Materials Chapter 16 & 25

Question 1

What is abrasion?

Answer 1

the wearing away of a tooth surface by grinding (of a cutting instrument)

Question 2

What is finishing?

Answer 2

the precess that produces the final shape of the restoration, a bur is used

Question 3

What is polishing?

Answer 3

the process of abrading the surface of a restoration to eventually reduce the size of the scratches until the surface appears shiny

Question 4

Define abrasive.

Answer 4

the material doing the wearing or abrading

Question 5

What is tribology?

Answer 5

the science of interacting surfaces in motion.

Involves the principle of friction, lubrication and wear

Question 6

Explain two-boy versus three-body tribology.

Answer 6

In the 2 body, the abrasive agent is affixed to a wheel, bur or a rubber cup. (no polishing paste is necessary with this system). In the 3 body, abrasive particles move in a space between the surface being polished and the application device. (rubber cup, prophy paste, and tooth).

Question 7

What is chalk?

Answer 7

Chalk-is a mineral form of calcite. It is also called whiting or calcium carbonate. It is a mild abrasive, used to polish teeth, gold, amalgam and plastic restorations.
Pumice is a silica-like volcanic glass. Used on enamel, gold, amalgam, and acrylic dentures. Pumice stone to scrub calloused heels.

Question 8

What types of abrasives are sand, cuttle, garnet and emery?

Answer 8

Different grades of sandy-type materials.

They are all mostly bonded to a paper disc and used for different circumstances.

Question 9

What type of abrasive is silex?

Answer 9

like quartz and is supplied in powder form then mixed with water to form a paste

Question 10

What type of abrasive is tin oxide?

Answer 10

it is in the form of white powder and is mixed with water to form a paste

used as a final polishing agent amalgam restorations

Question 11

What abrasive replaced emery?

Answer 11

Aluminum oxide. It is used in the form of a disc or strips or in rubber wheels and points which are used to adjust or finish or polish enamel or ceramics.

Question 12

List the different types of bonded and coated abrasives.

Answer 12

1. Diamond burs
2. Stones
3. Rubber wheels or points
4. Rubber cups
5. Disks or strips
6. Powders

Question 13

What type of abrasive has diamonds bonded to the shaft of a bur?

Answer 13

diamond bur

Question 14

What type of abrasive is used mainly in the dental lab?

Answer 14

stone

Question 15

What type of abrasive tool is impregnated with an abrasive material?

Answer 15

rubber wheels or points

Question 16

What type of tool has abrasive agents embedded in the cup?

Answer 16

rubber cup

Question 17

What has abrasive particles bonded onto the strips or discs?

Answer 17

disks or strips

Question 18

What needs water or glycerin to create a paste?

Answer 18

powders

Question 19

What are factors affecting the rate of abrasion?

Answer 19

1. Hardness- stronger than the surface being abraded
2. Size- GRIT
3. Shape- spherical is LESS abrasive
4. Pressure- this increases temperature
5. Speed- increases temperature
6. Lubrication- water is most common

Question 20

Why do we polish?

Answer 20

to reduce adhesions

to remove stain

to reduce corrosion on metal materials

polishing removes the acquired pellicle