Intraoral Radiography Techniques Flashcards
What are 3 principles of radiation protection
JustificTion
Optimisation - x ray tube is more efficient and shorter exposure times. Rectangular Collimator is used
Limitation
How do you achieve the best quality images
- keep the film and object as close together as possible and parallel to the object
- film beyond the apices of the tooth
- the x eat sour se to the object distance as great as possible
- x ray beam perpendicular tot he object and the film
What are the 3 categories of intractable radiography
Bitweings
Occlusal
Periapical
What do bitewings show and what are their characteristics
Bitweings show crowns of premolars and molars of both jaws
- no/ minimal overlap of enamel (up to half thickness is acceptable)
- see from contact point between canine and first pre molar to the most distal contact point
- horizontal will show superfiakc bone levels of bone loss is more than 6mm
What are indications tk use Bitweings
Detecting approximately,occlusal m, or recurrent caries
Assessing depth of caries or monitoring their progression
Checking for overhangs or calculus deposit
Assessing superficial bone levels
What is the technique for bitewings (horizontal)
Use a logn axis of horizontal film and ask patient to bit block in the middle of the film
Hold it as close as possible and parallel to the teeth
Beam projects at right angles to the film horizontally and vertically
What is technique for vertical bitewings
The long axis of the film is vertical
Each film covers fewer teeth but shows more alveolar bone
Two each side to cover posterior teeth
What are the characteristics using film holders
Simple, film not displaces by tongue and then the beam always at right angles to the film
Less chance of cone cutting and reproducible techniques
Disadvantage is more expensive initially and may be uncomfortable
What is an alternative method to using film holders
Using adhesive tab technique
Cheap simple and good for small children
Not reproducible
Operator dependant
What do periapical technique show?
Include all the tooth and periapical tissues approximately 3mm beyond the apex
What are the indications to use a periapical techqniey
Apical pathology (osteitis,cysts,root resorption
Periodontal disease or endodontics
Root morphology before extraction or impacted teeth
Implant assessment or trauma
What is the technique for periapical technique
Film holder and beam aiming ring
- holds film parallel to the tooth
Aids correct alignment of beam with image detector
What film size and ring so anterior periapical a use
Film size 0
Blue bite ring
What film size and ring does posterior periapical use
Film size 2
Yellow bite block
What is places between bite block and opposing teeth
Cotton wool roll is places between the bite block and opposing teeth
What are th eadvanatheous of the paralleling technique
Confirms 3.36 of guidance
Reproducible radiographs
- geometric accuracy
-less foreshadowing
-less likelihood of distortion due to film bending
Less superimposition if zygomatic over maxillary molars
Localising ring minimises cone cutting
So fewer repeats and therefore lower dose
What are the disadvantages of paralleling technique
Expedience
Holders need to be sterilised
Careful and accurate placement required
Some patients find it uncomfortable
Longer to perform a full mouth survey as smaller films uses anteriorly
Bisecting angle technique could be sued
What is occlusal technique
Like bisecting angle periapical
Use larger film size and circular collimator
Film is held between teeth and is parallle to the occlusal plane
Maxillary: use alar tragus line
Mandibular: use corner of mouth to tragus
What are the indications of using occlusal x ray teycnique
Pathology not fully covered by periapical
Assess impacted teeth such as maxillary canines
Used in localisation in conjunction with other films
Trauma and bony expansion of mandible
Submandibular duct stones
Why is a maxillary true radiograph useless
Inclination of maxillary incisors does not allow a cross sectional view
Bones of face and skull are superimposed over it
What can be used to show the anterior teeth
Maxillary oblique occlusal
