Open Bite Prescription

  • Easy: Less than 2.5 mm is very predictable (better if we do not need posterior intrusion)
  • Moderate: 2.5 mm with less than 1 mm of posterior intrusion
  • Complex: more than 2.5 mm (auxiliary techniques needed)

POSTERIOR TEETH INTRUSION

Place 4 mm wide occlusally beveled rectangular attachments on the uppers 4’s and 5’s to support the intrusion of the molars.

Here’s one more tip—overtreat the intrusion of the molars to a 2 mm posterior open bite, as aligners can routinely underperform in this area.

Class II open bite. Posterior intrusionIntrude the lower or upper tooth (6 or 7) and place class II elastics from the intruded tooth. Place attachments on other teeth.

ANTERIOR TEETH EXTRUSION

  1. Anterior extrusion needs space (plan IPR)

2. A strong posterior anchorage is needed for effective extrusion of the upper incisors. This anchorage will be provided by:

  • Not moving the posterior lateral zone during the anterior extrusion
  • Horizontal 5mm attachments on 4s/6s
  • Four lingual attachments on upper incisors during expansion to increase anchorage (horizontal beveled to gingival attachments).
  • Optimized attachments or conventional vertical in canines

Elastics for anterior teeth extrusion

Triangle elastics 3/16 4-6oz 24 hours (upper canines, lower canines and premolars)

Staging for open bite cases

  • Start the correction as soon as possible by transversal development of both upper and lower arches: this will provide space for the retrusion of the incisors (relative extrusion)
  • During the expansion, it is advisable to use attachments to the lingual surface of the incisors to increase anterior anchorage.
  • Postpone absolute extrusion till the end: do not move molars and extrude the upper incisors maintaining torque, remove horizontal beveled to gingival attachments in lingual and exchange them for optimized extrusion attachments by labial (ask for a reciprocal movement of anterior extrusion and posterior intrusion).
  • Minor cases might benefit from ‘Chewies’
  • Temporary anchorage devices (TADs) should be used to intrude the posterior zone (in cases of a gummy smile) or when the open bite has a skeletal pattern.

RELATIVE EXTRUSION

Relative extrusion can be obtained after expansion if the space opened by the expansion is used to retrocline the incisors:

  • Expansion changing posterior torque + simultaneous incisor retraction + Class II elastics to assist incisors retraction
  • Reciprocal movement of posterior intrusion 0.5mm + anterior extrusion at the end of treatment
  • Optimized attachments (or horizontal beveled to gingival attachments) for upper incisors extrusion
    • Anchorage attachments UA4/5
    • Optimized/vertical attachment in canines

POSTERIOR INTRUSION

  • Posterior intrusion of maxillary and mandibular teeth with consequent upward and forward mandibular closure (anticlockwise rotation of the mandible). This is visualized in the ClinCheck as a virtual jump.

PREDICTABILITY OF VERTICAL MOVEMENTS

Image: pocketdentistry.com

Instructions to the technician:

  1. Amount of intrusion/extrusion (millimeters – reference, plane or tooth)
  2. Sequence anterior movements (first – derotate, lastly – intrude or extrude anterior teeth before retraction)
  3. Elastic placement
  4. Lower incisors (do not increase incisors display if not needed)