body excretion).
7 Digestion – salivary amylase begins the breakdown of cooked starch (a relatively minor role in the whole digestive process, but important in relation to sucrose intake and oral disease).
8 Buffering action – helps maintain the neutral pH of the mouth. The bicarbonate ion is vital to the health of the mouth as it is concerned with the buffering action of saliva. The average resting pH of the mouth (when no food has just been consumed) is 6.7. This is neutral, neither acid nor alkaline. (pH is a symbol used to indicate measurement of acidity or alkalinity of substances or liquids, and stands for the German term potenz Hydrogen.)
Facts about saliva
Here are some general points of interest about saliva:
More is secreted when required (reflex action).
Composition varies according to what is being eaten (e.g. more mucous with meat).
Average amount produced daily by adults is 0.5–1 L. Certain medical conditions and disabilities cause the overproduction of saliva, resulting in dribbling (e.g. patients with Down’s syndrome and Parkinson’s disease, and fungal infections, such as angular cheilitis – see Chapter 8).
Flow almost ceases during sleep.
Saliva is sterile until it enters the mouth.
Saliva tests can be used to solve crimes, since saliva contains deoxyribonucleic acid (DNA), which can be used to help identify individuals. Dental companies sell saliva testing kits, which can be used by OHEs to demonstrate saliva pH to patients.
Other additives within the mouth
Although saliva entering the mouth is sterile, it soon loses this property as it collects organic materials that are already present, including:
Microorganisms: bacteria (mainly streptococci), viruses (e.g. herpes simplex), and fungi (e.g. Candida albicans).
Leucocytes (white blood cells), which fight infection. Not present in edentulous (toothless) babies or in saliva collected from the duct, so presumed to come from gingival crevice after teeth erupt.
Dietary substances (meal remains).
REFERENCES
1 1. Thibodeau, G.A. & Patton, K.T. (2002) Anatomy and Physiology. 5th edn. Mosby, Missouri.
2 2. Lang, N.P., Mombelli, A. & Attström, R. (2003) Dental plaque and calculus. In: Clinical Periodontology and Implant Dentistry (eds. J. Lindhe, T. Karring & N.P. Lang N.P.), 4th edn, pp. 81–105. Blackwell Munksgaard, Oxford.
3 3. Phillips, S. Oral embryology, histology and anatomy. In: Clinical Textbook of Dental Hygiene and Therapy (ed. S.L Noble), 2nd edn. pp. 3–5. Wiley‐Blackwell, Oxford.
4 4. Cleft Lip & Palate Association. (2019). What is Cleft Lip & Palate? Available at: https://www.clapa.com/what‐is‐cleft‐lip‐palate/ [accessed 13 March 2019].
5 5. Watkins, S.E. , Meyer, R.E., Strauss, R.P., Aylsworth, A.S. (2014) Classification, epidemiology, and genetics of orofacial clefts. Clinics in Plastic Surgery, 41(2), 149–163.
6 6. Lindhe, J., Karring, T. & Araújo, M. Anatomy of the periodontium. In: Clinical Periodontology and Implant Dentistry (eds. J.T. Lindhe, T. Karring & N.P. Lang). 4th edn, pp. 3–49. Blackwell Munksgaard, Oxford.
7 7. Collins, W.J., Walsh, T. & Figures, K. (1999) A Handbook for Dental Hygienists. 4th edn. Butterworth Heinemann, Oxford.
8 8. Fejerskov, O. & Kidd, E. (2003) Dental Caries: The Disease and its Clinical Management. Blackwell Munksgaard, Oxford.
Section 2 Diseases and Conditions of the Oral Cavity
INTRODUCTION
This section explores the reasons for, and the effects of, the breakdown of oral health, and details advice that should be given to patients to control disease and restore a good standard of oral health.
What causes oral disease?
There is, of course, no brief answer. The determinants are many and complex, and more often than not a combination of factors is involved in the development of a particular condition or disease: genetic, cultural, environmental, socioeconomic, diet, and lifestyle.
Education is vital in controlling dental disease, and that is where the oral health educator (OHE) can help.
Chapter 2 Plaque, calculus, and staining
Learning outcomes
By the end of this chapter you should be able to:
1 Explain the causes and development of plaque, and advise on plaque control.
2 Distinguish between aerobic and anaerobic bacteria and their effects on oral tissues.
3 List secondary factors in the development of plaque.
4 Explain the types, causes and effects of calculus, and its treatment.
5 Differentiate between intrinsic and extrinsic tooth staining, their causes and treatment (including whitening).
INTRODUCTION
Oral health educators (OHEs) need an understanding of plaque and calculus, and their roles in the development of common dental diseases, such as caries, gingivitis, and periodontitis. The OHE should also be able to distinguish between intrinsic and extrinsic staining, and answer patient questions on teeth whitening.
PLAQUE
Most people have heard of plaque, but few would be able to explain its composition.
Plaque is a soft, non‐calcified adherent film that collects on the surfaces of teeth, and comprises approximately:
70% microorganisms (bacteria, fungi, viruses).
30% matrix (the framework that holds it together).
Plaque is found in all mouths and makes up part of the natural flora of the body. The most common sites where plaque is found are occlusal pits and fissures, cervical margins of the teeth and in periodontal pockets. Patients can be made aware of plaque in their mouths by using a disclosing solution or tablets (Figure 2.1 a,b). (See Chapter 19.)
Plaque is a major causative factor in gingival and periodontal disease and a contributory factor in dental caries. Even in people with good toothbrushing skills, one would need to brush and floss approximately every 3 minutes in order to prevent plaque from forming.
Figure 2.1 (a,b) Plaque undisclosed (a) disclosed (b) in the same mouth.
Source: Alison Chapman.