Test #3 Flashcards
In ortho, the bond b/w the bond and the enamel is chemical or mechanical
mechanical
Dr. Angle introduced what appliance, when
Edgewise, 1928
Dr. Andrews introduced what appliance when
Modern straight wire appliance, early 1970s
Edgewise appliances character
Fixed, multibanded, bonded appliances with multiple wire bends
What was required in the wires for the Edgewise appliance
1st order, 2nd order, 3rd order bends
First order do what to teeth
rotate
Second order do what to teeth
intrusion/extrusion
Third order do what to teeth
torque buccal/lingual
Synonym for first order bends and how are they directed
In Out Bends, labio-lingual offsets on archwire in the horizontal plane
Synonym for second order bends and how are they directed
Tipping Bends, offsets on archwire in the Vertical plane to change angulation mesio-distally
Synonym for third order bends and how are they directed
Torquing Bends, placed in a rectangular archwire to change bucco-lingual or labio-lingual inclination of a tooth
How do Straight wire appliances work
prescribed for individual tooth with a certain thickness base and angulation of the slot to the long axis of the tooth both in the M-D and B-L all incorporated into the bracket
Theory of straight wire appliance
No need for 1st(rotating bends), 2nd (tipping bends), or 3rd (Torquing bends) order bends in the wire
Do orthodontists still do bends w/ straight wire appliances
yes, do finishing bends and detailing bends b/c teeth do not have ideal anatomy
Contemporary Fixed appliance set up
stainless steel bands and bracket
Stainless steel bands usually put on which teeth
Molars and second premolars
3 general types of contemporary brackets
Metal, Ceramic, Self-Ligating
What can metal brackets be made of
Stainless Steel, titanium, gold
Advantage of ceramic brackets
esthetics
What are self ligating brackets
special locking mechanism built on the bracket to engage the archwire in the slot eliminating the need for ligature
What is a ligature
the rubber o-ring that holds the wire in the bracket
2 most commonly used bracket slot sizes
0.018 X 0.025 “ 0.022 X 0.028 “
Band definition for the layman
metal that surrounds the whole tooth
Bracket for the layman
little piece that sits on the front of the tooth
When see bonding in Ortho should think what
putting bracket on the facial of a tooth
What has allowed brackets to be placed as far back as the molars
direct bonding technique
What attachments are preferred for the anterior teeth
bonded
What attachments are preferred for the premolars and molars
banded or bonded
Which is more complicated banding or bonding & why
Banding because it requires tooth separation, fitting of the band, and cementing the band
Purpose of Separation
slightly loosen tight interprox contacts b/w teeth to create space to fit bands at the following appointment
How long separation in children
1 week
How long separation in adulst
2 weeks
Most popular separator
elastics
What separator to use w/ tight interproximals
brasswire and metal springs
Is band one size fits all and does it have
attachments
No, they are preformed w/ prewelded attachments
General fitting of the band
you are stretching the stainless steel band over the tooth so that it is tight, but not so tight as to break it
2 most common cements used to cement the bands
Zinc phosphate Glass ionomer
Why are glass ionomer cements popular
elease fluoride ions to help minimize decalcification
how is bonding achieved in ortho
mechanical locking of adhesive to surface irregularities in enamel and to the meshed base of the orthodontic bracket
3 steps of bracket bonding
etch Prime
Place resin loaded bracket and light cure
Etch w/ what material
37% phosphoric acid
Purpose of etch
create surface irregularities on enamel to enhance bonding
What do self-etching primers do
combine etch and prime steps
What are “tooth size problems “
when there is space to adjust but not so much as to need tooth removal
how fix tooth size problems
can go interproximally and shave off enamel (up to 3mm ?)
Why are brackets good for ortho “tooth size” problems
leave the interproximal surface accessible for modification
Which are less prone to irritate gingiva or cause white spot lesions, bands or brackets
brackets
If tooth will receive heavy intermittent force against attachments (e.g. max first molar w/ headgear) what is placed, band or bracket
band
If tooth will need both labial and lingual attachments (e.g. teeth requiring crossbite elastics) what is placed, band or bracket
band
If tooth has short clinical crown is band or bracket placed
band
If tooth surface is incompatible w/ bonding, what can be placed
band
Example of a tooth surface incompatible w/ bonding
restored tooth surface
Example of a tooth surface incompatible w/ bonding
restored tooth surface
3 archwire materials
Nickel titanium Beta titanium
Stainless Steel
2 archwire forms
Broad
Regular
3 cross sections of archwire
Round Square
Rectangle
6 cross-sectional sizes of archwires
- 014” 0.016” 0.018”
0. 016 X 0.016” 0.016 X 0.022” 0.016X0.025”
What 2 things are archwire selection based on
Treatment philosophy Stage of Treatment
typical nickel-titanium archwire composition
55% Nickel, 45% Titanium
2 properties NiTi archwir
shape memory Superelasticity
The superelasticity of NiTi is based on what
phase transformation from austenitic to martensitic and back
is thermoelasticity the same as superelasticity
No thermoelasticity is a phase change based on heating or cooling. Wire is heated, bent, and when cooled, it maintains that new bended form
What is Superelasticity
Phase change due to the application of stress
what is the stress applied to superelastic NiTi archwire
pushing the archwire into the bracket
What phase is a NiTi straight out of the package, unstressed, in, austenitic or martensitic
Austenitic, stiff
Stressing the NiTi into the bracket makes it more pliable, which is what phase, austenitic or martensitic
Martensitic, pliable
How do the differences in stress work on a NiTi in ortho
as the tooth moves the stress on the NiTi lesses so it goes from martensitic(pliable) to Austenitic(stiff) until it is back to its original archform
Wire resumes its original shape upon deflection ,low formability
Shape memory, NiTi has high shape memory
Low stiffness means the wire is flexible or rigid
Flexible, NiTi is Highly flexible
Revovery exhibited by wire upon its unloading/deactivation
Springback, NiTi has high springback
Maximum deformation/deflection of an orthodontic wire w/in its elastic range
Range, NiTi has high range
Is NiTi high or low friction and is this a disadvantage or advantage
High friction, it’s a disadvantage, can cause translation to go slower due to friction in bracket as tooth moves
3 disadvantages of NiTi
High Friction, Can’t be soldered, Expensive
NiTi is used in what phase of ortho treatment and why
Initial stage, deliver light continuous forces w/ large deflections
Does Beta-Titanium wire have any Nickel in it
No
Beta-Titanium arch wire composition
9% Titanium (Ti)
11% Molybdenium (Mo) 6% Zirconium (Zr)
4% Tin (Sn)
How does Beta titanium relate to NiTi and Stainless
Steel
Stronger than NiTi but weaker than SS
Force level of Beta-Titanium versus for Stainless Steel for same amount of deflection
BTi has 1⁄2 force level for deflection as Stainless Steel
2 indications for using Beta-Titanium over Stainless Steel or NiTi
Pt has a Nickel Allergy
Pt requires force levels lower than SS but greater
than NiTi
What are the Springback, Range, and Friction for BetaTitanium, High or Intermediate
Intermediate
Can Beta-titanium be soldered or welded
Yes
Considered the main arch wire in most orthodontic practices
Stainless Steel
Stainless Steel composition
71% Iron (Fe)
18% Chromium (Cr)
8% Nickel (Ni) <0.2% Carbon ©
When would use Stainless Stell
finishing
3 reasons for Stainless Steel popularity
Good mechanical properties Corrosion Resistant
Low cost
Because it is highly formable, what does that mean for Stainless Steel wire
bends will stay in the wire
What is the Springback and Range of Stainless Steel, low, intermediate, or high
Low
Initial Stage ortho main goal and wire of choice
Intraarch level and align, NiTi
Initial stage goal stated differently
Take care of all rotations (1st order), intrusions and extrusions (2nd order) in the arch, not focused on spaces
Intermediate stage focus
space closure
What is required for space closure in Intermediate Stage
need greater control of tooth movement for interarch correction while providing intraarch stability
Wire choice for intermediate stage
SS or BTi
Finishing stage is called
Detailing
Wire choice for finishing stage
SS or Bti
If see a chain elastic, what is that used for and what can be assumed is the wire type it covers
used for space closure(intermediate stage), so must cover a SS or BTi
Elastics do what
help w/ tooth movement
Elastic types
Class I Class II
Class III Cross Elastics Box Elastics
Elastics require what for patient success
Patient cooperation
Elastic traction b/w teeth or groups of teeth of the same arch (e.g. during canine retraction using sliding mechanics)
Class I elastics
Elastics extending from the anterior aspect of the maxillary arch to the posterior aspect of the mandibular arch
Class II elastics
Class II elastics used for
Correct CII malocclusion Reduce overjet
Minimize anchorage loss during max incisor retraction by taking advantage of intermax anchorage
If elastic goes from Max Canine to Mand Mol in Class II elastics, what will each tooth do
Max canine pulled distal and will partially extrude, Mand mol pulled mesial and partially extrude
Class II elastics correct class II malocclusion how
pull maxillary teeth back and mand teeth fwd
What is a side effect that must be managed w/ class II elastics
Extrusion
Elastic from Mandibular Canines to Max first molars
Class III elastics
Class III elastics used when
aid Class III malocclusion correction Facilitate protraction of Max Post teeth
Improve incisor relationship in edge to edge situation
What do max mol and mand canine do in CIII elastics
Max mol moves forward, ,mand canine moves back and both extrude
2 cautions for both Class II and Class III elastics
create vertical force which may open bite Move anterior teeth forward (flaring)
When Class II elastics are used, which anterior teeth will flare
Mandibular anterior
Intermaxillary elastics in various configurations used to close open bites by extruding teeth
Vertical Elastics
2 configurations of Vertical Elastics
Triangular or Box
Elastic extending from the palatal aspect of a Max tooth to the Buccal aspect of a mandibular tooth (or reverse)
crossbite elastic to correct crossbite
Problem w/ crossbite elastic
crosses occlusal table so pt bites on it
What would an elastic that goes from Right Maxillary Canine across to the Left Mandibular Canine be doing
anterior elastic to bring midline back
Comprehensive Orthodontic treatment typically begins when
at or after late mixed dentition
3 Goals of Comprehensive Ortho
Function Esthetics
Stability
Treatment is hardline or compromise
Compromise of function/esthetics/stability for result that is most attainable and maintainable
3 functional Goals
Dental/Skeletal/ Soft Tissue
Function Dental Goals of Comprehensive Ortho
Class I canines
Normal Overbite/Overjet (2mm/2mm) Canine or Group function guidance
No crowding or spacing
Function Soft tissue Goals of Comprehensive Ortho
Lips close w/ minimum strain Balanced soft tissue
