118 R. F. SOGNNAES 



disease is but one of maii\' unfortunate examples of oral pathology 

 where basic knowledge is soreh' inadequate for intelligent inte- 

 gration with clinical practice. In particular, we lack the means of 

 precise clinical measurements bv which to diagnose early lesions 

 and delineate, in each individual patient, the relative significance 

 of the various structural, functional, en\'ironmental, and consti- 

 tutional influences enumerated above. Onlv with such means for 

 obtaining knowledge of the individual patient situation can one hope 

 to arrive at a truly professional and scientific approach to diagnosis, 

 prognosis, prevention, and therapy. 



With this reservation, the following practical points mav be 

 made. Because erosion, unlike caries, fails to produce subsurface 

 demineralization beyond 100 microns, one cannot diagnose the ini- 

 tial incipient surface lesion by the naked eye. The opacity, if any, 

 is too superficial. Better diagnostic "eves" are needed. The first 

 clinical detection of a patient's tendency to erosion must therefore 

 — in view of our present diagnostic inadequacies — await the mani- 

 festation of some grossly yisible loss of tooth substance, that is, a 

 very advanced stage of the lesion, biochemically speaking. 



On theoretical grounds, our microradiographic findings (suggest- 

 ing a primary surface demineralization) would lead to the conclu- 

 sion that one preventive approach would be to reduce the solubil- 

 ity of the tooth mineral. To date there is no demonstrable practical 

 way to achieve this better than the topical application of fluoride. 

 Possibly a somewhat stronger concentration (4 per cent) utilizing 

 the more soluble potassium fluoride (Sognnaes, 1941) and more 

 frequent applications to the erosion-susceptible tooth surfaces ( every 

 4 months) may prove advantageous. One may hope that other 

 trace element combinations, such as the inclusion of heav\' metal 

 ions as exemplified by tin fluoride, may be brought to bear upon 

 the clinical control of both erosion and caries. To my knowledge 

 there have been no direct comparisons between the relative inci- 

 dence of erosion and that of caries in fluoridated communities. This 

 should be established. Even without fluoridation it has been an 

 impression that a reverse relationship exists between these two types 

 of oral pathology to begin with. But even though the oral en\'iron- 



