A 3-year-old Quarter horse gelding in good condition had a swelling on his right maxilla that had been increasing in size (Fig. 49). There was nasal discharge with a foul odor coming from the right nostril. The maxilla was swollen in the area of the 107, however the clinical crown looked normal when examined, and there was no mobility of any teeth in the arcade (Fig. 52). There was a small amount of feed packing on the buccal side of the 107. An open mouth lateral oblique radiograph was taken to isolate the enlarged area over the 107 (Fig. 51). Also taken was a dorsal/ventral offset radiograph showing a clear image of the abscess involving the 107 (Fig. 50). It was large and spherical in shape surrounded with dense sclerotic bone. Most root abscesses involving the upper 7’s rupture and drain to the outside of the maxilla. In this case the drain tract was formed into the nasal cavity, which is unusual. This accounts for the purulent nasal discharge coming from the right nostril. The area was surgically prepped, and local anesthesia was infused in the area to desensitize the skin and subcutaneous tissue (Fig. 53). A maxillary nerve block was performed earlier for the oral extraction which lasts approximately 90 to 120 minutes. A skin flap was created first; then the subcutaneous tissue and periosteum were elevated off the bone and transfixed proximally. A 2cm Fortner drill bit was used to make the hole through the maxilla at the proximal end of the abscess. The bone was sclerotic and thick in this area due to the chronic abscess. The hole needs to be big enough to allow a curette to be manipulated in the abscessed area. After debridement of all necrotic tissue and fragments, the periosteum, subcutaneous tissue, and skin were replaced and sutured (Fig. 54). This area should granulate in quickly if all necrotic tissue and fragments have been removed. The communication with the nasal cavity was a small drain tract that was debrided and sutured. The nasal discharge should cease if the drain tract has been resolved. The 107 was extracted orally with the horse standing using sedation and local anesthesia (Fig. 53). This tooth was not difficult to extract because of lack of reserve crown and damaged periodontal attachment. After the tooth was removed, the alveolus was examined for debris and fragments. There were numerous tooth particles about the size of small buckshot laced throughout the necrotic tissue in the abscess.
The abscess was very extensive, making it difficult to curette the infected area, especially the proximal portion from the oral cavity.
We decided to make a small opening through the maxilla to gain access to the infected area for a thorough cleanup of the area. Also, we needed to evaluate the communication of the drain tract to the nasal cavity. Extraction of the 107 without removing the necrotic tissue and tooth fragments may not resolve the infection. Drainage of the abscess is established when the tooth is extracted, but the necrotic tissue and fragments may act as sequestra which will produce a chronic drain tract into the oral cavity. Aggressive debridement of these large abscesses may avoid a second surgery in the future.
Discussion:There are two main points to this article. The first is that an abscess takes the path of least resistance, which in this case was into the nasal cavity. This is not common because the flat bone of the maxilla is usually thin, but during the body’s walling off process of the abscess, the bone became thick and sclerotic on the outside of the maxilla before the abscess ruptured, which forced it to drain medially into the nasal cavity. Secondly, the oral extraction and the modified trephination surgery were performed on a standing horse with sedation and local anesthesia. The advantages of a standing procedure are increased hemostasis because the head is in an elevated position, comfort and good orientation for the oral practitioner, elimination of general anesthesia and possible complications, no recovery time, and more time to complete the procedure. Also, these procedures can be done in any clean environment, without a surgery suite or recovery room. Economically this favors the horse owner, and hopefully will encourage more advanced dental procedures to be used in the equine industry.