Cross bite

Introduction

Cross bites are a deviation of the normal bucco-lingual relationship of the teeth of one arch with those of the opposing arch. Graber defined cross bites as a condition where one or more teeth may be malposed abnormally, buccally or lingually or labially with reference to the opposing tooth or teeth.

Under normal circumstances the maxillary arch overlaps the mandibular arch both labially and buccally. But when the mandibular teeth, single tooth or a segment of teeth, overlap the opposing maxillary teeth labially or buccally, depending upon their location in the arch, a cross bite is said to exist.

Unilateral Posterior Crossbite

Classification

Anterior cross bites

Anterior cross bites is basically a condition where a reverse overjet is seen. Anterior cross bites can be further classified according to the number of teeth involved as:

• Single tooth cross bite
• Segmental cross bite

Posterior cross bites

According to the number of teeth involved.

• Single tooth cross bite
• Segmental cross bite

According to the existence of the cross bite on one side or both the sides of the arch.

• Unilateral cross bite
• Bilateral cross bite

According to the extent of the cross bite.

• Simple posterior cross bite: This type of cross bite is seen most frequently in clinical practice. Here the buccal cusps of one or more posterior teeth occlude lingual to the buccal cusps of the mandibular teeth.
• Buccal non-occlusion: Here the maxillary teeth palatal cusp of the occlusion and are placed buccal to the buccal cusp of the mandibular posterior

teeth. The condition is also known as scissors bite.

• Lingual non-occlusion: Here the maxillary posterior tooth or teeth are placed completely palatal to the lingual aspect of the mandibular posterior teeth, i.e. the buccal cusp of the maxillary tooth is palatal/lingual to the lingual cusp of the mandibular posterior teeth.

Based on the location of the etiologic factors.

• Dental cross bites: They are generally single tooth or sometimes segmental cross bites. These usually result from arch length discrepancy or an

abnormal path of eruption. These are usually not accompanied by any threat to general health of the patient, the problems arising due to such cross bites are periodontal or esthetic in nature.

• Skeletal cross bite: These include those cross bites, which are primarily due to mal-positioning or malformation of the jaws. These can be inherited (e.g. Cross bites seen in patients with Class III skeletal pattern), congenital (e.g. cleft lip and palate cases) or arising due to trauma at the time of birth (e.g. unilateral ankylosis of the TMJ) or later in life. They are capable of causing appreciable damage to a person’s health and personality as the appearance may be compromised to a larger extent.
• Functional cross bites: These cross bites are usually caused due to the presence of occlusal interferences during the act of bringing the jaws into occlusion. These can be caused by the early loss of deciduous teeth, decayed teeth or ectopically erupting teeth. If not corrected early, these can ultimately lead to skeletal cross bites.

Etiology

• Anomalies of number:

1. Supernumerary teeth
2. Missing teeth

• Anomalies of tooth size
• Anomalies of tooth shape
• Premature loss of deciduous and / or permanent teeth
• Prolonged retention of deciduous teeth
• Delayed eruption of permanent teeth
• Abnormal eruptive path
• Ankylosis

Correction of Anterior and Posterior Cross bites

Cross bites—anterior or posterior should be corrected as soon as they are detected. It may be better to treat them as the permanent teeth begin to erupt into the oral cavity. The child may be too young and uncooperative at the deciduous dentition stage. Moreover, it is easier to bring about changes in the mixed dentition stage.

If the cross bite is not treated in time it could lead to a skeletal malocclusion, which would require corrective orthodontic treatment later on. Some of the common appliances used in the correction of cross bites are—tongue blade therapy, inclined planes , composite inclines, Hawley’s appliance with Z-spring , quad helix appliance , medium , mini and microscrews embedded in acrylic appliances, etc.

Cross bite Resources
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