Classification of filling materials
There are several classification of filling materials.
Depending to which group the tooth belongs, filling
materials are distinguished:
 For front group of teeth( filling materials should
correspond to high esthetic requirements);
 For molars and premolars (filling materials should
stand high occlusion press)
According to the material from what restorative materials
are produced, they are divided into:
 1. Metals : amalgam, alloys, pure metals (gold);
 2. Non metals: cements, plastic, composite materials.
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According to the purpose
Filling materials are divided for:
 Temporary fillings;
 Permanent fillings;
 Curative linings;
 Isolative linings;
 Sealing for the root canal.
Separate group of filling materials consist from adhesives,
sealants, varnishes. It’s not filling materials, but dentist can’t
work without them.
From the point of view of functionality and peculiarities of
their usage in the clinic, all filling materials are divided into 2
groups:
 1. Restorative (should provide complete restoration of the
shape of the tooth, and also renew the function of the tooth
for long time);
 2. Curative-prophylaxis (should have good curativeprophylaxis qualities).
Direct restoratives: clinical properties, handling and
placement
Several factors have to be taken into account when choosing the most
appropriate restorative method and material for a clinical situation. The
limiting factors include:
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■ Patient motivation and suitability.
■ The number of remaining teeth and their relative positions.
■ The condition of their supporting tissues.
■ The amount of remaining tooth structure.
■ The restorative materials available, and their longevity as restoratives.
■ The occlusion and opposing teeth and restorations.
■ Aesthetic and other wishes of the patient, including cost factors.
Available materials
The direct restoratives in current, general use are
amalgam, composite, glass - ionomer cements and
combinations of the last two groups
Dental amalgam
Dental amalgam is a mixture of mercury and an alloy
containing silver and tin with added copper and zinc. The alloy
and mercury are held together in a capsule, with the two
components separated by a plastic diaphragm. When the
diaphragm is broken and the capsule is placed in the mixing
machine (amalgamator), the two components are mixed
together (triturated) to form a silver-coloured paste. This
paste is then condensed into the cavity. This is a very
important stage: well-condensed amalgams are stronger than
poorly condensed ones, as more of the weaker, mercury-rich
γ2-phase is removed during carving. Amalgam is weak in thin
section so cavities have to be cut suitably deep (2 mm) and
because amalgam does not adhere to tooth tissue, the cavity
must be undercut.
Resin composites
 Resin composites used in dentistry have several
components:
 ■ Resin matrix: commonly a fluid monomer, BisGMA.
 ■ Filler particles of silica-based glass.
 ■ Silane: an agent that allows the resin and filler
particles to bond together.
 ■ Activator for the setting reaction: normally
camphorquinone.
 ■ Pigments.
Direct resin composites are the material of choice for
anterior restorations and they are increasing in use
and popularity for posterior restorations, mainly because
of their appearance. Composites
do not adhere directly to tooth
tissue and rely on the acid-etch
technique and the use of dental
adhesives for adhesion to
enamel and dentine.
Light curing
Light curing of resin composites is initiated by light in
the wavelength range 450–500 nm. This blue light
can damage the eyes so an orange filter should be
used when the light is in use. The tip of the light
source should be placed as close as possible to the
surface of the restoration and each increment of
composite should be cured for 40–60 seconds.
Under-cured composites will readily absorb stain and
will rapidly degenerate.
Polymerisation shrinkage of the resin during curing (in the
order of 2–3%) still occurs and may contribute to marginal
defects, cuspal distortion and crack formation in the enamel
or dentine, and may therefore contribute to postoperative
pain or sensitivity for the patient. There are, however, a
number of clinical techniques available to overcome these
problems and the longevity of restorations using the newer
resin composites is much improved over that of the original
materials.
Diagram showing incremental placement of
resin composite
Reducing the effect of polymerisation shrinkage may
be achieved by incremental packing of the
composite. Each increment should touch as few walls
of the cavity as possible . The stress induced by
polymerization shrinkage is highest in cavities with
more bonded than unbonded surfaces: the occlusal
cavity has the potential for the most stress.
Resin composites are not suitable in the
following clinical situations:
 ■ Deep subgingival preparations.
 ■ Lack of peripheral enamel.
 ■ Poor moisture control.
 ■ Load-bearing cusps.
Glass ionomers
 Glass ionomers contain poly(alkenoic) acid and fluoroaluminosilicate glass which set by an acid–base reaction to
give a cement.
 They adhere directly to tooth substance and to base metal
casting alloys.
 They release fluoride after placement, giving the materials
cariostatic properties, although this may only be short term.
 They also have a low tensile strength which makes them
brittle and unsuitable for use in load-bearing areas in
permanent teeth.
 They are used as lining and luting materials and to restore
abrasion and erosion lesions, cervical lesions and deciduous
(primary) teeth and as interim restorations.
 It must be appreciated, however, that they are less
translucent than resin composite restoratives and therefore
their appearance is less acceptable.
Resin-modified glass ionomers
 Resin-modified glass ionomers have a resin (monomer)
component as well as the poly(alkenoic) acid and fluoroaluminosilicate glass of conventional glass ionomers.
 They set by two mechanisms: acid–base reaction and curing
of the monomer (chemically, by light or both).
 They have improved appearance and physical properties
compared with conventional glass ionomers.
 They are used in similar situations to glass ionomers and
may also be used for small core build-ups.
Polyacid modified resin composites
 Polyacid modified resin composites are also known as
compomers.
 Their properties are more like those of composites than
glass ionomers.
 They have limited fluoride release but are stronger and have
a better appearance than glass ionomers.
 Their wear resistance is less than that of composite
restoratives.
 They do not adhere directly to tooth substance without the
use of a bonding system.
 They may be utillised to restore cervical and anterior
proximal cavities and for primary teeth.
Acid etching
 Acid etching with phosphoric acid creates pores
within the enamel into which resin flows to create
tags.
 This micromechanical retention is very reliable unless
there has been contamination of the etched surface
by saliva or blood.
 This technique is used to retain fissure sealants,
composite restorations, orthodontic brackets, resinretained bridges, veneers and other tooth-coloured
restorations.
 There is some merit in etching preparations prior to
placing a sealer, liner or base, as etching will
remove the smear layer which is contaminated with
bacteria. Removal of the smear layer in this way
affords gross debridement of the preparation and
will also improve the quality of the interface
between the sealer/liner and the dentine substrate.
Dental adhesives
 Bonding to dentine is more difficult than bonding
to enamel as, unlike enamel, dentine contains
water and has a greater proportion of organic
material.
 Bonding to dentine may be achieved reliably with
current systems which involve between one and
three steps and which either remove or modify the
smear layer (this is a layer of debris created by
cutting through dentine).
 The bond to dentine is a combination of chemical
and micromechanical bonding.
Current systems are
classified as follows:
 ■ Total etch (or etch and rinse):
 3 step – comprising etch, prime and bond.
 2 step – etch followed by a single application of primer
mixed with bond.
 ■ Self etch:
 2 step – etch and prime step, followed by bond.
 1 step – etch, prime and bond in a single application.
Linings for pulp protection
 To prevent noxious stimuli reaching the pulp it has been
custom and practice to apply protective materials to the
floor and/or the pulpo-axial wall of preparations.
 These materials were commonly placed
under amalgams and resin composites
to prevent thermal stimulation of the
pulp and acid contamination of
dentine.
Liners
 Preparation liners also seal freshly cut dentine but have
additional functions, such as adhesion to tooth
structure, fluoride release and/or antibacterial action.
 Preparation liners are applied in thin section (<0.5 mm)
and materials currently used include RMGICs, dentine
adhesive systems, flowable resin composites and hardsetting calcium hydroxide cements.
Temporary restorative materials and their
placement
Temporary restorations are placed for the
following reasons:
■ To improve patient comfort by:
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Preventing sensitivity.
Preventing food packing.
Restoring appearance.
Covering sharp margins of a cavity.
■ To provide a sedative effect on an infllamed pulp.
■ As an interim restoration before placing the final
restoration; perhaps to allow improvement in
gingival condition or to assess the patient’s response
to diet and oral health advice.
■ As a planned procedure prior to placing a
laboratory-made restoration.
■ To assess the prognosis of the tooth and/or pulp.
■ To prevent drifting, over-eruption, tilting or gingival
overgrowth.
■ For caries prevention: by using a fluoride leaching
material, such as glass ionomer.
■ How long the temporary restoration is to be in
place: this depends on the wear characteristics of the
material used.
■ The choice of eventual restoration: eugenol
plasticizes composite resin restoratives so there is a
risk that any eugenol remaining from the temporary
restoration could adversely affect a subsequent
composite resin restoration, although recent
research suggests this is not a problem.
Ideal temporary material
 The ideal temporary material should be easy and
quick to mix, place and shape. It should set quickly
and have appropriate strength and wear
characteristics.
 The material used should be non-toxic and be nonirritant to the pulp, preferably with a sedative
effect on the pulp.
 It should also have an acceptable colour, taste and
smell and be cheap and readily available.
 It is essential that it is easy to remove and is
compatible with other materials.
Choice of material
This depends on:
■ The size and shape of the cavity: a self-adhesive
material such as a glass ionomer may be required if
the cavity has no inherent retentive form.
■ The position in the mouth: tooth-coloured material
should be used for anterior teeth. Stronger materials
should be used for the occlusal surfaces of posterior
teeth.
Available materials
■ Zinc oxide eugenol based materials: these are quick
and easy to insert and remove, but are unaesthetic,
lack compressive strength and the taste is sometimes
considered unpleasant.
■ Polycarboxylates.
■ Glass ionomers.
■ Light-cured polymers.