The document summarizes information about periapical cysts, also known as radicular cysts or apical cysts. It defines a periapical cyst as an odontogenic cyst derived from cell rests of Malassez that proliferate in response to inflammation from pulpal necrosis. Periapical cysts typically present as round radiolucencies associated with the apex of a non-vital tooth. Histologically, they contain a lumen lined by stratified squamous epithelium and surrounded by a fibrous connective tissue wall. Treatment involves extraction of the involved tooth along with cyst enucleation or marsupialization.

1. ORAL PATHOLOGY
Periapical Cyst
(Radicular Cyst)
Abbas Naseem
B.D.S
Dated: May 14th , 2011
abbas_naseem@yahoo.com

2. ORAL PATHOLOGY
Cyst
Cyst is pathological fluid-filled cavity lined by epithelium.
COMPONENT OF CYST:
1. Lumen (cavity) Wall (capsule)
2. Epithelial lining Lumen (cavity)
3. Wall (capsule) Lining
In this schematic drawing
Arrow A  the connective tissue wall that forms the cyst.
Arrows B  various types of epithelium that can line a cyst
developing within the oral regions.
PseudoCyst ?

3. ORAL PATHOLOGY
Classification
TYPES OF CYSTS (WHO – Modified)
ODONTOGENIC CYST NON-ODONTOGENIC CYST
DEVELOPMENTAL INFLAMMATORY Nasopalatine duct (incisive canal) cyst
Odontogenic Radicular cyst Nasolabial (nasoalveolar) cyst
keratocyst (periapical cyst)
(primodial cyst) -Apical
Dentigerous -Lateral
(follicular) cyst -Residual
Eruption cyst
Lateral periodontal cyst Paradental cyst
Gingival cyst of infancts
(epstein pearls)
• Gingival cyst of adults
Glandular odontogenic
cyst; sialo-odontogenic
cyst
Orthokeratinized
odontogenic cyst

4. ORAL PATHOLOGY
Periapical Cyst - Defination
• An odontogenic cyst derived from Cell Rests of Malassez
that proliferate in response to inflammation.
• Odontogenic Cyst (Defination)
A cyst in which lining of the lumen is derived from epithelium involved in tooth development.
• Non-Odontogenic Cyst (Defination)
The epithelial lining is derived from sources other than the tooth-forming organ

5. ORAL PATHOLOGY
Periapical Cyst / Radicular Cyst / Apical Periodontal Cyst
Types of Radicular cyst (periapical cyst)
1. Apical 70%
2. Lateral 20%
3. Residual
Most common location:
1. Maxillary anterior region
2. Maxillary posterior region
3. Mandibular posterior region
4. Mandibular anterior region

6. ORAL PATHOLOGY
Periapical Cyst - Epidemiology
• Worldwide
• Common – constitutes approx one half to three fourth of all cysts in the jaws
• Relative frequency: 60-70%
• Frequent in ages between 20-60 years (rarely in <10years age)
(Peaks in third through sixth decades)
• M/F ratio: 3:2
• Maxilla is 3 times more affected than mandible

7. ORAL PATHOLOGY
Periapical Cyst – Clinical Features
• Usually asymptomatic
• Slowly progressive
If infection enters, the swelling becomes
painful & rapidly expands
(partly due to inflammatory edema)
• Initially swelling is round & hard
• Later, part of wall is resorbed  leaving
a soft fluctuant swelling, bluish in color,
beneath the mucous membrane.
• When bone has been reduced to
egg shell thickness a crackling sensation
may be felt on pressure.

8. ORAL PATHOLOGY
Periapical Cyst – Pathogenesis
PHASES
1. Phase of Initiation
2. Phase of cyst formation
3. Phase of enlargment

9. ORAL PATHOLOGY
Periapical Cyst – Pathogenesis
RECALL
• Epithelial cell rests of Malassez (ERM)
are part of the periodontal ligament cells around a tooth.
• They are discrete clusters of residual cells from
Hertwig's epithelial root sheath (HERS) that didn't
completely disappear.
(remnants of HERS that persist in PDL after root formation
Is complete)
• It is considered that these cell rests proliferate to form
epithelial lining of various odontogenic cysts such
as radicular cyst under the influence of various stimuli.
• Some rests become calcified in the periodontal
ligament (cementicles)

10. ORAL PATHOLOGY
Periapical Cyst – Pathogenesis
(PHASE 1) Phase of Initiation:
• Stimulation of cell rests of Malassez in response to INFLAMMATION elicited by
- baterial infection of pulp
- direct response to necrotic pulp tissue.
(PHASE 2) Phase of Cyst Formation:
• Epithelial cells derive their nutrients by diffusion from adjacent C.T, progressive growth
of an epithelial island moves the innermost cells of that island away from their nutrients.
• Ultimately these innermost cells undergo ischemic liquefactive necrosis, establishing
Central cavity (lumen) surrounded by viable epithelium.
(PHASE 3) Phase of Cyst Expansion:
• Breakdown of cellular debris (innermost cells) within the cyst lumen raises
the protein conc.  increased osmotic press.  resulting
In fluid transport into the lumen from the C.T side  Fluid
Ingress thus assists in outward growth of a cyst.

11. ORAL PATHOLOGY
Periapical Cyst – Pathogenesis
Major factors in the pathogenesis of cyst formation
• Epithelial proliferation
• Hydrostatic effects of cyst fluids
• Bone resorbing factors
- Infection from pulp chamber induces Inflammation & proliferation of ERM
- Internal pressure is imp. for growth of cysts.
- Cyst fluid contains proteins which exert osmotic pressure
- Hydrostatic pressure within cysts is about 70cm of water
(higher than capillary blood pressure)
- Net effect is that pressure is created by osmotic tension within the cyst cavity.
- Bone resorbing factors PGE2 & PGE3, with osteoclastic bone resorption, the cyst expands

12. ORAL PATHOLOGY
Periapical Cyst – Pathogenesis (SUMMARY)
CARIES, TRAUMA. PERIODONTAL DISEASE
PULPAL NECROSIS ( Death of Dental Pulp )
Necrotic Debris is Inflammatory Stimulus
PERIAPICAL INFLAMMATION
PERIAPICAL GRANULOMA
Composed of granulation tissue, scar & inflammatory cells
PROVIDE RICH VASCULAR AREA TO RESTS OF MALASSEZ
RESTS OF MALASSEZ PROLIFERATE
FORM LARGE MASS OF CELLS
INNER CELLS OF MASS DEPRIVED OF NOURISHMENT
UNDERGO LIQUEFACTION NECROSIS
FORMATION OF A CAVITY IN THE CENTRE OF GRANULOMA
RADICULAR CYST / PERIAPICAL CYST
Cyst wall separates pulpal irritation from bone

13. ORAL PATHOLOGY
Periapical Cyst – Diagnosis
• Diagnosis is by the combination of
- Radiographic appearances
- A non vital tooth
- Appropriate histopathological appearances
By defination, a non vital tooth is necessary for the diagnosis of a periapical cyst.
Clinical Findings
Symptoms and Signs
• Small radicular cysts do not usually become acutely infected, are frequently asymptomatic,
and can be identified on routine dental x-rays.
• Larger cysts may produce expansion of the bone, displacement of tooth roots, and crepitus
when palpating the expanded alveolar plate.
• The discoloration of nonvital teeth and a negative response of the affected tooth to electric
pulp testing or ice are the presenting signs. In addition, infected radicular cysts are painful,
the involved tooth is sensitive to percussion, and there may be swelling of the overlying soft
tissues and lymphadenopathy.

14. ORAL PATHOLOGY
Periapical Cyst – Differential diagnosis
• Periapical granuloma
• Previously treated apical patholgy, surgical defect or periapical scar
• Periapical cemento-osseous dysplasia (early phase)
• Traumatic bone cyst
• Odontogenic tumors
• Giant cell lesions
• Metastatic disease
• Primary osseous tumors

15. ORAL PATHOLOGY
Periapical lucency

16. ORAL PATHOLOGY
Q. What are the components of cysts?
Lumen, Lining, and wall.
Lumen (cavity) of cyst
Epithelial lining
Wall (capsule) –
made of connective
tissue

17. ORAL PATHOLOGY
Periapical Cyst – Histopathology
• Lumen (cavity):
- Contains cyst fluid ; which is usually watery & opalescent
- sometimes more viscid & yellowish
- sometimes shimmers with cholesterol crystals
(typically rectangular shaped cholesterol crystals with a notched corner is characteristic)
- Cholesterol crystals are not specific to radicular cyst.
- Protein content of fluid – seen as amorphous eosinophilic material
• Epithelial Lining:
- Non-keratinized stratified squamous epithelium
- Lacks a well-defined basal cell layer
- Thick, irregular, hyperplastic or net like forming Rings & Arcades
- Hyaline Bodies ( Rushton Bodies) may be found.
- Mucous cells – as a result of metaplasia
• Transmigration of inflammatory cells through epithelium is common
with more Neutrophils & less lymphocytes.

18. ORAL PATHOLOGY
Periapical Cyst – Histopathology
• Wall/Capsule:
- composed of collagenous fibrous connective tissue
- capsule is vascular & infiltrated by chronic inflammatory cells
- plasma cells are prominent or often predominate
- Russel bodies are often found.
- Pulse or Seed granulomas are often found in cyst wall.
- clefts within cyst capsule  left by cholesterol dissolved out during preparation for
sectioning. (cholesterol is derived from breakdown of blood cells)
- clefts may be seen extending into the cyst contents but are formed in the cyst wall
- Small clefts are associated with foreign body giant cells, extravasated blood cells
& blood pigments
- In the bony wall there is osteoclastic activity (bone resorption),
beyond resorption
there is active bone formation – net effect cyst expands but retains bony wall
this bony wall progressively thins (since repair is slower than resorption) & until it
forms a mere eggshell, then ultimately disappears together  the cyst then starts
to distend soft tissues & appear as soft bluish swelling.

19. ORAL PATHOLOGY
Periapical Cyst – Histopathology
- foci of dystrophic calcification
May be seen subsequent
- cholesterol clefts
to hemorrhage in the
- multinucleated foreign-body giant cells cyst wall.

20. ORAL PATHOLOGY
Periapical Cyst – Histopathology
Hyaline Bodies ( Rushton Bodies) :
characterized by a hairpin or slightly curved shaped, concenteric lamination & occasional
Basophilic mineralization.
- In small percentage of periapical cysts/radicular cysts
- are within the epithelium lining
- origin believed to be previous hemorrhage
- are of no clinical significance
Russel Bodies:
refractile & spherical intracellular bodies representing accumulated Gamma Globulin.

21. ORAL PATHOLOGY
Periapical Cyst – Histopathology

22. ORAL PATHOLOGY

23. ORAL PATHOLOGY
HYALINE BODIES
(Rushton Bodies)

24. ORAL PATHOLOGY
Rushton bodies Hyaline / Rushton bodies are found in
epithelium and rarely in CT wall.
(hyaline bodies) These are curved or linear structures
with eosinophilic staining properties.

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31. ORAL PATHOLOGY
• Cholesterol crystals in
form of clefts are often
seen in the CT wall,
inciting a foreign body
giant cell reaction.
• Originate from
disintegrating RBC’s in
presence of
inflammation.
• Different types of
dystrophic calcification
are also seen in CT wall.

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38. ORAL PATHOLOGY
Periapical Cyst – Radiologically
• Radiolucency associated is generally round to ovoid,
with a narrow opaque margin that is contiguous with the lamina dura of involved tooth.
(peripheral radioopaque component may not be apparent if the cyst is rapidly enlarging)
• Majority cysts <1.5cm in diameter
• Long standing cysts:
- Cause root resorption of offending tooth
& occasionally of adjacent teeth.
Note: cause bone resorption
but Generally do not produce bone expansion (?)

39. ORAL PATHOLOGY
Periapical Cyst – Radiologically
 Periapical cyst is well circumscribed
 distinct line of cortication separating it from the surrounding bone
 May b associated with Resorption of apices of teeth, displacement of teeth or both.
 It is distinctly rounded & unilocular  may become v.large  erosion of inferior border &
Bulging of the buccal & lingual cortical plates.

40. ORAL PATHOLOGY
Periapical Cyst – Treatment
• Root canal filling ( removal of necrotic pulp; the inflammatory stimuli)
• Extraction of the involved non-vital tooth & curettage of apical zone
• Root canal filling in association with apicoectomy(direct curretage of the lesion)
• Surgery ( epicoectomy & curretage ) is performed for lesions that are persistent,
Indicating presence of a cyst or inadequate root canal treatment.
• If incompletely removed  residual cyst
Continued cyst growth can cause significant bone resorption & weakening of maxilla &
mandible.
Enucleation
Marsupialization

41. ORAL PATHOLOGY
Residual Periapical Cyst
• A cyst that may persist after the extraction of the causative tooth is called
Residual periapical cyst
- are common cause of swelling of the edentulous jaw in older persons
- may slowly regress spontaneously

42. ORAL PATHOLOGY
Residual Periapical Cyst

43. ORAL PATHOLOGY
Residual Periapical Cyst
Oral Pathology, 4th edition,
Soams and Southam

44. ORAL PATHOLOGY
Residual Periapical Cyst

45. ORAL PATHOLOGY
Lateral Periapical Cyst
• Are rare
• Form at the side of a non vital tooth as a result of opening of a
lateral branch of the root canal.
NOTE:
• Must be differentiated from LATERAL PERIODONTAL CYSTS

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Date: References:
May 14th , 2011
May 15th , 2011 • Contemporary oral and maxillofacial pathology - 2nd edition
• Regezi Oral pathology clinical correlations - 5th edition
• Cawson’s essentials of oral pathology & oral medicine – 8th edition
• Soams & Southam ‘ oral pathology – 4th edition
• Neville’s oral pathology – 2nd edition
• Wikipedia.com
• Dr. Rima Safadi, - Lab works - Amman, Jordan
• Dr. S. S Bhagwath, cystic lesions, India

48. ORAL PATHOLOGY
(MAY 2011)
Abbas Naseem
abbas_naseem@yahoo.com