ortho 2 Flashcards
3 phases of tooth eruption
pre eruptive
eruption - intra-osseous and extra-osseous
post eruption
what are the fibres formed at the periphery of the eruption pathway, that guide the tooth into the oral cavity called
gubernacular cord
describe the intra-osseous eruptive phase
root formation - proliferation of epithelial root sheath then dentine and pulp formation
movement of developing tooth occlusally or incisally - slow, several months
formation of gubernacular cord - links tooth follicle to gingiva
reduced enamel epithelium rises with oral epithelium to form junctional epithelium
describe the extra-osseous eruption phase
penetration of crown tip ruptures epithelium - fast, 1-2 weeks
formation of attached gingivae
crown moves through mucosa until contacts opposing tooth - slow, several months
environmental factors determine final position (forces from cheeks, lips, tongue)
describe the post eruptive phase of eruption
movement after tooth reaches occlusal plane
- response to growing alveolar bone and jaws
- response to attrition and abrasion - compensating for wear
- tooth wear of proximal surface leads to mesial drift
- over eruption due to loss of opposing teeth
give a cause of mesial drift
tooth wear of proximal surface
3 roles of the dental follicle
initiate resorption of overlying bone
creates eruption pathway via connective tissue degradation
promotes alveolar bone growth
what is interceptive ortho
any procedure that will reduce or eliminate developing malocclusion
when is the correct time to extract deciduous tooth to encourage permanent teeth to erupt
one half to two thirds root development of permanent tooth
what age can you treat ectopic upper permanent canines by extracting the cs
10-13
where in relation to the primary incisors to permanent incisors develop
palatal/lingual
Additional space is required to accommodate the larger anterior teeth of the permanent dentition, how is this space gained
lateral growth of jaws increases inter canine width
upper incisors erupt more proclined
lee way space
what is the leeway space in upper arch
1-1.5mm
what is the leeway space in lower arch
2-2.5mm
how to calculate leeway space
primary c d e - permanent 3 4 5 = leeway space
when does a diastema usually close
by 12 when the 3s have erupted
management options of ectopic 6 stuck beneath e
if <7 years wait 6 months and review
orthodontic separator
distalise 1st molar
extract E
file down distal of E
causes of unerupted central incisors
trauma to primary tooth causing dilaceration of permanent
supernumeraries
management of unerupted central incisors
remove primary teeth and supernumeraries
maintain/create space
monitor for 12 months if less than 9
if 9+ or still not erupted, expose and ortho traction
impact of early loss of deciduous teeth
localised crowding
what factors influence the effect of crowding after early loss of deciduous tooth
crowding already present
age
which arch
which tooth
reason for balancing extraction
maintain position of centre line
reason for compensating extraction
maintain buccal occlusion
loss of which deciduous tooth requires balancing extraction
C
why should you consider a space maintainer after early loss of an E
major space loss of don’t - 6 will drift mesially
more so in upper than lower
design a passive URA that will maintain space
Adams clasp 0.7mm HSSW on UL6 and UR6
southend clasp 0.7mm HSSW
baseplate with acrylic serenaded around teeth to prevent mesial drift
+/- mesial stop 0.6mm HSSW on individual tooth
example of a fixed space maintainer
band and loop
when is the most ideal result gained when extracting 6s of poor prognosis
7s bifurcation is calcifying
8s are present
moderate crowding
class 1
4 rules for extracting 6s
if extracting lower, take upper - compensate
don’t need to compensate an upper 6 extraction
don’t balance with a sound tooth
don’t balance if well aligned or spaced
What do we tell the patient when we fit a removable appliance ?
Wear Full-time
Keep teeth and appliance clean - 2x daily minimum and every time after eating. (Can be worn for eating but remove for tooth brushing.)
Use a daily fluoride mouthwash
Avoid sugary food and drinks especially carbonated drinks
Avoid hard, sticky foods
May want to remove for some sports
initially speech will be affected
excess saliva
eating might feel awkward
teeth being moved might be painful.
Advise whom to Contact if patient has any problems
describe an URA design suitable for crossbite correction
hyrax screw or coffin spring
post bite plane
Adams class 0.7mm HSSW on 4s and 6s
over correct
URA design for anterior cross bite
z spring for tooth behind Lower incisors 0.5mm HSSW
Adams clasps 0.7mm HSSW on 4s and 6s
posterior bite plane
management of digit habit
bitter nail polish
positive reinforcement
glove on hand
habit breaker appliance - deterrents such as goal posts
how to know if pt is wearing appliance
did they wear into surgery
ask them
still excess salivation or speech affected
are active components now passive
signs of wear on appliance, palate and gingiva
what should you check for when assessing ant.cross bite
gingival recession
mobility of lower incisor
tooth wear
displacement
what is the aetiology of an infra occluded tooth
ankylosis of primary tooth
surrounding alveolar bone continues to grow
primary tooth left behind
how do you diagnose infra-occluding teeth
percussion
check for mobility
radiographs
when radiographically assessing an infra occluded tooth, give 3 things to check for
ankylosis of tooth - no PDL space
presence or absence of successor
root resorption
treatment of infra-occluded tooth below contact point
extract and maintain space
Please provide an URA to maintain space UL5
Adams clasps UR6 and UL6 (0.7mm HSSW) Southend clasp UR1,UL1 (0.7mm HSSW)
extend baseplate distal to UL4 OR Consider wire stop
where does development of canines begin
high and palatal
when do you start palpating and assessing position of upper canines
9 - should be palpable by 11
what effect do ectopic upper canines have on lateral incisors
root resorption
what circumstances is extraction of c most successful - 3
pt between 10 and 13
canine distal to midline of upper lateral incisor
sufficient space is available
risks of doing nothing with ectopic maxillary canines
becomes more ectopic
root resorption of adjacent teeth
failure to erupt
ortho interceptive treatment options for class 3
maxillary protraction head gear +/- RME (rapid maxillary expansion)
reverse twin block
why treat OJ early
trauma risk
appearance - bullying
more difficult when pt stops growing
when is anterior cross bite treated by ortognathic surgery and when is it treated with orthodontics
orthognathic - skeletal cause
orthodontics - dental cause
objective of ortho
to produce an occlusion that is stable, functional and aesthetic
what is compromise treatment
correct certain aspects and accept others e.g. accept buccal cross bite with no displacement
which arch is ortho treatment planned around
plan around lower arch and decide lower treatment
then build upper arch around lower
when examining a pt upper and lower arches for orthodontic assessment what do you check for
crowding
angulation of incisors
angulation of canines
centrelines
when orthodontically assessing teeth in ICP, what do you assess
incisor relationship
canine and molar relationship
OJ
OB
centrelines
how do you measure space available and space required when assessing crowding
space available = measure arch length anterior to first permanent molar
space required = measure every tooth width anterior to first permanent molar and add together
for what degree of crowding in lower arch do you extract 5s
mild to moderate
0-4mm
5-8mm
if taking lower extract upper
for what degree of crowding in lower arch do you extract 4s
moderate to severe crowding
5-8mm
8+mm
if taking lower extract upper
what incisor and canine relationship is the aim of ortho
class 1
what molar relationship is the aim in ortho
class 1 OR full unit class 2
limitations of ortho
prone to relapse if forces are not balanced between occlusion, periodontal structures and soft tissues
movement limited by shape and size of alveolar process
effects are purely dento alveolar and tooth movement - little skeletal effect
when are functional appliances and overbite reduction most successful
if used during adolescent growth spurt
main constituent of stainless steel
iron 72%
stainless steel constituents
iron - 72%
chromium - 18%
nickel - 8%
titanium - 1.7%
carbon - 0.3%
what is iron combined with to form steel
carbon
property chromium gives to steel
corrosion resistance
what properties do nickel give to SS
corrosion resistance and strength
why is titanium added to SS
to prevent precipitation of chromium carbides at grain boundaries
carbon preferably binds to titanium over chromium
how to make HSSW
work hardening - drawing metal In cold state through series of dies of successively smaller diameter
what are active components
components that will be moving teeth with application of force
what is retention in a URA
resistance to displacement forces
what is anchorage
resistance to unwanted tooth movement
what is the function of a baseplate in a URA
connect components
anchorage
retention
diameter of wire used for active components
0.5mm HSSW
diameter of wire for Adams clasps and retentive components
0.7mm HSSW
what component can you utilise to correct an over bite
FABP
advantages of removable ortho - 4
less specialised training requires
tipping of teeth
anchorage
OH easy to maintain
disadvantages of removable ortho - 4
can be removed by pt
only 1-2 teeth at a time
rotations are difficult to correct
less precise control
purpose of tagging ends of Adams clasp
to add mechanical retention
what additional component is added to buccally placed active components to increase their strength and rigidity
0.5mm internal diameter tubing - example, buccal canine retractor
describe a URA for 12 in anterior cross bite
12 z spring 0.5mm HSSW
16 26 14 24 Adams clasp HSSW 0.7mm
posterior bite plane
active component that could be utilised to retract buccally placed canines
buccal canine retractors o.5mm with o.5mm ID tubing
component that would correct overbite in pt
pt also has OJ of 6mm
flat anterior bite plane OJ plus 3mm
steps in fitting a URA
check correct patient
check correct design
inspect design
check integrity of wire work
insert and check for blanching or trauma
check posterior retention - flyover then arrow head
check anterior retention
activate appliance
demo pt insertion and removing
review app. 4-6 weeks
what info will you give to a pt after fitting a URA
big and bulky feel
affect speech for short time
salivation
discomfort or ache
wear 24/7 inc meal times and sleep
remove after meal and clean
remove for contact sports
avoid hard or sticky foods
cautious with hot and cold
non compliance increases treatment time
emergency contact
Appliance that can be used to reduce 6mm OJ of 11 12 21 22 and OB
Roberts retractor - o.5mm HSSW with o.5mm ID tubing
0.7mm mesial stops on 13 and 23
16 and 26 Adams clasp
FABP OJ+3mm - need to reduce gradually
URA appliance design to expand upper arch
midline palatal screw
adams clasp on 16 26 14 24
PBP
why is facial growth important
size shape and position of jaws determines tooth position and therefor malocclusion
can utilise growth to predict changes and correct
what are thew two phases of life in utero
embryonic 1-8 weeks
foetal 8 weeks to term
when are all the limbs and organs formed in utero
first 2 months
when is the incidence of deformities that lead to miscarriage highest
first 8 weeks - embryonic
how many Carnegie stages is the embryonic period divided into
23
describe the first stage - first day of embryonic life
fertilised oocyte
male and female pronucleus
formation of zygote
ascribe stage 2 of embryonic life
separation and formation of blastomeres
what happens in stage 3 of embryogenesis
segmentation
embryonic and abembryonic poles
what happens after the primitive groove is formed
embryo with somites and neural groove formation
which cell migration is important in development of face
neural crest
how does the neural tube dorm
neural folds fuse to form neural tube at end of week 3
the neural tube fuses at the end of week 3, failure to fuse will lead to what?
spina bifida
the neural tube develops into the brain and spinal cord, what will failure to develop lead to
anencephaly - cerebral hemispheres and cranial vault absent
neural crest cells develop along the neural groove and then undergo migration to differentiate into many cell types such as…
spinal and autonomic ganglia
Schwann cells
adrenal medulla
where is the ectomesenchyme derived from
neural crest
what does ectomesenchyme contribute to
branchial arch cartilage
bone and connective tissue proper
dental tissues - pulp dentine cement and PDL
where are pulp dentine cementum and PDL derived from
ectomesenchyme
when does formation of the face occur in utero
first 8 weeks
defects of the face are closely related to defects where else
anterior brain
what cells form the majority of the face
migrating neural crest cells
what occurs when there is failure of fusion between the palatine processes or facial processes
cleft formation
why do cleft lip and alveolus occur independently of cleft palate and vice versa
the upper lip and anterior palate have different embryological origins to posterior palate and fuse at different times
where are mandibular and maxillary processes derived from
first pharyngeal arch
where is the operculum and sinus cervicalis derived from
2nd pharyngeal arch
the skull can be divided into two parts. what are the two parts
neurocranium - protective case of brain
viscerocranium - skeleton of face
give examples of intramembranous bones
vault of skull
maxilla
most of mandible
how is intramembranous bone formed
bone is deposited directly into primitive mesenchymal tissue
bone spicules form which radiate from primary ossification centres to periphery
progressive bone formation leads to fusion of adjacent bony centres
how is endochondral bone formed
bones are preceded by a hyaline cartilage
several centres of ossification which eventually fuse
which bones are formed by endochondral ossification
base of skull
where do cartilaginous growth centres remain at birth
between spend and occipital bones
nasal septum
intramembranous ossification is incomplete at birth and there are widening left on the vault of cranium. what are these called and what are their function
fontanelles - allow flexibility during birth
when does the ant. and post. fontanelle close
anterior - 2 years
posterior - 1 year
why does growth continue to occur at fibrous sutures until about 7
intracranial pressure
maxilla and mandible develop adjacent to preexisting cartilaginous skeletons, what is the name of these?
maxilla - develops adjacent to nasal capsule
mandible - develops adjacent to meckels cartilage
describe the growth of the mandible
develops adjacent to pre existing mockers cartilage
develops as several units responding to different stimuli - condylar, angular, coronoid, body and alveolar unit
3 main secondary sites of cartilage formation - condylar, coronoid and symphyseal
coronoid disappears before birth, condylar growth continues until 20, midline symphysis uses a few months after birth
what are the 5 units of mandible in development
body
angular
alveolar
coronoid
condylar
what does the body unit of mandible form in response to
IAN
what does the coronoid unit of mandible form in response to
temporalis muscle development
when does the alveolar unit of mandible form
only when there are teeth developing
what does the angular unit of mandible form in response to
in response to lateral pterygoid and masseter
what are the 3 main sites of secondary cartilage formation in the mandible at each end of mandible halves
condylar cartilage - grows until 20
coronoid cartilage - disappears before birth
symphyseal - midline symphysis fuses after birth
briefly describe prenatal growth of the face - 5
ossification of skull and face commences 7-8weeks
neurocranium incases brain, viscerocranium skeleton of face
the vault of skull is formed intramembranously
base of skull is formed by endochondral ossification
maxilla and mandible formed intramembranously but are preceded by cartilaginous facial skeleton
what cartilage is the primary skeleton of upper face
nasal capsule
what cartilage precedes the mandible
meckels cartilage
what is a primary abnormality and give an example
defect in the structure of an organ or part of an organ that can be traced back to an anomaly in development
cleft lip
spina bifida
what is a secondary abnormality and give an example
interruption in the normal development of an organ that can be traced back to other influences
trauma
infection - rubella virus
thalidomide
what is a deformation
anomalies that occur due to outer mechanical effects on existing structures
what is agenesia
absence of an organ due to failed development during embryonic period
what is a sequence abnormality - give example
single factor resulting in numbers secondary effects
pierre robin sequence - underdeveloped mandible
what is a syndrome and give example
group of abnormalities that can be traced to a common origin
trisomy 21 in downs syndrome
3 facial syndromes related to maxillary hypoplasia
aperts syndrome - acrosyndactyly
croutons syndrome - craniofacial dysotosis
doses syndrome
3 facial syndromes related to mandibular problems
teacher Collins - mandibulofacial dysostosis
pierre robin sequence
hemifacial microsomia
give an example of facial syndrome that arises from environmental cause
foetal alcohol syndrome
characteristics of foetal alcohol syndrome
indistinct philtrum and thin upper lip
short palpebral fissures
microcephaly
short nose and low nasal bridge
micrognathia - small mandible
mild mental retardation
characteristics of hemifacial microsomia
unilateral mandibular hypoplasia - spectrum
zygomatic arch hypoplasia
malformed pinna
deafness
what causes treacher collins
deformity of 1st and 2nd pharyngeal arches
what are the characteristics of treacher collins syndrome - mandibulofacial dystosis
anti-mongoloid slant palpebral fissure
colomboma of lower lid outer third
hypoplastic or missing zygomatic arches
hypoplastic mandible with antigonial notch
deformed pinna and conductive deafness
incidence of cleft L and P
1:700 births
when does cleft lip and cleft palate abnormality occur
cleft lip day 28-38
cleft palate day 42-55
3 genetic causes of cleft lip and palate
monozygotic twins
familial pattern
syndromes
3 environmental causes of cleft lip and palate
social deprivation
smoking
alcohol
3 dental features of cleft lip and palate
impacted teeth
crowding
hypodontia
what is achondroplasia
problem with endochondrial ossifications
defects in long bones - short limbs
characteristics of achondroplasia
short limbs - dwarfism
base of skull defects - retrusive mid third of face depressed nasal bridge, frontal bossing (prominent forehead)
what causes crouzons syndrome (craniofacioal dystosis)
premature closure of cranial sutures - coronal and lambdoid
characteristics of crouzons syndrome (craniofacial dystosis)
proptosis - shallow orbits
orbital dystopia
retrusion and vertical shortening of mid face
prominent nose
class 3 and narrow spaced teeth
what is cranial synostosis
early closure of cranial sutures
what is the cause of aperts syndrome - acrosyndactyly
premature closure of almost all sutures
characteristic of aperts syndrome/acrosyndactyly
proptosis - bulging eyes
hypertelorism - increased distance between orbits
maxillary hypoplasia
parrots beak nose
class 3 occlusion, AOB
acrosyndactyly/aperts affects the face by premature closure of almost all cranial sutures, where else does aperts affect
syndactyly of fingers and toes
3 differences between adult and child face
infant has small face compared to cranium
eyes are large and ears low set
forehead upright and bulbous
3 sites of facial growth
sutures
synchondroses
surface deposition
what is a suture
fibrous joint between intramembranous bones that fuse when growth is complete
where are synchondroses found
midline of sphenoid, occipital and ethmoid bones
what is a synchondrosis
a cartilage based growth centre - growth occurs in both directions
peripheral cartilage turns to bone while new cartilage forms in middle
what is the process of bone deposition and resorption known as
bone remodelling
what is the change in position of a bone due to remodelling known as
drift
how many fontanelles are present at birth
6
growth of cranial vault occurs in response to the expanding brain until what age
7
2 ways growth occurs in cranial vault
bone growth at sutures
external and internal surface remodelling of bone
2 ways growth occurs in cranial base
endochondral ossification
surface remodelling
large cranial base angle is associated with what skeletal class
class 2
class 3 is associated with what size of cranial base angle
small angle
where does sutural growth of maxilla take place
mid palatine suture
zygomatic and frontal bone sutures
how does the mandible grow in terms of direction
down and forward
how does the mandible grow to accommodate permanent dentition
condylar cartilage
surface remodelling - resorption anterior and lingual and deposition posterior and lateral
when does growth of the mandible accelerate significantly
during pubertal growth spurt
when does the maxilla growth start to slow
7
put in order of which growth of mandible and maxilla slows first - height, width, length
width - slows first
length
height
what treatment would an orthodontist use growth to facilitate - 4
functional appliance
rapid maxillary expansion
protraction headgear
overbite reduction
what causes growth rotations
imbalance in growth of anterior and posterior face heights
what growth rotation leads to development of deep bite
forward
what growth rotation can lead to AOB
backwards
3 ways to measure facial growth changes
lateral cephalometry
casts of face
3D photogrammetry
indications for lateral cephalogram - 3
aid diagnosis of skeletal discrepancy
treatment planning
to monitor progress of treatment e.g. functional appliance
position pf head and occlusion for lateral cephalogram
Frankfurt plane parallel to floor
RCP
how is head kept steady in cephalostat
ear rods
nasion support
what is a lateral cephalogram
standardised radiograph of face and base of skull
what is cephalometry
analysis and interpretation of lateral cephalograms
why are lateral cephalographs used for ortho treatment
they are reproducible - set distance
what do you analyse when interpreting a lateral ceph. - 4
relationship between jaws and cranial base
relationship between upper and lower jaw
teeth position relative to jaw
soft tissue profile
what angle measures maxilla in relation to mandible anteroposteriorly
ANB
what angle measures antero posterior position of mandible and maxilla in relation to base of skull
SNB - mandible
SNA - maxilla
what angle measures the position of mandible relative to maxilla vertically
FMPA
normal SNA
81 +/-3
normal SNB
79 +/-3
normal ANB
3 +/-2
normal FMPA
27 +/-4
normal LAFT/TAFH ratio
55%
UI-Mx and LI-Md measure the angulation of teeth to maxilla and mandible - what are their normal values
UI Mx 109 +/-6
LI Md 93 +/-6
UI/LI is 135
ANB in class 1
2-4*
ANB in class 2
mild 4-6*
mod 6-8*
sev >8*
class 3 ANB
mild 0-2*
mod -3-0*
sev <-3*
