Theme 10. Indications and steps of plastic crown fabrication.

1. Patient, 30 year old, has enamel defects on vestibular surfaces of upper incisors caused by fluorosis. What from the list of restorative constructions brings the most esthetic view to the patient’s smile?

1. *Composite crown

2. Metal crown

3. Partial crown

4. Combined crown by Belkin

5. Full cast crown

2. Patient is suggested to manufacture acrylic crowns on the upper central incisors. What impression material is preferable for taking workings impressions?

À) *silicone;

B) alginate;

C) gypsum;

D) hydrocolloid;

E) zinc oxide eugenol;

3. A patient of 30 years has come with the purpose of prosthetics. The chosen construction is a composite crown. What impression material is indicated?

À) *Speedex

B) Stens

C) Upeen

D) Ortokor

E) Gelin

4. Man, 25 year old, came for reconstruction of 11 tooth. The chosen construction is acrylic crown. What acrylic resin is used for this crown?

À) *Sinma-M;

B) Norakryl;

C) Redont;

D) Akryloxyd;

E) Ftoraks

5. Preparation for acrylic crown is conducted correct if:

À) *tooth has slightly tapered form;

B) neck of tooth is continuation of tooth crown;

C) tooth has a cylindrical form;

D) distance between reduced tooth and antagonists at closing of jaws is 0, 5 mm;

E) the vertical size of tooth did not change;

6. Polymerization of acrylic resin is produced at a temperature of (degrees per Celsius):

A. *100

B. 680

C. 120

D. 250

E. 80

7. Patient B. was recommended to restore central upper incisors with acrylic crowns. What impression material should be used in order to get auxiliary impression?

1. *Alginate

2. Silicone

3. Gypsum

4. Hydrocolloid

5. Impression compound

8. While preparing polymer dough you should follow this rule:

1. *Add polymer, then monomer

2. Add monomer, then polymer

3. Add monomer and polymer simultaneously

4. Technique doesn’t influence the quality of polymer

5. Heat the dough while mixing

9. Preparation of proximal surfaces for acrylic crown is performed with:

1. *Shaped diamond heads

2. Abrasive disks

3. Carborundum stones

4. Carbide burs

5. Millers

10. A shoulder for an acrylic crown must be located:

A)* at the level of gingiva;

B) below gingiva;

C) on 0,5- 1 mm higher than gingiva;

D) on 0,3-0,5 mm below gingiva;

E) on 0,5-1 mm below gingiva;

11. Thickness of acrylic crown is:

A) *1,5 - 2 mm

B) 0,2 - 0,25mm

C) 0,25 - 0,3 mm;

D) 0,5 - 1 mm;

E) 0,18 - 0,2 mm;

11. You should grind incisal edge of central incisor for acrylic crown on:

A) *2 mm

B) 0,5 mm

C) 1 mm

D) 1,5 mm

E) 2,5 mm

13. Method of acrylic crowns manufacture is:

À) *polymerization;

B) rolling;

C) burning;

D) casting;

E) swaging;

14. Acrylic resin named “Ftorax” is –

1. *Denture base resin

2. Silicone soft liner resin

3. Autocured resin

4. P.V.C.

5. Vinyl chloride resin

15. What are the most types of polymerization reactions?

1. *Polyaddition, polycondensation

2. Polymerization, polycondensation

3. Polysorbtion, polyaddition

4. Polysorbtion, polyaglomeration

5. Polyaglomeration, polymerization

16. Which polymer properties mainly determine functional features of denture and its long-life?

1. *Elasticity and impact resistance

2. Water absorbing and elasticity modulus

3. Specific crash viscosity and crash durability

4. Elasticity and water absorbing

5. Heat stability and impact resistance

17. Which stage of acrylic resin mixture is the most inappropriate for packing? Choose the most correct statement.

1. *Wet sand, rubber

2. Rubber, dough

3. Stringy, dough

4. Dough, wet sand

5. –

18. What is the main ingredient of the most denture base resins?

1. *Polymethylmethacrylate

2. Caoutchouc

3. Dimethylparatholuidin

4. Polycarbonate

5. Nylon

19. Packing is:

1. *Filling mold with polymer-monomer composition

2. Making gypsum mold

3. Acrylisation

4. Preparation of packing mixture

5. Pressing mold with acrylic dough

20. The patient is planned manufacture of plastic crowns. Which of the following is the most correct and complete list of relative contraindications to the manufacture of plastic crowns?

A. * Low clinical crown, abnormal abrasion, allergies, lack of posterior teeth

B. Pathological abrasion, allergies, open bite, high clinical crown

C. Low clinical crown, allergies, jaws anomalies, distal occlusion

D. Deep bite, jaws anomalies, abnormal abrasion, epilepsy

E. Low clinical crown, allergies, epilepsy, deep bite, defective dentition

21. The patient is being manufactured a plastic crown for 11. The doctor prepared tooth with a ledge, took impressions, disinfected them and passed to the dental laboratory. What class of plaster will technician use to cast a working model?

A. * 4, 5

B. 1, 2

C. 2, 3

D. 1, 3

E. 3, 4

22. The patient is being manufactured a plastic crown for 12. The doctor prepared tooth with a ledge, took impressions, disinfected them and passed to the dental laboratory. Technician cast models, engraved neck of gypsum tooth and proceeded to wax modeling. Where was a mistake made?

A. * Preparation of the cervical part of the gypsum tooth

B. Dissection

C. Priority of technical steps

D. The sequence of clinical stages

E. Taking impressions

23. The patient is being manufactured a plastic crown for 22. The doctor received the crown from the laboratory, inspected and tested its quality. What is the next step?

A. *Correction

B. Check in the mouth

C. Disinfection

D. Fixation

E. Polishing the crown

24. The patient is being manufactured plastic crowns for his frontal teeth. What is the optimal period of life of these crowns?

A. * 2 years

B. 4 years

C. 5 years

D. 6 months

E. 7 years

25. The patient is being manufactured plastic crowns for his frontal teeth. Technician cast models, mounted them into occluder, waxed crowns according to occlusal relationships, did the final modeling, invested model in a flask. What is the next step?

A. * burn out of wax

B. Mixing of plastic

C. Packing plastic

D. Opening of a flask

E. Lubrication of gypsum surface