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Resin adhesion first achieved in what year?
1982, mechanical hybridization
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Difference between resin and RMGI?
Mechanical (hydrophilic monomer layer) vs. Chemical bond
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Acute effects of cavity prep?
Hydrodynamic effect of fluid flow within tubules
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Tubule density increases from approx _______mm2 outer dentin to _______mm2 adajcent to pulp.
20,000-45,000
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Peritubular dentin and Type 1 collagen?
Completely devoid of it, much smaller apatite crystals
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Carious dentin and two layers, describe?
Demineralized, bacteria infected dentin
Deeper, affected layer that includes a transparent zone in which tubules are occluded by mineral deposits
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Extent of tertiary dentin deposition appears to be:
the trauma of cavity prep vs. restorative materials
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Thickness of mature dentin?
3mm
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OD extend how far into tubules?
.1mm-1mm
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Deeper cutting (less than __mm from the pulp) results in direct OD injury
.3mm
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Acids are (able to/unable to) destroy highly croos-linked dentin Type 1 collagen,
unable to
evidence shows it is host derived, activated by acidic pH
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What are whitlockite crystals?
magnesium-substituted tricalcium phosphate, occlude dentinal tubules in sclerotic dentin below affected dentin
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What acids account for 90% found in carious dentin?
Lactic, acetic, proprionic
pH about 4.9
do not diffuse across dentin more than .6mm
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Depth of cavities and immune response?
Innate immunity dominates in shallow caries, bacteria are too far for adaptive phagocytosis
Transition from innate to adap occurs in irreversibly inflamed pulps separated by less than 2mm deep carious dentin
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Expression which proteins is assoc. with cytoskeletal reorganization of surviving ODs after injury?
Fibronectin-binding protein and nestin, found in apical areas of ODs
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What proteins are invovled in the mineralixzation of the dentin matrix?
SIBLING
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How many teeth prepped for full coverage go necrotic?
4-33% will need RCT
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Pulpal necrosis occurs at a rate of about _% per year for single crowns?
1
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Most influential variables in pulpal injury were found to be:
- RDT
- Prep in abscense of coolant
- Restorationc choice in direct pulp cap
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Two pulpal responses most sensitive to cavity RDT?
ODs survival and reactionary dentin secretion
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ODs survival precents vs RDT?
- 100% >1mm
- 89% .5-1mm
- 83% .25-.5mm
- 68% <.25mm
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Greatest reactionary dentin secretion vs. RDT?
292% inc in .25-5mm
- less growth factors diffusing more than .5mm
- less than .25mm causes too much injury to ODs
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Describe heat shock proteins?
enhance ability of cells to withstand stress and signal upreg of defense and reparative responses during cellular injury
help cells resist injury
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Temp increases and effects on pulp?
inc of pulp temp of 5.5C irreversible injury
inc of 11C is necrosis
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Extent of intrapulpal heat generated determined by?
- Use of coolants
- Rotation speed
- Size, type, shape of cutting instru
- length of time in contact with dentin
- amt of pressure of handpiece
- cutting technique
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First dentin adhesion?
1982 by Nakabayashi
demineralize dentin, hydrophilic layer, hydrophobic layer
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Dentin composition?
- 50% inorganic
- 30% organic
- 20% fluid
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Etch and rinse adhesives, steps
- 30-40% phosp acid 15secs (5-8um demin)
- Rinse and apply primer (hydrophilic)
- Air to evap acetone or alcohol vehicle
- Apply adhesive (hydrophobic) cure
- Bulk resin
this is 4th generation
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Self etching adhesives, steps?
- Apply acidic resin primer (penetrates smear layer) 15-20 secs and then dried
- Adhesive now cure
- Bulk resin
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5th generation adhesive systems?
Combined primer and adhesive: single bottle adhesive systesms
etch-apply single bottle- two steps
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6th generation adhesives?
Self-etching primer followed by adhesive
No etch (primer)+adhesive = two steps
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7th generation adhesives?
Combines everything:
etch+prime+adhesives all one step
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Glass ionomers consist of:
alumina, silica, polyalkenoic acid
chemical and mechanical bond
mechanicl: milds acids cause microporosities created in dentin surface
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Dynamic bond of glass ionomer?
bonds break, new ones reformed
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Plasticization?
process which fluids are absorbed by hydrophilic resins
resins swell, degrade mechanical properties
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Application of MMPs to dentin bonding procedures, limitations why?
1. CHX delays or arrests MMPS?
2. MMPs only work on etch and rinse but not in self etching adhesives
3. CHX cytotoxicity and RDT less than .2mm
4. what about cysteine cathepsins?
5. a zone of resin sparse demineralized dentin always remains
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3 aspects effecting pulp during dentin bonding?
1. acid etching (dentin permeability)
2. resin cytotoxicity (esp RDT <.5mm)
3. microleakage (shrinkage, bonds weak)
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Greatest concern using resins?
microleakage
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Survival rates of ODs to materials:
- CaOH 100%
- Polycarb 81.8%
- ZOE 78.4%
- resin to dentin 74.2%
- Enamel bonding resin 48.3%
- RMGI 43.1%
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Placement of RMGIs within ___mm of the pulp reduced ODs numbers by more than ___%
.5mm
50%
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Most important factors in stimulation of reactionary dentin formation?
Trauma from prep and microleakage
VS
material cytotoxicity
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With RDT less than .5mm areas occupied by reactionary dentin, material rated?
CaOH > Resin (dentin) > Resin (enamel) > RMGI > ZOE
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Effectiveness of release of TGF-B1 by material rank
EDTA > Phosph acid > citric acid > polyacrylic > nitric acid
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ESDP?
EDTA soluble dentin matrix protein prep
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Rank of material ability to prevent microleakage:
RMGI > bonded amalgam > ZOE > bonded resin comp > GP > CaOH > compomer > silicate > zinc phosphate
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Avg replacement time of resin?
5.7yrs
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