s8-finals-Luting Cements

Question 1

What is the primary purpose of luting cements?

Answer 1

To bond prostheses to tooth structure and seal margins.

Question 2

Name two key requirements of an ideal luting agent.

Answer 2

Good adhesion, biocompatibility, low film thickness (any two).

Question 3

How are luting cements classified by use?

Answer 3

Permanent (definitive) or temporary (provisional).

Question 4

What distinguishes adhesive from non-adhesive cements?

Answer 4

Adhesive cements form chemical bonds; non-adhesive rely on mechanical retention.

Question 5

Name the 5 main types of luting cements (Craig’s classification).

Answer 5

Zinc oxide-eugenol, zinc phosphate, zinc polycarboxylate, glass ionomer, resin cement.

Question 6

What is micromechanical bonding?

Answer 6

Retention via surface irregularities (e.g., etching, sandblasting).

Question 7

How is enamel prepared for micromechanical bonding?

Answer 7

Etching with 37.5% phosphoric acid.

Question 8

What surface treatment is used for porcelain bonding?

Answer 8

Hydrofluoric acid etching + silane coupling agent.

Question 9

What is the main advantage of zinc oxide-eugenol cement?

Answer 9

Biocompatibility (sedative effect on pulp).

Question 10

Why is zinc oxide-eugenol avoided with composite restorations?

Answer 10

Eugenol inhibits resin polymerization.

Question 11

What is a clinical use for modified ZOE (EBA) cement?

Answer 11

Temporary cementation of permanent restorations.

Question 12

What is the main disadvantage of zinc phosphate cement?

Answer 12

High solubility in oral fluids.

Question 13

Why is a cool glass slab used for mixing zinc phosphate?

Answer 13

Prolongs working time, reduces heat, and accelerates pH rise.

Question 14

What is the ideal film thickness for luting cements?

Answer 14

≤25 microns.

Question 15

How is zinc phosphate cement tested for proper consistency?

Answer 15

Should string 10mm between spatula and slab.

Question 16

When should excess zinc phosphate cement be removed?

Answer 16

After complete setting (not during rubbery stage).

Question 17

What protects the pulp when using zinc phosphate cement?

Answer 17

Varnish or liner in deep preparations.

Question 18

What is the pH of zinc phosphate cement at mixing?

Answer 18

~4.2 (rises to neutral after 48 hours).

Question 19

What is the primary bonding mechanism of zinc polycarboxylate?

Answer 19

Chemical adhesion (carboxyl groups + tooth calcium).

Question 20

Why is zinc polycarboxylate biocompatible?

Answer 20

Weak polyacrylic acid and rapid pH rise (to 6-7).

Question 21

What is pseudoplasticity in cement mixing?

Answer 21

Viscosity decreases under shear force (e.g., spatulation).

Question 22

What is the working time of zinc polycarboxylate cement?

Answer 22

~2.5 minutes.

Question 23

How is adhesion improved for zinc polycarboxylate?

Answer 23

Apply 10% polyacrylic acid conditioner to tooth.

Question 24

What is the key advantage of glass ionomer cement (GIC)?

Answer 24

Fluoride release and chemical adhesion to tooth structure.

Question 25

Why is GIC contraindicated for all-ceramic restorations?

Answer 25

Risk of expansion-induced ceramic fracture.

Question 26

What are the components of GIC?

Answer 26

Alumino-fluorosilicate glass + polyacrylic acid.

Question 27

How does resin-modified GIC (RMGI) set?

Answer 27

Through acid-base reaction + light/chemical cure polymerization.

Question 28

What is the main disadvantage of conventional GIC?

Answer 28

Moisture sensitivity during setting.

Question 29

When is RMGI preferred over conventional GIC?

Answer 29

For metal/ceramic crowns needing higher strength.

Question 30

What are the three setting reactions of RMGI?

Answer 30

1) Acid-base, 2) Light cure, 3) Chemical cure.

Question 31

What is the compressive strength of resin cements?

Answer 31

200-250 MPa.

Question 32

Name the three polymerization modes of resin cements.

Answer 32

Chemical-cured, light-cured, dual-cured.

Question 33

Why is dual-cured resin cement preferred for deep cavities?

Answer 33

Ensures polymerization in light-limited areas.

Question 34

What surface treatment is needed for ceramic bonding with resin?

Answer 34

HF acid etching + silane coupling agent.

Question 35

What is the purpose of silane coupling agent?

Answer 35

Bonds resin to ceramic's silica content.

Question 36

What is the main disadvantage of resin cements?

Answer 36

Technique sensitivity and post-op sensitivity risk.

Question 37

How is enamel prepared for resin cementation?

Answer 37

37.5% phosphoric acid etching.

Question 38

What is the role of oxygen-inhibiting gel (e.g., Oxyguard)?

Answer 38

Prevents air inhibition of resin polymerization.

Question 39

What cement is best for high-caries-risk patients?

Answer 39

Glass ionomer (due to fluoride release).

Question 40

What cement is ideal for all-ceramic restorations?

Answer 40

Adhesive resin cement (for esthetics and bonding).

Question 41

When would zinc phosphate be preferred over resin cement?

Answer 41

For long-span bridges needing extended working time.

Question 42

What cement is recommended for deep preparations?

Answer 42

Zinc polycarboxylate (pulp-friendly).

Question 43

What is bioactive cement's key advantage?

Answer 43

Bonds to tooth/zirconia without separate etching.

Question 44

Name a commercial bioactive cement example.

Answer 44

Ceramir C&B (calcium aluminate + GIC).

Question 45

What cement should be avoided with resin-bonded retainers?

Answer 45

Zinc oxide-eugenol (inhibits resin polymerization).