pulpal reactions to dental caries and dental proceudres

PULPAL REACTIONS TO CARIES AND DENTAL PROCEDURES

DR. SAJJAD HUSSAIN

DEMONSTRATOR PROSTHODONTICS ISLAMIC INTERNATIONAL DENTAL COLLEGE

ISLAMABAD

TOPIC OUTLINE

• Pulpal Reactions to CARIES• Pulpal Reactions to LOCAL ANESTHETICS• Pulpal Reactions to RESTORATIVE PROCEDURES.• Pulpal Reactions to RESTORATIVE MATERIALS.• Pulpal Reactions to LASER PROCEDURES• Pulpal Reactions to CAVITY PREPARATION USING AIR ABRASION

TECHNIQUES.• Pulpal Reactions to VITAL BLEACHING TECHNIQUES.• Pulpal Reactions to PERIODONTAL PROCEDURES.• Pulpal Reactions to ORTHODONTIC SURGERY.• Pulpal Reactions to IMPLANT PLACEMENT AND FUNCTION.

1. PULPAL REACTION TO CARIES

Protective pulpal reactions include ;1)- Decrease in dentin permeability.2)- Tertiary dentin formation.3)- Inflammatory and immune reactions.

PULPAL REACTION TO CARIES

1) - Decrease in dentin permeability:It is the first & fastest defense to caries and is called Dentin Sclerosis.Increase the deposition of mineral crystals in intratubular dentin → narrowing the dentinal tubules → decreasing dentin permeability


1) - Decrease in dentin permeability:

It is the first & fastest defense to caries and is called Dentin Sclerosis.Increase the deposition of mineral crystals in intratubular dentin → narrowing the dentinal tubules → decreasing dentin permeability


2) - Tertiary dentin formation:It is not the most effective pulpally mediated defense.

MECHANISM; Acidic byproducts of the carious process → degrade the dentin matrix →liberate bioactive molecules sequestered during dentinogenesis → reassume their role in dentin formation.


• 2) - Tertiary dentin formation:


2) - Tertiary dentin formation:The resultant dentin character is highly dependent on the stimulus.

In Mild Carious Lesion, odontoblasts are activated to elaborate the organic matrix of dentin (reactionary dentin), which is similar in morphology to physiologic dentin and may only be apparent due to a change in the direction of the new dentinal tubules.


2) - Tertiary dentin formation:

In Aggressive Carious Lesion, repopulation of the disrupted odontoblast layer with differentiating progenitors, forming reparative dentin, its morphology can range from organized tubular dentin to more disorganized irregular fibrodentin.


3) - INFLAMMATORY AND IMMUNE REACTIONS:

In the advancing infection front of the carious lesion, multiple extrinsic and intrinsic factors that stimulate inflammatory reactions,provides cellular and humoral challenges to invading pathogens.

N.B: The buffering capacity of dentin fluid likely attenuates the pH before it can directly effect a deleterious response, except when the remaining dentin thickness is minimal.



The early inflammatory response can be seen beneath non cavitated lesions and noncoalesced pits and fissures.It is characterized by the focal accumulation

of chronic inflammatory cells.


3) - Inflammatory and immune reactions: It is mediated; Initially by odontoblasts; the most peripheral

cell in the pulp, and encounter foreign antigens first.

& later by dendritic cells, which are responsible for antigen presentation and stimulation of T- lymphocytes.


3) - Inflammatory and immune reactions: Two distinct populations of dendritic cells: •CD11c+ found in the pulp/dentin border and

subjacent to pits and fissures. •F4/80+ concentrated in the perivascular

spaces in the sub-odontoblastic zone and inner pulp.



Odontoblasts play a role in the humoral immune response to caries. Immunoglobulin IgG, IgM, and IgA have been localized in the cytoplasm and cell processes of odontoblasts in human carious dentin, suggesting that these cells actively transport antibodies to the infection front.



N.B: In the most advanced phase of carious

destruction, the immune response is accompanied by immuno-pathologic destruction of pulpal tissue.

2 - PULPAL REACTION TO LOCAL ANESTHESIA

VASOCONSTRICTORS:

• Such as: lidocaine and 1:100,000 or 1:80,000 epinephrine.

• Benefits: enhance the duration of anesthesia.

• Side effect: reduce the blood flow of the pulp.

N.B: The supplemental anesthetic techniques cause more severe reduction or even transient cessation of pulpal blood flow.

2 - PULPAL REACTION TO LOCAL ANESTHESIA

N.B: The effect of intrapulpal anesthesia on the pulp is not considered, since it is used during root canal therapy when other anesthetic administrations are insufficient.

• However, during pulpotomy in tooth with immature apex, no difference was detected on follow-up of over 24 weeks after administration of intrapulpal anesthesia that contain epinephrine.

3 - PULPAL REACTION TO RESTORATIVE PROCEDURE

One key requirement of a successful restorative procedure maintaining the pulp vitality is to cause minimal additional irritation of the pulp so as not to interfere with normal pulpal healing.

Pulp reaction to restorative procedure is controlled by: 1.Degree of Pretreatment Pulp Inflammation. 2.Degree of Physical Irritation 3.Biologic and Chemical Irritation 4.Proximity of Restorative Procedures to Pulp

III. PULPAL REACTION TO RESTORATIVE PROCEDURE

1) Degree of Pretreatment Pulp Inflammation: In the absence of severe spontaneous symptoms or pulp

exposure, the clinician cannot accurately determine the degree of preoperative pulpal inflammation. Thus, every effort should be made to minimize added irritation during restorative procedures.

In cases of aseptic mechanical exposures, exposure longer than 24 hours associated with the formation of a bacterial biofilm that is difficult for the pulpal immune responses to eliminate.


2) Degree of Procedure Physical Irritation:

• Heat: Any restorative procedures leads to

increase in pulpal temperatures In case of 10° C rise → irreversible pulp pathosis In case of 20 C rise → pulp abscess

formation

Gradual controlled heat application over a large area may not cause adverse reactions in the pulp.

If the cavity floor ≤ 0.5 mm from the pulp, areas of coagulation necrosis could be detected.


2) Degree of Procedure Physical Irritation

• Desiccation:• It is the aspiration of

odontoblastic nuclei into dentinal tubules.

• It is transient, within 7 to 30 days there is autolysis of the aspirated cells and formation of reactionary dentin.

• The pulp in cases with aspirated odontoblasts, following desiccation for 1 minute, was not sensitive to clinical scraping with an explorer.


3) Biologic and Chemical Irritation: The sources of microbial irritaion: cariogenic microorganisms remaining on cavity floor. contamination with salivary microorganisms. contamination with bacteria from water lines.

Prompting the use of cavity disinfection (chemicals irritation), and so the most common irritant is etching agents.


N.B: Once dentin is exposed, there is constant

outward flow of dentinal fluid that minimizes the inward flow of any noxious agents. this may aid in the reduction of irritation from residual microbial factors in dentinal tubules.

III. PULPAL REACTIONS TO RESTORATIVE PROCEDURES

4) Proximity of Restorative Procedures to Dental Pulp & Surface Area of Dentin Exposed =

Depth and/or Width of a Tooth Preparation

There is an reaction, with a greater likelihood of the pulp undergoing irreversible pathosis, as the carious lesion progresses towards the pulp, particularly when the remaining dentin thickness (RDT) is less than 0.5 mm.

III. Pulpal reaction to restorative procedure

4) Proximity of Restorative Procedures to Dental Pulp & Surface Area of Dentin Exposed: = Depth and/or

Width of a Tooth Preparation:

N.B: With the passage of time following cavity preparation,

there is reduction in the permeability of RDT, due to rapid deposition of reactionary dentin, the migration of large proteins into the tubules, and/or the diminution of tubule diameter as dentin becomes more sclerotic.


5) Permeability of remaining dentin & related odontoblastic :

The dentin is not uniformly permeable, and that permeability depends on factors such as;

a) The location within the same tooth the

pulp. b) The age of the patient. c) The presence of pathologic conditions.


5) Permeability of remaining dentin and related odontoblastic :

a) The location within the same tooth: The tubular diameter increases from about 0.6 to 0.8

μm close to the DEJ to about 3 μm at the pulp. Given that bacterial cells are about 0.5 to 1 μm in diameter, it is evident that in deep cavity preparations, particularly when total-etch procedures are employed, bacteria can migrate through the remaining dentin into the pulp.


5) Permeability of remaining dentin and related odontoblastic :

b) The age of the patient,: The width of peritubular dentin increases with

age, causing reduction in tubular lumen or sclerosis.

III. PULPAL REACTION TO RESTORATIVE PROCEDURES

5) Permeability of Remaining Dentin and Related Odontoblastic :

c) The presence of pathologic conditions such as dental caries.

• In superficial dentin, formation of caries crystals within the tubules of inner undemineralized dentin → decrease in permeability in dentin.

• Related odontoblasts, it was shown that irritation from cavity preparation increased the odontoblastic permeability only at the site of the cavity preparation


5) Permeability of Remaining Dentin and Related Odontoblastic :

N.B: In addition to the physical barrier to permeability

and the production of reactionary or reparative dentin, the odontoblastic layer may in fact contribute to the host response of the dental pulp by expressing important inflammatory mediators or recognize bacteria through toll-like receptor


6) Patient Age:

• Resting pulpal blood flow (PBF), • Response to cold application, decrease with

age. • Reduction in pulpal neuropeptides.

IV. PULPAL REACTION TO RESTORATIVE MATERIALS

1) - Direct Effects 2) - Indirect Effects 1) Direct effects of restorative materials:• Certain cytotoxic components of resin monomers

(Triethylene glycol dimethacrylate & 2-hydroxyethyl methacrylate).

• Some of the components of resin restorations are released at cytotoxic levels after polymerization is completed.


These chemicals have either: A short lived and in the absence of bacteria,is reversible

Or Irreversible prolonged cytotoxicity,stimulation of

hypersensitivity reactions, or impairment of the host immune response to bacteria.

N.B:•Subtoxic concentrations of certain agents are capable of

eliciting allergic reactions in humans.


2) Indirect effect of restorative materials: The technique sensitivity of certain materials

predisposes them to faulty bonds to tooth structure that can translate to dentin hypersensitivity, recurrent disease, and pulpal inflammation or necrosis.


During the etching process:The more highly mineralized peritubular dentin is preferentially dissolved, leaving free collagen fibrils and opening lateral tubular branches. Applied resin infiltrates the exposed collagen mesh, creating a layer5 to 10 μm thick referred to as the hybrid layer.

• If the preparation is too dry, the collagen fibrils collapse.

N.B:The optimal degree of hydration of the preparation surface can

vary from material to material.


N.B:• It is recommend to rehydrate the fragment

segment of the tooth prior to bonding, to increase the mechanical and the microbial seal.

• This is particularly important with a complicated crown fracture where the pulpal protection by intact dentin is absent.


Pulpal irritation is not considered a negative sequela all the time, the irritant potential ofcertain restorative materials has a usefulmotivated effect on odontoblasts in case of direct & indirect pulp capping.

The outcome of such treatments depends on:

•The biocompatibility of used medicaments.•The ability to seal the cavity.•A combination of the above.•Ability to control hemorrhage at the exposure site.


• For example:

• Calcium Hydroxide• Zinc Oxide Eugenol • Mineral Trioxide Aggregate • Hemostatic Agents• 2% chlorhexidine or 5.25% sodium

hypochlorite


CALCIUM HYDROXIDE

In direct pulp capping: It induces the formation of dentinal bridge

•Aqueous suspensions preparation: causes superficial necrosis of pulpal tissue followed by tissue displaying low-grade inflammation .Within 30 days, the tissue subjacent to the necrotic zone has reorganized and resumed normal architecture.

•Hard-setting preparation: is effective in eliciting dentinal bridge formation with a much smaller to nonexistent necrotic zone.


CALCIUM HYDROXIDE: In indirect pulp capping:

•The Application of calcium hydroxide to intact dentin appears to induce sclerosis by promoting crystal precipitation within the tubules, accompanied by reductions in permeability.

•The irritation potential is dependent on the remaining dentin thickness and permeability.


MATERIALS CONTAINING ZINC OXIDE AND EUGENOL:

ZOE is used for;• Anesthetic properties:

It has been shown to block transmission of action potentials in nerve fibers & suppress nerve excitability in the pulp when applied to deep excavations.

• Antiseptic properties:It inhibits bacterial growth on cavity walls.

• Sealing ability:It has good adaptation to dentin.


DIRECT PULP CAPING WITH MTA

Mineral Trioxide Aggregate (MTA):

Indication: • In pulps with traumatic or

carious exposure, for allowing the formation of a reparative dentin bridge and maintain continued pulp vitality.


DIRECT PULP CAPING WITH MINERAL TRIOXIDE

Mineral Trioxide Aggregate (MTA):

•At 1st week, no sign of necrosis close to the exposure site, and odontoblast-like cells are observed at the periphery with the deposition of calcified bridge.•At 2nd weeks, complete calcified bridge formation just below the exposure site.


• DIRECT PULP CAPING WITH MINERAL TRIOXIDE


Direct Pulp Caping with Mineral Trioxide Aggregate (MTA):

Success was determined:•Radiographically.•Disappearance of subjective symptoms.•Normal pulp testing with cold.•continued root formation on immature teeth.

Success depends on the prevention of bacterial ingress by the placement of a well-sealed restoration must also be provided.


Use of HEMOSTATIC AGENTS and DISINFECTANTS on Direct Pulp Exposures:

The mechanical exposure of a healthy pulp created during cavity preparation could be disinfected with either 2% chlorhexidine or5.25% sodium hypochlorite.

PULPAL REACTION TO LASER PROCEDURE

• Laser use on soft / hard tissues has potential benefits of efficiency, reduced sensitivity, disinfection, and precision.

• There are several different types of laser available that depend on the wavelength, active medium, emission mode, delivery system, power output, and duration of application.

PULPAL REACTION TO LASER PROCEDURE

• The main types available in dentistry today are:

• The CO2 laser (10,600 nm).• Er:YAG laser (2940 nm), has a high affinity for water and hydroxy-apatite.• Ho:YAG laser (2120 nm), has high affinity to water but not to tooth structure.• Nd:YAG laser (1064 nm), has high affinity for waterand pigmented tissues and offers good hemostasis.• HeNe laser (632 nm). laser Doppler• GaAlAs laser (720-904 nm).laser flowmetry and in treating dentin hypersensitivity.

PULPAL REACTION TO VITAL BLEACHING TECHNIQUE

Using of strong oxidizing agents(such as carbamide peroxide & hydrogen peroxide) may cause:

• Minor inflammation up to 2 weeks → reversible pulpitis, prevented by treating the teeth with flourides and by correcting defective restoration.

• Sever inflammation → irreversible pulpitis → pulpal necrosis.

PULPAL REACTION TO VITAL BLEACHING TECH

Clinical symptoms are likely to be due to increases in neuropeptides in the pulp.

N.B: A recent studies showed that 10% carbamide peroxide in a custom tray for 6 weeks was

safe for the pulp health, while light-& laser-activated bleaching systems, due to increase neuropeptides expression in the pulp to significant levels.

PULPAL REACTION TO PERIODONTIAL PROCEDURES

It is much more common for pulp necrosis or failed healing of periradicular lesions to present clinically with signs of periodontal disease than for periodontal disease to cause pulpal pathosis.


1°ry pulpal - 2°ry periodontal pathosis:is particularly evident with pulp chamber / coronal third perforation, vertical root fractures or congenital tooth defects.

1°ry periodontal - 2°ry pulpal pathosis:is rare to occur but periodontal scaling and root planning results in dentin hypersensitivity.


(WHY?)It is more likely for microbial irritants to move outward from a vital / necrotic pulp to cause periodontal breakdown than for them to move inward from a periodontal pocket to a vital pulp causing irreversible pathosis.


(HOW?)

The outward dentinal fluid flow in teeth with vital pulp contributes to the resistance to ingress of bacteria in sufficient amounts to cause a clinically significant disease process. Once the pulp degenerates, dentinal fluid flow no longer exists.

PULPAL REACTION TO ORTHOGNATHIC SURGERY

Osteotomy of the jaw → Disruption in the blood supply

• Postoperative manifestations common with traumatic injuries.

• Inflammation and/or necrosis.


N.B: Studies have shown that if a safe distance of

5 to 10 mm is maintained between the site of the surgery and the teeth, minimal disruption occurs. In most cases, the blood flow is regained within months of the surgery.


N.B: Studies have shown that if a safe distance of 5 to 10 mm is maintained between the site of the surgery and the teeth, minimal disruption occurs.

N.B: In most cases, the blood flow is regained within months of the surgery.

PULPAL REACTION TO IMPLANT PLACEMENT AND FUNCTION

The placement of implants requires multifaceted preoperative radiographic techniques.

(WHY?) The lack of attention to:• 3-dimensional anatomy of the site of implant placement.• the orientation of neighboring teeth. perforating the root and devitalizing the pulp.


It is usually recommended to place theimplants at a site free of periradicular lesion.

(WHY?)

Microbial irritants may interfere with osseointegration.

• Some studies claimed that teeth with periradicular lesions may reduce the success of neighboring implants, even if adequate endodontic treatment is performed.


However, recent data suggest that immediate implant placement in sites that have been adequately débrided is successful. Furthermore, implants that are not mobile buthave apical periimplant lesions have beensuccessfully treated with local débridementand “implant-apex resection” procedures.

REGENERATIVE POTENTIAL OF DENTAL PULP

Recent studies and case reports suggest that the dental pulp has great regenerative potential, particularly in the immature permanent tooth.

(HOW?)Stem cells from the apical papilla (SCAP) of immature teeth have likewise been identified and have been shown to develop into dentinogenic cells, given the proper stimulation.

REGENERATIVE POTENTIAL OF DENTAL PULP

pulpal reactions to dental caries and dental proceudres

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