Ideal Occlusion & Three Different Classifications of Bad Bites (Malocclusion)
Malocclusions can be divided mainly into three types, depending on the condition. However, there are also other conditions e.g. crowding of teeth, not directly fitting into this classification which are listed below.
Other Problems
Crowding / Crooked Teeth
Crowding presents itself as a general overlap of teeth in each jaw. You can see from the photographs the generalized overlapping of teeth and the extent of the crowding.
Crowding results from a number of factors, one of which is heredity. Genetically, we find examples of large teeth accompanied by a small jaw where the teeth won't all fit, but they continue to erupt and overlap each other. Crowding may also occur due to environmental factors such as premature loss of deciduous (baby) teeth either from decay, extraction or early natural loss. This allows the permanent teeth in the back part of the mouth to crowd forward resulting in a lack of space for other permanent teeth. Just as there is an early loss of deciduous teeth, prolonged retention of the primary teeth can deflect the permanent teeth from their normal eruption path, resulting in crowding and/or impaction.
Crossbite
A crossbite is a positional problem, where one or more of opposing upper and lower teeth bite on the wrong side of each other. This may affect either the front or the back teeth. In the growing child these crossbites may affect the growth pattern of either jaw and may cause a permanent skeletal change.
Deepbite
A deep bite occurs when the upper front teeth cover the lower front teeth too much. In some cases the lower front teeth might damage the gums behind the upper teeth.
Impacted Teeth
During the normal eruption pattern, the permanent teeth generally dissolve the roots of the deciduous (baby or primary teeth) as they erupt into the mouth. The end result is that the baby teeth fall out and are replaced almost immediately by the permanent successor.
Sometimes, however, the permanent teeth loose their normal path of eruption into the mouth and track off in an abnormal direction, where they fail to erupt. These are termed "impacted." The end result is a failure of the baby tooth to be lost and the permanent successor remains under the gum. The unerupted (impacted) tooth then has the potential to dissolve the roots of the tooth with which it comes in contact and, not uncommonly, this is an adjacent permanent tooth.
Impacted teeth can be a genetic trait with the incidence more common in females than males 2:1 and are closely associated with missing or very small lateral incisor teeth (the second upper front tooth). The third molars are the most common impacted teeth.
Excessive Spacing
Excess spacing describes the condition of when there are noticeable gaps between the teeth.
Midline Discrepancy
The midline of our upper and lower teeth should generally coincide. A discrepancy of this midline is when the middle of the upper and lower teeth does not align. This can be due to the upper or lower teeth moving to the left or right or a combination of both. Various factors can result in a midline shift such as the premature loss of baby teeth, retained baby teeth, crowding, missing teeth and tooth size issues.
Missing Teeth
The number of teeth affects the look or aesthetic appearance of the smile and the function of the jaws and the teeth. In cases of missing anterior (front) teeth, symmetry plays an important role in whether it is best to have a missing tooth/teeth replaced or the space of the missing tooth closed. Missing teeth may result from hereditary causes (quite common) or environmental factors such as decay, accidents where teeth may have been knocked out, or the failure of teeth to erupt, which leads to an impaction.
Openbite
An openbite refers to a vertical open space when the upper teeth do not overlap the lower teeth at all. Ideally the upper front teeth should overlap the lower teeth by 1.5mm—2 mm. Openbites may result from environmental factors such as thumb/finger sucking, tongue thrust swallowing, mouth breathing and pacifiers.
Incorrect Angulations
Angulations of teeth refer to the alignment of the long axis of the teeth in a line from the chewing surface along the root. Incorrect angulations may be caused by lack of space for the tooth to erupt or it may mean that something in the jaw is causing the tooth to tilt. Some examples of this would be a retained baby tooth, an extra tooth or a cyst.
Rotations
Rotations can occur with front or back teeth. As well as being an aesthetic problem, the tooth is predisposed to gum recession, improper function and tooth decay.
Submerged Primary Teeth
When baby teeth do not erupt along with the adjacent adult teeth, the baby teeth seem to submerge. This can become severe enough for the baby teeth to eventually be covered by gum tissue. If this occurs, the adjacent permanent teeth may tilt over the submerged baby tooth/teeth and create localized crowding.