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ASSESSMENT OF PULP
VITALITY
Presented by:-
Anjali Miglani
(P.G Student)
Department of Conservative
Dentistry & Endodontics
INTRODUCTION
The assessment of pulp vitality is a crucial diagnostic
procedure in the practice of dentistry-Noblett 1996
Most methods rely on stimulation of A-fibers gives no
indication of blood flow within the pulp
THE MOST COMMON SYSTEM ASSOCIATED WITH
SYMPTOMATIC PULP IN THE PAIN
PATHOPHYSIOLOGY OF PAIN
- An unpleasant sensory and emotional experience associated with
actual or potential tissue damage defines the physiologic and the
physiologic components.
- The pain process begins in the periphery, where specialized nerve
fibers receive a painful stimulus. These nerve fibers transmit this
information to the spinal cord and ultimately to the brain where
information is interpreted and recognized as PAIN.
DETECTION OF PAIN
Odontogenic pain transmission is mediated primary by peripheral sensory
nerves of the trigeminal nerve.
A fibers nerve – innervate the dentin (Fibers) – Unmyelinated fibers
innervate the body of these pulp and its blood vessels
A – DELTA FIBERS
Pulpodentinal complex – The circumpulpal nerve sends free nerve
ending onto and though the odontoblastic cell layer extending upto 200 um
into the dentinal tubules while also conducting the odontoblastic cell
processes. This intimate association of A Delta fibers with the odonto
blastic cell layer and dentin is referred to as the pulpodentinal complex.
Disturbances of the pulpodentinal complex in a vital tooth initially
affect the low threshold a delta fibers.
Drying, probing drying with air and application of hyper osmotic solution
to exposed dentin will cause pain.
- Movement of fluid in dentinal tubules known as the hydrodynamic
theory of dentin sensitivity stimulation the A –delta fibers.
- Vital pulp responds immediately with symptoms of dentinal pain.
- Through a Delta fibers pain is perceived as quick, Sharp, Momentary
Pain.
- Dessipates quickly upon removal of the stimulus such as drinking
cold liquids a probing exposed dentin.
- The clinical symptoms of a delta fiber pain signify that the
pulpodentinal complex is intact and capable of responding to a
external disturbance.
NERVE FIBERS
- Small,
- Unmyelinated nerves
- High Threshold fibers subadjacent to the A-delta fibers.
- Pain associated with C fibers dull, poorly localized
C fibers activated by intense heating or cooling of the tooth crown or
mechanical stimulation of the pulp.
C fiber pain associated with tissue injury and is modulated by inflammatory
mediations. Vascular changes in blood volume blood flow decrease in
tissue pressure
CLINICAL SIGNIFICANCE
- When inflammation leads to pulp necrosis, periradicular lesions may
develops
- Radiograph shows lesion
- Vital testing – response is seen
- Instrumentation of necrotic pulp may also cause pain
REASON
C fibers more resistant that A fibers to compromised blood flow and
hypoxic conditions
Pain associated with a necrotic pulp in due to
C fiber stimulation.
CLINICAL FEATURES OF PULPAL PATHOLOGIES
Clinical classification of pulpal disease is based on
INFLAMMATION OF THE PULP OR PULPITIS
May be
Acute on chronic partial or total infected or sterile
Can be
Determined can not be determined
Chronic inflammation of exposed pulp
Due to caries or trauma chronic hyperplasic pulpitis.
Acute form runs
- a short, painful cause
Chronic form runs
- Symptoms or slightly painful and of longer duration.
- Clinical class
- Baume found no direct correlation between clinical symptoms and
histologic findings.
Based on clinical symptoms, he divided disease of pulp into 4 categories
1) The symptom less, vital pulp which has been injured or involved by
deep caries, for which pulp capping may be done.
2) Pulps with a history of pain amenable to pharmacotherapy.
3) Pulps indicated for extirpation and immediately root filling.
4) Necrosed pulp accessible to root canal therapy.
Garfunkel and associated found a direct correlation between clinical
diagnosis and histologic examination in 49% of pulps examined.
HISTOLOGICAL FEATURES
Nature – Direct and immune mechanisms
- Release of chemical mediators
- Increase in vascular permeability of vessels
- Benkoryfe around dilated vessels
An interesting phenomenon
Mast cells (inhabitant of loose fibrous connective tissue)
Rarely seen in heath pulps appears in inflammation.
Immune and inflammatory reactions may destroy normal cellular and
extracellular components.
A. REVERSIBLE PULPITIS
Clinical Features
- Mild to moderate inflammatory condition
- Pulp is capable of returning to the uninflamed state following
removed of stimuli.
- Pain of brief duration subsides as soon as stimulus is removed
Histopathology
- Reparative dentin
- Disruption of the Odontoblastic layer
- Dilated blood vessels
- Extravasation of edema fluid
- Pressure of immunologically competent cells.
B. IRREVERSIBLE PULPITIS
It is a persistent inflammatory condition of the pulp, symptomatic or
asymptomatic, caused by a noxious stimulus.
Acute irreversible pulpitis exhibits pain usually caused by hot or cold
stimulus or pain that occurs spontaneously.
- Pains persists for several minutes to hours, lingering after removal of
the thermal stimulus.
- Nerves may occur quickly or the process may require years.
- Pulp death occur slowly and without dramatic symptoms.
- Microabssecesses of the pulp begin as tiny zones of necrosis within
dense inflammatory all infiltrates comprised principally of acute
inflammatory cells.
.
Symptoms
- Sudden temperature changes causes pain.
- Pressure from packing food into a cavity or suction exerted by tongue
or cheek.
- Recumbency which results in congestion of the blood vessels of the
pulp.
- Pain – Sharp, piercing or shooting may be intermittent or continuous.
- Changes of position, bend over or lying down excerts pains.
- In late stage, pain is more severe ,growing throbbing.
- Pain increased by heat and sometimes relieved by cold.
C. CHRONIC HYPERPLASTIC PULPITIS
- Pulp Polyp.
Due to extensive carious exposure of young pulp.
Rising out of the carious shell of the crown in mushrooms of pulp tissue
that is often firm and insensitive to touch.
- Low grade, long standing irritation
Histopathology
- covered by Stratified squamous epithelium
- Granulation tissue
Symptoms
- Symptoms except during mastication.
D. INTERNAL RESORPTON
- Is idiopathic slow or fast progressive resorptive process in the dentin of
the pulp.
HISTOPATHOLOGY
- Results of osteoclastic activity.
- Pressure of granulation tissue accounts for profuse bleeding when
pulps is removed
- Multinucleated giants cells are present
Symptoms
- Asymptomatic
- Manifested as reddish area pink spot.
E. NECROSIS
- Death of the pulp.
Partial total
Can be due to traumatic injury, sequel to inflammation.
Lack of collateral circulation and unyielding walls of dentin
Insufficient drainage
Necrosis
Coagulation necrosis liquefaction necrosis
Symptoms
- No painful stimulus.
- Dull or opaque appearance of the crown due to back of normal
transluscency
Teeth with partial necrosis can respond to thermal changes owing to
presence of vital nerve fibers.
Clinical Classification of Pulpal and Periapical Disease according to Cohen
Clinical classification system was developed. This system was based on the
patient’s symptoms and the results of clinical tests. It was developed to
provide basic terms and phrases that clinicians could use to describe the
extent of pulpal and periapical disease before selecting a method of
treatment. A clinical classification of this sort is not meant to list every
possible variation of inflammation, ulceration, proliferation, calcification
degeneration of the pulp, or attachment apparatus. Rather its purposes are to
suggest in the broadest possible interpretation whether the pulp is either
healthy or unhealthy and to help the clinical experience.
Pulpal Disease
Within Normal Limits – A normal pulp is asymptomatic and produces a
mild to moderate transient response to thermal and electrical stimuli. When
the stimulus is removed the response subsides almost immediately. The
tooth and its attachment apparatus do not cause a painful response when per
cussed or palpated radiographs reveal a clearly delineated canal that taper
smoothly toward the apex. There is no evidence of root resportion, and the
lamina dura is intact.
Reversible Pulpitis
The pulp is uninflamed to the extent that thermal stimuli – usually cold
cause a quick sharp hypersensitive response that subsides as soon as the
stimulus is removed. Otherwise the pulp remains asymptomatic. Any
irritant that can affect the pulp may cause reversible pulpitis including early
caries, periodontal scaling root planning microleakage and unbased
restorations.
Reversible pulpitis is not a disease it is a symptom. If the irritant is
removed and further insult is prevented by sealing the dentinal tubules
communication with the inflamed pulp the pulp will revert to an
asymptomatic uninflamed state. Conversely if the irritant remains the
symptoms may persist indefinitely or may become more widespread leading
to irreversible pulpitis. Reversible pulpitis can be distinguished from a
symptomatic irreversible can be distinguished from a symptomatic
irreversible pulpitis in two ways.
1. Reversible pulpitis causes a momentary painful response to thermal
change that subsides as soon as the stimulus is removes. However
symptomatic irreversible pulpits causes a painful response to thermal
change the lingers after the stimulus is removed.
2. Reversible pulpitis does not involve a complaint of spontaneous
(unprovoked) pain. Symptomatic irreversible pulpitis commonly
includes a complaint of spontaneous pain. Therefore the key
difference is that reversible pulpitis is reactive it produces a response
albeit exaggerated only when stimulated.
Irreversible Pupitis
Irrreversible pulpitis may be acute subacute or chronic it may be partial it
be partial or total infected or sterile. Clinically the acutely inflamed pulp is
symptomatic whereas the acutely inflamed pulp is symptomatic whereas the
chronically inflamed pulp is asymptomatic in most cases. The apical extent
of irreversible pulpitis cannot be determined clinically until the periodontal
ligament is affected by the cascade of inflammatory mediators and the tooth
becomes sensitive to percussion.3,58 Dynamic changes in the irreversibly
inflamed pulp are continual the pulp may move from quiescent chronicity to
acute pain within hours.
Asymptomatic Irreversible Pulpitis
Although uncommon asymptomatic irreversible pulpitis may be the
conversion of symptomatic irreversible pulpits to a quiescent state. Caries
and trauma are the most common causes of this condition which can be
information gathered from the patient’s dental history and properly exposed
radiographs.
Hyperplastic Pulpits
A reddish cauliflower like growth of pulp tissue through and around a
carious exposure is one variation of asymptomatic irreversible pulpitis. The
proliferative active nature of this pulpal reaction sometimes known as a
“pulp polyp,” is attributed to a low grade chronic irritation of the pulp and
the generous vascularity characteristically found in young people.”
Occasionally this condition may cause mild transient pain during
mastication.
Internal Resorption
Internal resorption is a painless condition resulting from the recruitment of
blood-borne clastic cells often stimulated by trauma which produces dentin
routine radiographic examination. If undetected internal resorption will
eventually perforate the root. Before perforation of the crown the resorption
can be detected as a pink spot on the site. Only prompt endodontic therapy
to eliminate these elastic cells will prevent tooth destruction.
Symptomatic Irreversible Pulpitis Symptomatic irreversible pulpitis is
characterized by spontaneous )i.e.), intermittent or continous paroxysms of
pain. Sudden temperature changes (usually cold) elicit prolonged episodes
of pain )i.e., pain that lingers after the thermal stimulus is removed). This
pain may be relived in some patients by the application of heat or could.
Occasionally patients may report that a postural change (lying down or
bending over) induces pain resulting in fitful sleep. Even with the use of
several pillows to stabilize themselves at a comfortable postural lives
patients ,may continue the experience pain.
Generally pain from symptomatic irreversible pulpitis is moderate to severe
it can be sharp or dull localized or referred. In most cases radiographs are
not useful in diagnosing symptomatic irreversible pulpitis because the
inflammation remains confined to the pulp. However radiographs can be
helpful in identifying offending teeth (i.e., teeth with deep caries extensive
restorations pins evidence of previous pulp capping calicific
metamorphosis)2. In the advanced stage of symptomatic irreversible pulpitis
thickening of the apical portion of the periodontal ligament may become
evident on the radiographs. Symptomatic irreversible pulpitis can be
diagnosed through synthesis of the information provided a thorough dental
history a complete visual examination properly exposed radiographs and
carefully conducted thermal tests. If radiating or referred pain is involved
the application of 0.2 ml of intraligamentary anesthesia in the distal sulcus
of the correctly identified tooth will immediately stop the pain. EPT is of
little value in the diagnosis of symptomatic irreversible pulpitis because the
pulp though inflamed is still reversible pulpitis because the pulp though
inflamed is still responsive to electrical stimulation.
There inflammatory process of symptomatic irreversible pulpitis may
become so severe that it will lead to necrosis of the pulp. In the
degenerative transition from pulpitis to necrosis the usual symptoms of
symptomatic irreversible pulpitis may subside as necrosis occurs.
Necrosis
Necrosis the death of the pulp actually refers to a histologic condition
resulting from an untreated irreversible pulpitis a traumatic injury or any
event that causes long –term interruption of the blood supply to the pulp.
Pulp may become liquefied or coagulated. Total necrosis is asymptomatic
before it affects the periodontal ligament because the pulpal nerves are
nonfunctional. For this reason there is no response to thermal or EPT. Some
crown discoloration may accompany pulp necrosis in anterior teeth but this
diagnostic sign is not reliable.27,48 Partial necrosis may be difficult to
diagnose because it can produce may be difficult to diagnose because it can
produce some of the symptoms associated with irreversible pulpitis. For
example a tooth with two or more toot canals could have an inflamed pulp
in one canal and a necrotic pulp in the other.
The bacterial toxins (and sometimes bacteria) that produced the
necrosis in the pulp follow the pulp tissue through the apical foramen to the
periodontal ligament resulting in an inflammatory reaction in the
periodontium. This inflammation will lead to thickening of the periodontal
ligament and manifest itself as tenderness to percussion and chewing.3.58
As these irritants cascade out of the root canal system often periapical
disease will occur.5
The difficulty with the use of the term “necrosis” is that pulp vitality testing
has been limited to electrical and thermal stimulation of pulpal nerves. In
the case of teeth that have been traumatized9 teeth in a segment of bone that
has been surgically repositioned,1 teeth with immature apices, 17,18,31 or
teeth that have calcified with age,8 nerve function can be diminished or
cease altogether while the pulp retains an intact vasculature. Thus reliance
upon EPT and thermal pulp testing can result in the unnecessary removal of
healthy denervated pulps. Perhaps the use of more sophisticated testing
techniques, such as laser Doppler flowmetry or pulse oximetry will
overcome this limitation and provide a clinical test
Laser doppler measurements augement clinical observations providing
an improved basis for dental treatment plan
Assessments of pulpal status in by various AIDS
Correction of various methods pulp vitality in different pulpal
conditions,
VARIOUS AIDS IN DETECTING THE VITALITY OF THE
PULP
Assessment of pulp vitality should be based on blood supply of the
pulp. Unfortunately, assessment of the pulpal blood supply remains
complicated and there is no practical clinical test to determine this basis
aspect of the tooth’s biology.
The clinical condition of the pulp can be evaluated by various
methods.
1. History of the patient
2. Thermal test
3. Percussion
4. Palpation
5. Electric pulp test
6. Transillumination
7. Liquid crystal testing.
8. Hughes probeye camera.
9. Occlusal pressure test
10.Anaesthetic test
11.Test cavity
12.Pulse oximetry.
13.Dual Wavelengths spectrophotometry
14.Laser Doppler flowmetry
15.Use of tooth temperature
16.MRI.
1. HISTORY OR THE PATIENT
To know the status of the pulp, patients is chief complaint plays an
important role includes symptoms that occur following specific events
(eg chewing drinking cold liquids)
- Whether pain is of short duration of long duration we can judge
condition to be
Acute chronic
It patient presents with so symptoms, but gives a part history of pain then
we can suspect necrosis of the pulp history should be corroborated with
other clinical tools and radiographs.
2. PALPATION
- Uses digital pressure to check tenderness in the cavity covering suspected
tooth.
Sensitivity indicates inflammation in the periodontal ligaments surrounding
affected tooth.
We can suspect that inflammation through caries lesion has gone to the
PDL if tenderness to palpation occur.
Thermal Pulp Tests:- One of the most common
symptoms associated with the symptomatic inflamed pulp is pain elicited
by thermal stimulation. Although some patients suffer pain when cold is
applied to the tooth but are comfortable with warm substances and others
require frequent applications of cold liquid to keep their pain bearable there
is no particular response to either heat or cold that is unique to a specific
pulpal pathologic state56.
The only conclusion the clinician may draw when a pulp responds
abnormally to thermal stimulation either in an exaggerated manner or not at
all is that is not in a state of good health.
The rationale for innervation of any bodily structure is to provide a warning
of damage that is occurring pain with the application of thermal stimuli is
normal and a vital part of the patient’s protective defense mechanism.
The pain is proportionate to the stimulation consequently even teeth with
intact enamel will react to extreme cold such a in ice or carbon dioxide
snow. When teeth begin to react to stimuli that do not normally produce
pain such as tap water the probability is that dentin has been exposed by
caries that the tooth structure is fractured or that faulty restoration abrasion
or attachment loss caused by periodontal disease exists. Additionally an
exaggerated response to thermal stimuli can indicate a lowered threshold to
stimulus because of pulpal inflammation (e.g immediately after placement
of a restoration).
Solution is to address the cause of the dentin sensitivity by occluding the
dentinal tubules by placing a temporary sedative restoration such as
intermediate restorative material (IRM).In the case of the new restoration
the clinician should simply wait to see whether the acute inflammation
subsides in a short.
When the chief complaint is pain to a thermal stimulus (usually cold)
the clinician must distinguish between thermal testing to isolate the
offending tooth by reproducing the patient’s symptoms and attempting to
determine whether a suspected tooth has a vital or nonvital pulp. In the
former case the patient is complaining of painful pulpal response cold
therefore pulpal vitality is not at issue.
A graduated method of applying the stimulus is required to avoid causing
the triple syringe followed by isolation the tooth under a rubber dam and
bathing it with cold water should elicit the patient’s symptoms and quickly
indicate the offending tooth. In contrast when there is no complaint of cold
sensitivity the following methods for using cold to determine pulpal vitality
are appropriate.
Cold Test: Various methods have been used to apply cold to the teeth for
testing. The most commonly used method are ice sticks, various
compressed gasses and carbon dioxide snow.
Freezing water in the plastic covers from hypodermic needles one is
removed from the freezer and held tightly in the clinician’s hand for a few
minutes. This melts the outside of the stick so that it can be removed from
the plastic and held in a 2” x 2” gauze for use. The ice stick applied
immediately to the middle third of the facial surface of the crown of the
tooth or on any exposed metal surface of crowns and kept in contact for 5
seconds of until the patient begins to feel pain.
Ethyl chloride is available as a compressed spray, commonly used in
medicine as a skin refrigerant. Its use in pulp testing is no longer
recommended because it has been found to be less effective than carbon
dioxide snow or dichlorodifluoromethane which is the refrigerant R-12
commercially packaged as a compressed spray (Endo-Ice). It has been
replaced by the manufacturer with 1,1,1,2 Tetrafluoroethane, which is the
nonchlorofluo-rocarbon refrigerant R-134a, available as Green Endo-Ice.
No studies are yet available on the efficacy of this replacement compared
with other testing methods. However it also has a low boiling point (-
15.10F). The material is sprayed liberally onto a cotton pellet or swab,
which is then applied immediately to the middle third of the facial surface
of the crown of the tooth. The pellet is kept in the contact with the crown
for 5 seconds of until the patient begins to feel pain.
Carbon dioxide snow formed into sticks is extremely cold. It is the
most effective method of eliciting a response in vital teeth. No detrimental
effects occurred in vital pulpal tissue and no cracks or surface irregularities
were produced in the enamel of tested teeth.26,43,47 The carbon dioxide is
released into a special syringe in which it forms the “snow”. It is compacted
with a plunger and the pellet is expressed onto a 2” x 2” gauze. It is applied
immediately to the middle third of the facial surface of the crown of the
tooth and kept in contact with the crown for 2 second or until the patient
begins to feel pain. Although less convenient than the isolating the teeth
individually with a rubber dam and bathing each tooth with ice water from a
syringe for 5 secs simultaneously cools all surfaces of the teeth.
Heat Test : As with cold testing many methods for heat testing teeth have
been suggested. Although all transfer heat to the tooth the methods most
commonly used are warm sticks of temporary stopping used are warm
sticks of temporary stopping and the hot water bath. Warm sticks of
temporary stopping and the hot water bath. Warm sticks of temporary
stopping are the most convenient for the clinician but the hot water bath
will yield the most accurate patient response.
Temporary stopping consists of gutta-percha in 3-inch sticks. To use
this technique the teeth to be tested are first protected with a light coating of
petrolatum to prevent the warm temporary stopping from sticking to them.
The stopping is warmed over a flame until it becomes soft and just begins
to glisten (Grossman’s method)23 but not so that it slumps and becomes too
limp to use. Application to the middle third of the facial surface of the
crown usually results in a response in less than 2 seconds. A 5- second
application has been found to increase the temperature at the pulpodentinal
junction less then 20 C there fore it is unlikely that damage will occur to the
pulp47.
The tooth is bathed in very warm water from a plastic syringe for 5 seconds
or until the patient begins to feel pain. Since the patient’s chief complaint is
pain in response to heat the temperature is gradually increased if no
response is obtained rather than producing unnecessary’s pain by beginning
with excessively hot liquid.
Although the cold and hot water bath methods of thermal testing are time
consuming they are clearly superior in their accuracy compared to very
warm temporary stopping or ice pencils. The use of water allows allows the
entire crown to be immersed not just one section of one surface of the tooth.
Even when the tooth has been restored with a full crown (metal or
porcelain) sufficient contact is made to allow cooling or warming of the
pulp. In addition the cold ant hot water bath methods prevent damage to the
tooth caused by excessive temperature change.
Responses to Thermal test: The sensory fibers of the pulp transmit only
pain whether the pulp has been cooled or heated. There are four possible
responses to thermal stimulation:
1. No response
2. mild- to – moderate degree of awareness of slight pain that subsides
within 1 to 2 seconds after the stimulus has been removed
3. Strong momentary painful response that subsides within 1 to 2
seconds after the stimulus has been removed
4. Moderate –to strong painful response that lingers for several seconds
or longer after the stimulus has been removed
If there is no response to thermal testing a nonvital pulp is often the cause.
However no response to thermal testing can also indicate a false negative
response because of excessive calcification an immature apex recent trauma
or patient premedication. A momentary mild-to-moderate response to
thermal change is generally considered within normal limits. A somewhat
exaggerated response that subsides quickly is characteristic of reversible
pulpitis. A painful response that linger for several minutes after the stimulus
is removed that lingers for several minutes after the stimulus is removed is
characteristic of irreversible pulpitis.
ELECTRIC PULP TESTS: The electric pulp tester (EPT) uses
electric excitation to stimulate the A sensory fibers within the pulp.
A positive response to electric pulp testing does not provide any
information about the health or integrity of the pulp it simply indicates that
there are vital sensory fibers present within the pulp.58 Often irreversibly
inflamed pulp is responsive to EPT because it still contains vital function
nerve fibers that can produce a toothache. The EPT provides only a
responsive or nonresponsive result that correlates in many cases with vital
or nonvital pulpal status. Therefore attempting to interpret the numerical
values produced by the EPT is not recommended. The electric pulp test fails
to provide any information about the vascular supply to the pulp which is
the true determinant of pulp vitality. As a result teeth that temporarily or
permanently lose their sensory function (e.g., teeth damaged by trauma or
teeth that have undergone orthognathic surgery) will be nonresponsive to
EPT. However they will have intact vasculature.9
Seltzer et al reported that 28% of teeth necrotic pulps tested positive
to EPT, and more that half of those with [partially necrotic pulps were
responsive.
When a patients reports sensation in a tooth with a necrotic pulp, it is
termed a false positive response. Circumstances that can cause false
positive response to electric pulp testing include patients anxiety, saliva
conducting the stimulus to the gingiva, metallic restorations conducting the
stimulus to the adjacent teeth, and liquefactive necrosis conducting the
stimulus to the attachment apparatus.
A false negative response means that although the pulp is vital, the patient
dose not indicate that any sensation is felt in the tooth. This situation can be
produced by premedication with drug or alcohol, immature teeth, trauma,
poor contact with the tooth, inadequate media, partial necrosis with vital
pulp remaining in the apical portion of the root, and individual patients with
atrophied pulps or high pain thresholds. Therefore, it is essential that
multiple tests be performed before a final diagnosis is made.
EPT is an imperfect, though useful, way to determine the pulpal status of a
tooth. In the case of a periapical radiolucency, EPT will help the clinician
determine whether the pulp is vital. When used thermal and periodontal
testing the EPT can help differentiate pulpal disease from periodontal
disease or nonodontogenic causes.
LASER DOPPLER FLOWMETRY. EPT uses electric current to
stimulate the A nociceptors in the pulp. When these fibers are intact
stimulation results in a painful sensation and the pulp is said to be vital.
However, intact nerve functioning is not essential for pulp vitality. Teeth
that have experienced recent trauma or are in a portion of jaw that has under
gone orthognathic surgery can lose sensibility while retaining an intact
blood supply and vital pulp. Investigators found that 21% of teeth in
patients that tested nonresponsive to electrical stimulation after having
undergone Le Fort operations had intact blood supplied when tested with
laser Doppler flowmetry. With EPT only, the pulps would have been
considered necrotic, and endodontic therapy would have been needlessly
undertaken.
Laser Doppler flowmetry uses a laser beam of known wavelength that is
directed through the crown of the tooth to the blood vessels within the pulp .
Moving red blood cells cause the frequency of the laser beam to be
Doppler shifted ands some of the light to the back scattered out of the
tooth. This reflected light is detected by a photocells on the tooth surface,
the output of which is proportional to the number and velocity of the
blood cells.
Laser Doppler flowmetry is complicated by the fact that the laser beam
must interact with moving cells within the pulpal vasculature. To avoid
artifactual responses, a custom fabricated. Jig (i.e., mouth guard) is needed
to hold the sensor motionless and maintain its contact with the tooth. The
position on the crown of the tooth and the location of the pulp within the
tooth cause variations in pulpal blood flow measurements. Additionally
differences in sensor output and inadequate calibrations by the
manufacturer may mandate the use of multiple probes for accurate
assessment and antihypertensive medications and nicotine may affect blood
flow to the pulp, producing inaccurate results. Finally, the equipment still is
too expensive for the average dental office.
Current limitations aside, laser Doppler flowmetry promises an objective
measurements of pulpal vitality and health.
When equipment costs decrease and clinical applications improves, this
technology could be used for patients who cannot communicate effectively
or whose responses may not be reliable (e.g. young children). Because this
testing modality produces no noxious stimuli, apprehensive or distressed
patients may accept it more readily than current methods.
PULSE OXIMETRY –
Another optical diagnostic method currently under investigation is the
adaption of pulse oximetry to the diagnosis of pulpal vitality. Pulse
oximetry is a widely used technique for recording blood oxygen saturation
levels during the administration of intravenous anesthesia. Increased acidity
and metabolic rate produced by inflammation cause deoxygenation of
hemoglobin and change the oxygen saturation of the blood. A pulse
oximeter uses a probe for oxygen saturation of the blood. A pulse oximeter
uses a probe containing a diode that emits light in two wavelengths (1) red
light of approximately 660 mm and (2) infrared light or approximately 850
nm. This light is received by a photodetector diode, connected to a
microprocessor. The device compares the ratio of the amplitude of the
transmitted infrared with red light. It uses this information together with
known absorption curves for oxygenated and deoxygenated hemoglobin, to
determine the oxygen saturation levels.
By monitoring changes in oxygen saturation, pulse oximetry may be able to
detect pulpal inflammation or partial necrosis in teeth that are still vital.
Several investigators have successfully used modified finger probes or
adapted the instruments to teeth to demonstrate the reliability of the system
in the diagnosis of pulp vitality. Other investigators indicate that the use of
reflected light may be preferable to transmitted light and that different or
multiple wavelengths may be required to improve the sensitivity of the
technique.
Pulse oximeters measure the arterial oxygen saturation of
hemoglobin, the technology involved is complicated but there are two basic
physical principles, first the absorption of light at two different wavelengths
by
haemoglobin differs depending on the degree of oxygenation of
haemoglobin second the light signal following transmission through
the tissues has a pulsatile component ,resulting from the changing
volume of arterial blood with each pulse beat .this can be distinguished
by the microprocessor from the non-pulsatile component resulting
from venous ,capillary and tissue light absorption the function of a
pulse oximeters is affected by many variable ,including :ambient
light ,shivering
abnormal haemoglobin pulse rate and rhythm ;vasoconstriction and
cardiac function a pulse oximeter gives no indication of a patient ,
ventilation ,only of their oxygenation ,and thus can give a false sense
of security if supplemental oxygen is being given ,in addition ,there
may be a delay between the occurrence of a potentially hypoxic event
such as respiratory obstruction and a pulse oximeter detecting low
oxygen saturation however ,oximetry is a useful non-invasive monitor
of a patient ,s cardio-respiratory system which has undoubted
improved patient safety in many circumstances
Pulse Oximeters are now the standard part of
preoperative monitoring which give the Operator a non -
invasive indication of the patient ,s cardio –respiratory
status .having been successfully used in intensive care the
recovery room and during anaesthesia they have been
introduced in other areas of medicine such as general wards
apparently without staff undergoing
What dose a pulse oximeter measure ?
1 the oxygen saturation of haemoglobin in arterial blood –which is a
measure of the average amount of oxygen bound to each
haemoglobin molecule ,the percentage saturation is given as a digital
readout together with an audible signal varying in pitch
depending on the oxygen saturation
Principles of modern pulse oximetry
oxygen is carried in the bloodstream mainly bound to
haemoglobin .one molecule of haemoglobin can carry up to four
molecules of oxygen ,which is then 100%saturated with oxygen .the
average percentage saturation of a population of haemoglobin
molecules in a blood sample is the oxygen saturation of the blood ,In
addition ,a very small quantity of oxygen is carried dissolved in the
blood ,which can become important if the haemoglobin levels are
extremely low .the however ,is not measured by pulse oximetry
a pulse oximeter consist of a peripheral probe, together with a
microprocessor unit, displaying a wave from, the oxygen saturation and
the pulse rate. Most oximeters also have an audible pulse tone, the pitch
of which is proportional to the oxygen saturation – useful when one can
not see the oximeter display. The probe is placed on a peripheral part of
the body such as a digit, ear lobe or the nose. Within the probe are two
light emitting diodes (LED’s) one in the visible red spectrum (660nm)
and the other in the infrared spectrum (940nm). The beams of light pass
through the tissue to a photodetector. During passage through the tissue,
some light is absorbed by blood and soft tissue depending on the
concentration of haemoglobin. The amount of light absorption at each
light free frequency depends on the degree of oxygenation of
haemoglobin within the tissue.
The microprocessor can select out the absorbance of the pulsatile
fraction of blood, i.e. that due to arterial blood, from consists absorbance
due to non pulsatile venous or capillary blood and other tissue pigment.
Several recent advances in microprocessor technology have reduced the
effect of interference on pulse oximeter function. Time division
multiplexing, whereby the LED’s are cycled, red on then infrared on,
then both off many times per second, helps to eliminate background
noise. Quadrate division multiplexing is a further then recombined in
phase later. In this way, an artifact due to motion or electromagnetic
interference may be phase later. In this way, an artifact due to motion or
electromagnetic interference may be eliminated since in will not be in
the same phase of the two LED signal once they are recombined.
Saturation values are averaged out over 5 to 20 second. The pulse rate is
also calculated from the number of LED cycles between successive
pulsatile signals and averages out over a similar variable period of time,
depending on the particular monitor.
From the proportions of light absorbed at each light frequency, the
microprocessor calculates the ratio of two. Within the oximeter memory
is a series of oxygen saturation values obtained from experiments
performed in which human volunteers were given increasingly hypoxic
mixtures of gases to breath. The microprocessor compares the ratio of
absorption at the two light wavelengths measured with these stored
values, and then display the oxygen saturation digitally as a percentages
and audibly as a tone of varying pitch.
Practical tips to the successful use of pulse oximetry.
Plug the pulse oximeter in to an electrical socket, if available to recharge the batteries.
Turn the pulse oximeter on the wait for it to go through its calibration and check tests. ]
Selects the probe you require with particular attention to correct sizing where it is going to go. The light should be clean (remove nail varnish).
Position the probe on the chosen digit, avoiding excess force. Allow several seconds for the pulse oximeter to detect the pulse and
calculate the oxygen saturation. Look for a displayed waveform. Without this, any reading is
meaningless. Read off the displayed oxygen saturation and pulse rate.
Be cautious interpreting figures where there has been an instantaneous change in saturation – for example 99% falling suddenly to 85%. This is physiologically not possible.
Is in doubt, rely on your clinically judgement, rather than the value the machine gives.
Pulse oximetery is a simple non invasive method of monitoring the
percentage of haemoglogin (Hb) which is saturated with oxygen. The pulse
oximeter consists of a probe attached to the patient finger or ear lobe which
is linked to a computerized unit. The unit displays the percentage of Hb
saturated with oxygen together with an audible single for each pulse beat, a
calculated hart rate and in some models, a graphical display of the blood
flow past the probe. A audible alarms which can be programmed by the
user are provided.
How does an oximeter work? A source of light originates from the probe
at two wavelengths (650nm and 805nm). The light is partly absorbed by
haemoglobin, by amounts which differ depending on whether it is saturated
or desaturated with oxygen. By calculating the absorption at the two
wavelengths the processor can compute the proportion of haemoglobin
which is oxygenated. The oximeter is dependent on a pulsatile flow and
produce a graph of the quality of flow.
The computer within the oximeter is capable of distinguishing pulsatile
flow from other more static signals (such as tissue or venous signals) to
display only the arterial flow.
Calibration and Performance. Oximeters are calibrated during
manufacture and automatically check their internal circuits when they are
turned on. They are accurate in the range of oxygen saturations of 70 to
100% (/-2%), but less accurate under 70%. The pitch of the audible pulse
signal falls with reducing values of saturation.
The size of the pulse wave (related to flow) is displayed graphically.
APPLICATIONS
Tooth pulp vitality Testing
Tubules within the dentin act as light guides and direct light incident on the
tooth surface into the pulp. This in highly vascular tissue and because of its
position within a rigid structure, the vessel compliance is vary limited.
Cardiac cycle blood pulsation in the supplying artery are transmitted to the
pulp capillaries as pulsations in blood velocity. These pulsation are apparent
on Doppler monitor traces of vital teeth and are absent from non vital teeth.
The mean blood flux level in healthy teeth is much higher than for non vital
teeth. However in vital teeth with impaired blood supply the flux level can
be low and the presence of pulsation is the only indication of vitality.
RADIOGRAPHIC INTERPRETATION
Only films of the highest quality should be accepted; any time or
money saved by not taking questionable films would be forfeited by one
misdiagnosis. Clinicians should strive to limit their patients exposure to
radiation and maximize their skills and the skills of staff members to
achieve this end. However because the benefits or radiographs outweigh the
risks, diagnostic quality radiographs should be obtained even at the expense
of repeated image
Once high quality radiographs are obtained, the next step is to view them
properly.
They found that a diagnosis based on the continuity and shape of the lamina
dura and the width and shape of the periodontal ligament space was the
most accurate in identifying teeth with nonvital pulps.
In addition to inspecting the lamina dura and periodontal ligament space,
the clinician should consider whether the bony architecture is within normal
limits or whether there is evidence of demineralization. The clinician should
be also consider whether the root canal system is within normal limits,
whether it appears to be resorbing or calcifying and what anatomic
landmarks could be expected in the area. A sound, correct examination
protocol includes a careful investigation of each of these considerations.
In addition to periapical films in the posterior region, it is helpful to prepare
bite wing films. Early caries, the depth of existing restorations, pulp caps,
and pulpotomies or dens invaginatus can be identified in bite wing films.
Deep caries or extensive restorations increase the likelihood of pulpal
involvement.
A necrotic pulp will not cause radiographic changes until the enzymes
produced by the inflammatory process have begun to demineralize the
cortical plate. For this reason, significant medullary bone destruction may
occur before any radiographic sings begin to appear. Toxins and other
irritants may exit through a lateral canal, causing periradicular (rather than
periapical) demineralization. Conversely, a lateral canal in a tooth affected
by periodontal disease can become a portal of entry for harmful toxins.
Pulp stones and canal calcifications do not necessarily have pathologic
origin; they can be the result of normal aging of the pulp.
These calcification were not correlated with the severity of periodontal
disease, did not produce higher EPT responses and were not related to age.
In traumatized teeth with pulp obliteration studied between 7 and 22 years
posttrauma, 51% had a normal response to EPT. Another 40% did not
respond but were clinically and radiographically normal. The investigations
calculated the average rate of pulp survival for 20 years at 84%.
Consequently, in the pulp stones or canal calcification should not be
interpreted as a pulpal disorder that requires endodontic therapy.
However, internal resorption (occasionally seen after trauma) is an
indication for endodontic therapy. The inflamed pulp recruits clastic cells,
which asymptomatically resorb the radicular dentin from the blood vascular
system. In this case the pulp must be removed as soon as possible to
eliminate these cells and avoid a pathologic perforation of the root.
Recognizing the presence of immature apices allows the clinician to
anticipate erroneous responses to thermal and electric pulp tests.
If the canal appears blurred when compared with the irregular
demineralized radiolucency surrounding the root, lingual development
grooves would be suggested.
In a few cases root fractures may cause pulp degeneration. Only a
horizontal root fracture will be identifiable in the early stage and then only
if the fracture line is within 15 degree of the central radiographic beam. In
the case of a suggested horizontal fracture, two additional radiographs
should be produced from angles 30 degrees. Vertical and oblique root
fractures will eventually cause demineralization and a resultant diffuse
radiolucency adjacent to the fracture.
SPECIAL TESTS
Crown Removal – Many times a patient will describe symptoms of
irreversible pulpitis, but the suspected tooth is completely hidden from view
clinically and radiographically by a prosthetic crown. Although thermal and
EPT may be possible, if there are intact nerve fibers in the pulp, the results
may be difficult to differentiate from normal. In this case it is often
necessary to complete the examination by carefully removing the crown to
inspect the tooth underneath. Many times leakage from sub gingival
margins that were impossible to adequately explore clinically has resulted
in a carious exposure of the pulp.
Removal of the prosthetic crown not only conforms the diagnosis it also
allows the clinician to assess the restorability of the tooth.
SELECTIVE ANESTHESIA TEST
Test Cavity – Occasionally the clinical will encounter a tooth that exhibits
mixed responses to pulp testing (e.g. it fails to respond to cold, but it does
respond to EPT). Is this an example of a false positive response to EPT
caused by gingival conduction.
The most accurate technique to discover whether a pulp is vital is to begin
to make a preparations in a concealed area of the tooth without
anesthetizing the patient, who has been adequately approved of what to
expect and how to respond if discomfort is felt, when the dentinoenamel
junction (DEJ) is passed, or as the pulp is approached the patient should
feel pain if the pulp is vital. Once a vital response is elicited, the cavity
preparation should caesed and the tooth should be restored. If no response is
evoked access preparation may continue and endodontic therapy completed.
Although the damage can be repaired, this not a reversible procedure.
Therefore, it should be reserved for cases when it is impossible to arrive at a
pulpal diagnosis in another way.
Technical Details
The technique requires probe stability relative to the tooth. A dental putty
splint with a small hole drilled at the tooth position of interest, provides
mechanical stability for the probe. This technique has the advantage of
enabling reproducibility of prove position at successive visit for chronic
monitoring. 2) The splint also prevents backscattered light scattering off
other tissue and eliminates contamination of the laser Doppler signal by
these source.
Laser Doppler sampling should be atleast 10 samples per second (10Hz)
and the integrated time should be set at 0.1 sec so that the cardiac pulse
wave can be observed. A record duration of at least 30 seconds is
recommended so that vasomotion features of vitality can also be assessed.
Comparison of a flux trace measured from the contra-lateral healthy tooth
often aids diagnosis of vitality. Signal processing technique now enable
diagnosis with a sensitivity and specificity better than 90%. that reliably
indicates pulpal necrosis
MAGNETIC RESONANCE IMAGING
Recently MRI has been tried out a diagnostic tool in endodontics Magnetic
fields and radiographic waves are used to generate high quality cross-
sectional images of the body. It works on electro magnetic energy (X-rays
involves ionization). It can distinguish blood vessel and nerves from
surrounding tissues.
However this needs large equipment. This high electromagnetic
waves which are needed have not been approved off for use in scanners. In
future MRI offers evaluation of odontogenic problems.
CONTRAINDICATIED in patients with cardiac pace makers metallic
restorations orthodontic appliances and aneurysms.
It can be divided into few simple stages-
1. The patient is placed in a magnetic field and essentially becomes a
magnet.
2. A radio wave is sent in
3. The radiowave is turned off.
4. The patient emits signal
5. The signal is received and used for reconstruction of the picture.
Application
MRI tried as for diagnosing pulp vitality By use of contrast medium
VITAL TEETH shows dye contrast
NONVITAL TEETH shows no dye contrast.
HUGHES PROBEYE CAMERA
It is used to assess the vitality of the pulp. It measure temperature changes
as small as 0.10C
TRANS ILLUMINATION WITH FIBER OPTIC LIGHT
Light is passed through a finely drawn glass or plastic fibres across the
tooth by a process known as Total Internal Reflection.
A pulp less tooth is not noticeably discolored may show a gross difference
in translucency when a shadow produced on a mirror is compared to that of
adjacent vital tooth
XENON -133
This was introduced by Ronni. It was used to check the status of pulpal
blood circulation. It is a radioactive substance and pulpal circulating is
checked by wash out of Xenon-133.
DUAL WAVELENGTH SPECTROPHOTOMETRY
This was developed by ‘Chance’. This technique measures the
oxygenation change of blood. This identifies the teeth with pulp chamber
that are either empty filled with fixed pulp tissue or filled with oxygenated
blood.
Wavelength of 760 nm and 850 nm were used.
– independent of a pulsatile circulation
– presence of arterioles rather than arteries in the pulp and
rigid encapsulation make it difficult to detect pulse in the
pulp space.
– PRINCIPLE :-
This method measures oxygenation changes in capillary bed rather
than in supply vessels hence does not depend on pulsatile blood flow.
• In young children ,in cases of avulsed and replanted teeth with
open apices the blood supply is regained within first 20 days after
replantation but nerve supply lags behind
• Spectrophotometric readings taken at start of replantation and
continuing up to 40 days revealed an increase in blood
oxygenation levels
indicating healing process
LIQUID CRYSTAL TESTING
Cholesterol liquid crystals are used to show temperature difference between
teeth. Vital pulp may be hotter or show a higher temperature than the
necrotic pulp (cooler)
IL-1 (A lymphocyte activating factor) is responsible for osteoclast
activation which results in bone resorption which is often a feature of
inflammatory response.
The presence of IL-1 is examined by an ELISA (Enzyme linked
Immunosorbent Assay)
PLETHEYSMOGRAPHY
It is a method in assessing the changes in volume and has been
applied to the investigation of arterial disease because the volume of the
limb or organ exhibits transient changes over the cardiac cycle.
Plethysmography in limb or organ exhibits transient changes over the
cardiac cycle. Plethyusmography in limb or digit can be performed using air
filled cuffs or mercury in rubber strain gauges.
As the pressure pulse passed through the limb segment, a wave form is
recorded which related closely to that obtained by intra–arterial
cannulation. The same principle can be used to assess the vitality of the
pulp. Presence or absence of a wave form can indicate the statue of the
tooth pulp.
Of all the diagnostic aids - Radiovisiography has gained popularity
and also Laser Doppler flowmetry, which has come into clinical use, but its
usage is limited due to the cost factor.
As we near the end of this discussion. We hope that it is possible in
the near future to have a host of tests, which will enable an endodontist to
assess the blood flow of the pulp and to make an accurate diagnosis, which
will help in devising proper treatment plan and increase the long-term
success of endodontic treatment.
An evaluation of the use of tooth temperature to assess human pulp
vitality
Thermographic imaging (TI) has also been used to measure tooth surface
temperature (Egg et al 1975. Pogrel et al 1989 kells et al. 2000 a,b)
The work of Pogrel el at (1989) supported the finding so Fanlbunda
(1986b) that. after cooling vital teeth would rewarm more quickly than
nonvital teeth. They also noted a disruptive effect of mouth air Currents.
and advocated the isolation of the teeth by rubber dam to exclude this
effect.
Kells et al. (2000a,b) isolated the eight. most anterior upper teeth in'
human subjects with heavy black rubber, dam and measured tooth surface
temperature using TI. They established that following isolation it took
about 15 min for tooth temperature to stabilize. Despite isolation from
respiratory air currents from both the mouth and the nose they noted a
significant cooling effect by room air currents.
Thermographic imaging is accurate allows comparison of different areas of
a tooth. and is entirely noninvasive. However it requires, considerable
technical expertise and demands rigorous standardization of the
experimental environment. Similarly 1n LDF it is valuable, as an
experimental tool but has limited prospect of becoming a common clinical
investigation in the near future.
CONCLUSION
Status of the pulp should always be collaborated with two or more test .no
one test should be considered final.