hybrid functional appliance / orthodontic courses by indian dental academy

HYBRID FUNCTIONAL APPLIANCES

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INDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.com

Functional appliances has been widely used in Europe for more than 60 years.

Today they are appropriately regarded as biomechanical tools of dentofacial orthopedics.

According vig and vig (Ajo 1986) concepts such as functional correction are expressed in an interesting but scientifically fair Manner.


It Implies an understanding of

Craniofacial Biology

The cause of malocclusion

The specific adaptation response to each named appliances.

Clearly all appliances are capable of producing some changes with proper diagnostic objectivity .

The clinician can take advantage of the best parts of the appliance.


Hybrid functional appliances are specifically and individually designed to exploit the natural processes of growth and development.

It determines the selection of the component and their assemblies, resulting in appliance design that matches the needs of individual patient.


Modifications of activator The bow activator of A.M. Schwarz:

The bow activator is a horizontally split activator having a maxillary portion and a mandibular portion connected together by an elastic bow.

This kind of modification allows stepwise sagittal advancement of the mandible by adjustment of the bow. In addition this design allows certain amount of transverse mobility of the mandible.

The independent maxillary and the mandibular portions can have screw incorporated to allow arch expansions.


Wunderer’s modification:

used in treatment of Class III malocclusion.

This type of activator is characterized by maxillary and mandibular portions connected by an anterior screw.

By opening the screw the maxillary portion is moved anteriorly, with a reciprocal backward thrust on the mandibular portion.


The reduced activator of cybernator of Schmuth:

This modification of the activator is proposed by Professor G.P.F. Schmuth.

This appliance resembles a bionator with the acrylic portion of the activator reduced from the maxillary anterior area leaving a small flange of acrylic on the palatal slopes.

The two halves may be connected by an omega shaped palatal wire similar to bionator.


The propulsor: Designed by Muhlemann and refined by Hotz.

This appliance can be said to be a hybrid appliance that combines the features of both the monobloc and the oral screen.

The propulsor is devoid of any wire components and consists of acrylic that covers the maxillary buccal portion like an oral screen.

This acrylic portion extends into the inter occlusal area and also as a lingual flange that helps position the mandible forward.


Cutout or palate free activator:

This is a modification proposed by Metzelder to combine the advantages of bionator and the Andersen’s activator.

The mandibular portion of the appliance resembles an activator while the maxillary portion has acrylic covering only the palatal aspect the buccal teeth and a small part of the adjoining gingiva.

The palate thus remains free of acrylic thereby making the appliance more convenient for patients to wear the appliance for longer hours.

According to Dr Klaws Metzelder the appliance is excellent in mandibular positioning in TMJ dysfunction cases. www.indiandentalacademy.com

The Karwetzky modification:

This consists of maxillary and mandibular plates joined by a ‘u’ bow in the region of the first permanent molar.

The maxillary and mandibular plates not only cover the lingual tissues and lingual aspects of teeth, it also extends over the occlusal aspect of all teeth.

This type of activator allows stepwise advancement of the mandible by adjustment of the U loop.

The U loop has a larger and a shorter arm. Based on their placement pattern we can have three types of Karwetzky activators.


Type I: used in the treatment of Class II division I.here the larger lower leg is placed posteriorly. Thus when the two arms of the U bow are squeezed the lower plate moves sagitally forwards.

Type II: This is used for the treatment of Class III malocclusion. In this appliance the larger lower leg is placed anteriorly. Thus when the U bow is squeezed the mandibular plate moves distally.

Type III: They are used in bringing about asymmetric advancement of the mandible. The U bow is attached anteriorly on one side and posteriorly on the other side to allow asymmetric sagital movement of the mandible.


Herren’s modification of the activator

Herren modified the activator in 2 ways:

1. By over compensating the ventral position of the mandible in the construction wax bite.

2. By seating the appliance firmly against the maxillary dental arch by means of clasps (arrowhead, triangular or Jackson’s)


The construction bite is taken in a strong mandibular protrusion.

This advanced position of the mandible causes the retractor muscles to try to bring the mandible back to original position. This causes a backwardly directed force on upper teeth and mesially directed force on lower teeth.

According to Herren, with every 1 mm increase of forward position of the mandible, the sagittal force on the jaws will increase by 100 gm. The amount of forward positioning of the mandible is 3-4 mm beyond the neutral occlusion i.e. in case of Class II molar relation the mandible is brought forward to Class I molar plus an additional 3-4 mm forward. A vertical opening of 2-4 mm is recommended. www.indiandentalacademy.com

Vig designed an appliance for the treatment of patients with the following problems

- sagittal mandibular deficiency

- Increase overjet and overbite

-Bilateral cross bite of mandibular posterior teeth.

-lack of space for eruption of second premolars

FRANKEL HYBRID APPLIANCE (AJO 1986)


Components •mandibular component has the features of frankle2 appliance (Lippads, Buccal shields, lingual pad with wire resting on the Cingulum.

•Maxillary portion has a bilateral posterior bite – block.

Mode of action •The maxillary bite blocks prevents vertical emption and mesial and buccal movement of the upper posterior teeth.

• Lower buccal shields prevent processes from the buccal musculature hence the lower posterior teeth can erupt vertically and laterally under the influence of the tongue pressure. www.indiandentalacademy.com

•Wires contacting the upper and lower lingual prevents the further eruption of anterior teeth.

• The bite registration in taken with the mandible in a forward position to correct the molar relation.

• The functional phase of treatment lasted for 10 months, which led to differential skeletal growth and mandibular change that shortened the treatment time of the fully banded appliances considerably.


Introduced by Neville Bass

Used – In growing patients with skeletal Class II malocclusion to optimize facial appearence and to rapidly and effectively correct the class II dental relationship.

Mode of action of Bass appliance - A well secured maxillary splint assures control of the upper arch. The anterior torquing spring prevents tipping and produces bodily movement of the incisors.

THE BASS APPLIANCE SYSTEM (JCO 1987)


-The maxillary arch is expanded with a Jackscrew or spring to prevent cross bite and allow more space for dental alignment.

- The lingual pads helps to hold the mandibular incisors in a protrusive position, the pads are progressively reactivated every 6-8 weeks as the mandible develops forward.


-A rigid face bow connected to a high full headgear is used to retard maxillary growth and control vertical development of the maxillary dentition.

- Buccal screens are used to improve the soft tissue environment of the developing dentition.


Advantages - Facial features are harmonized with good chin position.

- Balance and function of orofacial musculature is improved.

- Flattening of upper lip from retraction is avoided.

- The orthopedic phase last only 6-10 months.

-Speech quickly returns to normal ,there is no wire or acrylic lingual to the lower incisors

-- There are little chances of breakage.


--------------------------------Fig. 4 A. Anterior torquing spring. B. Cross-section of

torquing spring. Stippled area is relieved to avoid soft tissue swelling. Spring is lightly activated in palatal direction,

forming force couple between points x and x'. Small acrylic ledge Is required at point x'. C. Class II elastics attached to torquing spring. D. J-hook headgear attached to torquing spring. E. Attaching extraoral traction anteriorly allows

more vertical pull and greater premaxillary control.www.indiandentalacademy.com

. Fig. 6 A. Housing module with sliding

mechanism for lingual pads and side screens. B. Assembled module (patents pending). C.

Module with preformed

side screen


• Fig. 7 A. Top edge of lingual pads lies 3mm below gingival margin of Iower bicuspids. There is no contact with mandibular dentitlon. B. Pads are reactivated forward about every seven weeks. Each side is slid forward about 2mm, and lower Internal sliding tube Is gently squeezed with small plier to prevent retraction. C. After four activations.


Fig. 8 A. Side screen on model. B. Prefabricated side screen. C,D. Insertion of side screen. E. Inserting wire bent slightly

with triple beak plier for retention. (Custom screens are made to lie 2-3mm away from teeth and soft tissue and do not need

adjustment.)www.indiandentalacademy.com

Fig. 12 A. Maxillary splint replaced on models and waxed out for addition of side screens and labial screen. B. Screens built

up In acrylic, wax boiled out, and appliance removed from model.www.indiandentalacademy.com

Fig. 13 Polished appliance.www.indiandentalacademy.com

Fig. 14 Finished appliance. A. With mandibular pads In place. B. With side screens. C. With lip screens. D.

Intraoral view.www.indiandentalacademy.com

Designed by – Mickey Judras.

Used – for treatment of Class II malocclusion in the mixed dentition period.

Components - Two molar bands with lingual attachments

- Connecting wire (0.040) from molar bands.

- Anterior bite plate.

- Incisal ramp

RICK – A – NATOR APPLIANCE


The Rick – a – Nator in a very simple appliance which consists for 2 molar bands, Ist molar bands attached to an anterior bite plate.

Initially to encourage patient compliance, the anterior bite plate is flat for one month.

- next month the anterior bite plate places the incisor forword by the addition of an incisal ramp.

- The incisal ramp encourages the mandible to come forward which corrects the Class II molar relationship to class I and eliminates the overjet.


POSTERIOR BITE PLATE WITH HEADGEAR

Orton used posterior bite plate with headgear for the correction of Class II malocclusion with anterior open bite.

•The objective of this appliance is to intrude the upper posterior segment by at least 2 mm, so as to cause auto rotation of the mandible there by enabling, closure of the anterior open bite and 5-6mm of reduction in overjet.

• Here only the teeth in occlusion are overlaid with acrylic.

• The appliance is stabilized by Adam’s clasp on the upper permanent first molars and on Ist premolars.


-The palate is relieved so that full intrusion from occlusal and headgear pressure is taken by the posterior teeth.

- Another advantage is total freedom from spontaneous vertical development of upper and lower buccal

segments there by reducing the anterior open bite.


• ACTIVATOR HEADGEAR TREATMENT

• Head gear and activator have both been used

effectively for the treatment of Class II malocclusion.

• Hypothetically a simultaneous application of both appliances may result in number of desirable treatment effects greater than those induced by each appliance.


These changes believed to be are:

-Restraining the maxillary growth.

-Selective guidance of maxillary and mandibular dentoalveolar development.

-Some influence on mandibular growth or position.

Indications

-Adolescent patients with class II div 2 Molars.

-Preferably well formed dental arches although an abnormal arch shape or dental crowing in not necessarily contra indicated.


- Maxillary prognathism, mandibular retrognathism and decrease or increase facial height as treated differentially by varying the design and application of the appliance.

-The cervical headgear is claimed to be the most effective type of headgear for initiating an orthopedic displacement of the maxilla.

-Pfeiefer and Grobiky (Ajo 1982) preferred the use of cervical hedgear


Uses of CERVICAL HEADGEAR

- Extrusion of maxillary molars

- Applying orthopedic traction to the maxilla.The cervical headgear with a long outer bow is used. The inner bow is inserted into buccal tube attached to the maxillary Ist molar and the outer bow is adjusted to about 50 bellow the inner bow. This produces a predominantly distal forces through the centre of resistance of the molar teeth and lesser extrusive force component.

The Neck Strap produces a forces of approximately 400gms measured unilaterally, the activator used is modified for use with headgear applied to the maxillary Ist molars.


-Patients instructed to wear the appliances for 14 continuous hours a day, patients are seen once every 6 weeks

-During treatment once a Class I molar occlusion has been established this outer bow is raised above the inner bow for uprighting the molars .Teuscher (Ajo 1978)

Recommended the use of activator and high pull headgear as means of inducing vertical land sagittal maxillary displacement, achieving auto rotation and increase forward displacement of the mandible


Fig. 1 Headgear-activator combination.


Fig. 3 Patient with counterclockwise mandibular rotation. A. Before treatment. B. After headgear activator treatment. C. Five years later. D. Superimposition of pre-and post-treatment tracings. E. Superimposition of post treatment and five year post-treatment tracings.


In The correction of large saggital discrepancies between maxilla and mandible, the orthopedic effect of treatment is often of small magnitude when compared with the dentoalveolar changes.

A considerable amount of orthopedic improvement is needed in patient with large saggital discrepancies between the maxilla and the mandibular in order to accomplish a stable, esthetically and functionally satisfactory treatment result.

HEADGEAR – HERBST APPLIANCE


The appliances is constructed with cast splint banded to the lower arch and with bands on the upper perm Ist molar.

The bands were linked with a palatal bar and connected to the lower splint with Herbst Teclescopic arms, constantly keeping the mandible in a forward jump position.

Addition, a plate was constructed in the jaw as an anchorage for a Headgear to be worn 12-14 a day.

Lenant (Ajo-1993) found that prolongd retention period of over several years of activator wear was required.


A. Before treatment.B. B. Splints bonded to

teeth. C. C. Herbst telescoping

arms for correction of intermaxillary relationship.

D. Headgear worn at night.


-Albort oven used the functional regulator with headger for the treatment of vertical maxillary excess.

Long face syndrome is manifestated primarily by excessive lower face height.

This may result due to a number of reasons.

- Clockwise rotation of the mandible - High angle. - Narrow arches. - excessive exposure of maxillary teeth and gingiva. - Open bite. - Short ramus.

FUNCTIONAL REGULATOR WITH HEADGEAR (Jco 85)


The appliances consists of a regular headgear tubes to accept a face bow of a high pull headgear. The construction bite was 3-4mm protrusive, with 3-4mm inter maxillary clearance in the molar area.

The appliance was worn 20 hours/day and the headgear 12 hrs/ day, liplseal exercises are important for proper lipseal, treatment usually lasted for19 months.

Treatment of results Maxillary skeletal – no changeMaxillary dental – incisor tipped linguallyMandibular dental – no changeMandibular skeletal – chin moves forward.Vertical – changed towards Brachy facialwww.indiandentalacademy.com

Fig. 2 A. Modified function regulator. B. Occlusal

view. C,D. Side views. E. With facebow attached.www.indiandentalacademy.com

Fig. 3 Bite block discourages eruption of posterior teeth www.indiandentalacademy.com

Fig. 4 High pull headgear holds or intrudes posterior teeth.www.indiandentalacademy.com

Fig. 5 Case 1 before (top) and after (bottom) treatment.www.indiandentalacademy.com

Robert Miller (1996) introduced this appliance which reduces the number of moving parts that can lead to breakage. It is easy to use and more comfortable for the patient than the conventional cantilever type herbst.

Instead of a screw attachment, it has a ball joint connector and it needs no retaining springs.

To place the appliance, the maxillary sleeve attachments are fastened in a lock and key manner, after the crowns are cemented . The rods must be long enough so that they donot come out of the sleeves on maximum opening. They have forked ends that are crimped into the mandibular balls

FLIP LOCK HERBST APPLIANCE


This appliance was designed to prevent accidental or intentional removal by the patient as often happens due to loose screws, but it can be removed at the chair with a loop forming plier.

It is reactivatd every six to eight weeks using 1-3 mm spilt bushing that are crimped on to the rods as needed.

The molar tubes can be attached for fixed mehanotherapy.

The flip lock herbst can be combined with Jackscrew appliance.


Fig. 3 Flip-Lock Herbst appliance's ball-joint connector.www.indiandentalacademy.com

Fig. 4 End of rod crimped onto mandibular ball.


Fig. 5 Split bushings used for reactivation.www.indiandentalacademy.com

Fig. 5 Split bushings used for reactivation.


Mandibular Advancement Locking Unit (MALU) The MALU consists of two tubes, two plungers, two upper “Mobee” hinges with brass pins, and two lower key hinges with brass pins.

In the upper arch of the edgewise Herbst MALU appliance, only the Ist molars are banded, with 0.051” headgear tubes. A palatal arch can be used in cases of over expansion.

In the lower arch, the Ist molars are banded and the anterior segment is bonded from cuspid to cuspid with 0.22” brackets. The bicuspids may be left un – bracketed to help in settling the occlusion.

MODIFIED EDGEWISE HERBST APPLIANCE


Maxillary Malu attachment with copper pin opening. B. Mandibular Malu attachment with archwire slot and copper pin opening.

Assembled Herbst with Malu attachments


A 0.021” x 0.025” stainless steel archwire with slight labial torque in the anterior segment, is bent back tightly at the distal ends. Tipback bends mesial to the lower Ist molars are helpful in controlling the incisors.

Each upper Mobee hinge is inserted into the hole at the end of the MALU tube and secured to the Ist molar headgar tube with the brass pin.

Each lower hinge is inserted into the hole at the end of the plunger and locked to the each, distal to the cuspid, with the brass pin.

the length of the tube plunger assembly is adjusted according to the amount of mandibular protrusion needed.


by Ralph M. Clements and Alex Jacobson.

The function of the MARS appliance is similar to that of the Herbst appliance. in that the mandible is maintained in a continuous protruded position via compressive struts.

However there are several important differences between the two appliances.

advantages

1. Requires neither soldering nor extensive laboratory procedures.

2. Has minimal incidence of breakage.

THE MARS APPLIANCE


3. Does not depress the canines, open spaces in the premolar area, or flare mandibular incisors (provided the mandibular rectangular archwire is tied back to the terminal molars).

4. Is easily attached to or removed form the arch wire of a multi banded orthodontic appliance .

.Appliance design

The MARS appliance is composed of a pair of telescope struts, the ends are attached to the upper and lower arch wires of a multibonded fixed appliance by means of locking device


Each strut is composed of two separate parts; a piston or a plunger and a cylindrical or hollow tube.

These two components telescope together, forming an individual strut.

The free ends of the plunger and the hollow tube (strut) are attached to the upper and lower archwires by means of a slot and screw arrangement, which locks them securely in position on the arch wire.


Fig. 2. Telescoping struts of MARS appliance. Locking screw is illustrated in box at lower left-hand

corner of diagram.www.indiandentalacademy.com

Fig. 3. Piston fitted to the cylinder of a MARS appliance.


Fig. 4. A, Jaws in closed Class II centric position. B, Jaws protruded, condyle located toward crest

orarticular eminence. C, MARS appliance attached to jaws in position. D, Jaw opening with appliance in

position.www.indiandentalacademy.com

The AVC consists of 2 posterior occlusal splints, one for the upper and one for the lower jaw.

Samarium cobalt magnets are incorporated into the occlusal splints over the occlusal region of the teeth to be intruded.

One magnet per distal quadrant is used.

The magnets in the upper splints are incorporated in a mode to repel the magnets in the lower splints.

Therefore the appliance is a combination of acrylic posterior bite blocks and repelling magnetic forces.

ACTIVE VERTICAL CORRECTOR


To prevent unwanted cross bite development due to the shearing forces of repelling magnets ,angled buccal flanges are added to the lower occlusal splints to stablize the appliance during lateral jaw movements.

A heavy gauge stainless steel wire connects the occlusal splint of each arch.

The magnets are cylindrical in shape with a diameter of 10mm.

The magnents along with bite blocks measures 12mm in height.


Because SmCo is a highly reactive rare earth material they are best kept isolated from the oral environment.

Hence, they are sealed in stainless steel capsules.

If the anterior open bite is of skeletal origin than dental origin, it is preferred.

Hence, patients in the growing age and in the mixed dentition period are preferred to elicit maximum skeletal response.


When the posteriors are intruded , auto rotation of the mandible take place and the mandible moves anteriorly to close the open bite.

The AVC can be cemented or bonded.

At end of 12 weeks the appliance can be removed and can be used as a removel appliance.


Fig. 1. Example of the Active Vertical Corrector (AVC). Occlusal and tooth contact views of

mandibular appliance (A) and maxillary appliance (B).


Fig. 2. Seated Active Vertical Corrector (AVC).


Fig. 3. The AVC intrudes posterior teeth by reciprocal action as noted

by the arrows.www.indiandentalacademy.com

Fig. 4. Intrusion of posterior teath results in closure of the open bite and autorotation of the mandiblewww.indiandentalacademy.com

The inclined plane mechanism plays an important part in determining the cuspal relationship of the teeth as they erupt into occlusion.

Occlusal forces transmitted through the dentition provide a constant proprioceptive stimulus to influence the rate of growth and the trabecular structure of the supporting bone.

The muscles are the prime movers that modify the bone growth to meet the demands of function via the proprioceptive feedback mechanism.

When the appliance is removed at mealtime, the patient reverts to functioning with the mandible in a retrusive position.

TWIN BLOCK


The strongest functional forces are applied to the dentition during mastication and the proprioceptive functional stimulus to growth is lost if the appliance is removed while eating.

All the functional appliance that have evolved from the monobloc share ,the limitation that the upper and lower compartments are joined together. As a result, the patient cannot eat, speak of function normally with the appliance.

Moreover, it is impossible for the patient to wear a single piece appliance full time.

But the Twin Block appliance designed by William Clark (1989) can be worn for full time and it overcomes all the disadvantages of the other functional appliances. www.indiandentalacademy.com

Bite Registration

In class II division I, a protrusive bite is registered to reduce the overjet and the disto – occlusion on average by 5-10 mm.

The length of the patient’s protrusive path is determined by recording the overjet in centric occlusion and fully protrusive occlusion.

The activation should not exceed 70% of the protrusive path.


If there is an overjet of upto 10mm , the bite may be activated edge to edge on the incisors with a 2mm inter incisal clearance. This allows an overjet of upto 10mm to be corrected on the first activation, without further activation of the Twin Blocks.

Larger overjet invariably require partial correction , followed by reactivation after the initial correction is complete.

Because the young patients commonly have a protrusive path of 13 mm and will tolerate activation upto 10 mm. Beyond this range the muscles and ligament cannot adapt to altered function.


In the vertical dimension, a 2 mm inter incisal clearance is equivalent to an approximately 5 or 6 mm clearance in the I premolar region.

This usually leaves 3 mm clearance distally in the molar region and ensures that the space is available for vertical development of posteriors to reduce the overbite.

It is very important to open the bite slightly beyond the clearance of the freeway space to encourage the patient to close into the appliance, rather than to allow the mandible to drop out of contact into rest position, which is one of the disadvantages of making the blocks to thin.


The earliest Twin Blocks were designed with the following basc components;

1. A midline screw to expand the upper arch.

2. Occlusal bite blocks

3. delta Clasps on upper molars and premolars

4. Delta clasps on lower premolars (it is similar to the Adam’s clasp in principle ,but incorporates new features to improve retention, reduce metal fatigue and minimize the need for adjustment)


5. Ball end clasps on lower incisors (originally it was given on lower incisors, but it can be given only on the lower canines mesially, in mixed dention, “C” clasps can be given on all deciduous molars)

6. Labial bow. (It should be passive. If retraction of upper incisors is done prematurely, it limits the scope for functional crrection for mandibular advancement. Later the design was changed from labial bow to ball end clasps – in between upper canine and premolars.


Occlusal inclined plane

The inclined plane on the lower bite block is angled from the mesial surface of the II premolars or deciduous molars at 700 to the occlusal plane.

In most cases, the inclined planes are angled at 700 to the occlusal plane although the angulation may be reduced to 450 if the patient fails to posture forward consistently and thereby to occlude the blocks correctly, to the marginal ridge on the lower II premolar or deciduous molar.

The upper inclined plane is angled from the mesial surface of the upper II premolar to the mesial surface of the upper I molarwww.indiandentalacademy.com

.

Clinical managementThe twin block treatment is described in two stages:

1. Active phase – the sagittal correction is achieved before vertical development of the posteriors is complete. Rapid soft tissue changes occur during this phase. The changes in the muscle activity has been described by McNamara as the “pterygoid Response” which results from altered activity of the medial head of the Lateral Pterygoid muscle in response to mandibular protrusion.

During this phase, selective grinding of the upper bite blocks occluso-distally for allowing supra-eruption of posteriors is important in management of deep bite


2. Supportive phase – the aim of the 2nd stage is to retain the corrected incisor relationship until the buccal segment occlusion is fully established. The upper inclined guide plane is only placed and fixed appliance can be initiated.

If the direction of growth is vertical rather than horizontal, the mandible may be advanced more gradually to allow adequate time for compensatory mandibular growth to occur.

Phased activation is recommended in adult tratment, where the muscles and ligaments are less responsive to a sudden large displacement of the mandible.


.

The Concorde Facebow

When the response to functional correction is poor, the addition of orthopedic traction force may be considered. The indications are confined to a minority of cases with growth patterns where maxillary retraction is the treatment of choice. For example 1. In the treatment of serve maxillary protrusion 2. To control a vertical growth pattern by the addition of vertical traction to intrude the upper posteriors. 3. In adult treatment where mandibular growth cannot assist the correction of a severe malocclusion.

A method was developed to combined extra oral and inter maxillary traction adding a labial hook to a conventional face bow and extending elastic, back to be attached to the lower appliance in the incisor region.


Magnetic Twin Block

Dr. William J. Clark has modified Twin Blocks by the addition of attracting magnets to occlusal inclined planes, using magnetic force as an activation mechanism to maximize the orthopedic response to treatment.

Attracting magnets

The increased activation can be built into the initial construction bite for the appliances. The attracting magnetic force pulls the appliance together and encourages the patient to occlude actively and consistently in a forward position.


Repelling Magnets

It may be used with less mechanical built into the occlusal inclined planes. It is intended to apply additional stimulus to forward posture as the patient closes into occlusion.

Indication for Magnetic Twin Blocks:

1. The patient with weak musculature fails to respond to functional therapy

2. Used only where speed of treatment is an important considerations.


Fig. 1. Twin blocks appliance design. A, Anterior and lateral views show the following components. Upper appliance: (1) labial bow (0.8 mm) from mesial , (2) clasps (0.8 mm) incorporating coils to accommodate the Concorde face-bow,

and (3) occlusal inclined planes occlude at a 45° angle in region. Lower appliance: (1) ball-ended interdental clasps (1.0 mm) in region, (2) delta clasps (0.8 mm) on (the delta clasp, designed by the author, gives excellent retention

on lower premolars and requires minimal adjustment), and (3) inclined planes in region. B, Occlusal views. The upper appliance has a midline screw for

compensatory lateral expansion. Where necessary, a midline screw or recurved lingual bow (as in a Jackson appliance) can be included in the lower appliance.


Fig. 1 (Cont'd). C, The Concorde face-bow effectively combines extraoral and intermaxillary traction in the treatment of severe skeletal

discrepancies. A recurved labial hook is added to a conventional face-bow. Outer bow is 1.5 mm; inner bow is 1.13 mm reinforced with tubing;

labial hook is 1.13 mm.www.indiandentalacademy.com

D, Intraoral views showing twin blocks in open and closed positions. The Concorde face-bow is

illustrated with detail of the recurved labial hook and

intraoral attachment of the intermaxillary elastic.www.indiandentalacademy.com

Carlos M.C. Filho (1995) introduced the Mandibular protraction appliance for the treatment of Class II malocclusion.

It is a cost efficient appliance in case of fabrication and rapid installation, with infrequent breakage.

It is also comfortable to the patient.

Mandibular protraction appliance


Mandibular Protraction Appliance No. 1

Fabrication

Mandibular Protraction Appliance with stops placed in mandibular archwire distal to cuspids


Small loop bent at right angle to end of .032" stainless steel wire.

Appliance length measured from mesial of maxillary tube to mandibular archwire stop with mandible in proper protruded position.


Small right-angle loop bent in opposite direction into other end of .032" stainless steel wire

Circles closed with plier after appliance placement.www.indiandentalacademy.com

A. Appliance slides distally along mandibular archwire and mesially along maxillary archwire upon opening. B. Buccal offset in lower archwire to allow clearance for sliding


Mandibular Protraction Appliance No. 2

MPA No. 2 made with right-angle circles in two pieces of .032" stainless steel wire.

Coil of .024" stainless steel wire slipped over one wire.


One end of each wire inserted through other wire's loop

Travel of each wire limited by wire coil.


Improper relationship of wires is prevented by coil

Maxillary archwire has occlusally directed circles against molar tubes; mandibular archwire has occlusal circles 2-3mm distal to each cuspid.www.indiandentalacademy.com

Measurement between mesial surface of maxillary molar tube and mandibular circle.

Appliance length transferred to wire assembly; attachment loops bent in wire ends for maxillary and mandibular occlusal circles.

Attachment loops inserted into archwire circles and squeezed closed.


Mpa-3

Problems of breakage, restricted opening, and patient discomfort associated with the MPA No. 1 and the difficulty of chairside construction of the MPA No. 2 have discouraged many orthodontists from using these appliances.

Many of the limitations of the first two MPA designs have been overcome with the development of the MPA No. 3. This version eliminates much of the archwire stress and permits a greater range of jaw motion while keeping the mandible in a protruded position.


John Devincenzo (1997) designed this appliance. The forerunner to this spring was a system devised by Northcutt (1974).

The device incorporates significant changes to the Northcutt’s design including triple telescoping action, flexible ball and socket attachment, a completely encased spring that remains intact even if the device becomes disengaged, and a shaft for guiding the spring.

The main component of the spring is an open wound coil spring encased in a plunger assembly.

The ram is made from a special work hardened SS wire that has been precision machined with three different radii.

EUREKA SPRING


At the attachment end ,the Ram has either a closed or an open ring clamp that attaches directly to the arch wire.

The plunger has a tolerance of 0.002 inch within the cylinder.

A triple telescoping action permits the mouth to open as wide as 60mm before the plunger becomes disengaged, even if it disengages it can be reassembled easily.

The cylinder assembly is connected to a molar tube with 0.032 inch wire that has been annealed at the anterior end.

A 0.036 inch solid ball at the posterior end acts as a universal joint permitting lateral and vertical movements of the cylinder.

The spring is within 1.5mm of full compression.

The force of the open wound spring is linear throughout the length of the Ram thrust and is 16.6 gm for every mm of Ram compression.


The maxillary molar crowns rolls buccally and intrudes while the mandibular anteriors intrude and the cuspid crowns tend to move lingually.

Since there is no tendency for extrusion of lower molars as in the Class II elastics, downward and backward mandibular rotation and elaboration of the face anteriorly will be minimal.

Since the Eureka spring intrudes the lower anteriors, over bite correction reduces, more by leveling the occlusal plane than by the downwrd and backward mandibular rotation.

Thus the spring tends to create the combination of forces ideal for improving facial form in most Class II malocclusion.


However these same forces work against facial form improvement during the correction of Class III problems.

Hence the force will have a tendency to intrude the maxillary anteriors and depress the mandibular molars.

Thus there will be a tendency towards development of anterior open bite as the maxillary anteriors are pushed forward and upward.

The mandibular molar crown will tend to roll bucally producing an increase in intra molar distance.


This may increase the tendency for a posterior cross bite.

Additional downward and backward mandibular rotation, which is frequently desirable, will not occur.

Do not expect any orthopedic effect from the Eureka springs.

All correction is entirely dentoalveolar.


It can be used in all phases of treatment in the mixed or permanent dentition and with removable or fixed appliance.

Like other mandibular protrusion appliances, the UBJ uses a telescopic mechanism, an active coil spring can be added if necessary. It can be used in Class II and III cases.

the UBJ is attached to the maxillary Headgear tube with a ball pin. In the mandibular arch ,the sliding rods end in a 900 hook that is fixed to the each wire.

Lower cantilever type of UBJ is also available when used with removable acrylic splints; two lateral UBJs link the maxillary molar areas and the mandibular Ist premolar areas.

THE UNIVERSAL BITE JUMPER


They are attached to 1.2-mm ball clasps, which are constructed on the working cast and then incorporated into the thermoformed splints.

The lower loop of the UBJ should be oriented in an anteroposterior direction.

Re- activation is made every 6-8 weeks by crimping 2-4mm splint bushing on to the rods.

UBJ with NiTi coil springs do not need to be activated.

Adjusting one side or the other of the appliance can easily treat midline or asymmetrical problems.


The disadvantages of the Herbst appliance are the rigidity of the Herbst bite jumping mechanism itself. Although every attempt is made to allow freedom of movement of enlarging the attachment holes of the tube and plunger to the axles, the bite jumping mechanism restricts lateral movements of the mandible.

In an attempt to overcome these problems, Jasper developed a new pushing device that is flexible. This appliance produces both sagittal and intrusive forces, and affords the patient much freedom of mandibular movement.

The jasper jumper can be attached to most of the commonly used fixed appliances .

JASPER JUMPER


The system is composed of 2 parts –the force module and anchor units

Force module

The force module, analogous to the tube and plunger parts of the Herbst, is constructed by a stainless steel coil 0r spring that is attached at both ends to stainless steel end caps, in which holes have been drilled in the flanges to accommodate the anchoring unit.

This module is surrounded by opaque polyurethane covering for hygiene and comfort.

The modules are available in seven lengths, ranging from 26mm –38mm.


They are designed for use on either side of the dental arch. When the force module is straight it remains passive, as the teeth come into occlusion the spring of the force module curves axially. As the muscle of mastication elevate the mandible producing a range of forces from 1 to 16 ounces, this kinetic energy is then captured when the force module is curved. This force is converted into potential energy to be used for a variety of clinical effects. If properly installed to produce mandibular advancement, the spring mechanism will be curved or activated 4mm relative to its resting length, thus storing about 8 ounces (250gm) of potential energy for force delivery.


If less force is desired the jumper is not fully activated.

Increasing the activation beyond 4mm does not yield more force from the module, but only guilds excessive internal stress in the module.

The tendency to increase the force for faster treatment results is to be avoided.

To determine the proper length of the module measure from the mesial of upper I molar buccal tube to distal of lower lexan ball.

Adding 12mm to this measurement will give the appropriate length of the module.


If the Class II molar relationship is not corrected completely by the initial activation, the module should be re-activated after 2-3 months.

The modular system is activated by shortening the attachment to the maxillary I molar.

The pin extending through the force bow tube is pulled anteriorly I to 2mm on each side to re-activate.

Activation of the force module can also be made through adjustments in the lower arch by crimpable stops (1-2mm) placed mesial to the Lexan ball.


The Churro Jumper is effective and inexpensive, alternative force system for the antero – posterior correction of class II and III malocclusions.

Although the Chrro Jumper was conceived as an improvement to the MPA, it functions more like the Jasper Jumper.

It is secured by bending the pin down on the mesial end of the tube.

THE CHURRO JUMPER


The Churro Jumper has several disadvantages that sometimes limit its usefulness:

The restriction of mouth opening to 30-40mm is intolerable for some patients.

Archwire breakage is common if larger wires are not used.

Patients with a low tolerance for discomfort will often break the appliance (as well as the spirit of the orthodontist).

Presently, it must be manufactured in the office.


ADVANTAGES

It provides a constant force.

It can be used either unilaterally or bilaterally. It can be used to correct Class II or Class III malocclusions.

Very inexpensive

It can be constructed from commonly available materials universal in size

When broken, it is easily and inexpensively removed and replaced.


SEVERAL ADJUSTABLE INTER MAXILLARY FORCE SPRING (SALF Spring )

SAIF spring is a fixed force system, which are available in either 7mm or 10mm lengths.

The 10mm spring, extended from the 2nd molar to the cuspid, provides the optimal horizontal force for antero – posterior correction.

Placement of right and left springs takes about 5 minutes.


1. during mixed dentition treatment, while using a functional utility arch wire, simply crimp a hook onto the anterior vertical leg of the wire. With full fixed appliances, make an offset bend in the maxillary arch wire, between the cuspid and the lateral incisor, where the hook is to be placed. This will prevent the crimpable hook from sliding on the arch wire and opening spaces.

2. offset the eyelet end of the spring so that it cant slip easily over the molar hook.

3. close the molar hook so that the eyelet will not slip off.

The procedure is an follows:


4. activate the spring 2-3mm and cut off the excess leader coil.

5. after attaching the leader over the anterior hook, close both the leader and the hook so that they will not come apart.

(Ajo 1997, Austria) Weiland et al did a study to see the initial effects of treatment of Class II malocclusion with the Herren Activator, activator headgear combination, and Jasper, Jumper.

They found that -www.indiandentalacademy.com

The correction of molar relationship and overjet was more complete in patients with Jasper – Jamper than in patient with the activator.

- Skeletal changes, that accounted for overjet correction by the Herren type activator was 42%.

By Headgear activator was 35% and by Jasper Jumper was 48%.

- The correction of molar relationship occurred to 55%, 46% and 38% respectively.


Ajo (1989) – Poncherz et al, did a study to compare the class II correction in bass and Herbst therapy.

He found that, after 6 months of treatment with bass appliance secured to have greater influence on mandibular jaw base position than the herbst appliance.

But the correction in overjet and saggital molar relationship was more complete in Herbst than in Bass patients.

This was due to more dental changes taking place in the Herbst subjects.


CONCLUSION

• Fixed functional appliances form an useful addition to the clinician’s orthodontic armamentarium. But many of these appliances need further studies to substantiate the claims made by their respective originators. With this in mind, clinicians must take great care in selecting the right patient and also pay attention to every detail in the manipulation to attain successful results with these appliances


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