Dental composite restorative material

1. Dental
Composites
This Photo by Unknown author is licensed under CC BY-SA.

2. Contents
• Introduction
• History
• Applications
• Classification
• Composition and function

3. Introduction
• The term “composite material” refers to a material made up of at least
two distinct components, insoluble in each other, which produce a
material with different, often better, characteristics than the components
alone.

4. • Composite—In materials science, a 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; also a term used in dentistry to describe a dental
composite or resin-based composite. ( Philip's )

5. History
Esthetic restoration material
Silicate Cements
Unfilled resin – Polymethylmethacrylate ( PMMA )

6. Crosslinking resin and coupling agent added – Bowen
.(Oraganosilanes )
Fillers added - quartz

7. • Dental composite—Highly cross-linked polymeric materials reinforced by a
dispersion of amorphous silica, glass, crystalline, mineral, or organic resin
filler particles and/or short fibers bonded to the matrix by a coupling agent.
(Philip's)
• Composed of three main components -
Matrix Filler
Coupling
agents

9. • In addition ,
Activator – initiator system
Inhibitor

10. Composition
1. Resin matrix - Dimethacrylate monomer ( Bis – GMA , UDMA , TEGDMA)
2. Filler - “soft glass” and borosilicate “hard glass”, fused quartz, aluminum silicate,
lithium aluminum silicate, ytterbium fluoride, and barium (Ba), strontium (Sr),
zirconium (Zr), and zinc glasses.
• The most commonly used glass filler is barium (Ba) glass.
3. Coupling agent – organosilanes = γ-methacryloxypropyl trimethoxysilane
4. Activator -
• Chemically activated / Chemical cure
• Light activated / Light cure
• Dual cure

11. Chemical cure -
• Base paste contains—benzoyl peroxide initiator
Catalyst paste—tertiary amine activator (i.e. N, N-dimethyl-p-toluidine)
Visible light cure -
• Photoinitiator: Camphorquinone 0.2 wt.%
• Amine accelerator: Dimethylaminoethyl-methacrylate (DMAEMA 0.15 wt.%)
5. Inhibitor - Butylated hydroxytoluene (BHT)
6. Optical modifiers - titanium dioxide ,aluminum oxide

13. Classification
• Based on Particle ( filler ) size -
1. Macrofillers (10-100 µm)
2. Midifillers (1-10 µm)
3. Minifillers (0.1-1 µm)
4. Microfillers (0.01-0.1 µm)
a. Homogenous — contains only microfillers
b. Heterogenous — microfillers combined with prepolymerized fillers
— splintered prepolymerized particles
— spherical prepolymerized particles
c. Agglomerated — microfiller sintered to form larger filler complexes
5. Nanofillers (0.005–0.01 µm)
6. Hybrid (range of sizes which usually includes micro or nanofillers with macro, midi or
mini fillers

15. Based on curing mechanism
• 1. Light activated
• 2. Chemical activated ( self cure)
• 3. Dual cure resin

16. Based on viscosity
• Conventional
• Flowable
• Packable

17. Functions of individual components
1. Resin matrix - This matrix forms a continuous phase in which the reinforcing filler
is dispersed .
2. Filler -
• Reinforcement
• Reduction of polymerization shrinkage
• Reduction in thermal expansion and contraction
• Control of workability / viscosity
• Decreased water sorption
• Imparts radiopacity

18. 3.Coupling agent –
• to bond the filler particles to the resin matrix
• prevent water from penetrating the filler-resin interface.
4.Activator - provides the free radical supply
Initiator – acts on the activator to release the free radicals.
5.Coupling agent -
filler particles be bonded to the resin matrix. This allows the more flexible polymer
matrix to transfer stresses to the higher-modulus
(more rigid and stiffer) filler particles.

19. • A curing system—Chemical or light curing chemicals.
• Inhibitors (0.01%)—Prevents premature polymerization, e.g.
butylated hydroxytoluene (BHT).
• UV absorbers—to improve color stability
• Opacifiers—(0.001 to 0.007%) e.g. titanium dioxide and aluminum
• Color pigments—to match tooth color

20. Uses of composite resins
• Dental applications for resin-based composites include
1. Cavity and crown restoration materials,
2. Adhesive bonding agents,
3. Pit and fissure sealants,
4. Endodontic sealants,
5. Bonding of ceramic veneers,
6. Cementation for crowns, bridges, and other fixed prostheses.

24. BONDING OF PORCELAIN VENEERS

25. CEMENTATION OF CROWNS AND BRIDGES

26. FILLERS
• Filler size The size of the fillers affect the surface smoothness and the wear
resistance. The smaller the fillers the greater the surface smoothness.
Microfilled composites have the best surface smoothness and lowest wear.
• Filler loading Filler loading refers to the amount of fillers that can be
practically incorporated into the resin. The amount of filler that can be
added depends on the type of filler and the purpose for which it is intended.
Microfillers thicken the resin quickly
• Refractive index For esthetics, the filler should have a translucency similar
to tooth structure. To achieve this, the refractive index of the filler should
closely match that of the resin.

27. • Particle size distribution Most modern hybrid composites have particles
range in size from 0.01 to 10 µm. Microfillers are usually in the range of 0.01
– 0.07 (average 0.04 µm). If a single particle size is used, a space will exist
between the particles. Smaller particles can then fill-up these spaces, thus
increasing the filler content

28. BASED ON FILLER PARTICLE SIZE
1. MACRO FILLED COMPOSITE -
• 10- 100 µm size
• Conventional composite , Traditional composite
• Better mechanical properties , decreased water sorption , polymerization shrinkage
• Roughening of the surface as a result of the selective abrasion of the softer resin matrix
surrounding the harder filler particles.
2. SMALL PARTICLE COMPOSITE -
• 0.1-10 µm size
• More polishable than traditional composite
• Durable, appearance – Anterior restorations

29. 3.MICROFILLED COMPOSITE -
• 0.01 - 0.1 µm size
• Solves surface roughness and low translucency of above 2 types.
• Small size , high surface area – limited filler loading. ( less than traditional and
small particle filled ).
• Bond b/w composite particle and matrix is weak – prone to wear. ( not for stress
bearing areas)
• Inferior physical and mechanical property as compared to Traditional composite.
• Class III and Class V restoration.

30. 4. HYBRID COMPOSITE -
• Microfine ( 0.01 - 0.1 µm ) plus Fine/small particle ( 0.1-10 µm )
• Better surface smoothness than small particle composite.
• Better mechanical property .
• High stress area plus esthetic requirement high - Anterior , class IV

31. 5. NANOFILLED COMPOSITE -
• Nanoparticles ( 1- 100 nm)
• Greater filler loading of up to 79.5% vol.
• Polishability , optical properties like that of microfilled.
• But better mechanical properties than microfilled.
• Use – Posterior , stress bearing areas

32. CHEMICAL / SELF CURE RESINS

33. Light cure resin
Composite syringe
Primer and adhesive
Etchant

34. Curing lamps

37. BONDING OF COMPOSITE TO TOOTH
Micromechanical

40. Polymerization shrinkage
• As a result of the polymerization process, the
liquid or resin is converted into a solid, which
results in a density change that reduces the
overall volume.
• These phenomena can lead to internal stresses
and stresses at the margins of the restoration.
These stresses, over time, can lead to marginal
leakage and secondary caries.
• The only known methods to reduce shrinkage
are to reduce the number of methacrylates
or utilize a new polymerization chemistry.
• The other strategy is to increase the filler level,
thereby reducing the overall number of
methacrylates but it can increase viscosity
overall.