Amalgam in comparison to composite in dnetistry

1. Presented by
Dr.Chandana Menon
1st MDS

2. AMALGAM vs COMPOSITE
 Introduction
 Definition
 History
 Classification
 Composition
 General Properties
 Salient Properties
 Indications
 Contraindications
 Advantages
 Disadvantages
 Recent Advances
 Toxicity and Biocompatibility
 Conclusion
 References

3. BIOMATERIALS
Direct Restorative Biomaterial Indirect restorative Biomaterial
 Amalgam
 Liners and Bases
 Pit and fissure sealants
 Composites
 Glass Ionomers
 Impression materials
 Cast metal restorations
 Dental Cements
 Machined restorations

4. • Amalgam is an alloy that contains mercury
• Metal particles and mercury diffuse into each other on mixing causing precipitation
of compounds within the mercury
• Content of liquid mercury decreases due to formation of precipitation and the
mixture hardens amalgamation

5. • Amalgam has been the traditional material for filling cavities in posterior teeth for
the last 150 years .
• Due to its effectiveness and cost, amalgam is still the restorative material of choice
in certain parts of the world.

6. • In recent times, however, there have been concerns over the use of amalgam
restorations , relating to the mercury release in the body and the environmental
impact following its disposal.
• Resin composites have become an esthetic alternative to amalgam restorations
and there has been a remarkable improvement of its mechanical properties to
restore posterior teeth.

7. – An alloy of mercury silver
copper and tin, which may also contain
palladium, zinc and other elements to improve
handling characteristics and clinical performance
– An alloy of silver copper
and tin that is formulated and processed in the
form of powder particles or compressed pellets.
Phillips’ Science of dental
materials, 11/e Anusavice.
According to Sturdevant’s:
In materials and science word composite refers
to a solid formed from two or more distinct phases
that have been combined to produce properties
superior to or intermediate to those of individual
constituents.

8. • First use recorded in Chinese literature- 659AD
• Crawcours brothers introduced concept of
amalgam in 1833
• Amalgams used today are based on the
formulation published by G V Black in 1895.
• Modifications of GV Black’s formulation were
introduced in early 1960s.
• First half of 20th century- silicates (release of
fluorides)
• Acrylic resins replaced silicates due to tooth-like-
appearance, insolubilty in oral fluids,ease of
manipulation and low cost.
• They have poor wear resistance and tend to shrink
severely during curing.
• Excessive thermal expansion and contraction
caused further stresses.

10. 1. According to number of alloy metals
 Binary alloys (Silver-Tin)
 Ternary alloys (Silver-Tin-Copper)
 Quaternary alloys (Silver-Tin-Copper-Indium)
2. According to whether the powder consist of
unmixed or admixed alloys.
 One alloys
 One or more alloys or metals added to basic
alloy
Eg: Adding Copper to a basic binary silver tin alloy
1. Classification by Filler Particle Size
 Traditional (large particle)
 Hybrid (large particle)
 Hybrid (midifilled)
 Hybrid (minifilled)
 Nanohybrid
 Homogenous microfilled

11. 3. According to Shape of the Powdered Particles
 Spherical (smooth surfaced spheres)
 Irregular spindles to shavings (lathe-cut)
 Spherical with irregular surfaces (spheroidal)
4. According to Powder Particle Size
 Microcut
 Fine cut
 Coarse cut
 Heterogenous microfilled
 Nanofilled composites
2. Classification of composites based on Manipulation
Characteristics
 Flowable
 Condensable(Packable)
 Bulk fill
- Phillips’ Science of dental materials

12. Particles of spherical alloy for dental
amalgam (×500).
Particles of conventional
lathe-cut alloy for dental amalgam (×100).
Typical admix high-copper
alloy powder (×500).

13. 5. According to Copper Content of
the Powder
 Low copper alloys [4% or less]
 High copper alloys [More than
10%]
 Admixed
6. According to Addition of Noble
Metals
 Palladium (most effective)
 Gold
 Platinum
3. According to SKINNER’S
 Traditional composites (Macrofilled) 8-12µm
 Small particle filled composite – 1-5µm
 Microfilled composite – 0.04 – 0.4 µm
 Hybrid composite – 0.6 – 1 µm

14. 7. According to compositional changes of
succeeding generations of amalgam.
 First generation amalgam was that of G. V
Black i.e. 3 parts silver one part tin (peritectic
alloy).
 Second generation amalgam alloys -
 3 parts silver,
 1 part tin,
 4% copper (to decrease the plasticity and to
increase the hardness and strength.
 1 % zinc, acts as a oxygen scavenger and to
decrease the brittleness.
4.According to STURDEVANT
Classification of composites based on the filler particle
size
 Megafill- in this one or two large glass inserts 0.5 to 2
mm in size are placed into composites at points of
occlusal contact.
 Macrofill- particle size range between 10 to 100 µm
in diameter
 Midifill - particle size range between 1 to 10 µm in
diameter, also called traditional or conventional
composites.

15.  Third generation: First generation + Spherical
amalgam – copper eutectic alloy.
 Fourth generation: Adding copper upto 29% to
original silver and tin powder to form ternary
alloy. So that tin is bounded to copper.
 Fifth generation. Quaternary alloy i.e. Silver, tin,
copper and indium.
 Sixth generation (consisting eutectic alloy).
 Minifill - particle size range between 0.1 to
1 µm in diameter
 Microfill - particle size range between 0.01
to 0.1 µm
 Nanofill - particle size range between
0.005 to 0.01 µm

16. 8.According to Presence of Zinc.
 Zinc containing (more than
0.01%).
 Non zinc containing (less than
0.01%).
5. Based on method of cure
 Self-cure or chemical cure
 Light cure
-visible light
-UV light
 Dual cure

17. COMPOSITION
Amalgam constitutes of :
 Mercury
 Silver
 Tin
 Copper
 Zinc
 Indium/Palladium
Composite mainly consists of :
 Matrix
 Filler
 Coupling agent
Additionally:
 Activator initiator system
 Inhibitors

18. Composite is supplied as-
• Chemical cure - syringes or tubes
2 paste system
(base paste and catalyst paste)
- No control over working time
• Light cure- Single paste in a lightproof syringe or
Compules
- Light source for activation
- Control over working time
• Dual cure- Two light cure pastes in tubes or
syringes
MODES OF AVAILABILITY
Amalgam is supplied as-
• Mercury and alloy powder
• Reusable capsules with pestle
• Preproportioned capsule with pestle
• Self-activating capsules

19. SETTING REACTION
Amalgam sets by dissolution and precipitation
reaction (Amalgamation).
Composite sets by polymerization reaction

20.  Conventional Amalgam Alloys: (G.V. Black’s: Silver- tin alloy or Low copper alloy).
• Low copper alloys are available as comminuted particles (Lathe -cut and Pulverized)
and spherical particles.
• Low copper composition:
 Silver : 63-70%
 Tin : 26-28%
 Copper : 2- 5%
 Zinc : 0-2%

21. Silver:
• Constitutes approximately 2/3rd of conventional amalgam alloy.
• Contributes to strength of finished amalgam restoration.
• Decreases flow and creep of amalgam.
• Increases expansion on setting and offers resistance to tarnish.
• To some extent it regulates the setting time.
Role of individual component

22. Tin:
• Second largest component and contributes ¼th of amalgam alloy.
• Readily combines with mercury to form gama-2 phase, which is the weakest
phase and contributes to failure of amalgam restoration.
• Reduce the expansion but at the same time decreases the strength of
amalgam.
• Increase the flow.
• Controls the reaction between silver and mercury.
• Tin reduces both the rate of the reaction and the expansion to optimal values.

23. Copper:
• Contributes mainly hardness and strength.
• Tends to decrease the flow and increases the setting expansion
Zinc:
• Acts as scavenger of foreign substances such as oxides.
• Helps in decreasing marginal failure.
• The most serious problem with zinc is delayed expansion, because of which zinc free
alloys are preferred now a days.
Indium/Palladium:
• They help to increase the plasticity and the resistance to deformation.

24. • To overcome the inferior properties of low copper amalgam alloy -- shorter working
time, more dimensional change, difficult to finish, set late, high residual mercury, high
creep & lower early strength, low fracture resistance
• Youdelis and Innes in 1963 introduced high copper content amalgam alloys.
• They increased the copper content from earlier used 5% to 12%.
• Copper enriched alloys are of two types:
1) Admixed alloy powder.
2) Single composition alloy powder.

25.  Admixed alloy powder:
• Also called as blended alloys
• Contain 2 parts by weight of conventional composition lathe cut particles plus one part by
weight of spheres of a silver-copper eutectic alloy (homogeneous mixture of substances that
melts or solidifies at a single temperature that is lower than the melting point of any of the
constituents)
• Made by mixing particles of silver and tin with particles of silver and copper.
• The silver-tin particle is usually formed by the lathe cut method, whereas the silver-copper
particle is usually spherical in shape.

26. • Amalgam made from these powders are stronger than amalgam made from lathe cut
low copper alloys because of strength of Ag-Cu eutectic alloy particles.
• Ag-Cu particles probably act as strong fillers strengthening the amalgam matrix.
• Total copper content ranges from 9-20%.
Silver-69 %
Copper-13 %
Tin-17 %
Zinc-1 %
Admixed alloy powder: Composition

27.  Single composition alloy (Unicomposition):
• It is so called as it contains particles of same composition.
• Usually spherical single composition alloys are used.
• As lathe cut, high copper alloys contain more than 23% copper.
• Ternary alloy in spherical form, silver 60%, tin 25%, copper 15%.
• Quaternary alloy in spheroidal form containing Silver: 59%, copper 13%, tin: 24%,
indium 4%

28. Basic setting reaction of amalgam
AMALGAMATION REACTION/ SETTING REACTION:

29. AMALGAMATION REACTION/ SETTING REACTION:
 Low copper conventional amalgam alloy
• Dissolution and precipitation
• Hg dissolves Ag and Sn from alloy
• Intermetallic compounds formed

31. Conventional Low Copper Amalgam
• This type of amalgam sets by the reaction of silver–tin from silver–tin particles
with mercury to produce two reaction product phases:
(i) the silver–tin phase gamma-1 phase and
(ii) the tin–mercury phase gamma-2 phase

32. Gamma-1 Phase (Γ1)
• The silver–mercury (Γ1) crystals are generally small and forms most of the matrix. This
phase has intermediate corrosion resistance.
Gamma-2 Phase (Γ2)
• Tin–mercury (Γ2) reaction product crystals are long and blade-like, penetrating
throughout the matrix. Although they constitute less than 10% of the final composition,
they form a penetrating matrix because of intercrystalline contacts between the blades
• This phase is prone to corrosion in clinical restorations, a process that proceeds from
the outside of the amalgam, along the crystals, connecting to new crystals at
intercrystalline contacts.

33. • This process produces penetrating corrosion that generates a porous and spongy amalgam
with minimal mechanical resistance. Two key features of this degradation process are:
i. The corrosion-prone character of the tin-mercury phase gamma-2 phase(Γ2).
ii. The connecting path formed by the blade-like geometry of the crystals.
Both these are eliminated by the use of more copper in the initial composition.

34.  High Copper Amalgam
High-copper amalgams set in a manner similar to low-copper amalgams except
that tin-mercury reactions are suppressed by the preferential formation of copper-
tin phases instead.
a) High Copper Admixed Alloy
In high copper admixed alloys the reaction takes place in two steps.
There is elimination of gamma-2 phase, which is the weakest phase.

35. • b) High Copper Unicompositional Alloys
• The setting reaction of unicompositional alloy also eliminates the formation of the
weak gamma-2 phase and the phases involved are
• Setting reaction of unicompositional high copper amalgam alloy
[Ag3Sn + Cu3Sn] + Hg → Ag2Hg3 + Cu6Sn5 +unreacted [Ag3Sn + Cu3Sn]

36. 1. Matrix- A highly cross-linked polymeric resin matrix reinforced by a dispersion of
glass, silica crystalline
2. Filler- Metal oxide or resin-reinforcing filler particles or their combinations and/or
short fibres,
3. Coupling agents- Bonded to the matrix by silane coupling agents.
4. Additionally activator-initiator system- converts resin into hard, durable restoration.
inhibitors- extend storage life and working time

38. 1. MATRIX
• Blend of aromatic and/or aliphatic dimethacrylate monomer such as bis-GMA and
UDMA
• This matrix forms a continuous phase in which the reinforcing filler is dispersed.
• Because of the large molecular volume of these monomers, polymerization
shrinkage can be as low as 0.9%

39. • UDMA and bis-GMA are highly viscous- use varying proportions of lower-molecular-
weight highly fluid monomers such as triethylene glycol dimethacrylate (TEGDMA, 5 to
30 centipoise)
• Generally the greater the proportion of these “diluting” monomers, the greater the
polymerization shrinkage and the greater the risk of eventual leakage in marginal gaps
and the problems that may result.

40. 2.FILLER
• Various transparent mineral fillers are employed to strengthen and reinforce
composites as well as to reduce curing shrinkage and thermal expansion (generally
between 30% to 70% by volume or 50% to 85% by weight of a composite).
• They are “soft glass” and borosilicate “hard glass”, fused quartz, aluminum silicate,
lithium aluminum silicate (beta-eucryptite, which has a negative coefficient of
thermal expansion), ytterbium fluoride, and barium (Ba), strontium (Sr),
zirconium (Zr), and zinc glasses.

41. • Quartz- advantage of being chemically inert but it is also very hard, making it abrasive to
opposing teeth or restorations, difficult to grind into very fine particles; thus, it is also
difficult to polish.
• Amorphous silica- not hard,reduce abrasiveness and has high polishability.
• For acceptable esthetics-translucency of a composite restoration must be similar to that
of tooth structure.
• bis-GMA and TEGDMA, the refractive indices are approximately 1.55 and 1.46,
respectively, and a mixture of the two components in equal proportions by weight
yields a refractive index of approximately 1.50.

42. • A study was done on assessing selected organic fillers’ impact (ground coffee
waste (GCW), walnut shell (WS), brewers’ spent grains(BSG), pistachio shell (PS),
and chestnut (CH)) on the physicochemical and mechanical properties of silicone-
based materials.
They altered the mechanical properties:
• Reduced density,resiliency and tensile strength.
• But they could have potential applications as packaging materials due to their
degradability and lack of negative impact on the environment.
Article (2021)
Evaluation of the Impact of Organic Fillers on SelectedProperties of Organosilicon Polymer
Sara Sarraj * , Małgorzata Szymiczek , Tomasz Machoczek and Maciej Mrówka

43.  FUNCTION OF FILLERS
• Reinforcement- increases physical and mechanical properties that determine clinical
performance and durability, such as compressive strength, tensile strength, modulus of
elasticity (i.e., stiffness or rigidity), and toughness.
• Volume fraction of filler -70%, abrasion and fracture resistance are raised to levels
approaching those of tooth tissue, thereby increasing both clinical performance and
durability.

44. • Reduction of polymerization shrinkage/contraction- Increased filler loading
reduces curing shrinkage in proportion to filler volume fraction.
• Ranges from slightly less than 1% up to about 4% by volume.

45. • Reduction in thermal expansion and contraction-Increased filler loading
decreases the overall coefficient of thermal expansion of the composite.
• Control of workability/viscosity- Fluid liquid monomer + filler → a paste.
• The more filler, the thicker is the paste.
• Filler loading, filler size, and the range of particle sizes and shapes all affect
markedly the consistency of a composite paste- affects clinical manipulation and
handling properties.

46. • The filler loading in resin dental composite generally accounts for between 35-70
volume % or 50-85 weight % of composite .
• The filler has several major roles in ultimate restoration, including enhancing
modulus, radiopacity or altering thermal expansion behavior .
• Theoretically, increasing filler content could also minimalize polymerization
shrinkage and its consequence contraction stress due to reducing the organic phase
volume .
The influence of filler amount on selected properties of new experimental resin dental composite
Kinga Bociong, Agata Szczesio, Michal Krasowski and Jerzy Sokolowski
From the journal Open Chemistry
https://doi.org/10.1515/chem-2018-0090

47. • Flexural strength and modulus, hardness as well as fracture toughness, are
influenced by both filler morphology and filler loading.
• Tanimoto Y. et al, also demonstrated that the bending properties: such as
maximum stress and bending modulus, increase with filler content.
Article
The influence of filler amount on selected properties of new experimental resin dental composite
Kinga Bociong, Agata Szczesio, Michal Krasowski and Jerzy Sokolowski
From the journal Open Chemistry (September 18, 2018)

48. • Decreased water sorption- Increased filler loading decreases water sorption.
• Absorbed water softens the resin and makes it more prone to abrasive wear and staining.
• Imparting radiopacity.- Resins are inherently radiolucent.
• Radiopacity is most often imparted by adding certain glass filler particles containing
• heavy metal atoms, such as Ba, Sr, or Zn, and other heavy-metal/heavy-atom compounds
such as YbF3, which strongly absorb x-rays.

49. • The most commonly used glass filler is barium (Ba) glass.

50. COUPLING AGENT
• It is essential that 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.
• The chemical bond between the two phases of the composite is formed
by a coupling agent

51. • Is a difunctional surface-active compound that adheres to filler particle surfaces and
also coreacts with the monomer forming the resin matrix.
• Impart improved physical and mechanical properties and inhibit leaching by
preventing water from penetrating along the filler-resin interface.

52. • Titanates and zirconates -coupling agents,
• Organosilanes—such as γ-methacryloxypropyl trimethoxysilane—are used most
commonly
• In the presence of water, the methoxy groups (–OCH3) are hydrolyzed to silanol (–Si–
OH) groups, which can bond with other silanols on the filler surfaces by forming
siloxane bonds (–Si–O–Si–).
• The organosilane methacrylate groups form covalent bonds with the resin when it is
polymerized, thereby completing the coupling process.
• Proper coupling by means of organosilanes-extremely important to the clinical
performance of resin-based composite restorative materials.

53. ACTIVATION/INITIATION SYSTEM
Chemical cured or Self-Cure Resins
• Both monomethacrylate and dimethacrylate monomers polymerize by the addition
polymerization mechanism initiated by free radicals.
• Free radicals can be generated by chemical activation or by external energy activation
(heat, light, or microwave).
• Chemically activated resins (chemically cured composites) are supplied as two pastes
a) benzoyl peroxide initiator
b)aromatic tertiary amine activator (egg: N,N-dimethyl-p-toluidine)

54. Amine+ benzoyl peroxide Free radicals
Addition polymerization
• During mixing in chemical activation there is incorporation of air into the mix
resulting pores that weaken the structure and trap oxygen which inhibits
polymerization during curing.

55. • Formation of oxygen- inhibited layer
• Oxygen is diffused into the resin and is consumed by radicals formed resulting in
an unpolymerized surface layer.

56. Photochemically Activated (Light-Cure) Resins
• To overcome the problems of chemical activation
• Resins that do not require mixing ,by using a photosensitive initiator system and a light
source for activation.
• First light-activated systems-UV light to initiate free radicals.

57. • UV light–cured composites have been replaced by visible blue-light–activated
systems
 greatly improved depth of cure,
 a controllable working time
• Single paste contained in a lightproof syringe.
• The free radical initiating system, consisting of a photosensitizer and an amine
initiator, is contained in this paste.
• As long as these two components are not exposed to light, they do not interact.

58. Exposure to light in the blue region (wavelength of about 468 nm)
excited state of the photosensitizer,
Which then interacts with the amine to form free radicals that initiate addition
polymerization.
• Camphoroquinone(CQ) - commonly used photosensitizer
absorbs blue light with wavelengths between 400 and 500 nm

59. • Avoid the porosity
• Allows operator to complete the insertion and contouring before curing.
• Once curing is initiated, an exposure time of 40 seconds or less is required to light-
cure a 2-mm-thick layer, as compared with several minutes for chemically-cured
materials.
• Not as sensitive to oxygen inhibition as are the chemically cured systems.

60. Dual-Cured Resins
• To overcome limits on curing depth of light curing - combine chemical curing and
visible-light curing components in the same resin.
• Consist of two light-curable pastes, one containing benzoyl peroxide and the other
containing an aromatic tertiary amine accelerator.
• They are formulated to set up very slowly when mixed via the self-cure mechanism.
• The cure is then accelerated on “command” via light-curing promoted by the
amine/CQ combination.

61. • The major advantage of this system is assurance of completion of cure
throughout, even if photocure is inadequate.
• The major disadvantage is porosity caused by the required mixing,but this has
been greatly alleviated by the use of mixing syringes.
• Less color stability than with the photocure resins
• Air inhibition and porosity are problems with dual cure resins.

62. INHIBITOR
• To minimize or prevent spontaneous or accidental polymerization of monomers.
• Strong reactivity potential with free radicals.
• This prevents chain propagation by terminating the reaction before the free radical
is able to initiate polymerization.
• A typical inhibitor is butylated hydroxytoluene (BHT), which is used in
concentrations on the order of 0.01% by weight.
• BHT and similar free radical scavengers are also used as food preservatives to
prevent oxidation and rancidity.

63. Thus, inhibitors have two functions:
 to extend the resin’s storage life and to
 ensure sufficient working time.

64. OPTICAL MODIFIERS
• Shading is achieved by adding various pigments, usually consisting of minute
amounts of metal oxide particles.
• Translucency and opacity are adjusted as necessary to simulate enamel and dentin.
• If an excessive amount of opacifier is added, too much light may be reflected and
the observer then perceives that the restoration is “too white,” or more correctly,
“too high in value”.
• To increase the opacity, the manufacturer adds titanium dioxide and aluminum
oxide to composites in minute amounts (0.001% to 0.007% by weight).

65. • It is important to realize that all optical modifiers affect light transmission through a
composite.
• Darker shades and greater opacities -decreased depth of light-curing ability and
require either an increased exposure time or a thinner layer when cured.
• For optimal polymerization, resins with darker shades and opacifiers should be placed
in thinner layers.

66. WEAR OF COMPOSITES
 Two principal mechanisms of composite wear have been proposed.
 The first mode is two-body wear, based on direct contact of the restoration with an
opposing cusp or with adjacent proximal surfaces to mimic the high stresses
developed in the small area of contact.
 This is related to the higher force levels exerted by the opposing cusp or forces
transferred to proximal surfaces.
 Wear resistance is less for composite compared to amalgam

67.  The second mode is three-body wear, which simulates loss of material in noncontacting
areas, most probably owing to contact with food as it is forced across the occlusal
surfaces.
 This type of wear is affected in a complex way by a number of composite properties such
as toughness, porosity, stability of the silane coupling agent, degree of monomer
conversion, filler loading, and the size and types of filler particles.

68. • Variations among patients—such as differences in chewing habits, force levels, and
variations in oral environments—also play a significant role in the wear process.

69. 1. Classification by Filler Particle Size
 Small (Fine) Particle Composites-
• Mean particle diameters between 0.1 and 10 µm (mini filler and midifiller).
• More polishable than traditional macrofilled composites (i.e., 10 to 100 µm)
• Filler loadings are as high as or higher (77% to 88%) - provides a high degree of hardness
• and strength but also brittleness.
• Excellent balance among polishability, appearance, and durability make this category
• suitable for general anterior use.

70.  Microfilled Composites.
• Agglomerates of 0.01- to 0.1-µm inorganic colloidal silica particles embedded in 5- to
50-µm resin filler particles.
• The problems of surface roughening and low translucency associated with
traditional and small-particle composites can be overcome through the use of colloidal
silica particles

71. • Inorganic filler component, with a mean particle diameter about one tenth of the
wavelength of visible light (i.e., about 40 nm).
• Pyrolytic precipitation process where a silicon compound such as SiCl4 is burned in an
oxygen/hydrogen atmosphere to form macromolecular chains of colloidal silica
resulting in amorphous silica (colloidal, noncrystalline SiO2), which produces highly
polishable esthetic composite restorations.

72. • Because of their small particle size, they have large surface area ranging from 50-400
metre square per gram.
• Due to agglomeration they also produce long molecular chain.
• So this results in increased monomer viscosity thereby making the clinical
manipulation difficult

73. CLASS OF FILLER PARTICLE SIZE
Macrofillers 10 to 100 microm
Small/fine fillers 0.1 to 10 microm
Midifillers 1 to 10 microm
Minifillers 0.1 to 1 microm
Microfillers 0.01 to 0.1 microm (agglomerated)
Nanofillers 0.005 to 0.1 microm
CLASSIFICATION OF REINFORCING FILLER PARTICLE BY SIZE RANGE

74. • Highly polishable
• Greater water sorption
• Higher coefficient of thermal expansion
• Decreased elastic modulus
• Decreased tensile strength
Microfilled composites are:

75.  Hybrid Composites
• Formulated with mixed filler systems containing both microfine (0.01 to 0.1
µm) and fine (0.1 to 10 µm) particle fillers in an effort to obtain even
for better surface smoothness than that provided by the small-particle
composites while still maintaining the desirable mechanical properties of the
latter.
• Suitable for restoring certain high-stress-sites where esthetic
considerations dominate—for example, incisal edges and small non-contact
occlusal cavities.
• Widely used for anterior restorations, including class IV sites

76.  Modern hybrid composite-
• Colloidal silica and ground particles of glasses containing heavy metals, constituting a
filler content of approximately 75% to 80% by weight.
• 75% of the ground particles are smaller than 1.0 µm and colloidal silica represents 10%
to 20% by weight of the total filler content.
• The smaller microfiller sizes increase the surface area, which generally increases the
viscosity and requires a decrease in overall filler loading as compared with small
particle composites.

77.  Nanofilled Composites/Nanocomposites/Nanohybrid Composites
• Recently, nanoparticles (1 to 100 nm) have been fabricated by a different method from
the pyrolytic precipitation process used for colloidal silica.
• Particles -surface-coated (with γ-methacryloxypropyltrimethoxysilane, for example)
prior to becoming incorporated into three-dimensional macromolecule chains.
• Thereby preventsor limits particle agglomeration into large networks and driving up
viscosity.

78. • These composites have optical properties and superior polishability like those of
microfilled composites.
• Surface treatment reduces the increase in viscosity when incorporated into the monomer,
which allows an increased filler loading of upwards of 60% by volume and 78%
• by weight.
• Nanocomposites meet the strict requirement of having essentially all filler less than 100
nm.

79. • Sometimes primary nanoparticles are reported to extend into the micron size range
(e.g., 60 nm to 1.4 µm).
• Above 100 nm, clusters, like any particles, begin to scatter visible light and thereby
reduce the translucency and the depth of cure of the composite.
• Nanocomposites with clusters have increased filler loading and hence better
mechanical properties than a true homogeneous nanocomposite, they are not as strong as
a hybrid composite or a microfilled composite.

80. • To combat this deficiency, larger particles of either finely ground glass or precured
nanoparticle-filled resin organic filler particles (essentially the same as those found in
the microfilled composites) are combined with the monomer dispersed nanoparticles.
• “hybrid” nanocomposites or nanohybrids consisting of a blend of two or
more size ranges of filler particles, one or more of which is in the nanoparticle range

81. 2.Classification of Composites by Manipulation Characteristics
 Flowable Composites.
• Modification of the small-particle composite and hybrid composite results in
the so-called flowable composites,
• Popular since 1995.

82. • Typically have a lower viscosity through a reduced filler loading, which enables the resin
to flow readily, spread uniformly, intimately adapt to a cavity form, and produce the
desired dental anatomy.
• This improves the clinician’s ability to form a well-adapted cavity base or liner, especially
in class II posterior preparations and other situations in which access
is difficult.

83. • Inferior in mechanical properties owing to the lower filler loading and higher susceptibility
to wear and other forms of attrition.
• Because they can flow into small crevice defects along restoration margins, some dentists
refer to flowable resins as “dental caulk.”

84.  Condensable (Packable) Composites.
• Also known as packable composites were developed by adjusting their filler distribution
to increase the strength and stiffness of the uncured material and provide a
consistency.
• Derived from the inclusion of elongated, fibrous filler particles of about 100 µm in
length and/or rough-textured surfaces or branched geometries that tend to interlock
and resist flow.

85. • Uncured resin tends to be stiff and resistant to slumping yet moldable under the
force of amalgam condeners.
• At present, these materials have not demonstrated any advantageous properties
or characteristics over the hybrid resins other than being somewhat similar to
amalgam in their placement technique.
• Have not yet proven to be an answer to the general need for highly wear-
resistant, easily placed posterior resins with low curing shrinkage and a depth of
cure greater than 2 mm.

86. Bulk fill composite
• 2 types are available :
a)Low -viscosity
b)high -viscosity
• Low viscosity composite are placed in 4mm increments.
• Used as dentin replacement layers / for small restorations.
• Low filler rates.
• High-viscosity composites are used to restore large preparations
• 4mm depth of cure

87. • Modern amalgams are produced from precapsulated alloy and
mercury. The components are separated in the capsule by a special
diaphragm that is broken when the capsule is ‘activated’ just before
mixing.
• Precapsulated (preproportioned) amalgam-convenience
and some degree of assurance that the materials will not
be contaminated before use or spilled before mixing.

88. Types of capsules.
A, Reusable capsules with pestle.
B, Preproportioned capsule with pestle.
C, Preproportioned capsule without pestle.
A programmable triturator.

89. Amalgamator
• During the early part of the twentieth century, alloy powder and mercury were
proportioned crudely and mixed manually.
• To proportion and mix amalgam more carefully, manufacturers later
recommended the use of amalgamators.

90. The typical amalgamator has been designed to grasp the ends of the capsule in a claw that
is oscillated in a figure-of-eight pattern.
• This design accelerates the mixture toward each end of the capsule during each throw and
impacts the mixture with the pestle.

91. COMPRESSIVE
STRENGTH
(MPa)
TENSILE
STRENGTH
(MPa)
MODULUS OF
ELASTICITY
COEFFICIENT OF
THERMAL
EXPANSION
WATER
SORPTION
Unfilled
acrylic
70 24 2.4 92.8 1.7
Traditional 250-300 50-65 8-15 25-35 0.5-0.7
Hybrid 350-400 75-90 15-20 19-26 0.5-0.6
Microfilled 250-350 30-50 3-6 50-60 1.4-1.7
Flowable - - 4-8 - -
Packable - - 3-13 - -
Low Copper 145 60
Admixed 137 48
Single
composition
262 64
Phillips’ Science of dental materials, 11/e Anusavice,
Sturdevant’s
Amalgam vs Composite- Properties

92. LONGEVITY and SURVIVAL RATE
• No failure- 3 years
• Less than 10% of restorations-10 years
• High copper amalgams have more
survival rates
• Average annual failure rate- 0.3%-6.9%
Survival rate- 3 years
Significant failure - 5 years
Light cured microfilled- successful between
6.5 to 8.5 years
Autopolymerizing macrofilled- upto 6.5
years successful
 Bhagyashree Patki. “Direct permanent restoratives - amalgam vs composite”. Journal of Evolution of Medical and Dental Sciences 2013; Vol. 2, Issue 46,
November 18; Page: 8912-8918.

93. • Evidence shows that composite resin restorations had almost double the risk of failure compared to
amalgam restorations (risk ratio (RR) 1.89, 95% confidence interval (CI) 1.52 to 2.35; P < 0.001), and
were at much higher risk of secondary caries (RR 2.14, 95% CI 1.67 to 2.74; P < 0.001).
• Low‐certainty evidence that composite resin restorations were not more likely to result in restoration
fracture (RR 0.87, 95% CI 0.46 to 1.64; P = 0.66).
Direct composite resin fillings versus amalgam fillings for permanent posterior teeth
Helen V WorthingtonSara KhanguraKelsey SealMonika Mierzwinski-UrbanAnalia Veitz-KeenanPhilipp SahrmannPatrick Roger SchmidlinDell
DavisZipporah Iheozor-EjioforMaría Graciela Rasines AlcarazAuthors' declarations of interest

94. SALIENT FEATURES OF AMALGAM AND
COMPOSITE
Amalgam
• Delayed expansion
• Creep and Flow
• Tarnish
• Corrosion
Composite
• Degree of conversion
• Martrix constraint
• Toughness
• Curing shrinkage and shrinkage stress

95. AMALGAM
STRENGTH
DIMENSIONAL
CHANGE
MODULUS OF
ELASTICITY
CREEP
CLINICAL
CONSIDERATION

96. • Amalgam can contract or expand
• Severe contraction can lead to microleakage, plaque accumulation and secondary
caries.
• Excessive expansion causes pulp and post operative sensitivity
• 15-20 micro m/cm measured at 37 degree Celsius between 5 min and 24h, after the
beginning of triturition

98. • EFFECT OF MOISTURE CONTAMINATION
• On contamination with moisture,large expansion can take place.
• (zinc-contaning, low copper or high-copper amalgam)
• Starts at 3-5 days upto months- >400 micrometre/cm (4%).
• Delayed expansion/secondary expansion
• Caused by hydrogen produced by electrolytic action of zinc and water.
• Main source of contamination-saliva

100. • The compressive strengths of high-copper amalgams are greater than the strengths of
low copper amalgams because of the presence of the copper phases.
• High-copper amalgams have compressive strengths that range from 380–550 MPa (55,000–
80,000 psi) and are similar to those of enamel and dentin.

101. • Important for fracture resistance.
Low-copper and high-copper amalgams have low tensile strengths, but high-copper
amalgam is lower overall.
• Intraoral loading conditions produce tensile stresses along the occlusal surface and at the
margins.
• Amalgams that are corroded or have inadequate bulk to distribute stresses may fracture.

102. • High-copper amalgams that are left in place may fail eventually because of bulk fracture. It
is hypothesized that such bulk fracture is the result of mechanical fatigue.
• Occlusal restorations are stressed an average of one million times per year.
 Typically, materials fail in the 10–100 million-cycle range during laboratory testing.

103. EFFECT OF TRITURITION
• Under triturition or over-triturition decreases
strength for both conventional and high-copper amalgam.
EFFECT OF MERCURY CONTENT
• Insufficient mercury between particles leads to dry, granular mix.
• Rough, pitted surface promoting corrosion.

104. • Increasing final mercury content increases volume fraction of matrix phases at the
expense of alloy particles
• High mercury contents results in formation of gamma-2 phase leading to high
incidence of fracture.

105. EFFECT OF CONDENSATION
• Higher condensation pressure are required to minimize porosity
and express mercury from lathe-cut amalgam.
• Spherical amalgams require lighter pressure for adequate strength.
EFFECT OF POROSITY
• Voids and porosity reduce compressive strength of amalgam.
• Delayed condensation and undertriturition causes lack of plasticity of amalgam mix
which leads to porosity.

106. EFFECT OF AMALGAM HARDENING RATE
• Amalgams do not gain strength rapidly
• Typical amalgam will have reached 70% of its strength approximately 8 hours after
placement.
• High copper amalgam are resistant to fracture due its high compressive strength.
• Strong enough for crown buildups.

107. • By ADA specification no.1, creep is limited to 3% in set
amalgam
• Occurs when a solid material slowly deforms plastically
under the influence of stresses.
• Determined by placing a cylinder of set amalgam under
36MPa compressive stresses.

108. • Correlates with marginal breakdown of low-copper amalgams.
• Gamma-1 phase deforms plastically.
• Low-copper amalgams and presence of gamma -2 phase increases creep rate.

109. COMPRESSIVE STRENGTH
(MPa)
COMPRESSIVE
STRENGTH (MPa)
1 Hour 7 Days Creep % Tensile Strength
at 24 hrs (MPa)
Low copper 145 343 2.0 60
Admix (high
copper)
137 431 0.4 48
Single
composition
(high copper)
262 510 0.13 64
COMPRESSIVE STRENGTH,TENSILE STRENGTH AND CREEP OF AMALGAM

110. • Tarnish- result of silver sulfide forming on the surface
• Does not affect/change mechanical properties of amalgam.
• Corrosion- corrosion products are oxides and chlorides of tin
• Found at tooth- amalgam interface and bulk of the restorations.
• Can be prevented by producing a smooth,homogenous surface on the restoration

111. TYPES OF CORROSION
Galvanic Corrosion Electrochemical
Corrosion
Crevice
Corrosion
Stress
corrosion

112. • Corrosion products from the tin in gamma 2 phase include tin oxychloride.
• Due to corrosion, mercury gets released.
• This mercury then reacts with unreacted gamma particles and produces
additional gamma 1 and 2 phases which results in some expansion called as
MERCUROSCOPIC EXPANSION.
• This results in porosity and reduction in strength.
• Corrosion on surface of amalgam restorations usually occurs to a depth of about
100 – 500 micrometers.

113. DEGREE OF CONVERSION (DC)
• Is a measure of the percentage of carbon-carbon double bonds that have been
converted to single bonds to form a polymeric resin
• The higher the DC, the better the strength, wear resistance, and many other properties
essential to resin performance.
• The total DC within resins does not differ between chemically activated and light-
activated composites containing the same monomer formulations as long as adequate
light curing is employed.

114. MATRIX CONSTRAINT
• Presence of filler particles bonded to the matrix via coupling agents reduces thermal
expansion and contraction of the composite.
• When thermal stresses arise, the interfacial bond and the presence of a filler with a
lower coefficient of thermal expansion (nearly zero in some cases), prevents or
reduces the contraction or expansion of the matrix
• Thus, during expansion, while the space occupied by the filler tries to increase, the
filler with lower coefficient of expansion does not—and since the filler is chemically
bonded to the matrix, it prevents the space from getting larger and hence prevents
or reduces the expansion.

115. • Conversely, during cooling, the matrix contracts and decreases the space occupied by the
filler, but since the filler occupies that space, contraction is prevented or reduced.
• Thus the filler particles not only lower thermal expansion and contraction by simply
occupying space that polymers, which are susceptible to thermal expansion, would
otherwise have occupied but also constrains the interfacial bond from
expanding thermally.

116. TOUGHNESS
• Strength of composites is highly dependent on the ability of the coupling agent to
transfer stresses from the weak matrix to the strong filler particles.
• Without the coupling agent, the filler particles cannot absorb stresses in the matrix
thereby weakening instead of strengthening the matrix.
• Thus a crack travelling through the matrix simply bypasses the particles.
• As the crack propagates to a bonded filler particle, the crack must pass around the
particle, since it is stronger than the matrix and the interfacial bond.

117. CURING SHRINKAGE AND SHRINKAGE STRESS
• It arises as the monomer is converted to polymer and the free space it occupies
reduces(approximately 20% less than that among unreacted monomers).
• In turn, this polymerization shrinkage produces unrelieved stresses in the resin after
it reaches the “gelation” point and begins to harden.
The polymerization shrinkage and resultant stress can be affected by the
(1) total volume of the composite material,
(2) type of composite,
(3) polymerization speed, and
(4) ratio of bonded/nonbonded surfaces or the configuration of the tooth preparation
(C-factor).

118. • These stresses tend to develop at the tissue/composite interface, weakening the
bond, and eventually producing a gap at the restoration margins.
• Higher the shrinkage greater the chances of bond disruption and this leads to
leakage around margins and secondary caries.
• Consequently the risk for marginal leakage and the ensuing problems of marginal
staining and secondary caries are exacerbated.
Unfilled
acrylic
resin
Traditio
nal
Hybrid Microfilled Flowable
hybrid
Packable
hybrid
Curing
shrinkage
(vol %)
8-10 - 2-3 2-3 3-5 2-3

119. This problem has been combated in two ways.
 Larger monomers used to “dilute” the number of double bonds that need to be
reacted.
 Addition of inorganic fillers that do not enter into the polymerization process,
although they do bond to the polymer

120. CURING LAMPS
• Handheld devices that contain the light source and are equipped with a relatively
short, rigid light guide made up of fused optical fibers.
• Most widely used light source is a quartz bulb with a tungsten filament in a halogen
environment

121. LED LAMPS
Quartz-
tungsten
halogen
lamps
Argon laser
lamps
Plasma arc
curing
lamps

122. INDICATIONS FOR AMALGAM:
 Can be used as a permanent restoration
material in Class I, Class II, Class V, Class VI
caries.
 Used in Pin retained restorations.
 Post-endodontic access filling and core.
 Cuspal restoration.
 Die preparation.
 Retrograde root canal filling material.
INDICATIONS FOR COMPOSITE:
 Cavity and crown restoration materials
 Adhesive bonding agents
 Pit and fissure sealants
 Endodontic sealants
 Bonding of ceramic veneers
 Cementation of crowns
 Bridges
INDICATIONS

123. CONTRAINDICATIONS OF AMALGAM
The contraindications for the clinical use
of dental amalgam can be listed as teeth
where:
 esthetics is a high priority for the
patient,
 extensive destruction has occurred, or
 very small cavities need to be
restored.
CONTRAINDICATIONS OF COMPOSITE
CONTRAINDICATIONS
The contraindications for the clinical use of
dental composite can be listed as teeth
where:
 patients with heavy occlusion
 bruxism
 large occlusal coverage

124. Advantages of amalgam
1. Ease of use
2. High compressive strength
3. Excellent wear resistance
4. Favorable long-term clinical research results
5. Lower cost than for composite restorations
Advantages of composite
1.Esthetics
2.Conserves tooth
3.Less complex
4.Used almost universally
5.Bonded to tooth structure
6.Repairable
7.No corrosion
8.Cheaper then porcelain
ADVANTAGES

125. Disadvantages of amalgam
1. Noninsulating
2. Non-esthetic
3. Less conservative (more removal of tooth
structure during tooth preparation)
4. More difficult tooth preparation
5. Initial marginal leakage
Disadvantages of composites
1.Polymerization shrinkage
2.Technique sensitive
3.Higher Coefficient Of thermal expansion
4.Difficult, time consuming
5.Increased occlusal wear
6.Low modulus of elasticity
7.Lack of anticariogenic property
8.Staining
9.Costly compared to amalgam
DISADVANTAGES

126. AMALGAM
 FLUORIDATED AMALGAM
 BONDED AMALGAM
 GLASS CERMET
 RESIN COATED AMALGAM
COMPOSITE
 MONOMER SYSTEM
 MOLECULAR SIZED REINFORCING FILLER PHASE
 GIOMER
 SMART COMPOSITES
 COMPOMERS
 FIBRE REINFORCED COMPOSITE
RECENT ADVANCES

127. ADVANCES-
AMALGAM
FLUORIDATED
AMALGAM
BONDED
AMALGAM
GLASS
CERMET
RESIN
COATED
AMALGAM

128. RESIN COATED AMALGAM
• To overcome the limitation of microleakage with amalgams, a coating of unfilled resin over the
restoration margins and the adjacent enamel, after etching the enamel, has been tried.
• Although the resin may eventually wear away, it delays microleakage until corrosion products begin
to fill the tooth restoration interface.
FLUORIDATED AMALGAM
• Fluoride, being cariostatic, has been included in amalgam to deal with the problem of recurrent
caries associated with amalgam restorations.
• The fluoride amalgam serves as a “slow release device”
• Example: Fluoralloy

129. BONDED AMALGAM
• Since amalgam does not bond to tooth structure, microleakage immediately after insertion is
inevitable. So, to overcome these disadvantages of amalgam, adhesive systems that reliably bond to
enamel and dentin have been introduced.
• 4META has been used to bond amalgam to cavity walls.
GLASS CERMET
• It is also called as cermet ionomer cements. McLen and Gasser in 1985 first developed this material.
Fusing the glass powder to silver particles through sintering that can be made to react with polyacid
to form the cement.
• The properties include strength which is both tensile and compressive strength is greater than
conventional glass ionomer cement. The abrasion resistance is greater than conventional GIC due to
silver particle incorporation.

130. INNOVATIONS IN DENTAL
COMPOSITES
MONOMER SYSTEM
MOLECULE SIZED
REINFORCING FILLER
PHASE
SMART
COMPOSITES
COMPOMERS
GIOMER
FIBRE REINFORCED
COMPOSITE

131. MONOMER SYSTEMS
Polycarbonate Dimethacrylate
• “Alert” is a polycarbonate dimethacrylate product (Pentron Clinical Technologies, Wallingford, CT) .
• The cured polymer is a polyester using carbonate (-O-CO-O-) links, instead of the urethane links (-NH-CO-O-)
found in UDMA, to connect the methacrylate ends to the central section of the monomer.
• Packable like amalgam, photocurable in bulk segments, and readily curable without generating high residual
shrinkage stress.
High-Molecular-Weight Urethane with a Rigid Central Section and Flexible End Groups
• Has a high molecular weight and a long rigid central section with flexible methacrylate end groups; these
provide rodlike shapes that facilitate self-assembly into compact molecular structures.
This, together with dilution of the number of polymerizable end groups due to the high molecular weight
reduces curing shrinkage, while the flexible end groups promote reactivity and
enhance monomer-polymer conversion.

132. Dimethacrylate with a Bulky, Space-Filling Central Group
• A bulky, space-filling dimethacrylate monomer .
• The bulky three-ring central group provides steric hindrance, which holds the monomers apart
and thus slows the rate of polymerization.
• This lengthens the time needed for the cross-linking reaction to reach the gel point and
provides time for adjacent polymer chain segments to slip among themselves, rearrange to
lower energy configurations, and relieve developing stresses before the gel point is reached,
resulting in one of the lower curing-stress resins currently reported among commercial
products.
High-Molecular-Weight Phase-Separating Dicarbamate with Hydrophobic Side Chains
• Product that also contains a bulky central group, somewhat analogous to TDC-urethane
dimethacrylate.
• The bulky centeris made up of a 6-carbon aliphatic ring with two long hydrocarbon side chains
derived from a linoleic acid dimer

133. • Reduced shrinkage;
• A further advantage is the hydrophobic nature of the center group which restricts water absorption and
solubility with the other dimethacrylates in the formulation.
• This leads to the formation of two separate phases during polymerization and produces a small
expansion which partially offsets the polymerization shrinkage.
“Silorane” Ring-Opening Tetrafunctional Epoxy Siloxane
• These tetra-functional “silorane” monomers use ring-opening polymerization. Silorane chemistry
• utilizes a combination of epoxy functionality (three-unit ring with two carbons and an oxygen) combined
with siloxane units (–O-Si-O–) that can be cured with low-shrinkage via a cationic cross-linking
mechanism by means of ring-opening polymerization.
• “LS” (low shrinkage) designation for the commercial product.
• Previously, epoxy systems were not used for dental applications because a nontoxic curing initiator with
hydrolytic stability could not be found.

134. MOLECULE-SIZED REINFORCING FILLER PHASES
Organically Modified Ceramic Oligomers
• Ormocer is an acronym for organically modified ceramics.
• They are considered to be molecule-sized hybrid structures consisting of inorganic-organic copolymers.
• Limited cure shrinkage, very high biocompatibility, good manipulation properties, and excellent esthetics.
Polyhedral Oligomeric Silsesquioxane (POSS)
• POSS molecules are 12-sided silicate cages produced from silane and functionalized to copolymerize with
other monomers.
• Highly polishable and having excellent polish retention, mechanical properties, and wear resistance.

135. GIOMER
• Developed by Shofu
• Giomer is a fluoride-releasing, resin-based dental adhesive material that comprises PRG fillers
• Giomer utilizes the hybridization of GIC and composite by using a unique technology called the pre-reacted glass
ionomer technology. • The fluoro aluminosilicate glass is reacted with polyalkenoic acid to yield a stable phase of GIC
this pre reacted glass is then mixed with the resin.
• The S-PRG technology not only provides the benefits of mechanical strength of a composite material but also
provides release of multiple ions i.e Sodium ions, Silicate ions, Aluminium ions, Fluoride ions .

136. • The advantages of compomer luting cement are listed below:
 Retentive
 High bond strength
 High compressive strength
 High flexural strength
 High fracture toughness
 Low solubility
 Sustained fluoride release with the potential to act as a fluoride reservoir
COMPOMERS
• Also known as polyacid-modified resin composite, are used in dentistry as a filling material.
They were introduced in the early 1990s as a hybrid of two other dental materials, dental
composites and glass ionomer cement, in an effort to combine their desirable properties.

137. SMART COMPOSITES
• It is a light-activated alkaline, nanofilled glass restorative material.
• It releases calcium, fluoride and hydroxyl ions when intraoral pH values drop below the critical pH
of 5.5, counteracting the demineralization process of the tooth surface and making conditions favorable
for remineralization.
• The material relies on mechanical retention, requiring no etching and bonding agent and can be
adequately cured in bulk thicknesses of upto 4mm.
SELF HEALING COMPOSITES
The first self-healing resin-based synthetic material has been developed by White et al.
The material was an epoxy system which contained resin filled microcapsule dicyclopentadiene,
a highly stable monomer with excellent shelf life, encapsulated in thin shell made of urea formaldehyde.
Jain P, Kaul R, Saha S, Sarkar S. Smart materials-making pediatric dentistry bio-smart. Int J Pedod Rehabil 2017;2:55-9

138. TOXICITY
AMALGAM
 Mercury Toxicity
 Allergy
 Lichenoid reaction
 Amalgam tattoo
COMPOSITE
 Estrogenicity (BPA)

139. Contact dermatitis, Type IV hypersensitivity reactions- less than 1%
Mercury allergy
Lichenoid reaction

141. BIOCOMPATIBILITY OF COMPOSITES
• Concerns about the biocompatibility of restorative materials usually relate to the
effects on the pulp from two aspects:
(1) the inherent chemical toxicity of the material and
(2) the marginal leakage of oral fluids.
• A chemical insult to the pulp- leach out to reach pulp
• Inadequately cured composite materials -serve as a reservoir of diffusible
components - long-term pulp inflammation (particular concern for light-activated
materials).

142. • Adequately polymerized composites are relatively biocompatible
• Exhibit minimal solubility, and unreacted species are leached in very small quantities.
• Polymerization shrinkage of the composite marginal leakage.
• The marginal leakage might allow bacterial ingrowth, and these
microorganisms may cause secondary caries or pulp reactions.

143. Estrogenicity
Bisphenol A Toxicity
• Bisphenol A (BPA), a precursor of bis-GMA, has been shown to be a xenoestrogen, a synthetic
compound that mimics the effects of estrogen by having an affinity for estrogen receptors.
• Cause reproductive anomalies, especially in the developmental stages of fetal life.
• Testicular cancer, decreased sperm count, and hypospadias (displacement of the urethral meatus)
• Exhibit antiandrogenic activities, which may prove to be detrimental in organ
development.
• Studies have shown that the estrogenicity of resin compounds is mainly associated with BPA and
• BPA dimethacrylate (BPA-DM), monomers found in the base paste of some dental sealants.

144. CONCLUSION
• Use of composite restoration is very common due to its excellent adhesive bonding
to the tooth structure,esthetics.
• The science and technology of composites have significantly improved compared
with their predecessors.

145. • Although composites have not evolved to the point of totally replacing
amalgam, they have become a viable substitute for amalgam in many clinical
situations. However, new expanding resins, nanofiller technology, and
improved bonding systems have the potential to reduce these problems.
• With increased patient demands for esthetics, the use of composite materials
for restorations will continue to grow; and so will the area of research to
combat the existing limitations of composites as a restorative material.

147. REFERENCES
 Phillips’ Science of dental materials, 11/e Anusavice.
 Marzouk Operative Dentistry, Modern Theory And Practice
 Sturdevant'S Art and Science of Operative Dentistry
 Recent Advances in Dental Composites: An Overview
Dara Lavanya1,*, Divya Buchi1, Satyanaryana Raju Mantena2, Madhu Varma K3,
D. Bheemalingeswara Rao2, Vinay Chandrappa4-International Journal of Dental Materials 2019; 1(2)
 Biocompatibility of dental amalgams
Y. Uçar, W. Brantley, in Biocompatibility of Dental Biomaterials, 2017
 Bhagyashree Patki. “Direct permanent restoratives - amalgam vs composite”. Journal of Evolution of Medical
and Dental Sciences 2013; Vol. 2, Issue 46, November 18; Page: 8912-8918.

148.  Opdam NJM, Bronkhorst EM, Roeters JM, et al: A retrospective clinical study on longevity of
posterior composite and amalgam restorations. Dent Mater 23(1):2–8, 2007.
 Brownawell AM, Berent S, Brent RL, et al: The potential adverse health effects of dental amalgam.
Toxicol Rev 24:1–10, 2005.
 Mjör IA: The safe and effective use of dental amalgam. Int Dent J37:147–151, 1987.
 Direct composite resin fillings versus amalgam fillings for permanent or adult posterior teeth
M Graciela Rasines Alcaraz 1, Analia Veitz-Keenan, Philipp Sahrmann, Patrick Roger Schmidlin, Dell
Davis, Zipporah Iheozor-Ejiofor

149.  Article
Evaluation of the Impact of Organic Fillers on Selected Properties of Organosilicon Polymer
Sara Sarraj * , Małgorzata Szymiczek , Tomasz Machoczek and Maciej Mrówka
 Longevity of dental amalgam in comparison to composite materials
Katja Antony,*,1 Dieter Genser,1 Cora Hiebinger,1 and Friederike Windisch1
 Direct composite resin fillings versus amalgam fillings for permanent posterior teeth
(Review) Worthington HV, Khangura S, Seal K, Mierzwinski-Urban M, Veitz-Keenan A,
Sahrmann P, Schmidlin PR, Davis D, Iheozor-Ejiofor Z, Rasines Alcaraz MG
 Jain P, Kaul R, Saha S, Sarkar S. Smart materials-making pediatric dentistry bio-smart. Int J
Pedod Rehabil 2017;2:55-9
 The influence of filler amount on selected properties of new experimental resin dental
composite Kinga Bociong, Agata Szczesio, Michal Krasowski and Jerzy Sokolowski
From the journal Open Chemistry
https://doi.org/10.1515/chem-2018-0090