Metallic Biomaterials Study guide

Question 1

Two important aspects of identifying a biomaterial to be used in the human body are fuctional performance and ___-

Answer 1

biocompatibility

Question 2

____ are used widely as biomaterials for thier strength and toughness

Answer 2

metals

Question 3

give 3 example of metals used throughout the human body

Answer 3

stainless steel
titanium
colbalt alloys

Question 4

what is the most common type of medical grade stainless steel? Name 3 elements in this type of sS

Answer 4

Stainless steel 316L
Fe 60-65 wt%
Cr 17-19 wt%
Ni 12-14 wt%
C max .03%

Question 5

state three physical properties of metals that make them attractive for their use as a metallic biomaterial?

Answer 5

strength, toughness, malleable-easy to mold, ductile- can draw out into wires for braces etc.

Question 6

What element increases the formation of carbon carbide (Crv23Cv6)?

Answer 6

Carbon

Question 7

name the overall classification of materials that could potential be used as biomaterials

Answer 7

metals, ceramics, composites, polymers

Question 8

Give three examples of materials that can be used as dental metals

Answer 8

amalgam-fill cavities
gold&gold alloy-fill cavities
nitinol-braces (the wire)

Question 9

Which of these metallic biomaterials have the best corrosion resistance? Cobalt alloys, stainless steel, or pure titanium

Answer 9

titanium

Question 10

why is pure gold not useable in dental applications? What is added to make it a better dental biomaterial

Answer 10

it is too soft. platinum is added

Question 11

whi is it advisable to reduce carbon content in medical grade stainless steel?

Answer 11

additional carbon will increase carbon carbide formation… an increase of carbon carbide can impare the formation of surface oxide thus speeding up corrosion rates

Question 12

what is the main advantage of using a titanium alloy in bone as opposed to any other metal?

Answer 12

it has excellent bone bonding

Question 13

what is the purpose of adding tungsten or nickel to cobalt based alloys?

Answer 13

to improve machinablity and frabrication

Question 14

state three reasons why amalgam is preferred as a dental biomaterial

Answer 14

moldable, strong, hardens in time, inexpensive, stable

Question 15

list four metallic implants materials and explain the composition properties and potential applications for one of them.

Answer 15

stainless steel L316 -
stents
Fe 60-65 wt%
Cr 17-19 wt%
Ni 12-14 wt%
C max .03%
easy to manufacture, cheap, high strength and toughness

Titanium Alloy- bone screws
gold- used in teeth
co-Cr Alloy-bone, joint replacement, dental implants

Question 16

define biocompatiblity

Answer 16

the ability of a material to perform with a appropriate hose response in a devise inteded to interact with biological systems

Question 17

what is nitinol?

Answer 17

shape memory alloy. this allows has the ability to return to a predetermined shape when heated. it can be used as wire in braces or even medical staples

Question 18

name 3 medical devices

Answer 18

cardiovascular stent
bone screw
femoral hip stem

Question 19

state two ways in which atoms of metals mix to form alloys

Answer 19

sustitution

interstitial

Question 20

describe shape memory alloys

Answer 20

ability to return to predetermined shape when heated. nitinol is this. used in staples and in wire of braces

Question 21

what is the outer layer that protects a metal from corrosion?

Answer 21

surface oxide

Question 22

although several types of stainless steel are available for implant use in practice the most common is __ stainless steel. This alloy is composed predominantly ___ which makes up approximately 60-65% plus additon of ___, makes up 17-20% of the alloy. additionally approximately 12-14% of the alloy is composed of _____. in order to reduce possiblity of vivo corrosion, only trace amounts less than .03% of ___ are found in the alloy

Answer 22

Fe 60-65 wt%
Cr 17-19 wt%
Ni 12-14 wt%
C max .03%

Question 23

define unit cell as it related to metallic crystal structure

Answer 23

smallest repetitive volume which contains complete lattice patter of a crystal

Question 24

state and describe three types of imperfections/defects in metallic crystal structure

Answer 24

point defect:
vacancy atoms-atom missing
intersitital atom-extra atoms between atomic sites
substitutional atoms-atom replaces another

line defects= dislocations move causing a slip between crystal planes…

Question 25

state and describe two metal fabrication methods

Answer 25

forging- hamering or stamping. part of forming process

casting- mold is filled with metal, most common and cheapest method