orthodontics refined Flashcards
what are the three planes of space in ortho?
anteroposterior
vertical
transverse
how is lateral cephalogram technique made ALARA? - 4
aluminium soft tissue filter
thyroid collar
triangular collimation
fast film
what does ANB angle relate?
mandible to maxilla
what is the average value of SNA?
81
what is the average value of SNB?
79
what is the average value of ANB?
3
describe the facial profile of class 2
convex profile
increased cranial base angle
describe the profile and jaw relationship of class 3
acute cranial base angle
concave profile
where should mandibular plane and Frankfurt plane meet normally?
external occipital protuberance - back of head
what is the average Frankfurt mandibular plane angle? FMPA
27
which plane runs orbitale to porion cephalogram?
Frankfurt plane
which plane runs menton to gonion on cephalogram ?
mandibular plane
what is the average value of UAFH to LAFH on cephalogram?
55%
describe the FMPA of patients with long facial type
> 31*
describe the LAFH to TAFH proportion in patients with long facial type
> 55%
name 2 features that contribute to long facial type
AOB
backward mandibular growth rotation
describe the FMPA in patients with short facial type
<23*
describe the LAFH to TAFH proportion in patients with short facial type
<55%
what contributes to short facial type?
forward mandibular growth rotation
deep overbite
what causes crowding?
small jaws with normal size teeth
macrodontia
Your child patient presents with a single grossly carious first permanent molar. The condition of the other three first permanent molars is reasonably good. Which of the following are the main factors that influence any decisions that need to be made regarding whether or not to balance or compensate the extraction of this grossly carious tooth?
Select one:
a.
Presence of carious deciduous teeth, age of patient, Crowding
b.
Early loss of primary teeth, malocclusion type, age of patient
c.
Age of patient, presence of bilateral crossbite, degree of crowding
d.
Age of patient, degree of crowding, malocclusion type
e.
Presence of crowding, malocclusion type, presence of carious deciduous teeth
d.
Age of patient, degree of crowding, malocclusion type
When performing an intra-oral examination of a 9.5 year-old patient which of the following would not be considered a relevant feature to indicate the possibility of an unerupted ectopic canine?
Select one:
a.
Inclination/Angulation of the upper lateral incisor
b.
A palpable palatal elevation of the alveolar mucosa
c.
Mobility of the deciduous canine
d.
Discolouration of the deciduous canine
e.
Presence of an upper midline diastema
e.
Presence of an upper midline diastema
Which of the following would you expect to find in a patient with long face syndrome?
Select one:
a.
Backward growth rotation of the mandible.
b.
Increased maxillary posterior dentoalveolar height.
c.
An increased lower anterior face height percentage.
d.
Ante-gonial notching of the mandible.
e.
All of the above.
e.
All of the above.
What is the correct term used to describe a mismatch between the size of a patient’s teeth and jaws?
Select one:
a.
Microdontia.
b.
Dento-alveolar disproportion.
c.
Odonto-alveolar disproportion
d.
Dento-skeletal discrepancy.
e.
Severe crowding.
b.
Dento-alveolar disproportion.
What is the likely cause of a left-sided unilateral posterior crossbite that is not associated with a lateral displacement of the mandible on closure?
Select one:
a.
Mandibular prognathism.
b.
Vertical maxillary deficiency.
c.
A narrow maxillary dental arch.
d.
An anterior open bite.
e.
A true asymmetry of the mandible with the chin point shifted to the left.
e.
A true asymmetry of the mandible with the chin point shifted to the left.
Which of the following can be caused by early loss of primary teeth?
Select one:
a.
Ankylosis of permanent teeth and loss of alveolar bone
b.
Dental centreline shifts and loss of alveolar bone
c.
Drifting of adjacent teeth and caries in the permanent dentition
d.
Space loss and ankylosis of permanent successor
e.
Crowding and dental centreline shifts
e.
Crowding and dental centreline shifts
Which two the following categories of supernumerary teeth are the most likely to erupt into the oral cavity?
Select one:
a.
Mesiodens and complex odontome
b.
Supplemental and conical
c.
Compound odontome and tuberculate
d.
Conical and tuberculate
e.
Tuberculate and Supplemental
b.
Supplemental and conical
Which of the following is most commonly associated with a Class III jaw relationship?
Select one:
a.
Anteroposterior maxillary deficiency.
b.
True mandibular asymmetry.
c.
Mandibular prognathism.
d.
Vertical maxillary excess.
e.
Anterior open bite
a.
Anteroposterior maxillary deficiency.
what causes spacing?
large jaws normal size teeth
microdontia
what does local cause of malocclusion mean
localised problem within either arch - confined to one-several teeth - producing malocclusion
3 local causes of malocclusion
variation in tooth number
variation in tooth size/form
abnormal tooth position
4 causes of variation in tooth number?
supernumerary teeth
hypodontia
retained primary teeth
early loss of primary teeth
where are supernumerary teeth most commonly found in the dentition?
maxillary anterior
what are the four types of supernumerary teeth?
conical
tuberculate
supplemental
odontome
which type of supernumerary teeth are small, peg shaped and close to the midline (mesiodens)?
conical
which type of supernumerary teeth are barrel shapes and usually paired?
tuberculate
which type of supernumerary teeth tend not to erupt and are one of the main causes of failure of eruption of permanent upper incisors?
tuberculate
supplemental supernumerary teeth are most commonly which teeth?
upper laterals or lower incisors
which teeth are commonly affected by hypodontia?
upper laterals
second premolars
when should you be worried about retained primary teeth?
when more than 6 months has passed since the shedding of contra-lateral teeth
4 causes of primary teeth to be retained?
absent successor
ectopic successor
infra-occluded (ankylosed) primary molars
pathology/supernumerary
how would you treat a patient with absent successor teeth? 3
maintain primary as long as possible
extract early to encourage space closure if crowded
refer early to ortho
what are 5 causes of early loss of primary teeth?
trauma
periapical pathology
caries
resorption by successor
crowding
what effect does early loss of primary molars have on the dentition?
more space is lost with E than D
6s will drift mesially and steal the space for the 5
Early loss of primary teeth can lead to crowding in the permanent dentition - what 3 factors impact the degree of crowding?
which tooth is extracted/lost
when the tooth is extracted/lost
crowding of patient
what influences the impact of loss of 6s?
age at loss
crowding
malocclusion
how does age of the patient at loss of their 6s impact the dentition?
if lower 7s have erupted there is often poor space closure
if lower 6s lost too early there is distal drift of the 5s
what is the likely result of early loss of a central incisor?
drift of adjacent teeth
what is the likely result of late loss of central incisor?
long term space
what local pathologies can influence malocclusion?
caries
cysts
tumours
what are the effects of digit sucking on the dentition?
proclined UI
retroclined LI
anterior open bite
unilateral posterior cross bite - due to narrow maxillary arch
what effect can labial frenum have on the dentition?
Median diastema
what are the three ways teeth can vary in size or form?
macrodontia
microdontia
abnormal form
what problems are associated with macrodontia?
crowding
asymmetry and aesthetics
what problems are associated with microdontia?
spacing
linked to hypodontia
give examples of teeth of abnormal form
peg shape laterals
dens in dente
germinated/fused teeth
dilaceration
accessory cusps and ridges
what are two abnormalities of tooth position that cause malocclusion?
ectopic teeth
transposition teeth -interchange in position of two teeth in same quadrant
ectopic canines have higher incidence in what malocclusion
class 2 div 2
from what age should you palpate for buccal canine bulge?
9 years onwards
ectopic canine teeth are most commonly where?
palatal
what are buccal canines associated with?
crowding
how do you clinically assess ectopic canines?
visualisation/palpation of 3
inclination of 2
mobility of c and 2
colour of c and 2
what radiographs are required to localise position of ectopic canines?
OPT AND upper anterior oblique occlusal
what are the management options for ectopic canines?
prevention - monitor and assess from age 9
interceptive -extraction of c to encourage improvement
accept - its position and observe
exposure - surgically expose and ortho realignment
surgical extraction
autotransplantation
what age would you extract c to encourage eruption of ectopic 3
10-13
if extracting upper C to encourage eruption of ectopic 3, where is the ideal location of the 3 in relation to the lateral incisor
distal to the midline of upper lateral
what risks are associated with not treating ectopic maxillary incisors?
becomes more ectopic
root resorption of adjacent teeth
failure to erupt
what are possible causes of ectopic upper centrals?
no cause
supernumerary - tuberculate or odontome
trauma to primary - ankylosis or displacement of tooth germ or dilaceration of root
what are the classifications of transposition teeth?
true - whole root and crown are found in transposed position
pseudo - only the crowns or the roots are transposed, one stays in same place
what is hemifacial microsomia
half of the face is underdeveloped and does not grow normally
3 features of hemifacial microsomia
malformed ear (deafness)
progressive facial asymmetry
occlusal issues
what can removable appliances be used for
tip teeth
maintain space
to correct overbite/crossbites
what are the 3 major risks of orthodontic treatment
decalcification
relapse
root resorption
what age do you briefly ortho assess a patient
9 Years
when do you carry out a comprehensive ortho assessment
11/12 years old when premolars and canines erupt
Andrews 6 keys of ideal occlusion
molar relationship
crown angulation
crown inclination
no rotations
no spaces
flat occlusal plane
4 contraindications to ortho
allergy to nickel or latex
Epilepsy - Can’t have URA
drugs - gingival hyperplasia
imaging - if need MRI can’t have braces
how can the tongue and lips influence tooth position
incompetent lips - lip trap - proline UI
lip activity - hyper active will retrocline LI
tongue thrust - AOB
causes of AOB
tongue thrust on swallowing - relapse after ortho if endogenous tongue thrust
digit sucking
occlusal features of sucking habit
proclined upper anterior
retroclined lower anterior
localised AOB
unilateral posterior cross bite
what is the average angulation of upper incisors to Frankfort plane
110 degrees
average overbite covers how much of lower incisor crown
1/2-1/3
describe class 1 2 and 3 buccal segment relationship
class 1 - mesiobuccal cusp upper 6 sits in buccal groove of lower 6
class 2 - mesiobuccal cusp infront of lower 6
class 3 - mesiobuccal cusp behind lower 6
when is it not possible to move teeth with orthodontic force
if a tooth has no PDL or is ankylosed
what does RANKL stand for
Receptor Activator of Nuclear factor Kappa-b Ligand
what secretes osteoprotegerin (OPG)
osteoblasts
function of OPG
prevents osteoclastic differentiation and suppresses their activity
the balance between which 2 molecules regulates bone remodelling
OPG and RANKL
Which force range would be most appropriate to apply when trying to tip teeth?
35-60g
how do functional appliances work
mandible postured away from normal rest position
facial muscles stretched generating force on teeth and alveolus
how can a functional appliance affect facial growth on a class 2 patient 3 marks
restrict maxillary growth
promote mandibular growth
remodel glenoid fossa
what dento alveolar changes do functional appliances cause
retrocline upper
procline lower
mesial migration lower teeth
distal migration upper teeth
which movements require optimal force of 35-60g
tipping
extrusion
rotation
which movement requires optimal force of 10-20g
intrusion
which movement has optimal force of 50-100g
torque
Which force range would be most appropriate to apply when causing bodily movement of teeth with a fixed appliance?
150-200g
what factors affect the response to orthodontic force - 4
magnitude
duration
age
anatomy
ideal amount of tooth movement per month
1mm
type of resorption related to light forces
frontal resorption
type of resorption related to moderate forces
undermining resorption
describe the difference in speed of tooth movement between light, moderate and heavy forces
light - slow and steady movement
moderate/heavy - rapid initial movement then 10-14 days with little movement while undermining resorption occurs
what are the unwanted side effects of excessive forces
pain
Undermining resorption
root resorption
loss of vitality
anchorage loss
In order to promote eruption of an upper second premolar we are considering extracting the deciduous second molar. What would be the ideal stage of root development of the unerupted second premolar to produce an optimal result?
a. More than two thirds root formed
b.Less than one half root formed
c.One half to two thirds root formed
d.Less than one third root formed
e.Root formation not started but crown formation complete
c.One half to two thirds root formed
With regards to the mechanism by which bodily orthodontic tooth movement takes place during fixed appliance treatment, which of the following statements is true:
Select one:
a.
Bone is laid down in response to compression of the periodontal ligament on the same side of the tooth as the direction of intended tooth movement
b.
Bone is removed in response to tension of the periodontal ligament on the same side of the tooth as the direction of intended tooth movement
c.
Bone is laid down in response to tension of the periodontal ligament on the opposite side of the tooth to the direction of intended tooth movement
d.
Bone is removed in response to compression of the periodontal ligament on the opposite side of the tooth to the direction of intended tooth movement
e.
Bone is laid down in response to compression of the periodontal ligament on the same side of the tooth as the direction of intended tooth movement
c.
Bone is laid down in response to tension of the periodontal ligament on the opposite side of the tooth to the direction of intended tooth movement
Which of the following force ranges would be most appropriate to apply when trying to intrude teeth with a fixed appliance?
a.
50-100g
b.
35g -60g
c.
150-200g
d.
10-20g
e.
100-150g
d.
10-20g
Which of the following histological features is thought to play the biggest role in tooth eruption
a.
Epithelial root sheath ( Hertwig’s root sheath )
b.
Dental Follicle
c.
Gubernacular cord
d.
Reduced enamel Epithelium
e.
Epithelial cell rests (of Malassez)
b.
Dental Follicle
Which of the following is NOT a factor which can influence the rate of tooth movement?
Select one:
a.
Magnitude of force
b.
Anatomy of bone in the area
c.
Duration of force
d.
Age of the patient
e.
Direction of force
e.
Direction of force
order of eruption for deciduous teeth
abdce
lowers before upper
when do deciduous teeth erupt
6months to 2.5 years
when is extraction of neonatal teeth indicated
if mobile - risk of inhalation
difficulty breast feeding
what are natal/neonatal teeth
teeth present at or just after birth
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
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 is the leeway space in upper arch
1.5mm
what is the leeway space in lower arch
2.5mm
how do you calculate leeway space
width of CDE minus width of 345
when does a diastema close usually
12 when canines erupt
management of ectopic 6
if <7 years wait 6 months and review
orthodontic separator
distalise 1st molar
extract E
file down distal of E
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
how do you manage early loss of an E and why
consider space maintainer as 6 will drift mesial and space will be lost
when is the optimum result gained when extracting 6s of poor prognosis - 4
7s bifurcation is calcifying
8s are present
moderate crowding
class 1
URA design for anterior cross bite
A - z spring for tooth that is behind LI 0.5mm HSSW
R - Adams clasps 0.7mm HSSW on 4s and 6s
A - only moving one tooth
B - self cure PMMA with posterior bite plane
how do you manage a digit habit - 4
bitter nail polish
positive reinforcement
glove on hand
habit breaker appliance - deterrents such as goal posts
4 signs a patient is wearing their URA
active components now passive
wore into surgery
no excess salivation and speech adapted
signs of wear on appliance and tissues
how can you diagnose an infra occluded tooth
percussion note
radiograph - no PDL space
no mobility
why is it important to treat over jet early
trauma risk
aesthetics - bullying
more difficult to treat when pt stops growing
which arch do you treatment plan first
lower - then plan upper around the plan for lower
when assessing crowding, how is space available measured?
measure arch length anterior to FPM
you are going to extract a premolar to alleviate crowding in the lower arch -
when would you extract the 4 and when would you extract the 5?
4 - moderate to severe crowding
5 - mild to moderate crowding
define mild, moderate and severe crowding
Mild: <4
Moderate: 4-8
Severe: >8
stainless steel constituents
iron - 72%
chromium - 18%
nickel - 8%
titanium - 1.7%
carbon - 0.3%
what is iron combined with to form steel
carbon
what property does chromium give to stainless steel
corrosion resistance
what properties do nickel give to stainless steel
corrosion resistance and strength
why is titanium added to stainless steel
to prevent precipitation of chromium carbides at grain boundaries
carbon preferably binds to titanium over chromium
how is stainless steel hardened
work hardening - drawing metal in a cold state through a series of dies of successively smaller diameter
what is the function of a baseplate
anchorage
retention
connect components
what is ID tubing used for in URA and give two examples of active components that require ID tubing
added to buccally placed active components to increase strength and rigidity
Roberts retractor
Buccal canine retractor
how to you fit a URA - 9
Correct patient
Correct design
Inspect acrylic
Integrity of wire
Insert and check for blanching or trauma
Posterior retention - flyover then arrow head
Anterior retention
Activate appliance
Demo pt insertion and removing
Review app. 4-6 weeks
advice given to pt after fitting URA
big and bulky
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
what is the result of neural tube fusion failure
spina bifida
where are pulp dentine cementum and PDL derived from
ectomesenchyme
what deformity occurs when palatine processes fail to fuse
cleft palate formation
why can cleft lip and alveolus occur independently of cleft palate and vice versa
upper lip and anterior palate have different embryological origins to the posterior palate
fuse at different times
where are mandibular and maxillary processes derived from
first pharyngeal arch
what cartilage precedes the mandible
meckels cartilage
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
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 - cartilage based growth centres
what causes growth rotations
imbalance in growth of anterior and posterior face heights
UI-Mx and LI-Md measure the angulation of incisors to maxilla and mandible - what are their normal values
UI Mx 109
LI Md 93
average inter-incisal angle (UI/LI)
135
