Apicoectomy or Periapical Curettage: Two Different Techniques for Two Different Problems

Take Home Message—Apicoectomy is a prelude to endodontic therapy in the horse. Root tip amputation exposes the pulpar channels for debridement and filling. Some publications have reported using periapical curettage as an adjunct to the treatment of periapical infection, without subsequent endodontic therapy. These are not comparable techniques either in terms of the skill set needed to use them or the science behind their usage. The methodology utilized in periapical curettage is not completely clear and the long term success, if one (dangerously) combines the success rate of multiple studies, is approximately 66 percent.

I. Periapical curettage

Dixon et al. (2000)¹ cite Uberreiter (1959) as having success with curettage of the apex of infected cheek teeth. Eisenmenger (1959) also suggested that some cases of “alveolar periostitis” could be managed by apicoectomy and root end drainage.² These successes were tempered by Wintzer and Jaksch (1986) in which the authors reported having to remove teeth after treatment failure using this methodology.³ Gaughan (1998) reported that curettage and establishment of ventral drainage would, in some cases, result in successful treatment of infected cheek teeth.⁴ In a paper focusing on apical infections of equine cheek teeth, Dixon et al. (2000) reported that mandibular cheek tooth infections typically occurred in younger horses (median age of 5 years) and almost 59% had a ventral draining tract.¹ Initial treatment included repulsion, however after some of these teeth were found to contain vital pulp; the authors attempted a slightly more conservative approach. In 12 subsequent horses (which had been infected for a median time of 8 months) the infected bone and periphery of the infected cheek teeth was debrided and the horse subsequently placed on 7 to 14 days of antimicrobial treatment. 9 of these cases were available for follow-up and 5 were completely successful (55%). Of the remaining 4, while a second unsuccessful curettage was performed, all horses subsequently had the affected tooth removed. Due to the poor success rate, the technique was abandoned.

Subsequent to the above study, Carmalt and Barber (2004) reported a similar technique in 11 horses.⁵ Of those horses, 2 were lost to follow up. Of the remaining 9, two required repulsion and 7 were considered successful (78%). Of those that required repulsion, one was clearly an example of poor case selection as it had an orocutaneous fistula whose passage ran down the caudal (distal) aspect of the tooth. The second only had evidence of gingival recession and periodontal disease (which may have been a marker of periapical disease) on oral examination.⁶ The authors report on oral examination findings post-surgery in two horses (8months and 14 months after treatment). In the former case there was no evidence of the previous insult and the eruption of the tooth (407) was proceeding normally (as compared to tooth 307). In the latter case, dental eruption was uncompromised and there was no evidence of the original bony mandibular mass. Interestingly, inexplicably and controversially, these findings were reported despite the authors admitting to accidentally removing some of “the pulp without evidence of a subsequent occlusal defect.” Unfortunately this was only 14 months after the treatment and the horse was subsequently lost to follow up.

II. Apicoectomy

Simhofer et al. 2008) reported on apicoectomy as a prelude to endodontic therapy in the horse. This group reported a 58% complete, 17% partial success and 25% failure. This may constitute a 75% success rate (if one accepts that mandibular swelling may not totally resolve following treatment), however there were also apical sealant problems necessitating a second surgery in some cases. Previous clinical papers have described endodontic treatment successes ranging from 44 to 80%⁹ Given the complex anatomy of the equine pulp within cheek teeth and its age-associated variations, further work is needed to improve the success rate of equine endodontic treatment.

Bartmann et al. (2010) reported on a case series of 41 horses with mandibular fistulation. 31/41 fistulae were associated with apical cheek tooth infection, the remainder due to trauma or infectious damage to the mandible or parotid duct.⁷ 40/41 horses underwent surgical treatment. 2 had apicoectomy and endodontic treatment. The remainder underwent exodontia either by repulsion or intra-oral extraction. None had periapical curettage performed. The authors discuss that their cases were different from those reported by Carmalt and Barber (2004),⁵ in that all had a draining tract and that all pulps were deemed necrotic. They report that some of the previously reported cases were treated by curettage prior to the development of a ventral fistula and that none of the pulps were necrotic. They go on to state that determining grossly whether a pulp is necrotic or not, is difficult. While the statement makes practical and intuitive sense, the authors of the referenced paper did not report on the viability of the pulp. 9 of 11 horses had a draining fistulous tract in the paper by Carmalt and Barber (2004) and all affected teeth had only a single root involved. It may be that the horses reported by Bartmann et al. (2010) may have benefited from periapical curettage.

III. Discussion

Overall, apicoectomy is performed as part of the access preparation for surgical root canal procedures, or to facilitate repulsion of the tooth into the oral cavity. Periapical curettage is an effort to treat apically infected teeth by debridement of infected and necrotic tissues with assumption that there is reversible pulpitis rather than pulp necrosis. There is clearly a difference between these techniques.

Determining which of the two techniques should be applied to the horse with mandibular drainage associated with a cheek tooth infection is not straightforward. Is the tooth vital, with reversible pulpitis or, is there irreversible pulpitis or pulp necrosis? In the authors’ experience, accurate assessment of pulp vitality in the horse with apical abscessation is extremely difficult? Given that even in the hands of experienced equine dentists the success rate of endodontic treatment ranges from 58 – 80%, careful periapical curettage (without pulpar compromise) in selected cases may result in treatment success and retention of the tooth. It is also important to remember that in the hypsodont dentition, teeth will continue to erupt with necrotic pulp or after pulp removal and as such, a lack of clinical signs or poor case follow-up without complete oral/dental exams should not constitute treatment success for the treating veterinarian.

References

1. Dixon PM, Tremaine WH, Pickles K, et al. Equine dental disease Part 4. a long-term study of 400 cases: apical infections of cheek teeth. Equine Veterinary Journal 2000;32:182-194.
2. Eisenmenger F. Surgical treatment of alveolar periostitis in young horses. Wien Tier Mochenschr 1959;46:51-70.
3. Wintzer HJ, Jaksch W. Digestive diseases. Equine diseases 1986:89-147.
4. Gaughan EM. Dental surgery in horses. Veterinary Clinics of North America-Equine Practice 1998;14:381.
5. Carmalt JL, Barber SM. Periapical curettage: An alternative surgical approach to infected mandibular cheek teeth in horses. Veterinary Surgery 2004;33:267-271.
6. Ramzan PHL. Oral endoscopy as an aid to diagnosis of equine cheek tooth infections in the absence of gross oral pathological changes: 17 cases. Equine Veterinary Journal 2009;41:101-106.
7. Bartmann CP, Bienert-Zeit A. Etiology and surgical treatment of mandibular fistula in the horse. Pferdeheilkunde 2010;26:191-198.
8. Simhofer H, Stoian C, Zetner K. A long-term study of apicoectomy and endodontic treatment of apically infected cheek teeth in 12 horses. Veterinary Journal 2008;178:411-418.
9. Prichard MA, Hackett RP, Erb HN. Long-term outcome of tooth repulsion in horses - A retrospective study of 61 cases. Veterinary Surgery 1992;21:145-149.