Common orthodontic problems

Crowding

There is not enough room in the jaw for the teeth to sit in line, so they overlap and rotate.

Crowded teeth are harder to clean. Plaque collects in the overlaps, which can make decay and gum inflammation more likely.

Treated by creating room. That may mean expanding the arch, polishing small amounts of enamel between teeth, or in more severe cases removing a tooth.

Spacing

Gaps between the teeth. Caused by teeth that are small relative to the jaw, by a missing tooth, or by a prominent frenum, which is the band of tissue between the two upper front teeth.

Usually straightforward to close with either braces or aligners.

Overbite

The upper front teeth cover too much of the lower front teeth when the back teeth are closed. Some overlap is normal. A deep overbite means the lower teeth are biting into the roof of the mouth or wearing against the back of the upper teeth.

A deep bite can wear the lower front teeth and irritate the tissue behind the upper front teeth.

Treated by intruding the front teeth, leveling the bite, or in growing patients by encouraging the lower jaw forward.

Overjet

The upper front teeth sit forward of the lower ones horizontally. Often confused with overbite, which is vertical overlap.

Teeth that protrude are at higher risk of being broken in a fall or impact.

Treated by retracting the upper teeth, advancing the lower jaw in a growing patient, or both.

Underbite

The lower front teeth sit ahead of the upper ones. Usually caused by the lower jaw growing further forward than the upper, or the upper jaw being underdeveloped.

Causes uneven wear and can make chewing less efficient.

Easier to address in a growing child, where jaw growth can still be guided. In an adult with a significant skeletal underbite, correction may require surgery combined with orthodontics.

Crossbite

Upper and lower teeth meet on the wrong side of each other. In a posterior crossbite, upper back teeth sit inside the lower ones.

The jaw often shifts to one side to find a comfortable bite. Over time that shift can affect how the jaw grows in a child.

Treated by widening the upper arch, usually with an expander. Simpler while the palate is still growing.

Open bite

The front teeth do not touch when the back teeth are closed. There is a gap you could pass a straw through.

Makes biting into food difficult and can affect speech. Frequently associated with thumb sucking or tongue thrust.

Treated by addressing the habit if one is present, then closing the bite orthodontically.

Midline discrepancy

The center line between the upper front teeth does not match the lower. A small discrepancy is common and often not worth treating. A large one usually indicates a bite problem elsewhere.

Impacted teeth

A tooth that has not come through, usually because there is no room or it is angled wrong. Upper canines are the most commonly impacted after wisdom teeth.

Detected on X-ray, often before there is any visible sign. Treated by creating space and, if needed, exposing the tooth surgically and guiding it into position with orthodontic traction.

This is one of the reasons for an evaluation by age seven.

Missing teeth

Some adult teeth never form, most often the upper lateral incisors and the lower second premolars.

Two approaches: close the space orthodontically and reshape the neighbouring tooth to fill the gap, or open the space to the right width and place an implant or bridge once growth is complete.

Which one is appropriate depends on the bite, the amount of crowding, and the shape of the adjacent teeth.