If the carbohydrate in the diet consisted of rice, bread and grain food, the teeth decayed and disintegrated quickly. If the carbohydrate was in the form of poi and sweet potato, defective teeth do not decay and eventually become hard and smooth. We regard the role of bacteria as relatively unimportant, since their effect upon teeth may be controlled by diet.
Dr Martha R. Jones
Captain Cook landed in Hawaii in 1778. He found people who were tall, brown skinned with great muscular strength and broad dental arches. Dental decay was rare or unknown. The principal food crops were taro, usually consumed as poi, and sweet potato, which together made up 60 to 75% of the diet. Coconuts, fruit, fish and shellfish made up most of the remainder. Milk and grain foods were unknown.
Fast forward to the 1920’s. Rice, bread and other grain products had largely replaced taro and sweet potatoes as the staple. Early childhood caries (ECC) were rampant amongst the breast-fed children of plantation labourers. Tooth decay was so aggressive that it was frequently necessary for infants to have teeth removed before they reached their first birthday. By 2 years, almost 100% of those children were affected. Almost all of the plantation babies had pitted, soft chalky teeth from which the enamel was sometimes completely absent. The decay progressed in broad lines across the teeth, rather than in pits and fissures, and was associated with growth “spurts”. Active children who played outside in the sun were more susceptible. Rampant decay rarely occurred in those who did not eat grains, but instead consumed the traditional taro and sweet potatoes.
The children appear to have been grossly deficient in calcifying minerals, especially calcium, and possibly phosphorus and magnesium. A study was undertaken whereby 11 babies were provided diets rich in calcium, phosphorus and vitamins with supplementation by a quart of cow’s milk per day for nine months, together with fruit vegetable, egg and meats. When consumed with a diet where 30 to 40% of the calories came from grains, this supplementation did not prevent the rampant decay. However, when taro and sweet potatoes were substituted for the grains in the diet, rampant caries was prevented in 39 out of the 42 (or 93%) of the infants.
It apparently matters not whether the teeth are crooked or well spaced; whether the oral hygiene is practiced or not; whether the tooth structure is hypoplastic or perfect, or whether there is even any enamel present. We have never known a case of active caries in a normal adult who obtains 60 to 70% of the calories of his diet from poi and sweet potatoes.
Jones, M.R., and others, 1934: Taro and sweet potatoes versus grain foods in relation to health and decay in Hawaii”, The Dental Cosmos, 74, 395-409. [Link]