Pacifiers and thumb sucking

May 1, 2013
Babies are born with a sucking reflex, and they quickly discover that sucking provides nourishment and a sense of well-being.

New evidence points to oral complications in pediatric care


Babies are born with a sucking reflex, and they quickly discover that sucking provides nourishment and a sense of well-being. They learn naturally that they can prolong or substitute for that feeling by sucking on something else, such as a thumb, finger, or pacifier. Non-nutritive sucking is soothing and therapeutic, an easy fix for boredom, anxiety, or tiredness. Children usually stop spontaneously in early childhood, once sucking is no longer the primary way they are fed.1

These are not the only reasons non-nutritive sucking is good for a child. A 2009 article in American Family Physician summarized the benefits. Pacifiers can provide analgesic effects. They're recommended for pain relief in newborns and for infants undergoing procedures such as immunizations and venipuncture. They've been credited with shortening hospital stays for preterm infants. Studies have also shown pacifier use is related to a reduction in the risk of sudden infant death syndrome (SIDS). The American Academy of Pediatrics, the article says, even recommends nighttime pacifiers for that purpose.2

There are many potential complications, however, especially with prolonged or too-frequent use. Non-nutritive sucking can lead to delayed establishment of breastfeeding immediately after birth, as well as shorter duration and lower prevalence of breastfeeding. Use of pacifiers after six months of age is implicated in acute otitis media (AOM). When babies suck too hard or too often on a pacifier, it can alter their nasopharyngeal function.

Unsanitary pacifiers and fingers can be a vector of infection, leading to more illness in general. If a baby also has reduced antibody protection because of decreased duration of breastfeeding, one can see the problem.3 Non-nutritive sucking that continues beyond age 6, of course, is implicated in orthodontic complications.

The bottom line is that moderate pacifier use during sleep is beneficial and should not be discouraged in the first six months of life, with care taken that it is not frequent enough to interfere with breastfeeding establishment. Experts also say children should be weaned from pacifiers in the second six months of life because of the problems listed above.4

New information about pacifier use and thumb sucking came out in 2012. Studies conducted at five different universities and published last year by Niedenthal et al in Basic and Applied Social Psychology5 looked at negative emotional consequences of non-nutritive sucking. Do pacifiers, asked the researchers, disrupt facial mimicry in the user, and are they therefore associated with compromised emotional development? When a caregiver smiles at a baby, in other words, the baby should be learning to smile back, and to eventually learn by watching expressions whether the caregiver is happy or angry, bored, or engaged. When the baby is able to fully mimic the expressions, it furthers his or her emotional development and competence. If the baby's mouth is busy with a pacifier instead, he or she can't do much mimicking.

One of the studies recorded facial mimicry in children and discovered that long-term pacifier use was associated with reduced mimicry in boys. The two others, which questioned young adults, found that emotional intelligence in adult males was lower for boys who had used pacifiers. None of the studies found this consequence in females.

Babies' ability to read and mimic facial expressions had previously been shown to be important in the development of empathy.6 The lack of an ability to mimic, on the other hand, had previously been shown to compromise emotional response and the ability to accurately read others' facial expressions.7

The researchers in the Niedenthal study wanted to investigate whether a pacifier, in monopolizing the muscles around the mouth, would interrupt the baby's ability to copy its caregivers' facial expressions. Because the processing of facial expression is important to emotional development, they theorized, use of a pacifier could have long-term negative consequences.

They also looked at thumb sucking, but did not expect the results to be the same, since thumb sucking is seen as a more negative behavior and more likely to be done when the child is alone; also because thumb sucking is controlled by the child, and pacifier use by the adult. They expected the findings would be different between boys and girls, since girls have been shown to develop emotional competence more quickly than boys.

During the first study, 106 children with an average age of seven years, three months, were shown movies in which facial expressions changed gradually from smiles to frowns, or vice versa. The second study involved 167 university students, 92% of whom had used a pacifier in childhood for nearly two years. They filled out questionnaires that assessed their ability to see events from the viewpoint of other people. In the third study, 428 university students filled out the same questionnaires, but in addition they were administered the Adolescent Short Form of Trait Emotional Intelligence Questionnaire. (Higher scores on this test indicate greater emotional intelligence.)

Niedenthal and colleagues were able to confirm most of their hypotheses. Their findings showed that since the babies were hampered in facial mimicry because their mouths were hidden and occupied by a pacifier, their emotional growth and eventual competence were compromised.

Interestingly, thumb sucking did not show the same effect. In the first study, of young children, thumb sucking was shown to be positively associated with facial mimicry. In the second and third studies, no long-term effects on emotional competence were found because of thumb sucking.

The researchers concluded (as they usually do) that more research is needed on the subject. "We see this set of studies," they said, "as a first attempt to address the negative consequences of such inhibition early in development when emotional skills are being set in place."

As dental hygienists, we need to add this new information to our personal FAQ file, so that when parents ask about pacifiers and thumb sucking, we have the most current information for them. RDH


1. www.wikipedia.com, Accessed 1-16-13.
2. Sexton S, Natale R. Risks and benefits of pacifiers. Am Fam Physician. Apr. 15, 2009;79(8):681-685.
3. Adair SM. Pacifier use. Pediatric Dentistry. 2003;449-458.
4. Sonnby-Borgstrom M. Automatic mimicry reactions as related to differences in emotional empathy. Scandinavian Journal of Psychology. 2002;43:433-443.
5. Niedenthal PM, Augustinova M, Rychlowska M, Droit-Volet S, Zinner L, Knafo A, Brauer M. Negative relations between pacifier use and emotional competence, basic and applied social psychology. 2012; 34(5):387-394.
6. Sonnby-Borgstrom M. Automatic mimicry reactions as related to differences in emotional empathy. Scandinavian Journal of Psychology. 2002; 43:433-443.
7. Hennenlotter A, Schroeder U, Erhard P, Catrop F, Haslinger B, Stoecker D, Ceballos-Baumannn AO. A common neural basis for receptive and expressive communication of pleasant facial affect. NeuroImage. 2005;26:581-591.

CATHY HESTER SECKMAN, RDH, has written on dental topics for 26 years. She speaks on pediatric issues, and works clinically in a pediatric practice. She is also an indexer and a novelist.

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