Occlusion is a contact between the incising or masticating surfaces of the maxillary and mandibular teeth. Normal occlusion
in the dog and cat is also known as a "scissors bite". The mandibular teeth should occlude lingual to the maxillary teeth.
The mandibular incisor cusps should rest on the cingulum on the palatal side of the maxillary incisors. The mandibular canine
crowns should lie equally between the maxillary third incisor and maxillary canine. The mandibular premolar crown tips should
point to the interproximal spaces between the crowns of the maxillary premolars. Each mandibular premolar should be positioned
rostral to the corresponding maxillary premolar.
Malocclusion is any deviation from normal occlusion which is not standard for that breed. Recognition of malocclusion is
an important part of the oral exam. Patients with malocclusion may have difficulty chewing their food and/or significant
oral pain from teeth impinging on soft tissue. The American Veterinary Dental College (AVDC) has categorized commonly found
malocclusions. The goal of this lecture is a review of the signs and treatment options that are available to treat these
Types of malocclusion
Skeletal or jaw length malocclusion is found when the maxilla and mandible are abnormally positioned. The most common cause
is hereditary due to line breeding to achieve a particular characteristic and the mating of parents with dissimilar jaw sizes
and head shapes.
Dental or tooth malocclusion is found when you have normal relationship of the maxilla and mandible but the teeth are abnormally
• Distoversion – when a tooth is in normal anatomical placement but angled distally
• Mesioversion – when a tooth is in normal anatomical placement but angled mesially
• Linguoversion – when a tooth is in normal anatomical placement but angled lingually
• Labioversion – an incisor or canine tooth that is in normal anatomical placement but angled labially
• Buccoversion – a premolar or molar tooth that is in normal anatomical placement but angled buccally
Other non-genetic causes of malocclusion are local disturbances such as trauma, early or delayed loss of primary teeth, cystic
formation, bruxism or abnormal chewing. Systemic disturbances can also contribute, such as severe illness, nutritional or
Malocclusion of deciduous teeth
Some malocclusions involving deciduous teeth can be temporary or develop into a permanent problem. The most common malocclusion
seen involving deciduous teeth is jaw length discrepancies. These patients are genetically programmed for a normal bite but
are only temporarily maloccluded due to the fact that each mandible grows at a varying rate.
The most common malocclusion presentations seen in pediatric dentition is Class II – overshot, Class III – undershot, Base
Narrow Mandibular Canines, Class II with Base Narrow Mandibular Canines. With these conditions the deciduous dentition can
become trapped by a tooth or soft tissue on the opposite arcade which causes an adverse dental interlock. When dental interlock
is present trauma to the soft tissues can occur causing pain and infection.
• Standard treatment options for pediatric patients with malocclusion Is:
• Extraction: if trauma is present to minimize the trauma.
• Selective Extraction/Interceptive Orthodontics: If no trauma is present this is done to prevent adverse dental interlock
to allow the mandible to grow freely. The extractions usually are done on the jaw that needs to grow. Extractions are ideally
done at 4-8 weeks of age.