Malocclusions

Normal occlusion is when all teeth ( 20 primary and/or 32 permanent ) are accommodated comfortably in an ideal arch form, with a patent airway that matches that patients facial type. Any deviation from the norm is regarded as a malocclusion.

Developing Malocclusions

Any disturbance of the arch form and length i.e. tooth number and size, can trigger a developing malocclusion. 

  1. Poor oral hygiene due to a lack of education of good oral hygiene habits can cause decay and loss of tooth material making teeth smaller. As a result, the arch length decreases affecting eruption of  permanent teeth and triggering a developing malocclusion. 
  2. Early loss of primary teeth from caries or extractions and failure to maintain this space , detrimental oral habits like thumb sucking, mouth breathing, incorrect swallowing, tongue thrusting etc cause under development of arch forms and lack of space for the permanent teeth and developing malocclusion to result. 
  3. When the tongue is not positioned on the palate at rest, when the lips are not together at all times, except when eating or speaking, when the patient is not breathing through their nose and mouth breaths instead, when the patient swallows incorrectly using his muscles of facial expression, when the patient fails to chew a hard balanced fibrous diet 20 to 30 times before swallowing, the arch does not develop to its correct size and is unable to accommodate all the permanent teeth, causing a malocclusion to develop. 

Established Malocclusions

In established malocclusion relates to a misalignment or incorrect relation between the teeth of the upper and lower dental arches when they approach each other as the jaws close. The term was coined by Edward Angle, the “father of modern orthodontics”, as a derivative of occlusion. This refers to the manner in which opposing teeth meet.

Narrow arch forms/flattened arch forms, affect the length of the arch. When permanent molars drift forward due to early loss of the primary molars as a result of caries or early extractions they cause teeth to crowd. This lack of space, establishes the following features of malocclusion: – Narrow arch form, increased overjet (teeth sticking out) cross bites, Anterior open bites, deep bites, Blocked out/impacted canines of premolars, rotated teeth, traumatic occlusion, wear facets on teeth and jaw joint problems

Skeletal Malocclusions

Normally the upper jaw is slightly ahead of the lower by 1 to 4 degree (ANB angle). When the upper and lower jaws are incorrectly related. You will find the following nine skeletal relationships:

1.Normal skeletal class I relationship (1 to 4 degrees ANB)

  • Both the upper and lower jaws are under the nose (N-Point on Jefferson’s anterior arch)
  • Both the upper and lower jaws are behind the nose (behind Jefferson’s anterior arch)
  • Both the upper and lower jaws are in front of the nose (ahead of Jefferson’s anterior arch )

2. Skeletal class II relationship (5 degrees and greater )

  • The upper jaw is too far forward and the lower jaw is in a normal position
  • The upper jaw is normal and the lower jaw is to far back
  • The upper jaw is too forward and the lower is to far back

3. Skeletal class III relationship

  • The upper jaw is to far back and the lower jaw is normal
  • The upper jaw is normal and the lower jaw is to far forward
  • The upper jaw is to far back and the lower jaw is to far forward
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