Radiography Flashcards
Name 2 legislations governing radiation protection in medical practice
- Ionising Radiation Regulations (IRR)
2. Ionising Radiation Medical Exposure Regulations (IRMER)
Name 6 reasons for taking radiographs in orthodontics
- Assessing stage of dental development
- Presence of permanent, ectopic or supernumerary teeth
- Present of dental or or periodontal pathology
- Root morphology
- Assessment of skeletal relationships
- Monitor growth
Describe 2 reasons to radiograph deciduous dentition
- Following trauma to assess risk to underlying teeth
2. Determine prognosis of carious teeth
Describe 4 reasons to radiograph mixed dentition
- Asymmetric eruption of contralateral teeth ( >6 months)
- Failure of eruption of maxillary incisors
- Canines not palpable buccally by 10 years old
- Before carrying out interceptive treatment
Describe 3 reasons to radiograph permanent dentition
- Prior to definitive treatment planning
- Midway through treatment (assess treatment effects, root morphology and planned movement)
- Following active treatment (avoided unless indicated)
Name 5 radiographs commonly taken in orthodontics
- Orthopantomogram
- Occlusal
- Periapical
- Bitewing
- Cephalometric Lateral Skull
Describe an OPT
- Useful, relatively low-radiation dose, screening radiograph used to determine teeth, their position and pathological changes
- Useful in assessing TMJ changes
- Can be relatively unclear in labial segments due to shadowing
Outline 6 general steps of evaluating an OPT
- General overview of film
- Body of ramus of mandible
- Teeth
- Apical tissues
- Periodontal tissues
- Other structures
Describe how a general overview of an OPT is given
- Note the chronological and developmental age of patient
- Trace outline of all normal anatomical shadows and compare shape
Describe what to look for when assessing the body and ramus of mandible during an OPT evaluation
- Shape, outline, thickness of lower boarder
- Trabeculae
- Radiolucent or radiopaque areas
- Shape of condylar heads
Describe what to look for when assessing the teeth during an OPT evaluation
- Teeth present
- Stage of development
- Position
- Condition of crows
- Condition of roots
Describe what to look for when assessing the apical tissues during an OPT evaluation
- Integrity of lamina dura
- Radiolucencies or opacities associated with apices
Describe what to look for when assessing the periodontal tissues during an OPT evaluation
- Width of PDL
- Level an quantity of crestal bone
- Vertical or horizontal bone loss
- Any furcation involvement or calculus deposits
Name 3 other structures to view in an OPT evaluation
- Antra
- Nasal cavity
- Styloid processes
What does CBCT stand for?
Cone Beam Computer Tomography
Describe 5 uses of CBCT in dentistry
- Orthodontic treatment planning
- Dental implants
- Temporomandibular joints for osseous degenerative changes
- Evaluation of wisdom teeth v IDN
- Assessment of bony pathology
Describe 4 uses of occlusal radiographs
- Provides detailed view of root morphology in labial segments
- Can be used with additional views for parallax
- Useful assessing from and position of supernumerary teeth
- Assess extent of alveolar clefting
Describe 5 uses of periapical radiographs
- May be used assess localised pathology and root morphology
- Determine position of ectopic teeth via parallax
- Used to supplement views of anterior teeth on OPT
- Monitoring root resorption during treatment
- Assessing extent of alveolar clefting
What is the main use of bitewing radiographs?
Excellent views in assessing dental caries and bone levels in the buccal segments
Describe cephalometry
- A cephalometric radiograph is a standardised lateral skull radiograph
- Cephalometry is the measurement and analysis of these radiographs
Why is the standardisation of cephalometric radiographs important?
Allows comparison between images especially when monitoring growth or treatment progress
Describe the Cephalostat
- Maintains skull in a standardised relationship to X-ray fil and X-ray tube
- Mid-sagittal plane of skull usually 15 inches from film
- Mid-sagittal plane of skull usually 5 feet from tube
Describe a descriptive indication for cephalometric radiography
How does a patient compare with population means?
Describe 3 treatment planning indication for cephalometric radiography
- How much tooth movement is required?
- Does the underlying skeletal pattern restrict tooth movement?
- Can we achieve an aesthetic and stable result?
Describe 3 treatment monitoring indications for cephalometric radiography
- Is growth pattern unfavourable or favourable?
- Has growth stopped? (requires more than 1 film)
- What changes have occurred during treatment?
Describe 3 pieces of information from a cephalogram
- Relationship between maxilla and mandible to cranial base (vertically and AP)
- Relationship of teeth to jaws (inclination)
- Relationship of maxillary to mandibular teeth (overjet, overbite)
Describe cephalometric measurements
- Cephalograms are traced
- Identification points using standardised definitions
- Construction of lines or planes using points
- Measurement of angles between lines
Why are angles used in cephalometric measurements?
Reduces the effects of changes in absolute size during facial growth
What is S point in cephalometry?
Midpoint of sella turcica (pituitary fossa)
What is N point in cephalometry?
Most anterior point on frontal nasal suture
What is A point in cephalometry?
Deepest concavity anteriorly on maxillary alveolus
What is B point in cephalometry?
Deepest concavity anteriorly on mandibular symphysis
What is SN in cephalometry?
Joining point S to point N to give cranial base
Describe skeletal Class I relationship with regards to cephalometry and Eastman Analysis
- ANB 2-4 degrees
- Balances facial profile
Describe skeletal Class II relationship with regards to cephalometry and Eastman Analysis
- ANB > 4 degrees
- Profile shows relative mandibular retrusion
- May be result of mandibular deficiency / maxillary excess
Describe skeletal Class III relationship with regards to cephalometry and Eastman Analysis
- ANB < 2 degrees
- Profile shows relative mandibular prominence
- May be result of mandibular excess / maxillary deficiency
Describe incisor inclination to skeletal base
- Inclination as determined during clinical examination may be measured more accurately on ceph
- Useful in planning orthognathic cases and determining anchorage requirements
