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MAGNETS IN ORTHODONTICS

PRESENTED BY:MD. ISHTIAQ HASAN,FCPS-II TRAINEE,DEPT. OF ORTHODONTICS, DDCH

SUPERVISOR:PROF. DR. MD. ZAKIR HOSSAINBDS, PHD(JAPAN)PROF. & HEAD,DEPT. OF ORTHODONTICS,DDCH.

Magnets , at first used in dentistry to aid in retention of

dental prosthesis in 1953.In 1978, Dr. Blechman used

magnet in orthodontic tooth movement.

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TYPES OF MAGNETS

Platinum-cobalt (pt-Co)Aluminium-nickel-Cobalt (Al-Ni_Co)

FerriteChromium-Cobalt Iron

Samarium-Cobalt n(SmCo)Neodymium-Iron-Boron (Nd2Fe14B)

ADVANTAGES OF MAGNETIC FORCE OVER CONVENTIONAL FORCE SYSTEM

Constant force , no force decay over timeLess patient discomfortForce system frictionlessBetter directional control

Rapid tooth movement , Less treatment duration

Minimum appliance adjustmentLess chair side time

Can exert their force through mucosa and boneRemove need for elastics and springs

DISADVANTAGES

Corrosion of magnetBulkiness of magnetThermal sensitivity

During mastication, magnet may lost

SYSTEMIC EFFECTS OF MAGNET

Increase proliferation of fibroblast in presence of magnet

Reversible epithelial thinning in contact with epithelium

Increase blood flowIncrease cell divisionIncrease cartilage matrix formation ,

woven bone formation and increase proliferation in marrow bone.

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CLINICAL APPLICATION OF MAGNETS

Magnets can be used for--------- Tooth movement Retention Relocation of impacted tooth Maxillary expansion Open bite Distalization of molar Functional appliance

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RELOCATION OF IMPACTED TOOTH

• Relocation of impacted tooth can be done for all teeth—canine,premolar,molar.

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Reff:AJO-DO 1991 Dec(494-512)

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IMPACTED THIRD MOLARReff:AJO-DO 1991 Dec(494-512)

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Reff: AJO-DO 1991Dec (489-493)

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Reff: Cases Journal 2008,1:382

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EXTRUSION OF CROWN-ROOT FRACTURED TEETH

Reff:AJO-DO 1997 AUG (187-193)

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ADVANTAGES

• Magnets exert their force through buccal mucosa and bone.

• In conventional procedure, there is a communication between the impacted tooth & oral environment through the wire & chance of spread of infection & irritation of the lips with wire & difficult to adjust & change the direction of force & poor patient compliance.

• But in magnetic procedure , it is possible to move tooth in all three plane of space by altering the magnetic arm.

• Patient is able to maintain good oral hygiene..

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• Reduce treatment time. The rate of canine movement is 1.22 mm/28 days & in conventional procedure , 0.63 mm/28 days . (Reff-AJO-DO Volume1996 May 489-495)

• Easy for operator and patient because fewer adjustments are needed.

• Attachments are less likely to dislodge.• Less painful to patient• Force level increase with tooth

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RETENTION

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DIASTEMA CLOSURE

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ADVANTAGES

• Activation of the appliance is not needed.

• Less chair side time.• Better oral hygiene.• Magnets can be reused after

sterilization.• Invisible closure of midline diastema

can be obtained by applying magnets to the palatal surface of teeth.

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EXTRUSION OF POST TEETH It can be done by 2 ways

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EXTRUSION OF POSTERIOR TEETH

• An acrylic bite plane should use. If bite is very deep, the gap between the post teeth with anterior bite plane should be more than 4 mm and magnets should be bonded to the occlusal surfaces of post teeth.

• Tooth movement is rapid and about 2 mm in one month.

• If the gap between post teeth and ant bite plate is less than 4 mm , the magnets need to be positioned on buccal surface.

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INTRUSION OF ANT TEETH For ugly gummy smile , intrusion of incisors is indicated.

Bonding the magnets on labial surface of ant teeth.Make a full coverage occlusal splint with bucco-lingual extension containing attracting magnets 2-3 mm apical to the magnets on the ant teeth.

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INTRUSION OF POSTERIOR TEETH

procedure 1

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INTRUSION OF POSTERIOR TEETH

procedure 2

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ALIGNMENT OF IRREGULARLY PLACED TEETH

• Malocclusion where one or more teeth are misplaced , can be aligned by bonding magnets on the labial surface of the teeth & construct an acrylic plate with magnets in appropriate position

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TOOTH MOVEMENT ALONG ARCH WIRE Edgewise appliance is used. ButUpper & lower 6 have 2 molar tube.Occlusal molar tube carry the magnet.Gingival tube is used for basal arch wire.U & L magnetic poles face each other in attracting mode in order to generate force to move the upper canine distally along the arch wire.Anchorage is controlled in traditional manner with the base arch wire

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EARLY CLASS III TREATMENT

Aim of treatment---• Stimulate of forward maxillary growth• Maxillary expansion for correction of

cross bite• Restriction in forward mandibular

growth

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Reff:JCO 1993 Oct (563-569)

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Reff:JCO 1993 Oct (563-569)

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EARLY CLASS III TREATMENT

• Appliance design-------– Bonded upper plate & lower removable

plate is used ,each carrying two buccal magnets.

– The lower magnets are placed more anteriorly than the upper buccal magnets , thus creating a forward force in the maxilla & backward force in mandible.

– The upper bonded appliance containing two repelling magnets in the palate for expansion. Only one repelling magnet can slide for activation. 44

CLASS-II MALOCCLUSION TREATMENT

Reff:AJO-DO 1993 Mar(223-239)

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CLASS-II MALOCCLUSION TREATMENT

• The appliance is basically an upper & lower removable acrylic plate carrying attracting magnets in both buccal segments.

•Magnets are placed distal to upper canine & distal to lower first premolar.

• A 30° inclination of the occlusal surface of magnet to its buccal surface produce an oblige force to correct cl-II malocclusion.

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IN CL-II DEEP BITE CASES Reff:AJO-DO 1993 Mar(223-239)

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IN CL-II OPEN BITE CASES Reff:AJO-DO 1993 Mar(223-239)

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IN CL-II OPEN BITE CASES

• Two repelling magnets can be used posteriorly to produce molar & premolar intrusion with some distal movement of maxilla while pushing the mandible downward & forward. In addition , a pair of attracting midline magnets located at the retroincisal area to achieve symmetry , align upper and lower midline and prevent lateral movement. 49

PAIN FREE AND MOBILITY FREE ORTHODONTICS

• In American Journal of Orthodontics 1998 , Dr. Blechman told magnetic orthodontics is pain free and mobility free.

• Discomfort & pain is the leading cause of poor compliance during orthodontic treatment.

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PAIN FREE AND MOBILITY FREE ORTHODONTICS

• Some degree of mobility also can be noted during orthodontic treatment because during this process , bone resorption rate exceeds deposition rate. During chewing , this mobility also causes pain.

• Magnetic force generate rapid tooth movement without root resorption & periodontal disturbances. Treatment time is shorter.

• The magnetic field is responsible for the reduction of pain because it block the sensory nerve pathway. It can block almost 80% of action potential.

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PAIN FREE AND MOBILITY FREE ORTHODONTICS

• Magnetic field were used to accelerate human fracture repair. It also promote bone fragment revascularization with more expansion of vessels.

• Some neurologists and sport physician use magnet to treat pain for osteoarthritis & sports injury. By applying specially designed magnets , patient feel pain relief in 10 minutes & healing time is dramatically shortened. Accelerated healing is due to increased blood flow due to relaxation of capillary wall.

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PAIN FREE AND MOBILITY FREE ORTHODONTICS

• Magnetic orthodontics is mobility free because here bone deposition is almost equal to the rate of resorption.(Reff:AJO-DO 1998 Apr(379-383)

• Tooth movement causes increase stress that induce increase body’s citric acid level. Traditional appliances causes increase of 46% of normal citric acid level which is significant. But magnetic force increase 22% of normal citric acid level which is not significant.

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CONCLUSION Magnets are used successfully for

tooth movement but they are not routinely used.

Magnets and the magnetic force system is better device for theoretical & academic purpose. Not easily one can practice in day-to-day life. Need to be very thorough in magnetic physics. Also they are expensive.

Thus the main & only idea of all these discussion are to review the work of various authors , to learn from them , enjoy them & to think different.

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