Concepts and Components of ROA

CONCEPTS AND COMPONENTS OF REMOVABLE ORTHODONTIC

APPLIANCES

Presented By:-Dr. Chandrika Dubey

CONTENT• Introduction• Development and History• Scope of ROA• Properties of Orthodontic wires• Classification• Indications• Advantages• Disadvantages• Design Components• Commonly Used Appliances• Conclusion

introduction

• Removable appliance can be defined as an appliance one which can be removed by the patient for cleaning, but when in the mouth, is firmly attached to the anchor teeth, so that controlled pressure may be brought to bear on the teeth to be moved.

DEVELOPMENT OF REMOVABLE APPLIANCE

• In united states, the original removable appliance were rather clumsy combination of vulcanite bases and precious metal or nickel-silver wires.

• In early 1900s, George Crozat developed a removable appliance fabricated entirely of precious metal that consisted of an effective clasp for 1st molar teeth, heavy gold wire as framework and lighter gold finger springs to produce desired tooth movement

• Its limitation is that it produces tipping of teeth

(Profitt – 5th edition )(Removable Orthodontic Appliance – Graber Neumann)

• Development continued in Europe despite their neglect in the United States.

• This was because1. Angles dogmatic approach to occlusion, with its emphasis

on precise positioning of each tooth, had less impact in Europe than in US

2. Social welfare system developed much more rapidly in Europe which tended to place emphasis on limited orthodontic t/t

3. Precious metal for fixed orthodontic appliance was less available in europe.• It was banned in nazi germany which forced german orthodontist to

focus on removable appliance

(Proffit – 5th edition)(Removable Orthodontic Appliance – Graber Neumann)

• In 1925 to 1965 era, american orthodontics was based almost exclusively on the use of fixed appliance

• While fixed appliance were essentially unknown in europe and all t/t were done with removable, not only for growth guidance but also for tooth movement of all types.

Proffit 5th edition(Removable Orthodontic Appliance – Graber Neumann)

History

• Invention of Vulcanite – denture material –

“Regulating devices”

• Coffin Plate (1881) made out of piano wire

• N. W. Kingsley (1880) plate for “jumping the bite”

• Pierre Robin (1902) split plate with Screw

• J.H. Badock (1911) expansion plate with efficient screw

Next three decades these plates were eclipsed by

E. H. Angle’s fixed appliances

History

• C.F.L.Nord (1929) meeting of European

Orthodontic Society, Heidelberg – “simple plate

with screw for treatment of masses”

• M. Tischler (1936) Ninth International Dental

Congress, Vienna – demonstrated sophisticated

active plates

• A. M. Schwarz(1938) textbook entirely devoted to

treatment with plates

Scope of removable appliances

• The use of removable appliances still varies widely between clinicians, but it is possible to achieve adequate occlusal improvement with these appliances, provided suitable cases are chosen.

• It is vital to emphasize that cases suitable for removable appliance treatment are those that require simple tipping movements only, and surprisingly few malocclusions will fall into this category.

Properties of Orthodontic wires1) Esthetics Kusy, AO 19972) Stiffness3) Strength4) Range5) Springback6) Formability7) Resiliency8) Friction9) Biohostability10) Biocompatibility11) Weldability

1) Esthetics:– desirable property -no compromise on mechanical properties– composite wires

2) Stiffness/Load deflection rate:– Magnitude of force delivered by the appliance for a particular

amount of deflection.– LDR=Load/Deflection

Fα Edr4 d α l3

l3 r4

E- Modulus of elasticity d- Deflection r- Radius l- Length

Doubling radius = Increases force 16 foldDoubling length = Reduces force 8 fold

L3 α d (2l)3 α 8d 1α d 1 α 16d r4 (r/2)4

Low stiffness or LDR impliesi. Low forces will be appliedii. Forces more constant as appliance deactivatesiii. Greater ease &x accuracy in applying a given force

-For active components low LDR -For retentive components high LDR

‘Variable Cross-section Orthodontics’-Burstone‘Variable Modulus Orthodontics’NiTi ≤ TMA ≤ ss wire

3) Strength: – Force required to activate an archwire to a specific distance-

Kusy Shape and cross-section of wire have an effect

4) Range:– Distance to which an archwire bends elastically, before

permanent deformation occurs- Proffit

5) Springback:– The extent to which the wire reverses its shape after

permanent deformation. Wire can be activated to a large extent hence fewer

activations will be needed

6) Formability: – Ability to bend wire in desired configuration.

7) Resiliency:– Amount of energy stored in a body.

9) Friction: – While closing spaces in continuous archwire technique, involves relative

motion of bracket over wire.

Excess friction- loss of anchor - binding Least amount of friction desired

9) Biohostability: – Ability of a wire to accumulate, or be a site of accumulation of bacteria,

spores or viruses

10) Biocompatibility:– Resistance to corrosion and tissue tolerance to elements in the wire.

11) Weldability:– Ease by which a wire can be joined to other metals by actually melting the 2

metals in the area of the bond

ACTION OF REMOVABLE APPLIANCE• SPONTANEOUS MOVEMENT

– Where extractions are carried out as part of t/t, the relief of crowding may allow neighboring teeth to upright to upright towards extraction site

• ERUPTION GUIDANCE– As space maintainers

• UPRIGHTING– When crowding is relieved, a tooth may upright by movement of crown towards

extraction space

• LABIO-LINGUAL MOVEMENT

• MESIAL MIGRATION

Removable Orthodontic Appliance - Isaacson

ACTIVE MOVEMENTS•TIPPING– Mesiodistal Tipping– Buccolingual tipping

•ROTATIONS AND CONTROLLED APICAL MOVEMENTS•OCCLUSAL MOVEMENT•INTRUSION


WHY REMOVABLE APPLIANCE HAVE LIMITED USE IN LOWER ARCH

•Patients find the bulk unsatisfactory

•Retention is less satisfactory

•Considerably reduced area available for active component (it is not possible to construct springs with long range of action)


Classification

Types of Removable Appliances

• According to Moyers– Loose – fit imprecisely and alter neuromuscular

function– Attached – maintain fixed relationship with

dentition

• Active appliances• Passive appliances

Active Appliances• Extra oral traction devices– Head gears– Facemasks– Chin cup

• Lip Bumpers (“Plumpers”)• Active plates– Schwartz appliance– Sapce regaining appliances– Anterior Spring Aligners (Barrer Appliance)

• Crozat appliance• Vaccum formed Appliances ( Invisibles)

Passive appliances

Used to• To maintain the status quo within the

dentition• To disocclude the dentitions during

orthodontic treatment• To disclude the teeth prior to registration of

bite relationships• As adjuncts to treatment of

temporomandibular dysfunction

Passive appliances

• Bite planes• Occlusal Splints• Multiple Space maintainers• Retainers

ACTIVE PLATE• The removable appliance used at present were developed before

world war II• During that time, there were two distinctive devices

– ACTIVE PLATE• Uses force from within the appliance

– ACTIVATOR• Uses muscular force

• THE ACTIVE PLATE CONTAINS– Baseplate– Clasps– Active elements

• Labial wire• Springs• Screws • Elastics

(Removable Orthodontic Appliance – Graber Neumann)

• Appliance can be

Active Passive

(appliance which applies (appliance which does not force on the teeth) applies force on the teeth)

• According to skeletal or dental changes

Orthopaedic Changes. Orthodontic Changes

• Appliances classified according to the movement of teeth– Labiolingual and buccolingual movement of teeth– Mesiodistal movement of teeth– Rotation and root movement– Expansion and contraction– Intermaxillary and extra oral traction– Functional appliances


Minor tooth movement technique may be considered

– Malposition limited to relatively few teeth– Desired movement not more than few mm

– Adequate space between adjacent teeth to permit entry of teeth to be moved

– Allowable axial inclination corrected by tipping forces– Diastima closure

– Crossbite correction– Anterior crowding

IndicationsIndications

– Closing of spaces

– Uprighting of teeth

• Migration of mandibular incisors

• Retention after corrected malocclusion

•To gain space

•Preventive and interceptive orthodontics

ADVANTAGES DISADVANTAGESPatients maintain good oral hygiene Patient co-operation is vitally important

Easy to clean Whenever multiple tooth movements are to be carried out, it should be done at a time.

Tipping type of tooth movement is carried easily

Treatment duration is prolonged in case of severe malocclusion

Less chair side time Multiple rotations are difficult to treat using removable appliances.

Lesser forces are used, than those needed for bodily tooth movement

Requiring extraction, it is very difficult to close residual space by forward movement of posterior teeth.

Can be used by general dental practitioner who have received adequate training

Appliances are removable, there is a greater chance of patient misplacing or damaging them.

Relative less expensive Patients should exhibit enough skill to remove and replace the appliance without distorting them.

Can be removed -for cleaning of teeth & appliance -if in pain -on socially sensitive occasion

They cannot be used to treat severe cases of Class II and Class III malocclusions with unfavorable growth pattern.

Components of removable appliances

•Retentive Components•Baseplate •Active components

Retention– They are components that help in keeping the appliance in place

and resist displacement of the appliance.

– Retention is accomplished by clasps made of stainless steel wire. Other material such as platinised gold wire, have superseded by the former materials which has the advantage of far greater strength and equal resistance to corrosion. There clasps must be made in such a way that the active portion lies gingival to the greatest diameter of the tooth and so can be bent inwards to clasp the tooth and retain the appliance against strong displacing forces.

CLASPSCan be defined as a component of ROA that retains

and stabilizes an orthodontic appliance in oral cavity by contacting the surfaces of the tooth or by engaging

interproximal embrasures

Requirements of an ideal clasp

– It should offer adequate retention– It should permit usage in both fully erupted as well as partially

erupted teeth.– It should offer adequate retention even in the presence of shallow

undercuts.– They should not by themselves apply any active force that would

bring about undesirable tooth movements of the anchorage teeth.

– It should be easy to fabricate.– It should not impinge on the soft tissues.– It should not interfere with normal occlusion.

Mode of action of clasps

•There are 2 types of undercuts– Buccal and lingual cervical undercuts– Mesial and distal proximal undercuts

•Buccal and lingual cervical undercuts– The buccal and lingual surfaces of molars have a distinct undercuts at the

cervical margin. This can be seen from the mesial aspects of a molar.– Eg: Circumferential clasps, south end claps

•Mesial and distal proximal undercuts– The molars are widest mesio-distally at the contact point and gradually taper

towards the cervical margin. These surfaces sloping from the mesial and distal contact areas towards the neck of the teeth are called the mesial and distal proximal undercuts. Eg: Adams clasp, Crozat clasp

Classification of clasps

Free ended clasp(One end embedded in the acrylic portion and free end on the tooth surface.) Eg:

– Circumferential clasp– Duyzing clasp– Crozat clasp– Triangular clasp– Ball end clasp– Hand wrought roach clasp– Arrow pin clasp

Continuous or looped clasps(Both ends are embedded in the acrylic portion or base plate) Eg:

– Molar clasp– Visick clasp– Arrowhead clasp– Adams clasp– Eyelet clasp– South end clasp

Circumferential ClaspALSO CALLED

C-claspthree quarter clasp

INDICATIONSfor the retention on premolars and molars

WIRE USED0.9mm

DISADVANTAGES• Cannot be used on deciduous teeth as there is no infrabulge area• Cant be used on partially erupted teeth• Can only be used on post. Teeth• Clasp is rigit as it is made of thicker wire• Difficult to adjust, gets distorted easily• Tends to create space b/w teeth by wedging action as it is made of thicker wire• Can not be repaired if broken

ADJUSTMENTclasp is adjusted by holding it at the contact point and bending it towards the tooth

(Removable orthodontic appliance – MS Rani 2nd Edition)

Jackson’s ClaspALSO CALLED

full claspU-Clasp

INDICATIONSretention on premolars and molars

WIRE USED0.9mm

DESIGNEngages both buccocervical undercuts

ADVANTAGESSimple design Offers adequate retention

DISADVANTAGESInadequate retention in partially erupted teethsimilar to C clasp

ADJUSTMENTbending the clasp towards tooth by holding it at the contact point


Adam’s ClaspALSO CALLED

liverpool claspuniversal claspModified arrowhead clasp

INDICATIONSretention on molars, premolars and anteriors

WIRE USED0.7 mm for posteriors0.6 mm for anterior

DESIGNParts Bridge

Arrowhead Retentive arms

• Clasps act by engaging certain constricted areas of the teeth that are called undercuts. When clasps are fabricated, the wire is made to engage these undercuts. So, their displacement is prevented.

ADVANTAGESSmall, neat, unobtrusive, occupies minimum spaceRigid, offers excellent retentionUsed on any tooth in the archIf broken can be repaired by solderingPermits modifications in design

DISADVANTAGESExtensive wire bending incorporates stresses in the wire

ModificationsAdams clasp with single arrowhead

in partially erupted teeth Adams clasp with J hook

A hook can be soldered on to the bridge of the Adam’s clasp. This hook also helps in engaging elastics.

Adams clasp with helixA helix can be incorporated into the bridge of Adam’s clasp. This helps in engaging elastics.

Adams clasp with additional arrowheadAdam’s clasp can be constructed with an additional arrowhead. The additional arrowhead engages the proximal undercut of the adjacent tooth & is soldered on to the bride of Adam’s. This type offers additional retention.

Adams clasp with soldered buccal tubeA buccal tube can be soldered on the bridge of the Adam’s clasp. This modification permits use of extra oral anchorage using face bow headgear – assembl

Adams clasp with distal extension The Adam’s clasp can be modified so that the distal

arrowhead has a small extension in corporate distally. The distal extension helps in engaging elastics.

Double clasp on maxillary central incisorsAdam’s clasp can be fabricated on the incisors & premolars

when retention in those areas is required. They can be constructed to span a single tooth or two teeth.

(Removable orthodontic appliance – MS Rani 2nd Edition)(Removable orthodontic appliance – Isaacson)

Schwarz ClaspADVANTAGES

Can be used in deciduous or permanent teethArrowheads can be adjusted medially or distallyAllows partially erupted teeth to erupt in position

DISADVANTAGESSkill to fabricateCan be used only on posterior teethRequires special plier

ADJUSTMENTArrowhead bent towards papilla to engage undercuts


Duyzings ClaspINDICATIONS

used to engage buccal undercuts of molarsWIRE USED

0.7 mmADVANTAGES

one half of the clasp can be used if requiresDISADVANTAGES

easy displacement

ADJUSTMENT

Bending towards the tooth or undercut area

(Removable orthodontic appliance – MS Rani 2nd Edition)(Orthodontic Removable Appliance - Lokhare)

Eyelet ClaspWIRE USED

0.7 mmDESIGN

similar to triangular claspused as single eyelet or multiple eyelet claspeyelets placed in embrasures

ADVANTAGESNo sharp bends, breakage unlikelyDoes not interfere with eruption of teeth

DISADVANTAGESOn single tooth does not have firm grip

ADJUSTMENTBending eyelet interdentally towards the tooth


Delta Clasp (william J Clark)WIRE USED

0.7 mmDESIGN

similar to adams clasp in principleADVANTAGES

does not open with repeated insertion and removalmaintains shape betterrequires less adjustmentless prone to breakage

ADJUSTMENT

hold retentive loop and twist inwards or,

bending towards interdental undercut as it emerges from acrylic


Southend ClaspINDICATIONS

retention on anteriorsWIRE USED

0.7mmADVANTAGES

Esthetically more pleasingsimple designless obstructive as compared to double clasp

ADJUSTMENTadjusted by readapting it into the interdental area


BASEPLATEBase plate is to incorporate all these

components together into a single unit.

Functions

– Unit of all at components both active and retentive components.

– Helps in anchoring the appliance in place.– It provides support for the wire components– Distributing the forces over a larger area.– Bite planes can be incorporated into plate

Requirements and choice of material for base plate preparation

– Readily cleanable by the patient and remain clean in the mouth.– Should be strong.– Sufficiently hard to resist the abrasion.– The material must resist attack by the oral fluids and it should be

of such a colour that food debris is readily visible on it.– It should readily represent the pressure points.

Limitation to Base Plate

•Knife edge should not be attempted•Not be horseshoe shaped because it is not stronger and it can be warped.•No posterior seal is necessary (it makes palatal sore and difficult to clean).

Extension of the Base Plate

– Maxillary Base Plate • Usually covers the entire palate till the distal on the last molar.

– Mandibular base plate • Is usually shallow to avoid irritation to the lingual sulcus. To

compensate for this it should be made thicker to increase the strength.

• Usually made of Acrylic• As thin as possible(1-2mm)• Closely adapted• Extend as far as necessary to obtain anchorage• Lower baseplate- U shaped, relatively thicker• Shallow lingual sulcus reinforced with ss wire or bar

BITEPLANE

Anterior

Posterior

Upper

Lower

Parallel to occ plane

Inclined to occ plane

Anterior biteplane

• Platform behind upper incisor teeth• Height enough to separate • posterior teeth by 1.5-2mm• Reduce overbite of anterior teeth• ‘opening the bite’• Height of plane gradually increased• Proclination of upper incisors

Sved Biteplane

• Introduced by Sved in 1944• Covers incisal edges of upper anteriors• Pressure transmitted axially• Retention questionable• Ideal in growing individuals

Posterior Biteplane

• displacing activity of mandible• unilateral posterior crossbite• wide enough to contact buccal & palatal cusps• occlusion disengaged• equal on both sides• after correction appliance acts as retainer

Lower Inclined Plane• Catlan more than 200 yrs ago• Anterior crossbite• 45 degrees to occ plane• Upper incisors guided into correct position labially• indicated when incisors are in early stage of eruption If used for more than 6wks- anterior open bite results May need frequent cementation

Pre-treatment Post-treatment

In-vivo evaluation of the bacterial contamination and disinfection of acrylic baseplates of removable orthodontic appliances Fernanda Campos Rosetti Lessa,a Carla Enoki,a Izabel Yoko Ito,b Gisele Faria,c Mirian Aiko Nakane Matsumoto,d and Paulo Nelson-Filhoe(Am J Orthod Dentofacial Orthop 2007;131:705.e11-705.e17)

•INTRODUCTION– This randomized clinical trial assessed, by using microbial culture and scanning electron microscopy (SEM),

the contamination by mutans streptococci (MS) colonies/biofilms on acrylic baseplates and evaluated the efficacy of antimicrobial sprays (Periogard, Cepacol and sterile tap water [control]) on their disinfection.

•METHOD– Seventeen children were randomly enrolled in a 3-stage changeover system with a 1-week interval between

each stage. All solutions were used in all stages by a different group of children. The acrylic baseplates were worn full time except at meals. At the end of each week of the trial, the baseplates were submitted to a randomized disinfection protocol and were sent for microbiologic analysis. New baseplates were constructed, and the same sequence of procedures was repeated 2 more times. Acrylic baseplates representing each test solution were examined by SEM.

•CONCLUSIONS – In this study, acrylic baseplates of removable orthodontic appliances worn by children were contaminated by

MS colonies/biofilms in all cases after 1 week. Although Cepacol had better results than sterile tap water (control), Periogard showed significantly greater efficacy in reducing MS colonies/biofilms on acrylic surfaces and can be recommended for disinfection of removable orthodontic appliances.

• Active components

• Labial bow• Springs

BOWSLabial bow is that component if ROA which

helps in retracting and retaining the anterior teeth and also contribute for retention of

appliance

LABIAL BOWS

May have 2 functions1) Serve as active element for movement of teeth2) Hold the plate in place & retain the teeth

Labial Bow with ‘U’ loop INDICATIONS

retention of anterior teethretraction in case of minor overjet

WIRE USED0.7 mm wire

ADVANTAGEScan be fabricated easilycan correct minor discrepancy in overjeteasy to adjust

CONTRAINDICATIONIn case of severe proclination of incisor because bow portion has a tendency to slip gingivally when activated causing insufficient activation

ADJUSTMENTCompressing of ‘U’ loop Displaces palatally by only 1mm


Long Labial BowINDICATIONS

Minor anterior space closureMinor overjet reductionClosure of space distal to canine

Guidance of canine during canine retraction. Also is used for retention.

WIRE USED0.7mm

ADVANTAGESUsed to close space between canine and premolarcan control the canine

ADJUSTMENTClosing the U loops so that horizontal arm is displaced palatally by 1 mm each time it is activated


Split Labial BowINDICATIONS

Anterior retraction Correction of midline diastema

ADVANTAGESflexibility is more

DISADVANTAGESflattening of arch results in cases where it is not required

ADJUSTMENTclosing the U loops so that the arch form is maintained


Labial Bow with Reverse LoopINDICATIONS

can be used to retain anterior teeth after active treatment is completed. Controls the canine.

WIRE USED0.7 mm

ADVANTAGESprevents buccal drift of canine during retraction of anteriors

ADJUSTMENTDone in 2 stages1) Vertical loop opened by compressing with plier2) This lowers the bow in incisor region compensating bends at the base of the loop


Mills Bow ALSO CALLED

extended labial bowINDICATIONS

in severe protrusion of teethalignment of irregular incisors

WIRE USED0.7mm

ADVANTAGESmore flexible because of extensive loopslighter forcelong range of action

DISADVANTAGESbulkyless comfortablecannot be adjusted precisely

ADJUSTMENT(Removable orthodontic appliance – MS Rani 2nd Edition)

High Labial Bow with Apron SpringINDICATIONS

t’s useful in retracting the teeth with severe proclination of the teeth. It can be used to correct single tooth malposition.

WIRE USED0.9 mm/1 mm0.4 mm

ADVANTAGESdoes not slip over the inclined planes of teethlighter forceslong range of actionsingle tooth malposition can be corrected

DISADVANTAGESnot well tolerated by patientstime consumingcan not be used in lower archCannot be used in patients with shallow sulcus

ADJUSTMENTapron spring is bent towards the teeth for activation


Roberts RetractorINDICATIONS

correction of severe protrusion of teethWIRE USED

0.5 mmADVANTAGES

does not slip over inclined planelight force is appliedrange of action is more as more length of wire is incorporated

DISADVANTAGESuncomfortable cannot be given on lower arch as sulcus is shallow

ADJUSTMENTplacing a bend in vertical limb of wire where it emerges from coil so

that the wire is displaced palatally


Fitted Labial BowINDICATIONS

used for retentionWIRE USED

0.7 mmADVANTAGES

for retentioncanine is controlled

DISADVANTAGEStime consuming


Beggs Retention BowALSO CALLED

wrap-around retainerINDICATIONS

retention purposeWIRE USED

0.7 mmADVANTAGES

allows settling of occlusion at the end of active phase of ortho t/tno crossover wire

DISADVANTAGESIf not constructed well retention may not be good


SPRINGSSprings are active component of removable

orthodontic appliances that are used to effect various tooth movements

Ideal requisites of a spring

•Simple to design•Less likely to be distorted by the patient•Easier to adjust•Less likely to produce unintended tooth movements•Easy to clean•It should remain active over a long period of time

Factors to be considered in designing a spring– The connection between the length, thickness and amount of

deflection of a commonly used spring of round cross section expressed by the formula.

D PL3

T4

• D = Amount of deflection• P = Amount of pressure• L = Length of the spring• T = Thickness of the wire

• DIAMETER– Force directly proportional to diameter– diameter = Force = flexibility

• LENGTH– Length = force = flexibility

• FORCE– Force depends upon the number of teeth to be moved

• DIRECTION– Direction is determined by point of contact b/w spring and teeth

Simple rules for guidance in the design of these springs.

•The direction of tooth movement depends on the point at which the spring makes contact with it.

•The arm of the spring is virtually rigid and the coil may be regarded as the center from which the arm pivots. Movement of the arm will always be radial and movement of any point on it will be part of a curve with its center at the coil. Further away from the coil this path is nearer to a straight line. Nearer to the coil it will be a tight curve.

• If the tooth to be moved needs to travel in a straight line a long arm will be needed; if in a curve a very short arm. A long range of action is allowed by a long arm, a short range of action by a short arm.

• Wherever possible the arm should be kept straight so that its path can more accurately be assessed. On occasions a kink may be necessary to avoid interference from another tooth

• A simple formula may be used to find the position in which the coil should be placed. A line drawn joining the present position and desired position of the tooth. A perpendicular bisector is drawn to this line. The coil may be placed anywhere along this line, usually as far away as possible. The limiting factor is usually the presence of the other teeth.

Classification of Springs

I. Based on direction of tooth movement1. Springs for mesio-distal tooth movement2. Spring for labio-lingual tooth movement3. Springs for expansion of arches

II. Based on nature of support1. Self supported springs 2. Guided springs 3. Auxiliary springs

III. Based on presence of loop or helix

Single Cantilever SpringINDICATIONS

mesial or distal movement of teethclosure of midline diastema

WIRE USED0.5 mm

DISADVANTAGEScan be used only in those teeth which are in proper alignment bucco-linguallyalong the arch

ADJUSTMENTopening the helix3mm – 0.5mm wire1.5mm – 0.6mm wire


Double Cantilever SpringALSO CALLED

Z-springINDICATIONS

correction of minor rotation labiolingual movement of teeth

WIRE USED0.6 mm

DISADVANTAGESIf not perpendicular to palatial surface of teeth, it tends to intrude teeth

ADJUSTMENTrotation correction

opening the upper helix 2-3mmlabiolingual movement

opening both the helix 2-3mm(Removable orthodontic appliance – MS Rani 2nd Edition)

‘T’ SpringWIRE USED

0.6 mmINDICATIONS

buccal movement of posterior teethADJUSTMENT

vertical arm of T spring should be bent to displace horizontal arm toward the tooth

*not used for anterior coz if it is applied to a sloping surface, vertical component will be larger and labial component smaller ; this reduces the efficiency and tooth may intrude

(Removable orthodontic appliance – MS Rani 2nd Edition)(Removable Orthodontic Appliance – Isaacson)

Coffin Spring (Walter Coffin)INDICATIONS

expansion of dental archTransverse arch expansionUnilateral crossbite with lateral mandibular displacement

WIRE USED1.25 mm

ADVANTAGESeconomiceasy to cleandifferential expansion can be obtained in PM and Molar

DISADVANTAGEStends to be unstableeasy to overactivate

ADJUSTMENTexpand the spring so that two halves of the appliance move apart


Activation

CANINE RETRACTORSsprings that are used to move

canine in distal direction

CLASSIFICATION• Based on location

• buccal• Palatal

• Based on presence of helix or loop• Helical• looped

• Based on mode of action• push type• pull type

Buccal Self Supported Canine RetractorINDICATIONS

where canine is placed labially or high in the sulcuswhen both distal and palatal movement is required

WIRE USED0.7 mm for self supporting0.5 mm for supporting type

DISADVANTAGEScan not be used in lower arch due to shallow sulcusuncomfortable to patientflexibility is compromised

ADJUSTMENTfree end is cut short by 1mm and is re-adapted to engage the mesial side of canineor by closing the coil by 1mm


Supported Buccal Canine RetractorINDICATIONS

where canine is placed labially or high in the sulcuswhen both distal and palatal movement is required

WIRE USED0.5mm supported in tubing

ADJUSTMENTactivated by closing the coil by 2mm


Reverse Loop Canine RetractorINDICATIONS

canine is placed in the line of arch and has to be just distalizedWIRE USED

0.6mmADVANTAGES

can be used in shallow sulcusADJUSTMENT

coil is opened for activation 1 mm of free end of active arm is cut and re-adapted


‘U’ Loop Buccal Canine RetractorINDICATIONS

where functional depth of sulcus is lesswhen canines are placed bucally

WIRE USED0.6mm

ADVANTAGEScan be used in shallow sulcus

DISADVANTAGESrequires frequent adjustment

ADJUSTMENTfree end is cut by 1mm and re-adapted


Palatal Canine RetractorINDICATIONS

palatally placed caninerequires distal and buccal movement

WIRE USED0.6mm

DISADVANTAGESuncomfortable to patienteasily distorts

ADJUSTMENTcoil is opened by 2-3mm at the point where active arm emerges from the coil


BOXING AND GUARDINGBoxing is done prior to acrylisation of base by covering the spring by modeling wax

PROCEDURE OF BOXING•Fabricated spring is positioned on the cast•Active arm, coil and path traversed by active arm is covered by modeling wax•Waxing should be of sufficient thickness just to cover spring completely•After acrylization, the wax is flushed out in dewaxing unit or with hot water

Instruction to the patient• It is one of the most important aspects of ensuring success with

removable appliances that the patient and the parent should be adequately counseled.

• With the aid of a mirror the patient should be shown how to remove and insert the appliance

• The instruction to wear the appliance for 24 hours per day is then given, apart from removal for cleaning after meals

• Well constructed appliances do not interfere with eating normal food or with speech, and patients should be assured that within a few days they will find no difficulty with eating and speaking.

• A high standard of oral hygiene should be insisted on to avoid the possibility of enamel decalcification or gingival inflammation.

• Removable appliances should be taken out and brushed with soap and water and the mouth cleaned after every meal

• Diet should be that required for good general health and hard and sticky foods and sweets avoided completely.

• Patients must be told quite clearly that if an appliances is causing pain or discomfort, they should attend the clinic at once and preferably not remove the appliance as it will then be possible to see what is causing the pain and take appropriate action.

Microsensor technology to help monitor removable appliance wear Marc Bernard Ackerman,a Morgan Stuart McRae,b and William H. Longleyc Jacksonville, Fla (Am J Orthod Dentofacial Orthop 2009;135:549-51)

Retention is routinely prescribed after orthodontic treatment to prevent relapse. Orthodontists often notice a discrepancy between what a patient reports about retainer wear and what a clinical examination shows.

Smart Retainer environmental microsensor that can be easily incorporated into many types of removable orthodontic appliances to monitor compliance.

USB-powered Smart Reader uses wireless technology to download information about actual usage from the Smart Retainer. The information is decrypted and analyzed, and can be shown to the patient in easy-to-understand charts.

CONCLUSION

Removable appliances have many advantages, they exert minimal interference with dentoalveolar growth, and are particularly useful for treatment during the developing stages of the dentition. Removable appliance treatment, taking place at earlier ages, is attractive as it offers early completion dates and little inconvenience during socially and educationally busy years for the growing child.

The success of removable appliances depends on good design and attention to detail. Collaboration between the user of an appliance (the orthodontist) and the producer (the technician) must be close. Removable appliances must be well designed and accurately constructed to the specification of the orthodontist who, if necessary, must be able to construct an appliance himself exactly as he wants it.

References

• Orthodontic treatment with removable appliances- W. W.J.B. Houston, K.G. Issacson

• The Design, construction and use or Removable Orthodontic Appliances – C. Philip Adams

• Removable Orthodontic Appliances- T.M. Graber, Bedrich Neumann

• Orthodontics Principles and Practice- T.M. Graber • Contemporary Orthodontics- Proffit

References

• Orthodontics. Post graduate dental hand book- Spiro. J. Chakonas

• An Introduction to Orthodontics- Laura Mitchell• Removable Partial Prosthodontics - McCracken’s• Dentofacial Orthopedics with Functional Appliances,

Thomas. M. Graber, Thomas Rakosi, Alexandre G. Petrovic

• Removable Orthodontic Appliances. M.S.Rani

References

• High Labial Retainer Harvey.L.LevittJCO Jan1972

• A Removable cuspid-to-cuspid RetainerDoglus J. Shilliday JCO 1973

• Crozat Princilples and Technique. Wendell H. Taylr. JCO June 1985

• Crozat Appliance Treatment of Buccal Crossbite Frank Marasa. JCO June 2003

• Essix Retainers- Fabrication and supervision for permanent retention John. J. Sheridan, Willaim Ledoux, Robert Mcmin. JCO Jan 1993

• Van der Linden Retainer JCO May2003•

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References

• Molar intrusion with removable a appliance Giuilio Alessandri Bonatti, Daniela Giunta JCO Aug 1996

• Wraparound cantilever retainerTimonthy J. Tremont, JCO Feb- 2003

• Notes & Compilation of Articles. Dr.Arundhati P. Tandur

• Space maintainers in Pedodontics, Dr.N. Shivakumar, Library thesis, Department of Pedodontics, Manipal

THANKU

Documents

Concepts and Components of ROA