that cause septicaemic conditions, as well as infections in remote parts of the body. Hunter's revelation impressed at once the dental and medical professions and his criticisms immediately bore fruit. The general use of the X-ray as a means for study of the apical region of tooth roots, the development and application of specialized bacteriological technique for determining in pulp- less teeth the identity and character of the exciters of disease action and similarly those responsible for inflammatory lesions of the retentive structures of the teeth (commonly designated as pyorrhea aheolaris), all stimulated by the realization of the pro- found clinical importance of mouth infections as related to bodily health, quickly followed the communications of Hunter.
The total effect of this evidence, both clinical and scientific, upon the development of dentistry has been little short of rev- olutionary. From time immemorial it has been believed from empirical observation that an unclean and infected mouth cavity is a source of bodily ill health, and much direct evidence of a clinical character had accumulated to strengthen that belief, but the evidence now at hand has affirmatively established the facts by scientific demonstration. Until this development of knowl- edge concerning the systemic relationships of disorders of the teeth and their related structures and their bearing upon the bodily health, the major feature of dental interest, and that upon which the attention of the profession was concentrated, had been the development and perfection of manipulative pro- cedure in restorative operations. The ingenuity expended and the excellence of the results attained had become the outstanding characteristics of dental practice; and the restoration by prosthet- ic or operative means of the masticatory mechanism damaged by partial or total loss of teeth had been its dominating ideal. There is now an enforced recognition in the professional as well as in the lay mind of the importance of the welfare of the tissues and organs of the mouth. In the dental profession the conse- quent changes of technical procedure and objectives have been fundamental. The ideal of mechanical perfection in the methods and appliances by which the dental surgeon restores the patient's power to masticate has come to be regarded as a remedial meas- ure subservient to the larger ideal of normal mouth health.
Oral Hygiene in Schools. One of the principal factors which extended and popularized this knowledge is the oral hygiene move- ment, an effort to demonstrate practically the fact that school chil- dren, relieved of the disabilities arising from infected mouths and diseased teeth which handicap normal development, will show im- proved physical and mental efficiency. What is known as the Cam- bridge experiment, inaugurated in 1907 by the late George , Cunning- ham, of Cambridge, England, was perhaps the earliest practical test. The analogous work of Dr. Ernst Jessen, of Strassburg, re- sulted in the introduction of oral hygiene into the public schools of a number of towns in Germany. In the United States the oral hygiene movement took practical form in the test of its utility in the Marion school of Cleveland. O., in 1910, and in 1919 there was completed under conditions yielding accurate figures, a five years' test of applied mouth hygiene in the public schools of Bridgeport, under the direction of Dr. A. C. Fones. In this test 20,000 children of the first five school grades were under observation and treatment. The average number of carious cavities was found to be over 7% per child; 30% claimed that they brushed their teeth occasionally; 60% frankly stated that they did not use a tooth brush and IO% were found to have fistulas on the gums, showing outlets from abscesses from the roots of decayed teeth. Systematic application of oral hygiene, the intelligent and systematic use of the tooth brush, and the elimination of accretions, dental decay and suppurative con- ditions achieved striking improvement in general health and mental efficiency. With respect to general health the statistics of the Bridgeport board of health show that the most common fatal diseases among children in that locality were diphtheria, measles, and scarlet fever. The decrease in deaths from these sources after the introduction of oral hygiene in the public schools is shown by the following table, the figures for 1914 showing conditions before the test :
1914. 1918.
Diphtheria .... 36-6% 18-7%
Measles .... 20-0 4-1
Scarlet Fever .... 14-1 0-5
The improvement in mental efficiency is shown by the reduction in the percentage of retarded children. A retarded child as defined by the Bridgeport school board is one who is not less than two years older than the normal age for the school grade to which it should belong. The percentage of retarded children before and after the
introduction of mouth hygiene in the Bridgeport schools is shown in the following table:
Percentage of Retarded Children.
Drop in retarda-
Grade. Sept. 1912. Nov. 1918. tion
I- 16-5% 8-1% 51-0%
J{- 37-o 15-3 58-0
III. 53-o 24-7 53-0
!V. 59-5 3i-7 47-o
V. 61-0 33-1 45-0
VI 54-0 30-4 44-0
V"- 39-o 19-3 50-0
VIII. 27-0 12-s 54-0
Average. 40-0 20-1 50-0
Since retardation represents inability of the child to continue to advance with his class, it necessitates repetition of his grade work, and therefore becomes an economic question of serious importance to the ratepayer. The cost of reeducation in Bridgeport in 1912 was 42 % of the entire budget, and for 1918 only 17 %. Among the 20,000 children under observation in the schools of Bridgeport, it was found that 98% had various forms and degrees of malocclusion of the dentures, a condition now generally recognized as being associated with a symmetrical development of the bones of the face and the brain case. Many children with malocclusion owing to the arrested development of the facial and cranial bones suffer from impeded nasal respiration, and moreover develop adenoids and ton- sillar hypertrophy, leading to infection with its systemic sequelae and the interferences .with bodily nutrition incident to insufficient oxidation of the blood. Orthodontic treatment for the correction of malocclusion in children has come to be regarded as a therapeutic and prophylactic measure having an important health relation rather than as a mere cosmetic procedure for the relief of deformity. The foregoing facts furnish convincing evidence of the desirability of making oral hygiene available to children of school age as a feature of dental public health service on economic as well as humanitarian grounds and on the broader ground of national efficiency.
Work in Armies and Navies. Analogous considerations resulted in the organization in various countries of army and navy dental service of the nation. From small beginnings upon a contract basis the U.S. army and navy Dental Corps rose to an allot- ment by law of one dental surgeon for each 1,000 of the army personnel, and before the close of the World War provision had been made to double that allotment and to supply adequate equipment for field and hospital service. Instead of contract service the corps was placed upon a commissioned basis with pay and al- lowances identical with those of the Medical Corps and rank within the corps through all grades up to and inclusive of colonel. After 1918 full provision was made by the U.S. Government for the dental care of its enlisted men and of those demobilized from service suffering from dental defects or disabilities since de- mobilization. This latter activity is assigned to the dental division of the public health service. Accurate statistics as to the develop- ment of army and navy dental service in forces of other nations are not yet available, but the proportion of dental surgeons to army personnel in 1917, as given by officials of the British Dental Associa- tion (see " Man Power and the Army Dental Service," British Dental Journal, Feb. 15 1918), for some forces was: Canadian Expeditionary Force, one per 1,000 men; New Zealand Expe- ditionary Force, one per 2,500 men; Australian Expeditionary Force, one per 2,600 men. Satisfactory figures for the German army dental service are not obtainable, but according to Dr. Ernst Jessen, head of the dental work in Strassburg, quoted in the German Dental Review, there were 810 dental surgeons active in the field in 1915. France, during the World War, had at least 1,500 army den- tists working in various parts of the lines as fixed units, in addition to the dental ambulances. The French army dental service furnished a striking example of the practical importance of army dental serv- ice in that during the latter part of the war, when the man power of France was seriously depleted, over 250,000 effectives were mustered into the French service as the result of efforts instituted by Dr. Georges Villain, of Paris, by which that number of men who had been previously rejected because of loss of teeth, but were other- wise physically sound, were subsequently fitted with artificial den- tures and sent to the fighting line.
The British dental service in the World War was inadequate, owing to the limited number of qualified dental surgeons available and the unfortunate fact that of the 1,050 to 1,100 serving in the army and navy in various capacities about 300 were enlisted as combatants, and of those latter 50 were killed. (See Report of Par- liamentary Committee on the Relation of Military Service to Man Power. D. F. Pennefather, Chairman.) Great Britain created by Royal Warrant, issued Jan. 4 1921, a military dental service, the Army Dental Corps, which is administered by the Direc- tor General, Army Medical Service. The Army Dental Corps is a joint service for the army and R.A.F., and is on a commission basis with rank through the grades inclusive of lieutenant and lieutenant-colonel. Experience during the war clearly demonstrated to all the belligerent nations the importance of dental service as a
