ortho 5 zoom notes Flashcards
how would you reduce a 6mm OJ 22, 21, 11 and 12 and reduce the OB
ie do the appliance design
extract 1st premolars
aim: please construct a URA to reduce (OJ) 22, 21, 11 + 12 ~ reduce OB
Active Component: 22, 21, 11, 12; Roberts retractor; 0.5mm HSSW + 0.5mm I.D. tubing
stops: 13 + 23; medial stops; 0.7mm (flattened) HSSW
retentive: 16+ 26; Adams clasps; 0.7mm HSSW
anchorage: moving 4 teeth (yes and no)
baseplate: self-cure PMMA, flat anterior bite-plane (FABP); overjet + 3mm
why would you expand the upper arch
crowding
posterior cross bite
what is the active component when expanding the upper arch
midline palatal screw
what sort of retention can we use when we want to expand the upper arch
Cannot use a southend clasp as it would inhibit expansion by holding the teeth together
A labial bow also has the potential to inhibit this expansion (could also potentially cause the arch to flatten) ~ not impossible but not the best
Adam’s clasps for posterior and anterior retention are the best choice (utilise the molars and premolars)
if you are expanding the upper arch and the patient needed retention on deciduous teeth which thickness of wire would we use
0.6mm
what sort of anchorage do we have when expanding the arch
reciprocal anchorage
ie what happens on one side the same thing will happen on the other side (Newton’s 3rd law)
= expansion on one side happens the same on the other side
we are using the face that we don’t have anchorage to expand the upper arch
what is different about the appliance to expand the arch
Get a saw and cut appliance exactly down the middle to the screw
Only component holding 2 sides together is the screw
Give patient a little key to activate it themselves once or twice a week
how much tooth movement do we normally want per month
Usually we want 1mm tooth movement per month
when the patient activates their appliance how much movement do we want per week
If we get patient to activate it themselves we are looking at 0.2-0.25mm per week
what is added to the base plate if the patient has a posterior cross bite
posterior bite plane
what happens if we only want to expand the upper left posterior quadrant
We can change where we do our cut on the appliance
Based on newtons law
Only moving 4 teeth (segmental movement)
So there is considerably less movement on the other teeth
Greater subject of force on 4 teeth and the rest of the force is spread over more teeth
Get 4mm to the left and maybe 1mm in the other direction
Dissipating the force
Kind of like tug of war
More force on one side than the other then it will go to the side with more force
How can we move posterior teeth and not the anterior teeth?
Just don’t include anterior teeth and get your base plate to finish before anterior teeth
what is bi-expansion
= equal expansion on both sides
what do we need to include on the bite plate if we only want to move one side and why
If we only want to move one side then we need to include the anteriors to get greater anchorage force
what are % of elements in satin steel
0.3% carbon
72% iron
18% chromium
1.7% titanium
8% Nickle
