- Email: [email protected]
Equine Dental Advances
320
GREENE
denoted 1, 2, and 3; canines, 4; wolf teeth, 5; premolars, 6, 7, and 8; and molars, 9, 10, and 11. Each tooth, whether present or not, is numbered. This number is incorporated into the appropriate quadrant number. Changing the quadrants from 100 through 400 to 500 through 800 identifies the deciduous teeth. For example, 111 is the right, maxillary, third molar, and 707 is the left, mandibular, deciduous, third premolar. Recent studies have shown that aging mature horses by their dentition is an inexact s ~ i e n c e .AS ~ ~a result, , ~ ~ ~practitioners realize that the classic guidelines for aging horses are inaccurate in many individuals and that they should be cautious when aging a horse as part of a prepurchase examination. Well-designed motorized instruments, improved hand instruments, an increased opportunity for continuing education, and the incorporation of prophylactic and restorative procedures into equine practice have made providing quality dental care professionally rewarding. MOTORIZED INSTRUMENTS
The routine use of motorized instruments is the most significant advance in equine dentistry. Historically, mechanical hand-cranked floats were patented in the 1800s. Dr. Erwin Becker, a German equine practitioner and professor, designed a system of irrigated, flexible-shaft, rotary, motorized instruments in the 1930s. The introduction of newly designed motorized instruments allows difficult procedures to be performed more easily regardless of the strength or endurance of the clinician. Many practitioners now provide complete dental care for their patients. They understand that correcting malocclusions is an integral part of proper preventative care. Lists of equine dental instrument suppliers are available.13,52 Veterinarians should consult manufacturers and experienced colleagues before choosing the instruments appropriate for their practice. All are modified power tools, but the use of this term may be intimidating to some horse owners. As a result, the author prefers to use the term motorized instruments. The introduction of motorized instruments has resulted in the need to perform "visual dentistry." Mouth gags and speculums have been used for hundreds of years.35,55 A full-mouth speculum is critical to assess the rate of reduction, safely palpate the rear molars, and prevent the creation of iatrogenic malocclusions. Regardless of the instruments used, variable-speed control is necessary to prevent excessive crown reduction and minimize soft tissue trauma.27When using hand floats, many procedures are performed without a speculum and thus without visual assessment of the float blade engaging the tooth. Motorized instruments rapidly reduce the crown, and observation of the tooth during reduction is important to prevent unnecessary crown shortening. Motorized dentistry is not likely to antiquate hand instruments. The latter are always of value when performing many finishing and other
EQUINE DENTAL ADVANCES
327
Figure 1. A, Trauma to 401-403 resulting in excessive crown of 101-103. B, Incisors should be level following reduction.
It is generally accepted that significant malocclusions should be corrected. The current debate regarding incisors centers on the reduction of crown length in horses with normal incisor alignment and the proper relation between incisor length and cheek teeth occlusion. The author believes that if horses do not use their incisors as designed (i.e., shearing off coarse range grasses for 16-18 h/d), excessive incisor length may result. This increases the interocclusal space between the opposing cheek teeth arcades. That widened interocclusal space results in the cheek teeth being in contact for less time during the masticatory cycle.28The author further believes that this may result in incomplete assimilation of the dietary nutrients and larger stem segments in the manure. The premolar/molar interocclusal space as well as the cheek teeth occlusal surface angle has a direct effect on evaluating lateral excursion. Lateral excursion is evaluated when the mandible is moved laterally while the incisors are in contact (Fig. 2). The incisors come out of contact when the cheek teeth come into occlusion. The rate of incisor separation with continued excursion is a reflection of the occlusal surface angle of the cheek teeth arcades. It is important to remember that the evaluation of lateral excursion is in the opposite direction of how a horse normally chews. Excessive incisor length results in a larger premolar/molar interocclusal
330
GREENE
Figure 3. Grade 3 equine caries. (Courtesy of Tony Basile, St. Helens, OR.)
tants and practitioners realize their advantage compared with supporting a horse's head on one's shoulder. New Procedures
The use of radiography in equine dentistry has been well de~ c r i b e d .In~ the ~ , future, ~ ~ ~ systems for performing intraoral radiographs should become vossible. This should eliminate the effect of summation and permit isol&ion of specific teeth and the periodontium. After the extraction of a cheek tooth in horses, there is the potential for the tooth on either side of the extraction site to move into the svace created by the extraction. This movement results in an increase in the interdental spaces on the opposite side of these adjacent teeth. This places such patients at risk for developing periodontal disease and subsequent tooth loss. Bridges, acrylic spacers, and other materials have been used with mixed results in an attempt to preserve this space (Peter Emily, DDS, personal communication, 1996). Horses that are prone to the collapse of this space should be identified, and appropriate spacers should be placed to prevent this condition. Horses are hypsodonts and are unique in that the reattachment of the periodontal ligament to the tooth is a normal process during eruption (C.E. Harvey, DVM, personal communication, 1999).l Practitioners have the opportunity to treat and perhaps prevent periodontal disease. New products, instruments, and perioceutics are available for the prevention and treatment of eauine ~eriodontitis. Published rep;rts hive described equine endodontic procedures, periodontal disease, orthodontics, and surgical technique^.^, 4, 6, lo, 17,20, 21, 25, 33, 37, 54 Clinical research is currently being done in the areas of I
GREENE
denoted 1, 2, and 3; canines, 4; wolf teeth, 5; premolars, 6, 7, and 8; and molars, 9, 10, and 11. Each tooth, whether present or not, is numbered. This number is incorporated into the appropriate quadrant number. Changing the quadrants from 100 through 400 to 500 through 800 identifies the deciduous teeth. For example, 111 is the right, maxillary, third molar, and 707 is the left, mandibular, deciduous, third premolar. Recent studies have shown that aging mature horses by their dentition is an inexact s ~ i e n c e .AS ~ ~a result, , ~ ~ ~practitioners realize that the classic guidelines for aging horses are inaccurate in many individuals and that they should be cautious when aging a horse as part of a prepurchase examination. Well-designed motorized instruments, improved hand instruments, an increased opportunity for continuing education, and the incorporation of prophylactic and restorative procedures into equine practice have made providing quality dental care professionally rewarding. MOTORIZED INSTRUMENTS
The routine use of motorized instruments is the most significant advance in equine dentistry. Historically, mechanical hand-cranked floats were patented in the 1800s. Dr. Erwin Becker, a German equine practitioner and professor, designed a system of irrigated, flexible-shaft, rotary, motorized instruments in the 1930s. The introduction of newly designed motorized instruments allows difficult procedures to be performed more easily regardless of the strength or endurance of the clinician. Many practitioners now provide complete dental care for their patients. They understand that correcting malocclusions is an integral part of proper preventative care. Lists of equine dental instrument suppliers are available.13,52 Veterinarians should consult manufacturers and experienced colleagues before choosing the instruments appropriate for their practice. All are modified power tools, but the use of this term may be intimidating to some horse owners. As a result, the author prefers to use the term motorized instruments. The introduction of motorized instruments has resulted in the need to perform "visual dentistry." Mouth gags and speculums have been used for hundreds of years.35,55 A full-mouth speculum is critical to assess the rate of reduction, safely palpate the rear molars, and prevent the creation of iatrogenic malocclusions. Regardless of the instruments used, variable-speed control is necessary to prevent excessive crown reduction and minimize soft tissue trauma.27When using hand floats, many procedures are performed without a speculum and thus without visual assessment of the float blade engaging the tooth. Motorized instruments rapidly reduce the crown, and observation of the tooth during reduction is important to prevent unnecessary crown shortening. Motorized dentistry is not likely to antiquate hand instruments. The latter are always of value when performing many finishing and other
EQUINE DENTAL ADVANCES
327
Figure 1. A, Trauma to 401-403 resulting in excessive crown of 101-103. B, Incisors should be level following reduction.
It is generally accepted that significant malocclusions should be corrected. The current debate regarding incisors centers on the reduction of crown length in horses with normal incisor alignment and the proper relation between incisor length and cheek teeth occlusion. The author believes that if horses do not use their incisors as designed (i.e., shearing off coarse range grasses for 16-18 h/d), excessive incisor length may result. This increases the interocclusal space between the opposing cheek teeth arcades. That widened interocclusal space results in the cheek teeth being in contact for less time during the masticatory cycle.28The author further believes that this may result in incomplete assimilation of the dietary nutrients and larger stem segments in the manure. The premolar/molar interocclusal space as well as the cheek teeth occlusal surface angle has a direct effect on evaluating lateral excursion. Lateral excursion is evaluated when the mandible is moved laterally while the incisors are in contact (Fig. 2). The incisors come out of contact when the cheek teeth come into occlusion. The rate of incisor separation with continued excursion is a reflection of the occlusal surface angle of the cheek teeth arcades. It is important to remember that the evaluation of lateral excursion is in the opposite direction of how a horse normally chews. Excessive incisor length results in a larger premolar/molar interocclusal
330
GREENE
Figure 3. Grade 3 equine caries. (Courtesy of Tony Basile, St. Helens, OR.)
tants and practitioners realize their advantage compared with supporting a horse's head on one's shoulder. New Procedures
The use of radiography in equine dentistry has been well de~ c r i b e d .In~ the ~ , future, ~ ~ ~ systems for performing intraoral radiographs should become vossible. This should eliminate the effect of summation and permit isol&ion of specific teeth and the periodontium. After the extraction of a cheek tooth in horses, there is the potential for the tooth on either side of the extraction site to move into the svace created by the extraction. This movement results in an increase in the interdental spaces on the opposite side of these adjacent teeth. This places such patients at risk for developing periodontal disease and subsequent tooth loss. Bridges, acrylic spacers, and other materials have been used with mixed results in an attempt to preserve this space (Peter Emily, DDS, personal communication, 1996). Horses that are prone to the collapse of this space should be identified, and appropriate spacers should be placed to prevent this condition. Horses are hypsodonts and are unique in that the reattachment of the periodontal ligament to the tooth is a normal process during eruption (C.E. Harvey, DVM, personal communication, 1999).l Practitioners have the opportunity to treat and perhaps prevent periodontal disease. New products, instruments, and perioceutics are available for the prevention and treatment of eauine ~eriodontitis. Published rep;rts hive described equine endodontic procedures, periodontal disease, orthodontics, and surgical technique^.^, 4, 6, lo, 17,20, 21, 25, 33, 37, 54 Clinical research is currently being done in the areas of I