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Methods of Deep Caries Intervention
Protective base
1. Complete Excavation
Traditional operative dentistry approach to deep caries treatment advocated its total
removal using slow-speed rotary burs and hand instrument. Complete excavation
removes all the infected and affected dentin. A pulp exposure can occurs when
complete excavation of deep caries is employed. Complete caries excavation of deep
caries in primary teeth has three times of creating a pulp exposure compared to partial
excavation. The replacement of restorations could result in a very thin amount of
dentin covering the pulp. The amount of remaining dentin under a restoration has
been shown to be the most critical factor in determining the future health of the pulp.
In a closed carious lesion with extensive moist dentin, complete excavation will
greatly thin out the remaining dentin. Therefore, over-excavation is not
recommended.
2. Stepwise Caries Excavation (SW)
The second method of deep caries excavation is termed stepwise excavation and is
done over two patient visits. The first excavation is intended to remove the superficial
necrotic, infected, and affected dentin by completely excavating the periphery of the
lesion. This excavation does not excavate caries near the pulp to avoid a pulp
exposure. A retentive temporary restoration is placed leaving soft, moist, discolored
dentin on the pulpal floor. The dentin is then covered with calcium hydroxide and a
self-setting glass ionomer temporary filling. SW is intended to allow remineralization
of the affected dentin and formation of more tertiary dentin. The carious lesion
is reentered in 8–12 weeks by removing the temporary, and a final complete
excavation is done leaving only central yellowish or grayish hard dentin in the
pulpal floor. A final restoration is placed with the intention to seal the
pulp from any microleakage.
3. Partial (Incomplete) Caries Excavation
The third type of caries excavation is termed partial or incomplete excavation
involving one appointment removal of the peripheral decay but intentionally leaving
the deepest caries in place to avoid a pulp exposure. It implies that the carious dentin
is completely removed from the dentino–enamel junction and lateral walls, while the
necrotic carious dentin from the cavity floor was only removed superficially. The
hypothesis is that a restoration with an adequate peripheral seal, placed over a
cavitated dentin lesion, can arrest the progress of caries lesions. The sealing of the
cavity contributes to the formation of tertiary dentin and sclerosis of dentinal tubules,
thus preventing pulp exposure.
4. No Caries Excavation
The last form of caries treatment has been reported in primary teeth. It involves no
excavation of any caries and would be termed no caries excavation. A steel crown to
seal the caries and stop its progress is used. The technique presumes that sealing the
infected and affected dentin from microleakage will arrest the caries.
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Indirect Pulp Therapy
Indirect pulp therapy is a procedure performed in a tooth with a deep carious lesion
adjacent to the pulp. The decay remaining is mostly affected dentin. It may appear
moist and soft or dark and leathery, but the dentin color and consistency are not
critical to IPT success. If a biological seal is created with a final restoration, the
remaining bacteria in the dentin are believed to be nonviable, and the affected dentin
will remineralize and become harder. The caries near the pulp is left in place to avoid
pulp tissue exposure and is covered with a biocompatible material. A radio-opaque
base such as calcium hydroxide, zinc oxide eugenol or glass ionomer cement is placed
over the remaining affected dentin to stimulate healing and repair. The tooth then is
restored with a material that seals the tooth from microleakage. (Establish a recall
time of about 6-9 weeks, is it necessary?)
Indications:
• Teeth with deep caries that are free of any symptoms of painful Pulpitis.
• No history of spontaneous tooth pain, pain or percussion abnormal mobility,
radiographic evidence of radicular disease, internal/external root resorption.
Direct Pulp Capping
Placement of a medicament material on a pulp that has been exposed, in the course of
excavating the caries, due to mechanical exposures during routine caries removal
.
Indications:
Small mechanical or traumatic exposure less than 1 mm which is surrounded by
sound dentine. In case of light red bleeding form site of pulp exposure that can be
controlled by application of pressure using cotton pellets.
Contraindications:
• Carious pulp exposures.
• Any signs of pain; mobility.
• Radiographic evidence of thickened periodontal ligament/intraradicular
radiolucency.
• Excess bleeding at exposure site.
• Presence of purulent exudates/sinus tract formation.
Clinical Procedures of direct pulp capping
1. Calcium hydroxide
After adequate isolation, following pulp exposure, further manipulation of the pulp
should be avoided. Cavity is irrigated with saline and bleeding arrested with light
pressure from sterile cotton pellet. Capping material is then placed over the exposure
with minimum pressure and avoiding pushing the material into the pulp. A glass
ionomer or reinforced zinc oxide eugenol material should be placed over it to provide
a seal against microleakage since calcium hydroxide has a high solubility, poor seal,
and low compressive strength. The use of glass ionomer cements or reinforced zinc
oxide eugenol restorative materials has the additional advantage of inhibitory activity
against cariogenic bacteria. Cement base is placed over the medicament followed by
restoring the tooth with amalgam and stainless steel crown.
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2. Mineral trioxide aggregate(MTA)
Bleeding is controlled with a cotton moistened with Sodium Hypochlorite (NaOCl).
The MTA paste is obtained by mixing 3 parts of powder with 1 part of water to obtain
putty like consistency. Mixing can be done on paper or on a glass slab using a plastic
or metal spatula. Mixing of MTA should be less than 4 minutes which, if prolonged,
will result in dehydration. This mix is then placed in the desired location and
condensed lightly with a moistened cotton pellet. MTA being hydrophilic requires
moisture to set, making absolute dryness contraindicated. Presence of moisture (not
excess water that makes the mix soupy) during setting improves the flexural strength
of the set cement. MTA is placed over the exposed pulp using hand instruments. Hand
condensation is done with the help of a plugger. The material is padded into place
with a moist cotton pellet. The moist cotton pellet is placed on the MTA and the
material is allowed to set. The rest of the cavity is filled with temporary filling
material. In the next visit, after 1 week, the temporary material is removed along with
the cotton pellet and final restoration placed over the set MTA.
Reactions of materials against pulpal tissues
a. Formocresol
Formaldehyde is the devitalizing ingredient in formocresol. The cause behind use of
this material is to create a chemically altered zone under the medicament that will be
stable over time and leave the deeper untreated pulp tissue vital and uninflamed.
However, investigations have shown that chronic inflammation or even partial
necrosis of the residual pulp often results. Microscopic analyses showed that most of
the beneficial effects of formocresol was in the first 5 min, moreover, they showed
that prolonged exposure caused calcific degeneration. Thus, one-visit, 5-min-
application could be used. Although this method of application saved time, it rendered
the pulp tissue only partially vital leaving the tissue susceptible to abscess formation
and/or internal root resorption teeth that had been successfully treated with
formocresol and observed that the remaining radicular pulps had severe inflammation
adjacent to the amputation site, and most had areas of necrosis within the remaining
pulp tissue without evidence of pulp fixation. In conclusion, formocresol does not
induce healing of the pulp but does cause pathologic changes in the residual pulp.
The formocresol option should be reserved as a means to keep the affected primary
teeth functioning for a limited period of time. Regardless of this outcome, it has been
the benchmark against which all other pulpotomy medicaments are measured.
b.
Calcium hydroxide
It appears to serve as a protective barrier for pulp tissues, blocking patient dentine
tubules and neutralizing
the attack of inorganic acids and their leached products from
certain cements and restorative fillings. It is known to stimulate the formation of
reparative dentine bridges at the junction of necrotic tissue and vital inflamed tissue. It
is initially bactericidal and later becomes bacteriostic in nature
.
Calcium hydroxide (CaOH
2
) was thought to have its effects through the modification
of a solubility product of Ca and PO
4
and a precipitation of salt into an organic
matrix]. However, the effect of the very high pH of CaOH
2
that most likely initiates
either the reparative dentin cascade or one of inflammatory response. From the start,
pulpotomies with CaOH
2
were fraught with failures
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The dismal results shown for calcium hydroxide as a pulpotomy medicament in
primary tooth pulpotomies may be due to the chronic inflammation that may already
be present. This chronic inflammation or the presence of a blood clot may inhibit the
beneficial effects of CaOH
2
on the remaining pulp tissue and adversely affect the
results. It is also speculated that the high pH of calcium hydroxide wounds the pulp in
a manner that initiates the inflammatory cascade. Regardless of what mechanism is
activated, the poor success rate of CaOH
2
pulpotomies definitely limits its usefulness
as a pulpotomy medicament in primary teeth.
c. Mineral Trioxide Aggregate (MTA)
MTA induces similar tissue reactions when applied to pulp tissue. MTA, when mixed
with water, forms crystals of calcium oxide in amorphous structure of 33% Ca
2
+, 49%
PO4
3
-, 2% C, 3% Cl-, and 6% Si
2
+. MTA was developed as an apex filling material,
but has also been proven successful in vital pulp therapy procedures. MTA has a pH
of 10.2 immediately after mixing and increases to 12.5 after 3 hours of setting which
is almost similar to calcium hydroxide. MTA being hydrophilic requires moisture to
set, making absolute dryness contraindicated.
One of the downsides of MTA is that the presence of iron renders the tooth a
dark gray color. Another issue is the cost of MTA. In primary teeth, MTA is
predominantly used for direct pulp capping and pulpotomy procedures. The major
benefits of MTA are that it is biocompatible, it is bactericidal (high pH, 12.5), and it is
able to stimulate cementum-like formation, and bone regeneration. Moreover, its
sealing, mineralizing, dentinogenic, and osteogenic potentials make it the preferred
choice for numerous clinical applications. It has an ability to actively promote hard
tissue formation. The hard tissue barrier is a criterion that must be considered
favorable because it facilitates the clinical handling of the tooth. The hard tissue
barrier does not mean a tight seal against the oral cavity. It is therefore of utmost
importance that the restoration of the tooth provides a tight seal to prevent infection
through microleakage.
Calcium hydroxide and MTA contribute to pulpotomy but, as with any other pulpal
medicament, they have no healing effect on chronically inflamed pulp tissue.
Therefore; the diagnosis of the residual pulp and the surgical technique are of
paramount importance, even more so than the medicament used. In primary teeth,
medicaments such as MTA must be restricted to teeth where the residual pulp is
considered to be healthy in order to achieve a favorable outcome.