Ch.11 cements Flashcards
What are dental cements based on? (Rxns between what)
Basic powderes (ceramic particle) & Acidic liquids
Properties of cements depend on the extent to which the matrix is ____ in the ____ ____
minimized final material
What material is considered the “gold standard” for all other dental cements, despite its inferiority? How is it “inferior”? Does it bond to dentin?
Zinc Phosphate Weaker and more brittle No
In Zinc phosphate, what is the powder and liquid components made of?
Powder: 90% ZO - 10% Mg Liquid: 50% phosphoric acid in water w/ Al zinc salts
What material was developed in an effort to circumvent potential pulpal problems associated with the low pH of Zinc phosphates? What are the two types? Which one accounts for 75% of all cements used?
Polycarboxylate cement (PC)
GI & RMGI
RMGI
What material is used for all ceramic restos? how do they differ from composite material? What are the pros and cons?
Composite cement, have less filler particles thanc omposite
Best lab properties of all the cements, but more complicated clinical procedures and bonding systems
What are compomer cements called? Why? What was added to this type of composite cement?
“universal cements” b/c they promise to work for metal and all ceramic restos fluoride releasing glass filler particles
What are the two uses for dental cements?
Luting agents and bases
As luting agents, what are the important clinical requirements for cements? If cement is being used as a base, what different properties do you want compared to cements used as luting agents?
What influences the film thickness?
1) flow 2) wetting 3) film thickness
you want them to be mechanically stronger and are mixed with the maximum powder content manageable
viscosity of the cement, amount of space for the cement in the resto
How is the flow enhanced? How can you make a thin film?
Lowering the viscosity: - mixed low powder to liquid ratio phase particles of 5 um or less in diameter
Which type of material has the greatest film thickness? Which one has the lowest?
R-ZOE
ZP (zinc phosphate)
Rank all the materials from greatest tenile strength to lowest
COMP/RMGI (both 30-35)
GI (12)
ZP/PC (10)
EBA (7)
R-ZOE (4)
Rank compressive strengths form greatest to weakest
COMP (170-190)
RMGI (148-180)
ZP (zinc phosphate) (160)
GI (120)
PC (polycarboxylate) (70)
EBA (ethoxybenzoic acid) (65)
R-ZOE (48)
High P/L ratio = _____ mechanical strength High P/L = _____ viscosity
increased increased
What are the two goals for cementation?
1) retention 2) sealing
How is sealing compromised? What results?
Fatigue loading initiates cracks @ internal defects – propagates into network – cement loss or permits microleakage Accompanied by sensitivity or secondary caries
How to we fix the issue of fatigue and occlusal stress causing cracks in cemented crowns? (aka where do we transfer that stress?)
To the prep margins
What are the two forms of primary retention for restos? What is the primary form of sealing?
1) marginal stress 2) prep
from Chemical bonding
What is added to a prep to protect the pulp when using a Zinc Phosphate cement? why?
varnish or dentin sealer b.c during setting the release components from the acid rich matrix into dentin irritate pulp
Do you have to use sealers or varnishes for any other cement material?
No all others (PC, GIC, COMP, Ceramic) all bond to dentin directly
What are the liquid & powder components, and rxn products for ZOE?
Eugenol ZnO Crystalline zinc eugenolate
What are the L & P components, and rxn products of R-ZOE?
Eugenol ZnO, polymer, resin Crystalline zinc eugenolate
EBA?
Eugenol, EBA ZnO, Al2-O3, polymer Crystalline zinc eugenolate, crystalline zinc ethoxybenzoate
ZP?
H3PO4, H2O ZnO Crystalline tertiary zinc phosphate
Silicate (SC)?
H3PO4, H2O F-Al silicate glass Amorphous silicophosphate
PC?
PAA, H2O ZnO Amorphous zinc-polyacrylate gel
GI?
PAA, H2O F-Al silicate glass Amorphous aluminopolyacrylate gel
RMGI?
PAA, H2O, water soluble monomers F-Al silicate glass Amorphous aluminopolyacrylate gel, cross-linked polymer
Compomer ?
Monomers F-Al silicate Amorphous cross-linked polymer aluminopolyarylate gel
COMP?
Monomers silicate glass Amorphous cross-linked polymer
