Common plate appliances (here for lower jaw)
These two similar appliances exemplify the formerly widespread „active plate appliance“. It was not just an „expander“ to gain space, but allowed for dental straightening almost at the same time – if constructed and handled properly! H = anchoring clasps, D = expansion screws (which in fact require growth to work properly), here even in 2 directions E = spring for a tooth correction, shaped according to the desired movement, S = labial arch (a common element).
Most of the following appliances are based on this, but developped further.
In the second specimen, the anchoring clasps at the rear are slightly simpler, but the front is equipped more generously with protrusion springs for tidying up crowded teeth.

Find examples of full treatments with plates in the „case examples“ chapter. Hints for distinctive applications of Crozat and plate appliances are there in the sub-chapter about classical Crozat treatment.

Wrong: how a blocked cuspid had to stay trapped

This is a typical example of a poorly designed plate appliance. Treatment started in late mixed dentition, where the gap for one of the cuspids had narrowed to great extent. But instead of re-expanding this space little by little, the positions of the adjacent teeth were retained by this plate.
Since it has the screw elements in wrong positions, it wasted 2 precious years of growth and made the case severe. An attempt to obtain a second opinion in time was hampered, because the visited orthodontist was one of that kind who make all patients first wait until all milk teeth are gone. This strategy aggravates all cases more or less, which increases the profit of the orthodontist as well as the pain and damage that the late treatment does to the patients. The patient here was menaced by a common package of orthodontic extortion: mutilating extractions, or headgear, or expensive, but hampering large fixed installations (pendulum, distal jet) - and each of these combined with painful fixed bracket braces.
The rarer specialists of gentle treatment offered mainly Crozat appliances (see below), which were however rarely covered by health insurance here.

Plate with additional clasps (Voss plate): expansion, distalization, vampire cuspids
To develop a narrow jaw or a crowding of side teeth into a healthy situation by means of a plate, this appliance requires screws in the right positions. Moreover, it needs sufficient anchorage for efficient transmission of their forces. Additional clasps at both sides of the screw prevent the plate from lifting off when it is screwed further and further, that means that it loses its proper fit and that part of its force falls flat.
In this sense, the first photo shows a typical vampire canine teeth situation, where the narrowed gaps have already been re-gained. It is presumably a Y plate (see below) which bears additional clasps on the 2s and 4s here, and also guide wires for the cuspids which now are free to grow down.
The next photo shows a used plate expander with additional clasps on the 2s. It had expanded the upper jaw by approximately 5 mm even in this stage with no more milk teeth left. Also the green specimen under Plates for single-sided expansion against single-sided crossbite has additional clasps.
The b/w photo shows a successful re-distalization of 3 teeth which had shifted forward. This plate contains a further screw for simultaneous expansion, which was not used here. Teeth often migrate forward when milk teeth are destroyed before their successors are ripe, and narrow their gaps as it is displayed in the sequence below: the gap for the cuspid is narrowed to 1/3! Only 1 milk molar is left, but when it falls, it will provide another 2 mm of space.
2 wire elements support this plate in the incisor region, which was able to re-gain the lacking space by its backward screwed (distal) segment. It was provided with a lining of fresh plastic material during this, to re-establish the neat fit which generally degrades when screwed segments are used to greater extent. This treatment was accomplished by an activator which had additional guide elements for the growing cuspid as well as for the bicuspids which appeared rotated due to excess of space.

No lobby acts for this proven and economic technique. In contrast, manufacturers of countless fixed distalizers and „bone piercing“ (micro-implantat anchorage) engage reputable speakers for courses in which they promote these risky and forced techniques, which endanger children as well as adults.

Y plates, Z plates, Bertoni plates
Due to their large roots, cuspids (canine teeth) are important teeth, but often develop later than both their neighbors. Space can lack for them in case of insufficient jaw growth or premature loss of milk teeth. Then they often grow off-site, mostly before, rarer behind the main row of teeth.
Treatment would be easier when not waiting so long.
Y and Z plates use 2 common screws to gain space for the cuspids. Their gaps can nicely be expanded by the plastic ends of the screwed segments. These have to be shortened little by little when the cuspid grows in or is being aligned.
The Y-shaped segmentation of the colourful upper specimen causes expansion as well as stretching of the jaw. This is a light case, whereas the harder case in the mouth photo in vampire cuspids above obviously also wears a Y or Z plate: screw elements inside of the narrowed gaps had already re-gained them by expansion and stretching.

The following specimens (yellow and violet-from-b/w) have their screws more distally placed. They finger into the cuspid position by a Z-shaped 3-segmentation of the plate. By their rather sagittal direction, the gap is opened mainly by stretching and distalization.
Y and Z plates differ less in the lower jaw (pink specimen). The screws can be placed more or less frontally there.

The indication for the Y plate overlaps with that of the more recent Bertoni screw (3-way-screw). The green plate shown below contains it, and moreover 2 distal screws, so that this plate has 5 segments! Nevertheless it is not bulky, and can be used like a Y or Z plate to shape the dental arch.
In addition, it is equipped to derotate the canine teeth, which are rotated by lack of space, already while the space for them is under way to be recovered. Such are the details which make the difference between high-value plates for removable treatment and plates which are only for preparing fixed braces. 3- or 4-way screw elements in various sizes exist also for lower jaw plates.

Such plates as shown here were proven for treatment of children and, by taking some more time, also for teenagers. Nowadays, they fall into oblivion, irrespective that they offer a way out of the frequent bad business which is exemplified above under Wrong .. cuspid had to stay trapped: only treatment with extractions or with a headgear is offered there, or sometimes with more expensive, hindering fixed appliances under the palate (Pendulum, Distal jet), or even piercing mini implants (micro screws, micro pins) through the flesh into the bone, which imposes a considerable risk of persistent bone inflammations to the patient.
Compare all these options to wearing a segmented plate.

Molar distalization by screwed segments: (pre-prosthetic) adult treatment; impacted cuspids
The symmetrical blue plate contains on both sides 2 double screws with 2 independent segments each.
All 4 premolars lack in this adult upper jaw: 2 had been sacrified for orthodontic treatment long ago, and 2 were destroyed more recently. These latter should now be replaced, but the molar teeth have already migrated forward and narrowed the gaps too much. Therefore, the screwed segments should recover sufficient gaps. The enlarged image with the red arrows shows that the front segment is to shift towards the fixed position of the screw heads, while the rear segment is to shift away from it. A jagged anchor for this long element can be seen inside the plastic behind the incisors.

In the next, younger example, the canine teeth stayed impacted in the jawbone (as do impacted wisdom teeth sometimes without harm).
At first, sufficient space was created for them with the violet distal plate shown here and a subsequent one, by pushing teeth forward as well as backward. The big molar teeth had to be pushed individually, each with its own screwed segment of the plate, 1 on the right and 2 on the left hand side here (when the above double screw was unavailable). There, also the second-but-last molar can be shifted individually, if the more frontal screw is opened and the rear screw closed by the same distance. To prevent breakage well, it is advisable to choose the frontal screw bigger.
After the required space was provided, one cuspid grew in by itself (at an age of 25), whereas the other had to be cut free and pulled out slowly, by glueing a hook to it and connecting it with a rubber band to a corresponding hook at the appliance. Crozat appliances (see below) would also be suitable for this.

Crozat appliances
are the oldest system of removable braces, invented and developped to mastery in the 20ies of the last century, before plastic era. Wire elements of different thicknesses were soldered together to light appliances which are well-suited for full-time wear, in particular for adult and pre-prosthetic treatment, and if teeth or gums have already damages.
Experts, which become nowadays rare, perform full treatments not only of simple cases with these appliances, since they can widen and lengthen the arches and correct individual teeth. A limited expansion of the upper jaw is still possible in adults – slowly, but with these appliances with almost no discomfort.

Inspite of the plenty of orthodontic „late cases“ (= teenagers and adults) being, this gentle and proven method is hardly reported anywhere in the mass media.
Rather, orthodontic implants are systematically disseminated in congress-filling manner as a high-profit invasive technique, but endanger the patient with persistent bone inflammations (see below under Less discomfortable additives.. for more about it).
Find old and recent Crozat cases in my „case examples“ chapter.

Hybrid type and upgraded Crozats
Hybrids between Crozat and plate appliances can be built economically out of common materials without soldering or welding. E.g. the blue lightweight spring expander in the upper photo. There, small plastic wings bear common clasps (anchors) and are connected by a thicker wire spring. Even prefabricated parts which are intended for fixed use (lingual arch, palatal bar, quad helix ...) could be adapted for this, to make their use more human.

In contrast to plate appliances, normal Crozats have just 2 clasps, which are in the molar region. Because Crozat appliances were originally intended to give teeth just stimuli in the desired directions, and to leave them otherwise free to find their anatomic positions. Of course, Crozats can be built with more clasps, but that could hamper this original intention. Moreover, in some cases it cannot be judged in advance if 2 clasps would be enough. The lower photo shows an upgraded Crozat. Before, its anchorage had turned out to be insufficient. Occlusal extensions were also desired to treat a crossbite better. They were added out of plastic material, and additional clasps embedded in them.

Lightweight expanders with screw or spring instead of quadhelix or other fixed expanders
Removable expanders can be built such that they do not hinder speech, because leaving the frontal palate free, and that they are little visible when worn. In the upper specimen, plastic covers the side teeth instead of clasps. This is also suited for slow expansion in permanent dentition (upper jaw still expandable up to 4-6 mm). It could also be made by thermoforming of plastic sheet (if machine available). For children whose side teeth may change, on the other hand, ordinary clasps are preferable.

Continuous force can either be provided by a screw with an included spring, which is a specialized part, or by simple wire loops in spring expanders as shown below with various clasps. The strength or thickness of their spring can be varied, and also the position where it leaves the plastic wings. For details on this, also for the lower jaw, see Lightweight prototypes chapter.
Even more than 4 -5 mm width can be gained in children by removable expanders, with no need of splitting the palatal suture or other cruel treatment. Such widespread forced methods are due to an inhuman hurry and to a neclect of loving care.

If the 6s are too conical or not yet fully erupted, so that these appliances fit too loosely, then tiny white attachments could be glued to these teeth, which are now widespread in aligner orthodontics. In contrast to bands or brackets, they neither hurt the flesh, nor hamper cleaning these teeth far inside the mouth. The appliance would snap in as firm as an aligner splint (see below) on these attachments.
In contrast, the fixed quad helix, which is marketed as intensively as the devices for to brutal palatal splitting (Hyrax et similar), disturbs swallowing, speech and chewing. Every bit gets stuck in its coils, and the tongue becomes sore by always scratching along them.
Find victims´ reports in the „Less disturbing kinds“-chapter.

Plates for single-sided expansion (really!)
with an approximate force distribution of 2/3 to 1/3, to correct a single-sided crossbite that has already grown-in. For single-sided crossbite in early state (muscular crossbite), a simple expansion plate would often be sufficient (force distribution of 1/2 to 1/2).
A solution from old literature, the 1/4 – 3/4 divided activator (double decker appliance), would be larger scale, and the fixed, pre-fabricated quad helix which is nowadays advertised disturbs swallowing, speech and chewing (see examples in the „less disturbing kinds...“ chapter) and moreover, has more relapses than expansion plates have.

Both specimens here are asymmetrically divided.
The green belongs to a 8-yr girl who was threatened by rapid palatal expansion (RPE) elsewhere. To unlock the wrong occlusion, this plate extends over the side teeth. Many clasps assure a good grip, and the large expansion screw bears an included spring to deliver a continuous force. Simultaneously, 3 protrusion springs are to widen the frontal arch, and a finger spring is to re-gain the narrowed space for a growing cuspid.
The yellow specimen, which could also be equipped with further elements or coverage of side teeth, has a simple, big expansion screw and another solution for more continuous force delivery: the contact zone to the teeth which are in crossbite consists of silicone rubber.

Plate with spring bolt screws
By use of a reamer, the tiny spring-bolt screws can be inserted later into a plate appliance, e.g. if changing teeth appear too much inward.
In the example here, a young cleft-palate patient with 45° twisted front teeth profits from skillful removable treatment. The screws act from one side and the frontal wire from the other, to untwist these teeth. Note also that the expansion screw is already expanded by about 5 mm!
In the following picture, the left one of the frontal screws has been re-inserted, to re-adapt its direction to the proceeding correction.

This example demonstrates that even a cleft-palate child is not condemned to palatal splitting and other painful fixed stuff.
Find more details in the „expl. of cases“ chapter.

Plates equipped with silicone rubber for „complicated“ tooth corrections
If sufficient space has been provided, this rational technique can correct teeth which are in the row but nevertheless not straight, that means tilted (around 3 axes possible).
This appliance is mainly a plate, with a rigid body and clasps (and screws would also be possible). It should provide a framework around those (tilted) teeth which are to align. On the plaster model, these are then cut out and re-fixed in aligned positions (setup / aligner techniques), and silicone rubber is molded around them onto the outer framework and the distant inner plate border.

Such plates are much smaller than the common elastic „positioners“, which are used when fixed braces gave no good result, but can also be applied independently.
Moreover, such a plate would allow larger alignments / untwistings with litte effort, just by stepwise alignment of the plaster model and subsequent renewal of just the silicone rubber parts, which is easily done!

2 more examples for silicone rubber bearing plates and splints: 1 fine and 1 wide correction by W. Paulus.
Thermoformed splint for fine correction of lower incisors, manufacture: At first, a soft spacer splint is molded over the teeth of the original plaster model which are to correct (the one with the blue stripes here). The larger the required corrections are, the thicker this material should be. This part is cut to size and remains adjusted to the model while the final, hard splint is molded. Then, this is cut to shape, and the spacer is taken out.
Next, a set-up of these teeth is made, and silicone rubber is filled around them into the void of the splint which was created by the spacer.

Plate with silicone rubber for upper front correction to a greater extent, an ecomonic solution: At first, the silicone presses the teeth only there where larger movement is required. The other regions of these teeth on the plaster model are filled with wax. This allows the silicone of the first run of the final appliance to expand to the sides while squeezing frontally as desired.
Depending on whether the silicone has point contact or full contact to these teeth, it will move them rather tipping or rather bodily. The plate can moreover be equipped with screws.
For the second run of the appliance, the same set-up model can still be used. But now, all void is filled with silicone, no more wax. Note well that it acts from both sides here: instead of just a frontal wire, the plate has a plastic shield before the incisors, which bears also silicone inside.

Less discomfortable additives for fixed braces
The original add-on parts for US style multibracket techniques pay hardly attention to patient comfort, because the patient, especially if a child, has no other choice anyway. In addition, they hamper oral hygiene.
More recently, the profitable international orthodontic business spreads further orthodontic armament in form of little mini implants (mini pin, micro screw, mini screw, ...), which are pierced through the flesh into the bone, for all type of better fixation of fixed braces. Since they create a highway for bacteria into the bone, where inflammations are difficult to cure, their unneccessary use endangers adults as well as children. In contrast, they are completely useless for removable techniques! But nevertheless, removables are frequently abandonned.

Solutions with less discomfort or danger are obvious to those who are familiar with removable techniques, in particular with plate appliances, as single jaw treatment is concerned. The images show a speech-friendly, frontally open design of such an add-on plate, and 2 solutions to snap it in: silicone rubber to fixed buttons, or ball head clasps and outer grips for removal. Common applications:
-Maintain jaw width or position of last molars: simple blank plate to wear at night or part-time. Instead of head gear, lip bumper, nance appliance, palatal arch or other disturbing things.
-Expansion: screw, fan screw or spring expander (find more about this under Lightweight prototypes). Instead of quad helix or splitting of the palatal suture (for these, see victims´ reports in the „less disturbing kinds of braces“ chapter).
-Protrusion of front teeth: plate with protrusion springs / screws instead of disturbing lingual arches.
-Distalization (backward shift) of the last molars: segmented plate with distal screws, instead of headgear, lip bumper, pendulum, distal-jet or other such fixed instruments.

Concerning bite correction and vertical deviations (deep bite, open bite), prefabricated trainers are available, also such which are compatible with multibracket appliances (T4B = trainer for braces).
1) Class II overjet, also with increased overbite (deep bite), can be corrected by sustained use of such trainers for 1 – 3 years, instead of hampering Herbst appliances or other bulky, unhygienic fixed parts.
2) More rapidly, a covered or deep bite can be levelled out painlessly. The required vertical forces are easily provided by biting on the trainer, instead of fixed bite blocks which extremely hamper any mastication.
Apart from the (orange-coloured) T4B, which resembles the Muscle force Jaw shaper in shape (find instructions under Kaukraft Kiefer-Former), but has a groove for fixed braces, a thicker fixed-compatible trainer for covered bite is available. In contrast, the covered-bite type of the Jaw shaper allows the patient to have an arch shape which is somewhat more tapering than standard.

Lower exterior plate (buccal plate), e.g. for gap closure if teeth are missing
This wears comfortably because without plastic parts inside. It is described in literature only for the lower jaw and has advantage for straightening of inward tilted teeth and for gap closure with a traction screw, e.g. for those 5% of people whose premolars in position 5-below are not formed, if their respective milk molars could not be preserved. The coloured specimen is for demonstration.
Even if it is nowadays told with commercial interest that this task would require fixed braces to be solved properly, look in the case reports for successful removable treatments of such gaps. Spontaneous gap narrowing by forward migration of the molars should be allowed for before fitting an appliance. Moderate speed when screwing or light force when using springs (also with Crozat appliances which would be suitable here) are crucial for tilt-free gap closure.

The monochrome views show a specimen with an additional space creating screw between the crowded tooth 5 and 6 here on the right, and a traction screw to close a little gap on the opposite site.
A further application would be the contraction of the lower front e.g. if it had been expanded by bad tongue habits. With a frontal traction screw, and with elastic silicone joints in the cuspid region, such an appliance would contract just the front and not the whole arch.

Extrusion (elongation) of teeth / use of „shelves“ (tiny attachments)
To close an open bite after growth has finished, grips are required at the respective teeth to apply a force in extruding direction (the image shows a dummy). But no need to make them broader than required to pose a spring wire on them. Such tiny, tooth-coloured „attachments“ do not cause irritations, nor hamper cleaning. They have become common for active splint treatment (see below), for teeth which can otherwise not be grabbed sufficiently to direct the desired force to them.
Here, the attachments give a grip to the surrounding spring of a speech-friendly constructed open plate, so that its extrusion force can be transmitted. This principle can be transferred to extrude side teeth if required, and the plate can bear further elements e.g. an expansion screw. Compare how comfortable a common extrusion method is: rubber bands stretched between brackets or buttons in upper and lower jaw.
Attachments can also be used to improve anchoring clasps in difficult cases e.g. when teeth are not fully erupted.

Intrusion (= pressing too long teeth more into the bone)
The specimen shown here is intended for rather „cosmetic“ intrusion of the incisors. More often, re-intrusion of side teeth which have grown too long is required medically in pre-prosthetic treatment. Here, removable appliances are of hygienic advantage especially for patients who have already reduced, shrunken gums.
Intrusion plates require good anchorage at all other teeth, or extensions which allow to transmit the force of biting down just to the teeth which should be intruded. When anchoring teeth lack, also in children who lost many milk teeth at once, one-piece appliances could be an alternative, e.g. prefabricated trainers like the Muscle force Jaw shaper (see Kaukraft Kiefer-Former).

Active orthodontic splints (aligners): Orthocaps, Invisalign or hand-crafted „contact lenses for the teeth“
are rather for adults and older teenagers and not a „budget“ solution, but continuously developped further. A set of dozens of thin colourless splints is generated, each of which is some 0.2 mm more „correct“ than the previous. Each is to wear in full-time wear for 2 weeks. Part-time wear will prolong the treatment.
A moderate space gain for crowded teeth is possible by narrowing (stripping, slicing) the teeth, as has been done in the example here. In cases of open bite, little tooth-coloured attachments can be included, similar as in Extrusion (elongation) of teeth.
Other systems use a combination of hard and softer splint materials, and are moderately priced. Under continuous force, orthodontic movements proceed rapidly during the first 14 days and then slow down because the surrounding tissue exhausts. The system Orthocaps (www.orthocaps.de) prevents this exhaustion by using hard and soft splints in turns. Here, the whole treatment consists of up to 8 cycles.
Another possibility to profit from this „orthodontic chewing gum effect“ is offered by certain dental laboratories which manufacture orthodontic hard-and-soft compound splints.
In turns or in one, the combination of hard and soft material improves the recovery of the surrounding tissue from orthodontic stress. This makes the treatment more comfortable and nevertheless rapid.

Plate with tongue attracting element
Tongue malfunctions are a major cause of teeth / jaw disorders. Speech training can help more or less, but the most violent method of tongue guidance are fixed spikes!
In sharp contrast, for this „comfortable-feeling“ appliance the morphology of the frontal palate has been replicated in thin silicone rubber, to give the tongue an almost natural surrounding around this little hole, which attracts the tip of the tongue to its correct position.
Such a plate could perform further corrections at the same time, e.g. with screws. If the incisors were tilted forward („protruded“) by wrong tongue activity, they can be pushed back by tightening the frontal arch wire. For this, the border of the plate has to be shortened there, of course.
From old text Headgear Plate: using a headgear with a removable plate spreads its force much wider than the usual fixation to the first molars, which are then menaced with root damage (pain is always a warning!). Besides, some kinds of coupled plates or function correctors have similar effect to the headgear. They are more difficult to construct, but offer features for further corrections. Note well that the headgear is historically older.