Lip and Tongue Habits Affecting Orthodontics UK

Types of oral habits

The most clinically significant oral habits in the context of orthodontics are digit sucking (thumb or finger), dummy or pacifier use, lip sucking or biting, and nail biting. Each exerts a mechanical force on developing teeth and bone, and each carries a different risk profile depending on the age of the child, the frequency of the habit, its duration over time, and the intensity of the force applied. These are collectively described as non-nutritive sucking habits, though lip and nail habits involve different mechanisms.

Dental effects of digit sucking

Digit sucking - most commonly thumb sucking - exerts pressure on the upper front teeth, pushing them forward, while the lower lip may rest behind the upper incisors, reinforcing the effect. The characteristic dental changes include increased overjet (upper front teeth protrude further in front of the lower), anterior open bite (the front teeth do not meet vertically), posterior crossbite (the back teeth bite in the wrong position side to side), and a narrowed or constricted upper arch. The severity of these effects is directly proportional to the frequency, duration, and intensity of the habit. Occasional sucking causes less damage than constant, forceful sucking maintained throughout the day and night.

Normal self-resolution and age thresholds

Most children stop digit sucking naturally between the ages of 2 and 4 as they develop other coping strategies and social awareness. The consensus in orthodontic and paediatric dentistry is that habits ceasing before age 4 to 5 carry minimal long-term dental risk - the mouth is highly adaptable during this period, and most minor changes resolve spontaneously with normal jaw growth. Beyond age 5, and particularly if the habit continues past age 6 or 7 when permanent teeth are erupting, the risk of lasting dental change increases significantly. NHS and BSPD guidance reflects this threshold in decisions about when to intervene.

Dummy and pacifier effects

Dummies cause similar dental changes to digit sucking - open bite, increased overjet, and posterior crossbite - but the effects are generally milder because the force applied is lower and the contact is more diffuse. Dummies also have the advantage of being easier to remove than a thumb. Evidence suggests stopping dummy use by age 3 to 4 minimises dental risk, and most changes resolve naturally once the habit stops at this age. Some orthodontists prefer that children stop earlier, around age 2, as a precaution. Orthodontic-shaped dummies have limited evidence to suggest they are significantly better than standard dummies in preventing dental effects.

Lip sucking and lip biting

Lip sucking involves drawing the lower lip behind the upper front teeth, where it acts as a force appliance - pushing the upper teeth forward and pushing the lower teeth back. This directly worsens overjet and can create or perpetuate the habit of having the lower lip trapped behind the upper teeth (lip trap). Lip biting - biting on the lower lip - can have similar effects. These habits are sometimes secondary to an existing large overjet, where the lower lip naturally falls behind the upper teeth, creating a self-reinforcing cycle. Addressing the overjet orthodontically often resolves the lip habit as a consequence.

Clinical significance versus normal development

Not every child who sucks their thumb will need orthodontic treatment. Clinicians assess the overall malocclusion in context - including skeletal pattern, IOTN score, and the degree to which changes are likely to self-correct. A mild anterior open bite in a 5-year-old who has just stopped sucking their thumb is likely to resolve without intervention. A significant open bite, posterior crossbite, and increased overjet in a 9-year-old with a persistent habit is clinically significant and warrants orthodontic review.

Intervention timing and habit-breaking appliances

The first approach is always to wait for self-resolution and to support the child in stopping the habit voluntarily - positive reinforcement, behavioural strategies, and parental support are often effective. If the habit persists beyond age 7 to 8 and the dental effects are significant, habit-breaking appliances may be considered. The palatal crib is the most commonly used - a fixed appliance attached to upper back teeth with a wire cage or crib sitting behind the upper front teeth, acting as a physical barrier that interrupts the reward sensation of sucking. The Bluegrass appliance uses a bead roller that the tongue can play with instead, redirecting oral stimulation. These appliances are highly effective at habit cessation and are typically worn for 6 to 12 months.

Orthodontic correction after habit cessation

Once the habit has stopped, the extent of self-correction depends on the age of the child, the severity of the changes, and skeletal factors. Anterior open bites in young children show the strongest tendency to self-correct - the tongue posture often normalises and the teeth erupt into a better position over time. Posterior crossbites do not reliably self-correct and usually require palatal expansion. Increased overjet may partially resolve with growth but often requires full orthodontic treatment. Myofunctional therapy - exercises targeting the muscles of the lips, tongue, and face - can support self-correction and is sometimes used alongside or after habit-breaking appliances.

Useful related pages

This guide is for general information only. It is not a diagnosis, treatment plan, or substitute for advice from a registered dentist or orthodontist.