Fränkel functional regulator

Table of Content:

  > Introduction
  > History (Prof. Fränkel)
  > Overview of types of functional regulator
  > Principles of functional regulator action
  > Functional regulator type 3
  > Laboratory fabrication of the functional regulator type 3
  > Clinical handling
  > Other types of functional regulator

Introduction

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Functional regulators are removable orthodontic appliances belonging to the large group of functional orthodontic devices because of their growth-inhibiting or growth-promoting effects.
Definition of function regulator (Dental Dictionary):
Orthodontic device developed by Rolf Fränkel (Zwickau) in 1961 in the form of a skeletonized oral shield that, while not in contact with the underdeveloped parts of the jaw, is intended to bring about their development. Because the plate elements remain free, the tongue is unhindered within the oral cavity so that its shaping force can exert its full effect. At the same time, the lips are supported in the region of the nasolabial and mentolabial fold by frontal pads resulting in normalisation of lip closure. After application of wires and screw spindles, the functional regulator can also solve individual problems such as gap openings and malposition of individual teeth and groups of teeth in a mechanical orthodontic manner.
Definition of functional orthodontics, abbr. FOD, Norwegian system (Dental Dictionary):
- Therapeutic concept developed by Andresen and Häupl in 1935 of orthodontic treatment by means of functional appliances, e.g., the Activator®. Especially suitable for bite correction and bite levelling. Articular, mandibular and dentoalveolar changes are achieved.
- There are two different theories regarding the mechanism of action:
  1. Häupl’s vibration theory: It is only the appliance sitting loosely in the mouth that acts as a functional stimulator as the teeth are set almost oscillating between the appliance and the musculature (“molecular vibration”) and the excitability of the involved musculature is increased.
  2. Herren’s theory of diagonal jamming: It is not movement but the diagonally intermaxillary jamming of the appliance that produces the remodeling processes; the appliance works because it brings the mandible into an eccentric position and remodeling occurs as a result of pressure effects. Besides the activator there is a variety of functional orthodontic appliances, e.g., Bionator®, Gebissformer®, Functional regulator®, Kinetor® and many others (history: Monoblock®).

History (Prof. Fränkel)

Fränkel quote: "As a student of Leipzig University, I treated my first patient with such an appliance in 1928."
after 1957: Worked out the theoretical foundations and practical development of the functional regulator
1961: Director of the orthodontic institute in Heinrich Braun regional hospital in Zwickau, development of the functional regulator
1967: Monograph: "Functional orthodontics and the oral vestibule as an appliance base"
1973/1976/1984: 3 editions of his manual ("Technique and handling of the functional regulator")
from 1989: Publications with his daughter Christine Fränkel

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Overview of types of functional regulator

Functional regulator:	Indication:
Functional regulator type 1	Angle class I and crowding, especially when the apical base is underdeveloped Angle class II/1 (mandibular retrognathism) with normal overbite or open bite or distorotation of the mandible (vertical growth type)
Functional regulator type 2	Angle class I and overbite, especially when the apical base is underdeveloped Angle class II/2 (mandibular retrognathism) with overbite or vertical overlap, especially when the apical base is underdeveloped
Functional regulator type 3	Angle class III: mandibular prognathism, maxillary retrognathism and combinations
Functional regulator type 4	historical (no longer used) Used in the past in vertical growth type with anterior open bite

Principles of functional regulator action

Turn of the century	At the turn of the last century the oral vestibule was used as the basis for an appliance: NEWEL vestibular plate KÖRBNITZ lip former Vestibular shields to achieve competent lip closure
1892 - WOLF	Transformation law "Soft tissue shapes hard tissue"
1895 - ROUX	Law of functional adaptation: "Function is dependent on the functional demand, morphology is function become form" The term "functional orthopaedics" goes back to Roux Terms of reference: "learn new ways of functioning and by practice achieve skill and certainty in performing them"
SANDSTETT	Histological studies: - Traction -> bone augmentation - Pressure -> bone loss
1923 - LUNDSTRÖM	"Orthodontic problems are problems of the apical base" -> greatest treatment success in the period of most active growth the development in the size of the apical base is established in principle after tooth eruption -> this then determines the extent of the room for orthodontic maneuver -> the apical base must therefore be influenced during the mixed dentition period
1954 - BALTERS	Considered the "space function" important for orofacial development
1965 - ESCHLER	"Tongue size has no influence on the position of the mandible in the sense of forward translation, as its strongest muscle is attached to the mandible."
1968/1969 - MOSS	Concept of the "functional matrix": Cranial development is not subject to direct genetic control but is induced by the 'functional matrix' (theory is controversial).
1970/1972/1983 - VAN LIMBORGH	'Epigenetic regulation': principle of induction, familiar from embryology
1973 - MOYERS	"Maturation of the musculature": importance of environmental influences for the development of neuromuscular functional patterns and therefore for craniofacial morphogenesis
1975 - BOSMA	The adoption and maturation of physiological functional patterns of the orofacial musculature are paramount for the development of jaw and facial form The development of motor and tonic functional patterns begins posterior in the region of the tongue and palate Sucking lip function develops slowly The tension of the lips allows conclusions to be drawn about the entire outer soft tissue capsule -> if disturbed, early intervention is necessary in the development period Early identification of pathophysiological states is important Unphysiological spatial conditions are usually caused by incongruity of the retaining functions of the musculature -> note functional incongruities of muscle in particular
1985 - MOSS	MBI (natural muscle bone interface): Muscle functions can activate osteogenic growth zones only in the sense of a functional stimulus when there is a natural connection between muscle and bone. Growth: Following fertilization of the ovum, the genome does not yet contain information about all subsequent growth processes for optimal regulation of all specific local growth processes at later stages of development and growth but 'epigenetic information' must later control development, i.e., there is a genetic capacity for adaptive growth processes under different environmental conditions The growth zones respond to biomechanical influences, but only within their genetically determined potential The epigenetic regulatory mechanisms are not change by purely mechanical treatment -> risk of relapse It is therefore better to change these mechanisms and use them for treatment (e.g., 'Peruvian' skull bandages after the age of one year to influence the direction of brain expansion); this has demonstrated that the extent of growth cannot be influenced but its direction can (can be influenced vectorially)
1985 - ENLOW	Warns against highly simplified ideas of skull growth and that growth is easy to influence Bone tissue is not equipped with the capacity for independent growth

Aetiology of dysgnathia:

Multifactorial genetic system (influenced by environment and heredity)
Hereditary factors are highly involved in class III dysgnathia
The growth the maxilla and mandible is established by interval determination, i.e., optimal environmental influences allow the genetically determined interval limit to be reached -> full genetic dysgnathia does not develop in the phenotype
Functional regulator is a positive environmental factor used deliberately to harmonize further development

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Pathophysiology of the orofacial complex:

Close interaction between musculature and space:
The shape and size of the oral functional space are determined by the external soft tissue capsule that surrounds it
-> unphysiological spatial conditions must be seen in close conjunction with pathophysiological functional patterns of the muscles:
Hypertonicity of the cheek and lip muscles can lead to narrowing and decreased tone to enlargement of the oral space
The functional patterns of the muscles responsible for the position of the mandible also play a part in the shape and size of the oral cavity

Action of the functional regulator:

Corrects unphysiological spatial conditions and muscular imbalance
Mechanical expansion of the circumoral capsule by the buccal shields outside the alveolar processes -> the shape-changing action of the functional regulator is not based on application of pressure but on intervention in the epigenetic milieu
Release of regional tension, especially in the region of the nasolabial and mentolabial fold
Physiotherapy effect by massaging and kneading the soft tissues over the shields during all functional movements of the perioral musculature (speech, swallowing, facial expression)
Orthopaedic training device: "forced exercise" of the labial and buccal musculature due to functional adaptation to the resin elements

Oral functional space: pathophysiology

e.g., mandibular retrognathism:
The sagittal development of the lower half of the circumoral soft tissue capsule is delayed -> the development of mandibular length is thereby prevented; vestibular shields can enlarge the functional space and enable further development of the mandible and at the same time, normal contact between the upper and lower lip is produced with the aid of lip pads, thus achieving physiological closure of the functional oral space
e.g., maxillary retrognathism/mandibular prognathism: [fig. 8]
The sagittal development of the upper part of the soft tissue capsule is relatively delayed; narrowing of the capsule can be corrected with the aid of the vestibular shields with expansion of the functional oral space
e.g., crowding:
delayed transverse and sagittal development of the size of the circumoral capsule; corrected by expansion of the outer soft tissue capsule with the aid of the buccal shields
e.g., Angle class II/2 with horizontal growth type:
greater vertical expansion of the buccal shields
e.g., vertical growth type with absence of anterior oral space closure: lip closing exercises with the functional regulator

Nasopharyngeal functional space: pathophysiology

Physiological conditions are present in the oral and nasopharyngeal space only when the valves that close the functional oral space function correctly
Correct valve function in the oral and nasopharyngeal space, so-called triple "lip closure" [fig. 9]
- competent lip closure
- normal resting tongue position
- physiological posterior soft tissue closure (velopharyngeal closure)
If the nasopharyngeal air passage is narrowed, there is compensation by the respiratory musculature and diaphragm
Mouth breathing therefore does not necessarily arise from local narrowing of the airways (e.g., due to adenoids or enlarged tonsils) but is often an expression of an incorrect habit
When the closing function of the third posterior valve is intact breathing is through the nose even when lip closure is incompetent

Functional regulator type 3

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After growth is complete, the only possible therapy is combined orthodontic surgery and orthodontic treatment.

Indications

General indication: Angle class III, lead symptom: frontal crossbite or edge-to-edge bite

mandibular prognathism

maxillary retrognathism

combined forms

asymmetric skeletal or functional class III (only likely to be successful if treatment is started early)
also in combination with underdevelopment of the apical base (primary crowding symptoms)
Growth type: vertical, neutral or horizontal
as late treatment in symmetrical class III, if tooth deformities were previously corrected by orthodontic methods (with late treatments, follow-up after one year; depending on reaction advise that surgery may become necessary)
FR-3 as retention appliance:
- To ensure success after correction of unfavorable functional patterns
- To prevent function-induced relapse after orthodontic dentoalveolar compensation
- After combined orthodontic and orthodontic surgical class III treatment

Start of treatment:

Early mixed dentition, between the ages of 6 and 8 years
-> the eruption path of the upper incisors can be steered;
-> the epigenetic induction potential of the erupting upper incisors then influences sagittal maxillary growth
An earlier start of treatment does not appear useful as orthopedic exercise with the functional regulator assumes a degree of patient maturity
Early start of treatment: cooperation-dependent, depends on extent
Late start of treatment: dependent on general development status (chronological age, dental age, skeletal age)

Alternatives to FR-3:

U-bow activator type II
Wunderer prognathism activator
Head-chin cap
Delaire mask
RME

Principles of action of the FR-3

Pressure application:

Spring-activated, function-activated
Buccal shields sit on mandibular alveolar process
Labial bow in the mandible, anterior teeth for it relieved on the model
-> skeletal inhibition in the mandible

Elimination of pressure:

Elimination of pressure through resin elements in the maxilla standing away from the alveolar process with additional traction on periosteal regions to stimulate bone apposition
-> significant stretching effects in apical regions of the maxilla
-> sagittal and transverse development of the maxilla
Inhibitory factors in the perioral muscles are disabled
Stimulation of the osteogenic activity of the growth zones by epigenetic induction
Physiotherapeutic effect due to widening of the outer soft tissue capsule
Direct elimination of buccal and labial pressure, while the oral cavity is free apart from stabilizing transpalatal wire components -> thereby greater effectiveness of the tongue, the shaping force of which can act fully

Application of traction:

Fixed-direction traction on the periosteum through lip pads and buccal shields in the maxilla -> causes the perioral matrix to be deformed into osteogenic guide scaffolding
Effect: bone apposition, remodeling of the maxillary alveolar process in the mixed dentition period
The shields placed high in the vestibule stress the periosteum and outer alveolar walls near their base by directed traction -> effect as far as the base: more lateral or labial tooth eruption, no tipping
The mouth must be closed for the directed application of traction -> only works during the day, at night elimination of pressure exclusively

Functional regulation:

FR-3 as an orthopedic training device
Physiotherapeutic effect through kneading, massage, stretching the soft tissues during all functional movements such as speaking, swallowing, facial expressions
Gymnastics under more difficult conditions
Forced gymnastics of the labial and buccal musculature, e.g., lip closure with the appliance, lip closure training [fig. 13]
Muscle functions are forced to adapt functionally to the resin elements -> malfunction becomes more difficult or is prevented while normal function is allowed (speaking, swallowing, facial expressions = exercise)
In extreme cases additional "conscious" gymnastics: myofunctional therapy
Special exercise: hold a coin with the lips, FR-3 in situ 10-60 minutes daily
Train in nasal breathing

Aims of treatment with the FR-3:

Skeletal:
- Promote three-dimensional growth of the maxilla
- Inhibit three-dimensional growth of the mandible
Dental:
- Disable scrambling and constraining dental components
- Stabilization through harmonious static and dynamic occlusion
Soft tissues:
- Re-education and normalization of unphysiological functional patterns of the capsular musculature
- Stabilization by a harmonious soft tissue environment as regards morphology, rest position, function and cessation of habits

Tooth eruption:

The genetically pre-programmed movement of the teeth during eruption is the growth-inducing factor for the apical base
The functional regulator influences the eruption movements of the permanent teeth by eliminating perioral soft tissue pressure and traction on the base of the alveolar process, that is, by influencing the remodeling processes in the alveolar wall
van der Linden and Duterloo (1976):
- In the mixed dentition, the tooth germs of upper 3, 4 and 5 are palatal to their deciduous predecessors; in the mandible, the teeth, and especially their developing root apices, are markedly lateral -> in the maxilla, the teeth have to erupt in lateral direction and in the mandible straight upwards
- The buccal alveolar walls are resorbed even before actual tooth eruption (study by Falck, 1969)
- Especially in the maxilla, increased muscle tone in the soft tissue capsule thus acts directly on the tooth germs -> buccal shields prevent this and provide space for development of the apical base

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Directed application of traction and elimination of perioral soft tissue pressure by the buccal shields during mixed dentition Result: transverse development of the apical base

Laboratory fabrication of the functional regulator type 3

Construction elements of the FR-3

2 buccal shields: Extend down into the upper and lower vestibular fold End mesially at the level of the canines and distally behind the last molars In the maxilla they stand 2.5-3 mm away from the outer surfaces of the alveolar process and posterior teeth -> this widens the outer soft tissue capsule and enlarges the functional oral space -> space is created for transverse development of the maxilla The lower par of the buccal shields sits closely against the mandibular alveolar process to counteract excessive mandibular development		#pic#
2 upper lip pads: The upper border extends into the upper vestibular fold The lower border is 4-6 mm from the gingival margin The distance from the outer surface of the alveolar process is 2.5-3 mm -> this widens the outer soft tissue capsule -> space is created for sagittal development of the maxilla		#pic#

Connecting stabilising and active wire components:

Upper protrusion spring = protrusion bow:
- Sits on the palatal surfaces of the upper incisors close to the incisal edge
- Passes in buccal direction suspended distal to the canines
- Intermittently active element, the spring activation of which is intended to manage the upper incisors
Lip pad connecting bow:
- Curves widely to avoid the labial band
Connecting bows between lip pads and buccal shields:
- Must allow for labial bands
- The part in the buccal shield must not have any bends apart from the hooked ends
  -> this way, the lip pads can later be moved forward by pushing the wire in the resin of the buccal shields
Transpalatal bow:
- Sits on the palate with a small gap of 0.5-0.75 mm
- Passes behind the last molars into the buccal shields
- Provides the appliance with transverse rigidity
- When specially indicated, tongue stimulation beads or rolls can be attached to the transpalatal bow
Wire rests in the maxilla:
- optional (when greater occlusal locking is required for transferring the anterior teeth)
- sit on the occlusal surfaces of the buccal cusps of the last molars
- are ground off after a secure frontal overbite is achieved
Wire rests in the mandible:
- obligatory
- Provide the appliance with vertical support
- Run in the central fissure of the last lower molars
- Slight occlusal locking is achieved by the wire thickness
Labial bow in the mandible:
- Sits tightly against the lower incisors and canines at the level of the gingival papillae to achieve inhibition of mandibular development

Technical procedure

There is limited scope for correcting errors in the construction of the functional regulator in the patient -> a technically accurate procedure during fabrication is therefore essential

Fabrication of extended working models from white orthodontic plaster (leave the vestibular folds)
Mounting the models in the fixator
Relieving the working models
Application of the wax lining
Bending the wire components
Fabrication of the resin elements
Polishing

Technical fabrication: Functional regulator type 3

Clinical handling

Counselling and accepting the patient

OPG, lateral X-ray
Impressions for initial models
Clinical examination (soft tissues, MRFH [morphology/rest position/function/habits], dental findings, clinical functional diagnosis)
Informed consent:
- Separate discussion with parents (without the child present):
  Address prognosis including possible surgery after growth is complete (inform about late influences on growth)
- When counseling, always be very cautious with regard to prognosis as to whether surgery can be avoided; do not mention surgery in the child’s presence
- Explanation about long-term treatment
- No success = partial success (at least has not become worse)
- If reaction/cooperation insufficient: "allow to grow"

Start of treatment

Impression:
- Alginate impressions of the maxilla and mandible are needed to fabricate working models [fig. 19]
- Good representation of the outer surfaces of the alveolar process and vestibule is necessary for construction of the specific vestibular resin elements but there must not be any extreme compression of the soft tissues
- It may sometimes be useful to extend standardized impression trays individually with wax (note the course of the labial and buccal bands)
- However, extremely extended trays falsify the morphology of the base of the alveolar process and are therefore not recommended
- The impressions should be labeled FR for Functional regulator so that the working models are not trimmed too much by the technician and the full impression of the vestibule is preserved
Measurement of the maximal depth of the patient’s oral vestibule:
- As the full extended height of the upper vestibular fold in particular cannot be measured, it must later be relieved in addition on the working model
- As a basis for model relieving for the later lip pads, a resin-coated ruler is used to measure clinically the vertical distance from the incisal edge of the upper lateral incisors to the depth of the vestibular fold and this is noted in the technical instructions (average: 24 mm)
- In the lateral vestibular fold measurement for the planned buccal shields is not entirely practicable (tray margins coated with wax provide sufficient information here; the distance from the occlusal surface to the vestibular fold in regions 16 and 26 is 19 mm on average)
Bite registration (construction bite):
- Material: roll up a preformed wax stick or pink sheet wax
- Procedure: the patient sits upright with the head in natural position; the wax rim is first fixed to one jaw and then guided closed [fig. 20]
- Position to be adopted for fabrication of a functional regulator type 3:
  - sagittal: slightly forced retral condyle position
  - vertical: minimal vertical occlusion that just allows anterior tooth transfer (greater occlusion would make lip closure unnecessarily difficult or impossible)
  - transverse: note facial symmetry, ensure that the skeletal centre of the chin corresponds to the center of the face
- to fabricate a functional regulator type 1 or 2 the initial sagittal forward movement of the mandible should be 2 mm or 3 mm at most so as not to overtax the musculature
- to check occlusion, cut the wax rim free so that the buccal cusps are just visible and vertical occlusion can be assessed [fig. 21]
Patient’s color choice:
- Look at the color guide together with the child
- Make the color of the appliance as individual as possible (the child will be proud about this), ideally select two colors
- The buccal shields can appear 'striped' and the lip pads can be a different colour

Fitting the appliance, instructions for wear and caring for it

At the first fitting, check that the appliance fits exactly:
- The appliance is pressed against the maxilla and mandible in succession and the correct position of all wires and resin elements is checked
- If the working model has been relieved correctly, the upper border of the lip pads and buccal shields must be exactly in the vestibular fold
- Check that the resin elements stand away correctly from the maxillary alveolar process, while the buccal shields should sit directly on the mucosa over the mandible
- Hollow it out slightly over pale anemic areas of mucosa
- Check that there is no pressure contact between the lower edges of the pads and the mucosa when the mouth is opened
- Check lip closure: talk with the appliance in the mouth to overcome incorrect muscle tension

Wear instructions:

Ideal: wear for 24 hours a day (except during meals)
However, the appliance should be worn in extremely slowly
Wearing it at night or for long periods during the day immediately often causes pressure points (which jeopardize cooperation and also tend to ulcerate again even after healing)
Therefore, allow it to be worn for only 1/2 to 1 hour a day for 1-2 weeks until it is worn in (tell children this as they often enjoy the appliance and want to wear it for longer)
Increase wearing time slowly in the following weeks, but continue to allow it to be worn only during the day
The appliance may be worn at night also only after a wearing-in period of 2 to 3 months
The appliance should not fall out at night
-> this would be a sign that it is not yet sufficiently accepted by the patient and is perceived as a foreign body
-> "Losing it" at night also involves a risk of bending it
Aim: the functional regulator should be worn 8-10 hours during the day and all night
Obtain the child’s active cooperation, especially in performing lip closing exercises

Overview of wear instructions
Wearing period	Abbreviation
Only in the afternoons for a few hours for 5 weeks	T 1-2
Only during the day for 5 weeks	T 5-8
During the day and at night after 2-3 months	T 8-10 N
Retention phase	T 1-2 N

Care instructions:
- Store in a stable container (protect against bending)
- Clean the appliance with toothbrush and toothpaste

Follow-up

First follow-up session after ca. 4 weeks
- Check the mucosa for pressure points
- Slight erythema in the vestibular fold is common in the wearing-in period and is not alarming; however, if the erythema is greater, check the fit and edges of the vestibular places precisely and correct them if necessary
Second follow-up session after ca. 8 weeks
- If well tolerated after wearing daily for a number of hours the patient can now be given instructions for wear during the night
- Give specific lip closing instructions (symbols as a memory aid, such as dots stuck onto mirrors)
- Provide instructions on tongue exercises if necessary (special myofunctional therapy)

Regular follow-up sessions ca. every 6 weeks

Check the appliance for correct fit
Check the mucosa for pressure points
Consistent check of lip closure
Remotivate the patient
Activate the protrusion bow in the maxilla if appropriate:
This should sit passively and should be activated only the transfer phase of a frontal crossbite to achieve rapid tipping
Remove maxillary molar rests if applicable after anterior tooth transfer has occurred

Adjust the lip pads if necessary:

The lip pads can be drawn anteriorly by grinding free the distal retainer of the connecting bows between pads and buccal shields.	#pic#	#pic#
They are then fixed again by applying new resin so that the pads again stand away adequately from the alveolar process.	#pic#	#pic#
If deformity or wire breakage occurs due to incorrect handling of the appliance by the patient, correction or repair is often very difficult -> in case of doubt the rule is: fabricate a new appliance instead of attempting restoration..	#pic#

Interim follow-up after one year
- When the appliance has been worn for sufficient time success should be apparent after a year
- If obvious tongue dysfunction is still present, further myofunctional measures are indicated
Interim follow-up after two years
- If no success is apparent after two years, treatment should be discontinued now at the latest
- In this case, later combined orthodontic and orthognathic surgery will probably be necessary -> inform the patient of this
- Lengthening of the body of the mandible can be demonstrated by cephalometry after two years at the earliest
End of the period of wear
- Need for prolonged treatment (till after the puberty growth spurt)
- Wearing the appliance should cease at the latest after growth is complete
- Corrections by means of a multiband or multibracket system to shape the dental arches and for fine adjustment of occlusion may still be required

Other types of functional regulator

Functional regulator type I

Indications:

Angle class I and crowding
Angle class II/1 (distal occlusion) with normal overbite or open bite
Moderate labial inclination of the upper incisors
Underdevelopment of the apical bases (primary crowding symptoms)

Angle class I:

Early treatment: crowding, esp. with underdevelopment of the apical base
Late treatment: the apical base in the mandible must be already sufficiently developed as a precondition for expanding the dental arch by spontaneous uprighting of the teeth
Combination with extraction therapy is required if there is a major discrepancy between tooth size and the length of the dental arch

Angle class II/1:

Early treatment: mandibular retrognathism with normal overbite or open bite and underdevelopment of the apical bases
Late treatment: indicated especially for mandibular retrognathism with skeletal open bite (vertical growth type, distorotation of the mandible)

Start of treatment:

2nd half of the first mixed dentition period (ca. 7.5 to 8.5 years)
If open bite with eruption of upper 2 at the latest

Profile/cephalometry:

Mid- to hindface
neutral, horizontal or vertical growth pattern

Contraindications:

Eruption of upper 4 not yet complete if treatment is started only in the second mixed dentition period (requirement for secure intermaxillary support of the appliance)
Extreme deep overbite
Severe labial inclination of upper anterior teeth
Prominent foreface (maxillary prognathism)

Construction bite:

sagittal forward movement of the mandible of 2 mm, 3 mm at most, so as not to overstrain the musculature (3 mm with horizontal and 2 mm with neutral growth pattern)
minimal vertical locked occlusion: up to 2 mm in the molar region
correct transverse deviations in convulsive bite, 2 mm at most at the start if joint-fixed deviation

Measurement of vestibule depth:

In the region of the first upper premolars and maxillary tuberosity for the buccal shields
In the lower anterior vestibular fold for the lip pads

Construction elements of the type 1 functional regulator:

2 buccal shields:
- Stand away from the outer surfaces of the alveolar processes in the maxilla and mandible to allow transverse development
- Extend down into the vestibular folds, especially in the apical region of the upper 4s and in the region of the maxillary tuberosity
- Segmentation of the buccal shields for gradual forward movement of the anterior segment with lip pads and lingual shield
  gradual muscle adaptation
- Function:
  - Expansion of the outer soft tissue capsule -> transverse development of the dentoalveolar arches
  - Forced exercising of the labial and buccal muscles
2 labial shields
- Located in the anterior lower vestibule
- Shape: parallelogram with rounded corners
- Distance between the upper edges from the gingival margin of the lower anterior teeth: ca. 5 mm
- Function:
  - Support the lower lip in the region of the mentolabial fold -> this enables standard contact between the upper and lower lip
  - Prevent activity of the chin muscle during lip closure -> training effect for lip closing muscles
  - Expand the buccinator sling jointly with the lip pads
Lingual shield:
- Sits on the inside of the lower alveolar process
- Horseshoe-shaped
- Extends distally to the level of the second premolars
- The upper edges are below the gingival margin
- Function: achieves forward movement of the mandible without mechanical support: the pressure of the lingual shield activates the protractors and these then abolish the pressure sensation by moving the mandible forward
Wire components:
- Labial bow in the maxilla
  - Sits against the anterior teeth roughly in the middle of the labial surfaces
  - Can be used orthodontically for retrusion of proclined anterior teeth
- Canine loop
  - Interdental interposition between canine and first premolar for intermaxillary support of the appliance
  - Can be used as guide element if placement of the upper canine is necessary
- Palatal bow
  - For transverse rigidity of the appliance
  - Interdental interposition between upper 5 and 6 for vertical support of the appliance
  - Ends with a rest spike on the second deciduous molar (mixed dentition) or six-year molar (permanent dentition)
- Connecting wires between lip pads and lateral shields
  - Must bypass labial bands
- Connecting wire between lateral shield and lingual shield
  - Crosses the occlusal surfaces of the lower posterior teeth at a distance of ca. 1 mm
  - -> no interdental interposition as this would mean undesirable dental support of the forward movement of the mandible
- Lower lingual wires
  - In deep overbite, they sit lightly against the lower incisor and canine teeth at the level of the tuberosities -> prevent further extrusion
  - Touch the teeth only if protrusion is required, otherwise they must be worked to stand away from them

Functional regulator type II

Indications:

Angle class I and deep overbite
Angle class II/2 (distal occlusion) with overbite or vertical overlap
Severe labial inclination of the upper incisors
Underdevelopment of the apical bases
In the case of vertical overlap, prior orthodontic treatment to upright the upper anterior teeth is necessary
As retention appliance after treatment of vertical overlap

Angle class I:

Early treatment: skeletal deep overbite (horizontal growth type) and small apical base
Late treatment: also for skeletal deep overbite, possibly with extraction therapy beforehand if apical base is underdeveloped

Angle class II/2:

Early treatment: for mandibular retrognathism with overbite or vertical overlap with horizontal growth type and small apical base
Late treatment: for mandibular retrognathism without crowding; all single tooth deformities must be corrected by orthodontic measures before the start of the FR treatment

Start of treatment:

2nd half of the first mixed dentition period (ca. 7.5 to 8.5 years)
If vertical overlap with eruption of upper 2

Profile/cephalometry:

Mid- to hindface
Neutral to horizontal growth pattern

Contraindications:

Eruption of upper 4 not yet complete if treatment is started only in the second mixed dentition period (requirement for secure intermaxillary support of the appliance)
Prominent foreface (maxillary prognathism)

Construction bite:

sagittal forward movement of the mandible of 2 mm, 3 mm at most, so as not to overstrain the musculature (3 mm with horizontal and 2 mm with neutral growth pattern)
minimal vertical locked occlusion: up to 2 mm in the molar region
correct transverse deviations in convulsive bite, 2 mm at most at the start if joint-fixed deviation
Adjust edge-to-edge bite in the case of overbite

Measurement of vestibule depth:

In the region of the first upper premolars and maxillary tuberosity for the buccal shields
In the lower anterior fold for the lip pads

Construction elements of the type 2 functional regulator:

Vestibular shields and lingual shield are identical with those of the FR-1
- Additional important function of the buccal shield: prevents interocclusal interposition of the cheek
  -> no further inhibition of the vertical development of the lateral alveolar process
  -> bite raising
Differences from type 1 functional regulator:
- Modification of the canine loop to eliminate canine protrusion
- Additional upper lingual bow:
  - Sits on the palatal surfaces of the upper incisors
  - Must be interposed in deep interdental location between canine and first premolar or first deciduous molar
  - Function: intermaxillary support of the appliance; not suitable for protrusion of steep upper incisors, which is performed beforehand by orthodontic methods; however, the lingual bow prevents recurrence of incisor steepness

Functional regulator type IV

Indications:

historical (no longer used)
Used in the past in vertical growth type with anterior open bite or bialveolar protrusion and underdevelopment of the apical bases
Early treatment indicated even in the deciduous dentition period

Start of treatment:

1st mixed dentition period (ca. 6 to 7.5 years)

Profile/cephalometry:

Mid- or foreface
Neutral to vertical growth pattern

Contraindications:

Occlusion discrepancies

Construction bite:

sagittal: in habitual occlusion
vertical: minimal locked occlusion of ca. 1 mm in posterior region
transverse: adjust the skeletal chin centre to match facial centre

Measurement of vestibule depth:

In the region of the first upper premolars and maxillary tuberosity for the buccal shields
In the lower anterior fold for the lip pads

Construction elements:

2 buccal shields
2 lower lip shields
Palatal bow: runs behind the last molars
Upper labial bow: can actively retrude the upper anterior region
4 occlusal rests: stabilize the appliance vertically
Connecting wires