Likelihood of Dentigerous Cyst Formation in Dogs

In the Literature 

Hutt JP, Volker MK, Sánchez MD. Correlation between radiographic and histopathologic findings associated with unerupted teeth in dogs. J Vet Dent. 2022;39(4):330-336. doi:10.1177/08987564221108520

The Research … 

A dentigerous cyst can develop around an unerupted tooth when the epithelial lining covering the enamel (which normally becomes part of the gingival sulcus after the tooth erupts) produces fluid, causing expansion and destruction of surrounding bone. Diagnostic confirmation of a dentigerous cyst requires radiographic and clinical findings of the unerupted tooth and associated cystlike structure, as well as histopathologic findings consistent with the cyst lining. These cysts are often seen in young brachycephalic dogs but can develop in dogs of any age or breed with an unerupted tooth. Undetected and/or untreated dentigerous cysts can progress, significantly compromising adjacent teeth and the underlying jawbone.¹ Previous studies primarily focused on radiographic changes associated with unerupted teeth.^2-9  

This prospective study examined the correlation between histopathologic and radiographic findings of unerupted teeth and associated lesions in dogs. Surgically extracted unerupted teeth (63 mandibular first premolar, 2 maxillary canine, 2 maxillary second incisor, 1 maxillary third incisor) were submitted for histopathology, regardless of radiographic evidence of cyst formation. 

Twenty-eight of the 63 unerupted mandibular first premolar teeth had radiographic evidence of a cyst, and histopathology confirmed the cyst lining in 75% of cases. Of the 35 unerupted mandibular first premolar teeth without radiographic cystic changes, 77.1% had no histopathologic evidence consistent with a dentigerous cyst; however, 22.9% did have this evidence. Overall, 57.1% of unerupted mandibular first premolar teeth either formed or showed potential to form a dentigerous cyst.

… The Takeaways

Key pearls to put into practice:

• It is important to count dogs’ teeth; missing teeth are likely truly missing or unerupted. Each side of the upper jaw should contain 3 incisor, 1 canine, 4 premolar, and 2 molar teeth. Each side of the lower jaw should contain 3 incisor, 1 canine, 4 premolar, and 3 molar teeth. Mandibular first premolar teeth are most likely to be unerupted and have an associated dentigerous cyst. Brachycephalic breeds are most at risk for having unerupted teeth.

• Most permanent teeth erupt in dogs by 6 months of age. In patients older than 6 months missing a tooth at the time of a spay or neuter procedure, a full set of dental radiographs is recommended while the patient is anesthetized to determine whether the tooth is truly missing or unerupted.

• Unerupted teeth should be extracted. An unerupted mandibular first premolar tooth can be challenging to locate between the adjacent canine tooth and second premolar tooth, especially in small brachycephalic dogs. To avoid damage to adjacent teeth during extraction, a 22-gauge hypodermic needle can be placed in the gingiva at the expected location and dental radiography performed with the needle in place to help guide the starting location.