Evolution of Functional Appliances

04/11/2023Functional appliances- I1

A VERY GOOD AFTERNOON


Evolution Of Functional Appliances.


Introduction

Orthodontics presents a philosophical challenge in that both art and science are of equal importance. A quotation of Edward Angle(1907), from the turn of the 2oth century, is still pertinent today:

“The study of orthodontia is indissolubly connected with that of art as related to the human face. The mouth is a most potent factor in making the beauty and character of the face, and the form and beauty of the mouth largely depend on the occlusal relations of the teeth.

Our duties as orthodontists force upon us great responsibilities and there is nothing which the student of orthodontia should be more keenly interested than in art generally, and especially in its relation to the human face, for each of his efforts, whether he realizes it or not, makes for beauty or ugliness, for harmony or inharmony, for perfection or deformity of the face. Hence it should be one of his life studies.”

April 11, 2023Functional appliances- I4

Orthodontics & Dentofacial Orthopaedics

An essential distinction exists between the terms ‘Orthodontics’ and ‘Dental orthopaedics’. They represent a fundamental variance in approach to the correction of dentofacial abnormalities.

By definition, orthodontic treatment aims to correct the dental irregularity.

The alternative term ‘dental orthopaedics’ was suggested by the late Sir Norman Bennett. The broader description of ‘dental orthopeadics’ conveys the concept that treatment aims to improve not only dental and orthopaedic relationships in the stomatognathic system but also facial balance.


A fundamental question that we must address in diagnosis is: ‘does this patient require orthodontic treatment or orthopaedic treatment ,or a combination of both and to what degree?”

alternatively, does the patient require dentofacial surgery, or to what extent can orthopaedic treatment be considered as an alternative to surgery?


If the malocclusion is primarily related to a musculoskeletal discrepancy we should select an orthopaedic approach to treatment.

It is in the treatment of muscle imbalance and skeletal disproporation that functional orthopaedic appliances come into use.

Functional appliances were developed to correct the abrrent muscle environment- the jaw- to – jaw relationship – and as a result restore facial balance by improving function, to achieve the best of both worlds it is necessary to combine the fixed and functional appliance therapy.


Orthodontic Force

Fixed appliance are designed to apply light orthodontic forces that move individual teeth. Schwarz (1932) defined the optimum orthodontic force as 28g per square centimeter of root surface. By applying light forces with archwires and elasticity traction, fixed appliances do not specifically stimulate mandibular growth during treatment.

A bracket or ‘small handle’ is attached to individual teeth. Pressure is then applied to those teeth by tightening light wires to the brackets. The resulting forces applied through the teeth to the supporting alveolar bone must remain within the level of physiological tolerance of the periodontal membrane to avoid damage to the individual teeth and/or their sockets of alveolar bone.


Orthopaedic Force Orthopaedic force levels are not confined by the level of tolerance

of the periodontal membrane but rather by the much broader tolerance of the orofacial musculature. An orthopaedic approach to treatment is not designed to move the teeth , but rather to change jaw position and thereby correct the relationship of the mandible to the maxilla.

The forces of occlusion applied to opposing teeth in mastication are in the range of 400-500 g and these forces are transmitted through the teeth to the supporting bone. Occlusal forces form a major proprioceptive stimulus to growth whereby the internal and external structure of supporting bone is remodelled to meet the needs of occlusal function. This is effected by reorganization of the alveolar trabecular system and by periostal and endochondral apposition.


Functional appliance by definition is one that changes the posture of the mandible, holding it open or open and forward. Pressure created by stretch of the muscles and soft tissues are transmitted to the dental and skeletal structures, moving teeth and modifying growth.

The monobloc developed by Robin in the early 1900s is generally considered the forerunner of all functional appliances, but the activator developed in Norway by Andresen in the 1920s was the first functional appliance to be widely accepted.


The American And European Controversy

In the United States, the original removable appliances were rather clumsy combinations of vulcanite bases and precious metal or nickel-silver wires.

In the early 1900s George Crozat developed a removable appliance fabricated entirely of precious metal that is still used occasionally. The appliance consisted of an effective clasp for first molar teeth, heavy gold wires as a framework, and lighter gold finger springs to produce the desired tooth movement.


The Crozat appliance attracted a small but devoted following, and still is used by some practitioners for comprehensive treatment. Its limitation is that, like almost all removables, it produces mostly tipping of teeth. It had little impact on the mainstream of American orthodontic thought and practice, however, which from the beginning was focused on fixed appliances.

Crozat appliance


For a variety of reasons development of removable appliances continued in Europe despite their neglect in the United States. There were three major reasons for this trend:

(1)Angle's dogmatic approach to occlusion, with its emphasis on precise positioning of each tooth, had less impact in Europe than in the United States;

(2) Social welfare systems developed much more rapidly in Europe, which tended to place the emphasis on limited orthodontic treatment for and contemporary orthodontic appliances large numbers of people, often delivered by general practitioners rather than orthodontic specialists and

(3) Precious metal for fixed appliances was less available in Europe, both as a consequence of the social systems and because the use of precious metal in dentistry was banned in Nazi Germany.


This forced German orthodontists to focus on removable appliances that could be made with available materials. (Precision steel attachments were not available until long after World War II; fixed appliances required precious metal.)

The interesting result was that in the 1925 to 1965 era, American orthodontics was based almost exclusively on the Use of fixed appliances (partial or complete banding), while fixed appliances were essentially unknown in Europe and all treatment was done with removables, not only for growth guidance but also for tooth movement of all types. A major part of European removable appliance orthodontics of this period was functional appliances for guidance of growth.


In the European approach at that time, removable appliances often were differentiated into "activators," or functional appliances aimed at modifying growth, and "active plates" aimed at moving teeth. In addition to the functional appliance pioneers, two European orthodontists deserve special mention for their contributions to removable appliance techniques for moving teeth. Martin Schwartz in Vienna developed and publicized a variety of "split plate" appliances, which could produce most types of tooth movements.

Philip Adams in Belfast modified the arrowhead clasp favored by Schwartz into the Adams crib, which became the basis for English removable appliances and is still the most effective clasp for orthodontic purposes.

Martin Schwarz


Functional appliances were introduced into American orthodontics in the 1960s

• Through the influence of orthodontic faculty members with a background in Europe (of whom Egil Harvold was prominent),

• And later from personal contact by a number of American orthodontists with their European counterparts. (Fixed appliances spread to Europe at the same time through similar personal contacts.)

A major boost to functional appliance treatment in the United States came from the publication of animal experiment Results in the 1970s showing that skeletal Changes really could be produced by posturing the mandible to a new position and holding out the possibility that true stimulation of mandibular growth could be achieved.


At this point, the controversy between European and American orthodontics has largely disappeared. European style removable appliances particularly for growth modification during first-stage mixed dentition treatment, have become widely used in the United States while fixed appliances have largely replaced removables for comprehensive treatment in European elsewhere throughout the world.

Modern removable appliance therapy consists largely of the use of

(1) various types of functional appliances for growth guidance in adolescent and, less frequently, in children;

(2) active plates for tooth movement in preadolescents;

(3) clear plastic aligners for tooth movement in adults.


For many years, the exclusive province of dentofacial orthopedics was Europe, while North America was firmly rooted in Angle’s fixed appliance philosophy, yet it was Norman W. Kingsley who first (1879) used forward positioning of the mandible in orthodontic treatment. Kingsley’s removable plate with molar clasps might be considered the prototype of functional appliances, having a continuous labial wire and a bite plane extending posteriorly. As he described it, “The object was not to protrude the lower teeth, but to change or jump the bite in the case of an excessively retreating lower jaw.”


Edward H. Angle used a pair of interlocking rings, soldered to opposing first molar bands, much along the lines of today’s mandibular anterior repositioning appliance (Fig 1), to force the mandible forward.

Edward H. Angle

Fig 1


As a result of studies on a dolphin’s tail fin, Wilhelm Roux is credited as the first to study the influences of natural forces and functional stimulation on form (1883) (Wolff’s law).

His work became the foundation of both general orthopedic and functional dental orthopedic principles.

Later, Karl Häupl saw the potential of Roux’s hypothesis and explained how functional appliances work through the activity of the orofacial muscles.


The monobloc(1902)

The first practitioner to use functional jaw orthopedics to treat a malocclusion was Pierre Robin (1902). He was a French Stomatologist. He was born in 1867 and died in 1949. He wrote his thesis on role of mastication and follicular sac on eruption of teeth. In 1923 he published first of his 17 articles on the problem of glosooptosis and said that he treated this condition with monobloc which he first described in 1902 and which was used to restore the normal relationship of the maxillae and the mandible.


Pierre Robin syndrome (or sequence) is a condition present at birth, in which the infant has a smaller-than-normal lower jaw, a tongue that falls back in the throat, and difficulty breathing. Robin sequence (RS), previously known as Pierre Robin syndrome.

Fig: these are two illustration from the monograph by Dr Pierre robin


This syndrome consists of the following 3 essential components:

Micrognathia or retrognathia

Cleft palate (usually U-shaped, but V-shape also possible)

Glossoptosis, often accompanied by airway obstruction: The tongue is not actually larger than normal, but because of the small mandible, the tongue is large for the airway and therefore causes obstruction. Rarely, the tongue is smaller than normal.


Until 1974, the triad was known as Pierre Robin syndrome; however, the term syndrome is now reserved for those errors of morphogenesis with the simultaneous presence of multiple anomalies caused by a single etiology. The term sequence has been introduced to include any condition that includes a series of anomalies caused by a cascade of events initiated by a single malformation.

It extended all along the lingual surfaces of the mandibular teeth, but it had sharp lingual imprints of the crown surfaces of both maxillary and mandibular teeth. It incorporated and expansion screw in the palate to expand the dental arches

Treatment would obviously require a total body approach, to include psychological support, muscular and breathing exercises, and lip closure, with the monobloc indicated to stimulate the activity of the facial musculature and to normalize the occlusion.


Myofunctional Therapy(1906)

Alfred P. Rogers (1873-1959; Angle School, 1903),sometimes called the father of myofunctional therapy, also recognized the importance of the whole orofacial system.

Rogers grew up on the shores of Canada’s Bay of Fundy and developed a lifelong interest in nature and conservationism.

He was the first orthodontist in New England to limit his practice(1906).

In addition, he was a strong proponent of the total-child approach and advocated muscular exercises to improve neck, head, and tongue posture and encourage nose breathing.


ACTIVATOR(1908) Viggo Andresen of Norway was familiar with the

writings of American author Norman Kingsley.

Also on Andresen’s bookshelf was a favorite of his, the orthodontic textbook of Benno Lischer, published in 1912. One conclusion to be drawn from Lisher’s theory is that if compensatory, adaptive lip and tongue function could exacerbate excessive overjet in class II- type malocclusions and if abnormal swallowing and prolonged finger- sucking habits could create anterior open bite and narrow maxillary arches, could not the same muscles be used to correct these and other problems?

Viggo Andresen


Impressed with Kingsley’s concepts and appliances . Andresen developed a mobile loose fitting appliance modification that transferred functioning muscle stimuli to the jaws, teeth and supporting tissues. Actually, Andresen was not thinking of “guiding growth” at that time, but only of eliminating the adverse effects of abnormal function. This working hypothesis was tested on his own daughter, who was wearing fixed orthodontic appliances and who was going away to a camp over the summer. Andresen removed the fixed appliances and placed a modified Hawley-type retainer on the maxillary arch. However, he added a lingual horseshoe flange that guided the mandible 3 to 4 mm forward when teeth were brought into maximal closure allowed by the interposed acrylic guide plane. This was done to prevent any relapse over the three month vacation period. On his daughter’s return Andresen was surprised to see that nighttime wearing of the appliance not only had eliminated the abnormal neuromuscular compensation but also had produced a complete sagittal correction and significantly improved the facial profile.


The result was stable. Seeing the continuous improvement with the retainer he called it a biomechanical working retainer. He used it after the removal of fixed orthodontic appliances, not only as a way to stabilize the result achieved but also as a biomechanically functioning appliance, particularly during the summer vacations when the patients were gone for a longer period of time.

When Andresen moved from Denmark to Norway, he became associated with Haupl at the university of Oslo, Haupl, a periodontist and histologist, was impressed with the results obtained by Andresen’s functioning retainer. He was particularly interested in its effect on underlying bone.


By the time Andresen and Haupl teamed up to write an article about their appliance, they called it an ACTIVATOR, because of its ability to activate the muscle forces. The original name Andresen used for this type of treatment was biomechanical orthodontics.

Only later , after teaming up with Karl Haupl and doing further work on concepts and techniques refinements, was the name changed to functional jaw orthopedics’, which was more descriptive.


To much of the world, the treatment became known as the Norwegian system, even though Andresen was a Dane and Haupl a German ( both taught at the dental school in Oslo, Norway). His findings were supported by later researchers.

Andresen and Häupl later collaborated on a textbook (Funktionskieferorthopädie) about their system in1936. Although Häupl’s complete rejection of fixed appliances led the profession astray for a time, had it not been for his promotional efforts, the activator might have languished into unknown.

Karl Häupl’s advocacy of “Norwegian system”was main deterrent preventing Europeans’ acceptingfixed appliances


HERBEST APPLIANCE(1909)

Herbst was far ahead of his time. Much of what we know about orthodontic appliances today was already described by him more than 100 years ago (eg, rapid palatal expansion devices).“ His main contribution to modern orthodontics was, however, the development of the Okklusionsscharnier or Retentionsscharnier (Herbst appliance) Scharnier means joint, and the word retention was added because the upper part of the appliance stowed as a retainer tot an expanded maxillary dental arch by the incorporation of a circumferential palatal platinum-gold arch wire.

At the 5th International Dental Congress Of 1909 In Berlin, Emil Herbst presented a fixed bite-jumping device called Scharnier, or joint. The idea of keeping the mandible forward continuously and eliminating the need for patient compliance, as is required with removable functional appliances, appealed to clinicians. In 1934 Herbst and Martin Schwaz wrote a series of articles describing their case selection, experience, problems and solutions. Patients with retrognathic mandibles and TMJ problems responded best.



But after this, little appeared in literature until the concept was brought back to focus by Hans Pancherz. In 1979, Pancherz’s article in American Journal Of Orthodontics called attenetion to the possible stimulation of mandibular growth. The Herbst appliance can be compared with an artificial joint between the maxiila and mandible. The bilateral telescopic mechanism maintains the protracted position of the mandible, even during function.

Hans Pancherz.


The Bimler Appliance

Just as Andresen’s discovery of the activator was an accidental outgrowth of his retainer, so was Hans Peter Bimler’s (1916-2003) (Fig 4) elastischerGebissformer (elastic bite former) fortuitous development. As a surgeon treating jaw injuries during World War II, Bimler had devised a maxillary splint for a patient who had lost his left gonial angle. The splint provided a guide into which the patient could insert the remainder of his mandible. Hans Bimler got his

inspiration for Gebissformeras World War II army surgeon.


In so doing, however, the pull of scar tissue led to a slight widening of the maxillary arch. Bimler reasoned that it might be possible to expand the arch by means of crosswise mandibular movements, and the Bimler appliance was born.

After several modifications, the Bimler

appliance achieved its final form in 1949.

Also like Andresen, Bimler was attacked by the functional establishment, in particular Häupl, for his new ideas, but every functional appliance subsequently developed has incorporated atleast 1 of his innovations.


The Double Plate(1956)

Martin Schwarz (1887-1963) began his career as an ear, nose, and throat physician but was diverted into dentistry by famed histologist Bernhard Gottlieb. He became director of Kieferorthopaedia, Vienna Polyclinic, and the jaw orthopedics division of the Viennese government in 1939, where he expanded orthodontic service from 100 to more than 3000 patients.


In 1956, Schwarz attempted to combine the advantages of the activator and the active plate by constructing separate mandibular and maxillary acrylic plates that were designed to occlude with the mandible in a protrusive position. The double plate resembled a monobloc or an activator constructed in 2 pieces.


The Tooth Positioner(1944)

In 1944, Harold D. Kesling (1901-79)developed the tooth positioner. The technique involved taking impressions of a patient nearing completion, denuding the plaster of appliances, and resetting the teeth into ideal positions (the “diagnostic setup”). From the new models, a rubber positioner was made that, if worn enough hours, acted as a finishing appliance. It could also be used as a retainer. Harold D. Kesling,

inventor of tooth positioner.


The Nuk Sauger(late 1940’s)

In the late 1940s, Adolph Mueller, a West German orthodontist, took early treatment to its ultimate when he designed a pacifier to promote development of babies’ jaws and facial muscles.

With a bottle nipple duplicating the shape and texture of a mother’s nipple, this pacifier would better satisfy an infant’s natural sucking desire.

It could also preclude development of the tongue thrust that was believed to result from a baby’s attempt to block the copious flow of milk from conventional nipples.


The Functional Regulator(1957)

Rolf Fränkel (1908-2001) must be recognized as the inventor of an appliance that corrects malocclusions with little or no contact with the dentition. He studied in Leipzig and Marburg, Germany, receiving his Dr MedDent in 1931 but was treating patients in his office at Zwickau with Angle’s E-arch as early as 1928. In World War II, he was a military surgeon involved with jaw and facial injuries.

Recognizing that stability of treatment can occur only if the structural and functional deviations of the muscular system are corrected10,Fränkel designed the function regulator (FR, 1957), making the oral vestibule the operational basis for his treatment.


Rolf Frankel probably did more to interest American orthodontist in functional appliances than any single clinician. His outstanding three dimensional results, the spectacular improvements that have stood the test of time and were done with the highest integrity, showed what can be done with a carefully selected patients, properly designed appliances, and maximal patient compliance.

His impeccably researched clinical results are still the gold standard for all functional appliances, fixed and removable.

The use of buccal shields to screen off potentially narrowing muscle forces and of lip pelots in the lower labial vestibule to prevent abnormal perioral muscle function and lingualizing forces makes eminently good sense


Enlow et al, Moffett, Grabber, and others validate the fact that periosteal pull as created but the frankels buccal shields,, has the potential to stimulate bone growth.

Frankels step wise advancement, so easily achieved by the unique appliance design, has to provide the best and the most stable results,, and they are applicable to other functional appliances.

Of all the functional appliances, the functional regulator is the one that depends most on function, proper fabrication, sufficient length of wear and cooperation.

However, the popularity of the pure functional regulator has waned, not because of questions about the validity of the philosophy, but because of pragmatic use, more demanding laboratory procedures, and compliance demands.


Bionator(1960’s)

The bionator was developed by Balters, is the prototype of less bulky appliance. Its lower portion is narrow and its upper portion has only the labial wire and buccal screening wire extension, plus a stabilizing cross-palatal bar that actually can be adjusted for bilateral expansion if needed. The palate is free for proprioceptive contact by the tongue. The appliance has be worn all the rime except meals, which is critical for maximum response.

Kantorowicz termed the bionator“ the skeleton of an activator from which there is nothing left but naked emobodiment of Robin’s thoughts”.


According to Balter’s, the equilibrium between the tongue and the circumoral buccinators mechanism is responsible for the shape of the arches and intercuspation

Wilhelm Balters (1893-1973)


Other Functional Appliances Of The Early 1960s

In 1952, Hans Mühlemann created the propulsor. Itwas based on the activator, but it lacked the metal elements.

The propulsor was later perfected by Hotz. About a year later, Leopold Petrik(1902-65) introduced an activator having greater occlusal thickness to increase the vertical dimension.

Hugo Stockfisch(1914- ) came out with his kinetor. This device consisted of 2 movable plates connected by wire buccinators loops, which keep muscle pressure away from the cheeks. An unusual feature of the kinetor was the elastic tubes between the 2 plates that acted not only as shock absorbers but also as a means of broadening and optimizing orofacial muscle pressures.


Twin Block(1977)

On 7th September 1977, Dr. William J. Clarks developed Twin blocks.

The twin blocks were a natural progression in the evolution of functional appliance therapy, representing a significant transition from one piece appliance that restricts the normal function to a twin appliance that promotes normal function.

Of all the functional appliances, the bionator and the Clark twin block are the most popular. The successful use of bionator in TMJ disturbances has been documented.


It is true that the necessity is the mother of invention.

Name :- Colin Gove

Age / Sex :- 7yrs 10 months / Male

Chief Complaint :- Luxated upper central incisor

On Examination :- Class II div 1 malocclusion with a 9mm overjet and a midline shift to right.

Treatment :- The tooth was re-implanted but due to class II; lower lip was trapped lingual to the luxated tooth causing mobility and root resorption to prevent this the appliance with a Occlusal plane which could place the mandibular forward into a edge to edge bit was made later a fixed treatment was done. Later the re-implanted tooth was crowned and a stable result was obtained at age of 25 years.

It was seen that the overjet reduced from 9mm to 4mm in 9 months.


Magnetic Appliances(1989)

Blechman, Bondemark and Kurol and Vardimon et al as well as Darendelilier et al and Joho and Darendelilier, have been aware of the potential for using rare earth magnets in orthodontics and dentofacial orthopaedics for some time.

Blechman, the true pioneer , has been involve intimately in the medical and dental use of rare earth magnets. Recent medical research corroborates his observations that static magnet fields may have an electric field effect that potentiates tissue response.

Despite widespread and increasing use of magnetic adjuncts in general orthopedic problems, in vitro orthodontic research has produced mixed results thus far.

May be it’s a question of what to look for?


Heightened blood flow is clearly evident, and the alignment of blood flow is influenced by rare earth magnets,

but the magnitude or character of force, its duration, and whether continuous or intermittent force is applied are questions currently being addressed.


Conclusion

The past 20 years have seen an increasing awareness of the potential of functional appliances as valuable tools in the armamentaria of orthodontists.

An increasing recognition of the interrelationship of form and function, the realization that neuromuscular involvement is vital in treatment, the recognition of the importance of the airway in therapeutic considerations and a growing understanding of head posture and the accomplishments of dentofacial pattern changes are all factors producing rapid growth in use of functional appliances.


Certainly , abnormal and adaptive neuromuscular function can hinder the accomplishments of an optimal dentofacial pattern.

However, the same forces created under control can be used to eliminate morphologic aberrations resulting from abnormal lip trap habits, tongue posture and function, and finger habits that have produced that have produced deviations from the normal growth and development of the stomatognathic system.


One early article in American orthodontic literature, “ the Three Ms’. Muscles , Malformations and Malocclusions,”, by Graber (1963) described the effects of function and malfunction to a mechanistically oriented profession that was at that time treating patients according to numbers gleaned from two dimensional cephalograms.


“Orthodontics is not only the appliance, but which appliances, why, when, and for how long.”


References1. Dentofacial orthopedics with functional appliances. In: Graber TM, Rakosi

T, Petrovic AG, editors. Principles of functional appliances. St Louis: Mosby; 1985.

2. Concepts of functional jaw orthopedics. In: Graber TM, Neumann B, editors. Removable orthodontic appliances. 2nd ed. Philadelphia: Saunders; 1984. p. 87.

3. Moorrees CFA. Orthodontics and dentofacial orthopedics: past, present and future. Part 2. Kieferorthop 1998;12:127-40.

4. Rakosi TR, Graber TM, Petrovic AG. Dentofacial orthopedics with functional appliances. St Louis: Mosby; 1985.

5. Proffit WR, Fields HW, editors. Contemporary orthodontics. 3rded. St Louis: Mosby; 2000.

6. Hotz RP. The changing pattern of European orthodontics. Br JOrthod 1973;1:4-8.

7. Salzmann JA, editor. Practice of orthodontics. Philadelphia:Lippincott; 1966.

8. Bimler B. Hans Peter Bimler at age 85. Int J Orthod 2002;13:19-20.


9. Schmuth GPF. Milestones in the development and practical application of functional appliances. Am J Orthod 1983;84:48-53.

10. McNamara JA Jr. Rolf Fränkel, 1908-2001 (in memoriam). Am J Orthod Dentofacial Orthop 2002;121:238-9. 11. Harold D. Kesling (1901-79) (in memoriam). Am J Orthod 1980;77:574-5.

12. Kesling HD. The philosophy of the tooth positioning appliance. Am J Orthod Oral Surg 1945;31:297-304.

13. Gerber Medical Marketing. Via e-mail. June 20, 2005.

14. Melo ACM, dos Santos Pinto A, da Rosa Martins JC, Martins LP, Sakima MT. Orthopedic and orthodontic components of Class II Division 1 malocclusion correction with Balters bionator. World J Orthod 2003;4:237-42.

15. Levrini A, Favero L. The masters of functional orthodontics. Milan, Italy: Quintessenz Verlag; 2003.

16. Graber TM. Orthodontics: principals and practice. 3rd ed. Philadelphia: Saunders; 1972. p. 699.

17. Norman Walh, Orthodontics in 3 millennia. Chapter 9:Functional appliances to midcentury; AJODO vol 129 page 82


Thank you

Presented by-

Dr Sneh Kalgotra

2nd year post-graduate student.

Education

Evolution of Functional Appliances