Dental Materials Ch 3,6, and 9

In order to initiate the reaction stage of a light-activated material, a blue light must be used.

TRUE

Liquids have volume but no shape. Most dental materials are mixtures of more than one state of matter.

Both statements are TRUE

A material's shelf life has expired, but because it hasn't been opened, it should retain all of its properties.

FALSE

The physical property that affects a material's ability to flow is:

VISCOSITY

Intermediate restorations are meant to last several weeks to months.

TRUE

Gold is a brittle material because it is so thin.

FALSE

The characteristic of being thixotropic is desirable for a fluoride gel. The gel increases to a high viscosity when under mechanical pressure, which increases its ability to flow.

The first statement is TRUE, the second statement is FALSE

Brittle materials are able to withstand tensile stresses better than compressive stresses.

FALSE

Mixing a material quickly can speed up the reaction time of a material. High humidity slows down the reaction time of materials.

The first statement is TRUE, the second statement is FALSE

Enamel has high ___________ due to its crystalline structure, making it comparatively hard.

DENSITY

Your office has one curing light, and it is broken. Which material can you still use?

Chemical cure

The weakest primary bond where an electron is donated from one atom to another is which kind of bond?

IONIC BOND

You have mixed a dental cement for placement of a temporary crown in the patient's mouth. The material has been carried to the patient's mouth, but the temporary cannot be seated because the material has already begun to set. The material has reached which reaction stage?

Initial set time

When all electrons in the outer valences are shared by more than two atoms making a positive charge, which primary bond is formed?

Metallic bond

It is best to wait until the tooth is dry before selecting the shade of composite to be used.

FALSE

A class II, DO composite has been placed on #30. Which of the following areas should be cured after removing the matrix and prior to finishing/polishing?

Distal buccal/lingual

All of the following are reasons for incremental placement of composites except:

It eliminates polymerization shrinkage.

Curing lights should be checked with a radiometer.

TRUE

Glass ionomers are not good insulators.

FALSE

The thin surface layer on polymerized (cured) composites, which contains unreacted monomers that allow for additional increments to be added, is called the:

Oxygen inhibited layer

Darker shades of composite require longer light curing times. Too much filler can make a composite resin difficult to work with.

Both statements are TRUE

The function of the silane coupling agent in composite resins is to:

Bind the matrix to the filler.

All of the following are benefits of glass ionomer except:

It has greater strength than a composite.

**Benefits: fluoride release, no bonding agent required, & it chemically adheres to the tooth structure.

Direct composite restorations have less polymerization shrinkage than indirect composite restorations because they are molded directly to the tooth upon placement. Indirect composite restorations must be cemented for placement.

The first statement is FALSE, the second statement is TRUE

Resin-modified glass ionomer composites (RMGICs) are more esthetic-like composites but can recharge with fluoride ions in the oral cavity from toothpaste and water and re-release them. This allows for protection against recurrent decay.

Both statements are TRUE

Which of the following restorations would be an ideal use for a compomer?

Class III restoration on #7

The patient does not need eye protection when using a curing light, as the light is in the patient's mouth.

FALSE

The delivery tip of flowable composite syringes can be thrown in the trash.

FALSE

Glass ionomers have greater radiopacity than dentin, making them identifiable on radiographs.

TRUE

Sectional matrix bands come pre-formed and are for class II composites.

TRUE

Your 2 o’clock patient is coming in for a class IV composite on tooth number 9. Which composite material would you not choose?

Macrofill - macrofill composites are difficult to polish & become rough due to rapid wear making them a poor choice for anterior restorations.

Which material chemically bonds to the tooth structure itself without a bonding agent?

Glass ionomers (don't require a bonding agent)

**Nanohybrid composites, compomers, and giomers all require the use of an intermediate bonding agent due to their composite resin contents.

Chemical cure composite resins are self-curing.

TRUE

There is no final impression needed for CAD/CAM restorations. The final restoration can be viewed in 3D to make any adjustments before milling, which can eliminate most errors.

The first statement is FALSE (there is a final impression step in CAD/CAM restorations, but it does not involve retraction cord or impression material).

The second statement is TRUE

It doesn't matter if you do not go through all of the abrasives when polishing ceramics, only that you achieve the desired luster.

FALSE

The ceramic processing technique in which ceramic powder is mixed with a water-based liquid to form a slip and pressed onto a porous refractory die is called:

Slip casting

The ability of ceramics to resist compressive forces is more important than the ability to resist flexural forces.

FALSE

You should have your patients remove lipstick before taking a shade. Use the operatory chair light to ensure the correct shade.

The first statement is TRUE, the second statement is FALSE (The bright light from the operatory light can increase the perceived brightness and decrease the color intensity of the actual shade and should therefore be turned off)

Veneers can be used on premolars to give the appearance of correct alignment.

TRUE

Zirconia restorations can be cemented with glass ionomer cements.

TRUE

The material you should choose when cementing a lithium disilicate or leucite-reinforced ceramic crown is:

Resin cement - All glass-based ceramic restorations should be cemented with resin cement to maintain the esthetic color, as well as to not have a bond stronger than the restoration.

The changing of porcelain from a powder to a solid mass is called:

SINTERING - Sintering is when ceramic particles are heated to the point that they melt and fuse to adjacent particles, changing into a solid mass.

Your patient is coming in for a three-unit bridge on #5-7 and has a problem with bruxism. Which of the following materials would you use?

ZIRCONIA - Zirconia can be used for three-unit bridges and can be used to provide esthetic restorations for bruxers.

All of the following can cause porcelain/ceramic failure except:

Opposing gold restoration - Gold is a softer material than porcelain and will therefore not cause porcelain fracture

Porcelain is fused to metal by which of the following?

Chemical bonding w/ oxides - The metal core forms an oxide layer when it is heated, and when porcelain is applied it chemically fuses to the oxides on the metal, forming a strong bond.

Your patient wants a ceramic crown on #9. Which one would not be an option for this patient?

ZIRCONIA - Zirconia materials are somewhat opaque and are not esthetic choices for anterior teeth

Base metals require more porcelain layers to cover the dark color.

TRUE