RETENTIVE AND ACTIVE COMPONENTS OF REMOVABLE APPLIANCE

RETENTIVE AND ACTIVE COMPONENTS OF REMOVABLE APPLIANCEBy , Dr.Nikitha Aswath.PDept of pedodontics and preventive dentistry

1 INTRODUCTIONRemovable appliance:-Appliance that can be inserted and removed by the patient. K.G Issacson

Removable appliance are used mainly 1.Effective space maintainer.2.Retention appliance3.cross bite 4.scissor biteSuitable age for treatment with removable appliance is early mixed dentition.CLASSIFICATION REMOVABLE APPLIANCESRETENTIVE COMPONENTSACTIVECOMPONENTSClaspsBowsSpringsCanine retractorsScrewsElasticsBase plate RETENTIVE COMPONENTS DEFINITIONComponents that retain or hold the appliance in place and resist the unwanted displacement of appliance due to active components. PRINCIPLES OF CLASP FUNCTIONHeight of contour is the line encircling the maximum bulge or circumference of the crown.Undercut is portion of tooth surface which is below the height of contour and above the anatomical neck of crown.Clasp make use of these undercuts for retention purpose.

UNDER CUTMESIALDISTALBUCCALLINGUAL

UNDER CUTSMesial and Distal

Begins below the contact pointAccessible immediately after eruptionClasp using this undercut is most useful and efficientEg:-Adams clasp

Buccal and Lingual

Less extensive

Not accessible till full eruption

Less efficient

Eg:- C claspCLASSIFICATIONBased on using the Undercut1.Clasps using Mesial / Distal UndercutsAdams ClaspTriangular ClaspBall End ClaspArrow head / Schwarz Clasp2. Clasps using Buccal / Lingual UndercutsC ClaspSouth End Clasp3.Clasps Using Both UndercutsJacksons ClaspCrozat clasp

10Requirements of ideal clasp1.Provide adequate retention2.Engage fully erupted and partially erupted tooth.3.Offer adequate retention even in presence of shallow undercuts.4.Shouldnot apply any force by themselves.5.Should be easy to fabricate ,adjust and repair.

6.Should not injure the soft tissue.7.Should not interfere with normal occlusion and with normal mastication.1.FREE END

2.OCCLUSAL CROSSOVER

3.RETENTIVE ARM

4.RETENTIVE TAG PARTS OF CLASP.

C CLASPThree quarter clasp, Circumferential claspWire used for construction:-21 gauge-0.8mm

DesignEngages bucco cervical undercut.The C clasp can be mesial or distal clasp depending on location of open endThe open end of wire engages either mesial or distal interproximal embrasure.Extends either mesially or distally and passes below the maximum bulge along the cervical margin onto other interproximal embrasure.It is then carried over the occlusal embrasure to end as a single retentive arm on the lingual aspect that gets embedded in the acrylic base plate.

Indication:-permanent molars or premolars.

Adjustment:-Holding at contact point and bending towards the tooth.

C CLASPADVANTAGESSimplicity of design and fabrication.DISADVANTAGESNo adequate retention, only as supporting clasp.Cannot be fabricated on deciduous molar.Easily distorted.

JACKSONS CLASPFULL CLASP,U CLASP21 gauge-0.8mm of wire0.6mm if used in deciduous molars

DESIGNClasp is placed buccally Engages buccocervical,mesial and distal undercut.Wire adapted along the buccocervical margin just above the free gingiva.Then extended to both the proximal undercuts,from where it is vertically carried over the occlusal embrasures to end as retentive tags

ADVANTAGE DISADVANTAGESimple to fabricate Cannot be used in partially erupted toot as undercut not fully developed Provide adequate retention used only on posterior tooth ADAMS CLASP

Introduced by C PHILIPS ADAMS.UNIVERSAL CLASP,LIVER POOL CLASP ,MODIFIED ARROWHEAD CLASP22gauge 0.7mm

Parts:-A. Two arrowheadB. BridgeC. Two retentive arm

Two arrowhead engage the mesiobuccal and the distobuccal undercuts, connected by a bridge 2mm away at angulations of 45 to long axis of tooth and at level of middle third of crown.Arrow head continuos as retentive arm

AdvantagesExcellent retentionDifficult to fabricateCan be made on both primary and permanent toothGreater occlusal interferanceConstructed on any toothPartially or fully erupted toothRepaired by solderingPermit modifications in its designDisadvantages MODIFICATIONS

24 MODIFICATIONS

MODIFICATIONS

Adjustment:-1.Tightening the clasp by bending it gingivally at the point where wire emerges from base plate.2.Bending retentive arm inwardsANTERIOR ADAMS CLASP

Additional retention.

TRIANGULAR CLASPSmall triangular shaped clasps used between two adjacent posterior teeth

22 gauge -0.7 mm

TRIANGULAR CLASPDesign:-Parts:-A. Small triangle portion of 2-3mm sideB. A horizontal loopC.A vertical arm which continues as retentive arm.Apex of triangle:-positioned in embrasure.Base of triangle :-away from embrasure. Then wire is bent over the base of triangle, crosses the occlusal embrassure and continues as retentive arm.

.

Advantages:-No interference with oral hygieneDisadvantages:-No adequate retention.

Expansion plate with triangular clasp

SCHWARZ CLASPArrow head claspAdams clasp is a modification of this

Design:Parts:-A. Arrow head portionB. Vestibular portionC. Retentive armConstructed using arrow clasp forming and arrow clasp bending pliers. Head portion of arrowhead is bent gingivally towards the undercut. Vestibular portion is made in such a way it stands away from the soft tissue .

3 or 4 arrowhead s can be made depending on retention required .Anterior arm of clasp crosses over the mesial contact area of premolar/deciduous molar and continuous as retentive arm .poserior arm run distal to the last erupted tooth and ends on palatal or lingual aspect.

Advantages:-Better retention Disadvantages:-Bulky claspArrowhead causes injuryFabrication is difficult.Need special pliersUsed only on posterior teeth

CROZAT CLASP21 gauge-0.8mmDesign:-Full clasp with an additional piece of wire soldered at the base.

Advantages :-offers better retention than full clasp.Disadvantage:-Soldering machine required.

SOUTHEND CLASP22gauge-0.7mm

Design:-Wire adapted along cervical margin of both central incisor and passes across distolabial line angle and distal end carried over occlusal embrasure to end as retentive arm

Advantages:-Retention required in anterior segmentLimited undercutEsthetically more pleasing and less obstructiveDisadvantages:-cannot be used in proclined incisors

BALL END CLASPIndication:-Used as accessory clasp when additional retention is required.Design:-Consist of a knob or ball at one end of wire. Ball engages the proximal undercut. Distal end of wire passes over occlusal embrasure to end as retentive arm and a tag.

Ball end clasp engaging the lingual embrasure are given when removable appliance are used concurrently with fixed appliance. BASE PLATEBase plate serve as a framework for removable appliance,supporting active element transmitting the reactions to the anchorage also may sometimes be extended to act as bite planes or to provide inclined plane.Should be of minimum thickness 1.5 -2mm.Components of the appliance which exerts forces to bring about necessary tooth movement.ACTIVE COMPONENTSThe various types of Labial bows

Short labial bowLong labial bowSplit labial bowReverse labial bowRoberts retractorMills retractorHigh labial bow with apron springs Fitted labial bow

Labial bow Labial Bows Parts of labial bow 1. Incisor segment 2. Vertical loops 3. Cross over section 4. Retentive arm

Incisor segment

Usually in the junction of middle third and incisal thirdRight angle bend at the distal third of lateral incisors or mesial third of canine.Contacts only the most prominent teeth

Vertical loops Consists of parallel vertical legs joined by a smooth curve. Its usually 9 12 mm, extending 2 3 mm above the gingival margin. At the gingival level the loop is 1-1.5 mm away

Short labial bow

RETENTION0.7mm -22 gaugeBow:-Middle thirdLabial loop:-Middle third of canineREINFORCEMENT0.9 -1 mm-20 gauge LONG LABIAL BOWDesign:- 22 gaugeFirst premolar to other.Bows:-centre of crown.

Activation:-compress loop by 1-2mm,bow is displaced 1mm palatally.

LONG LABIAL BOW

INDICATIONS Minor anterior space closure Minor overjet reduction Closure of space distal to canine Guidance of canine during retraction Retention SPLIT LABIAL BOWModification of short labial bow.Design:-Horizontal arm split to increase flexibility.Activation:-compressing U loop by1-2mmModification used in closure of midline diastema.

MODIFIED SPLIT LABIAL BOW

9yr old boy,Mesiodens in between 11 and 21Extraction of mesiodensTreatment with active split labial bow

REVERSE LABIAL BOWDESIGN:-22 gaugeLoop -Distal to canine and bent at right angles to extent anteriorly.Short reverse labial bow:-Retentive arm is between canines and lateral incisor.Long reverse labial bow:-Retentive arm is between two premolars.

REVERSE LABIAL BOWActivation:-Step 1 :-opening of U loop, resulting in lowering of labial bow in anterior region.Step 2:-Compensatory bent given at the base of U loop ROBERTS RETRACTOR 24 gauge -0.5 mm Stainless steel wireDesign:-It has two helices of 3 mm internal diameter at base of U loop mesial to canine. Anterior vertical arm extent distal to lateral incisors and is parallel to the roots.

ROBERTS RETRACTORActivation:-Closing the coilIndication and advantagessevere anterior proclination.Range of action is longer.Disadvantage:-Not well tolerated and cannot be given in lower arch as sulcus is shallow.

MILLS RETRACTOR ( EXTENTED LABIAL BOW)Design:-Anterior part of bow extents till mesial to canine and forms a complex loop gingivally. Indication:-patients with large over jet.Disadvantages:-Difficult to construct and poor patient acceptance.

58HIGH LABIAL BOW WITH APRON SPRINGIndication:-Large overjet.Design:-Made of 0.9mm SS that extent into buccal vestibule Apron spring made of 0.4mm attached to high labial bow

Advantages:- used in retraction of one or more toothDisadvantages:-Difficulty in construction.

JOURNAL 1Journal of Indian Society of Pedodontics and Preventive Dentistry, Vol. 29, No. 1, January-March, 2011, pp. 57-61

Treatment of pseudo class 111 using modified hawleys appliance with inverted labial bowPRETREATMENTPOST TREATMENT

CASE REPORTAT TIME OF DELIVERYONE WEEK AFTER

SPRINGSClassification of springsThere are number of ways by which springs can be classified:Based on the presence of helix

Based on the direction of tooth movement brought about by the springs

Based on the type of force application

Based on the method of activation of coil

Based on the nature of support required for its action1.Based on the presence of helix : Cantilever principle of springSimple spring, less deflectionCompound or helical spring, more deflection with incorporation of coilLoop spring, more deflection2. Based on the direction of tooth movement brought about by the springs

Springs used for mesiodistal tooth movement : Finger spring, canine retraction spring

Spring used for labial/buccal movement: T-spring, Z-spring

Springs used for lingual movement: Buccal canine retractor

Spring used for the expansion of arches: coffin spring, quadhelix etc3. Based on the type of force applicationPush type : z-spring, T-spring, finger spring, palatal canine retractor

Pull type : Buccal canine retractor, reverse loop or helical canine retractor4. Based on the method of activation of coilOpen Coil (compression) spring : These are activated by opening up the helix. In other words the activation is done in the direction opposite to the making of the coil. The spring is then engaged in compressed state. The coil then tries to open and moves the tooth away from it.

Push type springs usually are open coil springs.

For open coil springs the active arm is towards the tissue side (below the coil) while the retentive arm is above the coil. Eg.: Z spring, T-spring, finger spring.Closed coil (Tension) springs: These are activated by closing the coil. In other words, activation is done in the same direction as making the coil. The active arm is engaged to the teeth in tension. The coil then tends to close and moves the teeth towards it.

Usually all the pull type springs are close type. For closed coil springs the active arm is above the coil while the retentive arm is towards the tissue side (below the coil).

Closed coil springs have more activation range than open coil springs eg., buccal canine retractor, reverse loop or helical canine retractor.Classification of springs based on their ability to withstand forces of distortionSelf- supported springs:Buccal canine retractorHelical loop canine retractorU loop canine retractorCoffin Springs

Guided Springs:Cantilever springsFinger SpringsPalatal canine retractorT Spring

Auxiliary springs:Apron springs SPRINGSKinetic energy stored in the form of loops and helices is transformed into potential energy to bring about tooth movement.PRINCIPLES OF DESIGNING SPRINGS F=KD4/L3F=forceD=diameter of wireK=flexibility constant/amount of deflectionL=length of the wire

Deflection:-Activation about 3mm is satisfactory.Rate of tooth movement:-1-2mm a monthMonthly adjustment sufficient.Force to be applied:-Single rooted tooth 25-40gDiameter of wire :-Flexibility depends on diameterDiameter decreased decreased force, gentle and continuous for long period

Parts of a spring :ABCA : Active armB : Coil or helixC : tag on retentive armFor maximum resilience, the coil should lie on the opposite side of the spring from the the tooth. So that it is bound up as the appliance is inserted and unwinds as the tooth moves.

Direction of tooth movement:-Tooth move in direction perpendicular to the tangent at the point of contact E.g:-Buccally placed spring to move tooth palatally

Length of wire:-Increased length-Force decreased-flexibility increased

Position of helix is very important - it must beplaced half-way between the starting position of the tooth and the desired finishing positionHELICE TOO FAR MESIALLY-TOOTH MOVES PALATALLYHelix too far distally - tooth will move buccally

Measurement of forceSpring gauge or dial type measuring gaugeDontrix:-Principle of spring gaugeMeasuring range:-28-450g approximatelyCorex:-Dial type measuring gaugeNo 1:-10 -100 gmsNo 2:-25 -250gmsNo 3:-100-500gmsNo 4:-200-1000gms

FINGER SPRING(SINGLE CANTILEVER SPRING)Indication :-Mesiodistal movement of toothUsed only on tooth that should be within the line of the arch.Design:-0.5 or 0.6mmActive arm:-12-15mm lengthTissue sideHelix:-3mm diameter.Along long axis and opposite to intented tooth movementRetentive arm:-4-5mm longAway from tissue.

Activation:-moving the active arm towards the teeth intented to be movedDone as close to coil as possible

Z PRING(DOUBLE CANTILEVER SPRING)Indication :- Labial movement of incisors.Minor rotation of incisors.Design:-0.5mm-24 gauge2 coils Spring :-perpendicular to palatal surface.Retentive arm :-10-12mm length.

Activation:-opening both helices by about 2-3mm at a time.Minor rotation correction:-one helices is opened.

Active component: Z-spring to 1/BITE OPENING: Posterior bite capping to 654 / 456 (more comfortable for patient)BASEPLATE: to connect everything togetherACTIVATE THE Z-SPRING.... Anterior cross bite12yr old male patient presented with anterior cross bite in relation to 11

Treatment:-Cemented posterior bite block with Z spring for 4 months

Pre treatmentPost treatment T SPRINGDesign:-T shaped arms ,loops incorporated in both arms of T.

Indication:-Buccal movement of premolars and sometimes canine.Activation;-pulling free ends of T towards intended direction of tooth movement.

Free ended springDESIGN:- -Gauge of wire-0.6mm -Parts-Mattress shaped with U loops extending as retentive arm. Engages close to gingival margin. MATTRESS SPRING

INDICATIONS labial movement of teeth in crossbite.

Free ended springDESIGN -Gauge of wire-0.6mm -Parts-Two helices on different arms with connecting arm. Supported by acrylic.Construction-generally made from 0.6mm wire with the connecting arm between the springs acting as part of the retentive arm.

HELICAL COIL SPRING

108Opening the helices Two sides can be activated by different amounts depending on amount of movement needed.Indications:- Used to regain lost extraction space. Used for mesial or distal movement after teeth have drifted into edentulous areaADJUSTMENT & ACTIVATION COFFIN SPRINGIntroduced by walter coffin.Indication:-slow dento alveolar arch expansion,unilateral cross bite or constricted upper arch.Design:-1.2 mm ss wire.U or omega shaped wire placed in midpalatal region.Retentive arm incorporated into base plate.

110Activation :-pulling the ends at region of clasp gently apart.1-2mm at a time.

Four registration points are drilled at the extremities of base plate for recording the amount of expansion by dividerBy pulling the sides apart manually, first in the premolar region and then in the molar regionActivation of 1-2 mm at a time appropriate CANINE RETRACTORS Used to move canine in a distal direction.CLASSIFICATION:Based on their location Buccal-Buccally placed. Palatal-Palatally placed.Based on presence of helix/loop Canine retractor with helix Canine retractor with loopBased on their mode of action push type pull type

U LOOP CANINE RETRACTORDesign;-0.6 or 0.7 mm wireUloop,active arm, retentive arm Base of U loop 2-3 mm below cervical margin

Mesial arm adapted around canine below mesial contact point.Retentive arm is distal.Activation:-closing U loop by 1-2mm/cutting free end by 2mm and readapting it.Mechanically least effective.

HELICAL CANINE RETRACTOR Reverse loop canine retractor,0.6mm wireDesign:-Helices of 3mm ,3-4mm below gingival margin.

Distal arm is active ,towards the tissue bent at right angles to engage canine.Activation:-Opening helix by 1mm/cutting 1mm of free end and readapting it.

PALATAL CANINE RETRACTORDesign:-0.6mmwire.coil of 3mm diameter. Placed along long axis of canine

Active arm placed mesial to canineIndication:-Retraction of palatally placed canineActivation:-Opening the helices 2mm at a time.

BUCCAL CANINE RETRACTORDesign:- 0.7mm wire coil of 3mm diameter ,distal to long axis of canineActive arm away from tissue

Indication:-Buccally placed canineTwo types:-Self supported:-Thicker gauge(0.7mm)Supported canine retractor;-0.5mm

Activation:-Self supported:-Closing the helices 1mm at a time

Supported :-closing helices upto 2mm

SCREWS

SCREWSDesign:-Removable appliance consisting of a split acrylic plate and adams clasp on posterior tooth. Screws connect the split plate and is parallel to intended tooth movement.

Indication:-Space necessary for correction is less than 3mm

Activation:-One quarter turn once weekly using a key,seperates acrylic 0.25mm,force ranging from 3-10 pounds,compress tooth in socket by 0.12mm per side,within the pdl space 0.25mm ,

Large intermittent force produced.

Case Report9yr old boy, pleasant profile, with chin deviated to right side by 3mm .Right maxillary segment tipped palatally .Mixed dentition with class 1 and half cusp class11 right molar relationship Overbite was deep .Mandibular midline deviated by 4mm.Case 2

APPLIANCE 1Source: The Saudi Dental Journal 2012; 24:105-113 (DOI:10.1016/j.sdentj.2011.12.005 )Copyright 2012 Terms and Conditions

126Insertion of first removable appliance to correct the anterior crossbite; jk screw and post bite plane

APPLIANCE 2Source: The Saudi Dental Journal 2012; 24:105-113 (DOI:10.1016/j.sdentj.2011.12.005 )Copyright 2012 Terms and Conditions

127Activated second removable appliance to correct the unilateral right posterior crossbite to expand right maxilla .Two adams and ball clasp was used

Post operativeSource: The Saudi Dental Journal 2012; 24:105-113 (DOI:10.1016/j.sdentj.2011.12.005 )Copyright 2012 Terms and Conditions

128Post-treatment extraoral and intraoral photographs.

4 months later129 CASE REPORT

8yr old girl Both central incisor in crossbite ,lateral incisor erupting.Class1 molar relation on both sides with a overjet of 2mm and 100 overbite.Sufficient spacing in maxillary arch to achieve labial movement of maxillary central incisor.In lateral cephalometry no bone pathology.

pretreatment

Removable appliance with a posterior bite plate and screw incorporated and activated for 16 weeksAfter 2 months incisors displayed edge to edge bite relationship.Cross bite corrected in another 2 month ,posterior biteplate then removed ,screw activation continued to gain 2 month to achieve overjet of 2mm.

AFTER 4 MONTH

During the treatment lateral incisor erupted ,left lateral incisor in cross bite .A new acrylic plate with a labiolingual spring was activated every 2 month till cross bite was corrected i.r.t 22. End of treatment by 8 month .Based on this study a removable appliance with screw is first choice of treatment to correct anterior crossbite when more than 1 incisor is involved.

After 6 month ELASTICSIndication:- for anterior retraction

Design:-Labial bow with hooks placed distal to canine..Latex elastics are stretched over them and lie over incisors.

Broadly classified based on manufacture and material used as:- -Natural or latex natural rubber -Synthetic or non latex polyurethane elastomersCLASSIFICATIONAvailable in various strengths which is dependant upon their diameter and thickness. Chosen according to the purpose. Color coded.Force 2 OZ 3.5 OZ 4.5 OZ 6 OZ 8 and 12 OZ Diameter 1/8WhiteClear or tooth colored 3/16RedGrayFiesta pinkClear or tooth colored 1/ 4BlueOrangeTealClear or tooth colored 5/16 YellowGreenTanMauveClear or tooth colored 3/8PinkLavenderNavyClear or tooth coloredAVAILABILITY CLASSIFICATION

CLASS 1 ELASTICSCLASS 11 ELASTICSCLASS 111 ELASTICS

BOX ELASTICCROSSBITE ELASTICANTERIOR ELASTICV ELASTICConclusion A removable appliance if thoughtfully designed, well constructed and carefully supervised can be successfully used to deal with simple cases of malocclussion . BIBLIOGRAPHYRemovable orthodontic appliance :-K.G.Issacson,J.D.Muir,R.T.LeadDesign construction and use of Removable orthodontic appliance:-C Philips Adams,W.john.rs-6th editionRemovable orthodontic appliance:-T.M.Graber,B.Newman 2nd editionOrthodontics The Art and Science:-SI Bhalajhi-4th editionThank you