Overview

• Most common type of cyst  
• Frequently seen between the age of 20-60  in males
• Most commonly seen in the anterior maxilla than the mandible  
• They are usually greater than 10mm in diameter
• It is associated with non-vital teeth  

Pathogenesis

• A granuloma [collection of macrophages] can lead to a cyst  
• Infection from the pulp chamber leads to  inflammation  and  epithelial proliferation  of the epithelial rest of malassez  which leads to the cyst   

– Radicular cysts arise from chronic periapical periodontitis  

Cysts Content:

– It is hypertonic compared to blood serum
– Water and electrolytes
– Large amount of serum  proteins  and  inflammatory exudate   
– Cholesterol crystals
– Grey/yellow cyst fluid  

Mechanism Of Cyst Expansion:  

• Cyst content is hypertonic compared to blood serum (high osmolality)
• Cyst wall acts as a semi-permeable membrane
• Movement of fluid from the surrounding tissues into the lumen of the cyst along the osmotic gradient
• Movement of fluid increases the hydrostatic pressure within the cyst
• Resorption  of the surrounding bone and increase in hydrostatic pressure causes the cyst to increase in size 

Histology

• Stratified squamous epithelium  
• Chronic inflammation 
• Cholesterol cleft 
• Rushton bodies 

Radiographic Features

• Well rounded radiolucency
• Defined borders
• Unilocular
• Adjacent teeth may be tilted or displaced  
• Associated with non-vital teeth

Treatment

• Root canal treatment 
  • Removes the infection. If the cyst is up to  2cm  it may regress without surgery and just with RCT
  • If resolution doesn’t occur after RCT, then biopsy should be performed  

• Enucleation  (see treatment section)
• Marsupialization (see treatment section)

Associated Cysts

Residual radicular cysts – These are cysts that are present after the extraction of the causative tooth. 

Lateral radicular cyst – Cysts that come about due to lateral canals of the tooth

Paradental cyst – These result from inflammation from partially erupted teeth

• These are attached to the neck of an un-erupted tooth and prevent eruption leading to the tooth being displaced. They surround the crown of the tooth.
• They are twice as common in males and most frequently associated with wisdom teeth and canines.

Radiographic Features

• Well rounded   
• Well defined  margins attached to the ACJ of an un-erupted tooth
• Unilocular
• Envelopes the crown of a tooth displacing it from its normal position.   
• It is often mistaken for an odontogenic keratocyst or ameloblastoma that encloses the tooth  

Pathogenesis

• Cyst lining attaches at the ACJ from reduced enamel epithelium  
• There is a strong association between failure of eruption of teeth and dentigerous cyst formation

Histology

• Cyst is composed of collagenous fibrous tissue normally free of inflammatory cells
• Cuboidal epithelium– 2 to 5 cells thick
• Forms at the level of the ACJ

Treatment

• Enucleate and extract
• Marsupialization and allow to erupt

• A soft round bluish cyst that lies superficially in the gingiva overlying a tooth about to erupt
• Normally only seen in children

Management

• Cyst roof may be removed and drained to allow eruption
• Most burst spontaneously, so no intervention is required

Cyst that form most commonly in the angle of the mandible with the ability to spread into body and ramus of the mandible. They are very aggressive in nature.

They arise from the dental lamina, also known as the gland of serres. It is named keratocyst as the cyst lining produces keratin.

Because of this aggressive nature, the World Health Organisation described the cyst as a “keratocystic odontogenic tumor”, they are however benign in nature.

It is common in the second decade of life in younger people.

They are often mistaken for ameloblastomas, especially when multilocular in nature.

Radiography

• Site: angle of the mandible (usually)
• Shape:  

– Scalloped margins (ribbon-like)
– Multi-nodular (small cavities)/ unilocular

• Margins: well defined 
• Resorption: roots are not usually resorbed 
• Adjacent teeth are rarely displaced 

Histology

• Lined by parakeratinised stratified squamous epithelium 5-10 cells thick
• Presence of daughter cyst making them liable to recur
• Basal cell layer is columnar/cuboidal
• Folded cyst lining
• Free of inflammation

Treatment

• Complete enucleation – with carnoys fluid or cryotherapy
• They DO NOT respond to marsupialization

Note: frequent reoccurence is common after marsupialisation

Possible reason for reoccurrence are:

• Finger like cyst extensions into the bone 
• Daughter cysts sometimes present and penetrating in the bone 
• Untreated underlying cause e.g. Gorlin Goltz Syndrome
• Difficult to enucleate 
• Difficult to remove due to the thin fragile cyst lining  

This is a rare tumour of odontogenic origin that is normally benign, but in rare cases can be malignant.

Most commonly found in the mandible

It is multilocular in nature as often described as a ‘soap bubble’.

Resorption of the roots can occur if the ameloblastoma is aggressive in nature.

The histology is the same as a keratocyst – the distinguishing feature is that the cortex of the mandible is affected with an ameloblastoma.

These are benign large lesions that expand the cortical plate. Adjacent teeth are usually displaced but root resorption is rare.

They have unknown aetiology, although it is suggested it can be due to trauma or inflammation.

They are more commonly found in the anterior mandible and have a multilocular appearance. They may have a honeycomb-like pattern.

There is a central form, which refers to involvement of bone and a peripheral form which refers to involvement of the gingival soft tissues.

There are 2 types:

1.  Aggressive – results in a large fast growing lesion
2. Non-aggressive

Diagnosis is confirmed via histopathology.

• Submandibular salivary gland defect or Stafne’s idiopathic bone cavity is a developmental anomaly on the lingual aspect of the mandible
• It may be mistakenly diagnosed as a cyst or tumour
• There are no clinical signs or symptoms

• It is a developmental odontogenic cyst
• Derived from the epithelial rests of malassez within lateral periodontium
• Usually found along the lateral surface of the root of a tooth.
• Asymptomatic

Radiography

• Site: Mandibular canine/premolar region
• Shape: Unilocular, round or oval shaped
• Size: less than 1cm in diameter
• Margins: well defined/well corticated

Enucleation

Enucleation is the complete removal of a cyst without cutting into it or dissecting it  

Clinical procedure:

• Mucoperiosteal flap is raised 
• Window is made in the bone 
• The cyst lining is removed and separated form it bony wall 
  • Aspiration of the cyst often helps remove the lining. The lining can be lifted from the underlying bone using a Mitchell’s trimmer 
• The rough bone should be smoothed 
• The cyst is sent in fixative to the lab 
• The cavity is irrigated [can use iodoform past, BIPP] 
• The flap is sutured up again 

Advantages

Complete lining available for analysis

Little after care required

Cavity usually heals without complication

Disadvantages

Risk of ID nerve damage

Risk of damage to atrium/sinus in the maxilla

Damage to other root apices

Risk jaw fracture

Recurrence if not comletely removed

Marsupialisation

Clinical procedure:

• Flap is made 
• Window cut 
• The cyst lining is sutured to the mucosa 
• A self cleansing cavity is made 
• Often ribbon gauze [soaked in iodoform paste, which is an antiseptic] is left in until the sides of the flap have healed, the gauze is often replaced periodically 
  • [can use iodoform paste, BIPP] 
• Or we can use a drain

Preferred choice when:

Teeth within the cyst are desired to erupt 

Cyst is associated with vital structures such as:

• The apices of many vital teeth 
• ID Canal 

Cyst is so big there is increased risk of fracture (jaw)

Disadvantages

The full cyst lining isn’t available for histological analysis 

Inconvenience of repeated visits 

Difficult to keep the cavity clean 

Only reduces size after a long time 

Scully, C. (1999). Handbook of oral disease. London: Martin Dunitz.

Jordan, R. and Lewis, M. (2004). A color handbook of oral medicine. New York: Thieme

Dental Updates: Oral medicine – Lumps And Swellings:
https://www.dental-update.co.uk/issuesSingleIssueArticle.asp?aKey=1182