230 M. N. Naylor sessions with a hygienist. The results after 3 years showed major reductions in gingivitis, decay and plaque when the test groups were compared with the controls. Returning to periodontal disease, there is overwhelming evidence that the basis of all treatment is plaque control. All the complex and sophisticated surgical procedures which are available today are doomed to failure unless supported by regular and effective re- moval of microbial deposits. An important advance in the provision of dental care is the widespread introduction of Dental Hygienists, first trained by and employed in the dental branch of the Royal Air Force during World War II. After the war hygienists were employed within the Hospital Service only, but in 1957, following the passing of the 1956 Dentists Act, they were allowed to work in general practice. The number of training school for hygienists has increased and the number of girls applying for the 1-year course far exceeds the number of places available. At Guy's Hospital, the School of Dental Hygienists started in 1963 with five trainees per year. We now have 20 per year and have no difficulty selecting high quality trainees from the many applicants. Many colleagues in general practice, the community service and in hospitals regard these girls as an indispensible feature of the service they provide to their patients. Not only do they carry out scaling and plaque control instruction, but they play a vital role in the provision of dental health education in its widest sense. To contemplate a preventive and periodontally orientated form of practice without hygienists' support would be rather like contemplating Heaven without Angels. As indicated previously, the composition of the diet is extremely important in determining decay experience. Sugars, especially sucrose, have long been regarded as being heavily implicated in the initiation and progressing of decay but it was not until the mid-1950's that it was appreciated that the relationship between intake and disease was not a simple one. A human study carried out at the Vipeholm Hospital at Lund in Sweden demonstrated that both the form of the sugar food and its pattern of consump- tion were of crucial importance. Sucrose consumed at mealtimes only, in whatever form, caused little or no new decay, but continuous between-meal consumption of sticky toffees profoundly increased decay experience. Subsequent animal studies and human dietary investigations have confirmed these findings. It must be clear therefore that dietary regulation is an important aspect of any pre- ventive programme. Dental health education which emphasises the differences between right and wrong patterns of sugar consumption, is much more likely to be successful than trying to banish dietary sugar which anyway is an important and relatively cheap form of calories. Perhaps the one and only truly community measure to prevent decay is fluoridation. The inverse relationship between the decay experience in a community and the fluoride ion content of the drinking water supplies has been known since the early 1930s. In 1937 Trendley Dean carried out a survey of the decay levels of children living in 21 U.S. cities with different levels of fluoride in the drinking water. The results clearly demonstrate that when the fluoride ion level of the water supply was 1 ppm (i.e. 1 mg/litre) the decay experience was considerably reduced. Studies in other parts of the world including the U.K. have confirmed these findings. In 1945 the first programme to adjust the fluoride level to 1 ppm was initiated at Grand Rapids, Michigan. After 10 years the reductions were entirely similar to natural fluoride areas. Thus began the water fluoridation story. Many areas have been fluoridated in countries throughout the world, amongst which are Canada and the U.S., S. Ireland and Hong Kong and, to a disappointing extent, the U.K.

Dental health 231 The main inhibiting factor has been a small and vociferous minority, who oppose fluoridation on the grounds that it is a hazard to health and that it is unethical to tamper with water supplies. Two years ago, the Royal College of Physicians published a report of a Committee which had spent nearly 3 years inquiring into possible health hazards. The unequivocal conclusion was that fluoridation is safe and constitutes no hazard. Regarding the ethical aspects, this is very much an emotional and personal view my view is that it is unethical to withhold this proven health measure. Fluoridafion exerts its effect systemically, the fluoride ions being absorbed intestinally and, via the bloodstream, becoming incorporated into the crystalline structure of the tooth enamel during the development period. In this way the proportion of fluorapatite is increased thus decreasing the solubility of the enamel acids. Tablets containing fluoride are believed to be just as effective but, their regular daily ingestion for the first 14 or so years of life does require intense dedication and motivation. Tablets provide an individual preventive measure but water fluorida- tion includes the community as a whole and requires no individual effort or responsibility. Topical fluorides using dentifrice, or mouthwash as the vehicle are becoming in- creasingly popular. In fact, over 90• of toothpaste sold in the U.K. contains either sodium monofluorophosphate or stannous fluoride. The actual amount of paste sold however, suggests that large numbers of the population do not use toothpaste at all. Almost all these toothpastes have been tested by means of a traditional 3 year Clinical Trial and shown to be effective in reducing decay. Taking into account the natural history of the decay process and the limited duration of the trials, it should surprise no one that the absolute values of the reduction in decay are somwhat small. However, there can be no doubt that regular and conscientious use of a fluoride dentifrice, both in terms of specific fluoride effect and the plaque removal function, is an important feature of any preventive programme. As far as mouthwashes are concerned, the early studies carried out in Sweden, indicated that fluoride mouthwashes used as infrequently as at monthly intervals, caused a significant and clinically relevant reduction in the number of fillings required. In recent years an increasing number of practitioners have been providing 'preventive packages' which comprise dental health education, dietary advice, topical fluorides including dentifrices. Whilst we support wholeheartedly this approach and the philosophy behind it, we are very doubtful of the need for multi-topical fluoride treatments. Our own work in recent years has been concerned with this matter and we have already published the report of one study and the second is about to appear very soon. The first study was carried out in Croydon and was designed to determine the effect on 2-year decay increments of supervised daily use at school of an acidulated phosphate fluoride rinse and a sodium monofluorophosphate toothpaste used singly and in com- bination. Statistically significant reductions in 2-year caries increments were observed in all three experimental groups, i.e. fluoride rinse alone fluoride dentifrice alone and both together- when compared with the control. However, there were no significant differences between treatment groups. Our second study was carried out on the Isle of Wight and in London and was designed to test the decay prevention of twice per year professional applications of APF gel and the unsupervised home use of a monofluorophosphate-calcium carbonate based dentifrice used either singly or in combination. The findings were similar to the Croydon Study.