Evolution of straight wire appliance /certified fixed orthodontic courses by Indian dental academy

Evolution of
Straight wire appliance,
transition from Edgewise
&
Bracket placement.

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INDIAN DENTAL ACADEMY
Leader in continuing dental education


Introduction
Introduced – 1970.
“sophisticated edgewise appliance”.
It seeks to build as much treatment in the
appliance as practical.


Evolution of the bracket.
 Edgewise Appliance:
Angle’s - edgewise appliance - place the teeth
according to - ‘line of occlusion’.
metal bracket - rectangular slot- 0.022 x 0.028”.
Original soft gold bracket - easily deformed by
the forces of occlusion & ligature wires
The original design - modified - slightly larger
bracket- tying area under the wings.

Single Width Bracket :
narrow width - ineffective tooth
rotation. Angle, - gold eyelets on the orthodontic bands.
Two brackets-single tooth.

Twin Brackets :
two edgewise brackets on a common base.
‘Siamese twin bracket’ by Swain
Space between two brackets - 0.050 inch =
width of one bracket.

The bases - curved to conform - curvatures of
the canines &PM.
some deflection of the bracket from the basepresent –controlled to a great extent .
This bracket offers ‘positive control’ on the tooth .
Disadvantage.
Interbracket span is greatly reduced causing
decrease in resiliency of wires .


Lewis Bracket :
Lewis soldered auxiliary rotation arms.
abutted against the bracket itself - lever arm
-deflect the archwire and rotate the tooth.

Vertical Slot Lewis Bracket :
A vertical slot 0.020 x 0.020 inch.
Uprighting springs - correct axial inclinations

Steiner Bracket :
Flexible rotation arm.
The flexibility - arms - a rotational effect .

Broussard Bracket :
Graffard Broussard –
0.0185 x 0.046 inch vertical slot –
accept a doubled 0.018 inch auxiliary wire

Later modifications:
Burstone modified canine bracket a vertical tube - retraction assemblies.
Edgelock Bracket and Hanson Speed
Appliance Bracket :
These brackets eliminate the need for
ligature ties as they possess self ligating
mechanism.

Holdaway - 1952
angulated brackets on the teeth adjacent
to extraction spaces:
aid in paralleling the roots .
setting up posterior anchorage.
obtaining correct axial inclinations or ‘artistic
positioning’ of the teeth.

John J. Stifter -1958
U.S. patent - designing an edgewise
bracket comprising a male and female
component

Female part - attached to the tooth.
Many interchangeable male components –
various - inclination , angulation and prominence.
First edgewise bracket - guidance into all three
planes of space .
did not address optimal tooth position &
too many separate parts - needed .

Ivan Lee -1960:
Torqued slots - regional and basic
edgewise bracket.
to eliminate - adding torque - anterior portion of
the upper archwire.

Manufacturers – 1960:
raised the base of lateral incisors.
Raised bases eliminated the need for
lateral offset bends.
Jaraback – 1963:
described the use of torqued brackets

Andrews Straight Wire Appliance - 1970.
two varieties .
The standard prescription for non extraction cases
& ‘Translation series’ for extraction cases .

Roth -1976:
bracket set up containing modifications of tip ,
torque and rotations.
purpose of Roth - over corrected tooth positioning.
 appliance in position - impossible to position the
teeth precisely into occlusion.
After appliance removal –
the teeth will shift slightly.

Alexander – 1983 :
Vari – simplex discipline .
Vari - variety of bracket types used ;
simplex - KISS principle. ( Keep it Simple Sir )
Discipline was chosen rather than the appliance.

Creekmore -1993: slot machine .
Slot machine - solution to the
inaccuracies of bracket placement ,
anatomic and biologic variations ,


over correction for tissue rebound and relapse
and
mechanical differences of preadjusted edgewise
orthodontic appliance

It orients - archwire slot - relative to the facial
surface of each tooth on the model .
Craig Andreiko – 1994:
Elan and Orthos system .
Represent for the first time the modern CAD / CAM
( Computer aided design / computer aided
manufacture ) technology .

Straight wire appliance – 1970 – Lawrence
F Andrews.
Origin of appl. & Six keys – interrelated.
Series of five studies.
1st – 1960 – examination of post trt. dental
casts – asses state of art – static occl.
2nd – 1964 – casts of dentitions – naturally
occuring optimal occl. 120 samples –
collected.
Never subjected to ortho trt.
Aligned & pleasing
Excelent occlsn.
Would not benefit from ortho trt.

3rd – most imp step  fully programmed appl.
Discovery – six keys to optimal occlsn.
4th – measurements – crown in 120 cast
sample.
- supply data – consistency – shape & position
of each tooth type
consistency – relative size – within an arch.
Help in design – new appl.

5th study – established need – for fully
programmed appl.
1150 – post trt. dental casts – compared –
non orthodontic sample – occlusal
characteristics.

Andrews –

Non Programmed appliance &
Fully programmed appliance.
Non Programmed Appliance:
Set of br. - same design for all tooth types.
wire bending - achieve optimal posn. –
individual tooth.
Fully Programmed appliance:
Set of br. – guide teeth – goal posn. –
unbent archwires.

Non Programmed Appliance:
Design short comings.
Six factors.Each factor –
Slot misdirected > 2°, optimal angulation &
inclination.
> 0.5 mm occluso gingivally, Mesio distally, Facio
lingually.

Factors are:
Br. Base perpendicular to br. Stem..
Br. Base not contoured occluso gingivally.
Slots are not angulated.
Br. Stem – equal facio lingual thickness.
Max. molar offset not built in.
Bracket siting tech. – unsatisfactory.

 Perpendicular bases.
Base per. – F-L axis of stem.
Each crown – its own optimal inclination.
Br. When sited – base point to FA point of
each crown –
target slots – that many difft. inclinations &
occluso gingival levels


Bases not contoured occluso gingivally:
Br. Unintentionally rocked – occl. Or
gingivally.
Potential inclination range - > 2°
Occluso gingival range - > 0.5mm.


 Mesio distal contour:
Partly
contoured base

Flat base


 Slots not angulated.
 When located on FACC’s & FA points of optimally
positioned crowns – slot angulations & Occl – gingival posn.
– not harmonious with Andrews plane.

To correct angulation – 2nd order bends
requd.
To eliminate bends – angulate br.
It

incln.& occluso gingival range – slot

siting.


 Stems of Equal
prominence.
Dist. From br. Base –
centre of slot – same in
each br.
Slots & teeth – irregular in
facial prominence – teeth
are optimally positioned.
Edgewise


SWA

Max. molar offset not built in.
mid sagittal planes – crowns & slots – not
coincidental for max. molars.
MB cusp – prominent facially.
So Mid sagittal plane of stem & slot –
angular to mid sagittal plane of crown.

Fully programmed standard bracket.
Concept of programming tooth guidance
into br. based on – extensive similarities –
Morphology – normal tooth types.
In posns. – optimal occlusion.


 Design – emanates – slot
site.

Slot site – “the area that the
bracket slot must occupy if
it is to passively receive a
full size and unbent
archwire when a tooth is
optimally positioned.”

Fully programmed std. Br.
Include:
Slot siting features.
Convenience features.
Auxiliary features.


Slot siting features
– explained from perspective – planes of
individual teeth & br.
 Mid transverse plane.
Separates crowns occl. half form gingival half.
It should coincide with MT plane – slot.


To achieve this –
Feature 1: MT plane of slot, stem & crown
same.
Feature 2: base of br.- same inclination –
facial
plane of crown – FA point.


Feature 3: Inclined base – contoured occlusogingivally –
curvature of the crown.
These three eliminate the need for:
2nd order bends – occluso-gingival disharmony.
3rd order bends – inclination.


 Midsagittal plane.
Midsagittal plane of each slot – facial extension of
crowns – mid sagittal plane.
To achieve this:
Feature 4;
Midsagittal plane of the slot, stem of the crown same.


Feature 5:
Plane of br. Base – base point – identical to the
facial plane of crown at FA point.
In max. molars – 100.
In all other teeth – 90 to mid sag. Plane


Feature 6:
Base of each br. – contoure to match – Md
radius of area of crown – designed to fit.
Feature 7.
Vertical components ( Mesial & distal
borders of br. Stem & tie wings) –
designed to parallel one another.
Horizontal components –
When sited equidistant – gingiva & cusp tip
–Base point – mate with crowns FA point.

Midfacial plane:
Of each slot – must superimpose – crowns
prominence plane.
Feature 8.
In an arch – all slot points – same dist. – from
crowns embrasure line.

Convenience features.
A design feature – facilitates – use by
orthodontist or promotes comfort for the
Patient – does not contribute to biological
aspect of trt. Or targeting the slot.

Machining procedures – not suitable.
Complex design – casting & molding –
practical manufacturing process.
Gingival tie wings – post. Br.- extend
farther laterally – easier ligation &
eliminates gingival impingement.

Facial surfaces – incisor & canine br. –
designed to // their bases – in turn // crowns’
faces. – lip comfort.
Mand. Incisor br. – least occlusofacial
prominence.-

occl. Interference.

Br. Identification.


 Gingival wings of posterior brackets, in SWA, are
stepped out. Results: easier ligation and less frequent
gingival impingement.

Auxiliary features.
Contribute to biologic aspects of trt.Power arms, hooks, facebow tubes, utility
tubes & rotation wings.
Incisor brackets:
Inclination range > for other teeth.
Three std. Br. – difft. Base inclination.
Used according to anticipated jaw relation:
Class I, Class II or Class III.

Posterior brackets:
Except for max. molars – 1 br . Type
needed.
Max. molars - 2 br.
Class I & Class II.


Fully programmed translation brackets:
When teeth require bodily movt.
Addnl. Qualities :
Power arm.
Slot siting features:
Counter mesiodistal tip &
Counter rotation.
Counter B-L tip – max. molars.


 Translation
problems:
Br – occlusal –
centre of resistance.
Tooth – tiphorizontal centre of
rotn. – mesial or
distal force.
Br.- lateral – CR.
Tooth – rotate –
vertical center rotn.MD force.

Slot siting features:
Counter rotation:
Rotating the slot – 3 sp. Amounts – vertical
axis ( 2, 4 or 6°).
Efficient force transfer – br. slot – centre of
crown –
MD length of br. = dist. from slot point –
tooth’s vertical axis.
Rationale – farther tooth moved – greater
rotation overcorrection needed.

Counter mesiodistal tip.
Rotating the slot – 3 sp. Amounts ( 2,3, 4°)
Counter moment – angulated slot & flexed
archwire - < moment – force applied.
For translation – lever long as the dist. from
the slot point to the centre of Res.
Power arm added.

SWA - mini

SWA - std

SWA - medium

SWA - maximum


Optimal power arm length =
dist. form bracket – C.R minus MD slot
length.
Power arm - gingival tie wing – side of
intended direction of movement.
Power arm – Calvin Case.

Counter Bucco lingual tip.
Rotating – base of br.- mesio distal axis.
needed – max. molar translational br.
More –ve base inclination – std. br.

Translation br. Categories.
Min. Translation br.
2mm or less transln.
2° of counter mesiodistal tip & power arm –
distogingival tie wing – distal transln.
Mesial transln. - 2°
2° - counter rotn. – direcn. of movt., 4° BL tip
Medium translation br.
Transln – 2-4 mm.
Power arm, 3° counter MD tip +/-, 4° counter
rotn, 5° counter BL tip.

Max. Translation br.
> 4mm transln.
4° counter MD tip, 6° - counter rotn., 6° of
counter BL tip.

Identification:
All trans. Br. – 1,2 or 3 notches – occl.
surface – base.
Molar – 1,2 or 3 raised dots – power arms.
1 – min, 2- medium; 3 – max.


Set of ant. br.


List of SWA brackets.


Roth Prescription:
Standard Straight-Wire brackets – treat
only nonextraction cases.
Andrews - different series and sets of brackets
- different combinations of extractions,
-ANB differentials, &
-anchorage requirements.
inventory - becoming a problem
Roth - prescription for a special set of
overcorrection brackets - applicable to most
cases.

Problems Roth noticed:

achieve desired tooth positions - standard
SWA, - mechanotherapy phase of treatment –
compensating curves – upper &
- reverse curves - lower archwires.
anchorage control, - extraction cases,
mesial inclination - in the buccal segments segments drift mesially during treatment.
Teeth posn.- end of the appliance therapy settle into non-orthodontic normal positions

This was the beginning of the Roth Prescription.
Roth’s reasoning:
use primarily one prescription - finish to an
"end of appliance therapy" goal
tooth positions are slightly overcorrected &
teeth - settle into non-orthodontic normal
positions.

Overcorrection
overcorrection - comprehensive prescription
using - Andrews extraction brackets.

Roth’s observations:
single prescription with overcorrection in all planes
of space &
Meet - "Six Keys to Normal Occlusion"
Avoid offset bends into archwires—
finishing with full-size wires –
only arch form bent &
flat - curve of Spee or compensating bends.


Maxillary prescription:
maxillary incisors- extra torque (5° more than
normal).
upper canines - less negative torque. 2°
more distal tip, because - retracted in most
treatment.
2° rotation to the mesial.
"Super Torque" - maxillary anteriors - Class
II, division 2


buccal segments - distally uprighted to 0°,
 the bicuspids- rotated 2° mesially,
molars -14° distal rotation (2x, > nonorthodontic normals) &
14° buccal root torque (5° more than
normal).

Mandibular prescription:

Incisor brackets - same - non-orthodontic
normals
Canines - 7° mesial tip and 2° distal rotation.
Lower buccal segment - 3° distal tip & 4°
distal rotation.
necessitate extra distal rotation.
buccal segments - torque - normal,
(overcorrection  to problems and
interferences)
Two lower molars -the same degree of root
torque

 Root Positions
Root positions of a set of extracted teeth –
Roth Prescription - overcorrection in appliance
& in arch form.
Overcorrection - extracted teeth –never
expressed intraorally

Roth prescription

Andrews prescription


Reasons:
Angle of deflection – b/w- bracket slot & the
archwire.
force values drop low – below threshold.
The teeth - relapse back to their original
positions.
Need to build in offsets - undesirable side
effects of tooth-moving mechanics.

Thank you
Leader in continuing dental education


Evolution of straight wire appliance /certified fixed orthodontic courses by Indian dental academy

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