CHAPTER 12 Dental Drugs, Materials, Instruments and Equipment
The hazards associated with materials commonly used in dentistry are also discussed in Subchapter 1.1. Oral health products are discussed in Chapter 8.
Toothpastes, fluorides, anti-plaque and other mouthwashes, etc. are discussed in Chapter 8. Whitening agents, antiseptics and disinfectants (decontaminating agents), the other products used in oral healthcare, are discussed here. The most common drugs used in dentistry are anaesthetics, sedatives, analgesics and anti-microbial drugs.
Tooth-whitening products include strips, gels and varnishes containing hydrogen peroxide (H2O2) and are used for bleaching. H2O2 has been used for more than 70 years for oxygenating mouthwashes and to bleach teeth. The most common source of H2O2 used for whitening is carbamide peroxide which typically contains between 10% and 30% peroxide (15% is recommended), roughly equivalent to 3–10% hydrogen peroxide.
Internal bleaching is performed on teeth that are discoloured due to internal staining. This usually happens in teeth that have become non-vital from trauma or caries (see Chapter 5). Internal bleaching involves drilling a hole to the pulp chamber, cleaning and filling the root canal, and sealing a hydrogen peroxide gel into the pulp chamber for some days, and replacing this as needed (so called ‘walking-bleach’ technique).
Local anaesthetics (LAs) most commonly used for dental procedures belong to a group of drugs called amides (for example lidocaine, prilocaine, articaine and mepivacaine). Most LA dental cartridges also contain a vasoconstrictor, either adrenaline or felypressin (see Chapter 13).
Most benzodiazepines take effect within one hour after they are taken. There is often little to choose between them in terms of anxiolytic effect and, in prolonged use, all (especially lorazepam) may produce dependence. All impair memory and judgement at least for a while. Alcohol and other drugs that depress central nervous system (CNS) function (e.g. antihistamines, anti-convulsants, tranquillizers) must be avoided as fatalities have occurred (Chapter 13).
For inhalational sedation, sometimes termed relative analgesia or RA, two medical gases, nitrous oxide (N2O) and oxygen, are used. These gases are stored in specifically coloured cylinders (Tables 12.1 and 12.2). At least 20% and more usually 30% oxygen is given.
|Size of Cylinder||Capacity (litres)|
Gases used in sedation/anaesthesia are usually supplied under high pressure either in cylinders or as a piped gas supply. The cylinders are made from molybdenum steel, in which gases and vapours are stored under pressure. The shape and colour of the plastic disc around the neck indicates when the cylinder was last examined. The most commonly used types/sizes are:
Pain is probably the most important symptom suggestive of disease. However, the absence of pain does not mean a patient may not have disease. Different people respond differently to pain. The threshold for tolerance is lowered by tiredness, psychological factors, etc.
Pain occurs when there is tissue damage that leads to the release of chemicals such as prostaglandins. These chemicals are produced via an enzymatic pathway involving a chemical called cyclo-oxygenase (COX). Certain drugs such as non-steroidal anti-inflammatory drugs (NSAIDs, for example aspirin) block COX and thus prostaglandin synthesis.
Anti-fungals, for example miconazole, are used to treat oral or oropharyngeal fungal infections. However, before starting with anti-fungals the clinician will check why the patient is having the infection (see below). It is important to treat this underlying cause along with anti-fungal treatment.
Erythromycin, penicillins (some), rifampicin and tetracyclines (except doxycycline) should be taken at least 30 minutes before food. This is because their absorption is otherwise delayed. Metronidazole may cause headaches if taken with alcohol.
Almost any drug may produce unwanted or unexpected adverse reactions, some of which are life-threatening – such as anaphylaxis (Chapter 2). These reactions are often predictable. However, some are rarely predictable unless the person has previously reacted adversely.
Patients should be warned if serious adverse reactions are predictable and likely to occur (e.g. weight gain, hypertension and diabetes with systemic corticosteroids). They should also be provided with the appropriate warning card to carry.
Schedule: under the Controlled Substances Act (CSA), all controlled drugs are classified into five groups called schedules. Schedule I drugs are recreational drugs not meant for medical use (e.g. heroin); schedule II drugs also have a potential for misuse but are used as medicines also (e.g. cocaine and morphine); schedule III, IV and V are drugs with decreasing potential for misuse but which are useful medicines.
Visit the website of the Medicines and Healthcare products Regulatory Agency (MHRA; www.mhra.gov.uk), the medicines safety watchdog, to read more about Yellow cards.
The webpage ‘Controlled drugs guidance for GP practices’ (www.gp-training.net/protocol/therapeutics/cd.htm) gives useful information about what should be included in a controlled drugs register and how they should be stored.
Cultural issues may affect the use of and prescription of certain drugs and dental healthcare products. However, remember that some religions, though at first sight apparently objecting to some constituents of drugs, do not prohibit their use if the product is designed to enhance health. Alcohol and some animal products are the sources of most concern. Some cultures are characterised by the use of certain drugs, for example Rastafarians often use cannabis.