The purpose of performance dentistry and equilibration is

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1 Performance Dentistry and Equilibration Maury B. Linkous, DVM Performance dentistry and equilibration is of the utmost importance for any horse which is ridden or driven. Properly done, with skill and judgment, it permits the horse to better respond to the rider or driver, minimizes fussiness on the bit, and through better mastication, improves nutrition. Every tooth must be addressed. Cheek teeth need to have sharp enamel points removed. Excessively long cheek teeth need to be reduced. Waves and ramps need to be corrected. Bit seats need to be established. Wolf teeth need to be extracted. Canine teeth need to be reduced in height and their margins rounded. Incisors need to be evaluated and corrected if necessary. Careful attention to these needs will help the horse to reach his full potential. Clin Tech Equine Pract 4: Elsevier Inc. All rights reserved. KEYWORDS bit seat, canine teeth, equilibration, incisors, molars, performance dentistry, premolars, wolf teeth Address reprint requests to Maury B. Linkous, DVM 9305 Roberts Road, Odessa, FL The purpose of performance dentistry and equilibration is to maintain the horse s mouth in a manner that better enables the individual to reach his potential. This encompasses providing a comfortable mouth on the bit or hackamore as well as insuring that the mouth closes adequately and evenly and has normal mandible-maxilla shift when the horse bends at the poll. This type of dentistry also enhances digestion leading to better nutrition, which again ultimately impacts performance. The difference between a winner and a loser in competition is often a very close margin a fraction of a second or a couple of points. Putting the right mouth on a horse helps your clients achieve that winning edge. These procedures require additional time, attention, and an investment in proper equipment. While most of these procedures can be performed with more simplistic tools than discussed in this paper, the same quality level is very difficult to achieve, the horse s mouth is often more sore (impacting the rider s ability to work the horse for several days), and additional risk is introduced into several of these procedures. In the end, one needs to assess the types of horses and clients that they have today and that they hope to retain and attract. Helping to set your client s horse s performance apart helps set you apart as their service provider. To successfully accomplish performance dentistry, one must address problems involving wolf teeth, premolars and molars, canine teeth, and incisors. It is important to understand the impact that these areas have on performance and how to address them in a manner that helps optimize the horse s performance, when (at what age) to address these needs, how to handle the procedure, equipment that is needed, and some exceptions one is likely to encounter (Fig. 1). Preparation Performance dentistry, like all other dentistry, requires proper preparation. Before sedation it is important to check general body condition, heart, and lungs to avoid unnecessary risks. Also, all food material should be flushed from the mouth as this interferes with visibility and with performing the dental procedure. An effective sedative combination for this type of dentistry in the average size horse ( lbs) is a combination of 1 cc detomidine hydrochloride (10 mg/cc; Dormosedan; Pfizer Animal Health, Exton, PA) mixed with 2 cc xylazine (100 mg/cc; AnaSed; Lloyd Laboratories Division, Lloyd Inc., Shenandoah, IA). Butorphanol (Torbugesic; Fort Dodge Animal Health, Overland Parks, KS) should be used only if the horse coming forward is desired (eg, one would not wish to use this sedative when using an overhead ring supported by a rope and pulley as it would be preferable in this case for the horse to back into a corner). Diazepam (5 mg/cc; Frank s Pharmacy, Ocala, FL), ¼ cc, is given to the horse that wants to chew continuously during dental procedures. After checking heart, lungs, and general body condition, the horse should be given one-third to one-half of the sedative mix, the mouth should be rinsed, and the procedure should commence. If additional sedation is needed once the above mix is exhausted, additional xylazine may be helpful. Wolf Teeth Wolf teeth create discomfort both from the bit moving against them and, if large enough, from the cheek being /05/$-see front matter 2005 Elsevier Inc. All rights reserved. doi: /j.ctep

2 Performance dentistry and equilibration 125 Figure 1 Consistently putting the right mouth on a horse requires an investment in time, attention, and equipment, but it can mean all the difference in the show ring, on the trails, or on the track. pulled into their sharp points. Their presence may also preclude establishing acorrect bit seat (Fig. 2). Normally wolf teeth erupt at 5 to 6 months. In young horses, they have a solid root and are not firmly anchored in the alveolus. Unless there is a problem, the veterinarian will usually wait to float teeth until the horse is 2, or just before training begins. However, it is a helpful practice to go through barns and pull the wolf teeth on yearlings. It is very uncommon to leave part of the root behind when extracting wolf teeth on a 1- or 2-year-old. It is probably just as uncommon not to have a portion of the root break in a horse over 4 or 5 years old. If the wolf tooth breaks during extraction and is well below the gum line, it should be left. If the broken root can be palpated, it is elevated and extracted. There is no single best tool or method for extracting wolf teeth. Their location and size vary greatly. One should start by sedating the horse; if appropriate, use Cetacaine (Cetylite Industries Inc.; Pennsauken, NJ) around the tooth and then inject 1 cc Carbocaine (Pharmacia and Upjohn; Kalamazoo, MI) around the tooth. Using a relatively short elevator which permits one to place his index finger on the tooth to be extracted as he elevates, a firm elevation should be made in front of and then behind the tooth. The elevator is then used Figure 2 Wolf teeth require extraction. Otherwise, their presence causes discomfort during work from the bit moving against them and, if large enough, from the cheek being pulled into their sharp points. Wolf teeth may also preclude establishing a correct bit set.

3 126 M.B. Linkous Figure 3 The primary instruments for extracting wolf teeth are elevators and forceps. Although these tools are not very complex in nature, it is critical to have the right sizes and angles available to reduce the risk of breaking a tooth. to move the gum away from the tooth on the medial and lateral sides. At this point, if the tooth is not too far from the second premolar, the east west elevators are used. If the tooth becomes loose but cannot be extracted with the east west elevators, dental forceps are used. In using dental forceps, it is important to select a size that fits the tooth. Forceps that are too large cannot grip the tooth, whereas forceps that are too small will often break a tooth. To minimize breaking roots, it is important for the tooth to be loose before extraction (Fig. 3). At times the wolf teeth are medial to the second premolar and the mouth must be propped open for a diagonal approach to the elevation and extraction. Occasionally, the wolf tooth will not grow down through the gum but will grow forward under the gum line, which is referred to as a blind wolf tooth. In this case, one should place Cetacaine (Cetylite Industries, Inc., Pennsauken, NJ) on the tissue over the tooth, inject 1 cc of Carbocaine (Pharmacia and Upjohn) over the tooth to be extracted, grasp the tissue over the point of the tooth with rat tooth forceps, and remove a section of gum over the tooth using curved scissors. Then the elevator should be used to loosen the skin around the tooth and elevate under the tooth. When loose, these teeth are extracted with forceps by a forward pull. Wolf teeth, particularly on draft breeds and their crosses, may be so large that normal elevation is virtually impossible. In these cases, a carefully directed elevator and a sharp blow from a rubber mallet are useful. These teeth are not limited to the upper jaw and will occasionally be found in the lower jaw. When found, the same methods of extraction are used as those for the upper jaw. Premolars and Molars Premolars and molars should be maintained on a regular basis. If they are not well maintained, they may cause a variety of issues in the performance horse, including difficulty in bending at the poll, poor nutrition, and difficulty on the bit (Fig. 4). Premolars and molars should be dressed so that they are free of sharp points on the lingual and buccal sides. Because the upper jaw of the horse is wider than the lower, the enamel points are most prominent on the lateral side of the upper arcade and on the medial side of the lower arcade. On the buccal side of the upper arcade and the lingual side of the lower arcade, the enamel points should be removed and the edges rounded. Teeth which extend above the arcade should be reduced in length. The reduction of a long tooth may be done with a molar cutter; however, this presents the risk of splitting the tooth even if the molar cutter fits properly. Molar cutters only work for teeth that are well above the rest of the arcade. They are of no benefit in correcting the waves and ramps that one finds in most horses. If one decides to use a molar cutter, there are several points to remember to help reduce these risks: Molar cutters that are too small for the tooth in question and contact the tooth in a scissor-like fashion should never be used. The jaws of the molar cutter should close evenly on the medial and lateral segments of the tooth and produce equal side-to-side pressure. Applying even pressure to both sides of the tooth lessens the chance of a longitudinal break. A common mistake in using molar cutters to remove a caudal hook from the ventral third molars is to elevate the handles of the molar cutters to gain a better grip on the tooth. This action often results in removing a large section of tooth and opening the pulp cavity. A safer, more controlled method for removing hooks, correcting ramps, and other abnormalities is to use an extended guarded bit with a Dremel (Dremel, Racine, WI) as a power source, a power float, or a variation of the power float. Short stroke Makitas (Carbide Products,

4 Performance dentistry and equilibration 127 Figure 4 Problems involving premolars and molars have a far-reaching impact on performance. If appropriate, the cheek teeth should be reduced to a normal height while maintaining the normal side-to-side slant. Torrence, CA) with straight and angled attachments are also beneficial. In conjunction with proper sedation, a full mouth speculum, and an adequate light source, these tools offer many advantages. If the height of the tooth prohibits placing a grinding tool on its top, one should consider removing the guard on the extended grinding tool and approaching it from its anterior surface 1 (Fig. 5). After completion of work on premolars and molars, the work should be carefully evaluated visually and by palpation, asking: Are the table angles correct on any reduced teeth? Are any sharp points present? Particular attention should be paid to the third molars, both upper and lower. Palpation is most easily done with a wet gloved hand in a wet mouth with a full speculum. Premolars and molars have normal transverse ridges on their table surfaces that interdigitate. These ridges, along with the uneven table surfaces, allow the horse to chew roughage efficiently. Occasionally, these ridges become excessive and are thought to hamper the slight rostral caudal movement of the mandible involved in chewing (which is primarily a lateral excursion) and in riding when the horse is asked to flex at the poll. Correction of this problem involves reducing the Figure 5 Power tools allow you to provide optimal quality, reduce risks, and minimize soreness. Because premolars and molars have a significant impact on the horse s performance and they require routine maintenance, an investment of power equipment should be considered.

5 128 M.B. Linkous Figure 6 Poor head carriage or fussiness on the bit may indicate the need for a proper bit seat, which will help prevent discomfort when the bit pulls the cheek against the premolars. ridge to a normal height while maintaining the normal sideto-side slant and not diminishing the effective grinding surface of the cheek teeth. There are a few points that should be made in association with dental reductions: No rough edges should be left and the reduced tooth or teeth should match the angle of the table surface of the rest of the arcade. Normally table surfaces are not dressed. The table surface of a tooth should only be dressed to reduce its height. Once a horse reaches 18 to 20 years of age, there will be little, if any, more tooth extruded. Therefore, it is important to make minimal arcade adjustments on older horses. Only a small portion of the offending segment of a long tooth should be removed to make the horse comfortable. Whatever gaps are produced in correction will probably remain for the duration of the horse s life. The back lower molars should be carefully evaluated, particularly in short-headed, dish-faced individuals such as Arabians. These horses often have a curved lower arcade that can easily give a false impression of having a lower caudal hook. Aging individuals also develop a normal curvature of the back lower molars called the angle of Spee. By either direct visualization, palpation, or both, one should determine whether the distance from the gum line to the crown is the same along the line of the ventral molars. If there is no change in distance, there is no caudal hook. Arcades that require dramatic correction to produce perfect alignment should be approached with patience and client education. It is a bad idea to attempt to correct a mouth wrecked by years of poor care in one session. Teeth that have become dominant should be reduced so that the opposing tooth may enter the arcade. If the opposing tooth is absent or compromised, the dominant tooth should be reduced so that it does not create a painful problem by impinging on tissue or a compromised tooth. In correcting arcade problems, small corrections made at 6-month intervals work well. In 1.5 to 2 years, a mouth with bad waves or ramps can usually be completely corrected, unless the horse is aged. Particular attention should be paid to the sharp points along the lingual surface of the lower arcade toward the back of the mouth. It has been suggested that, during work on the bit, the tongue flattens against these teeth and, if not properly dressed, discomfort results. 2,3 Bit Seats Producing bit seats is the practice of rounding the rostral corners of the upper and lower second premolars (106, 206, 306, 406) and should always be done in performance dentistry. The purpose of the bit seat is to increase the horse s comfort level, particularly when the bit pulls the cheek against the premolars. Horses demonstrating poor head carriage and fussiness on the bit may show immediate improvement after aproper bit seat is provided (Fig. 6). Producing a bit seat may be done with hand floats or power floats; asaddle-type bit and adremel are ideal (Fig. 7). Occasionally, there will be a horse which, because of an unusually long distance between the commissures of the lips and the second premolar, does not allow the operator to hold this saddle-type Dremel perpendicular to the tooth. A rounded burr, allowing the operator to grind the tooth from the front, works well for these individuals. A minimal amount of tooth should be taken from the rostral corners of each second premolar. These teeth should be carefully rounded and smoothed. This rounding and smoothing should extend from the gum line and include lateral and medial edges of these teeth. If deemed absolutely necessary, more tooth can be removed later, bearing in mind that excessive bit seats may create more problems than they

6 Performance dentistry and equilibration 129 Figure 7 The Dremel power tool with a saddle bit or rounded burr can be very effective in creating the bit seat. The saddle bit makes rounding of the tooth easiest. However, the saddle bit can only be used effectively if the handle can be held nearly perpendicular to the tooth. solve. Excessive bit seats may result in the bit or bit with cheek tissue being pulled into an unnecessarily large defect, thereby creating discomfort. Not only does it create discomfort, it increases the risk of opening the pulp cavity. Also, uneven bit seats, top and bottom, may result in a ramp or a rostral hook (Fig. 8). Canine Teeth Canine teeth usually erupt between 4 and 5 years of age. They are generally absent or are rudimentary in the mare. These teeth should be reduced by approximately half of their length and should have the edges rounded. A hand grinder and bit work well for reducing canines. Properly reduced canines help minimize damage to the tongue during work; long canine teeth often result in tongue lacerations when the tongue gets caught between the bit and the horse s teeth (Fig. 9). The practice of reducing canine teeth to the gum line should be discouraged. This radical reduction exposes the pulp cavity and leads to decay and loss of the tooth. Also, if the canine tooth is reduced to the gum line, the horse is more likely to allow his tongue to protrude from the mouth when worked on the bit; Figure 8 It is important that big seats are done properly and evenly on upper and bottom teeth. Excessive bit seats may cause more problems than they solve.

7 130 M.B. Linkous Figure 9 Long canine teeth often result in tongue lacerations when the tongue is caught between the bit and teeth. Corrected canine teeth not only reduce tongue lacerations, but they also make bridling and unbridling the horse easier and safer. this is especially apparent in disciplines that require the horse to workonthebitextensively,suchasdressage(fig.10). If the canine tooth has not erupted and tissue over the tooth is sore, this tissue may be blocked and removed in the same manner as one would remove the tissue over a blind wolf tooth. This procedure hastens the eruption of the canine tooth. Incisors Horses having excessively long incisors that hold the back teeth well apart do not have optimal response to the bit or the best chewing ability even if their teeth are properly floated. Management that allows the horse to spend most of its life on good pasture provides for a healthier mouth. Silicates in the grass cause normal dental wear, incisors are worn down, and cheek teeth alignment tends to be maintained. Neither hay nor grain contains silicates. Therefore, horses with limited or no pasture have a high incidence of incisor problems. These problems range from excessive length to malformations. Horses with excessively long incisors commonly drop feed, make very little grinding noise when eating hay or grain, often handle poorly, and usually show atrophy of the masseter muscles. They also often have cheek tooth malocclusions. On the other hand, it has been the author s observation that horses that crib badly (resulting in essentially no upper inci- Figure 10 The primary instrument for reducing and rounding canines is a hand grinder and bit. The front and back of the bit are rounded to work on the entire perimeter of the canine.

8 Performance dentistry and equilibration 131 Figure 11 It is only possible to properly evaluate incisors after all premolar and molar corrections have been addressed. sors, full cheek teeth contact, and immediate separation of the incisors on lateral excursion), rarely have malocclusion problems involving cheek teeth. Excessively long incisors create two primary areas of contact for the upper and lower jaw: the temporomandibular joint and the incisors. The cheek teeth, when centered, normally have no contact; however, a brief lateral excursion of about 5 mm (approximately half of tooth) will generally create contact of the cheek teeth and cause the incisors to separate. This happens if the cheek teeth have a normal occlusion angle of When evaluating incisor problems by lateral excursion, it is important to observe that the incisor separation is being caused by cheek tooth contact and not from incisor irregularities (Fig. 11). Incisor reductions are done with a Dremel and grinding burr, a diamond cut-off wheel, hand files, or any combination of these instruments. Care should be given not to overheat the tooth. A useful speculum for incisor work can be made from an adjustable bungee cord and 1.25 thick-walled PVC. 4 (Fig. 12). Here are some common incisor problems and methods of correcting them: Figure 12 Although the tools necessary to do good incisor work are minimal, care must be taken to use the equipment safely.

9 132 M.B. Linkous Figure 13 Excessively long incisors demand an excessive lateral excursion before the back teeth meet. 1. Incisors excessively long. Corrected by changing length and occlusal angle of incisors. By correcting the bite angle, incisor length is greatly reduced (Fig. 13). 2. Angled occlusive surface (slant, tilted, or diagonal). Corrected by removing bulk of tooth from the longest incisors (Fig 14). 3. Smile (ventral curvature). Corrected by removing bulk of tooth from lower corners and upper centers (Fig. 15). 4. Frown (dorsal curvature). Corrected by removing bulk of tooth from the upper corners and the lower centers (Fig. 15). 5. Irregular or stepped incisors preventing normal lateral excursion of the cheek teeth during mastication. Corrected by removing bulk of tooth from the highest points of incisors. May require several sessions (Fig. 16). If a horse has a severely back-to-front sloped incisor occlusive surface so that the fronts of the upper incisors are much taller than the backs, care should be taken not to fracture the edges of the incisors. One should use a padded speculum or reduce these points before putting a speculum on the horse. To avoid damage to the speculum, the upper pad must be able to slide. If both the top and bottom dental plates contain fixed pads, the horse has the ability to grip the speculum. A lateral excursion by the horse with pressure on the speculum will quickly reveal that dental speculums do not tolerate this force well. Pads may be readily made for the Conrad or Meister speculum by placing Scotch tape across the back of the lower dental plate, leveling it, and putting approximately ¼ inch of Shoe Goo in the well. (Shoe Goo is available at most athletic shoe stores.) The top pad can be made by turning the speculum over, leveling the plate, covering with Saran Wrap, applying Scotch tape across the back, and adding ¼-inch depth of Shoe Goo. The anterior portion of the plate is made by tipping the speculum after the first section is dry and, in sequence, applying Shoe Goo to the front, and then each side of the plate. Many times incisor problems are so severe that complete correction requires several sessions, usually at 6-month intervals. In older horses with minimal tooth left to be ex- Figure 14 May be caused by or create tooth abnormalities. May also be caused by too much pressure on the incisors.

10 Performance dentistry and equilibration 133 Figure 15 Both the smile and the frown prohibit proper lateral excursion-generating molar and premolar issues. truded, some incisor problems can never be corrected. It is important not to remove so much of an incisor that a gap is created, thereby causing excessive force on the cheek teeth. After completion of incisor corrections, a lateral excursion of about 5 mm in either direction should produce separation of the incisors as long as there is normal side-to-side angulation of the cheek teeth. Care must be taken that there are no high areas on the occlusive surfaces of the cheek teeth through careful evaluation with a good light and a speculum that will hold the cheeks away from the teeth. Even with the most conservative approaches to incisor corrections, stress patterns are changed. The temporomandibular joint must adjust, pressure on cheek teeth change, and the masseter muscles must now work harder. Consequently, any horse that receives incisor work that brings the cheek teeth closer together receives IV Butazolidin (Aspen Veterinary Resources, Ltd.; Kansas City, MO) with a recommendation to continue on an oral form for the next 4 days. Post Procedure At the end of the procedure, it is helpful to administer 2 to 5 cc Yohimbine (Frank s Pharmacy; Ocala, FL), depending on the size of the patient and on the degree of sedation at the time. If the sedated horse lowers his head shortly after the injection, he may develop an unattractive knot at the injection site. This is caused by increased pressure within the jugular vein, creating leakage under the skin at the injection point. This is commonly referred to as a bleed back. Although this subcutaneous bleeding will be absorbed in a few days, it may easily be avoided by attending the horse in the dental ring or other head support until he is relatively alert and will maintain his head in a horizontal position. Summary In conclusion, if one has removed the horse s wolf teeth, dressed the molars and premolars, reduced excessively long cheek teeth, Figure 16 Irregular or stepped incisors prevent normal lateral excursion of the cheek during mastication.

11 134 M.B. Linkous eliminated excessive transverse ridges, created a comfortable bit seat, reduced the canines, and corrected any incisor problems, the horse will be better able to handle the bit without resentment or pain. He will be able to grind his food and receive maximum nutrients from his ration. If performance dentistry and equilibration are done with skill and good judgment, the horse benefits in both performance and nutrition. References 1. Rucker BA: Ocala Equine Dentistry Workshop. November 6, Stubbs RC: personal communication, AAEP Convention Scrutchfield WL: Dental prophylaxis, in Baker GJ, Easley J (eds): Equine Dentistry. Philadelphia, PA: W.B. Saunders, 1999, pp Lokai, MD: Ocala Equine Dentistry Workshop. November 6, 1998