endo protecting the pulp,preserving the apex

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CH2 Protecting the Pulp, Preserving the Apex

Reporter:int 鄭家懋 Instuctor:VS 張淑芳 VS 錢正原 Date: 103/11/04

Chapter outline

DEFINITIONS IATROGENIC EFFECTS ON

THE DENTAL PULP 1.Local Anesthesia 2.Cavity/Crown Preparation 3.Dental Materials 4.Depth of Preparation 5.Specific Materials 6.Vital Tooth Bleaching PROTECTING THE PULP

FROM THE EFFECT OF MATERIALS

VITAL PULP THERAPIES

THE OPEN APEX

Pulp Protection

Threat to the healthy pulp dental caries and the treatment of dental caries

Heat, desiccation, toxicity of restorative materials, leakage at the margins

When dental caries is present, even a white spot lesions

Restorative procedures restore the mechanical integrity and appearance protect the pulp from further damage

Pulp Therapy

Direct pulp cap

A dental material placed directly on a mechanical or traumatic vital pulp exposure

Pulpectomy The complete surgical removal of the vital pulp

Pulpotomy The surgical removal of the coronal portion of a vital pulp as a means of preserving vitality of the remaining radicular portion is usually is performed as an emergency procedure for temporary relief of symptoms or therapeutic measure

Pulp Therapy

Apexification

Inducing a calcified or artificial barrier in a root with an open apex or the continuedapical development of an incompletely formed root in teeth with a necrotic pulp

Apexogenesis

A vital pulp therapy procedure performed to enable continued physiologic development and formation of the root end; term frequently used to describe vital pulp therapy that encourages the continuation of this process

IATROGENIC EFFECTS ON THE DENTAL PULP

Local Anesthesia

containing vasoconstrictorsblood flow is reduced to less than half of its

normal rate and much effectivethe rate of oxygen consumption in the pulp is

relatively lowpulp cells can produce energy anaerobicallySurvive episodes of ischemia lasting for 1 hour or

more

Cavity/Crown Preparation

Revolving bur contacts tooth Dentin is an effective insulatorBut! if the thickness of dentin is less than 1.0

mm or not enough water coolant“boiling” away dentinal tubule fluid at the

dentin surface


The “blushing” of dentin during cavity or crown preparation

without the use of a coolantvascular stasis and thrombosis

The amount of heat produced Sharpness of the bur Pressure Time


The safest way to prepare tooth use ultra-high speeds of rotation with an

efficient water cooling light pressure intermittent cutting air-water spray

Hand instruments and low-speed cutting are relatively safe ways

laser

Cavity Depth/Remaining Dentin Thickness

The deeper the cavity the greater the tubular surface

cause toxic substances can penetrate easilyThe longer of the dentinal tubulesremaining dentin thickness of 1 mm is usually

sufficienttertiary dentin is formed most rapidly when

the remaining dentin thickness is between 0.5 and 0.25 mm

Cavity Drying and Cleansing

A prolonged blast of compressed air aimed onto dentin rapid outward movement of fluid

Cause strong capillary forcesRapid outward fluid movement may also

result in odontoblast displacementodontoblast undergo autolysis and disappear

Cavity Drying and Cleansing

replaced derived from stem cells deeper in the pulp

Drying agents with rapid rate of evaporation

Cavities should be dried with cotton pellets and short blasts of air

Etching Dentin

Cutting dentin results in a smear layerImpervious to bacteria, but is not a barrier to

bacterial productsInterfere with the adherenceDissolution the smear layer opens the

dentinal tubules and increasing the permeability of dentin

May reduce microleakage

Impressions, Temporary Crowns, and Cementation

Rubber base and hydrocolloid materials do not injure the pulp

Modeling compound may be damaging as a result of the combination of heat and pressure

Polymerization of autopolymerizing resinsProvisional crowns fabricatedPostoperative sensitivityCement compresses the fluid

Polishing Restorations/Removing Old Metallic Restorations

frictional heat may be generated during the polishing

Remove metallic restorations also can produce of frictional heat

Especially amalgam or other metallic restorations can causes temperature increase of up to 20° C

Polishing should be at low speeds using intermittent pressure and a coolant

Need combination of water and air

Postrestorative Hypersensitivity

This may be due to any of the factors previously listed

If pain is prolonged… pulpitis may have been exacerbated

If delayed in onset by days… microleakage!!

restoration with modern composites may absence of postoperative sensitivity

Postrestorative Hypersensitivity

desensitizer does not reduce the incidence of sensitivity

deep carious cavities

If pain is evoked by biting… restoration may be exerting a strong shearing force on the dentin walls

does not injure the pulp but may cause a transient hypersensitivity

Dental Materials

Cytotoxicity

Certain restorative materials are composed of chemicals-ZOE, ZPC…etc

Intervening dentin limits the ability of such material reaching the pulp

The problems of these materials were a result of high degree of shrinkage and cause microleakage

the thickness and permeability of dentin affect the response to the material

Cytotoxicity

Materials are more toxic when they are placed directly on an exposed pulp

A set material may differ in toxicity from an unset material

The immediate pulpal response to a material is much less significant than the long-term response

The best measure of long-term response is the thickness of tertiary dentin

Heat on Setting/Desiccation by Hygroscopy

luting cements generate heat during setting

Most exothermic luting material is zinc phosphate

Some hygroscopic materials may cause injury by withdrawing fluid from dentin

But cause less damage than during cavity drying

Specific Materials

Zinc Oxide–Eugenol

Has many uses in dentistryAntibacterial properties, pain controlIt is toxic when placed in direct contact with

tissueWhen use in cements, it does reach the pulpThe release of eugenol is by a hydrolytic

mechanismProvides a tight marginal seal

Zinc Phosphate Cement

ZnOP is a popular luting and basing agentHigh modulus of elasticityCementation of castings with ZnOP is well

tolerated by the pulpMore likely to produce pulpal sensitivity than

GICBut no difference after 3 months

Restorative Resins

Early adhesive bonding and resin composite systems contract cause gross microleakage

Composites absorb water and expand To limit microleakage and improve retention beveled and acid etched recently developed hydrophilic adhesive

bonding composite systems

Glass Ionomer Cements

Originally used as esthetic restorative materials

Placed on exposed pulps in noncarious teeth, glass ionomer cement of bacterial microleakage similar to resins but less than calcium hydroxide cement

The incidence of severe pulpal inflammation or necrosis on exposed healthy pulps…

If a narrow remaining dentin thickness…When used as a luting agent…

Amalgam

Amalgam alloy is still a widely used material for restoring posterior teeth

Shrinkage, corrosionAmalgam is the only restorative material in

which the marginal seal improves with timeIn deep cavities in posterior teeth,

composites are associated with more pulpal injury than amalgams because of microleakage

Vital Tooth Bleaching

external bleaching with 10% carbamide peroxide may causes mild pulpitis

But can reversed within 2 weeksBoth short-term and long-term clinical

observation on bleached teeth report no significant pulpal changes

PROTECTING THE PULP FROM THE EFFECT OF

MATERIALS

Cavity Varnishes, Liners, and Bases

Liner, to improve the overall performance of a restoration

main concern is to reduce or eliminate microleakage

One 3-year clinical study, whether there is a liner or not, the result is same

In reduce dentin permeability, Bases provide the largest reduction, varnishes the least

“Insulating” Effect of Bases

A common misconception is the necessity of placing an insulator beneath metallic restorations

protect the pulp from thermal shockDentin is an excellent insulator Thick cement bases are no more effective

than just a thin layer of dentin


Maintaining an intact healthy pulp is preferable to root canal treatment

Dealing with a deep carious lesionindirect pulp capping

carious exposureOthers procedure, removal of inflamed pulp

tissuethe remaining tissue is then covered with

dressing

Removal of Dental Caries

Most common cause of pulp diseaseProducts of bacterial metabolism, notably

organic acids and proteolytic enzymesEliciting an immune response and

inflammatory reactionnear the pulpal wallDon’t use high speed and

Hand instruments!!

Capping the Vital Pulp

Step-Wise Excavation of Caries caries is removed in two or three appointmentsThe deeper dentin may remineralizeglass ionomer base is placedcareful case selection is necessary

Capping the Vital Pulp

Direct Pulp Cap Two considerations for direct pulp cappingDiffer in that the condition of the pulpHemorrhage controlledHard-set calcium hydroxide or MTACovered by glass ionomer cement should be followed by a permanent restorationThe long-term success rate…

Pulpotomy

When carious pulp exposures occur in young permanent teeth, inflammation may be restricted to the crown

The pulp must be vitalCarious dentin and the pulp to the level of the

radicular pulp are removedControl bleeding, rinsed with sodium

hypochlorite

Pulpotomy

capped with calcium hydroxide or MTA

Follow-up examination should no severe pain or swelling, internal or external resorption, canal calcification

Teeth with immature roots should continue normal root development and apex formation and closure

THE OPEN APEX

THE OPEN APEX

It is in the developing root of immature teeth Also develop as a result of extensive

resorption of a previously mature apexIf the pulp becomes necrotic before root

growth is complete….Resultant root is short with thin and

consequently weakened dentin wallsProvides significant challenges in the

treatment of pulpal injuryThe results of treatment are unpredictableapexogenesis or apexification

Diagnosis and Case Assessment

subjective symptoms, clinical and radiographic examination, diagnostic tests

may be difficult at radiographic examinationlesion tends to have a noncorticated, diffuse

bordercomparison with the periapex of other toothmesiodistal close, buccalingualopen

Treatment Planning

whether the tooth can be restored or fracturePatient compliance is important

Apexogenesis

often the case when an immature tooth sustains a small coronal exposure after trauma

for up to 7 days after the traumatic incident, inflammation is limited to the most superficial 2mm of the pulp

Treatment in these cases is a shallow pulpotomy

When there is a larger exposure…

Apexogenesis

TechniqueAnesthesia, rubber daminflamed pulp tissue removed, use sharp round bur or sharp spoon excavatorHemorrhage is controlledrinsed with 2.5% sodium hypochloriteMTA, powder with sterile water or saline at a ratio of 3 : 1patted in place with a moist cotton pellet

Apexogenesis

The primary goal is to maintain pulp vitalityallowing dentin formation and root-end closureThe time required 1 and 2 yearspatient should be recalled at 6-month intervals to determine the vitalityAbsence of symptoms does not indicate absence of disease

success rate is lower, calcific metamorphosis is a common occurrence

Apexification

Involves removal of the necrotic pulp and placement of an antimicrobial medicamentThe critical factors in apical barrier

formation are thorough debridement of the root canal system and establishment of a complete coronal seal

Calcium hydroxide has been the most widely accepted material for induction of an apical barrier

Produces a multilayered, sterile necrosis permitting subjacent mineralization

Recently, interest has centered on the use of MTA

Apexification

TechniqueAnesthesia, rubber damremoval of all necrotic tissue, H- fileWorking length is established, slightly short of the radiographic apexmaximize cleaning by copious irrigation with sodium hypochlorite and minimal dentin removalLarge paper point Put MTA as barrierpatted in place with a moist cotton pellet

Success or Failure of Apexification

The most common cause of failure is bacterial contamination

Loss of the coronal restoration, inadequate debridement of the canal, root fracture, treatment was not performed under strict aseptic conditions

All patients should be recalled at 12-month intervals for 4 years

Thanks for your attention~!!

endo protecting the pulp,preserving the apex

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