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The orthodontist—Innocent bystander or prime mover in facial growth?
THE
ORTHODONTIST-INNOCENT MOVER IN FACIAL WEXDELL
L. WYLIE,
D.D.S., KS.,”
BYSTANDER GROWTH?
OR PRIME
S.UWFRASCISCO,
CIALIE’.
VERY essayist on the program of a professional or scientific society had better leave to the audience any judgments as to whether or not. his papor is worth while. This I certainly propose to do. This paper, however, rcprcsents enough of a departure from my usual procedure that 1 cannot, let, it pass without notice. Ordinarily I write a paper and then supply a title for it---This time I sometimes even the title suggested by the program chairman. have reversed the procedure; undoubtedly, the question put in this particular title transcends in importance any of the fact,s which may be arrayctl beneath it. The question is important because it is one which orthodontists must answer for themselves fairly soon if they are to go much further in the dcvelopment of their specialty. In order that the importance of the question 1~ understood, some review of the ort,hoclontic thinking of the last two dccadcs is necessary. We must consider the work of clinicians and the work of research workers. some of whom are also clinicians. Jn evaluating honest attempts to discover t,he truth, we should take into account the intellectual climate which prevailetl when the study of the problem was made. Research or clinical investigation does not consist of a series of unrelated projects conducted by independent, persons who look upon themselves as rivals of one another. The picture must be considcrcd in its entirety, and it is just as asinine to lift one man’s work from the context of his contemporaries as it is t.o seize ulmn one aspect ~)f iI person’s work and ignore the remainder. Since about 1938, when really systematic investigation came to renlacc conj&ure and the writing of armchair essays! orthodontists have considcrctl tho following l~roblcms :
E
Arch length (or simply crowding). Arch relationship, which includes cross-bite in the posterior and anterior regions, although too frequently arch relationship is taken to mean only mesiodistal relationships which WC classify t,hem as Class I1 or Class III. Overbit,e. E’acial est,hctics. Read before the twelfth annual meeting of the American Institute of Dmtal Me~lic‘inc The Desert Inn, Palm Springs, California, Ott 25, 1955. *Professor of Orthodontics ancl Assistant Dean, College of Dentistry, ITniversity (Mifornia. 985
(I!’
986
WYLIE
0. s., 0. M., & 0. P. September, 1956
What do we know so far about these four problems, and what hope do we have for achieving, in a practical way, a permanent correction of the conditions 62 Among the great variety of approaches that have been brought to bear on these problems are rocntgenography of the facial skeleton and of the temporomandibular joint, electromyography, animal experimentation, and the measurement of plaster models. Prior to 1938, inordinate importance was attached to purely environmental factors, with not very much in the way of evidence to back up the conjectures. It was true that individual instances could be cited in substantial numbers, which seemed to indicate that environmental factors produced a given condition. That is, one could demonstrate the condition and produce some kind of history to the effect that t,he environmental factor had worked on a particular person. However, no attempt was ever made to discover how often the environmental factor prevailed without producing the condition, or how many persons presented the problem without those environmental factors being discoverable in their backgrounds. Thus, instances which would have been appropriate as illustrations if there had been a body of evidence to make illustration worth while came to serve as evidence itself, and a theory emerged which was easily abandoned when real evidence was accrued. With so much emphasis on environmental factors, it is not surprising tha.t in that era the factor of inheritance was largely ignored. This is an understatement, for anyone who had the temerity (as I did in my youth) to suggest that genetics might be a worth-while study for the orthodontist was likely to be denounced for having not only a bookish turn of mind, but a defeatist attitude as well. All this was substantially changed by the publication of a doctoral thesis by Allan Brodie and the subsequent attention which it attracted. Brodie demonstrated, by following a group of boys from the third month to the eighth year of life, that a remarkable proportionality could be observed in these children and that the basic architecture of the face was pretty stable, come what may in the way of environmental influences. Brodie’s paper has been so influential in orthodontic t,hinking that we have young orthodontists with US today who could not identify a tongue habit if they tried, but who ascribe to the chromosomes machinations of which t,hey could not possibly be capable. Brodie’s work was meticulously done and the generalizations in the original paper, when properly read, went no farther than the facts warranted. An often-repeated phrase, “constancy of pattern,” however, has led other persons to make dogmatic assertions which arc not supported by fact and into which meanings have been read which limit t,oo much t,hc scope of orthodontic treatment. Studies of the temporomandibular joint by Boman, Ricketts, and Foor have shown us that during orthodontic treatment growth occurs at the head of the condyle in amounts not likely to occur in that one limited area without orthodontic intervention. Moreover, careful examination of the cephalometric films
988
WYLIE
0. S.. 0. M.. & 0. P. September, 1956
Nature and when they were working against it. The disillusion that ultimately and inevitably crept up on them in the form of Nance and others was overwhelming. The result was that many orthodontists overreacted, Having discovered that one could not make a narrow mandible become a wide one by means of orthodontic appliances, they overlooked completely the fact that orthodontists may induce growth in height in the dental area with every expectation of success and as I have already said, evoke a growth response at the head of the condyle. The sober reflection which only hindsight can provide tells us the nature of the fundamental error: the development of alveolar height is a part of the natural process of growth, and so is endochondral growth at the mandibular condyle. When the orthodontist attempts to achieve these same things with his appliances, he is at least imitating Nature. Nature, on the other hand, adds but little to the lateral width of the face after birt,h; thus, when an orthodontist sets off in his direction, he is imitating nothing other than another orthodontist, and he does so at his own peril. One comment is in order with respect to making measurements of the dental arches. It has been good experience for orthodontists to make these measurements, for they indicate the relative severity of different malocclusions as we compare one with the other. Whether they should be used to indicate a specific clinical line of action is dubious. We must always temper our judgments by consideration of the face, the flaccidity of the lips, and many other things. Above all, let it be remembered that our objectives are not mathematical concepts, but that, instead, we are simply trying to establish a functional and esthetic dentition. In view of the fact that up to 2 mm. of crowding ma,y exist and be measured without any clinical evidence of the crowding, it should be clear that we cannot count upon treating to some mathematical standard. Baume’s work tells us that actually the best hope for regular teeth is to achieve good jaw proportions prior to the eruption of the deciduous teeth, for he has shown conclusively that “physiologic spacing” is a popular but ovcrrated concept, since the dimensions of the deciduous arch simply do not change. He has shown, furthermore, that growth occurs during the eruption of incisors ; however, the amounts are slight enough that, in my belief, it would solve only the milder problems. His findings should not be considered as a basis for the revival of the belief that severe malocclusions often may be outgrown by children. Several different independent studies indicate that, even if certain events which tend to relieve crowding occur up to the age of 10 years, arch dimensions decrease after that, so that relapse with respect to crowding and rotation should be expected rather than deplored. These works devising for themselves some sort of suggest the wisdom of orthodontists’ statute of limitations. In other words, how long must results remain perfect before we may say that we have succeeded in our efforts t Orthodontics, like all of dentistry, is still a little new in the field of reThere is a deplorable tendency among search and a little bit self-conscious.
ORTHODONTIST-INNOCENT
BYSTANDER
OH PRIME
MOVER, ?
:1X!)
dentists to feel that they are not qualified to decide on the basis of the cvidcnce and, instead, to follow blindly the dictatcbs of men who presume to htL ildcquate juclgos of such matt,ers. It is to be hoped t,hat more genuinely basic. work and a concomitant, CIAOgram of clinical invest,igation will be carried out, stressing thr fact that the scientific method is as important as the facts which t,ht scientific method 1)1-otluccs. If this should come about, it will mean t,he dcclinc o-f some of th(b so-c~nllctl authorities to whom other dentists are cupectcd to defer. C,%~ncomitant with that devclopmrnt would be a hcightenctl intcrcst in the prac+ticc> ot Ilentistt-y on the part of those who have that l~rivilcgc, ant1 an incrtl;rsc>cI sharing of t.hc exhilaration that comes From w r(‘stlill y with problc~tns which as yet are not altogcthcr solved.
ORTHODONTIST-INNOCENT MOVER IN FACIAL WEXDELL
L. WYLIE,
D.D.S., KS.,”
BYSTANDER GROWTH?
OR PRIME
S.UWFRASCISCO,
CIALIE’.
VERY essayist on the program of a professional or scientific society had better leave to the audience any judgments as to whether or not. his papor is worth while. This I certainly propose to do. This paper, however, rcprcsents enough of a departure from my usual procedure that 1 cannot, let, it pass without notice. Ordinarily I write a paper and then supply a title for it---This time I sometimes even the title suggested by the program chairman. have reversed the procedure; undoubtedly, the question put in this particular title transcends in importance any of the fact,s which may be arrayctl beneath it. The question is important because it is one which orthodontists must answer for themselves fairly soon if they are to go much further in the dcvelopment of their specialty. In order that the importance of the question 1~ understood, some review of the ort,hoclontic thinking of the last two dccadcs is necessary. We must consider the work of clinicians and the work of research workers. some of whom are also clinicians. Jn evaluating honest attempts to discover t,he truth, we should take into account the intellectual climate which prevailetl when the study of the problem was made. Research or clinical investigation does not consist of a series of unrelated projects conducted by independent, persons who look upon themselves as rivals of one another. The picture must be considcrcd in its entirety, and it is just as asinine to lift one man’s work from the context of his contemporaries as it is t.o seize ulmn one aspect ~)f iI person’s work and ignore the remainder. Since about 1938, when really systematic investigation came to renlacc conj&ure and the writing of armchair essays! orthodontists have considcrctl tho following l~roblcms :
E
Arch length (or simply crowding). Arch relationship, which includes cross-bite in the posterior and anterior regions, although too frequently arch relationship is taken to mean only mesiodistal relationships which WC classify t,hem as Class I1 or Class III. Overbit,e. E’acial est,hctics. Read before the twelfth annual meeting of the American Institute of Dmtal Me~lic‘inc The Desert Inn, Palm Springs, California, Ott 25, 1955. *Professor of Orthodontics ancl Assistant Dean, College of Dentistry, ITniversity (Mifornia. 985
(I!’
986
WYLIE
0. s., 0. M., & 0. P. September, 1956
What do we know so far about these four problems, and what hope do we have for achieving, in a practical way, a permanent correction of the conditions 62 Among the great variety of approaches that have been brought to bear on these problems are rocntgenography of the facial skeleton and of the temporomandibular joint, electromyography, animal experimentation, and the measurement of plaster models. Prior to 1938, inordinate importance was attached to purely environmental factors, with not very much in the way of evidence to back up the conjectures. It was true that individual instances could be cited in substantial numbers, which seemed to indicate that environmental factors produced a given condition. That is, one could demonstrate the condition and produce some kind of history to the effect that t,he environmental factor had worked on a particular person. However, no attempt was ever made to discover how often the environmental factor prevailed without producing the condition, or how many persons presented the problem without those environmental factors being discoverable in their backgrounds. Thus, instances which would have been appropriate as illustrations if there had been a body of evidence to make illustration worth while came to serve as evidence itself, and a theory emerged which was easily abandoned when real evidence was accrued. With so much emphasis on environmental factors, it is not surprising tha.t in that era the factor of inheritance was largely ignored. This is an understatement, for anyone who had the temerity (as I did in my youth) to suggest that genetics might be a worth-while study for the orthodontist was likely to be denounced for having not only a bookish turn of mind, but a defeatist attitude as well. All this was substantially changed by the publication of a doctoral thesis by Allan Brodie and the subsequent attention which it attracted. Brodie demonstrated, by following a group of boys from the third month to the eighth year of life, that a remarkable proportionality could be observed in these children and that the basic architecture of the face was pretty stable, come what may in the way of environmental influences. Brodie’s paper has been so influential in orthodontic t,hinking that we have young orthodontists with US today who could not identify a tongue habit if they tried, but who ascribe to the chromosomes machinations of which t,hey could not possibly be capable. Brodie’s work was meticulously done and the generalizations in the original paper, when properly read, went no farther than the facts warranted. An often-repeated phrase, “constancy of pattern,” however, has led other persons to make dogmatic assertions which arc not supported by fact and into which meanings have been read which limit t,oo much t,hc scope of orthodontic treatment. Studies of the temporomandibular joint by Boman, Ricketts, and Foor have shown us that during orthodontic treatment growth occurs at the head of the condyle in amounts not likely to occur in that one limited area without orthodontic intervention. Moreover, careful examination of the cephalometric films
988
WYLIE
0. S.. 0. M.. & 0. P. September, 1956
Nature and when they were working against it. The disillusion that ultimately and inevitably crept up on them in the form of Nance and others was overwhelming. The result was that many orthodontists overreacted, Having discovered that one could not make a narrow mandible become a wide one by means of orthodontic appliances, they overlooked completely the fact that orthodontists may induce growth in height in the dental area with every expectation of success and as I have already said, evoke a growth response at the head of the condyle. The sober reflection which only hindsight can provide tells us the nature of the fundamental error: the development of alveolar height is a part of the natural process of growth, and so is endochondral growth at the mandibular condyle. When the orthodontist attempts to achieve these same things with his appliances, he is at least imitating Nature. Nature, on the other hand, adds but little to the lateral width of the face after birt,h; thus, when an orthodontist sets off in his direction, he is imitating nothing other than another orthodontist, and he does so at his own peril. One comment is in order with respect to making measurements of the dental arches. It has been good experience for orthodontists to make these measurements, for they indicate the relative severity of different malocclusions as we compare one with the other. Whether they should be used to indicate a specific clinical line of action is dubious. We must always temper our judgments by consideration of the face, the flaccidity of the lips, and many other things. Above all, let it be remembered that our objectives are not mathematical concepts, but that, instead, we are simply trying to establish a functional and esthetic dentition. In view of the fact that up to 2 mm. of crowding ma,y exist and be measured without any clinical evidence of the crowding, it should be clear that we cannot count upon treating to some mathematical standard. Baume’s work tells us that actually the best hope for regular teeth is to achieve good jaw proportions prior to the eruption of the deciduous teeth, for he has shown conclusively that “physiologic spacing” is a popular but ovcrrated concept, since the dimensions of the deciduous arch simply do not change. He has shown, furthermore, that growth occurs during the eruption of incisors ; however, the amounts are slight enough that, in my belief, it would solve only the milder problems. His findings should not be considered as a basis for the revival of the belief that severe malocclusions often may be outgrown by children. Several different independent studies indicate that, even if certain events which tend to relieve crowding occur up to the age of 10 years, arch dimensions decrease after that, so that relapse with respect to crowding and rotation should be expected rather than deplored. These works devising for themselves some sort of suggest the wisdom of orthodontists’ statute of limitations. In other words, how long must results remain perfect before we may say that we have succeeded in our efforts t Orthodontics, like all of dentistry, is still a little new in the field of reThere is a deplorable tendency among search and a little bit self-conscious.
ORTHODONTIST-INNOCENT
BYSTANDER
OH PRIME
MOVER, ?
:1X!)
dentists to feel that they are not qualified to decide on the basis of the cvidcnce and, instead, to follow blindly the dictatcbs of men who presume to htL ildcquate juclgos of such matt,ers. It is to be hoped t,hat more genuinely basic. work and a concomitant, CIAOgram of clinical invest,igation will be carried out, stressing thr fact that the scientific method is as important as the facts which t,ht scientific method 1)1-otluccs. If this should come about, it will mean t,he dcclinc o-f some of th(b so-c~nllctl authorities to whom other dentists are cupectcd to defer. C,%~ncomitant with that devclopmrnt would be a hcightenctl intcrcst in the prac+ticc> ot Ilentistt-y on the part of those who have that l~rivilcgc, ant1 an incrtl;rsc>cI sharing of t.hc exhilaration that comes From w r(‘stlill y with problc~tns which as yet are not altogcthcr solved.