Post-natal Facial Growth and Development Flashcards
How does a neonatal face differ from an adult face?
- Face is small compared to the cranium
- Eyes are large and ears are low set
- Forehead is upright and bulbous
- Face appears broad
- Nasal region is vertically shallow, with nasal floor close to the inferior orbital rim
- In adults, the midface expands and the nasal floor descends
Identify and explain the three locations where facial growth occurs.
- At sutures or periosteal lined contact areas between the flat bones of the cranial vault, and between the bones of the maxilla and cranium
- In cartilage - synchondroses between the bones forming the base of the skull; in the secondary cartilage of the mandibular condyle and in the cartilage of the nasal septum
- By surface deposition over the surfaces of the cranial and facial bones, beneath the covering periosteum
Describe the growth process of the cranial vault, including timelines and mechanisms.
- Expansion in response to the growing brain (until 6-7 years)
- Growth occurs at sutures
- Shape modified by surface resorption/deposition
- After neural growth ceases, forehead continues to expand due to enlarging of air sinuses (pneumatisation)
Explain the timeline and significance of cranial base growth at synchondroses.
Lateral growth of the cranial base is completed by 3 years old
The sphenoethmoidal synchondrosis fuses at about 6-7 years of age
After sphenoethmoidal synchondrosis fusion, the anterior cranial base is relatively stable and is used as a baseline for further measurements of facial growth
Growth ceases at the spheno-occipital synchondrosis between 12-15 years of age
Complete fusion of spheno-occipital synchondrosis occurs by 20 years
What are the direction, mechanisms, and processes of maxillary growth?
- Grows downward and forward
- Displaced by growth of nasal cartilage and cranial base
- Growth occurs at sutures between maxilla and skull
- Surface deposition mainly posteriorly
- Surface resorption anteriorly and inferiorly
Describe the direction, location, and surface changes during mandibular growth.
- Tends to grow downwards and forwards
- Growth occurs at condylar cartilage
- Surface resorption occurs anteriorly and lingually
- Surface deposition occurs posteriorly and laterally
What methods are used to predict the adolescent growth spurt?
Chronological age
Secondary sexual characteristics (menarche or voice changes)
Hand-wrist radiographs
Cervical Vertebral Maturation (CVM
Describe the Cervical Vertebral Maturation (CVM) stages and their clinical significance.
- CS1 or CS2: Growth approaching – wait
- CS3: Peak growth in 1 year – start treatment with functional appliance
- CS4: Peak growth past
- CS5 and CS6: Peak growth ended
What are growth rotations and how do they affect facial appearance?
Important feature of facial growth
Forward rotations lead to ‘short face’
Downward and backward rotations lead to ‘long face’
What mechanisms contribute to dentoalveolar compensation and what is its significance?
- Tooth eruption
- Soft tissue forces
- Occlusal forces
- Mesial drift
These factors can all result in teeth tipping towards each other if skeletal discrepancy is severe
How can growth patterns contribute to worsening of malocclusion?
Adverse growth effects:
Downwards and backwards growth pattern can lead to worsening of malocclusion (as shown in case example in the lecture)
Describe the characteristics and patterns of adult facial growth.
Very variable
Continues slowly throughout life
Tendency to increased overall length and prominence of nose and chin (and forehead in men)
Summarize the key patterns and timeframes of post natal facial growth
In general, facial growth is downward and forward, but there is considerable individual variation with growth rotations
Growth slows after 16-17 years in girls and 18-20 in boys but continues throughout adulthood
The face gets ‘flatter’ and longer with aging
What methods are used to measure facial growth changes?
Casts of the face
Cephalometry
3D laser scanning
3D photogrammetry
What is lateral cephalometry and what are its uses?
- Standardized lateral radiographs of the face and base of skull
- Reproducible - patient positioned in a cephalostat a set distance from the cone and the film
- Cephalometry is the analysis and interpretation of these radiographs
- First step is to look for pathology
What are the key technical considerations for proper cephalometric radiography?
Fixed distances
ALARA (As Low As Reasonably Achievable) principle
Aluminum soft tissue filter
Thyroid collar
Triangular collimation
NHP (Natural Head Position)
Rare earth screen LANEX screen
Fastest film possible (60-70kV)
What aspects are analyzed in cephalometric assessment?
Relationship between jaws and cranial base
Relationship between the jaws
Position of teeth relative to the jaws
Soft tissue profile
What are the components of cephalometric analysis?
Identify:
Points/landmarks with precise definitions
Lines
Measure:
Lengths
Heights
Angles
Name and identify the key reference points used in cephalometric analysis.
Sella
Nasion
A Point
B Point
Anterior Nasal Spine
Posterior Nasal Spine
Pogonion
Menton
Gonion
Porion
Orbitale
Basion
What are the primary reference lines used in cephalometric analysis?
Sella-nasion
Frankfort plane
Maxillary plane
Occlusal line
Mandibular plane
A-Po line
What measurements and relationships does the Eastman Analysis evaluate?
Anteroposterior position of maxilla and mandible relative to base of skull (SNA, SNB)
Position of mandible relative to maxilla:
ANB (anteroposterior)
MMPA or FMPA (vertical)
Angulation of teeth to maxilla or mandible:
UIMxP (Upper incisor to maxillary plane)
LIMnP (Lower incisor to mandibular plane)
hat are the ANB values for different skeletal classifications?
< -3°: Class III (severe)
-3 to 0°: Class III (moderate)
0 to 2°: Class III (mild)
2 to 4°: Class I
4 to 6°: Class II (mild)
6 to 8°: Class II (moderate)
8°: Class II (severe)
What are the MMPA values for different vertical facial patterns?
< 17°: Decreased
17 to 22°: Decreased
22 to 27°: Decreased
27°: Average
27 to 32°: Increased
32 to 37°: Increased
37°: Increased
What are the normal values for incisor inclination in the Eastman Analysis?
Ui/MxP (Upper incisor to maxillary plane): 109° ± 6°
Li/MnP (Lower incisor to mandibular plane): 93° ± 6°
Ui/Li (Upper incisor to lower incisor): 135° ± 10°
What are the clinical applications of cephalometric radiographs?
Gross inspection (anatomy/pathology)
Assess dentoskeletal relationships
Assess soft tissues relationship to underlying hard tissues
Prognosis and treatment planning
Monitoring facial growth
Predict future growth (CVM)
Assess changes due to treatment and growth
In what clinical situations is a cephalometric radiograph indicated?
To aid diagnosis:
Skeletal class II or III (marked AP discrepancy)
Vertical discrepancy
Class III malocclusion
Pretreatment record:
Upper and lower fixed appliances
Monitoring progress:
Upper and lower fixed appliances
Functional appliances
Research project
What are the limitations and potential sources of error in cephalometric analysis?
Radiographic projection errors:
Magnification
Distortion
Errors within the measuring system:
Non-linear fields
Errors in landmark identification:
Quality of image
Landmark definition and location
Operator and registration procedure
Explain the mechanisms of facial skeletal growth through displacement and deposition/resorption.
Growth pattern of the face is such that it grows ‘out from under the cranium’
The maxilla and mandible are displaced forward and downward relative to the cranial base
As they are displaced, bone fills in at the maxillary sutures and the mandibular condyles to maintain the relationship with the cranial base
Concurrently, bone is resorbed from the anterior surface of the maxilla, mandibular body and ramus
