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Home , Hypercementosis, Veterinary dentistry

2015 WINTER MEETING

Sunday, February 8, 2015 Burlington Hilton Hotel

Robert M. Baratt, DVM, FAVD, FAVD/Eq., AVDC/Eq. Salem Valley Veterinary Clinic Salem, CT [email protected]

BEYOND FLOATING TEETH: COMPREHENSIVE ORAL HEALTH ASSESSMENT AND TREATMENT FOR THE EQUINE PRACTITIONER Schedule 7:00 – 9:00 Registration – 1st floor 7:45 – 8:45 USDA Accreditation – Vermont Room – 2nd floor 8:00 – 4:30 Exhibits Open – Montpelier Room – 1st floor 9:00 – 4:15 CE Programs (breaks at 10:30 and 2:45) Small Animal Cardiology – Adirondack A/B – 1st floor Equine – Adirondack D – 1st floor Marketing and Communications – Lake Champlain Rm – 2nd floor noon–1:15 Lunch – Green Mountain Ballroom (1st floor behind elevators)

HOLD THE DATE!

VVMA SUMMER MEETING Thursday and Friday, June 18-19, 2015 Burlington Hilton Hotel Thursday, June 18  Programs TBA  VVMA Member Wine Tasting Reception 4:45-7:00 p.m. Magnolia Bistro, One Lawson Lane, Burlington Sponsored by Merial

Friday, June 19  Small Animal Program TBA  Large Animal Program - Food Armor HACCP Program for Proper Drug Use. This is a proven six-step on-farm program to ensure food safety (both meat and milk) and responsible medication use on dairy farms.

Thanks for joining the Vermont Veterinary Medical Association! We are pleased to welcome the following new members who joined since our 2014 Summer Meeting:

Sarah Bronko, Veremedy Pet Hospital Rebekah DeBolt, Petit Brook Veterinary Clinic Amy Cordner, Burlington Emergency and Veterinary Specialists Colleen Flaherty, Qi Veterinary Clinic Erin Forbes, Mountain View Animal Hospital Megan Foy, Wood Pond Veterinary Services David Stevenson, Animal Medical Hospital of Northern Vermont Michaela Wozniakewicz, Rutland Veterinary Clinic and Surgical Center Helia Zamprogno, Burlington Emergency and Veterinary Specialists

88 Beech Street, Essex Junction, VT 05452 (802) 878-6888 • www.vtvets.org • [email protected]

For questions or more information on the VVMA, contact Executive Director Kathy Finnie Thank You to Our Exhibitors and Sponsors

Aesculight Rich Noss [email protected]

Boehringer-Ingelheim Lisa Karcher [email protected] Sponsor of Dr. DeFrancesco Elizabeth Olson [email protected]

Burlington Emergency Veterinary Specialists Jennifer LaDouceur [email protected]

Elanco Animal Health

Haun Gases Jamie Badger [email protected] Eric Eliason [email protected]

Idexx Laboratories Christina Griffin [email protected] Sponsor of Dr. Donnelly

Integralife Arthur Lubniewski [email protected]

Merial Mary Kathryn Edwards [email protected]

Pastore Financial Group Kyle Presson [email protected] Carl Harspar [email protected]

Patterson Veterinary Christopher Mancini [email protected] Tara Pitura [email protected] George White [email protected]

Penro Compounding Alison Moore [email protected]

Schiring Radiographic Imaging Jon Nealy [email protected] Chuck Gilroy [email protected] Steve DeVarney [email protected]

Universal Imaging Michael McElhinney [email protected]

Vetri Science Laboratories Cat McKeen [email protected]

Wilcox Pharmacy Tina Rotella [email protected]

EQUINE DENTISTRY Robert M. Baratt, DVM, FAVD, Dipl. AVDC/Eq Fellow, Academy of Veterinary Dentistry, Equine and Small Animal Founding Diplomate, American Veterinary Dental College Equine Specialty

Salem Valley Veterinary Clinic, 12 Center Street, Salem, CT 06420. 860-859-1649 Pieper Memorial Veterinary Center, 730 Randolph Rd., Middletown, CT 06457. 860-347-8387 [email protected]

I. Oral examination II. Dental III. Radiographic anatomy and signs of dental disease IV. Exodontia V. Equine odontoplastic resorption and hypercementosis VI. Dental disease in the geriatric horse VII. Dental disease in the Miniature Horse

I. Oral examination

Regardless of the chief complaint, the horse should be given a brief general physical examination prior to the detailed oral examination. The client should provide a history that includes the chief complaint, recent medical or surgical treatments, the recent/current use of medications, ability to shed the winter hair coat, quidding, observed weight loss, nasal discharge, and change in performance under tack/harness. Even routine oral health assessments should be preceded by this brief physical exam to assure that the horse is not febrile. Horses with even a low grade fever will have a significant adverse reaction to alpha-2 agonist sedative-analgesics manifest as tachypnea and poor ventilation.

The head should be examined for asymmetry or swelling and palpated for detection of areas of hyperesthesia and lymphadenopathy. The airflow from both nostrils should be evaluated and the presence of malodor noted. While not pathognomonic for dental etiology, a unilateral, malodorous nasal discharge is highly suggestive of sinusitis secondary to dental disease, whereas a unilateral nasal discharge without odor should be considered much more likely due to primary sinus disease. Other signs that are occasionally related to dental disease are epiphora or ocular discharge from dental disease extension into the nasolacrimal duct, head shaking, and ptyalism. Finally, the lips should be raised for examination of the and occlusion prior to sedation and placement of the full mouth speculum. This part of the exam will give the clinician a good read on the horse’s temperament and the will help in the formulation of a sedation protocol.

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Oral examination requires adequate patient sedation, a full mouth speculum and a bright light. Headlights work best if they are situated as close to the clinician’s eye level as possible, as opposed to inexpensive headlights that sit on the operator’s forehead. In general, the cost of the light is directly proportional to the brightness. Other instruments that are necessary for a comprehensive oral exam are a dental explorer, , cheek retractor and dental mirror. The explorer is a fine-tipped instrument, often in the shape of a shepherd’s hook, which is used to detect small surface irregularities on the teeth. It is particularly important in the detection of small cavities (defects) on the occlusal surface of the cheek teeth. A defect in the center of the infundibulum of maxillary cheek teeth is normal (the remnant of the occlusal vascular supply to the infundibulum). The normal cheek tooth will have dark staining irregular secondary overlying pulp horns. It has a smooth reflective surface and the dental explorer slides over it without a “catch.” A defect overlying the pulp horn is evidence of abnormal production of irregular secondary dentin. A single pulp horn defect, in the absence of clinical signs of dental disease, such as facial swelling or malodorous nasal discharge, should be noted in the records. However, a cheek tooth with multiple occlusal defects overlying pulp horns is an indication for dental radiographs, as this tooth has a high likelihood of being nonvital.1,2 The presence of crown fractures should be charted. A very high percentage of crown fractures are through pulp horns, while sagittal fractures of the maxillary cheek teeth generally are through the infundibulae. The relationship of crown fractures to apical abscessation has been investigated.3, 4, 5 In the first paper in this series, the authors documented that fracture planes involved the pulp in 30 out of 35 cheek teeth examined, with the other 5 (maxillary) involving the carious infundibulae. The second paper, examining 68 horses referred with idiopathic cheek tooth fractures, found that the most common fracture was the maxillary lateral slab fracture (45%), and the teeth most commonly involved were the -08’s and -09’s. Clinical signs in these horses were quidding (47% of cases), bitting and behavioral problems (28%), signs of apical infection, e.g. bony swellings or nasal discharge (21%), anorexia and weight loss (15%), halitosis (13%) and buccal food impaction (12%). Treatment of this group of horses was conservative when possible, with tooth extraction in only 41% of the cases. The 3rd paper in this series examined 147 horses with idiopathic cheek tooth fractures in primary private practices in England and Ireland. In this group, 39% were asymptomatic and only 9% of the fractured teeth were extracted. Oral endoscopy is increasingly being used for routine oral examination6. The advantages of endoscopic examination include real time visualization of the oral cavity on a monitor and the ability to capture still images and video clips. Human oral cameras and arthroscopes have been adapted for this purpose. There are also instruments designed specifically for equine oral endoscopy.a,b A relatively inexpensive rigid oral endoscopic system can be put together with a a Veterinary Dental Products Europe. Unit 4 Merlin Way, Bowerhill Industrial Est., Melksham, Wilts SN12 6TJ, UK. Telephone: +44 (0)1225 690 001. Email: [email protected]

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10 mm, 45 degree human arthroscope and a digital camera with wifi capabilities and an iPad. The total cost of this system is $2000-2500, well below the cost of commercially available equine oral endoscopy systems.

The normal periodontal pocket depth is less than 3 mm. It is more common to note rather than increased periodontal pocket depth on the palatal/lingual and labial aspects of the cheek teeth. Feed stasis or packing between cheek teeth is frequently associated with diastemata and is a common cause of . All areas of feed packing should be cleaned and investigated with a periodontal probe. A long alligator forceps and scaler are useful for removing packed feed from diastemata. The periodontal probe and explorer are too delicate for this procedure. Forceful water irrigation is also helpful in cleaning feed material from diastemata. An engine cleaner, readily available at auto parts stores, can be adapted to a garden hose for this purpose. A small garden sprayer can also be used.

The periodontal ligament space allows for a limited normal mobility of the cheek teeth, which is greater in the geriatric patient. Lightweight forceps can be used to test each cheek tooth for mobility. Increased mobility due to attachment loss is generally indicative of advanced periodontal disease.

Class 1 are abnormalities of individual teeth in of normal length. A class 2 is defined as a short , and class 3 as a short -incisive . Class 1 malocclusions that involve individual teeth are frequently secondary to dental pathology. For example, single overlong teeth (“steps”) are often opposite missing or fractured cheek teeth in the opposing row. Similarly, a focal overgrowth of a transverse ridge is often opposite a maxillary cheek tooth with infundibular decay or a small crown fracture. Rarely, cheek teeth are rotated on their long axis and these teeth are quite often tipped (versed) buccally or palatally as well. Patterns of abnormal cheek are common, but should be critically evaluated, as many times there is no related pathology or masticatory dysfunction. A slight wave, especially in a middle aged or geriatric patient, is likely of no clinical significance. Similarly, ventral curvature (“smile”) and diagonal bites are usually not associated with masticatory dysfunction. Normal mandibular excursion to molar contact in either direction is a good indication of satisfactory masticatory function.

It is important to record the findings of the oral examination in the patient’s permanent medical record. A dental chart is the most convenient method of recording the oral examination and

b Dr. Fritz Dental Stick. Swissvet Veterinary Products LLC. 204 W Magnolia Ave, Knoxville, TN 37917. 877-794-7735. [email protected]

3 treatment. A dental chart that has one page for examination and a second page for treatments is preferred over a single page document. Hand-written charts can readily be scanned into computerized records, or the chart can be filled out digitally on a computer or tablet. Digital photography of the oral cavity is another excellent means of documenting oral pathology and treatments.3

II. Dental Radiography

The radiographic anatomy of the equine head is complex, and interpretation is dependent on the ability to produce diagnostic standardized images. Towards this end, attention to correct positioning is very important, as inadvertent obliquity in the images will greatly complicate interpretation. With the widespread availability of digital radiography in equine practices, the practitioner can more readily learn the correct positioning for the various projections of the equine head that are used to evaluate the and sinuses. Digital systems provide rapid processing of the image, enabling the practitioner to correct positioning errors and retake the image without significant delay. The two digital systems that are in general use are the computed radiography (CR) and digital radiography (DR) technologies. Both systems can be used with the same portable xray generators that are commonly found in equine practice. The CR phosphor plate is physically transferred to a processor connected to a computer with software that generates a digital image, whereas the DR sensor is directly attached to the computer with software which generates the digital image. While the DR system is faster, and facilitates learning the correct positioning for each radiographic projection, the DR systems are significantly more expensive and do not presently have sensors that can be used intraorally for imaging the cheek teeth. Most portable CR systems can process small plates that can be used for intraoral imaging of the equine teeth. Adequate standing sedation is a prerequisite for obtaining diagnostic dental radiographs. When working in the field, a quiet, clean and dry area of the barn is preferred. The practitioner is encouraged to use sedative-analgesic agents that provide profound sedation without inducing significant ataxia. For intraoral views, the tongue motion is reduced with the administration of either butorphanol or diazepam. Typically, the longer acting alpha agonists romifidine (0.05 - 0.10 mg/kg) or detomidine (0.01 – 0.02 mg/kg) are used in combination with butorphanol (0.005 – 0.01 mg/kg). When performing long procedures, most practitioners will use these drugs in a constant rate infusion (CRI), so that the horse can be maintained in an even plane of sedation. Various devices can be used to obtain open mouth projections of the cheek teeth. Some full mouth speculums, such as the Stubbs model, permit placement of the plate or sensor between the speculum and the horse’s face and do not interfere with the image. Many McPherson type speculums also can be used. However, the larger Conrad-style speculums may interfere with the

4 image. In some cases it is sufficient to place a bite block made of wood between the incisors; a small section of polyvinylchloride (PVC) plumbing pipe can also be used. With the CR systems, the cassette can often be attached to the horse’s head with an elastic cord or simply held in position between the speculum strap and the horse’s head. This helps reduce scattered radiation exposure to assistants, and eliminates motion artifact not associated with chewing. With the DR systems, the assistant should hold the sensor, and when possible, the horse’s head should be supported so that the head and the sensor both rest on the support. Again, this minimizes motion artifact. A radiographic marker that incorporates lead beads is useful for determining the orientation of the horse’s head relative to the ground, and the identification of fluid lines within the sinuses. Some type instrument for holding the intraoral cassette in the mouth is needed. A simple holder can be fabricated from a short length of ½ to ¾ inch diameter PVC pipe that is slotted at one end. The American Veterinary Dental College (AVDC) convention for presenting dental radiographs is labial mounting. The radiographs are positioned so the viewer is looking at the images as if looking into the patient’s mouth from the buccal side or the front of the horse. The right cheek teeth would be presented with the horse’s nose on the viewer’s right. The maxillary incisors would be crown down, and the mandibular incisors presented crown up; the horses left incisors would be to the viewer’s right. The dorsoventral (DV) and ventrodorsal (VD) views of the skull are usually presented with the nose down, and the horse’s right side on the viewer’s left. These conventions become important when the radiographic label cannot be readily affixed to the intraoral cassette or the label is cropped out of the image, and the presentation is used to determine right-left orientation. The imaging software with the CR or DR system may not always comply with this convention, and it will be necessary to horizontally flip some digital images or make changes to the imaging software. The American College of Veterinary presents all skull films with the horse’s head facing left. A left or right marker is required to determine the positioning that was used; by convention, the side of the head near the sensor is the one labeled in the lateral views.

Radiographic views that are standard for a radiographic examination of the equine dentition and associated sinus structures have been reviewed recently, and this manuscript can be used as a reference for positioning and normal radiographic anatomy.7, 8 Straight lateral. The lateral view is obtained by placing the cassette on the side of the head and the xray beam is centered on the rostral end of the facial crest, perpendicular to the sagittal plane. If the plate or sensor is on the horse’s right side of the head, the image is presented with the nose to the viewer’s right. However, due to the magnification of the left cheek teeth, which are closer to the xray generator, the apices of the cheek teeth that are imaged on the straight lateral view are of left cheek teeth. This view is used primarily to image the paradental structures (sinuses and of the skull), especially fluid lines within

5 the sinuses, but is also important for evaluation of gross dental deformities and abnormal tooth numbers. The mouth does not need to be open for this view, and a speculum is thus not necessary. Straight DV. The DV view is best obtained when the horse is heavily sedated and the head is allowed to rest on a low support. This allows the clinician to position his/her head directly over the xray generator, which greatly facilitates obtaining a true DV view. In this view the maxillary and mandibular cheek teeth are largely superimposed, however, one can evaluate the medial cortex of the and the lateral aspect of the maxillary cheek teeth and the associated maxillae and sinus structures. The nasal septum (vomer) should be on the midline in this view. Deviation of the nasal septum and soft tissue filling defects of the nasal passages can also be appreciated on the DV projection. The intraoral DV or VD projection can also be obtained with the appropriate size vinyl cassette and CR plate, and the use of a mouth speculum. This projection eliminates the arcade overlap, and provides better detail of the nasal passages and vomer bone. Off-set mandible DV. This view is obtained either by using ropes or a speculum designed for this purpose. Right and left offset mandible DV projections should be obtained so that the images can be compared and pathology more readily appreciated. Maxillary DV lateral oblique, extraoral. The positioning for this projection is obtained by setting up as for the straight lateral view, then raising the generator in the dorsal direction, with xray beam directed at the maxillary arcade which is closest to the sensor/cassette. As noted above, the DV oblique view of the right maxillary arcade is obtained with the right side of the head next to the sensor/cassette. For a survey view of the entire arcade, the beam is perpendicular to the long axis of the head, centered dorsal to the rostral end of the facial crest and is about 30 degrees to the horizontal plane. The image is presented with the horse’s nose to the viewer’s right by AVDC convention, or to the left by ACVR convention. This view is generally obtained in an effort to image the apical aspect of the maxillary arcade that is adjacent to the sensor/plate. By obtaining this projection with a bite block or speculum in place to hold the mouth open, the amount of arcade overlap is reduced, providing an image with more useful information that is easier to interpret. Maxillary VD lateral oblique, extraoral. This is a particularly important view when an intraoral projection of the maxillary cheek teeth is not possible (either when using a DR system or if the amount of chewing precludes imaging with a CR intraoral plate). For this projection, the mouth must be held wide open with a speculum or bite block, and the beam is directed through the interarcade space at the maxillary cheek teeth on the side of the head next to the sensor/plate. The VD angle is about 60 degrees from the horizontal plane, and the beam remains perpendicular to the long axis of the head. To obtain the correct projection, start with the straight lateral positioning, and then lower the xray generator without moving it in a caudal direction, which would result in caudo-rostral obliquity. When properly executed, this image will give apical detail similar to that obtained with intraoral plates.

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The AVDC presentation of the maxillary VD view is consistent with the method outlined previously for the lateral projection. For the right maxillary VD view, the sensor or plate is placed on the right side of the horse’s head, and the image is presented with the horse’s nose to the viewer’s right. The magnified projection of the left maxillary arcade may also be visible when a large sensor or plate is used. Mandibular VD lateral oblique, extraoral. The positioning for this view is quite similar to that used for the maxillary VD lateral oblique view. Due to the narrower space between the mandibles, there is generally considerable overlap of the mandibular arcades. In the mandibular VD oblique projection, the roots of the mandibular arcade closest to the generator are superimposed on the crowns of the target mandibular cheek teeth. For example, in the VD projection of the right mandibular cheek teeth, with the sensor/plate on the right side of the horse’s head, the left mandibular cheek teeth reserve crowns/roots are superimposed on the crowns of the right mandibular cheek teeth. To image the crowns of the right mandibular cheek teeth, the positioning is similar to that used for the right maxillary (open-mouth) lateral DV view (but at 10-15 degrees dorsal to the horizontal plane), with the xray beam centered on the crowns of the mandibular cheek teeth in the interarcade space. Mandibular DV lateral oblique, extraoral. This is an alternate projection of the mandibular cheek teeth, in which the sensor/plate is place ventrally, as for the straight DV view. The bisecting angle technique is used, which in this case means an xray beam angle that is about 45 degrees off the sagittal plane, with the beam centered on the mandibular cheek teeth closest to the generator. The image is quite similar to that obtained with the mandibular VD lateral oblique technique. Canine teeth. The maxillary and mandibular canine teeth can be imaged with either intraoral or extraoral techniques, using both DR and CR systems. For the extraoral view of the maxillary canine teeth the sensor/plate is positioned on the side of the head, and the xray beam is directed in a slightly caudorostral oblique angle with the xray beam centered on the canine teeth. Due to the proximity of the mandibular incisors, it is not generally possible to image both mandibular canines in one extraoral view. Alternatively, the sensor or plate can be placed in the mouth. This requires sufficient sedation to prevent chewing (an aluminum full mouth speculum can be used). The occlusal DV view of the maxillary canines is obtained with the same technique used to image the maxillary incisors described below. In the oblique intraoral views the target tooth is the canine closest to the xray generator. Thus, the dorsal oblique intraoral view of the left maxillary would be obtained with the generator held on the horse’s left side, with a DV angle of about 45 degrees to the sensor/plate.

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The mandibular canine teeth are also readily evaluated with the intraoral technique used for the mandibular incisors, but the views are VD rather than DV. Both mandibular canine teeth can be imaged with the occlusal view. Incisors. Incisors are imaged with a bisecting angle, intraoral technique with both DR and CR systems. Sedation sufficient to eliminate chewing is required, however an aluminum speculum can be used to protect the cassette or sensor. The straight VD (mandibular occlusal) and DV (maxillary occlusal) views can be complemented with oblique views that separate the 3rd incisors. In geriatric horses the teeth and incisive bones are angled so that the xray beam can be almost perpendicular to the sensor/plate, whereas this positioning will result in foreshortening of the incisors in the young horse.. Maxillary cheek teeth, intraoral. The bisecting angle technique is used to image the maxillary cheek teeth with the CR plate placed intraorally. The CR plate, when placed on the palate, is almost at a 90 degree angle to the long axis of the maxillary cheek teeth. Therefore, the xray beam is directed at about a 45 degree angle to the plate, centered on the apical aspect of the cheek tooth. This positioning must be modified by slightly more DV angle (50-60 degrees) in the young horse with a very long reserve crown, as the apical aspect may be projected off of the plate. Intraoral imaging of the 3rd maxillary molar is also challenging, as it tends to be projected off the caudal aspect of the plate. In some cases, the alternate extraoral views (maxillary VD obliques) will provide a better image of the 3rd maxillary molars. Mandibular cheek teeth, intraoral. To obtain this projection, the CR plate with 2.5x8.0 inch dimensions is placed between the tongue and the lingual aspect of the mandibular cheek teeth. This requires profound sedation, and even then, some horses will not tolerate this positioning of the plate. The xray beam is directed perpendicular to the plate, however, a slight VD projection will usually result in capturing more of the reserve crown without significant lengthening artifact. In a young horse, only the clinical crown and a portion of the reserve crown will be imaged, whereas in the geriatric horse almost the entire tooth can be captured. As noted above, the open mouth, mandibular DV oblique can also be used to image the crowns of the mandibular cheek teeth.

III. Radiographic anatomy and signs of dental disease

The equine hypsodont dentition has a unique gross, ultrastructural and radiographic anatomy that reflects the adaptive evolution of this herbivore species. The radiographic anatomy of the incisor teeth is similar in both the deciduous and permanent dentition. The extends supragingivally and the enamel can be identified on the lengthy extent of the reserve crown. The enamel-lined infundibulum is readily identified, and the pulp chamber is compressed labially by this structure. Although not readily apparent on intraoral radiographs, serial sectioning of

8 incisors or computed tomographic studies reveal a complex pulp chamber anatomy, which in cross section varies from oval just apical to the infundibulum, becoming compressed in the mesiodistal dimension and often dividing into two root canals apically. For most of the horse’s life, normal coronal is compensated for by continued eruption of the incisor and lengthening of the root, such that the overall length of the tooth in the radiographs appears relatively constant until the horse is greater than 25 years of age. Complicated crown fractures are those fractures of the clinical crown that result in pulp exposure; these fractures are relatively common in the horse – both in the incisors and cheek teeth. In brachydont species this type of fracture invariably results in and often in apical abscessation. The horse, perhaps due to the hypsodont nature of the dentition, appears to be capable of mounting a pulpal response to injury which maintains a viable pulp. The odontoblastic response to injury appears to be production of reparative (tertiary) dentin, similar in nature to that laid down at the occlusal aspect of the pulp horns during normal attrition. Evidence of a “dentinal bridge” just apical to the fractured incisor crown can sometimes be identified. Occasionally apical abscessation of incisors is evident radiographically as apical bone lysis, but this is rare, even in cases with fistulation. Equine odontoclastic and hypercementosis (EOTRH) is increasingly recognized as a form of periodontal disease involving the incisors and canine teeth of horses.9 The degree to which both tooth resorption and hypercementosis occurs is variable; some horses exhibit primarily tooth resorption with very little hypercementosis while in others hypercementosis is the predominant feature. Tooth resorption frequently occurs initially in the canine teeth and 3rd incisors, and involves the 2nd and 1st incisors sequentially over time. The tooth resorption most frequently involves the middle 1/3 of the tooth, with pathologic fracture occurring just apical to the free gingival margin. Another common pattern is hypercementosis and labial tooth extrusion, with labial exposure of the entire reserve crown and root. Radiographs of these extruded incisors generally exhibit a widened periodontal ligament space, and a foreshortened reserve crown due to the change in the angulation of the incisor as it is extruded. Unlike the incisors, the canine tooth has a brachydont response to injury: pulp exposure usually does result pulp necrosis and in apical abscessation. Osteomyletitis with intrabony abscess formation may occur in the absence of fistulation. As noted above, EOTRH affects the canine teeth; however, in the canine teeth resorption tends to occur in the coronal 1/3, and bony replacement is more commonly observed in the distal 2/3. Spontaneous fracture of the crown may be followed by resorption and bone replacement of the root with normal gingival healing by second intention. The internal anatomy of the cheek teeth is best appreciated with computed tomography. The infolding enamel obscures the anatomy of the cheek teeth in both intraoral and extraoral radiographs. Although the infundibulum of the maxillary cheek teeth is enamel-lined, even this structure is difficult to appreciate in radiographs. However, the area of interest is often the apical aspect of the cheek teeth and surrounding alveolus, and these structures can be readily evaluated

9 with conventional radiography. It must be kept in mind that significant alveolar bone lysis (probably about 40% bone loss) must occur before it can be appreciated radiographically as a periapical “halo.” Other signs of apical infection of cheek teeth are blunting (“clubbing”) of the tooth roots, widening of the periodontal ligament space, sclerosis (condensing osteitis) of apical aoveolar bone, thickening of the lamina dura and the apical deposition of cementum. In a recent study, periapical halo and apical sclerosis were the radiographic signs of apical abscessation with the highest sensitivity and specificity.10 The practitioner must be familiar with the radiographic appearance of radicular (“eruption”) cysts that are a normal finding in juvenile horses presented with unilateral or bilateral facial swelling over the apices of the maxillary . These cases lack nasal discharge or malodorous breath, and radiographically, the apical anatomy is well- defined with thinning of the alveolar bone, rather than condensing osteitis (sclerotic bone). Sinusitis secondary to apical disease of the maxillary molars is relatively common, usually presenting as a fetid unilateral nasal discharge. Fluid lines within the compartments of the maxillary and ventral conchal sinuses are a frequent radiographic finding. Overt dental disease is not always readily apparent radiographically, and differentiating primary sinusitis from that of dental etiology can be challenging. Careful oral examination for the presence of exposed pulp horns, crown fractures, abnormal periodontal pocket depths, and infundibular decay may direct the practitioner to the diseased tooth responsible for the sinusitis. Some cases will require CT for identification of the diseased cheek tooth, as the sensitivity and specificity of identification of apical disease is better with CT than digital radiography. The presence of an oroantral fistula may allow packing of feed material in the maxillary sinus. In these cases, the radiographic appearance of the sinus may be of a soft tissue density with an irregular radiopacity due to the presence of feed material, purulent fluid and gas. Osteomylitis accompanying severe sinusitis may allow communication of the right and left sinuses, resulting in a bilateral nasal discharge. Sinus cysts, and ethmoidal hematomas are causes of unilateral nasal discharge that are not of dental etiology that may be identified radiographically. Sinus cysts and ethmoidal hematomas are space-occupying soft tissue density structures with smooth, curvilinear outline on standard radiographic views. These structures may displace normal bony and dental architecture, but bone lysis tends to occur only with secondary . Neoplasms of dental origin are extremely rare in the horse, with only a small number of cases reviewed in the literature.11 Neoplasia of non-dental origin is occasionally observed in the equine head, and frequently has radiographic evidence of extensive alveolar bone lysis, with teeth “floating” in soft tissue. The absence of infundibulae, associated sinus structures and the presence of only two roots make radiographic interpretation of the mandibular cheek teeth somewhat more straightforward than the maxillary counterparts. Eruption cysts and apical abscessation both can present as firm swellings of the ventral mandible. As in the case of the maxillary cheek teeth, the eruption cysts tend to exhibit normal radiographic appearance of the apical aspect of the developing roots, with

10 a surrounding cystic structure and thinning of the cortical bone ventrally. Apical abscessation of the mandibular cheek teeth often presents with fistulation and puruluent ventral drainage. The draining tract can be probed and radiographically imaged to identify the diseased tooth. The apically diseased mandibular cheek tooth may present with a radiographic halo and condensing osteitis in the absence of ventral drainage. Other etiologies for mandibular swelling, such as fracture and neoplasia, can be diagnosed with standard radiographic techniques, but may require CT imaging for accurate three-dimensional assessment and treatment planning.

IV Exodontia Extraction of Equine Permanent Incisor and Canine Teeth Indications for extraction of permanent incisors in the horse include periodontal disease secondary to malpostioned or supernumerary incisors, incisor fracture with retained reserve crown and root, incisor fracture with endodontic disease and apical infection or secondary periodontitis, and equine odontoclastic tooth resorption and hypercementosis. While the equine incisors and canine teeth more closely resemble the brachydont dentition of small animals and man, there are distinct hypsodont features that make management of equine incisor and canine significantly different from the small animal and human counterparts. The equine incisor has two hypsodont features that distinguish it from the brachydon incisors: a long reserve crown and an infundibulum. The horse’s canine teeth, which undergo no significant attrition and have no real reserve crown, have a more brachydont anatomy. The incisors, with pulp adapted for continuous attrition, can remain viable after traumatic fracture that results in pulp exposure. The canine teeth, on the other hand, tend to undergo pulp necrosis when there is tooth fracture or iatrogenic pulp exposure. The incisor infundibuli, which practitioners and horsemen frequently refer to as “cups,” have been historically used to aid in aging the horse. This enamel lined conical structure flattens the pulp chamber, which is located labial to the infundibulum. Tooth fracture of the immature permanent incisor may not appear to involve the small coronal extension of the pulp adjacent to the infundibulum. Clinicians are familiar with the change in the shape of the occlusal surface of the incisors as the horse ages. This reflects the differing cross-sectional dimensions of the equine incisor reserve crown. In addition, the incisor reserve crown curves slightly medially and lingually. The canine tooth has a more exaggerated curvature in two dimensions, with less overall taper. While the maxillary and mandibular incisors have relatively scant alveolar and virtually no cortical bone surrounding them, the canines are imbedded in more dense alveolar and cortical bone. Incisor and canine tooth extractions can readily be performed in the standing horse, but sedation must be profound, as chewing and head movements will impede the procedure significantly. The author generally starts with a combination of an alpha 2 agonist (such as detomidine, 0.015 mg/kg) and an opiate (butorphanol, 0.007 mg/kg), then places an intravenous catheter for administration of a detomidine constant rate infusion (CRI). The detomidine CRI is easily

11 administered by adding 30 mg detomidine to 1 liter of fluids, and giving about 1 drop per second though a 15 drop/ml drip set. The rate is slowed or quickened to effect. While the incisors and canine teeth, as well as their soft tissue attachments and alveolar bone are theoretically anesthetized with maxillary and mandibular nerve blocks, this is not always clinically observed. The clinician should be prepared to add local infiltration of a rapidly acting anesthetic (lidocaine or articaine) when reaction to dental instruments is observed. A dental aspirating syringe can be used to inject the anesthetic into the dense gingiva and periodontal ligament. The aspirating syringe takes 1.5 ml carpules, which can be purchased from dental suppliers. Alternately, luer lock syringes and 25-27 gauge needles can be used. The instruments used for small animal and human dentistry are generally adequate for equine incisor and canine tooth extraction. However, in addition to small animal/human luxators, elevators and forceps, it is helpful to have a variety of bone curettes, rongeurs and gouges and mallets. Some canine tooth extractions require significant removal of bone, which is greatly facilitated with a high speed, compressed air or electric motor driven handpiece and carbide and/or diamond bur. The incisors have a very long reserve crown, often over 60 mm in length. Its length and curvature can make it a challenging tooth to extract. The procedure outlined below should facilitate extraction in most cases. 1. Use a #15 Bard Parker blade inserted flat against the clinical crown to cut the epithelial attachment at the depth of the sulcus of the tooth to be extracted and at least one incisor on either side. If the tooth being extracted is the 3rd incisor, extend the incision distally through the gingiva over the crestal bone for 1 cm. Extending the length of this “envelope” flap will lessen the likelihood of tearing the tissues during elevation of the incisor. If multiple incisors are extracted, the 3rd incisor is extracted initially, followed by the 2nd, then the 1st. 2. Use a sharp periosteal elevator, such as a #4 Molt elevator, to elevate the mucoperiosteum from the alveolar crestal bone for a depth of about 1 cm. It is important to elevate the periosteum from the alveolar bone. 3. Insert a luxator of appropriate curvature in the periodontal ligament space. The luxator is a cutting instrument and should not be used to try to leverage the tooth, as this will break the working end of the instrument. Pressure should only be applied in an apical direction, parallel to the long axis of the tooth. The luxator is removed and reinserted as needed to cut the periodontal ligament attachments as much as possible circumferentially around the tooth. 4. Winged or standard elevators are then used to apply pressure that will further tear the more apical periodontal ligament attachments. Appropriately sized bone gauges may also be used with a light mallet to cut the deeper periodontal ligament attachments and to elevate the tooth from the alveolus.

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5. When the tooth is sufficiently loosened from its periodontal ligament attachments, forceps are used to pull the tooth out in the direction of its eruption path. 6. If the crown has fractured so that there is nothing to grasp with the forceps, a threaded Steinman pin can be screwed into the root canal and used to pull the reserve crown fragment. 7. In the event that simple extraction by elevation is unsuccessful, vertical releasing incisors are made from the line angles of the incisors (preserving the papillae), so that a full mucoperiosteal flap can be elevated, alveolar bone removed, and elevation of the tooth completed. 8. After the incisor is extracted, the alveolar bone is smoothed with rongeurs and/or the diamond bur on a high speed dental handpiece. The envelope flap is sutured with interdental placement of simple interrupted sutures (3-0 Monocryl). If a full mucoperiosteal flap was elevated, this is closed as above, with additional simple interrupted sutures along the releasing incisions. Unless there is significant alveolar osteomyelitis, the canine tooth is generally not readily extracted by simple elevation. A mucoperiosteal flap is created to provide exposure of the alveolar bone, which is removed using a high speed dental handpiece with irrigation. With adequate bone removal, the tooth can then be elevated as described for the incisors. Primary closure of the mucoperiosteal flap is more successful in this location than for the incisors, where the author relies on second intension healing. The periosteum at the base of the flap is carefully incised, which frees the flap from unwanted tension during closure with simple interrupted sutures of 3-0 Monocryl, spaced 3mm apart.

Oral Extraction of Equine Cheek Teeth. It has been well-documented that oral extraction of equine cheek teeth has a significantly lower rate of post-operative complications than surgical extraction techniques. Appropriate case selection, instrumentation and technique are important for successful implementation of oral extraction of cheek teeth. The gross anatomy of the equine cheek tooth is age-dependent. At the time of eruption, the cheek teeth are completely covered by cementum. As the tooth comes into occlusion, the cementum is worn off the occlusal surface. Initially, the roots are unformed, the apical aspect of the tooth being a common pulp chamber with a large open apex. The pulp chamber is limited to the most apical aspect of the tooth; it divides into 5-6 pulp horns that extend almost to the occlusal surface coronally. The anatomy of the pulp horns is complex, with communications between pulp horns being common in the first years after eruption. By the time the tooth has been in wear for 2 years, the roots have become well-developed and by dental age of 5 years the pulp chamber has divided into a separate mesial and distal system without communications.12, 13 It is of clinical

13 importance that the coronal extent of the pulp horns may be as close as 2 mm to the occlusal surface in horses of all ages, this being more likely in the older, rather than the younger horse. Also of clinical significance is the presence of the 6th (mesial) pulp horn of the maxillary second (1st cheek tooth, 106 and 206). The angulation of the caudal cheek teeth in a rostral direction and the rostral premolars in a caudal direction maintains the tight interproximal relationship between the cheek teeth. Any abnormality that results in a between cheek teeth will predispose to feed impaction and periodontal disease. Feed impaction on the lingual or buccal aspect of the cheek tooth may also occur when a cheek tooth is versed buccally or lingually, is rotated, or has gingival recession and/or anatomy that results in a so-called “valve diastema.” Not all cheek teeth can be extracted orally, and attempts to orally extract inappropriate teeth may result in serious iatrogenic trauma to adjacent teeth, maxillary or mandibular fractures and oronasal or oroantral fistulas that are irreparable. Situations where cheek teeth are not good candidates for oral extraction include: • The crown is missing (fracture at the gingival margin), or only a fraction of the clinical crown is intact. • There has been mesial drift of adjacent teeth or hypercementosis of the diseased tooth so that the eruption/extraction path has smaller dimensions than the reserve crown-root • Infundibular decay has resulted in sagittal fracture of the tooth, with one fragment being small and mobile, while the other has 2 roots and is immobile. • There is significant ankylosis of the reserve crown or roots. • The tooth has one or more root fractures. As is evident from this list, careful oral and radiographic examination is important. In some instances, computed tomography will be needed to formulate an exodontia treatment plan. Teeth that the practitioner should consider good candidates for oral extraction are mobile teeth in the geriatric horse with no history of nasal discharge or fistulation, and no radiographic evidence of root fracture and apically infected cheek teeth with a dental age of 0-3 years. Tooth mobility does not necessarily mean an easy extraction. The crown may be mobile due to a reserve crown or root fractures; while the coronal fragment may be readily elevated, the apical fragments may require surgical extraction. While the apically infected tooth in the 5-8 year old has a very long reserve crown, the roots are not well developed and these teeth often have a relatively intact or minimally weakened clinical crown that will not fragment with the use of molar forceps. Sedation will generally be necessary for over an hour for all but the easiest cheek tooth extractions. An intravenous catheter should be aseptically placed in a jugular vein. After the initial administration of a loading dose of an alpha agonist opioid combination, such as

14 butorphanol and detomidine, the sedation can be maintained for several hours with a constant rate infusion (CRI) of detomidine. The author usually adds 30 mg of detomidine to 500 or 1000 ml sterile saline solution, and administers this too effect, about 1 drop/1-2 seconds, using a 15 drop/ml drip set. With adequate local , most horses will tolerate surgical procedures of the head. The profoundly sedated horse is often ataxic, and the use of stocks is highly recommended. Head support in the form of a dental head stand, dental halter or ring is necessary as well. The alpha agonists have a significant diuretic effect, and intravenous fluids should be administered to maintain hydration and blood pressure. Pre-operative administration of flunixin meglumine or phenylbutazone is advised, but the use of antibiotics is case-dependent. Regional nerve blocks are extremely important for a smooth oral extraction. The 2 blocks that are essential are the maxillary nerve block and the mandibular (inferior alveolar) nerve block. These nerve blocks should be performed only when the horse is profoundly sedated, as inadvertent needle contact with the nerve can result in a dangerously explosive reaction by the horse. (This is especially important when performing the infraorbital nerve block). While there are several published methods of performing the maxillary nerve block, most specialists now utilize the technique recently described in which the anesthetic is deposited in the extra-periorbital fat pad and allowed to diffuse to the infraorbital nerve within the pterygopalatine fossa.14 This technique allows desensitization of the infraorbital nerve without risk of laceration of the closely associated vessels, which would result in a retrobulbar hematoma, with possible permanent loss of vision. The materials needed for this technique include items used for clipping and a sterile prep of the skin at the injection site, a 3.5 inch, 22 ga needle and 12 cc syringe. Some clinicians prefer to use a Touhy needle and a loss of resistance syringe to enhance the tactile feel when performing this procedure. The injection site is located by following the facial crest caudally to where it starts to deviate dorsally to become part of the zygomatic arch, usually ventral to the middle third to caudal third of the eyeball. Roughly 1 cm caudal to the point of dorsal deviation of the facial crest and parallel to the plane of the body of the facial crest marks the point of entry for the needle. The needle is inserted perpendicular to the skin and advanced slowly, trying to detect the change in resistance as the needle passes through the fascia on the medial aspect of the massester muscle. If bone (the dorsal aspect of the maxillary tuber) is contacted at about a depth of 1-2 cm, the needle is repositioned 1 cm caudally and advanced another 1-2 cm into the extraorbital fat pad. Deposition of 10 cc of local anesthetic, such as Carbocaine (2% mepivacaine) is sufficient to anesthetize the infraorbital nerve, desensitizing all the maxillary cheek teeth on the ipsilateral side. The mandibular (inferior alveolar) nerve block at the level of the mandibular foramen anesthetizes the entire ipsilateral mandibular arcade. The nerve exits the mandible at the mental foramena, and can be blocked at this location if only the mandibular incisors require anesthesia. The mandibular foramen is located on the medial aspect of the coronoid process of the mandible at the level of the occlusal surface of the cheek teeth. To locate the foramen a line is drawn

15 caudally extending from the occlusal surface of the mandibular cheek teeth and a second line is drawn from the lateral canthus of the eye ventrally to the mandible, perpendicular to the first line. The intersection of these two lines locates the mandibular foramen. A Touhy spinal needle (6”, 20 ga.) or the needle from a jugular catheter (5 ½”, 16 ga) can be used; attaching the needle to the syringe with an extension set prevents inadvertent removal if the horse lifts its head during the injection. Mepivicaine or lidocaine (15-20 ml) is injected. Some clinicians prefer the use of the shorter acting lidocaine, as inadvertent desensitization of the lingual nerve will not persist as long, reducing the risk of postoperative tongue maceration when the horse resumes eating. A peripheral nerve stimulator and an insulated 6” spinal needle can be used for more precise placement of a smaller volume of anesthetic agent with reduced likelihood of inadvertent anesthesia of the lingual nerve.15 Regardless of the anesthetic agent used, the horse should be held off feed for several hours post-operatively. The horse’s head must remain open with a full mouth speculum for a prolonged period of time. Therefore the speculum must fit well and not place pressure on soft tissues. With the profound sedation and regional nerve blocks, the patient should not be chewing during the procedure, and fatigue or stress to the temporomandibular joint and muscles or mastication should not be an issue. It is very important that the surgeon have an adequate light source for direct visualization and placement of the instruments used for extraction; otherwise, there is significant risk of iatrogenic trauma in the form of fracture of adjacent teeth or even inadvertent extraction of the wrong tooth. The tooth is attached to the alveolar bone by the attached gingiva the periodontal ligament. The attached gingiva has a periosteal attachment to the alveolar bone and an epithelial attachment to the tooth at the depth of the sulcus. A long-handled, right angled periosteal elevator is used to cut the epithelial attachment and elevate the attached gingiva from the crestal bone. These elevators, which come in a right and left configuration, should be kept sharp. The normal sulcular depth of the cheek teeth is only 1- 3mm, so elevation of the attached gingiva does not create significantly more crown for application of the molar forceps. Molar spreaders are carefully placed in the interproximal space adjacent to the tooth to be extracted. Obviously, there is only one interproximal space adjacent to the -06 and -11 teeth (2nd premolar and 3rd molars). A dental mirror and/or oral endoscope must be used to confirm correct placement of this instrument. The instrument is then closed slightly and held for 1- 2 minutes (or rubber tubing can be wrapped around the handles to prevent operator hand fatigue). The spreaders are then removed and placed in the interproximal space on the other side of the tooth, if extracting the 3rd or 4th premolar, or 1st or 2nd molar. This procedure is repeated several more times, gradually creating a slightly wider interproximal space. During application of the spreaders there is stretching and tearing of the periodontal ligament, hemorrhage within the periodontal ligament space (alveolus) and compression of the alveolar bone (cribiform plate). Fracture of the diseased tooth, or adjacent teeth may occur if the surgeon applies too much force,

16 or if the spreaders are misplaced on the tooth. The spreaders are available in several sizes, but one should always start with the smallest size that still exerts a wedge effect. Once the spreaders have been applied for 10-15 minutes, there should be 1-2 mm or interproximal space with increased bleeding, and a significant increase in the degree of mobility of the tooth (evaluate mobility with molar forceps; the tooth usually will not be “finger loose” at this stage). Molar forceps are chosen that will grasp the clinical crown at the level of the alveolar bone ridge without slipping. A variety of molar forceps will be necessary, as there is not one that fits all the crowns well. If the molar forceps does not engage the tooth firmly, then it will slip and gouge the crown, often resulting in further fracture of the crown, which may make oral extraction impossible. Of course some cheek teeth will have pathology that predisposes to crown fracture during oral extraction (particularly infundibular decay of the maxillary cheek teeth), and the surgeon should have an alternate plan for extraction if the clinical crown breaks down during manipulation with spreaders or forceps. The molar forceps is held firmly in place by wrapping rubber tubing around the handles, and axial rotational force is applied by moving the handles of the forceps laterally to resistance, and holding them in that position for 30 seconds. Too much force application will cause the fracture of the tooth or alveolar bone. The handles are then moved in the opposite direction until resistance is felt, and once again held for 30 seconds. This process is repeated as long as necessary to fatigue/tear the periodontal ligament resulting in significant mobility of the tooth. Hemorrhage will increase, and if the tooth is “wiggled” with the forceps, the bleeding will become “frothy” as the blood is mixed with air. Once significant axial mobility of the tooth has been achieved, the fulcrum is placed and the handles are pushed with firm steady pressure so that the force is exerted on the tooth in a direction that approximates the eruption path of the tooth. The surgeon will not appreciate any change until there is a sudden release of the tooth. Patience is the key to success in this part of the procedure. Removal of the tooth then simply involves placing the molar forceps more apically on the tooth, and replacing the fulcrum. Very long teeth may have to be slightly tipped lingually as they are extracted; alternately, they can be cut with molar cutters (this is the only legitimate use of molar cutters). At this point the extracted tooth should be carefully examined for evidence of root fracture, the alveolus should be digitally examined and post-operative radiographs obtained. The alveolus can be debrided with Sims curettes and irrigated with 0.12% chlorhexidine gluconate solution. Packing the alveolus with gauze sponges for 3-5 minutes (while obtaining radiographs) is generally all that is needed for controlling hemorrhage. Placement of an impression material (vinylpolysiloxane) plug or some other material to prevent feed impaction in the alveolus is probably only critical if there is a significant fistula between the alveolus and the nasal passage or maxillary sinus. The author generally will place a VPS plug in an alveolus of depth greater than 40mm. The VPS should only be placed in the coronal 2cm of the alveolus and should not extend supragingivally. If the material is still present at a re-examination 2-3 weeks later it is removed at that time. The re-examination is important; at this time the extraction site should be carefully examined (with adequate sedation, a full mouth speculum, good light source and a

17 dental mirror or endoscope) for the presence of dental or bone fragments. These can be readily removed with periosteal elevators and alligator forceps. Systemic antibiotic therapy is reserved for those cases in which there is concurrent apical osteitis and/or sinusitis. Nonsteroidal anti-inflammatory drugs are administered for an additional 3-5 days. The patient will require reduction of the crown of the cheek tooth in the opposite arcade until the diastema at the extraction site closes, and one can also anticipate the development of “hooks” on the mesial aspect of the 2nd premolars and distal aspect of the 3rd molars of the opposite arcade as drift occurs.

V Equine odontoplastic tooth resorption and hypercementosis

Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is a relatively recently described clinical syndrome in the horse.5,16,17 This syndrome is characterized by both tooth resorption and hypercementosis, and affects the incisors and canine teeth, generally in older horses. Tooth resorption (TR) frequently affects all of the incisors, with progression from the 3rd to 1st incisors over time. Incisors with early radiographic evidence of TR may have no associated clinical signs. Incisors with more advanced TR may have concomitant alveolar bone lysis, and fistulation through the attached gingiva or near the mucogingival junction overlying the affected tooth root. Spontaneous incisor or canine tooth fracture is often the first clinical sign noted by the owners. In some horses hypercementosis, as well as TR, is a prominent feature. These horses often have significant bulging of the incisive bone or the rostral mandibles associated with this incisor tooth root hypercementosis. While more advanced TR leads to mobility and fracture, the teeth with significant hypercementosis are generally immobile and not affected by fistulation. In some horses, the main clinical feature of EORTH is vestibular extrusion of the affected incisors. The etiology of this syndrome has not yet been determined. Initial efforts to treat this syndrome consisted of the combined use of corticosteroids and antibiotics.12,13 These treatments were found to be palliative, short lasting, and failed to arrest the progression of TR. Presently, management consists of extraction of affected incisors and canine teeth that are considered to be a cause of oral pain. In horses with EOTRH the canine teeth were frequently affected, sometimes before the disease was clinically apparent in the incisors. Canine teeth are more likely to undergo TR with bone replacement. Spontaneous fracture of affected canine teeth with uncomplicated healing of the gingiva over the retained tooth root has been observed and is the rational for performing crown amputation (CRA) and intentional root retention in horses where this form of TR is radiographically documented. In the incisors affected by EOTRH area of greatest TR is often the middle 1/3 of the reserve crown/root. Although there may be a thickened PDL space in the radiographs, tooth mobility noted is often due to the loss of tooth structure in the middle 1/3 rather than attachment loss. These incisors, if not fractured on presentation, are likely to fracture during extraction, leaving a

18 tooth root that is difficult to elevate from the alveolus. Three methods have been used for the extraction of these retained incisor tooth roots. The first technique is the use of sharp luxators to cut the PDL in a circumferential and apical manner. This is followed by standard elevation. The second technique is alveoplasty of the buccal (vestibular) bone plate using bone chisels, rongeurs or carbide burs on a high speed handpiece with water irrigation. With removal of the buccal bone and PDL, the root is more readily elevated from the socket. A third technique is to screw a positive thread Steinman pin into the retained root, and use the pin as a “handle” for putting traction on the root fragment while elevating it from the socket. Regardless of the technique used, post-extraction radiographs are necessary to confirm complete extraction of all dental fragments and cementomas. The extraction socket should be curetted to insure removal of all necrotic bone and inflammatory tissue. Sharp bony edges of the extraction socket should also be rounded with rongeurs and a bone rasp or a coarse diamond bur on a high-speed handpiece with water irrigation. With extraction of canine teeth and/or 3rd incisors, closure with a mucoperiosteal flap is not difficult. The design of the flap is largely personal preference, but the goal to achieve absolute tension-free closure. The use of a releasing incision and/or severing the periosteum at the base of the flap is generally required. When the 1st and 2nd incisors are extracted advancement of a mucoperiosteal flap is more difficult and rapid wound contraction will often result in dehiscence. Partial closure with cruciate sutures may help stabilize the blood clot in the extraction site, but the sutures increase the adherence of feed material to the surgical site. At present, there is no evidence to support the use of materials to fill the extraction socket.. While difficult to assess, the morbidity associated with multiple incisor extractions in cases of EOTRH was mild to moderate and required no more than nonsteroidal anti-inflammatory drug (NSAID) therapy. Extraction sockets heal quickly by second intension and are usually fully covered by healthy gingiva within 3 weeks. In those horses in which all the incisors are severely affected by TR and there is osteitis of the alveolar bone, extraction of all the incisors in one procedure is indicated. These horses will eat normally with standard postoperative NSAID therapy. Extraction of incisors and canine teeth affected by EOTRH can be performed in the sedated standing horse with regional anesthesia. It is frequently necessary to infiltrate local anesthetic around individual incisors to completely desensitize the tooth. The reason for failure of the infraorbital, mental or mandibular nerve blocks in these patients is not clear. It is possible that there is alternate nerve supply (lingual or palatine nerves). In any case, if the patient appears to break through sedation when the affected tooth is manipulated, local infiltration of 2% lidocaine will be required. The results of treatment of EOTRH with extraction of all incisors and affected canine teeth has been quite favorable. The horses are capable of grazing and their performance under saddle or in harness is not affected. The only sequel that should be anticipated is intermittent protrusion of the tongue from the lips (about 1-2 cm).

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VI. Dental disease in the geriatric horse In the geriatric horse the teeth have worn through much or all of the reserve crown. The reserve crown has a smaller cross sectional (occlusal surface) area and proportionately less enamel in the geriatric horse. Additionally, the geriatric cheek teeth lose rostral angulation of the molars and caudal angulation of the premolars, such that there is less compressive force maintaining tight interproximal spaces. The net result is the formation of senile diastemata which predisposes to feed entrapment and periodontal disease. Feed packing within senile diastemata is a painful condition, and geriatric horses will frequently resent oral examination and occlusal adjustments. Regional nerve blocks are often needed to adequately address dental disease in the geriatric patient. In the maxillary cheek teeth the infundibula extend apically nearly the entire length of the reserve crown, almost to the level of the pulp chamber. Normal attrition in the geriatric horse may result in a “cupped” occlusal surface when the entire reserve crown is lost; at this point the tooth has a smooth occlusal surface consisting of cementum and dentine only. Further attrition frequently results in total loss of reserve crown, with separate roots visible on oral examination. In the absence of periodontal disease these senile teeth generally require only removal of small overgrowths that might be the cause of soft tissue trauma. Geriatric horses with overlong teeth should be treated with conservative crown reduction (odontoplasty), as it has been documented that the pulp horns tend to be closer to the occlusal surface in these individuals.18 On the other hand, periodontal disease that has resulted in deep pockets, fistulae or >50% attachment loss are treated by exodontia. Exodontia in geriatric horses is often easier due to the decreased periodontal attachment. However, presurgical radiography is still indicated. Marked loss of alveolar bone detail with mobile cheek teeth that appear to be “floating” in soft tissue is characteristic of soft tissue neoplasms such as squamous cell carcinoma. Long-standing periodontal disease of maxillary cheek teeth is often associated with oronasal or oroantral fistulae, and a mixed radiographic pattern of irregular soft tissue and gas within the sinuses is suggestive of feed packing within the sinus cavity. Treatment of oroantral fistulae in the geriatric horse is complicated by the chronicity of infection and the associated thickening of the sinus lining, as well as the inability to effectively obturate the extraction alveolus and generate closure of the fistula by second intention healing. Chronic periodontal disease may also stimulate marked cemental hyperplasia of the reserve crown-root, which may make oral extraction of molar teeth impossible. Equine odontoplastic tooth resorption and hypercementosis (EOTRH) is a condition seen mainly in the geriatric horse (see section III, above). It is invariably associated with oral pain and these individuals may be quite difficult to examine, even with profound sedation. Intraoral radiographs are required for a definitive diagnosis, but a presumptive diagnosis can be made clinically. The etiology of EOTRH has not yet been determined, and the recommended treatment is extraction of all affected teeth. While it is often difficult to convince the owner that this is the

20 best treatment option, these horses do very well post-operatively, with immediate resumption of eating (including grazing). The owners invariably note an improvement in the horse’s attitude. Other than intermittent protrusion of the tongue, there are no adverse sequelae to extraction of all incisors and canine teeth in one procedure.

VII. Dental disease in the Miniature Horse

The Miniature Horse has a significantly higher incidence of class 1 and class 3 malocclusions. Anomalies regularly found in this breed are supernumerary and rotated incisors and missing, rotated and malpositioned cheek teeth. Anomalous incisors rarely cause clinical disease, and extraction of these teeth is not necessary. The class 3 (mandibular ) malocclusion will have variably long mandibular incisors; these teeth can be conservatively managed with odontoplasty at regular intervals. Eruption of permanent premolars may be impeded by crowding, and radicular cysts are not uncommon. This may cause expansion of the maxillary bone over the nose, rostral to the facial crest and on the ventral mandible. The clinician should perform an oral examination and remove deciduous “caps” that have persisted beyond their expected time of exfoliation. In addition to craniofacial abnormalities, malformed or malpositioned maxillary cheek teeth may be responsible for nasal obstruction and/or nasal discharge in the Miniature Horse. While some of these conditions will resolve with continued cheek tooth eruption as the young horse ages, other will require exodontia. The clinician must recognize that exodontia of cheek teeth in the young Miniature Horse is much more difficult than in the horse or pony, and surgical techniques are often required. Occlusal adjustments can be challenging due to the small size of the Miniature Horse’s mouth and the poor ergonomics of working on such small patients. Downsized instruments are commercially available and in some cases these prove invaluable. The use of small stocks on elevated platforms also facilitates routine dental examination and treatment of the Miniature Horse.

1 Van den Enden MSD, Dixon PM. Prevalence of occlusal pulpar exposure in 110 equine cheek teeth with apical infections and idiopathic fractures. The Veterinary Journal 178 (2008) 364–371. 2 Casey MB, Tremaine WH. The prevalence of secondary dentinal lesions in cheek teeth from horses with clinical signs of compared to controls. Equine vet. J. (2010) 42 (1) 30-36. 3 Dacre I, et. al. Equine idiopathic cheek teeth fractures. Part 1: Pathological studies on 35 fractured cheek teeth. Equine Vet J 2007; 39: 310-318.

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4 Taylor L, Dixon PM . Equine idiopathic cheek teeth fractures. Part 2: a practice based survey of 147 affected horses in Britain and Ireland. Equine Vet J 2007; 39: 322-326. 5 Dixon PM, et.al. Equine idiopathic cheek teeth fractures, Part 3: a hospital based survey of 68 referred horses (1999-2005). Equine Vet J 2007; 39: 327-332. 6 Galloway SS, Easly J, Incorporating oral photography and endoscopy into equine dental examination. Vet Clin N Amer Equine Pract 2013, 29 (2), 345-366. 7 Baratt RM. Advances in Equine Dental Radiology. Vet Clin N Amer Equine Pract 2013, 29(2), 367-396. 8 Baratt RM. How to Obtain a Diagnostic Radiographic Study of the Equine Cheek Teeth. AAEP Proceedings 2014, 60; 480-485. 9 Staszyk C, Bienert A, et.al. Equine odontoclastic tooth resorption and hypercementosis. The Veterinary Journal 178 (2008) 372–379. 10 Townsend NB, Hawkes CS, et.al. Investigation of the sensitivity and specificity of radiological signs for diagnosis of periapical infection of equine cheek teeth. Equine vet J. (2011) 43(2), 170-178. 11 Knottebelt DC, Kelly DE. Oral and Dental Tumors, In Equine Dentistry, 3rd Ed., Easley J, Dixon PM, Schumacher J. eds. 2011. Elsevier, Edinburgh. 149-184. 12 Dacre IT, Kempson SA, Dixon PM. Pathological studies of cheek teeth apical infections in the horse 1: Normal endodontic anatomy and dentinal structure of equine cheek teeth. The Veterinary Journal 2008; 178: 311-320. 13 Dixon PM, deToit N. Dental anatomy. In Equine Dentistry, 3rd Ed., Easley J, Dixon PM, Schumacher J. eds. 2011. Elsevier, Edinburgh. 51-76. 14 Staszyk C, et.al, Simulation of local anaesthetic nerve block of the infraorbital nerve within the pterygopalatine fossa: Anatomical landmarks defined by computed tomography. Research in Veterinary Science 85 (2008) 399– 406. 15 Rawlinson JE. Addressing Pain: Regional Nerve Blocks. Focus on Dentistry Proceedings, 2011. 74-81. 16 Gregory R C, Fehr J, Bryant J. Chronic Incisor Periodontal Disease with Cemental Hyperplasia and Hypoplasia in Horses, http://www.ivis.org/proceedings/aaepfocus/2006/gregory1.pdf 17 Baratt RM. Equine Incisor Resorptive Lesions. Conference Proceedings, 21st Annual Dental Forum, Minneapolis, 2007; 123-130. 18 White C, Dixon PM. A study of the thickness of cheek teeth subocclusal secondary dentine in horses of different ages. Equine vet. J. (2010) 42 (2) 119-123.

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