issues. Causes may be congenital, developmental, or due to lifestyle factors. Malocclusions Malocclusion is the imperfect positioning of the teeth when the jaw is closed. In dogs and cats with normal occlusion, the upper incisors rest in front of the lower incisors, the lower canines fit in the diastema between the upper canine and third incisor, the upper first premolars fit behind the lower first premolars, and the upper fourth premolars overlap the lower first molars. Any deviations are known as malocclusions, and they are separated by class. Class I malocclusion (MAL/1) Also known as neutrocclusion, MAL/1 occurs when the maxilla and mandible are correctly proportioned, but one or more teeth are misaligned. This type of malocclusion is further classified by type: Rostral cross bite (RXB) – one or more of the upper incisors are displaced so they rest behind the lower incisors, rather than in front. May be caused by retained deciduous (baby) upper incisors, preventing normal eruption of adult incisors. Caudal cross bite (CXB) – the mandible is wider than the maxilla in the area of the premolars. Instead of the upper fourth premolar resting against the inner cheek (buccal occlusion) and the lower first molar resting against the tongue (lingual occlusion), the positional relationship is reversed. This is commonly observed in dolichocephalic head types (having a long skull). Linguoversion (LV) – the lower canines are in the correct anatomic position but are angled inward towards the tongue, which can cause trauma to the palatal tissue (the roof of the mouth). Mesioversion (MV) – occurs when a tooth is in the correct anatomic position in the dental arch but is angled more forward than normal. Labioversion (LABV) – occurs when an incisor or canine tooth is in the correct anatomic position in the dental arch but is angled towards the lips. Distoversion (DV) – occurs when a tooth is in the correct anatomic position in the dental arch but is angled more behind than normal. Buccoversion (BV) – occurs when a tooth is in the correct anatomic position in the dental arch but is angled outward towards the cheeks. Class II malocclusion (MAL/2) Also called distoclusion, brachygnathism, overshot jaw, overbite, and parrot mouth, MAL/2 occurs when the upper teeth rest in front of the lower equivalents. The maxilla is forward (maxillary prognathism) and the mandible is behind (mandibular retrognathism). It is more common in animals with dolichocephalic skulls,