DIAGNOSTIC METHODS (Emphasis on Recent Advances) IN ENDODONTICS Correct treatment begins with a correct diagnosis. Arriving at that correct diagnosis requires knowledge skill, and art. Dictionary defines diagnosis as art of identifying disease from its signs / symptoms. Symptoms are the units of information sought in clinical diagnosis. Definition: Symptoms are defined as phenomenon or signs of a departure from the normal and are indicative of illness. Symptoms
Subjective Objective
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Subjective Symptoms are those experienced and reported to the clinician by the patient.
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Objective – are those ascertained by the clinician through various tests.
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Many diseases have similar symptoms, thus the clinician must differentiate one from another.
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Differential Diagnosis – is the most common procedure. This technique distinguishes one disease from several other similar
disorders by identifying their differences.
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Thus the criteria for an accurate clinical diagnosis includes : -
A good case history
-
A thorough clinical examination
-
Relevant investigations / diagnostic tests.
HISTORY Medical Dental Medical: Even though there are virtually no systemic contra indications to endodontic therapy [except uncontrolled diabetes or very recent myocardial infection] a recent and succient, comprehensive medical history is mandatory. It is only with such a history that the clinician can determine whether medical consultation or premedication is required before diagnostic examination or clinical treatment is undertaken. Some patients may require antibiotic prophylaxis before commencing the treatment because of systemic conditions like : -
Heart valve replacement
-
H/o Rh fern
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Advanced Aids
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In case of patients who daily take anticoagulants medications, either the dose may have to be reduced or suspended esp. for periodontal examination. When patients with infectious communicable disease such as AIDS, Hepatitis B or Tuberculosis report dentist and staff must use protection barriers. The clinician must also know what drugs the patient is taking so that adverse drug reactions can be avoided. Patient who present with mental or emotional disorders are not uncommon. In these cases too medical consultation before the diagnostic examination would be in the best interest of patient, doctor and staff. Dental History: After completing, the medical history the clinician should develop the dental history. The purpose of a dental history is to create a record of the chief complaint, the signs and symptoms the patient reports, when the problem began and what the patient can discuss that improves / worsens the conditions.
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The most effective way for the clinician to gather this important information is to ask the patient relevant questions regarding the chief compliant and listen carefully and sensitively to the patient responses. Whatever the reason patient’s chief complaint (C/C) is the best starting point for a correct diagnosis. The most common complaint that leads to dental treatment is PAIN – which is a “subjective symptom”. judicious questioning about the pain can aid the diagnostician in developing a tentative diagnosis quickly. One should ask the patient about: -
Kind of pain
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Its location
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Its duration
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Cause of pain
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What alleviates pain
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Referred to another site or not.
Type / Kind of pain Generally patients describe pulpal pain in one of two ways.
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a. Sharp Piercing and lacinating – such a pain is associated with excitation of “A-Delta” nerve fibres. Pain reflects on reversible state of pulpitis. b. Dull, boring growing or excruciating – associated with excition and slower rate of transmission of the “C” nerve fibres in the pulp. Pain reflects on irreversible state of pulpitis. Localisation of pain The ability to localise the pain is obviously important Pain is localise when the patient can point to a specific tooth or site with assurance and speed. Usually sharp, piercing lancinating pain in a tooth is easy to localise and responds promptly to cold. When the pain is diffuse patient describe an area of discomfort which is due to dull, boring and grawing pain and tooth responds abnormally to heat more than to cold. Duration of pain The duration of pain is also diagnostic Sometimes pulpal pain lasts only as long as an irritant is present. At other time it may last for a longer period even after removal of the irritant
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Referred pain At times pain is referred to other areas and even beyond the mouth. Most commonly it is manifested in other teeth in the same or the opposing quadrant. However, referred pain is not necessarily limited to the other teeth. It may e.g. be ipsilaterally referred to the pre-auricular area or down the neck or the temporal area. In these instances the source of extraorally referred pain almost invariably is a posterior teeth. Patients may report that their dental pain is exacubated with change in position. This occurs because of the increase in blood pressure to the head which increases the pressure on the confined pulp, as pulp is: i. Encase in hard tissue i.e. dentin ii. No collateral supply Pain caused by heat increases on change of position or occurs during mastication of food in a cariously exposed tooth usually indicates a need for endodontic treatment.
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Nature
Acute reversible pulpitis
Irreversible pulpitis
- Pain sharp lancinating
-Dull, boring, growing
perircing
excruciating pain
- Short duration disappears after
Duration
removal of the stimulus
Response to cold/heat Localization
-Longer duration persists even after removal of stimulus - Responds abnormally to
- Responds to cold
heat then to cold
- Usually localized
- Diffuse
Objective symptoms Objective symptoms are determined by the tests and observations performed by the clinician. These tests are Commonly used tests
Advanced diagnostic methods
1. Usual and Tactile inspection
1.
Xero-radiography
2. Percussion
2.
Pulse oximetry
3. Palpation
3.
Laser flowmetry
4. Mobility and depressibility 5. Radiographs
4.
8. Periodontal examination
Computerised tomography
6. Thermal test 7. Electric pulp test
Doppler
5.
Digital
substraction
radiography 6.
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MRI-
Magnetic
9. Anesthesia test
resonance imaging
10. Occlusal pressure test
7.
RVG
Radio-
visiography
11. Gutta-Percha point tracing 8.
12. Transillumination
–
Computerised
expert
system
13. Staining 14. Test cavity
9.
TACT
10.
CITI
Visual and tactile inspection
This is one of the simplest clinical tests.
Mostly the clinician performs this test tool casually as a result much essential information is lost.
A thorough visual, tactile examination of hard and soft tissues relies on three “CS – i.e contour, Colour and consistency”.
In case of soft tissues e.g. GINGIVA Colour –
Deviation from healthy pink colour to red colour is seen as in inflammation.
Contour –
Swelling causes change in contour
Consistency – In pathologic conditions gingival becomes soft, spongy and fluctuant.
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In hard tissue i.e. TEETH Colour – Normal appearing crown has a life like translucency and sparkle, where as teeth with necrotic pulp may appear discoloured, opaque and less life like. The discolouration can be caused by (apart from necrotic pulp) i)
Old amalgam restorations
ii)
Root canal filling materials and medicaments
iii)
Systemic medicaition such as tetracycline
Thus not all discoloured teeth require endodontic treatment. Contour Change in crown contour can occur due to: -
Fractures
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Wear facets
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Restorations
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Abrasion
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Erosion
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Attrition
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Developmental defects
Clinician should be prepared to evaluate the possible effects of such changes on the pulp.
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Consistency : of hard tissues relate to the presence of caries and internal or external resorption. Technique -
Technique is simple. It can be performed with finger, an explorer and periodontal probe.
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The test should be carried out in good light under dry condition.
This is because: (i) if covered by saliva clinician may not be able to detect the presence of a sinus tract (ii) same way if packed with food interproximal cavity may escape notice (iii) loss of translucency slight colour changes cracks may not be visible in poor light. -
Visual examination should also be used routinely to determine the periodontal status of the suspected tooth and adjacent teeth.
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The crown of the tooth should be carefully evaluated to determine whether it can be restored properly after completion of endodontic treatment.
Percussion -
This test enables one to evaluate the status of the periodontium surrounding a tooth.
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This test can be done using the finger or with the handle of an instrument.
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A painful response to percussion signifies inflammation of the periodontal membrane (Periodontitis).
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In performing this test, several teeth are percursed in a random order, to eliminate bias on part of the patient.
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One should change the direction of the blow from vertical-occlusal to the buccal or lingual surface of the crown and strike separate cusps in a differing order.
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Percuss a tooth very gently (not beyond patients tolerance) and if no response, sharp tap is given.
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Percussion may be misleading if used alone, thus used in conjunction with other periodontal tests such as palpation mobility and depressibility.
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A tender tooth does not always denote a pulpal involvement (i.e. Pulp necrosis)
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Apart from pulpitis, tooth may be tender in acute periodontal abscess.
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Acute apical peridontitis may also result from traumatic occlusion or sinusitis, though the pulp is vital.
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Absence of a response to percussion may be seen in chronic periapical inflammation.
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A dull not signifies abscess formation and a sharp note merely inflammation.
Palpation -
This simple test uses light pressure with the fingertip to examine tissue consistency and pain response.
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Although simple, it is an important test.
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Main features of the test are: i)
Helps in location of swelling over an involved tooth
ii)
Whether the tissue is fluctuant and enlarged sufficiently for incision and drainage.
iii)
The presence, intensity and location of pain
iv)
The presence and location of adenopathy i.e. Palpation of lymph nodes
v)
The presence of bone crepitus.
Note: During palpation of lymph nodes in the presence of an acute infection care must be assured to avoid the possible spread of infection through the lymphatic vessels. -
Diagnostically when posterior teeth are infected the submaxillary lymph nodes are involved and in lower anterior teeth infection submental lymph nodes are involved.
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When the infection is confined to the pulp and has not progressed into the periodontium palpation is not diagnostic.
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Excluding abscess formation associated with a periodontal disease, swelling of the mucosa over the root apex of a tooth denotes partial or complete necrosis of pulp.
Mobility – Depressibility testing: -
This test is used to evaluate the integrity of the attachment apparatus surrounding the tooth.
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The objective of this test is to determine whether the tooth is firmly or loosely attached to its alveolus.
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Greater the movement, poorer is the periodontal status.
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The test consists of moving a tooth laterally in its socket
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Mobility is detected by using i.
Finger.
ii.
Handles of two instruments.
iii.
Mobilometers.
Classification of mobility (According to Cohen and Grossman) Ist Degree
–
Barely discernible movement
IInd Degree
–
Horizontal movement of 1mm or less.
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IIIrd Degree
–
Horizontal movement of greater than 1 mm often accompanied by vertical movement.
Horizontal root fracture in the coronal or middle third and chronic bruxism also cause tooth movement apart from periodontal disease. Mobilometers: (Periodontometer) – By Mehlemann in 1954. -
Small force is applied to the crown, crown tips in the direction of force.
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Resistance to displacement of root is less initially. When force is gradually increased the crown displacement also increases.
Disadvantage : Not practically useful for large surveys as the instrument is attached in dental unit. Depressibility -
The test for dpressibility consists of moving a tooth vertically in its socket.
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Performed with fingers or with an instruments when depressibility exists, the chance of retaining the tooth ranges from poor to hopeless.
Radiographs: -
Radiograph is one of the most important clinical tool in making a diagnosis.
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But some clinician rely solely on radiographs to arrive at a diagnosis which can lead to major errors in diagnosis and treatment.
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As the radiograph is a two dimensional image of a three dimensional object mis inter pretation is a constant risk.
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To use radiographs properly, the clinician must have the knowledge and skill necessary to interpret them, thorough understanding of the underlying normal or anamolus anatomy and the changes that can occur due to aging, trauma, disease and healing.
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To avoid errors misinterpretation and to produce an excellent radiograph, the following points should be kept in mind. i. Proper placement of film in patients mouth; ii. Correct angulation of the cone with regard to film and oral structure. iii. Correct exposure time iv. Correct processing of the film.
Radiograph provide pertinent information regarding: i.
Presence of caries that may involve or threaten to involve the pulp.
ii.
Root anatomy – Show the number, course, shape, length and width of the root canals.
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iii.
The presence of calcified material in pulp chamber or root canal.
iv.
Resorption – Internal / external
v.
Calcification or obliteration of the pulp cavity-pulp-stones
vi.
Thickening of the PDL.
vii.
Resorption of cementum.
viii.
Nature and extent of periapical and alveolar bone destruction.
ix.
Root fracture.
x.
Anatomical landmarks (Normal structures) associated with roots - Maxillary sinus. - Mandibular canal - Mental foramina
Radiographic interpretation -
Interpretation of good – quality radiographs must be done in an orderly and consistent manner.
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The radiographs may reveal early pathologic changes in or around the tooth.
A. Root anatomy Radiographs provide essential information relative to i. Normal and abnormal root formation. ii. Extra root and root canals. iii. Curvatures iv. Invagination and dens in dente 16
Extra root or root canals It is necessary to identify these, canals on radiograph for the success of treatment. -
Extra roots can be more clearly viewed if the horizontally directed beam is from the mesial aspect.
Canals i)
If “an extra-dark line” is present in the coronal third of the root running parallel to the instrument, a second canal may be present. E.g. Mesiobuccal of maxillary molars and distal of lower molars.
ii)
“Slowey” described another diagnostic aid – “the fast break”. A sudden change in the radiolucency with in a canal signals the presence of an additional canal e.g. maxillary 1st premolars.
iii)
Buccal object rule It states that when radiograph is taken from mesial angulation. Buccal canal will appear the most distant one. This rule is used in radiographs taken for working length.
Curvatures Curvatures on buccal or lingual aspect are difficult to be viewed in radiographs.
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B. Lesion within the tooth. i. Pulp stones ii. Pulp calcifications iii. Internal resorption iv. Root fractures (i) Internal resorption should be differentiated from external resorption. Internal 1.
External
Has sharp, smooth margins that can be clearly defined.
The margins are rough, vary in density and have a moth-eaten appearance.
2.
The pulp “disappears” into the
lesion –
not
The radiographic outline of the
extending
root canal is often apparent within
through the lesion in its regular
the radiolucent area of resorption.
shape. 3.
When viewed from different
If the defect is external the
angulation, defect in relation to
relationship of the defect to canal
canal will remain constant
will
shift
on
altering
the
angulation. (ii) Root fractures -
Fractures of root are difficult to detect on a radiograph.
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Vertical root fractures can only be diagnosed in advanced cases of root seperation as compared to horizontal fractures which can be readily identified on a radiograph.
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-
Horizontal fractures must be differentiated from linear patterns of bone trabecular. o Root fracture causes thickening of periodontal ligament while bone trabecular extend beyond the border of the root.
C. Lesion outside the tooth seen on radiographs -
Radiographs do not show much changes in initial pulp necrosis because to reveal changes on radiograph, 60% cortical bone of destruction is necessary. i. Widening of periodontal space is seen in o Acute apical periodontitis o Acute apical abscess o Advanced pulpitis and root fracture o Changes associated with chronic periapical abscess. ii. External root resorption. iii. Changes associated with chronic periapical abcess.
D. Radiographic changes as a sequelae of pulp necrosis. i)
Chronic apical periodontitis a. Well-circumscribed osseous lesion b. Radiolucent area varying in size from few mm to few cms c. Borders may appear to be radio-opaque
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ii)
Apical cyst a. Difficult to differentiate from chronic apical periodontitis. b. More circumscribed with a dense bony perimeter. c. May move the roots.
Radiographic misinterpretations: This is a common problem. To avoid such a problem radiograph must be taken from two or more horizontal angulations. The radiographic phenomena that cause misinterpretations are: i)
Mental foramen – which gets superimposed over the apex of mand. Premolars and is mistaken for a periapical lesion.
ii)
Nasopalatine canal – Well circumscribed radiolucency at or near the apex of upper centrals. On change of angulations if radiolucency is a lesion it will be still
attached to apex. Differential diagnosis A number of pathologic changes in and near the alveolar process are mistaken for true periapical lesion.
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a. Lesion of non-odontogenic origin: i)
Globulomaxillary cyst
ii)
Midline palatine cyst
iii)
Nasopalatine On change of horizontal direction of central beam these structures
shift. b. Periodontal lesions should be distinguished from periapical lesion. - Silver or gutta – percha points help to detect the source of lesion. c. Periapical osteofiberosis / cementoblastoma d. External root resorption from lesion of pulp origin. e. Between abscess; cyst and granuloma - Clinical diagnosis of a pulpal disease must be supported by thermal and electric pulp tests. THERMAL TEST -
One of the most common symptom associated with inflamed pulp is pain induced or relieved by hot or cold stimulation.
-
Thus thermal tests are one of the valuable diagnostic aids.
Technique -
Explain the patient about the procedure
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-
Isolate the teeth
-
Check on normal side first and then on the involved teeth.
-
Ask the patient to raise a hand as soon as any sensation is felt.
-
Remove the stimulus immediately when sensation is felt. The heat or cold tests are performed by placing the stimuli in:
Anterior teeth – on the incisal 3rd of crown of labial surface Posterior teeth – occluso buccal surface. Heat test: -
The heat test can be performed using different techniques that deliver different degrees of temperature.
-
According to Cohen temperature preferred is approximately 65: 5°C.
-
In an article by A.H.R. Rowe and T.R PittFord (International endodontic Journal, 1990) the test may produce temperature as high as 150°C at the surface of the tooth.
-
Heat test can be carried out using i) Warm air blast ii) Hot water iii) Hot burnisher
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iv) Hot gutta-percha – Heat it until it becomes shiny and sags but before it smokes. v) Hot compound. -
Where a gold crown is present heat is applied by simply polishing the crown with an abrasion disc.
-
Precautions: Care must be used in applying these all heat test because the pulp may be damaged by overheating. o Remove stimuli as soon as patient feels sensation o Never place an overheated gutta-percha as it may cause a “burn lesion” in an otherwise normal pulp. o Apply Vaseline / cocoa butter to prevent the sticking of gutta-percha on the tooth.
-
A different technique is required for application of hot water. Tooth is isolated under the rubber dam and is immersed in “Coffee
hot” water delivered from a syringe. Disadvantage: Response is limited to one tooth. Advantage: Effective for a tooth with porcelain or metal full coverage restorations (According to Cohen). Cold test: -
For cold testing teeth must remain dry and isolated.
-
Most common technique to apply cold are:
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o A stream of cold air o Ethyl chloride spray – it evaporates rapidly absorbing the heat and thus cooling the tooth. -
It can be carried out under the rubber dam or applied on a cotton pellet and held against the tooth to be tested.
-
This technique is effective even on teeth with cast metal crowns. o Sticks of ice o Carbon dioxide snow (dry ice) o Feron 12 o Dichloro – diflouro methane
Carbon dioxide snow: -
Use of dry ice was described by ‘Ehrmann’
-
Because the temperature of dry ice is – 78°C, pulp vitality can be tested in teeth with full coverage restorations.
Responses to thermal tests -
The patient’s responses to heat and cold testing are identical because the neural fibres in the pulp transmit only the sensation of pain.
-
These are four possible reactions the patient may have
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a.
No response i.
Indicates a nonvital pulp
ii.
Possibly vital but gives a false +ve response due to o Excessive calcification o An immature apex o Recent trauma o Patient premedication
b.
A mild to moderate transient thermal pain response which is considered normal.
c.
A strong painful response which subsides quickly after the stimulus is removed signifies reversible pulpitis.
d.
A strong painful response that lingers after stimulus is removed, indicates a “sympatomatic irreversible pulpitis�.
ELECTRIC PULP TEST: -
The electric pulp tester is designed to simulate a response by electric excitation of neural elements with in the pulp.
-
The electric pulp tester is a valuable tool for diagnosis; as it helps the clinician in determining pulp vitality and also helps to distinguish between pulpal, periodontal or nonodontogenic causes when used along with radiographs and thermal test.
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Although pulp vitality is dependent on intiapulpal blood circulation, no practical clinical test has been devised to test circulation. The electric tester, when testing for pulp vitality, uses nerve stimulation instead. The objective is to stimulate a pulpal response by electric current. A +ve response indicates vital pulp. No response indicates – pulp necrosis. Technique (By Grossman) a.
Describe the test to the patient in a way that will reduce anxiety and will eliminate a biased response.
b.
Isolate the area of teeth to be tested with cotton rolls and a saliva ejector, and air-dry all the teeth.
c.
Check the EPT for function, and determine that current is passing through the electrode.
d.
Apply an electrolyte (tooth paste) on the tooth electrode, and place it against the dried enamel of the crown’s occlusobuccal or incisobuccal surface. Avoid contact with any restorations, adjacent gingival tissue with the electrolytic or electrode, which causes a false response.
e.
Retract the patient’s check away from the tooth electrode with the free hand which will complete the electric circuit.
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f.
Turn the rheostat slowly to introduce minimal current into the tooth, and increase the current slowly. Ask the patient to indicate when sensation occurs by using words such as “tingling” or “warmth”. Record the result according to the numeric scale on the EPT.
g.
Repeat the tests 2-3 times to avoid false readings.
Response to electric pulp test is affected by a. Enamel thickness. Thicker the enamel more delayed the response. Anterior teeth – yield a quicker response. Posterior teeth – slow response b. Patients level of anxiety / patient with an unusual high pain threshold. c. Full crown restoration / teeth with extensive restorations. d. Traumatized teeth / recently erupted teeth with incomplete root formation. e. Placement of probe tip. f. Teeth with pulp protecting base and sedative medication. False reading: The results from electric pulp test should be misleading in certain situations. False readings are divided into two
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i)
False – Positive
ii)
False – Negative
False positive – Readings means the pulp is necrotic but the patient feels the sensation. Main reasons for false positive response : a. Electrode in contact with a restoration (full crown, amalgam) or the gingiva allows the current to reach the attachment apparatus. b. Patient anxiety : patient must be instructed about the procedure and to raise the hand when he feels sensation. c. Liquefaction necrosis may conduct current to the attachment apparatus, (and the patient may raise his hand near the highest range). d. Failure to isolate and dry the teeth properly. e. In posterior teeth in which the pulp is partially necrotic with some nerve fibres still vital in one or more canals. False Negative : Reading means the pulp is vital but the patient appears unresponsive to EPT. Main reasons are: 1.
Pre-medications (with analgesics, narcotics, alcohol etc)
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2.
Inadequate contact with the enamel.
3.
Recently traumatized teeth.
4.
Excessive calcification in the canal.
5.
Dead batteries or if the pulp tester is not turned on
6.
Recently erupted tooth with an immature apex
7.
Partial necrosis.
Disadvantages a. It gives no indication of the state of vascular supply, which would give a more reliable measure of the pulp vitality. b. Readings taken from posterior teeth may be misleading because some combination of vital and non vital root canal pulps may be present. c. It cannot be used in patients with cardiac pacemaker because of potential interference with the pacemaker. d. Response not achieved correctly when glores are worm. e. Cannot be used for recently traumatized and immature apex. As response is not proper.
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f. It should not be done on teeth with full coverage restoration because an electric stimulus cannot pass undistorted through acrylic, ceramic a metallic portions of crown. g. Probe tip of EPT is removable and falls out easily. Advantages 1.
Intensity of stimulus is comfortable to the patients.
2.
The digital display of many E.P. Testers provide instant, easy and reliable information.
3.
In some EP testers a red indicator light flashes on and off when maximum stimulus is reached.
4.
Gives a quantitative reading and can be compared with the normal reading of control tooth.
Types of EPT : Two main varieties of pulp testers available arc (Nicholls). I. Monopolar / Bipolar -
Another method of differentiation of pulp testers according to Nicholls
II. Current is varied or voltage is varied.
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The former is considered preferable since a given voltage may lead to different amounts of current due to variation in the electrical resistance of tissues, especially enamel. Some of the EPT commercially available today are: a. Analytic technology pulp tester. b. Digilog pulp tester (battery operated). c. Pelton – crane compact, transistorized bettery operated electric pulp tester. d. Parkel : pulp tester (Battery – operated) e. Neotest ADP (automatic digital pulp tester). f. Green wood pulp tester. Analytical technology pulp tester: -
A battery operated instrument of –15 to –300 volts peak and a current from 1050 µ amp.
-
Each time the display increases one digit, one burst of 10 pulses of negative polarity is applied to the tooth (i.e. stimulus is produced in bursts of ten high – frequency pulses of –ve polarity.
-
The EPT is turned on automatically when the probe tip touches the tooth and turns off after the contact is broken.
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-
The readings are from 0 to 80. A newer model of ATPT is lip – clip attachment.
Green Wood pulp tester: This type of pulp tester requires an assistant to control the increase in current. There is no indication when electrical contact has been established or broken with the tooth. PERIODONTAL EXAMINATION -
Diagnosis is not complete unless the periodontal tissues are examined properly.
-
The periodontal tissues are examined using a periodontal probewhich is thin, blunt and has gradations / markings.
-
Periodontal probe is used to examine the gingival sulcus and depth of the pocket, for furcation involvement, exposed lateral canal.
-
To distinguish lesions of periodontal origin from those of pulpal origin, thermal and electric pulp test along with periodontal examination are essential.
ANESTHETIC TEST: -
In the uncommon circumstance of diffuse strong pain of vague origin when all other tests are inconclusive conduction, selective
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infiltration, or intraligamentary aneasthesia can be employed to help identify the source of pain. -
The basis for this test lies in the fact that pulpal pain, even when referred is almost invariably unilateral and stems from one branch of trigeminal nerve.
Technique -
Using either infiltration or the intraligament injection inject the most posterior tooth in the area suspected of being the cause of pain.
-
If pain persists, anesthesize the next tooth mesial to it and continue to do so until the pain disappears.
-
If source of pain is not determined whether in maxillary or mandibular give inferior alveolar block. If pain disappears it indicates involvement of mandibular tooth and localization of pain is done with intraligament injection.
Intraligamentary injection -
Most painful injection
-
Administered in the distal sulcus of each suspected tooth.
-
When involved tooth is anesthetize with this injection pain stops immediately but for few seconds.
TEST CAVITY:
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-
The test cavity involves slow removal of tooth structure to determine pulp vitality.
-
The test cavity is made by drilling through the enamel dentine junction of an unanesthetized tooth.
-
The cavity is prepared with a round bur at slow speed without a coolant.
-
This test is carried out only when other means have failed therefore disadvantage of this test is iatrogenic damage.
-
Pain or sensation felt by patient indicates vital pulp and thus the test is performed on other teeth until the involved tooth is found.
OCCLUSAL PRESSURE TEST: -
One of the patients complaint is pain on biting.
Causes can be -
Acute apical abscess
-
Periodontal abscess.
-
Incompletely fractured tooth
Different methods used in this test are: i.
Cotton – wood stick
ii.
Cotton – roll
iii.
Tooth slouth – an autoclavable plastic device
iv.
Rubber wheel-Burlew rubber disc. 34
-
Diagnosis of incompletely fractured tooth is one of the most difficult in endodontics.
-
These above mentioned methods may help in detecting a fracture.
Cotton wood stick may reveal the split tooth. The tooth slouth can be applied to the occlusal surfaces of various cusps and the biting / chewing test can be gently repeated. At times the tooth readily identifies the split tooth. A rubber polishing disc can be used to confirm the presence of a cracked crown when the patient bites on the disc, it acts as a wedge on the cracked tooth and causes pain. In case of “cracked tooth syndrome” – on biting (on cotton application or rubber wheel) the fracture segments may separate, and pain may be reproduced at intiation or release of biting pressure. TRANSILLUMINATION: -
Emergence of the fiberoptic as a dental instrument has been a great aid in the use of transillumination for diagnosis.
-
The test requires shining a light from lingual / palatal surface.
-
Transmission of powerful fiberoptic light through teeth helps to detect interproximal caries and a fracture mainly the vertical.
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-
During this test operating light is switched off and fiberoptic light is moved closed to neck of the tooth.
-
Light does not pass through fracture, thus the part of tooth beyond fracture remains dark.
-
Fiberoptic light sources are available with rubber dam clamp attachment
-
Most reliable results are obtained if restorations are removed before the examination.
GUTTA PERCHA POINT TRACING: -
Diagnostic silver cone and gutta percha trace the periodontal defect to the apex or an endodontic lesion.
-
Gutta-percha point is placed in the gingival sulcus through the sinus / fistula; A radiograph is taken and an endodontic lesion is localized in relation to a specific tooth.
-
The point tracks back to the source of infection.
STAINING: This test is used to identify and locate a vertical fracture. Different dyes used are: 1.
1-2% methylene blue.
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2.
Food coloring agents
3.
The occlusal surface is cleaned with a cotton pellet lightly moistened with 70% isopropyl alcohol. The alcohol washes away the food coloring on the surface, but the food coloring within the fracture since remains and becomes apparent. - Dye solution stains the fracture line.
4.
2% Iodine
ADVANCED / SPECIAL DIAGNOSTIC AIDS -
The present methods available for diagnosing the state of pulp are crude and not fully reliable.
-
Current research may well produce new ways of pulp testing.
a. XERORADIOGRAPHY: -
Xero-radiography is a new technology using the xero-radiography copying process to record images produced by dental X-rays.
-
“Xerox” is a Greek word meaning “dry”. This differentiates xeroradiography from conventional photochemical system which requires a dark room.
Technique: -
This technique uses a rigid aluminium photo receptor plate.
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The plate is electrically charged, placed in a light – proof plastic cassette, positioned in the mouth and exposed to X-rays. -
The entire technique of film processing is fast, requiring only 25 seconds for a dry permanent image.
-
The plates may be reconditioned, recharged and used repeatedly. The xeroradiograph may be viewed either by reflected or
transillominated light. The image gives a range of greys than the conventional X-ray film (which exhibits optical densities from black through gray to white). Advantages: 1. Xero-radiograph has the reoperty of edge enhancement of image boundaries. 2. Small structures are depicted with much clarity i.e. produces sharper, clearer image. 3. Xeroradiography provides better visualization of metallic instrument tips and root apices allowing more accurate length measurements. 4. Reduced radiation dose to patient. It appears to be a valuable addition to the endodontists diagnostic armamentarium.
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Pulse – Oximetry (JOE Vol. 17, No. 10 Oct 1991 Pg-488) -
Pulse oximetry has emerged as the leading non – invasive monitoring device for determining the oxygen (PO2) saturation and pulse rate of patients under intensive care or during sedation procedure.
-
The principle is simple in that light is passed from a photoelectric diode across a part of the body and into a receptor. The difference between the light received and light emitted is
calculated in a microprocessor to provide pulse rate and oxygen (PO2) saturation readings. Pulp oximetus used red and infra red wavelengths in order to transilluminate a tissue. Two wavelength of light are emitted from the diode to detect oxygenated haemoglobin (arterial blood) and deoxygenated haemoglobin (venous blood). -
It is the ratio of the absorbence of the wavelengths that provide percentage of oxygenation of the blood.
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This method of determining O2 saturation through haemoglobin concentration is extremely accurate as compared with former methods of blood gas sample analysis.
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Lack of neuronal response does not always indicate pulpal death; this test allows an immediate objective diagnosis of vascular integrity without inducing painful stimulation.
Limitations: 1.
Intrinsic – excessive CO2 in blood interfering with deoxygenation value.
2.
Extrinsic – Movement of probe, Overhead xenon arc lamps, Problems with probe itself.
Advantages 1. Verifies vitality in traumatized teeth as well as potential analysis of the stage of pathological process of pulp. 2. Method is clearly superior to other vitality testing methods since it does not rely on sensory nerve response. -
A probe developed for tooth testing was designed to consider the curvature of teeth and thus prevents false reading from the distortion of beam as it passed through a convex surface.
LASER DOPPLER FLOWMETRY -
Until recently pulpal blood flow measurement of intact human teeth was vision. There have been a number of attempts using various methods e.g. photoplethysmography and ultrasound Doppler,
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however the most promising method for potential development in the dental field is laser Doppler technique (LDT). -
Tooth vitality is related to pulpal blood flow and not to the function of sensory fibres as commonly tested by electric and thermal pulp tests.
-
The first indication of the ability to measure pulpal blood flow noninvasively using laser Doppler technique was shown in “1986 by Gazelius et al”.
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Also it was demonstrated the laser Doppler technique was capable of assessing tooth vitality by Olgart et al in 1988 and revascularization of traumatized teeth by Gazelius et al 1988.
Laser Doppler flowmetry has two system a. Closed system b. Open system Closed system The equipment used was a periflux PF2, with a Helium – Neon laser source emitting light at 632.8 nm. -
The probe fibres were of 0.75 mm diameter with a core seperation of 0.75mm.
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As the light hits various components of the tissues it is partially absorbed and partially back scattered. The back scattered light has 2 components: 1. Light – back scattered from static tissues which has the same frequency as the light going in 2. The other component is the Doppler shifted light with a different frequency. The back scattered light is processed and an output signal is produced i.e. both the unshifted and shifted light is transmitted to a detector by optical fibres where it is transduced / charged into electric current and processed. The detected output signal can be fed into analog printer, or be read from a digital board. -
The combination of a silicon splint for immbolization of the probe (closed system) and the use of 4 KHz signal bandwidth. Filter reduced the movement artefact, while increasing the signal differentiation between vital and non-vital teeth.
Advantage: -
This method ensures high accuracy of results.
Disadvantage: -
Technique is too complex
-
Time consuming
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Open System To overcome the limitations of original technique (closed system) a new instrument was developed known as LA VITAL (Sweden) Technique -
This instrument was used in combination with a laser diode emitting light at 750 nm
-
This instrument uses a rigid probe that is hand held on the buccal surface of the tooth during measurement (open system).
Advantages: -
Simple method
-
Less time consuming
Disadvantages: -
The greater penetration of 750 nm laser increases the risk of signal contributions from the surrounding tissues.
Advantages and limitations of laser Doppler flowmeters Advantages: 1. They are non – invasive 2. Simple to apply 3. Provide a continuous or near continuous record.
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Disadvantages of LDF 1. It is impossible to calibrate them in absolute units and their outputs may not be linearly related to blood flow. E.g. if the output signal increases by 100% it cannot be assumed that the blood flow rate has increased by 100%. The fact that they cannot be calibrated in absolute units stems from the fact that the signal derived from any one moving cell will depend upon the distance of that cell from the recording probe, and this distance is not known. Note: Avoid movements between the probe tip and underlying tissues to avoid artefacts or false data. While examining the teeth the probe can be fixed rigidly to tooth surface with some form of splints to avoid movements. -
These instruments provide a very valuable method for studying pulpal blood flow, but data they provide must be interpreted with care.
-
A new method is ‘Excimer laser system’ emitting 308 nm for residual tissue detection with in the canals (PINI et al 1989).
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RADIOVISIOGRAPHY (RVG) -
A new radiographic system called “radio vasiography (RVG)” developed in France by Dr. Francis Mouyen digitize ionizing radiation.
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The system provides an instantaneous image on a video monitor while reducing radiation exposure by 80%.
The RVG device has threee components a. ‘Radio’component -
It consists of a hypersensitive intra-oral sensor and a conventional X-ray unit.
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The small sensor confirms a fluoroscopic sensor screen, a set of optic fibres, and a miniature charged coupling device; that translates the image produced into an electronic signal that is transmitted to display – processing unit.
b. “Visio” portion -
It consists of a video monitor and display – processing unit.
-
As the image passes to the processing unit, it is dizitised, memorized by the computer and immediately displayed on the monitor. (This image is magnified four times).
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c.
“Graphy” component A high resolution videoprinter that instantly provides a hard copy of
the screen image, using the same video signal. Use of RVG: It is useful to measure the working length accurately. Advantages of RVG: 1. Eliminates the use of X-ray film. 2. Significant reduction in exposure time (100th of sec). 3. Instantaneous image display. 4. It can display multiple images. 5. As the image is digitalized further manipulation of image is possible. -
A recent study showed that RVG resolution is less than that’s produced with silver-halide film emulsions; but radiographic information can be increased by enhancement procedures.
-
The system appears very promising for endodontics.
DIGITAL RADIOGRAPHY: -
This process enables a digitized image to be manipulated by a computer and displayed on a screen.
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Although it is possible to capture an image in the digital form electronically, most digital imaging in dentistry uses standard radiology techniques using a film which is digitally processed. The basis of this technique is that image is divided into a grid or matrix of uniformly sized pixels, each of which is assigned a gray-scale value based on its optical density. One of the most useful operations involves a comparison of images called “Digital substraction radiography”. Advantages of DSR – Superior of conventional radiograph. Limitation of DSR – Cannot detect whether lesion is on buccal / lingual aspect. It consists of a charged coupled device (CCD) camera and a view box. Uses: 1. Digital substraction radio graphy is very useful in detection of lesion such as interproximal caries and also helpful to view the progression of caries from incipient lesion to as the lesion progress to DEJ. 2. It also helps to evaluate bony changes or the healing process or repair. 3. Helps to evaluate the treatment outcomes after endodontic therapy.
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COMPUTED TOMOGRAPHY: -
Computed tomography was introduced in Mid 1970.
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Computed tomography is a radiographic technique that blends the concepts of this laser radiography with computer imaging (computed).
-
Techibana has reported about the use of X-ray CT in bucco-lingual and mesio-distal widths of teeth and the presence or absence of root canal filling materials and metal posts. Also observable are the carious lesions, extension of the maxillary sinus and its proximity to the root apices.
Advantages 1. Observations of structures, which are difficult to visualize with conventional X-ray. 2. Provides images for 3-D reconstruction of roots, root canals and teeth. Disadvantages: 1. Expensive 2. Skin dose is large 3. Time consuming
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MAGNETIC RESONANCE IMAGING -
Recently MRI has been tried out as a diagnostic tool in endodontics.
-
MRI generates high quality cross – sectional images of the body.
-
However,
this
needs
very
large
equipment.
The
high
electromagnetic waves which are needed have not been approved of for use in scanners. It is believed that MRI machine will be developed for evaluation of odontogenic problems. Disadvantages: Not to be used in patients with cardiac pacemakers, metallic restorations or ortho-appliances, aneurysms. COMPUTERIZED EXPERT SYSTEM -
Reported by John Firriola
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Computerized expert system is used for the diagnosis of selected pulpal pathosis viz.,
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Normal pulps
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Reversible pulpitis
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Irreversible pulpitis due to hyper-occlusion
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Irreversible pulpitis
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Necrotic pulp
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Infection due to endodontic failure
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-
Appropriate diagnostic case facts are obtained and this data is entered into the computer. The computer checks and gives out the diagnosis. With the rapid advances being made in the field of computers, we may get many more programmers for efficient endodontic diagnosis. TACT (tuned aperature computed tomography) (Endodontic Dental
Traumotology 2000 Vol. 16 : 24-28). -
This is a relatively new type of imaging device that may have advantages over current radiographic modalities in viewing an object while decreasing the superimposition of the overlying anatomical structures.
-
It is a charge coupled device (CCD) based technique.
Uses 1. Used to detect external root resorption mainly. 2. To detect recurrent dental caries. 3. To detect simulated osseous defects. -
It consists of a standard radiographic unit, a digital image acquisition device, and necessary TACT software to reconstruct the images.
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Advantages of TACT over conventional radiography 1. Detects small size defects 2. Less radiation exposure. 3. Localizes a lesion accurately. 4. Detects lesion in bucco-lingual dimensions. COMPUTERIZED INFRA-RED THERMOGRAPHIC IMAGING (International Endodontics 33 Vol. 2 : 443-447.) -
This technique is another non – invasive method of detecting the surface temperature of a body.
-
It is highly technique sensitive and is still under research.
Summary and Conclusion -
To conclude, one could say that the determination of the exact pulpal status i.e. vital or necrotic is complex and is dependent on number of factors viz, patient history, clinical examination and various diagnostic tests conducted.
-
However, with the advent of newer diagnostic techniques such as pulse oximetry, laser Doppler flowmetry, and radiovisiography that are more quicker, easier and precise diagnostic means. The results of the newer diagnostic tests should never be relied upon individually but on the contrary it should be utilized in combination in order to arrive at a correct final diagnosis.
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