17: Human Diseases and Health Promotion

CHAPTER 17 Human Diseases and Health Promotion

17.1 Common human diseases

There are several reasons why diseases occur. These can be divided into (Box 17.1.1):

BOX 17.1.1 Causes of Human Diseases

Many diseases result from an interaction of several of these factors (Figure 17.1.1).

The severity of an illness

The severity of an illness can influence the type of operation or other medical care given, since in very ill patients such interference can cause the patient to deteriorate.

A commonly used system to classify the severity of illnesses is the American Society of Anesthesiologists’ (ASA) system, shown in Table 17.1.1.

TABLE 17.1.1 ASA Classification of State of Health

Class I Normal healthy individual
Class II Patient with mild systemic disease (not interfering with daily life)
Class III Severe systemic disease (interferes with daily life)
Class IV Incapacitating systemic disease (constant threat to life)
Class V Moribund (very seriously ill) patient with life expectancy <24 hours


Alcohol is the most commonly misused drug. It affects the functioning of the central nervous system (CNS) as follows:

Interfering with the functioning of the cerebellum (see Chapter 4) to cause unsteadiness of gait (ataxia) and inco-ordination of movements.

Eventually alcoholism interferes with the working of the brain centres (e.g. respiratory) and can cause unconsciousness or even death (Table 17.1.2). The high rate of deaths among people with alcoholism is mainly as a result of road traffic accidents and assaults. Alcoholics can also drown in their own vomit.

Many other diseases can be caused or aggravated by alcohol including:


Allergy is an abnormal response to an allergen (protein). Potential allergens in dentistry are:

Rare allergic reactions in dentistry occur in relation to:

Common allergens are listed in Table 17.1.3.

TABLE 17.1.3 Common Allergens

Allergen Source Examples
Dental materials Amalgam, gold, mercury, resins, plasters (e.g. Elastoplast)
Drugs Aspirin, penicillins
Environment Animal hair, dust mites, pollens
Foods Milk, nuts (especially peanuts), eggs, shellfish
Latex Gloves, dressings, elastic bands, condoms

Allergies are responsible for some types of the following diseases and conditions:

Anti-coagulant-related problems

Anti-coagulants are drugs used to slow blood clotting. This is required to control and prevent clotting in people who have deep vein thromboses (thrombo-embolic disorders) or after heart surgery. The dose of the drug needs to be controlled or the patient will bleed too easily. Warfarin is the most frequently prescribed anti-coagulant. The dose is controlled by doing a blood test called the international normalised ratio (INR). An INR above 1 indicates that clotting will take longer than normal.

Surgery is the main hazard for the patient on warfarin. Thus alternative treatments, e.g. endodontic treatment, are always considered.



Asthma is a common condition in which there is difficulty breathing because of narrowing of the airways. This can happen because of:

During an asthmatic attack a person may have difficulty breathing, cough and wheeziness.

There are two types of asthma (Table 17.1.5): extrinsic and intrinsic. Extrinsic asthma is more common and is caused by exposure to allergens. Intrinsic asthma is much less common and is often not related to exposure to allergens.

TABLE 17.1.5 Types of Asthma

  Extrinsic Intrinsic
Frequency Common Less common
Associations Allergic disease (hay fever, eczema, allergic rhinitis) None
Main precipitating factors Animal hairs Air pollutants
House dust mite Cold air
Pollen and moulds Drugs (NSAIDs)

Bell’s palsy

Bell’s palsy (Figure 17.1.5) is a type of facial paralysis that usually occurs on one side. It occurs mainly due to infection with herpes simplex virus (HSV). Most patients recover totally and spontaneously within a few weeks. Treatment includes:

Cannabis (marijuana) use

Cannabis is usually smoked as a cigarette (joint, spliff or nail) or in a pipe (bong). The main active chemical THC (delta-9-tetrahydrocannabinol), works by binding to the brain. This affects the person’s:

Within a few minutes of inhaling marijuana smoke, the user will often feel their heart beat increase, have a dry mouth, and red eyes. In some people, marijuana can double the normal heart rate and raise the blood pressure. Because of the effects of cannabis on perceptions and reaction times – which last for up to 24 hours – users can be involved in risky sexual behaviour, violence or in road traffic accidents. Some users may also have acute anxiety and paranoid thoughts; rarely, a user can have severe psychotic symptoms and need emergency medical treatment.

The long-term effects of using cannabis are not yet clear, but it may affect the lungs, heart, and immune system and mental health. Marijuana smokers may develop many of the breathing problems that tobacco smokers have, hypertension and increased heart rate and lowered oxygen-carrying capacity of blood. Because of this the risk of a heart attack is increased four-fold in the first hour after smoking marijuana. Long-term use of marijuana can trigger or worsen schizophrenia (see p. 389).

Coronary (ischaemic) heart disease

Coronary artery disease (CAD) is the leading cause of death in the UK.

It is caused by atherosclerosis of the coronary arteries.

Creutzfeldt–jakob disease

Creutzfeldt–Jakob disease (CJD) is a rare, progressive brain disease. It is a type of transmissible spongiform encephalopathy (TSE). Some TSEs are transmissible from animal to man; bovine spongiform encephalopathy (BSE; also known as ‘mad cow disease’) in cattle appears to be responsible for variant CJD (vCJD) in humans.

TSEs are caused by prions – which are abnormal cellular proteins. Prions are very resistant to normal disinfectants and sterilisation. TSEs have prolonged incubation periods of months to years. Persons with vCJD develop psychiatric symptoms (severe depression and behavioural disorders), followed by dementia, and finally death.

There is no effective treatment yet for vCJD and there have been few patients (172 dead and alive cases reported in UK by 2010).

Find out More

To read more about prion disease and health and safety, see HTM 01-05 (Section 1; see Chapter 1) and Transmissible Spongiform Encephalopathy Agents: safe working and the prevention of infection produced by the Advisory Committee on Dangerous Pathogens (www.dh.gov.uk/ab/ACDP/TSEguidance/DH_098253).


Diabetes mellitus is a common condition caused by a decreased production of the hormone insulin from the pancreas or because of insulin resistance. Insulin normally controls blood sugar by facilitating its entry into cells for use as energy. In diabetes, glucose (sugar) accumulates in the blood (hyperglycaemia) and the urine (glucosuria) leading to the production of large volumes of urine (polyuria) and to thirst (polydipsia). Fat and protein stores are metabolised to glucose with weight loss, muscle wasting and the production of ketone bodies, which may be detected on the breath (in particular acetone). Diabetes also causes damage to kidneys, nerves and eyes. Complications of diabetes can affect almost every part of the body and include:

Drug abuse (substance dependence)

Drug abuse is self-administration of certain drugs without any medical indication for them, despite adverse medical and social consequences (Table 17.1.6). The use of some drugs is illegal and people found in possession of these or, particularly, if there is any intention of dealing (supplying), can be charged.

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Jan 8, 2015 | Posted by in Dental Nursing and Assisting | Comments Off on 17: Human Diseases and Health Promotion
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