Caries, and non-inflammatory atrophy of skeletal and alveolar bones, cementum and dentin, are local manifestations of imbalance in blood and tissue fluids—the former toward the acid end of the equilibrium range; the latter, toward the alkaline. The two diseases do not occur simultaneously, and therefore serve as indicators of nutritional imbalances by means of which more favorable nutritional states may be attained. The exciting cause of caries and odontoclasia is in the medium surrounding the affected tooth, and is believed to be free acid resulting from bacterial activity. Nutritional state is reflected in the oral secretions. When the nutritional balance is optimal, free acid does not occur on tooth surfaces, either because it is not formed or because, if formed, it is rendered inert by oral secretions, regardless of degree of cleanliness of, or character of food debris or type of bacterial flora in, the mouth. In prolonged and extreme cases of acidosis in infants (starvation unto death), solution of enamel may occur in unerupted, bacteria-free teeth. In otherwise ” normal ” individuals, imbalance in blood and tissue fluids toward the acid end of the equilibrium-range may be induced by long continued preponderance of acid-forming and refined foods (grains, flesh, eggs and refined sugar) in the dietary over alkali-mineral-vitamin-rich varieties ( fruits, vegetables, milk, natural cane-juices, etc.). Once initiated, the imbalance may he further accentuated by excessive physical exercise, mental strain, ultraviolet radiation, pregnancy, accelerated rate of growth, development and calcification of skeletal bones, certain glandular dysfunctions, and diseases. Thus a vicious circle is formed, and an increasingly unfavorable nutritional state created, which may manifest itself in many seemingly unrelated ills. Many of the latter—caries, ” common cold,” gastro-intestinal irritations, etc.—are activated by exciting causes which obscure the predisposing factors. The almost universal incidence of caries, and the high and increasing incidences of respiratory, blood-vessel and other systemic diseases of unknown etiology, in the American people, indicate a state of nutritional imbalance in the entire population. Without material change in character, the ” average American diet “—which contains ” adequate ” amounts of calcium, phosphorus and vitamins, and is nearly neutral in potential reaction —could be modified in a number of ways to yield excess of alkali near the indicated optimum value, by more liberal use of green-leaf vegetables and root-tops ; and (or) substitution of the more alkaline types of fruits and vegetables for the less alkaline or acid-forming varieties ; and (or) more liberal use of sorghum and sugar-cane syrups; and (or) increase in the fruitvegetable-milk fraction. Such changes on a national scale would, it is believed, eventually solve the problem of caries and related ills, improve physical well-being, and increase the usefulness and happiness of the American people.
In a subtropical climate with seven to eight hours of sunshine daily, diets consisting essentially of fish, roots, tubers, fruits, vegetables and unrefined sugar-cane
juice were almost universally associated with immunity to dental caries, and with physical and dental development of a high order. Substitutions of polished rice and wheat-flour for taro and sweet potato, and refined sugar for natural sugar-cane juice, were accompanied by physical deterioration, with high susceptibility to caries, and respiratory, blood-vessel and other diseases ; high incidence of skeletal and dental defects in the newborn ; rampant disintegration of newly erupted teeth (odontoclasia) in more than 90 percent of the babies under fifteen months of age; low incidence of rickets ; high urine acidity ; high infant death-rate; and low total- base content and CO2-combining power of blood plasma of so-called normal adults. The ” rice-bread ” diet was comparable to the ” taro-sweet potato ” in character and carbohydrate content, but poorer in minerals and vitamins, though adequate for growth, reproduction and lactation. The two diets differed markedly in potential reaction, a 3000-calorie ” rice-bread ” ration yielding an excess equal to 50 cc. or more of normal acid ; a similar portion of the ” taro-sweet potato,” 100 cc. or more of normal alkali. Addition of orange juice, cod-liver oil, milk (16 to 40 oz.), and fruits and vegetables (1 to 3.5 lbs.), in quantities sufficient to furnish liberal amounts of all known essential nutrients (according to accepted standards) and to render the potential reaction of the diet neutral or slightly alkaline (0 to 20 cc. N alk.), did improve physical well-being and promote growth, but did not prevent caries. Subsequent feeding of taro, sweet potato, fruit, vegetable, natural cane- juice concentrate and milk, to many babies whose parents had the high-grain diet for six years or more, was accompanied by marked improvement in physical development of the babies, increased resistance to respiratory, skin and other diseases ; reduction in infant death-rate from a high figure to zero (last 16 months) ; and arrest of odontoclasia. The excess of alkali, from a 1,100-calorie diet, was approximately equal to 45 cc. of N solution, or about 2 cc. per pound of child weight. Immunity to caries was observed in various localities and climates on many types of diet—rich or poor in grains ; high or low in sugars ; with or without milk, citrus fruit and cod-liver oil ; and with or without oral hygiene. There was, however, a relationship between types of foods and caries immunity. A caries-preventive factor was obviously present in fruits, vegetables and unrefined cane-juices. Neither the quantities consumed, however, nor the absolute amounts of any of their known constituents, bore a constant relationship to caries immunity, but the alkali excess furnished exclusively by the fruits, vegetables and cane-juices did. The greater the consumption of grains and other acid-forming foods (flesh and egg), the larger were the proportions of green leaf and other alkali-mineral-vitamin rich varieties. Also, the hotter the climate and longer the hours of sunshine, the larger were the proportions of fruits, vegetables and natural sugars in the dietary, and the higher its potential alkalinity. The optimum potential alkalinity of an otherwise well constituted 3000-calorie diet was calculated to range from 75 to 125 cc. of N solution—the absolute amount varying with climate, exposure to sunshine, activity, nutritional state of the individual, etc. Diets excessively rich in fruits, vegetables and cane-juices, and yielding a larger than optimum alkali excess, regardless of mineral and vitamin contents, were associated with caries- free but loose teeth, resulting from non-inflammatory atrophy, usually of alveolar bone—sometimes of roots. These findings indicate that the potency of the caries- preventive bone-destructive factor in fruits, vegetables and cane-juices parallels or depends upon their yield of excess of alkali.
Dogs and humans reacted alike in respect to effects on bones and teeth of changes in the acid/base balance of high-carbohydrate, growth-promoting diets. Successive litters born to bitches on imbalanced diets showed, at birth, increased incidence of skeletal and dental defects and increased susceptibility to subsequent dietary faults. Accelerated calcification of skeletal bones (recovery from rickets or mineral deficiency resulting from nutritional imbalance) was accompanied by rampant disintegration of newly erupted teeth of both babies and puppies. In the latter (experimental), the enamel crowns remained intact during profound retrograde changes in skeletal and alveolar bones, cementum and dentin, in some instances the dentin of crowns and roots having been completely resorbed. Histologic examination of unerupted teeth (obtained at autopsy), of both babies and puppies, revealed unlike reactions of enamel and dentin-forming mechanisms, and like reactions of dentin-cementum and bone-forming mechanisms, to the same nutritional fault. Conditions that were favorable for development of enamel were less favorable, or unfavorable, for development of bone, dentin and cementum, and vice versa. In cases of extreme nutritional imbalance toward the acid side (fatal starvation in infants), skeletal bones and dentin, though low in mineral content, were structurally well formed, while enamel (unerupted teeth) was highly disorganized, apparently by solution of inorganic constituents, though there was no evidence of bacterial invasion of tooth crypts. In cases of rickets and osteogenesis imperfecta, the reverse was true—extraordinarily well-formed enamel and poorly formed bone and dentin. Other phenomena observed in dogs on experimental diets were : (a) pulp stones in teeth of newborn puppies ; (b) resorption of alveolar bone, cementum and dentin during excessively alkaline diet-periods, and repair of resorbed areas with haversian bone during acid or neutral periods ; (c) separation, in unerupted teeth, of the layer of ameloblasts from underlying enamel matrix, by wide bands of connective tissue, without any apparent interference with calcification of the matrix; (d) convulsions and death following repeated shifts in the acid/base balance of the diet.
References: J. Am. Den. Assoc., 1927, 1928; Am. J. Physiol., 1927; J. Den. Res., 1930 ; Den. Cosmos, 1930, 1934, 1935 ; J. Am. Med. Assoc., 1932 ; Am. J. Dis. Child., 1933; U. S. Naval Med. Bul., 1936.