Thumbsucking is a very common childhood activity that is estimated to occur in about 80% of normal infants and children. It has been observed in utero starting at 29 weeks of gestation and is usually observed within the first three months of life.
In the United States, about 30% of children suck their thumb at age 1. Most children spontaneously give up the habit between age 2 and age 4, with only 12% of children still sucking their thumbs at age 4.
While thumbsucking is more prevalent during sleep in early infancy, by age 1 it is more often a daytime habit, and can occur when the child is bored, tired or anxious. It can also occur while the child is holding on to an object (such as a blanket or toy). While girls and boys are equally likely to develop the habit, some data suggests that girls may have a harder time giving it up.
One study suggested that non-nutritive sucking (including pacifier use, finger sucking and thumbsucking) was more likely in infants who were bottle-fed than breastfed infants.
Consequences of Thumbsucking
Damage caused by thumbsucking. Image source: http://en.wikipedia.org/wiki/File:Alveolprog.jpg
Unlike pacifier use, thumbsucking has not been associated with a higher risk of otitis media or interference with breastfeeding, and even has been shown to have adaptive value up to age 4. Up to age 4-5, thumbsucking has not been shown to have long-term consequences.
However, If thumbsucking persists past age 5, it can cause permanent damage to the teeth, including overbites, cross-bites and dental crowding, although some recent articles have not found significant associations between improperly aligned bites and thumbsucking behaviors.
Parents should keep in mind that the likelihood of changes in dentition depends on both genetics and the duration and severity of sucking, with tooth movement generally requiring 4-6 hours of force per day.
Children are also at increased of skin and nail problems on the thumb such as callus formation, paronychia and herpetic whitlow. Children are also at risk of ingesting chemicals on the hand, and can even have orthopedic problems such as radial angular deformities from prolonged sucking.
Finally, children may suffer from low self-esteem if they are ridiculed by parents or peers.
Children under the age of 4 do not require any treatment, and parents should wait to see if the behavior stops spontaneously. Treatment should also not be pursued in older children if the habit is infrequent or not causing any negative consequences.
The first choice for treatment in children over four should be behavioral modification. If possible, children should be involved in creating their own behavioral modification plan. Pediatric dentists can also be involved in explaining the potential negative consequences of continued thumb-sucking to older children.
Recommendations for behavioral therapy include:
1. Positive reinforcement when the child is not sucking the thumb
a. Examples include praise, non-food rewards, stickers on a chart, or counting occurrences of sucking and then rewarding for decreases over time
2. Being attentive to triggers of thumbsucking (anxiety, boredom), and providing alternative comfort either in the form of parental attention or an alternate soothing technique such as squeezing an object
3. Aversion therapy, including splints, bad-tasting substances, socks, band-aids, splints or gloves.
If these methods fail, dental appliances can be installed that remind the child not to suck the thumb. Parents should make clear to the child that the appliance is not a punishment, but is only to help the child break the habit. Appliances usually only need to be in place for approximately 3 months, and should be placed in spring or summer so that the child has plenty of opportunity for distraction. Fixed appliances are more effective than ones that can be removed by the child.
Resources for families:
- Davidson L. Thumb and Finger Sucking. Pediatrics in Review. June 2008.
- Tsend AG, Biagioli FE. Counseling on early childhood concerns: sleep issues, thumb sucking, picky eating, and school readiness. American Family Physician. July 2009.
- Vinay C, Sandeep V, Hanumanth Rao CH, Uloopi KS, Kumar AS. Modified quad helix applicance for thumb sucking and cross bite correction. Contemporary Clinical Dentistry. October 2013.
- Luzzi V, Guaragna M, Ierardo G, Saccucci M, Consoli G, Vestri AR, Polimeni A. Malocclusions and non-nutritive sucking habits: a preliminary study. Progress in Orthodontics. November 2011.
- Montaldo L, Montaldo P, Cuccaro P, Caramico N, Minervini G. Effects of feeding on non-nutritive sucking habits and implications on occlusion in mixed dentition. International Journal of Paediatric Dentistry. January 2011.