Odontogenic cysts of
Dr. T. Balasubramanian M.S.
Synonyms: Cysts of maxilla, radicular cysts,
dental cysts, dentigerous cysts
Maxillary sinus is
closely related to the upper premolar and molar teeth. Any
infection / pathology involving the root of these
tooth will also have its effect on the maxillay sinus.
Definition: Odontogenic cysts are defined as epithelial cell
lined cysts. This lining is derived from the odontogenic
epithelium. Most of these odontogenic cysts are defined by
their position than by their histology. It is important hence
to describe even the site of lesion while sending the
surgical specimen to a pathologist.
are the cysts of odontogenic origin:
1. Radicular cyst:
Synonyms - Peiapical cyst, dental
This is the
commonest of all odontogenic cysts. This is usually caused due
to root infection involving the tooth closely related to the
maxillary sinus antrum. The resulting pulpal necrosis causes
release of toxins at the apex of the tooth leading to periapical
inflammation. This inflammation
stimulates the Malassez epithelial rests, which are found in the
periodontal ligament, resulting in the formation of a periapical
granuloma that may be infected or sterile. The epithelium
undergoes necrosis and the granuloma becomes a cyst. The cyst
could well be sterile if the patient had received
antibiotic treatment for dental infection. These lesions
when small can easily be missed until and unless a routine
it is virtually impossible to differentiate granuloma from a
cyst. If the lesion is large it is more likely to be a
cyst. Radiographically both granuloma and cyst appear to
be radiolucent, associated with the apex of non vital
These lesions can grow
into large lesions because they apply pressure over the bone causing
erosion. The toxins released by the granulation tissue is one
of the common causes of bone erosion. These are non
neoplastic lesions. Microscopically, the
epithelium is a nondescript stratified squamous epithelium without
keratin formation. Evidence of inflammation may
be observed in the lining wall.
features: As the cyst expands it causes erosion of the floor
of the maxillary sinus. As soon as it enters the maxillary
antrum the expansion starts to occur a little faster because there
is space available for expansion. When it reaches a size
wherein it fills up the whole antrum, it can erode the anterior
wall of the maxilla (in the canine fossa area). This is the
weakest portion of the maxillay bone. When it erodes the
anterior wall of the maxilla it could cause expansion of
the maxilla which could be seen as a swelling in the cheek
area. On palpation egg shell crackling may be felt in the
anterior wall of the maxilla over the canine fossa.
There will be associated tenderness.
Tapping the teeth with a tongue
depressor will cause tingling sensation because of involvement of
the root of the teeth.
showing swelling of right cheek caused by expanding dental
CT scan showing dental cyst of maxilla
If the cyst is small, then it may resolve with endodontic therapy of
the involved tooth. If the cyst is large then it will have to
excised / marsupialised through Caldwell Luc approach.
With the advent of nasal ensoscopy, the lesion could be accessed
using a nasal endscope. The excised specimen should be sent
for histopathological examination because squamous cell carcinoma
could be lurking within the cystic lesion.
cyst: This is the second commonest of odontogenic cysts.
It is always associated with unerupted tooth. Infact it
develops within the normal dental follicle. It is more common
over maxillary third molars and maxillary canine tooth areas.
This is not considered to be a true neoplasm. Most of these
dentigerous cysts are asymptomatic and are incidental
The usual radiographic
appearance is that of a well-demarcated radiolucent lesion attached
at an acute angle to the cervical area of an unerupted tooth. The
border of the lesion may be radiopaque. The radiographic
differentiation between a dentigerous cyst and a normal dental
follicle is based merely on size. While viewing an xray a
dentigerous cyst should always be differentiated from a normal
dental follicle. In all probability a large sized cyst could
only be a dentigerous cyst.
Histologically a normal
dental follicle is lined by enamel epithelium, where as dentigerous
cyst is lined by non keratinising stratified squamous
epithelium. Since the dentigerous cyst develops from
follicular epithelium it has more potential for growth,
differentiation and degeneration than a radicular cyst.
Occasionally the wall of a dentigerous cyst may give rise to a more
ominous mucoepidermoid carcinoma. Dentigerous cysts due to its
propensity for rapid expansion may cause pathological fractures of
Management: Dentigerous cyst must be
excised surgically via a Caldwell Luc approach.
cyst: By definition this cyst develops in place of
tooth. This could be due to the fact that formed dental
follicle undergoing cystic degeneration instead of
odontogenesis. Histologically these lesions are lined by
stratified squamous epithelium.
These cysts must be
of an excised primorial cyst
4. Residual cyst:
These cysts are caused by retained pericapical cysts after the teeth
is removed. The cyst wall is formed by stratified squamous
5. Lateral periodontal cysts: This is
actually a misnomer. These are not inflammatory cysts, and
they are not associated with periodontal epithelium. These
cysts are associated with lateral canals within the tooth
structure. These cysts are always well demarcated, small and
radiolucent. The lining epithelium is made of thin cuboidal
cells. The cyst wall shows no evidence of inflammation, and is
thickened by the presence of fibrous tissue.
cysts again must be surgically removed.
cysts: are of two types i.e. adult and new born.
In newborn these cysts are multiple, but rarely may also be
single. They are located in the alveolar ridges. In
children these cysts originate from the dental lamina. They
are asymptomatic and donot cause any problems. In adults these
cysts are commonly found in the lower premolar area. It is
7. Odontogenic kertocyst: These cysts
are very important because of their aggressive behaviour.
These cysts are difficult to remove and commonly recur.
Histologically these cysts are lined by stratified squamous
epithelium which is capable of producing orthokeratin and
parakeratin. Commonly both types of keratin are commonly
produced. The lumen of these cysts are filled with foul
smelling cheesy material. This is nothing but collected
degenerated keratin. These cysts commonly give rise to
These cysts must be completely removed to
prevent recurrence. When associated with hypertelorism,
midface hypoplasia, relative frontal bossing and prognathism, mental
retardation, schizophrenia, multiple basal cell carcinomas,
calcification of the falx cerebri, bifid ribs, palmar pitting, it is
known as Basal Cell Nevus Syndrome.
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