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occurring between the third and twenty-fourth months, allowing this period to embrace that of more active dentition, does not amount, annually, to one-seventh of the number born. Thus, in the last volume of the Registrar-General's Reports, the deaths in England for 1849, between the ages of 3 and 24 months inclusive, amounted to 40,847, while the number born was 295,158, making the number of deaths less than one-seventh. Dentition, taking place as it does, generally speaking, about the same time in all children, we should find, were its concomitant disorders of so fatal a character, that the infantile mortality at the period of its occurrence, if not relatively increased, would, at all events, not be materially diminished. Instead of that, however, "we find, with this cause of disease superadded to those previously existing, that about this very time the mortality commences, and continues afterwards, to be to a considerable extent smaller than before. From the 4th to the 14th month, allowing for extreme cases, has been stated as the period during which the teeth commence to make their appearance. According to Fox, the average date of their eruption is the 6th, 7th, or 8th month of infant life: Hunter, the 7th, 8th, or 9th; Blake, the 6th, 7th, or 8th ; and BeJ] the 5th, 6th, 7th, or 8th. Allowing, then, the eruption of the temporary teeth to commence during the 6th, 7th, or 8th months, we shall find, by calculating according to the data afforded by different tables of mortality for the first periods of infant life, given in "M. Quetelet's Treatise on Man," that the following ratios are obtained:—

Of 100,000 born, there remain alire at the end of the

1st month, 90,396, or 9604 die during 1st month.

2d „ 87,936, „ 2460 „ „ 2d „

3d „ 86,175, „ 1761 „ „ 3d „

4th „ 84,720, „ 1455 „ „ 4th „

5th „ 83,571, „ 1149 „ „ 5th „

6th „ 82,526, „ 1045 „ „ 6th „

12th „ 77,528, „ 4998 „ before 12th „

Thus, of 83,571 alive at the 5th month, 1045, or nearly ^g, die during the sixth month; while of 82,526 alive at the sixth month, there die before one year 4998, or only ^0 in the next guv months.

The following ratio is given, according to the data afforded bv another table of M. Quetelet:—

0 to 1 month 20,642 deaths.

1 ... 2 ... 5,233 ...
2... 3 ... 3,748 ...

3 ... 4 ... 3,090 ...

4 ... 5 ... 2,467 ...

5 ... 6 ... 2,213 ...

6 ... 8 ... 3,525 ...

The deaths here, during the 7th and 8th months, being 1155 less than during the 5th and 6th.

In the Registrar General's Returns for England, we find abstracts occasionally given of the comparative mortality at different ages in different years. Taking that for the years 1839-44 inclusive, p. 214 of vol. for 1847-48, as an average example, the annexed table will be found to give the ratio as exhibited there :—

[table]

The steady decrease in mortality exhibited by this table confirms what has been already advanced.

In the last published volume, namely for 1849, we likewise find the following table, as exhibiting the rate of mortality at different ages:—

[table]

Here we find 9,835 dying between the third and end of the sixth month, and only 15,031 between the sixth and end of the twelfth, or 4,639 less than if it continued at the same ratio as from the third to the end of the sixth, as the mortality would at that rate amount to 19,670 instead of 15,031.

While these statistics indicate so plainly the decrease of mortality during the eruption of the temporary teeth, there even appears to be a somewhat analogous circumstance connected with the evolution of the permanent set; for about the sixth year we find the degree of mortality became again suddenly reduced, and remaining extremely small until the age of puberty.— (Quetelet.) Whether or not the decrease in the rate of mortality depends upon, or is connected with, the conditions existing at the eruptive stage of dentition, may be difficult to determine, but the tables above quoted clearly demonstrate, that as the period for the evolution of the teeth advances, tidegree of mortality is checked, and appear to afford abundin: evidence that the influence of this process is inconsiderable in the production of fatal effects. There seems to be little chance of (kilter in statistics of so general an application to their subject as these ar<. since the process of dentition is one which of necessity takes place, and does so within a limited period of time, so that were its effecu of the unfavourable character generally represented, they couL scarcely avoid displaying themselves in a more obvious manner.

While these remarks are advanced as illustrative of the misconception prevailing in reference to the danger resulting from dentition, it i.s not meant to dispute the fact that important symptoms may exhibit themselves in connection with this process as it ocean in man, but rather to point out that too great anxiety exists with regard to it as a necessary, an unavoidable cause of suffering; aa opinion, if not arising from, at least increased by the obscurity and uncertainty involving the whole process, and extending to those principles upon which its treatment requires to be based.

It is in man alone, with the exception of a very few problematical cases, said to have occurred among the lower animals, that dentition is attended by those morbid symptoms manifested previous to atxi during the appearance of the temporary teeth; and the probability is, that in man alone do they ever occur, since an explanation of thein is to be found in causes which exist in no other animal. In considering the nature of the symptoms attending laborious dentition, we must look principally to the organic condition of those textures implicated in the action going on; recollecting that the teeth during their development and rapid growth, while acting in one sense as foreign and partly inorganic bodies within the gum, are endowed with a very high degree of vascularity and sensation, so that whatever pressure they may exert on contiguous parts, re-acts upon themselves with still severer effect, that again being aggravated in its consequences by the condition of the whole nervous system at this period of life. Whatever complications may arise as secondary consequences of dentition, pain seems to be its most frequent as well as its most simple accompaniment, and it is to the immediate causes of this condition, as mainly productive in its results, of those maladies observed to be more common about this age, that attention has been so often directed. Locally, the inconvenience seldom exceeds mere irritation; that, however, sometimes increasing to a considerable extent; and although almost universally asserted, it seems not to be satisfactorily established, that this arises from the cutting or penetration of the teeth through the superincumbent tissues, but from other circumstances special to man alone.

That the passage of a tooth above the gums, constitutes the principal cause of the disorders attending dentition, is a theory which, however questionable as to its accuracy, is yet home out. by the statements of our highest authorities on the subject. Mr Hunter remarks atp.80ofhis "Treatise on theTeeth",—"These twenty teeth, in cutting the gum give pain and produce many other symptoms which often prove fatal to children." And again, at p. 113, " While the operation of growth is going on, another operation is produced, which is a decay of that part of the gum and socket which covers the tooth, and which becomes the cause of the very disagreeable and even dangerous symptoms which attend this process. As the teeth advance in size they are in the same proportion pressing against the sockets or gums, from whence inflammation and ulceration are produced." Mr Fox, speaking of the same subject, at p. 73 of his work, says,—"The excitement occasioned by the passage of the tooth through the gums, often gives rise to the most alarming constitutional symptoms, which are always, with difficulty, alleviated and not unfrequently terminate in death." Mr Tomes, one of the latest authorities on this question, seems inclined to maintain the same opinion, and states at p. 128 of his work on "Dental Physiology and Surgery," that "Pressure, produced by the growing tooth upon the inflamed gum, and indirectly upon the formative pulp, are justly considered as the more immediate cause of these symptoms." Then, alluding to induration of the gum as another cause of them, a number of cases are cited in support of this opinion, where, after incising the gums the morbid symptoms disappeared, while the most serious results are adduced as the consequences of neglecting this operation. All of these authors, and many others advocating the same opinion— that the disorders accompanying dentition are produced by the pressure exercised by the teeth in a direction perpendicular to the socket at the time of their eruption from within the maxillae.

With regard to the teeth forcing a passage through the gums, being considered as a cause of so much suffering, it must appear remarkable, first, that this process should occasion so much more distress in man than is met with under the same circumstances in the lower animals; and secondly, that it is about the time of the appearance of those very teeth best calculated by their form, for making a way through the jaws and gums—namely, the incisors and canines —that the greatest amount ot distress is experienced. Both instances are remarkable, and both admit of explanation in a similar manner, by the want of sufficient Literal space for the accommodation of the teeth within the jaw. When compared with those of the lower animals, much less space exists in the human maxillae for the accommodation of their proper complement of teeth; for, it must be recollected, that man stands alone as an exception to the rest of the animal kingdom, having a similar arrangement of teeth, in having no space vacant in the dental arch, not even for the reception of the canine tooth of the opposing jaw—and when we reflect, that in the nearest approximation among the lower animals to the closely packed teeth of man, there still exists an empty space adjoining the canine teeth, of at least nearly their own breadth, it must be obvious that all lateral pressure on these organs both before and after their eruption. mast be considerably diminished. But not only is there no vacant space in the human jaw, but there would not even be room sufficient for containing the teeth already present, were it not for the protracted duration of the rudimentary saccular condition in the canines, which persists after the ossification of the crown in all the other teeth. It must be recollected that the arrangement of the temporary teeth within the jaw, previous to their evolution, is not as in the permanent set, irregular and adapted to the accommodation existing for their lodgment, but in a regular arch, each tooth occupying its future relative position to the others, and all very nearly on a level at the crowns. In this position we find ossification commencing in all the temporary teeth, with the excejvtion of the canines; as, for some time subsequently to this, the space between the lateral incisor and first molar being inadequate for the reception of the tooth destined to be placed there, ossification does not commence in it till a late period, and even then, in many cases, the space has become barely, if sufficiently large, for its accommodation.

The removal, upon the teeth being cut, of all symptoms of irritation, is, with much less probability, due to the process of perforation of the gums being completed, than simply to the dislodgment, so far, of the unyielding, enamel-coated wedges, constituted by these teeth, from being impacted between those still remaining within the jaw— only the root, or small end of the wedge of the teeth cut, now occupying its former situation. For, the tooth, having once perforated the gum, protrudes beyond it with great rapidity; and this does not arise from enlargement of the tooth itself, by the growth and elongation of its fang, but from its being actually lifted out of its socket by the contraction of the sac at its coronal portion; since the inner surface of the sac is attached to the fang, as far as that point where the enamel commences, and there becomes detached, forming in a manner a loose covering to the crown; so that, when this part of the sac is opened by the tooth, its cut edge having a fixed point hy its attachment at its free extremity to the gum, and adhering as it does to the root by its deeper margin, the contraction of the portion of the sac, intermediate between these two points, dislodges the tooth from its socket, leaving a vacant space between the bottom of the alveolar cavity and the extremity of the root. In the case of the canine teeth, deficient amount of lateral space is still more obviously manifest; as here a positive increase in the size of the jaw must of necessity take place before they can possibly be accommodated. And at least, in this instance, when the canines commence to be ossiBed, while also rising from the alveolus, the probability of lateral pressure seems quite sufficient to account for the more urgent symptoms frequently accompanying the eruption of these teeth, without taking the penetration of the alveoli and gums into consideration at all.

Lateral pressure, from the arrangement of the temporary teeth within the jaw previous to their eruption, seems then a sufficient and reasonable explanation of the peculiar and exceptional symp

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