EQUINE VETERINARY EDUCATION / AE / MARCH 2016


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Case Report


Equine odontoclastic tooth resorption and hypercementosis affecting all cheek teeth in two horses: Clinical and histopathological findings


N. T. Moore*†, W. Schroeder‡ and C. Staszyk§


†Moore Equine Medical and Dental Services, Georgetown, Texas, USA; ‡Equine Clinic: Surgery and Radiology, Freie Universit€


Veterinary Medicine, Justus-Liebig-University Giessen, Germany. *Corresponding author email: nick@mooredvm.com


Keywords: horse; equine odontoclastic tooth resorption; hypercementosis


Summary This report describes the clinical presentation and histopathological findings of two horses with equine odontoclastic tooth resorption and hypercementosis (EOTRH) affecting all cheek teeth. Equine odontoclastic tooth resorption and hypercementosis is a well documented condition known to affect the incisors, canines and occasionally the premolars in horses. At this time there have been no documented cases of EORTH affecting all cheek teeth described in the peer reviewed literature. This paper documents the first reported cases of EOTRH affecting the cheek teeth in one horse in the United States and one from Germany.


Introduction


During the last decade, incisor disorders associated with dental resorption and bulbous enlargement of the intra- alveolar parts of the teeth have been described in several reports (Gregory et al. 2006; Baratt 2007; Caldwell 2007; Kreutzer et al. 2007). The condition appears to be the result of two separate cellular processes, i.e. odontoclastic tooth resorption and hypercementosis characterised by an unregulated deposition of dental cementum (Staszyk et al. 2008; Sykora et al. 2014; Lorello et al. 2015). Therefore, the term equine odontoclastic tooth resorption and hypercementosis (EOTRH) was suggested (Staszyk et al. 2008). Equine odontoclastic tooth resorption and hypercementosis is a well described painful condition known to affect the incisors, canines and occasionally the premolars of older horses (Staszyk et al. 2008). Some horses show more resorptive lesions of the root and alveolar bone while others exhibit hypercementosis leading to a bulbous enlargement of the reserve crown and root (H€


uls et al. 2012; Earley and Rawlinson


2013; Sykora et al. 2014). Clinically, most cases present with varying degrees of gingivitis, periodontitis, gingival recession, alveolar bone protrusion and periapical abscessation with associated drainage tracts (Staszyk et al. 2008; Earley and Rawlinson 2013). Radiographic findings may include root resorption, root and reserve crown enlargement due to hypercementosis, alveolar bone loss, osteomyelitis, loss or disruption of pulp canal, and intra-alveolar root fractures (Staszyk et al. 2008; Earley and Rawlinson 2013). The disruption in the normal intra-alveolar dental architecture creates an environment that appears to facilitate periodontal disease


Case 1


A 20-year-old Arabian gelding was initially examined by Moore Equine Medical and Dental Services for behavioural changes that had developed over several months. The horse was exhibiting head-shyness and appeared to have difficulty eating. The horse had received regular dental care since living with the current owner (5 years). Following sedation, an oral examination revealed slightly protuberant maxillary 06s and 09s, the buccal margins of the maxillary cheek teeth and lingual margins of the mandibular teeth were sharp but


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(Rawlinson and Earley 2013). Resorptive lesions have been documented to involve the cementum, enamel, dentine and occasionally the pulp cavity (Staszyk et al. 2008). Histological examination has revealed extensive infiltration of white blood cells into the resorptive lesions while the affected tooth margins contain odontoclasts housed in Howship’s lacunae (Staszyk et al. 2008). Regions of hypercementosis have been described to cover Howship’s lacunae as well as normal portions of the root with irregular cementum deposited in a layered pattern (Staszyk et al. 2008). Severe cases can have extremely bulbous roots and reserve crowns several times larger than the original healthy tooth. The aetiology of this condition is currently poorly understood but recent work by Sykora et al. (2014) has revealed a potential involvement of Treponema and Tannerella spp. in the pathogenesis of periodontal disease that can occur with EOTRH. Resorptive lesions have been reported in other species as well as in man. In cats, a condition known as feline odontoclastic resorptive lesions (FORL, syn. resorptive lesions RL) is a common condition of unknown aetiology (Gorrel and Larsson 2002; Reiter and Mendoza 2002) that shares certain characteristics with EOTRH such as the infiltration of inflammatory cells into the resorptive lesions; however, FORLs lack the excessive hypercementosis often seen with EOTRH (Earley and Rawlinson 2013). Furthermore, FORLs are reported to occur more often in the molar and premolar teeth (Roux et al. 2005) in contrast to EOTRH which has been mostly reported in the incisors and canine teeth until this report. No treatment other than exodontia is currently available (Earley and Rawlinson 2013) and this report is the first to document the occurrence of EOTRH affecting cheek teeth (CT). The modified Triadan system of nomenclature is used throughout this report (Triadan 1972; Floyd 1991).


at Berlin, Germany; and §Institute of Veterinary Anatomy, Histology and Embryology, Faculty of

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