A special examination in dentistry now exists in connection with the Royal College of Surgeons of England for students training in that profession, a certain amount of information being required in various branches of medicine and surgery. Acurriculum of study in these departments has been arranged; and candidart.es who can produce certificates of attendance on it are admitted for examination, and, if found fit, receive a certificate entitling them to practise as dentists.

In America this special system has for long been adopted and carried to a much greater extent. Colleges of dentistry are established in many of the leading cities there, each with what they designate a faculty of professors in the various departments of the art. In the Dental Cosmos, vol. xvii. No. 11, an American periodical, advertisements appear of seven different dental colleges, with seventyeight professors, demonstrators, &c. The professorships in these institutions comprehend those of mechanical dentistry, operative dentistry, dental physiology, dental pathology, dental therapeutics, mechanical dentistry and metallurgy, institutes of dentistry, <fcc. In each a diploma in dentistry —“doctor of dental surgery,” or of “dental medicine,” as the case may be—is conferred, the general fee for which seems to be $30, on the candidates having fulfilled the curriculum and passed the examination.

In the medical schools and examining boards in Scotland all this is different. No special or partial diploma is there given by the Royal College of Surgeons or other licensing body, while diseases of the teeth and adjacent structures are understood to be made subjects of lecture and examination in the same manner as other regional or special diseases occurring in the practice of medicine or surgery; and great as the improvements certainly are which such arrangements as those of England and America are on the old system, still it is to be hoped, and it is likely, that ere long practitioners devoting themselves to dental surgery will—like oculists, or aurists, or obstetricians, or other physicians or surgeons restricting themselves to or selecting one branch of practice in preference to another— be at the same time fully qualified medical men.

Number of Teeth — The complement of teeth in the adult human subject amounts to 32—16 in the upper, and 16 in the lower jaw. These are divided into what are termed incisors, canines, bicuspids or small grinders, and molars or the large grinding teeth. The order in which these different forms of teeth are placed in each jaw is the following :—- there are four incisors in front; immediately behind these on each side is placed the canine or eye tooth; next come the bicuspids, two on each side; and behind these again are placed on each side the three molar teeth, the last of which is sometimes termed the wisdom tooth, from· its generally appearing so late as from eighteen to twenty-five.

In the infant or milk teeth, or, as they are more pro perly denominated, the temporary teeth, the number and class of these organs is different. Here only 20 members of the series exist, and are divided into four incisors, two canines, and four molar teeth, similarly placed—ten in each jaw. The four temporary molar teeth represent or rather precede the four bicuspid teeth of the adult set, while the six molars above and below of the adult are not represented in the temporary set at all. In other words, the true permanent molar teeth have no predecessors.

Dentition.— The temporary set appear, or are cut, as follows. The two lower central incisors appear between the sixth and eighth months of infant life—these are generally succeeded in a few weeks by those of the upper jaw; the two lateral incisors of the upper jaw next appear about the eighth or ninth month, and those of the lower jaw quickly follow; the anterior molars of the lower jaw are cut about the twelfth, fourteenth, or sixteenth month, and those of the upper jaw immediately after; the canines appear about the seventeenth or eighteenth month, generally those in the upper jaw first; and before the age of two and a half years the second milk molars have usually commenced to appear, thus completing the temporary set of teeth at the age of about three years.

The temporary set of teeth begin to be shed between the sixth and eighth years of life. Previous to this, however, the first permanent molars are cut, generally about the age of seven. These are followed by the central and then by the lateral incisors. Next come the anterior bicuspids about nine years old; the posterior about ten or eleven; the canines about twelve; the second molars at thirteen; and the last molars, or wisdom teeth, from the eighteenth to the twenty-fifth years of life. Deviations from the order and time of appearance of both sets occur, but the above may be regarded as the general rule in the evolution of the temporary and permanent teeth of the human subject.

Structure and Form of Teeth.— The structure of both sets may be said to be the same. The body of each tooth is composed of a dense bony substance termed dentine. This is invested on the crown by a cap of still more dense material termed enamel; while the root, or fang, is coated externally by a layer of a softer substance, closely resembling ordinary bone, and termed cement. In the centre of each fang, and extending into the body of the tooth, is a hollow canal termed the pulp cavity, for the passage of vessels and nerves.

In form the incisors of both jaws are single-fanged, as are also the canines. The bicuspids of the lower jaw are also single-fanged, while those of the upper jaw are occasionally double fanged, or have a single fang bifid at its extremity. The lower molars, both temporary and permanent, possess two fangs, one behind the other. These two fangs are widely separated in the temporary molars; while, on the other hand, in the posterior molars of the permanent set they are not uncommonly united into one. The upper molars of both sets possess three fangs—two external or cheek fangs placed one behind the other, and a third situated on that side of the tooth next the palate.

No such spaces exist between any of the teeth in the dental arch of man as occur in the lower animals. In this way, where the jaw is small, or where unusually rapid or simultaneous appearance of the members of the second, or persistence of those of the first set occurs, irregularity of the teeth results. This is sometimes increased by the evolution of supernumerary teeth, these being generally out of the line of the others; and occasionally matters are rendered worse by the natural teeth being themselves of unusually large size. Cases also occur in which the number of the teeth is defective, and some rare instances have been recorded where these organs never appeared at all.

The remedy in cases of dental irregularity is to remove by extraction such teeth as are in the way, and by mechanical contrivances, known as regulating plates, to apply pressure in such a manner as will move the misplaced tooth or teeth into their normal position, and retain them there for some time afterwards. Such plates are constructed on the same principles, and of the same materials, as the bases of artificial sets, which will come to be treated of afterwards. It not unfrequently happens that nature, if left to herself, effects a wonderful improvement in cases of dental irregularity. This is frequently observable where it is the upper canines which are misplaced. These teeth when appearing, as they often do, outside and much above the necks of the adjoining teeth, occupy a long time in descending, and in certain cases the anterior portion of the maxillary arch seems to enlarge sufficiently to afford space for their almost perfect arrangement during this period. The same thing occurs, but to a less marked extent, in the case of other teeth; in general, however, nature requires to be assisted by art in some way, as has been above indicated, where the irregularity exists to any great amount.

Diseases of Teeth.— The teeth being living organisms are, like other structures in the animal body, subject to disease. Some of the diseases bear a close resemblance to mere chemical decomposition, such as occurs in dead or inorganic matter, and at a certain stage of some dental affections a process of the kind does no doubt occur; but this is so mixed up with, and accompanied and preceded by vital action, that to consider it as a mere chemical or physical lesion would be pathologically incorrect. Various arguments have been advanced by its advocates in support of the chemical theory of dental caries; but however ingenious or specious these at first sight appear, they fail to explain many phenomena in the origin, the period of occurrence, and the stages and progress of this disease, unless the vital element in its nature be also taken into account.

Dental caries, or decay of the teeth, may briefly be described as consisting in a previous imperfect development, or in the access of some morbid action interfering with the nutrition or vitality of their tissues, thus rendering them liable to any destructive agencies to which they may be βubjected,by which they become disorganized, disintegrated, and broken down, leaving the sensitive pulp exposed, whereby acute pain is occasioned, especially when the destruction of the protective tooth substance has been rapid. Sometimes the process of decay is insidious and unobserved. Its advent is then supposed to have been sudden, and its progress more speedy than has really been the case. This, however, in many instances arises from the condition of matters being overlooked until the enamel, which resists destruction longest, being undermined and falling in, reveals for the first time the cavity existing underneath. Pain, probably also for the first time, is then experienced from exposure and irritation of the dentinal pulp, and toothache, as it is termed, is produced.

Necrosis, or death of a whole tooth, is another lesion to which these organs are liable. This may result from either acute or chronic inflammation in the tissues connecting them with the jaw, or from a blow, or from any other cause leading to their vascular supply being cut off. The necrosis may involve the whole tooth, or it may be partial —as, for example, where it is limited to one fang of a multiple fanged tooth. Tn these cases there may be no breaking down of texture, but the tooth becomes discoloured, loosened, extruded, and at last detached from its socket, from which after a time, and generally after considerable uneasiness, it drops out.

Exostosis, or a morbidly increased growth of certain parts of a tooth, being in almost every instance confined to the cement substance described as covering the fang or root, is an affection somewhat obscure in its outward symptoms. It is generally a consequence of previous disease of the tooth, leading to chronic inflammation of the textures covering the fang and lining the socket (or alveolus) in which it is implanted. This leads to a deposition of new material in the cement till that substance appears in nodular masses attached to or surrounding the apex of each fang, and sometimes uniting several of such fangs into one. The presence of this additional and increasing bulk of hard tissue within the inclosing socket produces pain of a severe and somewhat anomalous character by pressure on the adjacent nerves, which is often mistaken for neuralgia or tic of a less unaccountable origin. It further acts within the unyielding bony socket referred to as a means of rendering removal of the tooth much more difficult, owing to the bulbous extremity of the enlarged fang acting like a rivet in its fixation. Generally, however, the teeth in which exostosis occurs have been too long the subjects of irritation and decay not to be suspected when obscure pain of a less localized nature exists in their vicinity; and not unfrequently there is found round the necks of teeth or stumps so affected a red and tumified condition of the gum, sufficiently indicative of the state of matters below to warrant their extraction.

Alveolar abscess, or gum boil, as it is popularly denominated, is a localized inflammation going on to suppuration, and generally confined to the tissues surrounding the apex of a tooth fang. The pain usually commences with a feeling of tenderness and enlargement or lengthening of the whole tooth. The gum becomes swollen and tender over the whole depth of the root, generally to a greater extent on the outer side of the jaw. The face also becomes swollen, and the glands in the neighbourhood of the jaw feel enlarged and tender. The pain is not commonly continuous, but rather remitting in its character, sometimes ceasing altogether—only, however, to be followed by an increased attack, while its repeated exacerbations night and day lead in many'cases to very considerable constitutional disturbance. After a time the purulent matter secreted makes its way to the surface, sometimes finding an escape alongside of or through the pulp cavity of the fang, and very frequently, as the name given to the disease indicates, by pointing and discharging itself through the gum.

Occasionally, instead of pointing on the surface of the gum, the matter takes a more indirect course and points on the surface of the cheek, bursting and leaving an open sore there which seldom closes until the tooth or stump has been extracted. At an early stage of this disease fomentations and other modes of relieving inflammatory action do good, but evacuating the matter by means of incisions or extraction of the offending tooth are the only reliable remedies at a later period.

Teething.— What is termed dentition, although in its widest sense properly including the development of the teeth within, as well as their subsequent appearance through, the superimposed tissues, is generally restricted in its application to the latter division of this process, more especially as it occurs in connection with the temporary or milk set, during the period of early infancy. The genesis, increment, and evolution of these organs involve so much of what is purely physiological, and would entail the discussion of so many points of a histological nature, that only the latter stages of evolution or cutting of the teeth can be referred to here. Regarding this occurrence, the most vague and contradictory opinions have been entertained. Erroneous notions of its nature, and of the exact manner in which to account for many of its phenomena, have been and still are promulgated. A number of morbid affections incident during infancy are set down as clearly attributable to the tooth’s penetration of its inclosing tissues, and considered by many authorities as of every day occurrence; while the views advanced with reference to the pathology and treatment of such cases, suppositional or otherwise, are equally various and conflicting. The probable solution of the difficulty seems to be that, while evil consequences may in certain instances be traceable to dentition, the frequency and importance of such cases is very much exaggerated.

Extraction. —-This constitutes the most important operation of a surgical nature falling under the care of the dentist, and is chiefly called for where the condition of the tooth, from disease or injury, precludes the possibility of saving it by stopping or other means. The operation is also frequently resorted to where the teeth are too crowded in the jaw, or where they are irremediably misplaced, or where supernumerary members of the series exist and occasion inconvenience. In order to extract any tooth successfully, there is demanded a knowledge of what its configuration normally ought to be, and of the proper instrument to use; and, along with these, the condition to which decay or other disease may have reduced the tooth must be kept in mind while proceeding with the operation.

In seizing a tooth in order to its extraction the part upon which the hold is taken should be sufficiently sound and strong to withstand the force necessary for dislodging the fangs; and to obtain such a hold it is necessary to thrust the grasp of the instrument as far as possible beyond the spot affected by decay. It should then be detached from the walls of its socket in that direction where least resistance is likely to be met. This must be judged of according to circumstances, but in general is indicated by an acquaintance with the anatomy of the structures concerned. After being thus loosened it has merely to be lifted from the jaw to complete the operation. Sometimes a tooth is so firmly secured in the jaw that its own tissue will give way before it will separate from the alveolar cavity in which it is fixed. This is particularly the case in friable teeth; and frequently even in the strongest teeth the root or fangs may be malformed or bent, or secured in such a manner as renders their extraction extremely difficult or altogether impossible by any ordinary means.

The instruments employed in extraction may be divided into those which grasp the tooth between their blades and literally extract or draw it out, such as forceps, and those which apply the dislodging force by acting as a lever in the manner of a crow bar, such instruments being termed elevators. The key, an instrument of great power, but now very properly almost disused, partakes in a measure of the properties of both these instruments, but that in a very imperfect and disadvantageous manner. In some rare cases, however, it may be found of much service when used with circumspection. It is impossible here to enter into detail regarding the different forms of forceps, elevators, and other instruments required in dental surgery; but one great principle may be laid down with respect to all of them, which applies especially to forceps, and that is that their form should be as simple as possible consistently with fitting and grasping securely the particular tooth they are intended to remove, and with conveniently reaching that part of the mouth in which it is situated.

Régulation of Teeth.— In the extraction of teeth for the purpose of affording space in cases of dental irregularity from overcrowding, it often becomes necessary to remove a healthy organ, and before doing so among the permanent teeth certain questions present themselves for consideration. Unless there be a fair probability of such a step being sue cessful it endangers the loss of two teeth should the originally misplaced one be so objectionable and so unyielding to treatment as to require this. In the temporary set the principal disadvantage connected with the removal of any of their number is when to make room for one permanent tooth two or more temporary ones would require extraction,—as of course space is thus provided at the expense of the second permanent tooth, for which one of the two temporary ones was keeping a place. In this set, however, the objection to removal of any of its series is greatly obviated by the fact that, while the teeth are very soon to be lost at all events, the jaw is increasing in size and progressively affording more and more room itself for the incoming second set. Along with extraction, in the great majority of instances pressure requires...