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


Cements are used for :

In orthodontics,

• Luting of appliances

• Luting of molar bands

• Bonding of Brackets on tooth surface

5


Properties:

• Adequate working and setting times

• High tensile, compressive and shear

strengths

• Resistance to dissolution

• Clinically acceptable bond strength

6


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


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


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


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


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


• 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


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


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


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


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


• Developed by Wilson and Kent in the

early 1972.

35


• 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


• 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


Composition

Powder Liquid

• Polyacrylic acid in

the form of a

copolymer

• Tartaric Acid

• Water

• Calcium

fluoroaluminosilicat

e glass particles.

39


• Calcium fluoroaluminosilicate glass particles.

40


41


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


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



• 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



• 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


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


Barriers to adhesion

smear layer not removed

contamination (blood, saliva, too much

water)

setting reaction too far advanced before

application

47


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


49


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


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


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 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


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


Monomer

Binds filler particles together

Provides “workability”

Typical monomers Bisphenol A glycidyl methacrylate

(Bis-GMA) Urethane dimethacrylate (UEDMA) Triethylene glycol dimethacrylate

(TEGMA) 58


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 Gold

No excellent bonding.

New technologies includes sandblasting,

electrolytic tin plating, plating with

gallium tin solution

73


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

banding and bonding cements

Health & Medicine

phosphate zinc phosphate

zinc phosphate cement

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glass ionomer cements

cement affe

mixed cement mass

magne sium oxide

bonding cementsdr