Caries and Restorative Assalaam Alekum 15/4/2014 Pulpal reactions to Caries and Restorative procedures Dr. Gaurav Garg, Lecturer College of Dentistry, Al Zulfi, MU.

Pulpal reactions to caries Pulpal reactions to restorative Procedures Contents 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 implications. It means that pulp would react when dentin is injured whether the injury is caused by caries, attrition, abrasion, erosion or operative procedures.

Dentin Odontoblastic layer Cell Free zone Cell Rich zone

Dynamic Dental Pulp 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 Unhealthy reparative reaction Destructive reaction

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

Unhealthy reparative Reaction Degeneration of the 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 Odontoblasts will pave over this reparative dentin and form secondary 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 Necrosis

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

Pulpal reactions to Caries

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 Three basic reactions protecting pulp Decrease in dentin permeability Tertiary dentin formation 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 Tubular dentin Fibrodentin 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

Pulpal reactions to Local Anaesthetics

Effect on pulp 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

Pulpal reactions to Restorative procedures

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 restorative procedures causing pulp injury

Physical irritation from a procedure Heat Dessication Vibration

First principle to eliminate 2 sources of pulp injury is NEVER CUT DRY

Remaining Dentin Thickness 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

CR- Cell 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

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

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