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1. The notion of biomaterials. Their properties.

2. Electrical properties (galvanization).

3. Color selection. Dimensions of color.

4. Mechanical properties (strength, resilience, flexibility) of biomaterials biomaterials.

5. Characteristics of the compressive pressure. Impact strength.

6. Metals and metal alloys. Definition

7. Alloys for fixed dentures (noble, base). 8. Alloy casting, welding and bonding, alloy recycling. 9. Acrylic resins. Types. 10. The properties of heat activated acrylic resins (structure, porosity, volume change, thermal expansion, shrinkage during curing, thermal shrinkage, biological properties). 11. Indications for usage directions of acrylic plastic with thermal polymerization. Self polymerization acrylic resins. Release forms and their polymerization. 12. Ceramic masses. Definition. Chemical composition. 13. Stages of baking ceramic body on a metal structure. 14. Notion about new ceramic system: Hi-Ceram-Vita, Ceremony, In-Ceram-Vita, Dicor. 15. Notion about empress Technique. Mechanical copying methods. Computerized grinding methods (CAD-CAM). 16. Dental wax. Composition. Classification by the method of application. 17. Wax properties: melting range, flow, thermal expansion, mechanical properties, residual stresses, ductility. 18. Properties and advantages of dental investments and refractory materials. 19. The Definition of” Dental impression”. Characteristic. 20. Impression trays. Characteristic. Classification 21. Stages and technique of taking impressions. 22. The materials used for the manufacture of models. Properties. 23. Secondary properties for impression material (absence of toxic irritation, odor, taste, long storage and easy removal after curing imprint). 24. Technique of manufacturing metal models. Their use in practice. 25. Classification of filling materials. 26. Requirements for permanent filling materials. 27. Temporary filling materials. Requirements. 28. Temporary light-cured filling materials. Properties. 29. Characteristics of artificial dentin. Properties. Chemical composition. 30. Definition and classification of medical liners. The purpose of use of medical liners. 31. Water-based calcium hydroxide paste. Properties and indications for use. Calcium hydroxide cements based on resins. Properties and indications for use. 32. Zinc oxide paste. Properties and indications for use. Combined medical pastes. Properties and indications for use. 33. How to prepare medical liner. The mechanism of action of medical liner. 34. Notion and determination of the chemical composition of glass-ionomer cement. Types, curing glass-ionomer cement. 35. Properties of glass-ionomer cement. Indications for use directions and technology of mixing glass-ionomer cement. 36. Classification of glass-ionomer cement by Wilson and McLean (1988). Classification by G. J. Mount and W.R. Hume (1998). 37. Characteristics of glass-ionomer cement type I. Characteristics of glass-ionomer cement type II. Characteristics of glass-ionomer cement type III. 38. Definition of hybrid glass ionomer cements. Chemical composition. Types of polymerization. 39. Glass ionomer cement with addition of metal particles. Properties. Indications for use. 40. The difference between glass ionomer cement with addition of metal particles and metal ceramic particles (Cermet). 41. Definition of compomers. Indications for use of compomers. 42. Definition of ormocers. Properties. Indications for use. 43. Definition of amalgams. Classification of amalgam by the number of metals in it’s composition, by the content of copper in the silver alloy, silver lathe-cut. 44. Chemical composition of amalgam lathe-cut alloy. 45. Equipment and method for mixing of the amalgam. Capsules for mixing the amalgams. 46. Definition. General principles of adhesion. Physical adhesion mechanisms. Chemical adhesion mechanisms. 47. Features of adhesion to solid tissues of the tooth. Adhesion to enamel, morphofunctional features of enamel. Preparation of enamel for the adhesion. 48. Adhesion to dentin, morphofunctional features of dentin. Factors influencing the adhesion. 49. Classification of adhesive systems in association with (generations, type of polymerization, quantity of stages of imposing, pH, restoration material requiring adhesion). 50. IIIrd generation of adhesive systems (definition of primer and adhesive). IVth generation, characteristics, the procedure of etching, advantages and disadvantages. 51. Vth generation of adhesive systems characteristics, advantages and disadvantages. VIth generation of adhesive systems characteristics, advantages and disadvantages. 52. Definition of composite materials.Classification of composite materials by Lutz, Phillips and Willems. 53. Organic monomers of composite materials. (BIS-GMA, UDMA, DGMA, TGDMA). Inorganic fillers. Silans, polymerizations initiators, stabilizers, colorants and pigments. 54. Composite macro-filled sealing materials (classical and modern). Composite micro-filled sealing materials. Hybrid composite materials. Types of composite materials (powder liquid, liquid-paste, paste-paste, paste in the syringe). 55. Composite filling materials cured under UV radiation. Composite filling materials cured under the influence of light (halogen lamp). 56. Composite filling materials, cured under the influence of light (laser). Composite filling materials of dual curing. Biocompatibility (the reaction of pulp, microcracks, the irritation caused by the lamp curing, reaction of mucous of the gums). 57. Materials for filling the root canals. Classification. Temporary filling materials based on calcium hydroxide. Indications for use. Properties. Types. 58. Root canal materials for temporary filling based on iodoform. Indications for use. Types. The materials on the basis of paraformaldehyde. Indications for use. Their properties. Types. 59. Root canal materials for permanent filling. Characteristics. Materials for permanent filling based on glass-ionomer cement. Characteristics. Gutta-percha. Characteristics. 60. Root canal materials for permanent filling based on epoxy resins. Characteristics, properties. Primary solid materials for permanent filling of canals. 61. Irrigation and intra canal treatment (irrigation solution, solutions and gels for lubricant and chemical expansion of root canals).

Adhesive systems
Marcela Tighineanu,
Department of Stomatological Propaedeutics “Pavel Godoroja”
1
Bonding
• One of the initial problems when resin restoratives were
introduced was microleakage which resulted from the
shrinkage of the resin while curing.
• The problem was overcome to a great extent by the
introduction of the ‘acid etch technique’ by Buonocore in
1955.
Bonding may be achieved by one of two
mechanisms
1. Mechanical attachment;
2. Chemical adhesion.
Mechanical attachment
• In mechanical attachment, the adhesive simply engages in
undercuts in the adherend surface. When the surface
irregularities responsible for bonding have dimensions of
only a few micrometres, the process is known as
micromechanical attachment.
• This should be distinguished from macromechanical
attachment which forms the basis of retention for many
filling materials, using undercut cavities
Chemical adhesion
• In the case of chemical adhesion the adhesive has a chemical
affinity for the adherend surface.
• If the attraction is caused by Van der Waals forces or
hydrogen bonds, the resultant bond may be relatively weak.
• Whichever mechanism of bonding is used, the adhesive must
be capable of wetting the adhered surface.
• In the case of mechanical attachment, the adhesive must flow
across the surface and enter into all the surface undercuts in
order to form the bond.
• For chemical adhesion, the adhesive must wet the surface, in
order that intimate contact may result in the formation of
specific links which cause bonding.
Contact angle
For good wetting, a low contact angle, ideally approaching 0o, is required. High
contact angles indicate poor wetting and globule formation, and would
probably result in poor adhesion.
• Adhesive forces are maximized if the adhesive and surface are in intimate
contact over a large surface area. This requires that adhesives be applied in the
form of a low viscosity fluid or paste.
• If two solid surfaces are placed in contact, the rigid nature of the materials
dictates that unless the two surfaces are perfectly flat (very difficult to
achieve), the actual area of contact is only a fraction of the apparent area of
contact.
• Even if interactions between the two surfaces are favourable, the adhesive
strength is unlikely to be great enough to maintain the adhesive and adherend
in contact in the presence of even a small displacing force.
If the adhesive is fluid, but does not adequately wet the adherend surface the
situation may not be much better.
The ideal situation is of a fluid adhesive which fully wets the adherend
surface. The two interacting materials take full advantage of the adhesive
forces set up over the whole surface. In this case, the actual area of contact is
greater than the apparent area.
Acid etch technique
• The acid etch technique is one of the most effective ways of improving the bond and
marginal seal between resin and enamel.
• Mode of Action
• It creates microporosities by discrete etching of the enamel, by selective dissolution of
enamel rod centers, or peripheries, or both.
• Etching increases the surface area.
• Etched enamel has a high surface energy, allowing the resin to wet the tooth surface better
and penetrate into the microporosities.
Acid Used
• 37% phosphoric acid is used for etching.
• It is supplied in the form of a colored gel.
• Brushes are used to apply or the acid is supplied in a syringe from
which it can be dispensed onto the enamel.
Procedure
• The tooth is cleaned and polished with pumice before etching.
• The acid is then applied onto the enamel: 30 seconds enamel, 15
seconds dentine.
• The acid should be rinsed off for 15 seconds and the enamel dried
thoroughly.
• After drying, the enamel should have a white, frosted appearance.
• This surface must be kept clean and dry until the resin is placed.
Bond Strength
• Bond strengths to etched enamel range from 16 MPa (230
Psi) to 22 Mpa (3200 Psi).
• Drying the enamel with warm air or using an ethanol rinse
can increase the bond strength.
Bond agents
Enamel bond agents
• These were the earliest bond agents. The more viscous
composite did not bond well to the etched enamel. The
enamel bond agent helped improve the bond by flowing into
all the microporosities of the etched enamel.
• Composition
• They are unfilled resins similar to that of the resin matrix of
composite resin, diluted by other monomers to lower the
viscosity.
Dentin bond agents
• Acid etching of dentin is not done as it can injure the pulp. Thus, agents that could
bond to dentin were developed. Developing agents that will adhere to dentin was
more difficult because:
a) It is heterogenous.
b) The high water content interferes with bonding.
c) Presence of a smear layer on the cut dentin surface (The smear layer is the layer
of debris which adheres tightly to the dentin and fills the tubules after cavity
cutting).
• Ideally, the bond agent should be hydrophillic to displace the water and thereby
wet the surface.
• Restorative resins are hydrophobic, therefore agents should contain both
hydrophillic and hydrophobic parts.
– The hydrophillic part bonds with either calcium in the hydroxyapatite crystals or with collagen.
– The hydrophobic part bonds with the restorative resin.
Primers or Conditioners
• Dentin bond agents are supplied as a kit containing primers/
conditioners and the bonding liquid.
• Primers condition the dentin surface, and improve bonding.
They are acidic in nature. Examples of primers are : Ethylenediamine-tetracetic acid (EDTA), nitric acid, maleic acid, etc.
• They have the following functions:
• 1. Removes smear layer and provides subtle opening of dentinal
tubules.
• 2. Provides modest etching of the inter-tubular dentin.
Acid etch technique
• The acid etch technique was initially developed to improve
retention to enamel. Initial bond agents did not appear to bond to
the dentin.
• At the time it was widely believed that
– Dentin could not be etched as well as enamel
– Acid etching of dentin would cause injury to the pulp
• One reason for the low bond strength to dentin was because of
the hydrophobic nature of the early adhesive resins.
• The acid etch technique together with the application of current
bonding agents is one of the most effective ways of improving the
bond and marginal seal between resin and tooth structure.
Etchant/conditi
oner
The etchants are acidic in
nature. They may be
grouped as
1. Mineral (e.g. phosphoric,
nitric acid, etc
2. Organic (e.g. maleic, citric,
ethylenediamine-tetracetic
(EDTA), etc.)
3. Polymeric (e.g. polyacrylic
acid).
•
Etchant/conditioner
• The most frequently used etchant is 37% phosphoric acid.
• It may be supplied as clear or colored gel or liquid. Brushes are
used to apply or the acid is supplied in a syringe for direct
application on to the enamel.
• Another acid used is 10% maleic acid.
Mode of action on enamel
• 1. It creates microporosities by discrete etching of the
enamel, i.e., by selective dissolution of enamel rod centers, or
peripheries, or both.
• 2. Etching increases the surface area.
• 3. Etched enamel has a high surface energy, allowing the
resin to wet the tooth surface better and penetrate into the
microporosities. When polymerized, it forms resin ‘tags’
which forms a mechanical bond to the enamel.
Mode of action on dentin
• 1. Removes smear layer and partially opens the dentinal
tubules.
• 2. Provides modest etching of the intertubular dentin.
Procedure
• The tooth is cleaned and polished with pumice
before etching. The phosphoric acid is then
applied onto the enamel and then on to the dentin
(also known as total-etch technique).
• It has been shown that 15 seconds is enough. A
primary tooth requires longer etching time.
• The acid along with dissolved minerals should be
rinsed off with a stream of water for 15 seconds
and the enamel dried using compressed air.
• After drying the enamel should have a white,
frosted appearance.
• This surface must be kept clean and dry until the
resin is placed.
Enamel bond agents
• These were the earliest bond agents.
• The more viscous composite did not bond well to the etched
enamel.
• The enamel bond agent helped improve the bond by flowing
into all the microporosities of the etched enamel and
creating a mechanical retention.
Composition
• They are unfilled resins similar to that of the resin matrix of
composite resin, diluted by other monomers to lower the
viscosity. These materials have been replaced by agents that
bond to both enamel and dentin.
• Bond strengths to etched enamel range from 16 MPa (230
Psi) to 22 MPa (3200 Psi). Drying the enamel with warm air
or using an ethanol rinse can increase the bond strength.
Enamel/dentin bond systems
• The term dentin bond agent is no longer relevant.
• The problem lies at the resin-dentin/cementum interface.
Thus agents that could bond to dentin were needed.
Developing agents that will adhere to dentin was more
difficult because:
– It is heterogenous.
– The high water content interferes with bonding.
– Presence of a smear layer on the cut dentin surface.
• Ideally, the bond agent should be hydrophilic to displace the
water and thereby wet the surface, permitting it to penetrate
the porosities in dentin as well as react with the organic/
inorganic components.
• Restorative resins are hydrophobic, therefore, bonding
agents should contain both hydrophilic and hydrophobic
parts.
– The hydrophilic part bonds with either calcium in the
hydroxyapatite crystals or with collagen.
– The hydrophobic part bonds with the restorative resin.
Supplied as
• Dentin bond systems are supplied in one or more bottles
containing conditioners (etchant)/primers/ and adhesive
depending on the generation.
Generations
First generation (1950 to 1970)
• Mineral acids were used to etch enamel.
• Dentin etching was not recommended as it was believed it
would harm the pulp. They were generally self cured.
• The main disadvantage was their low bond strength (2 to 6
MPa) because of their high polymerization shrinkage.
• Leakage was a concern at the dentin-resin interphase.
Second generation (1970s)
• Developed as adhesive agents for composite resins which
had by then replaced acrylic restorations.
• Bond strengths achieved were three times more than the
earlier generations.
• Disadvantage Bond strengths were still low. The adhesion
was short term and the bond eventually hydrolysed.
• Prisma, Universal Bond, Clearfil, Scotch Bond.
Third generation (1980s)
• The third generation bond agents had bond strengths comparable to
that of resin to etched enamel. Thus bond strengths improved to 12 to
15 Mpa.
• Their use is more complex and requires two to three application steps.
• Etching of enamel using 37% phosphoric acid
• Conditioning of dentin using mild acids
• Application of separate primer
• Application of polymerizable monomer
• Placement of the resin.
• Examples are Tenure, Scotch bond 2, Prisma, Universal bond, Mirage
bond, etc.
Fourth generation (early 1990s)
• The fourth generation systems were
possible because of some important
ideological breakthroughs – like the
total etch technique and the
development of the hybrid zone.
The hybrid layer
• The hybrid layer is defined as “the structure formed in dental
hard tissues (enamel, dentin, cementum) by demineralization of
the surface and subsurface, followed by infiltration of monomers
into the collagen mesh and subsequent polymerization.
• Examples are All Bond 2, Scotch bond multipurpose, Optibond,
etc.
• The All Bond consists of 2 primers and an unfilled resin adhesive.
This system bonds composite not only to dentin but to most
dental related surfaces like enamel, casting alloys, amalgam,
porcelain and composite. Bond strengths were high but as with
the earlier system, multiple application steps were required.
Fifth generation (mid 1990s)
• The fifth generation combined the primer and
adhesive in to one bottle (self priming
adhesive). Examples of the fifth generation
self-priming adhesives are Single Bond (3M)
(Fig. 11.23), One Step (BISCO), Prime and Bond
(Dentsply).
• The advantages are:
• 1. Reduced application steps.
• 2. Less technique sensitive as it can bond to
moist dentin.
• 3. Less volatile liquid.
• 4. Pleasant odor.
• 5. Higher bond strength.
Sixth generation (mid to late 1990s)
• A separate etchant is not required. These
are 2 bottle systems. Two varieties are
seen—Type I and Type 2.
• Type I 2 bottle 2 step system. Etchant and
primer are combined in one bottle (called
self etching primer). Other bottle contains
adhesive. Examples are Clearfil SE bond
(Curare), Adhese (Ivoclar), Optibond solo
plus (Kerr), Nano bond (Pentron) etc.
• Type II 2 bottle 1 step
system. Liquid A contains the
primer. Liquid B contains a
phosphoric acid modified
resin (self etching adhesive).
Both liquids are mixed just
before application. For
example, Xeno III (Dentsply Fig. 11.25 ), Adper prompt Lpop (3 M), Tenure unibond
(Dent Mat) etc.
Seventh generation (early 2000)
• Attempts to combine all three (etchant,
primer and adhesive) into a single
product. Thus, seventh generation
adhesives may be characterized as – ‘no
mix self etching adhesives ’.
• Examples include iBond (Heraeus
Kulzer), G bond (GC), Xeno IV
(Dentsply) (glass ionomer based),
Clearfil S3 (Curare). Unfortunately,
insufficient research exists of the
efficacy of the newer systems.
• Indications for use of bond agents
• 1. For bonding composite to tooth
structure.
• 2. Bonding composite to porcelain
and various metals like amalgam,
base metal and noble metal alloys.
• 3. Desensitization of exposed
dentin or root surfaces.
• 4. Bonding of porcelain veneers.
• Contraindication
• Bonding should not be done
immediately after bleaching a
tooth. It is advisable to wait at least
a week following the procedure.
Procedure for iBond
• 1. Isolate the tooth from saliva contamination during the adhesive
procedure.
• 2. Clean the preparation, removing all debris with water. Remove excess
water.
• 3. Saturate the microbrush with iBondTM liquid from either the bottle
or single dose vial.
• 4. Apply 3 consecutive coats of iBondTM to both the enamel and dentin
followed by gentle rubbing for 30 seconds.
• 5. Use gentle air pressure or vacuum to remove the acetone and water
solvent.
• 6. Cure for 20 seconds with a dental curing light of at least 500 mW/C2.
• 7. Place composite.
Thank you for your attention!
Marcela Tighineanu,
Department of Stomatological Propaedeutics “Pavel Godoroja”
44
Biomaterials
• The science of biomaterials represents a branch or
a compartment of dentistry that deals with the
study of the origin, composition, properties and
changes of biomaterials during their processing.
• This department also deals with the development
of new materials.
• Depending on the purpose for which they are used, the
biomaterials can be divided into 2 main groups:
1. Basic materials – materials from which dentures are made
(metal alloys, metals, acrylate, ceramics).
2. Auxiliary materials – materials used at various stages of
making dentures (impression materials, materials for
making casts, wax, polish materials, acids, pastes)
Medico – biological requirements
No toxic and chemical action on the tissues of the oral
cavity
Neutral to the action of saliva and food components
Biologically tolerated by the tissues of the oral cavity
No unpleasant taste sensations and odors
No allergic agents
The basic materials must be easy to undergo the act of selfcleaning and hygienic cleaning in the conditions of the oral
environment
Classification of materials by McCabe, Walls, 2008
Inorganic salts
• Dental cements
• Gypsum products
Ceramics
• Porcelain crowns
Metals and alloys
Polymers
• Components of dentures
• Wires
• Cast restorations
• Denture bases
• Direct filling materials
No
Image
Polymer composites • Direct filiing materials
Elastomers
• Impression materials
Properties of dental materials
1. Physical properties
2. Chemical properties
3. Biological properties
Important properties of biomaterials
High mechanical qualities
-Durability
-Plasticity
-Elasticity
-Viscosity
-Fragility
Corresponding physical
qualities
Resistant to corrosion even under
extreme conditions (oral cavity)
High technological qualities
– Easy to comply to bonding,
casting, welding, stamping
polishing
Color, relatively low melting
point, small thermal
contraction, thermal and
electrical conductibility,
density, fluidity, weld ability
(weld of two alloys together),
malleability (ability to be
Physical properties
Mechanical properties
Express the ability of the material to withstand maximum resistance to the action of
various forces exerted on it to deform or crumble
1. Resistance – the property of the material to resist the action of
external forces, which does not easily change its properties under
the action of a physico-chemical agent.
2. Hardness – the property of the material to oppose the tendency of
another material to penetrate it. Durability – the quality of a
material to retain its physico-chemical and mechanical properties
for a long time.
3. Elasticity – the property of some bodies (solids, liquids, gases) to
deform, changing their volume or shape under the action of
external stresses and to return to their original state after the
cessation of external forces.
Mechanical properties
Express the ability of the material to withstand maximum resistance to the action of
various forces exerted on it to deform or crumble
4. Viscosity – the property of the material – of a fluid – to be
viscous, to resist flow.
5. Plasticity – the property of a consistent material to acquire
new shapes under the action of various forces, to be easily
shaped by pressing, to be easily shaped, cold or hot. The
property of a material to deform and to remain deformed
after the cessation of the action of the load.
6. Fragility – the property of the material to crumble to the
action of the forces executed on it. Lack of resistance of
materials to external stresses, to internal stresses.
Important properties of biomaterials
• Absorption – a process in which liquid or solid body incorporates
another substances through diffusion.
• Solubility – the ability of a substance to be dissolved in a solvent.
• Coefficient of thermal expansion and contraction – the ability
of a material to change its size when it is heated or cooled.
Important properties of biomaterials
• Thermal conductivity – the ease of which the heat can pass
through the material.
• Electrical conductivity- the ease of which electricity can
pass through the material, color.
• Stress – The internal resistance of the body to the external
force.
Desirable properties of dental materials
• Biocompatibility;
• Absence of toxicity;
• Aesthetic appearance;
• Strength and durability;
• Low solubility;
• Ease of manipulation;
• Long shelf life;
• Simple laboratory processing;
• Long working time;
• Rapid/snap set.
Metals and alloys
• Metals have been used in dentistry for
thousands of years as a replacement material
for missing tooth structure.
• Gold in a foil form was probably first used as a
dental restorative material. However, pure
metals, including gold, generally lacks enough
strength to be used for many dental
restorations such as crowns and bridges.
• For this reason, several metals are mixed
together to provide better physical properties.
• When 2 or more metals are mixed together,
the resulting mixture is called an alloy.
Metals and alloys. Classification
• Metals
Metals and alloys. Classification
• Alloys
Noble alloys
(have noble metals as the
majority of their
components)
The nobility of an alloy is
usually expressed as a
sum of the % of the
noble metals in the alloy
Non noble alloys
(have a greater percentage
of base metals)
For example, if an alloy
contains:
-60% gold
-10% Palladium
-5% Platinum
-25% Copper, the nobility
would be 75% (the sum
of Gold, Palladium and
Platinum)
Metals and alloys. Classification by Siebert
American Dental Association currently recognizes 3 major
categories of alloys:
Metals and alloys. Classification by Siebert
American Dental Association currently recognizes 3 major
categories of alloys:
Metals and alloys. Classification.
I.
Noble alloys
II. Half noble alloys
III. Non noble alloys
Metals and alloys. Classification.
Noble alloys
1. Gold alloys
– 916 fineness (91,6% Au; 4,7%Ag; 4,7% Cu)
– 900 fineness (90% Au; 4% Ag; 6% Cu)
-750 fineness (75% Au; 3% Ag; 9,7% Cu; 12% Cadmium)
2. Platinum
Metals and alloys. Classification.
Half noble alloys
Silver – Palladium alloys
1.PD– 250(72,1%Ag; 24,5%Pd) for stamp
crowns
2.PD-190(78,0%Ag; 18,5%Pd) for casting
3.PD-150(84,1%Ag; 13,5%Pd) for inlays
4.PD-140(53,9%Ag; 13,5%Pd) for
soldering
Metals and alloys. Classification.
Non noble alloys
1.Cr – Ni alloys
2.Cr – Co alloys
Cr-Ni alloys consist of:
•Cr – 12%
•Ni – 69-81%
Cr-Co alloys consist of:
– Co – 60%
– Cr – 30%
Metals and alloys
• Important properties of alloys:
 Melting range
 Density
 Strength
 Hardness
Physical and Mechanical Properties of Dental Casting Alloys
1. HIGH-NOBLE ALLOY
Alloy
Type
Melting
Range (ͦC)
Density
(g/cm³)
0,2%
Yield Hardness*
Strenght* (MPa) (Kg/mm²)
Uses
Goldplatinum
1045-1140
18,4
420/470
175/195
Full cast, porcelan bonding
applications
Gold- copper- 910-1065
silver
15,6
270/400
135/195
Full cast applications
*Some alloys can exist in a soft or a hard condition. When two numbers are
shown, the soft condition is shown to the left and the hard condition to the right
of the slash.
Physical and Mechanical Properties of Dental Casting Alloys
2. NOBLE ALLOY
Alloy Type
Melting
Range ( ͦC)
Density
(g/cm³)
Hardness*
(Kg/mm²
Uses
12,4
0,2%
Yield
Strenght*
(MPa)
325/520
Silver- goldcopper
865-925
125/215
Full cast applications
Palladiumcopper
1100-1190
10,6
1145
425
Full cast, porcelain bonding
applications
Silverpalladium
1020-1100
10,6
260/320
140/155
Full cast, porcelain
bonding applications
Physical and Mechanical Properties of Dental Casting Alloys
3. BASE METAL
Alloy Type
Melting Range
( ͦC)
Density
(g/cm³)
Ni-based
1275
7,5
0,2%
Yield Hardness*
(Kg/mm²
Strenght*
(MPa)
710
340
Co-based
1400-1500
7,5
870
380
Ti-based
1700
4
300
NA*
*NA, not applicable
Uses
Full cast, porcelain bonding,
partial denture, wrought
applications
Full cast, porcelain bonding,
partial denture, wrought
applications
Full cast, porcelain bonding,
partial denture, dental implant
applications
Measure unit of noble alloys
 The amount of gold in an alloy can be described in several ways besides
percentage.
 The term “Karat” is used to describe the gold content of jewelry.
Pure gold is defined as 24 karat. An alloy with 50% gold is 12k, with 75% 18k. The formula for determining the karat of an alloy is:
 Karat = 24 x %Gold/100.
 Gold content may also be expressed in terms of fineness.
Thus pure gold(100%) will have a fineness of 1000. An alloy with 50% gold
, would have a fineness of 500, and an alloy with 75% gold, would have a
fineness of 750. The symbol of fineness is “f” and this system is often use
to describe gold-based dental solders.
Non-metallic materials
The non-metallic materials can be divided basically in 3:
1)Polymeric materials (plastics)
2)Ceramics
3)Composites.
These materials have a wide range of applications in dentistry
and can be used as dental liners or filling materials, passing
through dental porcelain or fixation cements, the same way as
many other applications.
Polymeric materials (plastics)
The most used polymers are the acrylic polymers and they represent
the 95% of the polymers used to fabricate dentures.
The acrylic polymers can be soft and flexible or fragile and rigid and
consequently, they can be used in many applications.
Its main application is the fabrication of bases to support the artificial
teeth on complete or partial dentures. The acrylic polymers have been used
profusely for the fabrication of false teeth for dentures and in the majority
of the cases the behaviour of such teeth has competed correctly with the
porcelain teeth.
Classification Of Polymers
• Since Polymers are numerous in number with
different behaviours and can be naturally
found or synthetically created, they can be
classified in various ways.
1] Classification Based on Source
The easiest way to classify polymers is their source of origin.
(i) Natural polymers
Natural polymers are polymers which occur in nature and are
existing in natural sources like plants and animals. Some
common examples are Proteins (which are found in humans and
animals alike), Cellulose and Starch (which are found in plants)
or Rubber (which we harvest from the latex of a tropical plant).
1] Classification Based on Source
(ii) Synthetic polymers
Synthetic polymers are polymers which humans can artificially
create/synthesize in a lab. These are commercially produced by
industries for human necessities. Some commonly produced
polymers which we use day to day are Polyethylene (a massproduced plastic which we use in packaging) or Nylon Fibers
(commonly used in our clothes, fishing nets etc.)
1] Classification Based on Source
(iii) Semi-Synthetic polymers
Semi-Synthetic polymers are polymers obtained by making
modification in natural polymers artificially in a lab. These polymers
formed by chemical reaction (in a controlled environment) and are of
commercial importance. Example: Vulcanized Rubber ( Sulphur is
used in cross bonding the polymer chains found in natural rubber)
Cellulose acetate (rayon) etc
2] Classification Based on Structure of
Polymers
(i) Linear polymers:
These polymers are similar in structure to a long straight chain
with identical links connected to each other. The monomers in
these are linked together to form a long chain. These polymers
have high melting points and are of higher density. A common
example of this is PVC (Poly-vinyl chloride). This polymer is
largely used for making electric cables and pipes.
2] Classification Based on Structure of Polymers
(ii) Branch chain polymers:
The structure of these polymers is like branches originating at random
points from a single linear chain. Monomers join together to form a
long straight chain with some branched chains of different lengths. As
a result of these branches, the polymers are not closely packed
together. They are of low density having low melting points. Lowdensity polyethene (LDPE) used in plastic bags and general purpose
containers is a common example
2] Classification Based on Structure of Polymers
(iii) Cross-linked or Network polymers:
In this type of polymers, monomers are linked together to form a
three-dimensional network. The monomers contain strong covalent
bonds as they are composed of bi-functional and tri-functional in
nature. These polymers are brittle and hard. Ex:- Bakelite (used in
electrical insulators), Melamine etc
3] Based on type of Polymerisation
Polymerization is the process by which monomer molecules are
reacted together in a chemical reaction to form a polymer chain
(or three-dimensional networks).
3] Based on type of Polymerisation
i) Addition polymers:
This type of polymers are formed by the repeated addition of
monomer molecules. The polymer is formed by polymerization of
monomers with double or triple bonds (unsaturated compounds).
Note, in this process, there is no elimination of small molecules like
water or alcohol etc (no by-product of the process). Addition polymers
always have their empirical formulas same as their monomers.
Example: ethene n(CH2=CH2) to polyethene -(CH2-CH2)n-
3] Based on type of Polymerisation
ii) Condensation polymers:
These polymers are formed by the combination of monomers, with the
elimination of small molecules like water, alcohol etc. The monomers
in these types of condensation reactions are bi-functional or trifunctional in nature. A common example is the polymerization of
Hexamethylenediamine and adipic acid. to give Nylon – 66, where
molecules of water are eliminated in the process.
4] Classification Based on Molecular
Forces
i) Elastomers:
Elastomers are rubber-like solid polymers, that are elastic in nature.
When we say elastic, we basically mean that the polymer can be easily
stretched by applying a little force.
The most common example of this can be seen in rubber bands(or
hair bands). Applying a little stress elongates the band. The polymer
chains are held by the weakest intermolecular forces, hence allowing
the polymer to be stretched. But as you notice removing that stress
also results in the rubber band taking up its original form. This
happens as we introduce crosslinks between the polymer chains
which help it in retracting to its original position, and taking its
original form. Our car tyres are made of Vulcanized rubber.
4] Classification Based on Molecular
Forces
ii) Thermoplastics:
Thermoplastic polymers are long-chain polymers in which intermolecules forces (Van der Waal’s forces) hold the polymer chains
together. These polymers when heated are softened (thick fluid like)
and hardened when they are allowed to cool down, forming a hard
mass. They do not contain any cross bond and can easily be shaped by
heating and using moulds. A common example is Polystyrene or PVC
(which is used in making pipes).
4] Classification Based on Molecular
Forces
iv) Fibres:
In the classification of polymers, these are a class of polymers which
are a thread like in nature, and can easily be woven. They have strong
inter-molecules forces between the chains giving them less elasticity
and high tensile strength. The intermolecular forces may be hydrogen
bonds or dipole-dipole interaction. Fibres have sharp and high melting
points. A common example is that of Nylon-66, which is used in
carpets and apparels.
5] Classification by application
 Cements: polyacrylic acid is a constituent of zinc polycarboxylate
cements and glass-ionomer cements;
 Restorative materials: composite materials;
 Polymers used in the so-called adhesive techniques;
 Varnishes contain natural resins such as copal or resin;
 Impression materials: agar and alginates and polysulphide,
silicone and polyether elastomers;
 Polymeric crown and bridge materials;
5] Classification by application
 Denture base materials;
 Soft linings: plasticised polymers, higher methacrylates and
silicone rubbers;
 Acrylic tooth materials;
 Orthodontic base polymers;
 Die materials: filled polymers;
 Some pattern materials for partial denture construction can
be made of polymers such as polyethylene;
 Mouth protectors are made of polymeric materials.
Polymerisation process
To be able to comprehend the use and application of the polymers, it is
necessary to understand the polymerisation process.
In laboratory, the material should be mixed like a mass, moulded to obtain
the desired shape. It is left to set and solidify in the desired shape. This objective
is due to the polymerisation.
The activator of the reaction is an organic peroxide which decomposes in
active free radicals by heating or by the addition of an organic accelerator. In the
first case, it is necessary to get the temperature of 74 ºC to obtain good
decomposition rates. In the second case, the accelerator decomposes the
peroxide at room temperature. The products that need heat to decompose the
activator are called termopolymerisable plastics, and the products that need
an accelerator are called chemical polymerisation plastics or self plastics.
Methods of fabricating polymers
Condensation polymers
When the polymers were used, they were supplied in an intermediate stage of condensation, and moulded
by the application of heat and pressure to the required shape; during this process the condensation
process continued.
Compression moulding
The products of addition polymerisation are usually thermoplastic; that is, they soften on heating and
harden on cooling, without chemical change, (contrast to thermosetting polymers, which do not soften, but
burn or decompose on heating). Thermoplastic polymers can be moulded by the application of heat and
pressure.
Injection moulding
Industrially, thermoplastic materials are often moulded by heating the polymer until it is soft enough to be
injected into a mould of the required shape. This method is used in dentistry, though not frequently.
Dough technique
This method is widely used in dentistry in the moulding of polymethyl methacrylate for dentures. A dough
is formed from a mixture of the monomer (liquid) and polymer (powder); this is packed into a mould and
the monomer is polymerised under the appropriate conditions of activation and initiation to give a solid
material.
Composition of the acrylic polymers
Powder
Liquid
Poly (methylmethacrylate)
Methylmethacrylate (monomer)
Organic peroxid (initiator)
Hydroquinone (inhibitor
Titanium oxide (opacity)
Dimetacrylate (link agent)
Inorganic pigments
Organic amine (accelerator)
Properties of the acrylic materials
 The acrylic denture bases have a low thermic conductivity and patients feel a low
thermic stimulation of the oral tissue under the acrylic denture.
 The volumetric contraction of polymerisation in a mixture monomer-polymer of 3:1
is elevated (6%), and it can produce deformation of the acrylic denture during the
polymerisation process.
 The acrylic polymers absorb 0,6 mg/cm2 of water. This absorption reaches the
equilibrium at 2% of water. It can lightly modify the shape and the dimensions of the
acrylic denture base.
 The acrylic polymers don’t stick much to metal or porcelain, and mechanical fixing
methods are required to fix the acrylic polymer to these materials.
The properties of heat-activated resins
The properties of heat-activated resins
Thank you for your attention!
Marcela Tighineanu,
Department of Stomatological Propaedeutics “Pavel Godoroja”
96
Dental amalgam
• An amalgam is defined as a special type of alloy in which
mercury is one of the components.
• Mercury is able to react with certain alloys to form a plastic
mass, which is conveniently packed into a prepared cavity in
a tooth.
• This plastic mass hardens and is stronger than any dental
cement or anterior filling material.
• Dental amalgam was the most widely used filling material
for posterior teeth.
Indications
1. As a permanent filling material for
– Class I and class II cavities.
– Class V cavities where esthetics is not required.
2. In combination with retentive pins to restore a crown.
3. For making dies.
4. In retrograde root canal fillings.
5. As a core material in abutment teeth.
Contraindications
1. Amalgam should not be placed in patients with impaired
kidney function.
2. Individuals with allergic hypersensitivity to mercury or
components of the alloy
3. New amalgam fillings should not be placed in contact with
nonamalgam restoration like gold and metal devices, such as
orthodontic braces.
Classification of amalgam alloys
Release form
• •
Alloy and mercury in disposable capsules
• •
Preweighed alloy as tablet form in tubes and mercury in sachets
• •
Bulk powder and mercury in separate containers.
Composition of powder added to
mercury:
• Silver increases expansion, strength and reduces creep.
• Tin decreases expansion, strength, hardness and increases setting
time. It has more affinity for mercury than silver.
• Copper increases expansion, strength and hardness, reduces creep
• Zinc facilitates condensation and avoids the formation of oxides
during manufacturing processes. (Moisture contamination of zinccontaining amalgams causes delayed expansion of the material)
• Mercury (Hg) can enter the composition in a proportion of 2-3%
• Indium, introduced into the composition (in a proportion of 1015%), decreases the amount of excess mercury, increases the
wettability of the amalgam and decreases the amount of mercury
evaporated both during and after setting.
Composition
The powder contains:
•
•
•
•
Silver 40-70% which increases the strength of the amalgam and
reduces its flow. Together with mercury, it forms metal
compounds that are responsible for the expansion of the
•
amalgam during its formation.
A higher silver content gives the amalgam a higher hardness, but
it becomes more brittle, more difficult to handle, sets quickly
and tends to expand.
A lower content determines a prolonged working time, but
•
results in an amalgam with a lower hardness and tendency to
shrink.
•
Silver, as the main constituent of the alloy, influences the of the
amalgam. Silver ions have bactericidal action.
– Major element in the reaction.
– Whitens the alloy.
– Decreases the creep.
– Increases the strength.
– Increases the expansion on setting.
– Increases tarnish resistance in the resulting amalgam.
Tin 22-30% has an opposite effect to silver. It reduces the
expansion during amalgam setting and allows better
amalgamation due to its affinity for mercury and a more
plastic end product but an excessive amount makes the
amalgam crumbly.
The Tin-Mercury compounds reduce strength and increase
amalgam corrosion.
Tin controls the reaction between silver and mercury.
Without tin the reaction would be too fast and the setting
expansion would be unacceptable.
– Reduces strength and hardness.
– Reduces the resistance to tarnish and corrosion, hence
the tin content should be controlled.
Composition
The powder contains:
•
Copper 0-30% – increases the mechanical strength
and hardness of the dental amalgam but reduces the
creep and increases the expansion of the finished
product. In a proportion of over 15-20% copper also
has antiseptic properties.
•
– Increases hardness and strength.
– Increases setting expansion.
•
•
Platinum
Hardens the alloy and increases resistance to
corrosion.
•
•
Palladium
Hardens and whitens the alloy.
•
•
Indium
Indium when added to the mercury reduces mercury
vapor and improves wetting. Indium can also be
added to the powder. Though it reduces early
strength it increases the final strength.
•
•
Zinc 0-2% acts as a binder, increases strength,
provides gloss and facilitates crushing and
condensation of the amalgam. Its presence in larger
quantities requires a good isolation of the operating
field, otherwise by contamination with liquid it will
convert to zinc oxide and will cause an excessive late
expansion of the amalgam.
Zinc acts as a scavenger or deoxidizer during
manufacture, thus prevents the oxidation of
important elements like silver, copper or tin.
Oxidation of these elements would seriously affect
the properties of the alloy and amalgam. Alloys
without zinc are more brittle, and amalgam formed
by them are less plastic.
Zinc causes delayed expansion if the amalgam mix is
contaminated with moisture during manipulation.
Composition
The powder contains:
• Mercury must contain less than 0.02% non-volatile residues and show no surface
contamination. Mercury can be easily contaminated by sulfur-containing
atmospheric gases, forming sulfides (the surface looks like a mirror).
• It combines easily with many metals (gold, silver, copper, tin, zinc), forming
amalgams.
• It does not combine with metals such as nickel, chromium, molybdenum, cobalt, iron.
• The solidification point of mercury is -39 ° C. Boils at 357 ° C. Drops falling on smooth
surfaces retain their spherical shape (due to the increased value of surface tension,
which is 6.5 times higher than water).
• In some brands, a small amount of mercury (up to 3%) is added to the alloy. They are
known as pre-amalgamated alloys. Pre-amalgamation produces a more rapid
reaction.
Manual mixing
• A glass mortar and pestle is used. The
mortar has its inner surface roughened to
increase the friction between amalgam and
glass surface. A rough surface can be
maintained by occasional grinding with
carborundum paste. A pestle is a glass rod
with a round end.
• The three factors to obtain a well mixed
amalgam mass are
1. The number of rotations,
2. The speed of rotation and
3. The magnitude of pressure placed on the
pestle. Typically a 25 to 45 second period is
sufficient.
Mechanical trituration
• Mechanical amalgamators are more commonly used to triturate amalgam alloy and mercury
• The disposable capsule serves as a mortar.
• The capsule is inserted between the arms on top of the machines. When switched on, the arms holding
the capsule oscillate at high speed thus triturating the amalgam.
• Most amalgamators have hoods that cover the arms holding the capsule in order to confine mercury
spray and prevent accidents. Reusable capsules are available with friction fit or screw-type lids.
• The lid should
fit the capsule
tightly,
otherwise, the
mercury can
spray out
from the
Mixing time
• The mixing time can vary depending on the speed,
oscillating pattern, and capsule designs.
• Spherical alloys usually require less amalgamation time
than do lathe-cut alloys. A large mix requires slightly longer
mixing time than a smaller one. Manufacturer’s
recommendations should be followed when determining
mixing speed and time.
Advantages of mechanical trituration
• 1. Shorter mixing time.
• 2. More standardized procedure.
• 3. Requires less mercury when compared to hand mixing
technique.
Under-triturated mix
• It is rough and grainy and may crumble
• It gives a rough surface after carving and
tarnish and corrosion can occur.
• Strength is less.
• Mix hardens too rapidly and excess mercury
will remain.
Normal mix
• It has a shiny surface and a smooth and soft
consistency
• It may be warm (not hot) when removed from
the capsule.
• It has the best compressive and tensile
strength.
• The carved surface retains its lustre after
polishing, hence increased resistance to
tarnish and corrosion.
Over-triturated mix
• The mix is soupy, difficult to remove from
capsule and too plastic to manipulate
• Working time is decreased.
• Results in higher contraction of the
amalgam.
• Strength increases for lathe-cut alloys,
whereas it is reduced in high copper
alloys.
• Creep is increased.
PreProportioned Capsules
• Preproportioned capsules contain alloy powder and mercury in compartments separated by
a membrane.
• They usually contain 400, 600, 800 or in rare cases 1200 mg of alloy powder with
corresponding proportion of mercury. Before use, the membrane is ruptured by compressing
the capsule, and the capsule is then placed in a mechanical amalgamator.
PreProportioned Capsules
• Advantages
• 1. Consistent proportioning.
• 2. Low mercury/alloy ratio.
• 3. Physical handling not
required thus reducing health
hazard.
• Disadvantages
• Mercury and alloy may leak.
The dentist is forced to use one
alloy/mercury ratio for all
situations when using
disposable capsules. Also, the
disposable capsules are
expensive.
Advantages and disadvantages of amalgam
restorations
• Disadvantages
Advantages
1. Reasonably easy to insert.
2. Not overly technique sensitive.
3. Maintains anatomic form well.
4. Has adequate resistance to fracture.
5. Self-sealing; minimal-to-no shrinkage and
resists leakage.
• 6. Durable and long lasting.
• 7. Wears well and causes minimal wear of
natural teeth.
• 8. More economic than other alternative
posterior restorative materials like cast gold
alloys and composite.
•
•
•
•
•
•
• 1. The color does not match tooth structure.
• 2. They are more brittle and can fracture if
incorrectly placed.
• 3. Requires removal of some healthy tooth
structure for cavity designing.
• 4. They are subject to corrosion and may
darken as it corrodes.
• 5. Corrosion products may stain teeth over
time
• 6. Galvanic action. Contact with other metals
may cause occasional, minute electrical flow.
• 7. They eventually show marginal
breakdown.
• 8. Temporary sensitivity to hot and cold
because it is a metal.
• 9. They do not bond to tooth structure.
• 10. Environmental mercury concerns.
Thank you for your attention!
Dental bases and liners
Marcela Tighineanu,
Department of Stomatological Propaedeutics “Pavel Godoroja”
117
Liners
• Some materials for permanent filling have an unfavorable action on the
pulp, or don’t provide a good sealing.
• For this reason, liners are used.
• 1. Base
• A 0.75-1.0 mm thick layer of base is applied.
• It has the protective role of the pulp of thermal, chemical excitants;
• 2. The liner
• A fine layer of material;
• It has the purpose of chemical isolation of the pulp and it ensures the
connection between the cavity walls and the permanent restoration
material.
Bases
• A base is a layer of cement placed beneath a permanent
restoration to encourage recovery of the injured pulp and to
protect it against numerous types of insults to which it may
be subjected. The type of insults depends upon the
particular restorative material. It may be thermal or
chemical or galvanic. The base serves as replacement or
substitute for the protective dentin, that has been destroyed
by caries or cavity preparation. Nonvital teeth do not
require a base.
Types
• High strength bases
• These are used to provide thermal
protection for the pulp, as well as
mechanical support for the
restoration.
• Examples of high strength bases:
Zinc phosphate, Zinc
polycarboxylate, glass ionomer and
reinforced ZOE cements.
• Some important properties of
cements used as high strength bases
are strength, modulus of elasticity
and thermal conductivity.
• Low strength bases
• Low strength bases have minimum
strength and low rigidity. Their
main function is to act as a barrier
to irritating chemicals and to
provide therapeutic benefit to the
pulp. Examples are: calcium
hydroxide and zinc oxide eugenol.
Properties
• Thermal properties
• The base must provide thermal protection to the pulp. This property is
important especially when the tooth is restored with metallic restorations.
• For effective thermal protection the base should have minimal thickness of 0.75
mm.
• Protection against chemical effects
• Calcium hydroxide and zinc oxide eugenol are most effective for this especially
in deep (close to the pulp) cavities. Polycarboxylate and glass ionomer bases are
also used as chemical barriers in more moderate cavities.
Properties
• Therapeutic effect
• Some bases are used for their therapeutic benefit to the
pulp. For example, calcium hydroxide acts as a pulp capping
agent and promotes the formation of secondary dentin. Zinc
oxide eugenol has an obtundent effect on the pulp.
Properties
• Strength
• The cement base must have sufficient strength to
– Withstand the forces of condensation. Fracture or displacement of the base
permits the amalgam to penetrate the base and contact the dentin. Likewise,
in deep cavities the amalgam may be forced into the pulp through
microscopic exposures in the dentin.
– Withstand fracture or distortion under masticatory stresses transmitted to it
through the permanent restoration.
• Also the cement base should develop sufficient strength rapidly in order to allow
early condensation of amalgam. The minimum strength requirement of a base is
between 0.5 and 1.2 MPa.
Liners
• A cavity liner is used like a cavity varnish to provide a
barrier against the passage of irritants from cements or
other restorative materials and to reduce the sensitivity of
freshly cut dentin. They are usually suspensions of calcium
hydroxide in a volatile solvent. Upon the evaporation of the
volatile solvent, the liner forms a thin film on the prepared
tooth surface.
Classification of liners
• Zinc-phosphate cement;
• Polycarboxylated cements;
• Glass ionomer cement;
• Adhesive systems for composites.
Curative filling materials
• They are applied on the floor of the cavity, for the purpose of treating
inflammatory processes in the pulp or for remineralizing the hard
tissues. It is most often marketed as a paste. They are necessary for
stimulating the natural mechanisms of protection of the dentine and
pulp.
Classification of curative filling materials
•
Materials containing calcium hydroxide:
– self-curing;
– light-cured;
•
Zinc-eugenol cement:
– Zn-oxide-eugenol cements (unmodified) (ZOE);
– modified (reinforced) Zn-oxide-eugenol cements with polymer fillers (with methyl polymethacrylate);
– modified Zn-oxide-eugenol cements (reinforced) with alumina and orthobenzoic acid.
•
Curative paste containing fluoride:
– Elmex gel;
– Zinc-phosphate cement with fluorine.
•
Combined medicinal pastes, containing curative remedies:
– curative pastes combined, ready-made;
– combined curative pastes, prepared in pharmacies.
Requirements for curative filling
materials
•
Not to have irritating action on the dental tissues;
• To possess antiseptic, reparative properties;
• Plasticity;
• Good adhesion to dental tissues;
• To ensure a good sealing of the underlying dentin, connection with the hard dental
tissues, insulation and permanent sealing materials;
• To meet the physico-mechanical requirements of the definitive sealing materials.
Calcium hydroxide materials
• Curative filling materials are most often used in dental practice;
• Composition: calcium hydroxide with pH 12.4;
• It is sensitive to the action of CO2, turning into calcium carbonate;
• Due to the high pH, ​a degeneration and necrosis area initially
appears up to 50 mkm, after 3 months – the formation of tertiary
dentin begins.
Classification of materials based on
calcium hydroxide
• Water-based calcium hydroxide;
• Calcium hydroxide varnishes;
• Self-curing cements;
• Photopolymer materials based on calcium hydroxide.
Indications
• For direct and indirect pulp capping.
• As low strength bases beneath restorations for pulp
protection.
• Two paste system containing base and catalyst pastes in soft
tubes
Self-curing cements
Photopolymer materials based on calcium
hydroxide
Zinc-eugenol cement
• It has 2 components: powder and liquid.
• The powder is based on zinc oxide and additional
components to accelerate its hardening.
• The liquid is based on eugenol or clove oil and ethyl alcohol
to accelerate hardening.
Properties
• Antiseptic and pain-relieving action;
• Provides good sealing;
• Radiopaque;
• Long working time;
• Low resistance;
• High solubility at the action of the saliva;
• It cannot be used in combination with composite materials;
• Potential allergen.
Curative materials
• They may contain vitamins, ferencylates, salicylates,
antiseptics, antibiotics, preparations from the
sulphanilamide group, anesthetics, oils etc.
• It is mixed immediately before application. The entire floor
of the cavity is covered. It is applied for a short time (1-2
days). They don’t harden.
Combined materials for curative fillings
• As a base, they may contain ZnO or artificial dentine
powder, prepared with antiseptic, anesthetic, proteolytic
properties.
• The paste is kneaded with a calcium salt (eg 10% calcium
chloride solution).
• It has a plastic action, to stimulate regeneration.
Combined materials for curative fillings
• 1. Odontotropic remedies are substances that stimulate the
formation of dentin and remineralization processes in the
area of demineralized dentin: calcium hydroxide, fluorides,
calcium glycerophosphate, dentinal or bone sawdust,
hydroxylapatites (natural and artificial), collagen.
Combined materials for curative fillings
• 2. Anti-inflammatory remedies: steroids – glucocorticoids
(prednisolone, hydrocortisone), less often – non-steroids
(salicylates, indomethacin)
Combined materials for curative
fillings
• 3. Antimicrobial remedies: chlorhexidine, metronidazole,
lysozyme, sodium hypochlorite, ethonium paste (7% ethonium in
artificial dentin). The rationality of including antibiotics in the
composition of the curative filling is currently actively challenged.
• a) Metronidazole (Metronidasolum). The pharmacological action
has a wide spectrum of activity against anaerobic flora. It is used
for irrigation of carious cavities and is part of the combined
medicinal pastes.
• b) Lysocym. Pharmacological effect – it is a protein ferment, has a
bacteriolytic effect, inhibits the growth of Gram+ microbes, exerts
an antiviral, anti-inflammatory and mucolytic action.
Combined materials for curative fillings
• 4. Proteolytic enzymes – Trypsin (Trypsinum), crystalline
chemotrypsin (Chymotrypsin crystallisatum) exerts a
disinfectant and anti-inflammatory action, decomposes
necrotic tissues, fibrous structures. Being combined with
other substances (for example, chlorhexidine), they can be
quite effective in treating deep caries and pulpitis.
Combined materials for curative fillings
• 5. Other remedies: hyaluronidase, EDTA (ethylene diamine
tetraacetate), dimexid, kaolin, zinc oxide, lidocaine and
various oils = neutral [inert, non-exciting] essences, – sea
buckthorn, cloves, peach, eucalyptus, camphor, oily vitamin
solutions (vitamin A, vitamin E), glycerin.
Thank you for your attention!
Dental Ceramics. Porcelain
Marcela Tighineanu,
Department of Stomatological Propaedeutics “Pavel Godoroja”
146
Dental Ceramics. Porcelain
• Ceramics contain strong, directional, ionic bonds between
metals and oxygen that impart strength but will not tolerate
distortion.
• Ceramic can mimic tooth aesthetics better than any other
material. The first use of ceramic in dentistry was for denture
teeth.
• The terms ceramic and porcelain are often used interchangeably,
but incorectly.
According to firing temperature
• H
•igh fusing 1200-1400C°
• Medium fusing 1050-1200°C
• •
Low fusing 870-1050°C •
• Ultra low fusing less than 870°C
According to the number of layers
• Basic ceramics (ceramic core);
• Ceramics for dentine (more translucent);
• Ceramic for enamel (with a high degree of translucency).
Depending on the purpose for which they
are used:
1. Ceramic masses for making artificial teeth and prefabricated
veneers for which high melting point ceramic is used;
2. Ceramic masses for fully ceramic prosthetic restorations, for which
medium melting point ceramics are used;
3. Ceramic masses for metal-ceramic reconstructions, where low
fusion ceramic is used, which does not exceed the melting point of
the alloy to which it is applied.
Most current ceramics consist of two phases:
I. •
Glassy phase—acts as the matrix
II. •
Crystalline phase—dispersed within the matrix and
improves strength and other properties of the porcelain, e.g.
quartz, alumina, spinel, zirconia, etc.
• The structure of porcelain is similar to that of glass. The basic
structure therefore consists of a three dimensional network of
silica.
Composition of ceramic masses:
• Basic components:
• Kaolin;
• Feldspar;
• Quartz.
• Fluxes, metal oxides, additional or flux agents.
Kaolin
• As a raw material, it is used to give the plasticity of the material in
the initial stages of processing. It is a variety of higher clay. By
mixing with water, it forms a paste that can be molded.
• It is added to porcelain as a binder and provides rigidity to the
product.
• It is considered a powerful opacifier, so it is used in a smaller and
smaller proportion.
Quartz
• It must be as pure as possible to avoid staining of the burnt product.
• Quartz is a form of silica. It is the one that gives the ceramic mass
resistance, contributes to its translucency and maintains its shape
during combustion, due to the very high melting temperature.
Feldspar
• It is the main component of dental porcelain, and the
proportion of feldspar to other ingredients makes these
ceramic masses much different from industrial porcelain.
• Feldspar has the role of matrix in ceramic masses, for kaolin
and quartz. It is the one that gives the porcelain – translucency.
The release form
1. industrial
2. laboratory
Industrial
• Teeth with short cramps used for making total and partial prostheses;
• Veneers with short or long cramps, used for making bridges and which are
fixed by riveting or cementing;
• Physiognomic crowns – Logan, Davis, for unidentar prostheses;
• Veneers Steel;
• Ceramic implants: Bioceram, Cerapore, Frialit, Cerasiv.
Laboratory
•
•
a)
b)
c)
•
•
•
•
•
In the form of Powders, marketed in:
3 basic assortments:
base layer (primer, opaquer)
dentin layer;
enamel layer.
Accessory masses (additional):
Correction masses;
Masses for coloring;
Transparent mass.
Manufacturers pack these masses in numbered (glass) bottles, delivered in sets.
Laboratory
• Liquid, represented by:
• Distilled water mixed with:
•
glycerin;
•
dextrin;
•
special solutions, which facilitate the cohesion of the particles of the raw paste.
• In addition to these 2 basic components, we also need:
•
color key;
•
modeling tools;
•
brush no. 1, 5, 8, 12;
•
glass rods.
Stages of firing of ceramic masses on
metallic structure: (1)
• Prior to combustion, the metal component is prepared
for fusion with the ceramic, blasted, degreased and
subjected to a 4-5 minute oxidation burn at 900-960C
in the presence of air.
• Prepare the opaque mass by mixing the powder with
distilled water on a plate and then brush a layer with a
thickness of 0.30 mm by vibration and buffering with
filter paper.
Stages of firing of ceramic masses on
metallic structure: (2)
• The firing is then carried out under vacuum conditions at
960C-10 minutes followed by burning in air for 3 minutes. The
material from the firing undergoes a contraction, so the layer
will have a thickness of 0.25mm.
• The dentin and enamel layer is then deposited by vibration
and permanent buffering. The shape of the crown is oversized
in all directions to compensate for the contraction.
Stages of firing of ceramic masses on
metallic structure: (3)
• The enamel and dentine border should be blurred to prevent
the demarcation between the 2 porcelains. It should be
applied to oven door 5-10 minutes for drying.
• Place in the oven at 750C and gradually heat up to 960C under
vacuum conditions. Allow to cool slowly.
Stages of firing of ceramic masses on
metallic structure: (4)
•
•
The ceramic is processed to fit the dimensions and morphology of the natural tooth.
The glaze is then made by firing in the presence of air at 900-930C, thus obtaining a glossy mass.
• Porcelain can be polished using special abrasives. Porcelain
is an extremely hard material and is quite difficult to polish.
• Glazing is considered to be superior to conventional
polishing.
Objectives of glazing
1. Glazing enhances esthetics.
2. Enhances hygiene.
3. Improves the strength. Glazed porcelain is much stronger
than unglazed ceramic. The glaze inhibits crack propagation.
4. Reduces the wear of opposing teeth. The rough surface on
unglazed porcelain can accelerate wear of the opposing
natural teeth.
The characteristics of the ceramic masses.
Contraction
• It undergoes volumetric changes manifested by contractions
of 15-25%, one of their major disadvantages.
• The contraction is influenced by:
• Granulation of the ceramic mass (by using masses with
granules of different sizes and shapes, the degree of
contraction of the respective mass is greatly reduced).
The characteristics of the ceramic masses.
Contraction
• The condensation technique used (condensation aims – the removal
of water from the deposited ceramic paste and influences the
subsequent contraction).
• There are a number of condensation techniques:
1. vibration (most commonly),
2. spatulation,
3. brush application,
4. magnetization,
5. pressing,
6. combinations between different techniques.
The characteristics of the ceramic masses.
Contraction
• Firing – the most important form of contraction. It starts from drying by
evaporating water or alcohol from the composition. A second phase occurs
at 600-800C, by burning the organic additives used as a binder. During firing
, contraction occurs due to the elimination of air bubbles, which, despite all
the condensation done, remain in large numbers.
• The contraction is greater where the thickness is greater.
• It is influenced by the amount of fluid and temperature.
• Ceramic masses with a lower melting temperature have a higher contraction
compared to those with a higher melting point.
The characteristics of the ceramic masses.
Hardness
• It is large 400-417 units on the Brinell scale (uB).
• They are tougher than dental enamel (280-300 uB) and even
Cr-Co alloys (360-380 uB).
• The extremely high hardness causes uneven abrasion of
antagonistic teeth.
Pressure resistance
• It is large, being dependent on the composition and the
internal structure, the presence of voids and air bubbles.
• The bending resistance is quite low, which provided for the
introduction of aluminum oxide into its composition.
• Ceramics are a brittle material.
Color stability
• It is large because they are chemically inert and impenetrable
for substances in the oral environment.
The characteristics of the ceramic masses.
Translucence
• It is very good, which recommends ceramics as a valuable restoration material.
The characteristics of the ceramic masses.
1. From a biological point of view, they have a good tolerability
when used as replacement teeth, veneers or implants.
2. Extremely smooth surfaces.
3. Low surface tension.
4. Electrostatic rejection make the accumulation of bacterial
plaque on their surfaces less than on any other restorative
material, including natural tooth enamel.
New ceramic systems
HI-CERAM-VITA
• It consists of successive firing of the ceramic mass on a unit
model of silico-phosphatic refractory material.
• On this model the layers in the number of 2-3 of the nucleus
are burned at the average fusion temperatures of the ceramic
mass; over this core the system-specific dentin, enamel and
glaze layers burn.
CERESTORE (Johnson&Johnson)
• It consists of synthesizing ceramics on an aluminum-ceramic
core.
• The core is initially made in the form of a wax model, which is
packaged, obtaining a pattern.
• A thermoplastic tablet made of aluminum-ceramic material is
heated and injected inside the mold.
• The formed layer represents the substrate on which the
ceramic is applied.
IN-CERAM-VITA
• The most used system for obtaining totally ceramic works and is
based on aluminum cores that are infiltrated with a glass to obtain
high strength substrates.
• A duplicate model is made of a special gypsum on which alumina is
applied, obtaining a layer, which, after being burned at the specific
fusion temperature, is armed with glass powders and burned for a
long time (4h 1100C).
• Ceramic masses of dentin, enamel, glaze burn on the ceramic
skeleton formed by the reinforced layer.
• The aluminous core can be replaced by a crystalline structure
represented by magnesium aluminate in order to increase the
translucency, but with lower mechanical qualities.
IN-CERAM-VITA
There are systems containing 33% zirconium oxide in the core composition
to increase mechanical strength, but with lower aesthetic properties.
Advantages
• Good fit and marginal
adaptation.
• Good strength when compared
to the earlier all ceramic
crowns. Claimed to be strong
enough for posterior single
crowns and anterior dentures
use.
Disadvantages
•Comparatively less esthetic
because of the opacity of the
alumina core.
•Quite tedious to fabricate.
•Not all the dentures were
successful, a few of them did
fracture occasionally.
EMPRESS Technique
It uses a feldspat ceramic reinforced with leucite (40-50%).
Leucite crystals can increase the breaking resistance of the
feldspar glass matrix.
• The technique consists in the printing of a ceramic ingot in
plastic state in a thermal press (1100C) followed by the
firing of the incision and the glaze.
• ADVANTAGES
A. Better fit (because of lower firing shrinkage).
B. Better esthetics due to the absence of metal or an opaque
core.
• DISADVANTAGES
• Need for costly equipment.
• Potential of fracture in posterior areas.
•
Mechanical processing techniques
• It requires expensive equipment and allows to obtain
completely ceramic restorations by successively
reducing, from a ceramic block of a certain volume,
until the final shape is reached.
1. Mechanical copying techniques
2. Computerized milling techniques.
CAD/CAM
Computer assisted desing and computer assisted machining
• CAD/CAM dental restorations are milled from solid blocks of ceramic or composite resin closely
matching the basic shade of the restored tooth. After decayed or broken areas of the tooth are
corrected by the dentist, an image (scan) is taken of the prepared tooth and surrounding teeth.
• This image, called a digital impression, draws the data into a computer. Then a software is used to
create a replacement part for the missing areas of the tooth, essentially creating a virtual
restoration.
• The software sends this virtual data to a milling machine where the replacement part for the
defect (the dental restoration) is carved out of a solid block of ceramic or composite resin.
• Stains and glazes are fired to the surfaces of the milled ceramic crown or bridge to correct the
otherwise monochromatic appearance of the restoration.
• The resulting restoration can then be adjusted in the patient’s mouth and cemented or bonded in
place.
• Depending on the restorative material, cementing/bonding surface areas on the tooth and the
restoration may be respectively etched and silanized. Resin cement is then used to fuse the
restoration to the prepared tooth, completing the restorative treatment process.
CAD/CAM
Thank you for your attention!
Marcela Tighineanu,
Department of Stomatological Propaedeutics “Pavel Godoroja
186
Obturation
• Obturation – the final stage of dental
caries treatment, which seeks to restore
the lack of substance at the level of hard
dental tissues.
• The main purpose – to restore the morphology of
the tooth, the lost functions and the protection
of the pulp from the external harmful factors.
• The success of the obturation treatment
depends on the type of material chosen; its
physical, chemical and mechanical properties.
• It is necessary for the dentist to know the
reaction of the hard dental tissues and the
periodontium to the filling material, as
well as the possible modifications that it
may undergo during the work.
• Currently, new sealing methods are being
developed, which allow the restoration of
Restoration
• Restoration – replacement of lost hard dental tissues with
restorative materials, aiming to restore the initial aesthetic and
functional parameters. The criterion of distinction between
obturation and restoration – the quality of restoring the initial
parameters of the tooth.
• Restorations may be classified in a number of different ways.
• Types of restorations
1. Temporary, intermediate and permanent
2. Direct and indirect
3. Aesthetic and non-aesthetic
Reconstruction
• Reconstruction – modification of the initial
parameters, the basic characteristics of the
tooth, in order to improve the aesthetic,
functional properties.
Requirements for restorative materials (1)
• Chemical stability in the oral environment;
• Mechanical resistance during chewing;
• Color, transparency, translucency as close as
possible to that of natural teeth;
• Abrasion resistant;
• Good adhesion to the cavity walls;
• To keep their shape and volume for a long time;
Requirements for restorative materials (2)
• To be tolerated by the tissues of the oral cavity,
not to irritate the pulp, periodontitis, mucosa of
the oral cavity;
• Not to contain toxic, harmful components;
• To possess protective action against relapse;
• To be bad thermal conductors, in order to
exclude the thermal excitation of the pulp;
• To have a coefficient of thermal expansion,
similar to that of natural teeth;
Requirements for restorative materials (3)
• To maintain plasticity during modeling;
• Minimum humidity dependence during the
filling and polymerization process;
• Radiopacity;
• Long term and do not require special
conditions for use, storage, transport.
Classification of contemporary filling materials
1. Materials for dressings and temporary
coronary fillings;
2. Materials for basic curative fillings;
3. Materials for basic insulating fillings;
4. Permanent filling materials;
5. Materials for filling root canals.
Classification of filling materials
• The filling materials are divided into 6 groups according to their
functional destination:
• I. Permanent filling materials = permanent (long-lasting) – for
restoring the dental anatomical shape and masticatory functions
• 1. Direct filling materials:
• Cements (mineral, polymeric)
• Metal fillers (amalgams)
• Polymeric fillers (plastics, composites, compomers, ormoceres)
2. Indirect filling materials:
• metal
• ceramic
• polymers
• II. Materials for temporary coronary fillings
– for temporary filling of the dental cavity.
• III. Materials for curative and insulating
fillings (linings):
• Curative
• Insulators
• IV. Materials for filling of the root canals
• 1. Temporary filling materials
• 2. Sealers
• 3. Fillers (gutta-percha)
• V. Dental adhesives
• Self-curing (with chemical polymerization)
• Light cure
• Dual cure
• VI. Sealers
• Fissure sealers
• Endodontic sealers
• Filling sealers
Classification of permanent filling materials, by plasticity
at the time of filling and by chemical composition
Classification of the restorative
materials according to the curing
mode
1) Self-cured – chemical polymerization
(amalgam, mineral and polymer cements, selfcuring composites)
2) Light-cured
3) Double polymerization (hybrid glass ionomer
cements, compomers)
Temporary filling materials
• Temporary filling materials are used for temporary
sealing of the cavity (for diagnostic or curative
purposes) in cases where, according to clinical
indications, it is impossible to complete the
treatment of caries and its complications in a single
visit, in order to isolate the carious or dental cavity
(or root canals) from the of the external
environment, or for the application (fixation) of
medicinal preparations.
Indications of the temporary restorative
materials:
1) For dressings (treatment of dental caries and
its complications);
2) For filling temporary teeth;
3) As a liner;
4) For temporary fixation of dentures;
5) For filling the root canals for treatment
purpose.
Requirements for temporary
restorative materials:
1) Hermetic closure of the tooth cavity (minimum 2
weeks);
2) Suitable hardness, can be removed with a dental probe,
excavator or rotary instruments;
3) Indifference to dental pulp;
4) Easy to be inserted and removed from the cavity;
5) Lack of changes at the action of saliva and buccal fluid;
6) The lack of components that would slow down the
process of application, modeling, hardening of the
materials for permanent seals.
Materials for dressings and temporary
restorations
1) The temporary filling materials are applied to the
surfaces of the walls and the floor, previously dried;
2) The morphology and the contact point are restored;
3) The materials for temporary fillings can be used for the
purpose of isolating the curative paste, applied on the floor
of the cavity, in the pulp chamber or at the level of the
ostium;
4) Can be used as a temporary tooth filling material (when
less than 6 months left until their physiological exchange)
• The dressing is a variant of the temporary filling, applied
for a period of 1-14 days in case of the need to isolate an
underlying toxic drug, applied temporarily, from contact
with the environment of the oral cavity (arsenic paste,
paraformaldehyde paste).
• The patient is warned about the necessity to go to the
doctor for an additional visit (once) to remove the
dressing or to remove it on his own (by brushing).
• The dressings are applied for a period of 1-14 days:
✓Artificial dentine;
✓Dentin-paste;
✓Vinoxol (zinc-sulphate cement).
• Temporary seals are applied for several months (up
to 6 months). Ex: Zn-eugenol, Zn-phosphate,
sometimes polycarboxylated or glasionomeric
cements.
Artificial dentine (zinc-sulphate
cement)
• Composition: 66% ZnO; 24% Zn sulphate; 10% kaolin. It
is mixed with distilled water.
• Properties:
â–ª it hardens in 3-5 minutes;
â–ª easy to use;
â–ª good sealing;
â–ª indifference to the pulp;
â–ª low cost;
â–ª it can only be applied for a short time (up to 2 weeks).
Dentin-paste
• Composition: powder similar to the composition of artificial
dentine; but that is mixed with clove oil and peach oil.
• It is marketed as an already kneaded paste (tubes or bottles).
• Properties:
• It strengthens at body temperature, in the presence of buccal fluid,
for 1.5-3 hours;
• Easy to use;
• It does not require mixing;
• Hardness and strength greater than artificial dentine (water based);
• Antiseptic action;
• When condensing, it adheres to
the instrument, therefore it is
recommended to apply it in the
cavity with a lightly moistened
cotton roll. Because dentin paste
has a longer curing time, it is not
recommended to use it in
combination with arsenic paste.
• There is the danger of excessive
harmful action of the devitalizing
paste, its leakage, which could
lead to tissue necrosis.
• Cloves and peach oils can disrupt the
polymerization process of composites and
negatively influence their adhesion to dental
tissues. For this reason, it is not
recommended to use the materials that have
in their composition the clove oil, before the
restoration with composites.
The following types of materials are
marketed:
Zinc-eugenol cements
are used as temporary filling materials
Vinoxol
• Composition: 89% ZnO powder; calcium sulphate 5%; calcium
carbonate 6%; liquid.
• Properties: high strength (up to 6 months), good adhesion, antiseptic
properties.
• Mix on the glass in the proportion of 9-10 drops of liquid on one side of
dust, for 30 seconds, until the consistency of a paste is obtained.
• It is cured for 3-4 hours in the oral cavity.
Photopolymerizable materials for
temporary seals
“Сimpat LC” (Septodont), “Сlip” (Voco), “Fermit” (Vivadent).
Easily applied and removed from the cavity;
Preserves elastic properties after hardening;
Good marginal adaptation;
Some materials contain F, which allows the remineralization of
hard dental tissues. Ex. Clip F (Voice);
• High cost;
• It is introduced into the cavity in a single portion, then it is cured
for 20-40 sec.
• The purpose of their use is to create an intermediate layer
between the filling material and the dentin / tooth pulp.
•
•
•
•
•
Light-curing material with fluoride for
temporary restorations
• Easy to place-remove in one piece;
• Time-saving and economical;
• Tight margins and durable.
Thank you for your attention
Root canal filling materials
Marcela Tighineanu,
Department of Stomatological Propaedeutics “Pavel Godoroja”
1
• A root canal is a
complex 3D space.
The objective of
canal preparation
techniques is to
clean and shape
this space to
remove bacteria
and infected debris
and then to
prepare the space
to facilitate its
obturation.
• As a consequence, contemporary obturation materials need
to be plastic during placement to allow them to be moulded
to the canal form. It should also be possible to remove part or
the entire root filling with ease after it is completed, to allow
the use of a post to facilitate restoration of the tooth or repeat
endodontics if that is ever required.
• An ideal root canal filling should
be capable of completely
preventing communication
between the oral cavity and
periapical tissue. Root canal
sealers should be biocompatible or
well tolerated by the tissues in
their set state.
Grossman (1982) grouped the filling materials into plastics, solids, cements
and pastes. He also outlined 10 requirements for an ideal root canal filling
material:
1. Easily introduced into a root canal.
2. Seal the canal laterally as well as apically.
3. Not shrink after being inserted.
4. Impervious to moisture.
5. Bacteriostatic or at least not encourage bacterial growth.
6. Radiopaque
7. Non-staining the tooth structure.
8. Non-irritating.
9. Sterile/easily sterilized immediately before obturation.
10. Easily removed from the root canal if necessary.
Root canal sealers
• The sealer plays an important role in the obturation of root
canal.
• The sealer fills all the spaces that the gutta-percha is unable to
fill.
• A total hermetic seal of the root canal system is necessary to
prevent the reinfection of the canal. The sealer also acts as a
binding agent to the dentin and to the core material, which
usually is gutta-percha.
Ideal requirements of a root canal sealer
1. It should be tacky when mixed.
2. It should adhere well to the gutta-percha and the canal wall when set.
3. It should make a hermetic seal.
4. It should be radiopaque so that it can be visualized in the radiograph.
5. The particles should be very fine so that they can mix easily with the liquid.
6. It should not shrink upon setting.
7. It should not stain tooth structure.
8. It should be bacteriostatic.
9. It should set slowly to provide suitable working time.
10. It should be insoluble in tissue fluids.
11. It should be tissue tolerant, that is, nonirritating or toxic to periradicular tissue.
12. It should be soluble in a solvent if it is necessary to remove the root canal filling.
13. It should not provoke an immune response in periradicular tissue.
14. It should be neither mutagenic nor carcinogenic.
A Zinc oxide-Eugenol based
• Silver-containing (Rickert’s formula based)
Grossman’s formula based (Silver free)
Therapeutic – Formaldehyde
– Iodofor
• Pulp Canal Sealer (SybronEndo)
• Wach’s paste,Tubliseal (SybronEndo), Roths, Intrafill (SS White), Roth Root 801 (Roth) N2/RC2B, Endomethasone, SPAD, Riebler’s paste
• Zical (Prevest Denpro)
• Endomethasone N (Septodont), Endofill (Dentsply)
B Resin based
• BisGMA UDMA based
• Epoxy resin based
• Real Seal SE (SybronEndo), Acroseal (Septodont), Epiphany(Pentron), EndoREZ (Ultradent), Diaket (3M)
• Sealer 26 (Dentsply), AH Plus & AH-26 (Dentsply),
C Calcium hydroxide based
• CRS (Hygienic), Sealapex (SybronEndo), Life Apexit (Ivoclar) Vitapex
D Silicone based
• GuttaFlow (Coltene), RoekoSeal (Coltene)
E Glass ionomer based
• Ketac-Endo (ESPE)
F MTA based
• MTA Fillapex (Angelus), Endo CPM Sealer (EGEO), MTA Obtura (Angelus), ProRoot Endo Sealer (Dentsply)
– Steroid
Zinc Oxide-Eugenol-Based sealers
• Commercial names Tubli-Seal (SybronEndo), Pulp canal
sealer (SybronEndo), Roth’s cement, Procosol
• Rickert’s formula based (silver containing)
• The earliest sealers were made by dissolving gutta-percha in
solvents like chloroform and was termed ‘chloropercha’.
These sealers had problems resulting from shrinkage.
• Rickert’s formula was developed in 1931 as an alternative to
the chloropercha technique.
Composition
Powder
Zinc oxide
Precipitated silver
White resin
Thymol iodide
%
41.2
30
16
12.8
Liquid
Oil of clove
Canada balsam
%
78
22
• The silver was added for its radiopacity and germicidal qualities. It has
excellent lubricating and adhesive qualities. However, the silver content
caused discoloration of tooth structure. Pulp canal sealer is based on
Rickert’s formula.
• Grossman’s and Roth’s formula based (Silver free ZOE sealers)
• This includes most current ZOE sealers. In 1958, Grossman introduced a
nonstaining ZOE cement as a substitute for Rickert’s formula.
• This formulation is considered standard by which other cements are
measured because it reasonably meets most of Grossman’s requirements
for sealers. Many current sealers are still based on Grossman’s formula.
Composition
Powder
Zinc oxide, reagent
Staybelite resin
Bismuth subcarbonate
Barium sulphate
Sodium borate, anhydrous
wt %
42
27
15
15
1
Liquid
Eugenol
Zinc-phosphate cements
• This group includes: phosphate-cement, adhesive,
hydrophosphate-cement, phosphate-cement with silver.
These sealers are rarely used because:
✓The material hardens quickly (4-6 minutes);
✓High probability of irritation of the periapical tissues;
✓It is impossible to desobturate the canal in case of need;
✓The material is not resorbed in case of accidental discharge
after the apex;
✓Resorption of cement in the apical third.
Epoxy resin-based sealers
• Commercial names Diaket, AH-26, AH Plus (Dentsply), Adseal.
• Diaket was introduced by Schmidt in 1951.
• Advantages
1. Good adhesion.
2. Sets quickly in the root canal.
3. Low solubility and good volume stability.
4. Superior tensile strength.
• Disadvantages
1. It is highly toxic.
2. It is nonresorbable and forms fibrous encapsulation if extruded into the
periapical tissues.
AH-26
•
•
•
•
•
AH-26 was introduced by Schroeder 1957. It is an epoxy resin based sealer.
It is a powder-liquid system.
Powder
Silver powder
Bismuth oxide
Wt%
10%
60%
Hexamethylene tetramine
Titanium oxide
25%
5%
Liquid
Bisphenol diglycidyl ether
Manipulation and setting
AH 26 powder and resin are mixed to produce a root canal filling material. During the setting,
traces of formaldehyde are temporarily released, which initially makes it antibacterial. It is not
sensitive to moisture and will even set under water. It sets slowly, in 24 to 36 hours.
It has strong adhesive properties.
• Disadvantages
1. Slight contraction while setting.
2. Delayed setting.
3. Staining.
AH+
•
AH+ is an epoxy-amine resin based two paste root canal sealer. Epoxy paste contains radioopaque
fillers.
•
•
Composition
Epoxide paste contains bisphenol-A and F as epoxy resin, calcium tungstate, zirconium oxide, silica and
iron oxide pigments and Amine paste contains dibenzylediamine, aminoadmantace, tricyclodecanediamine, calcium tungstate zirconium oxide, silica and silicone oil.
• Advantages over AH-26
1. Less toxic.
2. New amines added to maintain the natural color of the tooth.
3. Half the film thickness.
4. Better flow.
5. Four-hour working time.
6. Eight-hour setting time allows for corrections of fillings.
7. Increased radiopacity.
Resorcinol-formaldehyde resin sealers
(russian red)
•
This group includes: paracin, fluorodent, bioplast, forfenan, resodent, resodent, resorcinolformalin paste.
Advantages
• Permanent antiseptic action
• Disinfection of the contents of the dentinal canals, deltoid branches
• Good handling properties
• Radioopacity
• Biological neutrality after hardening
Disadvantages
• High toxicity of components
• Irritant action on tissues
• Changes in the color of the dental tissue (of the crown of the tooth in pink)
Calcium hydroxide based sealers
• In endodontics, it is mainly used for pulp-capping procedures,
as an intracanal medicament, in some apexification
techniques, and as a component of several root canal sealers.
• The two most important reasons for using calcium hydroxide
as a root-filling material are:
1. stimulation of the periapical tissues in order to maintain
health or promote healing;
2. antimicrobial effects.
Calcium hydroxide pastes
• The materials lack the irritating
properties of ZOE cements, are less
soluble in tissue fluid, exert an osteogenic
effect on periapical bone and cement.
• Most often, they are used as nonsolidifying materials for temporary root
canal obturation.
• Due to the strong alkaline reaction (pHapprox. 12) calcium hydroxide when
filling the root canal, it exerts a
bactericidal action, destroys necrotic
tissues, stimulates osteo-, dentino- and
cementogenesis.
Setting of calcium hydroxide-based sealers
in root canals
• The setting time of calcium hydroxide-based sealers the root
canal is dependent upon the availability of moisture. The setting
reaction can progress very quickly even in canals which have
been inadequately dried.
• The amount of moisture required for the setting reaction reaches
the root canal by means of the dentinal tubules. The material
begins to set at the apex, as dentin is thinnest in this region and
the apical foramen admits additional moisture.
CRCS (Calciobiotic Root Canal Sealer)
• CRCS is essentially a ZOE/eucalyptol sealer to which calcium
hydroxide has been added for its called osteogenic effect.
• CRCS takes 3 days to set fully in either dry or humid
environments. It also shows very little water sorption.
• This means it is quite stable, which improves its sealant
qualities, but brings into question its ability to stimulate
cementum and/or bone formation. If the calcium hydroxide is
not released from the cement, it cannot exert an osteogenic
effect, and thus its intended role is negated.
Sealapex
• Sealapex is a zinc oxide based calcium hydroxide sealer containing
polymeric resin. It is available as a two paste system.
• Advantages
1. Biocompatible
2. Extruded material resorbs in 4 months
3. Good therapeutic effect.
• Disadvantages
1. Long setting time.
2. Absorbs water while setting and expands.
3. Poor cohesive strength.
Apexit Plus
• Apexit Plus is a radiopaque, non-shrinking root canal sealer paste that is based on calcium
hydroxide. It is available as a two paste system. It is used for the permanent obturation of
root canals and it is suitable for use in conjunction with all obturation techniques involving
gutta-percha.
• Working and setting characteristics
1. Long working time (over 3 hours at room temperature)
2. Setting Time – 3–5 hours in normal canals. Up to 10 hours in extremely dry canals.
• Advantages
1. Excellent tissue tolerance.
2. Durable sealing of the root canal due to the slight setting expansion.
3. Its easy flowing composition allows the material to adapt well even to morphologically
complicated canals.
4. Convenient application (static mix syringe and intracanal tip).
5. Better seal than that provided by Sealapex.
Glass ionomer-based sealers
Glass ionomer cements have been modified to be used as endodontic sealers. They have a low
toxicity and induce little tissue irritation.
• These cements adhere to dentine, but may be less good at sealing. Their physical properties are
better than zinc oxide eugenol, with less coronal leakage. Like restorative glass ionomer cements,
they leach fluoride, which is taken up by dentine. The composition and setting reaction are similar
to those of a luting glass ionomer.
• Commercial name Ketac-Endo
• Advantages:
1. Biocompatible.
2. Chemical bonding with the root dentine, hence strengthens the root.
3. Less solubility.
4. Dimensionally stable.
5. Less technique sensitive.
• Disadvantages:
1. Extruded sealer is highly resistant to resorption (delayed resorption).
2. Retrievability is difficult.
•
Mineral trioxide aggregate (MTA)
Mineral trioxide aggregate materials are indicated for various restorative, endodontic, and
regenerative dental procedures.
1. Vital pulp therapy (pulp capping and pulpotomy)
2. Apexification
3. Perforation repair (lateral and furcation)
4. Root-end filling
5. Internal bleaching
6. Resorption repair
7. As sealer and as obturating material (partial or complete).
• Commercial names
• The first commercially available product was a gray mineral trioxide aggregate, marketed as
• ProRoot® MTA (Dentsply). Subsequently for esthetic reasons a tooth-colored or white formulation
of MTA was introduced (Dentsply) in 2002.
• Currently Many MTA sealer formulations are available. These include Endo CPM Sealer (EGEO SRL,
Argentina), MTA Obtura (Angelus, Brazil), MTA Fillapex (Angelus), Endocem
• MTA (Maruchi, Korea) and ProRoot Endo Sealer (Dentsply Maillefer, Switzerland).
•
Mineral trioxide aggregate (MTA)
• Supplied as
1. Powder and liquid form (e.g. ProRoot MTA)
2. Two paste – base and catalyst in tubes (MTA Fillapex)
3. Two paste – in plunger tubes as static mixing system (MTA
Fillapex).
• Difference between white and gray MTA
• The difference between the gray and the white materials is
the presence of iron in the gray material, which makes up the
phase tetracalcium alumino-ferrite.
• Storage
• Powder form MTA pouches must be kept tightly closed and
stored in a dry area to avoid degradation by moisture.
• ProRoot MTA root repair material must be placed intraorally
immediately after mixing with liquid, to prevent dehydration
during setting.
Silver points
• Silver cones were themost widely used solid-core metallic filling material between
1940 to 1960.
• They have been replaced by gutta-percha and are rarely used currently.
• Jasper (1941) introduced silver cones which he claimed produced the same
success rate as gutta-percha and were easier to use.
• Rigidity provided by the silver cones made them easy to place and permitted
length control.
• They were mainly used for teeth with fine and curved canals which make the use
of gutta-percha difficult.
The disadvantages of silver points far outweigh their advantages
and their use has been discontinued
Advantages
1. A bactericidal effect.
2. Can be used in narrow and curved
canals.
3. Silver has more rigidity than guttapercha, and can be pushed into tightly
fitting canals and around curves.
Disadvantages
1. Silver points/cones have a circular
cross section unlike the canals which
may be oval hence a poor lateral seal.
2. Could show high levels of corrosion
3. Corrosion products are cytotoxic.
4. Retrievability may be difficult.
5. Preparation of canal for post and
core reconstruction is difficult.
Gutta-percha
• Gutta-percha is a polymeric resin-like material obtained from the
coagulation of latex produced by Palaquium gutta tree (commonly
known as the Isonandra gutta tree).
• Forms of gutta-percha
• Gutta-percha exists in three forms
1. α – (or alpha form)—runny, tacky and sticky
2. β – (or beta form)—solid, compactible and ductile
3. γ – (or gamma form)—amorphous and unstable form
• The α form is used with the thermomechanical and injectable
techniques.
• The β form is used with mechanical condensation techniques.
Supplied as:
1. Solid core Gutta-percha points
• –– Standardized points
• –– Nonstandardized points
2. Thermomechanical compactible Gutta-percha points
3. Thermoplasticized Gutta-percha
• –– Solid core system
• –– Injectable form
4. Medicated Gutta-percha
• –– Iodoform containing
• –– Calcium hydroxide containing
• –– Chlorhexidine containing
• –– Tetracycline containing
• Gutta-percha are supplied in point or pellet form.
• Tapered points of varying sizes. The sizes range from 15 to
80. The various sizes are usually color coded for easy
identification.
• Pellet form is used for the injectable technique.
Advantages and Disadvantages of Guttapercha
Advantages
1. It is compactible and adapts excellently
to the irregularities and contour of the
canal.
2. It can be softened and made plastic by
heat or by organic solvents
3. It is inert.
4. It is dimensional stable; when unaltered
by organic solvents, it will not shrink.
5. It is tissue tolerant (nonallergenic).
6. It will not discolor the tooth structure.
7. It is radiopaque.
8. It can be easily removed from the canal
when retreatment is indicated.
Disadvantages
1. It lacks rigidity. The smallest,
standardized gutta-percha cones are
relatively more difficult to use unless
canals are enlarged above size no. 25.
2. It lacks adhesive quality.
3. Gutta-percha does not bond to any
sealers.
4. It can be easily displaced by pressure.
5. Gutta-percha is almost wholly
dependent on a coronal seal to prevent
the apical migration of bacteria.
PROTAPER
F1
F2
F3
Стерильные бумажные штифты
F4
F5
F1
F2
F3
F4
F5
F2
F1
F2
F3
F4
F5
Thermaprep
Thermacut bur
Verifier for the appreciation of
the apical dimension
Post space bur
Calibrate the root canal with the Verifier,
which must be 0.5 mm shorter than the
working length, adhering tightly to the
walls.
1
2
3
Drying root canals with
sterile paper cones
Mixing the sealer and
applying it in a thin state on
the channel walls, using a
probe or a paper cone
1
2
3
Thank you for your attention!

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