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Miller Revisited
T u rn in g o n th e “ s p o tlig h t of p u b lic ity ” ■ ■ T h e 1972 House of Delegates resolved that when colleagues are being deprived of their human rights anywhere in the world, the Board of Trustees, on being duly informed, will review the facts, take appropriate actions, and report thereon to the House. An instance of such de
privation and the actions recommended are re ported on page 1142 of this issue of t h e j o u r n a l . We share the hope of Dr. Buckman of Al pha Omega that the spotlight of publicity in the free world will help alleviate the plight of this young dentist.
Opinion of Other Jo u rn a ls
M ille r re v is ite d M iT o the dental research worker who seeks inspiration from old masters, no source could be more warmly commended than the writings of W. D. Miller. These have recently been made more accessible by the interesting initiative of Professor K. G. König who suggested to the Karger publishing house that they should re print in unaltered form the opus entitled The M icro-Organism s o f the Human M outh 1 which first appeared in 1890. Miller’s chemicoparasitic theory has sur vived since that time as the essential explana tion of the carious process offered to genera tions of dental students. His theory commands no less respect today than it did when it was first enunciated. Subsequent research has added to our understanding of the pathogenesis of den tal caries, but without refuting the broad prin ciples which this learned man enunciated so long ago; at the time he attributed credit to several predecessors—notably Milles and Underwood who, in a paper delivered in London in 1881, re ferred to the action of acids and the action of germs as two constant factors in the carious pro cess. Miller described their investigations as ‘a great step in advance of anything hitherto ac complished in this direction.’ Yet it was Miller, unmistakably, who sep arated speculation from substance and who of fered a firm and clear explanation of the cause of dental decay. It was Miller who not only brought together the views of others but who 1 094 ■ ED ITO R IA LS
I JA D A ,
V o l. 87, N o v e m b e r 1973
gave shape and body to the hypothesis by de tailed and painstakingly recorded experiments. It was Miller above all who understood and demonstrated how micro-organisms produced enamel-dissolving acid by the fermentation of particles of dietary carbohydrate. What manner of man, and what manner of preparation, provide the stuff of which lasting discoveries are made? Miller, the son of a farm er, was born in Ohio in 1853 and, at the age of 22, having graduated B.A. in Natural Sciences at the University of Michigan, he travelled to Edinburgh to study physics and mathematics. Thence he went to Berlin where he was befriend ed by an American dentist and encouraged to study dentistry at the University of Pennsyl vania. After graduating, he returned to Ger many and, apart from becoming a leading den tal practitioner in Berlin, immersed himself in the study of bacteriology under the guidance of the great Koch. Clearly he was a most studious man, and managed to combine his clinical ac tivity and interest with a consuming curiosity about biological phenomena. This enabled him to become a pioneer in establishing a scientific basis for many aspects of dentistry apart from dental caries, and his extraordinary capacities are reflected in a list of almost 200 published papers. Lest anyone should doubt that Miller was unique, it need only be mentioned that while all this was going on he also contrived to be come the champion of Germany at golf, and to
retain his title for several years! Miller’s writing is rewarding for more than its undoubted scientific content. His literary style is something to savour, an emollient con trast to the stereotyped jargon that has come to characterise scientific communication. There are examples to relish on every page, and per haps two can be quoted, the first to reflect his abiding obsession and the second to illustrate his insight and humility. ‘The existence of a most excellent nursery for bacteria at the very portal of the human body is a fact which has only recently begun to receive the attention which its importance demands.’ ‘Most of us, for the sake of our backs, toward the end of a hard day’s work, now and then decide that a difficult cav ity is ready to fill when a careful examination of it might still reveal soft points.’ There is an additional message in these two quotations that will not be missed by those who deplore the separate paths sometimes taken by laboratory research and clinical practice. It must be remembered that Miller lived at a time when there were still current such mis conceptions as the notion that bacteria were the result and not the cause of fermentation. It was not enough for him to suggest that bacterial ac tion upon dietary carbohydrate accounted for the elaboration of acid. He needed, in addition, to disprove old fallacies and his manner of doing so by a series of simple and repeatable experi ments is enchanting to read and the very anti thesis of assertions formulated at a safe distance from exposure to laboratory testing or clinical trial. One of the consequences of the realisation that caries takes its inception from the fermen tation of food debris, was a great upsurge in en thusiasm for toothbrushing. It is said by one of Miller’s biographers that the slogan ‘a clean tooth will never decay’ arose at that time—and like so many slogans before and since proved to be no more than a device for the dissemina tion of a half-truth. It was not Miller, however, who built up the notion that mechanical means alone could prevent tooth decay, but rather those who extrapolated from his theories with out the cautious dependence upon scientific proof that characterised his work. Likewise, it was not Miller who evolved the concept that caries could be attributed entirely to dietary in discretion; indeed he could not countenance the attempt to banish carbohydrates from ‘the foods and luxuries of civilised races,’ and the advice he offered matches the modem view that
frequency of assimilation matters more than total consumption. Miller had too complete an understanding of the part played by micro-or ganisms in the carious process to pin his hopes for the conquest of caries on toothbrushing or the total exclusion of particular foodstuffs. The fact that Miller’s theory is more than 80 years old is occasionally regarded as indicating a lack of progress in caries research. When read ing his work, however, the importance of sub sequent discoveries becomes apparent for they have exposed serious flaws in his interpreta tion of the interaction between bacteria and sub strate. Conspicuous among the newer develop ments is the realisation that fermentable carbo hydrate need not be assimilated in a sticky, cling ing form in order to adhere to tooth enamel; the action of cariogenic streptococci in converting sugar to polysaccharide, a phenomenon easily demonstrated in vitro provides the answer to a problem that was perplexing to Miller. Strange to say he had observed the formation of dextran in test tubes but failed to realise its significance in the mouth. He described how the growth of a small coccus in sugar solutions resulted in the liquid becoming ‘slimy, viscous (stringy)’ and then, to show that even Homer nods, he declared that sugar was too soluble to remain upon the teeth for long and that to be really destructive it had to be consumed ‘as an ingredient of sticky, insoluble substances.’ He failed to appreciate that the deleterious effect of organisms was at tributable not only to their acid-producing po tential but also to their ability to change the phys ical nature of foodstuffs. W. D. Miller can be forgiven for his failure to appreciate the significance of plaque in the etiology of caries. He was a man who adorned our profession, and he contributed vastly to the emergence of dentistry from the status of a craft. His scientific approach to the understanding of dental disease is perhaps the greatest of all the lessons to be learned from The M icro-O rga nisms o f the Human Mouth. All detail apart, it is this which was Miller’s greatest gift to his pro fession. 1. The Micro-Organisms of the Human Mouth: The Local and General Diseases Which are Caused by Them. By Willoughby D. Miller (1853-1907). With an introductory essay on 'W. D. Mil ler and his Contribution to Dental Science’ by Klaus G. Konig (Nijmegen). London; S. Karger. Reprinted 1973. Pp. 364. Price
£8-10.
This editorial appeared in the August 21, 1973, issue of the B ritish Dental Journal.
EDITORIALS / JADA, Vol. 87, November 1973 ■ 1095
privation and the actions recommended are re ported on page 1142 of this issue of t h e j o u r n a l . We share the hope of Dr. Buckman of Al pha Omega that the spotlight of publicity in the free world will help alleviate the plight of this young dentist.
Opinion of Other Jo u rn a ls
M ille r re v is ite d M iT o the dental research worker who seeks inspiration from old masters, no source could be more warmly commended than the writings of W. D. Miller. These have recently been made more accessible by the interesting initiative of Professor K. G. König who suggested to the Karger publishing house that they should re print in unaltered form the opus entitled The M icro-Organism s o f the Human M outh 1 which first appeared in 1890. Miller’s chemicoparasitic theory has sur vived since that time as the essential explana tion of the carious process offered to genera tions of dental students. His theory commands no less respect today than it did when it was first enunciated. Subsequent research has added to our understanding of the pathogenesis of den tal caries, but without refuting the broad prin ciples which this learned man enunciated so long ago; at the time he attributed credit to several predecessors—notably Milles and Underwood who, in a paper delivered in London in 1881, re ferred to the action of acids and the action of germs as two constant factors in the carious pro cess. Miller described their investigations as ‘a great step in advance of anything hitherto ac complished in this direction.’ Yet it was Miller, unmistakably, who sep arated speculation from substance and who of fered a firm and clear explanation of the cause of dental decay. It was Miller who not only brought together the views of others but who 1 094 ■ ED ITO R IA LS
I JA D A ,
V o l. 87, N o v e m b e r 1973
gave shape and body to the hypothesis by de tailed and painstakingly recorded experiments. It was Miller above all who understood and demonstrated how micro-organisms produced enamel-dissolving acid by the fermentation of particles of dietary carbohydrate. What manner of man, and what manner of preparation, provide the stuff of which lasting discoveries are made? Miller, the son of a farm er, was born in Ohio in 1853 and, at the age of 22, having graduated B.A. in Natural Sciences at the University of Michigan, he travelled to Edinburgh to study physics and mathematics. Thence he went to Berlin where he was befriend ed by an American dentist and encouraged to study dentistry at the University of Pennsyl vania. After graduating, he returned to Ger many and, apart from becoming a leading den tal practitioner in Berlin, immersed himself in the study of bacteriology under the guidance of the great Koch. Clearly he was a most studious man, and managed to combine his clinical ac tivity and interest with a consuming curiosity about biological phenomena. This enabled him to become a pioneer in establishing a scientific basis for many aspects of dentistry apart from dental caries, and his extraordinary capacities are reflected in a list of almost 200 published papers. Lest anyone should doubt that Miller was unique, it need only be mentioned that while all this was going on he also contrived to be come the champion of Germany at golf, and to
retain his title for several years! Miller’s writing is rewarding for more than its undoubted scientific content. His literary style is something to savour, an emollient con trast to the stereotyped jargon that has come to characterise scientific communication. There are examples to relish on every page, and per haps two can be quoted, the first to reflect his abiding obsession and the second to illustrate his insight and humility. ‘The existence of a most excellent nursery for bacteria at the very portal of the human body is a fact which has only recently begun to receive the attention which its importance demands.’ ‘Most of us, for the sake of our backs, toward the end of a hard day’s work, now and then decide that a difficult cav ity is ready to fill when a careful examination of it might still reveal soft points.’ There is an additional message in these two quotations that will not be missed by those who deplore the separate paths sometimes taken by laboratory research and clinical practice. It must be remembered that Miller lived at a time when there were still current such mis conceptions as the notion that bacteria were the result and not the cause of fermentation. It was not enough for him to suggest that bacterial ac tion upon dietary carbohydrate accounted for the elaboration of acid. He needed, in addition, to disprove old fallacies and his manner of doing so by a series of simple and repeatable experi ments is enchanting to read and the very anti thesis of assertions formulated at a safe distance from exposure to laboratory testing or clinical trial. One of the consequences of the realisation that caries takes its inception from the fermen tation of food debris, was a great upsurge in en thusiasm for toothbrushing. It is said by one of Miller’s biographers that the slogan ‘a clean tooth will never decay’ arose at that time—and like so many slogans before and since proved to be no more than a device for the dissemina tion of a half-truth. It was not Miller, however, who built up the notion that mechanical means alone could prevent tooth decay, but rather those who extrapolated from his theories with out the cautious dependence upon scientific proof that characterised his work. Likewise, it was not Miller who evolved the concept that caries could be attributed entirely to dietary in discretion; indeed he could not countenance the attempt to banish carbohydrates from ‘the foods and luxuries of civilised races,’ and the advice he offered matches the modem view that
frequency of assimilation matters more than total consumption. Miller had too complete an understanding of the part played by micro-or ganisms in the carious process to pin his hopes for the conquest of caries on toothbrushing or the total exclusion of particular foodstuffs. The fact that Miller’s theory is more than 80 years old is occasionally regarded as indicating a lack of progress in caries research. When read ing his work, however, the importance of sub sequent discoveries becomes apparent for they have exposed serious flaws in his interpreta tion of the interaction between bacteria and sub strate. Conspicuous among the newer develop ments is the realisation that fermentable carbo hydrate need not be assimilated in a sticky, cling ing form in order to adhere to tooth enamel; the action of cariogenic streptococci in converting sugar to polysaccharide, a phenomenon easily demonstrated in vitro provides the answer to a problem that was perplexing to Miller. Strange to say he had observed the formation of dextran in test tubes but failed to realise its significance in the mouth. He described how the growth of a small coccus in sugar solutions resulted in the liquid becoming ‘slimy, viscous (stringy)’ and then, to show that even Homer nods, he declared that sugar was too soluble to remain upon the teeth for long and that to be really destructive it had to be consumed ‘as an ingredient of sticky, insoluble substances.’ He failed to appreciate that the deleterious effect of organisms was at tributable not only to their acid-producing po tential but also to their ability to change the phys ical nature of foodstuffs. W. D. Miller can be forgiven for his failure to appreciate the significance of plaque in the etiology of caries. He was a man who adorned our profession, and he contributed vastly to the emergence of dentistry from the status of a craft. His scientific approach to the understanding of dental disease is perhaps the greatest of all the lessons to be learned from The M icro-O rga nisms o f the Human Mouth. All detail apart, it is this which was Miller’s greatest gift to his pro fession. 1. The Micro-Organisms of the Human Mouth: The Local and General Diseases Which are Caused by Them. By Willoughby D. Miller (1853-1907). With an introductory essay on 'W. D. Mil ler and his Contribution to Dental Science’ by Klaus G. Konig (Nijmegen). London; S. Karger. Reprinted 1973. Pp. 364. Price
£8-10.
This editorial appeared in the August 21, 1973, issue of the B ritish Dental Journal.
EDITORIALS / JADA, Vol. 87, November 1973 ■ 1095