Dental cement dental material
-
Upload
dr-faisal-al-qahtani -
Category
Education
-
view
2.825 -
download
12
description
Transcript of Dental cement dental material
DENTAL CEMENTS
2014
CementsSubstances used to glue 2 solid objects together
2014
2014
In addition to the gluing function,
Dental Cements own many different applications
2014
3 main Categories
2014
Zinc Oxide
Alumino Silicate Glass
Phosphoric Acid Polyacrylic Acid
Eugenol
ZOE & Ca(OH)2
Zinc Polycarboxylate
Glass IonomerSilicate
Zinc Phosphate
Cements set via Acid-Base Rx
ZINC OXIDE EUGENOL (ZOE) CEMENT
2014
2014
Presentation forms
Powder Liquid
• Zinc oxide• Magnesium oxide• Zinc Acetate- Accelerator
• Eugenol• Olive oils• Acetic acid- Accelerator
Two paste system(Base & Catalyst)
Eugenol-Containing
Eugenol-Free
Single paste – sets in contact with water
2014
How it sets? via acid-base Rx (Chelation)
• ZnO + H2O Zn(OH)2 (1) • Zn(OH)2 + E Zinc Eugenolate (2)
Mixingon either paper pad or glass slab using a stainless steel spatula at high P/L ratio (4 :1)•Thin mix for temp. cementation •Thick mix for temp. filling
Set materialMatrix of zinc eugenolate (chelate) + Dispersed non-reacted Zinc oxide particles
• Presence of water is essential – Saliva could help• Zinc acetate dissolves faster in water zinc hydroxide
2014
Controllin
g the Rx sp
eed (setting time)
1. ↓ Powder p
article siz
e
reaction
2. Temperature
reaction
3. Acce
lerators
reaction
4. P/L ra
tio
re
action
5. M
ixing rate (sp
eed or time)
re
action
2014
1. Biological Characteristics• Bacteriostatic -- kills bacteria of carious cavities• Low thermal diffusivity -- insulate thermal and electrical irritations• Obtundent effect -- reduces the pulpal pain• High sealing ability -- minimize the leakage in temp. restored cavities
Material’s Characteristics (BMIECP)
2014
2. Mechanical Characteristics• Weak cement -- could not withstand either masticatory forces -- could not withstand amalgam’s condensation forces
4. Esthetic Characteristics• Opaque – not used to lute translucent ceramic restorations
3. Interfacial Characteristics• Mechanically-retained -- to both tooth and restorations’ surfaces -- adapt well to cavity walls
2014
5. Chemical Characteristics• Water soluable -- dissolves in oral saliva
• Eluted Eugenol -- changes the color of overlying composite restoratives -- retard the polymerization of overlying composite restoratives -- swallowed E causes gastric troubles
6. Practicability• Easily mixed – no special precautions but – it is better to mix it in thick consistency
2014
Applications
1. Temporary cementation
2
. Temporary filling
3. Cavity
liner
4. In
direct p
ulp capping
5. Endodontic sealer
6. Surgical packs
2014
Modified Materials
2014
CALCIUM HYDROXIDE
2014
Presentation forms
Ca(OH)2 powder
Single paste – methyl cellulose- sets in air
Light-cured Ca(OH)2 paste – resin matrix
Two paste -- the only sets via an acid-base Rx
Base Catalyst
• Calcium hydroxide• Zinc oxide• Zinc Acetate- Accelerator• Liquid vehicle
• di-salicylate, • Radio-opacifers,• Fillers
2014
1. Biological Characteristics --- related to material’s alkalinity (pH= 11-13)• Bacteriostatic -- kills bacteria of carious cavities• Neutralizes the acids produced by the cariogenic bacteria• Help differentiate pulpal stem cells -- reparative dentin stimulator
Material’s Characteristics (BMIECP)
2. Mechanical Characteristics• Weak cement -- could not withstand amalgam’s condensation forces
4. Esthetic Characteristics• Opaque – not used to lute translucent ceramic restorations
3. Interfacial Characteristics• Mechanically-retained -- does not adhere to the tooth structure
5. Chemical Characteristics• Quite soluble -- dissolves in liquids even under leaked restorations
2014
Applications
1. Dire
ct & indire
ct pulp ca
pping 4
. temp. endodontic fi
lling
2. Cavity
liner
5
. Temporary cementation
2. Endodontic s
ealer
6. pulpotomy
2014
ZINC PHOSPHATE CEMENT
2014
Powder Liquid
• Zinc oxide• Magnesium oxide• Other oxides &
fluorides
• Phosphoric acid (H3PO4)• Water (30-40%)• Buffering agents -- Zinc oxide, zinc
hydroxide
Presentation forms
Mixingon thick, cool glass slab using stainless steel spatula powder is added to the liquid in small incrementsMixing over a wide area•Thin mix for cementation •Thick mix for cavity base /temp. filling
2014
How it sets? Through a Fast , exothermic acid-base Rx (Crystallisation)
ZnO + H3PO4 Zn3(Po4)2 + H2O
Set material matrix of zinc phosphate salt+ dispersed non-reacted zinc oxide particles
Controlling the Rx speed (setting time)1. ↓ Powder particle size reaction2. Temperature reaction3. ↓ Buffers reaction4. P/L ratio reaction5. Mixing rate (speed or time) reaction6. Acid concentration reaction
2014
1. Biological Characteristics• Pulp irritant -- fresh mix is highly acidic (pH 1.6-3.6) -- Ca(OH)2 liner is needed in deep cavities -- Thin mix is more irritant than the thick mix -- Set material becomes neutral in 48 hrs• Low thermal diffusivity -- insulate thermal and electrical irritations
Material’s Characteristics (BMIECP)
2. Mechanical Characteritics• Stronger than ZOE and weaker than GI -- withstand amalgam’s condensation forces (cavity bases)-- could withstand masticatory forces ( permanent cementation /temp filling)
3. Interfacial Characteristics• Mechanically-retained -- to both tooth and restorations’ surfaces• Film thickness similar to that of zinc phosphate cement (15μm)
4. Esthetic Characteristics• Opaque – not used to lute translucent ceramic restorations
5. Chemical Characteristics• Water soluble -- dissolves in oral saliva -- thin mix dissolves more than the thick mix
2014
6. Practicability• Material is successfully used for a long time• Needs well-trained operator due to its short S.T.• precautions –
1. Liquid bottle should be tightly closed all the time2. Liquid with cloudy appearance should be discarded3. Shake the powder bottle before dispensing the correct ratio 4. never use powder of other cements (e.g. ZOE…) or of other manufacturer
2014
Applications
1. Final cementation
2.Cavity base
3. Temporary filling
4
. Cementation of orthodontic bands
5. Dentin building-up
2014
POLY-ACARYLIC ACID
in comparison to phosphoric acid•Has lower acidity •Has higher molecular weight --More viscous•Bonds chemically to the inorganic part of tooth structure
2014
ZINC POLYCARBOXYLATE CEMENT
2014
1. Powder Liquid
• Zinc oxide• Magnesium oxide• Flourides
• Poly-acrylic acid (30-40%)• Water
2. Powder in a single bottle
water settable material
Freeze dried acid is blended with the powder
3. Capsules
Presentation forms
2014
MixingOn a glass slab using stainless steel spatulaPAA is viscous and needs more effort during material’s mixing •Thin mix ( P/L ratio 1.5:1) for cementation •Thick mix ( P/L ratio 2.5:1) for cavity base /temp. filling
How it sets? Through a acid-base Rx
ZnO + PAA Zn-polyacarylate + H2O
Set material matrix of zinc polyacrylate salt+ dispersed non-reacted zinc oxide particles
2014
Controllin
g the Rx speed (setting time)
1. ↓ Powder p
article size
reaction
2. Temperature
reaction
3. P/L ratio
reaction
4. Mixing rate (sp
eed or time)
reaction
5. Acid concentra
tion
reaction
2014
1. Biological Characteristics• Pulp irritant -- fresh mix is acidic But less than zinc phosphate cement is -- Ca(OH)2 liner is needed in deep cavities -- Thin mix is more irritant than the thick one -- Set material becomes neutral in 48 hrs• Low thermal diffusivity -- insulate thermal and electrical irritations
Material’s Characteristics (BMIECP)
2. Mechanical Characteristics• Its strength is comparable to that of zinc phosphate cement-- withstand amalgam’s condensation forces (cavity bases)-- could withstand masticatory forces ( permanent cementation /temp filling)
3. Interfacial Characteristics• Chemically adhere -- to the tooth and base metal restorations• Film thickness similar to that of zinc phosphate cement (15μm)
2014
4. Esthetic Characteristics• Opaque – not used to lute translucent ceramic restorations
5. Chemical Characteristics• More soluble in water than zinc phosphate cement -- thin mix dissolves more than the thick mix
6. Practicability• Viscous liquid make the mixing process a little pit difficult• All metallic instruments should be cleaned up while the cement still unset• To achieve better bonding
1. Tooth surface should be cleaned and dried from saliva
2. Mixed cement should be applied to tooth structure as fresh as possible
2014
Applications
1. Final cementation
2.Cavity base
3. Temporary filling
4
. Cementation of orthodontic bands
5. Dentin building-up
2014