Orthodontics Flashcards
what can be used for parallax
horizontal parallax - two periapical radiographs
vertical parallax - an opt and occlusal
how does parallax work
need two images taken when the x-ray beam has changed direction
vertical - going from occlusal to OPT beam moves upwards - if tooth moves upwards - palatally placed
horizontal - two PAs, if move right and tooth moves right, palatally placed
SLOB - same lingual (palatal) opposite buccal
why do we take occlusal radiographs
to look for pathology in upper anterior region of maxilla
to confirm prescence of unerupted teeth
root resorption
to aid location of unerupted teeth - parallax
why do we take periapical radiographs
to investigate periapical infection
to check if a tooth is ankylosed
to check for root resorption
to aid location of unerupted teeth - parallax
why do we take bitewing radiographs
caries diagnosis
prognosis of tooth
alveolar bone levels
why do we take lateral ceph
aid diangosis - skeletal discrepancy
treatment planning
progress monitoring
research purposes
what position should the patient be in for lateral ceph and why are these useful
with frankfort plane horizontal and teeth in RCP, it is standardised and reproducible
what lines are seen on a lateral ceph
sella-nasion
frankfort - ponion to orbitale
maxillary plane - anterior nasal spine to posterior nasal spine
mandibular plane - menton to gonion
what analysis is commonly used for lateral ceph
eastmans analysis
what does the SNA and SNB line show in a lateral ceph and what are standard values
the antero-postero relationship of the maxilla (A) and the mandible (B) to the skeletal base. SNA - 81, SNB - 78
on a lateral ceph, what shows the relationship of the maxilla to the mandible
antero-postero - ANB
vertical - FMPA
what are the standard ANB values for each skeletal AP class
class 1 - 3-5
class 2 - more than 5, 8+ is severe
class 3 - less than 2, -3 is severe
what are the standard FMPA values for average, increased and decreased vertical class
average - 27 degrees
increased - above 27, above 32 mod
decreased - less than 27, below 22 mod
what should the inclination of the incisors be in relation to mandible and maxilla and what are the limits of camouflage
upper incisors - 109 ± 6
lower incisors - 93± 6
above these no.s - proclined
below these no.s - retroclined
uppers cannot be proclined past 120
lowers cannot be retroclined past 80
what measurements help to decided whether camouflage would be sufficient or if surgery would be required
ANB above 8 or below -3
FMPA above 37 or below 17
upper incisor above 120 or lower incisor below 80
why might we want to treat class 2 div 1
aesthetics - patients concerned, bullying
dental health - twice as likely to have trauma if OJ larger than 9mm
what skeletal pattern is often seen with class 2 div 1
AP - class 2, mandible behind maxilla, retrognathic mandible
vertical - variable, increased - AOB or decreased - large overbite
what soft tissue features are seen with class 2 div 1
lip trap - exacerbating proclination of uppers and retroclination of lowers
incompetent lips - incomplete closure of lips, increased risk of trauma
what habits are associated with class 2 div 1 and what are features of this
non-nutritive sucking habit
posterior cross bite - narrow upper arch
proclination of uppers
retroclination of lowers
anterior open bite
how is a sucking habit treatment
enforce that treatment cannot commence until habit stops - reinforcement, habit breaker - either URA or fixed
if stopped before 9 - spontaneous repositioning
after this, roots have completed growth so unlikely to get spontaneous
treat residual malocclusion
what management options are available for class 2 div 1
accept
enhance growth modification
simple tipping of teeth
camouflage
orthognathic surgery
what appliances can be used for growth modification
functional appliance - twin block
head gear
how does headgear work
restricts horizontal and/or vertical growth of maxilla to allow mandible to come forwards
how does a functional appliance work
utilize, eliminate or guide the force of muslce function, tooth eruption and growth to correct malocclusion
postures mandible downwards and forwards, stretches and activates masticatory muscles, mesialise mandible and distalise maxilla. restraint maxillary growth and enhance mandibular growth
what are therapeutic effects of functional appliance
minor skeletal change - any growth occured wouldve happened anyway. mostly dento-alveolar movement
distal movement of upper molars
mesial movement of lower molars
retroclination of upper anteriors
proclination of lower anteriors
what might be a design of a twin block functional URA
labial bow to retract upper incisors, midline palatal screw to expand upper arch, adams clasp for retention
when would a functional appliance be used
should be used during growth
can be used in early years - age 10 - can prevent trauma, compliance is better, but done in 2 phases as have to come back when secondary molars, not efficient and can get relapse
older ages - 12 - one phase of treatment, no relapse, easier, but risk of trauma, less compliant
what is the risk of using only ura to correct class 2 div 1
could tip the teeth back into class 2 div 2
when is camouflage appropriate
too old for functional, or had functional but compliance poor - can be used to mask skeletal difference if it is moderate
when is orthognathic surgery used
when growth is complete and AP or vertical skeletal relationship is severe
what is involved in orthognathic surgery for class 2 div 1
mandibular advancement and/or maxillary impaction
fixed ortho before, during and after treatment
what is the definition of hypodontia and severe hypodontia
congenital absence of one or more teeth, severe - 6 or more
what teeth are more commonly missing in hypodontia
upper and lower 5s
upper lateral incisors
lower incisors
last in series
what are the two types of hypodontia
syndromic - is a symptom of another syndrome - anhydrotic etodermal dysplasia, cleft palate
non-syndromic - mutations in at least 3 genes, familial or sporadic
how might hypodontia patients present
delayed eruption, unusual eruption pattern, retained primary teeth
what other problems are associated with hypodontia
microdontia, malformation of other teeth, impaction, delayed eruption, crowding or malocclusion
what are features of anhydrotic ectodermal dysplasia
effects all ectodermal tissue - hair, skin, sweat glands, teeth - sparse hair, dry wrinkly skin
what problems can hypodontia cause
spacing, over eruption, inadequate function, poor aesthetics
what treatment options are available for hypodontia patients
accept, ortho alone, restorative alone, ortho and restorative combined treatment
when missing upper laterals, what treatment options are available
open space - extract premolar, pull canine back and then restore with implant, denture, bridge
close space - use ortho to close space and leave it or can intrude canine and extrude premolar then alter shape of teeth with composite and bleach to make it look more like lateral - space closure plus
what must treatment for hypodontia achieve
satisfy aesthetic expectation, satisfy functional expectation, least invasive
what is the aetiology of class 2 div 1
skeletal - maxillary prognathism, mandibular retrognathism
dental - proclination of uppers
soft tissues - lip trap, NNS habit, tongue thrust
why is treatment required in class 2 div 1
OJ more than 9mm - IOTN 5a
high risk of trauma to incisors
aesthetics of concern to patient
what is the incisor definition of class 2 div 2
lower incisor edge lies posterior to upper incisor cingulum plateau, overjet is reduced or reversed, upper incisors are retroclined
what is the most common AP class seen in class 2 div 2
class 2 - ANB increased, more than 4
what vertical discrepancy is seen in class 2 div 2
reduced FMPA and reduced LFH
what are the soft tissue components seen in class 2 div 2
lower lip line is higher - entraps central incisors causing retroclination.
mentalis muscle is tight along chin - increases retroclination of lower incisors
what is the aetiology of class 2 div 2
skeletal - prognathic maxilla, retrognathic mandible
dental - increased overbite, retroclination of incisors, upper laterals have poorly developed cingulums, shortened crown height of laterals - missing lower lip and in lower lip trap
soft tissues - high lower lip line, tight mentalis muscle
what is the need for treatment in class 2 div 2
traumatic over bite - gingival stripping - 4f
what are the treatment options for class 2 div 2
accept - non-traumatic overbite, patient not concerned
growth modification - functional appliance
URA - mild malocclusion, used to reduce overbite
fixed appliance - camouflage if underlying skeletal pattern is mild
orthognathic surgery - outwith growth potential
what functional appliance can be used in class 2 div 2
modified from one used in div 1. want to procline upper incisors. ELSA design - expansion and spring - expand upper arch and spring to push upper incisors forward
what dental anomaly is commonly seen class 2 div 2
ectopic or impacted canines - have a long route eruption, utilise lateral incisors to ensure correct eruption - but if they are small, more likely to go wrong
what are the features of a class 3 incisor relationship
incisor - lower incisor edge lies anterior to cingulum plateau of upper incisors
AP - class 3, ANB less than 2
vertical - FMPA can be increased or reduced, LAFH can be increased or reduced
transverse - asymmetry - crossbite can cause deviation
what is the aetiology of a class 3 relationship
genetics plays large factor
environmental factor - cleft lip and palate, acromegaly
skeletal - mandibular prognathism, maxillary retrognathism
dental - reduced overbite, anterior crossbite, buccal crossbite, dentoalveolar compensation
how is the complexity of class 3 decided
number of teeth involved in anterior crossbite
presence of anterior open bite
skeletal discrepancy involved - ANB less than 0
when is a class 3 treated
aesthetic concerns
functional problems - unable to eat and speak
dental health concerns - gingival stripping, attrition, displacement on closing TMD problems
what treatment options are available for class 3
accept
growth modification - reverse twin block, restrict mandibular growth and encourage maxillary growth
URA - posterior bite plane, spring or screw plate to procline uppers over bite
fixed - procline uppers, retrocline lowers and correct OJ
orthognathic surgery
what is role of GDP in class 3
identify and classify, refer to specialist
produce URA when requested
what is the aetiology of the unerupted maxillary incisors
unerupted supernumerary preventing eruption
retained primary incisor
early loss of primary incisor
trauma to primary causing dilaceration of permanent root
crowding
ectoptic position of tooth germ
what systemic conditions are associated with unerupted
downs syndrome, turners syndrome, cleft lip and palate, rickets
how can an unerupted incisor be recognised
pattern of eruption - symmetrical - should appear within 6 months of condralateral
eruption pattern is out of sequence
how can an un erupted maxillary incisor be treated
accept - unlikely, poor aesthetics, risk of crown resorption
monitor - if less than 9 years old, apex open and chance for spontaneous eruption
if apex closed - surgical exposure and ortho gold chain and apply traction
what is the risk of leaving unerupted canines
root resorption of adjacent teeth
resorption of canine crown
ankylosis of tooth
cyst formation around crown
loss of deciduous and restorative options much more complicated when older
when might surgical removal of an unerupted canine be indicated
canine is not alignable
root resorption of adjacent teeth is clear
no risk of damage during procedure
patient is happy with appearance and doesnt want orthodontic treatment
what would indicate that canines are not alignable
too close to the midline
too high up - near the apical third of the incisors
the angle to the midsagittal plane is more than 55 degrees
what are the treatment options for unerupted canines
accept and do nothing
surgical removal
surgical exposure and fixed orthodontic treatment
autotransplantation
what are the benefits of ortho treatment
improved aesthetics - dental and facial, can improve QoL
improved function - mainly mastication if severe malocclusion
improved dental health
what is the IOTN and what is it used for
index of treatment need = to assess the need for treatment depending on the impact on dental health
what is the acronym used for IOTN
M - missing or impacted - risk of resorption or cyst formation
O - overjet - risk of trauma
C - crossbite - risk of tooth wear and recession
D - displacement of contact points - crowding or spacing, risk of caries
O - overbite - risk of gingival stripping
what are the most common risk of ortho treatment
relapse, root resorption, decalcification, periodontal health
name other less common risks of tx
soft tissue trauma, loss of vitality, enamel loss/tooth wear, allergy
what is relapse and what are the highest risk for relapse
the return of features of the original malocclusion following correction
high risk - lower labial segment, closure of spaced dentition (midline diastema), correction of rotation, reduced overjet but incompetent lips, reduced periodontal support
name diff types of retainers and their benefits
fixed bonded - compliance is not a problem, good for areas of high chance of relapse
essix - vacuum formed clear plastic, good aesthetics, well tolerated - should be worn daily for a week then overnight use
hawley - poor aesthetics but doesnt have to be removed for eating
what are complications with a bonded retainer
can de-bond without patient knowing, one tooth can then relapse
de-bonding can then act as plaque trap
difficult to clean and OH must be good to prevent calculus build up and periodontal disease
requires a lot of upkeep - fixing them and patient will have to pay
what is root resorption and what is normal root resorption
shrinking of the root, gets smaller
inevitable with tooth movement - 1mm of resorption after 2 year tx
what are risk factors for root resorption
root shape - blunt, pippette shape, short
previous dental trauma
habits - nail biting
large movements, long treatment, torque or intrusion
how should cases of high risk of root resorption be managed
screen for risk prior to treatment
if high risk - tx might not be completed fully, limit movements
monitor 6 months into tx with radiograph to check for root resorption
only radiographs after that is if unaccounted for mobility
what is decalcification
loss of calcium from mineralised tooth surface, it is the beginning of dental decay and can appear as a white spot, can be prevented by good OH and fluoride and it is reversible. if not adresed can lead to caries
how can decalcification be prevented
careful case selection - patients should not have treatment if high caries rate or poor OH
OHI - complete regime of brushing with F- tp, interdental brushes twice a day, also brush with normal toothbrush after every meal, use of F- mouth wash once a day, but not after brushing, spit dont rinse
diet advice - low sugar snacks, no fizzy drinks or juice, sugar limited to meal times
fluoride - high strength fluoride toothpaste, fluoride varnish, fluoride mouthwash, fluoride supplement
what are the risks to periodontal health with orthodontic treatment
gingivitis - most common, poor plaque control around gingival margin
gingival recession - if thin biotype, shrinks back from gum, sensitivity
periodontal disease - uncommon, should be stable and have excellent OH prior to tx
how does tooth movement occur with fixed appliance
light continuous force causes frontal resorption
pressure side - force acting upon it, hyperaemia of PDL, activates osteoclasts, causes bone resorption of lamina dura, allows PDL to move through
tension site - hyperaemia of PDL causes osteoblasts on this side, bone deposition and osteoid formed
remodelling of the socket and PDL reorganisation
what is the first step in the ortho emergency competence
describe the orthodontic appliance being used and what is is used for
what is the second step in the ortho emergency competence
patient safety - account for all the missing components
if unaccounted for and you are concerned - referral to A+E for chest x-ray to ensure it hasnt been inhaled - risk of lung perforation
what is acrylic creep and how is it solved
when you take a new impression of a patient midway through tx, the URA will be altered to this cast, but some acrylic can seep between appliance and cast causing creep and appliance will no longer fit the patient
solved by either using the original working cast if still available
or by taking an impression with the appliance in situ - when poured up the appliance will sit flush on the model
in what scenarios can acrylic creep be a problem
fractured adams clasp and requiring a new component
fractured south end clasp - requiring new component
how is a fractured adams clasp treated - completely fractured off
if beginnning of treatment - new appliance
if nearing end of treatment - smooth wire, check for hard edges and try in. If adequately retentive - leave
if not retentive - need new component. take imps of appliance in situ, send to lab asking for new adams clasp component
if a southend clasp is fractured at the flyover between central and lateral, how is it treated
too close to acrylic to soldier - flammable
cut at midpoint then bend back on itself - c clasp - retentive enough
if happened at start of treatment - new appliance
how are debonds of a fixed retainer treated
if just one debonded - smooth down with high speed and remove composite, check under wire for bacteria + caries
check wire work + ensure wire is flush and passive against tooth
etch, bond tooth and place composite back over wire - light cure
multiple debonds - wire has now become active - not fit for purpose. explain to patient why, remove rest of wire and composite. offer patient new one if within your scope, offer thermoplastic retainer in meantime. if nothing - ensure patient knows risk of relapse and get them to sign consent form
debonded on 3 and wire distorted. explain to patient why you cant rebond it - risk of tooth movement. cut it at distal to 2, smooth it off. provide thermoplastic retainer and tell patient to go to orthodontist for new one if required - risk of relapse on 3 if not
how would you treat wire slippage on a fixed appliance
slipped through on one side and short at the other. retentive tag at side it is short to prevent further slippage. cut it at other side to prevent trauma and retentive tag. tell patient to make an appt with orthodontist
how would you treat a URA that has been shattered extra orally
advise patient not to glue it back together, and dont wear it in its current state.
cant make new one as unsure of prescription. provide a thermoplastic retainer to freeze treatment and prevent relapse. make patient aware if they dont wear it, risk of relapse.
make appt with orthodontist
how would you treat a fractured adams clasp at arrowhead
can be soldered if facilities available - not close to acrylic
if not - modify it
cut it from baseplate, turn it back on its self to make a single arrowhead
or replace entire clasp - impression with appliance in situ
how would you fix a fractured transpalatal arch
needs to be removed
secure it first - floss around it and get patient to hold it
use high speed diamond bur with lots of water to remove it nearest the bands
get patient to make appt with orthodontist asap
how do you deal with brackets debonded from a fixed appliance
if circular wire - bracket will spin round it. risk of inhalation so needs to be removed. remove ligatures and give the patient the bracket - tell them to see orthodontist asap
if rectangular wire - bracket will just move side to side. doesnt need to be removed as no risk of inhalation. show the patient how to move the bracket for OH. tell them to make appt with orthodontist
how to deal with ura adams clasp fractured at acrylic
cant be soldered - flammable
cut adams clasp at corner of bridge
squeeze arrowhead - single arrowhead
or replace whole component - imps with URA in situ
how to deal with mobile molar band
GI cement has failed
cut wire between 5 and 6
remove band - give it to patient/parent
make retentive tag after 5
tell patient to make appt with orthodontist
how to deal with multiple missing brackets
ask how it happened - ensure story matches injury, no doubts for child protection
trauma stamp
remove wire - not doing anything
remove any loose brackets
give to patient
keep secure brackets
check for mobility - splint any mobile teeth - can use brackets for it
tell patient to make appt with orthodontist
how to deal with fracture in midline of southend clasp
could be soldered but too bulky - will rub
turn back on itself and squeeze to create 2 c clasps
