CHAPTER 5 Oral Disease
Diseases may be congenital (present at birth) or acquired (develop at some stage after birth). Most dental (odontogenic) disease is acquired and caused by the build-up and activity of micro-organisms (mainly bacteria) on the tooth surface within the dental bacterial plaque.
Plaque is a film containing bacteria (a biofilm) that builds up rapidly and is usually removed by toothbrushing and other mechanical oral hygiene aids. If plaque is not removed it eventually hardens into calculus because of the deposition of calcium salts. Chemicals in certain mouthwashes and toothpastes can inhibit the build up of plaque, and some inhibit calculus (tartar) formation. These oral healthcare products are discussed in Chapter 8.
The activity of the micro-organisms in plaque is responsible for, or may aggravate, a variety of oral diseases, in particular dental caries (tooth decay) and inflammatory periodontal disease (gingivitis and periodontitis), which are the most common oral diseases.
Table 5.1 shows the main dental diseases.
An infant who is teething may show irritability, disturbed sleep, flushed face, drooling, a small rise in temperature and/or a rash. Teething does not cause diarrhoea or any other disease (but these may occur coincidentally).
Teeth can erupt up to 12 months late – this is usually of little significance. Longer delays in tooth eruption are often caused by local factors such as the tooth becoming impacted against another tooth as it travels through the bone. The teeth that most often get impacted are the third molars (wisdom teeth), premolars and canines, because these are usually the last teeth to erupt.
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).
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.
|Fructose (except in fresh fruits and vegetables)||Golden syrup|
|Hydrolysed starch||Maple syrup|
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.
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.
|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 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.
Early caries, that is when there is only enamel decay, is painless. When the caries reaches the dentine, the person may get transient pain with sweet, hot or cold stimuli. When the caries approaches the pulp, the person may feel more prolonged pain, which may sometimes be spontaneous. Once caries reaches the pulp it becomes inflamed, causing spontaneous and severe pain (toothache).
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.
Attrition is a form of tooth surface loss. It is the wearing away of a tooth’s biting (occlusal) surfaces due to chewing (mastication). It is most obvious in people who have a coarse diet. Attrition can also occur in people with a habit such as bruxism (grinding of teeth). The incisal edges of the anterior teeth and the cusps on the occlusal surfaces of the premolars and molars wear down. Once the enamel is breached, the softer dentine is lost faster than the enamel, which results into a flat or hollowed surface (Figure 5.5). The tooth may need a restoration (see Chapter 9).
Abrasion is another form of tooth surface loss – the wearing away of the hard tissues at the neck of the tooth by a habit such as toothbrushing with a hard brush and coarse toothpaste. The gingiva recedes but is otherwise healthy. The cementum and dentine wear down but the harder enamel survives, resulting in a notch (Figure 5.6). The exposure of dentine also means the tooth may become sensitive to hot and cold. There may also eventually be tooth fracture. The tooth may need a restoration (see Chapter 9). Use of desensitising toothpastes and fluoride application may also help.
Erosion is tooth surface loss caused by dissolution of the tooth minerals by acids other than those produced in caries. Fruits or fruit drinks, cola (and other carbonated drinks) and stomach (gastric) acid are the main causes of erosion. In most patients there is little more than a loss of normal enamel contour but, in more severe cases, dentine or pulp may be involved. Patients who have a habit that causes erosion should be counselled to stop the habit. The teeth may need to be restored (see Chapter 9).
Teeth can fail to erupt fully because of insufficient space in the dental arch. The teeth most commonly affected are the third molars (wisdom teeth, lower third molars most common), second premolars and canines (Figure 5.7).
Impacted teeth may well be asymptomatic, but occasionally they can cause pain. This is usually because of the caries or pericoronitis that develops. Impacted teeth may also lead to cyst formation. There is no evidence that they contribute to malocclusion.
Treatment may include orthodontics to guide the impacted tooth to its correct position and sometimes surgery. The latest guidelines of the National Institute for Health and Clinical Excellence (NICE) recommend removal of impacted teeth only if they are causing problems such as recurrent pericoronitis or caries.
In the mixed dentition period it is not uncommon to see what appear to be two rows of teeth in the lower incisor region. Additional teeth may be seen occasionally in otherwise healthy individuals, occasionally in those with rare disorders.