Radicular(periapical)cyst

Odontogenic cysts divided into:

• Inflammatory cysts:

1. Radicular (apical) cyst
2. Lateral cyst
3. Residual cyst
4. Paradental cyst

• Developmental cysts:

1. Dentigerous (follicular) cyst
2. Eruption cyst
3. Odontogenic keratocyst (Keratinizing cystic odont. tumor)
4. Orthokeratinizing odont.cyst
5. Gingival cyst
6. Lateral periodontal cyst
7. Glandular odont.cyst (Sialo-odont.cyst)
8. Calcifying odont.cyst (Gorlin cyst) (Ghost cell tumor

Developmental cysts are of un known cause but not from an iflammatory reaction while Inflammatory cysts are the result of inflammation.

1-Radicular(Periapical cyst).

Def,
Radicular cyst is the most common cyst in the jaw,associated with non vital tooth
Origin,
Epithelial rests of malassez (remnant of epith root sheath of hertwig
Etiology and pathogenesis,
Radicular cyst develops on top of periapical granuloma(chronic periapical perodontitis). which is amass of chronic granulation tissue formen in response to infection from carious lesion spread to pulp then inflammation of pulp to apical foramen then periapical tissue= Granuloma at root apex, if proliferation of epith rasts of malassez -found in PDL- occurs, it will give rise to cyst formation = Radicular cyst
3 mechanisms of cyst formation on top of granuloma:
as we mentioned that there are epith rests proliferation then
1} when proliferate in the form of sheets.
the proliferation in granuloma occurs in form of shet ,so central epith cells are away from nourishment due to proliferation so it degenerates and die forming cyst
2} when proliferate in the form of arcades.
they trap C.T causing liquifactive necrosis (necrosis) as C.Y is vascular nourished by blood vessels
3} epithelization of abscess cavity if developed on top of periapical abscess

Cyst expansion,
cyst expansion means how cyst grows up? Radicular cysts as all cysts expand by Osmosis & Bone resorption.
1} Cyst expansion by Osmosis:
Because of the large number of osmotically active molecules in the cyst fluid, the contents are hypertonic inside the cyst so movement of fluid from tissue to lumen occurs increasing the hydrostatic pressure within the cyst causing it to expand in all directions.
2} Cyst expansion by Bone resorption:
Fibrous capsule of the cyst contains fibroblasts that release collagenase & bone resorping factor as prostaglandin which stimulate osteoclastic activity

Clinical features,

• Symptomless (no pain)
• affects any age but more in permanent.
• In maxilla more than mandible

Radiographic picture,

Histopathological features,
under microscope ,there is cystic cavity lined with non keratinized stratified squamous epith. the fibrous tissue surrounding contains chronic inflammatory cells, russels bodies,rushton bodies and cholestrol clefts with giant cells and mucous cells may be found

Russel bodies: degenerated plasma cells
Rushton bodies: thin ,slightly curved bodies ,eosinophilic,basophilic in mineralization, hematogenic or odontogenic in origin

Cyst contents:varies from watery to fluid to semi solid brownish material of paste like consistency contain break down proudcts (degenerated epith ,inflammatory cells ,C.T component) ,serum protiens (immunoglobulins) ,cholestrolcrystals and water & electrolytes

Radicular cyst on top of granuloma

Cyst on top of granuloma at root apex

Rushton bodies

Mucous secreting cells due to mucous metaplasia

Newly formed cyst (immature cyst)
irregular & vary in thickness

Treatment,
Treatment of radicular cyst as all inflammatory cyst either by Enucleation or Marsupilaization.


1} Enucleation:
the usual and effictive method used when the affected tooth is to be extracted or root filled and preserved, amucoperiosteal flap is raised over the cyst and awindow is opened in the bone to give access, the cyst then is separated from the bony wall carefully and the edges of the bony cavity is smoothened, bleeding is controlled and the cavity is irrigated for removal of debris, the mucoperiosteal flap is replaced and
sutured , the suture should be left for 10 days.

2} Marsupialization:
this method is used for large cyst when fracture is arisk, the cyst is opened as for enucleation but the lining is sutrured to mucous membrane at the margins of opening ,the aim is to produce self cleansing cavity which become an invagination of the soft tissue and the cavity is initially packed with gauze.

Cysts

first,we will discuss CYSTS as awhole odont.&nonodontgenic

initially we will give notes or abackground;
thetooth germ (tooth forming organ) consists of:
1.Enamel organ.
.origin: Ectoderm
.produce:Enamel
2.Dental papilla.
.origin:Ectomesenchyme
.produce:Dentin & Pulp
3.Dental sac (follicle).
.origin:Ectomesenchyme
.produce:Cementum & PDL & Alveolar bone

-Ectoderm gives oral epithelium
-Ectomesenchyme gives connective tissue and has similar characteristics of mesenchyme but arise from neural crest cell which are ectoderm in origin
-Remnants of dental lamina are epith rests of serres
-Reduced enamel epith derived from enamel organ and cover the fully formed crown of an unerupted tooth
-Remnants of epith root sheath of hertwig are epith rests of malassez

CYST: -it's apathological cavity lined with epith surrounded by C.T contains fluid or semi fluid, not containing pus .
-divided into 2 main groups:
.odontogenic cysts:epith lining derived from epith residues of tooth forming organ
.Non odntogenic cysts:epith lining derived from other sources than tooth forming organ
Classification of cysts:

1. Odontogenic cysts
2. Non odontogenic cysts
3. Non epitheliated primary bone cyst(pseudocysts)
4. Soft tissue cysts