Dental Materials Practice Exam I.

Dental Materials Practice Exam I

This exam is intended for you to practice the content from the Dental materials lectures 1 to 3 (Restorative Materials, Prosthetic Materials I. and Prosthetic Materials II.)

The exam result is not recorded, and you can repeat the exam as many times as you like.

1 / 20

Which of the following is NOT true about composite resin filling materials?

They are very moisture sensitive, and care must be taken to avoid moisture contacting them.

They are typically light cured by 470nm wavelength beams, but regular sunlight has no effect on them.

The silane links the silica or quartz filler to the resin, which polymerises using free radicals.

The size of the fillers in nanohybrid composites ultimately affects both the strength and colour of the filling.

2 / 20

Which of the following is true about composite materials? [Select three (3) correct answers]

Composite materials are typically light cured, which means that light activates the photoinitiator that starts the polymerisation reaction.

Glycerin is a transparent material that cuts off oxygen supply to the surface of the composite.

Most composites can only be layered up to 5 mm before light curing, because the photoinitiator is only present on the top surface of the composite.

The curing light uses a wavelength that is in the visible range. This appears to us as blue.

3 / 20

Which is the following is true about glycerin? [Select two (2) correct answers]

Glycerin prevents oxygen from reaching the surface of the composite.

Glycerin is mostly transparent, and so, it allows the curing light to pass through.

Glycerin chemically increases the linking strength between two layers of composite.

Glycerin should be left on the tooth for 2 to 3 hours to allow the polymerisation to proceed to completion.

4 / 20

Which of the following statements is accurate about universal adhesives?

Universal adhesives bond chemically to enamel, dentin and composite.

They are light cured, which causes it to dissolve slightly so that the tooth structure and the composite to touch more directly.

It is composed of 10 MDP polymers that are further polymerised upon self curing.

For composite fillings, the bonding action of the universal adhesive is not as important for the filling to remain inside, as the way the dentist shapes the cavity.

5 / 20

How can we reduce mercury exposure for dental staff?

By selecting composite materials instead for the cases where a lot of saliva will touch the filling during the procedure.

By using the HVE suction when removing amalgam with a drill.

By mixing enough capsules, so that the dentist always has enough to work with, even if this leaves excess.

Sterilising instruments after working with amalgam, and throwing the excess amalgam in the regular trash bin.

6 / 20

Which of the following is true about restorative materials?

The polymerisation reaction of composite is complete after 24 hours, and that is why patients should delay eating harder foods after the procedure.

The working time and setting time of a material mean the same thing.

Mixing a glass ionomer cement for long might cut into the dentist's working time.

Amalgam responds to pressure similarly to normal tooth structure, which means it cannot crack the tooth.

7 / 20

Which material are pediatric (childrens’) full metal crowns typically made out of?

Stainless steel.

Amalgam.

Gold-copper.

Vanadium tetrafluoride.

8 / 20

Which of the following is a possible material to use to make a denture base?

Acrylic

Wax

Zirconia

Nanohybrid composite

9 / 20

Which of the following statements about porcelain are true? [Select two (2) correct answers]

The full form of PFM is Porcelain Forged with Metal.

In all-ceramic crowns, the porcelain bonds to the metal coping with a layer of metal oxide.

PFM restorations are typically fabricated (made) by hand by the lab technician.

The first firing of ceramic is the bisque bake, while the final firing is the glaze bake.

10 / 20

Which of the following is a disadvantage of Porcelain fused to metal restorations?

They can begin to show a greyish tinge over time.

They are weaker than zirconia and e.max restorations.

They automatically chemically bond to tooth structure, which makes the cementation process more tedious.

Porcelain Fused to Metal restorations are more digital, and thus more expensive than other restorations.

11 / 20

Which of the following statements are true about alginate? [Select all the correct answers]

Alginate is a hydrocolloid, and can change size when left exposed to dry air for long.

The removal process of an already hardened alginate impression should be fast, to reduce the chance of tearing.

Calcium alginate is the insoluble compound that is produced during the setting reaction of alginate.

The water powder ratio has an effect on the tear strength of the alginate impression.

12 / 20

Which of the following techniques of handling gypsum is NOT correct?

It should be mixed evenly and thoroughly to avoid voids in the final cast.

The water and powder ratio of the manufacturer should be maintained.

The gypsum should be gently poured into the cast from all directions, little by little.

Using dedicated vibrating machines when pouring gypsum into impressions, helps prevent voids.

13 / 20

Which of the following is true concerning retraction cords and homeostatic agents? [Select two (2) correct answers]

Retraction cords are not needed for digital impressions with intraoral scanners.

If a #0 cord is too small, then a #00 cord should be tried next.

Some retraction cords are pre-soaked in ferric sulfate and/or epinephrine to control bleeding.

Cords that have not been pre-soaked in astringent by the manufacturer, can be soaked in ferric sulfate for at least 20 minutes.

14 / 20

How should we mix glass ionomer?

[Select two (2) correct answers]

With an clean stainless steel spatula.

Slowly add the liquid drops to the powder.

Slowly add small amounts of powder to the liquid.

Mix it on a clean dry mixing pad.

15 / 20

Which of the following are part of the four main parts of dental composite?

[Select two (2) correct answers]

Resin.

Glycerin.

Photoinitiator.

Calcium fluoroalumnosilicate glass.

16 / 20

“Composites harden by polymerisation” BECAUSE “the silane linking agent is activated by the light cure”.

(The format of the question is: “Statement 1” BECAUSE “Statement 2”)

Both Statement 1 and Statement 2 are true, and Statement 2 explains Statement 1.

Both Statement 1 and Statement 2 are true, but Statement 2 does not explain Statement 1.

Statement 1 is true, and statement 2 is false.

Statement 1 is false, and statement 2 is true.

Statement 1 is false, and statement 2 is false.

17 / 20

Why is Nickel used frequently in dentistry? [Select two(2) correct answers]

Nickel is strong.

Nickel is cheap.

Nickel has a low rate of allergy.

Nickel does not chemically corrode.

18 / 20

Which of the following impression materials are hydrophilic (go towards water)? [Select two (2) correct answers]

Alginate.

Addition Silicone.

Condensation Silicone.

Polyether.

19 / 20

What is the function of aluminium chloride in impression taking?

It is an anti-anxiety substance.

It stabilises the setting reaction of the silicon impression material.

It makes digital impressions more accurate.

It is a haemostat.

20 / 20

Identify the true statement about porcelain.

The first firing is the glaze bake, and the last firing is the bisque bake.

Feldspar and leucite are used to make e.max restorations.

Zirconia is a metal oxide.

Lithium disilicate restorations can be etched with orthophosphoric acid.

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