DEFINITION/OVERVIEW
- A retained or persistent deciduous tooth is one that is still present when the permanent tooth begins to erupt, or has erupted
ETIOLOGY/PATHOPHYSIOLOGY
- Dogs/cats
- Numerous factors influence the exfoliation of deciduous teeth
- Lack of permanent successor
- Ankylosis of deciduous root to alveolus
- Failure of permanent crown to contact deciduous root during eruption (Fig. 12-1)
- Lack of permanent successor
- Incidence/prevalence: unknown
- Numerous factors influence the exfoliation of deciduous teeth
Figure 12-1 Radiograph of developing permanent fourth premolar beneath the deciduous tooth in a dog. When the permanent tooth erupts, the deciduous tooth should be exfoliated.
SIGNALMENT/HISTORY
- Species
- Canine more likely than feline
- Breed predilections
- Small-breed dogs: Maltese, poodle, Yorkshire terriers, Pomeranian, and so on
- Mean age and range
- During permanent tooth eruption phase
- Beginning at 3 months for incisors and up to 6–7 months for canine teeth and molars
- May go undiagnosed until later in life
- During permanent tooth eruption phase
- Predominant sex: no correlation
CLINICAL FEATURES
- General comments
- Persistent deciduous teeth can cause the permanent teeth to erupt in abnormal positions resulting in a malocclusion; early recognition and intervention is essential
- Maxillary canine teeth erupt mesial (rostral) to the persistent deciduous canine teeth; this can narrow the space (diastema) between the maxillary canine and third incisor leaving no room for the lower canine tooth to occupy (Fig. 12-2)
- Mandibular canine teeth erupt lingual (medial) to the persistent deciduous teeth; this can result in a narrow space between the lower canines (base-narrow) resulting in impingement on the palate (Fig. 12-3)
- All incisors erupt lingual to the persistent deciduous incisors; this can result in an anterior crossbite
- Persistent deciduous teeth can cause the permanent teeth to erupt in abnormal positions resulting in a malocclusion; early recognition and intervention is essential
- Physical exam findings
- Presence of deciduous tooth with permanent tooth erupting or fully erupted
- Abnormal position of permanent tooth due to persistence of deciduous tooth (see “General Comments” section)
- Local gingivitis and periodontal disease due to crowding
- Oronasal fistula from base-narrow mandibular canine teeth
- Deciduous with no permanent successor
- Deciduous tooth is usually smaller than the permanent tooth
- Deciduous tooth may remain intact and viable
- Frequently does not last the patient’s lifetime
- Deciduous tooth is usually smaller than the permanent tooth
- Presence of deciduous tooth with permanent tooth erupting or fully erupted
Figure 12-2 Multiple persistent deciduous teeth, including the maxillary canine, with the permanent tooth erupting mesial to the deciduous tooth.
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