Lec. 11 - Dental Cements

Question 1

What are dental cements based on? (Rxns between what)

Answer 1

Basic powderes (ceramic particle) & Acidic liquids

Question 2

Properties of cements depend on the extent to which the matrix is ____ in the ____ ____

Answer 2

minimized final material

Question 3

What material is considered the “gold standard” for all other dental cements, despite its inferiority? How is it “inferior”? Does it bond to dentin?

Answer 3

Zinc Phosphate Weaker and more brittle No

Question 4

In Zinc phosphate, what is the powder and liquid components made of?

Answer 4

Powder: 90% ZO - 10% Mg Liquid: 50% phosphoric acid in water w/ Al zinc salts

Question 5

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?

Answer 5

Polycarboxylate cement (PC) GI & RMGI RMGI

Question 6

What material is used for all ceramic restos? What are the pros and cons?

Answer 6

Composite cement Best lab properties of all the cements, but more complicated clinical procedures and bonding systems

Question 7

What are compomer cements called? Why? What was added to this type of composite cement?

Answer 7

“universal cements” b/c they promise to work for metal and all ceramic restos fluoride releasing glass filler particles

Question 8

What are the two uses for dental cements?

Answer 8

Luting agents and bases

Question 9

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?

Answer 9

1) flow 2) wetting 3) film thickness you want them to be mechanically stronger and are mixed with the maximum powder content manageable

Question 10

How is the flow enhanced? How can you make a thin film?

Answer 10

Lowering the viscosity: - mixed low powder to liquid ratio phase particles of 5 um or less in diameter

Question 11

Which type of material has the greatest film thickness? Which one has the lowest?

Answer 11

R-ZOE ZP (zinc phosphate)

Question 12

Rank all the materials from greatest tenile strength to lowest

Answer 12

COMP/RMGI (both 30-35) GI (12) ZP/PC (10) EBA (7) R-ZOE (4)

Question 13

Rank compressive strengths form greatest to weakest

Answer 13

COMP (170-190) RMGI (148-180) ZP (160) GI (120) PC (70) EBA (65) R-ZOE (48)

Question 14

High P/L ratio = _____ mechanical strength High P/L = _____ viscosity

Answer 14

increased increased

Question 15

What are the two goals for cementation?

Answer 15

1) retention 2) sealing

Question 16

How is sealing compromised? What results?

Answer 16

Fatigue loading initiates cracks @ internal defects – propagates into network – cement loss or permits microleakage Accompanied by sensitivity or secondary caries

Question 17

How to we fix the issue of fatigue and occlusal stress causing cracks in cemented crowns? (aka where do we transfer that stress?)

Answer 17

To the prep margins

Question 18

What are the two forms of primary retention for restos? What is the primary form of sealing?

Answer 18

1) marginal stress 2) prep from Chemical bonding

Question 19

What is added to a prep to protect the pulp when using a Zinc Phosphate cement? why?

Answer 19

varnish or dentin sealer b.c during setting the release components from the acid rich matrix into dentin irritate pulp

Question 20

Do you have to use sealers or varnishes for any other cement material?

Answer 20

No all others (PC, GIC, COMP, Ceramic) all bond to dentin directly

Question 21

What are the liquid & powder components, and rxn products for ZOE?

Answer 21

Eugenol ZnO Crystalline zinc eugenolate

Question 22

What are the L & P components, and rxn products of R-ZOE?

Answer 22

Eugenol ZnO, polymer, resin Crystalline zinc eugenolate

Question 23

EBA?

Answer 23

Eugenol, EBA ZnO, Al2-O3, polymer Crystalline zinc eugenolate, crystalline zinc ethoxybenzoate

Question 24

ZP?

Answer 24

H3PO4, H2O ZnO Crystalline tertiary zinc phosphate

Question 25

Silicate (SC)?

Answer 25

H3PO4, H2O F-Al silicate glass Amorphous silicophosphate

Question 26

PC?

Answer 26

PAA, H2O ZnO Amorphous zinc-polyacrylate gel

Question 27

GI?

Answer 27

PAA, H2O F-Al silicate glass Amorphous aluminopolyacrylate gel

Question 28

RMGI?

Answer 28

PAA, H2O, water soluble monomers F-Al silicate glass Amorphous aluminopolyacrylate gel, cross-linked polymer

Question 29

Compomer ?

Answer 29

Monomers F-Al silicate Amorphous cross-linked polymer aluminopolyarylate gel

Question 30

COMP?

Answer 30

Monomers silicate glass Amorphous cross-linked polymer