Dental Caries in London School-children (1929-47)
Authors: M. Mellanby, H. Mellanby
Journal: BMJ (1948)

The present paper is a continuation of a series describing the dental condition of 5-year-old London County Council school-children in 1929, 1943, and 1945 (Mellanby and Coumoulos, 1944, 1946).Between July and the end of October, 1947, 1,590 such children were examined with the object of finding whether the improvement observed in 1943 and 1945 had been maintained.The children lived in the same areas of London, and in the majority of cases attended the same schools as those used for the earlier surveys.A few of the schools previously visited were no longer available ; substitutes in the same localities were then provided by the London County Council.As before, only children who had attained their fifth birthday but had not yet reached their sixth were selected, the average age being the same as in the other surveys.Although the presence of any permanent teeth erupting or erupted was recorded, this report refers only to the deciduous dentition.,In this 1947 survey the methods and standards adopted were similar to those used previously, full details of which can be found in the earlier papers. MethodsStructure.-Thestructure of the individual teeth of each child was assessed according to the method devised and first used by M. Mellanby as early as 1923 and since then also employed on numerous occasions by others, including King, Coumoulos, Deverall, H. Mellanby, and Davies.In essence the method &onsists in rubbing the labial surface enamel of each tooth with a fine probe of standard size and sharpness (S.S. White Stainless No. 37).After some practice it is possible to grade teeth in the mouth by the smoothness or roughness felt with the probe.It was shown many years ago that this external enamel texture could be correlated with good and poor microscopic structure (M.Mellanby, 1934).On sectioning, smooth teeth showed what were judged to be well- calcified enamel and dentine, whereas external roughness was usually associated with a less well-calcified minute structure, in particular with dentine containing interglobular spaces.The various macroscopic grades of surface roughness or defect are referred to as M-Hypoplasia (M-Hy) to distinguish them from gross or " textbooks" hypoplasia (G-Hy), which is the only type whose existence is commonly recognized by dentists.Gross hypoplasia, the aetiology of which is not fully understood, is uncommon in deciduous teeth in this country; it is readily visible to the naked eye, the teeth so classed having obvious enamel pits or, in some instances, areas from which the enamel is lacking.In surveys of this kind there are always some teeth whose structure it is difficult or even impossible to grade.This situ- ation may arise, for instance, when a tooth has some structural defect which does not correspond to any of the grades described below.These teeth are included in Tables under the heading " Hy unclassified."A small proportion of teeth were so carious and others had such heavy deposits of tartar over certain areas that no opinion could be formed about their original surface structure.Where for either reason it was impossible to make a satisfactory estimate of the average structure the teeth are recorded as being present in the mouth but are not included in the structure tables.By the probe method described, each tooth whose struc- ture could be assessed was graded according to the following symbols:Hy.: No hypoplasia; smooth shiny surface-good structure.M-Hy,: Slightly rough surface-slightly defective tooth.M-Hy,: Rougher surface-definitely defective.M-Hy,: Very rough-very defective.G-Hy: All varieties of gross or " textbook " hypoplasia.Caries.-Each tooth was examined for caries with a standard probe (S.S. White Stainless No. 12) and illumin- ated mirror