33rd Annual Scientific Meeting proceedings

Introduction
Over the past three decades, significant improvements have been made in equine dentistry. New diagnostic techniques (e.g. oral endoscopy), advances in digital imaging (digital radiography, computed tomography) and anaesthesia (sedation protocols, local anaesthesia techniques) as well as numerous anatomical and clinical studies facilitated the evolution from a „neglected field of study“ ¹ into a recognised clinical speciality. Today, a better understanding of dental and periodontal pathology and improved diagnostic modalities enable earlier diagnosis of dental disease. Conservative therapeutical approaches such as dental restorations and endodontic procedures might be considered as therapeutical options in selected cases. However, exodontia still remains the preferred treatment method in the majority of cases. While dental extraction techniques have been extensively focussed on in recent years, little information is currently available concerning endodontic treatment techniques and outcomes in peer reviewed literature. Considerable investments in equipment, a profound knowledge of dental pathology and dental materials, training and experience are required to successfully perform endodontic surgery². Consequently, the question as to whether equine endodontic treatment is a valid therapeutical option is justified.

Endodontic and restorative procedures in equines
Endodontic and restorative dental procedures are aimed at the preservation of affected teeth². Advantages of dental preservation are the continued use of the affected toot for mastication and the avoidance of extraction complications such as excessive antagonist eruption, mesial dental drift, oro-sinuidal or oro-nasal communications and alveolar sequestration².

Restorative and endodontic techniques²

1. Cavity restoration in teeth with vital pulp (carious cheek teeth infundibula)
2. Endodontic procedures involving vital pulp (pulpotomy)
3. Endodontic procedures involving non-vital pulp (pulp/root canal therapy)

Cavity restoration (carious cheek teeth infundibula, vital and healthy pulp)
Restorative dentistry is aimed at vital pulp protection, stopping of the progression of dental caries and the maintenance of dental function². Infundibular caries is a result of developmental hypocementosis, subsequent food impaction and acid destruction of the dental tissues³. Infundibular caries progression might trigger endodontic infection/pulpitis when the infundibular enamel is penetrated or might result in a mid- sagittal dental fracture^3,4. Restoration techniques for infundibular caries have been described^5,6. Careful case selection, meticulous cleaning and disinfection of the carious infundibula under endoscopic guidance and restoration of these lesions with dental materials that wear with the surrounding tooth are preconditions for a successful outcome^6,7,8.

Endodontic treatment techniques in acutely inflamed, vital teeth (pulpotomy)
Endodontic treatment techniques for acute pulp exposure have been described in the horse⁹. In a first step all necrotic and/or irreversibly inflamed pulp is removed. Haemostasis and placement of a three-layer pulp capping are subsequently performed^2,9. Thus, the remaining vital pulp is protected and may form a layer of tertiary dentine, replacing the original column of secondary dentine^2,9. Anecdotal reports and personal experience with this technique are promising. However, clinical studies of long-term results have not been published yet.

Endodontic treatment techniques in teeth with necrotic pulp (root canal therapy)
If the vital pulp is necrotic or severely infected, complete removal of the pulp is required. (root canal procedure). In young and middle-aged horses, the pulp cavities expand in apical direction. It seemed logical to overcome this problem by using an apical approach². However, results were disappointing^2,10. In 2016, an orthograde endodontic approach for endodontically infected equine cheek teeth has been described¹¹. Repeated treatments are necessary in most cases^{2, 11}. However, this technique and all follow-up treatments can be performed in standing, sedated horses¹¹. The aim of this technique is to stimulate the creation of an apical seal with tertiary (reparative) dentine². If this can be achieved, the remaining pulp canal(s) can be restored using a technique similar to infundibular restorations² with anecdotally promising results².

Conclusion
Restorative and endodontic techniques in equines are technically challenging, require advanced instrumentation² and ample experience. Peer reviewed publications evaluating the success rates of pulpotomy and orthograde endodontic treatment in equines are not yet available². Consequently, endodontic procedures in equines will remain a topic for trained and experienced specialists in this field in the near future.

References

1. Dixon PM. Equine dental disease – a neglected field of study. Equine Vet Educ 1993;(5):285-286.
2. Pearce CJ. Recent developments in equine dentistry. New Zealand Vet J, 2020;68(3):178-186.
3. Baker GJ. Some Aspects of Equine Dental Decay. Equine Vet J;6(3):127–130.
4. Dacre I, Kempsot S, Dixon PM. Equine idiopathic cheek teeth fractures. Part 1: Pathological studies on 35 fractured cheek teeth, Equine Vet J. 2007;39:310-318.
5. Klugh DO, Brannan R. Infundibular Decay in Equine Maxillary Teeth. J Vet Dent. 2001;18(1): 26–27.
6. Pearce CJ, Brooks N. Long-Term Follow-Up of Restorations of Equine Cheek Teeth Infundibula (2006–2017). Front Vet Sci. 2022;8:793631.
7. Horbal A, Reardon RJM, Liuti T, Dixon PM. Evaluation of ex vivo restoration of carious equine maxillary cheek teeth infundibulae following debridement with dental drills and Hedstrom files, Vet J. 2017;230:30-35.
8. Du Toit N. Clinical significance of equine cheek teeth infundibular caries, Vet Rec. 2017;181(9):233-234.
9. Earley E, Rawlinson JT. A new understanding of oral and dental disorders of the equine incisor and canine teeth, Vet Clin N Am Equine Pract 2013;29:273-300.
10. Simhofer H, Stoian C, Zetner K. A long-term study of apicoectomy and endodontic treatment of apically infected cheek teeth in 12 horses, Vet J.2008;178(3):411-418.
11. Lundström. Description of a technique for orthograde endodontic treatment of equine cheek teeth with apical infections. Equine Vet Educ.2016;28(11):641-652.