INTRUSION ARCHESINTRUSION ARCHES

PRESENTED BYSUSNA PAUL

CONTENTS

1. INTRODUCTION2. MAJOR PRINCIPLES OF INTRUSION 3. BIOMECHANICS INVOLVED4. VARIOUS INTRUSION ARCHES

1. RICKETT’S UTILITY ARCH2. TIPBACK SPRINGS ( INTRUSION SPRINGS)3. BURSTONE’S CONTINUOUS INTRUSION ARCH.4. BURSTONE’S THREE PIECE INTRUSION ARCH5. K-SIR (KALRA SIMULTANEOUS INTRUSION AND RETRACTION)

5. CONCLUSION6. REFERENCES

6. CONNECTICUT INTRUSION ARCH7. PG RETRACTION SPRING8. TRANSLATION ARCH9. LINGUAL ARCH FOR INTRUDING AND UPRIGHTING LOWER INCISORS

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INTRUSIONIntrusion refers to: the apical movement of the geometric center of the root (centroid) in

respect to the occlusal plane or plane based on the long axis of the tooth. - Burstone

Marcotte defines intrusion as the” tooth movement that occurs in an axial (apical) direction and whose center of rotation lies at infinity. It is an axial type of translation”

Nicolai as “ Translational form of tooth movement directed apically and parallel to the long axis”

Correction of the deep overbite can be accomplished in a number of ways depending on the initial diagnosis and treatment objectives. Deep bite can be corrected by various tooth movements which include:

a) Extrusion of posterior teethb) Uprighting of posterior teethc) Increasing the inclination of incisorsd) Intrusion of anterior teethe) Combination of one or two of the above tooth movements

Extrusion of the posterior teeth will result in increased lower facial height, steepening of the occlusal plane, downward and backward rotation of the mandible, resulting in worsening of the class II skeletal relationship

Intrusion of anterior teeth to correct deep overbite may be indicated in patients with unaesthetic excessive maxillary incisor showing at rest position of the lip (5-8mm)

MAJOR PRINCIPLES OF INTRUSION

Six major principle of intrusion should be followed; if genuine intrusion and greater control of force system is needed:

1.CONTROLLING FORCE MAGNITUDE AND CONSTANCY.2.ANTERIOR SINGLE POINT CONTACTS.3.POINT OF FORCE APPLICATION.4.SELECTIVE INTRUSION.5.CONTROL OF REACTIVE UNITS.6.AVOIDING EXTRUSIVE MECHANICS.

Burstone CJ. Deep overbite correction by intrusion. AmJ Orthod 1977;72:1-22

CONTROLLING FORCE MAGNITUDE AND CONSTANCY

TRUE INTRUSION LOW MAGNITUDE OF FORCE

If the magnitude of force are too great; rate of intrusion will not increase

rate of resorption will increase reciprocal effect on posterior

anchorage

In order to maintain a constant force during intrusion, wire with a low load deflection rate should be used.

If a high load deflection spring is used for intrusion as teeth moves, a rapid drop in force magnitude occurs, so that optimal force may be only momentarily reached..

ANTERIOR SINGLE POINT CONTACTS

By having a single point of force application on the incisors, the clinician knows more positively the full force system acting at the incisor segment and buccal tube, thereby producing a statically determinant system.

By placing the intrusive arch into the brackets produces a statically indeterminant system, which prevents the orthodontist from knowing exactly what type of force he is delivering

INTRUSION ARCH INTO THE BRACKET TORQUE TO THE ANTERIOR SEGMENT INTRODUCED

LABIAL ROOT TORQUE

INCREASES THE MAGNITUDE OF INTRUSIVE FORCE

INCREASES THE SIDE EFFECTS ON ANCHORAGE UNIT

LINGUAL ROOT TORQUE

DECREASES THE INTRUSIVE FORCE

POINT OF FORCE APPLICATION

Passing through center of resistance

Intrusion of incisor segment

Passing labial to the center of resistance

Flares the crown more labially

Prevented by 2 ways:if tooth is forwardly placed, retrude and then intrude.apply the vertical force lingual to the center of resistance

SELECTIVE INTRUSION

Leveling with a continuous arch or with a sectional wire can produce undesirable side effects.

Many times the overbite is corrected not because of intrusion but by extrusion.

CONTROL OF THE REACTIVE UNIT

Two basic side effects should be anticipated from intrusive mechanics:

From the lateral view a moment is created which tends to alter the plane of occlusion of the buccal segment and therefore in the upper arch, the plane is steepened.

1.the force are kept as low as possible2.teeth in the buccal segment are rigidly connected and the right and the left buccal stabilizing segment are connected3.So add more teeth for anchorage4.Do as much retraction as possible to decrease the length of moment arm

Second major side effect produced by an intrusive arch can be seen from the frontal view with an intrusive force acting on the incisors, there is an equal and opposite extrusive force acting at the molars and since the extrusive force is acting buccaly at the tube, a moment is created that tends to tip the crowns lingually and roots buccally.

One of the functions of the lingual arch is to resist side effectS.

AVOIDING EXTRUSIVE MECHANICS

Extrusive mechanics should be avoided if one is to accomplish genuine intrusion.

One of the classic situation for inadvertently erupting incisors which have been intruded or are going to be intruded is placement of continuous arch wire.

It is wise to intrude the maxillary incisors to a significant degree prior to any retraction:

1. Bite opening is achieved by moving maxillary incisors into the alveolus2. The potential for increasing a gummy smile is minimized 3. The unfavorable tipping of the occlusal cant will not be as common4. It will minimize the chances of moving the apices into juxtaposition against the dense

cortical bone5. There will be a reduction in the total amount of class II elastics that will be required6. The torquing requirements will be reduced, and when needed will be accomplished

within a more adequate anatomical area, and not restricted by the lingual cortical plate.

INTRUSION FORCEIntrusion Per-Side Total in Midline

Upper central inciosr 15-20(gm) 30-40(gm)Upper central and

lateral incisor 30-40(gm) 60-80(gm)

Upper central lateral and canine 60(gm) 120(gm)

Lower central incisor 12.5(gm) 25(gm)Lower central and

lateral incisor 25(gm) 50(gm)

Lower central lateral and canine 50(gm) 100(gm)

Dr. Charles J.Burstone., Modern Edgewise Mechanics and The Segmental Arch Technique

Proffit suggested 10-20 grams of force needed for intrusion.

Bench, Gugino and Hilgers in 1978, advocated intrusive force of 15 to 20 grams per lower incisor and 60 to 80 grams for all four lower incisors.

Lui and Herschelb in 1981 suggested use of 80 to 100 grams of force for four incisors intrusion

Though there has been many opinions regarding an ideal force for intrusion, all recognize the need for light continuous force

INTRUSION ARCHES

Intrusion can be accomplished in two ways with intrusion arches.1. With continuous archwire that bypasses the premolars and

canine teeth.

2. With segmented base archwire. So that there is no connection along the arch between the anterior and posterior segments and an auxiliary depressing arch.

1. RICKET’S UTILITY ARCH2. TIPBACK SPRINGS ( INTRUSION SPRINGS)3. BURSTONE’S CONTINUOUS INTRUSION ARCH.4. BURSTONE’S THREE PIECE INTRUSION ARCH5. K-SIR (KALRA SIMULTANEOUS INTRUSION AND RETRACTION)6. CONNECTICUT INTRUSION ARCH7. PG RETRACTION SPRING8. TRANSLATION ARCH9. LINGUAL ARCH FOR INTRUDING AND UPRIGHTING LOWER INCISORS

RICKETT’S UTILITY ARCH

McNamara JA Jr. Utility arches. J clin orthod 1986;20:p.452-456.

UTILITY ARCH

Utility arch designed by Robert M. Ricketts in the early 1950’s and has been popularized as an integral part of bioprogressive therapy.

continuous wire that extends across both buccal segments, but engages only the 1st permanent molars and four incisors .

MATERIAL FOR UTILITY ARCH

- Dimension in an 0.022" slot Non heat treated blue elgiloy 0.016" x 0.016" or 0.016" x 0.022”(mandible) 0.016" x 0.022” (maxilla)

- Dimension in an 0.022" slot Blue elgiloy 0.019" x 0.019”

Molar segments Posterior vertical segment Vestibular segment Anterior vertical segment Incisal segment.

MOLAR SEGMENT

It extends into a tube on the 1st molar.

This segment may be cut flush with the end of the tube or may be bend gingivally if the utility arch is to be tied back.

When utility arches are used in combination with full arch appliances, it is necessary to have auxiliary tubes located in the gingival portion of the 1st molar bands..

POSTERIOR VERTICAL SEGMENT  It is formed by making a 90° bend with 142 arch forming pliers.

Posterior step typically is 3-4mm in length.

VESTIBULAR OR HORIZONTAL SEGMENT

Vestibular segment is formed by placing a right angle bend at the inferior portion of posterior vertical segment. The wire then passes antero-inferiorly along gingival margin.

ANTERIOR VERTICAL SEGMENTS

Anterior vertical segments should be about 5-8mm in length.

INCISAL SEGMENT

Final 90° bend creates the incisal segment that should lie passively in the brackets of anterior teeth

UTILITY ARCHES

PASSIVE UTILITY ARCH

INTRUSION UTILTY ARCH

RETRACTION UTILITY ARCH

PROTRUSION UTILITY ARCH

INTRUSION UTILITY ARCH

Intrusion utility arch is similar in design to passive utility arch , arch is activated to intrude the anterior teeth.

Utility arch should produces 100 grams of force on the mandibular incisors, force level considered ideal for mandibular incisor intrusion.

Activation

occlusally directed gable bend in the posterior portion of the vestibular segment of the arch wire

Bench has advocated an alternative method of activation of utility arch to produce intrusion. This type of activation involves placing a tip – back bend in the molar segment .

However placing a tip back bend can occasionally lead to unintentional posterior tipping of 1st molars.

Thus activating the Utility arch by placing a gable bend in the posterior aspect of the vestibular segment seems to avoid unwanted tipping.

Retraction Utility Arch Retraction and intrusion can be

produced by activating the retraction arch in a similar fashion previously described of the intrusion utility arch.

The incorporation of the loop into the design allows for a longer range of activation.

Protraction Utility Arch

When passive, anterior segment lies approx. 2mm anterior to the expected position in the incisor bracket.

Protrusion force produced by tying anterior segment into the anterior brackets.

Activation:

BIO – MECHANICS OF INTRUSION ARCHES

One couple systems Two couple systems

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One Couple Appliances—Statically Determinate Systems

The end that is tied as a point contact only force

The end which is engaged in the bracket slot a force and a couple

1-couple system couple is generated only at the site of full engagement. It is statically determinate magnitudes of the forces and moments produced can be determined clinically after the appliance is inserted into the bracket.

Two Couple Appliances - Statically Indeterminate Systems:

Both the ends of the wire is engaged into brackets

magnitudes of the forces and moments produced can not be determined clinically after the appliance is inserted into the bracket.

Because of the inability to measure force systems produced by 2-couple appliances clinically, they are referred to as being statically indeterminate.

INTRUSION ARCHES

Two factors in the action of the intrusion arch are :

1. the relationship of the point of force application relative to the center of resistance of the incisor segment

2. whether the incisors are free to tip facially as they intrude or whether the arch is cinched back.

TWO COUPLE SYSTEM (utility arches)

At the incisors: a moment to tip the crown facially (Mf) is created by the

distance of the brackets forward from the center of resistance, and an additional moment in the same direction is created by the couple within the bracket (Mc) as the inclination of the wire is changed as it is brought to the brackets.

Placing a torque bend in the utility arch creates a moment to bring the crown lingually, controlling the tendency for the tooth to tip facially as they intrude increases the magnitude of the intrusive force on the incisor segment and the extrusive force and the couple on the molar

Cinching back the utility arch creates a force to bring the incisors lingually, and a moment of this force opposes the moment of the intrusive force. At the molar, a force to bring the molar mesially is created along with a moment to tip the molar mesially.

BURSTONE’S INTRUSION SPRING

TIP BACK SPRINGS (Intrusion Springs) By Burstone

The upper and lower arches have to be leveled and aligned and a rigid stainless steel wire, preferably 0.017”x 0.025” dimension is engaged.

Anchor is reinforced by TPA and lingual holding arch.

The intrusion springs are made from 0.017" x 0.025" TMA wire without a helix or 0.017" x 0.025" stainless steel wire with a helix so that forces can be made optimal for intrusion.

Wire is bend gingivally mesial to the molar tube and then a helix is formed.

The mesial end of the spring is bend into a hook and is engaged distal to lateral incisor (activation)

BURSTONE INTRUSION ARCH

Burstone CJ. Deep overbite correction by intrusion. Am J Orthod 1977;72:1-22

Continuous intrusion arch

The intrusion arch, as described by Burstone in 1977, is significantly different in its force deliver because it is not engaged in the incisor brackets.

The basic mechanism for intrusion consists of three parts:

1. The posterior anchorage unit.2. The anterior segment.3. The intrusion arch itself.

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Posterior anchorage unit Early in treatment the posterior teeth are aligned and

joined together with a buccal stabilizing segment of heavy wire.

Right and left posterior segments are joined together across the arch by means of a transpalatal arch in the maxilla and a lingual arch in the mandible.

Whenever possible, at least the first molars and second premolars should be used and the addition of other teeth would further enhance the anchorage potential.

Intrusive arch spring

The intrusive arch consists of an 0.016 x 0.022 inch or 0.017 x 0.025 inch TMA..

A step down is placed to the canine bracket to avoid this bracket upon activation of the intrusion arch.

Anterior segment

Initial alignment of anterior teeth is not necessary when performing intrusion..

Intrusive spring is tied to the wings of the brackets of incisor not into the slot.

Formed to fit the teeth to be intruded.

Continuous intrusion arch

Three-piece Intrusion Arch

Segmented approach to simultaneous intrusion and space closure: biomechanics of three piece base arch appliance” Am J Orthod dentofac Orthop 1995:107: 136-43

In patients with proclined incisors, a continuous intrusion arch tied at the midline cannot be used because the force system generated tends to worsen the axial inclination of the anterior teeth

So the selection of the point of application of the intrusive force with respect to the center of resistance of the anterior segment is important to precisely define the type of tooth movement that will occur

In many extraction cases the axial inclination of flared anterior teeth is corrected first by retraction of the incisors during initial space closure.

When no further retraction is possible because of the presence of a deep bite and the reduction of the overjet, intrusion is initiated to open the bite and allow subsequent space closure.

To achieve deep overbite correction and close extraction spaces simultaneously,

An appliance design needs to incorporate a variable point of application of the intrusive force, as well as a mechanism to direct the intrusive force along the long axis of the anterior teeth.

This is a segmented approach to simultaneously intrude and retract the flared by using frictionless mechanics

Introduced by Bhavna Shroff, Steven J. Lindauer, Charles J. Burstone, Jeffrey B. Leiss in 1995.

principles of the segmented arch technique

different wire cross-sections in a given arch rather than continuous wires

develop a precise and predictable force system between an anterior segment (incisors) and a posterior segment (premolar and molars) enabling pure intrusion of the anterior teeth and control of their axial inclinations

Three piece intrusion arch

Consists of:

Posterior anchorage segment Anterior segment with posterior extension Intrusive cantilevers Sometimes chain elastics

ANTERIOR SEGMENT WITH POSTERIOR EXTENSION

It is bent gingivally distal to the laterals and then bent horizontally creating a step of approximately 3 mm

Distal part extends to distal end of canine bracket where it forms a hook

0.021 X 0.025 SS

POSTERIOR SEGMENT

Aligned posteriors 0.017 X 0.025 SS TPA can be given for more consolidation

CANTILEVER OR INTRUSION SPRING

Made from 0.017" X 0.025" TMA wire.

The wire is first bent gingivally mesial to the molar tube and then a helix is formed. On the mesial end the cantilever, hook is bent through which the intrusion force can be applied to the anterior segment.

The cantilever is then activated by the making a bend mesial to the helix at the molar tube, and then cinched back.

A small distal force can be added by attaching chain elastic from the hook of anterior segment to the molar tube to facilitate simultaneous intrusion and retraction of the anteriors on each side

Biomechanics

 Intrusive force through CR will intrude incisor along line of action of this force. 

An intrusive force perpendicular to the distal extension and through CR will have the same effect as in A.

To obtain a line of action of the intrusive force through the center of resistance and parallel to the long axis of the incisors, the point of force application must be more anterior and a small distal force should be given

If the intrusive force is placed farther distally and an appropriate small distal force is applied, intrusion and simultaneous retraction of the anterior teeth occurs because of the tip back (clockwise) moment created around the center of resistance of the anterior segment consisting of four incisors.

K- SIR APPLIANCE

Varun Kalra, “simultaneous intrusion and retraction of the anterior teeth” JCO 1998 p535-540.

The K-SIR (Kalra Simultaneous Intrusion and Retraction) archwire is a modification of the segmented loop mechanics.

K-SIR archwire: .019“x.025" TMA archwire with closed U-loops 7mm long and 2mm wide.

K- SIR APPLIANCE

90° bends placed in archwire at level of U-loops.

Centered 90° V-bend creates two equal and opposite moments (red) that counter the moments (green) produced by activation forces.

Archwire with off-center 60° V-bend placed about 2mm distal to U-loop.

Off-center V-bend creates greater moment on molar, increasing molar anchorage and intrusion of anterior teeth.

20° antirotation bends placed in archwire just distal to U-loops.

Trial activation performed on each loop..

Archwire after trial activation.

Neutral position of loop determined with mesial and distal legs extended horizontally. In neutral position, loop is 3.5mm rather than 2mm wide.

K-SIR archwire in place prior to cinching back. First molar and second premolar are connected by segment of .019"x .025" TMA wire.

Archwire cinched back to activate loop about 3mm, so that mesial and distal legs are barely separated.

advantages

 simplicity of design, with a minimal amount of wire in the loop configuration

material properties of TMA combine to produce relatively low forces, a low load-deflection rate

the presence of the off-center V-bend, which acts like an anchor bend, molar anchorage control is excellent

THE CONNECTICUT INTRUSION ARCH

JCO, VOLUME 32 : NUMBER 12 : PAGES (708-715) 1998RAVINDRA NANDA, ROBERT MARZBAN, ANDREW KUHLBERG, DMD, MDS

THE CONNECTICUT INTRUSION ARCH

The CTA is fabricated from a nickel titanium alloy. It incorporates the characteristics of utility arch as well as those of the conventional intrusion arch.

Two wire size are available 0.016” x 0.022” and 0.17” x 0.25”.

In most cases, the wire is not directly ligated into the bracket slots, the anterior wire dimension is adequate to allow for it.

The bypass, located distal to the lateral incisors, is available in two different lengths to accommodate for extraction, nonextraction or mixed dentition cases.

Dimensions of preformed CONNECTICUT INTRUSION ARCHES

Maxillary CTA Mandibular CTA

Anterior dimension 34mm 28mm

Posterior dimension: long (non-extraction)

22mm 22mm

Posterior dimension: short (extraction and mixed dentition)

15mm 15mm

MECHANICS

The CTA’s basic mechanism for force delivery is a V bend lies just anterior to the molar brackets.

When the arch is activated, a simple force system results, consisting of a vertical force in the anterior region and a moment in the posterior region.

Incisor intrusion requires 50g of force directed apically along the center of resistance.

The moment created at the molar will also vary, according to the amount of force at the incisor multiplied by the distance at the molars. These minor changes can be made to ensure proper force delivery.

A pure intrusion arch would have a point contact at the incisors.

Insertion of the wire into the incisor brackets, however, will tend to flare the incisors, which may or may not be desirable.

The CTA’s point of force application is anterior to the center of resistance, which will flare the incisors.

A tight cinch-back—a sharp bend distal to the molar tube, preventing forward slippage of the wire—will prevent incisor flaring during intrusion and produce some retraction of the incisors.

PG RETRACTION SPRING

POUL GJESSING, DDS A Universal Retraction Spring J Clin Orthod.1994;28:04:p.222-242

PG RETRACTION SPRING(P0UL GJESSING, 1985)

Prefabricated ,standardized springs

0.017 X 0.025“ or 0.016 X 0.022” SS wire is used for PG springs.

CANINE RETRACTION INCISOR INTRUSION & RETRACTION

DESIGN

Configuration of double helix to produce 100g of horizontal driving force. PG Universal Retraction Spring with curved posterior extension.

DESIGN & ACTIVATION FOR INCISOR INTRUSION & RETRACTION

The posterior extension of the spring is always inserted in the gingival auxiliary molar tube, but the anterior extension can be attached to the lateral bracket in several ways.

The most practical is to use .018"´.025" lateral incisor brackets with vertical Broussard-type slots. The anterior extension is placed in the vertical slot of the lateral incisor bracket, pulled as far occlusally as possible, and locked with a mesial bend. These accommodate the .017"´.025" PG springs.

The spring is activated by pulling distal to the molar tube until the two loops separate.

The wire is secured with a gingival bend in the posterior extension.

Reactivation to the initial spring configuration should be done every four to six weeks

THE TRANSLATION ARCH

Martina R. Paduano S. The Translation Arch. J Clin Orthod. 1997;3;11:p.750-753

The Translation Arch

This is a kind of utility arch that can be used in bioprogressive therapy and similar techniques to simultaneously retract, torque, and intrude or control the extrusion of the maxillary incisors.

The Translation Arch is made of .016" × .022" TMA.

The posterior teeth are tied together with .017" × .025" stainless steel sectional wires and transpalatal arch.

A distal activation of 2mm on each end of the arch will produce the 100g of horizontal force needed for incisor retraction

A. Translation Arch has anterior segment inserted into incisor brackets and two buccal segments inserted into gingival first molar tubes.

A. Vertical loops between segments extend as far as possible. Arc—should be bent into each buccal segment to produce an intrusive force of 40g on the incisors

Design

LINGUAL ARCH FOR INTRUDING AND UPRIGHTING LOWER INCISORS

W Senior. A lingual arch for intruding and uprighting lower incisors. J Clin Orthod. 2003 Jun;37(6):302-6

This technique was introduced by WINSTON SENIOR. An .036" lower lingual arch is soldered to first molar bands.

Distal extensions form occlusal rests on the second molars to prevent distal tipping of the first molars as the incisors are intruded.

Four elastic chains are attached to the anterior bridge of the lingual arch with a mosquito forceps .

After cementation of the arch, the elastics are stretched to four lingual buttons on the lower incisors . These should be bonded as far as possible from the gingival margin to facilitate intrusion

Palatal elastics from TPA

- modification given by Prof. Dr. Jayade

CONCLUSION

These appliances are integral part of interceptive and comprehensive orthodontic treatment. It is efficient in intruding , protruding or retruding anterior teeth.

REFERENCES Charles J. Burstone “ Biomechanics of deep overbite correction” semin orthod 2001: 7: 26-33Bhavana Shroff, Steven J Lindauer , Charles J Burstone “ Segmented approach to simultaneous intrusion and space closure: biomechanics of three piece base arch appliance” Am J Orthod dentofac Orthop 1995:107: 136-43.Richard J. Smith, Charles J. Burstone, “ Mechanics of tooth movement” vol 85, 294-307McNamara JA Jr. Utility arches. J clin orthod 1986;20:p.452-456.Martina R. Paduano S. The Translation Arch. J Clin Orthod. 1997;3;11:p.750-753

Charles J. Burstone, Modern edgewise mechanics and the segmented arch technique” ed. Ormco 1995.

Steven J. Lindauer, “Basics of mechanics” semin orthod, 7, 2001: 1-15

Burstone CJ. Deep overbite correction by intrusion. AmJ Orthod 1977;72:1-22

Varun Kalra, “simultaneous intrusion and retraction of the anterior teeth” JCO 1998 p535-540.

Nanda R, Marzban R, Kulberg, “The Connecticut Intrusion Arch” JCO1998 p 708 – 715

POUL GJESSING, DDS a universal retraction spring j clin orthod.1994;28:04:p.222-242

W Senior. A lingual arch for intruding and uprighting lower incisors. J Clin Orthod. 2003 Jun;37(6):302-6

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