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Fixed functional appliiances /certified fixed orthodontic courses by Indian dental academy


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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

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  • 1. Fixed functional appliances
  • 2. INDIAN DENTAL ACADEMY Leader in continuing dental education
  • 3. CONTENTS • • • • • • • • • • • Introduction Historical back ground Classification Flexible fixed functional appliances(FFFA) Rigid fixed functional appliances(RFFA) Hybrid appliances Mode of action-theories on condylar growth Skeletal effects of bite jumping Treatment timing and outcome Conclusion References
  • 4. INTRODUCTION • Functional appliances are considered to be primarily orthopedic tools to influence the facial skeleton of the growing child in the condylar and sutural areas. • A functional appliance by definition is an appliance that produces all or part of its effect by altering the position of the mandible.
  • 5. • These appliances also exert orthodontic effects on the dentoalveolar area. The uniqueness lies in their mode of force application. • Functional orthopedic treatment seeks to correct malocclusions and harmonize the shape of the dental arch and oro-facial functions.
  • 6. Removable functional appliances have been used over the years and are clinically accepted. But they have some disadvantages: •normally very large in size, •have unstable fixation, •cause discomfort, •lack tactile sensibility, •exert pressure on the mucous • reduce space for the tongue, cause difficulties in deglutition and speech often affect aesthetic appearance. • alteration in the mandibular posture creates added difficulties.
  • 7. Fixed functional appliances have some advantages over removable systems: • They are designed to be used 24 hour a day • They are smaller in size, permitting better adaptation to functions • Reduce the need for patient compliance • As they are fixed on the upper &lower arches, transmit force directly to the teeth through support system
  • 8. HISTORICAL BACK GROUND Fixed functional appliances first appeared in 1900’s when Emil Herbst presented his system at the Berlin international dental congress. • Since then and up to the seventies, very little was published on this appliance. It was at that time that Hans Pancherz brought the subject back into discussion with the publication of several articles on the Herbst. • A number of fixed appliances have gained popularity in recent years to help achieve better results in noncompliant patients.
  • 9. • Originally, the telescoping parts of the Herbst appliance were curved conforming to the curve of spee. • Until 1934, Herbst made the telescopes of German silver. • In 1910, telescopic mechanism was placed upside down and anchorage system consisted of crowns on upper molars and lower first bicuspids.
  • 10. Original Herbst appliance
  • 11. Original curved Herbst telescopes • The telescoping parts were curved conforming to the curve of spee
  • 12. Standard anchorage system of Herbst • Crowns on upper first molars and lower first bicuspids • crowns joined by wires along palatal surfaces • Anchorage forms used from 1909 to 1934
  • 13. Anchorage forms from 1979 onwards • Pancherz used a banded type of Herbst appliance • Bands placed on upper first molars and premolars connected by sectional arch wires • Bands placed on lower first premolars connected by a lingual arch wire
  • 14. CLASSIFICATION Fixed functional appliances can be classified as: • Flexible • Rigid • hybrid
  • 19. FLEXIBLE FIXED FUNCTIONAL APPLIANCES(FFFA) • Flexible fixed functional appliances (FFFA) can be described as an inter-maxillary torsion coils, or fixed springs. • Elasticity and flexibility are the main characteristics of flexible appliances. • They allow great freedom of movement of the mandible. • Lateral movements can be carried out with ease.
  • 20. Drawbacks are: • Fractures can occur both in the appliance itself and in the support system, • Tendency to produce fatigue in the springs, • Tendency of the patient to chew on the appliance, • Wide mouth opening is not possible, • Curvature of springs accentuates the protuberance of cheeks- unaesthetic.
  • 21. • The intention when they first appeared was for the treatment of Class II, both in malocclusions characterized by a mandibular deficiency as well as in cases where a dental problem predominated. • Later on, their application extended to Class I problems especially when treatment including extraction was foreseen. • The appliance was used as an anchorage reinforcement or even for molar distalization. • The appliance is also used in a reverse type for treatment of Class III malocclusions, as well as in cases of midline discrepancy.
  • 22. • The type of the force exercised by FFFAs is continuous and elastic in nature. The amount of force is variable in accordance with the skeletal pattern of the patient, the type of movement desired and the size of the cusps. • FFFA produces a "headgear" effect on the maxillary dentition due to the intrusive force applied to the maxillary posterior segments and produces an anterior intrusive force on the lower dentition • It can be used to obtain maximum anchorage, holding upper molars back as the upper incisors are retracted
  • 23. Problems encountered • • • • Posterior open bite Posterior cross bite Proclination of lower incisors Not recommended in mixed dentition
  • 24. JASPER JUMPER • Jasper jumper was the first flexible functional appliance. • Introduced in 1987 by Jasper JJ. • Advantage : can be added to existing appliance at any point of time after initial arch alignment is completed. • System is composed of two parts: • force module • anchor units
  • 25. • When the force module is straight it remains passive. • When it is curved the muscles of mastication try to elevate producing a force of 1 to 16 ounces. • This kinetic energy potential energy to be used for clinical effects. • Types of forces produced: • • • • sagittal intrusive Head gear effect Retraction of anterior teeth Dental asymmetries Mandibular advancement
  • 26. THE AMORIC TORSION COILS • This appliance is made up of two springs, one of which slides inside the other. • They are intermaxillary springs without covering and have a simplified application system of rings on the ends. • These rings are fixed to the upper and lower arches with double ligatures. • The force exerted by the appliance is variable in accordance with the fixing points on the arch
  • 27. THE ADJUSTABLE BITE CORRECTOR (ABC) • • • It is assembled by the orthodontist as it is composed of various pieces – caps, closed coil springs, nickel titanium wire. It can be used on either side of the mouth with a simple 180º rotation of the lower end cap to change its orientation. In the center lumen of the spring a nickel titanium wire which is responsible for the "push" force generated.
  • 28. THE SCANDEE TUBULAR JUMPER • • • This is a coated intermaxillary torsion spring sold in a kit which includes the spring, the covering, the connectors, the ballpins and the glue. There is no distinction between left and right. The orthodontist constructs the appliance, cutting the spring to the length seeing fit.
  • 29. THE KLAPPER SUPER SPRING • Flexible spring element which is attached between the maxillary molar and the mandibular canine . • The length of the element causes it to rest in the vestibule when activated. This facilitates hygiene and avoids occlusal surfaces. The ends (fixing points) are different: • The open helical loop of the spring is twisted like a J-hook onto the mandibular archwire. • On the maxillary end it is attached to the standard headgear tube (Super Spring I) or to a special oval tube and secured with a stainless steel ligature (Super Spring II). • This new version prevents any lateral movement of the spring in the vestibule.
  • 30. THE BITE FIXER • • • This is a new intermaxillary spring coil. The spring is attached and crimped to the end fitting to prevent breakage between the spring and the end fitting. Polyurethane tubing is inside the spring to prevent it from becoming a food
  • 31. THE CHURRO JUMPER • • • • • This is an inexpensive alternative force system for the anteroposterior correction of Class II and Class III malocclusions. The mesial and distal end of the jumper are circles. The distal circle is attached to the maxillary molars by a pin and the mesial end is placed over the mandibular archwire against the canine bracket. This is the only flexible functional appliance which can be made up by the orthodontist in his lab. The costs are reduced and the time spent is minimal
  • 33. RIGID FIXED FUNCTIONAL APPLIANCES • These appliances have two distinct differences in relation to FFFAs: • RFFAs do not easily fracture but neither do they have elasticity or flexibility. • After fitting and activation they do not allow the patient to close in centric relation. This means that the mandible is in a forward position 24 hours a day creating greater stimulus for mandibular growth than with FFFAs • The working is based on telescopic mechanism which encourages forward re positioning of the lower jaw as the patient in to occlusion.
  • 34. HERBST APPLIANCE • The Herbst appliance was first described by Emil Herbst in 1905 at the Berlin Dental Congress. After that very little was written on this appliance until the end of the seventies when Hans Pancherz brought it back into discussion with the publication of a series of articles. • The Herbst appliance consists of two tubes, two plungers, axles and screws.
  • 35. The original device is a banded Herbst design. The Herbst appliance has undergone some changes in its original design but since the seventies has maintained its general shape with only a few modifications taking place with regard to methods of application (Type I, II and IV). Type I Type II Type IV
  • 36. HERBST TYPE I • Type I is characterized by a fixing system to the crowns or bands through the use of screws. • This is the most common form. • Necessary to weld the axles to the bands or crowns and then fix the tubes and plungers with the screws
  • 37. HERBST TYPE II Fixing system - directly onto the archwires through the use of screws. • Disadvantage:causes constant fractures in the archwires. • The lack of flexibility together with the difficulty in lateral movements and the stress placed on the archwires -causes fractures, especially in the lower arch •
  • 38. HERBST TYPE IV Fixation system- ball attachment, allows greater flexibility and freedom of mandibular movement. • disadvantage: needs brakes to stabilize the joint. • The brakes are small and sometime difficult to fit. • When a fracture occurs or a brake is lost, the appliance comes loose •
  • 39. HERBST APPLIANCE DESIGN • Banded herbst design • Stainless steel crown • Acrylic splint design
  • 40. BANDED HERBST DESIGN • The current version incorporates additional anchorage units of original design of Pancherz. • Bands on all first premolars and first molars. • Buccal and lingual wires connect these. • 0.040 or 0.051” wire form support wire , soldered on both sides
  • 41. STAINLESS STEEL CROWN HERBST DESIGN • Original design has SS crowns on upper first molars to which pivots are soldered tom secure maxillary tubes. • Transpalatal arch or hyrax is placed to increase the rigidity • Type I design of Smith- bands on lower I molars that connect SS crowns to each other by 0.045” SS lingual wire. • Type II design of Smith- cantilever herbst. Hs mandibular extension arms that are anchored to SS crowns on the lower I molars.
  • 42. ACRYLIC SPLINT HERBST • Has a wire frame work on which 2.5 to 3 mm Biocryl is adapted. • Splint can be : bonded or removable • Removable- from canine to I molar. • Boded- labial surfaces of canine not covered with acrylic.
  • 44. The mechanism of class II correction in herbst appliance treatment – A Cephalometric investigation Hans Pancherz – AJO 1982 • Sagittal skeletal and dental changes contributing to class II correction in Herbst treatment were evaluated quantitatively on lateral roentgenograms. • Study consisted of 42 cases, 22 treated with Herbst appliance for 6 months and others served as controls. • Results : 1) Bite jumping with the herbst appliance resulted in class I occlusal relationships in all treated cases. • 2) The improvement in occlusal relationships was about equally a result of skeletal and dental changes.
  • 45. •3) Class II molar correction was mainly the result of an increase in mandibular length, distal movement of the upper molars, and mesial movement of the lower molars. •4) Over jet correction was mainly the result of an increase in mandibular length and mesial movement of the lower incisor. •5) The restraining effect of treatment on maxillary growth, distal movement of maxillary incisors, and anterior condylar displacement was of minor importance for the improvement in occlusal relationship seen. •6) A direct relationship existed between the amount of bite jumping at the start of treatment and the treatment effects on occlusion and on mandibular growth.
  • 46. BSSO Vs. Herbst – Ruf and Pancherz AJO Aug’04 Study assessed the extent of adult Herbst treatment as an alternative to orthognathic surgery by comparing the dento-skeletal treatment effects. ∀ • In surgical group the improvement in sagittal occlusion was achieved by skeletal more than dental changes, in the Herbst group, the opposite was the case. ∀ • The success and predictability of Herbst treatment for occlusal correction was as high as surgery. ∀ • Herbst treatment can be considered an alternative to orthognathic surgery in border like adult class II MO, especially when a great facial improvement is not the treatment goal. •
  • 47. Cephalometric comparison of treatment with Twin Block and SS Crown Herbst application followed by fixed application therapy. (AJO July 2004) • Study compared the effects of two treatment protocols for correcting class II disharmony. ∀ • Very similar therapeutic modifications were produced though twin block group exhibited almost 2 mm greater correction of the maxillo-mandibular differential than did the crown Herbst group. ∀ • The treatment effects of both protocols led to a normalization of dentoskeletal parameters at the end of overall treatment period. • Over all, only minor differences were detected in the treatment and post treatment effects of compliance-free (crown Herbst) and non compliance-free application for correcting class II disharmony
  • 48. TMJ growth changes in hyper- and hypo- divergent Herbst subjects. Pancherz AJO August 2004 • Long term study assessed the amount and direction of glenoid fossa displacement, condylar growth and “effective” TMJ changes = sum of glenoid fossa displacement, condylar growth and condylar position changes in fossa) in 3 vertical facial types group class II div 1 treated with Herbst. • The amount and direction of TMJ growth changes were only temporarily affected favorably in the sagittal direction of Herbst treatment. • For glenoid fossa displacement changes, no differences existed between hyper and hypo subjects at examination period.
  • 49. Effectiveness of treatment of class II MO with the Herbst or Twin Block appliances AJO 2004 Kevin o’ Brien et al • Study evaluated the effectiveness of Herbst and Twin – block appliances for established class II div 1 malocclusion. • A total of 215 patients were randomized to receive treatment with either the Herbst or the twin block appliance. Study concluded that : • Patient cooperation with the Herbst application better than that with the twin block. • Phase I treatment is more rapid with the Herbst application, but overall duration of treatment is similar to that with the twin block.
  • 50. • The Herbst application is prone to debonding and component breakage. • There are no differences in the dental and skeletal effects of treatment between the 2 appliances. • Marked sex effect -girls responded treatment better than boys.
  • 51. Treatment and post- treatment effects of acrylic splint herbst appliance therapy AJO 1999 lorenzo Franchi and Mc Namara Evaluated the skeletal and dentoalveolar changes induced by acrylic splint Herbst therapy of 55 subjects with class II MO treated with Herbst followed by comprehensive edgewise therapy. • Treatment effects were mostly skeletal in nature and are due to changes in mandibular sagittal position and in mandibular dimension. • An important component in molar relationship and overjet correction was the mesial most of mandibular dental arch. • The amount of relapse during post treatment period is ascribed mainly to mesial involvement of maxillary molars. •
  • 52. Step wise advancement using fixed functional appliances Rabie Semi. Orthod 2003 • • • • • • Studied the pattern of bone formation in the TMJ in response to the step wise advancement compared to single step advancement with FFA’s. 250, 35-day old female spraue-dawley rats were randomized in to 20 experimental and 10 control groups. Results: during the first advancement, bone formation in the condyle and glenoid fossa was less than that of one-step advancement. In response to second advancement, new bone formation was significantly higher than with single advancement. Concluded : step wise advancement produced more skeletal effects than single advancement. More prominent effect seen with step wise advancement in glenoid fossa.
  • 53. CANTILEVER BITE JUMPER • • • • It is a Herbst style appliance fitted directly to the lower molar bands through a cantilever arm. Crowns have to be fitted to the upper and lower molars. Disadvantage -thickness of the screw mechanism can impinge on the patient’s cheek The parts are available in kit form with pre-welded screw mechanisms and cantilever arms on crowns of seven different sizes.
  • 54. MALU HERBST APPLIANCE • It consists of two tubes, two plungers, two upper "Mobee" hinges with ball pins and two lower key hinges with brass pins. • Advantages -lower cost, no laboratory needed, flexibility and the possibility of using combined with edgewise therapy
  • 55. •Each upper Mobee hinge is inserted into the hole at the end of the MALU tube and secured to the first molar headgear tube with ball pin. •Each lower key hinge is inserted into the hole at the end of the plunger and locked to the base arch, distal to the cuspid, with the brass pin.
  • 56. FLIP- LOCK HERBST APPLIANCE • • • • This is the third generation of ball-joint Herbst appliances available from this company. The first generation was made from a dense polysulfone plastic but breakage occurred because of the forces generated within the ball-joint attachment. The second generationplastic replaced with metal. Advantage: thin and small.
  • 57. THE MANDIBULAR PROTRACTION APPLIANCE • Filho developed in 1995 • Advantages- ease of manufacture, low cost, infrequent breakage, patient comfort and rapid fitting. • can be made up orthodontist
  • 58. THE VENTERAL TELESCOPE • This was the first telescopic RFFA that appeared as a single unit; i.e. upon reaching maximum opening it does not come apart • Available in two sizes and fixing is achieved • through ball attachments. • easy to activate-unscrewing the tube allows activation of around 3 mm.
  • 59. •Disadvantages quite thick , suffers from •fractures to the brake which stabilizes the joint. •Great accuracy is necessary with inclination and the welding of components
  • 60. THE MAGNETIC TELESCOPIC DEVICE • Consists of two tubes and two plungers with a semicircular section and with NdFeB magnets placed in such a manner that a repelling force is exerted. Fitting is achieved by using the MALU system. • Advantage: linking a magnetic field to the functional appliance. • Disadvantages: thickness, the laboratory work necessary to prepare it and the covering of the magnets
  • 61. THE MANDIBULAR PROTRACTION APPLIANCE • Filho developed in 1995 • Advantages- ease of manufacture, low cost, infrequent breakage, patient comfort and rapid fitting. • can be made up orthodontist
  • 63. MPA I • MPA I – each side made by bending a small loop at a right angle to the end of an .032" SS wire. • The length of the appliance is determined by protruding the mandible and another small right-angle circle is then bent in an opposite direction. • The appliance slides distally along the mandibular arch wire and mesially along the maxillary arch wire. • Bicuspid brackets must be debonded. • Limited mouth opening is the major disadvantage.
  • 64. MPA II • MPA II – made by making right-angles circles in two pieces of .032" SS wire. • A small piece of slipped coil is slipped over one of the wires. • One end of each wire is then inserted through the loop in the other wire. • This version allows the mouth to open wider than the first version.
  • 65. MPA III • MPA III – eliminates much of the arch wire stress that occurs with the MPA I and II. • It permits a greater range of jaw movement while keeping the mandible in a protruded position. • It is adaptable to either Class II or Class III malocclusions.
  • 66. UNIVERSAL BITE JUMPER • Its like a Herbst but is smaller in size and more versatile • It can be used in all phases of treatment in mixed or permanent dentition, Class II or III malocclusions • It is fitted in the patient’s mouth and cut to the appropriate length for the desired mandibular advancement. • Activations are made by crimping 2-4 mm splint bushings onto the rods. UBJs with nickel titanium coil springs do not need to be reactivated.
  • 67. THE BIOPEDIC APPLIANCE • Engaged on the maxillary and mandibular molars, using a cantilever like system, then attached to a BioPedic buccal tube. • Activation by sliding the appliance along the buccal tube and fixing the screw. • Universally sized for left and right sides. • Two pivots on the ends allow the appliance.
  • 68. THE MANDIBULAR ANTERIOR REPOSITIONING APPLIANCE(MARA) • Created by Douglas Toll of Germany in 1991. • It consists of cams on the molars which is guided the patient to bite into class I • Indication: skeletal class II with mandibular deficiency • Contra indications: dolicofacial, root resorption, dental and skeletal open bites, high mandibular plane angle
  • 69. IST -APPLIANCE • • • • The Intraoral Snoring-Therapy Appliance is a new device designed by Hinz, to treat patients who suffer from breathing problems during sleep. Suppresses snoring by moving the lower jaw forward reducing the obstruction in the pharyngeal area Advantage:orthodontist can change the protrusion on each side up to 8 mm An end stop in the guiding sleeve prevents the telescope from disengaging
  • 70. THE RITTO APPLIANCE • Ritto A K in 1998 • Miniaturized telescopic device with simplified intra oral application and activation • Initial wear of splint with bite block for 15 days to 1 month • There is posterior contact after advancement of mandible
  • 71. Hybrid fixed functional appliances
  • 72. HYBRID APPLIANCES • They classified as hybrid appliances because they represent the combination of a rigid fixed functional appliance (RFFA) with flexible fixed functional appliance (FFFA). • They could be described as rigid appliances with coil spring-type systems. • Objective is to move the teeth by applying 24-hour elastic continuous force that would replace the traditional use of elastics and extra-oral force.
  • 73. •Common feature- use of coiled springs to produce force. The force generated varies between 150 and 200 gm. • Advantages -reduction in the need for patient cooperation and the ease of placement.
  • 74. THE CALIBRATED FORCE MODULE Fixed appliance designed to substitute Class II elastics • Developed in 1988 by the CorMar Inc. • Applied to the inferior arch close to the molars and fixed by a screw, and mesial or distal to upper cuspids, and also fixed to the arch. • Its coil spring produced a force between 150 and 200 gm •
  • 75. EUREKA SPRING • Developed by DeVicenzo and Steve Prins. • It is a three part telescopic appliance fixed to the upper arch at the level of the molar band and to the lower arch distal to the cuspid. • The appliance has an open coil spring that is placed inside of a part of the system. • The placement is simple
  • 76. THE TWIN FORCE BITE CORRECTOR • • • • • Consists of two joint telescopic systems and two internal coil springs. At the superior level, fixed with a ball pin that is fitted into the buccal tube of a molar band. Lower arch involves a fitting-in system that is fixed with a screw to the inferior arch and placed distal to the lower cuspid. Available in two sizes. Drawback :difficulty to control the force.
  • 77. FORSUS- FATIGUE RESISTANT DEVICE • An innovative three telescopic appliance with a coil spring in its exterior part. • Advantage lies in coil spring resistance to breaking. • The coil spring is applied by its sliding on a rigid surface avoiding in this way angulations at the fixing points. • It is sold in kits that include different length sizes for left and right side
  • 78. THE FORSUS NITINOL FLAT SRING • • • The Forsus Nitinol Flat Spring is slim, flat and made of Super-Elastic Nitinol. Nitinol is always at work, delivering consistent forces Requires no laboratory setup, making chairside installation quick and easy. • Available in three different bypass designs, accommodate a variety of molar attachments • Force levels remain constant from the initial setup to the time of removal. The result is faster, more efficient treatment.
  • 79. • Study evaluated the clinical application of forsus spring , treated 13 patients with class II malocclusion. • It was found that the saggital correction improved by ¾ cusp width to the mesial on both sides as a result of distal movement of upper molars and mesial movement of lower molars. • Retrusion of of upper and protrusion of lower incisors , reduced over jet by 4.6mm and over bite by 1.2mm • Two- thirds of adolescent patients found Forsus spring more comfortable
  • 80. ALPERN CLASS II CLOSERS • • • • • • This appliance is most recent. It is predominantly applied in Class II correction and as a substitute for elastics. It consists of a small telescopic appliance with an interior coil spring and two hooks for fixing It functions in the same way as elastics and, similarly, is fixed to the lower molar and to the upper cuspid. It is available in three different sizes. Its telescopic action enables a comfortable opening of the mouth.
  • 81. Theories of condylar growth Can we aid in the growth of condyle to a clinically significant degree ?
  • 82. Genetic theory • Suggests that condyle is under strong genetic control, like an epiphysis that causes the entire mandible to grow downward and forward. • More related to prenatal development of condyle. • Questions the effectiveness of orthopedic appliances in condylar growth as proposed by Brodie.
  • 83. Lateral pterygoid hyperactivity hypothesis • By Charles et al, Petrovic and Later espoused by McNamara. • Earliest available acute and blind EMG monitoring technique, suggested that hyperactivity of the lateral pterygoid promotes condylar growth. • Anatomic research has not found evidence that significant attachments exist.
  • 84. 3 d perspective of primate TMJ –advanced downward and forward LPM tendon is observed attaching to the anterior border of the fibrous capsule. • Recently, permanent implanted longitudinal muscle monitoring techniques have found that condylar growth is actually related to decreased postural and functional LPM activity. ∀•
  • 85. Functional matrix theory • Postulates that the principal control of bone growth is not the bone growth is not the bone itself, but rather the growth of soft tissues directly associated with it. • · Validity is questioned as it lacks explanation of specific mechanism by which condyle is stimulated to grow.
  • 86. Enlow and Hans suggested that mandibular growth ↓ Composite of regional forces and functional agents of growth control ↓ Specific extracondylar activating signals ↓ Formation of the growth relativity hypothesis
  • 87. Growth relativity hypothesis Growth relatively refers to growth that is relative to the displaced condyles from actively relocating fossa.
  • 88. Three main foundations: • The glenoid fossa promotes condylar growth with the use of orthopedic mandibular advancement therapy. • Initially, displacement effects the fibro cartilaginous lining in the glenoid fossa to induce bone formation locally ; followed by the stretch of non muscular viscoelastic tissues. • New bone formation at some distance from the actual retrodiskal tissue attachment in the fossa.
  • 89. I -foundation The glenoid fossa promotes condylar growth with the use of orthopedic mandibular advancement therapy.
  • 90. II - foundation • Initially, displacement effects the fibro cartilaginous lining in the glenoid fossa to induce bone formation locally ; followed by the stretch of non muscular viscoelastic tissues
  • 91. III - foundation New bone formation at some distance from the actual retrodiskal tissue attachment in the fossa.
  • 92.
  • 93. Three growth stimuli Displacement + visco elasticity + referred force • Modification first occurs as a result of action of anterior orthopedic displacement. • Condyle is affected by the posterior viscoelastic tissues anchored between the glenoid fossa and the condyle inserting directly into the condylar fibro cartilage. • Displacement and visco elasticity further stimulate normal condylar growth by transduction of forces over fibro cartilage cap of the condylar head.
  • 94.
  • 95. Clinical implications of viscoelasticity Useful for dento alveolar changes using condylar displacement and viscoelastic to tissue forces. • Antero-posterior and vertical changes also occur by differential eruption of the dentition. • Key element in using propulsive orthopedic appliances is to avoid compression of condyle against the eminence. •
  • 96. • Compression is associated with reduced condylar growth, TMD, osteoarthritic changes, condylar flattening in preadolescent herbst patients. •To prevent these, herbst appliance can be used with a posterior bite block and in combination with a rapid maxillary expander
  • 97. Factors controlling C_GF modification 6 factors: • Skeletal(displacement) • Dental • Neuromuscular • Nonmuscular viscoelastic tissues • Biodynamic intrinsic and extrinsic factors • Maturational age
  • 98. Condylar light bulb analogy
  • 99.
  • 100. Skeletal effects of bite jumping therapy
  • 101. • The fundamental principle for all bite jumping functional appliance is to keep the mandible in protrusive position in an attempt to evoke condylar and then mandibular growth, which in turn consolidates the repositioned mandible. • · The fixed functional appliance have mainly two clinical advantages : • The coil-spring mechanism by using superior quality of NiTi alloy secures a forcible advancement of the mandible with sufficient flexibility of mandibular functional movement. • Direct and easy placement of appliance
  • 102. On TMJ and mandibular growth • During normal growth, the mandible is translated downward and forward as the actual growth occurs at the mandibular condyle and along the posterior surface of ramus. • The body of the mandible grows longer by periosteal apposition of bone on its posterior surface. • The ramus grows higher by endochondral replacement at the condyle. • Together with the remodeling of glenoid fossa straight down and posteriorly.
  • 103. • When the mandible is held in a forward position by functional appliance, the condyle is brought downward and forward from its original position. • The ligaments of the disc attaching to the posterior aspects of both condyle and the glenoid fossa are stretched and affect the tissue involved.
  • 104. •It has been shown that the proliferation of chondrocytes in condylar cartilage increases and the bone deposition in posterior of glenoid fossa is evident. • The Mesenchymal cell within the articular layer of both condyle and glenoid fossa are main source for bone formation. •Rabie et al found Mesenchymal cells to be stretched and oriented in the direction of the pull, which might trigger the bio physiological path of Mesenchymal cells differentiating into bone making cells in TMJ.
  • 105. • The key difference in mode of bite jumping between removable and fixed application lie in the duration of mandibular protrusion and the magnitude of vertical bite opening. In fixed appliances, the continuation of bite jumping is secured but the dimension in vertical bite opening is limited. • The Herbst application has been shown to enhance mandibular growth. It accelerates the growth of the condyles and result in a change in the growth direction of the condyles, mostly into a more sagittal direction. • Saggital condylar growth was increased white vertical condylar growth was unaffected by Herbst application therapy which in contrast to removable application.
  • 106. Effects related to treatment timing • The pattern of the mandibular growth curve follows that of the general growth curve. • Mandibular growth is characterized by an adolescent growth spurt and its peak closely coincides with that of the maxilla and general growth. • The pubertal growth period is most favorable time to attack many orthodontic problems with skeletal manifestation when correction of the malocclusion has been achieved, the patient would reach the rate adolescent growth period in which growth rate would slowdown
  • 107. •Unlike removable application, fixed application imposes a short treatment time of 6-12 months, which leads to, considerable flexibility in the selection of treatment time. •On a short-term basis, the most favorable time to treatment patient with Herbst application is at or just after the peak of pubertal growth spurt, as at this time influence of mandibular condylar growth is greatest and risk of undesirable dental effects on the mandible is small.
  • 108. • Taking into consideration other factors, such as the long term stability of treatment results and efficiency of retention, the ideal period is when permanent dentition stage has been reached; at / just after peak height velocity of growth. •The major difference in mandibular treatment changes during various growth periods is because of the variations in basic mandibular growth rate. •At long-term follow-up there seems to be no difference in length of the mandible between patients treated in different growth periods
  • 109. Effects related to post treatment follow -up • Significant enhancement of mandibular growth occurs during the initial treatment phase, but return to their pretreatment pattern after treatment on short term basis. • Long term studies show that the mandible effects remained and reason for relapse was the change in tooth position. The unfavorable post treatment changes occurring after the removal of application are dominantly appliance related.
  • 110. TREATMENT TIMING , IDEAL PERIOD AND OUTCOME • How efficient is early class II treatment compared to later treatment? • Study at the University of Giensen defined treatment efficiency as a better result in a shorter treatment time. • Late treatment of class II treatment was more efficient than treatment with removable appliances
  • 111. IDEAL PERIOD FOR HERBST APPLIANCE • Permanent dentition at or just after the pubertal peak of growth corresponding to stages FG to H of the middle phalanx of third finger
  • 112. CONCLUSION From 1900’s when the fixed functional appliances first appeared , to date, a number of fixed functional appliances have been developed and gained popularity. Fixed functional appliances are called “Noncompliance Class II correctors” giving a false idea about the co-operation necessary during treatment . Understanding mechanisms of action of these appliances is critical to orthodontist
  • 113. References • Dento facial orthopedics with functional appliance- Graber, Rakosi and Petrovic • Orthodontics and dentofacial orthopedics-McNamara • Contemporary Orthodontics-proffit • The Herbst appliance-Semi. Orthod2002 • Voudouris et al. AJO 2003;123:604-13. • Voudouris et al. AJO 2000;117:247-66. • McSherry P F BJO 200;27:219-25 • Ritto AK func. orthod.;1999: 16, 122-35. • Voudouris et al. AJO 2003;123:13-29
  • 114. • •Shin . crania fac res. 2005;8:2-10. •Pancherz A O 1997;67:111-20. •Pancherz A JO 1979;76:423-42. •Jasper JJ AJO 1995;108:641-50. •Filho JCO 1998;32:379-84. •Pancherz A JO 2002;121:559. •Frankel AJO 2001;120:17(a).
  • 115. THANK YOU Leader in continuing dental education