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dental materials > Ch. 1, 2, 8, 9, 20, 27, 30 > Flashcards

Ch. 1, 2, 8, 9, 20, 27, 30 Flashcards

1
Q

enamel

A
  • hard, wear-resistant surface material
  • resists compressive forces of biting
  • weak in resistance to bending/other forces that occur when food is ground by molars
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2
Q

dentin

A
  • makes up bulk of tooth
  • acts as cushion for brittle enamel
  • provides strength to resist complex forces that occur when biting
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3
Q

pulp

A
  • provides nutrients to dentin

- responds to stimuli with pain/sensitivity

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4
Q

periodontium

A
  • supports tooth in stale but dynamic position
  • provides feedback regarding force on tooth
  • includes pdl, cementum, alveolar bone
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5
Q

gingival tissue

A
  • seals out noxious agents of oral cavity
  • prevents chemicals and microbes from gaining access to periodontium and deeper tissues
  • forms barrier
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6
Q

restrictions on materials use

A
  • biting forces that may fracture teeth and replacement material
  • degradation of materials, teeth
  • temp changes
  • biocompatibility (lack of harmful effects to patient)
  • esthetic demand
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7
Q

class I medical device

A
  • least regulated
  • only good manufacturing practices are required
    ex. prophy paste, brushes
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8
Q

class II medical device

A
  • gain approval from FDA after being shown to be equivalent to other products
  • meets ADA’s seal of acceptance program
    ex. composite and amalgam
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9
Q

class III medical device

A
  • most regulated
  • require pre-market approval
    ex. bone graft materials
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10
Q

bridge

A
  • replaces lost tooth or teeth
  • also called fixed partial denture
  • supported by an actual tooth called an abutment
  • each abutment tooth is prepared and restored with a crown called a retainer
  • the missing tooth is replaced with a fake tooth called a pontic (only crown portion is replaced)
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11
Q

dental impression

A
  • negative copy

- filled with material to form replica or positive copy

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12
Q

cast

A

if restoration is constructed on replica

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13
Q

study model/diagnostic cast

A

if resulting replica is used to study size/position of oral tissues

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14
Q

luting agents

A
  • aka dental cements
  • glueing two objects together
  • after mixing cements must flow like a thin liquid so that a crown will fit properly
  • several min. after setting, cement is expected to be strong and insoluble in oral fluids
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15
Q

bases/liners

A
  • cements
  • protects pulp from irritating materials
  • serves as insulating layers under metal restorations, can reduce sensitivity
  • base implies degree of strength and insulation, greater bulk, serves to restore part of tooth and provide thermal insulation
  • liner is thin layer of material painted on to protect underlying dentin
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16
Q

dental materials can be classified by:

A
  • use
  • location of fabrication
  • longevity of use
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17
Q

direct restorative materials

A
  • restorations constructed directly in the oral cavity

- include amalgam, composite, glass ionomers

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18
Q

amalgam

A
  • metallic material that is formed by combining liquid mercury with powdered metals
  • placed directly in cavity prep, carved to resemble tooth, then hardens
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19
Q

composite

A
  • esthetic materials that polymerize in mouth

- supplied as pastes and set by chemical reaction

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20
Q

glass ionomers/other cements

A

-mortal-like materials set by acid-base chemical reaction in mouth and resemble tooth material

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21
Q

indirect restorative materials

A
  • must be fabricated outside the mouth because the processing conditions would harm oral tissues
  • include gold, ceramic, polymers
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22
Q

gold crowns/inlays

A

-made by melting metals and pouring (forcing) them into molds of the exact size and shape needed for each patient

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23
Q

ceramic materials

A
  • processed by a number of techniques
  • many times a ceramic powder is fired at a high temp and becomes solid object
    ex. porcelain crown
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24
Q

indirect restorative polymers

A
  • plastics typically processed or cured at elevated temperatures and under high pressures
    ex. pink “gingival” portion of denture
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25
Q

permanent restorations

A

fillings, crowns, bridges, dentures

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26
Q

temporary restorations

A

aka provisional restorations, planned to be replaced in short time, ex. temp crown while permanent crown is being made in lab

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27
Q

interim restoration

A

long term temp restorations, ex. fractured tooth needs crown but is undergoing orthodontic treatment may have large composite restoration until crown can be made

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28
Q

class I lesion

A

pits and fissures of posterior teeth

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29
Q

class II lesion

A

just below interproximal contacts in posterior teeth, commonly seen in radiographs

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30
Q

class III lesion

A

interproximal caries in anterior teeth, radiographs and exam commonly used to diagnose

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31
Q

class IV lesion

A

caries incisal angle of anterior tooth, also restorations used to restore due to fracture/trauma

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32
Q

class V lesion

A

gingival third of facial/lingual of anterior and posterior teeth, susceptible to caries with poor hygiene and high sugar

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33
Q

class VI lesion

A

cusp tip or incisal edge of tooth, quite rare, attrition can lead to “dished out” area of worn dentin

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34
Q

phases

A

commonly classify materials into one of three phases: solid, liquid, or gas

35
Q

gases

A

atomic bonds are very weak; easily broken by normal microscopic vibrations of atoms at room temp; will take on 3d shape of container they fill; if thermal energy is removed by cooling, gases condense into liquids

36
Q

liquids

A

have stronger attractions but not strong enough to carry a load or maintain shape without support; attraction between molecules results in short-range order which is a consistent spatial relationship among atoms or molecules 5-10 neighbors apart; other characteristics of a liquid are vapor pressure, boiling temp, viscosity, and surface tension

37
Q

solids

A

exhibit strongest attraction; atomic bonds of solids maintain the shape of objects and resist external forces placed on them; solids can be crystalline or amorphous; crystalline solids have a consistent spatial relationship of atoms or molecules repeated hundred to thousands of times called long-range order; distances and angles are uniform; ex: table salt, diamonds, hydroxyapatite of teeth; crystalline solids have both short-range and long-range order; amorphous have same atomic bonds but only have short-range order, much like liquids

38
Q

primary bonds

A

strong bonds between atoms that involve the transfer or sharing of electrons between atoms

39
Q

ionic bonds

A

result of an electron being given up by one atom and being accepted by another

40
Q

covalent bonds

A

result of two atoms sharing a pair of electrons

41
Q

metallic bonds

A

similar to covalent bonds in that valence electrons are shared between atoms; metals are good conductors of electricity and heat

42
Q

secondary bonds

A

aka van der waals forces; result of partial charges from an uneven distribution; can be temporary or permanent, weak or strong; important in determining the properties of polymers because they determine the interaction of the polymer chains and thus the properties of the polymer itself.

43
Q

permanent dipole

A

permanent partial charge

44
Q

hydrogen bonds

A

special case of permanent dipole; hydrogen atom contains only one electron, when it is pulled away from nucleus by greedy atom, the nucleus is left partially unshielded

45
Q

fluctuating dipole

A

weak bonds

46
Q

metals

A

held together with metallic bonds; most metals have bonds that are predominantly metallic but that also show some covalent or ionic tendency; metal can be bent- atoms slide against each other

47
Q

ceramics

A

atoms of ceramic material are bonded with ionic bonds; strong but brittle

48
Q

polymers

A

composed of long chains of covalently bonded repeating units

49
Q

cross-linking

A

the linking of one coil (or polymer chain) across to another with wire (or a covalent bond)

50
Q

composites

A

materials that are made of two or more different materials; common composites are mixes of a polymer and a ceramic; ex: sporting goods; what one material lacks the other compensates for

51
Q

colloids

A

two-phase materials, mixtures of gases, liquids, or solids at microscopic level; suspensions of one another

52
Q

emulsions

A

type of colloid composed of two liquids that don’t blend together to form one liquid; ex: oil and vinegar

53
Q

impression materials

A

used to make replicas of teeth and other oral tissues

54
Q

study model

A

used in diagnosis and treatment planning

55
Q

cast

A

replica for prep of restoration or appliance

56
Q

die

A

replica of single tooth

57
Q

impression trays

A

used to carry the impression material into the mouth, handle is used to remove impression; plastic ones good for infection control and inexpensive; metal trays more expensive but reusable and stiffer

58
Q

stock trays

A

“off the shelf” trays designed to take impressions of different oral conditions, can be metal or plastic

59
Q

custom trays

A

makes most accurate impressions; made on a model of the patient’s arch with acrylic or other resin; two impressions are necessary, preliminary impression is taken with stock tray and inexpensive material then a gypsum product is poured into impression and the resulting model is used to construct the custom tray, then the custom tray is used to take a final impression; used for full dentures, some partials, inlays, crowns, bridges

60
Q

bite-registration trays

A

type of special-use tray; records occlusal surface of both arches, used to relate upper and lower casts in dental lab in precise manner as they come together in patient’s mouth

61
Q

triple tray

A

type of special-use tray; used with dual-arch or closed-mouth impression technique; is a quadrant tray with a “J” shape that curls around posterior of most distal molars

62
Q

viscosity

A

measure of a liquid’s ability to flow; they are light, medium, monophase, heavy and putty.

63
Q

retraction cord

A

placed in gingival sulcus to facilitate crown and bridge impressions, pushes gingiva away from tooth; will frequently contain hemostatic med to control bleeding

64
Q

types of impression materials

A

inelastic: plaster, wax and impression compound, zinc oxide-eugenol (ZOE)
aqueous elastomeric: alginate (irreversible hydrocolloid), agar (reversible hydrocolloid)
nonaqueous elastomeric: polysulfides, condensation silicones, polyethers, addition sillicones

65
Q

plaster

A

rarely used but still sold, has same setting and properties as gypsum products

66
Q

wax

A

first impression material used in dentistry, cheap/clean/easy, comes in many forms like sticks, strips, tubes; low molecular weight, thermoplastic, also very weak, sometimes used to take impressions for full dentures, often used as tray extender; is softened or melted then formed into the desired shape of a restoration

67
Q

impression compound

A

wax with added filler to improve handling and stability, is stronger and more brittle, supplied as sticks or cakes of material, is softened in warm water bath, low thermal conductivity thus time/patience required to soften material; is placed in impression tray, resoftened, then seated in mouth; when it has cooled to room temp it returns to rigid state and is removed

68
Q

zinc oxide-eugenol (ZOE)

A

comes as two pastes; one paste contains eugenol and inert fillers, the other is formed by using zinc oxide powder mixed with vegetable oil; smells/tastes like cloves; set to a hard and brittle mass which limits their use to impressions of edentulous ridges for removable dentures

69
Q

alginate

A

irreversible hydrocolloid; supplied as powders that are mixed with water; powder contains potassium alginate, forms a sol. advantages include fewer air bubbles, and pouring is easier because its composed of water. disadvantages is that water evaporates if left exposed to air and then it shrinks.

70
Q

agar

A

reversible hydrocolloid; comes premixed in semisolid tubes/sticks; prep requires three baths; advantages: works well in wet environment. disadvantages: require special equipment for heating/cooling, and poor tear strength

71
Q

polysulfide

A

set via condensation polymerization reaction; supplied as two pastes; used to make impressions of crowns, bridges

72
Q

condensation silicone

A

hydrophobic, difficult to pour without voids/bubbles, must be poured without delay, not popular to use today

73
Q

polyether

A

set via ring-opening polymerization shrinkage; shorter working times, very accurate, easy to pour

74
Q

addition silicones

A

most popular especially for crown/bridges, most accurate, stable, and expensive materials, are supplied in as many as 5 viscosities, also supplied via automix gun

75
Q

gypsum products

A

made from gypsum rock; calcium sulfate dihydrate

76
Q

plaster

A

first gypsum product, weak, inexpensive

77
Q

stone

A

made from gypsum by carefully controlled calcination

78
Q

high strength or improved stone

A

also made from gypsum by calcining the gypsum but in calcium chloride solution, strongest, most expensive

79
Q

water-powder ration

A

proportion of water to powder

80
Q

working time or initial setting time

A

length of time from start of mix until the setting mass reaches a semi-hard stage

81
Q

final setting time

A

length of time from start of mix until the setting mass becomes rigid and can be separated from the impression

82
Q

wet strength

A

strength measured when the sample contains some or all of the water in excess of the theoretical amount required for hydration

83
Q

dry strength

A

strength measured when the excess water is not present in the sample, may be 2 or more times the wet strength

dental materials (6 decks)

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