Cyst is a pathological cavity lined by a epithelium and containing fluid or semi solid material.
Classification of cyst of the jaws
- Gingival cysts of infants (epstain pearls)
- Odontogenic kerato cyst(primodial cyst)
- Orthokeratinized odontogenic cyst
- Dentigerous (follicular cyst)
- Eruption cyst
- Lateral periodontal cyst
- Gingival cyst of adults
- Glandular odontogenic;sialoodontogenic cyst
- Nasopalatine duct cyst
- Nasolabial cyst
- Inflammatory odontogenic cyst
Key features of jaw cysts
- Form sharply defined radiolucencies with smooth borders.
- Fluid may be aspirated and thin walled cysts may be trans illuminated.
- Grow slowly,displacing rather than resorbing teeth.
- Symptoms unless infected and are frequently chance radiographic findings.
- Rarely large enough to cause pathological fracture.
- Form compressible and fluctuent swellings if extending in to soft tissues.
- Appear bluish when close to the mucosal surface
Major factors in the pathogenisis of the cyst formation
- proliferation of epithelial lining and fibrous capsule
- hydrostatic pressure of cystic fluid
- resorption of surrounding bone.
- Sequalae of acute periapical periodontitis
- Ultimate resault of chronic periapical periodontitis-due to acute inflammation that has been inadequately drained and incompletely resolved.
- tooth is usually non vital
- First recognized as rounded area of radiolucency at the apex of the tooth-usually 5mm in diameter and well defined margins.
- Interprited as early cyst formation.
- Chronic periodontitis is typical chronic inflamation characterized by lymphocytes,plasma cells and macrophages.
- Infection is confined by inflammatory cells and granulation tissue surrounds the area.the granulation tissue grows into rounded mass forming granuloma.
- Osteoclasts resorb the bone to accomadate it.
- Spontaneous healing is absent due to tunnel of continuous infection in the root canal
- Variable degrees of proliferation of the epithelial rests of Malaassez in a periapical granuloma at the apex of the dead tooth are common.
- Epithelial proliferation may be sufficient to lead ultimately to cyst formation.
- Most common type(Between 20-60yrs)
- Slowly progressing pain less swelling
- Pain and rapid exantion if inflammation/infection occurs.
- First swelling is hard,then become thinner and thinner.(creckling sensation->then fluctuent bluish colour swelling when par of the wall is entirely resorbed.
- Epithelium derived from-epithelial cell rests of malassez-stratified squamous epithelium.Hyaline/Rushton bodies may be seen in the epi.
- Cyst capsule-Colagenous fibrous connective tissue.
- Clefts-within the cyst capsule there are often areas split up by the fine needle shaped clefts.
- form in bone in relation to the root of non vital tooth
- arise by epithelial proliferation in an apical granuloma
- usually asymptomatic unless infected
- Diagnosis-radiograph+non vital tooth+histology
- Do not recur after complete enucleation
- Residual cysts can remain after the causative tooth has been extracted and diagnosis is then less obvious
- Cholesterol crystals often seen in the cyst fluid but not specific to radicular cyst.
- Arises in the bone and surrounds the crown of the tooth and is a dilation of the follicle.
- Attached to the neck of the tooth.
- Dentigerous cyst can cause pain or no pain.
- Affected teeth id often displaced.
- commonly associated with unerupted third molars and canines.
- May be mistaken radiographically for an odontogenic keratocyst or ameloblastoma.
- Respond to enucleation or masupialisation and do not recur after treatment.
- Occationally pseudoloculation as a resault of trabeculation or ridging of the bony wall can be seen.
- Slow growth causes sclerotic bony outline and well defined cortex.
- Lining of dentigerous cyst typycally consist of thin,sometimes bilaminar,stratified epithellium,frequently with numerous mucous cells.
- Epithelium may be occationally keratinized by metaplasia.
- Fibrous wall similar as Radicular cyst but inflammatory changes are typicaly absent.
Parakeratinized odontogenic cyst/Odontogenic keratocyst
- 5-11% of jaw cysts
- incident peaks in 2nd and 3rd decades.
- Form intraosseously,most frequently in the posterior alveolar ridge or angle of mandible.mandible 75%,predominantly premolar and molar region
- may grow round the tooth
- Sometimes multilocular radiographically
- Spread extensively along marrow spaces before expanding the jaw
- Frequently recur after enucleation
- Definitive diagnosis only by histopathologically,although clinical and radiographic features may help.
- May be confused with ameloblastoma or with dentigerous cysts radiographically.
- May be part of the basal cell naevus(Gorlin)synndrome
- usually multilocular
Typycal Histological features of odontogenic keratocyst
- Epithelial lining of uniform thickness
- Flat lower border of epithelium
- Clearly defined basal layer of tall cells in parakeratinized cysts
- Thin eosinophilic layer of para keratin
- Cyst lining typically much folded
- Epithelial lining weakly attached to the fibrous wall
- Thin fibrous wall
- Satellite cysts in the wall
- Inflammatory cells typically absent or scanty
Evidance that OKC may be neoplastic
- High proliferative activity of epithelial lining
- Caused by mutation or deletion of PTCH tumor supressor gene
- May contain defects of p16,p53 and other tumor suppressor gene
- Associated with other neoplasms in the basal cell nsevus syndrome
- infiltrative(agressive)growth pattern
- SCC may rearly develop within OKC
Possible reasons recurrance of OKC
- Thin fragile linings,difficult to enucleate intact
- Finger like cyst extensions in to cancellous bone
- Satellite(daughter) cysts sometimes present in the wall
- More rapid proliferation of keratocyst epithelium
- Formation of additional cysts from other dental lamina remnants(pseudo recurrance)
- Inferior standered of surgical treatment
- possibly a neoplasm
Orthokeratinized Odontogenic(kerato) Cyst
- Less common than para keratinized type
- Lower proliferative activity
- No association between basal cell naevus syndrome
- Usually monolocular
Key features of Lateral periodontal cyst and varients
Lateral periodontal cyst
- Developmental cyst that form beside a vital tooth
- Usually seen ny chance in routine radiographs
- Resemble other odontogenic cysts radiographically,apart from position near the crest of the ridge
- Cause no symptoms but can erode through the bone to extend in to th gingiva
- Microscopically,the lining is squamous or cuboidal epithelium,frequently only one or two cells thick,sometimes with focal thickenings
- Some cells may have clear cytoplasm
- Respond to enucleation
- The relate tooth can be retained if healthy
- Also rare and with many features in common with botryoid odontogenic cysts
- Frequently multi locular
- Microscopically,pools of mucin and mucous cells present in the epithelium
- Has a strong tendancy to recur
- Should be consevatively excised
Non odontogenic cysts
Naso palatine duct cyst
- Arise from the epithelium of the nasopalatine duct in the incisive canal
- Epithelial ling is stratified squamous epithelium or ciliated columnar epithelium
- Mucos glands and neurovascular bundles often present in the wall
- Often asymptomatic,chance radiographic findings
- Form in a incisive canal region
- Arise from the vestiges of the naso palatine duct and may be lined by columnar respiratory epithelium
- The long sphenopalatine nerve and vessels may be present in the wall
- Can usually be recognized radiographically
- Histological examination necessary to exclude othe cyst types arising at the site
- Do not recur after enucleation
- Very common cyst forms outside the bone in the soft tissues,deep to the nso labial fold
- Probably arising from remnants of the nasolabial duct
- Occatonally bilateral
- Lining-Pseudostratified columnar epithelium
- Treatment-Simple excision
- May be complicate if the cyst has perforated the nasal mucosa and discharged in to the nose.
Para Dental Cyst
- Occationally resault from inflammation around partially erupted teeth.
- Particularly mandibular 3rd molars
- Affects males predominantly 20-25yrs
- Affected tooth is vital but show pericoronitis
- Resembles radicular cyst
- But more inflammatory infiltration in wall.
- Cyst of soft tissue
- Commnly occur sublingually
- Developmental abnormality or branchial arches/pharyngeal pouches
- Develop belween hyoid and jaw or many form immediatly beneththe tongue
- Filled with desquamated keratin(sometimes)giving a semisolid(salty) like consistancy.
- Have dermal appendages in the wall->give the name dermoid cyst
- Dermoid cyst is a form of cystic teratoma which is similar to structure of dermis
- Derived from embryonic germinal epithelium/acquired entrapted skin/mucosa
- Lined by stratified squamous epithelium and contain skin appendages such as sebaceous glands in CT wall
- Dermoid cysts in the head and neck region appearing symmetrical swellings in the floor of mouth
- There are presumed to derived by entrapment of epithelium remnents during closure of mandibular and hyoid branchial arches
- Sublingual type produce bulge in floor of mouth
- Submental type produce bulge in submental arch(dough-like on palpation)
- Small epidermoid cysts may also be found in the tongue,soft palate,buccal mucosa and lips where they are considered to be acquired lesions resaulting from traumatic implantation of surface epithelium
- Simple lesions without skin appandages are epidermoid cysts
Aneurysmal bone Cyst
- Intra osseous lesions consist of blood filled cavernous spaces
- occur in some frequently in jaws and molar areaof younger individuals is the commenest site.
- rapidly expanding lesion
- X-ray multilocular radiolucency
- Thin fibrous CT wall and consist of many blood filled cavernous spaces
- False type of cyst.non epithelialized
- Arising from branchial arch remnants
- it has also been called lymphoepithelial cyst suggesting it's origin from cystic transformation of epithelium entrapted in cervical lymphnodes
- BC originated from 2nd arch->lateral aspect of upper neck near anterior border of sernocledomastoid muscle or at the mandibular angle
- Lesion->circumscribed fluctuent mass
- Young adults no sexual prediction
- Small ones canbe found in the floor of the mouth,Clinically resembles mucous retention cysts
- lined by stratified squamous epithelium
- Occationally columnar or cuboidal
- Cyst wall is composed of lymphoid tissue with scattered germinal centre surrounded by CT.
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