Bio mechanics of Space closure in orthodontics /certified fixed orthodontic courses by Indian dental academy

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3

Mushroom loop
o

Apical addition of wire in archial configuration

o

More patient friendly- reduces the horizontal part
of wire near vestibule

o

Beta-titanium CNA M loop- 0.017 x 0.025

o

Activation upto 5 mm

o

Reactivation- every 6-8 wks

o

Bypass premolars, IBD


o

Single cuspid retraction, en masse anterior
retraction

o

NiTi intrusion arch, tied piggyback to SS archwire


o

Preformed M loop space closing archwires

o

Preactivation- separating the legs by 3mm.
Gable bends- mesial to increase anterior moment
distal to increase anchorage moment

o

Torque in distal leg eliminated- wire passive in third
order in buccal segment

o

Loop reactivated until there is atleast 3 mm of space
closure

o

After space closure, wire left in mouth for 1-2 visitsroot uprightingwww.indiandentalacademy.com

Double keyhole loop
o

Roth treatment mechanics

o

Introduced by John Parker- 0.019 x 0.026

o

Concept



Complete space closure with one set of archwires



Allows operator to select how space will be closed



Activation- cinching wire distal to last molar tube


PG Retraction Spring
o

Poul Gjessing- 1985

o

Controlled tipping- uprightingover long periods of activation

o

Net result- bodily movement

o

Preformed-0.016 x 0.022 SS

o

Double ovoid apical helix- 10mm

o

Smaller occlusally placed helixactivation further closes the loops

o Segment of circle in distal leg- eliminate undesirable
moments acting on 2nd premolar

o

For canine retraction- 160gms

o

Double helix separated by 1mm

o

Resist tipping & rotational tendencies
-not correct rotation or extreme inclination

o

Leveling of buccal segment –must

o

Activation- every 4 wks

o

Each activation- 1.5mm of controlled movement


o

Controlled incisor retraction

o

Auxiliary molar tube- lateral incisor bracket

o

Twist anterior leg 90˚ - 3mm in front of vertical
helix- fit in vertical tube of lateral bracket

o

Intrusive force- 12-25gms each side

o

Estimated treatment time- 5-6 months on an avg


o

Used for retraction of both canine and incisors

o

Incisor segment intrusion- 20-25gms/side

o

Mesial and distal extensions angulated to build in
residual moments

o

Vertical forces in the posterior segment
counteracted by forces of occlusion


Opus loop
o

Described by Raymond E. Siatkowski

o

M/F for translation


Individual teeth: 7.1-10.2 mm



Groups of teeth: 8.0-9.1 mm

o

Most closing loops M/F 4-5 mm

o

To achieve net translation, add residual moment


Gable bends anterior & posterior



Posterior gable band & anterior wire-bracket
twist

Opus loop
Disadvantage of gable bend
o

Tipping- translation- uprighting

o

Correct magnitude of residual moments are
difficult to achieve

o

Changing areas of stress distribution in the pdl
may not yield most rapid, least traumatic method
of space closure


Opus loop
o

Study: design and verify loop design capable of
delivering M/F inherently without adding residual
moments.

o

Castigliano’s Theorem: to derive of M/F ratio in
terms of loop geometry.


Standard Opus 70 loop

M/F ratio on both the ends is equal

K-SIR LOOP
o

K-SIR – Kalra Simultaneous Intrusion and Retraction

o

Continuous 0.019 x 0.025 TMA archwire

o

Closed loop- 7mm x 2mm


K-SIR LOOP


K-SIR LOOP
o

Trial activation- releases stress built up

o

Reduces the severity of V bend

Neutral position

K-SIR LOOP
o

Second premolar bypassed- IBD

o

Controlled tipping- bodily-root movement

o

Reactivation 6-8 wks


K-SIR LOOP
Advantages
o

Simplicity of design- ease of fabrication

o

Comfortable to the patient

o

TMA- low forces, low LDR, long range of action

o

En masse retraction- Shortens treatment timeprevents appearance of unsightly space distal to
incisors.


A comparative analysis of commonly used retraction
loops in Edgewise mechanics- A FEM Study. Dr.
Chetan V. Jayade


Evaluate mechanical behavior of routinely used
retraction loops in edgewise mechanotherapy



9 different loop designs evaluated for assessing
M/F ratio and F/D rates when subjected to
horizontal activation forces

o

Findings of the study

o

Opus loop showed highest M/F ratio

o

‘T’ loop showed lowest LDR

o

Loop height= M/F = F/D rate


Loops Software
o

Program developed by Borland Delphi

o

Simulate any ortho loop connecting 2 brackets

o

AJO 1997- Demetrios Halazonetis


Obstacles to space closure
o

Inadequate leveling

o

Damaged brackets

o

Incorrect force levels

o

Interference from opposing teeth

o

Soft tissue resistance


Root Torquing
o

Stage III- correction of labio-lingual & mesiodistal root position

o

Torquing assessed by



Visual inspection of appearance of teeth



Palpation of roots



From radiographs


Tan auxiliary

Boot auxiliary- buccal root torque of molars


Uprighting springs
o

Size of coil

o

Mini spring- inner diameter of coil- twice the size of
wire diameter- coils tiny- difficult to grip

o

Midi spring- incisors 0.010”,canines-0.012”

o

Maxi spring- 4 times wire diameter


Torquing of rootso

Torquing of roots- twist in the rectangular wire

o

“The equal and opposite reciprocal reactions
(which generally cause undesirable opposite
movements of adjacent teeth) are commonly
disregarded”.

o

Biomechanics of torque- An FEM investigationDr. V. P. Jayade

Torquing of roots1,2,3 progressively
torqued more and
more?


Torquing of roots-


Torquing of rootso

Twists in the rectangular archwire seem to be
appropriate only when reciprocal torque is
required on the adjacent teeth, but beware of high
moments. (‘Use undersize wires’- Thurow)

o

“twists” in the rectangular wire for attaining
torque should be employed judiciously, and not
indiscriminately.


Alternate torquing methods (Thurow)


Alternate torquing methods
(DeAngelis)
o

Warren Spring

Alternate torquing methods
(Burstone, Isaacson)


o

Cantilever spring- En masse root correction


o

Rectangular loop- separate canine root correction


Conclusion
o

Space closure- fricton/frictionless

o

Anchorage classification

o

Root torquing


Zeal without knowledge is a
runaway horse


References
1.

Contemporary orthodontics.- William R. Proffit

2.

Modern Edgewise mechanics and the segmented
arch technique.-Dr. Charles J. Burstone

3.

Biomechanics in clinical orthodontics- Ravindra
Nanda

4.

Biomechanics and Esthetic strategies in clinical
orthodontics- ravindra Nanda

5.

Biomechanics in clinical orthodontics- Michael R.
Marcotte

References
6.

Systemized Orthodontic Treatment Mechanics.McLaughlin, Bennett, Trevisi.

7.

Tip-Edge guide and Differential straight- arch
technique.-Peter C. Kesling

8.

Refined Begg for modern times.- Dr. V. P. Jayade

9.

The Alexander Principle. Contemporary concepts
and principles.- R. G. Wick Alexander

10. Bio-Efficient
11.

Therapy.- Anthony Viazis

Fricker

References
11.

The segmented arch approach to space closure.
Charles J. Burstone. Ajo Nov 1982

12.

Segmental approach to mandibular molar
uprighting.- Roberts, Cracker, Burstone 1982 mar

13.

Biomechanical design and clinical evaluation of new
canine retraction spring. Poul Gjessing. AJO May
1985

14.

Effect of ph on chain elastics- AJO 1990 nov

15.

Use of vertical loops in retraction system- Apr 1991

16.

Clinical considerations in the use of retraction
mechanics. Julie Ann Stagger, JCO June 1991

References
17.

An investigation into the characteristics of PG canine
retraction spring. Eden and Waters. AJO Jan.1994

18.

T-loop position and anchorage control. Kuhlberg and
Burstone. AJO 1997

19.

Design and test orthodontic loops using your
computer. Demetrious J. Halazonetis. AJO Mar 1997

20.

Ongoing Innovations in Biomechanics & Materials for
the New Millennium- Robert P. Kusy

21.

Simultaneous intrusion and retraction of anterior
teeth. Varun Kalra. JCO 1998

References
21.

J- Hook Headgear- John Hickam

22.

Continuous arch wire closing loop design,
optimization, and verification. Part I & II. Raymond
E. Siatkowski. AJO Oct. 1997

22.

A comparative analysis of commonly used retraction
loops in Edgewise mechanics- A FEM Study. Dr.
Chetan V. Jayade

23.

Experimental evaluation of frictional resistance in
the posterior segment using different wires and
posterior attachments- Dr. Ashwini Joshi

26.

Biomechanics of torque- An FEM Investigation.
Dr V. P. Jayade


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