Thumb sucking

Last updated
Infants may use pacifiers or their thumb or fingers to soothe themselves BabySuckingFingers.jpg
Infants may use pacifiers or their thumb or fingers to soothe themselves
Newborn baby thumb sucking
A bonnet macaque thumb sucking Bonnet Macaque Western Ghats.jpg
A bonnet macaque thumb sucking

Thumb sucking is a behavior found in humans, chimpanzees, captive ring-tailed lemurs, [1] and other primates. [2] It usually involves placing the thumb into the mouth and rhythmically repeating sucking contact for a prolonged duration. It can also be accomplished with any organ within reach (such as other fingers and toes) and is considered to be soothing and therapeutic for the person. As a child develops the habit, it will usually develop a "favourite" finger to suck on.


At birth, a baby will reflexively suck any object placed in its mouth; this is the sucking reflex responsible for breastfeeding. From the first time they engage in nutritive feeding, infants learn that the habit can not only provide valuable nourishment, but also a great deal of pleasure, comfort, and warmth. Whether from a mother, bottle, or pacifier, this behavior, over time, begins to become associated with a very strong, self-soothing, and pleasurable oral sensation. As the child grows older, and is eventually weaned off the nutritional sucking, they can either develop alternative means for receiving those same feelings of physical and emotional fulfillment, or they can continue experiencing those pleasantly soothing experiences by beginning to suck their thumbs or fingers. [3] This reflex disappears at about 4 months of age; thumb sucking is not purely an instinctive behavior and therefore can last much longer. [4] Moreover, ultrasound scans have revealed that thumb sucking can start before birth, as early as 15 weeks from conception; whether this behavior is voluntary or due to random movements of the fetus in the womb is not conclusively known.

Thumb sucking generally stops by the age of 4 years. Some older children will retain the habit, which can cause severe dental problems. [5] While most dentists would recommend breaking the habit as early as possible, it has been shown that as long as the habit is broken before the onset of permanent teeth, at around 5 years old, the damage is reversible. [6] Thumb sucking is sometimes retained into adulthood and may be due to simply habit continuation. Using anatomical and neurophysiological data a study has found that sucking the thumb is said to stimulate receptors within the brain which cause the release of mental and physical tension. [7]

Dental problems and prevention

Alveolar prognathism, caused by thumb sucking and tongue thrusting in a 7-year-old girl. Alveolprog.jpg
Alveolar prognathism, caused by thumb sucking and tongue thrusting in a 7-year-old girl.

Percentage of children who suck their thumbs (data from two researchers)

AgeKantorowicz [4] Brückl [8]
Over 69%

Most children stop sucking on thumbs, pacifiers or other objects on their own between 2 and 4 years of age. No harm is done to their teeth or jaws until permanent teeth start to erupt. The only time it might cause concern is if it goes on beyond 6 to 8 years of age. At this time, it may affect the shape of the oral cavity or dentition. [9] During thumbsucking the tongue sits in a lowered position and so no longer balances the forces from the buccal group of musculature. This results in narrowing of the upper arch and a posterior crossbite. Thumbsucking can also cause the maxillary central incisors to tip labially and the mandibular incisors to tip lingually, resulting in an increased overjet and anterior open bite malocclusion, as the thumb rests on them during the course of sucking. In addition to proclination of the maxillary incisors, mandibular incisors retrusion will also happen. Transverse maxillary deficiency gives rise to posterior crossbite, ultimately leading to a Class II malocclusion. [10]

Children may experience difficulty in swallowing and speech patterns due to the adverse changes. Aside from the damaging physical aspects of thumb sucking, there are also additional risks, which unfortunately, are present at all ages. These include increased risk of infection from communicable diseases, due to the simple fact that non-sterile thumbs are covered with infectious agents, as well as many social implications. Some children experience social difficulties, as often children are taunted by their peers for engaging in what they can consider to be an “immature” habit. This taunting often results the child being rejected by the group or being subjected to ridicule by their peers, which can cause understandable psychological stress. [11]

Methods to stop sucking habits are divided into 2 categories: Preventive Therapy and Appliance Therapy. [10]

Examples to prevent their children from sucking their thumbs include the use of bitterants or piquant substances on their child's hands—although this is not a procedure encouraged by the American Dental Association [9] or the Association of Pediatric Dentists. Some suggest that positive reinforcements or calendar rewards be given to encourage the child to stop sucking their thumb.

The American Dental Association recommends:

The British Orthodontic Society recommends the same advice as ADA. [13]

A Cochrane review was conducted to review the effectiveness of a variety of clinical interventions for stopping thumb-sucking. The study showed that orthodontic appliances and psychological interventions (positive and negative reinforcement) were successful at preventing thumb sucking in both the short and long term, compared to no treatment. [14] Psychological interventions such as habit reversal training and decoupling have also proven useful in body focused repetitive behaviors. [15]

Clinical studies have shown that appliances such as TGuards can be 90% effective in breaking the thumb or finger sucking habit. Rather than use bitterants or piquants, which are not endorsed by the ADA due to their causing of discomfort or pain, TGuards break the habit simply by removing the suction responsible for generating the feelings of comfort and nurture. [16] Other appliances are available, such as fabric thumb guards, each having their own benefits and features depending on the child's age, willpower and motivation. Fixed intraoral appliances have been known to create problems during eating as children when removing their appliances may have a risk of breaking them. Children with mental illness may have reduced compliance. [10]

Some studies mention the use of extra-oral habit reminder appliance to treat thumb sucking. An alarm is triggered when the child tries to suck the thumb to stop the child from this habit. [10] [17] However, more studies are required to prove the effectiveness of external devices on thumb sucking.

Children’s books

See also

Related Research Articles

<span class="mw-page-title-main">Orthodontics</span> Correctional branch of dentistry

Orthodontics is a dentistry specialty that addresses the diagnosis, prevention, management, and correction of mal-positioned teeth and jaws, as well as misaligned bite patterns. It may also address the modification of facial growth, known as dentofacial orthopedics.

<span class="mw-page-title-main">Pacifier</span> Rubber, plastic or silicone nipple for infants or toddlers to suck upon

A pacifier is a rubber, plastic, or silicone nipple substitute given to an infant or toddler to suckle upon between feedings to quiet its distress by satisfying the need to suck when it does not need to eat. Pacifiers normally have three parts: an elongated teat, a handle, and a mouth shield which prevents the child from swallowing or choking on it.

<span class="mw-page-title-main">Prognathism</span> Protrusion of the upper or lower human jaw

Prognathism is a positional relationship of the mandible or maxilla to the skeletal base where either of the jaws protrudes beyond a predetermined imaginary line in the coronal plane of the skull.

<span class="mw-page-title-main">Malocclusion</span> Medical condition

In orthodontics, a malocclusion is a misalignment or incorrect relation between the teeth of the upper and lower dental arches when they approach each other as the jaws close. The English-language term dates from 1864; Edward Angle (1855–1930), the "father of modern orthodontics", popularised it. The word "malocclusion" derives from occlusion, and refers to the manner in which opposing teeth meet.

<span class="mw-page-title-main">Tongue thrust</span>

Tongue thrust is a pseudo-pathological name of what is either considered a normal adaptive lip seal mechanism, whereby normal nasal breathing or normal swallowing can occur, or seen as an oral myofunctional disorder a tongue muscle pattern that is perceived as clinically abnormal and in which the tongue protrudes anteriorly to seal otherwise incompetent lips.

<span class="mw-page-title-main">Maxillary central incisor</span> Tooth

The maxillary central incisor is a human tooth in the front upper jaw, or maxilla, and is usually the most visible of all teeth in the mouth. It is located mesial to the maxillary lateral incisor. As with all incisors, their function is for shearing or cutting food during mastication (chewing). There is typically a single cusp on each tooth, called an incisal ridge or incisal edge. Formation of these teeth begins at 14 weeks in utero for the deciduous (baby) set and 3–4 months of age for the permanent set.

<span class="mw-page-title-main">Anodontia</span> Medical condition

Anodontia is a rare genetic disorder characterized by the congenital absence of all primary or permanent teeth. It is divided into two subsections, complete absence of teeth or only some absence of teeth. It is associated with the group of skin and nerve syndromes called the ectodermal dysplasias. Anodontia is usually part of a syndrome and seldom occurs as an isolated entity. There is usually no exact cause for anodontia. The defect results in the dental lamina obstruction during embryogenesis due to local, systemic and genetic factors.

Dilaceration is a developmental disturbance in shape of teeth. It refers to an angulation, or a sharp bend or curve, in the root or crown of a formed tooth. This disturbance is more likely to affect the maxillary incisors and occurs in permanent dentition. Although this may seem more of an aesthetics issue, an impacted maxillary incisor will cause issues related to occlusion, phonetics, mastication, and psychology on young patients.

Orthodontic technology is a specialty of dental technology that is concerned with the design and fabrication of dental appliances for the treatment of malocclusions, which may be a result of tooth irregularity, disproportionate jaw relationships, or both.

Tooth gemination is a dental phenomenon that appears to be two teeth developed from one. There is one main crown with a cleft in it that, within the incisal third of the crown, looks like two teeth, though it is not two teeth. The number of the teeth in the arch will be normal.

<span class="mw-page-title-main">Overjet</span> Medical condition

Overjet is the extent of horizontal (anterior-posterior) overlap of the maxillary central incisors over the mandibular central incisors. In class II malocclusion the overjet is increased as the maxillary central incisors are protruded.

<span class="mw-page-title-main">Crossbite</span> Medical condition

Crossbite is a form of malocclusion where a tooth has a more buccal or lingual position than its corresponding antagonist tooth in the upper or lower dental arch. In other words, crossbite is a lateral misalignment of the dental arches.

Dental pertains to the teeth, including dentistry. Topics related to the dentistry, the human mouth and teeth include:

<span class="mw-page-title-main">Pediatric dentistry</span> Branch of dentistry

Pediatric dentistry is the branch of dentistry dealing with children from birth through adolescence. The specialty of pediatric dentistry is recognized by the American Dental Association, Royal College of Dentists of Canada, and Royal Australasian College of Dental Surgeons.

<span class="mw-page-title-main">Jaw abnormality</span> Medical condition

A jaw abnormality is a disorder in the formation, shape and/or size of the jaw. In general abnormalities arise within the jaw when there is a disturbance or fault in the fusion of the mandibular processes. The mandible in particular has the most differential typical growth anomalies than any other bone in the human skeleton. This is due to variants in the complex symmetrical growth pattern which formulates the mandible.

The Dahl effect or Dahl concept is used in dentistry where a localized appliance or localized restoration is used to increase the available interocclusal space for restorations.

TGuard is the brand name for a medical device used to stop chronic thumb sucking among children and young adults. It is manufactured in the USA by MED et al., Inc. Referred to commonly by dentists as a ThumbGuard, the company claims that it is the most effective removable appliance therapy used to stop and prevent thumb sucking.

<span class="mw-page-title-main">Tooth mobility</span> Medical condition

Tooth mobility is the horizontal or vertical displacement of a tooth beyond its normal physiological boundaries around the gingival area, i.e. the medical term for a loose tooth.

Open bite is a type of orthodontic malocclusion which has been estimated to occur in 0.6% of the people in the United States. This type of malocclusion has no vertical overlap or contact between the anterior incisors. The term "open bite" was coined by Carevelli in 1842 as a distinct classification of malocclusion. Different authors have described the open bite in a variety of ways. Some authors have suggested that open bite often arises when overbite is less than the usual amount. Additionally, others have contended that open bite is identified by end-on incisal relationships. Lastly, some researchers have stated that a lack of incisal contact must be present to diagnose an open bite.

Orthodontic indices are one of the tools that are available for orthodontists to grade and assess malocclusion. Orthodontic indices can be useful for an epidemiologist to analyse prevalence and severity of malocclusion in any population.


  1. Jolly A (1966). Lemur Behavior . Chicago: University of Chicago Press. p.  65. ISBN   978-0-226-40552-0.
  2. Benjamin, Lorna S.: "The Beginning of Thumbsucking." Child Development, Vol. 38, No. 4 (Dec., 1967), pp. 1065–1078.
  3. "About the Thumb Sucking Habit". Tguard.
  4. 1 2 Kantorowicz A (June 1955). "Die Bedeutung des Lutschens für die Entstehung erworbener Fehlbildungen". Fortschritte der Kieferorthopädie. 16 (2): 109–21. doi:10.1007/BF02165710. S2CID   28204791.
  5. O'Connor A (27 September 2005). "The Claim: Thumb Sucking Can Lead to Buck Teeth". The New York Times. Retrieved 1 August 2012.
  6. Friman PC, McPherson KM, Warzak WJ, Evans J (April 1993). "Influence of thumb sucking on peer social acceptance in first-grade children". Pediatrics. 91 (4): 784–6. doi:10.1542/peds.91.4.784. PMID   8464667.
  7. Ferrante A, Ferrante A (August 2015). "[Finger or thumb sucking. New interpretations and therapeutic implications]". Minerva Pediatrica (in Italian). 67 (4): 285–97. PMID   26129804.
  8. Reichenbach E, Brückl H (1982). "Lehrbuch der Kieferorthopädie Bd. 1962;3:315-26.". Kieferorthopädische Klinik und Therapie Zahnärzliche Fortbildung. 5. Auflage Verlag. JA Barth Leipzig" alıntı Schulze G.
  9. 1 2 "Thumbsucking - American Dental Association". Archived from the original on 2010-06-19. Retrieved 2010-05-19.
  10. 1 2 3 4 Shetty RM, Shetty M, Shetty NS, Deoghare A (2015). "Three-Alarm System: Revisited to treat Thumb-sucking Habit". International Journal of Clinical Pediatric Dentistry. 8 (1): 82–6. doi:10.5005/jp-journals-10005-1289. PMC   4472878 . PMID   26124588.
  11. Fukuta O, Braham RL, Yokoi K, Kurosu K (1996). "Damage to the primary dentition resulting from thumb and finger (digit) sucking". ASDC Journal of Dentistry for Children. 63 (6): 403–7. PMID   9017172.
  12. "Stop Thumb Sucking". Stop Thumb
  13. "Dummy and thumb sucking habits" (PDF). Patient Information Leaflet. British Orthodontic Society.
  14. Borrie FR, Bearn DR, Innes NP, Iheozor-Ejiofor Z (March 2015). "Interventions for the cessation of non-nutritive sucking habits in children". The Cochrane Database of Systematic Reviews. 2021 (3): CD008694. doi:10.1002/14651858.CD008694.pub2. PMC   8482062 . PMID   25825863.
  15. Lee MT, Mpavaenda DN, Fineberg NA (2019-04-24). "Habit Reversal Therapy in Obsessive Compulsive Related Disorders: A Systematic Review of the Evidence and CONSORT Evaluation of Randomized Controlled Trials". Frontiers in Behavioral Neuroscience. 13: 79. doi: 10.3389/fnbeh.2019.00079 . PMC   6491945 . PMID   31105537.
  16. "Unique Thumb with Lock Band to Deter Child from Thumb Sucking". Clinical Research Associates Newsletter. 19 (6). June 1995.
  17. Krishnappa S, Rani MS, Aariz S (2016). "New electronic habit reminder for the management of thumb-sucking habit". Journal of Indian Society of Pedodontics and Preventive Dentistry. 34 (3): 294–7. doi: 10.4103/0970-4388.186750 . PMID   27461817. S2CID   22658574.
  18. "Books on the Subject of Thumb-Sucking". Thumb-Heroes. 9 December 2020.
  19. Stevens Mills, Christine (2018). Two Thumbs Up - Understanding and Treatment of Thumb Sucking. ISBN   978-1-5489-2425-6.

Further reading