Persistent Deciduous Teeth, Unerupted Permanent Teeth, Dentigerous Cyst, Under Erupted Permanent Teeth, & Periodontal Disease in a 12-Month-Old MN Shih Tzu: Our Case Of the Month August 2020

August 31, 2020
The Focal Zone

Many dental presentations in ONE patient!

A 12-month old Shih Tzu’s owner watched as he bit and subsequently broke his baby tooth crown on the technician, then joked – “I guess the problem is finished and we don’t need to be here“….little did this unassuming owner know the plethora of dental pathology this land shark would soon reveal.

Dr. Jen Mathis, owner of Family Pet Veterinary Center in Des Moines, Iowa reviewed the image set showing the now retained tooth root and was able to identify several other dental issues.

  • Persistent Deciduous Teeth
  • Unerupted Permanent Teeth
  • Dentigerous Cyst
  • Under Erupted Permanent Teeth
  • Periodontal Disease (ALREADY at age 1, it starts early!)


Persistent deciduous upper canines without their adult counterparts were noted in a 1 yr old Shih Tzu. Beyond the oral issues, outward physical exam was within normal limits. 

Image Interpretation

Dental Exam Findings and Outome

The areas having persistent deciduous teeth: The upper right (503, 504) – no adult/permanent dentition is below the gumline. (Because patient broke a deciduous tooth in the exam room, Dr. Mathis felt the risk of deciduous tooth fracture was significant, so extracted 503, 504.)

The upper left permanent canine (604 retained root due to exam room fracture) is present as an unerupted tooth. The tooth lies in a bent shape and extends into the sinuses.

The overlap of the retained tooth root of 604 and the malpositioned 207 resulted in extraction and temporary oral nasal fistula of 204-207 region.

To Dr. Mathis’ surprise, the area between 110 and 109 had a 3mm pocket and apical changes were seen on 3D imaging.

110 was extracted to prevent progression of periodontal disease of that area. With crowding and skull shape, Shih Tzu’s are prone to periodontal disease even with such a diligent owner that brushes her pets’ teeth.

Finally, the lower canines were under erupted and were the height of the loose lower incisors.

An apically repositioned flap was performed to remove the pseudopockets and expose an almost normal amount of lower canine tooth enamel returning the area to an appropriate periodontal health.


RTR 604 T/U 204 PD3-4 110 Undererupted 304 404 PD2 301 302 303 401 402 403


Treatment: XSS 110, 204, 604 through 207 X 301 302 303 401 402 403 F/AR 304-404. The patient was recommended follow up intraoral radiographs in 6 months to check for cyst resolution at the site of 204 and evaluate the apically repositioned flap procedure of the lower canines. Due to the surprise unseen periodontal disease of 110, it is best to evaluate all areas of the mouth for hidden problems every 6-12 months with anesthetic dental procedures including intraoral radiographs.

See the full case with pictures here: