Dr. lama khaled El Banna Faculty of Oral and Dental Medicine Al – Azhar University operative dentistry part two

2. College of Dentistry
Operative Dentistry II
Direct Esthetic Tooth-Colored
Restorations -1-
Dr. Hazem El Ajrami

3. • The perception of the esthetic concept varies
among individuals. It is affected by the
personality, culture, education, experience and
self-image of an individual. In the present era,
an esthetic restoration is one that simulates the
natural teeth in color, translucency, shape,
size, form and contour, achieving what is
known as an invisible restoration that can't be
distinguished from tooth itself.

5. • Esthetic restorations are increasingly substituting
non-esthetic metallic restorations owing to:
Increased patient demand for esthetic tooth
-colored restorations.
The present era of adhesive and esthetic
dentistry has led to continued development of
technologies and materials required for esthetic
practice.
Conservation in cavity preparations for esthetic
restorations compared to unnecessary cutting in
tooth structure with non-bonded restorations.
Environmental awareness of mercury toxicity.

6. • Available esthetic tooth-colored restorations
are either direct; including resin composite,
glass ionomer and hybrid materials that
combines the benefits of both e.g. Resin
modified glass ionomer, Compomer and
Ionomer modified resin composite or indirect
including resin composite or ceramic inlays.

8. I. Resin Composite Restorations.
II. Glass lonomer Cements.
III. Hybrid materials between Composite
and GIC.

9. I. Resin Composite Restorations:
An esthetic restorative material should
satisfy many other requirements; including
satisfactory strength properties, wear
characteristics, insolubility and
biocompatibility. The material must also
remain color-stable and maintain the tooth
morphology to provide a lasting esthetic
restoration. Resin composites are currently
the direct restorative material that best
fulfills the requirements of excellent
esthetics and durability.

10. • The term composite refers to a material that is
composed of two or more constituents that are
insoluble in each other. This combination
produces a material with superior or
intermediate properties to those of the
individual constituents. Dental resin composites
evolved from mixing the silicate glass particles
with an acrylic resin monomer. Since their
introduction by Bowen in 1966, resin composite
restoration has undergone many modifications
and is currently being widely used in treatment
of anterior as well as posterior teeth.

11. • Composition and types:
Resin composites consist of an organic
resin matrix and inorganic filler particles
bonded together by an organic coupling
agent.
A. The organic resin matrix:
It is the continuous phase to which other
ingredients are added. It comprises:

13. 1. High molecular weight monomers:
Most systems are based on Bisphenol
glycidylmethacrylate (BisGMA) monomer,
some are based on Urethane Dimethacrylate
(UDMA) monomer and others incorporate a
mixture of both BisGMA and UDMA. Both
resins are extremely viscous. This decreases
the amount of filler that can be incorporated
into the monomer.

14. 2. Low molecular weight monomer:
A low-viscosity monomer e.g. Triethylene
Glycol Dimethacrylate (TEG-DMA) is thus
added as a diluent to provide more fluidity
for the material. It decreases the viscosity,
increases the wettability and results in
improved mechanical properties. However, it
results in more polymerization shrinkage and
increases the affinity to water sorption as it is
more hydrophilic.

15. 3. Activator/initiator system:
Matrix monomers in direct resin
composite systems could be polymerized
either through chemical-curing (auto- or self-
cure), photo-chemical through light
activation or dual-cured through both
mechanisms.

16. • Chemically-polymerized systems comprises
two-paste system. One paste contains the
activator, which is frequently an aromatic
tertiary amine; the other paste contains an
initiator, such as benzoyl peroxide. When the
two pastes are mixed together, the tertiary
amine activates the benzoyl peroxide causing
it to split into two free radicals and initiates a
chain of additional polymerization reaction.

17. • Light-polymerized systems comprise one paste
only. The paste contains a photo-sensitive
chemical e.g. camphorquinone (diketone),
which absorbs visible light at specific
wavelength which excites an aliphatic tertiary
amine to activate the benzoyl peroxide
initiator.
• Dual-polymerized systems combine both
versions. They start by photo-chemical
reaction and continue by a chemical process to
ensure curing of sites not reached by light.

18. 4. Inhibitors:
The monomer should contain an inhibitor
like hydroquinone that neutralizes free radicals
and prevents spontaneous polymerization. This
increases the shelf-life and the working time of
the material.
5. Pigments:
The monomer also contains metal oxides
pigments to provide composite with different
shades and opacity to match the color and
translucency of the tooth.

20. B. The inorganic fillers:
The fillers are the dispersed phase which
is added to improve the strength, wear
resistance and optical characteristics of the
material. They decrease the polymerization
shrinkage, coefficient of thermal expansion
and water sorption. However, they increase
the viscosity and adversely affect wetting.

21. • Types of filler:
It is formed of inorganic silica either in
crystalline form such as quartz or in non-
crystalline form such as glass. Crystalline forms
are stronger and harder but difficult to finish
and polish. Therefore, most current composites
comprise silicate glass. Barium, zinc and
yttrium ions are added to produce radiopacity of
the filler particles. Radiopacity of a restorative
material is a desirable property to allow for x-
ray detection of overhangs and recurrent decay.

23. • Filler particle size and loading:
As the particle size decreases, the
polishability and wear resistance of
composites increases. While as the filler
loading (% of filler content) increases, the
mechanical properties of composite is
enhanced. Thus, the ideal composite would be
highly filled with very small particles.
Unfortunately, loading a composite with large
amount of small filler is difficult because the
large surface area causes a marked increase in
viscosity.

24. • The early composites were macro-filled, with
average particle size 8-10 µm and filler
loading of 75-80 %wt. They were non-
polishable, because during polishing, the
weaker organic matrix will abrade more,
leaving the hard fillers in place and producing
a rough surface. This type of composite is
outdated and not used anymore.

25. Before polishing
After polishing

26. • Manufacturers produced next generations of
composites with decreased particle sizes.
Micro-filled composites have particle size of
0.02-0.04 µm. However, the percentage filler
loading is 35-50 %wt. They are polishable,
have smooth and lustrous surface, with good
wear resistance due to small filler size, but
with low mechanical properties due to high
resin content.

27. • Their use is thus restricted to non-stress
bearing areas where esthetics and smoothness
of restoration is of prime importance and as
veneers for other composites. Their low
modulus of elasticity (flexible material) makes
them suitable for use in cervical lesion where
tooth flexure may cause debonding of rigid
composites.

28. • There are two types of micro-filled
composites; homogenous and heterogeneous.
In homogeneous micro-filled composite, the
micro-fillers are added directly to the resin.
However, to increase the filler content and
overcome the problem of increased viscosity,
homogeneous micro-fill composites are heat-
cured and ground to 1-20 µm sized powder
which is then mixed with the monomer that
also contains micro filler particles.

29. Heterogeneous Micro-fill

30. • These pre-cured particles becomes chemically
bonded with the new material providing
islands of better properties which can, in the
same time, be finely polished. This variation is
known as heterogeneous micro-filled or
organic filler composite.

31. • Large Particle (Macro-fill):
Higher fracture toughness.
Higher stiffness.
Low thermal expansion.
Less polishable.
More superficial stains.

32. • Small Particle (Micro-fill):
Highly polishable.
Less superficial stains.
Lower fracture toughness.
More flexible.
Increased thermal expansion.

33. • Hybrid composites have combination of
colloidal silica micro-fillers and glass macro-
fillers. The combination of filler sizes allow
filler loading up to 80%wt. They combine the
advantages of both, where satisfactory
mechanical properties are combined with
adequate esthetics and good surface
characteristics. They are thus universal in their
use. The largest particle size range is used to
define the hybrid type, e.g. mini-filled hybrid,
micro-filled hybrid.

34. • Recently introduced nano-filled composites
have nano-fillers that range in size from 0.005-
0.01 µm. The fillers are so small that they fit
between several polymer chains of the matrix.
The filler size is below the wavelength range
of visible light, thus they do not produce
scattering nor significant absorption of light.
This will lead to thorough polymerization of
the resin matrix.

35. • Non-silicate fillers are used because they are
effectively invisible to light and they do not
tend to agglomerate like silica-based fillers.
Nano-fillers permit achieving high filler
loading while still maintaining workable
consistency.

36. Thank You