What causes poor dental occlusion

Spaced out, crowded, sparse, with gaps in between… Poor dental occlusion causes many problems, which can even lead to facial shape deformities. But why does it happen? Is it a matter of genes, or is there something we do?

As explained by Dr. Katerina Douma-Michelaki, DDS, PhD, Specialist in Orthodontics for Children & Adults, occlusion refers to the way the upper jaw’s teeth come in contact with those of the lower jaw. “The normal condition is for the upper teeth to be about 1-2 millimeters outside the lower teeth, while the cusps of the molars should fit specific grooves of the opposing teeth,” she says.

Most occlusion problems appear in childhood, after the baby teeth are replaced by permanent ones, and can involve the teeth themselves (e.g., crooked, protruding, or not fitting properly together) or be skeletal (the problem is in the jawbones) or dentoskeletal (there is a problem with both the teeth and the bones).

There are several categories of poor dental occlusion, with the three main ones being:

* Class I Occlusion Abnormality: This is the most common. In these cases, the facial bones are usually harmonious, but there are issues with the position of the teeth, such as crooked or crowded teeth, teeth out of place, extra teeth, large gaps, impacted teeth, etc.

* Class II Occlusion Abnormality: It occurs when the upper jaw bone is positioned too far forward compared to the lower jaw, or when the lower jaw is smaller than the upper, or when there is a combination of both. This skeletal disharmony usually results in the upper teeth protruding, causing the lower teeth to damage the gums inside the upper jaw.

* Class III Occlusion Abnormality: In these abnormalities, the lower jaw protrudes relative to the upper jaw, giving the face the characteristic expression of mandibular prognathism.

Most dental occlusion problems are genetically determined, but there are also external (environmental) factors that can play a role.

Genetically Determined Causes

Although one cannot do anything to avoid genetically determined causes of poor dental occlusion, the earlier they are noticed, the easier their treatment, emphasizes Dr. Douma-Michelaki.

She explains some of the causes that lead to poor occlusion:

* Abnormal jaw size or shape. This is one of the main causes of overbite and prognathism.

* Abnormal tooth shape. Sometimes the shape of the jaw is normal, but the teeth are too large or too small for it. When the teeth are large, crowding can occur, while if they are small, there will be spacing between them. It is also possible that the teeth form strange shapes or angles that prevent them from fitting properly when the mouth is closed.

* Impacted teeth. When there is not enough space for all the teeth to grow, some (e.g., wisdom teeth) may remain impacted, meaning they do not erupt. When this happens, sooner or later, problems will occur because the “trapped” tooth can push against neighboring teeth or even cause resorption of adjacent tissue due to intraosseous friction.

* Genetic malformations. Cleft lip and palate (also known as harelip and wolf mouth) is a classic example of a genetic malformation that causes poor dental occlusion.

* Supernumerary or congenitally missing teeth. Depending on their position and number, they can cause mild to severe orthodontic problems.

* Delayed loss of baby teeth. When the first teeth (baby teeth) do not fall out but permanent ones still emerge, dental crowding and displacement of teeth can occur. The development of permanent teeth behind the baby teeth is a typical cause of so-called crossbite of the teeth.

Environmental Causes

The environmental causes that may lead to poor dental occlusion can be largely avoided, emphasizes Dr. Douma-Michelaki. These include:

* Bad habits. Thumb sucking, prolonged use of a pacifier (after the age of 3 years) or bottle (after the age of 2 years), and pushing the teeth with the tongue can cause poor dental occlusion.

* Mouth breathing. Although considered an innocent habit, it is linked to many problems in the development of the face and mouth, including severe poor dental occlusion.

* Gingivitis. Periodontal disease causes gum recession, resulting in loosening and separation of the teeth.

* Tooth loss. When baby teeth are lost too early, it can lead to poor occlusion of permanent teeth. The loss of permanent teeth allows the remaining teeth to shift.

* Inadequate restorations. Crowns, fillings, bridges, and generally dental restorations that do not fit the patient’s mouth can create poor occlusion.

* Injury or tumor in the mouth and/or jaw. These can lead to deformities and serious occlusion problems.