Popular Technology Volume I Part 21

5. At the age just mentioned, the infant teeth begin to give way to those which lie deeper in the sockets, and which are designed to supersede the former. As the new teeth advance, the roots of the first are absorbed; and, after having been thus deprived of their support, they are easily removed; sometimes, by a slight pressure of the tongue.

6. In a majority of cases, the whole process is carried on by nature with the utmost regularity; but, as she is not uniformly successful in this operation, there is no other period at which the teeth of children require so much attention and care. Sometimes the second set rise in the socket without causing the absorption of the roots of the first. In such cases, the former approach in an improper direction; and, unless the latter are removed in season, deformity will be the consequence.

7. When, however, these precautions have been neglected, and the teeth stand in an irregular manner, they can sometimes be reduced to symmetry by the dentist, without occasioning much pain. When the front teeth are too much crowded by reason of the restricted dimensions of the jaw, the small teeth, situated next behind the eye, or canine teeth, are extracted, one on each side, to give room to the rest.

8. From the ages of six to fifteen years, the teeth of children should be examined, at least once in six months, by a dentist, who, if skilful, can seldom fail of rendering these ornaments of the human countenance regular, healthy, and beautiful. It is customary in England and France, for the proprietors of seminaries of learning to employ a dentist to visit their establishments regularly, for the purpose of performing such operations, and of administering such remedies, as their pupils may require.

9. The teeth are composed of very hard bone and enamel. The latter is a substance exceeding in density any other in the body. It covers the crown of the teeth, and is thickest in those parts which are most exposed to forcible contact in mastication; but, in no place, is it more than the twelfth of an inch in thickness.

10. The most common disease of the teeth is _caries_, or decay, and almost every part of them is liable to be affected by it, but especially the sides of those in front, and the crowns of those on other parts of the jaws.

11. The disease begins its attack either on the enamel or on the bony portion, and gradually extends itself over the tooth, until it reaches the nerves which supply its natural cavity. These having become exposed to the sudden changes of temperature, and to the contact of extraneous substances in mastication, pain and inflammation are produced, and the extraction of the tooth very commonly becomes the only means of relief.

12. All persons are more or less subject to this disease, but some much more than others; and caries of a peculiar character has been so often traced through whole families, from one generation to another, that it is considered hereditary, as much as any other disease to which the system is liable. In many cases, caries seems to be the effect of some serious disease which affected the const.i.tution, while the teeth were in the early stages of formation.

13. Although the teeth of some individuals possess but little durability, and, when caries attacks them, go on rapidly to decay, in spite of all the aid which science and skill can afford, yet, there are comparatively but few instances in which seasonable and judicious treatment will not arrest the progress of the disease.

14. When the teeth are but slightly affected with caries, especially on the sides, a cure may be accomplished by the removal of the decayed portion. This is effected, by the most approved dentists, chiefly with small cutting instruments. Formerly, the file and the saw were employed for this purpose; and, by their indiscriminate and injudicious use, many teeth were ruined, and the art of dentistry itself brought into disrepute.

15. Notwithstanding the injuries which have been inflicted by the improper application of the saw and file, in some instances they are indispensable; and, in the hands of the scientific operator, they need not be feared. They are especially useful in preparing the way for the employment of other instruments; for, in some cases, the affected part can with difficulty be reached by any other means. But filing the teeth for the purpose of improving their appearance, or for rendering the sides more accessible to the tooth-pick and brush, seems to be reprobated by the most intelligent part of the profession.

16. When the caries has penetrated far into the tooth, and, in its removal, a cavity of suitable form and dimensions can be produced, it is filled with some substance, with the view of protecting the bone from the action of extraneous agents. The dentist is careful to remove every particle of the decayed portion, and to render the cavity perfectly dry by repeated applications of lint or raw cotton, before he attempts to fill it.

17. Gold is the only substance which possesses sufficient solidity to withstand the ordinary friction of mastication, and which, at the same time, is capable of resisting the chemical action of the substances that come in contact with it; yet lead and tin are frequently employed; and many have been made to believe that they answer as good, if not a better purpose, than gold itself. The durability of these metals, however, can never be depended upon, and they ought not to be employed, where the tooth is capable of resisting the mechanical force required to fill it properly with gold.

18. The metal is prepared for the use of the dentist by the gold-beater, in the manner described in the article which treats upon the business of the latter. The leaves, however, are not beaten so thin as those designed for the common purposes of the arts. The portion to be applied is cut from the leaf, and, after having been twisted a little, is forced into the cavity. The metal is rendered perfectly solid by means of instruments adapted to the purpose.

19. This operation, properly performed under favorable circ.u.mstances, generally renders the tooth as serviceable, to the end of life, as if it had never been diseased. The hopes of the patient, however, are sometimes disappointed by the unskilfulness of the operator, or by the general unhealthiness of the mouth, arising from tartar, other decayed teeth, or want of care in keeping them free from the lodgment of particles of food.

20. It is a common practice to have teeth extracted, when they are affected with pain; but this operation is not always necessary. In many cases, the nerve can be paralyzed, and the tooth plugged. By these means, teeth which, under the ordinary treatment, would be prematurely sacrificed, are often retained, for years, in a serviceable state.

21. The next most destructive affection to which the teeth are liable, is the acc.u.mulation of _tartar_. This is an earthy substance, deposited from the saliva, and is more or less abundant in different individuals. This deposit is extremely troublesome, and generally does much injury to the mouth, even before those who suffer from it are aware of the mischief.

22. The tartar on the teeth of some individuals, is of a black or greenish color, and very hard; on those of others, brown or yellow, and not so firm. When it is first deposited, it is soft, and can be easily removed with a tooth-brush; but, if suffered to remain, it soon becomes indurated, and gradually increases in thickness about the neck of the teeth. The gums become irritated and inflamed. The sockets are next absorbed, and the teeth, being left without their natural support, either fall out, or become so loose, that they can be easily removed.

23. From this cause, old people lose their teeth, when, in many cases, they are perfectly sound; but comparatively very few are aware of the origin of this deprivation, or suppose that these valuable instruments can be retained in old age. The loss is attributed to the deleterious effects of calomel, or is imagined to be an evil inseparable from advanced age.

24. The affection of the gums, arising from causes just mentioned, is frequently called scurvy, and, like caries, produces fetor of the breath; but, when these two diseases are combined, as is frequently the case, they render it extremely offensive. Besides, the effluvia arising from these diseased parts give rise to many maladies which terminate fatally, if a remedy is not applied sufficiently early to save the patient.

25. The obvious remedy for diseases arising from tartar, is the removal of their cause. This is effected by the dentist, with small sharp cutting instruments of a suitable form. To prevent the tartar from acc.u.mulating again, and to restore the gums to a healthy state, nothing more is generally requisite than the daily use of a stiff, elastic brush, and the occasional application of some approved dentrifice or astringent wash. Sometimes it may be necessary to scarify the gums, or to apply leeches to them.

26. The operations of dentistry, mentioned in the preceding part of this article, are those which relate to the preservation of the teeth; and, if performed in a proper manner, and under favorable circ.u.mstances, they will, in most instances, prove effectual. But, as few persons resort to the dentist, until the near approach of deformity, or until they are impelled by pain to seek relief, a great proportion of dental operations consists in inserting artificial teeth, and in extracting those which are past recovery.

27. When a tooth has gone so far to decay, that it cannot be cured by _stopping_, it should not be suffered to remain in the mouth, lest it infect the rest. Front teeth, however, when the roots remain sound, and firmly based in the sockets, ought not to be extracted, as upon the latter artificial teeth can be placed with great advantage. In such cases, the removal of the crown only is necessary.

28. The instruments commonly employed in extracting teeth, are the key, or turnkey, the forceps, the hook, and the graver, or punch.

These are supposed to be sufficient to perform all the operations of this kind which occur in practice; and, although many attempts have been made to invent others which might answer a better purpose, yet those we have mentioned, in their improved state, are likely to continue in general use.

29. It seems to be a common opinion, that any one can pull teeth, who has a turnkey, and sufficient physical strength to use it; accordingly, blacksmiths, barbers, and medical students, are the chief operators in this line of dental surgery. The many fatal accidents which must inevitably be the consequence, such as breaking the tooth or jaw-bone, are considered matters of course. These, however, seldom happen with skilful dentists; and it is to be regretted, that the latter are not always employed, where unskilfulness may produce such serious consequences.

30. In the cut, at the head of this article, is represented a dentist, about to extract a tooth for a lady, who may be supposed to be in a state of alarm at the sight of the instruments; but he, having thrown his right hand, which holds them, behind him, shows the other containing nothing, with the view of allaying her fears. The manner in which teeth are extracted, needs no description, since it is an every-day operation in all parts of the world.

31. One of the chief sources of income to this profession, is the insertion of artificial teeth; for, although few are willing to expend much to prevent the loss of their teeth, many will incur great expense in supplying the deficiencies, after they have occurred. So perfectly and neatly is this operation performed, by some dentists, that it is difficult to distinguish between teeth which are natural, and those which are artificial.

32. The materials for artificial teeth were formerly found chiefly in the teeth and tusks of the hippopotamus, and in the teeth of some domestic animals; but, within a few years, a mineral composition, called porcelain, has come into great repute, since it is very beautiful, and is entirely proof against the most powerful acids.

33. Surgical operations upon the teeth were performed in ancient Greece and Rome, many of which were similar to those of the present day. The extraction of teeth must have been practised at a period of antiquity to which the records of medicine do not reach. The operation is recommended by Hippocrates, who describes many of the diseases to which the teeth are liable. He also mentions the practice of fixing the teeth by means of gold wire, and gives several formulas for making dentrifices.

34. Celsus, a Roman writer on medicine, who flourished about the beginning of the Christian era, seems to have been the first author who described the method of extracting teeth, and the first who notices the removal of tartar by means of cutting instruments, as well as filling carious teeth with lead and other substances, with the view of preventing further decay. Soon after this period, false teeth, of bone and ivory, were introduced. Actius, a writer of the fourth century, is the first who mentions the operation of filing the teeth.

35. The return of barbarism to Europe, nearly extinguished the knowledge of dentistry. As a branch of surgery, however, it was revived by the Arabian writer, Albucasis, in the tenth century; but, for many hundred years after this period, it received but little attention from men of science, the operations of surgery being confined chiefly to the barbers.

36. The first modern work on the diseases of the teeth was published at Lyons, in 1581. This was followed by many other publications on the same subject, in the succeeding century. In the year 1700, it began to be required in France, that all persons who intended to practise dentistry in that country, should undergo an examination, to test their qualifications. From this period is dated the establishment of the dental art as a distinct branch of medical practice.

[Ill.u.s.tration]

THE TEACHER.

1. Education, in antiquity, was entirely a matter of domestic concern.

In countries where priestly or royal despotism prevailed, schools for the benefit of the sons of the great, and for the priests, were established. Moses, the Jewish lawgiver, was educated in a priestly school in Egypt, and Cyrus, at a seminary belonging to the Persian court. In Palestine, the Scriptures were taught in the schools of the prophets; and, at later periods, in the synagogues, and in the schools of the Rabbis, reading, committing to memory the sacred books, and hearing explanations of their meaning, const.i.tuted the chief exercises.

2. In the Grecian cities, boys and girls were taught reading, writing, and arithmetic in private schools; and, after having completed the primary course, those who aspired to higher degrees of knowledge, resorted to the instructions of the philosophers and sophists. This system was commenced as early as 500 years before the advent of Christ.

3. Two hundred years after this period, the Romans began to have primary schools for boys, in the cities; and, from the time of Julius Caesar, who conferred on teachers the right of citizenship, they possessed the higher inst.i.tutions of the grammarians and the rhetoricians. In the former of these, were taught the Latin and Greek languages; and in the latter, young men of talent were prepared, by exercises in declamation, for speaking in public.

4. Children, among the Greeks and Romans, were accompanied to school by slaves, who, from the performance of this duty, were called _pedagogues_; but, after slaves and freedmen had made acquirements in literature and science, they were frequently employed as tutors; hence the term, at length, came to imply a teacher of children, and it is still used in reference to this employment, although we usually connect with it the idea of pedantry.

5. Until the time of Vespasian, who commenced his reign in the year 70 of the Christian era, the schools were sustained entirely by private enterprise. That emperor inst.i.tuted public professorships of grammar and rhetoric with fixed salaries, for the purpose of educating young men for the public service; and, in A.D. 150, Antoninus Pius founded imperial schools in the larger cities of the Roman empire. The most celebrated place for the cultivation of science, in the ancient world, was Athens; and, to this city, students from all parts of Europe resorted, even as late as the ninth century.

6. Christianity, by degrees, gave a new turn to education; and, in the East, it came gradually under the influence of the clergy. Schools were inst.i.tuted in the cities and villages for catechumens, and, in some places, those of a higher grade, for the education of clergymen.

Of the latter kind, that in Alexandria was the most flourishing, from the second to the fourth century.

7. From the fifth century, these higher inst.i.tutions began to decline, and others, called cathedral or episcopal schools, seem to have taken their place. In these, besides theology, were taught _the seven liberal arts_--grammar, logic, rhetoric, arithmetic, geometry, astronomy, and music; of which the three first were called the _trivium_, and the four last the _quadrivium_. The text-book employed was the Encyclopaedia of Marcia.n.u.s Capella, of Africa. This compendium was published at Rome, A.D. 470; and, although a meagre production, it maintained its reputation in the schools of Europe more than 1000 years.

8. The imperial schools established by Antoninus Pius, declined, and finally became extinct, in the confusion that followed the irruption of the barbarians; but their places were supplied by the parochial and cathedral schools just mentioned. These, however, were surpa.s.sed, in the sixth century, by the _conventual_ schools, which were originally designed to prepare persons for the monastic life, but which soon began to be resorted to by laymen.

9. These schools were connected with the convents belonging to the order of St. Benedict, and served as the chief glimmering lights during the darkest period between ancient and modern civilization, in Europe. They flourished in Ireland, England, France, and Germany, from the sixth to the eleventh century. The teachers of these seminaries were called _scholastici_, and from them the scholastic philosophy derived its origin and name.

10. In the year 789, Charlemagne, king of the Franks, issued a decree for the improvement of the schools of his empire, and for increasing their number. Not only every bishop's see and every convent, but every parish, was to have its school; the two former for the education of clergymen and public officers, and the latter for the lower cla.s.ses of people. This monarch inst.i.tuted an academy of learned men, to whom he himself resorted for instruction, and whom he employed to educate his children, and a select number of the sons of the n.o.bility and distinguished persons.

11. The encouragement which these schools had received from government was soon discontinued after the death of this monarch, and his school establishment declined like that of Alfred the Great, which was commenced in the ninth century, on a scale of equal liberality. The designs of the English monarch were frustrated by the invasions of the Danes.

12. In the mean time, the Jewish rabbis had schools in Syria and in Northern Africa, as well as in Europe, which contributed to the preservation of ancient learning. Arabian schools were also established, in the ninth century, by the followers of Mohammed, in their Eastern and African caliphates, and in their Moorish dominions in Spain. Through these inst.i.tutions, the mathematical and medical sciences were again revived in Europe.

13. The cathedral and conventual schools continued, for a long time, the princ.i.p.al inst.i.tutions for education in Europe; and from them proceeded many eminent men. By degrees the light of science began to shine more brightly; teachers of eminence appeared in different places, who collected around them a great number of scholars; and a new kind of schools arose, the heads of which a.s.sumed the name of _rectores_.