Dental Cements Flashcards
(52 cards)
Uses of dental cements
1- luting or cementing agent
2.Cavity liners (materials that placed as thin coating layer to
provide a barrier against chemical irritation), and bases to
protect the pulp from thermal, chemical and irritation.
Requirements of Dental Cements
- Non-toxic and non-irritant + obtudent
- Antibacterial effect.
- Adhesion to the tooth
4.Optical properties - Protect the pulp
- Insoluble in saliva
7- used as filling materials
Classification Of Dental Cements
Are generally classified according to their chemical ingredient
- Cements based on zinc oxide.
- Cements based on aluimino-silicate glasses.
- Resin cements.
- Calcium hydroxide (liner and pulp capping)
- Cavity varnishes.
Zinc Oxide-Eugenol Cement characteristics
PH approximately 7 , also they are characterized by their sedative (obtundent)
Zinc Oxide-Eugenol Cement types
- Unmodified zinc oxide-eugenol cement.
- Resin-modified zinc oxide-eugenol cement.
- Ortho-ethoxy benzoic acid alumina-modified zinc oxide-
eugenol (EBA- ZOE).
for patients sensitive to eugenol use
carboxylic acid
Applications of Zinc Oxide-Eugenol
Cements
1- Temporary cementation of cast restorations.
2-Temporary filling materials.
3- Cavity liner in deep cavities preparation.
4- Root canal sealer.
5- Periodontal and surgical dressing.
6- Gingival tissue pack.
Zinc oxide-eugenol cement is contra-indicated to be used under
composite resins because
it interferes with their polymerization and causes discoloration of the composites
Main disadvantage of Unmodified Zinc Oxide-Eugenol
Low strength, and high solubility
Biocompatibility of Unmodified Zinc Oxide-Eugenol
has a pH of 7 and has little or no effect on the pulp
when placed in deep cavities. The presence of free-eugenol has an
obtundent effect on the pulp and reduces pain. It is irritant when in
direct contact with the pulp .
Resin-modified zinc oxide-eugenol applications
- Cementing (luting) agents.
- Cavity liner and base materials.
3.Temporary filling materia
Ethoxy Benzoic acid Alumina-modified Cement
(EBA- ZOE) applications
- Permanent cementation of crown and bridges
- Temporary filling
- Base and lining materials.
(EBA- ZOE) solubility
Similar to that of the polymer-reinforced zinc oxide-eugenol.
*The resistance to solubility is greater than that of the zinc
phosphate cements.
Zinc phosphate cements composition
Powder :
(Magnesium oxide is added to maintain the white color)
silica and alumina (improve mechanical properties).
Liquid:
Is aqueous solution of phosphoric acid buffered by adding
metallic salts such as aluminium 2%-3% phosphate and zinc phosphate
(buffering agents)
Zinc phosphate cements Setting reaction is
exothermic
Zinc phosphate cements manipulation
Setting time…. , time increased by
3-6min
• Reducing P/L ratio
• Prolonging the spatulation of last increment.
• Cooling the glass slab
Zinc phosphate cements should be incorporated into the liquid slowly on a
cool slab
In Zinc phosphate cement’s manipulation, Film thickness depends on
A. Particle size of the powder
B. P/L ratio
C. Viscosity of the cement: the lower initial viscosity of the cement the
thinner is the film
D. Pressure applied
• Film thickness of zinc phosphate cement is 25µ
Zinc phosphate cement Biological properties
Irritant to pulp when used as cavity lining, PH of the freshly
mixed cements 1.3-3.6, at the end of one hour PH reach 6
a sub-lining should be used under zinc phosphate
cements.
Zinc phosphate cement Thermal and electrical conductivity
Has thermal insulating properties when used as a deep cavities
under metallic restoration to protect pulp .
Zinc phosphate cement advantages and disadvantages
Advantage
1. It is easy to mix
2. It has a sharp well-defined set.
3. It has a sufficiently high compressive strength to resist the forces of amalgam
condensation.
Disadvantage
1. Acidic – possible pulpal irritation
2. Lack of antibacterial action
3. Brittle (Low tensile strength)
4. Lack of adhesion
5. Provides only mechanical bond
6. Exothermic during set
7. High solubility (in oral fluids)
8. Low hardness
Zinc phosphate cement applications
• Permanent cementation.
• Temporary filing.
• Base.
Zinc poly-carboxylate cements applications
• Cementation of cast alloys, and orthodontic bands.
• Cavity liner or base material
• Temporary filling materials.
Zinc poly-carboxylate cements composition
Powder:
• The powder contains mainly zinc oxide (ZnO) with some magnesium oxide , may also contain small quantities of stannous fluoride.
Liquid:
• The liquid is approximately 30-40% aqueous solution of poly acrylic acid with other organic acids such as itaconic acid to prevent gelation upon storage and tartaric acid to control the setting reaction. Sodium hydroxide is added to control the pH and control the viscosity of the liquid.