Dental Cements: Luting Agents Flashcards
(35 cards)
Why use \_\_\_\_\_\_? Caries Fractures Misalignment Prolong the life of the pulp in the war against oral bacteria- using protective coatings Varnish Base Liner Pits & Fissure sealants
Dental Cements
Substance that hardens to act as a base,
liner, restorative material or luting agent
(adhesive) to bind devices and prostheses
to tooth structure or to each other
Dental cement
What do we want a Dental
Cement to be?
① Biocompatible- long-term ② Non-corrosive & Inert ③ Immune to acid attack • insoluble ④ Dimensionally stable- • no cracking of tooth or device by expansion • no leaking because of shrinkage 5) Sets during the dental procedure 6) Low surface tension; Handles & places easily 7) Adapts & adheres to anatomy 8) Insensitive to moisture during procedure 9) Anti-microbial/ F- release 10) Radiopaque- able to see it on a radiograph 11) “Cost-effective” HIGH values needed for: 13) Cyclic fatigue 14) Thermal cycling 15) STRENGTH a. Tensile b. Compressive c. Flexural Strength d. Shear
Applications of _______
- Luting cements
a. Permanent & provisional indirect restorations
b. Orthodontic brackets
c. Post and cores - Restorative materials
a. Permanent & provisional direct restorations - Cavity liners & Bases
a. Pulp protection - Multiple applications
a. No one cement can fulfill all requirements
Dental cements
Viscous material that fills the
microscopic space between the abutment-
prosthesis interface; upon setting, it forms a
solid that seals the space and retains the
prosthesis.
Luting cement/agent
What are the 8 ideal properties of a permanent luting agent?
- *Low film thickness (25 m)
- *Adequate strength (minimum 70 MPa)
- *Low solubility (0.2% max. @ 24h)
- *Reasonable setting time (2.5-8.0 min)
- Adequate working time
- Biocompatible, does not irritate pulp
- Cariostatic
- Adhesion to tooth structure and restorative materials
_____ bonding
very weak interaction, 2bonds
Van der Waals forces, hydrogen bonds
Physical bonding
_____ bonding
: strongest bond, 1bonds
Limited occurrence, dissimilar materials
Example: composite bond to adhesive bond agent
Chemical bonding
\_\_\_\_\_ bonding :interlock undercuts, surface irregularities Micromechanical retention Examples: Luting agent/tooth/crown Adhesive bond agent/tooth
Mechanical bonding
Cement locking into microscopic irregularities in prepared
tooth surface and the internal surface of the crown
Non-resin cements
Very low bond strength, 1-5 MPa
Luting cement:
Enamel: resin tags into etched enamel
Dentin: hybrid layer
Interdiffusion or micromechanical interlocking of resin with demineralized collagen of interbulular dentin
20-30 MPa bond strength
Adhesive bond agent/tooth:
Is the liquid or powder the acidic component of cement?
Liquid
Is the liquid or powder the basic component of cement?
Powder
_____ cement:
Indications
Temporary / intermediate
cementation
Zinc oxide eugenol
- Composition:
a. Powder: Zn Oxide Liquid: Eugenol
b. Modifications:
1) Polymer-reinforced: IRM
2) EBA (ethoxy-benzoic acid), Alumina - Low strength (MPa):
- Uses: temporary or provisional cement
and restorations
a. Eugenol acts as sedative, obtundent - ZOE unmodified, TempBond
a. Temporary cement - ZOE polymer-reinforced
a. IRM: Intermediate Restorative Material
1) Temporary cement: Retention or time
2) Provisional/intermediate restoration - Not use prior to resin-based permanent cement,
ZOE
+ Obtundent –+ Slow setting – Excess eugenol is irritant Cytotoxic Potential allergen – Shrinkage – Low strength – Solubility
ZOE
Temporary cement Eugenol replaced with other oils Used prior to permanent resin-based cement TempBond NE Slow set Low retention
ZnO non eugenol
\_\_\_\_ cement: Low strength: Compressive, 55-67 MPa (ADA spec 96 minimum = 70 MPa) Tensile, 6-8 Mpa Biological considerations Initial pH ~3, similar or lower than ZnPO4 Minimal pulp reaction, large molecule not enter tubules Dentin bond strength: ~2 MPa Chelation interaction: cement carboxylate (COO-) and Ca+ on tooth surface Physical bond: interaction between – and + charges 5. Advantages: Low pulpal irritation Adhesion to tooth structure More with enamel than dentin, Why? 6. Disadvantages: Low strength More viscoelastic Prosthesis dislodgement over time 7. Marketed as a temporary cement UltraTemp Can be used prior to resin cement No polymerization inhibition, Why? UltraTemp REZ: resin-based
Zinc Phosphate cement
\_\_\_\_\_\_\_\_\_ cement Oldest, still in use “Gold Standard” for new cements Easy to manipulate Working time 3-6 min Setting time < 14 min Indications: Luting (non-adhesive cementation) fixed prosthodontics
Zinc Phosphate cement
____ cement:
Introduced 1878
Micromechanical bond to preparation surface and crown
internal surface micro-irregularities
No chelation interaction
Bond strength: 0.5-1.5 MPa
Preparation retention and resistanceform critical
No longer a major luting agent
Possible current use: cement-retained implant crowns
Radiographic visibility, easier removal with less damage to Ti
implant surface
Zinc phosphate
\_\_\_\_\_\_\_ cement Powder >75% zinc oxide <13% magnesium oxide Radiopaque fillers Liquid= aqueous solution of 38 – 59% H3PO4 2-3% Al phosphate <9% Zn phosphate Reaction Products Amorphous Zn3(PO4)2·4H2O matrix Zinc aluminophosphate matrix Residual ZnO particles
EXOTHERMIC Use chilled glass slab Mix over large area of slab Mix in increments Create stringy consistency Remove excess after set
Zinc Phosphate
\_\_\_\_\_\_\_\_\_ Cement +Thermally protective –Acidic –Exothermic reaction – Some solubility w/ acids
Zn Phosphate
______ cement
Composition:
Powder: Fluoroaluminosilicate glass (FAS)
Liquid: Polycarboxylic acid/H2O
Strength:
Compressive: 90-140 MPa
Tensile: 6-7 Mpa
Fluoride release (from what component?)
Bond strength: 3-5 MPa
Chelation, cement carboxyl and Ca+ in apatite
Glass Ionomer
Post-cementation hypersensitivity Early protection (varnish) to prevent hydration and dehydration of initially set cement
Glass ionomer
