Lab techniques (3, 4, 5) Flashcards
URA
upper removable appliance
retract
move distal
space created by (2)
extraction
widen arch
overjet
horizontal
risk of trauma, function impaired, aesthetics, lip trap
overbite
vertical
anchorage
balance of forces
anchorage needed for 2 teeth movement
base plate sufficient
extension of base plate
is 7 erupted fully - half length of 7s
not all the way back to hard-soft palte - gag reflex issue (stronger in younger pt)
is overjet increases during tx - indicates
anchorage issue
southend clasp
anterior retention
engage undercut
components of palatal finger springs (4)
Zig zag tag embedded into acrylic
Coils – force exerted
Active arm – long arm around canine,
Goal post – guard – underneath the wire – allow active arm to slide along palate without rubbing – guideplane
posterior rentention classically by
adam’s clasp on 6s
9 advantages of removable orthodontics
- Tipping movement
- Anchorage – large baseplate
- Cheaper than fixed
- Shorter chairside time needed
- Good oral hygiene maintenance
- Non-destructive to tooth – no need to prep, no etch
- Less specialised training required to manage
- Can be easily adapted for overbite reduction
- Can achieve block movements
5 disadvantages of removable orthodontics
- Less precise control of tooth movement – cannot 3D movement - extrude, intrude tooth, keep angulation but move in palate
- Can be easily removed by the pt - only work when in the mouth
- Generally 1-2 teeth can be moved at one time – don’t want to compromise the anchorage
- Specialist technical staff required to construct the appliances
- Rotation very difficult to correct
how do teeth move in orthodontics
The force exerted creates pressure this causes the bone around the tooth to be remodel
- Remodelling - process where a bone is selectively removed in some areas and added in others
controlled by the periodontal ligaments or fibres (PDL) the PDL is a collection of fibres surrounding the root which act as a buffer against shock
- PDL shock
- Osteoclasts and osteoblasts activated
aim for
Retract canine (1st premolars extracted already), 6mm overjet (OJ), Reduce overbite (OB)
please construct URA to retract 13 + 23 and reduce overbite (OB)
ARAB for
Aim - please construct URA to retract 13 + 23 and reduce overbite (OB)
A – 13+23 palatal finger springs and guards, 0.5mm HSSW
R – same
A – same only moving 2 teeth
B - self cure PMMA
overbite tackled in URA how
base plate modification - flat anterior bite plane (FABP) OJ + 3mm
why can you not move all anteriors at one (if need to move 3-3)
compromise anchorage
FABP use
overbite
how to FABP reduce overbite
Lowers inhibit anteriors coming back
- don’t bend teeth need to change whole angulation
Lower anteriors bite against the platform
- Creates space/ posterior open bite
- posteriors will want to continue to erupt to continue being in occlusion
- still want bone and soft tissue around them
- lowers come up, upper do not as of appliance
- still want bone and soft tissue around them
Only works in young as bone form around
- otherwise roots get exposed = sensitive, unaesthetic, unstable
why is FABP OJ + 3mm
negative - bigger, bulkier, more invasice, less well tolerated by pt
but if not
Pt will retrude jaw – go inadvertently behind biteplane
- Retrocline lowers so increase overjet
11 uses of study casts
- Look back on treatment to show pt changes – progress
- Teaching purposes
- Pt motivate – where you have been and going
- Design appliance on it
- Study pt occlusion outwith pt presence – diagnosis
- Legal reasons
- Forensics
- Explaining treatment to pt
- Second opinion
- Retrospective studies
- Consent decision by pt more informed
retentive
resist displacement forces
go into undercuts
3 retentive components
adam’s clasp
southend clasp
labial bows
wire gauge for retentive components
0.7mm HSSW (permanent teeth)
0.6mm HSSW (primary teeth)
palatal acitve components (4)
finger springs + guard
Z-spring (double cantilever)
flapper spring
T-spring
palatal active components location
in palate - have acrylic over them - well protected
wire gauge for palatal active components
0.5mm HSSW
2 buccal active components
buccal canine retractor
roberts retractor
wire gauge and explanation for buccal active components
0.5mm HSSW; 0.5mm I.D. tubing
easily distorted so add sheating on top to increase strength and rigidity
stops role
passive
prevents relapse after active movement (mesial drift)
DOESN’T RESIST DISPLACEMENT FORCES
wire gauge for stops
0.7mm HSSW (flattened)
this is
adam’s clasp
0.7mm HSSW (0.6mm on deciduous teeth)
retentive
this is
southend clasp
0.7mm HSSW
retentive
this is
labial bow
0.7mm HSSW
retentive
buccal retactors (active component) wire
mesial aspect is thinner than distal aspect as distal aspect as 0.5mm I.D. tubing to protect it from being deformed
this is
finger spring + guard
0.5mm HSSW
active
this is
z sping
0.5mm HSSW
active
this is
flapper spring
0.5mm HSSW
active
this is
T spring
0.5mm HSSW
active
this is
buccal canine retractor
0.5mm HSSW; 0.5mm I.D. tubing
active
this is
roberts retractor
0.5mm HSSW; 0.5mm I.D. tubing
active
fitting a URA
10 stages
Disinfected ready to fit – in passive state
- Ensure the pt details match the details supplied for the appliance
* Check – right appliance for right pt - Check the appliance matches the design specifications – human errors
- Inspect the appliance and run your finger over all surfaces looking for sharp or potentially traumatic areas
- Check the integrity of wirework
- insert the appliance into the pt mouth, immediately looking for areas of blanching or soft tissue trauma – pain, stop wearing it
- check the posterior retention (Adam’s clasp)
* firstly flyovers, then arrowheads are correctly engaging the appropriate undercuts - apply the same principles to the anterior retention
- activate the appliance (1mm movement approx. per month)
- demonstrate to pt the correct procedure for insertion and removal of the appliance
* ensure that the pt demonstrates this correctly - book a review appointment 4-6weeks (need to reactivate the active component - 1mm movement done)
what to check wirework for
damage or work hardening
- bend one way than other – no flexibility = snaps on movement
- through trimming stage – easier to spot areas of damage – different diamete
- shine from chromium and prevents corrosion
- lost on damage = corrode (black area), break
aim for URA if want to
retract buccal placed canines, 1st premolars extracted, 6mm (OJ), reduce (OB)
aim - please construct a URA to retract buccally placed 13 + 23 and reduce OB
active component for
aim - please construct a URA to retract buccally placed 13 + 23 and reduce OB
13+23 buccal canine retractor, 0.5mm HSSW and 0.5mm ID tubing
- two lines (highlight tubing)
- wirework distal to premolar so not inhibited in area
finger spring only distal but need distal and palatal to get in line of arch
retentive component for
aim - please construct a URA to retract buccally placed 13 + 23 and reduce OB
16 + 26 Adam’s clasp; 0.7mm HSSW
11 +21 Southend clasp; 0.7mm HSSW
anchorage for
aim - please construct a URA to retract buccally placed 13 + 23 and reduce OB
good as only moving 2 teeth
baseplate for
aim - please construct a URA to retract buccally placed 13 + 23 and reduce OB
self cure PMMA
with Flat anterior bite plane OJ + 3mm
where to draw extension of base plate to
if 7s erupted
extend half away across 7s
when to use a palatal finger spring and guard or buccal canine retractor
Palatal finger spring – canines in line of arch
Buccal canine retractors – to move back and in line
10 points pt information and intructions for URA
- appliance will feel big and bulky (this is normal, and they will get used to it quickly)
- may causes initial excessive salivation (this will pass in 24 hours – normal)
- may impinge speech for a short period of time (practise reading a book aloud at home and this will subside – don’t want them to be teased)
- may cause initial discomfort or ache or pressure (this is normal, and indicates that the appliance is working)
- to be worn 24/7 including meal times and sleep - using masticatory forces to advantages
- remove after every meal and clean with a soft brush (warm water and soap)
- remove and store in a protective container when participating in contact or active sport (sharp intake of breath - running, swimming)
- avoid hard or sticky foods that may damage the appliance and be cautious with hot food and drinks
- not feel initial heat – appliance is insulator – not feel until to get to back of throat
- missing appointment and non-compliance will significantly lengthen treatment time
- provide emergency contact details in case any problems arise
issue of anterior crossbite (2)
aesthetics - dark hole due to light refraction
self concious
aim for appliance if 12 in anteiror cross bite
please construct a URA to correct an anterior crossbite on 12
active component for
Aim – please construct a URA to correct an anterior crossbite on 12
12 Z-spring, 0.5mm HSSW
(double coils a.k.a double cantilever spring; large amount of displacement force)
rententive for
Aim – please construct a URA to correct an anterior crossbite on 12
16+26 Adam’s clasp, 0.7mm HSSW
14+24 Adam’s clasp, 0.7mm HSSW
anchorage for
Aim – please construct a URA to correct an anterior crossbite on 12
good only one tooth moving
baseplate for
Aim – please construct a URA to correct an anterior crossbite on 12
Self cure PMMA
Posterior bite plane
why need for posterior bite plane in tx anterior Xbite
- Lower teeth will prevent the 12 moving forward
- create a temporary anterior open bite to allow tooth to move forward without obstruction
- incorporate all teeth prevent continuing to erupt
Overjet from Z spring
Natural retention from lowers
why do anterior teeth not over erupt in posterior bite plane use
Anterior teeth don’t occlude naturally together in humans
(unlike rabbis and rodents – continue to erupt – need to continue to gnaw to prevent not being able to open)
restorative use of posteiror bite planes
clinicians posterior bite planes to allow continued eruption to anterior teeth
- E.g. not reached maximum eruption level
Z spring can do
small amounts of rotation in URA
Helpful to get into line of arch when fixing anterior cross bite – protrude and rotate
- Straight forward – activate both coils equally
- Rotate to left = activate left coil more
- rotate to right = activate right coil more
move forward on a twist - like door
first step in drawing URA design
cross out teeth to be extracted/missing
buccal canine retractor distal placement
place as far back as you want canine to move to (e.g. mesial 5)
coil for active components
need to be on mesial aspect
so does the guard for finger springs
mesial stops
mesial aspect canines – naturally want to relapse
Stops are passive
- no active force applied
- do not resist displacement forces (not retention)
- not anchorage or baseplate (prevents drift forward)
Flattened – so not taking up a large amount of space
robert’s retractor
Active component
- But positioned in upper anterior undercut so resist displacement forces (by product)
Only use when have proclined upper anterior teeth
retention for URA with robert’s retractor
16+26 Adam’s Clasp; 0.7mm HSSW
- Cannot place southend*
- interfere with active components and fixate them where they are so prevent the active component action
- but have anterior retention as by-product of roberts retractor*
anchorage discuss for this URA
moving more than 2 teeth here (as 4)
- not perfect but can get away as 4 anterior as 4 shortest rooted teeth in upper arch so have posterior teeth and baseplate
how to continue to reduce OB
When bringing canines back by applying actual active force move quicker than teeth naturally eruptingposterior teeth
- new bone is soft needs to thicken
so if remove FABP at once then when bite down relapse as teeth sink back in
-
Take a small amount FABP anteriorly away in small increments
- Trim at a slant to follow the shape of the tooth
Lower teeth wont get stuck as less likely to lower jaw forward
- Moves backward naturally
why can a posterior bite plane not be used to continue to reduce OB
no use as relapse in few weeks as lowers press force on upper anterior as space posteriorly jaw want to resolve
- Drop down when takeout bite plane
- lower teeth contact above cingulum – relapse
URA get tipping or tilting
- So incisal edge of upper will lower when moving back – increases OB
Need to continue to reduce OB whilst moving anterior back
when may want to expand upper arch
to create space e.g. posterior cross bites
aim for expanding upper arch as posteiror cross bite
Aim – please a construct a URA to expand the upper arch
active component for
expand upper arch
midline palatal screw
retention for
expand upper arch
16 + 26 adams clasps; 0.7mm HSSW
14+ 24 adams clasps; 0.7mm HSSW (if deciduous 0.6mmm)
anchorage for
expand upper arch
reciprocal
reciprocal anchorage
Force equal on both sides – newtons 3rd law
To cancel out force need counteract the force in the other way
reciprocation in RPD
force on one side, reciprocal side arm to prevent unwanted tooth movement
baseplate for expansion upper arch
Self cure PMMA
- Needs cut in half down midline around screw
- Only held together by screw
posterior bite plane
lingual cross bites
posterior teeth biting on inside lowers instead of outside
problem with occlusion when expanding upper arch in post Xbite
Cusp to cusp – cuspal interference
- Inhibit movement of uppers
- Lowers can expand to – dragged with uppers
Want to relieve interference between uppers and lowers
- Posterior bite plane
- Must include all posterior teeth – so none continue to erupt
Not flat anterior bite plane – posterior teeth continue to erupt
- only used for overbite
posterior bite plane
relieve occlusal interference of uppers and lowers when expanding upper arch
must include all posterior teeth so none continue to erupt
flat anterior bite plane
posteiror teeth will continue to erupt
only used for OVERBITE
midline palatal screw relies on
Need pt compliance
- Demo to them and they demo them back to you
1 turn a week ->0.25mm a week (1mm a month)
- move teeth with osteoclastic and osteoblastic action around teeth
rapid maxillary expansion
similar but bonded onto teeth (turn couple times a day), fracture the midline suture
not tooth movement
why is diastema not created in upper arch expansion
Usually have cross over crowding so won’t get diastema
- give space to move teeth into correct alignment
modification for device if only expanding one quadrant i.e. unilateral posterior cross bite
cut different - emphasise effect on that quadrant
minimal expansion on other side
can’t move screw greatly due to curvature of the mouth
modification if dont want to expand anterior teeth region only posterior teeth region
remove base plate in anterior region
- cut distal to canines
wire bending
Hold pliers in dominate hand
- Counteract to straighten with pinch finger down
- Bend away from face and others
Cut with wire cutters – hold onto both ends to prevent ping away
adam’s clasp components (5)
Bridge – buccal away, lift in and out
Arrowheads – engage undercut, functional part
Flyover – between teeth so not interfering with occlusion
Leg – 0.5-1mm between palate and wire– inside baseplate – completely encompassed
Tag – 0.5mm to prevent slippage (mesial direction for distal leg to prevent sticking out back of baseplate)
aim for wire after manipulation
Shine
- chromium – needed – resistance to corrosion
Want minimal bends
- metal fatigue or work hardened
bridge of adam’s clasp
buccal away, lift in and out
arrowheads of adam’s clasp
engage undercut, fuctional part
flyover
between teeth so not interfering with occlusion
leg of adam’s clasp
0.5-1mm between palate and it
so inside baseplate - completely encompassed
tag of adam’s clasp
0.5mm to prevent slippage
(mesial direction for distal leg to prevent sticking out baseplate)
pro and con of digitised study casts
can be shared easily
not same feel for occlusion - used as addition not replacement
2 cons of physical study models
storage - need 12 years for legal
damage - fracture, attrition - render useless
12 uses of study casts
- Before and after treatment
- Medicolegal records
- Second opinions
- Study occlusion when pt not there
- Teaching
- Motivation
- Forensics
- Legal reasons - 10-12 years
- Tx planning
- Waxing up
- Diagnosis
- More informed decision for pt
- Retrospective studies
stainless steel 5 elements
iron
chromium
titanium
carbon
nickel
% iron in stainless steel
72
% chromium in stainless steel
18
% titanium in stainless steel
1.7
% carbon in stainless steel
0.3
% nickel in stainless steel
8
this is
adam number 64 pliers
this is
adam number 65 pliers
this is
wire cutters
