Extraction of cheek teeth using a lateral buccotomy approach in 114 horses (1999-2009)

Equine cheek tooth repulsion using small diameter repulsion pins: 20 cases

BACKGROUND

Reported complication rates after dental repulsion for equine exodontia are high (up to 80%), but repulsion methods have changed notably in the last 20 years.

OBJECTIVES

Describe the outcome for 20 cases after dental repulsion using small diameter repulsion pins.

STUDY DESIGN

Retrospective case series.

METHODS

Records of horses that underwent cheek tooth repulsion were reviewed (2014-2023). Inclusion criteria included: mandibular or maxillary cheek tooth extraction where oral extraction failed and repulsion was used to complete extraction, and where clinical follow up information was available. Repulsions were carried out under sedation with a regional nerve block or under a short general anaesthetic, using a small diameter repulsion pin (3-5 mm). Intra-operative radiographs facilitated instrument placement. The alveolus was packed with polymethyl methacrylate post-extraction. Horses were re-examined at 4-6 weeks post-operatively.

RESULTS

Twenty cases were included. Patients had a mean age of 10.3 years old (range 5-16 years). The majority (75%) of teeth had pre-existing dental fractures. Maxillary (n = 15) and mandibular cheek teeth (n = 5) were all successfully repulsed, with 16 cases performed with the horse standing and 4 with the horse under general anaesthesia. Intra-operative complications included damage to the mandibular bone (n = 1). Short-term complications (n = 2) included superficial surgical site infection, and dehiscence of one sinus flap. Long-term complications included the recurrence of sinusitis (n = 1) and small intra-alveolar fragments causing persistent bitting problems in another patient.

MAIN LIMITATIONS

Retrospective study design, small number of cases.

CONCLUSIONS

When oral extraction fails, cheek tooth repulsion using small diameter repulsion pins is an effective extraction technique. The total intra- and post-operative complication rate was 25%, which is comparable to previously published complication rates for repulsion using Steinmann pins and also those encountered after trans-buccal screw extraction.

Corkscrew Technique for Extraction of Premolars and Molars in Standing Sedated Horses: Cadaveric Study and Clinical Cases

Several tooth extraction techniques are described in equine literature, and oral extraction techniques in standing sedated horses are popular among equine practitioners. The objectives of this study were to develop the corkscrew technique for cheek tooth extraction (CSET) in equine cadaver heads and evaluate this technique in clinical cases. We hypothesized that the CSET could be performed safely to extract cheek teeth in standing sedated horses. First, the CSET was attempted and developed in eight equine cadaver heads. Second, the CSET was performed in clinical cases between 2016 and 2020, and the following information was recorded: diagnosis, affected tooth, procedure duration, intraoperative difficulties, tooth size, postoperative complications, medication, hospitalization time, and 1-year follow-up. Sixteen CSET procedures were performed in eight equine skulls with a 75% success rate. In 24 clinical cases, 25 CSET procedures were attempted to extract 22 superior and 3 inferior cheek teeth. CSET was successful in 76% of procedures. Fractures of the tooth and stripping of screw threads were the major complications that led to the failure of CSET. CSET is a viable and safe technique to extract cheek teeth in standing sedated horses. Longitudinal drilling is a must for this technique to be successful.

Dental sectioning for intraoral equine cheek teeth extractions: 29 cases

The objectives of this retrospective study were to describe cheek teeth extraction by the sectioning technique, the decision making to use this technique and its potentially associated complications. Sectioning for dental extraction purpose was used in 29/461 (6.3%) of cases. Oro-sinusal fistula was the main post-operative complication, with 4/29 (13.7%) cases developing a macroscopic communication between the alveolus of the tooth extracted and the adjacent sinus compartment. All teeth where sectioning was attempted were successfully extracted. Sectioning for dental extraction appears to be a safe technique that can be used instead of or in addition too other minimal invasive cheek teeth extraction techniques. Thorough preoperative planning including oroscopic examination and medical imaging modalities are required to help in decision making, as well as excellent sedation and analgesia and horse compliance.

Standing equine cheek tooth extraction: A multivariate analysis of the effect of antibiotics on the risk of post-operative complications

BACKGROUND

Commonly, cheek tooth extraction performed in standing horses using perioperative prophylactic antibiotics, results in low post-operative complication rates. However, no studies have documented the relevance of perioperative antibiotics to the risk of post-operative complications.

OBJECTIVES

To examine the association between perioperative antibiotics and post-operative complications after standing cheek tooth extraction.

STUDY DESIGN

Retrospective cohort study.

METHODS

Information from clinical records and follow-up questionnaires relating to horses subjected to cheek tooth extractions between September 2016 and May 2020 was obtained. Post-operative complications and associations with perioperative antibiotics, age, sex, breed, diagnosis, tooth position, and extraction method were analysed using multivariate logistic regression.

RESULTS

A total of 305 horses were included, and of these 71 (23.3%) received perioperative antibiotics. Antibiotics were not associated with the risk of complications in 264 horses that underwent standard oral extraction; 9/49 (18.4%) that received antibiotics and 35/215 (16.3%) that did not receive antibiotics experienced postoperative complications (P = 1, RR = 0.89, OR = 1, OR CI = [0.41; 2.46]). Of 41 horses that had cheek tooth extraction through minimally invasive transbuccal cheek tooth extraction (MTE), 5/22 (22.7%) that received antibiotics and 10/19 (52.6%) that did not receive antibiotics, experienced postoperative complications. Although not statistically significant when adjusting for multiple comparisons (naïve P = 0.04, adjusted P = 0.26, RR = 2.32, OR = 4.48, OR CI = [1.05; 19.11]), this finding is clinically relevant. Younger age was also significantly associated with development of complications (P = 0.02, OR = 0.92 per year, OR CI = [0.87; 1.36]).

MAIN LIMITATIONS

The retrospective nature of the study leads to uncontrollable potential confounders and there is a relatively low number of MTE cases.

CONCLUSION

Perioperative antibiotics were not associated with a lower complication rate in horses subjected to standard standing cheek tooth extraction. Use of perioperative antibiotics in conjunction with MTE may be merited, although further investigations are needed.

Clinical, Diagnostic and Histological Findings Involving Cheek Teeth Hypercementosis in Nine Horses

Hypercementosis is infrequently reported to affect the cheek teeth of horses and presents as mineral deposits either attached (peripheral) or solitary ovoid (nodular) structures in the tooth bearing region. There is overlap between radiological and histological appearance of hypercementosis, cementoma, and equine odontoclastic tooth resorption and hypercementosis (EOTRH). The clinical presentation, imaging features, surgical management, and histological findings of nine horses that presented for dental lesions and associated hypercementosis of cheek teeth are reported. Horses were 4-15 years old and presented for either nasal discharge or facial swelling. Peripheral and nodular mineral structures were identified using radiographs or computed tomography in six and three horses, respectively. Eight of nine cases involved maxillary cheek teeth. Of six cases with peripheral hypercementosis, three had enlargement of the apical cross-sectional area that was greater than the coronal cross-sectional area thus preventing extraction along the normal eruption pathway and necessitating sectioning (two cases) and repulsion. Nodular hypercementosis lesions were extracted in three of the four cases. Post-extraction complications occurred in five cases; four cases required additional procedures. All horses returned to their intended use, ie riding or pasture. Histology of extracted dental and proliferative mineral material revealed hypercementosis characterized by large sheets of eosinophilic matrix with lacunae (usually empty; presumed artifact) and frequent, irregular, basophilic cement lines. All cases had evidence of chronic inflammation, such as caries, chronic fractures and/or pulpitis. The findings of this case series share many features with previous published descriptions of cementoma and with histological findings of hypercementosis lesions of EOTRH. Further investigation into differentiation of these entities is warranted.

Long-Term Follow-Up of Restorations of Equine Cheek Teeth Infundibula (2006–2017)

Background:

Caries of the infundibula of equine cheek teeth can lead to significant dental disease including increased attritional wear, pulpar and apical disease, secondary sinusitis, and dental fracture. Restorations of cavities of equine cheek teeth infundibula have been performed since 1889. Recent advances in dental materials, instrumentation, and techniques have facilitated the use of dental restoration techniques by equine veterinary practitioners. No studies to date have demonstrated the safety or efficacy of restorations of equine cheek teeth infundibula.

Objectives:

To assess the long-term results of restorations of equine cheek teeth affected by infundibular caries, to report on the safety of the procedure, and to give guidelines for future restorative therapies.

Study Design:

Retrospective analysis of results of clinical and oroscopic examination of horses that underwent infundibular restoration procedures between 2006 and 2017.

Methods:

A total of 223 infundibula in 185 maxillary cheek teeth in 92 horses were restored using a variety of dental materials including glass ionomer cement, flowable and compactible resin composites. The time between restoration and re-examination was recorded along with findings of clinical signs in the interim, restorative material loss, and any further pathological changes of the teeth including caries progression, fracture, or apical disease. Follow-up examinations were performed over two study periods 2006–2012 and in 2017.

Results:

Over the full study period, 99% of treated horses available for follow-up examinations had no adverse clinical signs or developed any abnormalities of restored teeth observable on oroscopic examination. Of horses re-examined, 83% of restorations were shown to have minimal or no loss of the restoration material, with occlusal surface wear visibly comparable to other adjacent maxillary teeth. Statistical analysis showed success of the procedure was related to the restorative material used, the restoration technique, and the caries grade present at the time of restoration (grade 3 is more successful than grade 2).

Main Limitations:

There are no case controls in this study and therefore it is not clear if restoration of equine infundibula is a consistently beneficial procedure, or at which grade of caries progression restorations should be performed for optimum benefit. The procedures were not re-examined at consistent regular times creating some difficulties in standardizing results. Re-examinations of treated horses did not consistently include radiography or computed tomography and therefore some apical changes may have occurred in treated teeth without visual oroscopic or external clinical signs.

Conclusion:

Restoration of equine infundibula using materials developed for human dentistry including flowable resin composites is a safe and long-lasting procedure and appears to prevent the development of further pathological changes including apical infection and dental fracture.

Standing Intraoral Extraction of the Right Mandibular Third Molar Tooth in a Cow Utilizing Tooth Sectioning

A 2-year-old Holstein heifer presented to a university teaching hospital with an apical tooth infection of the right mandibular third molar. A standing oral extraction technique was attempted for tooth removal; however, the molar could not be delivered intact. A tooth sectioning technique was performed, and the affected molar was successfully delivered. Three months postextraction, the heifer had fully recovered, and the extraction site had healed. To the authors' knowledge, this is the first description of a tooth extraction in a cow using a tooth sectioning technique. This case describes an alternative technique for tooth removal in cattle with an apical tooth infection. The clinical, diagnostic, and therapeutic features of this case may be helpful to clinicians when they approach similar cases in the future.

Polyaxial pedicle screw external fixation to stabilize oblique mandibular fractures in three standing, sedated horses

OBJECTIVE

To report the radiographic, surgical and postoperative features in horses with unstable oblique mandibular fractures secured with polyaxial pedicle screws (PPS) external fixation construct and intraoral wiring.

ANIMALS

Three client-owned horses.

STUDY DESIGN

Short case series.

METHODS

Two horses each had a unilateral fracture, which did not improve after conservative management, and one horse had bilateral fractures. Clinical and radiographic features were documented. Polyaxial pedicle screw external fixators and intraoral tension band wiring were applied in standing horses after combining sedation and regional nerve anesthesia. Intraoral wires were implanted through a lateral buccotomy between teeth (two horses) or burred through exposed crown (one horse) and then secured around the incisors. The PPS were inserted under radiographic guidance to avoid tooth roots. Healing was assessed with radiographic examination. The PPS external fixator rod and intraoral wires were removed first. The mandible was manipulated, and, if it was stable, the PPS were removed.

RESULTS

Implants were removed at 6, 8, or 10 weeks after the mandibles were palpably stable. Complications included broken wires in one horse, bone sequestration in one horse, and infection in one horse. Follow-up communication with the owners 12 to 18 months later confirmed complete healing without further complications of the fractured mandibles or teeth.

CONCLUSION

Polyaxial pedicle screw external fixation led to fracture healing and a return to function in all three horses. The complications encountered did not preclude a successful outcome.

CLINICAL SIGNIFICANCE

Polyaxial pedicle screw external fixation coupled with intraoral wiring provides an alternative to treat unstable equine mandibular fractures without general anesthesia.

Minimizing Equine Tooth Extraction Complications

Oral extraction has become the most popular extraction technique owing to its high rate of success with minimal major complication. Repulsion continues to produce unacceptably high iatrogenic complication rates. To avoid tooth repulsion, veterinary dentists have introduced procedures to facilitate difficult intraoral extractions and surgical extraction techniques. Minimizing complications is best achieved preoperatively. A comprehensive preoperative evaluation and treatment plan allows the dentist to predict intraoperative complication and prepare for procedures to produce the best outcome. With proper case selection and adherence to extraction principles, the primary veterinarian and the veterinary dentist can perform equine tooth extractions with minimal complications.

Equine Standing Surgical Extraction Techniques

Dental repulsion techniques reported in the past decades have a high incidence of complications. Although the practice of surgical extractions in horses is limited because of the training, instrumentation, and experience required to perform these techniques, veterinarians should be aware these procedures are available, general anesthesia is not required, and when performed by skilled veterinary dentists they have low complication rates. Surgical techniques are often used after failure of other extraction techniques to remove retained tooth root and fragments or to debride chronically contaminated orofacial lesions. However, surgical extractions should be considered during initial treatment planning of all complicated cases.

Repair of an oronasal fistula with a two-layer closure method involving an autogenous fascia lata graft and oral mucosal flap in a pony

CASE DESCRIPTION

A 9-year-old pony gelding was evaluated because it was suspected that a persistent oronasal fistula had developed after a fractured right maxillary second premolar tooth had been extracted via repulsion 6 months earlier.

CLINICAL FINDINGS

Unilateral mucopurulent nasal discharge and malodorous breath were noted on clinical examination. Examination of the oral cavity revealed a 1 × 0.5-cm defect at the oral aspect of the right maxillary second premolar alveolus, from which feed material was extracted. Endoscopic examination revealed feed material in the rostral aspect of the right nasal cavity, confirming the diagnosis of oronasal fistula.

TREATMENT AND OUTCOME

The pony initially underwent a reconstructive surgical procedure that combined an alveolar bone flap with a sliding mucoperiosteal hard palate flap to repair the oronasal fistula. The fistula reoccurred 5 months later and was ultimately repaired by means of a novel 2-layer flap closure method involving an autogenous fascia lata graft and oral mucosa flap.

CLINICAL RELEVANCE

Fascia lata was effective as a scaffolding graft for repair of the oronasal fistula in this pony and may be useful for repair of oronasal fistulas in other equids as well.

Assessment of clinical and computed tomographic findings for association with the outcome of intraoral cheek tooth extraction in horses and ponies

OBJECTIVE

To describe clinical and CT findings for horses and ponies undergoing intraoral cheek tooth extraction and assess potential associations between these features and outcome of the procedure.

ANIMALS

74 horses and 7 ponies.

PROCEDURES

Medical records were searched to identify horses and ponies that underwent CT and intraoral extraction of ≥ 1 cheek tooth with standing sedation. Signalment and clinical variables were recorded, and CT scans were reviewed. Anatomic location and measurements of affected teeth; abnormalities of the periodontium, pulp, infundibula, roots, and tooth shape; fracture presence and type; presence of sinusitis; and affected sinus cavities were assessed by a surgeon and a radiologist. Intraoral extraction outcome was recorded as successful (complete removal of the tooth in 1 intraoral extraction procedure) or unsuccessful. Univariable and multivariable logistic regression analyses were performed to assess associations between clinical or CT findings and outcome.

RESULTS

89 cheek teeth (80 maxillary and 9 mandibular) were included in the analyses. Sixty of 89 (67%) cheek teeth were extracted successfully (56/80 [70%] maxillary and 4/9 [44%] mandibular cheek teeth). Only presence of a simple fracture (vs no fracture) was associated with outcome on multivariable regression analysis; odds of successful intraoral extraction were significantly lower when this feature was present.

CONCLUSIONS AND CLINICAL RELEVANCE

Most extractions of cheek teeth in the study sample were successful, and results may be useful for practitioners in refining cheek tooth extraction plans for horses and ponies. Further studies are required to assess whether specific CT findings can be used to predict the outcome of intraoral extraction in equids.

Transcutaneous Lateral Alveolar Ostectomy for Standing Surgical Extraction of Mandibular First Molar in an 8-Year-Old Miniature Horse

An 8-year-old, 125 kg (275 lb) female miniature horse was evaluated for a persistently thickened left mandible and cutaneous fistula. Pulp horn defects were identified in pulp horns 1 and 3 of tooth 309 and occlusal pulp exposure was detected with a dental explorer. Radiography of the left mandibular dental quadrant revealed changes consistent with apical infection of tooth 309. Following the failure of oral extraction, a standing surgical approach was taken for transcutaneous lateral alveolar ostectomy and extraction. Roots were sectioned at the level of the furcation and elevated from the surgical site, and the remaining reserve crown was luxated and repulsed into the oral cavity. Healing of the surgical site and alveolus was uncomplicated.

A long-term study of equine cheek teeth post-extraction complications: 428 cheek teeth (2004-2018)

BACKGROUND

Complications, especially delayed alveolar healing, are common following equine cheek teeth extraction, however, limited objective information is available on the prevalence and nature of these problems.

OBJECTIVES

To document the type and prevalence of complications that occur following equine cheek tooth extraction and to identify possible risk factors for these complications that could be used to predict their occurrence and hopefully reduce their prevalence.

STUDY DESIGN

Retrospective cohort study.

METHODS

Clinical records of all cheek teeth extractions performed between February 2004 and September 2018 were examined and written questionnaires sent to owners. Details of post-extraction complications were analysed and logistic regression was used to evaluate potential associations between the likelihood of post-extraction nonhealing alveolus managed by the authors and the variables: age, breed, reason for extraction, Triadan position and extraction technique.

RESULTS

Post-extraction complications were recorded following 58/428 extractions giving an overall complication rate of 13.6%, that caused a longer term clinical problem in 34/428 (7.9%) cases, with complications being asymptomatic or quickly self-resolving in the other 24 cases (5.6%). The most frequent complication was alveolar bone sequestration, including alveolar infection. Risk of developing a post-extraction alveolar disorder managed by the authors (n = 53) increased following extraction of the mandibular 06s, 07s or 08s compared with all other cheek teeth combined (P = .001); for cheek teeth with apical infections (P = .002) compared with those without; and following repulsion or minimally invasive transbuccal extraction (MTE) than following oral extraction (P = .01 and P = .02 respectively).

MAIN LIMITATIONS

Length of time between exodontia and survey data collection for some cases, use of clinical records and survey data and biases associated with decision to treat.

CONCLUSIONS

In agreement with previous studies, oral extraction had the lowest risk of complications. This study provides new information regarding the prevalence, types and risk of development of post extraction complications. Knowledge of these risk factors may help reduce these complications.

Recent developments in equine dentistry

Equine dentistry is a rapidly developing clinical specialty. It has benefitted from key advances in anatomical and physiological research, development of equipment and instrumentation, utilisation of standing sedation and anaesthesia protocols, a change towards minimally invasive surgical techniques, and the introduction of restorative and endodontic techniques translated from techniques used in human and canine dentistry. Anatomical research has provided further insight into the endodontic system of incisors and cheek teeth and how it changes throughout development with age. Studies of the periodontium have demonstrated a rich vascular supply and repair capacity. Routine dental visits are increasingly being performed utilising sedation and clinical instruments for routine examinations. Equipment has become more efficient, battery-operated and miniaturised giving benefits to both equine dental maintenance work and advanced techniques, assisting the transition to minimally invasive techniques, and the development of endodontic and restorative dentistry. Diagnosis has also benefitted from advances in equipment such as patient-side digital radiography systems, high definition oroscopy, and small diameter flexible fibrescopes that are capable of visualising inside a pulp canal. Dental units combining endodontic high- and low-speed drills, suction and air or water flush are becoming increasingly used and adapted for equine use. Sedative combinations and standing anaesthesia protocols have meant that revisions of traditional techniques, as well as novel techniques, can be performed with almost no requirement for general anaesthesia. Equine dentistry can only continue to advance in this way if there is early identification of dental disease through clinical oral examinations, leading to a system based on prophylaxis, as in human dentistry. This necessitates a change in attitude of the public and industry in general to a proactive approach, with early intervention based on examination and diagnostic findings of practitioners and not necessarily based on the clinical signs displayed by the patient.

A Retrospective Study of the Incidence and Management of Complications Associated With Regional Nerve Blocks in Equine Dental Patients

Regional anesthesia of the equine head is commonly performed to allow oral extraction of diseased teeth in the standing horse. The use of 4 blocks (infraorbital nerve, maxillary nerve, mental nerve, and mandibular nerve) is well documented for desensitization of dental quadrants for oral surgery for exodontia, but descriptions of associated complications are limited. A total of 270 regional nerve blocks were performed on 162 equine patients in a second opinion referral hospital setting. Criteria for inclusion in the study included a 24-hour stay in hospital, that the blocks be performed by one clinician and at minimum, a 2-week follow-up examination be performed. A total of 8 complications were identified in 7 patients representing a 2.96% incidence of complication. Complications included supraorbital hematoma (3), local hematoma (2), lingual self-trauma (2), and nerve block failure to desensitize (1). Treatment and management of complications are discussed. Complications associated with regional anesthesia may be reduced by reducing anesthetic volumes, precise needle placement, familiarity with the facial anatomy relevant to nerve blocks, adequate restraint, aseptic technique, postprocedural muzzling, and the use of a newly opened bottle of local anesthetic.

Equine cheek tooth extraction: Comparison of outcomes for five extraction methods

BACKGROUND

Post-operative complications are reported for all methods of equine cheek tooth extraction but not all methods carry the same risks. An outcome comparison for commonly used methods is needed so that clinicians can make informed treatment decisions.

OBJECTIVES

We conducted a side-by-side comparison of five cheek tooth extraction methods, comparing types and incidence of complications among oral extraction, tooth repulsion (three surgical approaches) and lateral buccotomy techniques.

STUDY DESIGN

Retrospective clinical study using hospital medical records.

METHODS

Medical records of all horses undergoing cheek tooth extraction between 1997 and 2013 were reviewed. Logistic regression was used to determine the likelihood of various post-operative complications, comparing oral extraction, tooth repulsion by maxillary and mandibular trephination or maxillary sinus bone flap, and lateral buccotomy.

RESULTS

The study included 137 horses and 162 cheek teeth extractions. Oral extraction was successful in 71% of patients in which it was attempted. Oral extraction (n = 55) had the lowest incidence of complications (20%) and repulsion by sinus bone flap (n = 20) the highest (80%). Complication rates for repulsion by maxillary (n = 19) and mandibular trephination (n = 28), and extraction by lateral buccotomy (n = 15) were 42, 54 and 53%, respectively. Cheek tooth repulsion by sinus bone flap significantly increased the odds of damage to adjacent teeth, post-operative sinusitis, damage to alveolar bone, delayed alveolar granulation and orosinus fistulation. Repulsion by maxillary trephination significantly increased the odds of superficial incisional surgical site infection; and extraction by lateral buccotomy significantly increased the odds of facial nerve neuropraxia. Post-operative pyrexia was more common in all repulsion methods.

MAIN LIMITATIONS

Some clinically relevant differences may have been missed due to small group numbers in several categories.

CONCLUSIONS

Oral extraction was associated with fewer post-operative complications than any other methods. Standing oral extraction remains the preferred choice, and recent surgical advances promise to further improve its success rate.

Cheek teeth apical infection in cattle: Diagnosis, surgical extraction, and prognosis

OBJECTIVE

To report the clinical presentation, treatment, and outcome of cattle undergoing surgical extraction of apically infected cheek teeth (CT).

STUDY DESIGN

Short case series.

ANIMALS

Nine adult cattle.

METHODS

Medical records were searched for cattle having a diagnosis of apical infection of CT that were treated with surgical extraction between 2005 and 2017. Data retrieved included clinical examination, ancillary tests, surgical procedure, and outcomes.

RESULTS

The main presenting complaints were mandibular swelling and decreased appetite and milk production. In total, 7 mandibular and 3 maxillary CT were extracted, 7 molars and 3 premolars that were distributed more frequently on the left dental arcades (n = 7 CT). Two cattle had no visible external lesions. Radiograph images revealed that lucency surrounded all affected tooth roots. Mandibular teeth were removed by lateral buccotomy with removal of alveolar bone plate or retrograde repulsion, and maxillary teeth were removed by repulsion through a maxillary sinus flap. Most common bacterial isolates consisted of anaerobic bacteria (6/11 isolates) and Truperella pyogenes (3/11 isolates). The most common complications included inability to remove the tooth intact (n = 4 cattle) and surgical site infection (n = 5). All cattle remained in their herd after treatment.

CONCLUSION

Surgical extraction of CT was achieved in all 9 cattle. The postoperative morbidity was high but without long-term consequences on animal productivity.

CLINICAL SIGNIFICANCE

Surgical extraction of CT is a successful treatment for apical infection in cattle.

Computed tomographic description of the highly variable imaging features of equine oromaxillary sinus and oronasal fistulae

Oronasal and oromaxillary sinus fistulae are well-documented complications following removal or loss of a maxillary cheek tooth. Diagnosis is currently based on a combination of oral examination, videoendoscopy, radiography, and computed tomography (CT). The objective of this retrospective, case series study was to describe the CT characteristics of confirmed oronasal and oromaxillary sinus fistulae in a group of horses. Inclusion criteria were a head CT acquired at the authors' hospital during the period of 2012-2017, a CT diagnosis of oronasal or oromaxillary sinus fistulae, and a confirmed diagnosis based on a method other than CT. Signalment, clinical findings, oral examination findings, presence of a confirmed fistula, and method for confirmation of the diagnosis were recorded. A veterinary radiologist reviewed CT studies for all included horses and recorded characteristics of the fistulae. Seventeen horses were sampled. Fourteen oromaxillary sinus fistulae and three oronasal fistulae were identified. All fistulae appeared as variably sized focal defects in the alveolar bone. Defects frequently contained a linear tract of heterogeneous material interspersed with gas bubbles, considered consistent with food. Computed tomographic attenuation of the material (Hounsfield units, HU) varied widely within and between cases. In 16 of 17 cases, there was evidence of concurrent dental disease in addition to the fistulae. Although the gold standard diagnostic test remains identification of feed material within the sinus or nasal passages, findings from the current study support the use of CT as an adjunctive diagnostic test for assessing the extent of involvement and presurgical planning.