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order to promote health and prevent or treat disease. It involves assessment, correct care and patient education to promote independence (Hahn and Jones 2000). Good oral hygiene is essential as poor oral health can affect a patient’s ability to eat or taste food, affect verbal and non-verbal communication, limit self-confidence and desire to interact with others and cause pain and infection, in some cases leading to life-threatening illness (Malkin 2009).

Anatomy and physiology

Structure of the oral cavity

The mouth consists of the vestibule and the oral cavity (Figure 9.7). The vestibule is the space between the lips and cheeks on the outside and the teeth and gingivae (gums) on the inside. The palate forms the roof of the oral cavity with the base of the tongue forming the floor of the mouth. It is bordered by the alveolar arches, teeth and gums at either side (Cooley 2002). The lips and cheeks are formed of skeletal muscle; the inner part of the cheeks is known as the buccal mucosa and consists of columnar epithelium. The lips are involved in speech and facial expression and keep food within the oral cavity. The cheeks control the location of food as the teeth break it down.

Figure 9.7 Structures of the mouth (oral cavity).

Reproduced from Tortora and Derrickson (2009).

Teeth

Teeth are formed of the crown (the visible part) and the root. The crown is covered in enamel, a hard, dense material which cannot repair itself once damaged. Below the enamel cap, the tooth is formed of a bonelike material called dentine. This extends into the root and surrounds the pulp cavity, which contains nerve fibres, blood vessels and connective tissue. When the pulp cavity extends into the root, it is known as the root canal. Teeth are embedded in alveoli (sockets) in the maxilla and mandible and are held in place by periodontal ligaments and a substance known as cementum. Teeth are important in breaking down and grinding food and are also involved in producing sounds in speech (Marieb 2001).

Tongue

The tongue is a muscular structure extending from its tip (apex) to the posterior attachment in the oropharynx. It houses taste buds and is involved in taste, forming food into a bolus and pushing it to the back of the mouth for swallowing. It is also involved in the articulation of sounds in speech.

Palate

The palate consists of the hard palate anteriorly and the soft palate which is a muscular structure leading to the palatoglossal arches and the uvula. The hard and soft palates are involved in mastication, swallowing and production of speech (Lockhart and Resick 2006).

Saliva

Saliva is produced by the parotid glands (in front of the ears), which produce saliva rich in amylase, the submandibular glands (in the lower part of the floor of the mouth), which produce mucinous saliva, the sublingual glands (in the floor of the mouth between the side of the tongue and the teeth), producing viscous saliva, and many minor salivary glands throughout the oral cavity (Hahn and Jones 2000). One litre of saliva can be produced daily, consisting of mainly water with electrolytes, amylase, proteins such as mucin, lysozyme and IgA and metabolic wastes (Lockhart and Resick 2006). Saliva is slightly acidic and can act as a buffer. It is also important in mastication, taste and speech. It acts as a defence against infection by physically washing debris off teeth and its proteins also have an antibacterial action (Hahn and Jones 2000).

Related theory

Dental decay

Dental decay begins with the formation of a biofilm known as plaque which is made up of sugar, bacteria and other debris on the teeth. Tooth enamel can be damaged due to bacterial action, resulting in a drop in pH around the tooth. Once there is damage to the enamel then the inner dentine can also decay (Cooley 2002). Areas of decay in teeth are known as caries. Plaque can be physically removed by brushing and flossing teeth. If it is not regularly removed, it can harden to form calculus (tartar) which requires dental treatment for removal. Calculus can also disrupt the seal between the