GD Exam 3 Flashcards
basic structural units of enamel
prism rods
the outer most layer of enamel is aprismatic true or false
true. (highly acid resistant)
Enamel prisms are composed of several _________and has a ______ like structure
several hydroxyapatite crystals and has a key-hole like stucture
homogenous structure
predictable bonding
and excellent long-term bonding durability
are all characteristics of
enamel
Describe the steps of bonding (only) to enamel
- clean the surface
- Etch the enamel surface up to 30 seconds (phosphoric acid gel)
- Rinse for 30 sec
- Air-dry; look for frosty surface
- Application of adhesive resin (bonding)
- Light curing for 20-40 second
Whats the significance of etching enamel?
increases wettability, create microporosities,
Comeplete the statements describing the different patterns of enamel etching
type 1:
type 2:
type 3:
type 1: removes prism core (the center)
type 2: removes prism periphery
type 3: mixed/combination of type 1 and 2
funfact there is no difference in micro-mechanical bonding of the different etching patterns
describe surface prophylaxis
its the removal of enamel pellicle and surface debris
necessary to properly etch the enamel surface
it increases infiltration of adhesive resin/sealant
the retention of sealant at the base of the pit is increased
the use of prophylaxix decreases microleakage of sealants
What is the effect of active ingredients on prophylaxis
active ingredients in prophylatic pastes such as fluoride and ACP can reduce the bond strength of resin-based materials to uncut enamel surfaces
Contamination of the surface with saliva, blood, or fluid will increase the sealing ability and the bond strength
false. duh.
As the severity of dental fluorosis increases, the bonding efficacy is ______
reduced
How do you overcome dental flourosis when etching?
etch for additional time up to 2 min) in enamel only
Which part of dentin is mainly mineralized?
intra-peri tubular dentin
which part of dentin is mineral and proteins found
inter-tubular dentin
Heterogenous structure and fair-long term bonding durability is a characteristic of enamel or dentin?
dentin
define the smear layer
layer of debris formed during the tooth preparation
How long do you etch in dentin
less than 15 seconds
true or false dentin must be completely dried
false; must keep dentin wet
true or false you can rewet enamel
false. rewetting technique is used in dentin
you rewet for atleast 3o seconds
dentin bonding agent primers are hydrophilic or hydrophobic
hydrophillic monomers that have a high affinity for water. HEMA, 4-META, Penta, Phenyl-P
Dentin bonding agent adhesives are hydrophillic or hydrophobic
hydrophobic monomers that bond to composite resin, resin cement, sealants. Bis-GMA and TEGMA
dentin bonding agent solvents are what
water, acetone, and ethanol
List 3 product names of the 3 step etch and rinse
- optibond FL
- All bond 2
- Adper scotchbond
List 3 product names of the 2 step etch and rinse
- Optibond solo plus
- one-step
- adper single bond plus
What does self-etching mean ( 1 and 2 step 6th and 7th generation)
theres no acid etching procedure, presence of acidic monomers.
*formation of the hybrid layer which is the simultaneous deminalization and infiltration of the adhesives system into the superficial dentin
in self etching enamel, the use of _______ prior to application
use of phosphoric acid
low bond strength values when applied to (cut or uncut) enamel
uncut.
note the higher bond strength values on cut enamel but is still lower than etch and rinse systems
Whats the latest generation of bonding systems
universal bonding systems *8th generation
Universal bonding systems use what type of etching technique?
the TOTAL ETCH technique
desensitizer agents are usually used after
after etching procedures
true or false GLUMA affects the bond strength
FALSE. gLUMA does not affect bond strength
what specfic type of agents can actually affect bond strength values?
Oxalate based agents
what is sclerotic dentin?
dentin that has become translucent due to calcification of the dentinal tubules as a result of injury or normal agaeing.
how do you manage sclerotic dentin?
over etch the dentin for 30 seconds or roughen the dentin surface with a diamond bur
true or false in carries-affected and caries infected dentin the bonding procedure remains the same
true
What is a composite material
a solid that contains two or more distinct constituent materials or phases. mechanical properties such as elastic modulus are altered
Development of Bis-GMA self-curing composite?
in 1965 by bowen
in 1969 the addition of ______ lead to better wear resistance
filler particles.
List the 5 basic componenets of dental composites
- organic polymer (resin) matrix
- inorganic filler particles
- coupling agent
- initiator-accelerator system
- others
true or false. filler particles make up a minor portion (by volume or weight) of dental composites
false. they make up a major portion
True or false. most filler particles contain heavy-metal oxides such as barium or sinc causing radiolucency
false. radiopacity
Particle ___, __, and ___ are all used to classify dental composites
particle size, shape, and distribution
what are the functions of filler particles
reinforce the resin matrix
provide appropriate degree of translucency
control the shrinkage of the composite during polymerization
reduction of the thermal expansion and contraction
control workability and viscosity
decrease water sorption
IMPART RADIOPACITY
Coupling agents are usually what
organic sillicon compounds, organosilane, or silane
the ______ of the fillers are treated with ______ during the manufacture of the composite
the surfaces of the fillers are treated with silane during the manufacture of the composite (think coupling agent)
How do coupling agents work?
during the curing of the composite, its unreacted double bonds will co-polymerize with resin monomers
list the functions of a coupling agent
- provides bonding between the inorganic filler particles and the organic resin matrix by forming an interfacial bridge that strongly binds the fillers to the resin matrix
- it enhances the mechanical properties of the resin composite and minimized the plucking of the filler from the matrix during clinical wear
3, it helps with stress distribution and provides a hydrophobic environment minimizing water absorption of the composite
Whats the purpose of photo-initiators and how do they work
photosensitizers are added to the monomer mixture during the manufacturing process
camphorquinone is the most commonly used used photosensitizer
photosensitizers absorb electromagnetic energy from blue light (at a peak wavelength of about 465 nm)
free radicals are generated upon activation
The first step of the initiator-accelerator system is photo -initiators. whats the next step?
- photo-initiators
- CHEMICAL INITIATORS (an organic amine should react with an organic peroxide to produce free radicals.
organic amine = catalyst paste
organic peroxide = universal paste
the free radicals produces will attack the carbon double bonds, causing polymerization
list some examples of chemical initiators
BPO (benzoylperoxide) and TBB
Whats the third step of the initiator accelerator system
- DUAL-Curing (which is basically just photo+chemical initiators)
Whats the role of inhibitors? list some examples
they prevent spontaneous polymerization (and so increase shelf life and working time)
ex: Hydroquinone (MEHQ, BHT)
what are the 4 states of the polymerization reaction
- activation
- initiation
- propogation
- termination
What is the degree of conversion
a tool to evaluate how well the composite was polymerized. It calculates the rates of C double bonded to C before and after polymerization
most dental composites have _______ conversion rates. there is never 100% polymerization.
most have 45-60% conversion rates
true or false: polimerization shrinkage 2-5,5%
true
polimerization shrinkage occurs towards the _____ portion of the material (NOT towards the light source)
towards the INNER portion of the material
-it induces stresses at the bonded interface
-creates gaps at the interfaces (enamel and dentin)
C factor is
ratio of bonded to unbonded surface
class I has a c factor of
5
5 bonded, 1 unbonded
class II has a c factor of
2
4 bonded, 2 unbonded
nonfilled composites allow higher volume of fillers and helps to overcome
polymerization shrinkage
Packable (high viscosity) are designed for
posterior teeth since they are opaque
also:
1. low polymerization shrinkage
2. difficult to obtain marginal adaptation
3. studies show high microleakage values
flowable (low viscosity) can easily adapt to
all areas of the preparation
highly porous
studies show no significant advantages regarding marginal seal and adaption compared to hybrid composites
Silorane is a new formulation that is an advancemnet in material compoisiton that helps to _____
overcome polymerization shrinkage
what are bulk fill composites
its a new formulation in composition to overcome polymerization shrinkage, It can actually result in incomplete polymerization at bottom of cavity and high polymerization shrinkage stress
What are the three classes of dental polymer-based restorative materials
class 1: materials whose setting is done by mixing and inititaor and activator (self curing)
class 2: materials whose setting is done by the application of energy from an external source such as blue light
class 3: dual cure: which basically is curing by the application of external energy and also have a self-curing mechanism present
what has a higher compressive strength, enamel or dentin
enamel
what has higher tensile strength, enamel or dentin
dentin
what has a higher elastic modulus, enamel or dentin
enamel (84)
strengths increase lineraly with the volume fraction of
fillers
true or false microhybrid has a higher compressive strength than microfilled
true
higher filler content = higher ______
higher hardness
The more resin content, the _____ the linear coefficient of expansion
more resin = higher linear coeff of thermal expansion
Photo-initiation light curing uses camphoroquinone and _______
a tertiary amine
about 468 nm
whats the max amount of degree of conversion
about 70%
Incident radiance is what
incident on the material surface
the amount of light that your dental composite will receive is always lower
radiant exitance or radiant emittance is what
the light emitted from the light curing tip
Spectral emission from the light curing unit and spectral absorption requirements of the photocurable material should be _______ for optimal ______!
Should be matched for optimal polymerization
true or false: you should increase curing time with decreasing distance from material.
false.
increase curing time with increasing the distance from the material
t or f sealants are applied after acid etching to coalescenced areas
F. its applied to NON-coalescenced (meaning pits and fissures) after acid etching.
Sealants protect against _____% of cavities for 2 years and continue protect against ___% of cavities for up to 4 years.
80% for 2 years and then 50% for up to 4 years
List the indications of placing sealants for adults and children
- deep developmental grooves and pits
- moderate or high risk for caries
- evidence of initial occlusal carious lesions
In children, sealants are most effective when placed with _____ immeditetly after eruption of permanent posterior teeth and occlusal surfaces are fully exposed
with proper isolation
What type of sealants require a dry field
Renin-based sealants
if a dry field cannot be maintained for a renin-based sealant, what do you do
use a different material like GI, RMGI, or poly-acid modified resin
what should you clean teeth with first to remove oral debris, smear layer, and potential surface contaminants before placing a sealant
clean teeth with slurry pumice
The slurry pumice should be free of ingredients that would effect ______
free of ingredients that would affect enamel bonding.
no occlusive or remineralize agents that would affect enamel demineralization during etching
no fluoride, calcium, essential oils, or flavoring agents
In 2008 the ADA said sealant retention can be improved if the clinician applies a bonding agent that contains both an adhesive and a primer between the previosuly acid-etched enamel surface and the sealant material.
read
what are the advantages to using dental composite
esthetics
-conservative tooth prep (less extension, no minimum depth, mechanical retention usually not necessary)
-low thermal conductivity
-universal use
-adhesion to the tooth
-repairability
What are the indications for using composite
- class 1-6 restorations
- core buildups
- sealant and preventive resin restorations
- esthetic procedures
- temporary procedures
- periodontal splinting
what are the contraindications for using composite
- if youre not able to obtain proper islotation
- occlusal considerations
- extension of the restoration on the root surface
- operator factors
when using composite, a flat pulpal floor is necessary
no
and theres no specified thickness/depth required either unlike amalgam
compared to amalgam, the width of a composite prep should be
very minimal
whats the clinical significance of C Factor
the higher the c factor, the higher the potential for polymerization shrinkage stress
post operative pain
and poor prognosis
Dental composites exhibit volumetric shrinkage of ______%
2-5%
What can a clinician do to minimize shrinkage
- use an INCREMENTAL technique
- choose appropriate restorative materials
3, Possible use of RMGI liner
Preventative resin restoration or conservative composite restoration techniques?
- limit prep to carious pits and fissures, no extension
- Combine compite and fissure sealant in restoration
conservative composite restoration was referred to originally as _____
preventive resin restoration (PRR)
The composite outline form and depth is determined by the
extent of the decay
true or false: dental sealant material may be used in combination with the composite to help reduce the risk of future disease
TRUE
True or false. You should lightly air dry to thin the bonding agent and expose it to curing light for 10 seconds
YES
The jiffy composite polishing brush is impregnanted with _______
silicon carbide
The initial development of the glass ionomer was in ______ by _____
1972 by Wilson and Kent
Define glass ionomer
glass ionomer is a generic name of a group of materials that use silicate glass powder and an aqeuous solutions of polyacrylic acid.
glass ionomers are water-based and self-adhesive restorative materials and can be used as liners, bases, luting agents, sealants, and temporary and final restorations
List and describe the 4 classifications of glass ionomer cements
Type I: luting crowns, bridges, and orthodontic brackets
type IIa: esthetic restorative
type IIb: reinforced restorative
type III: lining cements, base
What is the composition of the conventional glass ionomer (GI)
basic composition- only acid-base reaction (a chemical reaction)
What is the composition of resin modified glass ionomer (RMGI)
- HEMA and/or other polymers added to the liquid component and/or silicate glass of composite added
DUAL setting a) resin polymerization (light cured)
b) acid-base reaction (chemical reactionO
what liquid is used in glass ionomers (GI)
Polycarboxylic/ polyacrylic acid IS THE LIQUID
what powder is used in glass inomers (GI)
Fluoroaluminosilicate (FAS) glass IS THE POWDER
Is water added in the composition of GI?
Yes, its helps with ion transport in the acid-base reaction and fluoride release.
Whats the function of tartaric acid in GI
tartaric acid helps to control the working time and the setting characteristics
what are the key players of the acid base reaction in GI>
the acid-base reaction takes place by the liquid and the powder.
The liquid is the polycarboxylic acid and the powder is the FAS glass.
List the steps of the setting reaction in GI
- Dissolution
- Gelation and inital setting
- hydration and maturation
What is the mechanism of adhesion in glass ionomers (GI)
well enamel and dentin both undergo a chemical interaction with dental structures. The mechanism of adhesion is ionic (chemical) due to bonds between carboxyl groups and calcium from hydroxyapatite
whats the difference in composition between RMGI and GI?
Theyre both the same up until the tartaric acid.
RMGI has two more things
1. Hydrophillic methacrylate monomers: photo-initiated/redox reaction
2. Free radical initiors- trigger curing of metharcylate groups
T or F, in RMGI the FAS (the powder) reacts with water-soluble methacrylate components into an aqueous solution of polyacrylic acid (the liquid)
yes
What are the mechanisms of adhesion in RMGI
there are two mechanisms:
1. Micro-mechanical interlocking
2. Ionic bonds between the carboxyl groups and calcium from hydroxyapatite
t or f: does polyacrylic acid increase the sealing ability and bond strength to enamel and dentin?
yes!
t or f: ALL TYPES OF GI ARE NOT indicated for stress bearing areas in permanent dentition
true.
does GI and RMGi have higher or lesser solubility when compared to resin composite?
higher solubility
between GI and RMGI which one has higher wear and solubility
GI has poor mechanical properties but HIGh wear and solubilty
release of flouride in resin modified materials has what kind of effect?
anticariogenic effect
What are class V lesions?
defects or lesions at the cervical third- facial or lingual of anterior or posterior teeth
Tooth-colored materials: the use of composite as a restorative material for _________ predominates in areas of esthetic concern
cervical caries lesions
Whats the etiology of cervical lesions?
- dental caries
- Non carious cervical lesions (NCCLs)
-abrasion
-abfraction
-erosion - Multifactorial
KEY*: assigning a cause to the problem is necessary in order to determine the proper treatment (prep and restorative material to use) for class V defects
What are non carious cervical lesion?
these are multifactorial and can be intrinsic and extrinsic. this includes erosion/biocorrosion, abrasion, abfraction.
causative factrs must also be addressed.
how can you prevent root caaries (primary prevention)?
in office fluroide varnihs/prevident at home, diet counseling, OHI
How can you arrest root caries (secondary prevention)?
silver diamine fluroide for caries arrest
How can you restore root caries (tertiary prevention):
restorative material: conventional GI
RMGI, atraumtic restorive treatment
For Class V lesions, what are the indications for amalgam?
poor isolation, esthetics not being a primary concern, difficult access for placement and finishing
For Class V lesions, when is GI indicated?
extensive carious involvement!
1. a patient with high caries risk
2. root caries
3. multifactorial cervical lesions
*Fluroide releasing restorative materials help to control and prevent recurrence of cervical decay
Did you know newer RMGI materials have good levels of fluoride release over longer periods. This is termed as capability of recharging (to prolong fluoride release. Recharching occurs with continued use of fluoride containing toothpastes
read
material selection for abfraction lesions should have a ______ modulus of elasticty
low modulus of elasticity
it is believed that the restorative material should be somewhat flexible or a stress reducing liner should be used to help resist the tendency for displacement of the restoration due to flexure of the tooth
list the material selection for abfraction lesions
microfilled resin, filled adhesive, flowable composite
what clamp should you should for gingival retraction for rubber dam isolation
212 gingival retraction clamp
different etiologies result in different restorative options
for caries: restore with ______
due to abfraction: restore with ________
caries: restore with GI
Abfraction: restore with mcrofill composite
for Class V preps, the depth should be uniform from mesial to distal BUT the depth should be greater as you move more
incisally/occlusally
axial wall is convex
You should change the orientation of the handpiece for class V as your progress from mesial to distal. Why?
the orientation of the enamel rods changes
In class V sclerotic dentin, what do you do?
Add extra retention! how? more grooves
where do you add the grooves? axiogingival and axioincisal line angles
for abfraction, you want to fracture away enamel at the cervical area due to flexure of the tooth under occlusal stress. do you or do you NOT bevel?
Yes, enamel margins are beveled.
which one do you bevel for . RMGI or resin composite
resin composite. no beveling for rmgi
What are non carious lesions?
erosion, abrasion, attrition, abfraction, dentin hypersensitivty
The loss of surface tooth structure by chemical action in the continued presence of demineralizing agents (acids)
Erosion
What is a chelating agent?
chelating agents can bind freed calcium ions after surface loss and prevent remineralization.
citric acid is a chelating agent
where does erosion most commonly occur
occlusal surfaces, predominantly mandibular first molars
and then facial surfaces of the anterior maxillary teeth
also maxillary incisors and canines
first sign of minimal erosion may include a _____
dull appearance
foods that are acidic but high in calcium do NOT lead to _____
do not lead to demineralization
what are salivas protective mechanisms against erosion
-dilution and clearance of acid
-buffering and neutralization
-providing calcium and phosphate
patients with salivary flow impairment demonstrate a higher risk for erosion (sjogrens syndrome)
In uncontrolled bulumia, do you or do you not brush immediately right after vomiting
do NOT
what is perimylolysis?
It is the erosion wear of the lingual surfaces of the maxillary anterior and posterior teeth. It is most frequent in maxillary incisors. second is maxillary molars.
physical wear as a result of mechanical processes involving foreign substances or objects
abrasion
how does abrasion appear in cervical areas?
v shaped grooves
the physical wear as a result of the action of opposing tooth to tooth contact
attrition
how does attrition appear clinically?
facets with well-defined margins
Physical wear of teeth as a result of tensile or shear stress in the cervical portion of the tooth
abfraction
usually due to occlusal interference or eccentric forces
what is dentin hypersensitivity
response to stimulus on exposed dentin
short, sharp pain arising from exposed dentine in response to stimuli
what is most common site of dentin hypersensitivty
cervical-buccal area is the most common site
canines and premolars are most affected
what is the mechanism of dentinal sensitivity
its the exposure and opening of dentinal tubules but the HYDRODYNAMIC THEORY explains that the presence and movement of fluid inside the dentinal tubules activates the nerve endings at the pulp-dentin complex
stimuli which tend to move the fluid away from the pulp-dentin complex produce more pain true or false
true
cooling, drying, evaporation,
pulpul dentin the tubulus are ___% surface area compared to surface dentin tubules with are ___%
pulpal dentin tubules: 22% of surface area
surface dentin tubules = 1% of surface area
adhesive resins can seal ______ effectively by forming a hybrid layer
can seal dentinal tubules
oxalate reacts with calcium ions and froms calcium oxalate crystals inside the dentinal tubules as well on the dentinal surface. whats the effect of this
reduces permeability and occludes dentinal tubules
GLUMA contains what two important things
HEMA and gluteraldehyde
what two reactions does GLUMA carry out for desensitization?
- Gluteraldehyde causes coagulation of albumin in the dentinal fluid which causes protein precipitation
- HEMA polymerization forms resin tags and occludes the dentinal tubules
t of f. Gluma affects bond strenth
false. it does not affect it
retentive grooves are placed in ____
dentin
