Most Important Operative Dentistry MCQs With Explanations

1. The following chemically bond to the tooth:
A. Composite resin.
B. Dental sealants.
C. Glass ionomer cement. ***
D. All of the above.

2. Compomer restorative materials are:
A. Glass ionomer with polymer components
B. Resin systems with fluoride containing glasses. ***
C. Composite resin for cervical restorations only.

Explanation: The composition of compomers is similar to that of a dental composite however it has been modified, making it a polyacid-modified composite. This results in compomers still requiring a bonding system to bond to tooth tissue.

Although the name compomer implies that the material possesses a combination of characteristics of both composite and glass ionomers, these materials are essentially polymer-based composites that have been slightly modified to take advantages of the potential fluoride-releasing behavior of glass ionomers.

3. Loose enamel rods at the gingival floor of a class II amalgam cavity should be removed using :
A. Straight chisel.
B. Hatchet.
C. Gingival curette
D. Gingival marginal trimmer. ***

Explanation: Gingival marginal trimmers are primarily used for beveling gingival margins, and rounding or beveling of the axiopulpal line angle of Class II preparations. The gingival margin trimmer is designed to produce a proper bevel on gingival enamel margins of proximoocclusal preparations.

4. Removal of Undermined Enamel in Class II cavity is done by :
A. Chisel. ***
B. Angle former
C. Excavator

Explanation: PROXIMAL (CLASS II):
A chisel can be used to plane away unsupported enamel from the
margins of the completed preparation to produce a 90° butt joint.

5. What is the cavo-surface angle of prep for amalgam restoration:
A. 30 degree
B. 60 degree
C. 90 degree ***
D. 130 degree.

6. Hand instrument which we used to make internal angles retentive grooves and preparation of cavity walls in the cavity is:
E. Angle former. ***
F. Chisel.
G. File.
H. Enamel hatchet

7. To provide maximum strength of amalgam restoration the cavo-surface angles
should:
1. Approach 75 with outer surface.
2. Approach 90 with outer surface.
3. Be supported by sound dentine.
4. Be located in area free of occlusal stress.
A. 1+3 and 4.
B. 1+3.
C. 2+3+4. ***
D. 3+4.

8. Which of the following materials has been shown to stimulate reparative dentine
formation most effectively when applied to the pulpal wall of a very deep cavity:
A. Copalite varnish.
B. Calcium hydroxide preparation. ***
C. Zinc phosphate cement.
D. Anhydrous glass ionomer cement.

9. Calcium hydroxide is the best pulp capping material because:
A. It has the best seal over pulp.
B. It is alkaline + less irritating to the pulp.
C. It induces reparation dentine formation. ***

10. Clinical failure of the amalgam restoration usually occurs from:
A. Improper cavity preparation. ***
B. Faulty manipulation.
C. Both of the above.
D. None of the above.

11. It has been proven that amalgam restoration has the following characteristics:
1. Micro leakage decrease with the aging of the amalgam restoration.
2. It is the least technique sensitive of all current direct restorations.
3. High dimensional changes.
A. 1 , 2 and 3.
B. 1 and 3.
C. 1 and 2. ***
D. 2 only.

** During electrochemical corrosion of low-copper amalgams, The Sn-Hg phase is oxidized into Sn-O and/or Sn-O-Cl. The oxychloride species is soluble.
** The oxide Precipitates as crystals and tends to fill up the spaces Occupied by the original Sn-Hg phase. Along the margins Of the amalgam, Sn-O helps seal the space against Microleakage.
** During setting, most amalgams undergo very little Dimensional change.
** The dimensional change during the setting of amalgam is one of its most characteristic properties.
** Modern amalgams mixed with mechanical amalgamators usually have negative dimensional changes.
**The only exception to this statement is the excessive delayed dimensional change resulting from
contamination of a zinc-containing alloy with water during trituration or condensation.

12. When polishing the amalgam restoration:
A. Avoid heat generation by using wet polishing paste.
B. Wait 24 hours.
C. A and b. ***
D. B only.

13. Maximum time elapsed before condensation of amalgam after titration:
A. 1minute.
B. 3minutes. ***
C. 9minutes.

14. After amalgam trituration, the mix should be placed within:
A. 1 min. ***
B. 3 min. ***
C. 5 min.

15. MOD amalgam restoration with deep mesial box, patient comes with pain related to it after 1 month due to:
A. Pulp involvement. ***
B. Supraocclusion.
C. Upon contact.
D. Gingival recession.

16. Reduction in amalgam restoration should be:
A. 1-1.5 mm.
B. 1.5-2 mm. ***
C. 2-3 mm.
D. 3-5 mm.

Explanation: ** It must have a minimum thickness of 0.75 to 2 mm. (because of its lack of compressive strength)

17. Depth of amalgam restoration should be:
A. 1 – 1.5 mm.
B. 1.5 – 2 mm. ***
C. 2 – 3 mm.
D. 3 – 5 mm.

18. Silicate cement:
1. First tooth colored restoration.
2. It can be used as permanent filling.
3. It contains 15 % fluoride.
A. 1 , 2 and 3.
B. 1 and 2.
C. 1 and 3. ***
D. 1 only.

Silicate cement , the first translucent filling material, was introduced in 1878 by Fletcher in England . Silicate cement contain 12-25 % Fluoride. ZOE , reinforced ZOE, ZOE-EBA, Silicate and zinc phosphate cements are no longer routinely used to permanently cement restorations.

19. Length of pins must be equals in both tooth and restoration by a depth of:
A. 1 mm.
B. 2 mm. ***
C. 3 mm.
D. 4 mm.

20. Stainless steel pin is used in amalgam for:
A. Increased retention. ***
B. Increased resistance.
C. Increased strength.
D. A and b.

21. What can we use under composite restoration:
A. Ca (oh). ***
B. ZOE.
C. ZINC phosphate cement.

22. The x- ray of choice to detect the proximal caries of the anterior teeth is:
A. Periapical x-ray. ***
B. Bitewing x-ray.
C. Occlusal x-ray.
D. None of the above.

23. What is the copper ratio that eliminates gamma phase 2:
A. 2% copper
B. 4% copper
C. 10 % copper
D. 13 % copper ***

24. To prevent discoloration under amalgam filling:
A. Use Zn phosphate box.
B. Use cavity varnish. ***
C. Wash the cavity with NaOCL b4 filling.
D. Use the correct amalgam-alloy ratio.

25. Polishing bur have:
A. Less than 6 blades.
B. 6-7 blades.
C. 10-12 blades.
D. More than 12 blades. ***

26. Rubber dam is contraindicated in:
A. Pt with obstructive nose. ***
B. Mentally retarded Pt.
C. Un comparative child.
D. A and b.

27. Pt complain from pain in 45 which had gold onlays. The pain could be due to:
A. Chemicals from cement.
B. High thermal conductivity of gold. ***
C. Related to periodontal ligament.
D. Cracked tooth or fractured surface.

Explanation: Disadvantages of gold restoration:
Esthetics – cost – time consuming – difficulty of technique – the need to use cement. (the weakest point in the cast gold restoration) – Gold has high thermal conductivity.

28. Pt complain from pain during mastication which had gold onlays. The pain could be
due to:
A. Chemicals from cement.
B. High thermal conductivity of gold.
C. Related to periodontal ligament. ***
D. Cracked tooth or fractured surface.

29. Class II composite resin is lined by:
A. G.I. ***
B. Reinforced ZOE.
C. ZOE with epoxy cement.
D. Cavity varnish.

30. In cavity preparation, the width of the cavity is:
A. 1/2 inter cuspal distance.
B. 1/3 inter cuspal distance. ***
C. 2/3 inter cuspal distance.

31. Selection of shade for composite is done:
A. Under light.
B. After drying tooth and isolation with rubber dam.
C. None of the above. ***

32. Most commonly, after placement of amalgam restoration PT. Complain from pain with:
A. Hot.
B. Cold. ***
C. Occlusal pressure.
D. Galvanic shock.
E. Sweet.

33. Calcium hydroxide is used in deep cavity because it is:
A. Simulate formation of 2nd dentine. ***
B. Not irritant to the pulp.
C. For thermal isolation.

34. In placement of rubber dam:
A. 4 jaw contact in teeth.
B. Only 4 contacts 2 lingual surface and 2 buccal surface. ***
C. Only 4 contacts 2 mesial and 2 distal.