ORTHO cephalometrics Flashcards
in ortho when do we take radiographs?
confirm unerupted teeth
locate unerupted teeth
pathology
root morphology
assess skeletal pattern
monitor treatment changes
what is cephalometrics?
the analysis and interpretation of standardised radiographs of the facial bones
when is cephalometric analysis used?
skeletal discrepancies
incisor relationships
functional appliances
incisor change
research (with ethical approval)
name the parts of a cephalostat?
scale
ear rods
nose piece
film
aluminium wedge
where does the scale sit when using the cephalostat?
mid-sagittal plane
what position should pt be in when using cephalostat?
frankfort plane horizontal to the floor
teeth in RCP
What outlines are drawn in hand drawn cephalometrics?
soft tissue profile
cranial base
nasal bones
maxilla and teeth
mandible and teeth
trace an average of both eyes
what are the landmarks on a ceph?
sella
nasion
ANS/ PNS
A point + B point
gonion
menton
where is the nasion (N)?
the most anterior point of the fronto-nasal suture in the median plane
where is the sella (S)?
the point representing the midpoint of the pituitary fossa (sella turcica)
where is point A on a ceph? and what does it represent?
point at the deepest midline concavity of the anterior maxilla
represents the anterior limit of the maxilla
can point A change in a person?
yes - with growth and tooth movement
because it is on alveolar bone
where is the anterior nasal spine (ANS)?
the tip of the bony anterior nasal spine in the medial plane
where is the posterior nasal spine (PNS)?
tip of the posterior nasal spine
what can obscure the posterior nasal spine (PNS)?
developing upper 8s
where is point B?
deepest concavity on the mandibular symphysis
can point B change?
yes - with growth and tooth movement
because it is on alveolar bone
where is the pogonion (pog)?
the most anterior point of the mandibular symphysis
where is the menton (Me)?
the most inferior point on the mandibular symphysis
where is the gonion (Go)?
the constructed point of intersection of the tangents of the ramus plane and the mandibular plane
the most posterior and inferior point on the angle of the mandible
what dots make the cranial base?
S-N
what dots make the maxilla?
ANS - PNS
what dots make the mandible?
Go-Me
what are the lines on a ceph?
S-N (cranial base)
N-A + N-B
ANS - PNS (maxilla)
Go- Me (mandible)
upper incisor
lower incisor
what does the SNA angle indicate?
the relative antero-posterior positioning of maxilla in relation to cranial base
what does an increased SNA angle indicate? and what angle would this be?
prognathic maxilla (forward)
>82 degrees
what does a decreased SNA angle indicate? and what angle would this be?
retrognathic maxilla (backwards)
<82 degrees
what does the SNB angle indicate?
antero-posterior positioning of the mandible in relation to cranial base
what does an increased SNB angle indicate? and what angle would this be?
prognathic mandible
>80 degrees
what does a decreased SNB angle indicate? and what angle would this be?
retrognathic mandible
<80 degrees
what does the ANB angle denote?
the relative position of the maxilla and mandible to each other
what does an increased ANB angle indicate? and what angle would this be?
class II skeletal pattern
> 4 degrees
what does a decreased or negative ANB angle indicate?
class III skeletal pattern
what forms the MMPA (maxillo mandibular plane angle)?
intersection of mandibular plane with maxillary plane
what does an increased MMPA angle indicate?
vertical growth pattern
what does a reduced MMPA plane angle indicate?
horizontal growth pattern
what does an increased incisor inclination angle indicate?
proclined incisors
what does a decreased incisor inclination indicate?
retroclined incisors
what is the E plane?
Ricketts esthetic plane
line joins soft tissue chin and nose tip
what are E plane measurements in a balanced face?
lower lip = 1-2mm
upper lip = 2-3mm
what type of digital software is available for digital cephalometric tracing?
dolphin imaging software
OPAL image viewer
PACS - graphic tools
