Resin composites are dental restorative materials made of an organic resin matrix and inorganic filler particles. They contain monomers like bis-GMA that polymerize to form the matrix. Fillers like silica improve properties and radiopacity. Coupling agents bond fillers to the matrix. Composites are classified by filler size and polymerization method. Proper placement techniques and acid etching improve bonding to tooth structure. While esthetic and conservative, composites also have limitations like polymerization shrinkage, sensitivity, and wear over time.

1. By Dr. Dida Boru
April, 2014

2.  A composite: a combination of two or more
chemically different materials with distinct
interface between them and having properties
better than those of the components acting
alone.
 Resin composite: a restorative dental material
containing
◦ Organic resin matrix
◦ Inorganic filler particles
◦ Coupling agent
◦ Other components

3.  Are high molecular weight monomers
◦ Bisphenol A glycidyl methacrylate (bis-GMA)
◦ Urethane dimethacrylate
 Terminal methacrylate groups provide sites
for free radical polymerization
 Disadvantages of bis-GMA
◦ Color instability
◦ High viscouscity ( decreased by adding TEGDMA or
EGDMA)

4.  May be
 Colloidal silica: inert
◦ Low cofficient of thermal expansion
◦ Improved condensability and polishibality
 Barium silicate:medium hardness
◦ Is very radiopaque
 Quartz: most widely used filler material throughout 1970’s
◦ Very stable and inert
◦ Disadvantages lack of radiopacity
 Abrasiveness
 High cofficient of thermal expansion
 Wear opposing tooth
 Zinc silicate
 Lithium aluminium silicate

5.  The greater percentage of the filler content,
the better the physical properties
 Classification of filler particle size
◦ Macro fillers: 10-100 microns
◦ Midi fillers: 1-10 microns
◦ Mini fillers: 0.1-1 microns
◦ Micro fillers: 0.01-0.1 microns
◦ Nano fillers: 0.005-0.01 microns
 Generally the smaller the average particle
size, the easier it will be to polish

6.  Its primary purpose is to bond filler particles
to organic resin matrix
 Improve physical properties of resin
composite.
 Most commonly used coupling agent are
organosilanes (Gamma methacryloxy
propyltrimethoxy silane)

7.  Polymerization initiators
◦ For chemically activated: benzoilperoxide and
tertiary amines
◦ For light activated: diketone photoactivators
(camphoroquinone) are used
 Polymerization inhibitors: monomethyl ether
of hydroquinone
◦ to prevent spontaneous polymerization under
normal storage condition
 Uv radiation absorbers:
◦ added to improve color stabilty by absorbing
electro magnetic radiation.

8.  Based on filler particles size:
◦ Traditional (convectional)
◦ Small particle macrofilled resin composite (fine
particles)
◦ Microfilled resin composites
◦ Hybrid resin composites (blend)
 Based on polymerization method
◦ Chemically activated
◦ Light activated

9.  Filler : 70-80%
◦ 20-50 micron size
 Disadvantages:
◦ Roughness
◦ Staining and discoloration

10.  Filler: 70-80%
◦ 1-5 micron size
 Good compressive and tensile strength
(fracture resistant)
 Polished nicely
 Recommended for large (2mm or larger)
diastema closure and for class IV cavity

11.  Filler: 35-50%
◦ 0.02-0.04 microns
 Polish to high luster and produce excellent
esthetic result
 Should not be used in high stress bearing
area
 Physical properties are generally inferior to
those of small particles macro filled resin
composites
 Good choice for class V cavity

12.  The most commonly used nowdays
 Filler: 70-80%
◦ 0.04 and 1-5 microns sized
 Are usually radiopaque
 Physical properties are intermediate to that of
Traditional and Small particle macro filled
resin composite
 Fracture resistant

13.  Two paste system
 Base: contain benzoyl peroxide
 Activator (catalyst): Contain tertiary amine
 Disadvantage
◦ Contain porosity

14.  Ultraviolet light activated:
◦ contain benzoin methyl ether and tertiary amines
which when activated by UV light produce free
radicals
 Visible light activated:
◦ contain camphoroquinone (0.25%) photo initiator
and tertiary amines in single paste

15.  Advantages of visible light resin composites
over self cured composites
◦ Longer working time
◦ Shorter chair time
◦ Greater degree of polymerization
◦ Reduced porosity
◦ Greater color stability

16.  Disadvantages
◦ Non uniform polymerization secondary to limited
depth of penetration by the curing light
 Following light activation resin composites
continue to undergo polymerization for up to
24 hours

17. I. Incremental addition of resin composite
• Ensures completeness of polymerization
• Reduces polymerization shrinkage stress
II. Resin layer should not exceed 2mm in
depth
III. Minimum of 40 seconds exposure time
The most desirable finish surface for a
composite resin can be provided by
aluminum oxide disks
Contraindications for composite include
varnish and zinc oxide-eugenol

18.  Dr. michael Bounocore developed acid
etching technique using 85% phosphoric acid
in 1955
 Purposes
◦ Increases surface energy
◦ Chemically cleans tooth structure
◦ Creates micropores for micromechanical retention
 Standard acid etching of enamel is
application of 37% phosphoric acid for 15
seconds with 15 seconds rinsing and 15
seconds drying

19.  Other acids used
◦ Pyruvic acid
◦ Nitric acid
 Depth of enamel caused by enamel etchin is
approximately 10-15 microns
 Bonding agent is used instead of acid etchant
to open dentinal tubule
◦ EDTA

20.  Resin composite undergo volumetric
shrinkage of 1.6-5.7% during polymerization
due to monomer shrinkage
 Most detrimental effect of shrinkage is
microgap formation which results in
◦ Sensetivity
◦ Secondary caries
◦ Staining
◦ Pulpitis and necrosis

21.  Indications
◦ Class III cavity (except distal cavity on canines)
◦ Class IV cavity
◦ Cavity V cavity
◦ Filling gaps (diastemas) between teeth
◦ Veneering
◦ Minor reshaping of teeth
◦ Partial crowns on single teeth
◦ As Pit and fissure sealant
◦ Cementation of crowns

22.  Contraindications
◦ Class II cavity
◦ Class I cavity ( only indicated if requirements
fulfilled)
◦ Cavity on distal surface of canines

23.  Resin composite is indicated for posterior
tooth restoration if:
◦ Restoration is not in occlusal contact
◦ Isthmus is less than 1/3 of buccolingual intercuspal
dimension
◦ Cusps are not involved
◦ Margins are not involved
 Treatment area must isolated well

24.  Esthetics
 Low thermal conductivity
 No mercury or galvanism
 Conserves tooth structure
 Easily shaped prior to polymerization

25.  Time consuming to place
 Micro leakage
 Post treatment sensitivity
 Excessive wear
 Low strength
 Highly sensitive to moisture