Polar bear root canal is a sedate affair

The Baltimore Sun

Nearly every day in Maryland, people drag themselves to dental specialists to undergo the necessary ordeal of root canal surgery.

But only one was performed yesterday at the Maryland Zoo in Baltimore. And the 500-pound patient was a first, even for veterinary dental surgeon Dr. Ira R. Luskin, who already counts lions and antelopes among his patients.

Anoki, the zoo's 11-year-old female polar bear, slept through the entire two-hour procedure, splayed on her back with a dozen humans poking, prodding and watching her vital signs. She was returned by midafternoon to her Bear Watch habitat, where she awakened with a mended tooth and, it is hoped, a healthier future.

Luskin seemed pleased with the effort, although he wondered how Anoki might see it. "I'm definitely going to stay away from the exhibit for the next year," he quipped.

Anoki arrived at the zoo last summer with a broken lower-left canine, or "fang" tooth.

With the tooth's root canal, nerves and blood supply exposed by the fracture, it soon died. The slender channel filled with food and debris, and infection inevitably set in. It threatened to spread to the jawbone and potentially to her bloodstream and organs.

The problem was caught by the zoo's chief veterinarian, Dr. Ellen Bronson. She spotted signs of infection on X-rays taken during an exam soon after Anoki's arrival in August.

The bear's eating and behavior betrayed nothing out of the ordinary, she said. It is a trait common to many animals, including household pets. Showing signs of distress or pain in the wild can invite predators and a quick death.

"Even a big polar bear, which you would think have no enemies, they don't show it," Bronson said.

Bronson scheduled the surgery for winter to minimize the risk that Anoki would become overheated while under anesthesia.

So, about 10 a.m. yesterday, Anoki was shot with a tranquilizing dart to knock her out. After she was asleep, a breathing tube the size of a vacuum cleaner hose was inserted into her trachea, and she was trucked to the zoo's animal hospital.

With as many as 12 handlers lifting and shoving, she was transferred from the truck to a gurney and wheeled into the operating room, lying on her back. Monitoring equipment tracked her pulse, temperature and blood oxygen level. Her fearsome jaws were propped open, and Luskin went to work.

He said a root canal on a police dog might run $1,500 to $1,700. But he donates his services to the zoo. Bronson estimated the remaining costs at several hundred dollars, a tiny fraction of the $400,000 to $500,000 the zoo spends annually on veterinary care.

A graduate of the Veterinary University of Vienna, Austria, and credentialed by the American and the European Dental Colleges, Luskin owns the Animal Dental Centers of Towson, Annapolis and Frederick.

After more than two decades treating dogs, cats and "pocket animals," Luskin also began looking after the dental needs of zoo animals. He tries to keep Thursdays open for them, and has also donated his skills to the National Aquarium in Baltimore and other institutions.

"There are species I have no clue about as far as their dentition," he confessed. "It can be quite challenging."

Except for X-rays, he had never laid eyes on Anoki until she was wheeled into the operating room yesterday morning. But he knew the key challenge would be the sheer size of her canine tooth.

Root canal work - for people and polar bears - requires a drill to give the surgeon access to the canal, files to clear it of dead tissue and bacteria, and a list of substances to sterilize the hole, fill it in, and seal it.

Anoki's fangs are anchored deep in the bone. They're perhaps 5 inches long from root to tip, and they curve.

With Anoki's huge head propped on blue sandbags, her steak-sized tongue flopped to one side, Luskin began drilling. After several minutes of that, and with digital X-rays to guide his aim, his high-speed bit broke through to the canal. Almost immediately, a black fluid oozed out.

"All this black stuff here ... is dead tissue that has filled the canal. It's loaded with bacteria," Luskin said.

Assisted by Dr. Heather Duncan, Luskin worked slender metal files into the spaghetti-sized hole to clear the canal walls of tissue and bacteria. Some he turned with a power tool; some he rasped by hand.

He gradually worked his way down to the tip of the root, periodically irrigating the canal with sodium hypochlorite to remove the debris and sterilize the hole.

Anoki slept on, her vital signs stable throughout the procedure. As Luskin worked, Bronson and her staff took the opportunity to take urine and blood samples, and conducted ultrasound exams of her vital organs. And they checked frequently for signs she was waking up.

A wise vet, Luskin joked, "is not going to work unless she's in La La Land."

When Luskin had finished the surgery, and had closed the hole with a filling color-matched to Anoki's fang, Duncan took Luskin's seat to do some serious periodontal cleaning. The gums around Anoki's front teeth have receded, as has the bone beneath - all signs of significant periodontal disease. That's not uncommon, but a potential threat to her health. "There are definitely some areas we'll have to watch going forward," Bronson said.

By 2:30 p.m. zookeepers had the bear back in her exhibit. By 3 she was looking around, and by 3:30 she was walking - and very thirsty, according to zoo spokeswoman Jane Ballentine.

Bronson ordered pain medications for several days, two weeks of antibiotics and a soft diet - ground meat, iceberg lettuce and fish with their heads and tails removed.


See video of the polar bear root canal at baltimoresun.com/maryland

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