Myths and misconceptions in veterinary dentistry

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  • 1818 VetMedToday:ReferencePoint JAVMA,Vol231,No.12,December15,2007

    Periodontal disease is the most common disease identified in dogs and cats.1 Local severity and the impact on the rest of the body are reasons that all com-panion animal patients should receive an oral examina-tion every time they are at a veterinary facility.2,3

    Veterinary dentistry has progressed from the dental or prophylactic procedures of the 20th century, which often involved an injection of a short-acting tranquil-izer or anesthetic and a few minutes spent removing supragingival calculus, to the current comprehensive treatment of periodontal and other dental diseases that require general anesthesia. The days of clean-and-pull or watchful waiting in the case of fractured teeth have been replaced by prevention, recognition, and treat-ment of dental disease and painful oral conditions. As recently as 25 years ago, there were a limited number of veterinary textbooks, continuing education op-portunities for practitioners desiring to improve their dental knowledge and skills, and referral practices for dental care of animals. Currently, veterinary students and practitioners have multiple veterinary dental text-books, journal articles, and quality opportunities for continuing education, and referral to a board-certified veterinary dentist is a realistic option.

    Some traditional practices and misconceptions are still being taught and shared. Myths and misconcep-tions in other areas of veterinary practice have been ad-dressed.4-6 The objectives of the information provided here are to clarify new concepts, dispel common mis-conceptions and outdated beliefs, improve awareness of current veterinary dentistry, and aid practicing vet-erinarians in the delivery of a higher quality of dental care.

    MythVeterinary dentistry involves minor pro-cedures that require no special patient preparation or monitoring during anesthesia.

    RealityDental patients often become hypother-mic because of the cooling of a patient as a result of continuous use of water in the mouth from power scal-ers and high-speed drills, prolonged procedures, and metal tables. Very small animals (< 5 kg [< 11 lb]) are especially at risk of developing hypothermia because of

    Myths and misconceptions in veterinary dentistry

    From North Florida Veterinary Dentistry, 2961 Egret Walk Terrace S, Jacksonville, FL 32226 (Hoffman); Animal Dental Center, 2100 W Silver Spring Dr, Milwaukee, WI 53209 (Kressin); and Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616 (Verstraete).

    Address correspondence to Dr. Hoffman.

    their larger surface area-to-volume ratio, compared with heavier animals.7 Hypothermia defined as mild (36.7o to 37.2oC [98o to 99oF]), moderate (35.6o to 36.7oC [96o to 98oF]), severe (33.3o to 35.6oC [92o to 96oF]), and critical (< 33.3oC) has been correlated with decreases in heart rate, respiratory rate, and blood pressure; CNS depression; alterations in coagulation, cellular and humoral immunity, and wound healing; morbidity; and death.8,9 Bradycardia secondary to hypothermia is unresponsive to anticholinergics.10 Hypothermic ani-mals require more time to recover from anesthesia.11 Simple measures such as continuous monitoring of intraoperative temperature, use of circulating warm water blankets or forced-air warming devices, and IV administration of warm fluids will aid in the preven-tion and correction of hypothermia.

    Many patients that undergo dental procedures are old and have other problems, such as mitral valve regurgitation, hepatic disease, or renal disease. Con-sequently, anesthesia of these patients is likely to en-tail greater risk than would anesthesia of younger, healthier patients. The anesthetic protocol should be planned only after careful consideration of results of physical examinations and laboratory tests. Appro-priate IV administration of fluids and monitoring of blood pressure, oxygenation, heart rate and rhythm, and body temperature are especially important in older or compromised patients.4 Measurement of end-tidal carbon dioxide concentrations by the use of capnography can provide clinicians with informa-tion about a patients state of perfusion, ventilation, and metabolism as well as indications about equip-ment malfunction.12

    MythDental extraction sites should be left open to provide drainage and allow healing by second intention.

    RealityExtraction of teeth is a surgical proce-dure. After preoperative radiography, treatment plan-ning, and extraction, the alveolus is debrided carefully with a spoon curette to remove any infected granula-tion tissue, debris, purulent material, or necrotic bone. Rough alveolar bone edges are smoothed.13,14 Ideally, the gingiva should lie flat against the alveolar bone. Sutur-ing the alveolus closed helps to speed healing, prevent infection, and reduce postoperative pain.13 Suturing is mandatory following extraction of multiple mandibu-lar premolars and molars because the gingiva typically falls away from the extraction site, which leaves bone exposed. Exposed bone can cause pain and leads to de-layed wound healing.15 Sufficient gingiva is elevated to

    Reference Point

    Sharon L. Hoffman, dvm, davdc; Dale J. Kressin, dvm, davdc; Frank J. M. Verstraete, drmedvet, mmedvet, davdc

  • JAVMA,Vol231,No.12,December15,2007 VetMedToday:ReferencePoint 1819

    allow suturing without tension; otherwise, it is likely there would be wound dehiscence. To avoid tension, the flap may be released by further undermining or careful incision of the underlying periosteum. If it is not possible to fully close a gingival flap without ten-sion, then partial closure is preferable to tension; the resulting defect will heal by granulation and epitheliali-zation. Closure or partial closure will also help to keep in place the blood clot that forms in the alveolus fol-lowing tooth extraction, which is important for optimal healing.15

    Hemorrhage may be a complication of exodontia. Hemostatic defects may not be apparent until after ex-traction; associated hemorrhage does not stop within a few minutes, and copious bleeding continues and can become a life-threatening situation. Suturing the gin-giva with a hemostatic material in the alveolus can be beneficial.15

    When an oronasal fistula is evident before extrac-tion (because of extensive periodontal disease) or after extraction (as a complication), then closure of the fis-tula is required to prevent a constant influx of food and liquid into the nasal cavity.13,16,17

    MythSwelling or a draining tract located in the facial area below either eye is always an indication for extraction of the maxillary fourth premolar tooth.

    RealityEndodontic disease resulting in periapi-cal inflammation and abscess formation may cause swelling of hard or soft tissues or a draining tract. In dogs, this is most commonly secondary to endodontic disease of the maxillary fourth premolar (carnassial tooth), hence the term carnassial abscess.18 Dental ra-diography with periodontal probing of all teeth on the caudal maxilla is necessary to establish a diagnosis. A similar condition sometimes affects the maxillary first molar or third premolar. A facial (suborbital) swelling or draining tract may also recur when extraction is used as treatment and a root tip is left in place.18 Additional nondental causes of suborbital facial swellings or drain-ing tracts include sialoadenitis,20 bite wound abscess, foreign body abscess (such as gunshot or wood impac-tion), maxillary fracture and bone sequestration, and nasal or maxillary neoplasia.21 Orbital or retro-orbital cellulitis may or may not be related to extension of in-fection from a caudal tooth root. Examination of the caudal portion of the oral cavity and dental radiogra-phy are indicated in patients with decreased retropul-sion of the globe, exophthalmos, ocular discharge, and periocular swelling with or without evidence of pain when opening the mouth. Other differential diagnoses to consider in patients with orbital or retro-orbital cel-lulitis or abscess include extension of a nasal infection (bacterial or fungal), zygomatic sialoadenitis, and for-eign body penetration.22

    Radiography is essential in the diagnosis and treat-ment planning for suborbital swellings. Additional helpful diagnostic tests may include periodontal prob-ing, collection of tissue biopsy specimens for histologic examination, or computed tomography.

    Extraction of the maxillary fourth premolar tooth may not always be appropriate. Although there are some absolute indications (eg, no other treatment option

    exists) for extraction, alternative treatment is recom-mended for strategic teeth (permanent canines and car-nassial teeth) that are periodontally sound. Endodontic treatment and restoration of the crown can allow a tooth to be maintained.23

    MythPatients that need radiation therapy of the head or neck should always have teeth extracted prior to radiation treatment.

    RealityHigh-dose radiation therapy of the head and neck causes a hypovascular, hypocellular, and hy-poxic state in the jaws and surrounding soft tissues. This can lead to delayed wound healing and osteoradionecro-sis of bone.24,25 The risk of osteoradionecrosis continues for the remainder of the patients life and does not de-crease with time.26

    It has long been believed that extraction of teeth in poor condition (those with periodontal disease or car-ies) within the high-dose volume area prior to adminis-tration of high-dose radiation therapy would reduce the risk of osteoradionecrosis. This hypothesis has been ex-tended to patients with teeth in fair to good condition who have a good chance of being cured and a long life expectancy, particularly when the likelihood of main-taining the health of their teeth is in question. Howev-er, findings from a large series of human patients with oropharyngeal cancer who received radiation therapy revealed that extraction prior to radiation treatment does not reduce the risk of osteoradionecrosis, regard-less of the condition of the teeth.25 There was no differ-ence in the rate of osteoradionecrosis between patients with healthy teeth in the radiation-treatment field who had teeth extracted prior to radiation therapy, which indicates no clear benefit to the use of prophylactic ex-tractions.25 In a prospective study24 of 40 patients who received nasopharyngeal radiation therapy, extractions after radiation treatments had a low risk of complica-tions, and results pointed to age of a patient as a factor that may influence wound healing.

    The pretreatment recommendation remains to ex-tract teeth in the proposed high-dose treatment field when they are in poor condition because of existing dental disease. Teeth that are in fair condition, as de-termined by a veterinary dentist, need not be prophy-lactically extracted prior to radiation treatment in an attempt to prevent subsequent osteoradionecrosis.25

    During radiation therapy, patients should receive daily dental care by the owners at home and regular professional periodontal debridement (scaling and root planing). A long-term, 3-month interval between professional dental examinations is recommended.26,27 When compliance with daily dental hygiene at home or professional dental care is lacking, which is often the case in companion animals, it may be prudent that teeth affected by dental disease and that will be exposed to radiation be extracted prior to radiation treatment.

    MythA fractured tooth can always be treated with watchful waiting.

    RealityVeterinarians commonly examine frac-tured teeth in companion animals. A survey19 of oral and dental diseases in 63 anesthetized dogs revealed

  • 1820 VetMedToday:ReferencePoint JAVMA,Vol231,No.12,December15,2007

    that 27% had fractured teeth and 10% had multiple fractured teeth. Signs of pain or discomfort may not be recognized for several reasons. Veterinary patients often do not display signs of pain and discomfort and there-fore may be extremely stoic and silent. Clinical signs of pain and discomfort may only be evident as subtle changes in behavior, and veterinarians and veterinary staff members may not be adequately trained in evalu-ating animal behavior. Physical examinations may not be consistently scheduled for veterinary patients, and oral evaluations are too often inadequate, especially when a patient has pain or discomfort and is protect-ing the oral cavity. A patient with a fractured tooth may initially have severe pain, which subsequently subsides. Later in the disease progression, an affected dog may have pain associated with periapical lesions. Periapi-cal abscesses or draining tracts associated with chronic fractured teeth are often hidden from clear view by the lips and buccal mucosa, whereas periapical granulomas are typically not associated with clinical signs.

    Oral radiography is fundamental to the diagnosis of periapical disease. Early intervention for disease pre-vention or disease progression is a superior approach to the watchful waiting paradigm. The American College of Veterinary Anesthesiologists has adopted a position statement that includes the following concept: Animal pain and suffering are clinically important conditions that adversely affect an animals quality of life.28 Fur-thermore, the American College of Veterinary Anesthe-siologists encourages veterinarians and veterinary staff members to increase their knowledge and skills with regard to pain recognition and management and to ap-ply them to develop effective and safe protocols for the management of pain, which offers clients optimal treat-ment options for their pets.

    Veterinarians are encouraged to develop a philoso-phy that promotes prevention and alleviation of pain in animals. A proactive approach to dental care in com-panion animals is an important step. Veterinarians are encouraged to be proactive in recognizing and address-ing dental pain and infection associated with fractured teeth in companion animals. Performing fundamental diagnostic testing (oral radiography and periodontal probing) and determining the correct diagnosis is es-sential, and referral to board-certified specialists is rec-ommended when appropriate dental services cannot be provided by a veterinarian.

    MythAn animal with an abscessed tooth can al-ways be treated with antimicrobials.

    RealityFractured teeth are subject to bacterial ingress, pulpitis, pulp necrosis, and periapical inflam-mation (abscess, granuloma, or periodontitis).29 Frac-tured enamel or dentin, with or without pulp exposure, does not have the ability to heal or seal over. A tooth does not need to be fractured for there to be periapi-cal inflammation. Acute traumatic injury (blunt trau-ma), chronic trauma (bruxism or concussive chewing forces), or loss of blood supply (luxation) can result in pulpitis, eventual pulp necrosis, and formation of a periapical granuloma or abscess. Discoloration of any tooth is a strong indicator of pulpitis, and pulp necros...