Dental Composites

Resin Based Cements
Dental Composites

Contents
• Introduction
• History
• Definitions
• Composition & Function
• Applications
• Classification
• Properties
• Indications / Contraindications
• Advantages / Disadvantages
• Finishing & Polishing
• Repair of composites
• Restorative Techniques
• Curing
• Innovations in Dental Composites
• Conclusion
• References

Introduction
• The search for an ideal esthetic material for restoring
teeth has resulted in significant improvements in both
esthetic materials and techniques for using them.
• Composite resins have made it possible to provide
patients with highly conservative and esthetic
restorations
• Coupled with acid etching and bonding to tooth
structure, composite resin presently enjoy universal
application.

History
1870’s – Dental Silicates 1940’s - Polymethylmethacrylate 1950’s – Dental Silicates + PMMA
(Added Strength)
(Unfilled Acrylic Resins)
The MMA matrices were later replaced
with Bis-GMA (difunctional monomer)

History
1962 – Bowen developed a new composite
His main innovation was :
- Bisphenol-A glycidyl di-methacrylate as a matrix
- Organic silane compounds as coupling agents used to bind the filler particles to the
matrix
1970
First photocured
composite – UV Light
1972
Visible Light Cure
Composites
1980
Hybrid Composites
1991
MegaFIll Composites
with glass ceramic
inserts
1996
Flowable Composites
1998
Compomers / Ormocers
• Riva YR, Rahman SF. Dental composite resin: A review. InAIP Conference Proceedings 2019 Dec 10 (Vol. 2193, No. 1, p. 020011). AIP Publishing LLC.
• Zhou X, Huang X, Li M, Peng X, Wang S, Zhou X, Cheng L. Development and status of resin composite as dental restorative materials. Journal of Applied Polymer
Science. 2019 Nov 20;136(44):48180.

History
2002
Nanocomposites
2006
Silorane based
composites
2008
Smart dental composite
with pH control
mechanism
2012
Chlorhexidine
impregnated anti bacterial
composite
2015
Self healing
composite
2019
anti bacterial composite
with cellular nanocrystals
Riva YR, Rahman SF. Dental composite resin: A review. InAIP Conference Proceedings 2019 Dec 10 (Vol. 2193, No. 1, p. 020011). AIP Publishing LLC.

Definitions
• What is a Composite ?
- Solid formed from two or more distinct phases (e.g., filler particles
dispersed in a polymer matrix) that have been combined to produce
properties superior to or intermediate to those of the individual
constituents.
• What is a Dental Composite ?
- Dental resin-based composites are structures composed of three major
components: a highly cross-linked polymeric matrix reinforced by a
dispersion of glass, mineral, or resin filler particles and/or short fibers bound
to the matrix by coupling agents
Shenoy A, Nair CK. Phillips' Science of Dental Materials-E-book: A South Asian Edition. Elsevier Health Sciences; 2014 Jun 25.

Composition of Dental Composites
MATRIX
FILLER
COUPLING
AGENT
INHIBITORS
ACTIVATOR
INITIATOR
SYSTEM
OPTICAL
MODIFIERS
MAJOR COMPONENTS MINOR COMPONENTS

Resin Matrix
Bis – GMA
800,000 centipoise
UDMA
800,000 centipoise
Aromatic
/
Aliphatic
Dimethacrylate
Monomers
Highly cross-linked, strong, rigid and
durable polymer structures
TEGDMA
5-30 centipoise
Continuous phase
75% Bis-GMA + 25% TEGDMA = 4300 centipoise
50% Bis-GMA + 50% TEGDMA = 200 centipoise
Greater the diluent property of monomer, greater
is the polymerization shrinkage
Developments include oxybismethacrylates, highly
branched methacrylates, silsesquioxane, and
cyclic siloxane monomers

Fillers
Crystalline Quartz
Lithium Glass Ceramics
Calcium Silicates
Glass Beads
Glass Fibers
Beta- eucryptite
Calcium Fluoride
Barium / Strontium Glass
Lanthanum Glass
PPF’s
Conventionally
Used
Fillers
Other
Fillers
Must be in high concentration to avoid deformation of
matrix
Employed to strengthen and reinforce the composite
Reduces polymerization shrinkage and thermal expansion
Refractive index of the filler must closely match that of
the resin for translucency of the composite
Skinner's Science of Dental Materials: 1982. 8th Edition
Filler size is considered while restoring cavities in the
anterior and posterior teeth.
Decreased water sorption

Fillers
Classification of Reinforcing Filler Particles by Size Range
Quartz fillers - hard to polish & abrade
opposing teeth
Filler particles of size range 0.06nm – 0.1nm
are produced from pyrolytic process (burning)
Nanoparticles enables higher filler loading
(upto 79.5%)
Nanoparticles - monodispersed /
nonaggregated / nonagglomerated silica
nanoparticles (20-25nm)
Nanoclusters wear by breaking off individual
primary particles rather than plucking out the
larger nanocluster particle.

Coupling Agent
• Filler particles - hydrophilic whereas Resin matrix - hydrophobic
• Organic Silicone compounds – Silane - is used to bond the two
together.
• Most common coupling agent used - g-methacryloxypropyl
trimethoxysilane
• Stress producing during bonding is transferred from one filler particle
to adjacent filler particles.
Materials Used In Dentistry. S. Mahalaxmi. 1 Ed, 2013 p280

Activator - Initiator System
Chemically Cured Light Cured
2 Paste System – Catalyst & Universal Paste
Universal Paste – Benzoyl Peroxide Initiator
Catalyst Paste – Tertiary Amine Activator
Mixing both forms free radicals initiating
polymerization
Uses ultraviolet light to initiate polymerization
(470 nm)
Photosensitizer used is Camphoroquinone (CQ)
Light cured composites contains CQ (0.2 wt%)
& an Amine activator
CQ adds a yellow tint to uncured composite
which neutralizes during curing.

Initiator System
• Camphoroquione (CQ) + Tertiary Amine used
• Photoinitiator system starts a free radical polymerization (FRP) process
• CQ absorbs light between 400 – 500 nm range (peak – 470nm)
• Type 1 photoinitiator molecules – absorbs at lower wavelength (400nm)
• CQ – yellowish tinge, not preferred in enamel shades
• Type 1 (phosphene oxide) - anterior composites
Dental Composite Materials for Direct Restorations. Vesna Miletic. Springer 2018

Inhibitors
• Added in small amounts to prevent spontaneous
polymerization of monomers
• Strong reactivity potential with free radicals formed
when composite is exposed to light briefly
• Inhibitor used is – Butylated Hydroxytoluene (0.01%)
Powdered BHT

Color Modifiers
• Metal Oxides added to composites to impart
visual coloration and translucency.
• Common color modifiers – Titanium Dioxide
and Aluminum Oxide (0.001 -0.007 wt%)
• Darker shades of composite transmit less light
than light shades
• Darker shades – thin layer placement or cured
for a long time

Polymerization
Additional Condensation
NO by-products formed Water & Alcohol as by-products
Chemically cured composites – Additional
Polymerization
BASED ON POLYMER STRUCTURE & COMPOSITION
Synthesized from polyfunctional monomers
Polymers constituted by repeating units linked by
functional units of esters, amides, urethane &
sulfides
Synthesized without the loss of small molecules with
the same chemical composition as monomers
Materials Used In Dentistry. S. Mahalaxmi. 1 Ed, 2013

BASED ON POLYMER CHAIN CONFIGURATION
LINEAR BRANCHED CROSS LINKED
Monomers linked together in one
continuous chain
Thermoplastic polymers
Can be shaped by heat / dissolved by
solvents
Examples : Polyethylene / Nylon
Side branches of linked monomer
molecules protruding from central
branch
Decreased crystallinity
Polymer molecules linked to each
other by covalent bonds at points
other than their ends.
Light cross linking – High Elasticity
Tight cross linking – High Rigidity
Cannot be shaped by heat or
dissolved by solvents

Advantages
Esthetics
Conservative Cavity Preparation
Reparability
Low Coefficient of Thermal
Conductivity

Polymerization Shrinkage Stress
Disadvantages
Technique Sensitive
Proper Contact & Contour
Isolation
Secondary Caries

Classification
Nano-Filled Composites
Heterogenous Micro-Filled
Homogenous Micro-Filled
Flowable Hybrid
Packable Hybrid
Nanohybrid
Hybrid (Large Particle)
Conventional
Hybrid (Mid-Filled)
Hybrid (Mini-Filled)
Based on Filler Size

Classification
Based on Manipulation Characteristics
Flowable Composites Packable Composites

Conventional Composites
(Lutz & Phillip, 1983)
75 – 80 % inorganic filler by weight
Extreme hardness of the filler particles
Rough Surface Texture
Poor Marginal Integrity
No Radio-Opacity
Color Instability due to high water sorption
Lutz F, Phillips RW. A classification and evaluation of composite resin systems. J Prosthet Dent, 1983;50: 480-8.

Micro-filled Composite
Colloidal Silica particles used instead of ground Quartz
Particles have small size but large surface area
Pyrolytic process - particle agglomeration - long chains –
viscosity increases
Used in low-stress and subgingival areas (Class III / IV)
Weak bond between composite and resin matrix –
Chipping Wear
Diamond burs used instead of tungsten carbide burs

Hybrid Composites
Mixed fillers – Microfine & Fine
Used in High stress sites
Fillers – Colloidal Silica + Ground Glass particles
containing heavy metals
75% glass particles / 10-20% colloidal silica

Nanofilled Composites
Filler particle size – 1 – 100 nm
Particles coated with γ-
methacryloxypropyltrimethoxysilane
Limits particle agglomeration / doesn’t effect viscosity
Superior optical properties and polishability
Some nanoparticles exist as loosely bound clusters
Above 100 nm, particles reduce translucency and depth of cure
Clusters not bonded to each other, reducing the mechanical properties

Flowable Composites
Modification of micro-filled and hybrid composites
Reduced filler loading = Lower Viscosity
High Anatomical Adaptability
Low wear & fracture resistance
Used in Class II and Class I restorations

Packable Composites
Thixotropy for placement and sculpting
Greater Depth of Cure
Lower polymerization shrinkage / Radiopacity and Wear rate
Better Marginal Adaptation
High flexural strength / modulus of elasticity / coefficient of thermal expansion
Used in Class II restorations

Applications
Cavity and crown
restoration
materials
Adhesive Bonding
Agents
Pit & Fissure
Sealants
Endodontic
Sealants
Bonding of
Ceramic Veneers
Cementation for
Crowns, Bridges &
other Fixed
Prostheses

Properties
Properties for polymer-based restorative materials are based on ISO 4049 (ANSI/ADA specification no. 27)
PHYSICAL
CHEMICALLY ACTIVATED COMPOSITES
• Working Time – 90 seconds (ADA sp. no. 27)
• Setting Time – 3 to 5 mins
LIGHT CURED COMPOSITES
• Polymerization starts when exposed to light
• Curing reaction continues even after 24 hours
• Studies report 25% carbon double bonds remain
unreacted
• Degree of conversion is said to be 75%
• About 50% of composite is fully cured in the first 10
minutes.
• Orange Covers should be placed to avoid pre-
polymerization of composite
• Carbon double bonds converted to single bonds
• Volumetric shrinkage
• Higher Filler – Low Shrikage (Hybrid / Fine particle)
(1-1.7%)
• Low Filler – High Shrinkage (Microfilled) (2-4%)
Working / Setting Time Polymerization Shrinkage

Compensation of polymerization shrinkage
Composite related Restoration related
Different resin matrices used / filler particle volume
Crystal monomers, oxyranes, spiro ortho esters,
epoxy polyol system, siloxane-oxirane
New systems show 40-50% less shrinkage in vitro
Ormocers show reduced polymerization shrinkage
Use of flowable composite as lining material to
absorb stress
Incremental Buildup
Using light curing methods that slow down the
reaction

Coefficient of thermal expansion (CTE)
Composite expands with change in temperature
The CTE of composite should be as close to tooth as possible
Generally composites have a higher CTE than that of tooth
Filler particles with low CTE are added to composite in order
to lower the CTE of the resin.
Microfilled composites - higher CTE
Controlling CTE is important to prevent marginal leakage
between tooth / restoration interface
Linear CTE of composites ranges between -
25–38 × 10^−6/°C and 55–68 × 10^−6/°C
CTE of enamel - 11.4 × 10^−6/°C
CTE of dentin - 8.3 × 10^−6/°C

Water Sorption
Oral environment is wet
Filler particles adsorb water
Silane bonds between resin and filler disturbed
Diluent monomers + hydroxyl groups in bis-GMA = increased water sorption
Water sorption = expansion of material
Microfilled composites – High resin content – High water sorption

Solubility
Inorganic filler ions may leech in the surrounding environment
This results in breakdown of the restoration
Inadequate light intensity and duration
Deeper areas of restoration is left with unpolymerized resin matrix
High Solubility = Low Wear / Abrasion resistance & color instability

Radio-Opacity
Detection of caries very difficult under radiolucent restorations
Glass ceramics with heavy metals used for radio-opacity
Ba Sr Zr
ADA specification no. 27 requires that composite resins have radiopacity
equivalent to 1 mm of aluminum, equal to that of dentin

• Strength
MECHANICAL PROPERTIES
Compressive strength of composites – 200 MPa to 300 MPa
Compressive strength of Nanocomposites – 450 MPa
Lower Filler Volume = Lower Strength
Flowable / Microfilled < Hybrid / Packable
Stress -> Coupling agent -> Weak Matrix -> Filler particles
Use of Cross Linked Polymer Matrix prevents crack formation

Wear Resistance
• Composites have low wear resistance
• Matrix is soft and gets worn off faster leaving the fillers exposed
Wear resistance of composites is dependent on various factors :
Fillers Porosity Tooth Position Finishing & Polishing
• Directly proportional
> filler volume
• Indirectly proportional
> particle size
• Softer filler particles >
less stress > matrix
• Air entrapment
during mixing or
placement of
composite
• Stress buildup within
the matrix
• Posterior teeth
• More Wear
• Carbides / Diamonds – Micro
Crack formation in resin
• Unfilled low viscosity resin over
the polished composite
reduces wear by 50%

Biocompatibility
Chemical Toxicity Marginal Leakage
Inadequately cured composite – Leeching – Long term
Pulpal Inflammation
Adequately cured composite – Less leeching – No Pulpal
Inflammation
Rarely – patients and dentists develop allergic reactions to
composite
Polymerization Shrinkage
Marginal Leakage
Bacterial Growth
Secondary Caries
Pulpal Reaction

Bisphenol – A – Toxicity
• Bisphenol – A is a xenoestrogen
• BPA and other endocrine-disrupting chemicals (EDCs) reproductive
anomalies / Anti-androgenic activities
• Testicular cancer, Decreased Sperm Count, and Hypospadias seen as a
result of EDC’s
• Effect of BPA and other EDC’s humans yet to be ascertained

Finishing & Polishing of composites
Adapting the restorative
material to the tooth
Removing the overhangs
shaping occlusal surface
Surface Roughness Bacterial Growth
Secondary Caries Surface Staining
Gingival
Inflammation
Finishing
Polishing Removing Surface
Irregularities

Factors involved in Finishing & Polishing
Environment Delayed / Immediate Finish Types of materials Surface coating and sealing
Dry or Wet field ?
Dry > Wet
Marginal Leakage
Structural / Chemical
Changes
Water Cooling
Immediate > Delayed
Delay – Increased
Marginal Leakage
Finishing & Polishing
should be done shortly
after placement
Finishing – 15 mins after
curing
Scalpel blade - Flash
Aluminum Oxide Discs in
proximal areas
Tungsten Carbide /
Diamond Burs for
blending
Fine / Extra Fine
polishing pastes
Silicone carbide
impregnated polishing
brushes
Microcracks formed
Surface polymerized
layer removed
Immediate > Delayed
Surface sealer / Low
viscosity resin with no
filler
Better marginal seal /
Microcracks filled

Repair of composites
The beauty of composites is such that they can be repaired easily. Considerations are made for old or new restorations :
Old Restoration New Restoration
As the restoration ages – fewer remaining unreacted
methacrylate groups remain
Oxygen inhibited layer on the resin on the surface
Freshly polished restoration still has 50% unreacted
methacrylate groups
Composite can still be added after finishing and polishing
Greater cross linking makes it difficult for the fresh
monomer to penetrate the matrix
Polished composite has filler particles free from silane
Silane bonding agents applied before repair in old
restorations
Strength of repaired composite is less than half
the strength of the original material

Acid Etching
• Used to enhance the formation of resin bond to
teeth
• 30-50% phosphoric acid – enamel rods dissolved
to a depth of 10-100um & smear layer removed
• Differential etching of rods and interprismatic
substance creates ‘enamel pits’ 4um in diameter
• Composite flows into the pits and forms ‘resin
tags’ for anchoring of resin to tooth surface
• More resin tags produced if unfilled bonding
agent applied prior to composite

α-Hydroxy Glycolic Acid vs Phosphoric Acid
35% α-Hydroxy Glycolic Acid 35% Phosphoric Acid
• Originally used in dermatology for skin peeling
procedures
• Less aggressive than Phosphoric acid
• Etching pattern was same as Phosphoric Acid
• Rubbing of Glycolic Acid increased the bond strength
to enamel
• elevates collagen synthesis and fibroblast proliferation
in, in vivo and in vitro studies
Enamel – Etching - 30s / Rinsing with distilled water - 30s
Dentin – Etching – 30s / Rinsing with distilled water – 30s /
Blot dry
• Increases surface roughness, wettability, hardness of
enamel
• In dentin, it demineralizes the peritubular and
intertubular dentin, exposing type I collagen fibrils
• Studies have shown that the depth of dentin
demineralization does not correlate with bonding
effectiveness
Enamel – Etching - 30s / Rinsing with distilled water - 30s
Dentin – Etching – 30s / Rinsing with distilled water – 30s /
Blot dry
Cecchin D, Farina AP, Vidal CM, Bedran-Russo AK. A novel enamel and dentin etching protocol using α-hydroxy glycolic acid: Surface property, etching pattern, and bond strength stuDies. Operative dentistry. 2018;43(1):101-10.

Degree of conversion (DC)
• The extent to which monomers react to form polymers or as the ratio of
C=C double bonds that are converted into C–C single bonds
• High degree of polymerization – optimal physical / mechanical properties &
biocompatibility
• Degree of conversion is never complete, reaches a degree of about 50%-
75% for conventional composites after curing
• 50% – 81% for bulk fill composites
• 24 hour post cure values – 68% - 86%

C – Factor (Configuration Factor)
• Tridimensional configuration of a cavity
• It is the ratio of bonded to unbonded surfaces in a cavity
• Higher C-factor = More Polymerization Stress
• Lower C-factor = Lesser Polymerization Stress

Factors effecting Degree of Conversion (DC)
Intrinsic Factors Extrinsic Factors
Resin Composition
Filler Composition
Photo-initiator System
• High viscosity of Bis-GMA impairs mobility during
polymerization – low DC values
• Increasing the translucency / Decreasing filler
content / Increasing filler size
• CQ + Tertiary Amines – 1 free radical
• Mono-acylphosphine oxide – 2 radicals
• Bis-acylphosphine oxide – 3 radicals
Light Curing Units
• Higher the intensity of light – Higher DC
• Quartz-tungsten-halogen lights – more heat, less
longevity
• 1st-2nd-3rd Gen LED curing lights – High intensity –
Less curing time – Higher DC (Total Energy Concept)
• High Intensity – High Contraction Stress
• Fix - variable intensity during curing cycle
Pre Heating
• Pros – decreases viscosity, enhances marginal
adaptation, and reduces microleakage
• Cons – Greater polymerization stress
Tauböck et al concluded pre heating bulk fill / conventional – reduce
polymerization shrinkage forces – DC remains same

Curing Lights
• Handheld devices with a light source and a rigid light guide made of fused optical fibres
• Upon scission of the initiator molecule (camphoroquinone) by visible light in the blue
spectrum, in the presence of the aliphatic amine activator, free radicals are produced
which initiate the polymerization.
• irradiance value measured as mW/cm2

Types of Light Curing Units
QTH Curing Units Plasma Arc Curing Units
Argon Laser Curing Units LED Curing Units

Quartz – Tungsten – Halogen Light
Halogen Cycle
Filter White Light
Wear of bulb
50 Hours till burnout
Turn Off Guidelines
30 – 60 secs (2mm thick increment)

Plasma Arc Curing Lights
More Intensity
Less Curing Time
2 tungsten electrodes
surrounded by xenon
gas
Expensive
Noisy Fan
Large
Non Battery Operated

Argon Ion Lasers
More Intensity
Less Curing Time
Laser with photons of same wavelength emitted
Expensive
Non – Portable
Narrow Emission Spectrum
Non Battery Operated

LED Curing Units
2-3 times more intensity Less Curing Time Solid State
Light weight
Battery Operated
Long Life No Filtering Needed
1st
Gen
2nd
Gen
3rd
Gen

1st Generation LED Curing Light
Individual LED ‘cans’
Wavelength – 470 nm (max)
Low Heat
Low Output

2nd Generation LED Curing Lights
LED Chips
Intense Luminous Output
Surpassed QTH & PAC
More Heat Production
Cooling through Heat Sinks

3rd Generation LED Curing Light
CQ imparts yellow which is
problematic when
producing light /
translucent shades
Co – initiators added to
reduce conc. of CQ
Co – initiators get activated
at shorter wavelengths
Additional LED emitters
added
Each LED pad emits
different wavelength
Polywave®

Modes of Curing
• Various methods to minimize or compensate polymerization shrinkage have been the target of clinicians
• One such approach is to slow the rate of curing, instead of continuous high intensity curing, to allow the
flow of composite from the uncured, nonstress areas to the cured, stressed areas.
Soft Start Pulse Delay Ramped Cure
• Pre-polymerization
using low intensity
followed by final
exposure at high
intensity of
photoactivation.
• Short durations of light
energy applied with no
curing (pulsed) in
between.
• A combination of both
the pulse delay and soft
start polymerization
results in ramped curing.

Blue Light Hazard
Acute – Immediate
& irreversible
retinal burning
Highest at 440 nm
Chronic –
accelerated retinal
ageing / Age
related macular
degeneration
Children, persons who have had cataract surgery, or
those who are taking photosensitizing medications
have a greater susceptibility for retinal damage.
Blue Light Blockers for Operators and Patients

Restorative Techniques
• When placing posterior composites, the use of small increments is
recommended by many authors for insertion and polymerization so
that the after effect of shrinkage stress can be reduced.
Horizontal Layering Technique Oblique Layering Technique Vertical Layering Technique
Incremental techniques in direct composite restoration. Veeramachaneni et al. J Conserv Dent. 2017 Nov-De (2016)

Horizontal Layering Technique
• Technique used in posterior teeth
• 3-4 layers of resin placed horizontally
• Each layer is 2 mm thick
• This technique tends to increase the C – Factor
• Increases shrinkage stresses between cavity
walls
Horizontal Layering Technique

Oblique Layering Technique
• Placing series of wedge shaped increments
• Each increment photocured twice
- first through the cavity walls
- then through the occlusal surface
• Technique reduces C – factor
• Prevents distortion of cavity walls Oblique Layering Technique

Vertical Layering Technique
• Vertical increments placed starting from one
wall
• Photocuring done from behind the cavity wall
• Reduces gap at gingival wall due to
polymerization shrinkage
• Reduces post operative sensitivity and
secondary caries
Vertical Layering Technique

Successive Cusp Buildup Technique
• Individual cusps built up till the level of the occlusal table
• Reduces finishing time by progressive reconstruction of natural
morphology
• Each cuspal increment is photocured before placing another
increment
• Placement of stains in the central groove done after buildup

Credits : Dr. Rizal Rizky Akbar
Private Practice
Indonesia

Innovations In Dental Composites
ORMOCERS
Organically modified ceramics
Molecule sized hybrid
structures
Inorganic co-polymers
Organic co-polymers
High Molecular Weight Flexible Relatively Low Viscosity Crosslinking Molecules
Abrasion resistance
Low polymerization shrinkage
Benefits
Limited cure shrinkage High Biocompatibility
Good Manipulation Excellent Esthetics
Rao DB, Chandrappa V. Recent advances in dental composites : An Overview (2019)

Fiber Reinforced Composites
Glass Fibers / Carbon Fibers / Aramid Fibers
Unidirectional / Weave Type / Mesh Type
Silane coupling agents used to
bond resin matrix and fibers
Strength / Stiffness Wear Resistance
APPLICATIONS
Periodontal Splinting
Post Trauma Splint
FPD’s
Reinforcing / Repairing Dentures
Fixed orthodontic retainers
Root Posts
Increased Fracture Resistance

Self Healing / Self Repairing Composites
Epoxy based systems contains Resin filled micro-capsules
Destroyed when epoxy
resin undergoes crazing
Releases resin
Fills Cracks
Reacts with catalyst
Polymerizes resin & repairs the crack

Smart Composites
• Based on external stimulus response
• These composites release :
Temperature pH Mechanical Stress Moisture
Fluoride Calcium Hydroxyl Ions
Into surroundings
(when pH is less than 5.5)

Bellglass HP
• Indirect Restorative Material
• Introduced by Belle de St. Claire in 1996
• Increased pressure increases rate of curing and decreases vaporization of
monomers
• Nitrogen gas increases the wear resistance / provides an oxygen free
environment increases polymerization rate
Increased polymerization Cured under
Temperature
138 °C
Pressure 29 psi Nitrogen gas

Self Adhering Composites
• Also called “Compobonds”
• Introduced by Kerr Corporation in 2009
• Self etching dentin bonding agents + Nano-filled-resins
Eliminates Bonding Stage Reduces Post-op. sensitivity Act as shock absorbers
Properties similar to Flowable Composites Longer Curing Time

Nanocomposites
Nanometric Fillers Smooth Finish / texture Less Biodegradation
Excellent mechanical properties Anterior / Posterior Use
Less Polymerization Shrinkage Less Cuspal Deflections
Reduced microfissures in enamel margins Less Marginal Leakage
Less Discolouration Reduced Post-Op Sensitivity

Antimicrobial Composites
Quaternary Ammonium Polyethyleneimine Silver Zinc Oxide Titania Chitosan
Leeching of antimicrobials into surroundings
Direct contact elimination of microbes
Fatemeh K. et al. (2017) reported use of adhesives incorporated
with silver nanoparticles showed greater bond strength
Fatemeh K, Mohammad Javad M, Samaneh K. The effect of silver nanoparticles on composite shear bond strength to dentin with different adhesion protocols. J App Oral Sci. 2017;25(4):367-73.

Calcium Phosphate Nanoparticles
Hydroxyapatite Phosphate
Dicalcium Phosphate Anhydrous
Tetra Calcium Phosphate
Fillers
Anhydrous Calcium Phosphate
Increases Stress Bearing Capacity
Enables Ion Release that inhibits dental caries
• Xu HH, Moreau JL, Sun L, Chow LC. Nanocomposite containing amorphous calcium phosphate nanoparticles for caries inhibition. Dental Materials. 2011 Aug 1;27(8):762-9
• Xie XJ, Xing D, Wang L, Zhou H, Weir MD, Bai YX, Xu HH. Novel rechargeable calcium phosphate nanoparticle containing orthodontic cement. International journal of oral science. 2017;9(1):24

Conclusion
• Patients’ demand for aesthetics, phenomenal developments in resin and filler technologies,
advances in nanotechnology, and clinical training in their use has made composite resins a
material of choice for direct restorative purposes.
• The wide range of colors, shades, translucencies, opacities, fluorescence, tones, viscosities, etc.,
available with the present generation of composite resins has enabled the clinician to provide a
restoration that mimics natural tooth structure and optimizes function as well.
• Further research is always an ongoing process to reduce or eliminate the drawbacks of composite
resins.

References
• Shenoy A, Nair CK. Phillips' Science of Dental Materials-E-book: A South Asian Edition. Elsevier
Health Sciences; 2014 Jun 25.
• Dental Composite Materials for Direct Restorations. Vesna Miletic. Springer 2018
• Materials Used In Dentistry. S. Mahalaxmi. 1 Ed, 2013
• Lutz F, Phillips RW. A classification and evaluation of composite resin systems. J Prosthet Dent,
1983;50: 480-8.
• Incremental techniques in direct composite restoration. Veeramachaneni et al. J Conserv
Dent. 2017 Nov-Dec (2016)
• Riva YR, Rahman SF. Dental composite resin: A review. InAIP Conference Proceedings 2019 Dec
10 (Vol. 2193, No. 1, p. 020011). AIP Publishing LLC.

References
• Xu HH, Moreau JL, Sun L, Chow LC. Nanocomposite containing amorphous calcium phosphate nanoparticles
for caries inhibition. Dental Materials. 2011 Aug 1;27(8):762-9
• Xie XJ, Xing D, Wang L, Zhou H, Weir MD, Bai YX, Xu HH. Novel rechargeable calcium phosphate
nanoparticle containing orthodontic cement. International journal of oral science. 2017;9(1):24
• Fatemeh K, Mohammad Javad M, Samaneh K. The effect of silver nanoparticles on composite shear bond
strength to dentin with different adhesion protocols. J App Oral Sci. 2017;25(4):367-73.
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