Radiology

Question 1

where does the frankfort line run from

Answer 1

from superior border of external auditory meatus to inferior orbital

Question 2

where does orbitomeatal line run from

Answer 2

centre of external auditory meatus to outer canthus of eye

Question 3

what is the difference between anteroposterior and posteroanterior

Answer 3

anteroposterior - the tube is anterior to the patient with the receptor behind them
posteroanterior - the tube is posterior to the patient and the receptor is infront of them

Question 4

why is PA always used in external imaging for the face

Answer 4

the structure we want to see are at the front. PA reduces magnification and reduces dose

Question 5

what should be included in a radiographic report

Answer 5

the type of film
grade - acceptable or not
teeth and structures present
if restorations not already charted note these - RCT - condensed, to length
bone levels
periradicular changes - location, size, margins
caries

Question 6

what are differential diagnosis in the radiological seive?

Answer 6

normal
developmental
traumatic
inflammatory
cystic
neoplastic
osteodystrophy
metabolic/systemic
idiopathic
iatrogenic
foreign body
artefact

Question 7

when explaining radiolucencies, what should be included in the description

Answer 7

size
shape
location
margins - well defined, corticated
aetiology
affect on other structures - displacement, expansion, resorption

Question 8

what are some clinical indications for CBCT

Answer 8

orthognathic surgery
unerupted teeth
implant planning
pathology - cysts, malignancy
cleft palate
dental abnormalities

Question 9

what are kinds of odontogenic cysts

Answer 9

radicular cyst, dentigerous cyst, orthokeratocyst

Question 10

what are signs and symptoms of cysts

Answer 10

can be asymptomatic, increase in size, swelling, TTP on teeth, mobility of teeth, drifting of teeth, loss of vitality and change in colour of teeth

Question 11

what should be included when describing a cyst on radiograph

Answer 11

location, shape, margins - well defined, corticated, locular - uni-locular or multi, teeth involved, effecting any anatomy

Question 12

where does a radicular cyst develop from

Answer 12

periapical granuloma due to pulpal necrosis, stimulates rest cells of malassez to proliferate, forms epithelial lining around fluid and allows it to grow in size, corticated margins of cyst is continuous with lamina dura

Question 13

what is the difference between periapical granuloma and a radicular cyst

Answer 13

size - radicular cyst is more than 15mm, if the tooth has been RCT and the granuloma doesnt reduce - then it is a cyst

Question 14

what is a cyst

Answer 14

pathological cavity or sac, containing fluid, semi-fluid or gas, may or may not be epithelial lined

Question 15

what is the difference between a radicular cyst and a residual cyst

Answer 15

radicular cyst is when the cause is still present, residual cyst is when the cause has been removed (RCT or XLA) but the cyst persists

Question 16

what is a dentigerous cyst and where does it come from

Answer 16

cystic change of a dental follicle in unerupted teeth, been there for too long. Develops from reduced enamel epithelium. can be seen extending from ACJ of unerupted tooth

Question 17

how do you decide if a dentigerous cysts is a cyst or a follicle

Answer 17

measure from cusp to follicle. If less than 4mm - follicle. More than 4mm, consider cyst, if more than 10mm assume cyst

Question 18

what is the histology of a dentigerous cyst

Answer 18

thin layer of non-keratinised stratified squamous epithelium, coming from reduced enamel epithelium

Question 19

what is the difference between an eruption cyst and a dentigerous cyst

Answer 19

an eruption cyst is in soft tissue and develops from rest of serres, appears blueish in colour, tooth will erupt through it

Question 20

what is an odontogenic keratocyst

Answer 20

developmental cyst developing from dental lamina, not one particular tooth

Question 21

what is characteristic of a OK

Answer 21

multi-locular or pseudolocular - rarely one big balloon
scalloped margins giving view of pseudolocular
expansion through medullary bone - mesio-distal direction, cannot expand through cortical bone
displacement of adjacent teeth but unlikely to cause root resorption (more in ameloblastoma)

Question 22

what is a pre-surgical diagnostic test done with cyst aspirate for an OK

Answer 22

contains squames and low soluble protein content

Question 23

what is seen histologically with an OK and what impact does this have on surgery

Answer 23

very thin parakeratinised lining
lining is very friable, if teared during surgery, likely to leave daughter cells and allows for recurrence

Question 24

how does basal cell naevus syndrome present

Answer 24

multiple odontogenic keratocysts
multiple basal cell carcinomas
clacification of the intra cranial dura mater

Question 25

name 2 non-odontogenic cysts

Answer 25

naso-palatine duct cyst and solitary cyst

Question 26

where is the naso-palatine duct cyst and what can it be confused with

Answer 26

anterior between central incisors, can appear heart shaped due to nasal spine. can be confused with incisive follicle. if less than 6mm - follicle. 6-10mm - monitor, larger than 10 - assume cyst

Question 27

what is a solitary cyst

Answer 27

non-odontigenic developmental cyst, non-epithelial lined, normally asymptomatic, incidental finding, normally just monitor and it resolves on its own

Question 28

how might cystic material be obtained for tests

Answer 28

aspirate - if suspect fluid
incisional biopsy - remove part of the cystic lining, can be done with marsipulisation
excisional biopsy - remove cyst and send for testing

Question 29

what are treatment options for cysts

Answer 29

enucleation - complete removal of cyst
marsipulisation - create opening of cyst into oral cavity and allow for slow drainage

Question 30

what are the benefits are risks of enucleation

Answer 30

benefits - complete removal of cyst in one surgery, less follow up required, whole lining can be examined
risks - if large cyst - risk of fracture, large surgery requiring GA - is patient well enough for this, risk of recurrence if not all removed, damage to adjacent structures, if dentigerous cyst - loss of tooth

Question 31

when would marsipulisation be indicated and what is the risk of it

Answer 31

indications - large cyst which would leave the mandible at risk of fracture, elderly patient, dentigerous cyst where patient wants to retain tooth, cyst is close to important structures e.g. ID canal
risks - a lot of follow up required for pack change etc, risk of the window closing and the cyst re-growing