ALMOST all the standard dental procedures require numbing the area where the work is being performed. The use of local anaesthetic to achieve this is obvious since the practice of dentistry must never be a painful experience for the patient. The prick of the needle should never be anticipated as being uncomfortable or frightening since this preparatory measure is very innocuous.

I have never known anyone to suffer any adverse effects from local anaesthetic. It is used mainly to numb the area where a tooth is being extracted. It is estimated that over 750,000 dental capsules of anaesthetic are administered yearly in Guyana with relative safety and with possibly few complications resulting. However, like all drugs, the use of local anaesthetics, commonly referred to as “cocaine”, is not without hazard, and we must all be aware of the possibility of untoward reactions.

Patients need to inform their dentist of any history of previous anaesthetic experiences and whether they have shown any unusual reaction to drugs or allergies. The dentist should know any specific condition which may require support or treatment, and any disease for which the patient is or has been under the care of a physician, and the type of treatment, particularly drugs, currently being prescribed.

Most reactions occurring after the injection are potentiated by the anxiety that accompanies the dental appointment, and stress is the major problem to be avoided. Other conditions that may precipitate reaction to local anaesthetic are the following:

1. Low blood sugar levels resulting from fasting before the dental appointment. This is probably the foremost factor in fainting, so the patient must have had a regular meal. People who skip breakfast are prime candidates for fainting.
2. Extremes in temperature. Heat exhaustion will exacerbate reactions.
3. Any debilitating disease. Disease is a prime agent that reduces the ability to respond to stress.
4. This patient is sensitised, much like the allergic type. She has an increased blood level of steroids and needs careful handling.

Studies show that two to three out of every hundred members of the public will fall into a category of problem management cases. Most of those individuals have special requirements, and I will examine some of them.

Cardiovascular (heart and blood vessels) diseases. These patients will probably be on special medications such as Reserpine or Serpasil, digitalis derivatives (Digoxin),
diuretics (Lasix), and tranquillisers (Valium). All these drugs may interact with the anaesthetic agent used.

Respiratory diseases. These may include emphysema and asthma. These conditions limit the oxygenation mechanism. Since fear results in increased respiration, dental chair apprehension may cause a deficit.

Allergic diseases. This patient may have a history of hay fever, asthma, angioedema, contact dermatitis (“mad blood”), etc. There will often be a familial history of sensitivity. Atopic types are very sensitive to offending antigens and may develop severe anaphylaxis and die from the injection of small amounts of the allergen (continued in the anaesthetic).

Blood dyscrasias and haemorrhagic diseases. Many people are taking anticoagulant therapy and do not know. Patients frequently take tablets prescribed by their doctors without knowing the names and purpose of the medicine. When it takes more than ten minutes for a wound to stop bleeding, or if a woman menstruates more than six days, there is a possibility of the person having a coagulation problem.

Finally, individuals receiving steroid therapy do not respond well to stress. Those being treated for hyperthyroidism may have to be sedated. Uncontrolled diabetics should never have dental treatment. Healing and postoperative infections are a problem here.