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











































