Molar distalization – current trends

Dr Tony Pious

Current orthodontic philosophies have been oriented toward conservative treatment modalities to avoid extractions and, at the same time, to try to eliminate the need for patient cooperation; consequently, there are many devices for gaining space, particularly for the distalization of the maxillary molars.

The appliances used for molar distalization can be divided into

Removable appliances and Fixed appliances.

Removable appliances are: Extra oral traction Removable appliances with finger springs Sliding jigs with intermaxillary elastics.

The fixed appliances areA. Intramaxillary appliance1. Wislons 3D appliance2. Repelling Magnets3.The pendulum appliance4. Niti based appliances : archwires – single loop,

double loop; Compressed coil springs5. Jones jig6. Distal Jet7. Fixed piston appliances8. IBMD 9. K-loop 10. Distalix11.Franzulum appliance 12. Lokar appliance 13. First class appliance 14. Carriere’s Distalizer

B. Intermaxillary appliance:1. Herbst appliance2. Jasper Jumper3. Eureka Spring4. Klapper superspring

C. SAS supported distalization:

DISTALIZATION DIAGNOSIS The first step is to confirm the diagnosis of a forward

maxillary molar position. 1. Check the centric relation position (and vertical status).

Before considering the molar relationship in terms of dental or skeletal malocclusion, it is desirable to check the TMJ status. All records must be correlated, ie, cephalo metrics, functional axiographics, and radiologic exams (MRI, CT scan).

Korn has cautioned against using extraoral force in patients with undiagnosed meniscus disorders who are borderline clickers with an "end-on click. a. Korn has shown that the distalization may push back the maxillary molar ---- b. causing more posterior tooth contacts and then moving the condyle backward into a more posterior position, now with a "true click”. c. The mandible then assumes its normal position, but the meniscus is now too far forward.

2. Check the sagittal relationship. (1) The pterygoid vertical plane (PTV)/maxillary molar relationship and (2) the convexity prognosis.

According to Ricketts, the normal maxillary molar (M1) position is given by the distal face of the molar to the PTV. The clinical norm is age + 3 mm, and clinical deviation is 3 mm.

In good skeletal and dental Class I relationships, the facial axis normally crosses the mesial cusp of M1.

However, the maxillary molar analysis must not be static only, but also dynamic. If the distance M1/PTV is shorter than the normal measurement, the possibility for distalization is low and possible extractions will depend on growth potential and the presence of 3rd molar.

Therefore, posterior dental arch analysis must include mesiodistal measurement of all molars to determine the posterior space available at maturity

To determine a positive convexity, differentiation must be made between a forward maxilla and a backward mandible.

Patient age must be considered, to determine what the positive convexity will be with time and growth.

For example, a +4 mm convexity at 8 years of age could be completely different at maturity, according to the facial pattern.

In some borderline clinical situations, the long-range growth forecast could be useful. This might permit the clinician to know if extraoral force and/or distalization are indicated.

1.Brachyfacial2.Mesofacial3.Dolichofacial

DISTALIZATION INDICATION In the growing patient, only the growth

prognosis scientifically reveals the indication for distalization. When a young patient has a Class II maxillary molar relationship with a forward maxilla, the molar relationship could worsen, remain the same, or improve, depending on mandibular growth.

The best way to determine the indication for distalization is to conduct a Ricketts long-range growth forecast, from the original profile tracing. The new convexity and molar relationship can then be observed.

Define the treatment objectives to construct a long-term VTO, according to the following procedure: 1. Draw the mandibular arch with the estimated position of the mandibular incisor and the mandibular molar position according to the dental arch analysis. 2. Place the maxillary molar in a corrected Class I on the VTO, because this is the eventual therapeutic goal. 3. Do the S3 Ricketts superimposition; superimpose the VTO tracing on the original tracing, on the palatal plane with registered anterior nasal spine

4. Determine the necessary therapeutic molar movement needed to obtain the correction :

(1) If the maxillary molar moves downward, but does not go forward, distalization would not be recommended

(2) If the maxillary molar naturally moves x millimeters forward, distalization would not be useful

(3) If the maxillary molar needs a back ward movement of x mm to finish in a Class I relationship at the end of growth, then distalization would be strongly indicated.

INDICATIONS & CONTRAINDICATIONSTHE INDICATIONS FOR MOLAR DISTALIZATION

1. In non-extraction treatment of Class II malocclusion cases. 2. In low & average mandibular plane angle cases. 3. In class I skeletal pattern cases. 4. In patients with mild arch length discrepancy. 5. In cases where the upper permanent molars have moved mesially due to early loss of deciduous molars. 6. In patients where the second molars extractions are planned or where it has not yet erupted. 7. In second molar extraction cases where the third molars are well formed and erupting properly.

CONTRAINDICATIONS FOR MOLAR DISTALIZATION In high mandibular plane angle cases. Skeletal and Dental open bite Class II & III skeletal pattern Severe arch length discrepancy patients.

INFLUENCE OF 2ND MOLAR ON DISTALIZATION OF 1ST MOLAR

A controversy exists concerning the influence of second molars on the distal movement of the first molars.

Graber noted that extraoral traction on the first molars, when the second molars have not totally erupted, led to distal tipping only and not to bodily distal movement. Bondemark et al (AO 94 Magnets vs NiTi coils) stated that the presence of second molars did influence tipping and distal movement of the first molars.

Gianelly (AJO 91 NiTi coils) also found that treatment time was increased with the presence of second molars.

Muse et al (AJO 93 Wilsons BDA) found that the presence of maxillary second molars did not correlate with the rate of maxillary first molar movement or with the amount of tipping that occurred.

Studies on Pendulum Appliance The findings of the Byloff’s study (AO 1997)

were similar to those of Muse et al i.e. no statistically significant differences in linear or angular changes were found among three groups of eruption stages of second molars.

According to studies by Bussick and McNamara (AJO 2000March); Ghosh and Nanda (AJO 96); and Joseph and Butchart (Seminars in Orthod 2000) the position of the 2nd molar when distalizing the first molar with a pendulum appliance is of little if any importance

Kinzinger et al (AJO 2004 Jan) used modified pendulum appliance for bilateral maxillary molar distalization in 36 adolescent patients in various stages of the molar dentition.

In PG 1, eruption of the second molars had either not yet taken place or was not complete.

In PG 2, the second molars had already developed as far as the occlusal plane, with the third molars at the budding stage.

In PG 3, germectomy of the wisdom teeth had been carried out and the first and second molars on both sides had completely erupted.

Analysis of cephalograms to identify any changes in the sagittal plane showed that, in the direction of distalization, a tooth bud acts on the mesial neighboring tooth like a fulcrum.

PG1 PG2 PG3

The degree of distal tipping of first molars was less in patients with erupted second molars (PG 2 and PG 3) than in those whose second molars were not yet erupted (PG 1).

Tipping of erupted second molars was much more marked in PG 2 but much less pronounced in PG 3 than the corresponding movement of the second budding-stage molars in PG 1.

In PG3 almost exclusively bodily distalization of both molars is possible, even without bands being applied to the second molars.

However, if the first and second molars are distalized simultaneously with a pendulum appliance, the duration of therapy will be longer, greater forces will have to be applied, and more anchorage will be lost.

 

REMOVABLE APPLIANCES ARE : EXTRA ORAL FORCES REMOVABLE APPLIANCES THE CETLIN APPLIANCE EXTRA ORAL FORCES One of the earliest methods of molar

distalization introduced and proved to be effective was by extra oral forces employing use of the head gear.Components of Head Gear:

Force delivering Unit: Force Generating Unit. The Anchor Unit:

SELECTION OF HEADGEAR: 1. Headgear anchorage location: location of the

anchorage unit determines the type of force that will be applied to the unit. The relation of the force to the Cres of the unit to which it is applied determines the effects that will be produced by the orthopedic force. High pull headgear: this applies a superior (intrusive)

and distal force to the maxilla and the maxillary dentition. Cervical pull: this produces an inferior (extrusive) and

distalising force on the maxilla. Combination headgear: no moment is

produced and a distalising force is applied to the maxilla.

Since the Cres of the molar is located in the mid root region, force vectors above this point will result in a distal root movement. Forces below this point will result in a distal crown movement. Similar considerations apply to the maxilla.

TYPES OF HEADGEARS:CERVICAL HEADGEAR: This was first introduced

by SILAS KLOEHN in 1947. It is the most commonly used facebow in clinical practice. Typically it is used in growing patients with decreased vertical dimension. The purpose of the facebow is to restrict the forward growth of the maxilla. The vector of force is below the occlusal plane producing both extrusive and distalising effects.

Effects of cervical headgear: to erupt the entire upper jaw tends to move the upper jaw

distally Steepen the occlusal plane. Expansion of the upper arch.Effect of different positions of the outer bow:Effect of different positions of the outer bow:

when the outer bow is bent upwardswhen the outer bow is bent upwards::The forces that are produced are The forces that are produced are

A distalising force to the upper teeth, which is good A distalising force to the upper teeth, which is good for correction of class II relation.for correction of class II relation.When the outer bow is bent upwards, bringing it When the outer bow is bent upwards, bringing it down to the occlusal plane tends to produce a down to the occlusal plane tends to produce a negative moment that flattens the occlusal plane. negative moment that flattens the occlusal plane. Hence the steepening effect of the cervical Hence the steepening effect of the cervical headgear is nullified.headgear is nullified.Eruption of the entire upper arch tends to increase Eruption of the entire upper arch tends to increase the mandibular plane angle and tends to worsen the mandibular plane angle and tends to worsen the class II skeletal relationship.the class II skeletal relationship.this type is good for patients with forward growth this type is good for patients with forward growth rotationrotation

when the outer bow is bent downwards:

Forces that are produced are Positive moment on the occlusal plane is seen that tends to steepen the occlusal plane since the pull is below the Cres. Extrusive force and a distalising force.

When the outer bow and inner bow are in the same level, no moment is produced and there is a net distalising and extrusive force.

When the When the outer bow is shorterouter bow is shorter than the inner bow, than the inner bow, the headgear strap hook is placed too far anteriorly. the headgear strap hook is placed too far anteriorly. This results in a greater tendency to steepen the This results in a greater tendency to steepen the occlusal plane when the straps are engaged. The pull occlusal plane when the straps are engaged. The pull of the bow is further forward from the Cres and this of the bow is further forward from the Cres and this tends to steepen the occlusal plane. When the tends to steepen the occlusal plane. When the outer outer bow is longbow is long, there is a tendency to flatten the occlusal , there is a tendency to flatten the occlusal plane.plane.

Advantages Direction of pull is advantageous in

treatment of short face class II maxillary protrusive cases with low MPA and deep bites.

Disadvantages: It normally causes extrusion of the upper

molars. This movement is seldom desirable except in patients with reduced lower anterior facial height. It is contraindicated in patients with steep mandibular planes and in open bite cases.

Long term study on cervical headgear:

Melsen et al in AJO 2003 studied the intramaxillary molar displacement 7 years after treatment with Kloehn headgear and cervical traction. Two groups of 10 patients were studied. In one group, the outer bow was tilted upward by 200 and in another group, it was tilted down by 200. In the group that had the outer bow tilted downwards, molar correction was faster. In both the groups, the maxilla was moved backward and downward. A strong tendency of the molars to return to the key ridge was demonstrated, and there was no evidence that the Class I relationship obtained by extraoral traction was more stable than that obtained by functional or intramaxillary appliances.

OCCIPITAL HEADGEAR: The occipital headgear consists of a facebow which fits over the occiput of the head. The force generated by a high pull (occipital) has both distalising and intrusive forces since the force is exerted above the occlusal plane. Such forces are used in conditions where vertical control of the molars is important. As growth guiding appliance, a high pull headgear can decrease the vertical development of the maxilla, thereby allowing for autorotation of the mandible and maximizing the horizontal expression of mandibular growth.

Occipital pull with short outer bow (force Occipital pull with short outer bow (force anterior to Cres)anterior to Cres)This results in a force system at the unit’s Cres with a This results in a force system at the unit’s Cres with a moment that tends to flatten the occlusal plane and moment that tends to flatten the occlusal plane and creates distalising and intrusive components.creates distalising and intrusive components.

b. occipital pull with force passing through Cres

There is no moment that is created and hence there is no change in the cant of the occlusal plane. Intrusive and distal components of force are produced.

c. occipital pull with long outer bow( force posterior to Cres)

The force system at the unit’s Cres has a moment that tends to steepen the occlusal plane. Intrusive and distalising forces are produced. This system might be required in class II open bite patients.

Advantages: These headgears can be used in patients with steep

mandibular planes and in cases wherein mandibular growth is more vertical than horizontal. They can also be used in certain open bite cases caused due to excessive eruption of buccal teeth.

COMBINATION HEADGEAR.Combination headgears have both occipital and cervical traction springs. This is perhaps the most versatile type because the pull can be readily controlled by selecting the force level of the springs and by controlling the length of the outer bow. For distal translation of the upper posteriors, a distal traction is needed that passes through the Cres, neither above nor below. The combination type headgear will allow a distal force straight through Cres by having equal occipital and cervical components on the outer bow, which is angled upwards to allow the force to pass through the Cres.

Based on occlusal plane requirements:Action desired Outer bow angulation

distal force and flattening - outer bow above Cres

distal force and steepening - outer bow below Cres

distal force and no moment-- outer bow at Cres

REMOVABLE APPLIANCES

Alain (JCO 1972) explained the use of a removable appliance for distalizing the molars. The appliance was originally devised by G.Vienne and later produced by A.Lorette.

The appliances were introduced as the appliances with wires sliding in tubes.THE PRINCIPLE

The appliance consists of a stationary part and a movable part. Both these parts are held together by a long, horseshoe shaped wire which moves the movable part by virtue of the elasticity of the wire. Each end of the wire is inserted into a tube, one in the fixed part of the appliance and the other inthe removable part.

THE APPLIANCE The movable part has an adams clasp and

two parallel tubes embedded for the molars to be moved distally.

The stationary part contains the other clasps for the retention of the plate and one tube which contains the other end of the horse shoe shaped active wire.ACTIVATION

Using the 139 plier, the wire coming out of the tube embedded in the stationary part is bent, which makes the movable part slide distally. DISADVANTAGE

A delicate appliance, since the two wires holding the movable part should do so without binding.

3. THE CETLIN APPLIANCE

JCO 1983 Cetlin and Tenhoe The appliance involves a combination of extra oral force in the form of head gear and an intraoral force in the form of a removable appliance. The Cetlin appliance utilises a removable appliance intraorally to tip the crowns distally and then an extraoral force to upright the roots. So the intra oral removable appliance can be called the crown mover while the extra oral force, the root mover.

ANCHORAGE The anchorage for the removable appliance is by proper adaptation to the palate, an acrylic shield around the four maxillary incisors and a modified adams clasp on the first premolars.

THE EXTRA ORAL FORCE The extra Oral appliance is a headgear which is

inserted into molar tube. The headgear used is generally cervical or a high pull, depending on the usual consideration of the skeletal pattern.THE APPLIANCE

The removable appliance is worn 24 hours a day. The appliance also contains a bite plane to disengage the molars (to aid in rapid molar movement).THE FORCE APPLIED

In the removable appliance, the spring is activated only 1 to 1.5 mm, measured along the occlusal of the molar and it supplies force on the molars of only 30 gms. The springs are placed as far gingivally as possible to minimize crown tipping and to cause molar movement without irritation.

The extra oral head gear on the other hand exerts a 150 gm force per tooth and is used to control root position. The headgear is adviced to be worn for 12-14 hours/day.

INTRAMAXILLRY APPLIANCESWILSONS' RAPID MOLAR DISTALIZATIONAdvocated by William L. Wilson & Robert C.Wilson

(1984 JCO)under modular orthodontics. the pre-treatment antero-posterior positions. The

Wilson treatment achieves molar distalization without extra oral forces.

THE CONCEPT Newton’s' 3rd law of motion states that 'for every

force, there is an equal and opposite force', (i.e.) for every moment, there is a counter moment.

Implicit in Newton’s' law is the concept that control of counter moments increases the efficiency of the moment of force. Modular orthodontic units have been designed to control countermoments, eliminate 'round trips', and reduce headgear use.

DESIGN OF APPLIANCE Wilson advocates maxillary

bimetric distalizing arches (BDA) and a mandibular three dimensional lingual arch. The bimetric arch produces a coil spring action against the molars and producing an anterior counter moment against the incisors, which is controlled by the wearing of class II elastics.

These, in turn, react with a lower molar mesial force vector which is controlled by the 3D lingual arch with a design for anchorage resistance. This is supplemented by molar buccal root torque and cortical resistance to satisfy increased anchorage needs.

The vertical component of elastic force is controlled by using the elastic load reduction principle, in which the elastic force is reduced to physiologically acceptable levels. Mandibular anchorage and elastic load reduction control the reactive countermoments and produce a relatively friction free, rapid distalizing of molars; without headgear and with preservation of mandibular arch integrity.Wilson's Schedule for Maximum Mandibular Anchorage

6 ounce elastics for 5 days. 4 ounce elastics for 5 days and 2 ounce elastics for 11 days.

For minimal mandibular anchorage: 6 ounce for 10 days 3 ounce for 11 days.

REPELLING MAGNETS

Anthony A. Gianelly (AJO 1989)Design:

Nance appliance extends anteriorly to the incisor segment by means of an 0.045-inch wire soldered to the lingual aspect of the premolars. The acrylic component is placed against both the palatal vault and the incisors.

Bilateral distal extensions (0.045-inch wire) with loops at the end are soldered to the labial aspect of the premolar bands so that the loops approximate the molar tubes.

Anchoring the modified Nance appliance to the first premolar encourages the distal drift of the second premolars that normally occurs as first molars are moved posteriorly.

The modified Nance appliance serves two functions: Activation of the magnets Contains the reaction force arising from the action

of the magnets.

Molars were moved distally 2.0 mm while the premolars moved anteriorly 2.1 mm.

When 2nd molars were not present, the fastest molar movement was observed and Class I molar relationships were attained within 2 to 5 months. Disadvantages :

Magnets tend to be expensive and bulky. Magnetic force dissipates rapidly with increasing

intermagnet distance. Requires frequent recall reactivation appointment. Because of these drawbacks, Darendeliler has

concluded that magnets offer no advantage over conventional systems in molar distalization.

PENDULUM APPLIANCE

JAMES J. HILGERS, JCO 1992 The Pendulum Appliance is a

hybrid that uses a large Nance acrylic button in the palate for anchorage, along with .032" TMA springs that deliver a light, continuous force to the upper first molars without affecting the palatal button. Thus, the appliance produces a broad, swinging arc— or pendulum— of force from the midline of the palate to the upper molars.

Fabrication The right and left Pendulum

springs, formed from .032" TMA wire, consist of a recurved molar insertion wire, a small horizontal adjustment loop, a closed helix, and a loop for retention in the acrylic button.

The springs are extended as close to the center of the palatal button as possible to maximize their range of motion, to allow for easier insertion into the lingual sheaths, and to reduce forces to an acceptable range.

The anterior portion of the appliance can be retained in place with occlusally bonded rests or soldered to bands on either the deciduous molars or the first and second bicuspids.

The Nance button should be made as large as possible

to prevent any tissue impingement. It should extend to about 5mm from the teeth, to avoid the highly vascular cuff of tissue near the teeth and to allow adequate hygiene.

If expansion of the upper arch is needed, a midpalatal jackscrew can be incorporated into the center of the Nance button . The screw is activated one-quarter turn every three days, after a week or so for patient adjustment, to produce a slow, stable expansion. This version of the appliance is called a "Pend-X".

Preactivation and Placement The springs should be bent parallel to the midline of the

palate. About one-third of this overactivation is lost in placement, and the remaining pressure is tolerated easily by the patient.

Once the appliance is cemented in place, each Pendulum spring is brought forward with finger pressure, the mesial end of the recurved loop is grasped with a Weingart plier and the spring is seated in the lingual sheath. . Distal pressure holds the spring in the sheath quite effectively, but an elastic "O" ring can be used to secure it.

A. As the molar is driven distally, it moves on an arc toward the midline of the appliance— in other words, toward crossbite. B. This tendency can be counteracted by opening the adjustment loop slightly to increase the expansion and molar rotation. Distal root tip can also be produced by adjusting this horizontal loop on the Pendulum spring. Tipping back the recurved portion of the spring at the loop causes a more direct distal movement of the molars.

Reactivation The spring is reactivated by pushing the centre of helix distally toward the midline with a bird beak plier.

Stabilization Molars must be stabilized in their new distalized positions or they will rapidly drift back mesially. It is also important to move the buccal segments into a Class I relationship to harness the full advantages of the appliance.

The molars can be stabilized in any of four ways: The Nance portion is removed and a full upper fixed appliance is bonded. An upper utility arch holds the molars back with the incisors as anchorage. After removal of the Pendulum Appliance, a smaller, easier-to-clean Nance button ("Insta-Nance”) is placed. The entire upper arch is bonded and a continuous archwire with omega loops mesial to the upper first molar tubes is placed. A headgear is worn.

Drawbacks of PA The pendulum appliance not only drives the molars distally, there is also a slight lingual tipping. Causes the anterior bite to open Not very easy to fabricate.

MODIFICATIONS IN PA

SCUZZO JCO 1999 Nov The Modified Pendulum: M-Pendulum In the original design by Hillgers, adjustable loop was distally oriented to compensate for the tendency toward crossbite during distalization. M-Pendulum was designed by reversing the loop to the mesial to provide bodily movement of both the roots and crowns of the maxillary molars, rather than tipping or rotation. After some distalization has occurred, the loop is reactivated simply by opening it.

Hillgers design

M Pendulum

If the horizontal Pendulum loop is inverted, it will allow bodily movement of both the roots and crowns of the maxillary molars. Once distal molar movement has occurred, the loop can be activated simply by opening it. The activation produces buccal and/or distal uprighting of the molar roots and thus a true bodily movement rather than a simple tipping or rotation.

Before intraoral placement of the appliance,the Pendulum springs are activated to about 40-45° with a Weingart plier, resulting in about 125g of force on each side. This activation is repeated until the desired distalization of the molars is obtained.

The inverted loop should not be adjusted until the spring has deactivated following each phase of distalization. A passive fit of the distal ends of the Pendulum springs in the lingual sheaths, with no distal force applied to the molar crowns, will allow backward tipping of the molar roots. The terminal ends of the M-Pendulum springs are straight, rather than looped as in the original appliance.

The Pendulum springs should be activated primarily by a derotational bending of the distal ends, as with a conventional palatal bar. After distalization is complete, the terminal ends of the springs should be deactivated to allow a passive fit in the lingual molar sheaths.

SCUZZO JCO 2000 April A further modification of the M-

Pendulum appliance was made by using removable TMA arms that can be reactivated outside the mouth.Fabrication and ActivationThe modified appliance is fabricated as follows:

Double over two 7-9mm lengths of .032" TMA wire to form bayonets. Attach each bayonet to an M-Pendulum arm, either by using a laser welder or by wrapping .010" ligature wire around the arm and soldering the unit together with silver wire and a miniflame.

Embed each bayonet in the soft acrylic that will be used to form the Nance button, producing sheaths in which to insert the removable arms

Activate the arms as desired on the working cast

Place the appliance in the mouth, inserting the terminal ends of the arms into the lingual molar band sheaths

The removable arms can be reactivated during treatment without debonding and rebonding the occlusal rests of the Nance button. Distal molar movement can then be more precisely controlled than by opening the horizontal loops in the mouth. The conventional Pendulum or M-Pendulum produces about 5mm of distalization in three to four months. With the removable arms, distal movement can be continued at a rate of about 1.5mm per month for as long as necessary

Advantages Dramatic reduction in chair time. Sound biomechanical principles, producing

more precise and predictable results. Less chance of unwanted side effects. Easy replacement of Pendulum springs

without refabrication of the entire appliance. Ability to replace the active arms with

passive stainless steel auxiliaries after distal movement, thus producing a “quick” Nance appliance for stabilization.

STUDIES EVALUATING PA Ghosh and. Nanda. (AJO 1996)

Friedrich K. Byloff (1997 AO) part 1 & Part 2

Bussick & McNamara, AJO 2000March

Ghosh and. Nanda. (AJO 1996) evaluated the effect of Hilgers PA on 41 patients , mean age 12 years and 5 months.

DENTAL EFFECTSagittal Plane

The correction of the Class II relationship was achieved by a mean maxillary first molar distalization of 3.37 mm. Average distal tipping of 8.36°occurred in 1st molar.

The second molar teeth were distalized to a mean of 2.27 mm,and tipped distally 11.99°.

There was a statistically significant correlation between the amount of distalization and the amount of first molar tipping.Vertical plane

The vertical change in molar position was insignificant. There was a mean intrusion of 0.47 mm in second molar position

Transverse plane The transverse width at the maxillary second premolars

increased by 1.95 mm as they drifted distally into a wider part of the arch.

The arc described by the spring during its distal movement causes a mesiobuccal rotation instead of distobuccal rotation. The width between the mesiobuccal cusps of the right and left first molar teeth increased by 1.40 mm, whereas that between the distobuccal cusps showed no increase. The second molar teeth also showed an expansion of 2.33 mm between the mesiobuccal cusps.

Distalization of the maxillary first molars with this appliance therefore causes both distal as well as buccal tipping of the second molars.

The effect of distalization on the maxillary third molars was extremely variable. The third molars showed a net distal tipping of 2.49°, but an insignificant amount of horizontal or vertical change in position 0.19 mm distalization and 0.22 mm intrusion

Anchorage loss & effect on anterior segments Loss of anchorage was measured at the first

premolar teeth. For every millimeter of distal molar movement, the premolar moved mesially 0.75 mm.

The overjet increased by 1.30 mm and the overbite decreased by 1.39 mm as a result of treatment. The maxillary central incisor was proclined an average of 2.40° relative to the SN line.

The upper lip protruded 0.31 mm and the lower lip protruded 0.95 mm relative to the E plane. Effect of eruption of the maxillary second molar

This study indicates that the eruption of maxillary second molars had minimal effect on first molar distalization.

Skeletal effects with the pendulum appliance : The pendulum appliance caused insignificant

changes in the cant of the palatal and occlusal planes. The mandibular plane, on the other hand, showed a small backward rotation of 1.09° with treatment, which caused a decrease in the overbite by 1.39 mm.

Because there was no vertical change in the maxillary molar position and only an extrusion of 0.5 mm in mandibular first molar position, most of the backward mandibular rotation was caused by distalizing the maxillary molar "into the wedge." The lower anterior face height, as a result, increased by 2.79 mm.

Effect based on MPA The patients in the sample were arbitrarily

divided into three groups, based on their initial Frankfort horizontal to mandibular plane angle (FMA) measurements.

There was a trend for greater increase in FMA in group with FMA greater than 25°.

Patients with high mandibular plane angles showed posterior mandibular rotation and increase in lower face height, 4.13 mm as compared to 1.97 mm in average MPA group.

The increase in the lower face height as a result of molar distalization, was more than double in high angle group (4.13 mm) than in average group (1.97 mm).

Friedrich K. Byloff (1997 AO) part 1 studied, the dental and skeletal effects of the pendulum appliance, applying 200 to 250 g of force to the molars in 13 patients (age range 8 years to 13 years 5 months) by means of cephalometric radiographs.

This study suggest that the pendulum appliance is effective in moving the maxillary first molars distally at a mean monthly rate of 1.02 mm using an initial force of 200 to 250 g in a mean period of 4 months.

Distal molar movement, molar and incisor tipping: The pendulum appliance produces 3.39 mm ±1.25

mm distal molar movement with a mean bimolar intrusion of 1.17 mm ± 1.29 mm. This positive finding can be related to prevention of dentoalveolar vertical growth by the rigid bonded appliance.

Molar distal tipping of 14.5° ± 8.33° occurred. The trajectory of the TMA springs may account for the excessive tipping found in this study.

Maxillary expansion is possible for transverse deficiencies in combination with distal molar movement.

The pendulum appliance does not create dental or skeletal bite opening.

Anchorage loss: Second premolar anchorage loss found in this study was 1.63 mm (±1.37 mm) i.e. 29 %. Distal molar movement represented 71% of the space opened between molars and premolars. Incisor anchorage loss was minimal

Friedrich K. Byloff (1997 AO) part II In this study, the appliance was modified by incorporating an uprighting bend into the distalizing spring during the second phase of treatment to avoid excessive distal tipping of the maxillary molars. Treatment changes were analyzed and compared with the previous study. Due to the initial moderate dental transverse deficiency, 8 of the patients required maxillary expansion of 2 to 4 mm.

Appliance design and activation: The major difference was the incorporation of the molar uprighting bends. An expansion screw was added to the PA in 8 of the subjects who required 2 to 4 mm of transverse development; the appliance was activated every seventh day to achieve a slow rate of expansion.

Active treatment in this study, contrary to the previous one, consisted of two phases. 1. Distal molar crown movement: Molar distalization was done until an overcorrected Class I relationship was obtained. 2. Molar root up righting: The appliance was modified by adding a bend to the spring design to upright the molars by moving the roots distally. In order to make the uprighting bends, the angle between the recurved end of the spring, which is engaged into the palatal molar sheaths, and the long arm of the spring was increased intraorally in the sagittal plane 10° to 15°, using a Weingart plier. The moment created was expected to upright the molars. The springs were left slightly active in the sagittal plane to maintain the position of the molar crowns. The appliance was left in place until the molar crown seemed to be sufficiently uprighted.

Treatment time Mean total experimental time using the PA was 27.25 ±

7.12 weeks (6 months 3 weeks ± 7 weeks). 1st phase of treatment, ( obtaining a super Class I

relationship) the distal movement phase, took 16.45 ± 6.67 weeks.

2nd phase -- to upright the maxillary molars required another 10.9 weeks.

Thus the total treatment time was increased by 64.1%. Distal molar movement & molar tipping:

The percentage of molar movement compared with total space opening decreased from 70.92 % to 64.16.

Rate of movement was between 0.69 mm ± 0.29 mm and 1.20 mm ± 0.74 mm per month, depending on the rate of uprighting.

For 6.07° ± 5.15° of final molar tipping, rate of movement was 0.69 mm ± 0.29 mm per month.

During the uprighting phase, the average monthly distal movement of the apex was 1.01 mm ± 0.57 mm.

Second molar eruption stages In both study the position of the second molars didn’t

influence the amount of distal molar movement or premolar or incisor anchorage loss. Intrusion—extrusion

Increases in the premolar and incisor extrusion and decrease in molar intrusion when compared with the first study might be a result of the vertical reactive component of the uprighting bend.Anchorage loss

The price for more space opening and distal molar crown movement, and especially for more root movement and reduced final tipping of the molars, was increased total treatment time and 0.61 mm more anchorage loss at the premolars and 0.62 mm at the incisor edge level.

The effects of the original pendulum appliance were not significantly changed by the incorporation of the uprighting bends, although slightly more anchorage loss was noted on the maxillary incisal edge.

Bussick & McNamara, AJO 2000March Subjects were: Varying facial patterns (high, neutral, and low mandibular plane angles).

Cephalometric radiographs obtained from 13 practitioners were used to document the treatment of 101 patients (45 boys and 56 girls). The relative effect of erupted maxillary second molars on distalization of the first molar and the effects, if any, of permanent versus deciduous dentition based anchorage on distalization of maxillary molars were also evaluated. Treatment with a pendulum/pendex appliance, similar to the type described by Hilgers,was initiated in all patients

Treatment effects:1. An increase in overjet was shown.2. The average maxillary first molar distalization was 5.7 mm, with a distal tipping of 10.6°. The maxillary first molars intruded 0.7 mm, and the first premolars extruded 1.0 mm.

The maxillary molar distalization contributed to 76% of the total space opening anterior to the maxillary first molar, whereas 24% was due to reciprocal anchorage loss of the maxillary premolars. 3. Anchor teeth

Second premolar moved mesially by the 1.8-mm with a mesial tipping of 1.5°. The maxillary central incisors proclined slightly during treatment.

4. Second deciduous molars vs second premolar anchorage : A. The reduction in overbite was significantly greater in the second premolar group (average –1.5mm) than in the second deciduous molar group (average –0.3mm). B. Patients with erupted second premolars demonstrated significantly greater increases in lower anterior facial height (2.4 ± 1.3 mm) than did second deciduous molars (1.6 ± 1.5 mm). These changes are related to a downward and backward rotation of the mandible.

5. Presence or Absence of Erupted Permanent Maxillary Second Molars

1. No significant differences were noted in the anteroposterior movement of the maxillary first molar and sagittal anchorage loss between the 57 patients who had erupted maxillary second molars and the 44who had not.

2. In patients with erupted maxillary second molars, there was a slightly greater increase in lower anterior face height and in the mandibular plane angle and a slightly greater decrease in overbite in comparison to patients with unerupted second molars.

6. Variation in Facial Patterns: Lower anterior facial height increased 2.2

mm; there was no significant difference in lower anterior facial height increase between patients of high, neutral, or low mandibular plane angles.

For maximum maxillary first molar distalization with minimal increase in lower anterior facial height, this appliance appears to be best used on patients with maxillary second deciduous molars for anchorage and the absence of erupted permanent maxillary second molars, although significant bite opening was not of major concern in any patient in the study.

Distalization appliances based on NiTi wires and coils

Superelastic coils

Superelastic archwire: single looped,

double looped

1. SUPER ELASTIC NiTi COILS Anthony A. Gianelly (AJO 1991) used Japanese NiTi super elastic coils, exerting 100 gm of force, compressed against the maxillary first molars and moved the molars distally 1 to 1.5 mm/month. Coils are used in conjunction with a vertically slotted (0.020-inch) fixed appliance. A passive 0.016 ´ 0.22-inch wire with stops that abut the distal wings of the premolar brackets is inserted to ensure that the wire cannot move past the first premolars, thus placing the reaction force on the Nance appliance. Coils are placed on the wire between the first premolars and the molars. The coils are activated 8 to 10 mm by compressing and maintaining them against the molars by crimpable hooks or Gurin locks.

Anchorage A Nance-type appliance was cemented onto the first

premolars. The appliance extends from the incisors to the molar area and a bite plate is added to the incisal portion to disclude the posterior teeth slightlyAnchorage enhancement:

To enhance anchorage further, a 0.018-inch uprighting spring is placed in the vertical slot of the premolar brackets, directing the crowns distally.

Class II mechanics are used only when anchorage loss is at least 1 mm.

When Class II elastics are attached, a rectangular wire with 10° of incisor lingual root torque is inserted in the mandibular arch to maintain lower incisor position.

100 gm superelastic coils can be used successfully in patients with Class II malocclusions to move molars posteriorly at the rate of 1 to 1.5 mm/month with little or no cooperation from the patient.

SUPER ELASTIC NiTi WIRES The use of shape memory, superelastic Nickel Titanium

wires in distalizing the molars have been discussed by Ranieri &

Antony A.Gianelly in 1992.JCOFABRICATION

Gianelly used a superelastic NiTi arch wire here. 1. A 100 gm Neosentalloy wire with regular arch form is

placed over the maxillary arch. The superelastic NiTi wire is an 0.018 X 0.025 inch wire that also applies 100 gm of force.

The wire is then marked in three places on each side. A. At the distal wing of the first premolar bracket. B. 5-7 mm distal to the anterior opening of the buccal

tube C. Between the lateral incisors and canines

A stop is then crimped on the arch wire at each of the posterior marks and a hook is then added for inter-maxillary elastics between the lateral incisors and canines.3. The wire is then inserted into the molar tube until the posterior stop abuts the tube.

To place the wire through the first premolar bracket, the anterior stop is grasped and the wire gently forced distally so that the stop abuts the distal wing of the first premolar bracket, when ligated.

Since the wire is 5-7 mm longer than the available space, the excess will be deflected gingivally into the buccal fold.

ACTION OF THE WIRE/APPLIANCE The distalization of the molars occur as the wire returns to its

original shape, exerting a distal force of 100 gms against the molars and a reactionary mesial force on the first premolars, canines and incisors.

There is also a tendency for the premolars to move buccally.THE ANCHORAGEThe anchorage can be controlled by

a. Placing a 100-150 gm class II elastics against the first premolars. (or)

b. Placement of hooks between the lateral incisors and canines (or)

c. A Nance appliance cemented to the first premolars.

THE ADVANTAGE OF THE APPLIANCE 1. The appliance distalizes the molar at the rate of 1-2 mm

per month with little loss of anchorage. 2. The Neosentalloy wire is easy to insert even after all

teeth have been bracketed or banded.

Giancotti, & Cozza (JCO 1998 April) used double loop for simultaneous distalization of both molars Superelastic nickel titanium wires have been found as effective as other means in producing distal movement of the maxillary first molars. When the distalization is carried out before the second molars have erupted, it can reliably produce 1-2mm of space. Once the second molars have erupted, however, the distal movement can be more difficult and time-consuming, and loss of anchorage is likely. Author used Nickel Titanium Double-Loop System for Simultaneous distalization of First and Second Molars. Appliance Design The mandibular first and second molars and second bicuspids are banded, and the remaining mandibular teeth are bonded. A lip bumper is placed to prevent any extrusion from the use of Class II elastics. The maxillary molars and bicuspids are banded, and the anterior teeth are bonded

An 80g NeoSentalloy archwire is placed on the maxillary arch and marked distal to the first bicuspid bracket and about 5mm distal to the first molar tube . Stops are then crimped in the archwire at each mark (distal to 4 and 6)

Two sectional nickel titanium archwires (one for each side) are prepared by crimping stops distal and mesial to the second bicuspids and about 5mm distal to each second molar tube.

Uprighting springs are inserted into the vertical slots of the first bicuspid and Class II elastics are placed

JONES JIG APPLINCE Introduced by Jones & White in 1992. Jones Jig uses an open-coil nickel titanium spring to deliver

70-75g of force, over a compression range of 1-5mm, to the molars.Appliance Fabrication

A modified Nance appliance provides anchorage for the use of the Jones Jig. Modification in Nance:

It can be attached to the first bicuspids, second bicuspids, or deciduous second molars. The appointment sequence is as follows:

Appointment 1 : Separators are placed between the first molars and the anchor teeth.

Appointment 2 :Impression is made with bands. Pour the impression with the bands in stone.A .036" stainless steel wire is adapted to the palate on the cast, extending it as far as the canines, and soldered to the anchor bands.

The Jones Jig assembly consists of a mainframe of two prescriptions (0.018 & 0.22 inches respectively), which can be contoured in the anterior one third. It also consists of a mainframe hook which is tied to the hook of the molar tube. The force is delivered by a Nickel Titanium coil spring, which acts along the mainframe wire, when activated using a ligature. A 0.014 inch ligature wire is generally used to fasten the eyelet tube to the premolar bracket, which compresses the NiTi coil springs. The distal end of the mainframe consists of a keeper wire (0.018 inch) which goes into the archwire slot and a mainframe wire which enters the head gear slot of the molar tube. The extreme mesial end of the completed assembly should rest no further than the distal 1/3rd of the bicuspid.

ACTIVATION A 0.014 inch ligature wire is wound around the buccal

tube and the mainframe hook very lightly. Then a 0.012 inch-ligature wire is wound twice around the premolar bracket and the mesial end passed through the eyelet tube. The ligature wire is then tightened until 'light' through the middle of the open coil is barely seen.

Bunching or over activation of the coil spring should the avoided as it can lead to unwanted tipping and palatal irritation along the palatal button.

Although the force of the Jones Jig is applied in a Class I direction, the appliance may be contraindicated in cases of extreme vertical growth patterns, because extrusion of the molars is not restricted.REACTIVATION

Reactivation takes very little chair time and is due over a period or four to five week intervals.

TREATMENT TIME In Pseudo class II where it is the rotated class I which needs to be corrected, the treatment time is 90-120 days. In true class II molar relationships, the corrected class I relationship can be achieved in 120-180 days. However the treatment time is slightly increased in brachyfacial patterns.

Drawback: The use of the Nance appliance causes palatal tissue impingement. Laboratory expense Extra appointment needed to fit the Nance appliance. Coils demand extra diligence in cleaning

Comparison of Jones jig molar distalization appliance with extraoral tractionSeda Haydar (AJO 2000 Jan)

20 patients in late mixed dentition period with skeletal Class I or slight Class II malocclusions, with dental Class II relationship were treated with Jones jig and headgear. Ten cases were treated with the Jones jig appliance for upper molar distalization, and 10 patients used cervical headgear for correction of dental Class II relationship. The mean age was 10.6 and 10.7 years, respectively, for headgear and Jones jig group. Long cervical face bows were used, and the outer bows were parallel to the occlusal plane exerting 600 g of force with an average use of 16 hours per day until a Class I molar relationship was reached. Average treatment time for distalization with headgear was 10.7 months followed by a fixed appliance phase of 11 months.

In the Jones jig group, the spring was activated at 4 week intervals and 75 g of force was applied because 5 mm of activation was made at each visit. A modified Nance appliance was used as an anchorage unit. The average treatment time to move molars distally was 2.5 months. After distalization of molars, fixed appliance therapy was applied to each patient and total treatment time was 15.1 months.Skeletal change:

In the headgear group the decrease in SNA angle was found statistically significant, downward tipping of palatal plane was also found statistically significant.

On the other hand, none of these effects occurred in the Jones jig treatment group.

In this study, no increase was observed in GoGnSN angle in both groups.

Effect on molars and premolars In the headgear group, the distalization of

maxillary first molars and maxillary second premolars was a consistent finding

In the Jones jig group, the distalization and distal tipping of maxillary first molars and mesial movement of premolar occurred.

Extrusion of maxillary first molars was observed in both groups, but it was found statistically significant only in Jones jig group.

Jones jig group, showed mesial tipping of the anchorage unit, this is contrary to the finding in the headgear group in which spontaneous distalization of premolars was observed as a result of the distalization of molar teeth. Effect on Incisors

Headgear group, showed the extrusion and retrusion of incisors that might occur as a result of the retraction effect of headgear on anterior teeth.

Jones jig group showed protrusion of the incisors because the incisors were part of the anchorage unit

Average treatment time The average treatment time for molar correction with headgear and Jones jig was 10.7 and 2.5 months, respectively. Because intraoral distalization moves molars distally in a very short time, total treatment time is reduced by at least 6 to 8 months despite the fact that the anterior teeth move or tip mesially during molar correction. Although a distal drift of premolars take place during distalization, this does not reduce the total treatment time because treatment may cease at times when headgear cooperation is poor. Intraoral distalization seems more appropriate for regaining space for cases in which no orthopedic effect is desired on the maxilla as with skeletal Class I or borderline Class II patients.

Brickman, & Nanda ( AJO 2000 NOV) evaluated the effects of the Jones jig appliance on distal movement of maxillary molars and reciprocal effects on premolars and maxillary incisors.

Measurements were made on a matched sample of 35 patients treated with cervical headgear and compared with result of 72 patients treated with Jones jig.

Both series of patients were treated to correct an Angle Class II molar relationship. The results from the Jones jig sample showed

Mean maxillary first molar distal movement was 2.51 mm & distal tipping of 7.53°.

The mean reciprocal mesial movement of the maxillary premolar was 2.0 mm and mesial tipping of 4.76°.

The maxillary first molar extruded 0.14 mm & the maxillary premolar extruded 1.88 mm

The maxillary second molars were also moved distally 2.02 mm and tipped distally 7.89°.

The Jones jig sample demonstrated effective distal molar movement and maintenance of the Class I molar relationship. Cervical headgear sample showed treatment results comparable with Jones Jig.

The longitudinal assessment showed significant differences between the Jones jig sample and the cervical headgear sample for lower lip to E-line and SNA.

1. The Jones jig sample showed a mean decrease in lower lip to E-line of 0.25 mm versus 1.20 mm for the headgear sample.

2. SNA decreased 0.40° for the Jones jig sample versus 1.20° for the headgear sample.

DISTAL JET Distal jet was designed by Aldo

Carano & Mauro in 1996.Appliance Design

Bilateral tubes of .036" internal diameter which is attached to an acrylic Nance button.

A NiTi coil spring and a screw-clamp are slid over each tube.

The wire extending from the acrylic through each tube ends in a bayonet bend that is inserted into the lingual sheath of the first molar band. An anchor wire from the Nance button is soldered to bands on the second premolars

Components: 1. The Transpalatal connector – rigidly immobilizes the premolars and

provides a support to the Nance button. 2. The bayonet director unit - Lumen of the tube portion supports the

molar bayonet, while its outside diameter supports the spring and the activation lock.

3. The molar bayonet - It is drawn out of the bayonet director unit during distalization and inserts into the lingual sheath.

4. The Distal stop - Prevents the spring from riding up on the vertical arm of the molar bayonet while activation of the appliance.

5. Nickel titanium springs - Two force ranges - 180 gms and 240 gms. 6. Activation locks - To compress and activate the springs. 7. Lock wrench - To engage and tighten the screw of the activation

lock

1. TP connector

2. Bayonet director

3. Molar bayonet

6. Activation lock

7. C Res

Activation: The Distal Jet is

reactivated by sliding the clamp closer to the first molar once a month.

Once distalization is complete, the appliance can be converted to a Nance retainer simply by replacing the clamp-spring assemblies with cold-cure acrylic and

cutting off the arms to the premolars.

Advantage of distal jet : The appliance is relatively easy to fabricate, easy to insert,

is well tolerated and is esthetic. Easy activation Ease of conversion to a Nance holding arch to maintain the

distalized molar positions. The Distal Jet also permits the simultaneous use of full

bonded appliances, possibly avoiding the need for two phases of treatment

MODIFICATIONS OF DISTAL JET

Bowman (1998 Sept JCO) described several modifications to the original appliance.

Conversion to Nance Holding Arch:Upon completion of molar distalization, the Distal Jet is converted to a Nance holding arch to prevent further distal movement and consequent anchorage loss. It can be done by these two methods:

1. One way to stop movement of the bayonet wire through the tube is to flow a light-cured acrylic around the coil spring, over the distal bayonet bend, and over the activation collar to produce a solid extension from the molar bands to the acrylic button.

2. Wrap an .014" stainless steel ligature wire around the end of the doubled back wire (extending distally from the lingual sheath on the first molar band) and tie it around the tube just mesial to the activation collar. The coil spring should be compressed completely and the set screw tightened to prevent mesial movement of the molars.

Double -Set -Screw Distal Jet A modification of the Distal Jet

incorporating two set screws into the activation collar permits an easier, cleaner, and more reliable conversion to a molar Nance holding arch.

The mesial set screw is used during active distalization .The distal screw is set on the bayonet wire, locking the two pieces together to prevent molar movement.

The premolar supporting wires are sectioned where they enter the acrylic button, using a high-speed handpiece and diamond bur.

The bayonet wire or tube can be bent with a three-prong plier to adjust the pressure of theacrylic button against the palate

Conversion of double-set-screw Distal Jet to Nance holding arch: A. Upon completion ofmolar distalization, double-set-screw activation collar is slid mesially to gain access to coil spring.B.Free end of coil spring is grasped with plier. Coil spring is removed by peeling it away from bayonet wire.C. Distal end of tube, where bayonet wire enters, can now be seen.D. Double set-screw collar is slid back to this junction, mesial set screw is locked on tube, and distal screw is set on bayonet.

Quick & Angela Harris (JCO 2000 July) The Distal Jet is a fixed palatal appliance that is

most commonly used to distalize the maxillary molars, either unilaterally or bilaterally.

Disadvantage of Distal jet: Lies in activation The appliance is activated by sliding a collar

along the supporting tube to compress a coil spring, then fixing the collar in place by tightening a small set-screw.

This procedure is sometimes difficult because of the small size of the screw, the moisture and confined space of the intraoral environment, and food impaction in the screw head.

In addition, activation requires the use of a small Allen wrench, which has the risk of being swallowed or aspirated.

Appliance Design The basis of the modification is the rear entry of the sliding section into the lingual molar sheath, so that the appliance pulls rather than pushes the molars distally. The doubled-backwire (or “foot”) is inserted into the lingual sheath from the distal. The foot should be a little longer than the sheath so it can be tied back to the sliding section with an elastomeric or metal ligature. Either .030" or .032" wire is suitable for the sliding sections. Support tubes of corresponding internal diameter are embedded in the acrylic Nance button. The desired amount of activation is achieved by compressing the coil spring between the distal end of the support tube and a stop soldered to the sliding wire.

To reactivate the appliance, the safety ligature is cut, the sliding wire is pulled out distally, and a new, longer section of coil is placed over the wire.

In addition, no set-screws or Allen wrenches are used, simplifying the activation procedure.

After molar distalization is completed, the molar positions are held by replacing the open coils with either closed coils or solid tubing to prevent anterior relapse or a new Nance button can be made.

THE FIXED PISTON APPLIANCE The appliance was described by Raphael U.Greenfield in 1997. The appliance proposed to achieve distal bodily movement of the molars without tipping the crown with no loss of posterior anchorage. THE APPLIANCE

The components of the appliance are: a. Maxillary first molar and first bicuspid bands. b. 0.036" stainless steel tubing (soldered to the bicuspids). c.0.030" stainless steel wires (soldered to the first molar). d. Enlarged Nance button reinforced with an 0.040" stainless steel wire for control of anterior anchorage. e. 0.055" hyperplastic nickel titanium open-coil springs - to provide a light but continuous force.

Fabrication 1. The first molars are banded with a double or triple tube. 2. The first / second bicuspids are then banded. Normally the buccal and lingual piston assemblies should extend to the embrasure of the cuspid and first bicuspid to be long enough for adequate distalization. In maximum molar distalization however, the piston assembly may be extended beyond the first bicuspids. 3. A full arch silicone/vinyl impression is then taken such that the bands seat securely in the impression. 4. The bands are then waxed and a working cast in stone is made.

5. A 0.040" stainless steel wire is then adapted to the palate and is brought posteriorly to the gingival third of the bicuspid for soldering.

6. A 0.036" stainless steel tubing is then soldered to the buccal and lingual occlusal thirds of the bicuspid bands.

7. The 0.030" stainless steel wire is soldered to the buccal and lingual surfaces of the first molar bands. 0.040" stainless steel Nance wire is then soldered to the bicuspid bands.

The piston assemblies must be parallel in both the occlusal and sagittal views.

A slight palatal cant from distal to mesial can however be given to prevent occlusal displacements of the palatal acrylic.

A 2mm split ring stop is than added to the mesial of the buccal and lingual tube on each piston assembly every 6 to 8 weeks. This provides around 25 gms of force to each piston assembly which works out to 50 gms per tooth.

THE ADVANTAGESThe fixed piston appliance has been proved to be effective in molar distalisation and is said to have the following advantages:

Bodily movement of maxillary first molars (with no loss of posterior anchorage). Minimum patient compliance. Allows the use of head gear if needed. In non-extraction cases, it is proved to reduce treatment time as it distalizes at the rate of 1mm per month. Maintains the arch width after expansion with Haas or Hyrax appliances. Uses a light, controlled force of only 1-2 ounce per tooth. Because of this there is no loss of anterior anchorage and no inflammation of the palatal mucosa beneath and adjacent to the modified Nance button. Does not interfere with the occlusal plane, thus maintaining effective control over the vertical dimensions.

IBMD Ahmet Keles¸AJO (Jan 2000) 15 patients were treated with IBMD , their average age was 13.53 years old ranging from 11 to 16 Years old. Second molars were present in all the cases.

Appliance Construction The intraoral bodily molar distalizer (IBMD was composed of 2 parts: the anchorage unit and the distalizing unit. The anchorage unit was a wide Nance button, and the active unit consisted of distalizing springs The springs had 2 components: the distalizer section of the spring applied a crown tipping force, while the uprighting section of the spring applied a root uprighting force on the first molars.

Maxillary first molars and premolars were banded. On the palatal side of the first molar bands, 0.032 × 0.032 inch slot size hinge cap palatal attachments were welded, and a maxillary impression was taken. On the model, a wide acrylic Nance button was constructed and attached to the first premolar bands with 0.045 inch in diameter stainless steel retaining wires.

The acrylic button was constructed that functioned as an anterior bite plane to disclude the posterior teeth and enhance molar distalization.

For molar distalization 0.32 x 0.32 inch size TMA springs were bent and oriented from the acrylic. The springs had 2 components. The distalizer section of the spring applied a crown tipping force, whereas the uprighting section of the spring applied a root uprighting force to the first molars

B. The intraoral bodily molar distalizer (IBMD) was cemented to the first premolars without the springs engaged.

B. After the cementation, the hinge caps on the molar bands were opened.

C. Activation of distalizing componentD. Activation of the springs was accomplished by pulling

from distal to mesial with the help of a Weingart plier and then seating into the slot of the palatal hinge cap attachments. It applied a total of 230 g of distal force.

This study showed that maxillary 1st molars were distalized bodily 5.23mm on average. Maxillary molar extrusion was not observed after distalization. Maxillary molars did not rotate and intermolar distance did not change after distalization.

Class I molar relationship was achieved in an average period of 7.5 months.

Maxillary first premolars moved forward 4.33 mm, were extruded 3.33 mm, and tipped 2.7° distally.

A 4.77 mm protrusion and 6.73° proclination of the incisors were observed.

The overjet was increased by 4.1 mm; whereas the overbite was reduced by 2.63 mm. Mandibular first molars were extruded by 1.53 mm.

After the removal of IBMD, incisor protrusion and mesial migration of premolars spontaneously relapsed distally

Skeletal change:Mandibular plane angle

increased by 1.26°.Anterior lower face height to

total face height ratio was increased by 0.95 mm.

SNA increased by 1.56°, whereas ANB angle increased by 1.66°.

K-LoopPut forward by Valrun Kalra (JCO 1995)The K-Loop molar distalizer consists of

1. A K-Loop to provide the forces and moments. 2. A Nance button - to resist anchorage. The k-Loop is made of 0.017’ x 0.025' TMA wire which can

be activated twice as much as stainless steel, before it undergoes permanent plastic deformation.

A. The loop of the 'K' should be 8 mm long and 1.5 mm wide.

B. The legs of the 'K' are to be bent down 20 ° and inserted into the molar tube and the premolar bracket.

C. The wires are marked at the mesial of the molar tube and the distal of the premolar bracket.

A B C

D. Stops are bent into the wire 1 mm distal to the distal mark and 1 mm mesial to the mesial mark. Each stop are well defined and are about 1.5mm long.

E. These bends help keep the appliances away from the mucobuccal fold, allowing a 2mm activation of the loop

D E

The bends in the appliance legs produce moments that counteract the tipping moments created by the force of the appliance, and these moments are reinforced by the moment of activation as the loop is squeezed into place. Thus, the molar undergoes a translatory movement instead of tipping. Root movements are said to continue even after the forces dissipate.

For additional molar movement, the reactivation is 2mm after 6 to 8 weeks.

The premolars move forward by 1 mm during 4 mm of molar distalization (the anchorage loss). To prevent anchorage loss a head gear (straight pull or high pull) with forces of 150 g to the premolars can be used.

Advantages Simple & efficient Controls moment to force ratio to produce

bodily movement Easy fabrication and placement Hygienic and comfortable to the patient Low cost.

First class appliance Jco 99 June

Bands are placed on the maxillary first molars and on either the maxillary second premolars or the second deciduous molars.

Impressions are taken with these bands in place, and a working cast is poured.

Vestibular components: Formative screws are soldered on the buccal sides of the first molar bands, occlusal to the .022" × .028" single tubes, so they will not interfere with subsequent insertion of the archwire .

Split rings, welded to the second premolar or second deciduous molar bands, control the vestibular screws.

Stop screws are used to maintain the distal positions of the molars after active movement has been completed.

2. Palatal components. In the palatal aspect, the appliance is much like a modified Nance button, but is wider and has a butterfly shape for added stability and support during retention . The butterfly section is soldered to the second bicuspid or deciduous molar bands.The embedded .045" wires should be in single sections, without welded joints, to prevent breakage. Sections of .045" tube are soldered to the palatal sides of the first molar bands for insertion of the butterfly component of the appliance. These tubes allow the molars to be distalized without undesirable tipping.

Nickel titanium .010" × .045" coil springs, approximately 10mm each in length, are fully compressed between the bicuspid solder joints and the tubes on the deciduous molar or second bicuspid bands. These springs are designed to balance the action of the vestibular screws, preventing molar rotations and development of posterior crossbites.

Bodily distalization of first molars on both sides; detail of formative screw at end of activation

Fortini et al (AJO 2004 June) evaluated the treatment effects of FCA on 17 patients.

The FCA produced rapid molar distalization: bilateral Class II molar relationship was corrected in 2.4 months on average. The maxillary molar distalization contributed to 70% of the space created anterior to the first molars: 30% was due to reciprocal anchorage loss of the maxillary second premolars.

The maxillary first molars were moved distally an average of 4.0 mm per side with a mean distal tipping of 4.6°. Rate of distalization was 1.7mm / month.

Anchorage loss measured at the second premolars was1.7 mm with 2.2° of mesial tipping.

The maxillary central incisors proclined slightly during treatment (2.6°) with minimal increase in Overjet (1.2 mm).

No significant changes in sagittal or vertical skeletal relationships were observed.

Carriere Distalizer LUIS CARRIERE (JCO 2004 April) developed a new Class

II distalizer with advanced computer technology. Brachyfacial patterns respond best to treatment;

dolichofacial types are less responsive. Growing patients are ideal, but adults can be treated as well. Mixed dentition Class II cases with fully erupted first molars are candidates for first-phase treatment.Biomechanics:

The Carriere Distalizer is designed to create a Class I molar and canine relationship. The biomechanical objectives of the appliance are as follows:

1. Produce a distal rotational movement of the maxillary first molars.

2. Produce a uniform force for distal molar movement. 3. Independently move each posterior segment, from

canine to molar, as a unit.

Appliance Design The Distalizer is made of mold-injected, nickel-free stainless steel. It is bonded to the canine and first molar as follows: The canine pad, which allows distal movement of the canine along the alveolar ridge without tipping, provides a hook for the attachment of Class II elastics. This pad is the mesial end of an arm that runs posteriorly over the two upper premolars in a slight curve. The posterior end of the arm is a permanently attached ball that articulates in a socket on the molar pad.

The ball and socket joint provides torque (3D) control of both the canine and molar

The posterior portion of the Distalizer accomplishes three types of molar movement:

1. Uprighting of the crown, if it is mesially in clined .Once the molar has been upright ed; the articulation of the ball with the socket prevents distal tipping.

2. Distal rotation around the palatal root. When the molar has been derotated, the shoulder of the posterior base contacts the mesial arm to prevent over rotation.

3. Distal displacement without concurrent distal tipping of the crown

Appliance Placement The Distalizer comes in

three sizes: 23mm, 25mm, and 27mm. The appropriate size is deter mined by measuring from the midpoint of the maxillary first molar's buccal surface to the mid point of the maxillary canine crown, using a caliper or the supplied Dentometer.

In case of blocked out canines it is bonded to 2nd molar and 1st premolar.

Appliance is bonded to 1st molar and canine with a light cured adhesive

Possible 5 sources of anchorage: Passive .036’ lingual arch 0.45’ SS Hamula lingual arch Full mandibular fixed appliances Lower Essix appliance with hooks for elastics in lower

molar region. Miniscrews

Patient is instructed to wear heavy 6 ½ oz , ¼ “ Class II elastics 24 hours a day, except during meals.

BYLOFF et al (JCO 2000 sept) made a new device, based on the Pendulum that can distalize mandibular molars without the drawbacks of other appliances. Appliance Design

The Franzulum Appliance’s anterior anchorage unit is an acrylic button, positioned lingually and inferiorly to the mandibular anterior teeth, and extending from the mandibular left canine to the mandibular right canine.

Rests on the canines and first premolars are made from .032" stainless steel wire. Tubes between the second premolars and first molars receive the active components. The posterior distalizing unit uses nickel titanium coil springs, about 18mm in length, which apply an initial force of 100-120g per side

A J-shaped wire passing through each coil is inserted into the corresponding tube of the anchorage unit the recurved posterior portion of the wire is engaged in the lingual sheath of the mandibular first molar band.

The anchorage unit is bonded with composite resin to the canines and first premolars.

The J-shaped distalizing unit is then ligated to the lingualsheaths of the molar bands, compressing the coil springs. Thus, the active part of the appliance runs lingually at a level close to the center of resistance of the molar, to produce an almost pure bodily movement

During the distalization phase, the mandibular molars moved 4.5-5mm distally while the incisors moved 1mm anteriorly. The mandibular right molar crown tipped 4° distally, and the mandibular incisor crowns tipped 1° labially. Thus, the movement of the incisor crown resulted in an anchorage loss of 1mm and 1°.

B. Intermaxillary appliance:1. Herbst appliance2. Jasper Jumper3. Eureka Spring4. Klapper superspring

Herbst Appliance

The Herbst appliance is completely tooth-borne and uses both the maxillary and mandibular dentition to transfer the force exerted from the telescopic arms of the Herbst bite jumping mech anism to the bases of the maxilla and the mandible. The telescopic system produces a posterosuperiorly directed force on the maxil lary posterior teeth and an anteriorly directed force on the mandibular dentition. As a result, Class II molar correction generally is a combina tion of skeletal and dentoalveolar changes irre spective of facial morphology.

The Herbst telescoping bitejumping mechanism places a distal and intrusive force on the maxillary molars and the force vector passes occ1usally to the center of resistance. This force system produces backward and upward movements of maxillary molars in conjunction with distal crown tip ping. Because of the intrusive effect, distal movements of maxillary molars do not tend to open the mandible. These effects are similar to those produced by high-pull head gear.

In general, maxillary molar distal ization has been shown to comprise approxi mately 25% to 40% of molar correction with the banded Herbst appliance, whereas in the acrylic design it accounts for 20% to 25% of the correction.

The distalizing effects are reported to range from an average of 1.8 mm in the study by Franchi et al (AJO 1999) to 2.8 mm in the study by Pancherez (AJO 1982). The intrusive effects are 1mm approximately. The amount of distal and vertical movement of maxillary molars is found to be independent of the presence of erupted 2nd molar.Stability

In a long-term study on the results of Herbst treatment, Pancherz (AJO 1991) compared two groups of Herbst-treated patients with and without relapse in the occlusion. Skeletal and dentoalveolar changes in the mandibular arch were found to be similar in both groups 5 years after treatment. The reason for relapse was thought to be the anterior movements of maxillary dentition owing to muscular influence from the lips or tongue, or to an unstable occlusal condition after treatment.

 

The Klapper Superspring II: In 1997 Lewis Klapper introduced

the Klapper Superspring for the correction of Class II malocclusions. It resembles a Jasper Jumper with the substitution of a cable for the coil spring. In 1998 the cable was wrapped with a coil.

The Klapper Superspring II inserts from the mesial and is rigidly secured to the molar by an oval attachment tube. The Klapper Superspring creates a mo ment on the molar, which is expressed clinically as distal root tip, but extended wear of the appliance results in excessive distal root tipping.

 

Because the Klapper Superspring inserts gingivally on the molar and cannot roll to the buccal as readily as a Jasper Jumper, there may be a greater vertical component to the force vector. If this were of clinical significance, a patient with a pro nounced curve of Spee would level more quickly with the Klapper Superspring. However, extended wear should pro duce excessive intrusions and may require removal before sagittal corrections have been completed.

 Disadvantages of the Klapper Superspring: 1. Requirement of a special molar tube, 2. Limitation to maximal opening, 3. Risk of injury to the patient if breakage oc curs 4. Extended wear may cause excessive distal root

tipping to the maxillary molar and more intrusion to the molars and incisors than desired

The Eureka Spring 1997 JCO The interarch Eureka Spring

became available in 1996, has a pure compression action, and therefore delivers linear force throughout its range. It permits unlimited mandibular move ments and has good patient acceptance. It can be used in Class II and Class III malocclusions, does not require molar tubes, and can be used in conjunction with extraoral force. These springs come in two sizes and are converted at the time of insertion into left or right action; therefore inventory is minimal.

No auxiliary attachments are required. Because it is truly a compression spring, it is less prone to breakage than curvi linear than Jasper Jumper. A constant force of 16 grams per millimeter is generated, which permits the clinician to visually determine the force at any time and adjust the force as needed

A cephalometric evaluation of the first 50 consecutively treated bilateral Class II patients indicated the following:

Average anteroposterior correction was at the rate of 0.7mm per month.

For every 3 mm of anteroposterior correction, the maxil lary molars intruded 1 mm and the mandibular incisors intruded 2 mm.

The maxillary dentition moved distally 1.5 mm and the mandibular dentition moved mesially 1.5 mm.

No increase occurred in anterior face height between the dolichocephalic and brachycephalic subgroups.

As with the Jasper Jumper, intrusion of teeth occurs dur ing treatment. However, unlike the Jasper Jumper the amount of intrusive force can be altered by changing the force vector and magnitude

IMPLANT SUPPORTED DISTALIZATION

Karaman - implant-supported modified distal jet appliance

Graz implant supported pendulum Sugawara & Umemori SAS supported

mandibular distalization

Karaman (AO 2002 April ) A case report

In this study, author used an implant-supported modified distal jet appliance that has the advantages of implants and intraoral distalization appliances, and assessed its effect on dentofacial structures.

Molar bands with palatal tubes were fitted to the upper first molars. An anchorage screw three mm in diameter and 14 mm in length was placed at the anterior palatal suture, two–three mm posterior to the canalis incissivus under local anesthesia .

Anchor wires 0.8 mm in diameter were soldered to the tubes for occlusal rests on the first premolars. The 0.9-mm wire extended through each tube, ending in a bayonet bend that was inserted into the palatal tube of the first molar band.

For force application, Niti open-coil springs were adjusted.

The implant-supported modified distal jet appliance was attached to the anchor premolars and implant with light-cured composite adhesive.

The screw was removed without anesthesia and with no discomfort for the patient during the removal.

Maxillary molar moved distally 5mm after 4 months of treatment and intruded by 2mm without movement of premolars.

Upper incisor position, MPA, and LAFH remained the same.

The main advantages of the appliance are its stability against rotational movements. Adequate distal movement of the molar tooth was achieved without the loss of anchorage.

Irritation of the palatal mucosa and gingival hyperplasia didn’t occur because the patient could maintain optimum oral hygiene.

GRAZ IMPLANT SUPPORTED PENDULUM Byloff et al (Int J Adult Orthod. Orthognathic

Surg 2000) To avoid mesial movement of anchor teeth,

extraoral anchorage such as headgears and intraoral Nance holding arches are commonly used.

Advances with implants have made it possible to use them as a means of anchorage in adult orthodontic patients.

But with orthodontic patients, when only the question of anchorage must be addressed, the retro molar area or the palate as implant locations are preferred because they do not interfere with orthodontic tooth movement.

Site for Orthodontic Implants: The histomorphology of the palatal bone

shows that the median palatal region is the best location for an endosseous implant. Implant loading:

Implants are loaded after a period of approximately 12 to 24 weeks to allow healing and osseointegration, which seems to be a general rule in the use of implants.

Byloff described a newly designed palatal anchoring system, the Graz implant-supported pendulum (GISP) .This system can be loaded within 2 weeks to distalize and anchor maxillary first and second molars.

The anchorage part of the GISP consists of a simple surgical plate (15 X 10 mm) with 4 screw holes. Two cylinders (10 mm long and 3.5 mm in diameter) are soldered at right angles to the center of the plate.

The plate is fixed to the palatal bone via four 5-mm-long titanium mini screws The 2 cylinders perforate the palatal mucosa to enter the oral cavity .The entire anchorage device is made of 100% Titanium.

     Implant is placed under GA.     Maxillary impression is taken after 2 weeks

of healing.     Removable PA is fabricated. TMA springs are activated extraorally to

generate 250 g of force

Because molars tend to tip back when distalized with a PA,an uprighting bend ( Byloff AO 1997) was introduced into the recurved end of the spring when necessary.

After the 8 months of molar distalization, the first and second premolars have drifted distally, presumably under the influence of the elastic fibers in that area. The molars were almost in a full Class II relationship at the beginning of treatment

Advantages:1. Class II elastics to support anchorage are unnecessary, and side eff ects on the mandible are avoided. 2. This system can be loaded almost immediately, which is an advantage over implants requiring a healing and osseointegration time of at least 3 – 4 month.3. Unilateral distalization can be done without any effect of generated moment.4. Treat ment time is decreased because of the anchorage provided by the GISP. En masse retraction of anteriors can be done shortening the treatment time considerably.5. Stability against rotational movements

  Disadvantage: Invasive surgical procedure for insertion and removal of anchorage plates.

Sugawara & Umemori, (Ajo 2004Jan)   The skeletal anchorage system (SAS) consists of

titanium anchor plates and monocortical screws that are temporarily placed in either the maxilla or the mandible, or in both, as absolute orthodontic anchorage units, Distalization of the molars has been one of the most difficult biomechanical problems in traditional orthodontics, particularly in adults and in the mandible, However, it has now become possible to move molar's distally with the SAS to correct anterior crossbites, maxillary dental protrusion, crowding, dental asymmetries without having to extract premolars.

Skeletal anchorage system (SAS) uses pure titanium anchor plates and screws as absolute orthodontic anchorage units. The anchor plates are monocortically placed at the piriform opening rim, the zygomatic buttresses, and any regions of the mandibular cortical bone, Because the anchor plates work as the onplant and the screws function as the implant, SAS enables the rigid anchorage that results from the osseointegration effects in both the anchor plates and screws.

SAS does not interfere with tooth movement. Therefore, it is possible to distalize the mandibular molars with anchor plates placed at the anterior border of the mandibular ramus or mandibular body

  Sugawara & Umemori evaluated the treatment

and posttreatment changes during and after distalization of the mandibular molars, In 15 adult patients, a total of 29 mandibular molars were successfully distalized with SAS.

The amount of posterior displacement at the crown and root levels was measured on the occlusograms and the cephalometric tracings, respectively. The type of tooth movement was evaluated by the crown and root movement ratio. When the percentage ratio of the root movement to the crown movement (the tipping ratio) was less than 25%, the type of tooth movement was determined to be tipping.

 

The average amount of distal move ment with SAS was 3.5 mm at the crown level and 1.8mm at root apex level. The maximum amount of distalization at the crown level was 7.1 mm, and the minimum was 1.0 mm at the first molar. The average tipping ratio was 46.3%. Although most of the first molars showed bodily movement, 9 of 29 molars showed tipping movement, in which the tipping ratios were less than 25%.

Maximum relapse was 0.8 mm. and the maxi mum relapse rate was 40%. The average amount of relapse was 0.3 mm at both the crown and root apex levels. No significant correlation was found between the amount of relapse and the tipping ratio and the amount of tooth movement.

The SAS has outstanding advantages not provided by the other mechanisms for distalizing the mandibular molars.

1. It is possible to intrude the mandibular molars with the SAS. Therefore the extrusion of the mandibular molars after the tipping of the molar distalization can be corrected easily.

2. En masse distalization of the mandibular buccal segments or the entire dentition is also possible if the mandibular dentition is aligned.

3. With the SAS, it is not always neccssary to extract the mandibular first or second premolars even in patients with moderate to severe crowding.

4. Molar relationship in patients with symmetric or asymmetric Class III molar relationship can be corrected without having to extract mandibular premolars.

Conclusion Traditionally, the arch length deficiency has been calculated anterior to the first molars because molar distalization was assumed to be nearly impossible. However by using the space posterior to the second molars 14 permanent teeth can be well aligned in the alveolar bone as demonstrated by these studies. Therefore it will now become necessary to find an indicator to determine the posterior limits of the alveolar region from the standpoints of orthodontics, anatomy, and periodontology. E.g. Location of mandibular 3rd molar