reading stuff Flashcards
What is the best consideration for a tooth significantly weakened by extensive defects, especially in areas of heavy occlusal function where esthetics are a primary concern and why?
Ceramic onlays, crown, PFM crown
Bonds to tooth so good
What determines the lifespan of an esthetic restoration?
Nature and extent of initial caries Treatment procedure restorative materials and technique used Operator skill Patient factors (oral hygiene, occlusion, caries risk, adverse habits)
common reasons for failure of composites
Trauma
Improper prep
inferior matierals
Improper use
True or False: Composites can be used in almost any tooth surface or any kind of restorative procedure.
True
True or False: The ability to bond relatively strong material of composite to tooth structure (enamel and dentin) results in a restored tooth that is both well sealed and possibly regains a portion of its strength.
True
what kind of restoration is a fused (baked) Feldspathic porcelain inlay
Indirect ceramic restoration
benifit of CAD/CAM chairside ceramic restoration
eliminates need for impressions and temporary restoations
no ned for lab procedures and costs
less appointments
Types of Esthetic restorative materials
Ceramic inlays and onlys
Silicate Cement
Acrylic resin
Composite
what was the first translucent restorative material
Silicate cement
how long does silicate cement last in anterior teeth restorations
4-10 years
what lead to the belief that enamel adjacent to silicate cement was more resistant to caries
High fluoide content and solubility
what is the contempory versions of Silicate Cement
GIs (less soluble though)
how is Silicate cement made
Powder (acid-soluble glass)
Liquid (Phosphoric acid, water, and buffering agent)
How does Acrylic Resin cure
Self curing
problem with curing acrylic resin
Poor activator systems
high polymerization shrinkage
high linear coefficent of thermal expansions
lack of wear resistance (leakge, pulp injury, recurrent carries, color change, excessive wear)
when is acrylic resin not indicated
High stress areas (low strength and flowing under load)
when is acrylic resin used
temporary restorations esthetic veneer on facial of class 2 and IV
what is a composite
Polymeric resin matrix with inorganic fillers
roll of inorganic fillers in composite
Enhance physical properties (strength and reduce thermal expansion)
what is done to increase bond strength between organic matrix and inorganic filer in composites for increased mech properites
coat filler w/ silane coupling agent (increase strength, solubility and water absorption)
Macrofill composites
Convensional composites with 75-80% inorganic filler (8 micrometers) by weight
Characteristics of macrofill composites
rough surface texture
easily stained
resin matrix wears faster than filler
what makes up microfill compoistes
35-60% inorganic filler(.01-.04 micrometers of colloidal silica parties) by weight
use of macrofill today
Not used
properties of microfill composites
smoother (less stain)
less filler (inferior physical and mech properties)
highly wear resistant
low modulus of elasticity (flexes with the tooth)
what is hyride composites
75-80% inorganic filler by weight (microfiller and smaller filler particles)
why was hybrid composites made
Combine physical and mech of macro and smooth surface of micro
benifit of nanofill composite
Highly polishable (.005-.01 micrometer)
popular composite types
Nanofill and nanohybrid
why was packable composite made
easier restoration of proximal contact( increased viscosity makes marginal adaptation difficult
similar to handle like amalgam
(never reached these goals
where should floable composite never be placed
high occlusal or proximal stress (low filler so weak)
what acid is used with conventional GI
Polyacrylic acid (less soluble)
what is good for root surface acries
Conventional GI
when to use Conventional GI
in patients with high caries activity
non occlusal
permanent cementation of crowns
why was RMGI made
improve physical properrties of GI
properties of RMGI
resin makes it light curring also autocurring
easier to use
better strenth, resistance, and esthetics
when is RMGI usually used
Class V in adult with high risk class I and II for primary teeth no requiring long term service
what are compomers
composites with some GI components
LInear Coefficient of thermal expansion
Rate of dimensional change of material per unit change in temperature
How does Composite Linear coeffieicnt of thermal expansion differ from a tooth
3x tooth LCTE
How to decrease the negative effects of LCTE
bond composite to etched tooth surfcace
water sorptions
amount of H2O material absorbed over time
how to decreased water sorptions
increase filler
what has better wear resistance composite or amalgam
Amalgam
where is smoothness needed for composite
close to gingival tissues for heath
what has the smoothest surface
Microfill (nanohybrid and nanofill also good)
why is radiopacity important
so recurrent caries around or under restoration can be seen easily on the radiograph
modulus of elasticity
stiffness (higher means more stiff
pros and cons of low modulus of elastisity
allows bending of restoration with tooth, protecting interface
lower mech and physical properites
solubility of composites
like none
how to minimize effects of polymerization shrinkage
load in steps
using adhesives
using RMGI before composite to reduce microleakage and gap fomation
when is shrinkage of composites a problem
at the root surface (force of polymerization >initial bond)
configuartion factor
ratio o bonding surface to undbonded surfaces
greater configuration factor means
greater potentional for bond disruption via polymerization
pros and cons of self cured composites
greater risk for air inclusions
working time restricted
color instability
direction of polymerization generally centralized for better marginal adpatation and prevention of microleaks
pros and cons of Light cure
increased working time
less finishing time
better color stability (better bonding, improved properties
more success and economical
INdications of composite
CLASS i-vi Core buildups sealants and preventative rstorations parital and full veneers tooth contour mods diastema closure cements temporaries Perio splinting
contraindications of composites
bad isolations
all the occlusaion on the restorative material
restorations with extensions on the root surface
advantage of composites
esthetics conservative less complex preps insulating to heat bond to tooth repairable
disadvantage of composites
gap formation on the root more costly and time consuming technique sensitive isolation LCTE
True or False: If a void is detected immediately after insertion of composite but before contouring, more composite can be added directly to void area
True: must re-etch though
cause and solution of white line adjacent to halo
trama during contouring or finishing, inadequat ethcin, excessive polymerizations
re-etch, prime and bond, being ldightly, leaving a monitor for leaks
where is the exchange zone
over the chest under the chin
should the operator move eyes during tool exchange
No
Goal of isolation
Moisuter control
retraction and access
harm prevention (spray from handpiece can alarm patient)
benifits of the rubber dam
Dry, clean field acess and visibility improved properties of dntal materials protects patients and operator efficiency (patient doesn't talk or get in the way)
when to not use a rubber dam
teeth have no erupted sufficiently
3rd molars
badly malpositioned teeth
can’t breath through nose
thin vs thick rubber dams
Thin: easier to place thick: better retracting gingiva and more tear resistant (class V)
what side of the rubber dam should be used
the dull side (less reflective)
what should be done after the rubber dam is removed
massage gingiva to increase blood flow
how should retainers be placed on children
More gingivally due to short clinical crown
what retainers are used in priamry and young permant teeth
27: primary
w14: perminant
what drug is rairly used to decrease salivary flow when not using a rubber dam
Atropine
characteristics of air rotary power cutting instruments
head is smaller, weigh less, have more vibration
characteristics of electric rotary power cutting instruments
cut with higher torque and little stalling, high-precision cutting, higher initial expense and the weight and balance of it will confuse older clinicians, quieter and smoother cutting
low speed handpiece
12,000 rpm ( for cleaning, caries, finishing and polishing
high speed handpiece
200,000 rpm (preps and removal of old restoration
the part of the handpiece that goes into the rotary instrument
Shank
the cutting part
Head
negative rake angles
rake face ahead of radius of bur
possitive rake angles r
rake face behind the radius of the bur
rake angle
the angle between the rake face and the axis of bur
edge angle
the angle between the rake face and the clearnace face
clerance angle
the angle between the clearance face and the cut surface
the rake face
the face of the bur that does the cutting
the clearance face
clears chips (right after the rake face)
roll of Silicate glass particles in a composite
mech reinforement
light transmission and scattering (esthetics)
roll of acrylic in composoites
fluid and moldable
roll of the matrix phase of a composite
adapt to tooth prep
penetrate into micromech spaces of the etched enamel or dentin
what are bonding systemes made of
unfilled acrylic monomer mixes
what does a sbonding system do
fomrs a 1-5 micrometer film on etched surfaces to interlock mechanically to seal walls and co polymerizes with compsoite restorative material that fills the tooth prep
what is unfill sealance
unfilled acrylics (2% filler modified sealants)
pros and cons of high filler content
high filler improves all properties but fluidity
75% silica by weight is how much by volume
50%
for hybrid composites how are they named
named based on the largest filler in them
when is a composite homogeneous
when it consists of filler and uncured matrix
when is a composite heterogeneous
also has precurred composite and unusual filler
when is a composite modified
has novel filler modifications
how do heterogeneous microfills work
precured particles chemically bond to the new material
how is collloidal silica made
chemically precipitated from a liquid solution as amorphorus particles
how is pyrogenic silica made
precipitated from gaseous amorphous microfillers
what happens to light output as you decrease the fiber optic tip size
the light output decreases
how much will the pulp have to increase in temp for ti to die
5-8 degrees celcius
what causes curing light to scatter
filler particles
what absorbs more light, darker or lighter colorants
darker absorbs more
how much composite normal goes from monomer to polymer
55-65%
what leads to higher stress light composites or autocurred
light (higher energy curing light makes the problem bigger in addition to higher filling)
when would you want low and high elastic modulus
low: more retention
high: MOD to prevent tooth bending
CFA wear
wear due to food and not teeth usually found on small occlusal preps
what is CFA wear resistance related to
filler spacing not composite mech strength(microprotection)
Microprotection
when filler is close together so it protects the resin from wearing
what does color matching consist of
current colors and colors over the course of tie
should the tooth be wet or sry when color matching
wet (if dry will look too wet)
what type of material is more likely to yellow
Ante-rior restorative materials with high matrix contents that are self cured
what proceedure makes color matching difficult
bleaching (wait till tratment is done)
How can one make the difference between enamel and composite color less noticable
Bevel the edge
where do secondary caries occur most often
proximal and cervical margins
what is the biggest concern for posterior composites
posterior wear
cytotoxicty of unpolymerized materials
concern for post opperative sensitivty
but poorly solube in water, and polymerized intoa bound state
low amount does escapte
what are glass ionomers
materials consisting of ion-cross-linked polymer matricies surrounding glass-reinforcing filler particles
what are glass ionomers made of
aluminosilicate powder from silicates
polyacrylic acid liquid of polycarbs
water of glass ionomers and composites
GI: philic
Composites: phobic
pros and cons of ceramic metals (cermet) mixtures
much stronger than normal GI, but poor esthetics and not modified
uses of cermets
as cores
what is atrauamic restorative treatment
done when no professional available. remove caries without using instruments and then place GI in hole and have the person bite on it to make it the right shape
How does GI hold into the prep
Chem and mechanical means (good mech is better than good chem)
recharging of GI
when you place high levels of fluoride on the tooth and it goes back into the GI
Adhesion
the state in which 2 surfaces are held together by interfacial forces which may consist of valence and interlocking forces
mechanical adhesion
interlocking with irregularities in the surface
adsorption adhesion
chemical bonding between adhesive and the adhered (primary: ionic and covalent) (secondary: h bonds, dipole, van der waals)
Diffusion adhesion
interlocking between mobile moleulces
electrostatic adhesion
double layer of electrical at the interface of a metal and polymer
how are resins bound to toooth
Mech
adsoprtion
Diffusion
what is needed for good adhesion
glose contact
surface tension of adhesive lower than that of substrate
the major problems for bonding resins
resins shrink so adhesives must provide a strong initial bond to resist stresses of shrinkage
type I enamel etching pattern
Dissolution of prism cores without dissolution of prism peripheries
type II enamel etching pattern
dissolution of prism peripheries without dissolution of prism cores
type III enamel etching pattern
has patterns without prism morphology
what makes up enamel etchants
Phosphoic acid at 37% (30-40%)
bond strength of enamel etchants
20-50 megapascals
what is harder to bond
dentin or enamel
what in the smear layer allows for diffusion of the dentinal fluid
submicron porosity
what is the configuration factor
ratio of number of composite bonded surfaces to unbonded surfaces
what is water absorption by the resin related to
resin content
3 step etch steps
- Phosphoric acid etchant that is rinsed off
- A primer containing reactive hydrophilic monomers in alcohol, ethanol, acetone, or water
- Unfilled or filled resin bonding agent (adhesive) that contains hydrophobic monomers (Bis GMA) and hydrophilic molecules (HEMA)
purpose of primer in 3 step etch
increase surface tension of dentin
what happens when primer and bounding resin are applied to etched dentin
they penetrate the intertubular dentin and form and interdiffusion zone (hybrid layer) and polymerize the open tubules to form resin tags
2 step self etch
uses self etch primers containing phosphonated resin molecules that etch and prime dentin and enamel
no rinse
what happens to the resin tags in 2 step etch
smear plugs in the resin tags for less post op sensitivty
etching efficiency of two step etch
do not etch as well as enamel
what is in1 step self-etch adhesives
contain uncured ionic monomers that contact the compsote material directly
how do 1 step eself-etch adhesivess work
semi-permeable membranes, resulting in hydrolytic degradation
roll of water in self-etch adhesives
solubilize ca and p ions that form from the interaction of the monomers with dentin and enamel
patial removal of what protein may enhance remineralization
phosphoproteins
collagen not encased in resin can do what which is bad
vulnerable to degradation by matrix metalloproteins
microleakage
passage of bacteria and toxins between restoration and tooth walls
when does microleakage matter
pulpal irritiation by bacteria not chemical toxicity of restorative material
nanoleakage
small porosities in the hybrid layer or at the transition between the hybrid layer and the mineralized dentin for minuscule particles
what type of dentin is more resistant to acid etching
sclerotic dentin
what type of composites have a low elastic modulus
Microfilled composites
what area of the tooth is most hypersensitive
Cervical area
what does GLUMA work
reduced dentin sensitivty through a protein denaturation process
what must be done for cermanic and zirconia restorations
etched with HF acid for 1-2 minutes to create retentive microporosities
then rinsed
coupling agent applied
primer used with phosphonic acid monomer or carboxylate monomer to improve resin bonding
when is it best to place selants
in perminant teeth of children
how long to etch for a sealant
15-30 second
do carbide or diamond make a thicker smear layer
diamond
how far is needed to be left in the marginal ridge to not make a proximal box
1.5mm
when to use a RMGI base or CaOH liner
between .5-1.5 RDT use RMGI
less than .5 mm CaOH then RMGI base
stress in relation to C factor
higher stress from higher c factor: more walls bound
what can be added to reduce the effects of polymerization shrinkage
RMGI liner or flable composite due to favorable elastic modulus
the sandwich technique
when composite is placed over RMGI
advantage of the composite technique
RMGI binds to dentin without opening tubules (reduced sensitivity)
RMGI released fluoride
favorable elastic mdoulus
what surface does composite not bind to well
the root surface (dentin)
