Surgical Removal of a Large Maxillary Sinus Mass Containing Three Dental Structures in a Standing Horse.

Surgical removal of a large mass containing three ectopic teeth from the maxillary sinus of a standing horse was successfully performed using two simultaneous surgical approaches, preserving sinus and nerve structures while removing the mass.

Background

• Dental masses including odontogenic masses, heterotopic polydontia, and ectopic supernumerary teeth have been documented in horses but are rare, especially when involving large masses in the maxillary sinus.
• This case report is the first to describe a large maxillary sinus mass containing three ectopic teeth in an adult horse.
• The maxillary sinus is an air-filled space in the skull near the upper jaw where dental structures are located.

Case Description

• A 14-year-old warmblood gelding presented with chronic nasal discharge on the right side, indicating a possible sinus or dental problem.
• Diagnostic imaging revealed a large mass occupying the right maxillary sinus.
• The mass was covered by sinus mucosa, surrounded the infraorbital nerve canal, and contained three ectopic tooth structures, which were separate from the normal dental table that appeared intact.

Surgical Approach

• The surgery was performed on the standing horse, avoiding general anesthesia risks.
• Two simultaneous surgical approaches were used:
  • Right frontal trephination into the conchofrontal sinus (upper sinus area through the frontal bone).
  • Right maxillary sinusotomy — creating an opening in the maxillary bone for sinus access.
• These approaches provided enhanced visualization and access to the entire mass while preserving critical structures.
• Adhesions were noted between the dental masses, infraorbital canal, and maxillary bone, which made the surgery delicate.
• The surgical team successfully removed the entire mass without damaging sinus mucosa or nerve structures.

Significance and Considerations

• This represents the first documented complete removal of a large maxillary sinus mass containing multiple ectopic teeth in a standing horse using these techniques.
• The dual approach allowed preservation of the sinus architecture and nerve integrity.
• Because the mass was adherent to the infraorbital canal and maxillary bone, there was risk of infraorbital nerve damage either from the mass effect or during surgery.
• Potential neurological symptoms could develop if the infraorbital nerve was compromised, so preservation was a key surgical goal.
• The case highlights a minimally invasive yet effective surgical method for treating complex sinonasal dental masses in horses without general anesthesia.

Conclusion

• The study provides a novel surgical technique and important clinical insights for equine surgeons dealing with large sinus masses containing ectopic dental structures.
• Using combined frontal and maxillary sinus access, surgeons can achieve complete mass removal while maintaining sinus and nerve function.
• This approach may improve outcomes and reduce complications in similar cases of sinonasal pathology in horses.