TORONTO - Watching people brush their teeth in movies or on TV can really irk Dr. Andrea Johnstone.

A Toronto-based periodontist with a gleaming smile, Johnstone says the technique on display is often the very approach dental professionals warn their patients not to use.

"They are generally doing the scrub-brush method of just back and forth scrubbing their teeth. Even sometimes on toothpaste commercials. It drives me nuts, actually," she admits.

It's an illustration of a common problem. Everyone thinks they know how to brush their teeth. Heck, it's one of the first skills we learn in childhood, one we use — or should use — at least twice daily every day of life.

But many people don't actually use the right tooth-brushing technique, which can lead to cavities, tartar buildup and gum disease.

So what are we doing wrong? The most common shortcomings relate to the motion used and the length of time we spend on each brushing session, experts say.

"The tendency is for people to be far too quick when they brush their teeth, to actually not take the 2 1/2 to three minutes that are necessary to get your teeth clean," says Dr. Peter Doig, president of the Canadian Dental Association.

Some people go on autopilot when they put a toothbrush into their mouths. Up and down, or back and forth, they make a quick tour around their teeth, spit, rinse and are done with it.

Doig says in order to effectively remove plaque — the film of bacteria that can accumulate on teeth after eating foods containing sugars and starches — you need to concentrate. Every time, on every tooth.

Neither Doig nor Johnstone recommends a specific toothbrush. "It's not the wand, it's the magician," Doig says. But both say you should always use a soft-bristled brush to safely remove the plaque without damaging the gums.

That area — where the tooth meets the gum — is a critical part of the tooth to focus on. That's where plaque builds up. If it's not removed, it forms into tartar, which normal brushing won't remove.

"The goal is to get it before it hardens," says Johnstone.

That's because as tartar accumulates, it can go below the gum line, eroding the bone that holds the teeth in place. As the bacteria triggers recession of gums, more of the tooth's root is exposed, amplifying the bone erosion problem.

To stop this process from even starting, Johnstone says you need to angle the bristles of your toothbrush at a 45-degree angle where the gum meets the tooth. Use a gentle, circular massaging motion to loosen the plaque, and then flick the brush upward (or downward, if you are working on the upper teeth) to move the plaque away.

"So basically it's just kind of a wiggle at the gum line, and then swishing the plaque away from the gum line with their brush," she says.

Easy does it.

"A lot of people think they need to scrub brush their teeth," says Johnstone. "And then what can end up happening is then we start to see areas of gum recession. So they actually start to brush their gums away.

"We want to focus on removing the plaque gently and efficiently, but not removing the gums. Half my day I spend trying to transplant gums back onto people. ... A lot of that could be avoided with proper tooth brushing."

Doig says it's important to remember to brush each tooth, and each exposed surface. People often do a good job of brushing the exterior of their front teeth, he says, but may spend too little time on the inside of each tooth — or the inside of the teeth in general.

People may also forget to brush their tongue, which should be part of the routine, he says. Tongues get coated with a lot of bacteria, which can be a cause of halitosis, or bad breath. Johnstone recommends tongue scrapers — small plastic devices that can be run over the surface of the tongue to remove that film. And yes, she knows treating your tongue can trigger a gag reflex.

"I find the tongue scrapers a little better for gaggers. But it can still make you gag. But you've got to get through it. It's worth it for fresh breath."

Johnstone and Doig offer some oral hygiene dos and don'ts:

— Do brush at least twice a day. Brushing after every meal is better still.

— Don't hurry. You need to spend two to three minutes at brushing every time. Use a timer or pay attention to the timer feature of your electric toothbrush. Or brush for the duration of a song on the radio, Johnstone suggests.

— Do use fluoridated toothpaste.

— Do change your toothbrush every three months or so.

— Don't share a toothbrush.

— Do floss, at least once a day. It is the only way to clean the surfaces between teeth. Floss before brushing.

— Don't use stiff-bristled brushes.

— If you aren't sure about your brushing technique, do ask your dentist or hygienist to show you how to do it properly.

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    While dried fruits may be a definite <a href="http://www.huffingtonpost.com/2012/02/28/fruit-chew-snacks-ingredients_n_1304369.html">step up from processed fruit snacks</a>, they are still sticky and high in sugar. That means they not only adhere to teeth easily, but the sugar feeds the bacteria in the mouth, which can promote dental erosion, notes Joy Dubost, Ph.D., R.D., a spokesperson for the American Academy of Nutrition and Dietetics. "I'm not saying don't eat them, but just brush your teeth afterward," Dubost says. Messina adds that regular fresh fruits don't typically have this problem because -- even though they still have sugar -- chewing them up promotes saliva and they don't stick to the teeth. "Fruits are generally pretty safe because they're good for overall health <em>and</em> they're chewy, so your average fruit has some substance to it and we chew through it, causing us to salivate more," Messina says. "Saliva is a good thing because it has washing action and it's a nautral buffer [to] acid."

  • Sugary Drinks

    Sugary drinks, such as sodas and sports drinks, are especially bad for teeth when sipping for long periods of time. "If I have a soft drink or sports drink and I'm sipping it every 20 minutes, my teeth are getting bathed with a constant layer of acid," Messina says. "So sitting down and drinking it all at once, or with a meal, is better than snacking or sipping throughout a meal." For this reason, Dubost recommends that parents don't fill their kids' sippy cups with sugary drinks, since kids, whose teeth are still developing, tend to sip at those drinks over long periods of time.

  • Hard Candies

    For the same reason sipping on sodas all day is bad for teeth, hard candies aren't ideal for oral health, Dubost notes. These sweets pack a double whammy in that they not only stick to the teeth, but they also linger in the mouth for a long time as you wait for them to dissolve.

  • Alcohol

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  • Citrus/Acidic Foods

    Foods high in acid, such as citrus or tomatoes, can promote tooth decay, especially when eaten alone, Dubost notes. But these foods are fine to eat so long as you flush your mouth with water after consuming them in order to buffer the acid. Citrus not only has acid, but also sugar -- and people who have a habit of sucking on lemons or limes are actually harmfully bathing their teeth in acid, Messina says. "If you look in their mouths, their teeth have a shiny, glossy surface -- that's from constant bathing with the acids," he says. "They will have almost a peculiar look in that you'll see it on the front surfaces of their teeth, but not the back sides of the lower front teeth because those are under the tongue -- and the tongue protects the surface of teeth."

  • Starchy Foods

    Starchy foods, such as potato chips and white bread, easily get trapped in teeth, which can then <a href="http://www.yalemedicalgroup.org/stw/Page.asp?PageID=STW001565">feed the bacteria</a> that make up plaque, according to the Yale Medical Group.

  • Coffee

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