Radiolucencies Part 1

Question 1

List the Bone/Radiographic Description

Answer 1

-New (Number)
-Students (Size)
-See (Shape)
-Part (Periphery)
-Description (Density)
-Loving (Location)
-Education (Effect)

Question 2

Periapical Granuloma/Cyst

Answer 2

-Inflammation in the pulp leading to involvement of the periapical tissues
-Most common odontogenic cyst
-Acute cases are painful; chronic cases are asymptomatic
-Acute exacerbation of a chronic lesion can cause an abscess with or without swelling

Question 3

How does a Periapical Cyst/Granuloma appear radiographically?

Answer 3

-Round to ovoid radiolucency at the apex of a non-vital tooth
-Typically cause loss of lamina dura and can cause root resorption
-Most are <1.5cm in diameter
-Can’t distinguish by size or radiographic appearance (granuloma vs. cyst)
-Less commonly between teeth (lateral radicular cyst)

Question 4

Describe the histology of a Periapical Cyst/Granuloma

Answer 4

-Acute/chronic inflammation and granulation tissue (capillaries and immature fibroblasts)
1. WITH a variably thick, non-keratinized stratified squamous epithelial lining –> periapical cyst
2. W/O an epithelial lining –> periapical granuloma

**Note: NO granulomatous inflammation

Question 5

Describe the tx for a periapical cyst/granuloma

Answer 5

-Enucleation, with either extraction or endodontic therapy of the involved tooth
-If the lesion is not removed, a residual periapical cyst may result
-Recurrence is unlikely

Question 6

PA cyst/granuloma - when to worry?

Answer 6

1. Multilocular- not odontogenic infection
2. Significant root resorption or movement of teeth- increases chances that could be something else (perform tooth vitality test - if vital, start thinking it may be something else)
3. Does not respond to tx radiographically or clinically- think either inadequate tx or different diagnosis

Question 7

Parulis

Answer 7

-Yellowish/red nodule of granulation tissue representing an intraoral point of drainage for a sinus tract related to necrotic tooth
-Typically facial gingiva/alveolar mucosa apical or near tooth of origin (exceptions: palatal bone, mx lateral incisors, lingual plate, md 2nd and 3rd molars)
-Asymptomatic lesions are often patent and pus can be expressed from the center of the lesion

Question 8

List the Developmental Cysts

Answer 8

-Dentigerous cyst/Hyperplastic dental follicle
-Eruption cyst
-Lateral periodontal cyst
-Odontogenic keratocyst
-Nasopalatine duct cyst
-Simple bone cyst (not a true cyst but mimics)

Question 9

Describe the background of cysts

Answer 9

-Cyst: Abnormal sac or cavity lined by epithelium which is enclosed in CT
-Enlargement comes from fluid accumulation inside
-Developmental (may be inside bone (intraosseous) or soft tissue (extraosseous))
1. odontogenic
2. nonodontogenic (happens at planes of fusion)
-Inflammatory (periapical cyst, residual cyst)

Question 10

Where do odontogenic cysts/tumors come from?

Answer 10

-Dental lamina rests (rests of Serres): due to initial invagination of tooth formation
-Rests of Malassez: due to root development
-Reduced enamel epithelium: due to crown development

**All due to epithelial/CT fragments

Question 11

Dentigerous Cyst

Answer 11

-By definition, a cyst that forms around the crown of an impacted tooth (pericoronal)
-Second most common odontogenic cyst
-This is a developmental (as opposed to inflammatory) cyst
-Arises from reduced enamel epithelium; shows a thin, non-keratinized stratified squamous epithelium
- >3-4mm pericoronal radiolucency, smaller lesions are virtually identical to a hyperplasstic dental follicle (lack a true epithelial lining)
-Tx: enucleation of squamous lining and fibrous wall
-Prognosis is excellent - minimal tendency to recur
-Tissues should be submitted for microscopic examination to exclude other possible diagnoses

Question 12

When is it NOT a dentigerous cyst?

Answer 12

-Not around the crown
-Multilocular
-Any sign or opacity: this changes the differential completely!

Question 13

When is it less likely to be a dentigerous cyst?

Answer 13

-Impacted tooth other than 3rd molar or canine
-Larger lesions

Question 14

Dentigerous Cyst Diff Dx (mimics)

Answer 14

-Odontogenic keratocyst- most common
-Unicystic ameloblastoma- infrequent
-Odontogenic myxoma- uncommon
-Central giant cell granuloma- anterior of the first molar (don’t expect in the posterior mandible/ramus)

Question 15

Eruption Cyst

Answer 15

-Essentially represents a dentigerous cyst that forms in the soft tissue overlying the crown of an erupting tooth
-Usually somewhat translucent swelling but may be bluish b/c of blood accumulation
-Children generally affected
-Take a radiograph to confirm
-Tx: usually ruptures spontaneously or can excise the roof to allow the tooth to erupt

Question 16

Lateral Periodontal Cyst

Answer 16

-Derived from dental lamina rests
-Middle aged adults
-Asymptomatic - adjacent teeth are vital
-Usually unilocular radiolucency; can look multilocular (grape-like - called botryoid odontogenic cyst)
-Canine/premolar region, moat often mandibular
- <1cm
-Excision is curative

Question 17

Gingival Cyst of the Adult

Answer 17

-Identical to the lateral periodontal cyst but occurs with gingival soft tissues, not within bone
-Bluish to translucent/clear swelling, often centered in attached gingiva (can mimic a mucocele but there are no salivary glands on the gingiva)
-Excision is curative
-Parulis can also mimic this (but a parulis will most liekly be associated with a non-vital tooth)

Question 18

Nasopalatine Duct Cyst

Answer 18

-Also known as incisive canal cyst
-Located within the incisive canal (in bone) which often causes a palatal swelling over the foramen
-Radiolucency between apices of #8-9 in middle-aged adult
-Vital teeth
-Tx: surgical removal. Rare recurrence

Question 19

Odontogenic Keratocyst

Answer 19

-Benign but locally aggressive developmental odontogenic cyst
-Probably arises from dental lamina rests
-Affects a wide range
-Most commonly seen in the posterior mandible, but any segment of the jaws can be affected - clinically may mimic a wide variety of jaw cysts
-Often asymptomatic or causes swelling when large
-Unilocular radiolucency when small. Multilocular appearance often develops as the lesion enlarges

Question 20

Odontogenic Keratocyst Histology

Answer 20

-Uniform, thin stratified squamous epithelial lining
-Luminal parakeratin production
-Palisaded (“picket fence”) appearance of the basal cell nuclei
-Features altered with inflammation
-Satellite cyst formation may be seen

Question 21

Odontogenic Keratocyst Tx and Recurrence

Answer 21

-Some controversy as to best tx:
1. Small lesions: excision with curettage
2. Large lesions: resection, marsupialization followed by surgical excision of residual cystic epithelium
- 33% recurrence rate overall; larger lesions are more likely to recur
-With occurrence in the first decade, or with multiple OKC’s, nevoid basal cell carcinoma syndrome (Gorlin syndrome) should be ruled out

Question 22

Nevoid Basal Cell Carcinoma Syndrome (Gorlin Syndrome)

Answer 22

-Autosomal dominant condition
-OKCs of the jaws are a characteristic finding in these patients
-These often arise at an early age and may be multiple
-Cutaneous features:
1. basal cell carcinomas, early onset
2. palmar/plantar pitting
-Skeletal features:
1. calcified falx cerebri
2. increased cranial circumference
3. bifid ribs
-Tx/Management: sun screens; excision of basal cell carcinomas as needed; monitor for and excise OKCs; genetic counseling

Question 23

Simple Bone Cyst

Answer 23

-Also known as “traumatic bone cyst” though trauma isn’t present in most cases - theory
-Young patients (age 10-20)
-In jaws, mandible only - molar/premolar region
-Painless, expansion/swelling in up to 25% of cases
-Teeth are vital!

Question 24

Simple Bone Cyst - radiographs, diagnosis, tx

Answer 24

-Radiographs: Well-defined radiolucency that “scallops” between adjacent roots
-Diagnosis: Biopsy - no cyst lining, just a hole in the bone
-Tx: Scrape (curettage) inside of bony cavity to promote bleeding and regeneration of bone
-Follow-up radiographs to confirm bone fill