Theme 17 Fixed dentures cementation

1. The sequence of crown cementation:

1. put artificial crown on abutment tooth

2. degrease and dry up a crown and abutment tooth

3. put cotton rolls from both sides

4. make a cement paste and put it into a crown

5. take off surpluses of cement round a crown before cement gets fast

1. *3,2,4,1,5

2. 1,2,3,4,5

3. 2,1,3,4,5

4. 3,4,5,1,2

5. 2,4,3,1,5

2. For permanent cementation of swaged-soldered dentures we use –

1. *Phosphate cements

2. Acrylic resins

3. Aqua dentin

4. Repeen

5. Composite cement

3. Artificial crowns are permanently cemented by:

À)* cement “Visphate”

B) cement “Silicin”

C) cement “Silidont”

D) autocured resin

E) cement “Phosphate”

4. Setting time of zinc phosphate cement is approximately:

À) *4 - 9 min

B) 15 - 20 min

C) 10 - 15 min

D) 20 - 25 min

E) 25-30 min

5. What consistency glass ionomer cement should be?

1. *Creamy

2. Sticky

3. Jelly-like

4. Liquid

5. –

6. What is the influence of speed while mixing zinc-phosphate cement?

1. *Rapid mixing – rapid setting

2. Rapid mixing – slow setting

3. Doesn’t influence

4. Slow mixing – rapid setting

5. –

7. Fixed crown can be removed with the following EXCEPT:

1. *bring down with chisel

2. Cut with wheel shape bur

3. Cut with carborund disk

4. Cut with crown scissors

5. Bring down with Kopp

8. Artificial crown is being fixed in patient’s mouth. What is necessary to process a core of vital tooth in order to prevent pulp irritation before cementation?

1. *Copal cavity varnish

2. Alcohol

3. Petrolatum

4. Hydrogen peroxide

5. NaCl solution

9. A patient is at the appointment of crown cementation. Swaged crown will be cemented with zinc-phosphate cement. What is the bonding mechanism of this cement?

1. *Mechanical bonding

2. Micromechanical bonding

3. Molecular adhesion

4. Chemical adhesion

5. –

10. What is used for mixing zinc-phosphate cement?

1. *Smooth surface of glass slab

2. Rough surface of glass slab

3. Special paper

4. In a bowl

11. What cement doesn’t need dry tooth surface while cementation?

1. *Polycarboxylate

2. Zinc-phosphate

3. Glass ionomer

4. Zinc-oxide eugenol

5. –

12. What can be used for making irregularities on ceramic surface?

1. *Hydrofluoric acid

2. Electrolytic etching

3. Phosphoric acid

4. Sand-blasting

5. Chemical etching

13. A doctor is fixing cast bridge with abutments on 17, 14 using glass ionomer cement. He isolated a quadrant with teeth from saliva, cleaned and dried the teeth. Mixed cement rapidly with right proportions. Cement seemed to the operator too thick. What is the reason of this event?

1. *Short time of mixing

2. Inadequate proportions of powder and liquid

3. Long time of mixing

4. Cement is out of exposed data

5. –

14. Choose from the following correct and full statement about types of modern cements for permanent fixation?

1 – zinc-phosphate, polycarboxylate, glass ionomer, modified glass ionomer, polymeric

2 - zinc-phosphate, zincpolyacrylate, polyethylenoate, modified with polymers, polymeric

3 - zinc-phosphate, zinc-oxide eugenol, polycarboxylate, glass ionomer, modified glass ionomer, polymeric

1. *Both 1 and 2

2. 1

3. 2

4. 3

5. Both 2 and 3

15. The more powder of zinc-phosphate cement incorporated into the mix results in –

1. *The stronger and less acidic cement

2. The weaker and less acidic cement

3. The stronger and more acidic cement

4. The weaker and more acidic cement

5. –

16. Right consistency of phosphate cement –

À) *strings out about 10 mm between spatula and slab;

B) runs quickly off the spatula;

C) is nudged off the spatula;

D) strings out about 20 mm between spatula and slab;

E) jelly-like;

17. What luting agents possess the maximal tensile strength?

1. *Composite, modified glass ionomer

2. Polycarboxylate, glass ionomer

3. Composite, glass ionomer

4. Modified glass ionomer, polycarboxylate

5. Zinc-phosphate, glass ionomer

18. What luting agents can give the minimal film thickness?

1. *zinc-phosphate, glass ionomer, modified glass ionomer, composite

2. polycarboxylate, glass ionomer, modified glass ionomer, composite

3. glass ionomer, modified glass ionomer, composite

4. modified glass ionomer, composite

5. zinc-phosphate, polycarboxylate, glass ionomer, modified glass ionomer

19. Which three factors influence loosening restorations statistically deeply?

1. *Periodontal inflammation, failure of marginal seating, inadequate tooth preparation

2. Wrong selection of construction, caries of abutment teeth, inadequate tooth preparation

3. Periodontal inflammation, failure of marginal seating, wrong selection of construction

4. Wrong selection of construction, periodontal inflammation, occlusal disturbances

5. Periodontal inflammation, failure of marginal seating, caries of abutment teeth

20. Time of mixing for zinc-phosphates is –

1. *90 sec

2. 1 min

3. 30 sec

4. 45 sec

5. 2 min

21. What cement that mentioned below has the best adhesion to hard dental tissues?

1. *Polycarboxylate

2. Zinc-oxide eugenol

3. Silicate

4. Zinc phosphate

5. No one from this list

22. What luting agent that mentioned below has the best adhesion to enamel?

1. *Composite

2. Glass ionomer

3. Modified glass ionomer

4. Polycarboxylate

5. Silicate

23. What influences the marginal seating of fixed denture?

1. *All from the list

2. Finish line configuration

3. Viscosity of luting agent

4. Quality of impression

5. Nothing from the list

24. What tooth preparation leads to loosening of the restoration?

1. *With increased taper

2. With parallel walls

3. With diverted cone

4. Without shoulder

5. With 90° shoulder

25. Female patient complains of mobility and loosening of a crown from 21 tooth. Plastic crown has post inside which equals to ½ of root length. What is the reason of loosening of post and core construction?

1. *The length of post is not enough

2. Wrong selection of the construction

3. Wrong selection of luting agent

4. Inadequate color of facing material

5. The patient doesn’t follow the rules of crowns using