1. Principles of investigation and diagnosis

CHAPTER 1. Principles of investigation and diagnosis
Box 1.1

Principles of investigation and diagnosis
• A detailed history
• Clinical examination

• Special investigations (as appropriate)

Testing vitality of teeth
Radiography or other imaging techniques
Biopsy for histopathology (including immunofluorescence, immunocytochemistry, electron microscopy, molecular biological tests)
Specimen for microbial culture
Haematological or biochemical tests


History-taking needs to be tailored to suit the individual patient, but it is sometimes difficult to get a clear idea of the complaint. Many patients are nervous, some are inarticulate, others are confused.
Rapport is critical for eliciting useful information. Initial questions should allow patients to speak at some length and to gain confidence. It is usually best to start with an ‘open’ question (Tables 1.1 and 1.2). Medical jargon should be avoided and even regular hospital attenders who appear to understand medical terminology may use it wrongly and misunderstand. Leading questions, which suggest a particular answer, should be avoided because patients may feel compelled to agree with the clinician.
Table 1.1 Types of question
Type of question Example
Open Tell me about the pain?
Closed What does the pain feel like?
Leading Does the pain feel like an electric shock?
Table 1.2 Advantages and disadvantages of types of question
Types of question Advantages Disadvantages
Allows patients to use their own words and summarise their view of the problem
Allows patients partly to direct the history-taking, gives them confidence and quickly generates rapport
Clinicians must listen carefully and avoid interruptions to extract the relevant information
Patients tend to decide what information is relevant
Elicits specific information quickly
Useful to fill gaps in the information given in response to open questions
Prevents vague patients from rambling away from the complaint
Patients may infer that the clinician is not really interested in their problem if only closed questions are asked
Important information may be lost if not specifically requested
Restricts the patient’s opportunities to talk
It is sometimes difficult to avoid interrupting patients when trying to structure the history for the records. Structure can only be given after the patient has had time to give the information. Constant note-taking while patients are speaking is undesirable.
Questioning technique is most critical when eliciting any relevant social or psychological history or dealing with embarrassing medical conditions. It may be appropriate to delay asking such questions until after rapport has been gained. Some patients do not consider medical questions to be the concern of the dentist and it is important to give reasons for such questions when necessary (Box 1.2).
Box 1.2

Essential principles of history-taking
• Introduce yourself and greet the patient by name
• Put patients at their ease
• Start with an open question
• Mix open and closed questions
• Avoid leading questions
• Avoid jargon
• Explain the need for specific questions
• Assess the patient’s mental state
• Assess the patient’s expectations from treatment

Demographic details

The age, gender, ethnic group and occupation of the patient should be noted. Such information is occasionally critical. For instance, an elderly woman with arthritis and a dry mouth is likely to have Sjögren’s syndrome (Ch. 18), but a young man with a parotid swelling due to similar lymphoproliferation is far more likely to have HIV infection (Ch. 24). Some diseases such as oral submucous fibrosis (Ch. 16) have a restricted ethnic distribution.

History of the present complaint

Frequently, a complaint, such as toothache, suggests the diagnosis. In many cases, a detailed history (Box 1.3) is required and sometimes, as in aphthous ulceration, a provisional diagnosis can be made on the history without examination or investigation.
Box 1.3

History of the present complaint
• Record the description of the complaint in the patient’s own words
• Elicit the exact meaning of those words
• Record the duration and the time course of any changes in symptoms or signs
• Include any relevant facts in the patient’s medical history
• Note any temporal relationship between them and the present complaint
• Consider any previous treatments and their effectiveness
If earlier treatment has been ineffective, the diagnosis should be reconsidered. Many patients’ lives have been shortened by having malignant tumours treated with repeated courses of antibiotics.
Pain is completely subjective and, when physical signs are absent, special care must be taken to detail all its features (Table 1.3). Especially important are features suggesting a dental cause. A fractured tooth or cusp, dentinal hypersensitivity or pain on occlusion are easily misdiagnosed.
Table 1.3 Taking a pain history
Characteristic Informative features
Type Ache, tenderness, dull pain, throbbing, stabbing, electric shock. These terms are of limited use and the constancy of pain is more useful
Mild – managed with mild analgesics (e.g. aspirin/paracetamol)
Moderate – unresponsive to mild analgesics
Severe – disturbs sleep
Duration Time since onset. Duration of pain or attacks
Nature Continuous, periodic or paroxysmal
If not continuous, is pain present between attacks?
Initiating factors Any potential initiating factors
Association with dental treatment or lack of it is especially important in eliminating dental causes
Exacerbating and relieving factors Record all and note especially hot and cold sensitivity or pain on eating which suggest a dental cause
Localisation The patient should map out the distribution of pain if possible. Is it well or poorly defined? Does it affect an area supplied by a particular nerve or artery?
Referred pain Try to determine whether the pain could be referred
Factors triggering different causes of pain are discussed in detail in Chapter 34.

The medical history

A medical history is important as it aids the diagnosis of oral manifestations of systemic disease. It also ensures that medical conditions and medication which affect dental or surgical treatment are identified.
To ensure that nothing significant is forgotten, a printed questionnaire for patients to complete is valuable and saves time. It also helps to avoid medicolegal problems by providing a written record that the patient’s medical background has been considered. However, a questionnaire does not constitute a medical history and the information must be checked verbally, verified and augmented as necessary. It is important to assess whether the patient’s reading ability and understanding are sufficient to provide valid answers to the questionnaire.
A sample medical history questionnaire is shown in Box 1.4.
Box 1.4

An example of a medical history questionnaire
Other names
Date of birth Telephone number
The following questions are asked in the interests of your safety and any particular precautions that may need to be taken as a result of thorough knowledge of any previous illnesses or medications. Please, therefore, answer these questions as accurately as you can.
If you are in any doubt about how to answer them, please do not hesitate to ask.
1. Are you undergoing any medical treatment at present?
Yes No
2. Do you have, or have you had any of the following:
a. Heart disease?
Yes No
b. Rheumatic fever?
Yes No
c. Hepatitis?
Yes No
d. Jaundice?
Yes No
e. Epilepsy
Yes No
f. Diabetes?
Yes No
g. Raised blood pressure?
Yes No
h. Anaemia?
Yes No
i. Asthma, hay fever or other allergies?
Yes No
j. Familial or acquired bleeding tendencies?
Yes No
k. Any other serious illnesses?
Yes No
3. Have you suffered allergy or other reactions (rash, itchiness etc) to:
a. Penicillin?
Yes No
b. Other medicines or tablets?
Yes No
c. Substances or chemicals?
Yes No
4. Have you ever had any adverse effects from local anaesthetics?
Yes No
5. Have you ever experienced unusually prolonged bleeding after injury or tooth extraction?
Yes No
6. Have you ever been given penicillin?
Yes No
7. Are you taking any medicines, tablets, injections (etc.) at present?
Yes No
If YES can you please indicate the nature of this medication?
8. Have you been treated with any of the following in the past 5 years:
a. Cortisone (hydrocortisone, prednisone etc)?
Yes No
b. Blood-thinning medication?
Yes No
c. Antidepressants?
Yes No
9. Have you ever received radiotherapy?
Yes No
10. Do you smoke?
Yes No
If YES how much on average per day?
11. For female patients – are you pregnant?
Yes No
Signature Date
Address (if not the patient)
If the history suggests, or examination reveals, any condition beyond the scope of the dentist’s experience or clinical knowledge, referral for specialist medical examination may be necessary.
Medical warning cards may indicate that the patient is, for example, a haemophiliac, on long-term corticosteroid therapy or is allergic to penicillin. It is also worthwhile to leave a final section open for patients to supply any other information that they think might be relevant.
A detailed drug history is essential. Drugs can have oral effects or complicate dental management in important ways (Chs 13& 35).
In some ethnic groups, enquiry should be made about habits such as betel quid (pan) or smokeless tobacco use (Ch. 16).

The dental history

A dental history and examination are obviously essential for the diagnosis of dental pain or to exclude teeth as cause of symptoms in the head and neck region.
Symptoms of toothache are very variable and may masquerade as a variety of conditions from trivial to sinister. The relationship between symptoms and any dental treatment, or lack of it, should be noted.

The family and social history

Whenever a symptom or sign suggests an inherited disorder, such as haemophilia, the family history should be elicited. Ideally, this is recorded as a pedigree diagram noting the proband (presenting case) and all family members for at least three generations. Even when no familial disease is suspected, questions about other family members often usefully lead naturally into questions about home circumstances, relatives and social history which can be revealing if, for example, psychosomatic factors are suspected.


It is imperative to obtain patients’ consent for any procedure. At the very least, the procedure to be used should be explained to the patient and verbal consent obtained. If no more than this is done, the patients’ consent should be noted in their records. However, it is better to obtain written consent.
Patients frequently ask for particular types of treatment, such as fillings or extractions. This implies consent and usually no written agreement is expected. However, with the growing risk of litigation, many dental hospitals now require clinicians to give precise descriptions of treatment plans, however routine, and to obtain written consent. Written treatment plans are also required in dental practice.
Patients have a legal right to refuse treatment. Any such refusals may sometimes be due to failure of the clinician to explain the need for a particular procedure, or failure to soothe the patient’s fears about possible complications. Some of these fears may be irrational, such as the idea of an inherited allergy to local anaesthetics. In such cases, even prolonged explanations and persuasion may be unsuccessful.
When a biopsy is necessary, its purpose should be explained and that the biopsied area may be sore after the local anaesthetic has worn off. Also, it seems likely that when the patient’s tissue is to be retained, even in a block for histological examination, it should be explained that this has to be done in case future reference to it is needed and consent obtained accordingly.
In the case of more major surgery, a consent form should state the nature of the operation and also the likelihood of any significant complications or risks. In the case of an ameloblastoma, for example, it would be necessary to point out that a further operation may be unavoidable and that the alternative might be a relatively massive excision. Also, in such circumstances or when sedation or a general anaesthetic is indicated, patients should be encouraged to ask whatever questions or express any concerns about the procedure and to have it explained fully.
Even greater difficulties may arise in the matter of consent for parotid gland surgery. Explanation of the possibility of permanently disfiguring facial palsy has to be balanced against the need for complete eradication of a tumour. Also, in the case of older patients, it may seem probable that a benign tumour may not cause significant trouble within the patient’s lifetime and that the operative risks are not justified. On the other hand, such a patient may find the idea of living with a tumour emotionally unacceptable so that surgery with its possible complications has to be accepted.
For consent to be legally valid, patients should be given sufficient information, in understandable terms, about the proposed treatment for them to make their own decisions. It is not enough to get a patient, due to have major oral surgery, to sign a blanket consent form without any explanations. Though this has happened many times, the patient may later claim for assault, particularly if there have been unexpected complications.
When a drug has to be prescribed, the difficulties can sometimes be considerable. First, the level of risk of an adverse reaction from a drug is frequently unknown. Severe reactions to penicillin are rare, but it is difficult to explain to a patient that anaphylactic reactions in persons not known to be allergic to penicillin are exceedingly rare but, nevertheless, potentially fatal.
Misunderstandings are common. Many patients think that the word ‘drug’ means a drug of addiction so that the words ‘a medicine’ are preferable.
It is also essential to point out any precautions necessary when taking a particular drug. To take a common example, patients are frequently concerned about the risks of taking aspirin. But in view of the fact that it is estimated that 3000 tons of it are consumed every year, the chances of a reaction are almost infinitessimally small. Most people who complain that aspirin disagrees with them or that they are ‘allergic’ to it, have merely taken the tablets on an empty stomach or without a drink of milk. Obvious though they may seem, such precautions must be emphasised whenever aspirin or a non-steroidal anti-inflammatory drug is prescribed.
Even when the statistical risk of an adverse reaction to a drug is known, the level of risk may be difficult to explain. It may be known that the risk is 0.0001%, but the patient is an individual not a statistic and this does not mean that he or she will be the ten-thousandth patient and will necessarily be affected.
Risks from drugs are also in many ways unpredictable. For example, ataxia caused by carbamazepine is a recognised risk. Thus, one patient became unsteady on her feet as soon as she started taking it. By contrast, another patient who had been taking carbamazepine intermittently for many years without any adverse effects, suddenly lost his balance completely and repeatedly collapsed on the floor without any warning.
Another problem is that many patients are unclear about the difference between risk and harm and think that these are the same thing. It may be necessary to say therefore, ‘The chances of anything going wrong are probably less than one in ten thousand’. Or perhaps, ‘The risk is probably less than when you cross the road’.
However carefully the risks from a drug are explained, it is absolutely essential that patients are warned to come back as soon as they think that there has been an adverse reaction. 1
A Consent Form should therefore be used and should state:

1. The type of operation or investigation.
2. Possible risks and complications
3. A signed and dated statement by the clinician that he or she has explained these matters and any options that may be available in terms understandable to the patient, parent or guardian.
4. A section for the patient, parent or guardian to confirm:

a. that the information was understandable
b. that the person signing the form has a legal right to do so, i.e. is the patient, parent or guardian
c. that the procedure has been explained and agreed
d. that there are certain additional procedures that would be completely unacceptable and should not be carried out.
The form should be signed and dated by the clinician and patient, parent or guardian.
National standard consent forms are produced for use in the National Health Service and most users will have specific guidance as to how these are to be used. Many organisations require use of these forms and audit compliance.



First, look at the patient, before looking into the patient’s mouth. Anaemia, thyroid disease, long-term corticosteroid treatment, parotid swellings, or significantly enlarged cervical nodes are a few conditions that can affect the facial appearance.
The parotid glands, temporomandibular joints (for clicks, crepitus or deviation), cervical and submandibular lymph nodes and thyroid gland should be palpated. Lymphadenopathy (Ch. 26) is a common manifestation of infection, but may also signify malignancy – the cervical lymph nodes are often the first affected by lymphomas. Note the character (site, shape, size, surface texture and consistency) of any enlargement. Press on the maxilla and frontal bone over the sinuses to elicit tenderness if sinusitis is suspected.

Oral examination

Examination of the oral cavity can only be performed adequately with good light, mirrors and compressed air or other means of drying the teeth. If viscid saliva prevents visualisation of the tissues and teeth, a rinse with sodium bicarbonate mouthwash will help.

Soft tissues

The soft tissues of the mouth should usually be inspected first. Examination should be systematic to include all areas of the mouth. Care should be taken that mirrors or retractors do not obscure lesions. To ensure complete examination of the lateral tongue and posterior floor of mouth, the tongue must be held in gauze and gently extended from side to side.
Abnormal-looking areas of mucosa should be palpated for scarring or induration indicating previous ulceration, inflammation or malignancy. Examination should include deeper tissues accessible to palpation, including the submandibular glands.
If lesions extend close to the gingiva, the gingival crevice or pockets should be probed for any communication. Mucosal nodules, especially those on the gingiva or alveolar mucosa, which suggest sinus openings, should be probed to identify any sinus or fistula. Check the openings of the salivary ducts while expressing saliva by gentle pressure. Check that saliva flows freely and equally from all glands and is clear in colour. Do not mistake anatomical variations (Table 1.4) for disease.
Table 1.4 Some anatomical variants and normal structures often misdiagnosed as lesions
Structure Description
Fordyce’s spots Sebaceous glands lying superficially in the mucosa are visible as white or cream coloured spots up to 0.5 mm across. Usually labial mucosa and buccal mucosa. Occasionally prominent and very numerous (Fig. 15.4)
Lingual tonsils Enlarge with viral infection and occasionally noted by patients. Sometimes large or ectopic and then mistaken for disease (Figs 1.1 and 1.2)
Circumvallate papillae Readily identifiable but sometimes prominent and misinterpreted by/>

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Jan 9, 2015 | Posted by in Oral and Maxillofacial Pathology | Comments Off on 1. Principles of investigation and diagnosis
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