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
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
3
Q
pulp
A
- provides nutrients to dentin
- responds to stimuli with pain/sensitivity
4
Q
periodontium
A
- supports tooth in stale but dynamic position
- provides feedback regarding force on tooth
- includes pdl, cementum, alveolar bone
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
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
7
Q
class I medical device
A
- least regulated
- only good manufacturing practices are required
ex. prophy paste, brushes
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
9
Q
class III medical device
A
- most regulated
- require pre-market approval
ex. bone graft materials
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)
11
Q
dental impression
A
- negative copy
- filled with material to form replica or positive copy
12
Q
cast
A
if restoration is constructed on replica
13
Q
study model/diagnostic cast
A
if resulting replica is used to study size/position of oral tissues
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
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
16
Q
dental materials can be classified by:
A
- use
- location of fabrication
- longevity of use
17
Q
direct restorative materials
A
- restorations constructed directly in the oral cavity
- include amalgam, composite, glass ionomers
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
19
Q
composite
A
- esthetic materials that polymerize in mouth
- supplied as pastes and set by chemical reaction
20
Q
glass ionomers/other cements
A
-mortal-like materials set by acid-base chemical reaction in mouth and resemble tooth material
21
Q
indirect restorative materials
A
- must be fabricated outside the mouth because the processing conditions would harm oral tissues
- include gold, ceramic, polymers
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
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
24
Q
indirect restorative polymers
A
- plastics typically processed or cured at elevated temperatures and under high pressures
ex. pink “gingival” portion of denture
25
permanent restorations
fillings, crowns, bridges, dentures
26
temporary restorations
aka provisional restorations, planned to be replaced in short time, ex. temp crown while permanent crown is being made in lab
27
interim restoration
long term temp restorations, ex. fractured tooth needs crown but is undergoing orthodontic treatment may have large composite restoration until crown can be made
28
class I lesion
pits and fissures of posterior teeth
29
class II lesion
just below interproximal contacts in posterior teeth, commonly seen in radiographs
30
class III lesion
interproximal caries in anterior teeth, radiographs and exam commonly used to diagnose
31
class IV lesion
caries incisal angle of anterior tooth, also restorations used to restore due to fracture/trauma
32
class V lesion
gingival third of facial/lingual of anterior and posterior teeth, susceptible to caries with poor hygiene and high sugar
33
class VI lesion
cusp tip or incisal edge of tooth, quite rare, attrition can lead to "dished out" area of worn dentin
34
phases
commonly classify materials into one of three phases: solid, liquid, or gas
35
gases
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
liquids
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
solids
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
primary bonds
strong bonds between atoms that involve the transfer or sharing of electrons between atoms
39
ionic bonds
result of an electron being given up by one atom and being accepted by another
40
covalent bonds
result of two atoms sharing a pair of electrons
41
metallic bonds
similar to covalent bonds in that valence electrons are shared between atoms; metals are good conductors of electricity and heat
42
secondary bonds
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
permanent dipole
permanent partial charge
44
hydrogen bonds
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
fluctuating dipole
weak bonds
46
metals
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
ceramics
atoms of ceramic material are bonded with ionic bonds; strong but brittle
48
polymers
composed of long chains of covalently bonded repeating units
49
cross-linking
the linking of one coil (or polymer chain) across to another with wire (or a covalent bond)
50
composites
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
colloids
two-phase materials, mixtures of gases, liquids, or solids at microscopic level; suspensions of one another
52
emulsions
type of colloid composed of two liquids that don't blend together to form one liquid; ex: oil and vinegar
53
impression materials
used to make replicas of teeth and other oral tissues
54
study model
used in diagnosis and treatment planning
55
cast
replica for prep of restoration or appliance
56
die
replica of single tooth
57
impression trays
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
stock trays
"off the shelf" trays designed to take impressions of different oral conditions, can be metal or plastic
59
custom trays
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
bite-registration trays
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
triple tray
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
viscosity
measure of a liquid's ability to flow; they are light, medium, monophase, heavy and putty.
63
retraction cord
placed in gingival sulcus to facilitate crown and bridge impressions, pushes gingiva away from tooth; will frequently contain hemostatic med to control bleeding
64
types of impression materials
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
plaster
rarely used but still sold, has same setting and properties as gypsum products
66
wax
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
impression compound
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
zinc oxide-eugenol (ZOE)
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
alginate
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
agar
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
polysulfide
set via condensation polymerization reaction; supplied as two pastes; used to make impressions of crowns, bridges
72
condensation silicone
hydrophobic, difficult to pour without voids/bubbles, must be poured without delay, not popular to use today
73
polyether
set via ring-opening polymerization shrinkage; shorter working times, very accurate, easy to pour
74
addition silicones
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
gypsum products
made from gypsum rock; calcium sulfate dihydrate
76
plaster
first gypsum product, weak, inexpensive
77
stone
made from gypsum by carefully controlled calcination
78
high strength or improved stone
also made from gypsum by calcining the gypsum but in calcium chloride solution, strongest, most expensive
79
water-powder ration
proportion of water to powder
80
working time or initial setting time
length of time from start of mix until the setting mass reaches a semi-hard stage
81
final setting time
length of time from start of mix until the setting mass becomes rigid and can be separated from the impression
82
wet strength
strength measured when the sample contains some or all of the water in excess of the theoretical amount required for hydration
83
dry strength
strength measured when the excess water is not present in the sample, may be 2 or more times the wet strength
