To investigate the frequency of tongue-thrust swallowing in a breast-fed population and in a bottlefed population, 110 Navajo and 149 non-Indian children within the 7-to 13-year age range were individually tested. Frequency of tongue-thrust swallowing was 65% in the breast-fed (Navajo) sample and 81 % in the predominantly bottle-fed (non-Indian) sample. This difference was statistically significant. On the basis of a parent questionnaire, two subgroups were formed from the predominantly bottle-fed (non-Indian) sample. They were composed of a) 59 totally bottle-fed non-Indian children and b) 31 nonIndian children who had been breast-fed four months or longer. No statistical difference in terms of tongue-thrust swallowing was found between the two subgroups. However, a statistical difference was found when each of the two subgroups was compared separately with the breastfed Indian sample. Statistically more tongue-thrust swallowing existed in a totally bottle-fed group and in a group which had been breast-fed from four to twelve months than in the Navajo group which had been breast-fed from 18 to 36 months. The relationship between method of feeding in infancy and undue prolongation of tonguethrust swallowing clearly merits further investigation.
Stanley, E. O., & Lundeen, D. J. (1980). Tongue Thrust in Breast-Fed and Bottle-Fed School Children: A Cross-Cultural Investigation, International Journal of Oral Myology, 6 (1), 6-17.