Intro to Dental Radiography Flashcards
Radiology request card
Must be completed comprehensively and completely, otherwise no images will be taken and your px will be returned to clinic
Imaging requests
An imaging request form is completed by referrer
Must include:
1. Px identification label on both sides of document
2. Details of clinic and its consultant e.g. RD2/ Dr Dentist
3. Date
4. Clear and precise indication of images required
5. Clinical justification for those images
6. Clinicians signature
Any omissions and images will not be taken; px will be returned to clinic for appropriate corrections to be made
Extra-oral images
Dental Panoramic Tomograph (DPT, OPT, OPG)
Lateral & Postero-anterior (PA) Cephalometry
PA Mandible
Oblique Lateral Mandible
Occipitomental (OM) 10 and 30 degrees
Intra-oral images
Periapicals - paralleling and bisecting angle techniques
Bitewings
Maxillary occlusals
Mandibular occlusals
Which nerve goes through mandibular foramen
Inferior alveolar nerve
Positioning requirements
Px’s dental arch must be positioned accurately within zone of sharpness called ‘focal trough’
Series of positioning light beams enable operator to achieve this
Positioning technique
Have px remove jewellery, hair ornaments and intra-oral appliances containing metal in order that they do not cause artefactual images
Have pxs approach x-ray unit and hold hand grips for stability
Present bite block and ask them to bite in upper and lower grooves to place teeth in edge to edge occlusion
Activate positioning lights
Encourage px to press shoulders and chest forward to minimise image of cervical spine
Request they ‘suck bite block’ to press tongue into palate thus eliminating air over dorsum of tongue
Finally remind them to keep still for duration of exposure; approx 15-20s
Positioning lights
Sagittal light: coincides with px’s midline to ensure no tilt
Frankfort Plane light: demonstrates line connecting infra-orbital margin with upper notch of tragus of ear to ensure hard palate is horizontal
Image layer/ focal trough light: assessed for its position relative to upper 3, appropriate selection made on unit controls thus ensuring dental arch is in focal trough
Forming DPT image
DPT is not captured in its entirety as with other images
Image built up oover exposure period of up to 18s
Different part of px imaged at different stages in cycle
Paralleling periapicals
Taken using either film or photostimulable phosphor plates, in various sizes (image receptors)
-x-ray unit + image receptor holders with beam aiming arm and locator ring
Image receptor must be parallel with tooth/ teeth
Made possible by using paralleling device
Once exposed receptor is placed in appropriately sized cassette and introduced into image plate reader
Advantages of paralleling technique
Accurate image; no elongation, foreshortening overlapping or cone cut
Little superimposition of other anatomical structures
Images are reproducible
Disadvantages of paralleling technique
Quite uncomfortable to px, often stimulating gag reflex
Holders need to be sterilized or disposable
Elongation and foreshortening
If vertical angle of central beam too steep = foreshortened
If vertical angle of central beam too shallow = elongated
(bisecting angle periapical technique)
Maxillary canine
Image receptor is held in place by thumb or index finger of opposite hand
Central x-ray beam directed perpendicular to bisecting line in both horizontal and vertical planes and centred to receptor
(bisecting angle periapical technique)
Maxillary premolar
Receptor held in place, long axis horizontally, lower border 2mm beyond and parallel with occlusal surface of premolars
Centre x-ray beam to receptor, perpendicularly in vertical and horizontal planes
(bisecting angle periapical technique)
Advantages of bisecting technique (not used)
More comfortable for px
Quicker than having to assemble holders
Disadvantages of bisecting technique (not used)
Image often distorted, elongation, overlap etc., due to many variables
Superimposition of zygomatic buttress is problematic in imaging upper posterior molars
Bone levels are not clearly demonstrated
Not reproducible
Bitewings
Demonstrates interproximal spaces of teeth in upper and lower arch on one image
Using another type of beam aiming device
Bite platform is central to receptor holder so an equal proportion of upper and lower teeth are demonstrated
Receptor should be placed carefully into sulcus with mesial and distal border equidistant from lingual surface of premolars and molars
-avoids overlapping of crowns and therefore demonstrates interproximal spaces clearly on resulting image
Alignment of central beam (bitewing)
Important in all imagine but particularly in horizontal plane when taking bitewings; misalignment results in overlapping and inability to detect caries
Maxillary occlusal
To demonstrate anterior maxillary region - possibly unerupted canines
Mandibular 45 degrees occlusal
To demonstrate lower apical region, cysts, tumours or fracture displacement of anterior mandible in vertical plane
Mandibular 90 degrees occlusal
To detect presence of radiopaque calculi in floor of mouth
To assess bucco-lingual position of unerupted dentition
Evaluate bucco-lingual expansion caused by tumours or lesions in body of mandible
Assessment of fracture displacement in horizontal plane
Mandibular posterior oblique occlusal
To detect radiopaque calculi in submandibular salivary gland
Assess bucco-lingual position of unerupted lower third molars
Evaluate extent of bucco-lingual expansion of cysts, tumours and other bony lesions in body and angle of mandible
