|CYSTS OF THE JAWS
Cysts are abnormal epithelium-lined cavities which often contain fluid but only contain pus if they
become too infected. Jaw cysts predominantly arise from odontogenic epithelium and grow by a
means not fully understood but involving epithelial proliferation, bone resorption by prostaglandins,
and variations in intracystic osmotic pressure.
Many are detected as asymptomatic radiolucencies on X-ray; others present as painless swellings,
almost always of the buccal cortex. Infected cysts present with pain, swelling, and discharge.
Vitality test associated teeth. Take a DPT and a periapical film when possible to screen for size and
coexisting pathology. Transillumination rarely helps, but aspiration is sometimes useful and can
help distinguish some lesions. Rarely, cysts may present with a pathological fracture, especially of
(a) Enucleation with primary closure is commonest and generally the Rx of choice. It consists of
removing the cyst lining from the bony walls of the cavity and repositioning the access flap. Any
relevant dental pathology is treated at the same time, e.g. by apicectomy.
(b) Enucleation with packing and delayed closure is used when badly infected cysts, particularly
very large ones, are unsuitable for primary closure. Pack with Whitehead's varnish or BIPP.
(c) Enucleation with lbone grafting. Rarely useful.
(d) Marsupialization. This is the opening of the cyst to allow continuity with the oral mucosa;
healing is slower than with enucleation and a cavity persists for some time. It is useful to allow
tooth eruption through the cyst or where enucleation is C/I.
Always submit cyst lining for histopathology.
Types of cysts
Many classifications exist, few are helpful.
Inflammatory dental cysts are very common. Described as apical or lateral depending on position in
relation to tooth root, or residual if left behind after tooth extraction. Necrotic pulp is the stimulus,
and the epithelium comes from cell rests of Malassey. Rx: enucleation plus endodontics or
Dentigerous cysts form around the crown of an unerupted permanent tooth and arise from reduced
enamel epithelium. May delay eruption. Rx: marsupialization or enucleation, depending on position.
Keratocysts are lined by parakeratinized epithelium derived from the remnants of the dental lamina
and are thought to replace a missing tooth. They have a fluid filling with a protein content 4 g/dl.
Aspiration of samples for biochemistry and cytology for parakeratinized squames can be helpful. It
is important to identify these cysts, as outpouching walls and 'daughter' or 'satellite' cysts make
them more liable to recur. Their multiloculated appearance on X-ray may confuse them with an
ameloblastoma . Rx: careful enucleation, and/or cryotherapy and/or Carnoy's solution, or
aggressive curettage of the cavity. Rarely, excision is needed if recurrent.
Calcifying epithelial odontogenic cysts are rare and distinguished by areas of calcification and 'ghost
cells' on histology. Rx: enucleate.
Solitary bone cysts are usually an incidental finding on X-ray and devoid of a lining, but may
contain straw-coloured fluid. They probably arise following breakdown of an intraosseous
haematoma, and are distinguished by a scalloped upper border on X-ray where the cyst pushes into
cancellous bone between teeth but spares the lamina dura. Opening the cyst, gentle curettage, and
closure heals these 'cysts'; associated teeth need no Rx.
Aneurysmal bone cysts are expansile lesions full of vascular spongy bone. Present as a
symptomless swelling, unless traumatized, when bleeding causes pain and rapid expansion. Small
ones can be carefully enucleated, but larger aneurysmal bone cysts need excision and possible
reconstruction since they will recur if incompletely excised.
Fissural cysts are not associated with dental epithelium but arise from embryonic junctional
epithelium. They are rare and include incisive canal cysts, incisive papilla cysts, and nasolabial
cysts. Rx: enucleation.