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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
Cavity/Crown Preparation
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
Cavity/Crown Preparation
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
VITAL PULP THERAPIES
VITAL PULP THERAPIES
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
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~!!
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