The hypothesis that nipple pain and damage results from tongue friction, pinching, or compression lacks biological plausibility

It's still widely believed that nipple pain and damage is caused by tongue friction, pinching or compression

For many years, it's been believed that abnormal infant tongue shape and movement in breastfeeding due to restricted infant oral connective tissues causes a friction burn or graze of the nipple, despite lack of supporting evidence.

The hypothesis that maternal nipple pain and damage results from abnormal tongue movement which pinches or rubs the nipple against the palate or upper alveoloar ridge has resulted in widespread overtreatment of breastfeeding infants with frenotomy and bodywork exercises.1-3 4-6

But this hypothesis is not supported by

• Ultrasound or magnetic resonance imaging of the biomechanics of infant suckling

• Nor by anatomic dissection of the infant floor of mouth fascia.7-9

The research shows that nipple pain and damage is not caused by the tongue

When using the hypothesis that nipple pain and damage is due to tongue movements, nipple pain is attributed to

• Changes in tongue contour and movement, which are attributed to infant oral connective tissue tightness. But these changes in tongue contour and movement are more accurately interpreted as changes in tongue shape in response to variable intra-oral breast tissue volumes.12-14

• Innately high vacuum generation.10 11 But an infant reflexly applies high vacuums contextually, in response to difficulty transferring milk (which occurs with high levels of nipple and breast tissue drag). High vacuum generation is most easily explained as a functional response to context, not as an innate or hardwired characteristic.

• Use of pacifiers and bottle teats which alter neural pathways coordinating tongue movement and sucking patterns, resulting in nipple pain. But this theory is also based on misconceptions about the role of tongue in milk transfer. A 2015 systematic review of 14 articles found little evidence of a causal relationship between pacifier and bottle teat use, and nipple confusion.15-17

The hypothesis that a nipple burn or graze is caused by tongue friction doesn't make pathophysiological sense

A burn or graze caused by friction would present differently to the cracks and ulcers which characterise lactation-related nipple damage.

• A friction burn or graze is likely to cause a broad area of epithelial damage, on the aspect of the nipple which rests against the dorsum of the tongue during breastfeeding.

• But nipple cracks and ulcers are commonly located at the base of the nipple and on the nipple face, consistent with epithelial rupture due to tensile or stretching mechanical forces.

• Fiction burns would also be expected to occur on the surface of the infant tongue, if the friction is enough to cause an epithelial graze or burn on the surface of the nipple. But maternal nipple damage in breastfeeding does not coincide with infant tongue mucosal damage.

Saliva protects infant oral mucosa from friction damage

The mucosa of the infant’s tongue slides with minimal friction against mucosa lining other parts of the oral cavity because of the protective and lubricating effects of saliva, the mucin in saliva, the infant's oral mucin layer, and breast milk.

• The infant’s parotid, submandibular, and sublingual salivary glands secrete saliva from birth, and as do the minor salivary glands which are widely distributed throughout the submucosa of the oral cavity (except on the gingiva and the anterior palate).

• All salivary glands secrete mucin, the predominant constituent of the oral mucous layer.

  • Saliva mucin protects oral epithelial cells from dryness and contains synergistic proteins and peptides which promote cell mitosis and migration.

  • Saliva mucin entraps microparticles, including microorganisms, so that they are suspended and unable to settle into biofilms.

  • Some mucins interact with bacteria, dispersing and selectively destroying them.18

Tongue movement continuously redistributes saliva and saliva mucin over the surface of the nipple-areolar complex and intra-oral breast tissue. Ultrasound and MRI imaging confirm that there is no air in the oral cavity to exert a drying effect during suckling, even when the mother has nipple pain.7

You can find out what causes nipple pain and damage here and here.

References

1. Kapoor V, Douglas PS, Hill PS, et al. Frenotomy for tongue-tie in Australian children (2006-2016): an increasing problem. MJA 2018:88-89.
2. Wei E, Tunkel D, Boss E, et al. Ankyloglossia: update on trends in diagnosis and management in the United States, 2012-2016. Otolaryngology - Head and Neck Surgery 2020:https://doi.org/10.1177%2F0194599820925415.
3. Ellehauge E, Schmidt Jensen J, Gronhoj C, et al. Trends of ankyloglossia and lingual frenotomy in hospital settings among children in Denmark. Danish Medical Journal 2020;67(5):A01200051.
4. Joseph KS, Kinniburg B, Metcalfe A, et al. Temporal trends in ankyloglossia and frenotomy in British Columbia, Canada, 2004-2013: a population-based study. CMAJ Open 2016;4:e33-e40.
5. Dixon B, Gray J, Elliot N, et al. A multifaceted programme to reduce the rate of tongue-tie release surgery in newborn infants: Observational study. international Journal of Pediatric Otorhinolaryngology 2018;113:156-63.
6. Schwerla F, Daake B, Moeckel E, et al. Osteopathic treatment of infants in their first year of life: a prospective multicenter observational study (OSTINF study). Complementary Medicine Research 2021;28(5):395-406.
7. Mills N, Lydon A-M, Davies-Payne D, et al. Imaging the breastfeeding swallow: pilot study utilizing real-time MRI. Laryngoscope Investigative Otolaryngology 2020;5:572-79.
8. Geddes DT, Sakalidis VS. Ultrasound imaging of breastfeeding - a window to the inside: methodology, normal appearances, and application. Journal of Human Lactation 2016;32(2):340-49.
9. Mills N, Keough N, Geddes DT, et al. Defining the anatomy of the neonatal lingual frenulum. Clinical Anatomy 2019;32:824-35.
10. McClellan HI, Geddes DT, Kent JC, et al. Infants of mothers with persistent nipple pain exert strong sucking vacuums. Acta Paediatrica 2008;97(9):1205-09.
11. Geddes DT, Langton DB, Gollow I, et al. Frenulotomy for breastfeeding infants with ankyloglossia: effect on milk removal and sucking mechanism as imaged by ultrasound. Pediatrics 2008;122:e188-e94.
12. Douglas PS, Geddes DB. Practice-based interpretation of ultrasound studies leads the way to less pharmaceutical and surgical intervention for breastfeeding babies and more effective clinical support. Midwifery 2018;58:145–55.
13. Douglas PS, Perrella SL, Geddes DT. A brief gestalt intervention changes ultrasound measures of tongue movement during breastfeeding: case series. BMC Pregnancy and Childbirth 2022;22(94):https://doi.org/10.1186/s12884-021-04363-7.
14. Douglas PS, Keogh R. Gestalt breastfeeding: helping mothers and infants optimise positional stability and intra-oral breast tissue volume for effective, pain-free milk transfer. Journal of Human Lactation 2017;33(3):509–18.
15. Zimmerman E, Thompson K. Clarifying nipple confusion. Journal of Perinatology 2015;35(11):895-99.
16. McClellan HL, Kent JC, Hepworth AR, et al. Persistent nipple pain in breastfeeding mothers associated with abnormal infant tongue movement. International Journal of Environmental Research and Public Health 2015;12:10833-45.
17. Dias JS, Vieira TDO, Vierira GO. Factors associated to nipple trauma in lactation period: a systematic review. Revista Brasileira de Saude Materno Infantil 2017;17(1):27-42.
18. Pan L, Zhang X, Gao Q. Effects and mechanisms of histatins as novel skin wound-healing agents. Journal of Tissue Viability 2021;30:190-95.