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Aim of vital pulp therapy
stimulate formation of tertiary dentin (could be reparative or reactionary [surviving postmitotic OD])
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Pulp vulnerable to injury because (3)?
1. large vol of tissue, small vol of blood
2. terminal circulation, limited collateral
3. low compliance
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Describe the Kakehashi study?
Germ free rats w/ expose pulps, no inflammation but dentin bridge formation (32 days)
Reg rats partial necrosis (8 days) and complete in (14 days).
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Two issues modify pulp healing...
1. duration of pulpal exposure
2. abilty of material to seal vs. toxicity (both found to be important)
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Success of Ca(OH) pulp capping is reduced from ____ to _____ when microbial contamination is extended from _ hour(s) to _ days.
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1971 Brannstrom and Nyborg findings?
microleakage is greatest threat to pulp
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Pulpal devitalization following restorative procedure is likely to result from?
- Combined
- 1. bacteria (main factor)
- 2. mechanical injury
- 3. depth of cavity
- 4. toxicity of materials
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Pulpal mechanism to reduce bacterial invasion?
- 1. outward fluid flow
- 2. neutrophils
- 3. toxic substance sequester by binding to dentin
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What did Bergenholtz review/find?
Thin wall of primary dentin often prevents effects of toxic materials and bacterial leakage
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In regards to size of pulpal exposures, many dentists belive that...
pulp capping is most successful when exposure is less than 1mm in major dimension and patient is young
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Contrary to what dentist believe to size of pulpal exposure, it has been found that with partial pulpotomies:
96% success rate with 31 month follow-up and exposures ranged from .5-4mm
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Ca(OH) and macrophages?
inhibits funciton of and reduces inflammatory reaction
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Need for hemorrhage control in pulp capping?
first invesitgated by Marzouk and Van Huysen in 1966,
inhibits wound healing
shown to be successful with saline, NaOCl, CHX
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__% of pulps irrigated with NaOCl prior to adhesive placement showed normal soft tissue reorganization and dentin bridge.
86
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Dentin bridge formation is found in __% to __% of teeth treated with various Ca(OH) formulas.
50-87
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What is the reduction of pulp when CaOH is used to cap?
caustic pH causes up to .7mm reduction
still used because antimicrobial
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Describe the SEM of dentin bridge formed by CaOH, layers?
Superficial layer: amorphous layer of tissue debris
Middle layer: coarse meshwork of fibrodentin (most mineralized layer)
Inner layer: osteodentin
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A summary of several primate studies shows what defects in dentin bridge by CaOH?
Tunneling defects, in 90% of 192 dentin bridges, possible leakage route
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For successful vital pulp therapy, the healing process must exhibit these 3
1. rapid formation of hard tissue
2. barrier formation against 2nd pulp infections
3. induction of hard tissue at material/pulp interface
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Genes/expression of difference in healthy vs diseased pulp?
85 genes vs. 360
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What signaling pathway controls fate of multipotent stem cells?
Notch: CaOH pulp cap in adult rats
Notch 2: inc in coronal odonto
Notch 3: inc in area of PV cells
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CaOH placement inc these ECM proteins that help with cell adhesion.
Fibronectin and tenascin
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Pulp cells synthesize this in response to minor temp change?
LTB4
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RMGI as pulp capping material?
Great in primates (2yr follow up) but not the same in human teeth
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Why are dental adhesives not recommend for pulpcapping?
Persistent intense inflammation and foreign body reactions
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Many of the resin components empolyed in etch-and-rinse and self etching dentin adhesives are __________?
vasorelaxants
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Calcific metamorphosis:
Mineralized tissue extension from the exposure site into the body of pulp
Seen with MTA
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Most efficient bioactive molecule that induces homogenous and well mineralized reparative dentin?
Bone sialoprotein BSP
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What two major growth factors are implicated in OD activity?
TGF-B1 released from demineralized dentin
NGF released from pulp
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Dental pulp repair by implantation of bioactive molecules implies a cascaed of four steps:
1. mod inf
2. commitment of adult reserve stem cells
3. prolif of stem cells
4. terminal diff of stem cell
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1969 Keyes describes 3 factors essential to caries:
1. susceptible host
2. cariogenic bugs
3. suitable substrate
all work stimulaneously
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Caries penetration rate of dentin?
1mm every 6 months
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When bacterial penetration come within ___mm of the pulp or when the bacteria ____ previously formed ____ dentin, the degree of pulpal disease becomes _________.
.75
invade
reparative
irreversible
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Reason for abript change in .75mm of dentin?
Bacteria by-products can overhwhelm the pulp, if all caries are removed except for this superficial layer then the tooth will heal.
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Success of resin comp indirect pulp cap is dependent on (2 factors):
1. abilty of pulp to respond to material
2. sealing ability (total etch and total seal)
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What is the atraumatic restorative technique (ART)?
Caries is removed with hand instruments and restored with GI.
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Similar to MMPs what has been found to degrade comp bonds in indirect pulp caps?
Cysteine cathepsins
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Describe stepwise excavation?
6 months after indirect pulp cap over affected dentin (carious) is verified having been arrested and any darker dentin removed and resealed.
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