Thumbs down

Loren Batson/Dominion Post

Children's dentist Erin Mahoney with her son Finn Studd.

The instant quiet, the slightly glazed expression, that little pink finger hooked contentedly around a nose - there's a simple reason children suck their thumbs, says Dr Erin Mahoney.

"It just makes them feel good."

Thumb-sucking is a reflex that develops while babies are still in the womb, which means your child might already be a veteran when they arrive in this world. "In utero they're sucking already so it's a comfort thing," Mahoney says.

A paediatric specialist for the Wellington region's dental service, she says many parents worry about thumb-sucking - and the resulting orthodontist bills that could loom a decade down the track.

However, it's not a problem while children still have their baby teeth.

"There's a lot of mis-thought that you should immediately stop it at 2."

It's only when kids' permanent teeth are about to come through, usually when they're about 5 or 6, that they need to be gently weaned off to prevent permanent damage to their mouths.

"It can change the position of the teeth and the bone around the teeth quite a lot, but until the permanent teeth come through the body can fix itself."

The most common problem thumb-sucking causes over time is misaligned teeth: "If the thumb is in the mouth for a long enough period, which can be all through the night, you can end up with an open bite - your back teeth meet but your front teeth don't."

The constant sucking movement of cheek muscles can also sometimes change the shape of the upper jaw, from a U to a V. Both can lead to problems with speech and increase the chances of tooth decay.

Coating a dummy in honey or flavoured milk - as some parents do - is an absolute no-no. Not only does it reinforce the habit, it can easily cause dental decay.

Many parents will find their child will stop thumb- sucking by the time they hit school, without any prompting, Mahoney says. About half will need positive but persistent encouragement to give up and about 5 per cent will need a dentist's helping hand.

Most chemists sell bitter-tasting liquid that can be painted on little fingernails, but Dr Mahoney says it often doesn't deter ardent thumb-suckers. A better option, which can help your child consciously stop sucking, is a star chart.

Make it between three weeks and a month long - about the length of time it takes to break any habit - and explain to your child what the chart is for. "Say; 'if anyone in the family sees you doing it, then we have to start again'." Let them help decide on rewards, which can also be given for milestones such as the end of each thumb-free week.

One of Mahoney's favourite bed-time tricks is to cover the child's hand with a sock before they go to sleep. "They can't suck their thumb if they've got a sock on."

It's worth persevering on your own before getting outside help, but if nothing has worked and your child's adult teeth are about to make their debut, you might need to stage a dental intervention.

"Sometimes all it takes is someone else telling them to stop," Mahoney says. "It just needs some outside influence other than their mum or dad."

And for the absolutely determined thumb-sucker?

"We have means and ways of stopping thumb- sucking - by way of appliances that we fit in the mouth."

The older a child gets, the harder the habit is to break, especially in children over the age of about 10, who may not want to stop. In such cases it's best to head straight to a dentist or orthodontist. Sometimes,thumb- sucking might be a reaction to stress. Having a quiet chat with your child might help to uncover the real problem.

In all situations, keep encouragement positive and take a break if the battle becomes fraught, Mahoney says. "I wouldn't make fun of them or be too hard on them. It's something they've been doing for a very long time, before they were born . . . and they might be a bit sensitive about it." Fairfax

- © Fairfax NZ News