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How to Assess the Equine Periodontium

How to Assess the Equine Periodontium

RESPIRATORY/

How to Assess the Equine

Jon M. Gieche, DVM

The periodontium is the attachment apparatus of the . Evaluation of the periodontium requires specific knowledge of anatomy, processes of examination, instrumentation used, classification criteria and grading systems for findings to arrive at a correct diagnosis and to develop an appropriate treatment plan. Author’s address: Kettle Moraine Equine Hospital, Regional Equine Dental Center, N8818 Highway 67, Whitewater, Wisconsin 53190; e-mail: [email protected]. © 2010 AAEP.

1. Introduction oping treatment plans for practically all dental The standard of care in equine dentistry continues pathology encountered. to rise as scientific information becomes available 2. Anatomy and practitioners improve their knowledge base. The periodontium is the attachment apparatus of A thorough understanding of the basics of all sub- the tooth. It is defined as those tissues supporting disciplines of dentistry is important to appropriately and investing the tooth, and it consists of , diagnose and treat dental pathology. The seven periodontal , lining of the alveolus, primary subdisciplines, oral equilibration, periodon- and gingiva facing the tooth.7 The tooth is held in tics, orthodontics, endodontics, restorative den- the incisive, maxillary, or mandibular bone by the tistry, exodontics, and oral surgery, each require combined efforts of these structures in a fibrous specific knowledge of anatomy, processes of exami- called a gomphosis,7 a joint in which a conical object nation, instrumentation used, classification criteria, is inserted into a socket and held.8 and grading systems for findings to arrive at a cor- Cementum is a creamy tan to yellowish bone-like rect diagnosis and develop an appropriate treatment mineralized component of the tooth (Fig. 1). It at- plan. The incidence of in taches to either dentin or enamel on one side and the 1 horses has been documented for over 100 yr. In periodontal ligament on the other side (in the nor- the past, the standard of care has been based pri- mal horse). The periodontal ligament (PL) is a 2–4 marily on gross intraoral examination findings. markedly complex structure consisting of collagen Recent introduction of high-quality radiographic fibrils and fiber bundles with a network of blood techniques,5 intraoral cameras, and better instru- vessels and nerves coursing throughout it.9–11 The mentation has enabled our profession to develop a PL attaches to the cementum of the tooth and the standard similar to that alveolar bone through Sharpey’s fibers and to the used in human and small-animal dentistry.6 The gingiva through the gingival ligament.11,12 periodontium has a complex anatomy that requires The alveolar is the bone of the , consideration during examination and either di- , and that contains the alveoli rectly or indirectly must be considered when devel- (sockets). The outer layer (vestibular, lingual, or

NOTES

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Fig. 1. Yellow arrow, cementum on ; red arrow, widened interproximal space between 201 and 202; green arrow, ( index stage 1 [GI1]). Fig. 2. Radiographic anatomy. White arrow, pointing out the black line representing the periodontal ligament space; yellow arrow, pointing out the white line representing the lamina dura; labial) is the cortical plate. The dense inner layer, black arrow, interproximal bone; green arrow, crestal bone. the cribriform plate, can be seen radiographically as the lamina dura (Fig. 2). Cortical plate bone meets the inner alveolar bone at the alveolar crest. These can be differentiated radiographically in the normal cular depth is up to 3 mm for incisors, canines, and patient. The alveolar bone at the coronal extent of second and up to 5 mm for the remaining the alveolus is referred to as crestal bone. Bone teeth (Fig. 5).15 between two teeth is interproximal bone (mesial or distal to two adjacent teeth in a battery/arcade) (Fig. 3. Materials and Methods 3). Bone at the root tips is apical. The remaining alveolar bone is referred to as either labial, lingual, When to Schedule the Periodontal Examination vestibular, or palatal, depending on the alveolar In patients being evaluated for dental health for any wall involved. reason, a periodontal examination should be a stan- The gingiva surrounding and facing the tooth is dard component of the complete oral examination. also a component of the periodontium (Fig. 4). The Periodontal disease may be a manifestation of a coronal extent of the free/marginal gingiva is the variety of infectious and metabolic disorders, and it gingival crest.13 The epithelium facing the tooth on is not limited to dental pathology. A thorough this free gingiva is the gingival . physical examination will help rule out concomitant It attaches to the tooth as the systemic causes of periodontal disease. coronal to the crestal bone in the fully erupted tooth.14 In the normal equine, the gingiva attaches Instrumentation to tooth cementum on one side and alveolar crestal Specific instrumentation is necessary to properly bone or periosteum on the other side. Normal sul- evaluate for and grade the extent of periodontal

Fig. 3. Directional terminology. Black bracket, mesial (to midline) side of 201; red bracket, distal (away from midline) side of 201; yellow bracket, labial surface of 103; green arrow, apical (to the root tip) extent of clinical of 201; black arrow, coronal (to the crown) extent of clinical crown of 201; black lines, proximal (contacting/facing each other) surfaces of incisors. The interproximal space/surface is the space/surface between two teeth.

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Fig. 4. Gingival/mucosal anatomy. Red arrows, gingival crest of the free/marginal gingival; red bracket, marginal/free gingival; blue bracket, attached gingival; yellow bracket, mucosa; line where blue and yellow brackets meet, gingival mucosal junction. Note that the area forming a sulcus between the free gingiva and the tooth is the , and the lining of this sulcus on the gingival side is the gingival sulcular epithelium.

disease. A bright head light, full-mouth speculum be addressed before proceeding to the periodontal with bite/gum plates, buccal/lingual retractors, den- examination. tal explorers, periodontal probes, dental picks, long- The patient is sedated so that a full-mouth specu- handled alligator forceps, long-handled dental lum may be placed, chewing and motion is curettes, dental mirrors, molar forceps, and air-wa- eliminated, and the oral cavity may be instru- ter irrigation are required (Fig. 6). Intra- and ex- mented. Periodontal disease is painful. In some traoral radiographic equipment are also necessary specific cases, patient anxiety levels may escalate to fully evaluate and stage periodontal disease (Fig. dramatically on instrumentation of the oral cavity. 7). Digital and intraoral cameras are helpful for Animals may exhibit head tossing or excessive chew- recording intraoral findings during the initial exam- ing and tongue motion, resulting in an inadequate ination and documenting the treatment and results over time.16 Clinicians should be familiar with standing sedation/anesthetic techniques.17–21

Execution of the Periodontal Examination Significant time and effort must be devoted to the execution of the examination, because it is the basis of all further decisions regarding patient care. History, signalment, and physical examination find- ings are compiled. All patients are evaluated for risk factors that may preclude safe examination. Oral disorders may include diseased, absent, or struc- turally compromised tissues: equine odontoclastic and (EOTRH),22 missing incisors, temporal mandibular joint disease, and/or trauma. These may cause pain or further injury with full-mouth speculum placement. Limb arthritis, hyperkalemic periodic paralysis (HYPP), cer- vical vertebral instability, equine protozoal myeloen- cephalitis (EPM), etc. may increase risks to the patient, handler, and clinician. Proper restraint is an important consideration during sedation. A fixed or portable stocks with a boom for suspending the dental halter significantly aids restraint (Fig. 8). Head Fig. 5. entering the gingival sulcus on the stands may be used as an alternative to booms and labial side of 104. Note the bleeding from the gingival sulcus dental halters. Conditions that increase risks should and gingival crest of 404 post-prophylactic therapy (black arrow).

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Fig. 6. (A) Periodontal probe in the periodontal pocket with bleeding gingiva at the palatal aspect of the interproximal space between 107 and 108. (B) Full-mouth speculum with bite and gum plates. (C) Intraoral mirror. (D) Dental Explorer. periodontal examination. These horses are gener- tis, gingival recession, periodontal pockets, trauma, ally guarding against real or anticipated pain from widened interproximal spaces, etc.) (Fig. 10) are instrumentation. Deeper sedation and local infil- noted, measured, and recorded on the dental chart. tration or regional anesthesia19,20,23,24 maybenec- The gingival sulcus is checked for depth with a essary under these circumstances. Staging of the periodontal probe and examined for the tendency to examination and treatment may be necessary to bleed. If present, food material must be removed ensure clinician, handler, and patient safety. from periodontal pockets with dental picks, irriga- Decomposition of static food impactions in peri- tion, and/or long-handled alligator forceps before odontal pockets, widened interproximal spaces, buc- pockets can be evaluated for pocket type (suprabony cal vestibules, and lingual sulci leads to food and or infrabony)25 and pocket depth. Periodontal tissue degradation, often resulting in a fetid odor pockets are measured for depth, mesial to distal (Fig. 9). length, and width. Supra and subgingival surfaces The longer the food material is lodged/static in of the teeth are evaluated for cemental abnormali- these areas, the greater the risk of advancing peri- ties using dental explorers and mirrors: evidence odontal disease. The presence of fetid odor should of decay, , fractures, and hypo or hyperpla- be noted before flushing with an antibacterial sia may be seen (Fig. 11). ( gluconate, 0.12–0.20%, /compressibility is assessed and or dilute povidone iodine flush solution) to remove graded using molar forceps and digital manipula- food matter and debris. A bright head light, retrac- tion, being careful not to damage the periodontium tors (buccal/lingual), intraoral cameras,16 and a mir- or the tooth on manipulation. Physiologic move- ror aid complete/accurate visualization of the ment is considered normal and is limited to the width exposed oral aspect of the periodontium. All as- of the periodontal ligament and the elasticity of the pects of the , canine, , and molars alveolar support.26 Pathologic movement is a dis- are examined. Any abnormalities (such as gingivi- placement of a tooth, either horizontally or vertically,

Fig. 7. Intra- and extraoral digital radiographic equipment. (Left) Digital processor and computer. (Right) Cassettes and high- frequency beam generator.

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Fig. 10. Periodontal probe in gingival sulcus. Note the gingival bleeding, swelling, and recession (arrows).

odontal disease (attachment loss), which is the basis for periodontal treatment. Radiographic findings primarily associated with periodontal disease in- clude horizontal bone loss, vertical bone loss, and Fig. 8. Placement of the full-mouth speculum with gum plates widened periodontal ligament spaces (Fig. 12). and a dental halter suspended from a boom on the stocks during Other radiographic findings that may be associated examination of the incisors. with periodontal disease include bone lysis, bone sclerosis, blunting of root tips, fractures, etc. (Fig. 13). All findings of the periodontal examination are recorded in the permanent medical record/dental beyond its physiologic movement.26 Occasionally, be- chart for future reference. cause of advanced periodontal disease, mobility will be detected when tooth surfaces are examined with the Grading the Severity of Periodontal Disease dental explorer. The function of the periodontium is attachment of If evidence of periodontal disease is found during the tooth within the gomphosis joint. Disease of the oral examination, radiographic evaluation is in- the periodontium (gingiva, cementum, periodontal dicated. Both intra- and extraoral radiographic ligament, and alveolar bone) results in attachment techniques are used to evaluate attachment loss. loss. Periodontal disease is the stage of progressive Radiographs are paramount to the staging of peri- attachment loss, not the process itself.27 The active inflammatory process resulting in compromise of the periodontium is periodontitis.27 Periodontitis oc- curs in periods of quiescence and active inflamma- tion, and the process is not linear.27 Periodontal disease is distinguished from periodontitis in that it is the state of the progressive attachment loss re- sulting from the periods of periodontitis. Although attachment loss (periodontal disease) may be present, the examiner may not see the active state of disease because of the phasic nature of periodontitis. Accurate assessment and staging of the state of the periodontal attachment apparatus requires con- sideration of intraoral physical-examination find- ings, primary and supportive radiographic findings, and indices used to stage the disease. Staging in- dices are used when diseases are progressive in nature. The gingivitis index (GI) is used to stage severity of gingivitis (Table 1).28 Careful attention should Fig. 9. Food stasis in periodontal pockets and widened inter- be given to the exposed gingiva as well as the sul- proximal spaces. cular gingiva when grading gingivitis. Cementum

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Fig. 11. Yellow arrow, cemental hyperplasia of the cheek teeth; green arrows, gingival bleeding and calculus on the vestibular aspect of 207. on the clinical and gingival crown is evaluated for that result in food stasis is important in achieving staining, decay, hypoplasia, and hyperplasia. Peri- this goal. To a large extent, humans rely on me- odontal pockets are measured for depth and mesial chanical cleansing of the teeth to remove food depos- to distal length, and when interproximal spaces are its, plaque, and disease-causing bacteria of the involved, a lingual to vestibular, palatal to vestibu- periodontium. Horses must rely primarily on the lar, or labial to lingual measurement is recorded salivary bathing of the periodontium, continual 29 on the patients’ dental chart. Tooth mobility is movement of food matter through deglutition, and measured with reference to the occlusal surface of hypsodontic dental anatomical adaptations to re- the teeth. It should be noted that the tooth occu- duce the likelihood of periodontal disease. Oral pies a gomphosis joint, and in some cases, slight equilibration is an important component of treat- physiologic mobility may be evident, especially in ment to reduce food stasis. Malocclusions causing geriatric patients with expiring teeth. All mea- dental interlocks reduce normal masticatory motion surements are recorded in millimeters. The mo- and food movement (Fig. 14). Vestibular (buccal) bility index is used to grade tooth mobility (Table and/or lingual enamel points may lead to ulcerations 2).30 A grade of M1 indicates slight movement causing oral pain and packing of food in the vesti- beyond normal physiologic mobility and is patho- logic mobility.6,26 When the components of the bules, increasing the risk of periodontal disease. periodontium have been intraorally and radio- Abnormal occlusal forces resulting in orthodontic graphically evaluated, an estimate of attachment movement of teeth may create areas where food loss is made, and the stage of periodontal disease becomes lodged (Fig. 15). Normalizing these forces is assigned based on the periodontal disease index and reducing sharp enamel points must be consid- (PDI) (Table 3).6,31 ered when treating periodontal disease. Dental fractures and areas of decay may not only increase Treatment the risk of food stases but may directly con- The goal of treatment is to preserve the periodon- tribute to periodontal disease through trauma to tium supporting the tooth, preventing tooth failure the periodontium. These conditions should be and eventual exfoliation. Addressing all factors treated accordingly with appropriate methods,

Fig. 12. Radiographic evidence of attachment loss. White brackets, horizontal bone loss; yellow arrowheads, blunting of root tips; white arrows, widened periodontal ligament space.

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Fig. 13. Bone sclerosis related to dental disease. (Left) 100 arcade in an 18-yr-old horse. (Right) The same patient’s 200 arcade, with red arrows indicating an area of sclerotic bone related to chronic 207 fracture and accompanying periodontal disease.

which may include endodontic, restorative, or surgi- reduced food stasis. Horses with interproximal cal procedures. spaces that trap even soft hay or grass may be fed a Correction of all conditions predisposing to food watered-down complete pelleted feed. Pelleted stasis may not be possible. In aged horses with feeds break down quickly in a small amount of water minimal tooth remaining in the alveolus, widened and have a small particle size, helping them to move interproximal spaces may not be reducible. through the widened interproximal space. Time Although uncommon, the same is true for younger spent masticating this food can be increased by horses with cheek teeth that have parallel axes of spreading the feed out in a pan or trough as opposed eruption and widened interproximal spaces. In to feeding from a bucket. cases where the teeth are unable to drift together to Before of the periodontium, rinsing close the widened interproximal spaces, the condi- the oral cavity with antiseptic mouthwash will re- tion is managed, not cured. Eliminating grain from duce oral microflora loads.32 Careful attention the diet and increasing grass or soft hay will in- must be paid to rinsing agents and their dilutions crease masticatory motion and time. This results (chlorhexidine, 0.12% or less), because some have in more salivary bathing of the periodontium and been shown to inhibit healing of the periodontium.33 In patients predisposed to high risk of infection, perioperative prophylactic antibiotics should be con- sidered.33 It is imperative to remove as much in- Table 1. Gingivitis Index fected and/or necrotic tissue from the periodontium Stage Examination Findings as possible. This may require supra and subgingi- val scaling, curettage, or root planning of affected GI0 Normal gingiva. GI1 Mild inflammation; slight change in color, slight edema; no . GI2 Moderate inflammation; redness, edema, and glazing; Table 3. Equine Periodontal Disease Index bleeding on probing. GI3 Severe inflammation; marked redness, edema, and Stage Degree of Attachment Loss ulceration; tendency to spontaneous bleeding. PD0 Normal: no attachment loss. Probing depth Ͻ3 GI, gingivitis index. mm I, C, and PM1-PM2 and Ͻ5 mm to PM2- M3. PD1 Gingivitis: no attachment loss. Probing depth Ͻ3 mm I, C, and PM1-PM2 and Ͻ5mmto Table 2. Mobility Index PM2-M3. Stage Degree of Mobility PD2 Early periodontal disease: Ͻ25% attachment loss and/or radiographic evidence of crestal/marginal M0 Normal: no distinguishable sign of movement greater bone loss around teeth. than normal (immeasurable movement). PD3 Moderate periodontal disease: Ͻ50% attachment M1 Slight: the first distinguishable (measurable) sign of loss or radiographic evidence of bone loss Ͻ50% movement greater than normal. around tooth root(s). M2 Moderate: movement of up to ϳ3mm(1mmin PD4 Advanced periodontal disease: Ͼ50% attachment humans). loss or radiographic evidence of bone loss Ͼ50% M3 Severe: movement Ͼ3 mm in any direction and/or is around tooth root(s). depressible. PD, periodontal disease; I, incisor; C, canine; PM, premolar; M, M, mobility index. molar.

AAEP PROCEEDINGS ր Vol. 56 ր 2010 447 RESPIRATORY/DENTISTRY patches placed in widened interproximal spaces may help retain the perioceutic in place longer and act as a physical barrier to food impaction during the heal- ing process (Fig. 16). Systemic antibiotics may include potentiated tri- methoprim sulfa, metronidazole, potentiated tri- methoprim sulfa in conjuction with metronidazole, and doxycycline. In humans, antiseptic mouth- washes (chlorhexidine digluconate, 0.12–0.20%) q 12 h for 1–4 wk post-periodontal surgery aid in wound healing and reduction of gingivitis.34 In horses, caregivers can be taught to use 400-ml nylon dose syringes or garden sprayers to administer post- periodontal surgery antiseptic . If a tooth has a mobility index of M3 or a periodon- tal disease index of PD4, the treatment of choice is extraction. If left in place, these teeth only predis- pose proximal teeth to the spread of periodontal disease. When the extent of treatment necessary is Fig. 14. Arrows, malocclusions reducing normal masticatory beyond the scope of the primary practitioners expe- motion. Note the disparity between the 100 and 200 arcades. rience and/or instrumentation, referral to a practi- tioner with advanced training in equine dentistry is appropriate. teeth. Currently, this is limited by the instrumen- Prevention tation available. Hand instruments, air Prevention is a key component in the control of units, magnetostrictive or piezoelectric ultrasonic periodontal disease. Regular veterinary oral-health scalers, high-speed hand pieces with diamond burs, examinations, oral-equilibrium maintenance, appro- and equine diastema burs are available. If human priate grazing periods, and early detection and dental instruments are used, the dental bur and treatment of periodontal disease all decrease the scaler tip lengths are limiting factors when debrid- likelihood of advancing periodontal disease. By the ing deep pockets in equidae. time owners notice common signs of periodontal dis- Doxycycline and metronidazole have been used in ease (halitosis, pain, attitudinal changes, behavioral perioceutic products for the treatment of periodontal changes, facial swellings, weight loss, etc.), the pa- pockets with the goal of regeneration of the peri- tient is already in advanced stages of periodontal odontal ligament. When regeneration efforts are disease. To meet the goal of treatment, which is unsuccessful, should be considered. preservation of the tooth, periodontal pathology Vinyl polysiloxane or polymethylmethacrylate must be diagnosed and treated before the advanced stages of PD3–PD4 (Table 3). After periodontal disease has exceeded stage 2, extraction becomes a likely course of treatment. Frequency of veterinary

Fig. 15. Widened interproximal space after removing food mat- ter. Note the gingival recession (arrow) and bleeding. Fig. 16. Vinyl polysiloxane in a widened interproximal space.

448 2010 ր Vol. 56 ր AAEP PROCEEDINGS RESPIRATORY/DENTISTRY examination and treatment is based on patient pa- 12. Nanci A. Ten cate’s oral histology: development, structure, thology. Combined efforts of the veterinarian and and function, 7th ed. St. Louis, MO: Mosby, Inc., 2007;260. owner are necessary to improve prevention, early 13. Nanci A. Ten cate’s oral histology: development, structure, and function, 7th ed. St. Louis, MO: Mosby, Inc., 2007; initial detection, detection of recurrence, and treat- 351. ment of periodontal disease. 14. Newman MG, Takei HH, Carranza FA. Carranza’s clinical , 10th ed. St. Louis, MO: Saunders/Elsevier, 4. Results and Discussion 2006;64. The periodontium is structurally and functionally 15. Klugh DO. A review of equine periodontal disease, in Pro- complex. It requires regular evaluation to ensure ceedings. 52nd Annual American Association of Equine Practitioners Convention 2006;551–558. appropriate treatment. Treatment should be di- 16. Easley KJ. How to properly perform and interpret an endo- rected at elimination of food stasis, direct treatment scopic examination of the equine oral cavity, in Proceedings. of periodontal tissues, management of ongoing dis- 54th Annual American Association of Equine Practitioners ease, and prevention of recurrence of the disease Convention 2008;383–385. state to eliminate exfoliation of the teeth. Owner 17. LeBlanc PH. Chemical restraint in the standing horse. Vet Clin North Am [Equine Pract] 1991;7:521–533. compliance and regular veterinary monitoring are 18. Quandt J. The art and science of sedation, in Proceedings. critical to success of treatment. Examination and Veterinary Dental Forum 2005;19. treatment of periodontal disease are often an exer- 19. Tranquilli WJ, Thurmon JC, Grimm KA, et al. Lumb & cise in management of an ongoing condition and not Jones’ veterinary anesthesia and analgesia. 4th ed. Ames, a curative process. 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