56 K. J. Franklin 



along such lines if results of a simpler study (see above) on 

 Merion rats proved promising. A very large programme was 

 agreed upon by G. A. Cowan, his registrar, J. L. Marsden, this 

 Department's Senior Lecturer in Histology, F. J. Aumonier, 

 and the author. The subjects were to be patients of all possible 

 ages and both sexes, and biopsy specimens were to be removed 

 with agreement from all requiring extractions, the first 

 biopsy being made coincident with first attendance at the 

 Outpatient Department. The total number of such biopsies 

 was to run into four figures so as to allow for proper statistical 

 treatment of findings subject to many more variables (e.g. 

 left- and right-handed brushing, varying loss of teeth) than is 

 the case in Merion rats. 



The scheme has been put into practice in the hope that it 

 will give evidence of variation with age in the response to 

 brushing, as well as be of direct dental relevance without 

 reference to age. Patients are instructed to brush their gums 

 twice daily using a standard dentifrice and brush, both of 

 which are supplied free. The brushing ritual consists of twelve 

 single strokes from gum to tooth on each of four " quadrants " 

 into which each jaw is divided, giving a total of 96 strokes in 

 each of the two daily brushings. Biopsies are taken one, two, 

 and three months after the beginning of treatment. The 

 biopsy material is fixed in Bouin's fluid, embedded in paraffin 

 wax, sectioned perpendicular to the epithelial surface, and 

 stained with haematoxylin and eosin. 



So far 53 patients, aged from 6 to 67 years, have been 

 studied. The majority fall into the teenage, the twenties and 

 the thirties, other decades being as yet represented by very 

 few individuals. It is still premature to try to relate changes 

 in the response to the stimulus to changes in age, but such 

 indication as exists to date is in favour of an increase, rather 

 than the opposite, with increase in age. Perhaps this is 

 a puberty effect, and that possibility will be borne in 

 mind. The response to the set stimulus is a noticeable 

 thickening of the cornified layer of the epithelium (Fig. 6b); 

 the whole epithelial sheet also tends to thicken but, as the 



