than or equal to 40
mu mg/mm
 Solubility – less than 7.5 mu mg/mm
 Radiopacity – glass ceramics – Ba, Sr, Zr
 Colour stability – marginal discoloration,
General surface discoloration, bulk or deep
discoloration

18. Strength – 200 Mpa to 300Mpa
Hardness – directly related to vol. fraction
of inorganic fillers.
Wear resistance – fillers, porosity, tooth
position, degree of polymerisation,
finishing and polishing
Biocompatibility – cytotoxic in vitro but
there is still some controversy regarding its
clinical implications