Cats with Overbite and Underbite: Causes and Concerns

What is Malocclusion in Cats?

Malocclusion, one of the three most common oral diseases, refers to the misalignment of teeth, jaws, and facial structures due to factors such as genetics, diseases, functional disorders, or issues during the transition from milk teeth to permanent teeth. This can include crooked teeth, misaligned arches, and improper relationships between the jaws and the skull. Simply put, a cat's malocclusion is a condition where the top and bottom teeth do not align properly and do not bite together correctly.

Malocclusion can lead to various harmful effects, such as oral injuries, periodontal diseases, soft tissue damage from repeated biting, excessive tooth wear and fractures, tooth necrosis, and in some cases, even orofacial fistulas.

Types of Malocclusion in Cats

Cats have 26 milk teeth and 30 permanent teeth. The transition from milk teeth to permanent teeth begins as early as 34 months for the first incisors (front teeth) and as late as 46 months for the last molars (back teeth). If this process is disrupted, the teeth may not align correctly, causing malocclusion.

There are several types of malocclusion in cats:

1. Crossbite: This occurs when the upper and lower jaws are structurally normal, but some teeth are misaligned.

2. Overbite (Deep Overjet): This is when the upper jaw extends too far over the lower jaw, similar to a human's deep overbite.

3. Underbite (Dental Prognathism): An underbite is when the lower teeth are in front of the upper teeth, with the upper front teeth positioned behind the lower front teeth, leading to a lack of proper bite function and a retracted upper lip and palate, commonly known as "buck teeth."

4. Level Bite: This is when the upper and lower incisors are aligned in a straight line.

5. Misaligned Bite: This refers to an uneven growth of teeth on either side, causing the jaw to appear crooked.

Causes of Malocclusion in Cats

The main causes of malocclusion in cats include:

1. Genetics: The shape of the skull is closely related to genetics, so some malocclusions are caused by hereditary factors, especially in breeds with flat faces like Persians and Exotics, where the short mouth can lead to an imbalance between the upper and lower jaws due to selective breeding by humans.

2. Injuries or Trauma: Fractures or dislocations of the temporomandibular joint in young kittens can lead to imbalanced blood supply and uneven growth of the teeth, resulting in a misaligned bite.

3. Malnutrition in Early Life: Malnutrition can lead to skeletal development disorders and may cause bite issues.

4. Retained Milk Teeth: During the transition to permanent teeth, if milk teeth do not fall out in time and are retained while permanent teeth are erupting, they can interfere with the growth of the permanent teeth.

Treatment for Malocclusion in Cats

1. Tooth Extraction: Evaluate the length of the upper and lower jaws and check at 6 weeks of age. If the lower jaw is too short relative to the upper jaw, the lower teeth may pierce the upper palate and cause pain, so extraction may be necessary. If the cat's teeth are tilting towards the tongue, they may also need to be extracted to prevent the permanent teeth from growing in the same direction.

2. Orthodontics: If malocclusion is detected after the permanent teeth have grown in, orthodontic treatment can be considered. This is typically done when there is a tendency for malocclusion, or when the canines fall to the tongue side and damage the upper palate, causing significant pain. However, most methods involve applying the cat's chewing force to push the teeth back into the correct position. Since this is a highly specialized field, not all veterinary hospitals offer these services.

3. Refusing to Breed Cats with Malocclusion: If a cat has malocclusion, there is a high likelihood that the next generation will also have malocclusion. Therefore, the best approach is to avoid breeding these cats.