THE Teeth, Formation, which are the hard­est and smoothest Bones of the Body, are formed within the Cavities of the Jaws. Above the Gums they are not covered by any Membrane, but within their Sockets are invested with the common covering of all other Bones; viz. the Periosteum, a fine transparent Skin, observable in scraping any Bone, after the Meat is taken clean off.

The Number of Teeth in a grown Person are generally thirty-six; more or less according to Age, Constitution, &c. As they are not all formed at once, so neither do they all appear at the same time; the last but one, of the great Teeth in each Jaw, 'tis remarkable, sel­dom appears 'till about the Age of twen­ty-one, [Page 2]and the last, sometimes not till that of forty.

Each Tooth is composed of an in­ternal bony Substance, and an exter­nal vitrious Cortex, of a solid hard Con­sistence, and of the Colour of Ivory. The Uses of this glossy Substance are to prevent the Teeth being worn by the Friction they undergo in Mastica­tion or Chewing; and to preserve their bony Substance from the Air.

The different Shape and Series of the Teeth are sufficiently obvious; the four front Teeth in each Jaw which are thin and broad, are called Incissores or Cutters, from their cutting or dividing the Aliment. The Canini or Dog-teeth, which are two in each Jaw, are so call­ed from their Resemblance to the Tusks of a Dog; those of the upper Jaw are by some, called the Eye-teeth, from the Communication of Nerves betwixt them and the Eyes; they are thick and round, terminating in a sharp Point, and like the Incissores have but one Root, but are remarkably strong, and of a greater Length than any of the rest: Their proper Use being to pierce and hold the [Page 3]Aliment steady when we bite it, as the front Teeth are very apt to be forced outwards by the Things we hold or break with them.

The large or double Teeth, are by Anatomists called Molares or Grinders, from their Use in grinding and making small our Aliment before it is swallowed. They are ten in each Jaw; their Extremi­ties are broad and uneven, and because the Pressure upon them is perpendicular, they are provided with two or three, and sometimes four Roots separated a little from one another, and inclining somewhat outwards, that in chewing our Aliment the Pressure may be less upon the Jaws, than if they run directly down­wards, and with only a single Root.

The first Teeth, according to Hip­pocrates, are engendered in Time of Preg­nancy; this Urbain Hemard confesses he never could discover; he says, indeed, that having opened the Jaws of some Children three or four Days old, and others immediately at their Birth, he has found the Incissores, the Canini, and some of the Molares on each Side the Jaw in part ossified, and in part muci­laginous, [Page 4]of a middling Size, and sur­rounded with their little Alveoli.

However this may be, it is certain they do not appear, until some Time af­ter the Formation of the other Bones, notwithstanding the Matter of which they are formed, is at the same Time in the Womb; and therefore Galen ^* writes, that he who would understand the Works of Nature, and observe her Oeconomy in the Composition of the human Body, ought not implicitly to rely on what he finds in Books, but rather what he sees with his Eyes.

The Teeth are formed within the Ca­vities of the Jaws, which are lined with a thin Membrane, supplied with several Vessels, conveying a thick, viscous, trans­parent Liquor, which as it increases, hardens into the Form of Teeth.

This transparent Humour appears first in Form of a Mucus, afterwards a thin cortical Lamella, and some ossious Strata are perceived, with a large Cavity in the Middle, then gradually both the vitrious and bony Parts increase by the hardening of the Mucus, and Opposition of new Matter.

The ossious Strata are no other than a Separation of this fluid Matter, made by the same Membrane which covers the whole Cavity of the Jaw; and this Division forms two Lays, one below the other, the uppermost of which forms the Teeth which come out first; but about the seventh Year, they are thrust out by the Teeth made at the undermost Lay, which then begin to sprout; if these latter be lost, they seldom if ever grow again; some are indeed observed to shed their Teeth twice, which must be owing to their having three Lays of this Matter.

The Teeth receive Nerves and Vessels at the Orifices of their Roots; it is these Nerves which are afflicted in the Tooth­ach, and which are frequently shewn to the common People, by the ignorant among Tooth-drawers, for Worms; which they pretend would have eaten the whole Tooth in a short time, &c. Part of these Nerves being always torn away with the Tooth drawn, it requires great Care to keep the Mouth warm un­till the Gum becomes closed, and the Nerve defended from the Air.

This Orifice commonly closes about [Page 6]the Age of thirty-five, which is the Reason why old People are not so sub­ject to the Tooth-ach as young.

The first Teeth perceived, are the Incissores of the upper Jaw, then those of the lower, these being the thinnest and sharpest. After them appear the Ca­nini, and last of all the Molares.

The general Opinion is, that the Teeth are connected to thin Alveoli, or Sockets, by that kind of Suture called Gomphosis, that is, like a Nail drove in­to a Piece of Wood; but this is proved to be false by the following Experiment. If the Jaws be macerated in Water, for some Time, all the Teeth will drop out, which they would not do, if they were of the same Size of their Alveoli. From hence it appears, that it is by a Liga­ment, or by the Articulation called Syn­chondrosis.

That the Teeth are joined to their Sockets by some means like this is evi­dent, for when a Tooth hath been drawn and replaced immediately, it hath taken root, and been as firm as ever, which could not have happened, had [Page 7]not the Cavity been lined with a Mem­brane, which contained it.

After all that can be said concerning the Formation of the Teeth, nothing will so much illustrate the Tooth in Em­brio, as that called the Sweet-Tooth in a Calf, by which the Reader may form an Idea, not only of the Colour and Sub­stance of the Mucus, or Juice usually suck'd out, but of the Lamella or Shell­work itself.

The Use of the Teeth.The Teeth are so necessary to Man, that I conceive the greatest Diffi­culty of his subsisting in the younger part of his Life without them: Certain it is, that the strongest Constitution, would not be able to digest or separate a Quantity of Chyle sufficient for the Nourishment of the Body for any con­siderable Time, were the Aliment to be swallowed whole and unprepared; for it is well known how much the chewing our Aliment contributes to the easy and expeditious Digestion of it, and consequently to our Health. There are indeed many old People and others, who for want of Teeth are confined to a liquid Diet, such as Broths, Jellies, [Page 8]Milk, &c. for the Sake of an easy Di­gestion. To those in old Age, I think such a Diet not only proper, but very necessary; for Nature, by the Decay of Strength, the Loss of Teeth, and the gradual Diminution of our Senses, seems to have appointed this Time, as a Re­turn to our primary Innocence; that we may make our Exit in some Measure conformable with our Birth: And at this Time the Weakness of the Body generally renders it incapable of per­forming the natural Functions, and con­sequently of digesting such Meats, as before it had been accustomed to.

Upon a transient Reflection we might imagine it injudicious of Nature to leave Age thus helpless and unable to support itself, but upon a more careful Survey, we shall find in this, as well as in all her Works, that her Oeconomy is ab­solutely just, and that every minute Va­riation of Form, &c. is important: Whenever we think otherwise, we ought always to suspect our Capacities of being too gross to comprehend the Sublimity of her Wisdom.

The Loss of Teeth to an old Man, is in Fact but trifling, for the Human Body is so providentially disposed, that [Page 9]as the natural Powers begin to lessen i [...] their Force and Action, the less is required in the Constitution to maintain that Force and Action; and that a less Quantity of Chyle will better nourish and support Health in old Age, is a Truth every Anatomist is able to as­sert, for it is frequently seen in the Dis­sections of the older Subjects, that ma­ny of the small Vessels, and sometimes Part of the larger also have been collaps­ed and grown up, so as to reject the Fluid that used to circulate through them: And this is one Reason why old People are most subject to paralytic Disorders.

If the Number of Vessels be diminish­ed, as in this Case they certainly are, then is there the less required to fill them, and the Body is more easily sup­ported than before, and from hence it is, that we can so well dispense with the Loss of Teeth when old: But when this Loss happens earlier in Life, I think it may justly be deemed very great, since it is capable of depriving us of our Health, our Beauty, our Voice: Nor does the Inconveniency stop here, it proves of Detriment even to Society.

If such extensive Effects appear strange, let the Husbandman, so neces­sary to Society, be viewed in this State, and we shall soon be convinced, that the Want of Teeth is of greater Mo­ment than is commonly imagined: It would oblige him to live on a liquid Diet, by no means proper in his labo­rious Employ; for we are not the least capable to support the continual Action of the Body (and which in his Business is almost violent) without proper Food; I mean such as will remain some Time in the Stomach and yield its Nourishment gradually to the lacteal Vessels, which receive and carry it to the Blood.

This is always performed by such Food either animal or vegetable. And if the Diet of the Labourer consisted only of those Juices exclusive of the Substances, tho' these latter afford no Part of Nou­rishment, yet the Body would waste, the Fibres would become lax, the In­testines would lose their Tone, and a general Languor would seize the whole Body; and if not relieved by a Change of Diet, a Diarrhea, Dropsy, &c. would be the certain Introduction to Death.

The Consequence of a liquid Diet is no where more obvious, than in the old sedentary Man, in whom, by an inac­tive Life, the Viscera are rendered weak, and the Vigour of the digesting Powers in a great Measure lost for want of Use. He is indeed better able to support Life than the working Man, as he is void of the Fatigue; but with what great Difficulty it is effected, may be seen in his pale lan­guid Countenance, his emaciated Bo­dy, and the Defect of Vigour in his Motion.

I cannot help reflecting in this Place on the general Error of Men fond of Study, whose contemplative Geniuses in­clining them to a Life, in other Respects full of Indolence and Neglect, they sup­pose it agreeable to their Way of Life, to eat their Aliment liquid, and pre­pared for an expeditious Passage in the Primae Viae; in this Method they seem to imitate Birds and other Animals, which, in the room of Teeth, Nature has supplied with two Stomachs. Where in the first the Corn is only swelled and softened by the Liquor of its Glands, but broken and disolved in the second; which is composed of very strong Mus­cles. [Page 12]This Oeconomy is wonderful in the Animal, but by no means applicable to the rational Creature. Although the Pot and other Implements used in Cook­ery, where the Aliment receives some Degrees of Digestion, may bear some Analogy to the first Stomach in the Ani­mal, yet the Operation is different, it is by the Succus Gastricus, a Liquor sepa­rated by the Glands of the Stomach, that the Corn is made soft and fitted, to the Action of the second Stomach, where it is received together with the Juices of the first. But in boiling, the most nutrimental Parts are lost, the more volatile and spiritous evaporate, while the gross fatty Parts are blended with the Water.

Therefore whoever takes down the Substance loads the Stomach to very little Purpose, and whoever drinks the Broth will relax his Stomach, and rob it of the Vigour required to perform its Office. But nothing will so much con­vince us of the Impropriety of such a Regimen, as a Knowledge of Digestion, and the Manner of its being performed; which for the Sake of such Readers as are unacquainted with these Subjects [Page 13]we will take a cursory View of in its first Stages.

The principal Agents employed in this Action, are the Teeth, the Saliva, the Succus Gastricus, and the Liquors we drink. The Aliment being broke by the Teeth, and mixed with the Saliva in the Mouth, descends into the Stomach, where it imbibes the Juices of the Glands, and the Liquors drank, whose chief Property is to soften the Aliments, as they are Fluids which easily enter the Pores of moist Bodies, and, swelling them, break their most intimate Cohesions; and this is augmented by the Impetus which the Heat of the Stomach gives to the Particles of the Fluids; and likewise by rarefying the Air contained in the Pores of our Food, which bursts its Parts asunder.

The Aliments thus prepared, their Parts soon separate from one another, and di­solve into a Fluid with the Liquor of the Stomach, by the continual Motion of its Sides, whose absolute Power is demon­strated (by Pitcairn) to be equal to the Pressure of 117088 Pound-weight: To which if we add the absolute Force of the Diaphragm, and Muscles of the Ab­domen, which likewise conduce to Di­gestion, [Page 14]the Sum will amount to 250734 Pound-weight.

From whence this Force? Or for what Purpose hath Nature (who yet hath ne­ver been detected in an Error) employed all this Mechanism, if useless? There can be no Occasion to spare it the Trouble of its Office, and the only Excuse Men find for so doing, is because 'tis already weakened by some Cause, and incapable of acting. But to such I would observe, that 'tis not by these Means to be brought to its natural Tone. And the studious Man, whose Life is generally inactive, will find it more to his Advantage, and agreeable to the Constitution of his Nerves, on whose Sensation he de­pends for his Ideas, to live more upon Food containing the natural Juices, of which Kind especially are all roasted Meats.

I could not conveniently treat on this Subject without mentioning Digestion, since the Teeth are the first and necessary Organs of it. Wherever we observe these Instruments wanting in Animals, &c. we shall always find them furnished with [Page 15]two Stomachs; and where they have Teeth besides, they are only used as Weapons of Defence, which we see in the Viper, and some Kinds of Fish, who swallow their Prey whole.

From hence we may conclude, that the Teeth, besides their Importance for the Preservation of our Health, are like­wise necessary for the Agreement of the Voice, the Pronunciation and Articula­tion of our Words, and the Ornament of the Face.

Precau­tions for preserv­ing the Teeth.Tho' the Production of the Teeth is entirely the Work of Nature, the Preser­vation of them depends greatly upon our­selves.

Men are naturally attentive to their Health, but by a Neglect of this Kind they are too often rendered incapable of attaining it: For, as I have before shewn, the Health depending on the Digestion of the Aliments, which ought first to be pounded as it were, and broke for the easier Admission of the Juices of the Stomach: And this being the Office of the Teeth, it intimately concerns us [Page 16]to keep them in such Order as will enable them to perform it.

The Means to preserve them, consists then principally in the Choice of a good Regimen, and avoiding the Use of such Things as are hurtful to their external Parts.

The first you see will not only preserve the Teeth, but at the same Time the Health also, as it consists in the Choice of such Aliment as will yield a good Nourishment. But the Generality of People are so prone to Intemperance, and eat with so little Attention, or rather so precipitately, that too much cannot be said of its ill Effects. Nothing is capable of producing greater Disorders, than an imperfect Mastication; for if the Ali­ment be not well broken by the Teeth, 'tis certain the Dissolution in the Stomach will be long, laborious, and imperfect. And the sweet balsamic Blood, will be changed into a thick, acrid, and vis­cous State. And this Alteration cannot fail of producing a bad Effect in the Teeth, not only as it circulates thro' them, but by the Vapours which arise from the Stomach and Breath, and [Page 17]lodge upon them as they pass thro' the Mouth.

The too great Use of Vegetables, as also the Flesh of Pork, salted Meats, Salt-fish, Cheese, &c. must be preju­dicial, as they all produce a bad Chyle.

All Kinds of Sweet-meats and Sugars contribute very much to the Destruction of the Teeth; because their gluey Juice is insinuated into the Gums, and sticks to the Teeth; besides, Sugars are of an acid, penetrant, and corrosive Nature, and by a Chymical Analysis we see that the Effects will be sooner or later per­nicious. 'Tis also remarkable that those People who make great Use of this Poi­son, are more subject to the Tooth-ach, and lose their Teeth sooner than others.

Those who love Sugar, and use it frequently, are seldom remarkable for handsome Teeth, and very rarely good ones. This is particularly exemplified in Holland, the Inhabitants whereof, especially the Women, are great Tea-drinkers, and in their Manner some­what particular, for instead of sweetning each Dish with Loaf-Sugar as in Eng­land, [Page 18]they hold a Piece of Sugar-Candy in their Mouths, which frequently serves six or eight Dishes before 'tis di­solved, which inevitably produces those Effects to which they are so subject, viz. the Loss and Ruin of their Teeth: For 'tis rare to find a Dutch Woman of thirty Years of Age with a good Set of Teeth: For this Reason, after eating Sugar, or any Thing that contains much Sugar in its Composition, it will be ne­cessary to rince the Mouth with warm Water, to dissolve and wash away those Parts which would stick to the Gums and Teeth.

It would be absurd from hence to conclude it absolutely necessary to de­prive ourselves of these Things, but to regulate their Use; and not to make a Habit of that which Experience shews to be prejudicial most certainly is worth our Consideration.

Of no less Importance is Mode­ration in Drinking, since our Health is equally dependant on Sobriety; the ma­ny Constitutions we see ruined by Ex­cess of this Kind, is a stronger Argument [Page 19]to deter us than any Thing that can be further said on this Head.

'Tis as necessary likewise to avoid chewing or breaking any hard Bodies, as Nuts, Cherry-stones, &c. biting off the Ends of Thread or Silk, lifting up great Weights, picking them with In­struments of Gold, Silver, or any other Metal, by which they may be either loosened or lost, and other such idle and pernicious Practices.

Excessive smoaking Tobacco is also very injurious (especially if Care be not taken to cover the End of the Pipe with Wax); which will by Degrees wear off their vitrious or glossy Substance, and subject them to the Danger of becoming rotten, and perfectly useless: It besides gives them a black and filthy Appear­ance, and causes an unnatural Heat in the Mouth, which by the immediate Ad­mission of cold Air, may arrest a Hu­mour in the Gums or neighbouring Glands, and be the Foundation of great Pain and Trouble.

I would not have the Reader imagine me ignorant of the Qualities of Tobac­co: [Page 20]I am sufficiently sensible of its Ser­vice in preserving the Teeth, by evacu­ating the superfluous Humours: But like any other Specific, it may, if im­properly made use of, answer a very different Effect. I would therefore by all Means advise washing the Mouth with warm Water, and not exposing it too soon after smoaking to the Impressi­ons of a cold Air, &c.

The Effects which have been observed to follow smoaking, are the very same when we eat our Victuals too hot, and im­mediately, or in a little Time after, eat something cold. Many People drink, in the same Instant, a Liquor almost boiling hot, and some other as cold as Ice, without recollecting that the Diver­sity of Heat and Cold is able to arrest and fix the Humours which nourish the Teeth, which stagnating, will ferment and break the Membrane that covers the Roots of the Teeth, and render them carious.

This Effect is produced by the Dila­tation of the Parts and the Rarefaction of the Liquids that pass thro' the Vessels, occasioned by Heat. As Cold on the [Page 21]contrary will contract and shut up the Parts, abate the Motion of Circulation and render the Juices contained in [...]he Vessels, thick and incapable of passing.

The great Preservation of our Teeth, in short chiefly depends on our Regimen of Living; the Constitution, and the Teeth, have so equal a Dependance on each other, that the Destruction of the latter proves the Ruin of the former, almost as certain, as that a bad Blood can never supply the Teeth with good Nourishment.

General Causes of the Disor­ders of the Teeth.The Causes that produce the Diseases of the Teeth, are two in general: The one internal, the other external. The internal Cause is owing to the Quantity or Quality of the Lymph, which by its corrosive Parts is capable of destroying the most compact Parts of the human Body, such as are the Teeth, by break­ing the external Substance, or glossy Covering of the Bones of which they are composed.

The Lymph we find of this Character in the Scurvy, in the King's Evil, and in the Pox.

When the nutritious Juice is too abundant, or distributed in too great Quantity into the Teeth, that it stagnates between their Alveoli and their Roots, its Effects are very dangerous, like as when the Blood is inflamed, it may form phlegmonic Abscesses in the Ca­vity of the Teeth, or in the neigh­bouring Parts: It may also occasion the most exquisite Pains, incurable but by the Loss of the Tooth.

The Regi­men of Li­ving.Too much Sleep, too much watching, a too sedentary Life, or a too laborious one, contribute not a little to the Preser­vation or to the Ruin of the Teeth.

The good Quality of the Milk which the Child receives from its Nurse is of great Importance to the Formation of the Teeth, in the Time of too thing; as it serves to prevent or diminish the many Accidents that happen to Children, when the Teeth are disposed to pierce the Membrane of the Gum, that covers their Extremities and opposes their Issue.

All violent Passions are capable of al­tering Digestion, of increasing or thick­ning the Mass of Blood, of causing Ob­structions, and of stopping the Secre­tions and Excretions which mould ope­rate daily for the Preservation of our Health. The Passions, I say, may, when they alter the Mass of Blood to a certain Degree, be ranged with the internal Causes that produce the Diseases of the Teeth.

All Persons in a pituitous or pletho­rick Habit of Body, in whom the Lymph is very abundant, are generally subject to suffer not only Pain in the Teeth, but even their Loss.

The Generality of Women with Child are likewise subject to this Complaint: The menstrual Discharge being stopped, the Mass of Blood must rest charged with a Superfluity; 'tis therefore from the Quantity that is deposited on the Teeth or on the Gums, that Women suffer this Uneasiness sooner when with Child than at other Times; and we see that they are often afflicted for the same [Page 24]Reason, when their monthly Oeconomy is over.

The Ja [...]dice occasions so much Dis­order in the Blood, that the Teeth sometimes perish by an Abscess on those Parts.

The external Causes are not less in Number, nor are they less dangerous in their Effects. The thick Vapours that arise from the Stomach and Lungs ad­here to the Mouth much in the same Manner that Soot adheres to the Sides of the Chimney, forming a tenacious vis­cous Substance that covers the Teeth like Paste. This tenacious Matter is very hurtful to the Teeth. When certain l [...]tle Portions of our Aliment adhere to the Teeth, or stick betwixt their Inter­stices or the Gums, it is capable of pro­ducing the same Effect, especially if we neglect rincing our Mouths after.

The Injuries of the Weather are the Causes of Rheums and Catarrhes, from which the Teeth, the Alveoli, and the Gums, are too often very great Suffer­ers

The too great Use of dentrifick Pow­ders serves chiefly to Destruction, as they use or wear off the Part of the most Im­portance to their Preservation, viz. their Enamel or vitrious Substance.

But the Neglect in not keeping them clean, is the most general Cause of all the Disorders that happen to the Teeth.

Mercury is a great Enemy to the Teeth, not only by itself but by the bad Effects that it may produce in the Body, by the corrosive Qualities that most of the Preparations of Mercury are charged with, or by the Alliance that it contracts with different Principles in our Bodies, when it stays too long, or when 'tis not properly evacuated.

'Tis very evident that Mercury, by its ill Effects, swells the Gums and renders them sore; this it does also to the Mem­branes that cover the Roots of the Teeth, either internally or externally; it de­sects, if I may be allowed the Expressi­on, the very Roots, and throws them out of their Sockets, or otherwise, it [Page 26]destroys them by the Caries that it occa­sions. These melancholy Effects we see but too often, especially where Mercu­ry hath been employed by Persons little versed in its Use. The most experien­ced Practitioners in the Venereal Disease use it with the utmost Circumspection, and with great Industry guard against its Poison. The Gilders and those who cover Looking-Glasses, Plumbers, and such as work in Mines, &c. expe­rience the bad and fatal Impressions that Mercury makes upon them, and particularly upon their Teeth.

'Tis by the Effects produced from these Causes, that the Teeth are attended with such Diversity of Diseases, almost al­ways accompanied with Pain, more or less violent.

Authors have reckoned the Number of Diseases of the Teeth to amount to upwards of an hundred, but I find on­ly nineteen necessary to comprehend all that may be useful to know, and these may be divided into three Classes: In the first are those produced by external Causes; in the second are contained the Disorders of the Alveoli and Gums; [Page 27]and in the third are the Diseases acci­dental or symptomatic.

Of the Tartar or Turf.The first Disease from external Causes worth our Notice is, the Tartar or Turf, concerning which Authors speak of many different Sorts, as the yellow, the grey, the black, and the petrified, and distinguish them also by their Degrees of Consistence; but as this last is owing only to the Duration, and the Difference of Colour not mate­rial, I shall speak only of the most com­mon Sort, which is of a dark yellow, tending rather to a brown Colour.

The Tartar is a Matter accumulated on the Surface of the Teeth, near the Gums, which in Process of Time will form a strong Crust, of a considerable Bigness, common to those who are ne­gligent in keeping their Teeth clean. This foreign Matter as it increases in Quan­tity, inevitably consumes the Gums, and by that Means occasions a Rottenness of the Teeth.

For the better understanding the Na­ture of this Tartar, with the Causes [Page 28]that produce it, and the Manner of its insensible Formation, the two following Principles may be of Service.

First the Foundation of this Matter and its Increase may bear some Analo­gy to the Stones formed in the Kidneys, Bladder, &c. which owe their Origin very often to a Retention of some Mat­ter, capable of Attraction and Cohesion: The small Portions of our Aliment that adhere to the upper Part of the Teeth, or betwixt their Interstices, being soft­ened by the Saliva, become of a gluey Consistence, which soon grows dry, by the Assistance of more Air, passing in Inspiration and Expiration.

Secondly, when the Saliva becomes viscous, from a Deprivation of the Lymph, and is loaded with saline Par­ticles, 'tis very probable that it may be lodged upon the Body of the Teeth, and by Degrees form the Mass we are speaking off. That this Matter may be so caused, I am the more ready to be­lieve from the Observation ^* of a strong [Page 29]Concretion being found upon the Roots of the Tongue, formed by a viscous Lymph, resembling the Saliva in Thirst. 'Tis difficult to assign any other Cause than that the Saliva may become tar­tarous and form this Substance.

The first Lay or Bed of Tartar be­ing once formed, 'tis easy to conceive it augmented by the Addition of fresh Matter, and to increase to an extraordi­nary Size.

From the Nature of this Disease we may readily infer, that the Cure, or Means to prevent it, will consist in keep­ing such a Regimen as will preserve the Purity of the Blood in its natural State; and by being careful to wash the Mouth often, (which is absolutely ne­cessary to prevent a stinking Breath oc­casioned as well by this Neglect as the Disorder here mentioned) we may main­tain the Use and Beauty of our Teeth, for many Years.

The Jaundice of the Teeth is men­tioned as another Disease; but I think with Impropriety, it being nothing more than a tarnished Substance, or Viscosity [Page 30]sticking to the Teeth, like Dust, or the Humidity that covers the Surface of a Looking-glass when 'tis not kept clean; and to me it seems to be nothing more than a Bed or Lay of Matter, form­ing the Tartar.

Sensibility and Agace­ment.The Sensibility and Agacement of the Teeth, are Disorders produced from external Causes.

The Writers on this Subject have been of opposite Opinions, some main­taining the Teeth to be insensible Bodies, others on the contrary making them ex­tremely capable of Sensation. 'Tis true that simply as so many Bones, we may consider them as insensible; but as co­vered and lined with Membranes, and furnished with Vessels and Nerves, we cannot deny them the Quality of Sensa­tion, any more than other Parts of the Body.

By the Sensibility of the Teeth is to be understood that fixed and permanent Pain, that we generally express by say­ing we have the Tooth-ach.

By the Agacement of the Teeth is meant that acute Pain we express by saying they are set on Edge, caused by certain Sounds, such as the touching of Stuffs, the slipping of a Knife or Fork upon a China-Plate, or the filing a Piece of Iron, &c. &c.

The Pains of the Teeth are of diffe­rent kinds: But the most general are those called pungent or pricking, com­ing by Intervals; the other distensive or continual, such as accompany a Caries, in which the Air by drying or crisping the Fibres, Nerves and Coats of the little Vessels, render them bony, and contract their Diameters too small to re­ceive any Fluid thro' them, by which Means the Efforts of the Humours, to distend their Orifices, cause that Pain we call distensive.

If on the contrary the little Vessels should be ruptured, the Liquor extrava­sated would soon change its Nature, and fermenting would irritate the Mem­branes, and produce the Pain called pungent.

The Agacement we find to be a dif­ferent Kind of Sensation, owing, ac­cording to the general Opinion, to an acid Juice, insinuated betwixt the Fibres of the Membranes, that covers the Roots of the Teeth; and when the Teeth are compressed against this Mem­brane, that Disposition occasions the Action of the Juices against the Fibres of the Membrane.

I believe that the Juices of certain Fruits, such as Cherries, Gooseberries, Apples, &c. may be insinuated betwixt the Interstices of the Fibres that com­pose the Membranes, and distending them, intercept the Course of the Li­quors in some Vessels, and by stretch­ing the Nerves, produce a Sensation more or less troublesome to bear: But 'tis very different from that seated in the Body of the Tooth.

What makes me consider that the Agacement is fixed only to the Body or Surface of the Teeth is, if they are wiped with a Piece of warm Linen, it will immediately diminish their Uneasi­ness. And in Opposition to the Opini­on of an Acid being the Cause, the [Page 33]following Experiment will serve to con­vince: If the Herb Sorrel be chewed between the Teeth, the Agacement will suddenly cease; if this Disease be oc­casioned by an Acid, is it not strange that it should admit of this Remedy? Sorrel which is itself an Acid, must ra­ther increase than abate the Disorder! 'Tis possible that some Parts of the Juice may be subtle enough to penetrate the Fibres that terminate it: But how Sor­rel acts in remedying this Evil, I con­fess, I am not able to conceive. We may observe that the Air taken in Re­spiration when the Mouth is half open, will produce the same Effect: And I cannot believe that Air in passing, pres­ses so forcibly as to make that Compres­sion against the Membranes at the Roots of the Teeth, which they assign to be the Cause. 'Tis more natural to suppose that the subtle Particles of the Air en­tering the Pores of the Enamel, and the Resistance made to the grosser Parts, may occasion a Tremor in the Tooth, and a Sensation not unlike the Agace­ment.

The Caries or Rottenness is a Disease produced likewise from external Causes. Rottenness.

The Teeth are more subject to this Disease, than all the other Bones in the Body, both by their Structure and Situ­ation.

This Disease is occasioned by a Hu­mour insinuated between the boney Fi­bres of the Teeth, which generally meets with Obstructions in the most sub­stantial Part of the Tooth, and by the particular Impulse, that every Particle communicates to the Cells of the Tooth, by Degrees, breaks off little Parcels, and in Time, makes that dark Cavity in the Tooth which we call hollow.

The Teeth are more subject to Rot­tenness than the other Bones, because their Periosteum is more pressed; which renders them subject to Obstructions, &c. The Molares are more subject to this Disease than the Incissores or Cani­ni; and the Incissores and Canini of the upper Jaw, more than those of the lower Jaw, because by their Situation they are more exposed to Heat and Cold, in eating or drinking, in Inspiration and Expiration.

It often happens, that after a Tooth is attack'd with a Caries, the opposite Tooth, on the other Side of the same Jaw, is affected also. Nor does it appear that this Effect depends only upon Haz­ard: For 'tis remarkable, that in the opposite Tooth the Caries will not only much resemble the other, but sometimes be exactly uniform to it.

The Vulgar, as well as certain Au­thors, are of opinion, that all Pains of the Teeth are caused by a Worm, that gnaws and eats the Membranes and Nerves of the Teeth. This Notion is founded upon pretended Experiments on these Infects, which (as they report) by smoaking Hembane, will fall from the Teeth, &c. And some of the Doctors of Montpellier have been very prolix in their Accounts of the Genera­tion of these Worms; besides the Dis­coveries with their Glasses: But who­ever will be at the Pains to make some Trials with the Microscope, may prove the Absurdity of this Notion.

The Time in which the Caries ra­vages most of the Teeth, is between the Age of 25 and 50 Years.

I have omitted the many Divisions that may be seen in some Books upon this Subject; both on Account of their Perplexity and Non-use. For the Ca­ries, of what Kind or Cause soever, pro­duces its Effects, more or less consider­able, according to the Parts of the Tooth they attack. And the Operations practised on these Occasions are more or less difficult, according to the Situation of the Tooth; or according as the Ca­ries is more or less penetrating in the Body, or the Roots of the Teeth.

Whenever the Caries is situated with­out the Gums, either on the Sides, or Extremity of the Tooth, the Cure will consist in separating the rotten Part from the sound, by Exfoliation, with the File, the Rugine, Cautery, &c. And by fill­ing the Cavity with Wax (which must be often renewed) it will defend the boney and nervous Parts from the Air, or the Impression of any other Bodies; likewise hinder any Bits of our Aliment [Page 37]from lodging in the Cavity, which are so apt to putrify and cause a stinking Breath.

Altho' the Teeth, Fractures. in their natural Situation, are harder and more compact than the other Bones in the Body, and more remarkably so in the human Specie than Brutes, we find them by Experience extremely subject to break; especially when the least Defect happens in them.

Their Fractures, are simple, compound, or Fissure.

The Simple happens often by Falls and Blows, particularly by the Attempts to draw them before they are loose: The Compound is when, their Roots are strongly attached to their Alveoli, and a Piece of the Jaw comes away with Part of the Tooth: A Fissure is a Fracture lengthways, without any seeming Alte­ration in the Form of the Tooth.

When once the Parts of the other Bones are divided, they never can be again united; for the Vessels distributed in them are not so disposed as to furnish a Juice sufficient, or that is capable of a Glutination; because their proper Sub­stance [Page 38]is too compact to give them Pas­sage; or their Motion, the Air, and Bodies that they touch, are Obstacles that oppose the Re-union of the divided Parts.

But tho' the Re-union of the Fracture be impracticable, the Scales, or Splinters, that remain, may be extracted, or their Angles and sharp Points smoothed and polished.

All the Luxations the Bones suffer in their Articulations, Luxations. are either complete, or incomplete. When a Tooth is loosened, it is a Luxation incomplete.

If after having been naturally well situated, they lean either in, or out of the Mouth, of one Side, or the other, they are so many Luxations.

When a Tooth turns in the Alveoli, so that the lateral Parts of the Tooth incline, either outwards or inwards, 'tis a Luxation complete.

When a Tooth seems to be longer, and exceed the others, that the Neck and Part of the Roots appear above the Edge of the Gums, occasioned by some [Page 39]Matter contained in the Alveoli, 'tis a Semi-luxation.

The large Teeth are most frequently luxated inwards. The Incissores, on the contrary, generally luxate outwards: Altho' both these Dislocations are bad, and incommode the Equality of Masti­cation, yet the Luxation inwards is the worst, because it fatigues and hurts the Tongue; which Uneasiness is more than the Inconvenience that is caused by the Teeth against the Lips, or Cheeks, when they fall outwards. The least inconve­nient Luxation is, when the Tooth is only turned in the Cavity of the Alveoli.

When the Teeth are luxated, in such a manner as to exceed the others by their Extremities, which we call a Luxa­tion, or Dislocation of the Bottom to the Top of the lower Jaw, or of the Top to the Bottom of the upper Jaw, the Masti­cation is very difficult.

In all these Cases, the Remedy is, to return them, each, in their proper Places, by which means they will often become quite fast; to guard against the Causes of Luxations, and so fortify the Gums.

Diseases within the Alveoli and Gums.The Diseases that happen to the Parts of the Teeth contained within the Al­veoli and Gums, are,

1. Caries of the Neck and Roots of the Teeth.

2. Inflammation of the Membranes, that line the internal Cavities of the Roots of the Teeth, their Periosteum, &c. occasion'd by Cold.

3. Abscesses in the Cavities of the Teeth and Gums: The Consequence of an Inflammation.

4. Atrophy, or Dryness of the Al­veoli and Membranes of the Gums; which is sufficient to make the Teeth fall out, without any Caries, and even without Pain.

The accidental, or symptomatic Dis­eases of the Teeth, are,

1. Caries of the Alveoli, caused by the Teeth.

2. Exostosis of the Alveoli, occasioned by the Teeth also.

3. Inflammation of the Periosteum, lining the Cavities of the Alveoli.

4. Fracture of the Alveoli, caused by the Extraction of the Teeth, &c.

5. Hemorrhage, sometimes violent, occasion'd by the Extraction of the Teeth also. Sometimes this Hemorrhage proceeds from, the Gums being tore in the Operation of drawing.

6. Abscesses in the Gums, Cheeks, and Palate, caused by the Teeth.

7. Fistulas occasion'd by long Conti­nuance of those Abscesses.

8. Miscarriages have been the Conse­quence of violent Pains in the Teeth: And,

9. Nausea, Vomiting, Diarrheas and Fevers, and to Infants, even Death itself.