CHAPTER 17 Human Diseases and Health Promotion
BOX 17.1.1 Causes of Human Diseases
|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|
People, particularly those who are ill, often have concerns about privacy, and about the social implications of their condition. You must therefore strictly adhere to data protection and patient confidentiality principles. Reassure the patient that none of their details will be discussed, even with partners, unless permission is gained from them.
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.
|Dental materials||Amalgam, gold, mercury, resins, plasters (e.g. Elastoplast)|
|Environment||Animal hair, dust mites, pollens|
|Foods||Milk, nuts (especially peanuts), eggs, shellfish|
|Latex||Gloves, dressings, elastic bands, condoms|
A person is said to have anaemia when their haemoglobin (Hb) level is below the normal for their age, gender and ethnic background. Haemoglobin is required to carry oxygen to the brain and tissues (see Chapter 4). Anaemia has many causes as shown in Table 17.1.4.
|Nature of Anaemia||Cause|
|Increased loss of red blood cells (RBCs)||Menstrual blood loss|
|Gastro-intestinal blood loss|
|Haemolysis (breakdown of the RBCs), such as in malaria or sickle disease|
|Reduced RBC production||Dietary deficiency|
|Bone marrow disease, such as in leukaemia|
|Increased tissue requirements||Puberty|
|Decreased tissue requirements||Hypothyroidism|
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.
Thrombo-embolic disorder: a disorder related to the formation of blood clots (thrombi) in one part of the body, of which either small portions or the whole clot can then become loose (emboli) and travel to other parts of the body in the blood stream, causing e.g. pulmonary thrombosis.
LA regional block injections, or those given in the floor of the mouth, may be a hazard since bleeding into the tissues of the neck can block the airway and suffocate the patient. If surgery is to be more than simple or minor, or the INR is above 3.5, the patient is usually treated in hospital or another specialist centre.
Aspirin and non-steroidal anti-inflammatory agents (NSAIDs) inhibit platelet aggregation and cause bleeding. Thus they should be avoided in these patients. Paracetamol is the analgesic of choice for these patients.
Anxiety is an unpleasant emotional state characterised by fear and a variety of physical symptoms. Stress raises blood levels of the adrenal hormones: cortisol, adrenaline (epinephrine) and noradrenaline (norepinephrine). These ‘stress hormones’ influence many physiological functions, causing:
RA affects women most frequently. It mainly affects the wrists, hands and feet (Figure 17.1.3). Patients may also have a dry mouth (Sjögren syndrome, see Chapter 5 and Figure 17.1.4).
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.
|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)|
Atheroma is the accumulation of fats (cholesterol and lipids) in the artery walls. The accumulation occurs in the form of plaques. These can cause narrowing of the arteries and reduce the blood supply to the tissues supplied by that artery.
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:
Blood-borne virus infections (e. g. hepatitis B virus (HBV), hepatitis C virus (HCV), or HIV) are transmitted mainly by sharps injuries, but also via unscreened blood and sexual contact. Occasionally they are transmitted through the mucosa of the eye or mouth (see p. 379).
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.
Psychotic symptoms: psychosis is a serious mental disorder in which a person loses touch with reality or their perception of reality is highly distorted. The classic symptoms are: hallucinations and delusions and other confused thoughts. There may also be a lack of self-awareness.
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).
Electrosurgery can cause heart pacemakers and implantable cardiac defibrillators to malfunction. Some older electrically operated dental equipment may also be a risk but most modern dental equipment is safe in this respect.
In the past, patients thought to be at risk from infective endocarditis were routinely given anti-microbial prophylaxis (‘cover’) before dental surgery and some other procedures. But that is no longer the case (see p. 383). Some ‘cardiac’ drugs can cause gingival swelling.
Cerebral palsy (CP) is the most common congenital physical disability. In cerebral palsy, muscle control is abnormal because of damage to a child’s brain early in the course of development. The brain damage is caused mainly by lack of oxygen (hypoxia), trauma or infection. Physiotherapy is an important part of management.
BOX 17.1.2 Conditions Related to CAD
A person with myocardial infarction requires immediate aspirin and hospital admission (see Chapter 2). Up to 50% of patients die within the first hour; but early treatment halves the death rate.
Cytotoxic chemotherapy is used to treat many cancers and other malignant conditions such as leukaemia. The drugs often cause hair loss (alopecia), nausea and vomiting, and pins and needles (paraesthesia) but one of the biggest problems for the patient is a sore mouth (mucositis). Analgesics are needed, as well as a soft diet. Sucking ice cubes may help ease the pain, and many other concoctions are available to help the patient. Oral hygiene must be maintained.
The adrenal hormone cortisol is released in the response to stresses such as trauma, infection, general anaesthesia or surgery. Secretion of cortisol is regulated via a biological feedback system that includes another hormone called adrenocorticotropic hormone (ACTH). In patients given systemic corticosteroid drugs (steroids), this feedback response may not occur. As a result, the adrenal gland is unable to produce the necessary steroid response to stress. The patient may then have a fall in blood pressure and collapse.
Biological feedback: the system by which the body feeds back information to the various regulating organs, which then respond by either increasing or decreasing the formation of regulators, for example, hormones.
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.
A unique feature of prions is their remarkable capacity to bind to steel. They resist inactivation by conventional methods: heat, most disinfectants, and by ionising, ultraviolet and microwave radiations. This presents significant infection control problems when patients with CJD undergo medical or dental interventions. Disposable equipment is the best answer.
Prions are also a rare hazard from exposure-prone (invasive) procedures. Dental interest in prion disease (CJD) and the related conditions centres on the risk of their transmission from patient to patient in the course of dental treatment through contaminated instruments. There is no known case of this happening and appropriate dental infection control precautions will reduce the scope of the theoretical risk. It is not yet known whether CJD can be transmitted via blood or other tissues encountered during dental surgery.
CJD and related conditions raise new infection control questions because prions are much more difficult to destroy than conventional micro-organisms. So single-use instruments are recommended. All other instruments should be decontaminated.
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).
Dementia is a progressive loss of intellect, memory and social abilities without clouding of consciousness. The prevalence increases with age; it is rare in people younger than 60 years. Alzheimer disease is the most common form of dementia – a neurodegenerative disease in which neurones in the brain die and plaques form.
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:
Peripheral vascular disease: when the blood vessels that carry blood to the extremities, such as the arms and legs, become narrowed so that blood flow is compromised. This affects the health of the local tissues.
Hypoglycaemia is avoidable by appropriate planning, such as operating mid-morning to allow the patient to have their breakfast. Furthermore, particularly before surgical procedures, the patient’s blood glucose level may be tested. More protracted procedures such as multiple extractions should only be carried out in hospital.
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.