Ortho Flashcards
How does cleft palate happen
Failure of fusion of the palatal shelves
What are 4 genetic aetiolgies that can lead to the formation of a CLP
Syndromes; CP 50% will have a cardiac abnormality due to neural crest migration.
Family history ; if your first child has CLP 5% likely your next child will
Sex ratio
Laterality ; more common on the left than the right
The smoking ban has reduced the number of babies born with CLP by what
10%
The lip of a child with CLP is closed at around three to six months - why isnt the palate also closed at this time. When is it closed
This is because children are primary nasal breathers until they are 6 months
So the surgery is done between 6-12 months
Want it down by 12 months as this is when the baby will start to make sound
What are the three compulsory surgeries in CLP
Lip closure
Palate closure
Bone graft
There are 5 main dental implications for a child with CLP - what ar they
Missing teeth
Impacted teeth
Crowding - Relaspe rate is high , constricted upper arch and are likely to have descidious teeth extracted leading to crowding
Growth - they have a 20% tendency to be a class 3
Caries ; cannot bone graft to a child when they have caries and this can be a big issue in this group
- teeth come through hypoplastic and this makes them diffuckt to clean
How do we clinically assess for an impacted canine
Palpate - buccaly and palatal
Check for mobility of the C
Look at the angle of the lateral incisor - often is the canine is palatal it may tip the lateral distally - it may also have resorbed the root so check mobility
What interceptive method can be used to help with impacted canines
Early removal of teh Cs at the age of 10
This only works in palatal canines are as often the C is obstructing the eruption pathway
When do we used a closed or an open exposure in impacted canines
If the canine is buccal
Needs to be a closed exposure and gold chain - the gold chain has to come down through the alveolar ridge to allow eruption onto the correct keratinised mucosa
Teeth will not erupt onto the non keratinised buccal mucosa as it doesnt have the proper cellular mechanism
If palatal placed
Open exposure and coal pack sutured in for 10 days
The palate is keratinsed so the canine can erupt
When there is an unerupted tooth what two things do we look at
Symmetry and sequence of eruption
What is the most common cause of an unerupted maxillary central
Super numerary - most commonly a tuberculate
Not including the 8s what are the most common teeth affected by hypodontia
L5
U2
U5
What is normal incisor width
6-7mm
What is the minimum amount of space we need to root apex for an implant
7mm
What is intramembranous ossification
Bone deposited directly into primitive mesenchymal tissue
What is endochondral ossification
Bones are preceeded by a hyaline cartilage matrix
The mandible and the maxilla form adjacent to pre-existing cartilaginous structures what are these
Mandible - mecjels cartilage
Maxilla - primary skeleton of the upper face
How does cleft lip happen
Failure of fusion of maxillary prominence and medial nasal prominence
What is interceptive ortho A
Any procedure that will reduce or eliminate the severity of a malocclusion
If there is no 5 present and we are deciding to maintain an E why do we need to build it up into occlusion
Because if we don’t the 6 will drift and try and tip mesially over the top of it and the 4 will tip distally over the top and the occlsuion will become worse
How do fixed appliances move teeth
They move teeth in a 3D way through bodily movement
What is the order of movement with fixed appliances
1st in and out
2nd tipping and tilting
3rd torque
In fixed appliances what kind of wire is use for initial alingment and why n
Nickel titanium
Light continuous force
Flexible
Shape memory
Higher friction than SSS
When we have alinged teeth and are ready to apply 3rd order force to the teeth what kinf of wire is used
SS
This has less friction to allow the brackets to slide over each other to close the space
Allows control of torque movement
Elastomeric power chains are used to close spaces - what is there disadvanaghre
They loose their pull over time due to the oral envirment so need to be replaced regularly
Osteoblasts control all the reactions in tooth movement - what is hapeongin during compression
In areas of compression the osteoblasts bunch up together and expose the osteoid layer giving osteoclasts access to the bone
Osteoblasts send signals ie RANKL to osteoclasts to activate them
In areas of tension what are osteoblasts doing
They are flattened covering the Osteiod layer preventing the osteoclasts from gaining access to the bone
They secrete OPG preventing osteoclast differnetion ans thier actvity
The balance between what two things regulates bone remodelling
OPG and rankl
Why do adults seek treatment
Improve dental appearance
Refused treamtent as a child
Facilitate restorative treatment
After periodontal drift
Part of surgical correction of jaw discrepancy
Name 5 things that are different in adults to children receiving ortho
Lack of growth
Periodontal disease
Missing/ heavily restored teeth
Physiological factors
Adult motivation
In terms of the periodontal tissues in adult ortho, previous ortho does not preclude treatment but what does
Active periodontal diease
Loss of support of periodontal tissues in an adult ortho patient leads to what two things
Tooth centre of rotation moving apically
Anchorage value reducing
What are 3 restorative reasons that an adult may receive ortho
Upright abutments to aid restoration ( i.e. path of insertion)
Intrusion of over erupted teeth
Extrusion to increase crown lenthj
Perio patients must be stabilised before receiving orthodontic treatment - what do they need following treatment
Long term retention
What are Andrews 6 keys
Tight approximal contacts with no rotation
Class 1 incisors
Class 1 molars
Flat occlusal plane or slight curve of spee
Long axis of the teeth have a slight mesial inclination expect lower incisors
The crowns of the canines back to the molars have have a lingual inclination
