Mrs. Mellanby’s Conclusions

            At a recent British meeting Mrs. Mellanby exhibited the jaws, sections and photomicrographs of the teeth of several families of puppies to show the great changes in the structure of the teeth and jaws brought about by apparently small variations in a basal diet. The members of one litter of puppies each had a different cereal in an otherwise similar diet while those of another had a different fat. A third litter showed the differences caused by additions of vitamin D or vitamin A or Carotene, while yet another showed the effects of the addition of various salts of calcium, phosphorus or sodium. For example, a puppy receiving oatmeal, separated milk powder, raw lean meat, olive oil, orange juice, yeast and sodium chloride had hypoplastic teeth, the degree of hypoplasia varying with the rate of growth, & c. The substitution of fresh cod-liver oil (known not to have the vitaminc D destroyed by too long keeping, &c.) instead of olive oil in the diet of another pup of the same litter resulted in perfect teeth.

There were also the jaws and tooth sections of puppies from two mothers whose diet had been controlled previous to and after the puppie’s birth. Pairs of puppies, one from each mother, had been fed on similar diets. The effect of the maternal diet on both the deciduous and permanent teeth of the young was very pronounced.

Sections and photographs were shown to illustrate the effect of a deficiency of vitamin A on the predental tissues, both their development structure and their liability to disease, and also resulting in demyelination of the nerves.

Mrs. Mellanby’s demonstration showed the various grades of hypoplasia (macroscopic and microscopic) seen in both deciduous and permanent teeth of man and dog. To illustrate the many grades of structure, series of teeth, enlarged photographs of surface enamel and photomicrographs of sections where shown. She uses the term “hypoplasia” (underdevelopment) to cover any form of imperfect calcification, basing her standards mainly upon nutritional experiments on animal of different species. She uses as her standard of perfection teeth which have a smooth, white and shiny surface, ground sections of which, when viewed under the ordinary microscope, are seen to possess enamel of normal thickness for the type of tooth and with none of the defects recognized at the present time. The dentin is comparatively thick and contains no interglobular spaces.

In contrast hypoplastic teeth of man and the dog are more or less rough, discolored and opaque and in section the enamel, which is usually comparatively thin, shows defects such as pigmentation, and greater powers of staining (indicating poorer calcification) than the perfect or normal; the dentin is thin with interglobular spaces generally small and few in number in the slightly hypoplastic (Hy1), large and many in the grade 3 (Hy3). In Hy3gr. (gross) the enamel and dentin are not necessarily so badly calcified but the tissues and especially the enamel are very deficient and often irregularly so, and are, therefore, very obvious to the naked eye even before extraction or shedding of the tooth, while it is still covered with saliva. Charts illustrated the association of caries with the quality of the structure of the teeth and the result of the investigations on the control of decay in children’s teeth.

-The British Dental Journal.