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Maxillofacial Surgery
The Maxilla and Midface
Built from Facial Aesthetics — Concepts and Clinical Diagnosis
What’s inside
14 sections · 163 slides
Overview
- What this deck covers
Midface and maxilla
What the words mean and why the region matters
- 'Midface' and 'maxilla' are not the same word
- What the midface is built from
- Why the maxilla matters
- Where the word 'maxilla' comes from
- Word roots that keep coming back
- Three steps before you can correct a deformity
The vocabulary of jaw position
Words that must mean exactly one thing
- Too far forward: prognathic
- Too far back: retrognathic
- When a jaw only looks wrong: 'relative' terms
- Protrusion, retrusion and the dentoalveolus
- Protrusion is not proclination
- Vertical words and size words
- Hypoplasia and hyperplasia
How the maxilla moves
Three planes to slide in, three axes to spin around
- Bodily translation: sliding without turning
- Rotation around the three axes
- How the maxilla rotates around its three axes
- The three axes drawn on the upper jaw
- Roll: one side of the bite drops
- Pitch: front and back at different levels
- Yaw: the dental midline swings across
- The six degrees of freedom
- Where the idea came from
- The occlusal plane as a table top
Anatomy of the maxilla
A pyramid of thin bone around a large air space
- One 'maxilla', two bones
- The four surfaces of the body
- Landmarks on the front surface
- Bony landmarks of the maxilla from the front
- The four processes of the maxilla
- The bony palate: the roof of two rooms
- Why the palate is arched
- The maxilla seen from inside, front and below
Clinical evaluation
How to set the patient up, and what to look at
- Setting the patient up before you look
- The examination has three parts
- Upper midface and lower midface
- Hide the lower face to judge the middle of it
Sagittal soft tissue signs
Reading front-to-back maxillary position off the face
- White showing under the iris is a warning sign
- How far the eye should sit ahead of its rim
- Where the cheek starts and stops
- What holds the cheek up
- What ageing does to the cheek
- The submalar triangle: where hollowing shows
- Managing the hollow midface
- One curve that should never break
- A broken contour line before and after advancement
- What a break in the curve tells you
- Paranasal hollowing beside the nostrils
- The maxilla is the shelf the nose stands on
- A 2:1 ratio that shrinks when the maxilla is back
- What the upper lip is telling you
- Upper lip inclination against nasion-perpendicular
- Splitting the nasolabial angle in two
- What actually supports the upper lip
- A chairside test with a cotton wool roll
- The true vertical line through glabella
- The signs of midface retrusion
- Reading the retrusion checklist
Sagittal cephalometric measures
Putting numbers on where the maxilla sits
- An angle for the inferior orbital rim
- Maxilla against the anterior cranial base
- Maxilla against nasion-perpendicular
- Where the upper incisors should sit
- Maxillary base against the Frankfort plane
- Maxilla against mandible: the ANB angle
- Unit lengths: comparing jaw sizes
- How long the maxilla should be
Vertical evaluation
Face height, tooth show and the tilt of the bite
- Face height is about proportion, not millimetres
- How much tooth should show
- Incisor show at rest, posed smile and spontaneous smile
- Too much tooth at rest: two causes
- Telling those two causes apart
- A trap: posterior VME with normal tooth show
- The tilt of the maxillary plane
- When the bite plane tips front to back
- Four measurements that define the sagittal bite plane
- Parameter 1: how the maxillary plane is inclined
- Posterior midface height values
- Parameter 2: the sagittal maxillary occlusal curve
- Parameters 3 and 4: how far the teeth hang down
- Why these four numbers are worth the trouble
Transverse evaluation
Arch width, crossbites, midlines and cants
- Study casts are the transverse instrument
- Posterior crossbite: what it is
- Why a posterior crossbite happens
- Comparing a patient with arch width standards
- Dental arch width measurements (age 18) Data from Moyers et al.
- Measuring the bone, not just the teeth
- Palatal vault width in normal, dental and skeletal crossbite
- Reading the palatal vault on a cast
- Dental crossbite: normal vault, teeth tipped inwards
- Skeletal crossbite: narrow vault, teeth tipped outwards
- Widening a narrow upper arch
- Checking the upper dental midline
- Why upper midlines drift
- Correcting a deviated midline
- A cant across the bite: two roots
- Two ways the bite plane comes to be canted
- The dentoalveolar cant, step by step
- Measuring a transverse cant at the chairside
- Using the eyes as a reference - with a caveat
- What a skeletal cant looks like on imaging
- Levelling a canted maxilla
Maxillary deficiency
Too far back, too short, too narrow - often all three
- Deficiency is usually three-dimensional
- Scar tissue can hold the maxilla back
- Sagittal deficiency: what the face shows
- Sagittal deficiency: nose and lip signs
- The sinus wall gives the diagnosis away
- What the bite looks like
- Submental length separates the two Class III patterns
- One measurement that names the culprit jaw
- Vertical maxillary deficiency: the short face
- The short face pattern in a Class II patient
- Short face: bone and tooth show
- Short face: what the mandible does
- Short face: lips, mouth, nose and palate
- Short face: the bite
- Why transverse deficiency matters
- A wider part meets a narrower part
- Relative narrowing disappears when the casts are re-articulated
- Absolute narrowing stays whatever you do
- “
- Correcting sagittal deficiency
- Higher and wider: Le Fort II and III
- The Le Fort osteotomy levels
- Correcting vertical and transverse deficiency
- Correcting transverse deficiency
Maxillary excess
Too far forward, too long, too wide
- Excess can occur in any of the three planes
- Prominent under the nose, normal at the chin
- When the whole midface is forward
- Vertical maxillary excess: the long face
- Excess bone between nasal floor and tooth roots
- Three patterns of vertical excess
- Total vertical excess: gum showing front and back
- Posterior VME can hide behind a normal smile
- A gummy smile from overerupted incisors alone
- Long face: lip and tooth relationship
- Long face: what the mandible does
- Long face: angle and palate
- Anterior open bite and where it comes from
- Two open bites, two different curves
- A skeletal open bite and its curves
- When the teeth manage to compensate
- A soft tissue open bite
- A planning warning for soft tissue open bites
- Transverse excess and the spaced upper arch
- Planning the correction of excess
- Correcting sagittal excess
- Knowing when not to move the maxilla back
- Correcting vertical excess
- What decides how much impaction
Maxillary asymmetry
When the two halves no longer match
- What maxillary asymmetry means
- Three mechanisms of asymmetry
- They rarely come one at a time
- Bad records manufacture fake asymmetry
- What matters most in diagnosing asymmetry
- Getting the casts right
- Articulated casts revealing a canted bite plane
- Three-dimensional reconstructions
Pulling it together
The points worth carrying out of the room
- Takeaways: the words and the movements
- Takeaways: what to look at
- Takeaways: deficiency, excess, asymmetry
- References
- References (continued)
- References (continued)
- Facial Aesthetics: Concepts and Clinical Diagnosis, 2nd Edition