CONCEPTS AND COMPONENTS OF REMOVABLE REMOV ABLE ORTHODONT ORTHODONTIC IC 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
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Removable appliance can be Removable b e defined as an appliance one which can be removed by the patient for cleaning, but when in the mouth, is firmly attached att ached to the anchor teeth, so that controlled pressure may may be brought b rought to bear on the t he teeth to be moved.
DEVELOPMENT OF REMOV REMOVABLE ABLE APPLIANCE •
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In united states, the original remov removable able appliance were rather rather clumsy combination of vulcanite bases and precious metal or nickel-sil nickel-silver ver wires. In early 1900s, George Crozat developed a removable appliance fabricated entirely of precious metal that consisted of an effective 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 because 1. Angles Angles dog dogma matic tic app appro roach ach to occ occlus lusion ion,, with with its emp emphas hasis is on precise positioning of each tooth, had less impact in Europe than in US 2. Soc Social ial we welf lfar are e sys syste tem m dev develo eloped ped muc much h more more rapi rapidly dly in Europe which tended to place emphasis on limited orthodontic t/t 3. Pr Preci ecious ous me meta tall for for fix fixed orth orthodo odont ntic ic appl applian iance ce was was less 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)
•
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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 tooth movement of all types.
Proffit 5th edition (Removable Orthodontic Appliance – Graber Neumann)
History •
Invention of Vulcanite – denture material – Regulating “
devices
”
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Coffin Plate (1881) made out of piano wire
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N. W. W. Kingsley Ki ngsley (1880) (18 80) plate for jumping the bite
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Pierre Robin (1902) split plate with Screw
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“
”
J.H. Badock 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 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) Schwarz(1938) textbook entirely devoted to
treatment with plates
SCOPE OF REMOV REMOVABLE ABLE APPLIANCES •
•
The use of removable appliances still varies widely between clinicians, but it is possible po ssible to achieve adequate occlusal improvement improv ement 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 WIRES 1) Es Esth the eti tics cs 2) Stiffness 3) Strength 4) Range 5) Springback
6) Formability 7) Resiliency 8) Friction
9) Biohostability 10) Bioc Biocomp ompat atibi ibilit lity y 11) Weld eldabi abilit lity y
Kus usy y, AO 199 997 7
1) Esthetics: –
desirable property -no compromise on mechanical properties
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composite wires
2) Stiffness/Load deflection rate: –
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Magnitude of force delivered by the appliance for a particular amount of deflection. LDR=Load/Deflection
Fα Edr4 l3
d α l3 r4
E- Modulus of elasticity
d- Deflection r- Radius l- Length Doubling radius = Increases force 16 fold Doubling length = Reduces force 8 fold
L3 α d 1α d r4
(2l)3 α 8d 1
α
(r/2)4
16d
Low stiffness or LDR implies i.
Low forces will be applied
ii.. ii
For orce cess mo morre co cons nsttan antt as ap appl plia ianc nce e de deac acti tiv vat ates es
iii. ii i.
Grea Gr eate terr ease ease &x acc accur urac acy y in in app apply lyin ing g a gi give ven n for force ce
-For active components low LDR
-For retentive components high LDR Variable Cross-section Orthodontics -Burstone
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Variable Modulus Orthodontics
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NiTi ≤ TMA ≤ ss wire
’
’
3)
Strength: –
Force required to activate an archwire to a specific distanceKusy
Shape and cross-section of wire have an effect effect 4)
Range: –
5)
Distance to which an archwire bends elastically, before permanent deformation occurs- Proffit
Springback: –
The extent to which the wire reverses reverses its shape after permanent deformation.
Wire can be activated to a large extent hence fewer activations will be needed
6)
Formability: –
7)
Ability to bend wire in desired configuration. configuration.
Resiliency: –
Amount of energy stored in a body.
8)
Friction: –
While closing spaces in continuous archwire technique, involves relative 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)) Bi 10 Bioc ocom ompa pati tibi bili lity ty:: –
Resistance Resist ance 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 SPONT ANEOUS MOVEMENT –
Where extractions extractions are carried out as part of t/t, the relief of crowding may 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
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LABIO-LINGUAL LABIO-LINGU AL MOVEMENT
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MESIAL MIGRA MIGRATION TION Removable Orthodontic Appliance - Isaacson
ACTIVE MOVEMENTS •
TIPPING –
Mesiodistal Tipping
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Buccolingual tipping
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ROTATIONS AND CONTROLLED APICAL MOVEMENTS
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OCCLUSAL MOVEMENT
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INTRUSION
WHY REMOVABLE APPLIANCE HAVE LIMITED USE IN LOWER ARCH •
Patients Patien ts find the bulk unsatisf unsatisfactory actory
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Retention Reten tion is less satisf s atisfactory actory
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Considerably reduced area ava available ilable for active component (it is not possible to construct springs with long range of action)
Removable Remov able Orthodontic Appliance - Isaacson
CLASSIFICATION
Types of Removable Appliances •
According to Moyers –
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Loose – fit imprecisely and alter neuromuscular function Attached – maintain fixed relationship with dentition
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Active appliances
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Passive Passiv e appliances app liances
Active Appliances •
Extra oral traction devices – – –
• •
Lip Bumpers (“Plumpers”) Active plates – – –
• •
Head gears Facemasks Chin cup
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 withi within n the dentition To disocclude the dentitions during orthodontic treatmen t reatmentt To disclude the teeth prior to registration of bite relationships As adjuncts to treatment treatment of temporomandibular dysfunction •
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Passive appliances •
Bite planes
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Occlusal Splints
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Multiple Space maintainer maintainerss
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Retainers
ACTIVE PLATE •
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The removable appliance used at present were developed before before world war II During that time, there were two distinctive devices –
ACTIVE PLA PLATE TE •
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ACTIVATOR •
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Uses force from within the appliance Uses muscular force
THE ACTIVE PLA PLATE TE CONT CO NTAINS AINS –
Baseplate
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Clasps
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Active elements •
Labial wire
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Springs
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Screws
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Elastics
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Appliance can be Active (appliance which applies force forc e on the teeth)
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Passive
(appliance which does not applies force on the teeth)
According to skeletal or dental changes
Orthopaedic Changes.
Orthodontic Changes
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Appliances classified according to the movement of teeth –
Labiolingual and buccolingual movement of teeth
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Mesiodistal movement of teeth
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Rotation and root movement
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Expansion and contr contraction action
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Intermaxillary and extra oral traction
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Functional appliances
Removable Orthodontic Orthodontic Appliance - Isaacson
Indications Minor tooth movement technique may be considered –
Malposition limited to relativ relatively ely few teeth
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Desired movement not more than few mm
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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
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Closing of spaces
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Uprighting of teeth
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Migration of mandibular incisors
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Retention after corrected malocclusion
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To gain space
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Preventive and interceptive orthodontics
ADVANTAGES
DISADVANTAGES
Patients 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
They cannot be used to treat severe cases of Class II and Class III malocclusions with unfavorable growth pattern.
Components of removable appliances
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Retentive Components
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Baseplate
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Active components components
Retention –
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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 resistance to corrosion. corrosion. There clasps must must be made in such a way that the active portion lies gingival to the greatestt diameter of the tooth and so can be bent inwards to greates clasp the tooth and retain the appliance against strong displacing forces.
CLASPS Can be defined as a component of ROA that retains and stabilizes stabilizes an orthodontic appliance in i n oral cavity by contacting the surfaces of the tooth or by engag engaging ing interproximal embrasures
Requirements Requir ements of an ideal clasp –
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It should off offer er 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 any active force force that would bring about undesirable tooth movements of the anchorage teeth.
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It should be easy to fabricate. fabricate.
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It should not impinge on the soft tissues.
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It should not interfere with normal occlusion.
Mode of action of clasps There are 2 types of undercuts
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Buccal and lingual cervical undercuts
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Mesial and distal proximal proximal undercuts
Buccal and lingual cervical cer vical undercuts
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The buccal and lingual surfaces of molars have a distinct undercuts at the cervical margin. This can be seen from the mesial mesial aspects of a molar. molar. Eg: Circumferential Circumferential clasps, south end claps
Mesial and distal proximal undercuts
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The molars are widest mesio-distally at the contact point and gradually taper towardss the cervical margin. These surfaces sloping from the mesial toward mesial and distal contact areas towards the neck of the teeth are called the mesial and distal proximal proxi mal 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:
Continuous or looped clasps (Both ends are embedded in the acrylic portion or base plate) Eg:
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Circumferential clasp
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Duyzing clasp
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Crozat clasp
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Triangular clasp
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Ball end clasp
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Hand wrought roach clasp
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Arrow pin clasp
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Molar clasp
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Visick clasp
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Arrowhead clasp
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Adams clasp
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Eyelet clasp
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South end clasp
Circumferential Circumferen tial Clasp Cla sp ALSO CALLED C-clasp three quarter clasp INDICATIONS for the retention on premolars and molars WIRE USED 0.9mm DISADVANTAGES •
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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
ADJUSTMENT clasp is adjusted by holding it at the contact point and bending it towards the tooth (Removable orthodontic appliance – MS Rani 2nd Edition)
Jackson s Clasp ALSO CALLED full clasp U-Clasp INDICATIONS retention on premolars and molars WIRE USED 0.9mm DESIGN Engages both buccocervical undercuts ADVANTAGES Simple design Offers adequate retention DISADVANTAGES Inadequate retention in partially erupted teeth similar to C clasp ADJUSTMENT bending the clasp towards tooth by holding it at the contact point
(Removable (Remov able orthodontic appliance – MS Rani 2nd Edition)
Adam s Clasp ALSO CALLED liverpool clasp universal univer sal clasp Modified arrowhead clasp
INDICATIONS retention on molars, premolars and anteriors
WIRE USED 0.7 mm for posteriors 0.6 mm for anterior
DESIGN Parts Bridge Arrowhead Retentive arms •
Clasps act by engaging certain constricted 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 preve prevented. nted.
ADVANTAGES Small, neat, unobtrusive, occupies minimum space Rigid, offers excellent retention Used on any tooth in the arch If broken can be repaired by soldering Permits modifications in design
DISADVANTAGES Extensive wire bending incorporates stresses in the wire
Modifications Adams 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 helix A helix can be incorporated into the bridge of Adam’s clasp. This helps in engaging elastics.
Adams clasp with additional arrowhead Adam’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 tube A 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 extension helps in engaging elastics.
Double clasp on maxillary central incisors Adam’s clasp can be fabricated on the incisors & premolars when retention retention in those areas is required. They can be constructed to span a single tooth or two teeth. (Removable (Remov able orthodontic appliance – MS Rani 2nd Edition) (Removable (Remov able orthodontic appliance – Isaacson)
Schwarz Clasp ADVANTAGES Can be used in deciduous or permanent teeth Arrowheads can be adjusted medially or o r distally Allows partially erupted teeth to erupt in position
DISADVANTAGES Skill to fabricate Can be used only o nly on posterior teeth Requires special plier
ADJUSTMENT Arrowhead bent towards towards papilla to engage undercuts (Removable (Remov able orthodontic appliance – MS Rani 2nd Edition)
Duyzings Clasp INDICATIONS used to engage buccal undercuts of molars mo lars WIRE USED 0.7 mm ADVANTAGES one half of the clasp can be used if requires DISADVANTAGES easy displacement ADJUSTMENT Bending towards the tooth or undercut area
(Removable (Remov able orthodontic appliance – MS Rani 2nd Edition) (Orthodontic Removable Appliance - Lokhare)
Eyelet Clasp WIRE USED 0.7 mm DESIGN similar to triangular clasp used as single eyelet or multiple eyelet clasp eyelets placed in embrasures
ADVANTAGES No sharp bends, breakage unlikely Does not interfere with eruption of teeth
DISADVANTAGES On single tooth does not have firm grip
ADJUSTMENT Bending eyelet interdentally towards the tooth
Delta Clasp (william J Clark) WIRE USED 0.7 mm DESIGN similar to adams clasp in principle ADVANTAGES does not open with repeated insertion and removal maintains shape better requires less adjustment less prone to breakage ADJUSTMENT hold retentive loop and twist inwards or, bending towards interdental interdental undercut as it emerges from acrylic (Removable (Remov able orthodontic appliance
MS Rani 2nd Edition)
Southend Clasp INDICATIONS retention on anteriors WIRE USED 0.7mm ADVANTAGES Esthetically more pleasing simple design less obstructive as compared to double clasp
ADJUSTMENT adjusted by readapting it into the interdental area
(Removable (Remov able orthodontic appliance – MS Rani 2nd Edition)
BASEPLATE Base plate is to incorporate all these components together into a single unit.
Functions –
Unit of all al l at components both active ac tive and retentive retentive components.
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Helps in anchoring the appliance in place.
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It provides support for the wire components
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Distributing the forces over a larger area.
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Bite planes can be incorporated into plate
Requirements Requiremen ts and choice choi ce of material for base plate preparation –
Readily cleanable by the patient and remain clean in the mouth. mo uth.
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Should be strong.
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Sufficiently hard to resist the abrasion.
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The material must resist attack 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 •
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Knife edge should not be attempted Not be horseshoe shaped because because it is not stronger stronger and it can be warped. No posterior seal is necessary (it makes palatal palatal sore and difficult to clean).
Extension of the Base Plate –
Maxillary Base Plate •
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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 for this it should be made thicker to increase the strength.
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Usually made of Acrylic
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As thin as possible(1-2mm)
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Closely adapted
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Extend as far as necessary necessar y to obtain anchorage
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Lower baseplate- U shaped, s haped, relatively thicker thicker
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Shallow lingual sulcus reinf reinforced orced with ss wire or bar
BITEPLANE
Anterior
Upper
Parallel Par allel to occ plane plan e
Posterior
Lower
Inclined to occ plane
Anterior biteplane •
Platform Platf orm behind upper incisor teeth
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Height enough to separate separate
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posterior teeth by 1.5-2mm
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Reduce overbite of anterior teeth
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‘
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Height of plane gradually increased
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Proclination of upper incisors
opening the bite
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Sved Biteplane •
Introduced by Sved in 1944
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Covers incisal edges of upper anterior anteriorss
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Pressure transmitted axially
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Retention Reten tion questionable
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Ideal in growing individuals
Posterior Biteplane
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displacing activity of mandible
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unilateral posterior crossbite
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wide enough to contact buccal & palatal cusps
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occlusion disengaged
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equal on both sides
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after correction appliance acts as retainer
Lower Inclined Plane •
Catlan more than 200 yrs ago
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Anterior crossbite
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45 degrees to occ plane
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Upper incisors guided into correct position labially
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indicated indicate d when incisors are in early stage of eruption
If used for more than 6wksanterior 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 Matsumoto ,d and Paulo Nelson-Filhoe (Am J Orthod O rthod Dentofacial Orthop 2007;131:705.e11-705.e17)
INTRODUCTION
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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 sprays (Periogard, Cepacol and sterile tap water [control]) on their disinfection.
METHOD
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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 randomiz randomized ed 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 representing each test solution were examined by SEM.
CONCLUSIONS
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In this study, acrylic baseplates of removable orth- odontic appliances worn by children were contaminated contaminate d by MS colonies/biofilms in all cases after 1 week. Although Cepacol had better results than sterile tap water (control), (control) , Periogard showed significantly greater efficacy in reducing MS colonies/biofilms on acrylic surfaces and can be recommended for disinfection of removable
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Labial bow
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Springs
Active components
BOWS Labial bow is that component if ROA which helps in retr retracting acting and retaining the anterior teeth and also contribute for retention of appliance
LABIAL BOWS May have 2 functions 1) Se Serv rve e as as act activ ive e ele eleme men nt for for mo mov vem emen entt of of tee teeth th 2) Ho Hold ld th the e pla platte in in pla place ce & ret retai ain n the the tee eeth th
Labial Bow with U loop INDICATIONS retention of anterior teeth retraction in case of minor overjet WIRE USED 0.7 mm wire ADVANTAGES can be fabricated easily can correct minor discrepancy in overjet easy to adjust CONTRAINDICATION In case of severe proclination of incisor because bow portion has a tendency to slip gingivally when activated causing insufficient activation ADJUSTMENT Compressing of U loop Displaces palatally by only 1mm ‘
’
(Removable (Remov able orthodon orthodontic tic appliance – MS Rani 2nd Edition)
Long Labial Bow INDICATIONS Minor anterior space closure Minor overjet reduction Closure of space distal to canine Guidance of canine during canine retraction. Also is used for retention.
WIRE USED 0.7mm ADVANTAGES Used to close space between canine and premolar can control the canine ADJUSTMENT Closing the U loops so that horizontal arm is displaced palatally by 1 mm each time it is activated
(Removable (Remov able orthodontic appliance – MS Rani 2nd Edition)
Split Labial Bow INDICATIONS Anterior retraction Correction of midline diastema
ADVANTAGES flexibility is more DISADVANTAGES flattening flatteni ng of arch results in cases where it is not required ADJUSTMENT closing the U loops so that the arch form is maintained
(Removable (Remov able orthodontic appliance
MS Rani 2nd Edition)
Labial Bow with Reverse Loop INDICATIONS can be used to retain anterior teeth after active treatment is completed. Controls the canine.
WIRE USED 0.7 mm ADVANTAGES prevents buccal drift of canine during retraction of anteriors ADJUSTMENT Done in 2 stages 1)
Ver erti ticcal lo loop op op open ened ed by com compr pres essi sing ng wit ith h pli plier er
2)
This lowers th the e bo bow in incisor re region compensating bends at the base of the loop
Mills Bow ALSO CALLED extended labial bow INDICATIONS in severe protrusion of teeth alignment of irregular incisors WIRE USED 0.7mm ADVANTAGES more flexible because of extensive loops lighter force long range of action DISADVANTAGES bulky less comfortable cannot be adjusted precisely ADJUSTMENT (Removable (Remov able orthodon
appliance
nd
Edition)
High Labial Bow with Apron Spring INDICATIONS t ’s useful in retracting the teeth with severe proclination of the teeth. It can be used to correct single tooth malposition.
WIRE USED 0.9 mm/1 mm 0.4 mm ADVANTAGES does not slip over the inclined planes of teeth lighter forces long range of action single tooth malposition can be corrected DISADVANTAGES not well tolerated by patients time consuming can not be used in lower arch Cannot be used in patients with shallow sulcus ADJUSTMENT apron spring is bent towards the teeth for activation (Removable orthodontic appliance – MS Rani 2nd Edition)
Roberts Retractor INDICATIONS correction of severe protrusion of teeth WIRE USED 0.5 mm ADVANTAGES does not slip over inclined plane light force is applied range of action is more m ore as more length of wire is incorporated DISADVANTAGES uncomfortable cannot be given on lower arch as sulcus is shallow ADJUSTMENT placing a bend in vertical limb of wire where it emerges from coil so that the wire is displaced palatally (Removable (Remov able orthodon orthodontic tic appliance – MS Rani 2nd Edition)
Fitted Labial Bow INDICATIONS used for retention WIRE USED 0.7 mm ADVANTAGES for retention canine is controlled DISADVANTAGES time consuming
(Removable (Remov able orthodontic appliance
MS Rani 2nd Edition)
Beggs Retention Bow ALSO CALLED wrap-around retainer INDICATIONS retention purpose WIRE USED 0.7 mm ADVANTAGES allows settling settling of occlusion at the end of active phase of ortho t/t no crossover wire DISADVANTAGES If not constructed well retention may not be good
(Removable (Remov able orthodontic appliance – MS Rani 2nd Edition)
SPRINGS Springs are active component of removable orthodontic appliances that are used to effect various tooth movements
Ideal requisites of a spring •
Simple to design
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Less likely to be distorted by the patient
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Easier to adjust
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Less likely to produce unintended tooth movements
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Easy to clean
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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
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P = Amount of pressure
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L = Length of the spring
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T = Thickness of the wire
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•
DIAMETER –
Force directly proportional to diameter
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diameter = Force = flexibility
LENGTH –
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FORCE –
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Length = force = flexibility
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 ar m 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 straightt line. Nearer to the coil it will be a tight curve. straigh •
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If the tooth to be moved needs to travel in a straight straight line a long arm ar m 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 accuratel accurately y 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 bisector is drawn to this line. The coil may may be placed anywhere anywhere along this line, usually as far away away as possible. The limiting factor factor is usually the presence presence of the other teeth.
Classification of Springs I.
Based on direction of tooth movement 1. Springs for mesio-distal tooth movement 2. Spring for labio-lingual tooth movement 3. Springs for expansion of arches
II.
Based on nature of support 1. Self supported springs 2. Guided springs 3. Auxiliary springs
III. Based on presence of loop or helix
Single Cantilever Spring INDICATIONS mesial or distal movement of teeth closure of midline diastema WIRE USED 0.5 mm DISADVANTAGES can be used only in those teeth which are in proper alignment bucco-lingually along the arch ADJUSTMENT opening the helix 3mm – 0.5mm wire 1.5mm – 0.6mm wire (Removable (Remov able orthodontic appliance
MS Rani 2nd Edition)
Double Cantilever Spring ALSO CALLED Z-spring INDICATIONS correction of minor rotation labiolingual movement of teeth WIRE USED 0.6 mm DISADVANTAGES If not perpendicula perpendicularr to palatial surface of teeth, it tends to intrude ADJUSTMENT rotation correction opening the upper helix 2-3mm labiolingual movement opening both the helix 2-3mm (Removable (Remov able orthodontic appliance – MS Rani 2nd Edition)
teeth
T Spring WIRE USED 0.6 mm INDICATIONS buccal movement of posterior teeth ADJUSTMENT 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 (Remov able orthodontic appliance – MS Rani 2nd Edition) (Removable (Remov able Orthodontic Appliance – Isaacson)
Coffin Spring (W (Walter alter Coffin) INDICATIONS expansion of dental arch Transverse arch expansion Unilateral crossbite with lateral mandibular displacement WIRE USED 1.25 mm ADVANTAGES economic easy to clean differential expansion can be obtained in PM and Molar DISADVANTAGES tends to be unstable easy to overactivate ADJUSTMENT expand the spring so that two halves of the appliance move (Removable (Remov able orthodon
appliance
apart nd
Edition)
Activation
CANINE RETRACTORS springs that are used to move canine in dist distal al direction
CLASSIFICATION •
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Based on location •
buccal
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Palatal
Based on presence of helix or loop •
Helical
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looped
Based on mode of action •
push type
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pull type
Buccal Self Supported Canine C anine Retractor INDICATIONS where canine is placed labially or high in the sulcus when both distal and palatal movement is required WIRE USED 0.7 mm for self supporting 0.5 mm for supporting type DISADVANTAGES can not be used in lower arch due to shallow sulcus uncomfortable to patient flexibility is compromised ADJUSTMENT free end is cut short by 1mm and is re-adapted to engage engage the mesial side of canine or by closing the coil by 1mm (Removable (Remov able orthodon orthodontic tic appliance
MS Rani 2nd Edition)
Supported Buccal Canine Retractor INDICATIONS where canine is placed labially or high in the sulcus when both distal and palatal movement is required WIRE USED 0.5mm supported in tubing ADJUSTMENT activated activat ed by closing the t he coil by 2mm
(Removable (Remov able orthodontic appliance – MS Rani 2nd Edition)
Reverse Loop Canine Retractor INDICATIONS canine is placed in the line of arch and has to be just distalized WIRE USED 0.6mm ADVANTAGES can be used in shallow sulcus ADJUSTMENT coil is opened for activation 1 mm of free end of active arm is cut and re-adapted
(Removable (Remov able orthodontic appliance – MS Rani 2nd Edition)
U Loop Buccal Canine Cani ne Retractor INDICATIONS where functional depth of sulcus is less when canines are placed bucally WIRE USED 0.6mm ADVANTAGES can be used in shallow sulcus DISADVANTAGES requires frequent adjustment ADJUSTMENT free end is cut by 1mm 1m m and re-adapted
(Removable (Remov able orthodontic appliance
MS Rani 2nd Edition)
Palatal Canine Retractor INDICATIONS palatally placed canine requires distal and buccal movement WIRE USED 0.6mm DISADVANTAGES uncomfortable to patient easily distorts ADJUSTMENT coil is opened by 2-3mm at the point where active arm emerges from the coil (Removable (Remov able orthodontic appliance – MS Rani 2nd Edition)
BOXING AND GUARDING Boxing is done prior to acrylisation of base bas e by covering the spring by modeling wax PROCEDURE OF BOXING •
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Fabricated Fabrica ted spring is positioned on the cast Active arm, coil and path trav traversed ersed 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 •
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It is one of the most important aspects of ensuring success with removable removabl e 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.
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A high standard of oral hygiene should be insisted on to avoid the possibility of enamel decalcifica decalcification tion or gingival inflammation. Removable appliances should be taken out and brushed with soap Removable 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 Patients pain or discomfort, they should attend the clinic at once and preferably pref erably not remove the appliance as it will then be possible to see what is causing the pain and take appropriate action.
Microsensor removable
technology to help appliance
monitor 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 interference with dentoalveolar growth, and are particularly par ticularly useful for treatment during the developing stages of the dentition. Removable Remov able appliance treatment, taking place at earlier ages, is attractive attr active as it offer offerss 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 attention to detail. detail. Collaboration between the user of an appliance (the orthodontist) and the producer (the technician) must be close. Removable Remov able appliances must be well designed and accurately constructed to the specification of the orthodontist who, if necessary necessary,, must be able to construct an appliance himself exactly as he wants it.
References •
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Orthodontic treatment with removable appliancesW. 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
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Orthodontics Principles and Practice- T.M. Graber
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Contemporary Orthodontics- Proffit
References •
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Orthodontics. Post graduate dental hand book- Spiro. J. Chakonas An Introduction to Orthodontics- Laura Mitchell Mitchell Removable Partial Prosthodontics - McCracken s Dentofacial Orthopedics with Functional Appliances, Thomas. M. Graber, Thomas Rakosi, Alexandre G. Petrovic Removable Orthodontic Orthodontic Appliances. M.S.Rani ’
References •
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High Labial Retainer Harvey.L.Levitt JCO Jan1972 A Removable cuspid-to-cuspid Retainer Doglus J. Shilliday JCO 1973 Crozat Princilples Princi lples and a nd Techniqu Technique. e. Wendell H. Taylr Taylr.. JCO June 1985 Crozat Appliance Treatment of Buccal Crossbite Frank Marasa. JCO June 2003 Essix Retainers- Fabrication Fabrication and supervision super vision for permanent retention John. J. Sheridan, Willaim Ledoux, Robert Mcmin. JCO Jan 1993 Van der Linden Retainer JCO May2003 •
References
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Molar intrusion with removable a appliance Giuilio Alessandri Bonatti, Daniela Giunta JCO Aug 1996 Wraparound cantilever retainer Timonthy 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
