Banding and bonding cements
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Transcript of Banding and bonding cements
DR. GAURAV ACHARYA
PG RESIDENT
DEPARTMENT OF ORTHODONTICS & DENTOFACIAL ORTHOPAEDICS
PEOPLES DENTAL COLLEGE AND HOSPITAL,
KATHMANDU, NEPAL1
Contents
1. Introduction
2. History
3. Zinc Phosphate Cement
4. Zinc Silicophosphate Cements
5. Zinc polycarboxylate Cements
6. Glass ionomer Cements
7. Resins
8. Bonding to unconventional surface
9. Summary
10.References2
Introduction
The cements may be classified by composition
into four categories:
• Phosphate → zinc phosphate and
silicophosphate
• Phenolate→ zinc oxide-eugenol and calcium
hydroxide
• Polycarboxylate→ zinc polycarboxylate and
glass-ionomer cements
• Resin cements3
Introduction contd..
Cements are used for :
Luting of preformed restorations and
orthodontic Bands
Thermal and chemical insulators under
restorative materials
Temporary or permanent restorations
Root canal sealers
4
Introduction contd..
Cements are used for :
In orthodontics,
• Luting of appliances
• Luting of molar bands
• Bonding of Brackets on tooth surface
5
Introduction contd..
Properties:
• Adequate working and setting times
• High tensile, compressive and shear
strengths
• Resistance to dissolution
• Clinically acceptable bond strength
6
Introduction contd..
Banding and bonding cements
Zinc Phosphate cement
Zinc silicophosphate cement
Zinc Polycarboxylate Cement
Glass ionomer Cement
Resin Cement
7
History
Zinc phosphate and zinc polycarboxylate
cement used earlier.
Glass ionomer cement was first bracket
adhesive to release fluoride and bond to
enamel
8
History
Direct bonding only really became practical
― with the introduction of Resin
composite orthodontic adhesive and
phosphoric acid etching of enamel.
Resin modified glass ionomer cements
― bond to unetched enamel in a moist
environment.
9
Zinc Phosphate
• Oldest luting cements
• Widely used for
cementation of
orthodontic bands
10
Zinc Phosphate contd..
Composition
Powder
Liquid
11
Zinc Phosphate contd..
Setting Reaction
• Alkaline powder is dissolved by the acid
liquid
• Exothermic reaction
• Set cement is → hydrated amorphous
network of zinc phosphate that
surrounds incompletely dissolved
particles of zinc oxide.
12
Zinc Phosphate contd..
MANIPULATION
• Powder-to-liquid ratio for the cement
affects the working and setting times.
• A thin consistency (low viscosity) used as a
luting agent, to ensure adequate flow during
cementation of orthodontic bands.
• As specified ADA specification no. 96 (ISO
9917):
Working time: between 3 and 6
minutes13
Zinc Phosphate contd..
MANIPULATION
Powder should be incorporated into the
liquid in small portions and at a relatively
slow rate .
• Exothermic setting reaction is retarded
• Reduction in heat generation.
• The viscosity of the mixture remains
low
• Working time is increased 14
Zinc Phosphate contd..
MANIPULATION
Mixing → over a large
area of the glass slab
lower temperature
increase from the
setting reaction
provides extended time
for manipulation.
15
Zinc Phosphate
Care of the Liquid
exposure to dry air
loss of water
lengthened setting
16
Zinc Phosphate
Care of the Liquid
• the bottle tightly closed when not
dispensing the material
• Liquid dispensed just before mixing
17
Zinc Phosphate
Frozen Slab Method
→Glass slab and spatula are cooled below
5°C at freezer
→ thin layer of moisture deposited on the slab
when taken out from freezer
→Cement Is quickly mixed incorporating as
much powder as possible.18
Zinc Phosphate
Frozen Slab Method
Advantage:
working time of the mix on the glass slab Is
increased (about 10 minutes)
setting time in oral cavity is reduced (about
20 to 40%). 19
Zinc Phosphate contd..
• exhibits porosity as a result of
entrapment of air during mixing of the
powder and liquid
20
Zinc Phosphate
21
Zinc Phosphate
APPLICATIONS
1. For luting permanent
metal restorations
2. As a base
3. Cementation of
orthodontic bands
4. As a provisional
restoration.
22
Zinc Phosphate
Gross decalcifications observed after the
removal of orthodontic bands
Loss of the luting material between the
band and the tooth, resulting in a favorable
environment for bacterial action.
23
Zinc Phosphate
The Role of Zinc Phosphate Cement in Enamel Surface Changes on Banded Teeth; Per Johan Wisth; Angle Orthodontics Vol: 40, No: 4
The decalcification sometimes found under
orthodontic bands is not due to the action of
the phosphoric acid in the cement binding the
band to the tooth. However, it appears to the
contrary, that covering the tooth surface with
phosphate cement increases its resistance to
decalcification.24
Zinc Silicophosphate
• Hybrids of zinc phosphate and silicate
materials.
• Supplied as a powder and liquid.
• Liquid is an aqueous solution of
phosphoric acid
• Powder is mixture of zinc oxide and
black copper oxide.
• The settings reaction is similar to that for
zinc phosphate materials.
25
Zinc Silicophosphate contd…
translucent and esthetically superior
strength of zinc silicophosphate Is
superior than zinc phosphate cernent
Effective in caries inhibition due to
fluoride
Use is declining because of development
of esthetically better materials such as
resin and glass lonomer cements. 26
Zinc Polycarboxylate cements
► Introduced by Dennis Smith in 1967
►First dental material developed with
adhesive potential to enamel and dentin.
►Clinically similar to those
for zinc phosphate cements.
27
Zinc Polycarboxylate cements contd…
COMPOSITION
supplied as a powder and a liquid
Powder
• Zinc oxide
• 10% magnesium oxide
or tin oxide
• Silica, alumina, or
bismuth salts
• 4—5% of stannous
fluoride
• Pigments
Liquid
• acrylic acid
• Copolymer - as
itaconic and maleic
acids.
28
Zinc Polycarboxylate Cement contd..
Bonding to Tooth Structure
• bonds chemically to the tooth structure
• polyacrylic acid react with calcium ions
via carboxyl groups on the surface of
enamel or dentin
• bond strength to enamel is greater than
that to dentin. 29
Zinc Polycarboxylate Cement contd..
Manipulation
• Water powder ratio: 1:1 to 2:1
• Working time: 2-5 min at room temperature (230C)
• Setting time: 6-9 min at 370C
• powder should be rapidly incorporated into
the liquid in large quantities
• working time extended by:
by lowering the temperature of the
mixing slab
30
Zinc Polycarboxylate Cement contd..
Manipulation
• Cements used while it has glossy
surface apperence
Glossy apperence
Sufficient no. of free
carboxylic acid groups
on the surface of the
mixture
Dull looking mixture
Insufficient no. of
unreacted carbioxylic
acid groups are
available to bond to
the calcium in the
tooth surface.
31
Zinc Polycarboxylate Cement contd..
Removal of excess cements
• Excess cements may extrude beyond the
margins of orthodontic bands
• Should not be removed while the cement is
in rubbery stage
• Danger that cement may be pulled out from
beneath the margin leaving void
• Excess cements removed when the
cements become hard.32
Zinc Polycarboxylate Cement contd..
APPLICATIONS
• Luting permanent alloy restorations
• As a bases.
• In orthodontics for cementation of bands.
33
Disadvantage of Zinc phosphate/Zinc
polycarboxylate as a banding cement
• Extensive chair time.
• Frequent screening for caries or
decalcification under tooth structure
• Chemical and mechanical irritation of the
gingiva
• The requirement of additional
arch space to accommodate
placement
34
Glass ionomer Cement
• Developed by Wilson and Kent in the
early 1972.
35
Glass ionomer Cement
• Material was based on reaction between
silicate glass powder & polyacrylic acid.
• Bond chemically to tooth structure &
release fluoride for relatively long period.
36
Glass ionomer Cement contd..
Used in a wide range of clinical
applications, such as:
• Restorations
• Pit and fissure sealants
• Cavity liners
• Luting agents for inlays and crowns.
• In orthodontics for band cementation.
37
Glass ionomer Cement contd..
• Recommended as an alternative to
adhesive resins in orthodontics
• Advantage over adhesive resins:
Avoid the enamel etching
procedure
Elimination of the mineral loss that
occurs during debonding38
Glass ionomer Cement contd..
Composition
Powder Liquid
• Polyacrylic acid in
the form of a
copolymer
• Tartaric Acid
• Water
• Calcium
fluoroaluminosilicat
e glass particles.
39
Glass ionomer Cement contd..
• Calcium fluoroaluminosilicate glass particles.
40
Glass ionomer Cement contd..
41
Glass ionomer Cement contd..
Polyacrylic acid in the
form of copolymer with
itaconic, maleic, or
tricarboxylic acids
• Increase the reactivity of liquid
• Decrease viscosity of liquid
• Reduce gelation
Tartaric Acid• Improves handaling
characteristics
• Increases working time
• Shortens setting time
Water Hydrates the reaction products
42
Glass ionomer Cement contd..
Chemistry of Setting
• When the powder &
liquid are mixed,
surface of glass
particles are
attacked by acid.
• Ca, Al, sodium, &
fluoride ions are
leached into
aqueous medium.
43
Glass ionomer Cement contd..
Chemistry of Setting
• Calcium poly salts are formed first,
then followed by aluminum poly salts
which cross-link with poly anion chain.
• Set cement consist of unreacted
powder particle surrounded by silica
gel in amorphous matrix of hydrated
calcium & aluminum poly salts.44
Glass ionomer Cement contd..
Chemistry of Setting
• Water plays an important role in
structure of cement.
• Water contamination prone to the cracking & crazing, due to
drying of loosely bound water .
• cements must be protected by
application of varnish 45
Glass ionomer Cement contd..
Adhesion with tooth structure
Bonds chemically to the tooth structure
Reaction occur between carboxyl group of poly acid & calcium of hydroxyl apatite.
Bonding with enamel is higher than that of dentin due to greater inorganic content. 46
Glass ionomer Cement contd..
Barriers to adhesion
smear layer not removed
contamination (blood, saliva, too much
water)
setting reaction too far advanced before
application
47
Glass ionomer Cement contd..
Anticariogenic properties
• Fluoride is released at the time of mixing
& lies with in matrix.
• Fluoride can be released out without
affecting the physical properties of
cement.
• Fluoride release continuous for a long
period.
• Initial release is high, declines after 3
48
Glass ionomer Cement contd..
49
Glass ionomer Cement contd..
Luting GIC
Has extended working times (3 to 5
minutes)
Relatively short setting times (5 to 9
minutes),
Rheological properties enable the
formation
of a film ranging from 25 35 µm in
thickness.
50
Glass ionomer Cement contd..
Luting GIC
Have the lowest strength among the
different types of glass-ionomer cements.
Compressive strength of the luting glass
ionomer cements ranges between 90 and
140 MPa
51
Glass ionomer Cement contd..
Resin modified glass ionomer cement
Powder consist of fluroalumino silicate glass particles & initiator for light curing.
Liquid component consist of water & poly acrylic acid with methacrylate & hydroxyl ethyl methacrylate monomer.
provide higher bond strength than the
conventional glass-ionomer cements and a
decreased probability for bond failure. 52
Glass ionomer Cement contd..
Glass ionomer cements and light cured
glass ionomer cements are routinely used
in orthodontics for cementing bands.
Preteatment with polyacrylic acid
facilitates chemical bond between glass
ionomer and enamel- should be
performrd.
53
54
Glass ionomer Cement contd..
In vivo bonding of orthodontic brackets with glass ionomercement Axel Voss, Priv.-Doz. Dr. med. dent.; Reinhard Hiekel, Prof. Dr. med. dent.;Stefan Mölkner, Dr. med. dent.; The Angle Orthodontist Vol. 63 No. 2
The adhesion of orthodontic bracket bases was
examined in vivo 24 to 32 hours after bonding
with glass ionomer cement (GIC). In contrast to
bonding with composite resin, with GIC there is
no need to etch the enamel surface of the tooth.
Conventional metal brackets with mesh pad,
bonded with GIC, showed an average shear
bond strength of 3.6 ± 1.1 MPa, approximately
one-fourth the bond strength of composite resin
55
Resin Cements
Based on the methyl methacrylate.
High esthetics and high bond strengths.
Widely used for the cementation of orthodontic
brackets and resin bonded restorations.
56
Resin Cements contd..
Composition
Resin matrix monomer initiator inhibitors pigments
Inorganic filler glass quartz colloidal silica
Coupling Agent 57
Resin Cements contd..
Monomer
Binds filler particles together
Provides “workability”
Typical monomers Bisphenol A glycidyl methacrylate
(Bis-GMA) Urethane dimethacrylate (UEDMA) Triethylene glycol dimethacrylate
(TEGMA) 58
Resin Cements contd..
Bonding agent
Unfilled resins absence of filler particles Lower viscosity and thus superior
diffusion into the enamel rods Improved interfacial adaptation
59
Resins contd..
Classification of Orthodontic Adhesive
Systems
1. Chemically activated
2. Light-cured (also termed photocured)
3. Dual-cured (chemically activated and light-
cured)
4. Thermocured
60
Resins contd..
Chemically Activated Orthodontic
Adhesive Systems
Initiator: benzoyl peroxide
Activator: a tertiary aromatic amine such as
dimethyl-p toluidine or dihydroxyethyl-p-
toluidine
61
Resins contd..
Two-Paste Adhesive Systems
Used in earlier days.
Mixing of paste and liquid components.
May create surface porosity and air
voids in the bulk material
Gradually eliminated from very active
orthodontic practices.
62
Resins contd..
One phase adhesive system
Application of liquid component on
enamel and bracket base
No mixing is involved
May not be recommended in
applications where the adhesive
thickness is increased, as in bonding
molar tubes.
63
Resins contd..
Light cured Orthodontic Adhesive Systems
Exposure to light curing source initiate
polymerization
Rapid setting reaction
Reduces time available for atmospheric
oxygen to diffuse and deactivate the free
radicals (oxygen inhibition process)
superior mechanical properties
64
Resins contd..
Light cured Orthodontic Adhesive Systems
Advantages
• Permits increased working time for
optimal bracket placement.
• Ideal for educational purposes.
Disadvantages
• Time-consuming process.
• Increased chair time65
Resins contd..
Dual cured Orthodontic Adhesive Systems
Activation of polymerization → visible light
Polymerization in the bulk material →
chemical curing process.
Improved surface and bulk material
properties
Clinical application process for this type of
adhesive is prolonged because both mixing
and photocuring are required.66
Resins contd..
Thermocure Systems
For indirect orthodontic bonding and
restorations.
Increased polymerization rates
Superior properties
Use is currently limited -
increased temperature required for
polymerization
Necessity for adapting an indirect bonding
setup
67
Resins contd..
Moisture-Active
Adhesives
can perform in the
presence of moisture
based on the hydrophilic
attraction of its
constituents.
main reactive
component of this
product is a
68
Resins contd..
Moisture-Active Adhesives
Suitable for difficult moisture control
situation
Second molar bonding
Risk of blood contamination on half of
erupted teeth
On impacted canines.
69
Resins contd..
Adhesive Precoated (APC)
Brackets
These are the brackets
coated with adhesives.
increased bonding efficiency
application of the APC
approach to clinical conditions
may have merit and should be
investigated further.
70
Bonding to nonconventional surface
Bonding to porcelain
Deglaze the bracket base
area by sandblasting with
aluminium oxide for 2
minutes
Etching with 9.6%
hydrofluoric acid in a gel
form applied for 2 minutes.71
Bonding to nonconventional surface contd..
Bonding to Amalgam
Sandblasting with aluminium oxide for 3
seconds
Etching with 37% phosphoric acid for 15
seconds
72
Bonding to nonconventional surface contd..
Bonding to Gold
No excellent bonding.
New technologies includes sandblasting,
electrolytic tin plating, plating with
gallium tin solution
73
Bonding to nonconventional surface contd..
Bonding to Composite Restoration
less unreacted methacrylate groups remain
on the surface for cross-linking with the
bonding resin.
the exposed filler particles are freed
(“plucked out”) from the silane coupling
agent.
Uppermost resin composite layer removed
with a diamond or carbide bur.
Then the surface is acid-etched with 37%
74
Evaluation of antimicrobial activity of orthodontic adhesive associated with chlorhexidine-thymol varnish in bracket bonding Carolina Freire de Carvalho Calabrich, Marcelo de Castellucci e Barbosa, Maria Regina Lorenzetti Simionato, Rogério Frederico Alves Ferreira; (Dental Press J Orthod 2010 July-Aug;15(4):62-8)
The association of chlorhexidine -thymol
varnish with an adhesive system used in
orthodontics proved to be advantageous
due to its antimicrobial activity75
Mutans streptococci and incipient caries adjacent glass ionomer cement or resin-based composite in orthodontics T. Ortendahl, B. Thilander, and M. Svanberg Goteborg and Viixj6, Sweden (American Journal of Orthodontics and Dentofacial Orthopedics September 1997 )
This suggests that in patients who,
before treatment, have relatively high
salivary levels of mutans streptococci and
especially in those who harbor S.
sobrinus, the use of GIC for bonding
may prevent incipient caries formation
during orthodontic treatment.
76
Summary
It is important to know the properties of
the banding and bonding cements as it
is widely used in orthodontics.
Proper manipulation and proper handling
of the material gives the best result.
77
References
Tancan Uysal, DDSa; Zafer Sari, DDS, PhDb; Abdullah Demir, DDS, Msa (Angle Orthodontist, Vol74, No 5, 2004)
Immediate versus Delayed Force Application after Orthodontic Bonding; An In Vitro Study
M. Basafa 1, F. Farzanegan 2 (Journal of Dentistry, Tehran University of Medical Sciences, Tehran, Iran (2006; Vol:3, No.1)
The Role of Zinc Phosphate Cement in Enamel Surface Changes on Banded Teeth; Per Johan Wisth; Angle Orthodontics Vol: 40, No: 4
78
References
Phillips’ science of dental materials, 11th ed, Anusavice
Orthodontic Materials, Scientific and Clinical Aspects; William A. Bra ntley, Theodore Eliades
Dental material and its selection ,3rd ed. William j O’ brien
Restorative dental materials, 11th ed. Robert G Craig and John M Powers
Are the Flowable Composites Suitable for Orthodontic Bracket Bonding?
79
Thank
you 80