THE PLACE OF CROWNS AND BRIDGE-WORK IN MODERN DENTISTRY.

MENTAL DEFECT IN SCHOOL-CHILDREN. "

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certain social aspects of character,

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general behaviour. Dr. S. D. PORTEUS, Superintendent of Special Schools at Melbourne, has indicated the possibilities in this direction in a " social rating scale." A census with a scientific basis of this sort would be of great value. A census based merely on the working definitions of the two existing Acts of Parliament would not be adequate. The vast majority LONDON :SATURDAY, AUGUST 16, 1924. of the cases at present certified under the Mental Deficiency Act are cases of very low grade intellectually-very little higher than the idiots and imbeciles MENTAL DEFECT IN SCHOOL-CHILDREN. already provided for in the Lunacy Acts ; these are by THE proportion of mentally defective persons in the no means so dangerous from a eugenic point of view community is not yet a matter of complete agreement. as many who elude certification, but make as certainly Some estimates of this proportion have been made defective and undesirable as parents. At the period at different times and in different areas by more the passing of the Mental Deficiency Act the eugenic I aspect of had to be slurred over in deference to opposition or less independent investigators, one of the most recent and most thorough being that of Dr. CYRIL emanated more from the heart than the head, BURT, psychologist to the London County Council, but a census that is to be of any practical and scientific who found a percentage of one and a half among to the nation cannot be thus influenced. London school-children. The standard adopted has varied with the investigator, and data have usually been incomplete. Dr. G. K. BowES, in a careful study THE PLACE OF CROWNS AND BRIDGE-WORK of children of school age in the rural area for which he IN MODERN DENTISTRY. is responsible, has discovered so large a proportion of AT the annual meeting of the British Dental defectives as 3 per cent., and suggests that it should Association at Edinburgh, which has just concluded, be 4 We on 313 his cent. possibly print p. really per method of ascertainment and some interesting Mr. H. W. BENNETTE read a paper on collar crowns descriptions of individual families. It is probable, as in which he unsparingly condemned this method of Dr. BOWES himself hints, that the proportion of saving teeth, and in the discussion which followed it mentally deficient persons in a rural population is was apparent that most of his hearers agreed with greater than that in a town population, because of the him. In considering the evolution of operative fact that a lower degree of intelligence serves for self- dentistry from its lowly beginnings, there are certain support in a rural area; but on the other hand there methods which stand out as landmarks. Amongst appear to be some grounds for thinking that the them the use of crowns and bridges represents a proportion in the town areas is larger than has been notable change in the outlook of the modern dentist. generally stated hitherto. The somewhat disturbing It does not require a very long professional life to figures suggest the necessity for considering the have witnessed the gradual evolution of crowns and feasibility of attempting to make a national census of bridges to their highest point of technical achievement, mental defectives. The social and eugenic aspects of and their decline in popularity to the present time This the problem of mental deficiency are of sufficient when so many regard them with disfavour. importance to the State to justify such a census in decline is not due to the substitution of other methods order that the magnitude of the problem may be of greater technical efficiency, but rather to a different, accurately judged. In the case of children of school outlook on the aims and objects of dental surgery. age the legal provision and the machinery already Even to-day it would be premature to regard the exist. The terms of both the Acts of Parliament discussion on crowns and bridges as ended, and the dealing with mental deficiency make it obligatory obituary notice as read. There are still a large upon local authorities to discover all defective number of dentists both in this country and abroad children, but it is extremely doubtful whether in any who use these methods extensively. The pages of dental journals abound in advertisements of various area anything like a complete census is yet available. Local authorities, in particular, who have no special appliances to facilitate the construction of crowns. school provision are apt to be slack in the performance and bridges. A new edition of a popular text-book of this duty ; with others the difficulty is shortage of on crowns and bridges has recently been issued and staff, and, it may be also, lack of experience among the will doubtless find many purchasers. But although there exists this discrepancy between the academic staff in diagnosis of deficiency. But legal provision and machinery are not enough. teaching of dentistry and its practice in many There is as yet no definitely fixed standard of what is quarters, there can be no doubt that the modern meant by mental deficiency. Yet in this respect the trend is definitely away from these methods of position to-day is very different from what it was at saving teeth. The reasons which led to the introduction and the time of the Royal Commission on the subject which preceded the passing of the Mental Deficiency Act. decline of these operative methods are instructive. Thanks to the efforts chiefly of an army of psycho- Thirty or forty years ago, when great technical logists, we are now provided with scales of tests, advances were beginning to be made in dentistry, intelligential and educational, which, however the aim of the dentist was to save as many teeth imperfect, are of practical value in estimating as possible. The local hygiene of the mouth was not intellectual capacity, and which in their use allow of entirely disregarded, but it was looked at from a, greater uniformity in the methods of examiners than narrow point of view and without much regard to was possible before their existence. It is true, of the general health of the patient. Many ingenious course, that diagnosis of mental deficiency cannot be methods for splinting loose pyorrhceic teeth weremade by such tests alone-if it were attempted the devised on the principle that all teeth which could result would be alarming. But although we are still be used without pain should be retained as long as without generally applicable tests of character, it does possible. Relics of this attitude still exist, but they not seem impossible to devise some method of are fast passing away. When teeth were too carious.

THE

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328 to be filled the method of restoring them by an evidence to show they are more frequently the seat artificial crown of gold or porcelain was introduced. The of an apical lesion than pulpless teeth which have crown was fastened to the root either by a collar placed been filled. The logical extension of such an attitude over the root and cemented on, or by a post passing would be to state that no tooth which had not a into the root canal and secured by cement. It is living pulp should be retained in the mouth, and obvious that, even with the highest technical skill- that no treatment involving the root canals should still more, if the crown is poorly constructed-there be undertaken. This view has been put forward in is a tendency for food and bacteria to collect round a America by some, but it does not appear to us that In the case of collar crowns the facts warrant so sweeping a statement or so drastic device of this kind. there is the added factor that there must be a ledge a limitation of conservative dentistry. The presence tmder the gum which collects debris, no matter how of apical infection in some teeth which have been well constructed, and must act as an irritant to the treated is a wholesome challenge to the dentist, for For this reason it raises the question as to whether dental technique gum and periodontal membrane. many dentists began to condemn this type of crown is sufficiently thorough and scientific to exclude ou the grounds that it predisposed to pyorrhoea, and infection from devitalised teeth. The dental profession This feeling has been steadily is fully alive to the gravity of this issue. Already the was an unclean device. growing, until there are few dentists to-day who interest aroused has resulted in a notable improvewould not agree that the collar crown is insanitary ment in root canal technique which warrants the belief and should be abandoned. This is not to say that that in the near future infection will be eliminated crowns as a whole are to be regarded as an illegitimate with certainty in the treatment of diseased pulps. form of dentistry. There is still a wide field of usefulness for crowns, but with the proviso that not only must they be constructed with great accuracy, but ZOOLOGY AND MEDICINE. also that the crown must fit the root edge to edge THE presidential address to Section D of the British so that there is no ledge to collect debris. There has Association, delivered by Prof. F. W. GAMBLE been so general a condemnation of crowns by doctors at Toronto on August llth, is of more than usual that it is well to make it clear that properly con- interest to medicine and its institutes. Taking as structed, and in suitable conditions, a crown may be his title " Construction and Control in Animal Life," he brings out emphatically the change which in a perfectly scientific and hygienic method of conserving teeth. Any type of crown, however, which involves recent times has come over the subject which he professes. Most of last century was occupied with a collar fitting over the root and extending below the description and classification: ". zoology " and " comgum margin is, in the opinion of most dentists, a parative anatomy " were more or less interchangeable form of conservative dentistrv which leads to dental terms, and the animation which followed the publicasepsis and should be tion of the " Origin of Species " left the method of vvitn regard to ariagework, in so rar as tne aou’t- inquiry much the same, while it transformed the ments of the bridge which are placed on the supporting interpretation of the results. The outlook has now teeth are collar crowns, then the condemnation of changed again and the dying Darwinian impetus But there is has been replaced by the experimental method. such crowns applies to bridges also. another factor. Each tooth is capable of slight Animals are no longer products which are, within under the stress of mastication, comprehensible periods of time, finished and stable movement independent ; the being, well-being, and becoming of them through the yielding of the periodontal membrane. beings are no longer problems of statics, but of dynamics. the force of mastication. This buffer-like action lessens Regulation " is the keynote of the development When two teeth are splinted together, as in a bridge, of zoological knowledge, whether internally, as by they must both move together, instead of indepen- the discovery of the factorial hypothesis, or externally, dently, and the stress to which they are submitted as in oecological relations. Form has been predominant will cause them to become loose. In the case of large over function in the formal discipline of zoology; has been assumed by most people that form has bridges which bear a considerable amount of impact it determined function. But function is now coming the strain on the abutments will during mastication, soon cause the loss of the supporting teeth. In the to the front, zoology and physiology and pathology are fusing their spheres of action, and a good many - case of small bridges exposed to little or no strain, are wondering whether function does not really this factor mav not be serious. Added to this there determine The applications of the older form. is also the factor of cleanliness. It is difficult to zoology to medical science are obvious enough. make so complex a piece of apparatus as a bridge It is impossible to investigate the functions and self-cleansing. It tends to gather debris far more lives of things which have no names, and the interthan a crown, and may become a veritable trap for vention of LiiN-N.7Fus was timely. The energy spent filth, well meriting the original condemnation passed on the nicest work in comparative systematics " on bridges by Dr. WILLIAM HUNTER. If the bridge is has never been wasted. As the master said, nomina si he et and did well rerum," nescis, cognitio perit removable the foregoing objection may have less insist that the live world must be arranged, to Such weight. bridges call for a high degree of technical identified, and put into a form as convenient and skill. They may have a legitimate place within lucid as a collection of postage stamps. Every schoolnarrow limits, but not to an extent which seriously boy who is taken to a museum knows that the being qualifies the general distrust of bridgework as a clean of Anopheles means something different from the method of tooth restoration. Since the advent of being of Culex; the native will learn not to tie up the X ray has shown that pulpless teeth, free from his foreskin for fear of bilharzia when he knows about the systematics of snails ; it seems symptoms, may sometimes be infected at the apices, enoughthat some of the most puzzling problems of crowns have received additional blame. Sir WILLIAM likely and prevalence of plague in India the distribution WILLCOX, for instance, has stated that all crowns have been solved by the elegant separation of should be extracted because of the apical infection so castia from X. cheopis by experts in fleas. Xenopsylla often present. There is some confusion of thought Pathology has, too, a significant connexion with this here. It is not the presence of the crown which leads side of zoology, through its demonstration of the to apical infection, but rather the infection of the species specificity of immunological relationships. pulp canal consequent on the death of the pulp. The identification of a bloodstain by a precipitin Crowned teeth are usually pulpless, but there is no reaction does something more than bring a murderer

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