| | Dental Endoscopy in the HorseAn oral examination is an essential part of the investigation of any suspected dental disease in the horse. The range of opening of the equine mouth is extremely limited even when the horse is sedated and this severely limits the visualization of the occlusal surfaces of the teeth and structures at the caudal aspect of the oral cavity. This can be facilitated by the use of dental mirrors, but better visualization is achieved by using an endoscope adapted for the equine mouth, which produces a greatly magnified image suitable for demonstration purposes. A rigid endoscope coupled to a halogen light source and a chip camera enables detailed visualization of the occlusal aspects of the cheek teeth. In addition, the buccal, lingual, and palatal aspects can be examined enabling greatly improved detection of oral ulceration and periodontal disease. Endoscopy enables more sensitive detection of dental diseases including dentine fissures, infundibular hypoplasia, caries, enamel fissures, dental fractures, periodontal pocketing, cemental caries, and other oral diseases including gingival ulceration. Under endoscopic guidance occlusal lesions can be probed and assessed more thoroughly. Although equipment costs are high and a moderate level of sedation is required, equine endoscopy represents a significant advance in the ability to accurately examine the equine mouth. Due to the improving understanding of equine dental pathology and better awareness of the signs of dental disease, there is a need to improve our diagnostic ability of dental disease, particularly in its early stages. In addition to advances in imaging techniques including scintigraphy, magnetic resonance imaging, and computed tomography,1 there remains a place for improved visualization of structures within the oral cavity. This can be achieved by better direct visualization using brighter light sources and angled mirrors and also indirectly by endoscopy. Dental endoscopy facilitates the exploration, visualization, magnification, and recording of lesions of the oral cavity and has a great role to play in education and documentation of lesions within the oral cavity. Dental endoscopy enhances the diagnostic value of the oral examination and has become a routine part of the author’s investigation of dental and oral diseases. Equipment  Dental endoscopy can be performed with either a flexible fiber-optic or video-endoscope or with a rigid telescope such as an instrument designed for human laparoscopy. Flexible endoscopes give satisfactory pictures, but the soft PVC sheath protecting the electrical and optical components can be damaged easily by sharp dental prominences with the result that sterilizing the endoscope becomes difficult and moisture leakage into the sheath can result in fogging of the lens. Rigid telescopes come in various lengths. A 50-cm telescope with a 50 to 70° viewing angle is ideal (Dr. Fritz Dental Endoscopes, Tuttlingen, Germany; Fig. 1). The durability is improved if the telescope is protected in a stainless steel sheath. An additional outer plastic sheath is a useful addition to dampen any vibrations when the telescope contacts the rostral teeth during examinations. The telescope is then coupled to a chip camera and monitor to enable viewing and, if necessary, recording of the images. Restraint Horses should be sedated for dental endoscopic examinations. The ideal depth of sedation results in the horse resting its chin on the headstand or suspended halter with a low probability of upward jerking of the head. Additional muscle relaxation can be achieved using 5 to 10 mg diazepam intravenously, which can result in reduced movement of the tongue, which can impair a thorough examination. Technique for Dental Endoscopic Examination The endoscopic examination is always preceded by a thorough visual and digital examination of the oral cavity. The initial visual inspection is performed before washing the mouth out to identify any sites of food accumulation. The author’s protocol for an endoscopic examination is to start examining the occlusal dental surfaces, beginning with cheek tooth 106 and then advancing the endoscope caudally inspecting each occlusal surface, in turn noting any defects in the occlusal surface which may be of pathological significance. Any potential defects in the occlusal surface, particularly of the secondary dentine corresponding to the pulp horns, or areas of infundibular cemental hypoplasia are re-examined while inserting a fine probe into the site of the defect. The endoscope is then rotated and repositioned to examine the palatal mucosa and interdental spaces noting any fibrous food entrapment and diastema. The endoscope is finally rotated to the buccal aspect of 106, and advanced caudally to identify diastema, displaced teeth, and in particular mucosal ulcers, which may go undetected on a routine visual examination. The gag may need to be loosened slightly to enable sufficient cheek retraction to thoroughly explore the buccal mucosa. Deep periodontal pockets are thoroughly cleaned using a pick and water jet and then re-examined for the presence of inflamed granulating tissue. The findings for each arcade are then annotated onto the dental chart (Fig. 2) and the second arcade commencing with 206 is examined. The mandibular arcades are then examined in a similar fashion. When examining the mandibular arcades, the lingual aspect of the arcade may be visualized more successfully if an additional tongue retractor is used, particularly at the caudal aspect of the arcade. Lesions Identified during Dental Endoscopy Dental Fractures While most dental fractures are easily identified on inspection with the naked eye and by digital palpation, dental endoscopy can provide useful additional information, such as the presence of ulceration associated with a sharp fracture fragment impinging on it. In addition, the detailed inspection of the fractured surface can reveal the site of the fracture and identify pulp exposure, which may provide useful guidance for subsequent treatments (Figure 3, Figure 4, Figure 5, Figure 6). Secondary Dentine Fissures The presence of small fissures in the secondary dentine is a potentially significant finding, which may indicate a potential communicating tract between the oral and pulp cavities or it can indicate previous pulpal insult, which has resulted in failure of secondary dentine production in the coronal pulp horn (Figure 7, Figure 8).2 Such fissures are almost impossible to identify on even the most thorough visual examination. A fine probe is inserted into the fissure to attempt to determine the depth, but in many cases it is impossible to advance even a fine probe very far into the fissure. In some cases, the significance is unclear, but as the knowledge of dental pathology improves their significance will become clearer and it is possible that restorative pulp sealing and endodontic therapy of such lesions may in the future prevent advanced pulpitis and caries eventually necessitating dental removal. Infundibular Hypoplasia Infundibular cemental hypoplasia is a commonly observed finding on dental endoscopy (Fig. 9). The size of the infundibular defect depends on the age of the horse, and, in young horses, the presence of wider infundibulae must not be automatically diagnosed as being due to hypoplasia and caries (Fig. 10). Infundibular hypoplasia most commonly affects maxillary cheek teeth 109 and 209, which results in a wider infundibulum with increased likelihood of food impaction.3 The putrefaction of this causes dissolution of the enamel and dentine and caries. Advanced, deep-seated infundibular caries can eventually penetrate through to the pulp, leading to pulpitis and death of the tooth. Peripheral cemental hypoplasia has also been commonly identified in ponies, particularly on the buccal aspect of the teeth. Enamel Fissures Enamel fissures are defects in the enamel and sometimes in the primary dentine, which are observed during dental endoscopy. They appear to be commonly observed in the teeth of mature horses. The clinical significance of these lesions is unclear, but since enamel has no reparative capacity, they represent permanent defects in the occlusal surface, which are a potential structural weakness possibly predisposing to dental fracture along the fissure lines. They can also be a potential entry portal for oral pathogens to enter the pulp. Gingival Ulceration Buccal ulcers represent a significant cause of oral pain. Most frequently they are the result of soft tissue trauma from a dental prominence, such as a cingula or focal dental overgrowths (Fig. 11). The accumulation of food at the site of dental lesion may also accelerate the development of oral ulcers. Such altered mastication will lead to altered masticatory movement and affect masticatory efficiency and also the rate of wear of the teeth. Small focal ulcers are commonly missed on routine dental examinations, and dental endoscopy enables a careful examination of the buccal mucosa on both its alveolar and buccal aspects right as far as the gingival reflection, and also of the lingual mucoperisosteum and the ventral surface of the tongue, which can also be the site of ulceration (Fig. 12). Diastema Individual diastema are usually detected during routine examination. However, in many cases, particularly where overcrowding is present (Fig. 13), diastema may be present in many sites and is often bilateral, particularly affecting the mandibular arcades. Endoscopic examination of these defects allows the most severely affected sites to be assessed and enables the appropriate treatment to be selected after a thorough examination of the whole mouth (Figure 14, Figure 15, Figure 16, Figure 17, Figure 18). Gingival Recession and Periodontal Pocketing Severe periodontal disease is usually the consequence of diastema and food accumulation in horses. Although diastema is identified during a routine visual examination, the extent of deep periodontal disease can be assessed far more accurately by endoscopic examination after clearing the periodontal pockets with a water pick. The presence of hemorrhage of dark pink granulating tissue in gingival pockets indicates acute gingival inflammation necessitating treatment of the periodontal disease. Dental Overgrowths Small dental overgrowths can be missed on oral examination, although in most cases they can be assessed by palpation. The presence of small but sharp overgrowths, particularly at the back of the mouth, is greatly clarified using endoscopy (Figure 19, Figure 20). References 1. 1Gibbs C. Equine dental imaging. In: Dacre IT editors. Equine Dentistry. (ed 2). Philadelphia, PA: Saunders; 2005;p. 171–201. 2. 2Dacre . Equine dental pathology. In: Baker , Easley editor. Equine Dentistry. (ed 2). Philadelphia, PA: Saunders; 2005;p. 87–107. 3. 3Dixon PM, Tremaine WH, Pickles K, et al. Equine dental disease. III. A long-term study of 400 cases: apical infections of the cheek teeth. Equine Vet J. 1999;32:182–194. MEDLINE |
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Department of Clinical Veterinary Sciences, University of Bristol, Langford, Bristol, UK  Address reprint requests to Dr. W. Henry Tremaine, University of Bristol, Department of Clinical Veterinary Sciences, Langford House, Langford, Bristol BS40 5DT, UK.
PII: S1534-7516(05)00051-X doi:10.1053/j.ctep.2005.04.011 © 2005 Elsevier Inc. All rights reserved. | |
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