Download - 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
Removable Orthodontic Appliance - Isaacson
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)
Removable Orthodontic Appliance - Isaacson
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
Removable Orthodontic Appliance - Isaacson
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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 orth- odontic 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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
Fitted Labial BowINDICATIONS
used for retentionWIRE USED
0.7 mmADVANTAGES
for retentioncanine is controlled
DISADVANTAGEStime consuming
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
‘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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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
(Removable orthodontic appliance – MS Rani 2nd Edition)
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