RESPIRATORY/DENTISTRY How to Assess the Equine Periodontium Jon M. Gieche, DVM The periodontium is the attachment apparatus of the tooth. 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 cementum, diagnose and treat dental pathology. The seven periodontal ligament, bone 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 joint 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 periodontal disease 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 periodontal examination 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 process is the bone of the maxilla, consideration during examination and either di- mandible, and incisive bone that contains the alveoli rectly or indirectly must be considered when devel- (sockets). The outer layer (vestibular, lingual, or NOTES AAEP PROCEEDINGS ր Vol. 56 ր 2010 441 RESPIRATORY/DENTISTRY Fig. 1. Yellow arrow, cementum on incisors; red arrow, widened interproximal space between 201 and 202; green arrow, gingival recession (gingivitis 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 premolars and up to 5 mm for the remaining the alveolus is referred to as crestal bone. Bone cheek 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 sulcular epithelium. physical examination will help rule out concomitant It attaches to the tooth as the junctional epithelium 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 crown 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. 442 2010 ր Vol. 56 ր AAEP PROCEEDINGS RESPIRATORY/DENTISTRY 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 gingival sulcus, 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 tongue 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 tooth resorption and hypercementosis (EOTRH),22 missing incisors, temporal mandibular joint disease, and/or jaw 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. Periodontal probe 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). AAEP PROCEEDINGS ր Vol. 56 ր 2010 443 RESPIRATORY/DENTISTRY 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