Assalaam Alekum
15/4/2014
Dr. Gaurav Garg, Lecturer
College of Dentistry, Al Zulfi, MU.

• Introduction
• Cells of the pulp
• Pulpal reactions to caries
• Pulpal reactions to restorative Procedures

Introduction
 Embryologically and physiologically Dentin and pulp are so intimately related that dentin can be considered as the peripheral calcified portion of the dental pulp.
 However This intimate relation extends beyond embryological and physiologic considerations.
 It has important clinical

Dentin
Odontoblastic layer
Cell Free zone
Cell Rich zone

• Responds to external stimuli in a variety of ways
• Ability to form dentin throughout life
• Potential for regeneration and repair diminishes with age
• Very sensitive to thermal stimuli
• Encased in a low compliance environment
• Scarcity of collateral circulation

Cells of the Pulp
• Formative cells ( odontoblasts, fibroblasts )
• Defense cells ( Histiocytes , Lymphocytes )
• Reserve cells (undifferentiated mesenchymal cells)

MODES OF IRRITATION TO PULP
• 1. DIRECT-
• Direct irritation to the pulp-Dentin organ- Carious/ iatrogenic pulp exposure
• Allows direct access for the oral flora and other irritating ingredients
• 2. INDIRECT-
• Irritating toxins/chemicals enter through the dentinal tubules

Reaction of the pulp-Dentin organ to stimulation/irritation

Healthy reparative Reaction
• Most favorable response
Sclerotic dentin and/or calcific barriers followed by
Normal secondary dentin
Healthy reaction occurs without any disturbances in the pulp

odontoblasts
Dead tracts
Complete cessation in formation of secondary dentin
Accompanied by mild pathological and clinical changes of reversible nature
Irregular type of tertiary dentin –
Irritation dentin

A – Dead tracts
C – Reparative dentin

Limitations of tertiary dentin
• Permeable
• Reduces the capacity for further defensive action
• Less elastic than primary dentin

Destructive Reaction
• Most unfavorable response
Loss of odontoblasts/outer protective layer
Involvement of pulp tissue proper
Inflammation
Chronic inflammation/Abcess formation

T- stained tubules
A- abcess
CI- cellular infiltration
V- calcified vessels and hard tissue formation

Dental caries Facts
• Localised , Destructive and Progressive infection
• Destroys dentin at a rate of 1mm/six months
• Foci of pulpal inflammation occurs when caries is within 750 microns from the pulp

Pulpal Reaction to caries
protecting pulp
1.
Decrease in dentin permeability
2.
Tertiary dentin formation
3.
Inflammatory & Immune reactions

Dentin permeability -
Importance
• Channels of diffusion – Dentinal tubules
• More no of tubules per unit area towards pulpal side as compared to peripheral dentin
• Fluid permeation is proportional to Tubule diameter and number
• Clinical importance – Dentin beneath a deep cavity preparation is more permeable than dentin underlying a shallow cavity

Decrease in dentin permeability
• First defense to caries – SCLEROTIC DENTIN
Combination of
•
An increased deposition of intratubular dentin
•
Direct deposition of mineral crystals (Whitlokite) into narrowed dentinal tubules

Whitlockite crystals

Tertiary Dentin
• Occurs over a Longer period than does sclerotic dentin
• Mild stimuli quiescent odontoblasts
Reactionary Dentin
Observed when initial dentin demineralisation occurs beneath non cavitated enamel lesion

Tertiary Dentin
Tertiary Dentin

Tertiary Dentin
• Aggressive lesion cytocidal to odontoblasts
Repopulation of the disrupted odontoblast layer
Reparative dentin
Tubular dentin Fibrodentin

Pulpal Immune Response
• Early response is characterised by focal accumulation of chronic inflammatory cells
• Mediated initially by odontoblasts and later by dendritic cells
Progressive inflammation

• Intact pulpal blood flow is critical
• Dental pulp is enclosed in a rigid chamber and cannot benefit from collateral circulation
• Reduction of blood flow – Reduction in clearance of large molecular weight toxins or waste products
• Anaesthetic delivered through an intra osseous route or periodontal ligament route can compromise the inflamed pulp’s ability to heal by reducing the blood flow

restorative procedures causing pulp injury
Tooth Preparation (Restorations/ Crown)
Acid Etching
Chemicals from restorative materials (Cements/ Bases)
Lasers
Effects of Caries, Microleakage, Restorative procedures and materials is Cumulative

Physical irritation from a procedure
•
Heat
•
Dessication
•
Vibration

• First principle to eliminate 2 sources of pulp injury is

•
Most critical factor in determining the intensity of pulp reaction is RDT
•
2mm of RDT provides adequate protection
•
So it is advocated that if RDT < 2mm
USE OF A PROTECTIVE BASE IS MANDATORY

Effect of Hand instruments
•
Sharp hand cutting are most biologically accepted wherein the energy used is completely dissipated in the actual cutting
•
Excessive pressure in decreased effective depths causes aspiration of the odontoblasts

CRCell rich zone
Aspirated odontoblasts

Effect of Rotary instruments
•
Rotary abrasive instruments (stones) are not recommended for cutting in vital dentin, as their abrasive action will elevate the temperature of surrounding dentin. It may crush vital dentin
•
It should be confined to enamel
•
•
Rotary cutting instruments (burs) are biologically acceptable if used over RDT of 2mm or more
Carbides provides more cool cutting

Other factors to be considered
•
Extensiveness and Duration of preparation time is directly proportional to extensiveness of the reaction of the pulp dentin complex

1. Pathways of pulp tenth-edition- Stephen Cohen
2. Endodontics-sixth edition- Ingle
3. Endodontics- Franklin S. Weine
4. Textbook of Endodontics- Walton Torabinezad