5: Oral Disease

CHAPTER 5 Oral Disease

Diseases of the teeth

Table 5.1 shows the main dental diseases.

Dental Caries (Tooth Decay)

Dental caries is a very common disease. The main plaque micro-organism that causes dental caries is the bacterium Streptococcus mutans (also called viridans streptococci). Other bacteria such as Lactobacillus and Actinomyces may also play a role. The bacteria act by converting the sugars in the diet to acids (especially lactic acid). The acids destroy (decalcify) the enamel and dentine of the teeth (Figure 5.1).

Sugars are mainly found in the diet as sugar (lactose) in milk and non-milk sugars. Lactose is less cariogenic than the other sugars.

The non-milk sugars include the common table or cane sugar (sucrose), glucose, and fruit sugar (fructose). Sugars are also added to many foods and drinks, in particular to refined carbohydrates such as starch and foods such as cakes and biscuits. Non-milk sugars (Table 5.2) are the most cariogenic. Dietary starch is also broken down slowly by salivary enzymes to glucose and maltose. Concentrated fruit juices and dried fruits also have a high concentration of sugars such as fructose and are therefore also cariogenic. Fresh fruits and vegetables are not cariogenic.

TABLE 5.2 Cariogenic Sugars

Pure Sugars Mixtures
Dextrose Brown sugar
Fructose (except in fresh fruits and vegetables) Golden syrup
Glucose Honey
Hydrolysed starch Maple syrup
Invert sugar Treacle

The caries disease process

The sugars in the diet are converted to lactic acid. When the acidity increases to a particular level (i.e. the pH falls), minerals such as calcium and phosphate are released from the tooth (called demineralisation or decalcification) causing dental caries (decay). The level of acidity is measured by finding out the pH, which is low when the acid level is high. If the pH in the mouth falls below 5.5 (the critical pH) the tooth starts to decalcify. The longer the pH remains low in the mouth, the greater the decalcification and damage. Thus eating sticky sugars (e.g. toffees), repeatedly eating or drinking sugary foods, or sucking sweets for hours, leads to a long drop in the pH, and a lot of damage. Even more damage occurs if the sugars are eaten just before going to sleep, because saliva production falls during sleep, and therefore the natural cleaning of the mouth is reduced.

The least tooth damage is done by:

Decalcification produces opaque whitish areas on the tooth, which are painless. Decalcification is also reversible to a point if the person changes their diet and reduces intake of more cariogenic carbohydrates.

The critical pH for dentine demineralisation is higher at around 6.5 (so less acid needed) and the dentine is softer than enamel, so caries spreads more rapidly once it reaches dentine. It may then spread to the pulp causing infection, inflammation and pain (pulpitis).

Table 5.3 summarises the key points you need to know about dental caries.

TABLE 5.3 Facts You Should Know About Dental Caries

Cause Plaque bacteria, especially Streptococcus mutans, which acts on sugars to produce lactic acid, which decalcifies (demineralises) the teeth
Plaque This biofilm tends to form in pits and fissures, interproximally at contact areas; and at the cervical margins (sites where caries begins)
Main sugars implicated in caries Sucrose, glucose
Sugars and sweeteners rarely implicated in caries Fructose, lactose, sorbitol, aspartame
Acidity (critical pH) below which enamel decalcification occurs 5.5
Methods of detection Visual examination
Bitewing radiographs (see Chapter 14)
Transillumination (shining a light through the tooth)
Electronic caries detectors
Using a probe (but this may cause further damage; see Chapter 7)
Preventive measures Consuming less sugars in the diet
Using fluorides, e.g. fluoridated toothpastes
Using amorphous calcium phosphate

If caries is not treated

If the carious process is allowed to progress, it destroys the enamel, causing a cavity to form in the tooth. Eventually it reaches the dentine. Once caries reaches the dentine, the carious process speeds up. Also, the patient may feel pain on stimulation with sweet/sour or hot/cold. This pain is similar to the pain that occurs when dentine is exposed due to loss of enamel for other reasons such as trauma, erosion or abrasion (see p. 141). The pain subsides within seconds of removing the stimulus. The pain may be poorly ‘localised’, that is, it may be difficult for the patient to say where exactly it is. Often pain is localised only to an approximate area within two to three teeth of the affected tooth.

The inflammation causes swelling of the pulp but, since the pulp is confined within the rigid pulp chamber, the pressure builds up. Thus there is severe and persistent pain in the tooth. The swelling also stops the blood flow into the pulp – which then dies. The pain may then subside for a while. However, the dead pulp is infected with bacteria from the mouth. So the infection can then spread through the tooth root apex and cause apical periodontitis. This is very painful, especially when the tooth is touched or the patient bites on it. Such a tooth must be root treated (endodontics) or extracted (exodontics) in a timely fashion. Otherwise a dental abscess (Figure 5.1B), granuloma or cyst (see below) will eventually form.

Periapical Abscess (Dental Abscess)

A dental abscess often follows pulpitis caused by caries or trauma. The pulp, and so the affected tooth, is dead (non-vital). Therefore although the tooth cannot itself cause pain, the inflammation travels to the bone surrounding the tooth apex. This is called apical periodontitis. If the inflammation persists, it may cause an abscess (apical or dental abscess) both of which produce pain. A dental abscess will cause pain and also result in a swelling, typically in the labial or buccal gingiva (Figure 5.2). Sometimes the face can swell up too (Figure 5.3) and the patient may also develop lymph node swelling and a fever.

Analgesics and antibiotics may be needed in the short term to alleviate the patient’s symptoms. Eventually, extraction or root canal treatment of the affected tooth will be required to remove the source of infection, or the problem will return.

If the tooth is not correctly treated, a cyst (periapical, radicular or dental cyst) can develop. Again, either root canal treatment or root end surgery (apicoectomy or apicectomy) will then be needed (see Chapter 9).


Trauma to the teeth is commonly seen in sports, road accidents, violence, epilepsy, and in restorative dentistry! Tooth trauma is seen mainly in boys or young men. It usually affects the maxillary incisors. Because of the impact of trauma, a tooth can be lost from the mouth or dislodged within its socket (Figure 5.4), fractured (the crown or root), or it can die. (See also Chapter 16). Dental trauma is also seen in children who have been abused. In all forms of trauma, there can also be damage to the jaws or soft tissues. Thus it is important for the clinician to take a careful history and do a thorough examination to ensure there are no injuries elsewhere in the body, especially head or chest injuries (which can be fatal), or damage to the neck – which can lead to paralysis or death.

Jan 8, 2015 | Posted by in Dental Nursing and Assisting | Comments Off on 5: Oral Disease
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