Examination and Diagnosis

(1)

Canberra, ACT, Australia
 
Summary
The challenge when assessing the dental pulp status is complicated since no single diagnostic pulp testing technique can reliably diagnose all pulp conditions. An assessment of the patient history with respect to the problem tooth, careful clinical examination including diagnostic tests and appropriate radiographs will enable the clinician to arrive at the best probable diagnosis.

Clinical Relevance
Assessment of the dental pulp status is undertaken using a combination of diagnostic tests including thermal and electrical tests that indicate the functioning of Aδ nerve fibres only. For many teeth the tests are quick and often reliable but on occasion these tests are inconclusive and do not represent the true status of the pulp in disease. The clinician must be aware of the shortcomings of these diagnostic tests and be able to interpret results with confidence thereby serving the patient in their best interests. Alternative methods to assess pulpal status of teeth include physiometric testing such as laser Doppler flowmetry, which although prove valuable have yet to become established in our common practising lives.

11.1 Overview of Endodontic Diagnosis

Vitality testing is an important tool in the diagnosis of pulp disease and apical periodontitis. Several devices or procedures are available to the clinician when determining whether the pulp is vital or not. Commonly used diagnostic procedures include a detailed pain history, thermal testing (hot and cold), electronic pulp testing, assessment of the tooth for presence of mechanical allodynia and radiographic detection of peri-apical disease. If the pulp is deemed to be unhealthy based on diagnostic tests, then endodontic treatment is indicated. Pulp vitality testing has been recommended when assessing traumatised teeth over an extended period to monitor their vitality following the traumatic incident. Traumatised teeth, which may initially not respond to testing, may well do so after a period of weeks or months. It is also important to assess pulp vitality prior to undertaking extensive tooth preparation in order to improve the prognosis of the restoration. Vitality testing may also be indicated for the periodic assessment of continued pulp vitality in teeth that have undergone pulp preservation procedures (such as indirect or direct pulp capping). Patients typically attend our surgeries on a daily basis with pulpal complaints such as extended thermal sensitivity associated with irreversible pulpitis. Vitality testing is a prerequisite in the diagnosis of the offending tooth in such cases where one needs to clearly identify the source of the complaint and reproduce the symptoms to confirm suspected diagnosis [14].
As dentists we are involved in diagnosing disease as part of our everyday clinical practice. A range of tests, systems, guides and equipment, which can be generally referred to as diagnostic procedures, are available to aid in diagnostic decision-making. It is well known that the available diagnostic procedures, used to assess pulp vitality, are not completely reliable, specific or sensitive in determining the true nature of the pulp status [510].
Clinical studies have demonstrated that there is no direct correlation between signs and symptoms of the pulp and histological diagnosis [1113]. From a clinical standpoint the clinician is only able to indicate the probable status of the pulp. It is therefore recommended that any pulpal diagnosis made should be based on all the information readily available not reliant on any one test in particular.
Current vitality testing is assessing the integrity of the Aδ fibres present in the pulp–dentine complex by application of thermal or electric stimulus. The tests indicate that the nerve fibres are conducting but do not give any indication as to the blood flow within the tooth and whether there is any damage. In general when there is a diminished blood supply within the tooth, the anoxic effects result in irreversible damage to the Aδ fibres and loss of function. Hence a nonvital tooth will not respond to thermal or electrical pulp testing. A positive response would usually indicate a healthy tooth. A negative response could indicate the possibility that the tooth is necrotic. A prolonged response to thermal stimulus may indicate an irreversibly damaged pulp. Often multi-rooted teeth may give rise to false-positive or false-negative results depending on the differing pulp status within the individual canals. The tests themselves may also be unreliable giving false-positive or false-negative results depending on how the test has been carried out, the age of the patient and the presence of a calcified canal system with diminished pulp volume and history of trauma. Since the responses to these tests are subjective in nature, patient interpretation may influence the clinicians’ determination as to whether the test result is normal or not [4, 1419].
Application of a cold stimulus causes a rapid movement of dentinal fluid resulting in ‘hydrodynamic forces’ acting on the Aδ nerve mechanoreceptors within the pulp–dentine complex leading to a sharp sensation lasting for the duration of the thermal test (see Chap. 1). The notion that the prolonged application of cold stimulus to teeth resulting in irreversible pulp damage is unfounded [20]. Cold tests should be applied until the patient definitely responds to the stimulus or for a maximum of 15 s, whichever comes first [20]. Dichlorodifluoromethane (DDM) and carbon dioxide (CO2) snow are more reliable compared to ethyl chloride [2124]. The cold test is particularly useful when assessing teeth with full coverage restorations [25].
Application of a hot stimulus to provoke a pulpal response can be carried out using a number of methods including heated gutta-percha, hot water applied by a syringe and direct application of heat source (system B). The disadvantage of using heated gutta-percha is that prolonged heating could result in pulp damage. Application of heat should be for no more than 5 s [26].
Electric pulp testing (EPT) stimulates intact AD nerve fibres within the tooth on electrical stimulation. The readout is not a quantitative measurement whereby indicating how healthy or to what degree the pulp is inflamed. The technique is sensitive and many variables will affect the response given. The tooth to be assessed should be sufficiently dry and a contact medium should be used. The position of the electrode on the tooth influences the response, and it should be placed near to the pulp horns of the tooth where the nerve density is greatest. In anterior teeth this means that placing the electrode on the incisal edge gives the least amount of electrical current. A recent study has revealed that the optimum site for tester electrode placement on molars is the tip of the mesiobuccal cusp [2731].
There has been controversy in the past as to the use of electric pulp testers and patients with cardiac pacemakers. An in vivo study simulated EPT use on 27 patients with implanted cardiac pacemakers or cardioverter/defibrillators. The report found that EPTs did not produce any interference effects [32].
It has been well documented in the literature the possibility of false-positive (indicating a nonvital tooth responding positively) and false-negative readings (vital teeth responding negatively) obtained from common pulp vitality diagnostic tests [33] (Table 11.1). The clinician must be aware of these confounding variables, which can influence the result of the tests and take these into account when assessing probable pulp status of any given tooth.

Table 11.1

Causes of false-positive and false-negative responses to pulp testing
False-positive responses
 Anxious patients
 Pulp liquefaction necrosis (multi-rooted teeth)
 Contact with metal restorations
 Contact with gingivae or periodontium
 Vital tissue still present in a partially necrotic canal
 Vital tissue present in a multi-rooted tooth
False-negative responses
 Incomplete root development
 Recently traumatised teeth
 Calcific metamorphosis (sclerosed canals)
 Recent orthodontic treatment
 Patients with psychotic disorders
Traumatic injuries to teeth present problems with respect to vitality. Teeth that temporarily or permanently lose their sensory function will not respond to EPT and are described as ‘concussed’. These teeth, however, may have intact vasculature and it is recommended that for traumatised teeth pulps should be considered vital until proved otherwise. The EPT is often unreliable in testing immature permanent teeth, as full development of the plexus of Raschkow does not occur until 5 years after tooth eruption. The cold thermal test is a more reliable one for these types of teeth [34].
Physiometric testing has been reported in the literature as a means to overcome some of the inherent problems of reliability associated with thermal and electric pulp testing. These tests are aimed at measuring or quantifying whether a healthy blood supply is present as opposed to a neurogenic response. A modified technique involving pulse oximetry as a non-invasive technique used to measure the oxygen saturation levels within the tooth has been demonstrated with some success [35]. Laser Doppler flowmetry has been used to assess the vitality of the tooth based on an intact blood flow. A modified fibre-optic probe is attached to the tooth surface whereby a laser light can be emitted directly to the pulp. The light emitted is absorbed by red blood cells within the intact pulpal circulatory system resulting in a Doppler shift. By virtue of the Doppler principle, light absorbed by stationary objects do not undergo a shift in frequency (i.e. when the tooth is nonvital, the blood flow is disrupted and absent). Any frequency-shifted light can be detected by a photodetector, which emits a signal. This technique has been shown to be much more reliable and sensitive in determining the pulp status of the tooth. Unfortunately the technique is very treatment sensitive, requiring a modified probe and expensive medical grade equipment making it not suitable for day-to-day clinical use at the present time [3640].

11.2 Examination

Clinical examination of the patient is carried out to reproduce the patient’s symptoms (defined as any bodily changes perceptible to the patient) if possible and confirm the presence of any signs (defined as any bodily changes which are perceptible to a trained observer) of disease. The examination process can be categorised into three main elements, namely, the general observation of the patient’s health and appearance, extra-oral examination of the head and neck and examination of the intra-oral tissues. The examination must be a thorough systematic approach ensuring all areas are examined. Few patients have died as a result of pulpitis, but many have died as a result of a late diagnosis of a malignancy. Occasionally malignant lesions can present as endodontic lesions and careful examination with a methodical approach at each step will at least ensure to some degree that we do not fall short of our clinical duty to the patient.
Extra-oral examination
Head, face and neck
The face and neck is visually examined from the front looking for any obvious lumps, skin blemishes, moles, facial asymmetry or signs of facial palsy. When examining the neck, the patient is asked to tilt the head back slightly to allow for any swelling or abnormality to be clearly seen.
Eyes
The eyes are inspected for any signs of limitation of ocular movement or strabismus, which may indicate a fractured zygoma. Enophthalmos, exophthalmos, subconjunctival haemorrhage, colour of the sclera and dry eyes may all indicate presence of underlying pathology.
Lips
Visual examination is carried out inspecting for any drooping of the commissures or inability to purse the lips. Any changes in colour, texture, ulceration, patches, lumps or raised lesions may require further investigations.
Lymph nodes
In normal health lymph nodes are not palpable and any palpable nodes should alert the clinician to some underlying pathology. Lymph nodes in the outer circle group consist of the submental (lies behind the chin, underlying the mylohyoid muscle), submandibular (between the mandible and submandibular gland), buccal (lies on the buccinators muscle anterior to the insertion of the masseter muscle), mastoid (on the mastoid process), parotid (pre-auricular region in front of the tragus of the ear) and occipital (around the occipital artery). Lymph nodes of the cervical group consist of the superficial cervical nodes (distributed around the external and anterior jugular veins), the deep cervical chain (distributed along the internal jugular vein), jugulo-digastric (between the angle of the mandible and the anterior border of the sternocleidomastoid muscle) and jugulo-omohyoid (just behind the internal jugular vein, above the inferior belly of omohyoid).
Lymph node examination is carried out extra-orally with bimanual palpation from behind the patient. The patient is asked to expose the neck by loosening relevant clothing. Asking the patient to tip their head forwards and then trying to roll the node against the inner aspect of the mandible enable examination of the submental node. The submandibular nodes are examined by asking the patient to tip their head to the side being examined.
The site, size, texture (soft, rubber hard), tenderness, number and whether the nodes are fixed or mobile is recorded. Note acute infection will often result in nodes that are large, soft, painful and mobile. Chronic infection may result in large, firm, less tender, mobile nodes on palpation. Metastatic cancer will result in stony hard nodes, which are fixed to underlying tissues and often painless. If a non-dental cause is suspected, then urgent referral to a specialist for further investigations may be warranted.
Salivary glands
The parotid gland is located mainly distal to the ascending ramus of the mandible. The gland is viewed from the front and then palpated for any enlargement or tenderness. The submandibular gland is bimanually palpated using the index finger and middle finger of one hand intra-orally and the same fingers of the other hand extra-orally. The gland is palpated both above and below the mylohyoid, and the ducts are checked for the presence of any calculi.
Articulatory system and muscles of mastication
The temporomandibular joint is examined for range of movement, tenderness on palpation, joint sounds, locking, muscle tenderness, evidence of bruxism, associated headache, neck ache and any occlusal discrepancies (see Chap. 1).
Intra-oral examination
Lining mucosa
The site, shape and size of any lesions detected are noted. The lesion is palpated to determine whether it is soft or hard in texture, whether the edges are well defined or diffuse and whether the lesion is fixed or mobile. The colour of the lesion is noted. Lesions can be described as ulcers, vesicles, erosions, bulla, plaques, papules, macules or pustules.
A draining sinus indicates a blind-ended epithelial lined track. A sinus should be tracked with a probe or gutta-percha cone to reveal its origin.
Tongue
The dorsum of the tongue is inspected both at rest and in the protruded position. The lateral borders of the tongue are examined using gauze to hold the tip and moved to one side.
The floor of mouth and ventral surface of tongue are also carefully inspected. This area known as the ‘gutter’ is a common site for oral cancer to present. Asking the patient to raise the tip of their tongue to the palate should allow for inspection of the floor of the mouth.
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Sep 7, 2015 | Posted by in Endodontics | Comments Off on Examination and Diagnosis
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