The most common disorder of
teeth is dental caries
Dental caries is the result of damage to the enamel and dentine by acid formed
Bacterially generated acid in the mouth is usually
neutralized by the alkaline secretions of the salivary tissue. However, when the
acid is made by bacteria in plaque, the physical density of the plaque prevents
reaching the enamel surface of the tooth.
The acid dissolves the calcium hydroxyapatite
of the enamel and progressively penetrates the full thickness of the enamel,
it as it goes.
This produces a visible cavity in the tooth.
As the cavity forms, bacteria can penetrate deeper into the tooth until the
reached, and then penetrate the dentine layer through the hollow dentinal
tubules which become distended with bacteria and tissue debris. This, combined
with the continuing demineralizing effect of the acid, leads to liquefaction of
Eventually the dentine layer may be fully penetrated, and both bacteria and acid
reach the soft central dental pulp.
Along the line of attack, the enamel and dentine are destroyed and the
Although there is limited capacity for tissue reaction because the tissues are
cellular, in chronic lesions the odontoblasts may produce secondary dentine in
at repair and restitution.
The consequences of carious attack are a pit or crater in the enamel, a
destruction of the dentine and, when the dentine is fully penetrated, acute
due to bacterial and acid damage to the soft tissues of the pulp.
The most important complications of dental caries are pulpitis and periapical
inflammation or abscess.
Spread of bacteria and acid into the soft pulp space through carious penetration
to necrosis of some of the pulp tissues, with an associated acute inflammatory
(mainly vessel dilatation, oedema, and neutrophil infiltration).
When there is
tissue necrosis a pulp abscess may form.
The combination of bacterial
and acid necrosis with increased intra-pulp pressure due to inflammatory oedema
leads to extensive necrosis of all the pulp tissues.
Inflammatory stimulation of the
nerve twigs in
the pulp produces severe pain, localized or diffuse toothache being the main
symptom of acute pulpitis.
Where the penetration of the enamel and dentine has been through a narrow
the pulp cavity remains largely isolated from the mouth cavity (closed pulpitis).
where there has been extensive destruction of the enamel and dentine, the pulp
be exposed to the oral cavity (open pulpitis).
In these cases the pulp cavity is
completely replaced by inflammatory granulation tissue, which progresses through
of vascular granulation tissue, fibrous granulation tissue, and fibrous scar.
The scarred pulp forms a polypoid protrusion into the oral cavity, which may become re-epithelialized.
Inflammation and death of
the pulp is often followed by apical periodontal infection,
the inflammation initially being confined to the small space beneath the apex,
tooth apex and the surrounding bone.
At first the infection is acute, with a
predominantly acute inflammatory reaction that is rich in neutrophils, and there is often
The inflammation eventually becomes chronic, with a heavy
infiltrate of lymphocytes and plasma cells, and granulation tissue formation (chronic
The enlarging inflammatory mass often erodes the bone around the apex of the
an osteolytic, rounded lesion composed of chronic inflammatory granulation
tissue, which may contain small neutrophil accumulations.
This is sometimes called a 'periapical
is the most common cause of teeth-related cystic lesions in the bone .
Expansion of acute or chronic inflammatory lesions at the apex of abnormal teeth
inflammation in surrounding tissues with, for example, abscesses in the mandible
pointing through the skin of the neck or producing sublingual cellulitis.
in the upper
jaw can break through the floor of the maxillary sinus to produce chronic sinus
Periodontal disease, not associated with apical abnormality, is usually a
consequence of gingivitis.
Some form of gingivitis (inflammation of the gums) is present in almost every
and is usually the result of neglected oral and dental hygiene.
gingivitis particularly affects young men, manifesting as swelling and soreness of the
with bleeding and ulceration.
Large numbers of bacteria are present in the
and are probably causative.
Chronic gingivitis occurs as a result of accumulation of bacterial plaque.
usually begins in childhood, when it is asymptomatic.
Regular brushing of teeth,
beginning in childhood, minimizes the accumulation of bacterial plaque and
reduces the likelihood of significant gingivitis in later life. Bacterial plaque becomes
calcified in adults, separating the gingiva from the tooth. There is chronic
inflammation in the gingival epithelium and sub-mucosa, with large numbers of
lymphocytes and plasma cells.
Chronic periodontitis results from the consequences of chronic gingival
inflammation in relation to the presence of calculous plaque between the gingiva
and the tooth. These are:
• Destruction of the periodontal ligament, leading to loosening of the tooth in
• Progressive deepening of the pocket between tooth and gingiva, which contains
ever-increasing amounts of sub-gingival plaque.
• Progressive inflammatory destruction of the alveolar bone, leading to severe
• Periodontal abscess formation. if the chronic inflammatory process becomes
accelerated by acute bacterial infection. This accelerates destruction of the
alveolar bone, and pus may extrude into the alveolar cavity or alongside the
tooth in the sub-gingival pocket.
Cysts related to the teeth can produce osteolytic lesions
in the bones of the jaw
Dental cysts can be simply classified into
those due to a developmental abnormality,
and those that are secondary to inflammatory disease associated with the teeth.
The most important inflammatory cyst is the radicular cyst.
It is far more common than the developmental cysts, and usually occurs in adults in
with dental caries of the permanent dentition.
Most commonly involving the
upper lateral incisors, it follows the development of a periapical granuloma resulting
Cords of squamous epithelium grow into the chronic inflammatory mass,
and central dissolution of the epithelial masses leads to cyst formation.
is characteristically inflamed, and cholesterol clefts are frequent, often with
foreign body giant cells.
The associated tooth dies, and the cyst may persist
after extraction of the tooth.
As the chronic inflammatory cyst enlarges, the
surrounding bone may be eroded, producing a well-defined area of lucency on radiology.
Among the most important developmental cystsare odontogenic keratocysts,
which usually occur in young males and are related to the mandibular molar
They may be asymptomatic or may present with an intraoral swelling.
squamous epithelium, with a variable keratin layer that is sometimes
parakeratotic, they may be multilocular and are occasionally multiple.
Treatment is difficult,
tend to recur after incomplete removal.
Dentigerous cysts mostly involve the third molars or the canine teeth.
cyst envelops the crown of an unerupted or displaced tooth and is attached to
The cyst is lined by stratified squamous epithelium, usually only a few cell
layers thick,supported on a thick fibrous wall.
At its junction with the neck of the tooth,
the cyst epithelium merges with the reduced remnants of the enamel epithelium.
contains yellow fluid, which is usually clear. However, metaplasia of the squamous
the cyst can occasionally lead to the production of keratin and mucin, which may
cyst contents mucoid or pasty.
These cysts are derived from the dental follicle
of the unerupted
tooth and are unilocular.
As their name implies, lateral periodontal cysts lie alongside the tooth.
origin is uncertain. They are frequently asymptomatic, mainly being detected in routine
as a round, osteolytic lesion that is discrete from, and lateral to, the root of
a canine or premolar tooth. The cyst is lined by thin, non-keratinized squamous epithelium,
with a surrounding
The cyst is lined by stratified squamous epithelium.
The cyst is related to the neck of a displaced tooth, and is lined by a thin
layer of stratified
Tumours derived from dental precursor tissues are rare
The most common tumour derived from
odontogenic epithelium is the ameloblastoma.
It is benign and does not metastasize.
Tumours are mainly seen in the mandible
middle-aged adults, the vast majority developing at the angle of the mandible.
are slow-growing lesions, which locally invade the bone, tumour expansion often
leading to separation of the teeth and, occasionally, to loosening.
of islands of odontogenic epithelium, often with a mixed fibrous stroma.
epithelium forms islands with peripheral, tall ameloblastic epithelial cells
loose epithelium, resembling the stellate reticulum of the developing tooth.
metaplasia may occur, which is a source of potential confusion with invasive
squamous carcinoma. The tumour may resemble a unilocular or multilocular cyst