Lecture 4 Reding Flashcards
composite:
compound of 2+ diff. materials w/ props that are superior or intermediate to those of the individual consituents
Organic matrix of enamel:
enamelin
Inorganic matrix of both enamel and dentin:
hydroxyapeptite
Organic matrix of dentin:
collagen
Advantages of RBC(Resin Based Composites)
resist fracture and wear, set on command (when ready), conservative prep, low heat conductivity, no current conduction, radiopaque
RBC prep requires removal of:
only the lesion
Disadv’s of RBC:
shrink (2-4%), DBA and lite curing, tech sensitive, lengthy placement, RD required, water sorption (amlgam does not)
Amalgam is more technique flexible than RBCs
T
T or F? Amalgam has high sorption.
F.
RBC components:
4: Polymer matrix (resin monomers) Resin fillers, coupling gent, initiators to start rxn
Continuou phase to which other ingredients are added:
Organic polymer matrix
Bis-GMA:
bishpenyon-A-glycidyl methacrylate
% of high vs. low weight polymers in organic matrix RBCs:
70% high molecular weight / 30% low
Examples of high molecular weight polymers:
Bis-GMA, UDMA,
Low l=molecular wight/low viscosity:
TEG-DMA
Low shrinkage monomer
Bis-EMA or oxybismethacrylate
What is the part of the RBC that shrink?
the matrix
Inorganic Fllers:
Quartz or Glass based (zirconium oxide,aluminum oxide, or silicone dioxide?)
Quartz inorganic fillers:
fused silica, lithium aluminum silicate
Glass inorganic fillers:
borosilicate, ziconium, barium, strontium
Fillers improve these properties:
color stability, reduce water sorption, comp and utensil strength, reduce coeff of thermal expansion, reduce shrinkage, imp wear resistance
What part of a RBC is responsible for water sorption and weakness and shrinkage ?
matrix
% V that inorganic fillers account for:
30-70% of the composite
% weight that inorganic fillers account for:
50-85% of the composite
Coupling agents are aka:
silanes
Functions of coupling agents;
coats filler particles promoting adhesion to the matrix, polymerizable silica-reactive monomer. Provides adhesion to silaceous surfaces
Does the addition of a weak matrix to a strong filler lead to the formation of a weak or strong composite?
weak
Does the addition of a weak matrix to a strong filler and silane lead to the formation of a weak or strong composite?
strong
Modes of initiators:
- chem run of mixed composites 2. exposure to light
Most current composites are activated by:
exposure to visible light (460-480nm) blue light
What color light activates current composite?
blue
Initiator and activator for chemically activated systems:
init: benzoyl peroxide act: aromatic tertiary amine (2%) (N,N-dimethyl-p-toluine)
Initiator and activator for light-activated systems:
Init:Alfa-diketone camphorquinone Act: aliphatic tertiary amine (0.01-0.04%) +468nm light
Volumetric shrinkage of RBC can be up to:
7%
Coefficient of thermal exp:
2-6 X (30-60 ppm/’ C) that of dentin (9 ppm/’ C)
Enhanced flowability vs.
increased risk of porosity
To prevent resin from sticking to instrument:
alcohol gauze
Traditional RBCs are what type?
macrofilled (10-100um)
Macrofilled RBCs:
ground quartz, 70-80% filled by weight, pronounced plastic deformation, micro leakage, water sorption, surface staining, intrinsic discoloration
Microfilled composites (0.01-0.1um):
only sub micron particles, ground to 5-50um & incorporated into additional microfilmed material
benefit of combining sub micron particles with additional microfilled particles:
filler content is maximized, polymerization shrinkage is minimized
When to use microfilmed composites:
non-stressbearing areas (anterior)
Microfilled composites use:
colloidal silica as a filler and pre polymerized particles
Properties of microfilled composites:
low shrinkage and highly polishable
Advantages of microfilm resins:
excellent polish, highly esthetic areas (class V, composite veneers)
Disadvantages of microfilm resins:
low strength (don’t use for Class IV), water absorption may be higher compromising long-term color stability
hybrid resins are blends of:
0.04um and small particles (1-4um)
The combination of filler article sizes allows:
the highest levels of filler loading with the corresponding improvement in physical properties
Do hybrid resins have less or more internal discoloration?
less
Which has the best properties, traditional, microfill, or hybrid?
hybrid
Which polishes better, hybrid or microfilm composites?
microfills
T or F? Hybrid composite are radiolucent.
F.
For which area are hybrid composites indicated>
stress bearing (posterior)
Which are more esthetic, hybrid or microfilm composites?
hybrid (monochromatic)
Benefit of micro-hybrid composites:
combine polishing props of micro with the strength of hybrids
Avg particle size of Micro-hybrid or nano-filled:
less than 1um
Ex of Micro-hybrid or nano-filled composites:
Esthet-X (caulk) and Point 4 (Kerr)
T or F? Flowable composite is more resistant to wear.
F. less
Filler by volume % of flowable composite:
37-56%
Does flowable composite have high or low polymerization contraction?
high
Are flowable composites more or less elastic?
more (flees with tooth)
flowable composite is indicated for:
very small Class V, sealants, liner under high C-factor preps
Any light unit with a range of these wavelengths can be used for visible light curing units:
400-500nm
How to test your light curing unit:
radiometer
Extent of composite polymerization depends on:
Wavelength of light, light intensity, exposure time, distance from light, shade of resin composite
CAMBR
Carries Mmgmt by Risk Assesement
Main components of MID:
assessment of disease risk, w/ focus on early detection and prevention, external and internal remineralization, use of a range of restorations, dental material and equip, and surgical only when required and after disease controlled.
When should surgery be done according to MID?
only when required and only after disease has been controlled
High risk protocol:
F varnish every 3mo, Rx paste 2X/day, including before bed (pos teeth could be sealed if at risk)
Moderate risk protocol:
F varnish every 6mo, OTC paste 2Xday, OTC rinse 1-2Xday (pos teeth could be sealed if at risk)
Low risk protocol:
OTC paste 2Xday
Antibacterial rinse:
Chlorohexadine (does not reduce caries) 1st wk of each mon
MI paste:
Ca and P remineralize tooth
Xylatol:
Replacement for sugar, can be prescribed
T or F? Demineralization indicates an active lesion.
F. Not always
PTPM:
Plaque control, Tx of existing caries lesions, Protection of surfaces at risk, and Maintenance for prevention
ICDAS Score of 1(or2) for caries mgmt:
no caries lesions or arrested caries lesion in fissure with caries-susceptible morphology
ICDAS Score of (1) or2 for caries mgmt:
suspected but no distinct evidence of caries lesion at base of fissure
ICDAS Score of 3,4,5,6 for caries mgmt:
Obvious cavitation or radiographically evident carious dentin at base of fissure
Tx for ICDAS Score of 1(or2) for caries mgmt w/ low risk:
No tx
tx for ICDAS Score of (1) or2 for caries mgmt:
Sealant
Tx for ICDAS Score of 1(or2) for caries mgmt w/ mod or high risk::
sealant
Tx for ICDAS Score of 3,4,5,6 for caries mgmt:
restoration
Placement of sealant:
external 0.5mm of fissure (to provide sound enamel for bond)
Use are to dry possibility active lesion for this ICDAS score:
3
Tx for ICDAS score of 3 w/ an active, non-proximal corona lesion:
lesion arrest (remineralization or resin infiltration) and recall for reveal of risk status and lesion
What is resin infiltration?
?
Mgmt of caries lesion in root surfaces of permanent teeth: lesion hard to explorer; stained or unstained, moderate or high risk:
lesion arrest (remin therapy)
Mgmt of caries lesion in root surfaces of permanent teeth: lesion hard to explorer; stained or unstained, low risk:
monitor lesion at periodic reeval appt
Mgmt of caries lesion in root surfaces of permanent teeth: lesion soft to explorer and est. depth less than 0.5mm:
Lesion arrest (remin therapy)
Mgmt of caries lesion in root surfaces of permanent teeth: lesion soft to explorer and est. depth less than 0.5mm. We did remain therapy and after 3-6 mo the lesion progressed:
Restoration (Rc, RMGI, or sandwich)
Mgmt of caries lesion in root surfaces of permanent teeth: lesion soft to explorer and est. depth greater than 0.5mm:
Restoration Restoration (Rc, RMGI, or sandwich)
Mgmt of caries lesion in root surfaces of permanent teeth: lesion soft to explorer and est. depth less than 0.5mm. We did remain therapy and after 3-6 mo the lesion did not progress, moderate or high risk pt:
Lesion arrest (remin therapy)
Mgmt of caries lesion in root surfaces of permanent teeth: lesion soft to explorer and est. depth less than 0.5mm. We did remain therapy and after 3-6 mo the lesion did not progress, low risk pt:
monitor lesion at period eval appt.
T or F? A caries lesion can be arrested, but not reversed.
F
Ways to remineralize:
change oral hygiene, change diet, apply fluid, stimulate saliva
What can you do for a pt with chronic dry mouth?
prescribe saliva substitute with inorganic ions
In one study, sugar-containing foods were not assoc with caries experience unless:
the kid brushed once a day or less
How can a person with open embrasures keep their mouth cleaner?
interproximal brushes
How can a periodontal pt keep their mouth cleaner?
interproximal brushes
How can a pt with closed interdental spaces keep their mouth cleaner?
floss
Floss __times a day for caries prevention.
1
Floss __times a day for gingivitis.
2
Antimicrobials that have been added to F:
amine (Am) and stannous ions (Sn)
What intrinsic properties does Amine have?
antiglycolytic properties
Which as stronger antimicrobial effect, amine fluoride or sodium fluoride?
amine F
T or F? Stannous effects mineral dissolution.
F. It has antimicrobial activity (SnF2)
Which is better at inhibiting plaque formation AmF/SnF2 or other fluoride combinations?
AmF/SnF2
How is AmF/SnF2 effective at low concentrations?
by slowing bacterial growth through the inhibition of bacterial metabolism (i.e. acid prod)
This added to toothpaste provides antibacterial effects by disrupting bacterial cells walls:
Triclosan
Mechanism of Triclosan having antibacterial effects:
disrupts bacterial cell walls
This would be considered a lower-level F dentrifice:
1,100 ppm F (25% reduction in caries)
Use of lower-level F dentrifices offers a __ % reduction in caries:
25%
High-F dentrifice (ppm?):
5,000 ppm
Use of a high-level F dentrifice offers a __ % reduction in caries:
75%
What to do when plaque control is not sufficient?
topical F solution, gels, or varnishes. Suggest sugar-free gum. Then brush 3Xday (or rinse/tablet)
Stains plaque pink to see how well pt is brushing:
disclosing solution
Available strengths of OTC F rinses:
0.02% and 0.05% NaF
Reduction in caries with F gel:
21%
strengths of Rx F gel:
1.1% NaF
Rx strength NaF rinse:
0.2% NaF
Avg caries reduction w/ Rx strength NaF rinse:
30%
Mouth rinses have been made with:
acidulated P F (APF), stannous F, ammonium F, and amine F
Benefit of acidulation:
may increase the F uptake into the tooth mineral
How does acidulation work?
It causes mild etching of the enamel, which creates micropores for better F diffusion & inc SA
Etching may cause the transfortmation of apatite to:
brushite
What happens to brushite when exposed to low conc F/
recrystallizes into fluorapatite
When will brushite recrystallizes into fluorapatite most readily?
low F/Ca ratio
What about APF enhances F uptake by enamel?
the low pH
The presence of this (with APF) prevents enamel dissolution by surrounding the tooth with P ions:
orthophosphate
Many rinses recharge:
glass-ionomer restos
Why are APF solution contraindicated for pts with glass-ionomer restos, por crowns, and veneers?
The acidic topical F degrades them
Which ionomer is more resistant to surface degradation than glass-ionomers?
RMGI
The application of acidic F solutions produces what for pts with resin composites?
filler dislodgment and destruction of the filler-resign matrix interface
Food products that Xylitol can be found in:
gum, oral syrup, and gummy bears
Why is xylitol non-cariogenic?
bacteria can’t metabolize this sugar
Xylitol gum should be recommended for these pts;
moderate-high-risk pts, hyposali-vation
Ca agents added to pastes:
nanohydroxyapptite, (nHAP), tricalcium phosphate (TCP), alcium sodium phosphosilicate (NovaMin, NovaMin Technologies), and amorphous calcium phosphate (ACP)
Products with functionalized TCP improve:
remineralization of white spots
NovaMin-based pasts release:
Na, Ca, and P, resulting in the formation of crystalline hydoxycarbonate apatite layer
T or F? ACP technology is based on stabilized ACP.
F. unstabilized
Explain how unstabilized ACP works:
Ca salt and a P salt are separately added to mouth via dual chamber device. The salts release Ca and P ions resulting in immediate precip of ACP or amorphous C F phosphate (ACFP). These are unstable and form hydroxyapatite and fluorhydroxyapatite
What type of caries do ACP-based rinses lower the incidence of?
root caries (and promot remain of enamel (e) subsurface lesions)
What is the health concern with ACP-based rinses?
may promote calc formation w/ long term use
Why is frequent eating bad for your teeth?
pH issn’t allowed to neutralize, and demin outweighs remin
Diet suggestions:
Combine cooked & processed foods w/ nonacidogenic foods, include foods of firm or hard texture, choose good fats that will coat tooth surface and reduce plaque adherence
2Xyear F varnish tx in adolescents prevented proximal caries;
69%(high risk), 66% (medium risk), and 20% (low risk)
F varnishes have __ % NaF
5
F varnishes have __ ppm NaF
22,600
How does F varnish work?
CaF globules are deposited and act as a reservoir for the slow release of F and Ca over time and under acid challenges
Can F varnishes reveres and arrest active enamel lesions?
yes
How are F gels applied?
custom-made trays
F gels are made of:
1.23% acidulate P F or neutral 2% NaF
T or F? Active whit elesions can be arrested with brushing alone.
T
Sealing is only recommended on O surfaces if:
the surface is not being cleaned
Sealants are indicated for adults and children who:
mod/high risk, active white spot lesions, existing pits and fissures that are susceptible to caries
2 main types of pit and fissure sealants (P&FS)
resin-based sealant and composites and glass-ionomer cements
T or F? Resin-based sealants contain F.
F. glass-ionomer cements do.
T or F? On proximal and free, smooth area, caries proceed quickly.
F. slowly
What must be done before applying the actual sealatn?
acid etching or conditioning
T or F? Sealants are self-cleansing to prevent plaque accumulation.
T
Advantages of sealants;
no irreversible intervention, active dentin lesions that are covered do not progress further, new lesions are prevented
Disadvantages of resin composites:
shrink in polymerization, require isolation for proper bonding, less resistant to ear than ceramics, prone to chipping, do not bond well to dentin and root surfaces, don’t have antibacterial props
__-__ % of anterior Class III and Class V resin comp resorts remain acceptable after 5 yrs.
60-80%
Most common reasons for repair of ant resin comp resto
marginal staining, surface discoloration, secondary caries, edge chipping in high-stress areas, and/or fractures of the resto
Varibales to why ant rests survive or not:
dr, location, size, age of pt, caries risk, bonding substrate
4 components of resin composite;
polymer matrix, filler article, couling agent, and initiator system
This is the continuous phase to which the other ingredietns are added:
matrix
Does bis-GMA have a high or low viscosity?
high
What is frequently added to bis-GMA to make it less viscous?
triethylene glycol dimethacrylate (TEGMA)
T or F? Self-adhesive composites are now available.
T
FIller particles are usually:
radiopaque glass, zirconium oxide, aluminum oxide, or silicon dioxide
Benefits of adding filler:
improves translucency, reduces Co thermal exp, reduces poly shinkage, makes it stronger, harder, denser, and more resistant to wear
t or F? In general, the lower the percentage of filler added, the better the physical props of the resin composite.
F. the greater the perc
What are the filler particles coated with?
a coupling agent (organosilane)
Why add coupling agent to the filler?
capable of production chemical bonding to the filler particles and the resin matrix, increase strength of the cohesive mass
How are resin composites cured?
mix 2 components or expose a single component to a light
What does the initiator, benzoyl peroxide, do to activate the rxn?
splits into 2 active free radicals when attached to the amine
What does benzoyl peroxide initiate the polymerization of?
metacrylate molecules
Most commonly used molecule for light cured composites:
camphorquinone
When is photo initiation most efficient?
when an amine molecule is also unloaded in the formulation to act as a type of accelerator in the presence of he camphorquinone
Disadvantages of resin composite:
shrikage (1.5% to 5), marginal defects, sensitivity, staining at margins, recurrent caries, nanoleakag at the resin-dentin interface
Rigidity is aka:
gelation
Recommendations to offset the shrinkage of resin composites:
incremental placement, long enamel bevels,low-shrinkage material, flexible resin liners, slow-setting resin-modified glass ionomer liners, and modified light-curing
Benefit of unit dose resin comp.
fewer trapped air bubbles, infection control
What are shrinkage stresses that occur in the early phase of polymerization relieved by?
deformation and flow of the material
Where are the weakest bonds for resin comps:
dentin or cementum
C-factor:
configuration factor, the ratio of bonded SA to the non bonded SA of the resto
What influence the intensity of the stresses produced during polymerization?
The C-factor
Do you want a high or low C factor to endure high shrinkage stress?
high
Is the C factor favorable or unfavorable for most ant restos?
favorable
Will high or low-stiffness material typically generate higher shrinkage stress?
high-stiffness
How do the co of thermal expansion of resin comp and tooth structure compare?
resin is 2-6 times higher (expands and contracts more and at a greater rate)
Classifications of resin comps based on viscosity:
conventional, packable, or flowable
Disadvantage to low-viscosity resin comps:
tend to be sticky and tend to slump, risk of porosity inside the rest increases
Are viscous resin comps sticky or not?
not
T or F? Variations in the viscosity of a resin composite is always a reflection of the filler content.
F.
Do low or high viscosity material generally have a lower filler load?
low-viscosity (seems backwards)
What to avoid when using alcohol on your instrument while placing RC:
let it dry first so it doesn’t incorporate into the resin
Recommendation when using very sticky materials
use wetting resin to lubricate instument
What provides chroma in typical dentition?
dentin, as well as opacity, and fluorescence
How does enamel effect the appearance of the tooth
it adds translucency and opalescence
Microfilled resin composites contain:
silica filler of sub micron size
Why can only low amounts of silica filler be added to composites?
very high SA and requires a large amount of monomer to wet the SA
Are microfilled composites relatively strong or weak?
weak, so they add pre polymerized resin fillers to maximize the filler content
Why is microfilmed resin composite so highly polishable?
bc each silica particle si only about 0.04 um in size
Which composite can be polished best and have the smoothes surface?
microfilled
Primary indication for microfilmed resin composite:
esthetic areas
Are microfilmed resin composites indicated for stress-bearing restos?
no
Do microfilmed resin composites absorb more or less water?
more
Do microfilmed resin composites have an increased or decreased long-term color stability?
decreased
Hybrid RCs are a combo of:
conventional and microilled technology
Hybrid RCs are indicated for anterior/pos/both.
both
What leads to resistance to internal discoloration for the Hybrid RCs?
high filler content
Avg particle size of RCs:
less than 1um
Many nano hybrids contain this to reduce overall curing shrinkage:
PPRF
Properties of most nano filled comps:
nonsticky and nonslumping
How do the amines differ bw chemically and light activated RCs?
chem- aromatic, light - -aliphatic
Refractive index of tooth and composite;
1.5
Most RCs on market are:
nanofills and hybrids (she says microfilled at another spot)
IPS target for wear resistance:
10^-7
nano is 10^-?
9
The larger the filler particles, the greater the space bw them and therefore,
the more resin matrix available to create problems
T or F? Class IV restorations should be done with microfill resin.
F. not good at stress bearing (use hybrid for stress bearing)
Types of light curing units
Quartz/Tungsten/Halogen OR LED
How often should you test your light curing unit?
every few months
T or F? Intensity of the light and the necessary duration of exposure are always directly related.
F
T or F? The darker the shade of the composite the longer it will take to polymerize.
T
Issue if a partial sealant is lost:
pt is at higher risk of caries
Which teeth retain sealants best?
man and premolars (vs molars)
how to prep before the actual sealant is placed?
acid etch, then bonding agent (wets fissures)
Adv/disadv of RMGI sealants:
good caries prevention, poor mechanical retention compared to resin
When should RMGI sealants be considered?
when moisture contol is an issue
T or F? Resin composite performs well as a sealant.
T
PRR stands for:
preventative resin restoration
PRRs are successful for up to:
10 yrs
What % of sealants placed with PRRs are lost per year?
5-10%
When is a PRR indicated?
when some areas of the fissure system of a tooth are associated with carious dentin and other are not, with a deep caries lesion when areas of the fissure system are not carious
How can you reduce the viscosity of a RC?
heat it
Are bevels required at eh occlusal margins of sealant preps?
no
What type of restorative material should be used in dentin?
highly filled
increments no greater than __mm should be used for RC
2
T or F? An occlusal sealant can be placed over a resin composite.
T
T or F? A pit or fissure can be open to dentin.
T
When is a lesion likely active?
enamel surface is whitish/yellowish opaque and chalky, with loss of luster, rough when probed, in a plaque stagnation area
plaque stagnation areas:
pit and fissures, near the gingiva, below the prox contact
Leson likely to be arrested when:
surface of enamel is white, brown or black, enamel is shiny, fells hard and smooth when gently probed, lesion is located some distance from gingival margin
Best way to remineralize pit and fissure noncavitated lesions:
sealant
T or F? microcavitations can be sealed.
T
Which is more preventative against carious lesions, fl varnish or sealant?
sealant (27% reduction vs 65%)
Which teeth should be sealed?
cavitated lesions or teeth that are at risk
Primary prevention w. sealant ex.:
seal a tooth before any caries form
secondary prevention w. sealant ex.:
seal after a tooth has a lesion
What is the only limiting factor for a sealant blocking bacteria and sugar and preventing caries progression?
the loss of the sealant
T or F? Sealant stop progression of lesions.
F. sig reduce the progression
When should sealants be placed?
early, non-cavitated carious lesions to prevent progression of the lesion
types of sealants
resin (clear or opaque), flowable, (glass-ionomer)
Why resin sealants are better than glass ionomer:
more effective, better retention rates
Advantage of clear sealant:
you can see the underlying lesion
What type of acid do we use to prep for sealant?
phosphoric
T or F? Opaque resin composite requires an adhesive.
F. you can if you want
PRR:
remove only carious portions and seal the rest
bite registration paper is aka:
accufill
