The Habit

Thumb sucking at an early age is considered a normal and natural activity among children. It grows out of very strong sucking reflex, which is vital for child's survival. While babies use sucking in order to get nutrition, they experience certain pleasurable oral sensations, some of which associated with the fulfillment from food, closeness, and tenderness. In most cases, as the child matures he or she finds alternative means of receiving the same forms of positive emotional fulfillment.

Most children stop somewhere between two and four years of age. However, some children look for a way to continue the once necessary and pleasantly soothing experience of nutritional sucking (either breast feeding or sucking from the bottle), thus forming the thumb (or finger) sucking habit. This habit, if not eliminated by a certain age, may become detrimental to a child's physical, emotional and social development. The effects of thumb sucking are usually reversible up until the age of seven, because children still have their deciduous (baby) teeth. If thumb sucking continues beyond the age of seven, when the second teeth are erupting, permanent dental problems can occur.

The Ins and Outs of Thumb-Sucking

Studies show that 50 percent to 70 percent of children have a thumb-sucking habit during their first year. Thumb sucking often begins as early as the 29th week of gestation, and most children spontaneously stop the habit by age 4 or 5.

Here's what you should know about thumb-sucking:
  • It is a reflexive response to any nipple-shaped object brushing the cheek or lips.
  • It satisfies the child’s need for oral stimulation, and it is a natural, normal way that children soothe themselves.
  • Infants explore their world primarily through the mouth.
  • Prior to age 5, thumb-sucking is acceptable if the habit stops before the permanent teeth emerge. Thumb sucking rarely affects speech.
Problems caused by thumb and finger sucking

Excessive thumb sucking may lead to:

  • Misaligned teeth - for example; the front teeth may be pushed out of alignment. This can alter the shape of the face and lead to an open bite.
  • A lisp - pre-school children who suck their fingers and thumbs can push their teeth out of their normal position. This interferes with the correct formation of certain speech sounds.
  • Health - an increased risk of communicable childhood diseases, as a result of constantly putting a dirty thumb in the mouth.
  • Socially - a possibility of slowing down child's social development because children who suck their thumbs (fingers) are perceived by their peers as babies, and in many instances, either not accepted by the group as equal or ridiculed by their peers.(2)

Vigorous thumb sucking may profoundly alter the development of the mouth and the positioning of the teeth in the upper and lower jaws. As a result, the roof of the mouth is pushed upward and narrows, which leads to the development of a cross bite. Improper positioning of the front teeth and tongue can often lead to speech impediments (the inability to pronounce certain sounds).

Rather expensive orthodontic work, involving lots of time, effort, and unpleasant dental procedures would be required to correct these problems (if the habit is not eliminated at the right time).

It's important to remember that if thumb sucking is extinguished at an early age, many of the problems listed above may naturally fix themselves, including the shape of the jaws and positioning of the teeth. A study suggests that "natural correction of malocclusion caused by thumb and finger sucking is related not only to the degree of malocclusion, but also to lip and tongue function as well as that of other perioral musculature."[1]

SOURCES:
(1)"Damage to the primary dentition resulting from thumb and finger (digit) sucking", Journal of Dentistry for Children. Nov-Dec 1996.
(2) "Influence of thumb sucking on peer social acceptance in first-grade children", Pediatrics. April, 1994.