Critical evaluation of ex vivo restoration of carious equine maxillary cheek teeth infundibulae following high-pressure gas and micro-particle abrasion P.M. Dixon *, D. Savill, A. Horbyl, R.J.M. Reardon, T. Liuti The Royal Dick School of Veterinary Studies and The Roslin Institute, Easter Bush Veterinary Centre, The University of Edinburgh, Midlothian EH25 9RG, Scotland, UK ARTICLE INFO Article history: Accepted 4 April 2014 Keywords: Equine dentistry Cheek teeth Infundibular caries Restoration ABSTRACT Infundibular caries of the equine maxillary cheek teeth is an important disorder that can lead to dental fracture or apical infection. Treatment by removing food debris and carious dental tissue from affected infundibulae using high-pressure abrasion with aluminium hydroxide micro-particles, followed by filling the cleaned defect with endodontic restorative materials is a recommended treatment. However, al- though anecdotally considered a successful treatment option, there is currently no objective evidence to support this claim. Forty maxillary cheek teeth (CT) that contained 55 infundibulae with caries (mainly grade 2) were extracted post-mortem from 21 adult horses. Five of the CT were sectioned prior to treatment to facili- tate visual examination of the carious infundibulae. The remaining carious infundibulae were cleaned using high-pressure abrasion with aluminium hydroxide particles and five CT were sectioned to assess the efficacy of this cleaning process. The remaining 30 CT containing 39 carious infundibulae were then filled with a composite restorative material. The efficacy of this restoration was assessed by computed tomography imaging followed by direct visual examination after sectioning the teeth. Only 46% (18/39) of restored infundibulae, all with shallow (mean 9.6 mm deep) defects, were fully cleaned of food debris and carious material, and filled with restorative material to their full depth. Of these 18, 11 had peripheral defects around the restoration, leaving just 18% (7/39) of restorations without any gross defects. The remaining 54% (21/39) of infundibulae (mean depth of infundibular caries defect, 18.3 mm) still contained food debris and/or carious material in more apical locations, with infundibulae with the deepest caries defects being the least effectively cleaned. The findings of this study indicate that high-pressure micro-particle abrasion is only effective in cleaning food debris from shallow, carious CT infundibulae and consequently, the majority of subsequent infundibular restorations are imperfect. © 2014 Elsevier Ltd. All rights reserved. Introduction Equine maxillary cheek teeth (CT) contain two crescent-shaped infundibulae, i.e. enamel invaginations that extend from the oc- clusal surface for much of the length of the tooth. These infundibulae should normally be filled with cementum, except for a small central defect (Fig. 1), the site of the former vascular supply from the oc- clusal aspect of the dental sac (Kilic et al., 1997; Dixon et al., 2011). The fact that many horse and donkey CT infundibulae are incom- pletely filled with normal cementum is considered a likely contrib- utor to the development of caries (Becker, 1962; Baker, 1970; Kilic et al., 1997; du Toit et al., 2008a, 2008b). The results of a recent an- atomical study indicated that 88% of equine CT infundibulae had areas of cemental developmental hypoplasia, or contained cemen- tum that was discoloured, porous, or carious, with the Triadan 09 infundibulae being disproportionally affected by the most severe cemental defects (Fitzgibbon et al., 2010). Similarly, a recent com- puted tomography study by Windley et al. (2009) found lesions in 90% of all CT infundibulae. A consequence of infundibular cemental defects is the impac- tion of food deep into these spaces and the subsequent develop- ment of caries. These lesions may remain confined to the infundibular cementum (grade 1 according to the modified Honma grading system [Dacre, 2005]; Fig. 1), extend to the underlying enamel (grade 2; Fig. 2), involve enamel and dentine (grade 3; Fig. 3), or even result in the loss of dental integrity (grade 4). Consequences of such ex- tensions of caries include pulpar and thus apical infection of af- fected CT (Dacre et al., 2008), or more commonly, mechanical weakening of affected teeth. This may include coalescence of both carious infundibulae and lead to midline sagittal fractures (Dacre * Corresponding author. Tel.: +44 131 6506242. E-mail address: p.m.dixon@ed.ac.uk (P.M. Dixon). http://dx.doi.org/10.1016/j.tvjl.2014.04.004 1090-0233/© 2014 Elsevier Ltd. All rights reserved. The Veterinary Journal 200 (2014) 368–374 Contents lists available at ScienceDirect The Veterinary Journal journal homepage: www.elsevier.com/locate/tvjl