Seminar 3: VPT Flashcards
What are the the 3 functions of the pulp ?
Formative: aids in formation of dentine
Defensive: immune and inflam response
Sensory: through a delta, a beta and C fibres
What happens during a defence reaction of a healthy pulp-dentine complex to e.g bacteria/trauma ?
Initial inflammatory response in pulp
Outflow of dentinal fluid
Temporary blockage of tubules by protein molecules in transudate
Sclerosis of tubules by mineral deposition
Tertiary dentine laid down
If the pulp is not able to cope with the oncoming bacteria / trauma what happens?
Death/Necrosis
What is the first line of sensory defence in the PDC?
A delta fibres
What effect does localised inflammation have in a delta fibres ?
It will reduce their threshold of activation leading to hypersensitivity
What is the second line of sensory defence in the PDC?
C fibres leading to deep seated pain
What role does TGF beta play in dentine formation?
Responsible for signalling odontoblast differentiation
Where’s does TGF beta become deposited in the dentine matrix ?
It is secreted by differentiated odontoblasts and becomes part of the calcified matrix. During caries which results in dissolution of the matrix TGF beta is freed up helps to signal dentine deposition from odontoblast
If the pulp injury is very severe where are odontoblasts recruited from?
Pulp mesenchymal pool
These are odontoblast like cells
What impact does damage to dentine have on the odontoblasts ?
Causes damage to the tight junctions causing them to become more permeable
By what methods can dentine become more permeable?
Acidic via caries or acidic oral environment
What two degenerative pulpal changes exist ?
Inflammation
Dystrophic calcification
What are the two types of dystrophic calcification ?
Coronal - usually smooth rounded
Radicular- usually irregular
What problems to calcifications cause during RCT?
- Surfaces which harbour bacteria
- they Can break off and cause blockages during RCT
List some factors that can cause pulpal injury
Pre op: TSL/ caries / trauma / resorption / systemic disease e.g hypophosphotaemia
Intra op: intra and extra coronal restorations / pulp exposure/ restorative materials/ortho
Post op: MICROBIAL LEAKAGE
What are the advantages of maintaining pulp vitality ?
Sensory feedback maintained
Protective and defensive via dentine fluid which also has Ig’s in
Formation of whitlockite crystals
Root development
What are the disadvantages of not maintaining pulp vitality ?
Loss of tooth tissue
Effect of chemicals of dentine e.g NaOCl reduced flexural strength of dentine
Loss of A beta fibres leads to loss of proprioception
What is found occupying space of dentine tubules ?
Odontoblast process and dentinal fluid
Which end of the dentinal tubule is wider?
Pulpal end (3 microns ) Surface near enamel (less than 1 micron )
How can dentine be classified ?
Peri/intra tubular or intertubular
Primary secondary tertiary
Where is peri/intra tubular dentine located ?
Lines the tubules - this increase in age
Less collagen and more mineralised dentine
Where is intertubular dentine located?
Between tubules
Forms the bulk of dentine
What percentage of dentine is comprised of dentinal tubules ?
Gulbivala et Al 2010
20-30%
Primary dentine is laid down when and what rate?
Until root formation complete
4 microns per day
Secondary dentine is laid down when and what rate?
After root completion
<1 micron per day
Tertiary dentine is laid down when and what rate?
Response to injury eg caries
3 microns per day
What are the types of tertiary dentine
Reactionary (laid down by original odontoblasts )
Reparative ( laid down by odontoblast like cells )
Pulp injury can either be direct or indirect. How do they occur?
Direct: damage direct to neurovascular bundle e.g trauma
Indirect: via pulp dentine complex
What effect do restorative procedures have on PDC?
LA with adrenaline - causes vasoconstriction through activation of alpha 1 receptors
Desiccation from air spray
Microbial leakage at the time and over time
Thermal: use of hand pieces
Chemical: acid etch
What negative effect does ZNO eugenol have on pulp?
Cox et al 2002
Murray et al 2002
May cause inflam If dentine not >0.5mm thick since eugenol can be toxic to pulp
What positive effect does ZNO eugenol have on pulp?
Murray et al and Cox et al 2002
Prevents micro leakage
Reduced pain
Antibacterial
What benefit does RMGIC have on pulp?
Performs well in preventing microleakage
What are the risks of using composites ?
Cox et al and Murray et al 2002
Polymerisation shrinkage
Hydrolytic degradation over time leading to leakage
Etch can cause tubules to open causing bacterial ingress
Unreacted monomers cytotoxic
Benefit of GIC in deep restorations ?
Tolerated well esp when less than 0.5mm dentine
Released fluoride
Benefit of amalgam restorations ?
Corrosion products prevent microleakage
Risks of amalgam?
Thermal conductivity - deeper base
Condensation pressure can cause inflammation
Why does caries progress sideways along CEJ?
Because the mantle layer is present and it is less mineralised and organised
Starting from the EDJ what are the zones of dentine caries?
Destruction
Invasion
Demin
Tubular sclerosis
What is the critical pH of enamel ?
5.5
What is the critical pH of dentine
6.7
What role do whitlockite crystals form?
Formed by calcium and phosphate ions released from demineralisation and bind together forming crystals which reduce permeability of tubules preventing further bacterial ingress
What is the premise of vital Pulp therapy based on with regards to infected and affected dentine?
Deepest layer of dentine is not infected
Inner Softened layer of caries has collagen not affected by bacterial proteases and can remineralise and protect pulp
At that depth of caries is pulpal inflammation seen?
Once within 0.8mm of pulp floor
What are the types of vital pulp therapy?
Direct
Indirect
What are the types of indirect VPT?
ART
STEPWISE (2 stage)
DIRECT COMPLETE (1 stage)
What are the types of direct VPT?
Pulp cap
Partial pulpotomy
Full pulpotomy
What stage of inflammation must the pulp be in for VPT to work?
Reversible
What procedural requirements are there for VPT?
Sterility through RD
Irrigate cavity with NaOCl
What role does EDTA and CaOH play in VPT?
They stimulate growth factors to be released from the dentine matrix
EDTA intensifies the response from dentine by solubising the growth factors
What are the risks of using caries detector dyes in caries removal?
Does not discriminate infected vs affected dentine so can lead to over prep
What is the difference between hard and firm dentine?
Hard: resistant to probing
Firm: probed but not removed with hand instrument
Soft: removed with hand instrument
When would you carry out ART?
Limited resources
Places firm reliance of quality of the seal
In direct complete / one stage VPT how much caries is left?
Only residual caries (this is caries if removed would expose the pulp)
Clean all walls
If the remaining dentine left following caries removal is suspected to be less than 0.5mm thick what material would you place?
Biodentine
RMGIC
GIC
What is the benefit of biodentine over MTA
Faster setting time
No bismuth oxide so no staining
How does two stage differ from one stage caries removal ?
Re enter in 8-12 weeks and place definitive restoration
Carry out a final hand excavation after re entry
How do you carry out a partial pulpotomy?
Removal of inflamed coronal tissue and seal with MTA/CaOH with aim of forming hard tissue barrier which takes 3-6 months
How is haemostasis achieved in partial pulpotomy?
Irrigation with low concn NaOCl eg 0.5% which is antibacterial but does not destroy pulp tissue
What is important with partial pulpotomy with regards to proximity of material and the remainder of pulp?
No clot between as this can affect healing
How long should it take for haemostasis to occur in partial pulpotomy
Within 1-10 mins
If longer then remove more pulp
How much pulp is removed in a Cvek Pulpotomy?
2mm coronal pulp - this removes superficial layer and helps retain the CaOH
How much pulp is removed in a full pulpotomy ?
All coronal pulp with aim of retaining radicular pulp for root development
What are the disadvantages of VPT?
Obliteration can occur
Can complicate treatment later on
May get staining with MTA
Pain/unpredictable
Resorption can be seen in cases of trauma
Can be difficult to decide when to place extra coronal restoration
Why do younger patients respond better to VPT?
Pulp free of age related changes
Wide spices
Enhanced blood supply
How can you assess outcome of VPT?
Clinically - symptoms
Radiographs- denture bridge , root completion, No path present
Physiometric test: laser Doppler and pulse oximetry
Histology : following xla
Success rates for direct vital pulp therapy are?
73-99% and more successful in young patients
Success rates for indirect vital pulp therapy are?
62% one stage (more likely to have pulp exposure )
74% stepwise
How long does it take calcific bridge to form?
4 weeks
How long for reactionary dentine?
4 weeks
How long for reparative dentine for form?
6 weeks
How long to see radiological changes?
6 months
What are some ideal features of pulp capping materials ?
Maintain vitality
Non toxic
Radiopaque
Promote tertiary dentine formation
What are the benefits of using CaOH as a pulp cap material ?
Aids in formation of dentine bridge
High pH
Aids in release of bio active molecules
How does CaOH aid in formation of dentine bridge?
- Direct contact with pulp causes caustic injury with a superficial layer of necrosis
- inflammatory cells migrate to the area and fibroblasts which lay down a fibrodentinal matrix which then becomes mineralised
What is the main disadvantage of using CaOH?
Soluble !
Benefit of using ZOE in pulp cap?
Prevents microleakage and bactericidal
What are the disadvantages of ZOE in vital pulp therapy cases?
Cannot use in combination of RBC
No dentine bridge formation
Less superior results than CaOH
Can cause pulp necrosis
What are the risks of using composites as pulp cappers?
No long term data
Etch opens tubules facilitating bacterial ingress
No dentine bridge formed
Minimises toxic to pulp
What is the benefit of RMGIC in pulp capping ?
Chemical bond to dentine
Works well in close proximity but NOT direct contact with pulp
Disadvantages of RMGIC in pulp caps?
No bridge formation
Benefit of using corticosteroids in direct pulp cap?
Reduced pain and inflammation
Risks of corticosteroids in direct pulp cap
No dentine bridge formation
Reduced immune response
May give false impression that pulp cap worked as pain is controlled
Also steroids reduce connective tissue growth
What is the risk when using steroids in pulp capping?
Dampens immune response facilitating further bacterial ingress which is why the antibiotic is added
What is the benefit of MTA in pulp caps ?
Bioactive CaOH is released Extracts growth factors from dentine Less soluble than CaOH Alkaline pH sustained
Risk of using MTA in pulp capping ?
Stains
Expensive
Long setting time
Advantage of biodentine over MTA
Interface between biodentine and dentine greater than that of MTA and dentine
Shorter setting time
What type of materials are biodentine and MTA
Tricalcium silicate
What benefit do statins have in pulp caps
Promotes angiogenesis
Promote mineralisation
Comparing survival rate between CaOH and MTA which performs better?
82% 5 year survival CaOH
97% 9 year Survival MTA
