DENOMINATOR. 



DENTITION, DISEASES OF. 



470 



or be capable of any grant of hinds, &c., from the crown ; nor will the 

 British government, it is supposed, consider an alien who has obtained 

 a certificate merely, entitled to British protection, in his own native, or 

 in any foreign country. [ALIEN.] 



DENOMINATOR, the number of parts into which a unit ia divided 

 in any fraction; thus, in 7-10th's of a unit, 10 is the denominator. 

 [FRACTION.] 



DENSITY. This term is absolutely of the same practical meaning 

 as its measure, SPECIFIC GRAVITY, implying that relation of one mass 

 of matter to another, which is suggested by our knowing that a given 

 bulk of the first weighs more than the same of the second. The term 

 has no absolute meaning ; gold is more dense than air, but neither is 

 absolutely dense, nor can we assign any meaning to the latter term. 

 It were perhaps to be wished that the shorter term, density, should be 

 employed instead of the longer one, specific gravity ; but as custom 

 has referred to the latter term all mathematical considerations con- 

 nected with the former, we do not here pursue the subject further. 

 [SPECIFIC GBAVITY.] 



DENTILS. [COLUMN,] 



DENTITION, DISEASES OF. (Difficult Teething.) Every infant 

 at the period of birth, is imperfectly organised. There is no structure, 

 and scarcely any tissue of its body, which has attained its due con- 

 sistence and firmness. Several of the most important organs are 

 entirely rudimentary, and there is not one that is perfect either in 

 structure or function. Development is the great process unceasingly 

 carried on at every point of the system. 



Among the organs the first to be developed after birth are the 

 teeth, and the jaws which are to contain the teeth. These organs are 

 agents indispensably necessary to the performance of a primary and 

 essential function that of nutrition. Before birth there are no teeth, 

 the nutrition of the foetus being carried on by nutritive matter derived 

 from the mother. For a considerable period after birth there are no 

 teeth, the nutritive matter by which the infant is to be nourished being 

 still formed for it by the mother. But the infant is ultimately to 

 acquire an existence wholly independent of the mother, and from 

 the moment of its birth nay, long before the period of birth 

 processes of preparation are going on in its system whicli have for 

 their object the formation of an apparatus destined to enable it to 

 prepare and digest food independently of ita parent. [DENTITION, 

 NAT. HIST. Div.] 



This apparatus, from its most rudimentary state, possesses a highly 

 organised and delicate structure; and it is placed in a position in which 

 its progressive development is attended with peculiar difficulties, which 

 at first view would appear insurmountable. A bony structure has to 

 be formed and to make ita way through the dense substance of the 

 gums ; at the same time the jaws have to attain a bulk fitted to receive 

 these structures when duly prepared and evolved. The too hasty 

 evolution of the teeth, or the too tardy growth of the jaws, pro- 

 duces evils in the system, by the disturbance of that balance which 

 is indispensable to the orderly and safe progress of all developmental 

 actions. 



Supposing the formation of the teeth in the jaws to have proceeded 

 quite naturally up to the time proper for their evolution, at that period 

 they are included in a firm membranous envelope, and are covered by 

 the thick and dense gum. When the process of dentition proceeds in 

 a natural manner, the membrane and the gum are absorbed in order to 

 make way for the passage of the teeth. 



This process, even when accomplished in a perfectly natural manner, 

 is almost always attended with some degree of local infl.iTnm.it.inn. 

 The gum itself is manifestly red and swollen, and is apparently painful 

 and itching, indicated as well by the obvious occasional uneasiness of 

 the infant, as by the constant desire it evinces to press against the gum 

 everything it can lay hold of. The irritation of the gum extends to 

 the salivary apparatus placed in the mouth and its neighbourhood, as 

 is proved by the increased flow of saliva, which is commonly more or 

 less altered in quality, as well as increased in quantity, being thicker 

 and more tenacious than the natural secretion. These symptoms of 

 local irritation are usually accompanied by a slight degree of consti- 

 tutional disturbance, the skin beiug commonly hotter and dryer, the 

 face occasionally flushed, the bowels more relaxed, and the infant itself 

 more restless and fretful than natural. The irritation of the gum when 

 restricted within a moderate limit seems to be the necessary conse- 

 quence of the developmental process that is going on. The effect of 

 the local irritation, namely, a determination of blood to the salivary 

 apparatus, occasioning an increased flow of saliva, and that of the con- 

 stitutional disturbance, namely, a determination of blood to the mucous 

 membrane of the intestines, occasioning diarrhoea, appear to be reme- 

 dial rather than morbid, to be evacuations established by nature for 

 the purpose of relieving over-distended vessels and over-excited nerves. 



When the infant is in a state of sound health, and when the process 

 of <1> iititii>n proceeds in a natural manner, the local and constitutional 

 evils attending the evolution of teeth amount to no more than have- 

 now been described ; but when the infant is in a state of either 

 congenital or acquired disease, or when the natural course of the 

 process of dentition in disturbed, evils result always serious and often 

 fatal. 



Su|i|,oe that the formative proceeds faster than the absorbing 

 procea* ; that the teeth grow with a rapidity with which the action of 



the absorbents is not commensurate, the necessary consequences are, 

 that the tooth is forced against the gum, that the investing membrane 

 is compressed between them, and that this pressure is communicated 

 to the delicate and soft pulp on which the organisation of the tooth 

 is still proceeding. The effects of the irritation thence induced 

 will vary according to the degree of pressure, the sensibility, and 

 irritability of the individual, and the pre-disposition of its natural 

 or acquired constitution to disease. In some it may produce only a 

 slight aggravation of the local and constitutional ailments already 

 described ; iu others it may produce every form of disease to which 

 infancy is subject, attended with every symptom appertaining to such 

 diseases. 



Iti the infant, the mucous membrane which lines the alimentary 

 canal, from its commencemeut in the mouth to its very termination, 

 is highly sensitive and irritable ; the membrane which covers the 

 external surface of the body, the skin, which possesses easentially the 

 same structure as the internal liniug membrane, and between which 

 there is the most intimate sympathy, is alike sensitive and irritable ; 

 the mucous membrane which lines the air-passages, and which forms 

 the air-vesicles of the lungs, is scarcely less sensitive and irritable. 

 Morbid irritation excited in any of these extended and most important 

 surfaces is readily propagated to the great nervous centres, the spinal 

 cord and brain, in which are induced, often with extreme rapidity, 

 some of the most formidable diseases to which the human body is 

 subject ; and from diseases established in the spinal cord and brain 

 disease is reflected back upon the muscles. Thus the most prominent 

 diseases produced by abnormal (irregular) dentition have their seat in 

 the stomach, the intestines, and all the organs which form a part of 

 the digestive apparatus ; in the external skin, iu the air-passages and 

 lungs, in the spinal cord and brain, and in the muscles of voluntary 

 motion. 



The irritation attendant on abnormal dentition commences in a 

 portion of the mucous surface of the digestive apparatus, and from its 

 source in the mouth it is readily propagated to the stomach, intestines, 

 and liver, producing iu the stomach pain, nausea, vomiting, flatulence, 

 acid eructations, &c. ; in the intestines, griping pain, flatulence, dia- 

 rrhoea ; in the liver, disordered secretion of bile, in consequence of 

 which the faecal evacuations are greatly altered in quantity and quality, 

 being at one time too scanty, and at another time too copious, some- 

 times light or clay-coloured, and at other times dark-green, spinach- 

 like, and preternaturally foetid, mixed with large quantities of 

 unhealthy viscid mucus. 



The external skin sympathising with the irritation set up in the 

 internal mucous surface, is constantly affected with eruptions of 

 various names and natures, sometimes attacking the scalp, sometimes 

 surrounding the lips and extending over the face, and at other times 

 covering the whole body. 



The irritation is propagated from the mucous membrane of the 

 mouth and fauces to that of the air-passages and air- vesicles, inducing 

 hurried, difficult, and painful respiration, frequent cough, and all the 

 symptoms of inflammation of the lungs. 



There is the closest possible connection between the skin, the 

 digestive surface, the respiratory surface, and the great nervous 

 centres, the spinal cord and brain. Any irritation excited in the 

 former is readily propagated to the latter. There is a direct route by 

 which the intercourse is established. The nerves proceeding from all 

 these surfaces take a direct course to the spinal cord and brain, where 

 they communicate the irritation which they receive, and excite, among 

 other diseases, more especially that which constitutes hydrocephalus 

 acutus, or water in the head. This disease, among the most formidable 

 to which infancy is subject, and the most common cause of which is 

 abnormal dentition, is preceded by the start in sleep, the slight chill, 

 hardly amounting to rigor ; the flushed face ; the sudden, darting, 

 transient pain in the head ; the unusual drowsiness ; and then come 

 the sudden start from that deep sleep, with a loud scream; the 

 injected eye, the dilated pupil, followed by the constant rolling of the 

 head upon the pillow, the loss of sight, and the progressively increasing 

 insensibility and coma. The irritation thus produced in the spinal 

 cord and brain is quickly reflected back upon those muscles the action 

 of which depends upon an influence derived from these great nervous 

 centres the muscles of volition, which are affected with twitehings, 

 spasms, convulsions, sometimes passing into chorea, epilepsy, catalepsy, 

 and tetanus. 



When the acute symptoms induced by inflammation of the brain, 

 followed by effusion, pass away without immediately destroying life, it 

 is often only to leave a state of permanent idiotcy far worse than 

 death. 



Besides all these evils produced by abnormal dentition, there is one 

 specific disease that results from it of a most formidable nature, and 

 often fatal. This affection may be termed the disease of development ; 

 it is commonly called infantile remittent fever. The accession of this 

 disease is denoted by languor, lassitude, chilliness, shivering, succeeded 

 by heat of skin, perspiration, and accelerated pulse. The little patient 

 is spiritless, discontented, and fretful. Yawning, sighing, marked 

 increase of irritability, unusual mutability of temper, loss of appetite, 

 perhaps alternating with importunate desire for food, which when 

 given often cannot be eaten, some peculiarity of respiration, and at last 

 impatience of light and sound, accompany or quickly follow a distinct 



