History of Amercian Orthodontics 3/2

From Wartime Ingenuity to a Transatlantic Conversation in Orthodontics

Author

Borris Upton
September 15, 2025

Fränkel’s Functional Regulator — East German Precision

In the 1950s and 60s, Rolf Fränkel in East Germany reimagined functional appliance therapy with his Functional Regulator (FR) series. His appliances used wire and acrylic shields placed in the vestibule — outside the dental arches — to train the lips and cheeks to exert healthier forces.

  • FR-II addressed Class II malocclusions by encouraging mandibular growth.

Frännkel II appliance. In: KFO Dr. Dr. Greuner. Herausnehmbare Zahnspangen.

  • FR-III treated Class III by influencing maxillary development.

Frännkel III appliance. In: Der Funktionsregler nach Fränkel Typ FR-3 Teil II

Fränkel’s approach emphasized soft tissue function over direct tooth movement. By altering the “envelope” of oral muscle activity, he aimed for stable skeletal and dental change.

American orthodontists adopted Fränkel’s appliances in the 1970s, often blending them with fixed appliance therapy for comprehensive results.

Clark’s Twin Block — Britain’s Answer to Compliance

In the late 1970s, William Clark of Scotland wanted a functional appliance that patients would actually wear. The result was the Twin Block — two separate acrylic plates (upper and lower) with bite blocks that guided the jaw into a forward position when biting.

The genius was in comfort and usability:

  • Could be worn full-time, even while speaking.

  • Incremental advancement allowed gradual adaptation.

  • Worked well alongside fixed appliances in later treatment phases.

In: Twin-Block

The Twin Block spread rapidly in the UK and, by the 1990s, was embraced in American practices — often for growing Class II patients.

The S-III Appliance (Sander’s Back-Push Double Plate) — Germany’s Answer to Early Class III Therapy

In the 1990s, German orthodontist Franz Günter Sander developed the Rückschubdoppelplatte (S-III appliance) in Ulm as a removable functional device specifically for treating children with early mesial malocclusion (progeny) before the age of nine.

In cases of progene dentofacial development (where the lower jaw is excessively mesially positioned), the S-III appliance guides the mandible posteriorly via interlocking acrylic spurs and adjustable stops, offering a functional alternative to extraoral traction appliances.

Key advantages and features:

  • Designed for early intervention—ideally before age nine—when skeletal adaptation is more feasible.

  • Acts both therapeutically and as a retention device, often well tolerated by patients.

  • Avoids reliance on bulky external devices like face masks or chin-caps.

  • Useful in cases where the maxilla is underdeveloped, rather than conditions with an over-grown mandible.

Diagnostic and prognostic considerations:

  • The individualized ANB angle (based on the patient’s SNA and ML–NSL relationship) is used to assess jaw positions.

  • Prognosis and the success of non-surgical therapy depend on the difference between mandibular and maxillary lengths; in 12-year-olds, a difference of 15–28 mm is considered within the treatable range.

Sander’s Back-Push Double Plate - Effective intraoral correction of dental Class III cases. In: Rückschubdoppelplatte (S-III-Apparatur nach Sander)

Sander’s Back-Push Double Plate. In: Rückschubdoppelplatte (RDP)

The RMR as class III functional treatment option

The removable Mandibular Retractor. In: RMR.

In recent studies, A. Majanni and H. Mohammad Y. demonstrated that bone-anchored intermaxillary elastics offer a promising therapeutic approach for growing Class III patients with mild to moderate skeletal discrepancies, proving comparable or superior to the Reversed Maxillary Retractor (RMR) as a functional treatment option.

Their findings reinforce that both bone-anchored elastics and removable functional appliances represent valid alternatives to the traditional Delaire facemask, expanding the orthodontist's armamentarium for managing Class III malocclusions in young patients.

This evolution toward less invasive, more patient-friendly appliances continues the trajectory established by earlier innovators like Sander, who sought to minimize the psychological burden of conspicuous extraoral devices while maintaining therapeutic efficacy.

The Herbst Appliance — Fixed Functional Origins

While the Activator line developed as a removable tradition, Germany also produced a fixed functional design early in the 20th century.

  • Emil Herbst (1905) introduced a telescoping hinge mechanism fixed to upper and lower molar bands, holding the mandible forward around the clock.

The primordial Herbst-Appliance. In: Das Ur-Herbst-Scharnier

  • Its fixed nature ensured constant wear — eliminating compliance problems.

  • After decades of limited use, Hans Pancherz revived the Herbst in 1979 with clinical studies proving its skeletal and occlusal benefits.

The Herbst’s revival marked a parallel to removable functionals: instead of relying on patient discipline, it used mechanical permanence.

Herbst appliance. In: Therapie der dentalen und skelettalen Klasse II im permanenten Gebiss. Herbst-Apparatur.

Modern Fixed-Functional Hybrids

Today’s orthodontists often combine Herbst principles with contemporary materials and bracket systems. Examples include:

  • MARA (Mandibular Anterior Repositioning Appliance) — Less bulky, allows gradual mandibular advancement.

Mara Appliance. In: Mara Appliance & Thikriat Al-Jewair, Mohammadreza Ghorbaniparvar, Lorenzo Franchi, Carlos Flores-Mir, Comparison of…

  • Jasper Jumper — Flexible push-rods integrated with fixed braces for simultaneous tooth alignment and jaw correction.

Jasper Jumper appliance. In: Treatment effects of the Jasper Jumper and the Bionator associated with fixed appliances. Neves et al.

  • Forsus Fatigue Resistant Device — Spring-based system delivering continuous force without patient activation.

Forsus appliance in situ and model. In: Forsus appliance & Clinical innovation

  • Carrière Motion 3D Class II Appliance — Uses elastic force and minimal bulk to reposition the mandible before braces.

These devices blend skeletal correction with the efficiency of fixed orthodontics, continuing the fixed-functional lineage started by Herbst.

Lingual Orthodontics — Aesthetic Demands Drive Collaboration

While functional appliances influenced jaw growth, another transatlantic exchange was unfolding in the realm of aesthetics. In the 1970s, European orthodontists in France and Germany refined lingual orthodontics — placing brackets on the tongue side of teeth. By the 1980s, American manufacturers and clinicians were adapting the technique for the U.S. market, catering to adult patients seeking discreet treatment.

Lingual braces in situ. In: Lingual braces; two web sources

Removable Plate Appliances — The Parallel European Branch

While the functional appliance tradition focused on jaw growth, another European innovation was evolving: removable plate appliances. Clinicians like G.V. Adams, with his universally adopted clasp design, made retention reliable. In the 1920s and 30s, pioneers such as Schwarz, Stockfisch, and Tränkmann combined stainless steel wire with acrylic plates to create adjustable devices for minor tooth movement, expansion, and retention.

These appliances became the forerunners of the Hawley retainer and modern acrylic-and-wire designs, serving both as post-treatment retention and, in many cases, active correction. Their influence paralleled the functional appliance story and shaped orthodontic correction and retention philosophy on both sides of the Atlantic.

A Century of Cross-Pollination

From Robin’s Monoblock to Clark’s Twin Block, from Crozat’s lightwire elegance to Fränkel’s tissue training, functional appliance design has never belonged to one continent. Each innovation reflected its inventor’s philosophy, but they all shared one goal: to guide growth and function for lasting dental health.
Between 1930 and 1960, American orthodontics shifted from invention to refinement, all while engaging in a lively exchange of ideas with Europe. From Pierre Robin’s airway-saving monoblock to Fränkel’s muscle-training regulators, functional appliances crossed the Atlantic and took on new life in American practices. This period cemented orthodontics as a global conversation.

📍 Functional Appliance Timeline

  • 1900s — Pierre Robin’s Monoblock (France)

  • 1905 — Emil Herbst’s original Herbst appliance (Germany)

  • 1919 — Crozat Appliance (USA)

  • 1920s — Andresen-Häupl Activator (Denmark/Germany)

  • 1930s — Korkhaus Activator refinements (Germany)

  • 1920s–30s — Schwarz, Adams, Stockfisch, Tränkmann removable plates (Europe)

  • 1950s — Wilhelm Balters’ Bionator (Germany)

  • 1950s–60s — Rolf Fränkel Functional Regulators (East Germany)

  • Late 1970s — William Clark’s Twin Block (Scotland)

  • 1979 — Hans Pancherz revives Herbst appliance (Germany)

  • 1980s–Present — MARA, Jasper Jumper, Forsus, Carrière Motion (International)

  • 1980s — Lingual Orthodontics refined (France, Germany → USA)

  • Today — ALF appliance (USA), blending Crozat principles with cranial orthopedics

📚 Sources & References

Primary Historical Sources

  • Robin, P. (1902). Sur la Respiration nasale et ses Malformations. Paris.

  • Andresen, V., & Häupl, K. (1936). Funktions-Kieferorthopädie. Leipzig: Thieme.

  • Herbst, E. (1934). Atlas und Grundriss der Kieferorthopädie. München: Lehmann.

  • Crozat, G.B. (1919). Technique for Orthodontic Correction without Extraction.

  • Balters, W. (1950). Der Bionator.

  • Fränkel, R. (1969). Regulation of Function in Orthodontics.

  • Clark, W.J. (1988). The Twin Block Technique.

  • Tweed, C.H. (1944). “The extraction of teeth in orthodontic procedure.” American Journal of Orthodontics and Oral Surgery, 30(8), 405–428.

  • Wiebrecht, A.T. (1930). Clinical Expansion Techniques with the Crozat Appliance.

Secondary & Contemporary References