Normal occlusion or malocclusion: that is the question (Proceedings)


Normal occlusion or malocclusion: that is the question (Proceedings)

May 01, 2011

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 malocclusions.

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 located.

     • 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 endocrine disorders.

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.