Sucking is a normal, self-soothing reflex present before birth. Most children take up a thumb, finger or dummy at some point, and most give it up on their own without any lasting effect. The question parents actually need answered is when it stops being normal and starts changing the way the teeth and jaws develop.
The short answer on timing
A sucking habit that stops by around age three generally causes no lasting change; any effects on the baby teeth tend to correct themselves once the habit ends. Habits that continue past age four, and particularly past the point where the adult front teeth are coming through at around six, are the ones associated with changes that persist and may need treatment.
So the practical rule is: no concern before three, gentle encouragement from three to four, and active support to stop from around four onward.
What prolonged sucking can do
- An open bite, where the front teeth do not meet when the back teeth are together, leaving a gap the thumb or dummy occupied.
- Upper front teeth tipped forward, which increases the risk of them being knocked in a fall or during sport.
- A narrowed upper jaw, because the cheek muscles press inward when the tongue is not resting against the palate. This can lead to a crossbite where the upper back teeth sit inside the lower ones.
- Tongue thrust and speech effects, where the tongue pushes forward into the gap during swallowing and speech, which can reinforce the open bite.
Intensity matters as much as duration. A child who sucks vigorously for hours will show changes sooner than one who rests a thumb in the mouth while falling asleep.
Thumb or dummy?
Both can affect the bite. The practical difference is that a dummy can be removed by a parent and a thumb cannot, which is why dummy habits are usually easier to stop and tend to end earlier. Orthodontic-shaped dummies may reduce the effect somewhat, though the evidence is not strong; duration remains the dominant factor.
Never dip a dummy in honey, jam or anything sweet. It bathes the front teeth in sugar for extended periods and causes rapid decay in exactly the teeth already under pressure from the habit.
Helping a child stop
What does not work: nagging, shaming, and pulling the thumb out repeatedly. Sucking is a self-soothing behaviour, so pressure and anxiety tend to increase it.
What tends to work:
- Wait until the child is willing. A child who wants to stop succeeds far more often than one being made to. Around four to five, many respond to a simple conversation about big kids and grown-up teeth.
- Identify the triggers. Tiredness, boredom, screen time and anxiety are the usual ones. Addressing the trigger often does more than addressing the habit.
- Reward progress visibly. A sticker chart aimed at daytime first, since nights are harder, and a goal the child chose.
- Substitute at the trigger point. A cuddly toy to hold at bedtime, or something to occupy the hands during television.
- A gentle physical reminder at night, such as a sock or a plaster over the thumb, framed as a helper rather than a punishment, and only with the child’s agreement.
- Let someone else say it. Children often take the message better from a dentist than from a parent, which is worth using.
- Pick your moment. Not during a house move, a new sibling, or starting school.
Where a habit persists past six or seven despite genuine effort, a dentist can discuss appliances that interrupt the habit. These are a later step, not a first resort.
When to raise it at an appointment
Mention it if the habit continues past four, if you can see a gap between the front teeth when your child bites together, if the upper front teeth are tipping forward, if the upper back teeth are biting inside the lower ones, or if speech sounds are affected. An assessment around ages seven to nine is useful in any case, because that is when early intervention is most effective if it is needed at all.
Reassuringly, many bite changes from a sucking habit improve on their own once the habit stops, particularly if it stops before the adult front teeth are established.
What assessment costs
For children covered by the Medicare Child Dental Benefits Schedule, examinations and cleans may be covered; check eligibility and the current balance through your Medicare online account. Otherwise our new patient consultation and clean package starts from $219 and includes an examination, scale and clean, fluoride treatment and two bitewing X-rays. Where orthodontic treatment is eventually needed, Invisalign ranges from $4,200 to $8,990 and traditional metal braces from $4,000 to $8,000. Current fees are on our price list, with more on dental care for children and braces.
Common questions
My two year old still uses a dummy. Should I be worried?
No. At that age it is entirely normal and unlikely to cause lasting change. Aim to phase it out before around three.
Will the teeth straighten by themselves if the habit stops?
Often, yes, particularly if the habit ends before the adult front teeth are through. Some changes persist and need orthodontic treatment later.
Is a dummy better than a thumb?
Both affect the bite similarly. A dummy has the practical advantage that it can be taken away, so habits tend to end sooner.
Should I use bitter nail polish on the thumb?
Some families find it useful with an older child who wants to stop. It works poorly and can feel punitive with a younger child who is not ready.
Booking an appointment in Canberra City
Civic Gentle Dental Care is a dentist in Canberra at Suite 8, Level 3/161 London Circuit, Canberra City, a short walk from the Canberra Centre. To arrange an appointment, call (02) 6247 0224 or send us a message through our contact page.
This article is general information only and is not a substitute for individual dental advice. Whether a treatment is suitable for you, and what it will involve, can only be determined after an examination by a dentist. Any prices mentioned are estimates drawn from our current price guide and are not a quote.