Dental Pulp 14
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Resin adhesion first achieved in what year?
1982, mechanical hybridization
Difference between resin and RMGI?
Mechanical (hydrophilic monomer layer) vs. Chemical bond
Acute effects of cavity prep?
Hydrodynamic effect of fluid flow within tubules
Tubule density increases from approx _______mm2 outer dentin to _______mm2 adajcent to pulp.
Peritubular dentin and Type 1 collagen?
Completely devoid of it, much smaller apatite crystals
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
Extent of tertiary dentin deposition appears to be:
the trauma of cavity prep vs. restorative materials
Thickness of mature dentin?
OD extend how far into tubules?
Deeper cutting (less than __mm from the pulp) results in direct OD injury
Acids are (able to/unable to) destroy highly croos-linked dentin Type 1 collagen,
evidence shows it is host derived, activated by acidic pH
What are whitlockite crystals?
magnesium-substituted tricalcium phosphate, occlude dentinal tubules in sclerotic dentin below affected dentin
What acids account for 90% found in carious dentin?
Lactic, acetic, proprionic
pH about 4.9
do not diffuse across dentin more than .6mm
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
Expression which proteins is assoc. with cytoskeletal reorganization of surviving ODs after injury?
Fibronectin-binding protein and nestin, found in apical areas of ODs
What proteins are invovled in the mineralixzation of the dentin matrix?
How many teeth prepped for full coverage go necrotic?
4-33% will need RCT
Pulpal necrosis occurs at a rate of about _% per year for single crowns?
Most influential variables in pulpal injury were found to be:
- Prep in abscense of coolant
- Restorationc choice in direct pulp cap
Two pulpal responses most sensitive to cavity RDT?
ODs survival and reactionary dentin secretion
ODs survival precents vs RDT?
- 100% >1mm
- 89% .5-1mm
- 83% .25-.5mm
- 68% <.25mm
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
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
Temp increases and effects on pulp?
inc of pulp temp of 5.5C irreversible injury
inc of 11C is necrosis
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
First dentin adhesion?
1982 by Nakabayashi
demineralize dentin, hydrophilic layer, hydrophobic layer
- 50% inorganic
- 30% organic
- 20% fluid
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
Self etching adhesives, steps?
- Apply acidic resin primer (penetrates smear layer) 15-20 secs and then dried
- Adhesive now cure
- Bulk resin
5th generation adhesive systems?
Combined primer and adhesive: single bottle adhesive systesms
etch-apply single bottle- two steps
6th generation adhesives?
Self-etching primer followed by adhesive
No etch (primer)+adhesive = two steps
7th generation adhesives?
etch+prime+adhesives all one step
Glass ionomers consist of:
alumina, silica, polyalkenoic acid
chemical and mechanical bond
mechanicl: milds acids cause microporosities created in dentin surface
Dynamic bond of glass ionomer?
bonds break, new ones reformed
process which fluids are absorbed by hydrophilic resins
resins swell, degrade mechanical properties
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
3 aspects effecting pulp during dentin bonding?
1. acid etching (dentin permeability)
2. resin cytotoxicity (esp RDT <.5mm)
3. microleakage (shrinkage, bonds weak)
Greatest concern using resins?
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%
Placement of RMGIs within ___mm of the pulp reduced ODs numbers by more than ___%
Most important factors in stimulation of reactionary dentin formation?
Trauma from prep and microleakage
With RDT less than .5mm areas occupied by reactionary dentin, material rated?
CaOH > Resin (dentin) > Resin (enamel) > RMGI > ZOE
Effectiveness of release of TGF-B1 by material rank
EDTA > Phosph acid > citric acid > polyacrylic > nitric acid
EDTA soluble dentin matrix protein prep
Rank of material ability to prevent microleakage:
RMGI > bonded amalgam > ZOE > bonded resin comp > GP > CaOH > compomer > silicate > zinc phosphate
Avg replacement time of resin?
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