Marine Mammal Dentistry & Oral Health Flashcards
Describe the dental anatomy of marine mammals.
What is unique about sea lion teeth?
What is unique about walrus tusks? What type of modified tooth are they?
What type of modified tooth are narwhal tusks?
Anatomical descriptions and dental formulas
- Pinniped maxillary and mandibular anatomy, depicted below (black coloration is normal)
- Tooth anatomy involves enamel, dentin, pulp, periodontal ligament holding it in the alveolus
- Apex of the tooth is the deepest part of the root with blood vessels and nerves
- Walrus tusks (maxillary canines) have an open apex and are continuously growing
- In general the bone of marine mammals is heavier and denser than terrestrial mammals, making some procedures more difficult
- Most species lose deciduous teeth in utero or shortly after birth
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Cetaceans are homodont, pinnipeds are heterodont
- Premolars and molars are so similar in california sea lions that they are commonly all called “postcanines”
- Narwhal tusks are modified canines
- Dental formulas of common species are listed below
What are the dental formulas of the following marine mammals?
Bottlenose dolphins
Killer whales
Walrus
Harbor Seal
California Sea Lion
Southern sea otter
Walrus
Supernumerary teeth are common in what marine mammal?
Periodontal disease is common in what marine mammal?
Tooth resorption is common in what marine mammal?
When should extraction or root canal be considered for tooth fractures?
Diseases
Missing teeth
- This can occur because they were never formed, were retained in bone, or were avulsed
- In some species, the high frequency of missing teeth makes establishing a true dental formula problematic
- Teeth retained in bone can form dentigerous cysts and should be extracted
Supernumerary teeth
- very common in california sea lions
Periodontal disease
- 4 stages of disease severity
- Prevalence of periodontal disease is high in sea otters and polar bears
- Prevention is the best treatment
Tooth resorption
- In many species of delphinidae, tooth resorption has been described as a caries-like lesion
- Prevalence varies by species
- Radiographic evaluation is recommended
Tooth fractures
- No treatment necessary if the pulp is not exposed, but intraoral rads are recommended to assess plp involvement or development of fistulas
- In the case of a complicated crown fracture, extraction or root canal is indicated
- Complicated crown-root fractures should be treated similarly
- Root fracture, if deep enough may be left alone as the gingiva will grow rapidly to cover it
Describe the evaluation of dental radiographs in marine mammals.
What would you see with a healthy young animal versus a healthy older animal?
What about in periodontal disease?
What about with endodontic disease?
What about tooth resorptions?
Digital intraoral radiology
- Helpful aid to the oral exam
- Some animals can be trained to hold the plate in their mouth voluntarily, so some images can be taken awake
- Standard techniques apply
Radiographic interpretation
- Normal young patient
- Dentinal wall is thin and the pulp chamber is large
- Apex may be open
- Normal older animal
- Decreased or absent canal and increased dentinal wall thickness
- Apical foramen usually not visible
- Periodontal disease
- Rounding and loss of alveolar crest
- Subgingival calculus
- Endodontic disease
- Lucency around the apex of the tooth root, resorption of the tooth root internally or externally, fractures seen above or below the gingiva
- Tooth resorption
- Range from barely visible coronal lucency to total resorption
- Retained roots may be seen
Describe the treatments for fractured teeth in marine mammals.
What are the pros and cons of each?
Treatments for fractured teeth
- Endodontics
- Root canal - removal of the pulp chamber contents and filled with an inert substance
- Advantage is that it is less traumatic than surgical extraction and alignment is maintained
- Exodontics
- Extraction
- Can be difficult in some of the larger marine mammals, but large elevators and other instruments are commercially available
- Should have: elevators, luxators, extraction forceps, magnifications and lighting
- Extraction techniques
- Most can be extracted with elevation or creation of a surgical flap
- Usually easier to split multiroot teeth before extraction
- Standard techniques, nothing marine mammal specific
Describe the dentition of marine mammals.
What is odontocete teeth like?
- How does dolphin dentition compare to porpoise dentition.
What is sirenian dentition like?
- How many teeth do they have?
- How many do they have throughout their lives?
- How does that differ in manatees vs dugongs?
- What teeth make up the dugong tusks?
What is pinniped dentition like?
- How does that differ in walruses?
- What teeth make up the walrus tusks?
Odontocete dentition
* Single set of interlocking teeth
* Not continuously growing once mature
* Undifferentiated in form (single tooth type)
* Conical with long single roots
* Porpoises = spade shaped
Sirenian dentition
* Occlusive flattened molars replaced through sequential eruption (move forward as new ones erupt from back, front are lost
* Similar to elephants
* Both manatees and dugongs have 6 teeth per quadrant BUT
* Manatees have up to 40 molars per quadrant erupting sequentially throughout lives
* Dugongs have only 6 in each quadrant throughout lives
* Male dugongs also have incisor tusks
Pinniped dentition
* Monophyodont, terrestrial carnivore-like
* EXCEPT walrus → 4 cylindrical dentine pegs as cheek teeth in each quadrant and large upper canine tusks (males and females)
* Tooth size varies
Describe treatment of odontocete dental disease.
What is the most common pathology in cetaceans?
What is the underlying pathophysiology that make their teeth susceptible?
What are the two routes of managing dental disease in these animals?
What dental blocks can be performed in cetaceans?
Describe surgical extraction.
How does management differ in orcas?
Odontocete Dental Disease
* Trauma
– Primary cause = chewing on hard substrates/enrichment
– Chronic regurgitation → high pH → enamel erosion → dentine erosion → exposure of pulp cavity
* Treatment:
- Endodontic therapy
– Partial coronal pulp therapy > root canal may be better in this spp
– Keeps pulp alive and encourages bridge of tertiary dentine to form
– High failure rate in mature animals due to poor vascular supply
- Once pulp exposure has occurred → extraction
– Most practical and predictable option (little follow up/repeat procedures unlike endodontic therapy)
– Nerve blocks
– Infra-alveolar branch of mandibular nn → only for mandibular teeth and large volume of local anesthetic is needed
– Individual infiltration usually preferred
– Extract through socket → severing periodontal ligament before attempting to remove
– Open surgical extraction not practical, can’t make a flap
– Not usually feasible to extract in killer whales
– Most facilities treat acute dentoalveolar abscesses and perform routine flushing to remove food/bacteria
– Palliative only
Describe the management of dental desease in pinnipeds.
What is the most common cause of dental disease in pinnipeds?
- What teeth are most commonly affected?
- What differentials shoudl be considered?
- How are they treated?
- What considerations need to be made regarding endodontic procedures in pinniped canines?
What is the most common dental pathology in walrus?
- What is the cause of this?
- What is the pathophsyiology of dental abscesses in this sepcies?
- What makes surgery so difficult?
Pinnipeds
* Trauma usually secondary to repeated abrasion rather than single episode of trauma → wear of crowns
* Mandibular teeth more often than maxillary
* Canine most frequent in adults
* In young sea lions rostral and cheek teeth (chewing)
* First sign of perapical abscess will usually be external swelling in young animals
– Ddx - benign incisor development can cause nonpurulent swellings in young animals
* Treatment
– Extraction most practical (teeth not used for mastication, don’t need to catch fish in managed care)
– Open procedure, take care not fracture mandible
– If endodontics elected note that apical foramina of canine teeth have LONG period of maturity (can be >12y) → contraindicated to endodontics and attempts to root-fill
Walrus
* Canine tusks (male and female)
* Common area of fracture in managed care due to use for hauling out
* Natural behavior, but ice is softer than concrete
* Pulp exposure usually does not occur after fx
* Usually see secondary dentine allow bacteria to enter pulp cavity → pulp necrosis → periapical abscess discharges facial through sinus tract rostral to eye
* Prevention via capping tips, but frequently fail
* Some call for removal of tusks “prophylactically” at a young age
* Extraction is difficult and will require open surgery and knowledgeable surgeon
* Frequently removal of portion of maxillary bone required
Describe the oral soft tissue diseases and neoplasms in marine mammals.
What group commonly gets gingivitis?
- What virus is this associated with?
What is the most common oral neoplasm of marine mammals?
Soft Tissue Oral Conditions in Marine Mammals
* Periodontal disease and gingivitis
– Uncommon in cetaceans, otariids
– Sea lions and fur seals have black discoloration secondary to calculus and chromogenic bacteria → not pathological
– Not seen in phocids
* Seals - 2 forms of gingivitis
– Destructive to gingiva and associated with novel phocid herpesvirus (PhHV-7)
– Harbor seals (rescue)
– Self limiting - resolved in ~10d
– Proliferative generalized gingivitis
– More chronic, observed in managed care seals
– Typically no obvious dental plaque/calculi
Oral Neoplasia in Marine Mammals
* oral/genital neoplasia in cetaceans (free ranging and managed care)
* Slow progression from papillomata → carcinoma in situ → SCC
* seals/sea lions - r/o SCC when periodontal dz seen
