Activator (orthodontics)
The activator is in the orthodontics a removable bracket for upper and lower jaw in one piece. It consists of plastic and some wire elements, mostly an upper and lower labial arch. If necessary, additional wire elements to prevent misaligned teeth, an adjustment screw or lip shields can be added, while retaining clips are unusual. It is the oldest and best-known treatment tool in functional orthodontics (FKO). Unlike so-called active or orthodontic braces, it uses only oral muscle strength as a source of power. Activators are used to treat bite anomalies in the growth phase , primarily lower jaw reserves with or without a deep bite.
History and variants
In the 1930s in Oslo, Viggo Andresen and Karl Häupl discovered the influence of the mouth muscles on the development and healing of deformities. From this they developed functional orthodontics and the activator as their basic treatment to normalize abnormal jaw development by influencing jaw growth.
In contrast to orthodontics, functional orthodontics is a term coined in German. This painless new healing method spread rapidly, especially in Europe. Orthodontics for children has been based on active plates and activators for decades , because both complement each other: plates for 2-dimensional corrections of the dental arches in their plane, and FKO devices to achieve the appropriate jaw position for normal teeth and to grow teeth into the occlusal plane leave what a correction in the vertical 3rd dimension means. With active plates, space was gained if necessary, the teeth were arranged and the dental arch was congruent. Then, if necessary, the bite position was established with activators and, if necessary, a deep bite was raised. If the change of teeth was already completed, this phase could last 2 years.
Early treatments were preferred for severe distal bites or more difficult misalignments, such as an open bite or progeny , and are faster because of the greater growth.
Activators were thick-walled and voluminous with the production techniques of the time and made it difficult to speak. Therefore, various more delicate braces were developed from it, such as B. the following:
- Wilhelm Balters described the “mouth bite” syndrome and developed the Bionator for longer portability during the day by reducing the plastic body and changing the wire elements: a lip clip that is supposed to guide the lips and has loops on the sides that are supposed to keep pressure off the cheek, and one directed towards the palate Tongue bar for orientation of the tongue. Equipped in this way, the Bionator should not only normalize the oral functions, but also strengthen nasal breathing and improve posture.
- The U-bracket activator according to Karwetzky consists of a plate-like upper and lower jaw part, which are held together at the rear by two U-shaped elements made of thick wire. These U-brackets can be bent to move the lower part against the upper part. This means that even strong backslides can be treated with just one device, and with modified brackets, a push back or a pivoting of the lower jaw can be set instead.
- The Teuscher activator according to Ullrich Teuscher is a variant that combines the activator with a headgear in order to eliminate the negative therapeutic effects of the activator and to achieve better results in profile aesthetics.
- The resilient bit formers according to Bimler are particularly graceful. Your skeletonized lower jaw part can also be readjusted by bending, and the upper jaw part can be designed for expansion (jaw stretching). Bimler discovered that wearing the denture shapers at night had a sufficient effect and attributed this increase in effectiveness to the elasticity. This is confirmed by other elastic braces that are easier to manufacture with today's materials, such as: B. assembled rail activators .
- The newer Maxillator according to Hangl is a hybrid (mixed form) of the resilient Bimler upper part and the stable lower part of the U-bracket activator including brackets.
- However, activators can now also be made thin-walled and delicate, although they are still mostly made of acrylic glass (PMMA) . Such small activators are hardly noticeable in the mouth, hardly interfere with speaking and leave the roof of the mouth and also the front palate free, against which the tongue should rest.
The difference between activator and bionator became fluid, and there are mixed forms. The range of applications of functional orthodontics is v. a. supplemented by the separately developed function controller.
Construction and mode of operation
The activator is an orthosis : it gives incorrectly growing bones and joints (of the jaw) an overcorrected posture in order to “guide them correctly” in the literal sense of “orthopedics”. To produce an activator, this corrective jaw position is imprinted as a so-called construction bite in a wax strand, in addition to plaster models of the jaw. In this position, the chewing surfaces are molded in plastic on the activator, which gives the wearer a feeling of clenching despite the shifting of the jaw. While the actual activator effect is painless, the part of the mucous membrane inside the jaw can cause pressure points. These zones would then have to be ground out.
The literature does not give a uniform recommendation for the extent of the fundamental construction bite. Against the back of the lower jaw, you will find information such as “aim for a head bite”, “two thirds of the maximum feed distance” or “not more than 4 to 5 mm, if more correction is required, plan a follow-up copy”. FKO devices with adjustable feed such as the above avoid this ambiguity. Another construction bite parameter is the bite opening. Here it is recommended to open the bite more strongly in patients with a more vertical skull development than in those with more horizontal growth, but to choose their (horizontal) advancement less. Strong bite opening and strong advancement at the same time would also make the activator too uncomfortable.
The chewing surface of the activator should be grinded out where teeth should grow into healthy teeth. With a deep bite, the lower premolars are often too deep, while with an open bite the incisors are supposed to grow together. With well-interlocked lower jaw rests, the upper jaw is often too narrow for the normal lower jaw position. The position of the lower jaw determines the position of the tongue and the tongue determines the development of the upper jaw. In old literature, the lower and upper jaw are sometimes compared with a foot in a slipper. Activators also normalize the position of the tongue, but for a more targeted treatment, activator screws have been developed that only spread the upper jaw part of a three-part activator. However, newer multi-unit FKO devices that are more delicate also make this possible.
There are also different statements in the literature as to whether the activator should click into place on the lower dental arch or lie loosely in the mouth. Due to the bulging of the lower molars, it locks into place if you don't drag them free. There are also inconsistent observations as to whether activators tilt the lower incisors or not. This can be related to not locking or locking into place: whether the lower jaw can fall back while sleeping and these teeth unintentionally press against the activator edge, or not.
A regularly worn activator orients the masticatory muscles after a short time so that the lower jaw is held further forward by itself. This training effect is also called the Sunday bite and disappears again when the activator is stopped. With it, a daily wearing time of 12 to 15/24 hours is usually sufficient because there is a residual effect on the jaw joints in the remaining hours. After about 6 months, the desired jaw correction begins to manifest itself in the hard tissue.
Satravaha described success through additional targeted physiotherapy in the more difficult progeny treatment with modified activators in 1993.
literature
- German-language textbooks on orthodontics, especially older ones, section functional orthodontics
Individual evidence
- ^ GD Singh, BS Thind: Effects of the headgear-activator Teuscher appliance in the treatment of class II division 1 malocclusion: a geometric morphometric study . In: Orthodontics & Craniofacial Research . tape 6 , no. 2 , 2003, ISSN 1601-6343 , p. 88-95 , doi : 10.1034 / j.1600-0854.2003.c245.x ( wiley.com [accessed July 4, 2019]).
- ↑ Satravaha, S. (1993): Early treatment of progeny cases in Thailand. Prakt Kieferorthop 7: 23-30
