Intraoral radiograph techniques Flashcards
Name the 3 different types of intraoral radiographs
- Bitewings
- Periapicals
- Occlusal
What are the 3 principles of radiation protection?
- Justification
- Optimisation
- Limitation
What type of collimator do we use for a majority of intra oral radiographs?
Rectangular radiographs
Which type of x ray tube is the most efficient?
DC x rays tubes are most efficient and allow for shorter exposure time
What part of the mouth can bitewings show?
shows the crowns of premolars and molars of both jaws with no or minimal overlap of the enamel
What should we be able to see between the canine and first molar?
The contact point between the canine and first premolar to the most distal contact point
What will a horizontal bitewing show?
Will show superficial bone levels if bone loss is less than 6mm
What can bitewings indicate?
- Detection of approximal caries
- Detection of occlusal caries
- Detection of recurrent caries
- Assess depth of caries
- Monitor caries progression
- Check for overhangs
- Check for calculus deposits
- Assess superficial bone levels
How do we take a bitewing radiograph?
- Use firm holder with beam aligning device
- Long axis of film horizontal
- Use size 2 fit, for adults and size 1 or 0 for children
- Bite block. in the middle of the film
- Make sure the film is held as close to the teeth as possible
- Beam pporijects at right angle to the film
What are vertical bitewings?
They are bitewings there the long axis of the film. os vertical
How many vertical bitewings do you usually need to cover the posterior teeth?
2
What are the advantages of using a film holder
- Simple
- Film not displaced by tongue
- Beam always right angles to film
- Less chance of coning off
- More chances of being reproducible.
What are the disadvantages of using a film holder
- May be more expensive initially
2, May be uncomfortable
What is the adhesive tab technique?
The original technique use to take bitewings
It uses a sticky tab attache to the middle of the film
Who is the adhesive tab technique useful for?
useful for children who can’t cope with larger film holders in their mouths.
What are the advantages of the adhesive tab technique?
- Cheap
- Simple
3 .Good for small children
What are the disadvantages of the adhesive tab technique?
- Not reproducible
- More change of coning off
- Operator dependent
What do Periapical radiographs aim to show in the mouth?
- All of tooth (crown and root)
2. Periapical tissues (approximately 3 mm beyond the apex)
How can we achieve the best quality image when taking a periodical radiograph?
- Film and object as close together as possible
- Keep the Film parallel to object
- Keep the film beyond the apices
- Keep the ray source to object distance as great as possible
- Keep the Xray beam perpendicular to the object and the film
What can a periapical radiograph indicate?
1. Apical pathology – e.g. rarefying osteitis, cysts, root resorption 2. Periodontal disease 3. Endodontics 4. Root morphology 5. Impacted teeth 6. Post trauma
Describe the periapical paralleling technique
- Film is held parallel to tooth by the use of film holders
- Due to anatomical constraints the film hasto be a distance from the tooth in most areas of the mouth (other than lower molars)
The fact that the film has to be a distance form the tooth means what?
It causes magnification so it is very important that the e source to object distance is increased
What is the optimum object to source distance when taking a periapical radiograph
optimum is 30cm
What film size should we use when taking a periapical radiograph?
0 or 1 anteriorly
2 posteriorly
How is cotton wool used when taking a periapical radiographs?
Cotton wool roll is placed between bite block and OPPOSING teeth NOT the tooth being x-rayed
What are some of the advantages of the paralleling technique when taking periapical radiographs?
- Geometric accuracy with minimal magnification
- Sharper images made
- Anatomical accuracy of the alveolar crest
- Less superimposition of zygoma over roots of maxillary molars
- Less foreshortening or elongation
6 Approximal caries well shown - More accurate image of relationship of restoration to tooth surface
- Patient’s head can be in any position
- Reproducible radiographs possible
- Less likelihood of distortion due to film bending
- Lower dose to thyroid, gonads, no dose to finger
What are some of the disadvantages of the paralleling technique when taking periapicalradiographs?
- Expensive in first instance due to purchase of film holders and 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 used anteriorly.
Name the 2 techniques we can use to take a periapical radiograph?
- paralleling technique
2. Bisecting angle technique
What foes the bisecting angle technique rely on?
Relies on film being as close to tooth as possible
Where should the film be places according to the bisecting angle technique?
Crown edge touching film and root diverging away
This is so the X-ray beam is perpendicular to a line which bisects the angle between the long axis of tooth and film
What must patients have in order to have a bisecting angle technique periapical radiograph?
Patient must have relevant occlusal plane parallel to floor
When taking a radiograph of the maxillary occlusal plane using the bisecting angle technique what line should we place the x ray at?
Alar-tragus line
When taking a radiograph of the mandibular occlusal plane using the isecting angle technique what line should we place the x ray at?
Corner of mouth to tragus
When taking a periapical radiograph using the bisecting angle technique who holds the film?
Film holders can be used but more common for patient to hold film in place with finger
What film should we use when taking a periapical radiograph using the bisecting angle technique?
Use the largest periapical film anteriorly to reduce risk of cone cutting.
What are some of the advantages of the bisecting angle technique when taking periapical radiographs?
- Cheap
- Quick
- More comfortable for patient
- Occasionally can be a useful adaptation of the paralleling
technique if you can’t get a very long root onto the film
What are some of the disadvantages of the bisecting angle technique when taking periapical radiographs?
- Difficult to assess line of bisection
- There can be foreshortening/elongation
- Finger irradiated if holding film in place
- Patient must have occlusal plane parallel to floor
- Beam angles have to be remembered
- Bone levels not accurate
- Zygoma superimposed over roots of maxillary molars
- Increased likelihood of cone cutting
- Not reproducible
- Thyroid more likely to be irradiated
How can we optimise our radiographs when executing the paralleling technique?
Paralleling technique using film holders with beam aligning devices This Reduces chances of non diagnostic films
What do we use to take an occlusal radiograph?
- Uses a larger film size
2. Use circular collimator
Where do we place the film when taking an occlusal radiograph?
Film held between the teeth, parallel to occlusal plane
– Raised dot/sensitive surface of the receptor towards the arch being imaged
What can occlusal radiographs indicate?
- Pathology not fully covered by periapical
- Assesses impacted teeth such as maxillary canines
- Used in localisation in conjunction with other films (parallax principle)
- Can indicate trauma especially in children
- Bony expansion of mandible
- Submandibular duct stones
What does “true” mean in terms of radiographs?
When the X-ray beam is perpendicular to the film from all directions
What does “oblique” mean in terms of radiographs?
When the X-ray beam is angled to the film in an angle other than a right angle from at least one direction
What are the different types of occlusal radiographs?
- Maxillary oblique occlusals
- Mandibular True Occlusal
- Lower Anterior Occlusal
- Lower Oblique Occlusal
Where is the maxillary oblique occlusal taken from?
- The midline
Common angulation is 60-70 degrees through tip of nose.
What is a maxillary oblique occlusal sometimes referred to as?
- upper standard occlusal,
- anterior oblique (AO)
- maxillary midline
Why is a maxillary true image virtually useless?
Theres an inclination of the maxillary incisors which doesn’t allow for a cross sectional view
Theres also an unclear view of the incisors
Is a maxillary vertex radiograph a “true” occlusal radiograph?
NO as the Beam angle is more than 90° to film
Where does a maxillary vertex radiograph project through?
Projects down through the vertex of skull along long axis of incisors, resulting in cross sectional view
Does a maxillary vertex give a clear image of the teeth?
Does not give a detailed image, teeth look like “a string of pearls”
Why does a maxillary vertex give a clear image of the teeth?
The X-ray beam is angled towards the abdomen
What is a mandibular True Occlusal also known as?
A lower 90 degree occlusal
How is the x ray beam positioned in relation to the film when taking a mandibular True Occlusal?
X-ray beam is 90o to the film
This will achieve a cross sectional view
Where is a mandibular true occlusal taken from?
Can be taken from the midline or to one side or the other
What can a mandibular true occlusal radiograph indicate?
- Detection of calculus in the submandibular ducts
- Can Assess the bucco-lingual position of unerupted mandibular teeth
- Can evaluate the bucco-lingual expansion of body of mandible lesions
- Can asses fracture displacement of the anterior mandible
- Can asses the mandibular width for implants
What can a Lower Anterior Occlusal indicate?
- Periapical assessment of lower incisors in patients unable to tolerate film holders
- Can evaluate larger lesions in the anterior mandible
To what angle is the beam angulated at in when taking a Lower Anterior Occlusal?
45 degrees
What can a Lower Oblique Occlusal indicate?
- Radiopaque calculi in the
submandibular gland - Assessment of bucco-lingual position of unerupted lower third molars
- Evaluation of bucco-lingual expansion of lesions in posterior mandible.
Where is the x ray tube aimed when taking a lower oblique occlusal?
X-ray tube aimed upwards and forwards from below and behind the angle of the mandible.
What do we need to localise when taking an X-ray?
Often need to localise impacted teeth or foreign bodies
What does the SLOB rule say about localisation of X rays?
Same lingual opposite buccal
If you want to take an assessment for caries which type of x ray would be recommended?
A bitewing
