Malocclusions in Cats – When Teeth Are Misaligned
Kittens normally have 26 deciduous (primary or baby) teeth, which erupt during the first six months of life, and adult cats have 30 permanent teeth. Cats have four types of teeth:
- Incisors are the smaller teeth located between the canines on the upper and lower jaws. They are used for grasping food and they help (along with the lower canines) keep the tongue within the mouth.
- Canine teeth are located on the sides of the incisors and are used to grasp food and other objects. The lower canines help to keep the tongue within the mouth. Even with the loss of canines and incisors, cats are less likely to let the tongue protrude (tongue lolling) when compared with dogs.
- Premolars are located behind the canines and are used to shear or cut food.
- Molars are behind the premolars and are the teeth found at the back of the mouth. They are used for grinding food preparing it for swallowing.
What does occlusion mean?
Occlusion is a term used to describe the way teeth align with each other. “Normal” occlusion occurs when the upper incisors just overlap the lower incisors (scissor bite), when the lower canines are located at an equal distance between the upper third incisor and the upper canine teeth, and when the premolar crown tips of the lower jaw point between the spaces of the upper jaw teeth.
"Occlusion is a term used to describe the way teeth align with each other."
Cats often have incisors that exhibit more of a level bite i.e., where the upper and lower incisors meet each other evenly. Flat-faced breeds (e.g., Burmese and Persian cats) have “abnormal” bites that are recognized as being “normal” for their breed, where the lower jaw protrudes in front of the upper jaw and alters the above tooth-to-tooth relationships.
What is malocclusion?
Malocclusion refers to abnormal tooth alignment. There are two types of malocclusion: skeletal and dental.
A skeletal malocclusion results when there is a discrepancy in jaw length of the lower jaw, relative to the length of the upper jaw. A skeletal malalignment causes the teeth to be out of normal orientation with each other.
A dental malocclusion, or malposition, occurs when the upper and lower jaw lengths are considered normal but there may be one or more teeth are out of normal alignment (malpositioned tooth/teeth).
When a dental or skeletal malocclusion causes trauma to other teeth or oral soft tissues, the condition is termed non-functional, the occlusion is considered traumatic and treatment is needed.
Therapy options include:
- moving the offending or offended tooth/teeth, or
- surgically creating additional space for the malpositioned tooth to occupy.
For more information on moving teeth, see handout "Orthodontics (Moving Teeth in Cats).
What are some common forms of skeletal malocclusion?
- Mandibular Distoclusion or Class 2 Malocclusion (MAL2). Also known as an overbite, overjet, overshot and mandibular brachygnathism, it occurs when the lower jaw is shorter relative to the length of the upper jaw. When the mouth is closed, the teeth of the lower jaw do not occlude (align normally) with their corresponding teeth in the upper jaw. There is a space between the upper and lower incisors when the mouth is closed and the lower incisors may traumatically contact the roof of the mouth behind the upper incisors. The upper premolars are aligned too far toward the nose compared to their counterparts in the lower jaws.
- Mandibular Mesioclusion or Class 3 Malocclusion (MAL3). Also known as an underbite, undershot, reverse scissor bite, and mandibular prognathism. It occurs when the lower jaw is too long relative to the upper jaw and the lower teeth protrude in front of corresponding upper teeth. If the jaw length discrepancy is minimal, then the upper and lower incisor teeth may meet each other edge to edge resulting in an occlusion referred to as an even or level bite.
- Maxillomandibular Asymmetry. The asymmetry may occur in a number of different ways. It is important to keep in mind that there are 2 upper jaws and 2 lower jaws. All 4 jaws grow/develop independently. Therefore, asymmetry may occur in the lower and/or the upper jaws. When there is a length disparity between the right and left side it is referred to as a rostrocaudal asymmetry (upper and/or lower). When the asymmetry results in a lack of centering of the upper and lower jaws over each other causing a midline shift, then it is referred to as a side-to-side asymmetry. Finally, there may be an asymmetry that is exhibited as an abnormal (increased) space between the upper and lower jaws (may affect one or both sides) and is referred to as an open bite.
What are some common forms of dental malocclusion?
- Mesioverted. Canine teeth are malpositioned rostrally (towards the nose) and they may or may not be in traumatic contact with other teeth or the oral soft tissues. This dental malocclusion may be an inherited in some breeds (e.g., Persian Cats).
- Mesiopalatoverted Maxillary. This may be inherited or developmental, secondary to persisting deciduous teeth.
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