Module 5 Flashcards
Intra Oral techniques - Bitewing:
Modern:
- holder with aiming ring
Original:
- Wing or tab
Taking a bitewing radiograph:
1) is it an adult or child?
The normal size is 31x41mm - small is 22 x 35mm
- film
- solid state sensor
- photostimulable phosphor plate
2) position patient
head supported with the occlusal plane horizontal
3) position film/holder
lingual sulcus
distal of lower canine to the mesial aspect of lower third molar
receptor and teeth as close as possible
4) patient to close teeth on bite platform
Beam angulation (BW):
- beam indicating device should be used
- centre this on receptor
- beam meets teeth and receptor at right angles (90 degrees)
- beam passes through all contact points
- beam aimed downward approximately 5-8 degrees
Choose settings (BW):
- think about cross infection
- patient preparation:
- Explain procedure
- Check ID
- Check radiographic views required
- Remove dentures, appliances etc
- expose:
- Patient in full view, ensuring they don’t move throughout the exposure
Advantages and Disadvantages for BW:
Advantages:
- Simple and straightforward
- Difficult for tongue to displace the receptor
- Beam aiming device determines angulation
- Cone cutting avoided
- Autoclavable/disposable holders
Disadvantages:
- Not 100% reproducible
- Uncomfortable for patients
- Expensive holders
Radiographic Features (Bw):
- Crowns
- Enamel
- Dentine
- Pulp chamber
- Coronal part of root
- Alveolar crests
- Lamina dura
- Periodontal ligament space
Additional features (Bw):
- Floor of antrum
- Carious cavity
- Calculus
- Unerupted/developing teeth
- Restorations
- Pulp stones
- Airspaces
Ideal Quality criteria (BW)
- no distortion or blurring
- no coning
- no overlap of approximal surfaces
- include mesial surface of first premolar to distal surface of second molar
- geometrically comparable to previous bitewing
- occlusal plane in the middle of the image
- buccal and lingual cusps superimposed
Ideal quality criteria - density and contrast (Bw)
Caries and restoration assessment:
- well exposed
- good contrast
- differentiation between enamel and dentine
- ADJ will be seen
Periodontal status
- under exposed
- avoid burn out
- vertical bitewing
Technique errors (Bw)
- Receptor positioned too far posterior =
no premolars - Receptor incorrectly placed =
displacement of receptor by tongue, distortion - Incorrect beam alignment in horizontal plane =
too far posterior or anterior - coned off
not aimed through contact areas - overlapping - Incorrect beam alignment in vertical plane =
no superimposition of buccal and lingual cusps - incorrect exposure settings =
overexposed - burn out - poor contrast - dark image
underexposed - poor contrast - pale image - movement of patient or BID
blurring
Quality assessment - technique (Bw)
assess the following:
- Are all required teeth shown?
- Are the crowns of upper and lower teeth shown?
- Are the contact areas overlapped?
- Are the buccal and lingual cusps superimposed?
- Has there been any cone cutting?
- Is the occlusal plane horizontal?
- Is it geometrically comparable to previous films?
Quality - exposure factors (Bw)
- Is the image too dark?
- Is the image too pale?
- is the amelodentinal junction apparent?
- what effect has exposure had on the structures shown?
- is any cervical burn-out noticeable?
Periapical Radiography (PA)
Includes:
Paralleling or bisecting angle techniques
Coverage 2-4 teeth
Individual teeth:
- apical areas
- detailed view of tooth and alveolar bones
Clinical indication (PA)
- Apical infection/inflammation
- Assess periodontal status
- After trauma - check teeth and bone
- Presence and position of unerupted teeth
- Root morphology prior to extraction
- Endodontic progression
- Evaluate apical cysts or other alveolar bone lesions
- Post operative evaluation of implants
Geometric requirements (PA)
- Tooth and film in contact or as close as possible
- Tooth and film packet parallel
- Beam meets tooth film at right angles, beam should be at right angles in both planes (horizontal and vertical)
Paralleling technique (PA) practical technique
- Receptor positioned in holder, placed with the long axis
- vertical for incisors and canines
- horizontal for molars and premolars - Ensure enough film beyond the apex to record the tissue in this area
- Holder needs to be positioned so that the tooth to be x-rayed is touch bite block, may need to use a cotton wool roll
- Patient to bite together
- Locate ring should be just touching the patients face
- Align the spacer cone with the ring
- Ensure patient is still and make the exposure
- This should be a reproducible position
Image positioning variations (PA)
Maxillary incisors and canines =
-Accommodate height of palate
-Posterior position
Mandibular incisors and canines =
-In floor of mouth
-In line with lower canines or premolars
Maxillary premolars and molars =
-In midline
-Accommodate height
Mandibular premolars and molars
-Lingual sulcus
-Next to appropriate teethPatient care(PA)
- Justification
- Patient identification
- Explain procedure
- Remove appliance/dentures
- Set exposure parameters
- Patient positioning
- Head support
- Occlusal plane horizontal
- Check required view
- Position receptor
- Align beam
- Make exposure
Cross infection control =
- PPE
- Barriers
- surfaces
- receptors
- Disinfection
- Hand washing
- Clinical waste
Radiographic features of the MAXILLA
CENTRAL INCISORS:
- shadow of top of nose
- trabecular bone pattern
- lamina dura
- median suture
- gingival soft tissue
- periodontal ligament space
- pulp canal
- restorations if present
CANINES:
- trabecular bone pattern
- lamina dura
- periodontal ligament space
- pulp canal
- overlapping crowns
- superimposed roots of first premolars
- restorations if present
PREMOLARS:
- trabecular bone pattern
- lamina dura
- periodontal ligament space
- intercrestal bone
- pulp canal
- restorations if present
- floor of antrum
- maxillary antrum
MOLARS:
- trabecular bone pattern
- lamina dura
- periodontal ligament space
- intercrestal bone
- pulp canal
- restorations if present
- floor of antrum
- maxillary antrum
- zygoma
- unerupted 3rd molar
Radiographic features of the MANDIBLE
INCISORS:
- enamel
- periodontal ligament space
- upper margin of the lower lip
- lamina dura
- trabecular bone pattern
CANINES:
- enamel
- pulp canals
- periodontal ligament space
- orientation dot
- lamina dura
- bone pattern
- burn out
PREMOLARS:
- lamina dura
- bone pattern
- pulp canals
- mental foramen
MOLARS:
- interdental bone
- varying bone patterns
- inferior dental canal
- developing third molar
Ideal quality criteria(PA):
- no distortion or blurring
- include correct anatomical area with apices and 3-4mm of surrounding bone
- no overlap of approximal surfaces
- no coning off
- geometrically comparable with previous periapical images
DENSITY AND CONTRAST:
caries, restorations, periapical assessment:
- well exposed
- good contrast
- differentiation between enamel and dentine
- differentiation between periodontal ligament space
periodontal status:
- under exposed
- avoid burn out
Preparation, positioning and technique errors: (PA)
Dentures and appliances not removed - superimpositions Incorrect position of receptor - not over the area of interest - no apicies or periapical tissues - bending - distortion Incorrect orientation - no image (back to front) Poor alignment of BID - horizontal - cone cutting, overlapping contact areas - vertical - cone cut, foreshortening, elongation Poor communication - movement, blurring Incorrect settings - poor contrast Double exposure - receptor used twice
Considerations for PA:
- children and disabled
- anatomical difficulties
- neurological difficulties
- radiographic investigations appropriate to the limitations
- appropriate film size
- modify technique
- assistance
- under GA
- avoid OPG
- paralleling technique preferred
Positioning when doing Bisected angle technique:
PATIENT:
- seated
- head supported
- occlusal plane parallel to floor
- bite gently or slight support with thumb or index finger
IMAGE RECEPTOR:
- orientate
- as close to tooth as possible
- do not bend
- tube head placed dependent on tooth for investigation
- assess vertical angle
- beam 90° to bisected angle
- horizontal angle through interproximal areas
Vertical angulation (PA):
Maxilla - downwards angulation: INCISORS - 45° to bridge of nose CANINES - 50° PREMOLARS - 40° MOLARS - 30°
Mandible - upwards angulation: INCISORS - 25° CANINES - 20° PREMOLARS - 15° MOLARS - 5°
ADVANTAGES - Bisected angle technique:
- comfortable positioning for patient
- positioning is relatively simple and quick
- dependent on correct angulation, image is same length as tooth
- adequate for most diagnostic purposes
DISADVANTAGES - Bisected angle technique:
- distortion due to many variables
- elongation/ foreshortening - vertical angulation wrong
- periodontal bone levels not seen
- zygomatic shadow overlies roots of upper teeth
- skill required for angulation assessment
- not reproducible
- cone cutting
- roots and crowns overlap - horizontal angulation wrong
- distortion of crowns common
- foreshortened buccal roots of maxillary posterior teeth
EXPOSURE FAULTS (PA):
Elongation - Angulation to shallow, long image
Foreshortening - Angulation too steep, short image
Coning - Angulation not central to film, partial exposure
Blurred image - Movement of patient or collimator
Transparent film - Film inserted the wrong way round
Fogged film - Exposure to light before x-ray beam
Blank film - Machine not switched on
Occlusal radiography:
Maxillary occlusal projections
- upper standard occlusal (standard occlusal)
- upper oblique occlusal (oblique occlusal)
- vertex occlusal
Mandibular occlusal projections
- lower 90° occlusal (true occlusal)
- lower 45° occlusal (standard occlusal)
- lower oblique occlusal (oblique occlusal)
Upper standard occlusal
ANTERIOR OF MAXILLA
Clinical indication:
- presence of unerupted canines, supernumeraries, odontomes
- Position of unerupted canines
- Lesion evaluation
- Anterior teeth and alveolar bone fractures
PATIENT •Seated •Occlusal plane horizontal •Head supported •Bites together gently
IMAGE RECEPTOR •Flat in mouth •On occlusal surfaces of lower teeth •Orientated •Centrally •Long axis crossways (adult) •Antero-posteriorly (child)
TUBEHEAD: • Above patient • In midline • Downwards through bridge of nose • 65° - 70° to film packet
Upper oblique occlusal:
POSTERIOR OF MAXILLA AND UPPER POSTERIOR TEETH ON ONE SIDE
clinical indications:
- lesion evaluation - cysts tumors etc
- antral floor assessment including the position of displaced roots
- posterior teeth and alveolar bone fracture
PATIENT •Seated •Occlusal plane horizontal •Head supported •Bites together gently
IMAGE RECEPTOR •Flat in mouth •On occlusal surfaces of lower teeth •Orientated •Long axis Antero-posteriorly •on side of investigation
TUBEHEAD:
• side of patients face
• Downwards through cheek 65° - 70° to film
• centred to region of interest
LOWER 90° OCCLUSAL:
TOOTH BEARING PORTION OF THE FLOOR OF THE MOUTH
CLINICAL INDICATIONS:
- presence and position of calculi in salivary ducts
- position of unerupted teeth
- lesion evaluation
- horizontal plane assessment of fracture of body of the mandible
PATIENT:
- head tipped back
- head supported
- bites together gently
IMAGE RECEPTOR:
- orientate so that it is centrally placed
- onto occlusal surfaces of lower teeth
- long axis cross ways
TUBEHEAD:
- circular collimator
- below chin
- in midline
- centred to interproximal of the first and second molars
LOWER 45° OCCLUSAL:
ANTERIOR OF MANDIBLE AND ANTERIOR TEETH
clinical indications:
- periapical assessment if patients are unable to tolerate periapical radiography
- lesion evaluation
- vertical plane assessment of fractures
PATIENT:
- head supported with the occlusal plane horizonal
- bites gently together on the film
IMAGE RECEPTOR:
- orientate
- centrally in mouth
- to occlusal surfaces of lower teeth
- long axis antero-posteriorly
TUBEHEAD:
- in midline
- centered through chin point - 45° to film
LOWER OBLIQUE OCCLUSAL:
UNILATERAL VIEW OF MANDIBLE AND/OR SUBMANDIBULAR SALIVARY GLAND
clinical indications:
- detect calculi in submandibular salivary gland
- position of unerupted third molars
- lesion evaluation, posterior of body of mandible
PATIENT:
- head supported, facing away
- chin raised
- bite together gently
IMAGE RECEPTOR:
- orientate to the side of the investigation
- place on the occlusal surfaces of lower teeth
- long axis anterior posterior
TUBEHEAD:
- using a circular collimator
- position it upwards and forwards, below and behind the angle of the mandible - parallel to lingual surface
EXTRA ORAL RADIOGRAPH - oblique lateral:
Radiographs of the head and jaw
TRUE LATERAL:
Sagittal plane and film parallel
X-ray beam perpendicular to both
Taken using a cephlostat unit
OBLIQUE LATERAL:
Film and sagittal plane not parallel
X-ray beam perpendicular to film
Differing projections possible
CLINICAL INDICATIONS FOR OBLIQUE LATERAL:
- Assessment of unerupted teeth
- Detect fractures of the mandible
- Evaluate lesions, cysts etc
- Alternative to intra oral view if patient unable to open mouth or cannot tolerate intra oral radiographs
- Specific views of anatomy required i.e. salivary glands
EQUIPMENT FOR OBLIQUE LATERA:
- Standard dental x-ray set
- Extra oral cassette containing film and intensifying screens or digital phosphor plate - 13 x 18cm in size
Positioning - OBLIQUE LATERAL:
CASSETTE:
- held by patient over the area of interest
PATIENT:
- seated/upright with head rotated to the side of interest
- raise chin this increases the triangular space between the back of the ramus and the cervical spine through which the x-ray beam will pass (radiographic keyhole)
TUBEHEAD:
- opposite side to film
- behind ramus through radiographic keyhole
- beneath lower border of the mandible
BIMOLAR TECHNIQUE
- same radiograph used twice
- right and left side of jaws
- lead screen to protect film not being exposed
- turn patient and film around
- lead screen used to shield part of film already exposed
- make second exposure
DENTAL PANORAMIC TOMOGRAPHY (DPT) - image production:
- narrow beam rotational tomography
- 2 centers of rotation
- focal trough
- 3 dimensional
- image created in sections which are built up during rotations
Equipment (DPT):
- tube head
- cassete and carriage assembly
- positioning apparatus
Taking a DPT:
• Patient considerations
• Ensure correct identification
• Procedure explained to the patient giving reassurance regarding
the equipment
Selection Criteria for DPT:
- Orthodontic assessment
- Assessment of bony lesions or unerupted teeth
- Prior to hospital admission
- Periodontal assessment
- Assessment of third molars
- Fracture of the mandible
- Antral disease
- TMJ assessment
- Implant planning
Preparation (DPT)
- Cassette or phosphor plate inserted
- Collimate field
- Select exposure settings – 70 – 100kV; 4 – 12 mA
- Place bite peg – barrier cover
Patient Considerations (DPT)
• Confirm the patient's identity • Check their current medical history • Confirm the radiographic request • Explain the procedure • Reassure the patient • Remove spectacles, dentures, orthodontic appliances and any metal objects
Positioning of the Patient (DPT)
- Ensure they have a straight spine and to hold the supports
- Bite edge-edge on bite peg
- Immobilise their head using temple supports
- Use light markers to indicate
- Vertical mid sagittal plane,
- Frankfort plane horizontal
- Canine light between upper lateral incisor and canine
- Ask them to close their lips and keep their tongue to roof of the mouth
- Tell them not to move throughout the exposure
Anatomy Markers
- Mid sagittal plane
- Frankfort plane
- Canine light
Panoramic Anatomy
- Real or actual shadows
- Air shadows
- Ghost or artefactual shadows
Additional points (DPT)
- Not an alternative for intra oral techniques
- Less operator technique required
- Technique sensitive
- Digital improves resolution
Occlusal Radiographs
Intra oral technique with image receptor (5.7 x 7.6 cm) placed in the occlusal
plane, at present there are no suitable sized solid-state digital sensors
Maxillary Occlusal Projections
Upper Standard Occlusal
Upper Oblique Occlusal
Vertex Occlusal - no longer used
Mandibular Occlusal Projections
Lower 90° occlusal Lower 45° occlusal Lower oblique occlusal
Clinical Indications (occlusal rads)
• Evaluate size and extent of lesions in anterior maxilla
• Assessment of anterior periapical regions where periapical
techniques cannot be tolerated
• Detection of unerupted canines, supernumeraries and
odontomes for orthodontic assessment
• Dento-alveolar trauma to anterior maxilla
Technique (occlusal)
• Patient seated, head supported, horizontal occlusal plane
• Image receptor inserted with long axis cross ways for adults
• Antero-posteriorly for children
• Patient gently bites together
• Tube head positioned in the midline above the patient,
downwards angle of 65° - 70° to image receptor
• Periapical film for small children, place flat in occlusal plane,
tube head at 50°
Upper Oblique Occlusal
Clinical indications
• Evaluate size and extent of lesions in posterior maxilla
• Assessment of posterior regions where periapical techniques cannot
be tolerated
• Antral floor assessment
• Cleft palate assessment
• To assess fractures of posterior teeth or alveolar bone
Technique (Upper Oblique Occlusal)
• Patient seated, head supported, horizontal occlusal plane
• Use protective thyroid shield
• Image receptor inserted with long axis antero posteriorly to side of
mouth under investigation
• Patient gently bites together
• Tube head positioned to the side of the patient, downwards angle of
65° - 70°to image receptor through the cheek
Lower 90°/ True Occlusal
Clinical indications
• Detection of calculi in submandibular duct
• Assessment of mandible affected by lesions causing bucco -
lingual expansion
• Torus mandibularus assessment
• Assessment of unerupted tooth position, bucco – lingual
• Assessment of fractures for horizontal displacement
• Implant assessment
Technique
• Image receptor centrally placed – crossways or antero- posteriorly
• Patient gently bites together
• Head tilted backwards as far as comfortable
• Tube head placed in midline below the patient’s chin 90° to image
receptor
• Tube head placed below body of mandible on side of investigation 90°
to image receptor
Lower 45° Occlusal
Clinical indications
• Assess dento-alveolar trauma (in conjunction with periapicals)
• Assess anterior mandible for lesions – size and extent
• Alternative for patients who cannot tolerate periapicals
• Assess mandibular fractures for vertical displacement
Technique
• Patient seated with head supported and with the occlusal plane
horizontal and parallel to the floor
• Image receptor facing downwards centrally placed onto the occlusal
surfaces of the lower teeth with the long axis Antero-posteriorly
• Patient gently bites together
• Tube head placed in midline below the patient’s chin 45° to image
receptor
• Tube head placed below body of mandible on side of investigation 90° to
image receptor
Lower Oblique Occlusal
Lower Oblique Occlusal
Clinical indications
• Detection of calculi in sub mandibular salivary gland
• Assessment of the bucco lingual position of unerupted lower wisdom
teeth
• Evaluation of the extent and expansion of cysts etc in the posterior part
of the body and angle of the mandible
Technique
• Patient seated with head supported and rotated away from the side of
investigation
• Image receptor facing downwards centrally placed onto the occlusal
surfaces of the lower teeth with the long axis antero posteriorly
• Patient gently bites together
• Tube head is aimed upwards and forwards from below and behind the
angle of the mandible and parallel to the lingual surfaces of the mandible
Cephalometric Radiography
Clinical Indications Orthodontic Treatment • Initial diagnosis – skeletal/soft tissue abnormalities • Treatment planning • Treatment progression • Appraisal of treatment Orthognathic Surgery
- Preoperative evaluation
- Treatment planning
- Postoperative appraisal
Equipment
Cephalostat:
• Head positioning and stabilising apparatus
• Anti scatter grid
• Cassette holder
Cassette -usually 18 x 24 cm
• Aluminium wedge filter – attenuates the x-ray beam selectively in the
region of the soft tissues to enable the soft tissue profile to be seen on the final radiograph
Beam Characteristics • Fixed position • Sufficiently penetrating • Parallel • Collimated
True Cephalometric Lateral Skull
- Sagittal plane of head vertical
- Frankfort plane horizontal
- Teeth in full occlusion
- Immobilise the head
- Film parallel to sagittal plane
- Beam perpendicular to film
- Position aluminum wedge
Cephalometric Postero-Antero of the Jaws
- Rotate head stabilising apparatus 90°
- Position patient head tipped forward
- Radiographic baseline horizontal and perpendicular to film
- Forehead to nose position
- Immobilise the head
- Beam horizontal, central ray through cervical spine
Cephalometric Points
- Sella S
- Orbitale r
- Nasion N
- Anterior nasal spine ANS
- Subspinale or Ponit A
- Prosthion Pr
- Infradentale Id
- Supramentale or point B
- Pognion Pog
- Gnathion Gn
- Menton Me
- Gonion Go
- Posterior nasal spine PNS
- Articulare Ar
- Porion Po
Planes and Angles:
- Frankfort plane
- Mandibular plane
- Maxillary plane
- SN plane
- SNA
- SNB
- ANB
- Maxillary incisal inclination
- Mandibular incisal inclination
