Class II problems represent an abnormal bite relationship in which the upper jaw and teeth are located in front of the lower jaw and teeth. Class II patients usually exhibit a convex facial profile with a recessed chin. A skeletal Class II problem occurs when the upper back molars are forward of the lower back molars. This gives the patient the appearance of having a recessed lower jaw, a protruding upper jaw or both. In both cases, this relationship is due to the inherited characteristics.
Class III problems are also primarily genetic in origin. In this instance, the lower jaw and teeth are positioned in front of the upper jaw and teeth. The lower jaw may appear to be excessively large, but in many cases the lack of upper jaw development is at fault. Several treatment options are available to correct a Class III problem.
Crowding of the teeth is probably the most common orthodontic problem. Although many factors contribute to dental crowding, this problem typically stems from a discrepancy between the space in each jaw and the size of the teeth.
Crowding is often one of several orthodontic problems. Crowding can be the cause or result of other problems, such as impacted teeth, retained teeth or teeth that do not naturally fall out. Crossbite of the front or rear teeth can also cause the teeth to become crowded.
Excessive vertical overlapping of incisor teeth, called "overbite", is generally found in association with excessive eruption of either the upper or lower incisors or sometimes both.
Spaces between teeth are another common problem associated with the need for orthodontic care. Like crowding, spacing may be related to a tooth-to-jaw size disharmony. Spacing may occur between the front and the back teeth. Tooth size discrepancies, such as smaller teeth or abnormally shaped teeth, can also create abnormal spacing.
An openbite can occur with both the front or back teeth. An open on bite on the front teeth is called an anterior open bite, while an openbite on the back teeth is called a posterior openbite. An anterior openbite is the lack of vertical overlap of the front teeth and can usually be traced to jaw disharmony or habits such as thumb sucking or the posture of the tongue pushing against the front teeth. A posterior openbite is a problem in which the back teeth do not meet vertically, which keeps the jaw from functioning properly.
Also known as a gummy smile, this orthodontic problem gives the appearance of excessive exposed gums on the upper arch. There are several treatment options for this problem. In severe cases, corrective jaw surgery may be necessary to actually shift the jaw vertically upward, thus reducing the amount of exposure of the upper gum tissue.
A posterior crossbite will usually result from a narrow upper jaw or abnormally wide lower jaw. When a patient with a narrow upper jaw is closing their mouth, they will likely be forced to move the lower jaw forward or to the side in order to achieve a stable bite. When closed into this accommodating position, the lower teeth are located outside the upper teeth.
A posterior crossbite can involve one side of the jaw, known as a unilateral crossbite, or both sides of the jaw, known as a bilateral crossbite.