Pacifier- and digit-sucking habits.

ABSTRACT

During the 20th century, the incidence of artificial sucking habits has increased while digit sucking has relatively decreased. This phenomenon is of concern to parents and clinicians as well as those involved in preventive health care. Greater harm to the dentition is caused by digit sucking than artificial sucking, both because the thumb acts as a lever, forcing the maxilla forward, and because the habit is harder to stop. Artificial sucking habits, however varied, are common in the industrialized world of today, the main reason being that breast-feeding is reduced both in intensity and in duration. Crossbite and tendencies to crossbite should be carefully checked in two to three year olds with artificial sucking habits.

Dr. Erik Larsson from Oslo University, Norway, has studied these problems for more than 30 years and has written several articles about his investigations. With Dr. Samir Bishara of the University of Iowa as editor, Dr. Larsson published his results and ideas in a book entitled The Influence of Oral Habits on the Developing Dentition and Their Treatment: Clinical and Historical Perspectives. (1) (See www.thumbandpacifiersucking.com). The following article is taken from sections of this book.

Keywords: breast feeding; cephalometry; fingersucking; malocclusion; pacifiers; sucking behaviour

RESUME

Au cours du 20e siecle, l'incidence des habitudes de succion artificielles a augmente alors que la succion des doigts a relativement diminue. Ce phenomene presente un interet special pour les parents et les cliniciens ainsi que pour les personnes qui travaillent en soins de sante preventifs. La succion des doigts cause un plus grand tort a la dentition parce que le pouce agit comme un levier, poussant le maxillaire vers l'avant, et parce que l'habitude est difficile a perdre. Les habitudes de succion artificielles variees sont communes dans le monde industrialise d'aujourd'hui, la principale raison etant que l'allaitement maternel a diminue en intensite et en duree. L'occlusion croisee et les tendances a l'occlusion croisee devraient etre soigneusement verifiees chez les enfants de deux a trois ans qui ont des habitudes de succion artificielles.

Le Dr Erik Larsson de la Oslo University, a Norway, a etudie ces problemes depuis plus de 30 ans et a ecrit plusieurs articles sur ses recherches. Avec le Dr Samir Bishara de la University of Iowa comme editeur, le Dr Larsson a publie ses resultats et ses idees dans un livre intitule The Influence of Oral Habits on the Developing Dentition and Their Treatment: Clinical and Historical Perspectives. (1) (Voir egalement www thumbandpacifiersucking.com). Cet article est un extrait de son livre.

HISTORY

FOR UNCOUNTED MILLENNIA, HUMANS RAISED THEIR children with mothers breast-feeding their children for two to three years. On-demand breast-feeding was most common; the child was allowed to suckle when and as much as it wanted. In some cultures, the use of wet nurses was also common.

In the mid-18th century, William Hunter, a Scottish doctor, emphasized the need for mothers to breast-feed their children to minimize the risk of developing "milk fever." This is now scientifically described as "stagnation mastitis" and often referred to as "caked breast."

In more modern and industrialized societies, women started to schedule breast-feeding in set periods of four to six times per day and also reduced the length of time the baby was allowed to breast-feed. This in turn increased the child's need for additional sucking time to satisfy the sucking urge. In some cultures, it was common to provide the child with a knotted strip of cloth that contained honey or other foods for the child to suck on. The concept is similar to the use of the modern pacifiers introduced in the second half of the 19th century.

In this article, we attempt to provide an overview of digit- and pacifier-sucking habits, their etiology, and their effect on the developing dentition.

PREVALENCE AND DURATION

The prevalence of non-nutritive sucking habits varies in different cultures as well as within the same culture at different time periods. (1)

Numerous studies have examined initial sucking habits in young children. (2-13) Especially interesting are Larsson's studies from a small county in southwest Sweden where the sucking habits of children born in this region have been recorded over a long period (table 1). As can be seen from this table, initial pacifier sucking has increased and digit sucking has decreased.

When comparing the initial and continuing sucking habits of 60 three-year-old girls in seven different areas of the world, Caglar et al. (2) registered a considerable difference in both digit and pacifier sucking. The digit-sucking prevalence data were rather low except for Iowa in the United States where half of the girls started a digit-sucking habit. Initial pacifier sucking was fairly popular in most areas with a prevalence of up to 70%-80% in Sweden and Brazil. The exception was in Nigata, Japan, where none of the girls had started a pacifier sucking habit.

Children who start digit sucking often have greater problems abandoning the habit than do pacifier suckers. Larsson (3) found that half the children who started a digit-sucking habit still sucked at the age of seven. Similar results have recently been shown by Bishara et al. (4) Girls seem to have more problems stopping than do boys. (3)

THUMB AND FINGER SUCKING

Etiology and development of digit sucking

The exact etiology of digit-sucking habits is still not clear but is thought to primarily satisfy the sucking that infants need. There are several different hypotheses regarding the etiology of prolonged finger sucking.

Psychoanalytic theory

Freud described his concept of the etiology of thumb sucking by stating the following: "It is clear that the action of the thumb sucking child is determined by the fact that it seeks a pleasure which has already been experienced and is now remembered." He then adds, "The first and most important activity in the child's life, the sucking from the mother's breast (or its substitute), must have acquainted it with this pleasure. We would say that the child's lips behaved like an erogenouzs zone." (15)

Basically, the Freudian approach considered the sucking mechanism as an instinct. Freud also considered thumb sucking as a form of infantile sexuality, beginning initially as a reflex mechanism, but continuing when the infant finds that it can derive pleasure beyond its normal nutrient sucking needs. According to Freud's theories, the oral zone is the first erogenous zone within which the baby could feel satisfaction. The oral zone, the sucking urge, as well as the need for safety and satisfaction by getting food, are closely related. If this urge is not satisfied--because of insufficient breast-feeding, for example--a digit-sucking habit can emerge. Also according to Freud, prolonged thumb sucking is a symptom of a mental disturbance. He talks about regression into the habit and fixation of the habit.

Learning behaviour theory

According to this theory, the sucking habit provides the baby with satisfaction and reduces anxiety and therefore a prolonged thumb sucking is not a symptom of a severe mental problem. However, the sucking habit itself can become a problem if the child cannot stop the habit as it gets older. More specifically, the thumb sucking may cause the child to be insecure and may interfere with social interactions.

Unphysiologic reduction of breast-feeding

An alternative but complementary theory has been suggested by Larsson and Dahlin. (16) Simply stated, if the sucking need is not satisfied at the breast, the infant's fingers will be used as a substitute. Early in life, the habit will be stimulated by hunger or if the child is tired, unhappy, idle, or under stress. (17) Larsson and Dahlin (16) pointed out the extreme differences in prevalence and duration of breast-feeding between the contemporary rearing of babies and that of earlier societies. In earlier societies as well as among some traditionally reared people still living today, the children were breast-fed on demand for two to three years.

Finger sucking habits and malocclusion

A number of studies (5,6,18-20) indicated an increased incidence of malocclusion in individuals with persistent sucking habits when compared with children with no history of the habit. According to Bowden, (6) the proportion of Skeletal Class II relationships was higher among the digit suckers (40%) and dummy suckers (35%) than among the non-suckers (29%). In addition, there was a significant increase in the incidence (62%) of the Skeletal Class II relationship in children where digit sucking persisted until eight years of age. (6)

[FIGURE 1 OMITTED]

The position of the fingers while sucking influences the direction of the displacement of the anterior teeth. There is typical thumb sucking with the ventral side of the finger facing the palate and maxillary incisors. A second way is sucking with the dorsal side of the finger facing upward (see figure 1). Here, if the finger or fingers are passive, the effect would be similar to sucking on a pacifier but this type of finger sucking is relatively less common.

Effect of the finger habits on the dentition

Dental changes

A typical clinical picture of a persistent finger habit includes anterior open bite, as well as an increased overjet, that are the result of the labial inclination of the upper incisors. (6,18-20) The lingual inclination of the lower incisors, although suggested in the literature, is not necessarily the typical picture. Subtelny and Subtelny, (21) as well as Larsson (19) and Moore (20) in their cephalometric studies, found that the lower incisors' inclination in digit suckers was not significantly different from that in non-suckers. The prevalence of a transverse discrepancy increases markedly among children who continue the habit vigorously beyond two or three years of age. (7)

Cephalometric changes

Larsson, in a series of longitudinal studies, evaluated a group of Swedish children who had persistent finger habits until nine years of age. (19,22,23) He found significant maxillary incisor protrusion and upward tipping of the palatal plane with an anterior displacement of the maxilla (see figure 2a). In the children who discontinued the habit between 9 and 12 years of age, there was "uprighting"--the proclination/inclination was reduced--of the maxillary incisors and a progressive closing of the anterior open bite. At 16 years of age, these children displayed upper lips that were more anteriorly positioned relative to the control group with maxillary apical bases displaced anteriorly. The upward tilting of the palatal plane remained (see figure 2b).

[FIGURE 2A OMITTED]

[FIGURE 2B OMITTED]

Treatment

The effect of prolonged digit sucking is often considerable and the need for orthodontic treatment often high. Attempts to stop a digit-sucking habit should be made when the patient has a post-normal molar relationship or is developing in that direction. There are, of course, also psychological reasons for stopping a sucking habit. A 10-year-old digit sucker is normally embarrassed because of the habit. If the patient wants to stop a digit-sucking habit and the effects are mainly limited to the anterior part of the dentition, a removable plate with a palatal crib can be used. The acrylic should be relieved palatal to the incisors to allow them to retrocline when the habit ceases. A fixed palatal arch with a crib can also be used and sometimes is more effective because it eliminates the need for the patient's cooperation. (1) If a child with prolonged digit-sucking habit is treated with a fixed appliance, the child's mental health should be carefully observed. (For more information, see Larsson.) (1)

PACIFIER SUCKING

Etiology and development of pacifier sucking

The etiology of a pacifier-sucking habit is probably the same as for finger sucking. For millions of years, children had unrestricted breast-feeding for the first two to three years of life. More recently, on-demand breast-feeding has been replaced by more strictly scheduled breast-feeding for a few months, supplemented and/or replaced by bottle feeding.

As can be seen from table 1, there is a negative relationship between the prevalence of initial pacifier-sucking habit and initial digit sucking. The figures in table 1 support the belief that pacifier sucking may often prevent the child from developing a thumb-sucking habit.

This hypothesis is strongly supported from the results of a study by Zadik et al. (8) See also another relevant study by Larsson. (9) In the Zadik et al. study, parents and nursery staff in one kibbutz in Israel were instructed not to use the pacifier while parents and staff in another kibbutz were given the opposite recommendation. In the kibbutz where pacifiers were recommended, about 70% of the children started to suck a pacifier and a few became digit suckers. In the other kibbutz where pacifiers were prohibited, the pacifier suckers were few but the thumb suckers were about five times as many as in the first kibbutz.

Obviously, if the child gets a suitable pacifier at a young age, it will probably develop a pacifier-sucking habit. If not, the risk that the child will become a digit sucker will increase considerably. (8,9) (See table 1.)

Pacifier sucking and breast-feeding

Pacifier sucking has had a bad reputation throughout most of the 20th century and the habit was actually condemned at the beginning of the 1900s. Recently, several studies from "Baby-Friendly Hospitals" have reported significant associations between pacifier use and early weaning. (24-28) The World Health Organization recommends avoiding the early use of pacifiers. (29) However, Kramer et al. in a comprehensive study concluded that "pacifier use is a marker of breastfeeding difficulties or reduced motivation to breastfeed, rather than a true cause of early weaning." (30)

Larsson also questioned the WHO recommendation. (1) In his material, initial pacifier sucking increased from 55% in 1971 to 72% 1997. On the other hand, during the same period, breast-feeding at six months of age increased from 4% to 67%.

Pacifier sucking and malocclusion

Effects of pacifier sucking on the primary dentition 

Since pacifiers are normally used before the teeth have erupted, they may hinder the full eruption of the primary incisors as well as the growth of the alveolar processes, resulting in an anterior open bite (see figure 3). In those rare cases when the child still sucks a pacifier at the time of the eruption of the permanent incisors, the anterior open bite can be significant. Sometimes several pacifiers are tied together with one in the mouth and the others hanging outside (see figure 4). This extra weight can act as a lever, affecting the dentition in a similar way as digit sucking.

In most children, the use of the pacifier is discontinued by three or four years of age and incisal contact is established in a relatively short time. Also, in older children, a spontaneous correction often occurs. (See figure 5.)

Effects on the posterior occlusion 

Several studies (7,10,11,18) have revealed an increased incidence of posterior crossbite in the primary dentition in pacifier-sucking children. The prevalence of posterior crossbite among three-to-four-year-old pacifier suckers from the county of Skaraborg in southwest Sweden rose from 13% to 20% between 1975 and 1990. The incidence of crossbite was especially high in girls, 26%. (10) (See figure 6.)

A probable reason for the correlation between pacifier sucking and crossbite is that when the teat of a pacifier is kept in the mouth for extended periods, changes will occur in the surrounding tissues. The tongue will occupy a lower position in the anterior part of the mouth, reducing the palatal support of the upper primary canines and molars against the pressure of the cheeks. The tongue will exert increased lateral pressure on the lower canines and first molars. The lack of palatal support from the tongue will result in a narrower upper arch, and the pressure of the tongue will widen the lower arch. Both these changes act synergistically to create a transverse disharmony that will increase the tendency for a posterior crossbite to develop. (11)

In a longitudinal study, Larsson followed 60 consecutively born girls from the Falkoping area in Sweden. (9) In this prospective study, parents were informed about the risk of developing a crossbite with the use of the pacifier and were asked to reduce the "in-the-mouth time" of the pacifier. The findings from the study indicated that only 2 of 39 girls (5%) who were still pacifier-suckers at three years of age had developed a posterior crossbite.

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

[FIGURE 6 OMITTED]

These results suggest that it is possible to significantly reduce the risk of developing a crossbite in pacifier suckers by asking the parents and the staffs of nurseries to reduce the time the pacifier is in the child's mouth. Further evaluation of these cases has also indicated that in some instances a spontaneous improvement can take place if the sucking habit stops.

Can these results be explained? According to Proffit, (31) pressure against the teeth has to exist for at least 6 hours out of 24 to result in tooth movement. Differences in the number of hours per day that children spend with the pacifier in the mouth, plus the sucking intensity, could probably explain why some children develop a posterior crossbite more than others.

Treatment

Need and timing of treatment

Today, children often place the pacifier in their mouth almost full-time. It should be pointed out that in these cases, the pacifier seems to act as a substitute for non-nutritive feeding or unrestricted breast-feeding of earlier practices. Professionals dealing with pacifier-sucking habits should attempt to prevent the child from using the pacifier incorrectly by educating the parents. Such information can minimize many problems. The need for physical contact between the mother and the baby should also be stressed.

From an orthodontic perspective, the main reason for allowing pacifier sucking is that it reduces the incidence of digit-sucking habits. If children are forced to break the pacifier-sucking habit at an early age (before two or three years of age), there is a risk that they will develop a digit-sucking habit instead. (3) This risk is greater for girls. One should therefore have good reasons for trying to break a pacifier-sucking habit early.

Factors to consider

1. In most cases of pacifier sucking, the anterior open bite may close spontaneously when the habit terminates.

2. If the difference between the upper intercanine arch widths and that of the lower is less than 3 mm, the risk of posterior crossbite developing should be considered high and the parents should be encouraged to reduce the pacifier-sucking time. (7)

3. The transverse relationship between the dental arches should be evaluated in pacifier-sucking children at the age of two to three years. If interfering contacts between the primary canines exist, the parents should be instructed to reduce the "in-the-mouth time" of the pacifier. One idea is to let the child use the pacifier only for a short time after meals and when going to sleep. Occlusal equilibration might need to be performed to eliminate the interfering contacts.

4. If a unilateral crossbite develops in combination with a forced lateral guidance of the mandible, this should be treated as soon as possible by equilibrating the primary dentition to adjust the occlusion or by the use of an expansion appliance.

5. In those rare cases in which it is decided to try to break a pacifier-sucking habit, a positive reinforcement method is recommended. With this approach, the therapist, the child, and the parents should decide to break the habit on a special day some months ahead. A suitable day to choose is the last school day before a holiday. The child selects four or five small presents for the parents to buy. On the appointed day, the child brings all his/her pacifiers to the therapist. As an encouragement, the child receives one of the presents bought earlier each day for the next four to five days.

CONCLUSION

Artificial sucking habits, however varied, are common in the industrialized world of today, the main reason being that breast-feeding is reduced both in intensity and in duration. Crossbite and tendencies to crossbite should be carefully checked in two to three year olds with artificial sucking habits. However, greater harm to the dentition is caused by digit sucking, both because the thumb acts as a lever, forcing the maxilla forward, and because the habit is harder to stop.

REFERENCES

1. Larsson E. The influence of oral habits on the developing dentition and their treatment: clinical and historical perspectives. 2nd ed. Edited by S. Bishara. [n.p.] Sweden: CELA Grafiska; 2003. Available from: www.thumbandpacifiersucking.com.

2. Caglar E, Larsson E. Andersson EM, Hauge MS, Ogaard B, Bishara S, Warren J, Noda T, Dolci GS. Feeding, artificial sucking habits, and malocclusions in 3-year-old girls in different regions of the world. J Dent Child (Chic). 2005;72(1):25-30.

3. Larsson E. Dummy- and finger-sucking habits with special attention to their significance for facial growth and occlusion. 1. Incidence study. Swed Dent J. 1971;64(10):667-72.

4. Bishara SE, Warren JJ, Broffitt B, Levy SM. Changes in the prevalence of nonnutritive sucking patterns in the first 8 years of life. Am J Orthod Dentofacial Orthop. 2006;130(1):31-6.

5. Traisman AS, Traisman HS. Thumb- and finger-sucking: a study of 2,650 infants and children. J Pediatr. 1958;52(5):566-72.

6. Bowden BD. A longitudinal study of the effects of digit- and dummysucking. Am J Orthod. 1966;52(12):887-901.

7. Modeer T, Odenrick L, Lindner A. Sucking habits and their relation to posterior cross-bite in 4-year-old children. Scand J Dent Res. 1982;90(4):3238.

8. Zadik D, Stern N, Litner M. Thumb- and pacifier-sucking habits. Am J Orthod. 1977;71(2):197-201.

9. Larsson E. Sucking, chewing, and feeding habits and the development of crossbite: a longitudinal study of girls from birth to 3 years of age. Angle Orthod. 2001;71(2):116-9.

10. Ogaard B, Larsson E, Lindsten R. The effect of sucking habits, cohort, sex, intercanine arch widths, and breast or bottle feeding on posterior crossbite in Norwegian and Swedish 3-year-old children. Am J Orthod Dentofacial Orthop. 1994;106(2):161-6.

11. Lindsten R, Larsson E, Ogaard B. Dummy-sucking behaviour in 3-year-old Norwegian and Swedish children. Eur J Orthod. 1996;18(2):205-9.

12. Larsson E. Dummy- and finger-sucking in 4-year-olds. Swed Dent J. 1975;68(6):219-24.

13. ______. De initiala napp-och fingersugningsvanornas frekvens. Tandlakart.1983; 75:695-9.

14. Larsson E, Ogaard B, Lindsten R. Dummy- and finger-sucking habits in young Swedish and Norwegian children. Scand J Dent Res. 1992;100(5):292-5.

15. Freud S. Three contributions to the sexual theory. New Yori: Journal of Nervous and Mental Disease Publishing Co.; 1910.

16. Larsson EF, Dahlin KG. The prevalence and the etiology of the initial dummy- and finger-sucking habit Am J Orthod. 1985;87(5):432-5.

17. Oral motor behavior: impact on oral conditions and dental treatment. Workshop proceedings, May 16-17, 1979, co-sponsored by the National Institute of Dental Research. [Bethesda (MD)]: U.S. Dept. of Health, Education, and Welfare, Public Health Service, National Institutes of Health; 1979.

18. Warren JJ, Slayton RL, Bishara SE, Levy SM, Yonezu T, Kanellis MJ. Effects of nonnutritive sucking habits on occlusal characteristics in the mixed dentition. Pediatr Dent. 2005;27(6):445-50.

19. Larsson E. Dummy- and finger-sucking habits with special attention to their significance for facial growth and occlusion. 4. Effect on facial growth and occlusion. Swed Dent J. 1972;65(12):60534.

20. Moore MB, McDonald JP. A cephalometric evaluation of patients presenting with digit sucking habits. Br J Orthod. 1997;24(1):17-23.

21. Subtelny D, Subtelny J. Oral habits--studies in form, function, and therapy. Angle Orthod. 1973;43(4):349-383.

22. Larsson E. Dummy- and finger-sucking habits with special attention to their significance for facial growth and occlusion. 5. Improvement of malocclusion after termination of the habit. Swed Dent J. 1972;65(12):635-42.

23. ______. Dummy- and finger-sucking habits with special attention to their significance for facial growth and occlusion. 7. The effect of earlier dummy- and finger sucking habit in 16-year-old children compared with children without earlier sucking habit. Swed Dent J. 1978;71:2333.

24. Barros FC, Victora CG, Semer TC, Filho ST, Tomasi E, Weiderpass E. Use of pacifiers is associated with decreased breast-feeding duration. Pediatrics. 1995;95(4):497-9.

25. Righard L, Alade MO. Sucking technique and its effect on success of breastfeeding. Birth. 1992;19:185-9.

26. Aarts C, Hornell A, Kylberg E, Hofvander Y, Gebre-Medhin M. Breastfeeding patterns in relation to thumb sucking and pacifier use. Pediatrics. 1999;104(4):1-10.

27. Gale CR, Martyn CN. Dummies and the health of Hertfordshire infants, 1911-1930. Soc Hist Med. 1995;8(2):231-55.

28. Clements MS, Mitchell EA, Wright SP, Esmail A, Jones DR, Ford RP. Influences on breastfeeding in southeast England. Acta Pediatr. 1997;86(1):51-6.

29. WHO/UNICEF. Protecting, promoting, and supporting breast-feeding: the special role of maternity services. Geneva, Switzerland: World Health Organization; 1989

30. Kramer MS, Barr RG, Dagenais S, Yang H, Jones P. Ciofani L, Jane F. Pacifier use, early weaning, and cry/fuss behavior: a randomized controlled trial. JAMA. 2001;286(3):322-6.

31. Proffit WR. On the aetiology of malocclusion. Br J Orthod. 1986;13(1):1-11.

by Erik Larsson* and Samir Bishara[dagger]

* Dr. Larsson graduated from the dental faculty, Karolinska Institute, Stockholm, Sweden, 1963 and obtained his doctorate in odontology in 1973. In 1990, he was appointed Associate Professor at Lund University and in 1999 was appointed Professor II at the University of Oslo, Norway. Since 1980, he has also been head of the orthodontic clinic in Falkoping, Sweden.

[dagger] Dr. Bishara has been professor of orthodontics at the University of Iowa since 1976. He obtained his dental and specialty degrees from Alexandria University, Egypt, and the University of Iowa.

                      % initial  % initial
Year          Sample  pacifier   digit
born          size    sucking    sucking

1961 (3)        920   45         30
1967 (12)     3,563   55         22
1980-82 (13)    280   72         23
1986 (14)       171   70         18
1995-97 (9)      60   72         10

Table 1. Initial pacifier and digit sucking in Skaraborg County, Sweden