Tooth Eruption Problems

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).

FIGURE 5.1 (A) Carious cavities in upper anterior teeth. (B) X-ray showing an abscess at the base of the carious second molar.

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

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.

FIGURE 5.2 Dental abscess.

FIGURE 5.3 Severe infection in the canine region.

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

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.

FIGURE 5.4 Palatal luxation of upper left deciduous central incisor.

Attrition

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).

FIGURE 5.5 Attrition.

Abrasion

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.

FIGURE 5.6 Abrasion.

Erosion

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).

Impacted Teeth

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).

FIGURE 5.7 (A) A mesio-angular impacted lower left third molar and (B) a horizontally impacted lower right third molar.

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.

Pericoronitis

Pericoronitis is the inflammation of the gingival flap (operculum) over an erupting or impacted tooth. Usually this happens around the lower third molar (see Subchapter 17.1).

Variations in Tooth Number

Hyperdontia (too many teeth)

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.

• Extra teeth of normal shape (supplemental teeth; Figure 5.8) are uncommon, but most frequently seen in the maxillary lateral incisor, and in the premolar and third molar regions of either jaw.

• Extra teeth of abnormal form (supernumerary teeth) are also uncommon, usually small and/or conical in shape and are seen particularly in the midline of the upper arch (mesiodens).

FIGURE 5.8 A supernumerary incisor.

Term to Learn

Mixed dentition period: this is when the permanent teeth start erupting, which is before all the deciduous incisors have been lost (exfoliated) so that there are both permanent and deciduous teeth in the mouth at the same time.