Magnets in orthodontics /certified fixed orthodontic courses by Indian dental academy

MAGNETS
IN
ORTHODONTICS

www.indiandentalacademy.com

INDIAN DENTAL ACADEMY
Leader in continuing dental education


 Introduction
 Types of magnetic materials
 Properties of magnets
 Application of magnets in orthodontics.

 In 1953, magnets were first used for denture
retention by BEHRAN & EGAN.

 Use of magnets in orthodontic- BLECHMAN &
SMILEY.


PROPERTIES OF MAGNETS

 Flux Density


 In dentistry, ferromagnetic materials with
static field are used.
 Magnetocrystalline Anisotropy.
 Coercivity.


 Coulombs law:-This law states that force between
two magnetic poles is directly proportional to
magnitude & inversely proportional to square of
the distance between them.
 Curie point:-Pierre Curie(1859-1906)


 High force to volume ratio.

 Maximal force at shorter distances.


 No interruption of magnetic
force lines by intermediate
media.
 No friction in attractive force
configuration.

 No energy loss.


TYPES OF MAGNETIC MATERIALS







Platinum-cobalt(Pt-co)
Aluminium-Nickel-Cobalt(Al-Ni-Co)
Ferrite
Chromium-cobalt-Iron
Samarium Cobalt(SmCo)
Neodymium-Iron-Boron(Nd2Fe B)
14


 SAMARIUM-COBALT (SmCo5&Sm2Co17)
MAGNETS:-

-high resistance to demagnetization.

-corrosion resistance.


 Advantages:-Continuous force is exerted.
- Eliminates the patient co-operation.
-No friction.
 Disadvantages:-Tarnish &corrosion products are cytotoxic.
-Cost factor


 Biological effect of magnetic forces:-

Aronson:-thinning of epithelium under
attracting & repelling magnets.
McDonald - proliferative activity of fibroblasts
in presence of static magnetic field
Lars Bondemark & Kurol studied changes in
human dental pulp and gingival tissue.

APPLICATIONS OF MAGNETIC
APPLIANCES
1.
2.
3.
4.
5.
6.

Tooth intrusion
Expansion
Tooth Impaction
Space closure
Molar distalization
Magnetic Edgewise brackets

7.
8.

Functional Appliances.
Retainers.


 Tooth Intrusion:Active Vertical Corrector-Dellinger(1986)
-Samarium cobalt magnets in the repelling mode
are used.


 Fixed Magnetic Appliance:-introduced by VARUN KALRA & CHARLES BURSTONE.

Appliance consists of an upper &lower acrylic splints with
samarium cobalt magnets in stainless steel casting
embedded in a repelling mode.




EXPANSION:-Vardimon et al(1987) demonstrated
palatal expansion using two types of magnetic devices in
Macaca fascicularis monkeys.
-Tooth borne appliance


 Tissue borne appliance (attached directly to
palate by endosseous pins).


 Tooth Impaction:- Vardimon,Graber,Drescher
-Neodymium Iron Boron magnets can be used to
assist eruption of an impacted canine.
 Mancini(1996)-force levels are sufficient enough to
induce the cellular &biochemical changes are required to
produce orthodontic tooth movement.


space closure
-simple tooth movement without archwires :-Muller(1984)
-Complex Intra &Interarch Mechanics:-Blechman(1985)

CL-II mechanics with a magnetic force
system in a CL-I extraction case


3 magnet configuration to enhance
CL-II mechanics

3 magnet configuration
used to simultaneously
move all 4 canines distally

CL-II mechanics using magnetic force
system in CL-II extraction case.

Repulsive CL-II mechanics in CL-II
Nonextraction cases.


 Molar Distalization.
-Gianelly et al(1989):-repelling magnets in conjuntion with a
modified Nance appliance was used.
-Bondemark & Kurol:-repelling samarium cobalt magnets
were used for distalization.


 Magnetic Edgewise Brackets:-Kawata(1987)
-Samarium cobalt magnet with an edgewise bracket
(o.018slot) .


 Functional Orthopaedic Magnetic Appliances:Vardimon(1989)
-for correction of CL-II&CL-III malocclusion.


 Magnetic Twin Block:Clark(1996)
-Samarium cobalt magnets
were embedded in the
inclined surface of the
twin block in attractive
mode.


 Magnetic Activator Device(MAD):-Darendilier (1993) developed this magnetically active
functional appliance.
MAD I-mandibular deviations
MAD II-CLII malocclusion
MADIII-CLIII malocclusion
MADIV-skeletal open bite correction.

MAD-II


MAD-II FOR CORRECTION OF CL-II,DIVISION 1
MALOCCLUSION.

Deep Bite

open Bite


 MAD III


 MAD - IV


MAD IV(a)

MAD IV( b)

MAD IV( c)


 Treatment of CL-II
bimax with magnetsDarendelier&Joho(199
2)
-Autonomous fixed
magnetic appliance.


 Propellant Unilateral Magnetic Appliance (PUMA)
- Chate(1995)
Magnets are use to stimulate costo-chondral bone
graft in Hemi facial microsomia.


 Retainers:-Springate &
Sandler(1991)
-micro magnets made
of neodymium iron boron
magnets as a fixed
retainer in a patient with
persistent diastema.


 Bibiliography:-

-Dentofacial Orthopedics with functional appliances-T.M Graber,
Rakosi,Petrovic.
-


Thank you
Leader in continuing dental education


Magnets in orthodontics /certified fixed orthodontic courses by Indian dental academy

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