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Veterinary Dental Case Study: Intra-oral radiographs to rule out pathology

Posted in Festival of All Things Dental @ Apr 27th 2016 - By Adjunct Associate Professor Anthony Caiafa, North Coast Veterinary Specialists
Im3 Case Study Figure 1 Foster With Left Side Facial Swelling 1

Sometimes, diagnostic tests such as radiographs are taken to rule out pathology rather than to detect it. 

Introduction

A 9 year old desexed male Golden Retriever cross Labrador “Foster” was referred to a Veterinary Specialist Referral Practice with a history of a sudden onset of a firm swelling ventral to the left eye (figure 1 to the right). The dog had a history of occasionally being offered bones to chew as well as playing games of retrieval of large sticks with the owner. The dog had also recently been on a farm with other dogs. Since the swelling had come up, the dog had become slightly lethargic but was still eating but had no pyrexia on presentation to the referring veterinarian. 

The referring veterinarian did not have intraoral radiography capabilities and assuming that the swelling was dental in origin and mostly likely a tooth root abscess involving the maxillary 4th premolar (208) or maxillary 1st molar (209), the veterinarian could only offer the client extraction of one or both teeth. The referring veterinarian did however offer the option of referral to a facility that could take intraoral radiographs and thus determine the origin of the swelling. The client accepted this advice.

Examination (awake) including whole body, extra- and intra-oral examinations

On presentation to the referral practice, the dog appeared well with no raised temperature. The swelling just below the left eye was firm and fixed and the dog resented the mouth and muzzle being handled on that side. There was no pain on opening the mouth.  The left draining mandibular lymph node was slightly enlarged, non- painful on palpation and mobile. A cursory look at the maxillary caudal teeth on the left side revealed no obvious crown fractures. The medical history revealed a long history of atopic dermatitis which had been controlled by cyclosporine (Atopica® capsules, Novartis Animal Health, Australia). 

Since unilateral facial swelling (especially being just ventral to the eye) is often associated with an endodontically involved tooth or teeth and because a concussive or subluxation injury to a tooth does not always lead to crown fracture, but can still cause a pulp to become necrotic, at the top of the differential diagnoses was pulp necrosis due to concussion or subluxation injury of the maxillary 4th premolar (208). The most likely cause was bone, rock or stick chewing. The client was also advised that other causes of the swelling could be due to foreign body penetration, dog fight or considering the age of the dog, a facial tumour was possible.

The dog’s pre-anaesthetic blood analysis was unremarkable and there was no evidence of a white cell elevation or hepatopathy (a known contra-indication for long term cyclosporine use) in the biochemistry results.

Extra- and intra-oral examination under general anaesthesia

Under general anaesthesia, an examination of the facial mass revealed it to be firm and slightly mobile. A fine needle aspiration revealed some whole blood. There was no purulent discharge present in the sample. The draining left mandibular lymph node was slightly enlarged.

An oral examination revealed evidence of abrasive wear of the teeth (rocks, bones, sticks). Periodontal probing depths were generally 4mm or below (normal is <3mm) and there was some evidence of generalised gingival hypertrophy (a known side effect of long term cyclosporine use) (figure 2).

Figure 2 - Cyclosporine induced gingival hypertrophy (mild)There was also a papilloma like mass just dorsal to the left maxillary 3rd premolar (207) (figure 3). Another known side effect of cyclosporine usage is verruciform lesions or papilloma formation.

There was also a papilloma like mass just dorsal to the left maxillary 3rd premolar (207) (figure 3). Another known side effect of cyclosporine usage is verruciform lesions or papilloma formation.

Figure 3: Gingival wart- like lesion LHS apical to tooth 207. Lesion is possibly associated with cyclosporine administration.

Because of the dog’s age, the client requested a whole mouth series of intraoral radiographs to rule out any other oral pathology. A whole mouth series of intra-oral radiographs were taken using a size 4 phosphor storage plate (5.7 x 7.5cm) (Durr CR7, iM3 Inc., Sydney, Australia). Because the dog was a large breed (32Kg), the size 4 plate was ideal for the task and reduced the number of exposures required to do the whole mouth series of radiographs from the usual 10 or sometimes more exposures (with a size 2 film) down to 6 exposures. This helped reduced anaesthesia time, as well as being more diagnostic by covering more of the oral and nasal cavities in the one exposure. Imaging of the left (figure 4) and right caudal maxillae (figure 5) revealed no obvious dental or nasal problems (if in doubt, when faced with unilateral oral disease, radiograph the other side for comparison).

  

Figure 4: LHS Maxilla demonstrating the premolar /molar teeth (teeth 206, 207, 208, 209, 210). There is no dental pathology visible. The caudal extent of the nasal cavity also looks normal. (Size 4 Phosphor Storage plate) 

Figure 5: RHS Maxilla demonstrating the caudal premolar/ molar teeth (teeth 106, 107, 108, 209, 210). (Size 4 Phosphor Storage plate)

Having ruled out an obvious dental cause for the swelling, it was decided to make a small incision into the mass and with a 5mm skin biopsy punch, and take incisional type biopsies of the facial mass (figure 6).

Figure 6: Incisional biopsy including skin and greyish red firm mass

The biopsied tissues were firm and greyish- red in appearance. The oral papilloma type mass apical to the left maxillary 3rd premolar (207) was also excised just in case it was associated with the facial swelling. On biopsy of this wart-like lesion, the lesion disintegrated and revealed a mucous blood tinged discharge. Mosquito forceps were used to enlarge the cavity below the intra-oral lesion and a size 60 gutta percha point was placed into the facial swelling and found to communicate with the intra-oral lesion (figure 7).

Figure 7: A gutta percha point (flexible radio-opaque root canal filling point) is placed into the facial swelling. It is following the path of least resistance (the sinus tract) and is pointing to the LHS Maxillary 3rd premolar (207Exploration of the lesion inside the mouth revealed a small grass seed (figure 8) and this was removed. No other grass seeds were found.

Figure 8: Grass seed foreign body found within the firm facial swelling

A diagnosis of foreign body granuloma was made and the dog was discharged on amoxicillin/ clavulinic acid combination for 7 days. Within 4 days post- surgery, the facial swelling had reduced significantly (>80%) and by 7 days had disappeared and has since not returned. “Foster” is back to his normal self, but is having his teeth brushed regularly to help control plaque accumulation due to the cyclosporine induced gingival hypertrophy.

Different case

For comparison, Figure 9 demonstrates another case involving a dog with true oral disease caused by trauma and pulp necrosis of RHS maxillary 4th premolar (108). 

Figure 9: Apical periodontitis showing a radiolucency involving the distal root apex of tooth 108 (different case). This tooth should be either extracted or root canal treatment performed on it

Conclusions

Sometimes, diagnostic tests such as radiographs are taken to rule out pathology rather than to detect it.

The referring veterinarian was to be commended in referring this case. Years ago, when intra-oral radiographs were not available, unilateral facial swellings were always assumed to be related to dental pathology unless proven otherwise (often belatedly after the tooth had already been extracted). This lead to a number of healthy teeth being extracted without the resolution of the patient’s presenting complaint.

It is my opinion that before too long, a minimum standard of companion animal practice will require veterinarians to either offer intra-oral radiographs to their clients or to refer patients with oral disease to a practice that can offer such a service. It is well accepted that without the use of intra-oral radiography, a number of feline tooth resorptions will be missed and a number of teeth will have fractured roots left behind after extraction, often leaving the patient in continuing pain and discomfort. 

Case study provided by iM3

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