Bionator appliance is an Orthodontic functional appliance that was used to correct different malocclusions in orthodontics. The appliance was developed by Wilhelm Balters and it was designed to be a daytime appliance and less bulky compared to the Activator appliance. The appliance was primarily designed to be used in Class 2 Division 1 malocclusions. Bionator appliance was created due to the fact that 50 years of use of Activator appliance made it to too bulky for patient's to be compliant with their orthodontic treatment.
This appliance was developed by Wilhelm Balters in 1950s. The idea behind developing this appliance was to increase patient’s comfort and facilitate daytime wear to increase functional use of appliance. Thus the appliance could be used both night and day time. This appliance was developed at the same time as the Bimler Appliance which was known as the skeletonize version of Activator appliance.
Balters believed that tongue is the center of reflex in the oral cavity. This appliance was also loose fitting which allowed children to speak normally immediately compared to activator appliance which took a long time for patients to get adjusted with their pronunciation. He believed that any abnormal activity of the tongue could lead to deformation of the dental arches and mandibular growth. Thus Balters believed that the equilibrium between the tongue and the circumoral muscles was responsible for any normal and abnormal malocclusions.
This appliance does not take make allowances for facial pattern and growth direction, like activator does. It is believed that high construction bite could impair tongue function and patient can develop tongue thrust habit. Myotatic reflex activity with isotonic muscle contraction is stimulated and this loose appliance works with kinetic energy, just like activator appliance. Bionator focuses on tongue and Frankel appliance focuses on neuromuscular component of the mouth.
The standard appliance was used for treatment of Class II division I correcting the backward position of the tongue. It was also used for treatment of narrow dental arches of Class I to stimulate tongue function and to increase the volume or mass of the tongue and achieve lip closure.
The appliance was designed to correct the forward positioning of the tongue by bringing the tongue backward. Thus, the palatal bow is curved mesially as opposed distally in traditional. This allows tongue to fall back and encourage the forward growth of the maxillary area. In this type of appliance, the acrylic is trimmed behind lower teeth by 1mm to allow lingual tipping of lower incisors.
This appliance is constructed to correct the abnormal position of the gonue. Thus, the palatal and vestibular wires are same as traditional appliance. The labial bow is placed at the height of correct lip closure to stimulate lip to achieve a competent seal. The construction bite is as low as possible.
This modification was done by Erich and Annette Fleisher. In this appliance the acrylic was reduced in size and a lower bite plane was included which was made out of metal wires to correct the deep bite. The transpalata bar opens in the distal direction as Class 3 appliance. It had separate maxillary and mandibular labial bow wire.
The appliance consists of parts belowAcrylic - The acrylic in the lower arch is a horseshoe shaped acrylic lingual plate extending from distal of last erupted molar. In the upper part, posterior lingual extensions covered the premolar and molar areas. Anterior portion is open canine to canine to allow proper tongue function.
Labial Bow - This wire was placed 1mm away from front incisors and it runs from canine to canine anteriorly. Posteriorly, it runs from distal of 1st molar where it becomes vestibular wire with buccinator loops
Buccinator Loops - The loops were designed to keep away soft tissue of cheeks to prevent the inhibitory influence of the muscle.
Palatal Bar - The bar emerges from acrylic and forms a loops and inserts on opposite side of arch. The wire is 1mm away from palate, with the loop toward distal of the arch. It is designed to touch dorsal surface of tongue and postures tongue forward.
Since the volume of the appliance is already reduced from activator, the anchorage of this appliance was a major concern. Balters introduced the following terms when it comes to trimmingArticular Plane
Ascher in 1968, proposed different types of anchorage based on deciduous teeth.Dental Arches are originally well aligned
Mandible is in posterior rest position
Skeletal discrepancy is not severe
Labial tipping of upper incisors is not evident
Some of the disadvantages of this appliance is easier distortion when in the mouth. If the appliance is used in a patient with severe skeletal deformity, then the change of tongue function is secondary compared to the skeletal deformity. The indications for this appliance are reduced due to no allowance for vertical component, unlike other appliances such as Twin-Block or Activator.