DEFINITION/OVERVIEW

In rodents and rabbits, many dental problems are directly related to the continuous growth pattern of incisors and some cheek teeth
- Elodont: continuously growing and erupting
- Aradicular: open-rooted tooth
- Hypsodont: long anatomical crown compared to the root
Acquired dental disease (ADD): improper wear; multifactorial
In caviomorph rodents (guinea pigs, chinchillas), all teeth grow continuously and have open-rooted apices, similar to rabbits (but rabbits have a second pair of maxillary incisors—small peg teeth)
In murine rodents (rats, mice, hamsters, gerbils), the molars have closed roots
- Anelodont: not continually growing and erupting
- Radicular: closed root apex
- Brachydont: short crown compared to the root (similar to human teeth)
Dental formulae
- Rabbits: 2 × (I 2/1; C 0/0; P 3/2; M 3/3) = 28
- Chinchilla: 2 × (I 1/1; C 0/0; P 1/1; M 3/3) = 20
- Rat, hamster (golden and Russian): 2 × (I 1/1; C 0/0; P 0/0; M 3/3) = 16
- Prairie dog: 2 × (I 1/1; C 0/0; P 2/1; M 3/3) = 22
Incisor and cheek teeth overgrowth: excessive lengthening of crown height, typically due to lack of normal physiological attrition, which would offset continuous growth
Rodents and rabbits normally have an anisognathic relationship: maxilla wider than mandible
In other small mammals, teeth have closed roots and do not continuously erupt, so dental issues are often related to diet or acquired disease (trauma)
- Ferrets: 2 (I 3/3; C 1/1; P 3/3; M 1/2) = 34
  - Carnivore/omnivore: teeth similar to cat
  - Fractured canine teeth are the most common presentation
  - Can develop periodontal disease: home care can be helpful
- Hedgehogs: 2 (I 2-3/2; C 1/1; P 3-4/2-3; M 3/3) = 34–40
  - Insectivore
  - Primitive tooth structure
- Sugar glider: 2 ( I 3/2; C 1/0; P 3/3; M 4/4) = 40

ETIOLOGY/PATHOPHYSIOLOGY

Rabbits
- Incisors: the most common clinical presentation due to visibility
  - Congenital: mandibular prognathism/maxillary brachygnathism
    - Lack of proper positioning leads to overgrowth of incisors
  - Trauma: common in rabbits due to a fall or chewing on cage
  - Malocclusion of cheek teeth: incisor malocclusion is secondary
  - Metabolic bone disease
    - Decreased calcium levels; lack of exposure to natural sunlight
    - Demineralization of bones and teeth
- Cheek teeth
  - ADD: elongation of crowns
    - Abnormal occlusal plane: “wave mouth”
      - Spikes lingually on mandibular cheek teeth can damage the tongue
      - Spikes buccally on maxillary cheek teeth can damage buccal mucosa
    - Can lead to deformity of mandibular ventral cortical bone (pressure extending apically)
    - Crown fracture
      - Apical abscess
Guinea pig
- Incisor malocclusion less frequent
  - Almost always secondary to ADD of cheek teeth
  - Mandibular incisors normally long in appearance
    - Improper trimming can cause problems
- Tooth fractures less frequent
- Mandibular prognathism/maxillary brachygnathism not documented
- Metabolic bone disease not reported
- Malocclusion and excessive crown elongation of cheek teeth common
  - Presenting signs are usually more severe than in rabbits
  - Mandibular cheek teeth can elongate over the tongue (seldom lacerate the tongue), sometimes in a complete bridging (tongue tie)
  - Elongation pressure on apices
    - Pressure on intra-alveolar nerves painful and difficult to resolve
Chinchilla
- Incisor malocclusion less frequent than in rabbits
  - Almost always secondary to cheek teeth malocclusion
- Fracture more common than guinea pigs
- Prognathism/brachygnathism and metabolic bone disease not documented
- Cheek teeth elongation: signs at presentation generally less severe than in guinea pig
  - Apical deformities of cheek teeth
  - Perforation of cortical bone, but fewer abscesses than rabbits
Hamsters (golden and Russian)
- Incisor fractures common, but difficult to see
- Cheek teeth may have wear, caries, and fractures
Gerbil
- Incisor malocclusions due to wear or fracture
Rat
- Cheek teeth: fractures and caries
Prairie dog
- Incisor fractures common: falls and chewing on cages
- Pseudo-odontoma
  - Dysplastic maxillary incisors: malocclusion due to trauma, fraction, or improper trimming
  - Interference with proper eruption
  - Pressure: apical growth and deformation of germinal tissue
    - Irregularities of new dentin
    - Progress to severe root deformation, leading to progressive nasal obstruction (not neoplastic)
Dietary influences
- Inadequate roughage for attrition
- Excessive selenium or deficiency of vitamin C (guinea pigs)
  - Impaired collagen synthesis that could impact periodontal ligament (PDL), leading to tooth mobility
  - Mobile teeth may drift out of proper occlusal alignment
Diseases secondary to dental problems
- “Dental disease syndrome”
  - Rabbits: usually in poor condition
    - Skin: slobbers due to hypersalivation or poor grooming (Fig. 60-1)
    - Ocular disease: epiphora or later abscessation due to lacrimal duct involvement
    - Tongue/mucosa: lacerations, defects due to crown overgrowth
    - Abscesses/osteomyelitis
  - Guinea pig
    - Gastrointestinal: reduced food intake can slow peristalsis—bloat
    - Skin and ocular disease less common
    - Abscesses less common
  - Chinchilla
    - Epiphora due to nasolacrimal duct involvement
  - Hamsters
    - Facial mass secondary to periapical abscess
    - Cheek pouches: impaction, prolapsed, or neoplasia