atlas of removable orthodontic appliances.pdf
TRANSCRIPT
An Atlas of RemovableOrthodontic Appliances
Second edition
GORDON C. DICKSONB Ch U (Leeds).F D S, D Orth, R C S (Eng)Orthodontic Consultant to thePortsmouth Hospital Group
ALBERT E. WHEATLYF B I S T. M O T AChief Technician, Dental Wing, RoyalPortsmouth Hospital
CONTENTS
Preface 8 The Materials 10 The Tools 12 Anodic Polishing
Apparatus 14 Wire Bending 16 Construct ion of the Adams
Clasp 24 Variations of the Adams
Clasp 38 The Adams Clasp for
Extraoral Tract ion 40
Alternative Clasps
42 The Effect of a Finger-
spring 44 Resistance to Displacement
46 Resistance to Tooth Move-
ment (Anchorage) 50
The Simple Cantilever
Spring 56 Boxing-in 62 Paired Cantilever Springs
64 Double Cantilever Springs
66 The Kinked Cantilever
Spring 68 Premolar Retraction
Springs 70
Palatal Movement of Premolars and Molars 72
Mesial and Distal Move-ment of Incisors 74
Lateral Movement of Canutes 76
Labial Movement of Canines 78
Distal Movement of Canines 80
The Labial Canine Retractor 82
Sleeving the Canine Retractor 84
Adjust ing the Retractor
86 The Cut-and-bend Spring
88 Palatal Movement of
Lateral Incisors 90 The Sved Bile Plate 92 The Effect of a Bite Plane
94 The Labial Arch 96 The Labial Arch as a
Retainer 98 The Roberts Retractor
100 Construct ion of the
Roberts Retractor 102
Apron Springs 104
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Variations of, and Addit ions to, Labial Arches 106
More Variations of the Labial Arch 108
The Inverted Labial Arch 110
Space-maintainers 112 Expansion Screws 114 Asymmetrical Radial
Expansion 120 Distal Movement of
Buccal Segment (Schwarz) 122
Labial Movement of Upper Incisors (Schwarz) 124
Rotat ion of a Single Tooth 126
Rotat ion by Contra-acting Springs 132
Extraoral Tract ion 134 Extraoral Anchorage 138 Buccal Movement of
Premolars 144 Incisor Elongation 146 The Andresen Appliance 150 The Oral Screen 156
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THE M A T E R I A L S
Stainless steel wire
This must be H A R D POLISHED [Br i t ish Standard No. 3507 (1962)] Hard drawn, unpolished wire is inferior and should not be used. It is specified in metr ic diameter measurement and the correct sizes for each appliance wil l be found on the text-page opposite each appliance.
Stainless steel tube
Tubing may be HARD POLISHED or BRIGHT ANNEALED. It is usually specified by internal diameter only, the thickness of the tube wall being appropriate for orthodontic purposes.
Stainless steel tape
As used in orthodontics, tape is supplied SOFT, POLISHED ONE SIDE, the other side being mat t to facilitate adhesion of cement.
Acrylic resin
CLEAR acrylic denture base is used for the construct ion of all appliances, chiefly as it allows blanching of the tissues over pressure areas to be detected visually, and also because it shows more clearly when food debris has collected around the springs.
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THE TOOLS
For the vast major i ty of removable appliances lour instruments only are required.
1. Universal pliers
These are used for all wire bending wi th the exception of the format ion of loops or coils. The beaks are stout , tapered and rectangular in sect ion, and meet only at the tips. Beaks which are in contact throughout their length tend to eject a large diameter wire (Inset A ) . The beaks of Universal pliers are parallel when gripping the wire (Inset B). When the pliers become worn they should be resharpened, maintaining a beak size of 1 mm square at each t ip and cut t ing back so that a 0.6mm wire can be passed between them at the base when the pliers are closed.
2. Loop-forming pliers
These have round, tapered beaks around which loops or coils of various sizes may be formed.
3. Wire cutters
The diagonal type of wire cutter is used and must have hardened blades.
4. Hollow-chop pliers
Used for making bends in wires which are already anchored at both ends in an appliance, these pliers have one beak round and the other hol lowed so as to wrap round its opponent. They therefore exert pressure simultaneously at three points on the wire. They may also be used for increasing the bend in the labial canine retraction spring shown on page 82.
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A N O D I C POLISHING APPARATUS
The anodic polishing bath i l lustrated is used for reducing the diameter of stainless steel wire where a variation in thickness is required.
In use the positive pole is connected to the wire to be thinned using a crocodi le c l ip and so forming the anode. The cathode (negative pole) is formed of a stainless steel plate.
A current of 8 amps at 20 volts is suitable for most purposes. A variable resistance is unnecessary as the current can be varied by moving the anode nearer t o , or further f r o m , the cathode.
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WIRE BENDING, 1
Soft curves
For labial arches of all kinds, smooth curves are formed by holding one end of the wire f irmly on one hand and forming a curve with the thumb of the other hand. The thumb is then drawn firmly along the wire, creating a smooth curve of large radius. Repeating the process will increase the curve to any desired extent. Avoidance of the use of pliers will ensure a bend without kinks.
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WIRE BENDING, 2
Right angle bends
Hold ing ihc wire at right angles to the long axis of the pliers the wire is held against the thumb and the bend made by pressing the thumb f i rm ly on the wire as closely as possible to the plier beak. (For clar i ty in the i l lustration the thumb is shown a l i t t le too fat back.)
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WIRE BENDING, 3
Acute bends These are formed by holding the wire along the beaks of the pliers and bending firmly back with the forefinger.
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WIRE BENDING, 4
Small radius bends
Hold ing the wire at right angles to the plier beak the wire is bent with the thumb placed a short distance away f rom the bend.
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CONSTRUCTION OF THE ADAMS CLASP, 1
If desired the clasp may be pre-lightened by t r imming the plaster tooth as shown.
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CONSTRUCTION OF THE ADAMS CLASP, 2
Forming the bridge A careful estimate is made by eye of the mesiodistal width of the tooth. A piece of 0.7mm wire about 12cm (5in) long is held at right angles to the pliers at a point where the width of their beaks is equal to about two-thirds of the tooth-width.
Using the thumb and forefinger the two ends, which should be of equal length, are pushed backwards as far as the plier beaks will permit. The tips of the beaks are then used to increase these bends to slightly less than a right angle so that the ends of the wire cross each other.
A
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CONSTRUCTION OF THE ADAMS CLASP, 3
Forming the first arrowhead
As the length of the arrowhead will vary according to the height of the crown of the tooth to be clasped, this is first estimated and a bend made in a position which will place the bridge about half-way up the crown. This is made in two stages. First stage: a right angle bend as shown opposite.
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CONSTRUCTION OF THE ADAMS CLASP, 4
Forming the first arrowhead (contd.)
Second stage: this bend is increased by bending thc wire backwards over the beak-lips (as on page 21).
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CONSTRUCTION OF THE ADAMS CLASP, 5
Forming the second arrowhead
Holding the clasp in the position shown, the second arrowhead is formed in the same way as the first (Inset D). Each arrowhead is then squeezed lightly between the plier beaks (Inset E) to increase the sharpness of the arrowheads. This should not be carried to excess or the wire will later break at this point.
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CONSTRUCTION OF THE ADAMS CLASP, 6
Aligning the arrowheads
Each arrowhead in turn is held in the pliers as shown and bent until the plane of the arrowhead lies at about 45° to the bridge.
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CONSTRUCTION OF THE A D A M S CLASP, 7
Forming the togs
A right angle bend is formed at a level slightly below the bridge by holding the arrowhead as shown (the thumb has been wi thdrawn for c lar i ty) .
Over the contact point of the tooth a second, shallow bend is formed and the clasp presented to the t oo th . It is essential that the bridge should not lie in contact w i th the buccal surface of the tooth and these last bends should be increased if necessary to achieve this.
Finally the tags are completed by bending over the palate and the ends turned under and forced in to the plaster (page 25). The tags should lie out of contact with the plaster so that they wil l later be completely surrounded by acrylic material.
When the clasp has become slack in wear it is l ightened by increasing the bend in the tag at a point immediately overly ing the contact point of the too th .
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VARIATIONS OF THE ADAMS CLASP
The auxiliary clasp A. A second arrowhead is formed as shown and united to
the bridge of the main clasp using hard solder and stainless steel flux. The minimum amount of heat should be used and the solder should not be heavily polished, otherwise it will be removed entirely from the surface and will have no mechanical hold. Soldering may be carried out either on the model or after processing.
The incisor clasp
B. A single incisor can be clasped as shown in the left-hand diagram, the arrowheads resting against the mesiolabial and distolabial aspects of the tooth.
C. Two central incisors can be clasped as shown.
Materials
All clasps are made with 0.7mm wire.
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THE ADAMS CLASP FOR EXTRAORAL TRACTION
Where upper first premolars have been extracted an auxiliary arrowhead may be used (page 38) but this is not easy to adjust. A variation is to place arrowheads on the mesial of the second premolar and the distal of the molar as in diagram A
This form of retention is of value in extraoraI anchorage (page 138) but for convenience of accommodating adjustment loops of friction stops, ii is con-venient to offset the tubing in which the arch fits as shown in diagrams B and C.
Construction
Adams clasps Extraoral arch: Tubing.
Attachment of tubing
0.7mm stainless steel wire 1.25mm wire 1.25 internal diameter stain-
less steel Strapping with 2.0 x 0.1 mm stainless steel tape or binding with soft wire and soldering
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A L T E R N A T I V E CLASPS
Both the clasps il lustrated use the same principle as the Adams clasp i.e. retention f rom the undercut areas present on the mesiobuccal and distobuccal corners of the molar teeth.
The ball-ended clasp
A, B. Prefabricated ball-ended wires are bent in the f o rm shown and sprung in to the angular undercuts. Alterna-tively, stainless steel wire may be bent i n to a sharp, closed curve and cu t o f f short to replace the balls.
The Duyzings clasp
C. Two stainless steel wires are bent over the max imum contour of the t o o t h f r o m mesial and distal aspects and then curved back upon themselves so that the lower part lies below the max imum contour and the ends are sprung into the undercuts.
Materials
Both clasps are made f rom 0.7mm stainless steel wire.
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THE EFFECT OF A FINGERSPRING
A. On the tooth
Owing to the tact that the palatal surface of an upper incisor tooth has a downward and forward slope, it acts as an inclined plane and the horizontal forward thrust of a fingerspring is convened into an upward and forward thrust. In the case illustrated in diagram A the palatal surface is at 60c to the horizontal and the thrust may be divided, as shown by the length of the lines, into an upward component of two units and a forward com ponent of three units
B. On the appliance
Reciprocally, in accordance with Newton's Third Law of Motion, the tooth exerts a backward and downward force on the spring, as represented in diagram B. It follows that the clasps on such an appliance must be placed, not only to resist the backward thrust of the tooth, but also to resist a considerable downward dis-placing force.
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RESISTANCE TO DISPLACEMENT, 1
Downward displacement of an upper appliance
In diagram A a labial arch is used to retract upper incisors. There is a backward force on the incisor c o m -bined wi th a downward force due to the incl ined plane effect. Reciprocally a forward and upward force is exerted on the appliance. Only the forward force is resisted by the clasped molar tooth (black) while the palate acts as a fu lcrum and receives the upward force.
In diagram B a palatally placed spring is mov ing the incisors forward. The incl ined plane of the tooth here exerts a backward and downward force on the anterior part of the appliance, which would pivot on the clasped first molar (black). Addi t iona l clasps must be placed on the first premolars (black) to produce an upward com-ponent and prevent displacement.
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RESISTANCE TO DISPLACEMENT, 2
A lingually placed spring exerts a forward force on the sloping surfaces of the lower incisors and consequently receives an upward and backward thrust f rom the teeth. A clasp placed on the first premolar (black) acts as a fu lcrum about which the appliance wi l l p ivot, t i l l i ng the posterior end downwards.
The downward thrust is countered by placing an occlusal rest on the second molar tooth (black), so giving an upward thrust and stabil izing the appliance. ( I f the second molar is uncrupted the occlusal rest may be placed on the distal por t ion of the first molar )
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RESISTANCE TO TOOTH MOVEMENT (ANCHORAGE), 1
Retraction of labial segment
A. If, following extraction of first premolars, an attempt is made to retract the entire labial segment at once, the only teeth resisting this movement are the four remaining posterior teeth. It may be expected, therefore, that the forward movement of these teeth will exceed the backward movement of the incisors and canines.
B. When the canines alone are retracted the incisors take part in the anchorage. Only two teeth are being moved against an anchorage of eight teeth. Although these will inevitably undergo some slight forward movement, this will be small compared with the distal movement of the canines.
C. The canines now being in the fully corrected positions, an appliance designed to retract only the four incisors can utilize all the six remaining teeth as anchorage, so producing a major movement of the incisors with l i t t le further forward movement of these teeth.
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RESISTANCE TO TOOTH MOVEMENT (ANCHORAGE), 2
D. Distal movement of a buccal segment
Following extraction of an upper second molar the first molar and both premolars of that side may be moved distally, three teeth moving against an anchorage of nine teeth. The labially displaced canine is not included in either part of the appliance.
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RESISTANCE TO TOOTH MOVEMENT (ANCHORAGE) , 3
The proper application of extraoral traction
A At the commencement of extraoral t ract ion designed to move ail the upper teeth posteriorly fo l lowing extract ion of second molars, the labial arch is bent away f rom the labial segment. Al l the extraoral force is then directed against the cheek teeth, which wi l l move distal ly.
B. At the complet ion of distal movement of the cheek teeth the labial arch is bent back to rest against the labial segment, not to press against i t . When the extra-oral force is applied the labial segment wi l l move posteriorly. At the next visit the labial arch wi l l be seen to stand away f rom the incisors Until the extraoral force is applied. It can then once more be adjusted to rest against the anterior teeth.
C. If the labial arch is adjusted (via the U-loops) to press against the incisors, appl icat ion of the extraoral force wil l increase pressure on the incisors, but wi l l not release the forward force on the cheek teeth produced by the tension in the U-loops. The anchorage problem generated within the appliance is not removed by the application of extraoral force.
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THE SIMPLE C A N T I L E V E R SPRING. 1
Parrs of the spring
A, A simple cantilever spring consists of three parts. The tag is embedded in the acryl ic resin of the support ing baseplate. The coil is the active part of the spring and is normally made so that it tends to open, rather than close, in use. The arm of the spring undergoes only slight bending and may be regarded as a rigid lever.
Direction of pressure
B. As fr ict ion between the spring and the tooth can be ignored, the direction of pressure wil l always be at right angles to the arm of the spring and, if the spring has to work over a long angular range, this wi l l change con-siderably during too th movement. The path traced by the t ip of the spring is known as the Path of Act ion.
C. The longer the arm of a spring the greater wi l l be its range of act ion. A short spring not only has a short range of action but, as it moves, its tip describes an arc of a small circle. As its length increases so this arc becomes straightened and its path of action is nearer to a straight l ine. As length increases, so the spring must be made of thicker wire to exert the same force,
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ACTIVATING THE CANTlLEVER SPRING
A small, controlled and accurate amount of tension can bo given to cantilever springs by squeezing the coil in the tips of the universal pliers as in diagram A. This produces a slight flattening of the curve, exaggerated for clarity in diagram B.
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THE SIMPLE CANTILEVER SPRING
The spring illustrated is moving .in upper incisor 'over the bite'.
The arm of the spring is set at right angles to the intended path of the tooth to be moved and is lelt long so as not to lose contact with the tooth towards the end of its movement.
Ihe coil is set as far away as possible from the tooth to be moved
The tag is short and well within the thickness of the acrylic.
The bite is raised on the cheek teeth either by a thickness of acrylic resin or, as shown here, by a single wire passing over the occlusal surfaces of the cheek teeth. This is used where the thickness of acrylic capping (see Inset A) would be too little to stand the bite with-out fracture;
Inset B shows the same spring adapted to move two teeth
Construction
Springs: 0.5mm boxed-in Retention: Adams clasps on 64/46 Bite-raiser: 10 mm wire or acrylic capping Baseplate: Full palate
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BOXING-IN
The purpose of boxing-in is to protect the spring from damage and to act as a guide along which the arm can slide. At the time the spring is constructed and tacked to the plaster model with wax, it is covered with a small amount of thin plaster which is shaped up with a knife, care being taken to note the following points.
1. It should extend beyond the tip of the spring and should have a smooth outline,
2. It should have a smooth, flat upper surface.
3. It should continue this smooth, flat surface right in between the teeth
4. As the teeth move forward so the control excited by the capping is lost, It is possible lo use instead a guide wire, as illustrated. This can be advanced as the teeth move by squeezing the sides with pliers. The guide is made of 0.7mm soft stainless steel wire
After appropriate protection the plaster is covered evenly with baseplate wax and processing completed. A check should then be made to ensure that the spring has free travel without Fouling any projection of the baseplate.
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PAIRED C A N T I L E V E R SPRINGS
Where four incisors are to be moved over the bi te, each spring moves the central and lateral incisor nearest the end of the spring.
Construction
Springs: 0.5mm boxed-in Clasps: 0.7mm Retent ion: Adams clasps on 64/46 Baseplate: Continued over all check teeth as capping
Inset A
This lateral view shows boxed-in spring and just sufficient clearance to al low the upper incisors to move forward wi thout foul ing the lowers.
Inset B A double cantilever spring may be used as an alternative for the same too th movement (0 .6mm wire), bu t this requires a greater degree of skil l in adjusting.
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DOUBLE CANTILEVER SPRINGS
Forward movement of two upper lateral incisors, may be carried out by means of two small double cantilever springs which can be used to vary the direction of move-ment, or where space for the spring is confined.
Construction
Springs; 0.5 mm boxed-in Clasps: Adams clasps on 64/46 Baseplate. Full palate (capping on cheek teeth if
the lateral incisors must pass over the bite)
Inset A
Lateral movement is produced by opening the right-hand coil
Inset B
Forward movement is produced by opening the left hand coi l
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THE KINKED CANTILEVER SPRING
Interference with the movement of the spring by the palatal surface of a premolar may prevent a simple spring moving a palatally displaced canine into the arch. This is overcome by kinking the spring, which still behaves as a lever pivoting on the coil.
Construction
Spring: 0.6 or 0.7mm boxed-in Clasps: Adams clasps on 6 4 / 6 Baseplate: Full palate (capping on cheek teeth if
the canine must pass over the bite)
Inset The position of the spring at completion of tooth move-ment
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PREMOLAR RETRACTION SPRINGS
TWO alternative springs are shown, one incorporating a guide wire and one boxed-in, both moving the first pre-molar distally into an extraction space.
Construction
Left side Right side Springs: 0.6mm 0,6mm with guide wire
boxed in Clasps: Adams clasps Adams clasps on 6/6
on 6/6 Baseplate Full palate Full palate, cut away
to expose spring
Inset
The spring must follow as closely as possible over the contact point.
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PALATAL MOVEMENT OF PREMOLARS AND MOLARS
Buccally displaced teeth may be moved palatally by means of springs passing between the teeth. On the left an upper molar is being moved; on the right t w o pre-molars are being moved, both using a buccally placed co i l .
Materials
Clasp: 0.7mm Spring: 0.6mm Tape: 2 . 0 x 0 . 1 mm Solder and f lux
Construction
Springs: 0 .6mm Clasps: Adams clasps on any cheek teeth not
being moved Baseplate: Ful l palate, cut away to allow palatal
movement of teeth
Inset This shows the level of the arm of the spring and the large coil in an alternative design where the spring is attached to the molar clasp.
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MESIAL A N D D I S T A L MOVEMENTS OF INCISORS
Tour palatally plated fingersprings are used. A. This diagram shows distal movement, the posit ion of the
coil of each spring being carefully placed to carry the too th in the desired direct ion. Here the springs are boxed-in.
B. This diagram shows mesial movement, but here the path of movement of the teeth is not only dictated by the position of the coils of the springs but is guided by a labial arch and a palatally placed guide wire which prevents them 'wandering' in an anteroposterior plane. The springs are no t covered by the baseplate.
Construction
Springs: 0 .6mm Labial arch: 0 .7mm Guide wire: 0 .6mm Clasps: Adams clasps on 6 /6 Baseplate: Ful l palate in A
Ful l palate cut away in B
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L A T E R A L MOVEMENT OF CANINES
Simple cantilever springs are i l lustrated, the posit ioning of the coil being dictated by the direct ion of t oo th movement. Both springs are uncovered and control led by guide wires, this faci l i tat ing insertion of the appliance by the patient.
Construction
Springs: 0.6 or 0 .7mm Guide wires: 0 .7mm Clasps: Adams clasps on 6/6 Baseplate: Ful l palate, cut away to expose springs
and if necessary carrying bite platforms on all the cheek teeth to al low the canines to move over the b i te
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L A B I A L M O V E M E N T OF CANINES
A covered canine spring is d i f f icu l t for the patient to insert if any degree of activation is appl ied: in this appliance (designed by R. Hanney) the spring is kinked in the middle of the arm and the baseplate is corre-spondingly cut away. The spring thus has the protective advantages of boxing-in yet the patient can engage the kink wi th a fingernail and so compress the spring to facilitate insertion of the appliance.
Construction
Spring: 0 .6mm boxed-in Clasps: Adams clasps on 6/46
Space-holding clasps on 42 / : 0 .6mm Baseplate: Ful l palate, with cut-away in cover for
spring. Bile platforms where necessary
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D I S T A L M O V E M E N T OF CANINES
Palatally placed cantilever springs are used, their coi ls being placed so as to give movement of the canines along the arch wi thout displacing them either l ingually or buccally.
Inset To avoid sliding down the mesial slope of the canine the spring is careful ly bent so as to f i t between the lateral incisor and canine and to take advantage of the f lat mesial surface of the tooth. Once movement has begun it can be modi f ied to f i t round the neck of the too th .
Construction
Springs: 0 .7mm boxed-in Clasps: Adams clasps on 6 /6 Baseplate: Ful l palate
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THE L A B I A L CANINE RETRACTOR
This is one of the few springs in which the coi l is made to close rather than to open in act ion. The coi l lies in the labial sulcus.
Points to note
1. The end of the spring should be bent at a r ight angle before being shaped to the curve of the t oo th , l ike a golf-club.
2. The loop should lie as high as possible in the sulcus w i thout interfering with any f o l d of soft tissue commonly found in this area.
3. The tag should lie as close as possible to the second premolar, and the posterior arm should not cut across the first premolar posit ion where it would interfere w i th retraction of the canine.
Construction
Spring: 0 .7mm wire or 0 .6mm sleeved (see page 84) Retent ion: Adams clasps on 6 /6 Baseplate: Full palate, cut away to allow movement
of canines
Inset A
Shows (1) Posterior arm in contact w i th second pre-molar and passing over the contact point of this too th .
(2) Golf-club end of anterior arm, sharpened at t ip .
Inset B Shows (1) Path of act ion.
(2) Clear area behind the canine, unobstructed by the spring.
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SLEEVING THE CANINE RETRACTOR
1. Sleeve prepared (upper end chamfered). 2. Sleeve passed over the posterior arm. 3. Sleeved portion bent over to complete the posterior
arm and form the tag.
Materials Spring: 0.6mm hard polished stainless steel Sleeve: 0.6mm internal diameter soft (annealed}
stainless steel tube
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ADJUSTING THE RETRACTOR
1. Increasing the tension As the coil is in the reverse direction to that of the fingerspring it cannot be adjusted In the same way. Increased tension is produced by bending the anterior arm using 'hollow-chop' pliers such as Marthews' or Andresen's. A. Position of the plier beaks on the anterior arm. B. Resultant bend.
2. Lowering the spring on the tooth
C. Position of the plier beaks on the posterior arm, D. Coil and anterior arm lowered.
3. Raising the coil
E. Position of the plier beaks on the posterior arm. F. Coil and anterior arm raised. This must be followed
by a downward bend of ihe anterior arm as in A and B.
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T H E CUT-AND-BEND SPRING
Al though the spring requires frequent adjustment, it can be used where a low labial sulcus prevents the use of the labial retractor described on pages 82 and 84, yet where a palatal component of movement is needed. It is also useful in lower appliances where there is rarely any depth of sulcus.
The spring may touch the labial surface of the canine for palatal movement (as on left of i l lustrat ion) bul is well clear of the tooth anterior ly except where the l ip touches the mesial aspect of the l oo th .
To activate the spring the t ip is bent back about 1 mm. When the tooth has moved by this amount, 1 mm is cut off the t ip of the spring and the bend remade so that the shape of the spring is maintained (Inset B).
Construct ion
Spring: 0.6mm Clasps: Adams on 6/6 Baseplate: Ful l palate
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PALATAL MOVEMENT OP LATERAL INCISORS
Individual springs are preferred to a ful l labial arch which, wou ld f ou l the central incisors. Each spring is f lat tened at the t ip on an anvi l , tapered in the anodic pol ishing bath and bent to a golf-club and before adapting it to the too th . Pressure should be exerted as near to the t ip of the tooth as possible and the springs are activated w i th hol low-chop pliers.
Construction
Springs: 1.0mm wire thinned to 0.6mrn anodically
Retent ion: Adams clasps on 6/6 Baseplate: Full plate, cu t awaybeh ind 2/2
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THE SVED BITE PLATE
This is i l lustrated in combinat ion w i th canine retractors, though it may be used alone. Pressure on the bite plane by the lower incisors is transferred to the upper incisors instead of to the soft tissues.
Construction
Springs: 0.6mm sleeved Retention: Adams clasps on 6 /6 Baseplate: Pull palate and covering tips of upper
incisors, thickened to form bite plane
Inset A
This shows relationship of lower incisors to bite plane which must be extended suff ic ient ly to make it impossible for the lower incisors to bite behind i t . It is necessary to mount the models on an art iculator for this purpose
Inset B Should this open the bite on the check teeth by more than 3 or 4mm, the plane should be lowered, and later in treatment i t can be raised by adding co ld cur ing acrylic resin.
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T H E EFFECT OF A BITE PLANE
A bite plane such as that used in the Sved plate exerts a variable force on the lower incisors depending on its incl ination.
A. A plane at 45° exerts as much forward force on the opposing teeth as it exerts downward — for example, a force of 85g (3oz) is divided in to two forces each of 42.5g(1.5oz) .
B. A plane at 30° to the horizontal would divide a similar
force into 56.7g (2oz) downward and 28.3g (1oz) horizontal ly.
C. A horizontal plane exerts al l i ts force downwards.
It should be noted that the appliance itself receives equal and opposite pressures to those exerted on the opposing teeth.
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THE L A B I A L ARCH
This, the simplest fo rm of incisor retract ion, is f i rm and positive in action but works over only a short range and consequently requires frequent adjustment.
The arch itself should make contact w i th the incisors about half-way up the crowns; the U-loops l ie over the canines and should be tall enough to faci l i tate adjustment. This is carried ou t by closing the loops w i th ho l l ow chop pliers.
The baseplate is cut away a l i t t le at a l ime behind the incisors, keeping slightly in advance of their movement.
Construction
Labial arch: 0 .7mm wire Retent ion: Adams clasps on 6/6 Baseplate: Ful l palate
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T H E L A B I A L ARCH AS A R E T A I N E R
The fitted labial arch
This is used to secure the incisors f i rm ly after they have been rotated. It is here shown w i th a short steep bite plane to maintain the posit ion of the lower incisors after they have been depressed (Inset B).
Inset A shows the reverse loops which may be employed w i th this arch or w i t h the plain labial arch when it is desired to cont ro l the posit ion of the canines.
Construction
Labial arch: 0 .7mm wire Retent ion: Adams clasps on 6 /6 Baseplate: Full palate, thickened anter ior ly to
f o rm bite plane
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THE ROBERTS RETRACTOR
This adaptation of the labial arch designed by G. H. Roberts consists of two sleeved Canine retractors joined to form an apron spring. It is suitable only for retraction of the four upper incisors following previous retraction of the canines. Forward relapse of the canines is prevented by spurs on their anterior surfaces, contoured to pass incisally to the contact point.
The arch should lie half-way up the crowns of the teeth (Inset A) and should extend only two-thirds of the width of the lateral incisors; otherwise adjustment becomes difficult towards the end of tooth movement. The baseplate is cut away in advance of tooth move-ment in the manner shown in Inset B.
Construction Retractor: 0.5mm wire sleeved in 0.5mm internal
diameter soft stainless steel tubing Spurs: 0.6mm wire Retention: Adams clasps on 6/6 Baseplate: Full palate
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CONSTRUCTION OF THE ROBERTS RETRACTOR.
The diagram shows how chamfered annealed stainless steel tubing is slipped over the ends of the Spring before bending the posterior arms to form tags as in the con-struction of the canine retractors.
Materials
0.5mm hard polished stainless steel wire 0.5mm internal diameter bright annealed
stainless steel tubing
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APRON SPRINGS
A high labial arch incorporat ing a step in each vertical arm carries a light wire spring which lies half-way down the crowns of the incisors. If the incisors arc spaced it is important no t to carry the arch too far across the lateral incisors.
After bending the spring in to shape it is attached by winding round the labial arch close to one of the angles, two or three turns being taken round each of the horizontal and vertical arms (Inset A ) . It is activated by bending the upright arms of the apron spring w i t h hollow-chop pliers. The palate is cut away in advance of the too th movement .
Construction
High labial arch: 1.0mm wire Apron spring: 0 .35mm Retention: Adams clasps on 6/6 wi th
ancillary arrowheads on 5/5 Baseplate: Ful l palate
Inset B
Shows an individual apron spring to retract a central incisor. Here the spring is strapped on to the arch by stainless steel tape which is welded t ightly round both wires. The spring is wound round the high labial arch on both sides of the strap and again, loosely, at the opposite end of the apron spring.
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VARIATIONS OF, AND ADDITIONS TO, LABIAL ARCHES
Sometimes, after the upper incisors have been retracted, it is found that the canine stands too far labially. The 'bridge spring' illustrated can be taped on to a 0.7mm arch as at diagrams A and C or simply wound on as shown at diagram B.
Materials
Labial arch: 0.7mm Bridge spring: 0.35mm extra hard stainless steel Tape: 2.0 x0.1mm
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MORE V A R I A T I O N S OF THE L A B I A L ARCH
A. Flexible 0.7mm labial arch with bends to conlro l the canines.
B. Flexible 0.7mm labial arch with extended labial section to control canines.
, D. Flexible 0.7mm labial arches designed by J. R. E. Mil ls. These may also be extended to contro l canines. They are activated mainly wi th the fingers.
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THE INVERTED LABIAL ARCH
Whilst lingually occluding upper incisors may be moved 'over the bite' by means of palatal cantilever springs alone, additional backward movement of the lower incisors with an inverted labial arch greatly shortens treatment time. This arch exerts Class III intermaxillary traction.
The bite is propped open on all the cheek teeth. It is essential that a retrusive bite in the slightly open position is taken and the models placed on an articulator before bending the arch, the vertical arm of which should lie well clear of the lower canine and premolar (Inset A).
The arch is activated by bending back slightly with the thumbs until the lower incisors will only just pass behind it. As the mandible closes it swings forward (Inset B) so that the arch is slightly flexed. The palatal springs are simultaneously brought into action.
Construction Inverted labial arch: 1,25mm wire anodically
thinned to 0.8mm wire or sleeved as shown in Inset C
Palatal springs: 0.5mm wire boxed-in Retention: Adams clasps on 64/46 Baseplate: Full palate and covering all
cheek teeth sufficiently for upper incisors to clear lowers
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SPACE-MAINTAINERS
The appliance shown is to maintain the space for any unerupted canine fo l lowing extract ion of first premolars. HaIf clasps around the teeth adjacent to the space prevent movement of the lateral incisors and second premolars. The baseplate is cut away well clear of the erupt ing canine and the lags of the half-clasps are placed so as to al low further cut t ing of the baseplate if necessary.
Construction
Half-clasps: 0 .6mm stainless steel wire Retention: Adams clasps on 6/6 Baseplate: Pull palate
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EXPANSION SCREWS, 1
Direct lateral expansion
The appliance shown is to move l ingual ly, occluding upper molars and premolars in to normal relationship w i th their opponents.
Correct placing of the screw is of the utmost importance and the fo l l ow ing points should be careful ly observed.
Af ter plastering the screw according to the maker's instruct ions it should be placed: 1. as deep in the palate as possible, 2. between the first premolars, 3. w i th its long axis parallel to the occlusal plane, 4. at right angles to the median raphe.
Rate of activation
Using a screw w i th one end threaded, this is one quarter-turn per day ; a screw w i th both ends threaded, one quarter-turn every other day.
Construction
Screw; A screw of hard metal such as stainless steel, w i th guide pins intact , should be used and its length should be adequate
Retent ion: Adams clasps on 64 /46 Baseplate: Ful l palate, divided down the centre
after processing
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EXPANSION SCREWS, 2
Radial expansion
Lateral movement of the premolars and canines is achieved by unit ing the two halves of the appliance across the posterior border w i t h a t ie-wire so that the appliance hinges at the back and opens fanwise. It fol lows that the screw must open on a curve. Special screws have been manufactured to permit this to take place, but it is qui te satisfactory to use a loose, soft-metal screw such as the Badcock screw wi th the guide pin cut o f f (Inset B).
The screw must be positioned as fo l lows: 1. as far forward as possible, 2. as high in the palate as possible (Inset A ) , 3. at right angles to the median raphe, 4. w i th its long axis parallel to the occlusal plane.
Rate of activation
The screw is given one quarter-turn twice a week.
Construction
Screw: Soft metal w i th guide pin removed Tie; 0 .9mm stainless steel wire Labial arch: 0.7mm stainless steel wire Retent ion: Adams clasps on 6 /6 Baseplate; Ful l palate, divided through the mid
l ine after processing
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EXPANSION SCREWS, 3
Asymmetrical expansion
Correction of unilateral lingual occlusion of the cheek teeth (and sometimes a canine and a lateral incisor) presents problems in anchorage due to the tendency of the l ingually occluding side to resist movement more than the normal side. The appliance il lustrated raises the bite on the cheek teeth on both sides and carries a lingual flange on the normal side, to engage wi th the lower cheek teeth and so to add them to the anchorage. A short stainless steel screw should be used, placed near to the centre of the segment to be moved, wi th its long axis parallel to the occlusal plane and at right angles to the line of the cheek teeth. Spurs or half-clasps engage
21/. Rate of activation
The screw is usually turned at the rate of two quarter-turns per week.
Construction
Spurs: 0.6mm stainless steel wire Screw: Short, stainless steel Retention: Adams clasps on 64/46 Baseplate: Ful l palate, divided as shown and
carrying a smoolhed-of f b i t ing section on the small segment and a b i t ing section indented by the lower teeth and wi th a lingual flange on the ' f i xed ' side
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A S Y M M E T R I C A L R A D I A L EXPANSION
The i l lustrat ion shows an appliance to regain space loss in the region of a labially displaced lateral incisor.
As the appliance is joined by a tie at the posterior border a soft metal screw is used. The guide p in is removed and the screw angulated so as to lie along the circumference of a circle which has the tie as i ts centre. As wi th all other screws, it must lie parallel w i th the occlusal plane.
Rate of activation
The screw is turned at the rate of two quarter-turns per week.
Construction
Screw: Soft metal (Badcock type) Tie: 0.9mm stainless steel wire Spurs: 0.6mm on 3 1 / . Retent ion: Adams clasps on 64/46 Baseplate: Full palate, divided as shown
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DISTAL MOVEMENT OF BUCCAL SEGMENT (SCHWARZ}
Distal movement of an upper buccal segment after extraction of the second molar can be accomplished by means of the appliance illustrated. A hard metal screw is placed with its long axis parallel to the line of the segment to be moved and to the occlusal plane. A short, steep inclined plane is incorporated to assist anchorage by applying some forward pressure to the lower incisors (Inset). A spur or half-clasp on the left lateral incisor prevents this tooth drifting distally.
Rate of activation
The screw is turned at the rate of one quarter-turn per week.
Construction Screw: Hard metal (stainless steel) with guide
pin Spur: 0.6mm stainless steel wire Retention: Adams clasps on 64/46 Baseplate: Full palate with anterior inclined plane,
divided by two cuts, one across the screw and the other exactly parallel with the buccal segment to be moved and with the long axis of the screw
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LABIAL MOVEMENT OF UPPER INCISORS (SCHWARZ)
Although this appliance is somewhat bulky it has the merit that the screw can be adjusted by the patient. The screw should be placed as close as possible to the incisors and as low as possible without tilting and while retaining parallelism with the occlusal plane (Inset). Spurs or half-clasps arc placed distally on 2/2 and mesially on 3/3.
The bite is raised on all the cheek teeth so as to clear the overlap of the incisors.
Rule of activation
The screw is turned at a rate of one or two quarter-turns per week, the slower rate being used if the appliance tends to slip off the teeth.
Construction Screw: Stainless steel, minimum bulk Spurs: 0.6mm on 32/23 Retention: Adams clasps on 64/46 Baseplate: Full palate, with capping over molars and
premolars, divided transversely as shown
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R O T A T I O N OF A SINGLE T O O T H , 1
Rotat ion may, w i t h d i f f i cu l ty , be carried ou t by using a 'couple' - a pair of springs exert ing pressure in opposite directions on the mesial and distal corners of an incisor tooth. Unfor tunate ly, this f requent ly results in shortening of the too th and is not applicable to canines which are of unsuitable shape.
The long 'wh ip ' or 'capstan' spring i l lust rated is attached to a standard twin-wire channel or W-lock as shown in Inset C. Construct ion of the band and channel may be in welded stainless steel or , for those who do not possess a welder, in whi te gold al loy which is soldered.
When first made, the spring wil l project f rom the
mouth and is held down by a project ion from a separate
removable appliance (Inset A ) , which wil l usually com-
plete the alignment of the tooth wi thout further adjust-
ment. Subsequently the spring may be k inked outwards
to continue the movement and over-rotate the t oo th , so
reducing the retention period. This over-rotation usually
results in labial displacement of the too th and if this is
expected a labial arch may be incorporated (Inset B). In
this case the retaining spur may be welded or soldered to
the arch.
Construction
Incisor band: 3.0 x 0 .1mm soft stainless steel tape OR 3.0 x 0.15mm white gold tape
Channel: 3.0 x 0 . 1 m m (OR 2.0 x 0 .1mm) stainless steel tape OR 3.0 x 0.15mm (OR 2.0 x 0.15mm) wh i te gold tape
Spring: 0.35mm extra hard stainless steel wire Retaining spur: 0 .7mm soft stainless steel wire Labial arch: 0.7mm stainless steel wire Retent ion: Adams clasps on 6 /6 (or other
available teeth) Baseplate: Ful l palate, cut away f r o m t o o t h to
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R O T A T I O N OF A SINGLE TOOTH, 2
A l though the appliance shown on page 127 may be modi f ied to suit ro ta t ion of a premolar too th , the appliance i l lustrated opposite offers more cont ro l as the labial arch is extended distally to an attachment on the molar clasp on one side. Such attachment may be made by welding straps of steel tape over both arch and clasp or by soldering. In this appliance the end of the rotat ion spring is formed in to a three-quarter collar around the arch as shown in Inset B. The thicker wire of the arch forms a protect ion for the more vulnerable ro ta t ion spring (Inset A ) .
At the complet ion of treatment by either appliance, cold cur ing acrylic resin may be added to the cut-away port ion of the baseplate after removing the band and the appliance converted to a retainer.
Construction Premolar band: 3.0 x 0 .1mm stainless steel tape OR
3.0 x 0.15mm white gold tape Channel: 2.0 x 0.1 mm stainless steel tape OR
2.0 x 0.15mm while gold tape Strap: 2.0 x 0.1 mm stainless steel tape Spring: 0.35mm extra hard stainless steel wire Labial arch: 0 .8mm stainless steel wire Retent ion: Adams clasps on 6/6 Baseplate: Ful l palate, cut away around
premolar tooth
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ROTATION OF A SINGLE T O O T H , 3
With the development of acid-etch preparation of enamel pr ior to bonding wi th composite f i l l i ng materials, it has become possible simply to attach a spring to the labial or buccal aspect of a tooth (diagrams A and B). The spring may be attached wi th carding wax to an adjacent tooth while the composite sets.
Over-rotation
To achieve good final alignment it is common practice to over-rotate and to retain in the over-rotated posit ion for six months. To avoid displacing the adjacent tooth it is necessary to bend a dog-leg in the spring as in diagrams 3 and 4.
Construction
Spring: 0.35mm extra hard stainless steel wire Composite: Any composite f i l l ing material
suitable for acid-etch retent ion Baseplate, etc: As on page 129.
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R O T A T I O N BY CONTRA-ACTING SPRINGS
When two springs act in opposite directions on opposite corners of an incisor tooth the force produced is k n o w n as a 'couple'. Such an appliance is i l lustrated and its purpose is to rotate the two lateral incisor teeth.
Some ingenuity is required to k ink the springs and the labial arch so as to fo l low the rotary movement of the teeth (Inset). Nevertheless, such an appliance can be effective, provided that slight shortening of the lateral incisor is acceptable.
Construction
Springs: 0 ,5mm stainless steel wire (boxed-in) Labial arch: 0.7mm stainless steel wire Retention: Adams clasps on 6/6 Baseplate: Fu l l palate, relieved around 2/2
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E X T R A O R A L FRACTION, 1
When it is necessary to retract the upper labial segment w i thout exert ing any forward force on the cheek teeth, the appliance illustrated may he used. It differs only in its application f rom that shown in plan view on page 137.
Four clasps provide f i rm retention and a f lexible U-loop labial arch is attached distal to the canines, taking care not to obstruct any distal movement of these teeth. The extraoral 'whiskers' are attached ei ther by strapping and soldering or by banding wi th soft wire and soldering as shown in the Insets on page 137. The junction of the labial arch and the extraoral arch is the vulnerable point and it may be reinforced by sl iding tub ing over the labial arch prior to bending.
Several forms of cervical traction can be constructed w i th webbing and elastic but as ready-made neckbands and neckpads (such as Orthoband) are easily available and quite satisfactory it is this which has been i l lustrated
Construction
Extraoral arch: 1.25mm stainless steel wire Labial arch: 0.9mm stainless steel wire Retention: Adams clasps on 6 4 / 4 6
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E X T R A O R A L T R A C T I O N , 2
Backward movement of all the upper teeth may now be readily accomplished wi th removable appliances if the second molars have been extracted; this applies also if 4/4 have been extracted and the space lost. F i rm reten-tion is required and a Cof f in spring is used to increase upper arch width and so avoid development of a molar cross-bite.
Movement is in two phases. The cheek teeth are moved dislally in Phase I by opening the U-loops and Standing the arch 2mm away f r om the incisors. In Phase II (retract ion of the labial segment) the labial arch is allowed to rest on the incisors but should not press unt i l the elastic traction is applied. This avoids moving the cheek teeth forward again (see page 55).
Construction
Coff in spring: 1.25mm stainless steel wire Extraoral wires: 1.25mm stainless steel wire Labial arch: 0.9mm stainless steel wire Retent ion: Adams clasps on 64/46 Baseplate: Two sections extending f rom mesial
of 3/3 to distal of 6/6 Attachment of Strapping wi th 2.0 x 0.1 mm extraoral arms: stainless steel wire OR binding wi th
soft wire and soldering
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EXTRAORAL ANCHORAGE, 1
Forward movement of anchor teeth during retraction of anterior teeth may be anticipated and prevented by applying exlraoral traction at night to a removable appliance which is worn during the whole of the 24 hours.
The appliance illustrated carries a bite plane (Inset A) and palatal canine retractors (boxed-in) with guide wire (Inset B). Additional retention is provided by Adams clasps on 1/1 (Inset C) (page 38) and modified Adams clasps on 65/56 (page 40). The extraoral traction arch is inserted into molar tubes and stands clear of the incisors. It may be reinforced, as shown, by stainless steel tubing before attaching the traction wires.
Construction Canine retractors: 0.6mm stainless steel wire Canine guide wires: 0.5mm stainless steel wire Anterior clasp: 0.6mm stainless steel wire Adams clasps: 0.7mm stainless steel wire Molar tubes: 1.25mm internal diameter Labial arch: 1.25mm stainless steel wire Extraoral arch: 1.25mm stainless steel wire Anterior tubing: 1.25mm internal diameter soft
Labial arch, tubing and extraoral arch sttapped and soldered
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E X T R A O R A L A N C H O R A G E , 2
Class II division 1 treatment may need to be supported by extraoral t ract ion. The common sequence of canine retract ion w i th buccal canine retractors (page 84) and incisor retraction wi th a Roberts retractor (page 100) is i l lustrated opposite. Retention is by Adams clasps on 6/6 wi th auxi l iary arrowheads on 5/5 but the alternative clasp il lustrated on page 41 may be used.
Note: Normal ly the extraoral arms should lie in the same plane as the arch but have been bent clear in the i l lustrations to show details of construct ion.
Construction
Retention: Springs:
Labial arch: Molar tubes: Extraoral whisker:
Adams clasps on 65/56 Canine retractor 0 .6mm sleeved;
Roberts retractor 0 .5mm sleeved
1.25mm stainless steel wire 1.25mm internal diameter 1.5mm stainless steel wire
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E X T R A O R A L A N C H O R A G E , 3
The second stage of Class II division I treatment fo l lows in the same way as the canine retract ion. A Roberts retractor is constructed as described on page 102 and a double Adams clasp made for 65/56. Some ingenuity is necessary to pass the tags of the retractor and the clasps between canines and first premolars. Tubes are attached to the clasps (page 140) and a labial arch wi th U-loop stops inserted into them; the bridges of the clasps may have to be contoured so that the buccal tube wil l accept the extraoral arch.
During treatment the baseplate is cut away behind the incisors and it may be necessary to close the extra-oral U-loops to br ing the arch back and avoid d iscomfor t to the lips. However, at no t ime should this arch rest on the teeth: the too th movement is produced by the Roberts retractor.
Construction Retention: Double Adams clasps on 65/56 Retractor: 0 .5mm stainless steel wire Sleeve: 0.5mm internal diameter soft
tub ing Molar tubes: 1.25mm internal diameter
stainless steel Extraoral arch: 1.25mm stainless steel wire Extraoral whisker: 1.5mm stainless steel wire
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BUCCAL MOVEMENT Of PREMOLARS
The disadvantage of simple fingersprings to move palatally placed upper premolars into the arch is that they are extremely difficult for the patient to insert, the spring usually coming to lie on the occlusal surface of the tooth.
The Adams T-spring illustrated falls into the correct place as the appliance is inserted.
So that the T-piece will not slide into the gingiva as the tooth moves, its initial contact must be near the occlusal surface: it will slide gingivally as the tooth moves. It is then boxed-in shallowly.
Construction T-spring: 0.5mm stainless steel Wire
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INCISOR E L O N G A T I O N , 1
Without access to bands and welders It has been impossible to exert vertical traction on teeth. The advent of acid-etch retained composite resins has reversed this situation.
T w o methods are shown: on the left , a hook made of stainless steel tape has been laboratory-welded to a piece of f ine stainless steel gauze (BS No. 155) This is cemen-ted to the tooth by the acid-etch technique. This gives a very positive ho ld to the spring.
On the opposite page is i l lustrated a simpler technique in which a fa i r ly th ick b lob of composi te. resin is attached to the too th and then grooved by means of a number 1 or 2 fissure bur. Diagram D shows the spring resting on the slot.
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INCISOR ELONGATION. 2
A simple removable appliance can be adapted to elongate incisors (or canines) which may have been delayed, for example, by a supernumerary tooth.
A simple sleeved fingerspring is employed but it is important to note the position of the coil so that the arm will follow the tooth without slipping off. It is activated by flattening a section of the coil.
Construction Clasps: Adams on 6/6 Spring 0.5mm stainless steel Sleeve: 0.5mm internal diameter soft stainless steel
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T H E A N D R E S E N APPLIANCE. 1
This appliance consists essentially of an upper and lower baseplate uni ted together in such a manner as to hold the mandible forward. lt is used mainly in the treatment of Class II division I malocclusions, and too th movement is produced by the pul l of the muscles of mastication which t r y to return the mandible to its rest posi t ion. I f required the backward pull of the mandible can he reinforced by extraoral t ract ion. This is shown in the large i l lustrations to show the placing of the extraoral 'whiskers', but it is required in only a relatively small propor t ion of cases.
Diagram A
The Cof f in spring.
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Diagram B
The appliance is shown here in plan view with a Cof f in spring in posit ion. The appliance overlies the palatal half of the occlusal surfaces of the cheek teeth.
Diagram C
The points of insertion of the labial arch and extraoral wires.
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THE ANDRESEN APPLIANCE, 2
Diagram D The baseplate is cut away behind the upper incisors but should not be removed from the tips of the lower
incisors.
Diagram E
Removal of the acrylic material f rom the occlusal
surfaces wil l allow adjustment of the occlusal level of
the cheek teeth.
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Diagram F Full extension of the acrylic resin between the teeth should be allowed, when cutting away from the occlusal surfaces. In the mouth these extensions will bear on the upper teeth as shown, causing them to move dislally.
Diagram G
When the acrylic is cut away from the occlusal surfaces of the lower teeth the interdental extensions act as shown, causing them to move mesially.
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T H E ANDRESEN APPLIANCE, 3
Construct'on
A bi te is taken in the protrusive posit ion, w i thou t straining and open 2 - 4 mm. This is mounted on an art iculator and the appliance waxed as shown in diagrams B and C. After t r imming the models very closely they are flasked together as shown in diagram H. The reverse half forms a plug in the palate and a raised bite is impossible. The appliance is completed in the usual way.
Materials
Baseplate:
Cof f in spring: Labial arch:
Extraoral wires:
Deeply extended and thickened in lower molar region, rising to clear the gingiva and contact only the teeth in the lower incisor region. Upper as shown in diagram A 1.25mm 0.8mm sleeved or 1.0mm anodically th inned to 0.8mm 1.25mm
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THE ORAL SCREEN
The oral screen is an active orthodontic appliance worn during sleep and transferring the pressure of the circumoral soft tissues to the upper incisor teeth. It is necessary, therefore, to raise the screen away from the dentoalveolar structures except those teeth to he moved. This is known as waxing out and is carried out as follows. 1. Wax is added to the areas shown, filling in anteriorly
to the lower incisors and into the other hollows indicated.
2. A sheet of baseplate wax is applied to the whole area except the most prominent upper incisors.
3. A second sheet of wax is applied over the whole area and then scraped away over the tips of the prominent incisors, so that these prolrude very slightly through the wax.
4. After applying a separating medium a double thick-ness of wax is adapted over the entire area and trimmed away from all mucous folds. It should extend distally no further back than the middle of the upper first molars. This is then removed and converted to clear acrylic resin.
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