Cements 2, Cements for Restoration and Bases

- It was the first translucent filling material with anticariogenic properties.

SILICATE CEMENT

CEMENTS FOR RESTORATION

1. SILICATE CEMENT

2. GLASS IONOMER CEMENTS

3. METAL MODIFIED GLASS IONOMER

4.RESIN MODIFIED GLASS IONOMER

5.COMPOMERS

CEMENTS FOR BASES

1. ZINC PHOSPHATE CEMENT (ZnPO4)

2. ZINC POLYCARBOXYLATE CEMENT

3. GLASS IONOMER CEMENTS

4. ZINC OXIDE EUGENOL

5. ZINC SILICOPHOSPHATE CEMENT

Powder Composition of Silicate Cement

○ Acid-soluble glass of silica (Sio,)

○ Alumina (Al2°3)

○ Fluoride ( Na/f, CaF,, NagAIF6) lowers fusing temperature

○ Calcium salts Ca(H,PO)2H20 and CaO.

Liquid Composition of Silicate Cement

an aqueous solution of phosphoric acid with buffer salts.

Properties of Silicate Cement

1. Brittle

2. Low pH - less than 3 at the time of insertion & remains below 7 even after 1 month

3. Severe pulpal irritant -requires greater need for pulp protection

4. Contains fluoride which is released throughout the life of the restoration

3 Cardinal rules when using GIC as restorative material

1. Condition the tooth surface

2. Proper manipulation of cement

3. Protect cement during setting

Surface preparation of GIC (conditioning)

1. After tooth prep, apply 10% polyacrylic acid solution to the surface for 10-15 sec, to remove the smear layer

2. Rinse with water for 30 sec

3. Eroded areas with no prep, clean dentin and cementum with pumice slurry

4. Swab the area with 10% polyacrylic acid for 5 sec.

5. Dry the area but do not desiccate. Any contamination will impair the bonding.

Manipulation of GIC

1. The mixed cement is immediately packed by means of a plastic instrument or injected into the cavity. Dull appearance denotes that the cement is beginning to set and will produce inadequate adhesion to the tooth Pre-shaped matrix is applied for maximum contour and ensures the best possible surface integrity.

2. The matrix also protects the setting cement from losing or gaining water during the initial set.

3. Leave the matrix for 5 - 7 minutes until the cement has set

4. On removal of matrix, the cement must immediately be protected while excess is trimmed from the margins using hand instruments rather than rotary tools, to prevent ditching. 5. A special varnish, single-component, unfilled light-cured resin bonding agent may be used. 6. Further finishing should be delayed for at least 24 hours. 7. Before dismissing the patient, the restoration should be coated again with protective agents to prevent crazed, chalky surfaces.

It has metal fillers to improve strength, fracture toughness and resistance to wear

METAL MODIFIED GLASS IONOMER

- Fluoride release of Metal GI's compared to type lI GIC

● Less fluoride is released from cermeT

● Admix releases more fluoride than type ll but decreases over time

Metal modified GI's are of limited in use as alternative to _______ and ________

amalgam and composite

METAL MODIFIED GLASS IONOMER

- Metallic fillers do not improve mechanical properties, including __________ ________

- Also for __________ in cast crown restoration

Metallic fillers do not improve mechanical properties, including fracture toughness

- Also for core build-up in cast crown restoration

Types of Metal Modified Glass Ionomer

● Silver alloy admix: spherical amalgam alloy and type lI GI

● Cermet: bonded silver particles fused to glass powder of GI

AMALGAM

- It lasts for __-__ years

- Most _________ restorative material

- Downside: _____________ (Poisonous)

- History: ______

AMALGAM

-It lasts for 20-50 years

- Most reliable restorative material

- Downside: Mercury content (Poisonous)

- History: 1970

Resin Modified GIC's is also termed _________GICs, __________ GICs (light cured and acid base reaction),________ GICs (dual cure+ chemical one), _________ , _________, __________

Resin Modified GIC's is also termed:

-Light cured GICs

-Dual cure GICs (light cured and acid base reaction)

-Tri-cure GICs (dual cure+chemical one)

-Resin ionomers

-Compomers

-Hybrid ionomers

○ Conventional GCs set by __________?

Pure acid base reaction

What was the property of resin modified GI's that is not found in conventional GIC

Resin

○ Conventional sets by acid base reaction. Resin modified GI's sets by ___________ and __________

acid base as well as light cure

Powder composition of resin modified GI's

Ion leachable glass and initiator for light or chemical curing or both

Liquid composition of resin modified GI's

Water, polyacrylic acid with some carboxylic groups modified with methacrylate and hydroxyethyl methacrylate monomers (responsible for polymerization)

Properties of of resin modified GI's

1. Reduced translucency

2. Greater amount of plastic deformation

3. Bonding mechanism similar to conventional GIC

4. Have higher bind strength to composite resin

5. Greater degree of shrinkage on setting and

increase microleakage

6. Reduced water sensitivity but still susceptible to

dehydration

7. Biocompatibility is comparable to conventional

GICs but pulp still need to be protected by

calcium hydroxide in very deep prep

- Polyacid-modified composite made by incorporating glass particles of GIC In water-trae polyacid liquid monomer with appropriate initiator.

COMPOMERS

Compomers has ______________ of GI and the ________ of composites

-fluoride releasing capacity of GI

-durability of composites

Compomers is usually supplied as a one-paste, light-cured material for restorative or powder liquid system for luting application

-One-paste

-Light-cured material for restorative

-Powder liquid system for luting

- Compomers is used in low stress bearing areas such as class Ill and V prepared cavity; etching and bonding procedures must be performed

As a Restorative Material

-Compomers is used ___________ indicated for cementing prostheses with metallic substrate. After seating, margins should be light-cured immediately to stabilize the prosthesis

As a Luting cement

Functions of Cement for bases

Functions:

1. Thicker protective layers under restorations

2. Protects the pulp from thermal shock and

chemical irritation

3. Serves to replace or substitute for dentin

destroyed by caries

4. Provides therapeutic benefits to the pulp

Factors to be considered in selection of Bases

1. Design of the cavity

2. Type of permanent restorative material to be used 3. Proximity of the preparation to the pulp

Base for Amalgam

-Calcium Hydroxide (CaOH)

-Zinc Oxide Eugenol(ZOE)

-Cavity varnish

Base for Direct Gold Filling

-Zinc Phosphate Cement (ZnPO4) over Varnish

-Polycarboxylates

-Glass ionomer

Bases for Resin

-Calcium Hydroxide(CAOH)

-Glass Ionomer Cements(GIC's)

- The oldest and strongest base material

- Used primarily for final cementation

- Thermal conductivity is similar to tooth

ZINC PHOSPHATE CEMENT (ZnPO4)

- The alkaline powder is dissolved by the __________

- Acidic; needs a layer of ________ before its application To afford effective protection, a __mm thickness is required

acidic liquid

varnish

5 mm thickness

Mixing time and Setting time of Zinc Phosphate cement(ZnPO4)

Mixing time: 60-120 sec

Setting time: 5-9 min

Powder composition of Zinc Phosphate Cement

Powder Composition

○ 75% Zinc oxide

○ 13% Magnesium oxide

Liquid composition of Zink Phosphate Cement

Liquid Composition

○ 38-59% Phosphoric acid

○ 30-55% Water

○ 2-3% Aluminum phosphate

Physical and Mechanical Properties of Zink phosphate Cement(ZnPO4)

1. High compressive strength - 104 Mpa

2. Low tensile strength

3. Relatively strong and stiff

4. Low solubility in water

5. Does not adhere to tooth structure or any

restorative materials

6. Mechanical interlocking is the means of

retention

FACTORS INFLUENCING WORKING AND SETTING TIME OF ZnPO4

1. Powder:Liquid ratio

2. Rate of powder incorporation

3. Spatulation Time

4. Temperature of the mixing slab

Powder:Liquid ratio of ZnPO4

↑ PL ratio = ____________

↓ PL ratio = ____________

Powder:Liquid ratio

↑ PL ratio - lengthens setting time

↓ PL ratio - decreases setting time

Slow incorporation of powder to liquid in ZnPO4 will Increase __________ _________

- It also reduces the amount of __________ _________ by the set cement

Working time and Setting time

amount of heat generated

Prolonged spatulation of ZnPO4 will increase ________ and _________

Prolonged spatulation of ZnPO4 will increase setting and working time

Most effective method of controlling working time and setting time of ZnPo4 cement.

- Cooling the slab markedly retards ____________ reaction- ↑ WT, ST

-Temperature of the mixing slab

- Cooling the slab markedly retards chemical reaction- ↑ WT, ST

- The first cement to exhibit chemical bonding to the tooth

ZINC POLYCARBOXYLATE CEMENT

- Higher viscosity than ZnPO4

ZINC POLYCARBOXYLATE CEMENT

Compressive strength of Zinc Polycarboxylate cement is (approx. ___ Mpa), is less than __________ but similar to reinforced ZnOE

55 Mpa

less than ZnPO4 but similar to reinforced ZnOE

Zinc Polycarboxylate cement is more elastic than

ZnPO4

-Produces minimal irritation to the pulp

- Excellent biocompatibility and lacks post operative sensitivity

ZINC POLYCARBOXYLATE CEMENT

- Cannot be used for restorative purposes because the cement is opaque

- If you use this as base, lesser reaction or lesser post operative sensitivity

ZINC POLYCARBOXYLATE CEMENT

POWDER COMPOSITION OF ZINC POLYCARBOXYLATE CEMENT

● Powder:

○ Zinc oxide

○ Magnesium oxide

○ Tin oxide

○ Bismuth oxide, and/or alumina

○ Some stannous fluoride- to adjust the

setting time, increase the strength and

enhance manipulative properties

LIQUID COMPOSITION OF ZINC POLYCARBOXYLATE CEMENT

○ Aqueous solution of copolymer of acrylic acid with other carboxylic acids such as itaconic acid

MANIPULATION OF ZINC POLYCARBOXYLATE CEMENT

Mixing time: 30 sec

Working time: 2.5 min

Setting time: 6-9 min

Zinc polycarboxylate cement should be mixed on a_______ to _________ the working time.

Should be mixed on a cool glass slab to increase the working time.

Zinc polycarboxylate cement

The __________ of can be refrigerated because it retards the reaction, but the _______ component is viscous and should not be refrigerated.

Powder-can be refrigerated

Liquid-Should not be refrigerated

Zinc polycarboxylate cement

- The liquid should be dispensed just before use because the water in the liquid _____________ which raises its viscosity.

evaporates quickly

Zinc polycarboxylate cement

- The powder should be ________ incorporated into the liquid

Rapidly

Zinc polycarboxylate cement

- Rapid spatulation _______ the viscosity

- Longer mixing time _______the viscositi

- Rapid spatulation reduces the viscosity

- Longer mixing time increases the viscosit

The pH of the cement liquid of Zinc polycarboxylate cement is initially slightly less acidic than that of ZnPO4 but still very low (____).

1.7 pH of cement liquid of Zinc polycarboxylate cement

-ZINC POLYCARBOXYLATE CEMENT is unable to bond to ______

Metal

Zinc polycarboxylate cement

Conditioning of prep with ___ % _________ or ___________ applied for __-__ sec. is important

Conditioning of prep with 10% polyacrylic acid or maleic acid solution applied for 10-15 sec. is important

L:P is 1:1.5 correct consistency of mix is ________ in appearance; Must be used before it loses its gloss.

glossy in appearance

What type of GIC is used as a Base or Liner

- Type Ill as base or liner

- GIC's __________ bonds to the tooth

- Chemically bonds to the tooth

GLASS IONOMER CEMENTS

- _____ for deep cavity is needed

- (Calcium Hydroxide) CaOH for deep cavity is needed

- Has anticariogenic properties

- High early solubility

- Complete setting is 24 hours

GLASS IONOMER CEMENTS

ZOE Type III is used as a ______?

- Type III as a cement base

- Has sedative effect on the pulp

ZINC OXIDE EUGENOL

- in ZOE _____ and _____ accelerate setting reaction

Water and heat accelerate setting reaction

- ZOE Provides ______ thermal insulation

- Provides little thermal insulation

Characteristics of ZOE as a Base

- Provides little thermal insulation

- Retards penetration of acids

- Inhibits polymerization of resins

ZOE is difficult to remove you must use ________?

- use oil of orange

in ZOE as a base a thickness of __mm is needed for strength to support restoration

2mm

ZINC SILICOPHOSPHATE CEMENT MIXING TIME

1 minute

PHYSICAL AND MECHANICAL PROPERTIES OF ZINC SILICOPHOSPHATE CEMENT

1. Does not bond to tooth structure but only forms

mechanical interlocking

2. Used for cementation of precision casting

3. Stiff; brittle

4. Initial solubility to water is high

5. Contains fluoride, has a potential to inhibit

secondary caries

6. Needs pulp protection because it is acidic

7. Translucent - good for all-ceramic restoration

as luting agent

POWDER COMPOSITION OF ZINC SILICOPHOSPHATE CEMENT

● Powder:

○ Silicate glass

○ Zinc oxide powder

LIQUID COMPOSITION OF ZINC SILICOPHOSPHATE CEMENT

● Liquid:

○ Phosphoric acid

○ Water

○ Aluminum