normal and abnormal facial growth Flashcards
what does the facial growth of hard tissues involve?
bone
in what ways are facial bones laid down?
-endochondral ossification (bone laid within cartilage)
-intramembraneous ossification (bone laid within a membrane)
what can occur after bone is laid down?
bone remodelling- where bone is laid down and bone is resorbed to alter size and shape of individual bone
how do bones connect?
via sutures- peri-ossteous-fibrous joins (none movable)
what joint is the exception to a non-movable joints?
-TMJ
what bony structures of the face?
-calvarium (skull)
-cranial base
-naso-maxiallary complex
-mandible
what type of bone lay down occurs in the calvarium?
intramembraneous ossification
how many fontanelles are found in the calvarium and what are they for?
6- to allow compression of head during birth
where are fontanelles found?
where the sutures merge
when do fontanelles close?
-18 months
how do fontanelles close?
as brain grows-causes tension across sutures-and bone is deposited by intra-membraneous ossification
does remodelling occur in the calvarium?
yes- bone formation-external
bone resorbs internally
how is bone laid down in the cranial base?
-endochondreal ossification
what two areas of synchondroses occurs in the cranial base?
sphenoid-occipital- age 13
sphenoethmoidal- age 7
what does the nasomaxiallary complex include?
-maxilla
-nasal septum
-zygomatic bones
how does the nm complex grow?
by intramembraneous ossification at sutures
does bone remodelling occur in nm growth?
yes
as the cranial base grows how does the nm complex move?
move the nm complex forward and down
what type of bone growth occurs in the mandible?
-endochondreal ossification
do you get surface remodelling in the mandible?
yes- so the mandible can grow in a downward and forward position
when is facial growth completed in females?
16-17 years
when is facial growth completed in males?
17-19 years
what is involved in the facial growth of soft tissues? orofacial musculature
-lips
-tongue
-cheeks
-influences dental arches- teeth lie in position of equilibrium lingual/buccal/labial musculature due to forces from tongue cheek and lips
why do we have gum pads and no teeth at birth?
for suckling
at what age do deciduous teeth start to erupt?
-6 months
when is the deciduous dentition normally completed by?
age 3
when is root formation completed after the tooth erupts?
18 months after
when do deciduous teeth calcify?
in utero
when do deciduous teeth begin to exfoliate and when do they complete permanent eruption and what is the exception?
-6 years
-13 yrs
-except 8s
when is root formation of permanent teeth normally completed after eruption?
3 years after
permanent teeth are bigger then deciduous teeth, how is this facilitated?
-erupted into bigger arch
-decidious had spacing
-jaw growth
discuss the buccal width of dec and perm teeth and what is the purpose?
-dec teeth have wider buccal teeth
=leeway space
-allows space for canines and pre-molars to erupt
why is the leeway space in the lowers larger?
-allows 1st perm molars to erupt into class position- will be slightly further forward that the upper 1st molars
when do perm teeth finish erupting?
when they occlude with each other
what can late growth of the mandible cause in early 20s?
lower inscisor crowding
what is an abnormality of the calvarium (incomplete skull)
craniosynotosis
what is craniosynotosis?
premature fusion of the sutures of the calvarium- causing abnormal head shapes
what is a abnormality of the nm complex and pro-facial musculature?
cleft lip and palate
when does the lip form?
around 5-6 weeks in utero
how is the upper lip formed and alveolus ?
by maxillary processes
how does the palate form?
when the palatal shelves flip from vertical to horizontal and fuse- around 8 weeks in utero
what is the most common craniofacial birth defects?
CL and P
what’s more common in
CLP
CP
CL
males
females
males
what is more common unilateral or bilateral ?
unilateral- LHS more common
what causes CLP?
-genetic factors
-envirnomental factors- smoking, maternal age, alcohol
how is CLP classified?
LAHSHAL system
how are cleft lips diagnosed before birth?
ultrasound at 20 weeks- easier to diagnose CL than CP
what happens if CLP goes unnoticed after birth?
- will cause problems feeding- not enough food taken in by baby and will cause failure to thrive.
what are general problems that CLP cause?
-breathing
-feeding
-speech
-hearing
-bullying
-learning difficulties
what are dental problems that CLP can cause?
-facial appearance
-hypodontia
-supernumeraries
-hypoplastic teeth
-high caries rate
when are CL surgeries performed in UK?
-at 3 months
-as lip and nose are more developed
-anaesthesia risk reduced
when are CP surgeries performed in UK?
6-9 months
-to get better functioning muscles before speech starts to develop
what is the main dental problem with CLP?
-higher caries risk
what should be done due to higher caries risk of CLP?
PREVENTION
-OHI
-regular dental visits
-diet advice
-fluoride varnish
-fissure sealants
-duraphat
what other surgery may be required for CLP ?
-alveolar bone grafting
what are the reasons for alveolar bone grafts?
-facilitate tooth eruption
-support teeth
-provide stability to cleft segment
-close fistula
-reduce need for prosthetic teeth at cleft site
-improve aesthetics
when are bone grafts complete?
8-10 yrs
when do they take radiographs before grafts?
age 7
-when 1/2-2/3rds of canine roots are formed
what teeth are commonly missing in clp?
upper 2s - or very small in size
if upper 2s are present what may be done?
earlier bone graft to assist aligning upper 2s
why is pre-alveolar bone graft orthodontics performed?
use removable appliances to:
-improve surgical access
-reveal true extent of fistula
what else may orthodontists do pre-surgery?
improve access by:
-extract deciduous teeth at cleft site
-extract teeth with poor prognosis
-extract supernumerary teeth
-extract u2s if distal to cleft to allow room for canines
when are extractions carried out?
2 months before to allow tissues to heal before surgery
what does an alveolar bone graft involve?
take distant bone and adding it to the cleft site
what other orthodontic management may be necessary after surgery?
-fix alignment
-fix hypodontia-prosthetics
must always have retention to prevent relapse
what is Orthognathic surgery?
-to fix deficient maxillaries that arise after CLP surgery
-pt may have class III malocclusion
what are the risk of Orthognathic surgery?
-relapse due to splits of soft tissue-due to scarring
-compromise speech
what is an alternative to orthgnatic surgery?
distraction osteogenesis
what is distraction osteogenesis?
slow movement of skeletal pattern change- gradual stretching of soft tissues
what are the differences in outcomes of os and dog?
neither have been proved to have better outcome
how can feeding affect child?
communication between nasal and oral cavity- may require special bottle which ejects fluid
how can breathing affect child?
-babies breathe whilst feeding
-CLP often cause nasal obstructions
