The cross bite
Assit. Lec. Dr. Ahmed Muhsin AL-Mayali
B.D.S M.Sc. Ortho.
The cross bite
2- Classification of Crossbite
3-Etiologyof cross bite
4-Treatment of cross bite
At the end of the lecture we hope:
1-know the crossbite.
2-give an example of the crossbite
3-define the crossbite
4-mention the types of the crossbite
5-comparision between its types
6-give an opinion about the best treatment method
1-What is cross-bite?
Definition of American Association of Ortodontists Glossary: An abnormal relationship of a tooth or teeth to the opposing teeth, in which normal labiolingual relationships are reversed.
Deviations from ideal occlusion in the transverse plane of space in the posterior and/or in the sagittal plane of space in anterior .
2-Classification of Crossbite
A malocclusion in which one or more of the upper anterior teeth occlude lingually to the mandibular incisors; the lingual mal positions of one or
more maxillary anterior teeth in relation to the mandibular anterior teeth when the teeth are in centric relation occlusion.
The Anterior Crossbite Involves one or more incisors or canines and Usually involves single tooth Either of dental or skeletal Origin.
An occlusal disorder where one or more of the upper incisors are in reverse overjet relative to the lower arch, which means that the upper incisors are lingual to the lower incisors, is called anterior crossbite. If all four upper incisors (or at least both upper central incisors) are lingual to the lower incisors it is called negative overjet. Inversion of incisors usually refers to a situation where one to three individual incisors are in anterior crossbite.
One or more posterior teeth locked in an abnormal relation with the opposing teeth of the opposite arch; can be either buccal or a lingual cross-bite and may be companied by a shift of the mandible.
3- Etiologyof cross bite
The etiology is dentoalveolar, e.g. crowding in the upper arch or a retained primary incisor, which leads to one or more palatally displaced incisors from the arch.
Anterior crossbite may be due to abnormal inclination of the maxillary and mandibular incisors, occlusal interferences, or skeletal discrepancies of the maxilla and/or mandible
Individuals with Class III malocclusion may have combinations of skeletal and dento-alveolar components
anterior crossbites are caused by local environmental factors. These factors, such as retained primary teeth, odontomas, trauma, crowding could change the normal path of eruption allowing the upper incisors to erupt palatally and /or the lower incisors to erupt labially
Posterior Crossbite May involve single tooth or multiple teeth and Unilateral with True maxillary arch constriction And the Functional crossbite is Bilateral.
Skeletal, muscular or dental factors, or a combination of these factors
Multi-factorial phenomena related to genetic, congenital, environmental,
functional, or habitual origins.
Skeletal crossbites may be caused and/or influenced by habits and
other localized deforming factors, Digit or pacifier sucking habits ,Oral respiration, Low tongue position, Tongue thrusting.
Class III skeletal relationship May present as anterior crossbite ,Severe Class II skeletal relationship May pressent as posterior crossbite.
Insufficient maxillary arch width may cause Unilateral posterior crossbite or Bilateral posterior crossbite.
the majority of anterior crossbite a singletooth or a few teeth and are caused by dental factors:
1-A congenitally-caused eruption pattern of the maxillary anterior teeth.
2-Trauma to the primary dentition which leads to the displacement of the
primary or permanent tooth bud
3-Trauma to permanent teeth that result in their being displaced by luxation
4-Delayed eruption of the primary dentition and Supernumerary teeth.
5-An over-retained, necrotic, pulpless primary tooth or root.
6-A sclerosed bony or fibrous tissue barrier caused by premature loss of a primary tooth
7-Biting of the upper lip.
8-A repaired cleft lip or palate.
9-Inadequate arch length.
Varies significantly from one ethnic group to another
Prevalence of posterior crossbite Asians or Africans < Caucasians
Prevalence of Class III malocclusion Asians > Africans or Caucasians
Anterior crossbite in 10% of Japanese population in 3% of US population
A static reproducible position of the mandible in which there is maximal contact of the inclined planes of the opposing teeth with balanced,
unstrained relationship in the temporomandibular articulation.
Centric Relation (CR)
A gnathologic term, signifying optimal condyle- articular eminence–glenoid fossa relationships, determined by muscle balance and not by tooth inercuspation. Changing concepts no longer accept the most retruded, rear-most or hinge axis definition, originally derived from prosthetic articulators. To the orthodontis, the condylar position can vary
somewhat, but is generally recognized as high on the posterior surface of the articular eminence. Lack of harmony of centric occlusion and centric
relation status is particularly important in diagnosis of TMD problems.
4-Orthodontic treatment for crossbites
Early treatment of posterior crossbites appears to prevent them from being passed on to the adult dentition. However Posterior crossbite’ occurs when the top back teeth bite inside the bottom back teeth. It is unclear what causes posterior crossbites and they may develop or improve at any time from when the baby teeth come into the mouth to when the adult teeth come through. If they affect one side of the mouth the lower jaw may need to move to one side to allow the back teeth to meet together. This movement may have long term effects on the growth of the teeth and jaws. Several treatments have been used to correct posterior crossbites :
1-Fixed orthodontic appliance.
2-screw appliance .
Text book of orthodontics , Gurkeerat Singh 2nd Edition 2007.
Singh G. :Textbook of Orthodontics ,2007.
Proffit WR, Fields HW, Server DM. : Contemporary orthodontics, 4th edition, Reed Elsevier , 2013.