Extra-oral Flashcards
1
Q
indication of OPG
A
- overall examination of mouth
- demonstrating the extensive caries or periodontal diseases
- eval the position of impacted teeth
- monitor growth and dental development
- assessing intraosseous pathology such as tumours, cysts or infection
- assess dentomaxillafacial trauma
- gross eval of TMJ
- comparison of pre and post implant changes
2
Q
principle of OPG
A
- side of patient’s dental arches closest to the receptor is recorded in focus
- side closest to the xray source is blurred out of focus
- xray beam focus on multiple points of the dental arch, aka focal trough
- xray beam is directed in a lingual to labial direction
- imaged from left to right
- resulting image is uniformly magnified due to the long object-receptor distance with some premolar contact overlapping
3
Q
position technique for OPG
A
- ensure that the MSP plane is vertical, frankfurt line is horizontal and canine line is on or slightly away from canine
- patient to put their tongue to the roof of mouth
4
Q
criteria of OPG image
A
- entire maxilla and TMJ recorded
- symmetrical display of the structures right to left
- slight smile or downward curve of the occlusal plane
- good representation of the teeth with minimal under or over magnification
- tongue in place against the palate with lips closed
- minimal or no cervical spine shadow visible
- overlapping of posterior teeth, particularly the premolars, is expected
5
Q
advantages and limitations of OPG
A
advantages:
- gross eval of the entire mouth
- almost pain free
- less traumatic than intra-oral imaging
- well-tolerated by most patients
- more soft tissue eval
- good for impacted tooth
- lesser radiation dose
limitations:
- difficulty in positioning patients who have short neck and wide shoulders
- limited when patient is wheelchair bound
- unsuitable for all patients
- long exposure times
- inability to pause and continue
- unable to wear neck thyroid shield
- unable to visualise fine details
- unreliable measurements due to image distortion
6
Q
indication of lat ceph
A
orthodontics
- initial diagnosis
- treatment planning
- evaluate growth
- monitor treatment progress
- assessment of treatment outcome
orthognathic surgery
- pre-op eval
- treatment planning
- post op assessment
7
Q
position technique of lat ceph
A
- sagittal plane of head vertical and frankfort plane horizontal
- ensure teeth in maximum intercuspation
- immobilise the head with the plastic ear rods inserted gradually into the EAM
- position the ruler at the level of glabella
8
Q
criteria of lat ceph
A
- entire maxilla and tmj recorded
- good representation with minimal under or over magnification
- soft tissue profile seen
- overlapping of mandible angles and EAMs
- visualisation of pituitary fossa and hard palate
- ruler at level of glabella
9
Q
rationale of special tmj view
A
- evaluation of osseous abnormality or infection
- trauma
- joint dysfunction
- disease progression
10
Q
rationale for special PA ceph skull view
A
- evaluation of osseous abnormality or infection
- trauma
- joint dysfunction
- surgical planning
11
Q
positioning for special PA ceph skull view
A
- similar to routined PA skull
- pt face the IR
- ear pegs to fit into EAM
- ensure frankfort line is perpendicular to the IR
12
Q
rationale for occlusal view
A
- used for locating roots and supernumerary, unerupted and impacted teeth
- localise FB in jaws and stones in the duct of sublingual and submandibular glands
- demonstrate and outline the integrity of maxillary sinuses
- aids for pt with small mouth width
- obtains info in extent of the injury for fractures to the maxilla and mandible
- determine and detect extent of pathologies
