Malocclusion Of Teeth

Dogs normally have twenty-eight deciduous (primary or baby) teeth that erupt during the first six months of life. Most breeds have forty-two adult teeth. There are 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 help keep the tongue within the mouth. Canines (also called cuspids or fang teeth) are located on the sides of the incisors and used to grasp food. Premolars (bicuspids) are for shearing or cutting food and are located behind the canines. The molars are the last teeth in the mouth. They are used for grinding nourishment for entry into the esophagus.

Occlusion

The way teeth align with each other is termed occlusion. Normal occlusion in most breeds consists of the upper (maxillary) incisors just overlapping the lower (mandibular) incisors (scissor bite). The lower canine should be located equidistant between the last (lateral) incisor and the upper canine tooth. Premolar tips of the lower jaw should point between the spaces of the upper jaw teeth. Flat faced breeds (Boxers, Shih-Tzu, and Lhasa Apso) normally do not have scissor bites.

Malocclusion

Malocclusion refers to abnormal tooth alignment. Overbite (overshot, class two, overjet, mandibular brachygnathism) occurs when the lower jaw is shorter that the upper. There is a gap between the upper and lower incisors when the mouth is closed. The upper premolars are displaced at least twenty-five percent toward the front, when compared to the lower premolars. An underbite (undershot, reverse scissor bite, prognathism, class 3) occurs when the lower teeth protrude in front of the upper jaw teeth. If the upper and lower incisor teeth meet each other edge to edge, the occlusion is an even or level bite. When the upper and lower incisors do not overlap or even meet each other when the mouth is closed, the pet has an open bite. Anterior crossbite occurs when the canine and premolar teeth on both sides of the mouth occlude normally but one or more of the lower incisors are positioned in front of the upper incisors. Anterior crossbite is the most common malocclusion, is not considered genetic or hereditary, and is correctable. If there is an anterior crossbite there must be a condition termed posterior crossbite. Posterior crossbite occurs when one or more of the premolar lower jaw teeth overlap the upper jaw teeth. This is a rare condition that occurs in the larger-nosed dog breeds. A wry mouth or bite occurs when one side of the jaw grows longer than the other. It is considered hereditary and difficult to correct. Base narrow canines occur when the lower canine teeth protrude inward and can damage the upper palate. Often this condition is due to retained baby teeth and can usually be corrected through inclined planes used to push the teeth into normal occlusion.

Scissors Bite For most breeds the scissors bite is ideal. Scissors bite is one in which the upper incisors just overlap and touch the lower incisors.	Scissors Bite
Overshot (overbite, parrot mouth, class two, overjet, mandibular branchygnathism) In this condition the upper jaw is longer than the lower jaw. There is a gap between the upper and lower incisors when the mouth is closed. Some puppies that are born with an overbite might self-correct if the bite is no larger than the head of a wooden match. In most breeds of dog the bites are "set" by the time a puppy is ten months old. An overshot bite will rarely improve after the puppy reaches ten months. Some puppies with overshot bites will experience difficulties when their permanent teeth come in. Due to the increased size of the permanent teeth, as they come in they can damage the soft parts of the mouth. Overbites should be carefully watched, as sometimes extractions become necessary.	Overshot
Undershot (underbite, reverse scissors bite, class 3, prognathism) In this condition the lower jaw is longer than the upper jaw. If the upper and lower jaw meet each other edge to edge, the bite is referred to as an even or level bite. In some breeds of dog an underbite is the correct bite. Check your breed standard.	Undershot
	Level Bite

Anatomy

Occlusion

Malocclusion