THE EDITOR'S CORNER
Removable appliances have been used in orthodontics for many years. The addition of an anterior inclined bite plane or the use of extraoral traction for reinforcing anchorage, is a well-recognized procedure. The lip bumper used in conjunction with fixed appliances for the purpose of increasing lower molar anchorage is also a well-recognized appliance. This paper is a preliminary report which serves to introduce the concept of the Aktionator appliance. The Aktionator combines a simple upper removable appliance with the lower lip bumper.
The Aktionator Appliance
The appliance consists of two parts: an upper Hawley and a lower lip bumper that can be connected to tubes on the cribs of the upper appliance (Fig. 1). It is essentially a simple functional appliance that makes use of the lower lip musculature. It may be constructed in cold cure acrylic without the use of an articulator and with the minimum of wire work. It is well tolerated and easily handled by both the patient and the operator. Chairside time may be kept to a minimum.
According to the requirements of each case, many modifications can be made to the basic design of the appliance, e.g. expansion screws or finger springs may be incorporated (Fig. 2). An anterior inclined bite plane is usually added to further reinforce anchorage and encourage bite opening together with labial tipping of the lower incisors.
A more comprehensive study is in progress to determine by means of cephalometric analysis the changes produced by the appliance on the dentoalveolar and skeletal component of the orofacial complex. At present it would appear that certain force systems are active when the appliance is worn:
1. Jaws and alveolar ridges. There is an intrusive and retrusive force on the maxilla produced by the anterior bite plane together with the lip bumper. At the same time, the mandible is rotated clockwise and positioned anteriorly, causing the condyle to leave the condylar fossa.
2. Teeth. There is a labially directed force on the lower anteriors caused by the inclined bite plane as well as by the tongue. The lower anteriors are also shielded from the action of the lower lip by the lip bumper. The upper anteriors will tip in a palatal direction under influence of the labial arch of the upper appliance.
The molars and premolars will tend to erupt further due to the presence of an anterior bite plane which at the same time may be responsible for a certain amount of intrusion of the lower anteriors.
Construction
Impressions are taken with alginate material in the normal way and a bite registration is taken in retruded contact position. The models are trimmed like routine study models.
The models, held in occlusion, are placed with their backs on a card and the outline of the upper and lower bases and sides are drawn with a sharp pencil (Fig. 3a). The lower model is then moved down so that the posterior teeth are 2-4mm apart, keeping the models in the same vertical plane (Fig. 3b). The position of the lower model is again marked on the card (Fig. 3c).
The upper removable appliance is then constructed. The Adams cribs are made from 0.8mm. (.032") stainless steel wire with a tube of 1.12mm (.045") internal diameter soldered to the bar of each crib. The acrylic base of the appliance is completed and the bite plane constructed so that the lower anterior teeth make contact with the plane while the models are in the open position on the card.
The lip bumper is constructed from 1.12mm (.045") wire with an activation loop in the first premolar region. The acrylic portion should be kept low in the labial sulcus, about 2-3mm from the alveolar mucosa.
Special Considerations
The upper appliance is worn all the time, but the lip bumper is taken out when eating. The importance of the lip bumper as the active component is stressed.
The patient is seen every 4-6 weeks and the normal checks are made for retention, ulcerations, etc. The lip bumper is also activated forward and down 1mm at every appointment.
The ideal type of case to treat with this appliance should have the following characteristics:
(1) Low mandibular plane angle (SN-GoGn).(2) Labial inclination of the maxillary incisors.(3) Lingual inclination of the lower incisors causing them to be behind the APo line, together with mild crowding in the anterior segment.(4) The patient should be in the preadolescent growth spurt, with good growth potential.(5) Favorable tooth size to jaw relationship.
Case Report
The patient was a boy aged 11 years 1 month and presented (Fig. 4a) with an Angle Class II Division I with a full Class II molar relationship on the right and a cusp-to-cusp relationship on the left. There was an excessive overbite and an overjet of 12.5mm.
The patient was treated under supervision by undergraduate students. After four months' treatment, both the overbite and overjet was reduced (Fig. 4b).
After ten months, a full Class I molar relationship was achieved on both sides (Fig. 4c, Fig. 5, and Table 1). No extraoral traction was used. The inclination and alignment of the lower incisors still require further treatment, and it is possible that the case will be finished with full fixed appliance therapy.
The main objective of treatment with the Aktionator was to achieve a Class I relationship of the buccal segments without the use of extraoral traction.
In certain cases, provided individual tooth alignment is satisfactory, the treatment may be completed without the use of fixed appliances or extraoral traction. In more complex cases, the Aktionator may be used only as a first stage in treatment for the correction of interarch relationships. In either case, it is a useful addition to the list of available removable and functional appliances.
