The activator is the first internationally recognised ‚functional orthodontic’ dental brace and was first introduced by Viggo Andresen in 1935. The removable activator is a brace that encompasses both teeth brackets simultaneously (double brace). It is manufactured in such a way that it repositions the lower jaw through the bite. For a long time many orthodontists believed that they could actually control muscle function with such a device and with it the growth of the lower jaw. However, bringing about any change in muscle function by using a brace is the stuff of legends and we know today that it is not really possible to influence this growth by much more than one millimeter. At the end of the day, the therapeutic effects of the activator are no greater than that of the fixed brace, but the treatment lasts considerably longer and the results are generally not significant unless a fixed brace is subsequently used.
Since the activator significantly hampers speech and is therefore socially irksome, most patients do not wear this brace for long enough, so that 30% – 50% of all treatment ends in failure. Even if this has proven Andresen’s hypotheses to be false, the activator is still one of the most popular braces in Germany, at least as far as orthodontists are concerned, but less so with younger patients. They resist this awkward appliance and only wear it at night when it is highly unlikely to have any real effect.

A Little Picture Gallery of Horrors


In the fifties and sixties every self-respecting German orthodontist introduced their own double brace which was really nothing more than a variation on the activator, yet it offered no significant differences in efficacy. One such appliance is Balter’s Bionator, which is a slightly smaller activator and featured a Klammt elastic activator, a Bimmler bite-former (both skeletonized activators with a lot of wire components) and Karwetzky’s U-Clamp Activator, a two-piece brace connected with wire to a U-shaped activator. The list of such braces goes on ad infinitum and is more of a demonstration of personal vanity than it is an enrichment of orthodontics. One outsider in this series is Fränkel’s Function-regulator which in the oral vestibule just consists of wire and plastic plates. In spite of being an awkward and highly inefficient appliance, it has its fans amongst orthodontists.

Whilst all the appliances mentioned above are outdated and should no longer be used for children, the one big exception is the Headgear-Activator combination. A number of authors have introduced their own Headgear-Activator combinations (Teuscher-Activator, Van Beek-Activator, Bass-appliance, Dynamax, Hansaplate, etc). These appliances have an extra active advantage because of the headgear and strap and are so efficient that almost every distoclusion can be treated and corrected within a reasonable period of time even if the appliance is just worn at night.

Activator with strap

Patient wearing an Activator with headgear

Similarly, another double-brace appliance that is still viable today is the Twinblock, which admittedly has to be worn all day but that means that the treatment timespan is very short. The Twinblock is the standard appliance for distoclusion patients in Great Britain. If the Twinblock is worn all day it is highly effective and can correct every distoclusion within 9 – 12 months – it would take years to do this with an Activator! However, like all removable braces, the Twinblock also has the disadvantage of having a high failure rate.