Theme 13. Troubleshooting while crowns fabricating.

1. A crack appeared on the vestibular surface of the metal crown during the final swaging by combined method (MMSI). What is the origin of this defect?

* A. There was no pre-annealing

B. Significant mechanical forces

C. The size of the die is too large

D. The size of the crown is too small

E. The way of swaging is incorrect

2. A crease was formed on the approximal surface of the crown during the initial swaging. What is the origin of this defect?

A. * large size of a cartridge

B. Small size of a die

C. Too rapid swaging

D. Force was applied at an angle to the axis of the die

E. cartridge was thinned

3. While fitting test a plastic crown is applied with great effort, bursting adjacent teeth due to excess of plastic on the contact surfaces. What is the reason of this mistake?

A. * brake off the adjacent teeth on the model

B. plaster was loosen on the surface model

C. Shrinkage of impression material

D. streaks or creases in the impression

E. Displacement of teeth in the mouth

4. In the manufacture of the plastic crown on the stage of replacing the wax on the plastic gypsum die with wax pattern is invested in the flask. What position of the die in flask prevents brake off a gypsum die while packing acrylic dough?

A. * Vertical

B. Horizontal

C. Under 45 °

D. Vestibular surface to the bottom

E. Vestibular surface to the top

5. The finished crown made of plastic "Sinma-M" has a clear blue-green hue. This suggests that the wax reproduction was modeled in wax:

* A "Lavax"

B. "Formodent"

C. “Modevax”

D. Sticky Wax

E. Base wax

F. Colorless wax

6. For the manufacture of cast crown for 35 tooth, the impressions of the corresponding half of both jaws are received, casts are poured. What mistake will it cause while modeling the crown?

A. * Disharmony in shape and size with 45

B. It is impossible to put model in the central occlusion

C. Improper modeling of the occlusal surface of 35

D. Incorrect modeling of the vestibular surface of 35

E. Improper modeling of approximal surfaces of 35

7. Endodontically treated tooth will be covered with porcelain crown. Peculiarity of preparation in this case is -

A) *Post and core

B) Dental tissues are reduced less

C) Tapered preparation

D) Dental tissues are reduced more

E) Pins

8. By purpose the crowns are:

1. *restorative

2. jacket

3. duplicating

4. partial

5. full

9. By construction, the crowns are:

A) jacket; B) combined, and C) of metal; D) Telescopic, E) plastic.

A. * A, B, D

B. A, D

C. A, B, C, D, E

D. B, D

E. B, C, D, E

10. The patient, 24 years old, is being made a complete composite crown for 13 tooth. Objectively: dentition are intact, 13 tooth is pulpless, changed in color. Doctor prepared the tooth: it has a little taper, the ledge is 0.8 - 1.0 mm, angled at 130 degrees, located at 1 mm below the gingival margin. What mistake made the doctor?

A) * the level of ledge location;

B) the size of the ledge;

C) the shape of the ledge;

D) localization of the ledge in the cervical area;

E) irregular shape of the core;

11. A patient came with complaints about pain in 25 tooth, which appeared on the second day after fixing of artificial crown. Examination: percussion of 25 is painless, the edges of ceramic crown adjoin to the gingival edge. On bite record the premature contact is on a 25 tooth. What is the most evident reason of pain?

À) *increase of interalveolar height;

B) pulpitis;

C) caries;

D) trigeminal neuralgia;

E) eating of solid food;

12. In order to remove cast metal-acrylic restorations you should use:

1. *diamond bur

2. vulcanite disk applied to vestibular surface

3. Kopp apparatus

4. Local heating and cooling of crowns

5. Electrophoresis ions with 0.9% NaCl solution

13. Male patient, 45 year-old, came with complaints about pain at biting on a 25 tooth, which had appeared in 2 weeks after covering with crown. Intraoral exam: 25 tooth is covered by a metal crown; percussion is painful, gap between construction and tooth is determined while probing. Premature contact between antagonists was revealed on the occlusogramm. When did the doctor likely make a mistake?

1. *Cementation

2. Preparation

3. Fitting

4. Taking impression

5. Treatment planning

14. A healthy gingival crevice usually has a depth of:

1. *0.7 mm

2. 0.5 mm

3. 0.6 mm

4. 1 mm

15. A 32-year-old patient complains about gingival haemorrhages during eating and tooth

brushing. It is known from the anamnesis that 2 weeks ago the patient got a cast metal

crown. Objectively: the 27 tooth has a cast metal crown going beyond the gingival edge by

1-1,5 mm, touching causes haemorrhage. Percussion is slightly painful. What tactics is the

most appropriate in this case?

A *To remove the crown and administer treatment for marginal periodontitis

B To administer gargling with Rotocan

C To open the crown through the masticatory surface

D To give the patient time to get used to the prosthesis

E To remove the crown and fabricate a splint

16. After making the complete swaged crown a doctor conducts try-in of the crown in the oral cavity. While he is pressing on the edge of crown it deepens into a gingival sulcus and injures its bottom. What tissue covers the bottom of gingival sulcus?

À) *epithelium;

B) epidermis;

C) connecting tissue;

D) muscle tissue;

E) cartilaginous tissue;

17. There is marginal leakage between artificial crown and tooth. What complications are possible, except:

À) *premature contact with antagonists;

B) formation of calculus with closing of access in a gingival sulcus;

C) acute gingivitis;

D) development of neck caries;

E) poor hygiene of oral cavity.

18. What is the reason of gingivitis while using a single complete artificial crown?

À) *poor marginal seating of restoration;

B) cervical caries;

C) inherited predisposition;

D) eating of solid food;

E) middle depth caries.

19. What is the reason of acute traumatic periodontitis while using a single artificial crown?

À) *interalveolar increase in one of occlusions;

B) interalveolar decrease in central occlusion;

C) low degree of marginal seating of restoration;

D) absence of equator of artificial crown;

E) absence of contact points with neighboring teeth.

20. What is the reason of acute traumatic periodontitis of tooth opposing to a tooth with single artificial crown?

À) *lower periodontium resistance of tooth-antagonist than tooth, that covered with crown;

B) higher periodontium resistance of tooth-antagonist than tooth, that covered with crown;

C) poor endodontical treatment;

D) faulty treatment of caries;

E) pathological attrition.

21. A patient came to hospital with a complete artificial crown on 25 tooth. A doctor diagnosed marginal periodontitis. What is possible reason?

À) *an artificial crown deeply submerges in a gingival sulcus;

B) eating of solid food;

C) allergic reaction on material of crown;

D) absence of contact with antagonists;

E) poor treatment of pulpitis;

22. A week ago a swaged crown was cemented on a tooth. Pain at biting appeared. Supercontact was revealed at examination. What is a reason of pain?

1. *Traumatic apical periodontitis

2. Gingivitis

3. Chronic periodontitis

4. Chronic pulpitis

5. Acute periodontal disease

23. Male, 48 year-old, came with complaints about pain at biting in area of a 25 tooth, which appeared in a month after covering with crown. Dental history: tooth was treated concerning caries. Examination: 25 tooth is covered with complete metal crown, percussion is painless. On occlusogramm is a premature contact between antagonists. What could be the most possible reasons of this condition?

À) inadequate occlusal reduction, overcontouring of crown;

B) inadequate axial reduction;

C) congenital disorders of teeth eruption;

D) defective investing and casting;

E) inadequate marginal configuration;

24. While swaging dental technician made a mistake – the crown was made too long, that’s why it excessively deepened into gingival sulcus and leaded to marginal periodontitis. What depth is appropriate for the marginal edge of swaged crown?

1. *0.1 – 0.25 mm

2. 0.3 – 0.5 mm

3. 0.6 – 0.8 mm

4. 0.8 – 1.1 mm

5. 1.1 – 1.3 mm

25. While preparation the shoulder the doctor made a mistake. Which shoulder location is incorrect?

1. *1 mm subgingivally

2. Supragingivally

3. At gingival level

4. 0.3 mm subgingivally

5. 0.5 mm subgingivally