Orthodontic Radiography Flashcards
Why might you choose to take an OPT?
State of development- presence or absence of permanent teeth
- make sure to palpate for them first.
Presence and position of ectopic or supernumerary teeth
State of development in individual teeth
Morphology of unerupted teeth
State of the alveolar bone
Pathology- caries, PA pathology, state of restorations.
Oral surgery indications
What makes a radiograph justified in orthodontics?
Benefit to the patient from the diagnostic information should outweigh the detriment of the exposure.
Record in the notes why the radiograph was taken, report on the radiographic findings.
Why is the focal trough relevant when taking a radiograph of someone with a severe malocclusion?
If the patient cannot bite edge to edge on the bite block in the OPT machine, then some teeth or structures may be outwith the focal trough and look blurry on the radiograph or not visible at all.
How would certain malocclusions look on an OPT if parts of the teeth are outwith the focal trough?
Class II div 1- majority of the lower incisors will be outwith the focal trough
Class II div 2- some of the root of the lower incisors will be outwith the focal trough
Class III- Part of the upper root will be outwith the focal trough.
Why might we request a standard upper occlusal radiograph?
Look for pathology in the upper anterior region of the maxilla
To confirm the presence of unerupted teeth
Root resorption
To aid localisation of unerupted teeth in combination with another radiographic view (parallax).
What radiographs might you want to request if you were looking for the orientation of an unerupted canine?
OPT and AOM- vertical parallax
Two PA views- horizontal parallax
What are the indications for taking a lateral ceph?
To aid diagnosis- vertical discrepancy
Treatment planning
- help clarify the tooth movements to be achieved
- orthographic planning
Progress monitoring
- fixed appliance treatment, functional appliance treatment.
- monitoring facial growth
What are the advantages of a lateral ceph?
Standardised- lateral radiographs of the face and base of the skull.
Reproducible- patient positioned in a cephalostat a set distance from the cone and the film.
What is the patient positioning for a lateral ceph?
Patient should be in RCP and Frankfurt plane parallel to the floor.
Head kept steady using the ear rods and making contact with soft tissues of nasion.
What type of analysis is used for lateral cephalograms?
Eastman analysis
What aspects of the lateral cephalogram are you looking to analyse?
Relationship of the maxilla and mandible to the anterior cranial base.
Relationship of the maxilla to the mandible.
Position of teeth relative to the jaws.
Soft tissue profile.
When do we use CBCT in orthodontics?
Localisation of wisdom teeth if we need more information on their proximity to adjacent teeth and the possibility of resorption.
Get a better view of structural anomalies
Some orthographic cases
Some cleft palate cases
Why do we not routinely do CBCT?
Radiation dose is higher than plane film radiography.
Set up time is longer and patient needs to stay still for longer.
Reporting for CBCT needs to be done by someone with additional training
Cost
