Hygiene, dental and general

Front matter

Class

Book.

Copyright N°_

Preface

There are many reasons why the dentist should have an authentic and fundamental knowledge of hygiene. Whether willingly or unwillingly, he is placed in the position of an adviser. The ordinary practice of his profession is not alone concerned with the hygiene of the mouth. Troubles which he is endeavoring to prevent, correct and improve, affect the general health and are reacted upon by it. Moreover many people consult the dentist who do not visit a physician and to most of these he is a "doctor" who is expected to know not only the facts relating to infection, but also the rules for health. Many a practicing dentist can testify that he is questioned on every health problem from diet to municipal sanitation.

How much ought the dentist to know about these subjects? Obviously he should have the most definite knowledge available upon the interrelationship between abnormal conditions of the mouth and other organic and systemic defects. His knowledge of the danger of transmitting disease in dental practice should be equally definite. The rules of personal hygiene are of use to him not only in regulating his own living but also in getting the best results with his cases. To prescribe a schedule of hygienic living will often do as much as an office treatment in getting the patient into a normal condition.

Public health activities also have a right to claim the attention of the dentist. He is coming to take an increasingly larger part in municipal, school and industrial Hygiene and lie should know the powers, organization and responsibility of the health agencies of the government. But apart from these fields in which he is interested professionally he has special duties of citizenship, for his training has given him a basis for appreciating the value of hygiene and sanitation. Excepting possibly the physician and sanitarian no one in the community can so well understand the possibilities and b PREFACE

advantages of efficient public health administration. The dentist may well be expected to assume some degree of leadership in these matters and if he is able to do so successfully his standing in the community is markedly benefited both socially and professionally.

There has hitherto been no treatment of the subject of hygiene specially prepared to meet the needs of the dental profession. In writing this book for the dental student and practitioner, special attention has been given to those phases of the subject which relate to dental practice wherever they occur.

In arranging the order of the text, those aspects of both dental and personal hygiene that are not related to infection are first considered. Then follows a discussion of the development of the new science of disease prevention and its effect upon dental practice, personal hygiene, and the public health.

The author desires to acknowledge gratefully the assistance received from many persons in the criticism of the manuscript. In particular thanks are due to Professor Percy Gr. Stiles of the Harvard Medical School for reading some of the manuscript on personal hygiene and for assisting in the preparation of a diagram of the autonomic nervous system. Special thanks are also due to Dr. F. H. Slack for reading the chapter on immunity, to Dr. F. A. Woods for suggestions in connection with the material on heredity, to Dr. A. LeEoy Johnson for assistance in the chapter on oral hygiene, and to other teaching associates for stimulating and helpful suggestions.

The author also wishes to express appreciation to Professor C.-E. A. Winslow for permission to use cuts number 6, 9, 10, 29 and 31 from Healthy Living, to Dr. Lawrence Baker for permission to use cuts number 3 and 4 from one of his unpublished researches, and to the many others who have assisted in securing illustrative material. ^ -p t> ttrnfr

Massachusetts Institute of Technology, Cambridge, Mass.

Chapter I Dental Hygiene Page

The Divisions of Personal Hygiene — Hygiene of the Mouth — The Form and Arrangement of the Teeth — Contact and Occlusion — Orthodontia — Function — Deforming Habits — Structure of the Teeth— The Investing Tissues— The Saliva 17

CHAPTEE II

THE HYGIENE OF NUTRITION

Diet — Water — > Nitrogenous Foods — Carbohydrates — Fats — Inorganic £>alts — Vitamines — Dietary Diseases — Balanced Diet — The Varied Diet — Digestion — Digestion and the Emotions — The Hygiene of the Emotions — Mastication — Water with Meals — Rest after Eating — Assimilation — Assimilation Defined — Oxidation — Eliminating the Body Wastes — Autointoxication — Constipation — Food Poisoning — Obesity — Under-eating — Conclusions 33

Chapter III The Hygiene Of Action

Two Kinds of Bodily Activity — Exercise — What Exercise Does for the Body — Types of Physical Exercise — Rhythm in Exercise — Walking — Ordinary Body Activities — Figure — Round Shoulders — Carrying the Head Forward — Spinal Curvatures — Deformities of the Feet — Ocular Hygiene — Breathing — Bathing — Clothing 54

Chapter IV The Hygiene Of The Central Nervous System

Function — Concentration — Habit — Sleep — Dreams — Change of Work — Sunday Observance — Neurasthenia — Overwork — Emo^ tions — Bodily Defects — Stimulants — The Neurasthenic ... 68

Chapter V The Hygiene Of Reproduction

The Problem Defined — Heredity— Mendelian Inheritance — How Sex in Offspring is Determined — Sex Linked Characters — Inherited Diseases and Abnormalities — Mentality and Heredity — Feeble-mindedness— Heredity and Conduct — Prenatal Care —

8 CONTENTS

PAGE Standards for Maternity Care — Infant Care — The Obligation of the Community to the Infant and the Preschool Child — Sex. Hygiene — Sex Education — Summary — The Child's Ten Commandments to Parents 80

Chapter VI The New Science Of Disease Prevention

Communicable Diseases — Early Theories of Disease — Fore-shadowings of the Present Theory — Fermentation and Disease — Pasteur — Lister — Koch and the Development of Bacteriology — Preventive Medicine — Smallpox and Vaccination — Immunity in Anthrax and Rabies — Diphtheria and Antitoxin — Preventive Sanitation — The Epidemic of the Broad Street Well — A Typhoid Fever Epidemic from Oysters— Preventive Hygiene — Resistance — Summary 108

Chapter VII The Essential Facts Of Immunity

Immunity Defined — Nonspecific Immunity — Fatigue — Exposure to Wet and Cold — Drugs — Under-eating — Oral Defects — Specific Immunity — Natural Immunity — Local Immunity — Acquired Immunity — Active and Passive Immunity — Carriers — Disease Reactions — Toxins — Endotoxins— Tractive Phenomena — Phagocytosis — Anaphylaxis — Specific Substances — Theories of Immunity — Exhaustion Theory — Retention Theory — Phagocytic Theory— Side Chain Theory -. .... 125

Chapter VIII

Caries — Diet in Relation to Decay — The Care of the Gums and Gingivae — Gingivitis — Deposits — Prophylactic Treatment — The Dental Hygienist— Daily Care of the Teeth— Method of Brushing the Teeth — Care of the Brush — Dental Floss — Toothpicks — Mouth Washes — Tooth Powders and Pastes — Tooth Cleansing Foods — Care of the Mouths of Children — Septic Teeth as a Source of Systemic Disease 144

Chapter IX

Three Great Plagues — Tuberculosis — Prevalence — The Difficulties — • Transmission of Tuberculosis — Prevention and Control — Syphilis — Importance — Nature of the Disease — Transmission — Immunity — Prevention — Educational Program — Common Cold — The Cause of Colds — Catching Cold — Influenza — Cause — Morbidity and Mortality Rates — Immunity — Control 165

CONTENTS 9

PAGE CHAPTER X

Public Health Authority— Federal Public Health Fuuctions— The Power to Regulate Commerce — Taxation — Defense and Welfare Powers — Treaty and War Powers — The U. S. Public Health Service — Other Federal Agencies — State Health Functions — Public Health Laws — State Health Administration — Organization — Administrative Functions — Local Health Administration — Authority — Local Health Organization — The Health Officer— Unofficial Health Activities 188

Chapter XI

Food Adulteration — Cost of Adulteration — Nature and Cause of Adulteration — Pure Food Laws — Misbranding — Law Enforcement — Food Sanitation — Milk — Graded Milk — Remade Milk — • Meat — Dangers in Meat — Prepared Food 209

Chapter XII

What Is Good Water — Sources of Water Supply — Water Analysis — Environment — ' Bacteriological Study — Physical Tests — Chemical Tests — Nitrogen and the Nitrogen Cycle — Chlorine — Microscopic Analysis — Water Purification — Storage — Filtration — Chlorination 22(3

Chapter XIII

Sewage Disposal — Direct Disposal — Chemical Purification — Bacteriological Purification — Aerobic Processes — Anaerobic Processes — Possibilities and Limitations of Sewage Purification — Rural Sanitation — Report of the A. P. H. A. Committee . . 243

Chapter XIV

The Problem — Special Groups of Defectives— The Scope of School I [ygieni — Health Control — Personnel — Physical Examination — Treatment — Administration — Defect ive Vision — The Dental Care of School Children — Teaching Hygiene in Schools — School Hygiene and Sanitation — Age and Sex Differences — Standards ' 274

10 CONTENTS

PAGE

Chapter XV

General Aspects of Industrial Hygiene — General Problems — Hours of Work — Fatigue — Child Labor — Women in Industry — Factory Inspection — Health Administration in Industry — Accident Prevention — Industrial Sanitation — Food — Medical Activities — Industrial Dentistry — Disease Prevention and Health Education — Industrial Diseases — Lead Poisoning — Phosphorus Poisoning — Mercury Poisoning — Benzene Compounds — Acids — Protection against Industrial Poison 301

Chapter XVI

Good Air Defined — Temperature — Moisture — Odors — Testing Air — The Sling Psychrometer — The Hygrodeik — The Polymeter — The Comfort Meter — Ventilation and Heating — Natural Ventilation — Artificial or Mechanical Ventilation — Moisture in the Air — Air Washing and Humidifying Cooling Air — The Economic Value of Good Ventilation — Lighting — Office Lighting . 323

APPENDIX A

The American Public Health Association Committee Report upon: Actinomycosis — Acute Infectious Conjunctivitis — Ankylostomiasis (Hookworm) — Anthrax — Cerebrospinal Meningitis — Chicken P'ox — Cholera — Dengue — i Diphtheria — Dysentery (Amebic) — Dysentery (Bacillary) — Favus — German Measles — Glanders — Gonorrhea 1 — Leprosy — Malaria — Measles — Mumps — Paratyphoid Fever — Plague — P'neumonia (Acute Lobar) — Poliomyelitis — Rabies — Rocky Mountain Spotted or Tick Fever — Scarlet Fever — Septic Sore Throat — Smallpox — Syphilis — Tetanus — Trachoma — Trichinosis — Tuberculosis (Pulmonary) — Tuberculosis (Other than Pulmonary) — Typhoid Fever — Typhus Fever — Whooping Cough — Yellow Fever 339

APPENDIX B

Definitions — Disinfection versus Sterilization — Antiseptics — Deodorants — Fumigation — Disinfection — Control of Disinfection — Natural Disinfection — The Ideal Disinfectant — Standardizing Disinfectants — Physical Agents of Disinfection — Gaseous Disinfection — Formaldehyde Gas — Sulphur Dioxide — Oxygen — Hydrocyanic Acid — Liquid Disinfectants — Mercuric Chloride — Formalin — Potassium Permanganate — Lime — Whitewash — Milk of Lime — Disinfection in Dental Practice — Hands — Materials —The Office 378

Bibliography 389

Index 394

ILLUSTRATIONS

FIG. PAGE

1. Model illustrating normal occlusion 20

2. Model illustrating normal occlusion 21

3. Asymmetric development of the bones of the skull of a dog . 22

4. Upper aspect of the skull shown in Fig. 3 23

5. Deformity from lack of function 24

6. Air passages of the mouth and nose showing their relationship

to the adenoids and tonsils 25

7. Deformity due to thumb sucking . . . 26

8. Diagram illustrating groups of fibers of the gingivae and peri-

dental membrane *..<,,.., 29

9. The composition of cow's milk 40

10. Portions of different foods each yielding approximately 100

calories of heat energy 41

11. Diagram, showing the most important distributions of the auto-

nomic nervous system 46

12. The worry-auto-intoxication cycle 50

13. Good and bad postures 60

14. Posture chart showing the result of the examination of Har-

vard Freshmen . 61

15. Inheritance in guinea pig showing where one color dominates

over another color 81

16. Diagram illustrating the mechanism by which the unit factor,

color, is inherited in guinea pigs .83

17. Eminent twins 84

18. Transmission of color blindness 87

19. Cholera deaths in the epidemic of the Broad Street Well . . 119

20. Diagram illustrating the three orders of immunity as described

in Ehrlich's Side Chain Theory of Immunity 141

21. Deformity resulting from neglect of the teeth 144

22. Showing malocclusion due to caries 145

23. Diagram illustrating nomenclature of gingiva) 149

24. Diagram illustrating nomenclature of gingivae 149

25. Dental hygienists in Prophylactic Clinic at Forsyth Dental In-

firmary for Children 154

26. Tooth brushes of proper shape and material 158

12 ILLUSTRATIONS

FIG. PAGE

27. Comparative figures showing the number of disease and battle

deaths each year per thousand troops in the wars of the United States 166

28. The relative proportion of army deaths caused by the principal

diseases in the war with Germany 167

29. An inexpensive and easily constructed outdoor sleeping porch . 173

30. Chart showing the time and temperatures at which bacteria

are killed and at which the quality of the milk is changed . 217

31. Pasteurization of milk at home 218

32. Pollution of wells by water which soaks through the soil from

privies or cesspools 229

33. The nitrogen cycle 232

34. Diagram shoAving the condition of the stream studied at Brock-

ton 237

35. Diagram showing the abundance of microorganisms at the va-

rious sampling stations 238

36. Shows how completely the higher aquatic plants fill part of

stream in summer 239

37. Showing how differently the same region appears under winter

conditions and high-stream flow 239

38. A chemical closet installed in a home where running water is

not available 245

39. Eemoving the sludge from the sand beds at the Brockton Sew-

age Purification Works 248

40. Imhoff tank 252

41. Sewage purification plant in Atlanta, Ga. 254

42. A single-seated sanitary privy 260

43. Bear and side view of privy 261

44. Outdoor incinerator (Arnold type) 268

45. Floor plan and arrangement of medical inspector's room gen-

erally followed in New York City 281

46. The effect of treatment for adenoids upon the general appear-

ance of three children 284

47. Errors in refraction . . . , 285

48. Dental Clinic at the Forsyth Dental Infirmary for Children . 290

49. Wet and dry bulb thermometer 327

50. Sling psychrometer 328

51. Hygrodeik instrument 329

52. Portable foot candlemeter 338

Foreword

By William T. Sedgwick, Sc.D.

Professor of Biology and Public Health, Massachusetts Institute of

Technology, Chairman Harvard-Technology School of

Public Health, etc.

Whoever regards the human mechanism objectively cannot fail to be struck with the growth and function of its harder parts. Bones, nails and teeth, though wanting in the early embryo, are rapidly formed soon after independent life begins. The bones, securely covered, are rarely exposed to decay or wear, and the skeleton in age is in many respects more complete and perfect than in youth. But with the teeth it is otherwise. Pushing outwards through the soft parts these are very early exposed to unfavorable conditions and, like knives and millstones, become dull and worn with use. Eventual) y, if not forcibly removed they fall out, so that at the end of life man is often "sans teeth," though not "sans everything" — no other organs of the body except the hair and epidermis being thus deciduous.

Hence it is that the teeth for their protection require unusual care — a fact now generally recognized by the rise of the dental profession and the popular enthronement of the toothbrush. But scientific care of any of the organs of the body is neither more nor less than hygiene, so that Dental Hygiene — the scientific care of the teeth — is one of the fundamentals of all hygiene. And since the human body is not merely an assembly of discontinuous and unrelated parts, but rather a complete entity or organism — originally homogeneous and never more than incompletely differentiated — so much so that the hand cannot say to the foot, or the brain to the teeth, "I have no need of thee" — it follows that dental hygiene is

14 FOREWORD

only a part of General Hygiene. Accordingly, while this book deals with the hygiene of the teeth and takes its beginnings with the teeth it does not — because it cannot — end there. Foods and feeding, the flow of saliva, the blood stream and the lymph drains and, more remotely but not less surely, sleep and rest, work. and play, muscular activity and mental fatigue — all these and many more aspects of general hygiene contribute to the welfare of the teeth. Conversely, the health or disease of the teeth plays an all-important part in the welfare of the other organs of the body and of the body as a whole, as all know who have been incapacitated by acute toothache.

Professor Turner's is the first work which, taking for its principal field the hygiene of a single set of organs, reaches out from these to the rest of the body. And perhaps it is for this reason that our textbooks of hygiene have so often hitherto been comparatively uninteresting and ineffective. It may be that they have been too general and in seeking to tell all things about hygiene have failed to tell any well. It is for this reason among many that I predict for this work an unusually hearty welcome, for those who read it attentively will find that while the text of the sermon is dental hygiene, and while the teeth — as in the speaking human face — are always near and much in evidence, the lessons taught apply quite as well to the entire human body and its effective conservation. Such conservation, however, not only requires careful consideration of the human body but of that environment with which the body deals and which plays upon it from birth to death.

Fifty years ago the slogan for health was mens sana in corpore sano — an admirable aphorism but one curiously typical of a neglect of environment characteristic of the pre- Darwinian period. Nowadays we know only too well that the sound mind and the sound body are unavailing for the conduct of normal living unless the environment with which

FOREWORD 15

they have to deal consists of fairly good air, fairly pure water, fairly good food, and is fairly free from communicable diseases, unfavorable temperatures, defective ventilation, dirt, noise and other prejudicial sanitary conditions. Hence, Professor Turner surveying the whole field of dental and general hygiene has found it necessary to reach out beyond the teeth and other organs of the body, and even beyond the body itself, to a consideration of those environmental factors which contribute so heavily to health or disease, with the result that his work is not merely novel and comprehensive, but also original, logical and representative of the best hygienic thought of the time.

Chapter I Dental Hygiene

Hygiene or the science of healthful living furnishes to man the basis for a rational control over those habits and conditions of existence which affect for good or ill the smooth and normal operation of the body mechanism. The development of healthful habits of life depends primarily upon the individual, but the maintenance of healthful living conditions is largely beyond individual control, and the responsibility rests upon organized society. In the restricted sense hygiene considers the health of the individual, sanitation the control of the environment.

In considering the hygiene of both the mouth and the body as a whole there are two distinct sets of problems: (1) the proper development and normal functioning of the parts and (2) the problems arising because of infectious organisms. In this book the two subjects are separated, the first-mentioned receiving consideration in the first five chapters.

The Divisions of Personal Hygiene. — Personal Hygiene as contrasted with public hygiene or public health considers those principles and activities for the promotion of health over which the individual has control, and to determine the scope of this science we have to consider the functions of man as an animal. In blunt and simple language nature has decreed that man shall eat, work, think, and breed. The zoologist expresses this idea more elegantly and scientifically by saying that the particular functions of animals are assimilation, action, sensation, and reproduction. Accepting either set of terms in their broad sense we may group the problems of Personal Hygiene under these four heads:

3. Hygiene of the Central Nervous System.

HYGIENE OF THE MOUTH

The subject of Hygiene concerns the health of the body in all its parts and there is no natural division which makes it necessary to consider any particular portion of the body under a separate head; nevertheless Dentistry is such a distinct and highly specialized subject that it will certainly be profitable to treat the hygiene of the mouth in detail and apart from the above mentioned divisions, for the dentist's interest is of necessity centered upon oral conditions and, for this reason, he should be able to speak with authority upon the means available for the preservation of the health of the various oral structures and of the relationship of oral health to the general well-being of the entire organism. We are perhaps warranted therefore in adding another division of the subject for the purposes of this volume, namely the Hygiene of the Mouth.

In the treatment of this subject it seems desirable to consider it under two heads: (1) Proper development and normal functions of the oral structures (Chapter I), and (2) The treatment and prevention of unhygienic or septic conditions (Chapter VIII).

We will consider the means provided by nature for the maintenance of oral health under four headings, as follows:

1. Form and arrangement of the teeth.

2. Structure.

3. Investing tissues.

4. Saliva.

1. The Form and Arrangement of the Teeth should be such that their relationship offers the highest degree of correlation ; each tooth performs its functions as a dependent unit in a perfect machine operated under the motive power of the muscles of mastication.

A study of normal conditions is necessary and a conception of the normal should be constantly held in mind as a definite picture. The question may well be asked: What is the normal? Does it ever exist in fact? Johnson defines normal as applied to morphology as signifying "a standard determined by constancy. ' '

The teeth are in four classes, incisors, cuspids, bicuspids and molars, each class designed for a particular function in the process of mastication. The type or form of the teeth in each of these classes varies according to the shape of the face of the individual, as Williams has shown in his classic work. ("Classification of Human Tooth Forms," Journal of the Allied Dental Societies, Vol. IX, No. 1.)

Contact and Occlusion. — When the teeth are in normal alignment the approximating surfaces of the teeth in each jaw are in actual contact at one point, known as the contact point. The object of this contact is the protection of the investing tissues. This is accomplished by preventing the crowding of food into the interproximal spaces. Any deviation from normal alignment or the loss of any tooth in the arch, (with the possible exception of the third molar) will result in impairment of function and a loss of the protection to the investing tissues; and opportunity w T ill be afforded for the crowding of food material between the teeth, thereby establishing a condition favorable to fermentation and putrefactive changes.

The alveolar process, which is the bony tissue surrounding the roots of the teeth, is a temporary structure designed to furnish support to the teeth while present within the jaw. It is built up around the roots of the teeth as they develop after the eruption of their crowns and is removed by the process of absorption after the loss of any tooth. It follows, therefore, that after the premature loss of a tooth and the removal of its supporting process, no stimulus remains for bone development; the continuity of the entire arch is broken and the teeth tend to drift in the direction of least resistance. This results inevitably in the loss of the normal relationship between the approximating surfaces of the teeth of each jaw as well as the occlusal relationships of the teeth in opposing jaws. Serious deformity may follow.

Smith has shown {Journal of the Allied Dental Societies, Vol. I, April, 1906) that in certain cases of malocclusion the timely and well judged extraction of teeth may result beneficially by relieving the crowded condition. The tendency of the drift may then bring the surfaces of the remaining teeth into positions closely simulating the normal.

Fig. 1. — 'Model illustrating normal occlusion.

Orthodontia. — We agree with Johnson that the attainment of the ideal normal occlusion of the teeth by orthodontic interference is not always possible and in many cases an attempt to bring this about will result in an inharmony in the relationship of the teeth to the general contour of the bony and muscular structures of the face which nature will not tolerate. Not only will it be impossible to retain the teeth in their new position, which is an abnormal one, but there may ultimately result a deformity more objectionable than the original condition. Extensive orthodontic treatment

DENTAL HYGIEXE 21

should be undertaken only after a careful study of all prevailing conditions by one whose vision is not limited to the teeth alone. It is futile to attempt to permanently establish ideal normal occlusion when all the forces of nature are being exerted to maintain the position of the teeth in their relationship to the organism as a whole.

Development. — Let us revert to the period of development. Baker has shown in his researches upon animals that the normal development of the dental arches is dependent upon the presence within the jaw of the developing teeth. The development of the bone is synchronal with the development of the roots of the teeth. The removal of the teeth from one side of the jaw was shown to cause an arrested development of the bone which resulted in marked deformity. The inharmony of the side of the face from which the teeth were removed was very apparent. It was further demonstrated

Fig. 2. — Model illustrating normal occlusion.

that normal development of the entire bony structure of the head is to a certain extent dependent upon the proper development of the teeth.

Function. — Among the causes of malocclusion must be considered the dependence of development upon function. For instance, a study of the organs of mastication of the anthropoid ape (man's prototype) reveals massive structure, demanded by the functional activity incident to the mastication of the kind of food available for his sustenance and upon which his existence depended.

With the development of modern methods for refining the raw materials to be used as food and the acquirement of the epicurean habit — which demands the preparation of complex, highly seasoned food calculated to stimulate pleasurable sen-

Fig. 3. — Observe the asymmetric development of the bones of the skull of a dog due to the interference with the function of the upper left lateral half of the dental apparatus.

sations in those whose appetites are already satiated by overindulgence — the necessity for vigorous muscular effort has been removed and the stimulating effect of vigorous functioning has been lost. The lower part of the face has thus been reduced in size but the teeth have not relatively changed. The result is that the teeth of many people are out of harmony in size with the rest of the features.

All variations from the normal in the development of the

Fig. 4. — Upper aspect of the skull shown in Fig. 3.

various units, which are interdependent, must of necessity affect the proper functioning of the organism as a whole and, therefore, become problems in hygiene.

Although there is a difference of opinion on this subject, there are orthodontists who believe that the normal development of the oral structures is also impeded by substituting the artificial feeding of the infant in the place of breast feeding. "Whoever has observed carefully the infant in the act of nursing must have noticed that much exertion is put forth in the effort to obtain the milk. It is upon this muscular effort, and the enforced position of the oral structures during the act of sucking and swallowing that normal development is in a considerable degree dependent. No bottle feeding device perfectly simulates the breast or affords the

Fig. 5. — Deformity from lack of function. Ankylosis prevented the movement

of the jaw.

vital muscular resistance which supplies the essential stimulus for the development of the oral structures of the growing infant.

Deforming Habits.— Deformities of the face and jaws arising from mouth breathing or other habits contracted in infancy, such as thumb-sucking and the continued use of pacifying devices, deserve consideration.

One of the most common causes of mouth breathing is the presence of adenoids in the posterior nares which so fill up the space required for normal breathing that the child resorts

DEXTAL HYGIENE to mouth breathing in order to obtain sufficient air. Adenoids are enlarged lymphoid follicles. These follicles are normally present in the nasopharynx but from various sources of irritation they frequently become congested and swollen.

The deformities resulting from the use of pacifying devices are frequently seen; and their use either reflects upon the intelligence of the parents or they are used in utter disregard

%X~Adenoids

Fig. 6. — The air passages of the mouth and nose showing their relationship to the adenoids and tonsils.

of the welfare of the child. In any case the resulting deformity is a constant rebuke to the neglect of the child.

The thumb-sucking habit may be overcome by binding the arms of the child to its side or by the use of celluloid hand protectors. The deformity 'of drawn-in arches which results from thumb-sucking is so characteristic as to be unmistakable, and not only interferes with the functioning of the teeth but destroys the entire contour of the mouth.