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Types of Malocclusion - Topic Overview

The term "malocclusion" (poor bite) refers to a number of possible conditions. The most common are:

  • Upper protrusion (overjet). In an upper protrusion, the upper front teeth are pushed outward (buck teeth). A small lower jaw may be the cause. Pacifier use or thumb-sucking can also create this condition by pushing the teeth outward, sometimes causing the roof of the mouth to change shape (upper palate).
  • Spacing or crowding problems. Too much or too little room for the teeth can cause spacing or crowding problems. Crowding can prevent permanent teeth from coming in properly or at all (impaction).
  • Misplaced midline. In people who have a misplaced midline, the front center line between the upper front teeth doesn't match up with the center line of the lower front teeth.
  • Open bite. Although the molars fit together in a person who has an open bite, the upper and lower front teeth don't overlap. This creates an opening straight into the mouth. An open bite can also be present on one or both sides of the mouth.
  • Overbite. In a person who has an excessive overbite, the upper front teeth reach too far down over the lower front teeth and, in severe cases, can cause the lower teeth to bite into the roof of the mouth.
  • Underbite. An underbite is present when the lower front teeth are farther forward than the upper front teeth.
  • Cross bite. A cross bite occurs when any or all of the upper teeth fit into the wrong side of the lower teeth.
  • Rotation. Rotation is present when a tooth turns or tips out of its normal position.
  • Transposition. Transposition occurs when teeth grow (erupt) in one another's place.

A normal fit is when the upper teeth are slightly forward of the lower teeth. Malocclusion camera.gif, when there isn't a normal fit, is classified by how the upper and lower teeth fit together. The bones of the jaw are also checked for proper position in relation to the teeth.

  • Class I. Although the upper and lower molars are properly positioned, the teeth are crowding together or have too much space. Cross bites, rotations, and overlapping can also occur in severe cases.
  • Class II. The lower molars fit the upper molars but are positioned toward the throat, drawing the chin back.
  • Class III. The lower molars are far forward and do not fit into their corresponding upper molars. This arrangement creates a jutting jaw and jutting lower front teeth, which are in a cross bite with the upper teeth.

A jaw structure problem that children are born with can cause malocclusion. Malocclusion can also cause the jaw joint to move out of place.

    This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http:// cancer .gov or call 1-800-4-CANCER.

    WebMD Medical Reference from Healthwise

    Last Updated: January 02, 2013
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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    Only 18.5% of Americans never floss. You are missing out on a simple way to make a big difference in the health of your mouth. Regardless of how well you brush, plaque still forms between your teeth and along your gums. Floss removes food trapped between the teeth and removes the film of bacteria that forms there before it turns to plaque, which can cause inflamed gums (gingivitis), cavities, and tooth loss. Try flossing just one tooth to get started.

    You are one of 31% of Americans who don't floss daily. You are missing out on a simple way to make a big difference in the health of your mouth. Regardless of how well you brush, plaque still forms between your teeth and along your gums. Toothbrush bristles alone cannot clean effectively between these tight spaces. Flossing removes up to 80% of the film that hardens to plaque, which can cause inflamed gums (gingivitis), cavities, and tooth loss. Aim for 3 more days!

    You are one of 31% of Americans who don't floss daily, but you're well on your way to making a positive impact on your teeth and gums. Regardless of how well you brush, plaque still forms between your teeth and along your gums. Toothbrush bristles alone cannot clean effectively between these tight spaces. Flossing removes up to 80% of the film that hardens to plaque, which can cause inflamed gums (gingivitis), cavities, and tooth loss. Aim for all 7 days!

    Only 50.5% of Americans floss daily, and good for you that you are one of them! Regardless of how well you brush, plaque still forms between your teeth and along your gums. Toothbrush bristles alone cannot clean effectively between these tight spaces. Flossing removes up to 80% of the film that hardens to plaque, which can cause inflamed gums (gingivitis), cavities, and tooth loss. Congratulations on your good oral health habit!

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    American Dental Association, Healthy People 2010

    This tool is intended only for adults 18 and older.

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