DEFINICTION

Killey and kay(1966) – cyst constitutes an epithelium –lined sac filled with fluid or semifluid material

Killey and kay (1966) – revised definition”A cyst is an abnormal cavity in hard or soft tissue which is contains fluid, semifluid or gas and is often encapsulated and lined by epithelium.”

Kramer’s(1974) – A cyst is pathologic cavity having fluid, semifluid, or gaseous contents that are not created by the accumulation of pus; frequently, but not always, is lined by epithelium.

PARTS OF CYST:

• There are three main parts of cyst:
• Wall that is made of connective tissue
• Epithelial lining
• Lumen of the cyst.

CAUSES OF CYST:

Common causes of cyst includes

• Tumors
• Genetic conditions
• Infections
• A fault in an organ of a developing embryo.
• A defect in the cells.
• Chronic inflammatory conditions.
• Blockages of ducts in the body that causes a fluid build up.
• Impact injury that breaks a vessel.

TYPES:

• True cyst: These are the cysts that are lined by epithelium e.g Dentigerous cyst, Radicular cyst.
• Pseudo cyst : These are the cysts that are not lined by epithelium. E.g Solitary bone cyst,Aneurismal bone cyst

CLASSIFICATION

Various classifications have been given:

1. WHO Classification
2. Shears Classification
3. Shafers Classification

WHO Classification is divided into 2 Types:

1. Developmental
2. Inflammatory

Developmental:

I. Odontogenic:

• Primordial ( Kerato ) cyst.
• Gingival cyst.
• Eruption cyst.
• Dentigerous ( Follicular ) cyst.

II. Non Odontogenic:

1. Naso palatine duct ( Incisive canal ) cyst.
2. Globulomaxillary cyst.
3. Naso labial ( naso alveolar ) cyst.

Inflammatory Cysts: Radicular cyst.

SHEAR’S CLASSIFICATION

It is divided into 3 types:

1. Cysts of Jaw
2. Cysts associated with Maxillary Antrum
3. Cysts of the soft tissues of the Face, Neck and Mouth Cysts Of Jaw:

Epithelial Cysts Of Jaws:

I. Odontogenic:

A).Developmental

1. Primordial (Kerato) cyst .
2. Gingival cyst of infants .
3. Gingival cyst of adults .
4. Lateral periodontal cyst .
5. Dentigerous cyst .
6. Eruption cyst .
7. Calcifying odontogenic cyst.

B). Inflammatory

1. Radicular cyst .
2. Residual cyst .
3. Inflammatory collateral cyst.
4. Para dental cyst.

II. Non-Odontogenic:

1. Nasopalatine duct cyst & Incisive canal cyst
2. Median palatine cyst
3. Median alveolar cyst
4. Median mandibular cyst
5. Globulomaxillary cyst
6. Naso labial (naso alveolar) cyst

Non Epithelial Cysts:

A). Simple bone cyst:

1. Traumatic
2. Solitary
3. Hemorrhagic

B). Aneurysmal bone cyst.

Cysts Associated with the Maxillary Antrum

1. Benign mucosal cyst .
2. Surgical ciliated cyst of maxilla.

Cysts of the Soft tissues of the Face, Neck and Mouth

1. Dermoid & Epidermoid cysts
2. Branchial cleft cyst (Lympho epithelial cyst)
3. Thyroglossal duct cyst
4. Anterior median lingual cyst
5. Oral cyst with gastro intestinal epithelium
6. Cystic hygroma
7. Cysts of the salivary glands
8. Parasitic cysts: Hydatid cyst, Cysticerous cellulosae

SHAFERS CLASSIFICATION

1. Primordial cyst .
2. Dentigerous cyst & Eruption cyst .
3. Periodontal cyst :
   a. Apical periodontal cyst .
   b. Lateral periodontal cyst .
4. Gingival cyst :
   a. Gingival cyst of newborn(Dental lamina cyst)
   b. Gingival cyst of adult .
5. Odontogenic kerato cyst .(Jaw cyst, Basal cell nevus & Bifid rib syndrome)
6. Calcifying odontogenic cyst .

PATHOPHYSIOLOGY OF CYST

• Phases of cyst development :

CYST INITIATION

Stimulation of cell rests of Malassez in response to INFLAMMATION elicited by - baterial infection of pulp - direct response to necrotic pulp tissue.

CYST FORMATION

• Proliferation of Epithelial Lining and fibrous Capsule
• Insufficient diffusion of oxygen and nutrients
• Death of central cells or disquamation of the central cells.
• Formation of a small cystic cavity

CYST ENLARGEMENT

• Attraction of fluid into tthe cyst cavity
• Retention of the fluid within the cavity
• Production of raised internal hydrostatic pressure
• Resorption of the surrounding bone with an increase in the size of the cavity

CLINICAL FEATURES

• Commonly seen in 1st and 3rd decade of life
• Males more affected than females
• Capable to becoming aggressive lesion
• Asymptomatic unless they develop into very large cyst or get infected
• Expansion of bone  Facial asymmetry
• Displacement and root resorption of adjacent teeth
• Pain may occur if secondary infection supervenes

TREATMENT

• Marsuplization
• Enucleation of cyst together with removal of unerupted teeth
• This permits decompression of a resulting decrease in the size of bone defects.