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Thumb or Digit Sucking

Published on Mar 14, 2020 and last reviewed on Nov 28, 2022   -  5 min read


Thumb or digit sucking is the most common oral habit among children. If this continues after 3 to 4 years of age, then it can result in harmful effects on the teeth and jaws. Read the article to know more about this article.

Thumb or Digit Sucking

Babies have the natural rooting reflex and sucking reflex, which makes them insert fingers in their mouth and that persistent habit leads to thumb or digit sucking. This habit has dangerous effects on the development of the dentofacial complex. To avoid all these complications, one need to diagnose it early and get it treated. This article helps you understand the signs that you need to look out for and ways to help your child stop sucking his or her thumb.

What Is Thumb or Digit Sucking?

Digit or thumb sucking is the placement of thumb or any of the digit in the mouth. In this habit, there is forceful sucking of thumb or digit. It involves or is associated with strong buccal and lip contractions, which have deleterious effects on the dentoalveolar complex.

Psychology of Thumb Sucking:

There are various theories stating the psychology of children behind the cause of thumb or digit sucking:

  1. One of the theories states that it is because of improper feeding or interference in nursing that results in thumb or digit sucking, which is antisocial behavior.

  2. Another theory states that it is not because of weaning, but it is because of prolonged nursing and therefore child continues to feed by sucking.

  3. Few other states that thumb sucking is an expression of a need to suck, because of its association with primary reinforcing aspects of feeding. Thumb sucking arises from the rooting and placing reflexes.

Clinical Aspects of Digital Sucking:

1) Prenatal or Antenatal - This habit of thumb or digit sucking can be noticed shortly before the child passes through the birth canal. The fetus shows increased muscular activity. Fetus seeks this position of comfort, which may interfere with postnatal development of the dentofacial complex.

2) Postnatal - Finger sucking in the first 4 years of age. Infants start sucking habit in the first three months of life, mostly because of:

Thumb sucking habit is in the first four years of life, then it is confined to the anterior segment and when it is temporary, then the child starts with normal occlusion. An exerciser or pacifier greatly reduces the need and desire of the infant for thumb sucking between meals and at bedtime.

Active Finger Sucking After 4 Years of Age: When the habit of thumb or digit sucking continues even after four years of life, then the probability of malocclusion increases.

Trident of Habit (Thumb or Digit Sucking) Factors:

  1. Duration - The time of sucking, meaning the hours per day that a child sucks on his thumb plays a a crucial role in tooth displacement or malocclusion.

  2. Frequency - The number of times the child indulges in thumb or digit sucking per day affects the development of the dentofacial complex.

  3. Intensity - The intensity is directly proportional to damage to the dentofacial complex.

Effects of Thumb Sucking:

The effects of sucking habit depend on:

  • Position of the thumb in the mouth.

  • Leverage effect the child gets against the other teeth and the alveolus.

1) Apposition of sucking finger on the maxilla - When the finger rests on the lower incisors, it leads to:

  • The development of class I and class II division I malocclusion.

  • Anterior open bite.

  • Protraction of maxillary anterior teeth.

  • Labial tipping of mandibular anterior teeth.

  • Lingual displacement of lower anteriors.

  • Vertical equilibrium is altered on the posterior teeth.

  • The maxillary arch tends to become v-shaped.

2) Thumb sucking along with tongue thrusting (this is to maintain the anterior seal):

  • Narrow nasal floor.

  • High palatal vault.

  • The upper lip is hypotonic.

  • The lower lip is hyperactive.

  • Hyperactive mentalis muscle.

3) When the child bites on both its index fingers, it leads to:

  • Protrusion and open bite.

  • Bilateral posterior crossbite because the posterior teeth are pushed palatally by the strong buccal musculature.

4) Apposition of finger sucking on the mandible - Proclination of upper and lower incisors is due to forward and downward placement of the tongue, which can lead to:

  • Class III malocclusion as mandible jaw is pulled forward by sucking fingers.

  • Facial asymmetry.

  • Occlusion is disturbed.

  • Callus formation.


Most children discontinue this habit around 4 years or 5 years of age. When they stop, malocclusion, if present, corrects by itself and treatment is not needed in that case. If the habit continues up until the time of eruption of the permanent incisors approach, consultation with a dentist is advised.

  • Reminder therapy - Use of adhesive bandage and waterproof tape on the finger that is being sucked.
  • Reward system - In which a small tangible reward is given daily for not engaging in the habit.
  • If this fails, then take an elastic bandage and wrap it loosely around the elbow. This prevents the child from flexing the arms and sucking the finger.
  • If this fails, then a reminder appliance is fitted. For example, crib, maxillary lingual arch with a crib, etc.

Psychological Approach - This is useful in older children whose cooperation can be obtained. Such a child will not get any satisfaction from habit but experience a painful reaction. When he or she cames to know it is harmful, they stop doing it.

Chemical Approach - Use of hot, bitter, or foul-smelling preparations on the finger that is being sucked.

Removable Appliances:

1) Tongue spike or tongue crib - It serves the following functions -

  • To break the suction and reduce the force on the anterior segment.

  • As a reminder.

  • It makes the habit non-pleasurable.

  • Forces the tongue backward, nearly to a normal position.

2) Rake appliance - A rake may be removable or fixed. It is useful in correcting thumb sucking, tongue thrusting, and abnormal swallowing.

Fixed Appliances:

Vestibular screen -

  • Maxillary lingual arch with a palatal crib.

  • Bluegrass appliance was used to stop thumb sucking. Here, a modified six-sided roller machine made from Teflon was used.

Time of Therapy:

Followup appointments are made at a 3 to 4-week interval. The appliance to be worn for 4 to 6 months. A period of three months with a total absence of finger sucking is assurance for no relapse. The appliance is removed in parts. After three months of habit free period, the spurs are cut off. Then three weeks later, posterior loop extension is cut. Ant then palatal bar and crown may be removed after another three weeks.

For more information, consult a dentist online now!


Last reviewed at:
28 Nov 2022  -  5 min read




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