adhesion
The chemical attraction between unlike molecules is __?
cohesion
The chemical attraction between like molecules is __?
coefficient of thermal expansion
This index indicates how one material reacts to temperature extremes in relation to another
creep
Slow dimensional changes caused by compression
ductility
The ability to undergo change of form without breaking
Elasticity
A materials ability to recover its intiial shape after undergoing a force
galvanism
An electrical current generated by dissilimia metals in an acidic environment
Gelation
The process of gelling (solidification by cold)
gram
The volumetric weight of one cubic centimeter or millimeter of water
Imbibition
Absorption of a solvent by a gel
malleability
A materials capacity to be shaped by force or pressure
microleakage
Pass of oral fluids/bacteria into and out of tooth structure due to marginalgap or failure of marginal (restorative) seal
percolation
microleakage is also known as __?
polymerization
The linking, branching, or cross linking of smaller molecules
proportional limit
The force at which a material cannot return to its original shape
syneresis
Contraction of a gel due to the loss of a solvent
tensile strength
The force needed to stretch a material to the point of fracture
viscosity
Resistance to flow
amalgam
An alloy of mercury with silver, copper, tin and zinc
to minimize corrosion
Why is copper added to amalgam?
silver
Which base metal in amalgam is susceptible to corrosion?
1. durable
2. similar compressive strength to enamel
3. relatively inexpensive
Desirable features of amalgam are:
coarse to fine
When polishing amalgams, it is important to move from __ to __ agents.
with tin oxide
Final polish of an amalgam in the mouth is __?
1. Using a proper place band and wedge
2. Detecting overhang with explorer
Avoid overhang formation by __?
properties
If you change a material's components then you change it __?
15-20 second etch
rinse
dry
apply
air-thin
polymerize
The steps for applying a bonding agent are:
fiber optic light
Polymerization in bonding is typically activated how?
saliva or oils
The most common failures from bonding are caused by what?
Bonding agent (like 4 sealants) bisphenol a-glycidyl methacrylate
What is BIS-GMA
pit and fissure sealants
This is a barrier used to protect the occlusal surfaces of teeth from bacterial assault by sealing anatomically unprotected tooth structure with resin.
1 pumice, rinse, isolate, etch, rinse, dry, apply, polymerization
2. re etch if enamel lacks the frosty look
3. retention is mechanical
Steps for applying a sealant
mechanical
Retenion of a pit and fissure sealant is __?
composite
This is an esthetic restorative material composed of a bonding agent and tooth-colored filler particles of various sized
silicates
quartz
glass
What are the most common filler particles for composite retorations?
high polishability and ease of handling but require tooth support
Microfill for composites are popular why?
combined strength and beauty
Hybrid filler for composites are popular why?
increase surface area and therefore bond strength, also polishability
Nanofills for composites are good why?
tin oxide or diamond polish paste NEVER coarse pumice
When polishing a composite always use __?
liners
These are generally used to seal dentin or medicate the dental pulp
1. varnish
2. calcium hydroxide
3. Zinc oxide
4. Resin modified glass ionomer
Types of liners include:
resin modified glass ionomer
The preferred liner in modern day is __?
bases
These are generally used to provide thermal insulation or mechanical protection for the dental pulp
base
Cements are typically considered what type of material?
cements
These are used to affix a restoration to a tooth structure or as a base.
zinc phosphate
This cement releases heat when mixed (exothermic), causes mechanical interlock between tooth and casting.
Polycarboxylate
This cement has a high chemical affinity for enamel and is a powder mixed with polyacrylic acid.
Glass Ionomer
This cement binds to dentin, releases fluoride, can be used as a Class V restorative material and its coefficient of thermal expansion approximates actual tooth structure.
Resin
This cement is tooth colored for restorations and ortho applications and is also used for luting etched metal retainer such as resin-bonded bridges and prefab endo posts
Hybrid
This cement is redin modified glass ionomers. It seals dental effectively which minimizes sensitivity and also releases fluoride.
ZOE or Zinc oxide/eugenol
This cement is commonly used for temp cementing, its putty like consistency works well for a temp restoration. Orange solvent is used to clean instruments contaminated with this cement type.
Rigid
Flexible
The types of impression materials are:
Aqueous
Nonaqueous
Flexible impression material can be broken down into which types?
flexibility
Elastometric means __?
1. Plaster
2. Compound (border mold custom tray)
3. Zinc Oxide/ Eugenol (final impression, full denture)
Rigid inelastic impression materials include:
Hydrocolloid:
*alginate: non-reverisible
*agar: reversible because it gels based on temp
Flexible aqueous (elastometric) impression material includes:
1. Polysulfide rubber
2. Polyether Rubber
3. Silicone Rubber
4. Vinylpolysiloxane
Flexible non-aqueous impression materials include:
messy smelly and must be poured up the same day
The thing to remember about Polysulfide rubber is?
Unstable in the presence of moisture! It is somewhat ridgid, good tissue detail
The thing to remember about Polyether Rubber is?
Rarely used, putty like
The thing to remember about Silicone Rubber is?
Tasteless, odorless, stable, strong, accurate, easily mixed, capable of multiple pours
The thing to remember about Vinylpolysiloxane is?
according to manufacturers guidelines
The mixing time for impressions materials vary how?
mineral, calcium sulfate di-hydrate
Gypsum products are made of?
wax patterns, models and occlusal impressions
What are gypsum products used for?
it expands
What happens to gypsum as it sets?
Made of Beta-calcium
Porous
Undergoes HIGH-setting expansion (ie needs more water)
It has LOW compressive strength overall
Characteristics of stone (Type II gypsum) are?
Made from alpha-calcium
Less porous
Undergoes LOW-setting expansion (needs less water)
Has a HIGHER compressive strength
Characteristics of plaster (Type III gypsum) are?
Made from alpha-calcium
Has the HIGHEST compressive strength
Has additive to make it more durable and wear resistant
Characteristics of Diestone (Type IV Gypsum) are?
greater expansion and less strength
More water in gypsum leads to __?
plaster (easy to polish)
Which impression material would you use for an Orthodontic model?
stone (more accurate and wear resistant)
Which impression would you use for a study/working model?
Diestone (accurate and most wear resistant)
Which impression would you use for a crown and bridge model?
perpendicular
The model base of a gypsum product should be trimmed ___ to the midline between the central incisors
1. inlay and casting wax for cast restorative patterns
2. baseplate wax for removable prothetics
3. Bite registration
4. Boxing wax for pouring models
5. sticky wax for attaching models
6. Utility wax for adjusting the shape of impression trays and to cus
Some ways waxes are used in Dental Materials are?
fabricating inlays, onlays, crowns and bridges
Casting alloys are used for __?
noble metals
Precious alloys contain __?
base metals
Nonprecious alloys contain __?
1. gold
2. platinum
3. palladium
Examples of noble metals used in casting alloys are:
silver
copper
nickel
tin
zinc
Examples of base metal used in casting alloys are:
tin oxide
Intraorally, gold may be polished with?
rouge
Extra orally gold may be polished with?
24 karat
1000 fine gold =
These metals resist tarnish and corrosion
Precious noble
These metals may be allergenic (causing ginigval inflammation)
non-precious base
Implant
This is a bio-compatible titanium alloy prosthesis used to replace missing teeth
mobility due to a lack of osseointegration or inadequate bone
The leading cause of implant failure is __?
1. inadequate bone
2. uncontrolled perio
3. smoking
4. infection
Contra-Indications for implant placement include:
yes
Can an implant patient use an electric toothbrush?
1. NO metal except titanium or graphite
2. Air polisher OK
Which materials can be used with implant patients?
pyrophosphates
The active ingredient in tartar control toothpaste is?
pyrophosphate
The leading cause of dentinal hypersensitivity is __?
triclosan (antimicrobial)
The active ingredient in gum care toothpaste is?
postassium nitrate, sodium citrate and strontium chloride
The active ingredient (s) in desensitizing toothpaste is/are?
carbamide peroxide or hydrogen peroxide
The active ingredient in whitening toothpastes is?
pits and fissures
According to GV Blacks classification of caries a CLASS I includes which areas?
posterior proximals
According to GV Blacks classification of caries a CLASS II includes which areas?
anterior proximals
According to GV Blacks classification of caries a CLASS III includes which areas?
anterior proximals that involve the incisal surface
According to GV Blacks classification of caries a CLASS IV includes which areas?
facial or lingual at the gingival 1/3
According to GV Blacks classification of caries a CLASS V includes which areas?
cusp tip and/or incisal edge
According to GV Blacks classification of caries a CLASS VI includes which areas?
1. The smaller the particle size, the easier to mix, place and finish
2. Thicker is quicker
3. more filler, more strength
4. cold slows
5. less water = more strength
6. Plaster < stone < diestone
7. Contamination by saliva - ruins everything!
Kerrs Rules of Thumb =
hardness
The Brinnell and Knoop Test are used in determining?
BIS-GMA resin
The main ingredient in sealant material is __?
may bend without breaking
If a material is considered to be highly ductile, it: