EARLY TREATMENT OF CLASS III MALOCCLUSIONPreceptores:Dr Shalaj BhatnagarDr Meenu Presented by;Dr jasmine

INTRODUCTIONDEFINITIONCOMPONENTS OF CLASS IIICLASSIFICATIONEITIOLOGYEARLY SIGNS AND SYMPTOMS OF CLASS IIIRATIONALE FOR EARLY TREATMENTTREATMENT TIMINGSTREATMENT MODALITIESFACEMASKFM + RMEALT RAMECMMPHTTBAMODIFIED TTBAMAXILLARY PROTACTORCHIN CUPFUNCTIONAL APPLIANCE THERAPYFR IIIACTIVATORBIONATORTWO PIECE CORRECTOR*

INTRODUCTIONMandibular prognathism has received the attention of dental clinicians for several hundred years. In 1778, John Hunter, in writing in his book The Natural History of the Human Teeth, stated: It is not uncommon to find the lower jaw projecting too far forwards, so that its fore teeth pass before those of the upper jaw, when the mouth is shut; which is attended with inconvenience, and disfigures the face.

The use of restraining devices to reduce mandibular prognathism was reported in the early 1800s Cellier in France and Fox, Kingsley, and Farrar in the United States all designed appliances that resemble todays chin cup. These early attempts to correct mandibular prognathism tended to fail for one of two reasons. First, the forces generated by appliances in the 1800s were usually too small to have an influence on condylar growth mechanisms. Second, treatment was often begun after facial skeletal growth was completed, leaving the practitioner with the task of literally driving the mandible backward in the craniofacial complex. There was no clinical concept of growth guidance.

The early failure with the chin cup appliance was one of the reasons that orthodontists turned to intraoral appliances with intermaxillary elastics in an attempt to correct the Class III problem. By their very nature, however, the intraoral appliances limited the clinician to a dental correction in a skeletal malocclusion. While it was sometimes possible to mask the skeletal disharmony between upper and lower jaws with a dental correction, the majority of cases that were treated were compromised and unsuccessful.

A conceptual change in the treatment of the Class III malocclusion was offered in the late 1940s and early 1950ss After observation of the gross effects of Milwaukee brace treatment on the growth and form of the mandible, it was proposed that strong orthopedic forces in the range of 400 to 800 Gm. might be used to reduce a mandibular prognathism. The orthopedic force concept was put into actual use by directing strong forces to the mandibular basal bone through a chin cup mechanism. Although the design of the appliance was certainly not new, the use of heavy force was an important modification.

DEFINITION According to ANGLE class III malocclusion is defined as class III molar relation with the mesio buccal cusp of the maxillary first permanent molar occluding in the inter dental space between the mandibular first and second molars. Or lower permanent molar is ahead of the upper first molar by a distance of the width of a premolar or half the width of a molar.*

COMPONENTS OF CLASS III Guyer et al found that approximately 57% of the patients with either a normal or prognathic mandible showed a deficiency in the maxilla. In a sample of Chinese patients, Wu, Peng, and Lin found the percentage of skeletal Class III malocclusion with maxillary retrusion to be as high as 75%. Contemporary studies have found Class III to be composed of pure mandibular protrusion (19.1% to 45.2%), pure maxillary retrusion (19.5% to 37.5%), or a combination of mandibular protrusion and maxillary retrusion (1.5% to 30%).According to Ellis and McNamara 1984 and Sue et al 1987, maxillary retrognathism is present in 62% to 67% of all class III patientsAccording to Bell et al AJO 1981 maxillary retrognathism was found in 3040% and Jacobson et al AJO 1974 reported that the one-quarter of Class III malocclusions demonstrated retruded maxilla

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CLASSIFICATIONAcc to Delaire, Class III malocclusion can be classified as:

Maxillary retrusion with mandibular retrusionOrthognathic maxilla with prognathic mandibleMaxillary and mandibular protrusionMaxillary retrusion with orthognathic mandibleMaxillary and mandibular retrusionMaxillary retrusion with mandibular protrusionOrthognathic maxilla with mandibular retrusionMaxillary protrusion with mandibular orthognathiaMaxillary protrusion with mandibular retrusion

ETIOLOGY Class III malocclusion may have a multifactorial etiology. It can be broadly classified as:

Genetic:33 out of 40 decendants of the HABSBURG family had a class III jawEthnic3% in caucasians5% african american14% chinese and japanese(3.4% indians)Environmental (epigenetic):Large tongueForward tongue position ( eg in cases of adenoids)Mouth breathing

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Systemic: Acromegaly and hemi mandibular hypertrophy:

Acromegaly is caused by anterior pituitary tumour that secretes excessive amount of growth hormone. Here excessive mandibular growth occurs creating a skeletal class III malocclusion.

Teratogenic:

Teratogens causing cleft lip and palate are aspirin, cigarette smoke (hypoxia), dilantin, 6-mercaptopurine, valium vitamin D excess causes premature closure of sutures and might lead to class III malocclusion.*

EARLY EXTRAORAL SIGNS OF A DEVELOPING CLASS III

Early signs of true progressive mandibular prognathism can be observed from infancy.Straight or concave facial profileMalar deficiencyIncreased lower anterior facial heightAnatomically large lower lip length

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EARLY INTRAORAL SIGNS OF A DEVELOPING CLASS III

Eruption of the maxillary central incisors in a lingual relationship and the mandibular incisors in a forward position with no overjet.Development of an incisal crossbite during the eruption of the lateral incisors into a normal relationship.Flattening of the tongue as it drops away from the palatal contact and postures forward, pressing against the lower incisors

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EARLY SIGNS OF A DEVELOPING CLASS III

Zero overjetUnilateral/ bilateral posterior crossbiteProclined maxillary incisors and retroclined mandibular incisorsWide lower arch and narrow maxillary archFlat curve of spee

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EARLY SIGNS OF A DEVELOPING CLASS III

Habitual protraction of the mandible by the child into the protruded functional and morphologic relationship

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Pseudo class III*Habitual occlusionCentric relation

How to differentiate a dental crossbite from a skeletal crossbite

Cephalometric-Cranial featuresPatients with a Class III malocclusion exhibited a cranial base angle (Ba-S-N) that was more acute and exhibited a more anteriorly positioned articulare compared with patients with a Class I malocclusion.

Cephalometric-Maxillary features The horizontal "A Point" movement is approximately 0.4 mm/yr compared with 1.0 mm/yr in patients with a Class I malocclusion

Cephalometric-Mandibular featuresThe ascending ramus tends to be shorter with a steeper mandibular plane angle. The gonial angle is more obtuse in Class III malocclusions Typically, patients with Class III malocclusions display dentoalveolar compensation in the form of proclination of the maxillary incisors accompanied with retroclination of the mandibular incisors.

RATIONALE FOR EARLY TREATMENTEarly Timely Treatment Of Class III Malocclusion, Peter Ngan, Seminars In Orthodontics 2005 11:140-145To prevent progressive irreversible soft tissue or bony changes ( wear of mandibular incisors, gingival recession etc)To improve skeletal discrepancies and provide a favourable environment for future growth. Excessive mandibular growth is often accompanied by dental compensation of the mandibular incisors. Early orthopedic treatment improves skeletal relationships, hence minimizing dental compensationTo improve occlusal function (CR/CO discrepancy) To simplify phase 2 comprehensive trtTo provide more pleasing esthetics thus improving the psychosocial development of child

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Turpin has developed a list of positive and negative factors to aid in deciding when to interrupt a developing class III malocclusion

Positive factors:Good facial estheticsMild skeletal disharmonyNo familial prognathismAntero posterior functional shiftConvergent facial typeSymmetric condylar growthGrowing patients with expected good cooperation.

If the above factors are not present in the patient , they are listed as negative and treatment can be delayed until growth is completed.*

TREATMENT TIMINGSAccording to Delaire : Between 5 and 8 yearsClinically : at the time of the initial eruption of the maxillary central incisors

(Negan 1997 , Kapust et al 1998 , McNamara et al 2000)

Greater degree of anterior maxillary displacement can be obtained when protraction facemask therapy starts in the Primary or Early Mixed Dentition

(Baccetti Franchi McNamara . WJO 2001, Ngan, Semin orthod 2005)

Melsen , 1975 : The Circummaxillary sutures are smooth and broad before age 8 and become more heavily interdigitated around puberty (age 11-13)

Class III treatment with maxillary expansion and protraction is effective in the maxilla only when it is performed before the peak ( CS1 or CS2 ), whereas it is effective in the mandible during both prepubertal and pubertal stages .

(Baccetti , Franchi and McNamara . Semin Orthod,2005 The Cervical Vertebral Maturation( CVM) Method for Assessment of Optimal Treatment Timing in Dentofacial Orthopedics)

GROWTH TREATMENT RESPONSE VECTOR (GTRV)GTRV ratio of an indivisual with normal growth pattern of age 8-16 is 0.77That is, mandible usually exceeds the maxilla in horizontal growth by 23% to maintain good skeletal relation.Class III patients with excessive mandibular growth together with GTRV between 0.38- 0.88 can be successfully treated without surgery

TREATMENT OPTIONSFor retrusive maxillaFm + RmeAlt RamecMmphTtbaModified TtbaMaxillary ProtactorFor protrusive mandible- Chin CupFor combination therapy- Functional ApplianceFr IiiActivatorBionatorTwo Piece Corrector

FACE MASK THERAPYFace-mask therapy was first described more than a century ago, and since the late 1960s it has been used with increasing frequency for the correction of Class III malocclusion. In 1944, Oppenheim reported that it is impossible to move the mandible backward, but that it is possible to bring the maxilla forward to compensate for mandibular overgrowth when treating Class IIIThe use of protraction facemask was 1st done by Jean Delaire in 1875.It is indicated in cases of retruded or hypoplastic maxilla

DESIGN OF APPLIANCE: The orthopedic facial mask consists of three basic components. The facial mask, a bonded maxillary splint and elastics. The facial mask is an extra oral device composed of a fore head pad and a chin pad that are connected with a heavy steel support rod. To this support rod is connected a cross bow to which are attached rubber bands to produce a forward and downward elastic traction of the maxilla. The position of the pads and the cross bow can be adjusted simply by loosening and tightening set screws within each part of the appliance.

DESIGN OF APPLIANCE:

Acrylic component should cover crown of teeth leaving 1mm at the gingival marginMargins should have a chamfer finish to minimise food retentionOcclusally, thisckness should not exceed 1-2 mmHooks should be placed between lateral and canines approx 15 mm gingival to occlusal plane.The bite plane may be banded or bonded, however bonded is preferred due to ease of useA Hyrax may be placed in the mid palatal area to assist in correction of transverse discrepancy and loosen the circum-maxillary sutures

Class III mandible is often accompanied by a narrow, collapsed maxilla; thus RME alongwith FM is indicated Patients who have lateral discrepancies that result in either unilateral or bilateral posterior crossbites involving several teeth are candidates for rme. Cleft lip and palate patients with collapsed maxillae . A Hyrax may be placed in the mid palatal area to assist in correction of transverse discrepancy and loosen the circum-maxillary sutures

APPLIANCE MANIPULATIONAt the first appointment, the plate is bonded.On the 2nd appointment RME and traction is started. Rate= 0.5mm/day i.e. one quarter turn twice daily7-10 days of expansion followed by protractionIn patient in whom no increase in transverse dimension is desired, the appliance still activated for 8-10 days to disrupt the maxillary sutural system and to promote maxillary protraction (HASS 1965)Face mask should be worn for 10-12 hours dailyThe force generated by elastics should be in the range of 350-400g/side

After the patient has been accustomed to wearing the maxillary splint, the facial mask treatment is initiated.

Sequence of elastics: At the time of delivery 3/8 8 oz 2 weeks After 2 weeks 1/2 14 oz Increased to a max of 5/16 14 oz

Young patients (4-9) years should wear the mask on a full time basis except during meals. Clinically, the maxilla can be advanced 2 to 4 mm over a 12 to 15-month period of headgear treatment.*

Class III correction was a result of a forward movement of the maxilla with no downward and backward rotation of the mandible. However, improvement of the skeletal profile is greater in Group E, in which devices were anchored on deciduous teeth

DIRECTION OF FORCE APPLICATIONStaggers JCO 1992 - The orthodontist must first decide, whether to protract with a clockwise moment on the maxilla, a counterclockwise moment, or no moment. Protraction forces applied parallel to the occlusal plane, at the level of the maxillary arch, have been shown to produce anterior rotation and a forward movement of the maxilla. If the patient has normal overbite and normal vertical proportions, protraction without any moment is indicated. If the patient has an anterior open bite in addition to the maxillary deficiency, a clockwise moment should be used.If the patient has a deep bite, counterclockwise moment should be chosen.

Biomechanics:

According to Tanne et al and Hirato, The centre of resistance of the maxilla is located along the distal contacts of the maxillary first molars, one half the distance from the functional occlusal plane to the inferior border of the orbit.( Lee AJO 1997)Protraction of maxilla at or below the centre of resistance produces counter clock wise rotation of the maxilla. hata et al (AJO 1987)

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EFFECTS OF PROTRACTION FACEMASK WITH RMEAnterior displacement of maxillaForward movement of maxillary dentitionDownward and backward rotation of mandibleIncrease in LAFHIncrease in convexity and improved profile

ALT-RAMEC PROTOCOLLIOU described a unique protocol for effect maxillary protraction. It had 3 components:A two hinged rapid maxillary expander for greater anterior displacement of maxilla alternative weekly expansion and contstriction for disarticulating the sutures (Alt-RAMEC)Intraoral maxillary protraction springs for non compliant patients.

The expander was alternatively activated and deactivated for 9 weeks by 1 mm/day. This is followed by routine protraction.

MODIFICATIONS OF FACEMASK THERAPY

DESIGNS OF PROTRACTION FACEMASKSDelaire mask- 1978Extraoral anchorage from forehead, chinElastics attached between hooks soldered on intraoral arch

Petit -1983Forehead and chin padsForce generated from distal of maxillary molars

Supraorbital protraction appliance by GrummonsZygomatic areas provide more surface for anchorage

Protraction headgear by Hickham 1991More estheticMust be carefully adjusted behind the ear

(Am J Orthod Dentofacial Orthop 2000;117:27-38)Ichikawa et al and Kawagoe et al reported that conventional maxillary protraction headgears cause extrusion and anterior rotation of the anchor teeth, and upward and forward rotation of the maxilla. As the mandible is attached to the head with temporomandibular joint (TMJ), it is impossible to really stabilize the force system in reverse pull headgear, which takes anchorage from the chin, because the movement of the mandible does not allow us to apply a consistent force. In growing children, force application to the chin by reverse-pull headgear causes downward and backward rotation of mandible. Grummons claimed that reverse headgears might have harmful effects on the TMJ because they take support from the mandible.

It consists of a removable upper splint, a lower splint, and a traction bow. The upper splint contains the buccal hook (placed on the maxillary first deciduous molar or premolar region) and to the lower splint is attached a traction bow from the molar tubes.TTBA is delivered and patients are instructed to wear the appliance for 12-14 hours per day. Approximately 300-500 g/side of force is delivered from the lower traction bow to the buccal hooks of the upper splint, at an angle of 20 below the occlusal plane to minimize the counterclockwise rotation tendency

J Clin Orthod 2003;37:218-23

Maxillary expander: a full coverage acrylic cap splint type expansion appliance that covered all the maxillary dentition. Hooks embedded in both the premolar and the molar region on the buccal sides of the expander. The maxillary expansion appliance to be activated everyday (0.20 mm)Mandibular plate: a mandibular plate covering the posterior mandibular dental arch was constructed

Chincap: hooks were attached on the lateral sides of the acrylic chincap to apply cervical forces.

Lower face bow (1.2 mm in diameter): it attached the acrylic chincap to the mandibular plate. A horizontal bar was used to apply protraction elastics two to three cm in front of the lips (Figure 3c,d).

RETENTION AFTER FACEMASK THERAPYAcc to Delaire, facemask therapy should be retained by a thick posterior bite plane for the day and a chin cap for the night

CHIN CUP THERAPYSkeletal Class III malocclusion with a relatively normal maxilla and a moderately protrusive mandible can be treated with the use of a chin cup.

Review of literatureAccording to graber, the early attempts with the chin cup were not successful because of incomplete knowledge of mandibular and facial growth.Armstrong applied 500 gm of force via chin cups and reported that half of his patients showed improvement in the class III profile, whereas none of the control, non treated patients showed any favorable change.Thilander treated sixty patients with chin cups. A significant percentage of patients did not improve since the force generated by the chin cup in his study was only 150 to 200 gm. Graber, chung, and aoba reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 1.5 to 2 pounds on each side. They showed that mandibular growth could be redirected with a chin cup. They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results.

Chin cup therapy primarily works on the hypothesis that a force directed through the condyles will inhibit as well as redirect the condylar growth.

EFFECT ON MANDIBULAR GROWTHThe orthopedic effects of a chin cup on the mandible include1) redirection of mandibular growth vertically, 2) backward repositioning (rotation) of the mandible, and 3) remodeling of the mandible with closure of the gonial angle. To date, there is no agreement in the literature as to whether chin cup therapy may or may not inhibit the growth of the mandible . Because of the backward mandibular rotation, control of the vertical growth during chin cup treatment is difficult to manage.

EFFECT ON MAXILLARY GROWTH Some studies have indicated that a chin cup appliance has no effect on the anteroposterior growth of the maxilla.However, Uner, Yuksel, and Ucuncu showed that early correction of an anterior crossbite with a chin cup appliance prevents retardation of anteroposterior maxillary growth.

FORCE MAGNITUDE AND DIRECTIONChin cups are divided into two types: the occipital-pull chin cup- that is used for patients with mandibular protrusion and the vertical-pull chin cup - that is used in patients presenting with a steep mandibular plane angle and excessive anterior facial height. Appropriate force= 300 to 500 g per side .Patients are instructed to wear the appliance 14 hr/day. Usually in the evening and night The orthopedic force is usually directed either through the condyle or below the condyle.

Stability after chin cup therapy The stability of chin cup treatment remains unclear. Several investigators reported stability in horizontal maxillary and mandibular changes associated with chin cup treatment.

(Deguchi T, Kitsugi A: Stability of changes associated with chin cup treatment, Angle Orthod 66:139-146, 1996. 66. However, few studies reported a tendency to return to the original growth pattern after the chin cup is discontinued

Uner O, Yuksel S, Ucuncu N: Long-term evaluation after chin cup treatment, Eur J Orthod 17:135-141, 1995 Hideo Mitani: Recovery Growth Of The Mandible After Chin Cup Therapy: Fact Or Fiction, Semin Orthod, Sept 2007

Sugawara J et al: Long-term effects of chin cup therapy on skeletal profile in mandibular prognathism, Am J Orthod Dentofacial Orthop 98:127-133, 1990.Sugarwara et al published a report on the long-term effects of chin cup therapy on three groups of Japanese girls who started chin cup treatment at 7, 9, and 11 years. All 63 patients were followed with serial lateral head films taken at the ages of 7, 9, 11, 14, and 17 years.The authors found that the skeletal profile was greatly improved during the initial stages of chin cup therapy, but these changes were often not maintained. Patients who started treatment at an earlier age had a catch-up mandibular displacement in a forward and downward direction before growth was completed. The authors concluded that chin cup therapy did not necessarily guarantee a positive correction of the skeletal profile after completion of growth, which suggests the need for the extended use of the chin cup over the growth period.

Effects on TMJClinical Evaluation Of Temporomandibular Joint Disorders In Patients Treated With Chin Cup, Deguchi And Mimura, Angle Orthod 1998, 68(1)91-94.Anterior displacement of the disc is is the most commonly encountered type of internal derangement. Posterior displacement of the condyle which can be induced by the chin cup therapy, may cause anterior disc displacement

FUNCTIONAL APPLIANCE THERAPY

FRANKEL III APPLIANCEThe Frankel III (FRIII) regulator is a functional appliance designed to counteract the muscle forces acting on the maxillary complex.

Indication: This appliance has been used during the deciduous, mixed, and early permanent dentition stages to correct class III malocclusion characterized by maxillary skeletal retrusion, and not mandibular prognathism.

The FRIII appliance can also be used as a retentive device following maxillary protraction treatment

Appliance design and constructionThe FR-3 (Fig. 1) is composed of wire and acrylic. As with the FR-2 appliance, the base of operation is the buccal and labial vestibule.There are four acrylic parts of the FR-3:Two vestibular shields and two upper labial pads. The vestibular shields extend from the depth of the mandibular vestibule to the height of the maxillary vestibule. The upper labial pads that lie in the labial vestibule above the upper incisors function to eliminate the restrictive pressure of the upper lip on the under- developed maxilla

The upper labial pads of the FR-3 are in an inverted tear-drop shape in sagittal view. They should lie in the height of the vestibular sulcus parallel to the contour of the alveolus. The force of the upper lip is transferred by the upper labial pads to the vestibular shields. Since the vestibular shields lie in close approximation to the mandibular alveolus, the force of the associated soft tissue may be transmitted through the appliance to the mandible.

The upper labial pads are connected to the vestibular shields by a support wire The lower aspects of the vestibular shield are connected by a lower labial wire that rests against the labial surface of the lower incisors.

Upper lingual wire originates in the vestibular shield, traverses the interocclusal space, and rests against the cingula of the upper incisors. The palatal wire originates in the vestibular shields and traverses the palate behind the last molar present. Thus, the maxilla and the maxillary dentition are not restricted in their forward movement by the wires of the appliance. There are two pairs of occlusal rests in the molar region, one of which is optional. The purpose of this wire is to prevent the eruption of the lower first molar as is advocated by Harvold.

There are two pairs of occlusal rests in the molar region, one of which is optional. The purpose of mandibular rest is to prevent the eruption of the lower first molar as is advocated by Harvold. The maxillary occlusal rest is necessary only in cases of anterior crossbite so that only enough vertical opening is achieved to allow for the correction of the anterior crossbite. As soon as the crossbite has been corrected, the upper occlusal rest should be removed from the appliance to minimize bite opening.

Construction bite A horseshoe wafer of medium hard wax is used The bite registration is taken with the patient's mandible in the most comfortably retruded position. It is necessary to allow 1 to 2 mm of inter occlusal space in the molar region for the construction of the lower and, when necessary, upper occlusal rests. A wide open-bite registration should be avoided. In cases with an anterior open bite, only 1 mm of vertical bite-opening in the posterior region is necessary.*

Appliance activationAfter the appliance has been worn on a full-time basis for 3 or 4 months, the distance between the upper labial pads and the underlying alveolus will decrease. Thus, activation of the appliance is necessary to continue treatment. A crosscut fissure burr is used in a low- speed dental handpiece to free the ends of the labial- pad support wires. Enough acrylic is removed around the end of this wire to allow anterior advancement of the wire and maxillary labial pads. The lingual surface of the upper labial pads are kept 3 mm away from the underlying alveolus throughout treatment.

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CLASS III ACTIVATOR Somchai satravaha, (AJO 1999)The activator was introduced by andresen and has been long served for correction of skeletal class II malocclusions. Rakosi suggested modification of the activator for use in class III treatment. The goal of using a class III activator was to achieve posterior positioning of the mandible or maxillary protraction.

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The wire components are 4 stop-loops located mesial to all first molars to prevent mesial tipping of the molars and to stabilize the appliance, Lower labial bow to stabilize the appliance,Upper labial pads to remove the force of the upper lip and create periosteal pull to induce bone formation, and Tongue crib to correct anterior tongue thrusting habit.

The construction bite is taken by retruding the lower jaw. The upper labial pad of the activator is intended to protract the maxilla

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Treatment changesbackward positioning of the mandible. significant increases of the anb angle and the wits values.The snb and snpog get smaller resulting in increasing facial convexity (napog).The articular angle enlarges, thus augmenting the sum of the saddle, articular, and gonial angles.The facial axis opensThere are significant differences in the upper face height (n-ans), mandibular length (co-gn), and ramus length (ar-go). Dentoalveolar adaptations included labial tipping of the upper incisors as well as lingual tipping of lower incisors .

The shorter elastics (1/8 6oz ) are attached from the mandibular hook to the most anterior hook on the maxilla. As treatment progresses, it is moved to the posterior hook. The longer elastic on each side stretched from the mandibular hook to the molar hook can be , or 3/16 depending on the comfort.Duration: 12 hours a day in conjugation with face mask. 11 months of treatment time and 18 -24 months of retentionIndication: Mild skeletal class III where future surgery would not be indicated. And used during preadolescent and adolescent growth periods*

CLASS III BIONATOR (garatinni et al ajo 1998)BALTERS BIONATOR III can be used in patients with skeletal class III malocclusion. The use of this appliance causes some skeletal changes through neuromuscular modifications. CriteriaAngle class III molar relationship;Edge-to edge incisor position or anterior cross bite;Concave profile;Head hyperextension posture;Static and dynamic class III neuromuscular attitude;Hypertonic upper lip;Low and forward tongue rest position.

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Lower labial bow slightly in contact with lower incisors

Palatal bar upto 1st pm to position the tongue

Construction bite:The construction bite is taken by gently repositioning the mandible distally in centric relation technique. The mandible is positioned distally, applying as little force as possible in order to put the condyle in centric relation, avoiding compression in the retrodiscal pad. The vertical thickness of the bite, corresponding to the interocclusal acrylic between upper and lower first molar should not exceed 3 to 4 mm, patients had to wear this appliance for at least 22 hours a day.

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Results:Mean increase in the upper jaw length Advancement of point A Palatal and mandibular plane angles widened Increase of the anterior facial heightReduced antero posterior mandibular growth

therefore, the bionator III is helpful in class III malocclusion treatment in growing patients with midfacial deficiency, hypo divergent growth pattern, and reduced facial height.*

TWO PIECE CORRECTOR Egnhouse JR, Jco 1997The two-piece corrector was designed by Gerald.R.Eganhouse It is a removable acrylic appliance that simultaneously applies an anterior force to the maxilla and an equal posterior force to the mandible. The flat, sliding surfaces of the two pieces create almost no friction as the dentition is disoccluded during movement, but provide both lateral and anteroposterior stability

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