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Bionator I


Appliance Purpose / Function:

The Bionator I is a removable functional appliance used to treat patients with a Class II malocclusion and a deep bite. While the appliance holds the mandible in a protruded position with acrylic, there is no coverage of the posterior teeth. Instead there are fluted channels angled facially cut into the acrylic that guide the eruption of posterior teeth. This allows for the correction of a deep bite while also expanding the arches dentally. An acrylic cap covers the mandibular incisors and the maxillary incisors contact this cap on a flat plane. This prevents the undesirable eruption of the anterior teeth while also controlling flaring of the mandibular incisors which can occur as a result of the forces exerted on the mandible. There is no acrylic in the palatal vault to allow the proper positioning of the tongue. An omega loop coffin spring joins the two halves across the palate for rigidity and can be activated for lateral expansion of the appliance if an optional expansion screw located on the midline lingual to the lower anteriors is utilized.
Appliance Components:

  • Labial Bow- .040 wire
  • Lingual Arch- .040 wire
  • Coffin Spring- .045 wire

Suggested Materials:

  • Wire: Elgiloy wire
  • Dental Acrylic

Appliance Fabrication Standards:


  • A clear acrylic cap must cover the lower anterior teeth from just above the gingival margin on the labial surface and join with the main body of the appliance on the lingual surface. The incisal surface must be smooth and flat and act as a bite plate for the upper anteriors with all fully erupted upper incisors contacting it. Note: This portion of the acrylic is poured first, trimmed and polished to give access to the incisal cap. Be sure to place a protective coating of wax on the incisal surface before pouring the rest of the appliance as this area is very difficult to access once the bow and lingual arch wire are incorporated into the acrylic
  • The lingual flange on the lower portion of the appliance must cover ¾ of the lower sagittal wall and extend to the distal surface of the terminal molar
  • Acrylic must be kept away form the lingual frenum for patient comfort
  • The palatal pads must cover the upper sagittal walls in a curve from the first bicuspid or primary molar to the terminal molar
  • The upper and lower segments of the appliance are joined by interocclusal acrylic built to the height indicated by the Client’s construction bite
  • There must be no acrylic on the occlusal surfaces of the upper or lower teeth as this interferes with the desired function of allowing the posterior teeth to erupt. Instead, each posterior tooth must have its lingual surface resting against an angled fluted path to guide the eruption process. These paths must be trimmed at a 45 degree angle to the central axis of each posterior tooth and fluted to match the width of each tooth. Additionally, the upper paths must angle slightly towards the posterior and the lower paths must angle slightly towards the anterior
  • All borders must be tapered towards the tissue with a rounded edge (thin, sharp knife-like edges not acceptable)
  • Desired overall thickness is approximately 3mm; however, the acrylic will need to be thicker in the inter-occlusal area to accommodate the features dictated by the design. The Trimmer must make the acrylic as form fitting as possible here to avoid bulkiness and provide for patient comfort


  • The labial bow differs from a Hawley bow in that it is an ideal arch form and doesn’t necessarily contact all of the maxillary anterior teeth. Particularly those anteriors more lingually placed than others in the arch. It still needs to be positioned in the middle third of the anterior teeth. Where it crosses the occlusion distal to the canines, it must be kept out of the embrasure in order to allow for the eruption of the bicuspids
  • The lingual arch wire must contact all of the maxillary anterior teeth on the lingual surface at or below the cingulum except in cases of extreme crowding, in which case only the most lingually positioned teeth should be contacted. Technician should form this portion into as smooth an arch form as possible avoiding sharp bends
  • The coffin spring begins with a 6mm omega loop with the open end facing towards the anterior. It must be positioned in the first molar region on the patient’s midline approximately 2mm off of the tissue. The transpalatal arms of the coffin spring must align with the mesial edge of the first molars and extend laterally out of the loop. They must be contoured to the shape of the palate and kept 2mm off of the tissue. At a point approximately 3-4mm below the gingival margin the wire must be bent into a 90 degree angle and extend distally to the distal edge of the first molars. At this point another 90 degree bend must be made towards the midline and the wire clipped at about 2mm