Dental Problems

Posterior Cross bite- Overview

Pulpitis - Diagnosis and Treatment of PulpitisA posterior cross bite is an abnormal buccolingual relationship of a tooth or teeth in the maxilla or mandible, or both, when the two dental arches are brought into a centric occlusion. In this article there is a brief discussion on the posterior cross bite. Read on to know more.

Posterior cross bite:

  1. Ectopic eruption of the permanent first molar.
  2. Prolonged thumb or finger sucking.
  3. Prolonged retention of primary teeth.
  4. Occlusal interferences
  5. Skeletal: They may be caused due to the following:
    • a. Deficient lateral growth of the maxilla as seen in cleft palate repair.
    • Increased growth of mandible or
    • Combination of both.

Modalities for the correction of posterior cross bite

The important consideration is to determine whether the cross bite is unilateral or bilateral, and which has got a functional component to it. Following points can be can be considered in differential diagnosis:

  • Study models using a waxbite can be an asset to diagnosis. It also helps in detecting abnormal inclination of teeth, symmetry of the dental arches to certain extent the growth pattern.
  • Cephalometric analysis will show gross skeletal abnormalities.
  • An occlusal radiograph can also be taken preoperatively to compare with the post-operative x-ray.
  • The midline should be checked to determine if unilateral mandibular shift is present.
  • A facebow transfer may sometimes confirm the functional shift, however, by observing the patient closing from rest into centric occlusion, a lateral deviation can be frequently observed.

Corrective measures and appliances:

  • a. Occlusal equilibrium:

    A dental bilateral lingual cross bite in the primary or mixed dentition may be simply corrected by removing occlusal interferences, usually in the cuspid areas. However, this may sometimes need to be accompanied by some appliance.

  • b. Removable W-arch appliance:

    This appliance should be limited to only bilateral dental cross bite conditions because of the reciprocal action. Caution should be exercised since a precise control of the force being applied to the teeth is difficult.

  • c. Cross elastic appliance:

    Cross elastic therapy is useful in correction of dental unilateral cross bite involving one or two teeth. Bands are adapted and cemented to the teeth involved. A hook or button spot is welded to the bands. The two teeth are engaged by means of an elastic. Reciprocal movement of both the upper and lower teeth occurs. The disadvantages are patient cooperation and increased armamentarium.

  • d. Removable Hawley appliance:

    A removable maxillary Hawley appliance with an offset jackscrew embedded in the acrylic resin, may be useful in the correction of two teeth unilateral dental cross bite. The appliance offers good control of the amount and direction of force being applied to the teeth. The activation of the screw is done at ¼ turn every week.
    When the cross bite is corrected, the appliance should be worn in passive retention for an additional three to six months as a retentive appliance.

Skeletal correction:

It may be carried out in two forms:

  • a. Slow palatal expansion
  • b. Rapid palatal expansion

The various appliances used include the following:

Minnesota expander

Hyrax jackscrew

Fixed split palate acrylic appliance

The above article discusses about the

posterior cross bite

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