Distal Bite: Signs, Causes and Treatment

A distal bite is one of the most common bite anomalies: the upper jaw or upper dental arch protrudes noticeably forward relative to the lower one. To some degree this condition affects roughly a third of the population, and it influences not only appearance but also chewing, breathing and the health of the temporomandibular joint. Here is how to recognise a distal bite, where it comes from and how it is corrected.

What a distal bite looks like

With a normal bite the upper incisors overlap the lower ones by about a third of their height. With a distal bite the overlap is increased, and a horizontal gap appears between the cutting edges of the upper and lower incisors. External signs that are often visible in profile:

• a convex facial profile;
• a sloping, "receding" chin;
• a short upper lip, with the mouth often slightly open;
• strain of the chin muscle when closing the lips;
• a pronounced chin crease.

Many patients are embarrassed to smile and dislike their profile, so the problem has a psychological side as well. But the functional consequences matter more: overloading of the front teeth, accelerated wear, joint pain and speech difficulties.

Two forms of distal bite

First form

The upper incisors are tilted forward and fan out, gaps appear between them, and the teeth may be crowded in the side sections. It is often combined with an open bite. This position makes biting food difficult and can affect the pronunciation of hissing and whistling sounds.

Second form

The upper central incisors, by contrast, are tilted inward towards the palate, there are no gaps between them, and the lateral incisors may protrude forward. In this form the lower incisors often injure the palate, and the overlap can be very deep.

The form and severity can only be determined through diagnostics, based on the examination, a 3D scan and X-ray images.

Why a distal bite develops

The causes are divided into hereditary and acquired, and most often they act together.

• Genetic predisposition. The size and position of the jaws are largely inherited.
• Bottle feeding. When sucking from a bottle the lower jaw works less than during breastfeeding and lags behind in growth.
• Impaired nasal breathing. Frequent colds and enlarged adenoids and tonsils force a child to breathe through the mouth, which changes tongue position and jaw growth.
• Harmful habits. Prolonged use of a pacifier or thumb sucking, resting the chin on a hand, biting the lip.
• Childhood diseases. For example rickets and other conditions that affect bone growth.
• Early loss of baby teeth and facial injuries.

How a distal bite is treated

The approach depends on the patient's age and on where the problem lies: in the position of the teeth or in the size and position of the jaws.

Children and teenagers

While the jaws are still growing, a distal bite responds especially well to correction. Functional appliances are used to stimulate growth of the lower jaw and normalise the position of the tongue and lips. In adolescence braces or aligners are added.

Adults

In adults jaw growth is complete, so treatment works with the position of the teeth. The main options are:

1. Braces, including self-ligating systems such as Damon, often combined with elastics to correct the jaw relationship.
2. Aligners: clear trays (Invisalign, Angel Aligner, Spark) that can correct many forms of distal bite almost invisibly to others.
3. Combined treatment with a maxillofacial surgeon in pronounced skeletal cases, when moving the teeth alone is not enough.

Sometimes creating space requires extraction of individual teeth or distalisation of the molars using orthodontic mini-screws; this is decided individually based on the diagnostic results.

What happens without treatment

A distal bite does not go away on its own. Over time it leads to uneven tooth wear, overloading of the periodontium, joint problems and postural issues. The earlier treatment begins, the simpler and shorter it is. After diagnostics, the iOrtho orthodontist in Yerevan will suggest the option that suits you and will state the timeline and cost of treatment.