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Category: Dentistry

The term “beakistry” sounds like it could be one of the dark arts worthy of inclusion in a novel by Stephen King, the master of the horror genre, it isn’t. It’s a term to describe a form of dentistry applied to animals with beaks, like birds and turtles.

Turtles like Stephen King.

Now, don’t call any lawyers, because we’re not sullying the good name of any best-selling authors. Stephen King is the name given to a yellow-bellied slider turtle rescued from a pier at Falls Lake in Wake Forest after he was severely injured by a fisherman’s hook.

Stephen King’s beak was damaged by a fishhook.

It appears that the turtle was caught by someone fishing from the pier. While attempting to remove the fishhook from the turtle’s mouth, its beak was horribly injured. Fortunately, this turtle was noticed by good samaritan Loren Tatum, a former member of the NC State College of Veterinary Medicine’s Turtle Rescue Team and a veterinary technician.

Tatum took the turtle to a local veterinarian, the hook still embedded in its mouth. The injury was so severe the case was referred to NC State. Graduate student Mandy Womble took the call and handled the intake for the injured turtle. “At first I didn’t understand why they couldn’t treat the turtle locally — until I saw how bad it really was,” she says.

The Turtle Rescue Team is headed up by Greg Lewbart, professor of aquatic animal medicine. The team is a volunteer organization run by veterinary students who provide medical, surgical and husbandry services free of charge in the hope of releasing rehabilitated turtles back into the wild.

The Turtle Rescue Team sees and treats over 500 wild turtles, reptiles and amphibians each year. Students have the opportunity to not only refine their medical skills on exotic species like turtles, but they also help protect North Carolina’s native wildlife.

Student volunteers take turns accepting patients into the program, and all the turtles who come under the care of the team, get names. This year, they are using the names of celebrities, which is how Stephen King the turtle got his name.

Lewbart says that he had never seen an injury quite like the one suffered by Stephen King. “It was out of my wheelhouse,” he noted. But as luck would have it, just this summer the CVM has added two board-certified veterinary dentists to its team of clinicians and Lewbart thought they may be able to help in this particular case.

He was right.

Curtis Stiles, clinical assistant professor of dentistry and oral surgery, and Lenin Arturo Villamizar-Martinez, assistant professor of dentistry and oral surgery, were eager to be of service. They operated on Stephen King for more than an hour, with help from registered veterinary technician Jeannie Losey.

Lenin Villamizar-Martinez, assistant professor of dentistry and oral surgery, left and Curtis Stiles, clinical assistant professor of dentistry and oral surgery, right.

The dentists had to improvise a technique they — and possibly no one else — had ever used before. “We used some buttons and elastic that are used in human dentistry,” Villamizar-Martinez explains, “and just used regular principles of the profession to brace the injury. The hardest part was getting the repair stabilized. It was a strange injury.”

He points out that the case met three principles he and Stiles use in treating veterinary dental cases — that after treatment the animal is able to socialize, eat by itself and is not in pain and can enjoy a good quality of life. Stephen King met all three.

Reptiles and amphibians are slow healers, Lewbart says, so the brace will be in place for about three months. Although it won’t be able to eat normally, its mouth is left slightly open so it can breath in case its nose is somehow obstructed. In the meantime it will be fed and kept hydrated through a feeding tube inserted by Womble  — “the first one I’ve ever done” she says. The turtle will be kept in its own tank in the Turtle Rescue Team quarters until it is fully healed and ready to be released back in the wild at Falls Lake.

Although it was an unusual case and the injury was especially bad, Lewbart says he is very optimistic that Stephen King will fully recover and return his old haunts (sorry, couldn’t resist that). With resources like the Turtle Rescue Team and a fully staffed clinical dentistry service, the CVM is prepared to handle unusual and difficult cases of all kinds for individual clients and referring veterinarians.

Even cases that require beakistry.

~Steve Volstad/NC State Veterinary Medicine

Last year, the American Dental Association (ADA) introduced a new exam called the Advanced Dental Admission Test (ADAT). This was in response to the lack of scores from other standardized dental exams such as the National Board Dental Examination (NBDE) Part I/II and the dental colleges having switched to using a Pass/Fail system. Advanced dental/specialty

The post The Advanced Dental Admission Test (ADAT) : What We Know So Far appeared first on Student Doctor Network.

Evidence-Based Endodontics welcomes submissions!

Santiago Peralta, DVM, DAVDC, and Nadine Fiani, BVSc, DAVD, Cornell University

CE TEST

The CE test is provided at the bottom of this article.

As described in “Part 1, Principles & Normal Findings” (January/February 2017), dental radiography in dogs and cats constitutes an essential component of a comprehensive diagnostic plan.1-4 Part 1 also described appropriate mounting and display of radiographic films/plates for reviewing purposes, explained a recommended workflow to review radiographs and record findings, and presented radiographic examples of normal relevant structures.

This article focuses on interpretation of normal anatomic variations as well as congenital and pathologic abnormal findings on dental radiographs in dogs and cats (Box 1). Both articles assume the reader is familiar with basic dental radiographic acquisition techniques, concepts, and skills.

REVIEWING DENTAL RADIOGRAPHS

Teeth Abnormally Present and/or Absent

Persistent deciduous teeth with the permanent counterpart present (Figures 1A and 1B) are considered a pathologic condition of suspected genetic origin that predisposes the involved permanent teeth to periodontitis and malocclusion. This is a common condition in dogs, especially toy breeds, but uncommon in cats. The treatment of choice is extraction of the persistent deciduous teeth.

Although the initial diagnosis is clinical, radiographs are necessary to document the orientation of the root relative to the permanent counterpart and/or other teeth in the immediate vicinity, as well as the degree of root resorption (if present). This information is essential to minimize potential collateral damage when extracting a persistent deciduous tooth.

Figure 1. Persistent deciduous teeth. Figure 1A shows a persistent right maxillary deciduous canine tooth in a 7-month-old dog; the permanent counterpart is present. Figure 1B shows a persistent right maxillary deciduous canine tooth in a 6-month-old cat; the permanent counterpart is present. Figure 1C shows a persistent deciduous left maxillary second premolar tooth in a 1-year-old dog; the permanent counterpart is not present. Figure 1D shows a persistent deciduous left mandibular fourth premolar tooth in the same dog as Figure 1C; the permanent counterpart is not present.

Persistent deciduous teeth without a permanent counterpart (Figures 1C and 1D) are usually smaller and slightly more radiolucent than the contralateral, adjacent, and/or opposing permanent teeth.

Clinicians should keep in mind that the morphology of a persistent deciduous premolar resembles that of the permanent tooth immediately distal to it (eg, the deciduous fourth premolar resembles the permanent first molar) to it but is significantly smaller.

Clinicians should be also familiar with normal deciduous tooth exfoliation times and know which teeth have a deciduous predecessor (ie, deciduous dental formula).5,6

Retained (unerupted or embedded) teeth (Figures 2A and 2B) are important because they can result in dentigerous cyst formation (see Jaw Lesions of Developmental Origin)7 and are, therefore, considered pathologic. Although deciduous teeth may be retained, most retained teeth are permanent.

Figure 2. Retained (unerupted or embedded) teeth. Figure 2A shows a retained right mandibular first premolar tooth in a 6-year-old dog. Figure 2B shows retained left and right mandibular canine teeth in a 4-year-old dog. Note that the left and right mandibular premolar teeth are missing; based on history and breed, the absence of these teeth was considered congenital in origin.

The cause of tooth retention is not always apparent. If a physical barrier (eg, bone, another tooth) did not allow the tooth to erupt, the tooth can be referred to as impacted. Retention of the first premolar tooth appears to be relatively common in brachycephalic dogs, suggesting possible genetic mechanisms.7 In some cases, historical or radiographic findings may suggest a traumatic origin (eg, local trauma during odontogenesis); some retained teeth may be dysplastic.

As retained teeth are not visible clinically, radiographs are necessary to establish a diagnosis. Dental radiographs are indicated whenever there are missing teeth with no obvious cause (eg, previous tooth loss, extraction).

Congenitally missing teeth (Figure 2B) are considered an incidental finding. The term hypodontia is applied when several teeth are absent; the term oligodontia is a relative term that can be used when only a few teeth are present.8 Congenitally missing teeth should be suspected if dental radiographs do not show retained and/or resorbing roots, unerupted teeth, or vacated and/or remodeling alveoli.

Crowding and rotation (Figure 3A) may be considered normal or part of the standard in certain breeds (eg, brachycephalic dogs). Teeth present in severely crowded areas may be rotated owing to the lack of space; this is particularly common with the maxillary third premolar tooth of dogs with maxillary brachygnathia. Teeth that are in close proximity represent a plaque-retentive area and may therefore predispose an animal to focal periodontitis. Although crowding and rotation can be appreciated clinically, dental radiographs are useful to document the periodontal status of the teeth involved (Box 2).

Figure 3. Crowding and supernumerary teeth. Figure 3A shows crowding of premolars with rotation and palatoversion of the right maxillary third premolar tooth in a 6-year-old dog. Figure 3B shows a supernumerary right maxillary first premolar tooth, as well as crowding of premolars with rotation and palatoversion of the right maxillary third premolar tooth in a 3-year-old dog.

Supernumerary teeth (polydontia) (Figure 3B) can be present at any location in the dental arches. More than one supernumerary tooth can be present in the same area. Other than creating a plaque-retentive area and, therefore, predisposing the animal to periodontal disease, supernumerary teeth are usually considered a normal anatomic variation.

Malformations

Enamel hypoplasia (Figures 4A and 4B) is considered pathologic; affected areas are plaque retentive and predispose affected teeth to caries and periodontal disease. The defects can be seen clinically and radiographically as irregularities in the enamel. Teeth with enamel hypoplasia can also have dysplastic roots that are only detectable radiographically.9

Figure 4. Enamel hypoplasia. Figure 4A shows the clinical appearance of enamel hypoplasia affecting the maxillary incisors and canine teeth in a 7-month-old dog. Figure 4B is a lateral projection of the left maxillary canine tooth on the same dog; note the defective enamel at the mesial aspect of the cusp.

Dysplasia (odontodysplasia) (Figure 5A) of the crowns of erupted teeth is evident clinically; however, malformation of roots or of unerupted teeth is only detectable radiographically. If only one or a group of adjacent teeth are malformed, local trauma or infection during odontogenesis is suspected as the cause. If odontodysplasia is generalized or semigeneralized, systemic acquired or congenital causes are suspected.

Dens-in-dens (dens invaginatus; Figure 5B) is a rare malformation in which the enamel and underlying dentin invaginate towards the pulp cavity, sometimes resulting in a direct or indirect communication and, in some cases, secondary endodontic disease. The malformation may or may not be clinically evident. Radiographically, it may appear as a small tooth-like structure within the pulp cavity, and endodontic disease (see Endodontic Findings) is often present.

Figure 5. Odontodysplasia and dens-in-dens. Figure 5A shows a dysplastic root of the right maxillary canine tooth in a 9-year-old dog. Periodontitis of varying severity is present at the incisors, canine, and premolar teeth, as well as external inflammatory tooth resorption at the second premolar. Figure 5B shows dens-in-dens affecting the right mandibular first molar tooth of a 5-year-old dog; note the abnormal appearance of the crown just above the furcation area and extending mesially.

Double teeth (Figures 6A and 6B) appear to have two crowns due to gemination or fusion. Gemination occurs when two crowns originate from a single root; fusion occurs when the roots of two independent teeth fuse. Clinically, these conditions are indistinguishable; radiographs are necessary to determine if double teeth are due to gemination or fusion. Regardless, double teeth are most often an incidental finding.

Figure 6. Double teeth. Figure 6A is a clinical image of a right maxillary first incisor tooth in a 4-year-old dog with seemingly two crowns. Figure 6B shows the occlusal radiograph of the same dog; note that the double maxillary incisor corresponds to fusion.

Concrescent or fused roots (Figure 7A) represent nonpathologic anatomic variations of clinical relevance because they may affect the surgical approach if a tooth requires extraction. The roots of multirooted teeth are usually slightly divergent with alveolar bone in between. However, in some cases, concrescence occurs when the roots of a tooth converge and are only separated by cementum. In other cases, actual fusion of the roots occurs.

Dilacerated roots (Figure 7B) have an acute angulation at their apical third. Although this is considered a developmental abnormality, it is not usually of clinical significance, unless the tooth has to be extracted for any reason. The extraction may require additional root exposure to avoid fracturing the tooth.

Figure 7. Fused and dilacerated roots. Figure 7A shows fused roots at the left mandibular second molar tooth in a 5-year-old dog. Figure 7B shows dilacerated roots at the left mandibular first molar tooth in another 5-year-old dog.

Peg teeth are relatively small, permanent mandibular premolar teeth with only one root (Figure 8). These are usually considered an anatomic variation of little or no clinical significance.

FIGURE 8. Peg tooth. The radiograph shows an abnormally small and single-rooted left mandibular third premolar tooth in a 6-year-old cat.

Jaw Lesions of Developmental Origin

Dentigerous cysts, by definition, are associated with unerupted teeth. The most commonly associated tooth is the first mandibular or maxillary premolar in dogs7; dentigerous cysts have not been reported in cats. The cystic lesion is usually visible radiographically as an area of geographic bone loss (see Jaw Lesions) of varying size; in some cases the lesion involves adjacent teeth (Figure 9A).

Mandibular radiopacities are round or oval well-defined radiopacities observed along the caudal or mid-mandibular body (Figure 9B). In the absence of clinical signs or anatomic proximity to an endodontically diseased tooth, the finding can be considered incidental and is likely the result of sclerotic bone.10

Figure 9. Jaw lesions. Figure 9A shows an unerupted right mandibular first molar tooth with an associated dentigerous cyst in an 8-year-old dog. Figure 9B shows a caudal mandibular radiopacity just rostral to the mesial root of the right mandibular first molar tooth in a 6-year-old dog.

Periodontal Findings

Calculus deposits, when thick, can be visible radiographically (Figure 10) because of their mineralized nature. However, the amount of calculus accumulation visible clinically and radiographically should not be used as an indicator of the severity or extent of periodontal disease.

FIGURE 10. Calculus. Heavy calculus deposits are visible radiographically over the left maxillary fourth premolar tooth in an 8-year-old dog.

Alveolar bone loss by definition is pathologic. Namely, if alveolar bone loss is present, a diagnosis of periodontitis is established. Of the 4 tissues that compose the attachment apparatus of teeth (the periodontium), alveolar bone is the only one that is directly visible on radiographs. In general, alveolar bone loss can follow a vertical or a horizontal pattern. Vertical bone loss is when the defect is perpendicular to the cementoenamel junction (CEJ; Figures 11A, 11B, and 11C); horizontal bone loss is when the defect is parallel to the CEJ. A combined pattern can also occur. The pattern of bone loss is clinically relevant as it can affect therapeutic options.

Buccal bone expansion is an alveolar bone loss pattern that seems to be unique to cats. Buccal bone expansion appears radiographically as bulbous and/or thickened alveolar bone with varying degrees of vertical bone loss, primarily on the buccal aspect of canine teeth (Figure 11D). More than one tooth can be affected.

Furcation defects can occur at a very early stage of periodontitis because the furcation area is very close to the alveolar margin. Furcation involvement is used to describe bone loss that is observed at the furcation but does not appear to communicate all the way through (Figure 11C). In contrast, furcation exposure refers to through-and-through defects (Figures 11A and 11C). If furcation exposure is detected, the long-term periodontal prognosis is poor, and extraction is most often indicated, regardless of severity of periodontitis.

Figure 11. Alveolar bone loss. Figure 11A shows moderate horizontal bone loss with furcation exposure affecting the left mandibular fourth premolar and first and second mandibular teeth of a 10-year-old-dog. The first molar tooth also has vertical bone loss at the mesial aspects of both roots. Note the inflammatory root resorption affecting the distal root of the second molar tooth. Figure 11B shows near-total loss of attachment due to severe horizontal bone loss at the left mandibular first and second incisors in the same dog and left and right mandibular canine teeth. Note the inflammatory root resorption at the apical area of the first incisor tooth; also note the calculus deposits on the crowns of the canine teeth. Figure 11C shows moderate horizontal bone loss with furcation exposure at the right mandibular fourth premolar and first molar teeth in a 15-year-old cat; note the inflammatory root resorption at the furcation areas. Figure 11D shows buccal bone expansion affecting the right maxillary canine tooth more than the left in a 9-year-old cat; note the inflammatory root resorption affecting the right canine tooth; note also the retained roots present at the incisor area.

Periodontal–endodontic lesions may be detectable radiographically if alveolar bone loss (ie, periodontitis) has allowed bacteria to enter the pulp cavity via the apical delta or accessory canals, with ensuing apical periodontitis. The radiographic characteristics usually include some degree of alveolar bone loss and periapical lucency around the root(s) (Figure 12). The prognosis of periodontal–endodontic lesions is poor.

FIGURE 12. Periodontal–endodontic lesions. This radiographs shows a right mandibular first molar tooth in a 7-year-old dog. There is moderate to severe combined horizontal and vertical bone loss and well-defined periapical lucencies at both roots.

Endodontic Findings

Crown integrity may be lost because of traumatic fractures. Tooth fractures are visible radiographically, although pulp exposure cannot be reliably diagnosed on a radiograph (it is determined clinically). The loss of crown integrity (Figure 13A) should alert and encourage clinicians to look for radiographic indicators of endodontic disease (see Apical periodontitis and Relatively wide pulp cavities) because the most common cause of endodontic disease is trauma.

Apical periodontitis is inflammation of the periapical tissues that invariably occurs in the presence of untreated endodontic disease (eg, inflamed or necrotic pulp). This inflammatory process is detectable radiographically after enough lysis of the associated bone has occurred (Figure 13B). Typically, the lesion appears as an ill- or well-defined round, lucent area that encompasses the apical portion of the root(s). Lack of radiographically detectable periapical lucency does not rule out apical periodontitis.

Relatively wide pulp cavities—when compared with contralateral, opposing, or adjacent teeth—may indicate a longstanding nonvital pulp (Figures 13A and 13C). Clinicians should be aware that a lack of discrepancy in pulp cavity width does not rule out endodontic disease, especially in cases of endodontic disease of relatively short duration (a few days or weeks).

Pulp stones are considered incidental findings that appear as mineralized structures within the pulp cavity on dental radiographs, sometimes in otherwise clinically and radiographically healthy teeth (Figure 13D). In the event endodontic intervention is required for unrelated causes, pulp stones may interfere with root canal instrumentation.

Figure 13. Endodontic disease. Figure 13A shows an occlusal maxillary radiograph of a 5-year-old dog; note the fractured crown of the right maxillary canine tooth and the relatively wide pulp cavity when compared with the contralateral tooth. Figure 13B shows a fractured middle cusp of the left mandibular first molar tooth in a 6-year-old dog; note the well-defined periapical lucencies at both roots. Figure 13C shows the occlusal maxillary radiograph of a 9-year-old dog with severe abrasion of several incisors; note the relatively wide pulp cavity of the right maxillary first incisor tooth and the associated well-defined periapical lucency. Figure 13D shows pulp stones at the mesial and middle pulp horns of the left mandibular first molar tooth in a 4-year-old dog; the tooth is otherwise periodontally and endodontically sound.

Chevron signs are widened periodontal ligament spaces in the apical areas of endodontically sound teeth, often in the shape of a chevron, resembling radiographic signs of apical periodontitis (Figure 14). This occurs most frequently at the maxillary incisors, canines, and mandibular first molar teeth. It is believed these areas are normal anatomic variations and possibly correspond to vascular channels in the bone.11 A chevron sign is suspected in the absence of clinical and radiographic signs of endodontic disease; in some cases, however, it is very difficult to differentiate between a chevron sign and pathologic changes.

FIGURE 14. Chevron sign. This radiograph is the lateral view of the right maxillary canine tooth in an 8-year-old dog. Note the wide lucent space at the apex. The lesion is not bulbous, round, or encompassing of the entire apical area, and the lamina dura appears intact. Given the lack of other radiographic indicators of endodontic disease, and in the absence of clinical signs, this finding should not necessarily be considered pathologic.

Other Dental Findings

Tooth resorption may be secondary to inflammatory processes (ie, inflammatory root resorption) or of unknown origin (Figures 15A through 15D).12 Although tooth resorption is often clinically detectable, radiographs are necessary to reveal the actual extent, severity, and radiographic pattern of resorption. The pattern and stage of tooth resorption help determine the surgical approach (ie, extraction or coronectomy), the level of surgical difficulty, and possible complications.13

Figure 15. Tooth resorption. Figure 15A shows advanced inflammatory tooth resorption affecting the left mandibular fourth premolar and first molar teeth in an 8-year-old cat. Figure 15B shows advanced replacement resorption affecting the left and right mandibular canine teeth in a 14-year-old cat. Figure 15C shows replacement resorption affecting both roots of the left mandibular fourth premolar and mesial root of the mandibular first molar in a 7-year-old dog; note the loss of periodontal ligament space and sclerotic alveolar bone around the affected roots. Figure 15D shows inflammatory root resorption secondary to apical periodontitis at the left mandibular canine tooth in a 7-year-old dog; note the irregular and relatively short apical third of the tooth compared to the contralateral.

Caries have not been described in cats, and the prevalence of caries is relatively low in dogs compared to humans. The radiographic appearance of a caries lesion depends on the stage of disease. Very early caries lesions may or not be detectable radiographically. Advanced caries lesions involving the dentin appear as cup-shaped cavitated lesions that may or may not extend into the pulp cavity (Figure 16).

FIGURE 16. Caries lesion. An advanced caries lesion affecting the left maxillary first molar tooth in a 5-year-old dog; note the loss of crown integrity and apical periodontitis secondary to pulp involvement.

Abrasion and attrition are wearing of teeth due to contact with an external object or surface (abrasion) or another tooth (attrition). Radiographically, abrasion and attrition usually appear as even or smooth loss of tooth surfaces of varying severity, often affecting multiple teeth (Figures 17A and 17B). Wear of dental structures can result in damage to the pulp; therefore, clinicians should be attentive to radiographic signs of endodontic disease (see Endodontic Findings).

Figure 17. Abrasion and attrition. Figure 17A shows wear of the occlusal surface of the right mandibular second and third molar teeth in a 6-year-old dog. Figure 17B shows mild wear of the distal aspect of the right mandibular canine tooth in a 6-year-old dog, consistent with cage-biting behavior.

Jaw Structures

Jaw lesions appear on dental radiographs as areas of bone loss of inflammatory, cystic, or neoplastic origin. The bone loss can have a geographic, permeative, or moth-eaten pattern.14 A geographic pattern is characterized by an area of bone loss that is uniform in appearance and has well-defined borders (Figure 18A). In contrast, a permeative pattern of bone loss is an area with poorly defined borders (Figure 18B). Multiple contiguous areas of bone loss with poorly defined borders characterize a moth-eaten pattern.

Figure 18. Bone loss jaw lesions. Figure 18A shows a multilocular lesion of geographic bone loss involving the right mandibular third and fourth premolar teeth in a 5-year-old dog. Figure 18B shows extensive permeative bone loss affecting both rostral mandibles in a 15-year-old cat.

Maxillomandibular fractures may be detected on dental radiographs (Figure 19). However, patients that have sustained maxillofacial trauma often have multiple injuries that are not detectable radiographically; therefore, computed tomography (CT) is the imaging modality of choice to detect mandibular and/or maxillary fractures.15

FIGURE 19. Mandibular fracture. This radiograph shows a comminuted mid-body fracture between the left mandibular third and fourth premolar teeth in an 8-year-old dog.

Symphyseal separation may be observed if the fibrocartilaginous fibers at the symphysis have been stretched or torn as a result of trauma. The symphyseal space may appear wider than usual and an occlusal discrepancy between the right and left incisor teeth may be observed (Figure 20).

FIGURE 20. Symphyseal separation. This radiograph shows an abnormally wide space at the symphysis of a 2-year-old dog consistent with symphyseal separation.

Limitations of Dental Radiography

Dental radiographs have some limitations and disadvantages compared with other modalities. For instance, unlike advanced imaging modalities (eg, CT, cone-beam CT), dental radiographs represent 2-dimensional images of 3-dimensional structures. Given the anatomic complexity of certain areas (eg, caudal maxilla) and the level of superimposition of dental and related structures, radiographs may fail to reveal lesions depending on their nature, location, extent, and severity. Moreover, dental radiographs are useful only for imaging teeth and associated structures in the immediate vicinity. They have little or no value for imaging other maxillofacial structures.

In cases of maxillofacial trauma, temporomandibular joint disorders, and neoplasia of the head and neck (including oral tumors), CT (multislice or cone-beam CT) may be indicated.14–16 If a CT scan of the head is already available, dental radiographs may not be necessary to detect radiographic signs of periodontitis or endodontic disease.17 Cone-beam CT has been proposed as a valid imaging modality for the diagnosis of dental disease in animals, but its precise clinical applications and limitations have not been systematically investigated.18

Dental radiography has traditionally been, and still is, considered the gold standard for the diagnosis of dental disease in dogs and cats. In a general practice setting, its diagnostic value and the relatively low cost of required equipment make dental radiography the most practical imaging modality.

References

  1. Eisner ER. Standard of care in North American small animal dental service. Vet Clin North Am Small Anim Pract 2013;43:447-469.
  2. Holmstrom SE, Bellows J, Juriga S, et al. 2013 AAHA dental care guidelines for dogs and cats. JAAHA 2013;49:75-82.
  3. Verstraete FJ, Kass PH, Terpak CH. Diagnostic value of full-mouth radiography in dogs. Am J Vet Res 1998;59:686-691.
  4. Verstraete FJ, Kass PH, Terpak CH. Diagnostic value of full-mouth radiography in cats. Am J Vet Res 1998;59:692-695.
  5. Shabestari L, Taylor G, Angus W. Dental eruption pattern of the beagle. J Dent Res 1967;46:276-278.
  6. Wiggs RB, Lobprise HB. Veterinary Dentistry: Principles and Practice. Lippincott-Raven Publishers, 1997.
  7. Verstraete FJ, Zin BP, Kass PH, et al. Clinical signs and histologic findings in dogs with odontogenic cysts: 41 cases (1995-2010). JAVMA 2011;239:1470-1476.
  8. Fulton AJ, Fiani N, Verstraete FJ. Canine pediatric dentistry. Vet Clin North Am Small Anim Pract 2014;44:303-324.
  9. Fiani N, Arzi B. Diagnostic imaging in veterinary dental practice. JAVMA 2009;235:271-273.
  10. Carle DS, Shope BH. Diagnostic imaging in veterinary dental practice. JAVMA 2012;241:1283-1285.
  11. DuPont GA, DeBowes LJ, eds. Atlas of Dental Radiography in Dogs and Cats. St. Louis, MO: Saunders Elsevier; 2009.
  12. Peralta S, Verstraete FJ, Kass PH. Radiographic evaluation of the types of tooth resorption in dogs. Am J Vet Res 2010;71:784-793.
  13. Peralta S, Verstraete FJ, Kass PH. Radiographic evaluation of the classification of the extent of tooth resorption in dogs. Am J Vet Res 2010;71:794-798.
  14. Amory JT, Reetz JA, Sanchez MD, et al. Computed tomographic characteristics of odontogenic neoplasms in dogs. Vet Radiol Ultrasound 2014;55:147-158.
  15. Bar-Am Y, Pollard RE, Kass PH, et al. The diagnostic yield of conventional radiographs and computed tomography in dogs and cats with maxillofacial trauma. Vet Surg 2008;37:294-299.
  16. Arzi B, Cissell DD, Verstraete FJ, et al. Computed tomographic findings in dogs and cats with temporomandibular joint disorders: 58 cases (2006-2011). JAVMA 2013;242:69-75.
  17. Campbell RD, Peralta S, Fiani N, Scrivani PV. Comparing intraoral radiography and computed tomography for detecting radiographic signs of periodontitis and endodontic disease in dogs: an agreement study. Front Vet Sci 2016;3.
  18. Soukup JW, Drees R, Koenig LJ, et al. Comparison of the diagnostic image quality of the canine maxillary dentoalveolar structures obtained by cone beam computed tomography and 64-multidetector row computed tomography. J Vet Dent 2015;32:80-86.
  19. Tsugawa AJ, Verstraete FJ. How to obtain and interpret periodontal radiographs in dogs. Clin Tech Small Anim Pract 2000;15:204-210.
  20. Lommer MJ, Verstraete FJ, Terpak CH. Dental radiographic technique in cats. Compend Contin Educ Pract Vet 2000;22:107-116.
  21. Floyd MR. The modified Triadan system: nomenclature for veterinary dentistry. J Vet Dent 1991;8:18-19.

Notes on Images

All radiographic images provided are representative examples that support the explanations presented in the article. They are displayed based on labial mounting and considered to be of diagnostic quality. Some of the images have been cropped, but the structures of interest have not been altered or enhanced.

All images were acquired following standard technique for small animals19,20 using a commercially available dental radiography unit (Heliodent DS, Sirona, Bensheim, Germany) and a computerized radiographic processor using phosphor plates of size 0, 2, or 4 with corresponding software (CS7600, Carestream, Rochester, NY). Due to space limitations, most radiographs shown are from dogs.

In case some readers are unfamiliar with other accepted systems (ie, modified Triadan), anatomic dental nomenclature is used here.21 For more information, interested readers are encouraged to consult a more specialized source.

The College of Veterinary Medicine at Cornell University (CVM) owns and retains the copyrights to all images. The CVM grants permission to use the provided images within the context of the articles titled Interpretation of Dental Radiographs in Dogs & Cats – Part 1: Principles & Normal Findings and Interpretation of Dental Radiographs in Dogs & Cats – Part 2: Normal Variations and Abnormal Findings.

Santiago Peralta, DVM, DAVDC, is an assistant professor of dentistry and oral surgery at Cornell University College of Veterinary Medicine. His clinical and research interests include the microbial pathogenesis of dental diseases, comparative aspects of maxillofacial birth defects, comparative aspects of maxillofacial imaging, and molecular mechanism of oral tumor formation in dogs and cats. Dr. Peralta received his DVM from Universidad de La Salle in Bogota, Colombia, and completed a 3-year residency in dentistry and oral surgery at the University of California, Davis.

 

Nadine Fiani, BVSc, DAVDC, is an assistant clinical professor of dentistry and oral surgery at Cornell University College of Veterinary Medicine. She has an interest in education and a clinical interest in endodontics and zoo dentistry. Dr. Fiani received her veterinary degree from the University of Sydney and completed a rotating internship followed by a 3-year residency in dentistry and oral surgery at the University of California, Davis. Before her current position, Dr. Fiani spent 3 years in private referral practice in Sydney.

 


Interpretation of Dental Radiographs in Dogs & Cats Part 2: Normal Variations and Abnormal Findings

Learning Objectives

After reading this article, clinicians should be able to:

  • Identify the radiographic features of normal variations and abnormal findings when reviewing dental radiographs in dogs and cats
  • Describe the diagnostic advantages and limitations of dental radiography

Overview

This article is the second of two articles that focus on interpretation of dental radiographs in dogs and cats. It includes normal dental variations and pathologic findings that can be viewed on dental radiographs.

The article you have read has been submitted for RACE approval for 1 hour of continuing education credit and will be opened for enrollment when approval has been received. To receive credit, take the approved test online at vetmedteam.com/tvp.aspx A $5 fee applies. Questions and answers online may differ from those below. Tests are valid for 2 years from the date of approval.

  1. What does the radiograph below show? 

A. Persistent deciduous premolar teeth in a dog

B. Retained deciduous premolar and molar teeth in a dog

C. Persistent deciduous premolar and molar teeth in a dog

D. Retained deciduous premolar teeth in a dog

  1. Which of the following statements is true about retained teeth?

A. They represent an incidental finding during oral examination.

B. They cannot be detected radiographically.

C. They are associated with dentigerous cyst formation.

D. They usually involve deciduous teeth.

  1. When is the term hypodontia applicable?

A. The teeth present are abnormally small.

B. Several teeth are missing.

C. Only a few teeth are present.

D. Deciduous teeth persist after normal exfoliation times.

  1. True or false: The amount of calculus detected clinically and radiographically is an excellent indicator of the severity of periodontal disease.

 

  1. Which of the following are visible on the radiograph below? 

A. Severe horizontal bone loss

B. Periodontal–endodontic lesions

C. Furcation exposure and/or involvement

D. All of the above

  1. Which of the following is true regarding the pulp cavity of a nonvital tooth?

A. It becomes progressively wider due to internal resorption.

B. Its width remains static while the pulp cavity of vital teeth progressively narrows.

C. It becomes progressively narrower due to tertiary dentin formation.

D. None of the above

  1. Which radiographic sign is not indicative of endodontic disease?

A. Chevron sign

B. Periapical lucency

C. Inflammatory root resorption

D. Relatively wide pulp cavity

  1. True or false: Pulp exposure is a clinical but not a radiographic finding.

 

  1. True or false: Tooth resorption occurs in cats but not in dogs.

 

  1. Which is the imaging modality of choice in cases of maxillofacial trauma?

A. Intraoral radiography

B. Conventional radiography

C. Magnetic resonance imaging (MRI)

D. Computed tomography (CT)

Note

Questions online may differ from those here; answers are available once CE test is taken at vetmedteam.com/tvp.aspx. Tests are valid for 2 years from date of approval.

 

 

 

The post Imaging Essentials: Interpretation of Dental Radiographs in Dogs and CatsPart 2: Normal Variations and Abnormal Findings appeared first on Today's Veterinary Practice.


Today’s Veterinary Practice and Banfield Pet Hospitals (banfield.com) have partnered together to bring you Pet Health by the Numbers. This column provides clinically relevant statistics extracted from medical record data of nearly 2.5 million dogs and nearly 500,000 cats presented to more than 920 Banfield Pet Hospitals in 2015.

February is National Pet Dental Health Month and, in honor of this important initiative, this column features statistics on the prevalence of periodontal disease in dogs presented to Banfield Pet Hospital in 2015. Read this issue’s dental articles, Interpretation of Dental Radiographs in Dogs & Cats and Chronic Feline Gingivostomatitis: Proven Therapeutic Approaches & New Treatment Options.

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Reference

  1. Wolf HF, Rateitschak EM, Rateitschak KH, et al. Color Atlas of Dental Medicine: Periodontology, 3rd ed. Stuttgart: Georg Thieme Verlag, 2005.

The post Pet Health By the NumbersCanine Periodontal Disease appeared first on Today's Veterinary Practice.

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Santiago Peralta, DVM, DAVDC, and Nadine Fiani, BVSc, DAVDC, Cornell University

Dental radiography is considered part of the standard of care for dogs and cats undergoing dental intervention.1,2 Radiographs are essential for identifying and documenting the nature and severity of dental disorders and conditions.3-5 Dental radiographs often reveal relevant clinical information that would be missed based solely on an oral examination (ie, visual examination and periodontal probing), underscoring the critical role of radiographs as part of a systematic diagnostic approach.4,5

QUALITY OF RADIOGRAPHS

The diagnostic quality and potential utility of dental radiographs are influenced by many factors, including:6,7

  • Patient positioning
  • Radiographic projections
  • Radiographic exposure time
  • Quality of processing.

All of these purely technical aspects of radiography can be optimized by following standard procedures, as have been described elsewhere.7,8 Diagnostic-quality radiographs can be achieved with relative ease via proper training, practice, and experience. Specialized equipment is also required, including a dental X-ray generator and an analog or computerized dental radiograph processing system.9

Normal radiographic findings are defined as those consistent with what is considered typical, average,
or expected and are free of any indicators of disease.

Normal variations are defined as radiographic findings that deviate from what is considered typical, average, or expected but that would not otherwise indicate any preventive or therapeutic medical or surgical intervention, monitoring, or maintenance recommendations.

Abnormal radiographic findings are any findings considered pathologic.

DIAGNOSTIC POTENTIAL

From a purely medical perspective, it is the clinician’s ability to identify lesions of potential clinical interest and interpret them in the context of the individual patient’s signalment, history, and clinical findings, which ultimately leads to an accurate diagnosis and adequate treatment planning.

Proper dental radiographic interpretation requires knowledge of normal anatomic structures and a solid understanding of the pathogenic mechanisms involved with dental diseases, disorders, and conditions that affect dogs and cats. This article describes the most basic skills and knowledge required for radiographic interpretation, as well as the radiographic characteristics of teeth and surrounding tissues and structures during health and disease.

Interpretation of Dental Radiographs in Dogs & Cats

Part 1 of this article series:

  • Describes appropriate mounting and display of radiographic films/plates for reviewing purposes
  • Explains a recommended workflow to review radiographs and record findings
  • Presents radiographic examples of normal relevant structures.

Part 2 focuses on common normal radiographic variations, as well as abnormal findings, including explanations of the underlying disease processes when pertinent, comments on the diagnostic limitations of dental radiography, and current imaging alternatives.

The articles in this series assume the reader is familiar with basic dental radiographic acquisition techniques, concepts, and skills.

ORIENTING & MOUNTING DENTAL RADIOGRAPHS

Dental radiographic interpretation starts with the correct display and mounting of the images. Radiographs are typically obtained intraorally, although some clinicians prefer an extraoral view when imaging the maxillary premolar/molar region in cats (Figure 1).

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Figure 1. Intraoral radiograph (A) of the right maxillary premolar and molar teeth in a 5-year-old cat; extraoral radiograph (B) showing the same teeth in 3-year-old cat. The dotted lines show the trajectory of the zygomatic arches on both radiographs, illustrating how more superimposition with structures of interest occurs in the intraoral view than in the extraoral view.

Display

Whether using films or plates, ensure that the radiograph is displayed on the correct side.

With film, a raised dot (or bubble) can be observed or felt with the fingers at one of its corners. Except when using extraoral technique, this dot marks the plate’s exposed side; it should be on the top side when viewing the film.

With computerized systems, the image usually is displayed automatically on the computer screen in the way it was exposed. However, care must be taken not to accidentally invert the radiograph (most software programs have this function) because the mirror image created may be confused as a radiograph from the opposite side of the mouth (Figure 2).

Because the dental radiographic software assumes the radiographs are obtained intraorally, the only time a radiograph should be inverted intentionally is when an extraoral projection is used.

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FIGURE 2. Lateral intraoral radiograph (A) of the right maxillary canine tooth in an 8-year-old dog; the radiograph is oriented properly based on dental radiographic viewing standards. Mirror image (B) of the same tooth that would be confused as the left maxillary canine tooth based on its orientation.

Mounting

In the majority of patients, a full-mouth study is obtained preoperatively; individual images are usually obtained only under specific circumstances (eg, during/after surgery, for follow-up studies of individual teeth).

The total number of radiographs may range from 10 to 20, depending on size of the animal, but the images are always displayed based on labial mounting (Figure 3). Labial mounting consists of organizing images with the:

  • Maxillary radiographs shown on the upper half of the study
  • Mandibular radiographs on the lower half
  • Radiographs of the patient’s right side on the left
  • Radiographs of the patient’s left side on the right.

The first step when mounting is to determine whether the radiographs correspond to maxillary or mandibular dentition and rotate them as needed, with the maxillary teeth pointed downward and mandibular teeth pointed upward. Identifying structures unique to the maxilla or mandible assists the process:

  • The presence of the palatine fissures and/or nasal turbinates, or the characteristic shapes, size, and number of roots of the maxillary fourth premolar and molar teeth, identify radiographs of maxillary teeth.
  • In contrast, presence of the mandibular symphysis, mandibular canal, mental foramina, or ventral mandibular cortex, or the characteristic shapes, size, and number of roots of the mandibular first, second, and third molar teeth, indicates mandibular dentition.

The next step is to assign radiographs to the left, center, or right of the study. Initially, the two occlusal radiographs (ie, one maxillary, one mandibular) are placed in the center. For all other radiographs, the dentition present is identified in order to place the film/plate on the side in which the mesial teeth are located closer, and the distal teeth farther, to the occlusal radiograph.

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FIGURE 3. Labially mounted full-mouth radiographic study from a 5-year-old dog. The maxillary (Max) teeth are displayed on the upper half, and the mandibular (Mand) teeth are displayed on the lower half. The letters R and L indicate the right and left sides, respectively.

RECOMMENDED WORKFLOW

Once the full-mouth study is mounted properly, the radiographs are ready for review. Radiographs usually are reviewed twice.

The first review occurs during the treatment planning stage, usually while the patient is under general anesthesia (Figure 4). The ideal time for review is after dental charting has been completed and the animal is receiving complete periodontal treatment (ie, supra- and subgingival ultrasonic scaling with or without hand scaling) prior to any surgical intervention as indicated by clinical and radiographic findings (eg, extractions, biopsy, periodontal surgery, endodontic therapy).

This initial radiograph review should be performed in the context of the oral examination findings that were recorded in the patient’s chart. This allows the clinician to establish a tooth-by-tooth diagnosis and decide whether disease is present and, if so, which treatment is indicated.

A second and more meticulous review is recommended to allow a detailed radiographic report to be written and incorporated into the patient’s medical record. This can be done after the procedure has ended to avoid unnecessarily prolonging the anesthetic event.

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FIGURE 4. The initial dental radiographic review usually occurs in a clinical setting. The clinical findings (dental chart) are compared with the radiographic findings, and a treatment plan is established, usually while the patient is still under general anesthesia.

REVIEWING DENTAL RADIOGRAPHS

To minimize oversight when reviewing radiographs, establish a routine based on both the order in which the radiographs are examined and certain predetermined categories.

A logical sequence is to examine quadrants in the following order:

  • Right maxillary
  • Left maxillary
  • Left mandibular
  • Right mandibular.

For each quadrant, review the most mesial tooth first and the most distal tooth last. Assess each quadrant separately based on the following predetermined clinically and radiographically relevant categories.

Anatomic & Developmental Findings

Assess the presence, number, and relative size, shape, and direction of the teeth and corresponding roots and identify dental tissues, anatomic areas of interest, and surrounding structures. All findings should be interpreted with consideration of the age, size, and breed of the patient.

Two normal developmental processes are relevant when evaluating radiographs: dentin deposition and apex formation.

Dentin deposition begins prior to tooth eruption and, under physiologic conditions, continues throughout the life of each permanent tooth. Any dentin secreted prior to eruption is called primary dentin. Once the tooth erupts, usually with still very thin dentinal walls, all further dentin secretion that occurs under physiologic conditions is called secondary dentin (Figure 5). As the animal ages, more dentin is secreted and the pulp cavity diameter gradually narrows (see Endodontic Findings).

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FIGURE 5. Lateral intraoral radiograph (A) of the left canine tooth in a 6-month-old dog showing a relatively wide pulp cavity (asterisk), relatively thin dentinal walls, and an incompletely formed apex (black arrow). Radiographs (B and C) corresponding to the same projection and tooth in an 11-month-old dog and a 9-year-old dog, respectively. Compare the differences in apex, pulp width, and dentinal wall thickness, as would be expected based on the animals’ ages.

Apex formation (Figure 5) describes eruption of the permanent tooth prior to full formation of the apex. An incompletely formed apex is often referred to as an open apex. Apex formation lasts a few weeks after eruption and is usually complete by the age of 9 months in both cats and dogs.

Finally, distinguish radiographically deciduous from permanent teeth. Deciduous teeth are relatively smaller and less radiodense than permanent teeth. Under normal circumstances based on average eruption times, the term mixed dentition is applied when permanent and deciduous teeth are present simultaneously in the oral cavity (Figure 6).

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FIGURE 6. Mixed dentition in a 6-month-old dog. The full-mouth study shows the simultaneous presence of erupted deciduous and permanent teeth. L = left; Mand = mandibular teeth; Max = maxillary teeth; R = right.

What You Need to Know

To decide whether radiographic findings are normal, the clinician should be familiar with normal:

  • Tooth and root anatomy
  • Tooth and root development stages
  • Deciduous and permanent dentition formulas
  • Normal deciduous tooth exfoliation times
  • Normal dental and maxillofacial anatomy
  • Any pertinent variations among specific breeds.

Periodontal Findings

The attachment apparatus of teeth (periodontium) consists of the gingiva, periodontal ligament (PDL), cementum, and alveolar bone (Figure 7).

Alveolar bone is mineralized and large enough to be seen directly on radiographs. Normal alveolar bone should provide coverage to the entire root(s), and its margin should be located immediately apical to the cementoenamel junction (CEJ) of the tooth. In multirooted teeth, the area between roots (ie, furcation) should be occupied evenly by cancellous bone.

The PDL cannot be seen because it is composed mostly of nonmineralized collagen fibers. Under normal circumstances, however, the space occupied by the PDL can be seen as a relatively narrow, regular, lucent area located between the root(s) and surrounding alveolar bone.

On the osseous side of PDL space, a dense opaque line, referred to as lamina dura, can be traced around all roots. Anatomically, the lamina dura corresponds to the compact bone that normally lines the alveolus.

While cementum is partially mineralized, it is too thin to be discernible on radiographs. Conversely, while gingiva is not usually mineralized, it is thick enough to be visible sometimes on radiographs. If visible, normal gingiva should appear as a subtle soft tissue opacity immediately coronal to the alveolar margin that extends just beyond the CEJ without covering larger areas of the crown.

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FIGURE 7. Normal periodontal and endodontic findings. Lateral intraoral radiograph (A) of the left maxillary tooth in an 8-year-old showing the alveolar margin (black arrowheads) in close proximity to the cementoenamel junction (CEJ; dotted line). The gingiva is visible as a soft tissue opacity (asterisks) along the alveolar margin. The periodontal ligament (PDL) space can be traced around the entire root as a regular and relatively narrow lucent line surrounded by the lamina dura, seen as a thin, opaque line (yellow arrowhead). The apex and periapical structures (dotted red circle) show a normal PDL space. Intraoral parallel view (B) of the caudal mandible in an 8-year-old dog showing the same normal structures as shown in A; note the presence of cancellous bone occupying the entire furcation areas of the first and second molar teeth (black arrows).

Endodontic Findings

The structures of interest when evaluating the endodontic status of teeth are the pulp cavity, apex, and periapical tissues (Figures 7–10). The integrity of each crown and root is also assessed.

The pulp cavity—the entire area occupied by the pulp—is divided into three distinct areas: pulp chamber, root canal, and pulp horns in multirooted teeth. As noted, the width of the pulp cavity of permanent teeth decreases with age. Because this process occurs bilaterally at similar rates, no pulp cavity width discrepancies should be noted when comparing endodontically normal teeth with their contralateral counterparts (Figures 8–10).

The apex refers to the most distal third portion of the root and is the location of the apical delta.

The periapical tissues—the PDL space surrounding the apex and the tissues in its immediate vicinity—should be normal. That is, the width of the PDL space in this area should be consistent with the width of the PDL space on the sides of the root, and no evidence of bone lysis affecting the bone periapically should be present.

Finally, root length and appearance of an endodontically normal tooth should be similar to those of its contralateral counterpart.

The clinician should always scrutinize the radiographs of areas in which teeth are missing to rule out the presence of retained roots. However, the clinician must be aware that endodontically diseased teeth sometimes appear radiographically normal.

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FIGURE 8. Occlusal mandibular radiograph in a 7-year-old dog showing a normal mandibular symphysis (arrowheads). Note the symmetric diameter of the pulp cavity at the left and right canine teeth (asterisks). The clinical examination revealed periodontally sound mandibular incisors; despite this, note that the alveolar margin is located apical to the cementoenamel junction at all mandibular incisors.

Determining What Constitutes Normal

Because radiographs are two-dimensional images often representing complex anatomic structures, care must be taken not to under- or overestimate what may constitute normal findings.

CEJ and canine alveolar margins: In some cases, additional projections of the same tooth may be necessary. A relevant example is the occlusal view of canine teeth. Because the distance between the CEJ and alveolar margin of canine teeth cannot be established easily on an occlusal projection, a lateral radiograph is necessary to document the periodontal status more accurately (Figure 7 and Figure 9).

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FIGURE 9. Intraoral occlusal maxillary radiograph in a 6-year-old dog illustrating the difficulty in assessing the periodontal status (ie, distance between the alveolar margin and CEJ) at the canine teeth (white arrowheads). Note that the pulp cavities of both canine teeth are of similar diameter, which is expected in endodontically healthy teeth, as well as the normal turbinate pattern present in the nasal cavity.

CEJ and incisor alveolar margins: In contrast, the periodontal status of the mandibular incisors in dogs does not always correlate with clinical findings and can be overestimated easily. Namely, the radiographs of clinically normal incisors (ie, no mobility, increased probing depth, or gingival recession) often reveal an apparently increased distance between the CEJ and alveolar margin (Figure 8).

In all of these cases, always correlate clinical and radiographic findings prior to establishing a diagnosis and/or making any clinical decisions.

Other Findings

With regard to teeth, other findings usually include those that do not fit into any of the above categories. Because these findings typically correspond to either normal variations or pathologic findings, however, representative examples will be presented in Part 2.

Several non-dental structures are visible on dental radiographs that could potentially reveal abnormalities or disease. Therefore, the clinician should be familiar with the normal radiographic appearance of these structures.

Nasal Cavity

The nasal cavity is viewed on maxillary occlusal radiographs (Figure 9). Under normal circumstances, the following should be present:

  • Well-defined turbinate pattern
  • Relatively symmetric separation of right and left cavities by vomer and septum
  • Palatine fissures clearly visible as two distinct lucent round or oval-shaped structures caudal to the maxillary incisor teeth.

Mandibular Structures

A normal mandibular symphysis appears radiographically as a relatively narrow lucent line that joins the two mandibles at the midline, with the right and left mandibular incisors in symmetric occlusion. The mandibular symphysis can be relatively linear, although in cats it follows more of a zigzag pattern (Figures 8 and 10).

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FIGURE 10. Occlusal mandibular radiograph in a 4-year-old cat showing symmetric diameter in pulp cavity width at both canine teeth (asterisks) and the typical zigzag appearance of the mandibular symphysis (arrowheads).

The mandibular bodies should also be assessed. Despite some degree of variability among dog breeds with regard to shape and relative size, the mandibular canal should be visible as a relatively lucent linear structure occupying the middle and/or ventral third of the mandibular body (Figure 11).

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FIGURE 11. Intraoral parallel radiographs showing the normal appearance of the mandibular canal in the caudal mandibular body area. Note the relative position and size of the associated roots in an 8-year-old small dog (A), 4-year-old large dog (B), 12-year-old cat (C), and 7-year-old medium-sized dog (D).

In cats and medium- to large-breed dogs, the roots of the mandibular premolar and molar teeth are located in the area most dorsal to the canal; in small dogs, the roots of the mandibular fourth premolar and first molar teeth extend into and/or beyond the canal and, in some cases, to the level of the ventral cortex of the mandible.

To avoid misinterpreting them as pathologic findings, note the appearance and typical location of the middle and caudal mental foramina. These structures are usually well defined radiographically and appear as round or oval-shaped lucencies ventral to the first and/or second mandibular premolar teeth and third and/or fourth mandibular premolar teeth, sometimes overlapping with the apex of one of the roots (Figure 12).

The most caudal areas of the mandibular body and the ramus are not visible on dental radiographs. Other imaging modalities should be considered, if medically indicated.

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FIGURE 12. Intraoral radiograph of the rostral mandibular premolar area showing the middle and distal mental foramina (arrows).

Temporomandibular Joint

The use of dental films for extraoral imaging of the temporomandibular joint has been described;10 however, examples are not included in this article because the diagnostic yield is poor, especially compared with advanced imaging modalities, and imaging of this structure is beyond what is considered dental radiography.

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References

  1. Eisner ER. Standard of care in North American small animal dental service. Vet Clin North Am Small Anim Pract 2013; 43:447-469.
  2. Holmstrom SE, Bellows J, Juriga S, et al. 2013 AAHA dental care guidelines for dogs and cats. JAAHA 2013; 49:75-82.
  3. Lommer MJ, Verstraete FJ. Radiographic patterns of periodontitis in cats: 147 cases (1998-1999). JAVMA 2001; 218:230-234.
  4. Verstraete FJ, Kass PH, Terpak CH. Diagnostic value of full-mouth radiography in dogs. Am J Vet Res 1998; 59:686-691.
  5. Verstraete FJ, Kass PH, Terpak CH. Diagnostic value of full-mouth radiography in cats. Am J Vet Res 1998; 59:692-695.
  6. Lemmons M. Clinical feline dental radiography. Vet Clin North Am Small Anim Pract 2013; 43:533-554.
  7. Tsugawa AJ, Verstraete FJ. How to obtain and interpret periodontal radiographs in dogs. Clin Tech Small Anim Pract 2000; 15:204-210.
  8. Lommer MJ, Verstraete FJ, Terpak CH. Dental radiographic technique in cats. Comp Cont Educ Pract Vet 2000; 22:107-116.
  9. Coffman CR, Brigden GM. Oral and dental imaging equipment and techniques for small animals. Vet Clin North Am Small Anim Pract 2013;43:489-506.
  10. DuPont GA, DeBowes LJ, (eds). Temporomandibular joint. In Atlas of Dental Radiography in Dogs and Cats. Saint Louis, MO: Saunders Elsevier, 2009, pp 122-133.
  11. Lommer MJ, Verstraete FJ, Terpak CH. Dental radiographic technique in cats. Compend Contin Educ Pract Vet 2000; 22:107-116.
  12. Floyd MR. The modified Triadan system: Nomenclature for veterinary dentistry. J Vet Dent 1991; 8:18-19.
  13. White SC, Pharoah MJ (eds). Oral Radiology: Principles and Interpretation. 6th ed. St. Louis: Mosby/Elsevier, 2009.

Notes on Images

All radiographic images are representative examples that support the explanations presented in the article. They are displayed based on labial mounting and considered to be of diagnostic quality. Some of the images have been cropped, but the structures of interest have not been altered or enhanced in any way.

All images were acquired following standard technique for small animals7,11 using a commercially available dental X-ray unit (Heliodent DS, Sirona, Bensheim, Germany) and a computerized radiographic processor using phosphor plates of size 0, 2, or 4 with corresponding software (CS7600, Carestream, Rochester, NY). Due to space limitations, most radiographs shown are from dogs, but radiographs from cats are included if a feline-specific point needs to be made.

In case some readers are unfamiliar with other accepted systems (ie, modified Triadan), anatomic dental nomenclature is used here.12 For more information, interested readers are encouraged to consult a more specialized source.13

The College of Veterinary Medicine at Cornell University (CVM) owns and retains the copyrights to all images. The CVM grants permission to use the provided images within the context of the articles titled Interpretation of Dental Radiographs in Dogs & Cats – Part 1: Principles & Normal Findings and Interpretation of Dental Radiographs in Dogs & Cats – Part 2: Abnormal Findings.

 

author_s-peralta

Santiago Peralta, DVM, DAVDC, is an assistant professor of dentistry and oral surgery at Cornell University College of Veterinary Medicine. His clinical and research interests include the microbial pathogenesis of dental diseases, comparative aspects of maxillofacial birth defects, comparative aspects of maxillofacial imaging, and molecular mechanism of oral tumor formation in dogs and cats. Dr. Peralta received his DVM from Universidad de La Salle in Bogota, Colombia and completed a 3-year residency in dentistry and oral surgery at the University of CaliforniaDavis.

 

author_n-fiani

Nadine Fiani, BVSc, DAVDC, is an assistant clinical professor of dentistry and oral surgery at Cornell University College of Veterinary Medicine. She has an interest in education and a clinical interest in endodontics and zoo dentistry. Dr. Fiani received her veterinary degree from the University of Sydney and completed a rotating internship followed by a 3-year residency in dentistry and oral surgery at the University of California Davis. Prior to her current position, Dr. Fiani spent 3 years in private referral practice in Sydney.

 

 

Interpretation of Dental Radiographs in Dogs & Cats
Part 1: Principles & Normal Findings

Learning Objectives

After reading this article, clinicians should:

  • Recognize the importance of appropriately mounting and displaying dental radiographic films/plates for review and interpretation purposes
  • Understand how to establish a reproducible workflow to review and record pertinent findings systematically
  • Be able to describe how normal dental and associated structures appear radiographically.

Overview

This article is the first of two articles that focus on interpretation of dental radiographs in dogs and cats. It includes basic principles of dental radiographic interpretation and describes normal radiographic findings.

This article is RACE-approved for 1 hour of continuing education credit. To receive credit, take the approved test online at vetmedteam.com/tvp.aspx (CE fee of $5/article).

 

1. Choose the most appropriate orientation for the radiograph shown below.

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A. Rotate the image 90 degrees clockwise.

B. Rotate the image 180 degrees.

C. Rotate the image 90 degrees counterclockwise.

D. The image should remain as it is.

 

2. What structure does the radiograph in Question 1 show?

A. Right maxillary canine tooth

B. Left maxillary canine tooth

C. Left mandibular canine tooth

D. Right mandibular canine tooth

 

3. Which of the following statements about dental radiography in dogs and cats is TRUE?

A. Full-mouth radiographic studies are not recommended.

B. Radiographs are not necessary if dental charting was performed.

C. Dental radiographs are by definition always obtained intraorally.

D. Radiographs and dental charting are both necessary to establish a diagnosis and treatment plan.

 

4. From what type of animal was the following radiograph most likely obtained?

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A. 6-month-old dog

B. 6-year-old dog

C. 12-year-old dog

D. Cannot determine based on the image

 

5. What type of radiograph is shown in Question 4?

A. Standard extraoral view of the rostral maxilla

B. Standard occlusal radiograph of the mandible

C. Standard occlusal view of the maxilla

D. Cannot determine based on the image

 

6. Assuming both are appropriately displayed (ie, based on labial mounting), which of the following images corresponds to the left mandibular molar/premolar teeth?

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A. Top image

B. Bottom image

C. Neither

D. Both

 

7. What structures are part of the periodontium?

A. Gingiva, apical delta, cementum, periodontal ligament

B. Gingiva, pulp, cementum, periodontal ligament

C. Gingiva, alveolar bone, cementum, periodontal ligament

D. None of the above

 

8. What is the area occupied by the dental pulp and surrounded by dentinal walls?

A. Root canal

B. Pulp cavity

C. Pulp canal

D. Pulp chamber

 

9. What are the radiographic areas of interest when evaluating the endodontic status of a tooth?

A. Integrity of the crown and root

B. Relative pulp cavity width

C. Periapical structures

D. All of the above

 

10. Which of the following cannot be assessed using standard dental radiographic technique?

A. Mandibular ramus

B. Alveolar bone height relative to the cementoenamel junction

C. Mandibular body

D. Mandibular symphysis

Note

Questions in the journal may differ from those here; answers are available once CE test is taken at vetmedteam.com/tvp.aspx. Tests are valid for 2 years from date of approval.

 

The post Imaging EssentialsInterpretation of Dental Radiographs in Dogs & CatsPart 1: Principles & Normal Findings appeared first on Today's Veterinary Practice.

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