Dear Annie: Recently, I stayed with my niece and nephew while my brother and his wife took a trip. This seems like a trivial problem, but I know it can lead to serious health issues in the long run. Neither of my brother’s teenaged kids brushed their teeth regularly. I reminded them often, but they found ways to wiggle out of it. One was even running the electric toothbrush outside of his mouth — so I would think he was brushing his teeth. When I went into the bathroom afterward, the electric toothbrush was bone dry. His sister later told me about that trick.

I asked my brother about this, and he said they’ve tried for years to get the kids to brush their teeth more consistently. They gave them excellent electric toothbrushes and set a great example of brushing at least twice a day themselves. If they try to watch the kids brushing, it turns into a huge fight every time. They’ve spent hundreds of dollars on dental care as a result. They’re at a loss as to what to do. The kids understand it’s important but just don’t care enough to change their habits. Of course, they do not realize the long-term damage they may be doing, including dangers of infection and disease.

Anything I can do to help them? We’re very close, so my brother and his wife would not see it as butting in. They’d welcome a solution. — Brushless in Baton Rouge

Dear Brushless: While this may seem like a molehill of a problem now, a mountain of plaque buildup on your niece’s and nephew’s teeth is a huge problem. This is a fight worth fighting. Since they are teenagers, explain to them the diseases and long-term damage that they are at risk of if they fail to brush their teeth. Showing them actual pictures of decayed teeth, while disturbing to look at, could be powerful motivators. Being upfront about the cost of the dental work, and what their family could have spent money on instead — vacation, shopping, extracurricular activities — might have them see the impact of their poor dental hygiene in a new way, too.

Perhaps your brother and his wife could try incentives or rewards for completed brushings. It takes roughly two months to form a good habit. So, when setting the reward, have that goal in mind. When they do brush their teeth or get a good cleaning, take a moment to point out just how good it feels to be clean and taking care of your body. Naturally, as humans, we like to be clean.

Also, continue to have their dentist talk to your niece and nephew about the importance of dental hygiene.

Editor’s note: “Ask Me Anything: A Year of Advice From Dear Annie” is out now! Annie Lane’s debut book — featuring favorite columns on love, friendship, family and etiquette — is available as a paperback and e-book. Visit http://www.creatorspublishing.com for more information. Send your questions for Annie Lane to dearannie@creators.com.