• An ideal occlusion - according to the American Veterinary Dental College (AVDC) - can be described as perfect interdigitation of the maxillary and mandibular teeth. This ideal relationship with the mouth closed can be defined by the following:
  • The maxillary incisor teeth are all positioned rostral to the corresponding mandibular incisor teeth.
  • The crown cusps of the mandibular incisor teeth contact the cingulum of the maxillary incisor teeth.
  • The mandibular canine tooth is inclined labially and bisects the interproximal  (interdental) space between the opposing maxillary third incisor tooth and canine tooth.
  • The maxillary premolar teeth do not contact the mandibular premolar teeth.
  • The crown cusps of the mandibular premolar teeth bisect the interproximal (interdental) spaces rostral to the corresponding maxillary premolar teeth.
  • The mesial crown cusp of the maxillary fourth premolar tooth is positioned lateral to the space between the mandibular fourth premolar tooth and the mandibular first molar tooth.
• A malocclusion is any deviation from ideal occlusion described above. In dental malocclusion, one or more teeth are in abnormal position within the dental arch. In skeletal malocclusion, there is an abnormal relationship between the maxillary and mandibular dental arches; dental malocclusion may be present in addition to skeletal malocclusion.

Presenting signs

• Neutrocclusion (class 1 malocclusion = normal rostrocaudal relationship between the maxillary and mandibular dental arches):
  • Distoversion (tooth angled distally).
  • Mesioversion (tooth angled mesially).
  • Linguoversion (tooth angled lingually).
  • Labioversion (tooth angled labially).
  • Buccoversion (tooth angled buccally).
  • Crossbite (mandibular tooth or teeth positioned more labially or buccally than maxillary antagonist tooth or teeth when mouth is closed):
    • Rostral crossbite (one or more mandibular incisors labial to maxillary antagonist tooth or teeth).
    • Caudal crossbite (one or more mandibular cheek teeth buccal to maxillary antagonist tooth or teeth).
• Symmetric skeletal malocclusion:
  • Mandibular distocclusion (class 2 malocclusion; abnormal rostrocaudal relationship between the maxillary and mandibular dental arches in which the mandibular arch occludes caudal to its normal position relative to the maxillary arch).
  • Mandibular mesiocclusion (class 3 malocclusion; abnormal rostrocaudal relationship between the maxillary and mandibular dental arches in which the mandibular arch occludes rostral to its normal position relative to the maxillary arch).
• Asymmetric skeletal malocclusion (maxillary-mandibular asymmetry):
  • Rostrocaudal (unilateral mandibular mesiocclusion or distocclusion).
  • Side-to-side (loss of midline alignment between upper and lower jaws).
  • Dorsoventral (abnormal vertical space when mouth is closed resulting in an open bite).

Age predisposition

• Malocclusion is often present from the time of eruption of the deciduous or permanent teeth.

Breed/Species predisposition

• Dental malocclusion:
  • Brachycephalic breeds (eg crowding of teeth that try to find a space in a shortened jaw)  Crowding of teeth.
  • Dolichocephalic breeds.
  • Mesaticephalic breeds (eg after trauma to developing and erupting permanent tooth).
• Mandibular distocclusion:
  • Dolichocephalic breeds.
• Mandibular mesiocclusion:
  • Brachycephalic breeds.

Special risks

• Early periodontitis Periodontal disease due to increased plaque accumulation at crowded teeth  Teeth: calculus.
• Trauma to soft and hard tissues as a result of opposing maloccluding teeth.