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Classification and external resources
ICD-10 K07.4
ICD-9 524.4
MeSH D008310

A malocclusion is a misalignment of teeth and/or incorrect relation between the teeth of the two dental arches. The upper arch is called the maxilla and the lower is called the mandible.



Most people have some degree of malocclusion, although it isn't usually serious enough to require treatment. Those who have more severe malocclusions may require orthodontic and sometimes surgical treatment (orthognathic surgery) to correct the problem. Correction of malocclusion may reduce risk of tooth decay and help relieve excessive pressure on the temporomandibular joint. Orthodontic treatment is also used to align for aesthetic reasons.

Malocclusions may be coupled with skeletal disharmony of the face, where the relations between the upper and lower jaws are not appropriate. In these cases the dental problem is, most of the time, derived from the skeletal disharmony[citation needed].


Malocclusions can be divided mainly into three types, depending on the sagittal relations of teeth and jaws, by Angle's classification method. However, there are also other conditions e.g. crowding of teeth, not directly fitting into this classification.

Many authors have tried to classify or modify Angle's classification. This has resulted in many subtypes.


Angle's classification method

Class I with severe crowding and labially erupted canines
class II molar relationship

Edward Angle, who is considered the father of modern orthodontics, was the first to classify malocclusion. He based his classifications on the relative position of the maxillary first molar.[1] According to Angle, the mesiobuccal cusp of the upper first molar should rest on the mesiobuccal groove of the mandibular first molar. The teeth should all fit on a line of occlusion which is a smooth curve through the central fossas and cingulum of the upper canines, and through the buccal cusp and incisal edges of the mandible. Any variations from this resulted in malocclusion types. It is also possible to have different classes of maloclusion on left and right sides.

It is estimated that approximately 18% of the United States population suffers from an over sided malocclusion, while only 11% suffer from an under malocclusion.[citation needed]

  • Class I: Here the molar relationship of the occlusion is normal or as described for the maxillary first molar, but the other teeth have problems like spacing, crowding, over or under eruption, etc.
  • Class II: (retrognathism, overjet) In this situation, the upper molars are placed not in the mesiobuccal groove but anteriorly to it. Usually the mesiobuccal cusp rests in between the first mandibular molars and second premolars. There are two subtypes:
    • Class II Division 1: The molar relationships are like that of Class II and the anterior teeth are protruded.
    • Class II Division 2: The molar relationships are class II but the central are retroclined and the lateral teeth are seen overlapping the centrals.
  • Class III: (prognathism,negative overjet) is when the lower front teeth are more prominent than the upper front teeth. In this case the patient very often has a large mandible or a short maxillary bone.

Crowding of teeth

Crowding of teeth is where there is insufficient room for the normal complement of adult teeth.


Crowding of teeth is recognized as an affliction that stems in part from a modern western lifestyle. It is unknown whether it is due to the consistency of western diets[citation needed], a result of mouthbreathing[citation needed]; or the result of an early loss of deciduous (milk, baby) teeth[citation needed] due to decay.

Other theories state that the malocclusion could be due to trauma during development that affects the permanent tooth bud, ectopic eruption of teeth, supernumerary teeth, and early loss of the primary tooth[citation needed].


Crowding of the teeth is treated with orthodontics, often with tooth extraction, dental braces, followed by growth modification in children or jaw surgery (orthognathic surgery) in adults.

Other conditions

Other kinds of malocclusions are due to vertical discrepancies. Long faces may lead to open bite, while short faces can be coupled to a deep bite. However, there are many other more common causes for open bites such as tongue thrusting, thumb sucking, etc, and likewise for deep bites.

Malocclusions can also be secondary to transversal skeletal discrepancy or to a skeletal asymmetry.


Oral habits and pressure on teeth or the maxilla and mandible are etiological factors in malocclusion [2] [3].

In the active skeletal growth [4] mouthbreathing, finger sucking, thumb sucking, pacifier sucking, onychophagia (nail biting), dermatophagia, pens biting, pencils biting, abnormal posture, deglutition disorders and other habits greatly influence the development of the face and dental arches [5][6][7][8][9].

Pacifier sucking habits are also correlated with otitis media [10][11].

Dental caries, periapical inflammation and tooth loss in the deciduous teeth alter the correct permanent teeth eruptions.


  1. ^ "Angle's Classification of Malocclusion". Archived from the original on 2008-02-13. Retrieved 2007-10-31. 
  2. ^ Klein ET. (1952). "Pressure Habits, Etiological Factors in Malocclusion". Am. Jour. Orthod. 38(8): 569-587. 
  3. ^ Graber TM. (1963). "The “Three m’s”: Muscles, Malformation and Malocclusion". Am. Jour. Orthod. 49: 418-450. 
  4. ^ Björk A., Helm S. (1967). "Prediction of the Age of Maximum Puberal Growth in Body Height". Angle Orthod. 37(2): 134–143. 
  5. ^ Brucker M. (1943). "Studies on the Incidence and Cause of Dental Defects in Children: IV. Malocclusion". J Dent Res 22: 315-321. 
  6. ^ Calisti LJP, Cohen MM, Fales MH. (1960). "Correlation between Malocclusion, Oral Habits, and Socio-economic Level of Preschool Children". J Dent Res 39: 450-454. 
  7. ^ Subtelny JD, Subtelny JD (1973). "Oral Habits - Studies in Form, Function, and Therapy". Angle Orthod. 43(4): 347–383. 
  8. ^ Aznar T, Galán AF, Marín I, Domínguez A. (2006). "Dental Arch Diameters and Relationships to Oral Habits". Angle Orthod. 76(3): 441–445. 
  9. ^ Yamaguchi H, Sueishi K. (2003). "Malocclusion associated with abnormal posture". Bull Tokyo Dent Coll. 44(2): 43-54. 
  10. ^ Wellington M, Hall CB. (2002). "Pacifier as a risk factor for acute otitis media". Pediatrics. 109(2): 351–352. 
  11. ^ Wellington M, Hall CB. (2008). "Is pacifier use a risk factor for acute otitis media? A dynamic cohort study". Fam Pract. 25(4): 233-6. 

External links

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