Practical dentistry, surgical and mechanical : with appendix, numerous formulae, and guide how to become a registered dentist

Front matter

ESTABLISHED 1878.

The British and Colonial Druggist.

A WEEKLY JOURNAL OF PHARMACY AND OF THE DRUG, CHEMICAL AJID ALLIED TRADES.

Preface

The desire lias often been expressed by students and others for a small, but comprehensive work, dealing with the main features of both branches of the dental art.

This want it is attempted to supply in the following pages, and it is hoped they will meet with the approval of dental students and practitioners.

The aim throughout has been to treat each operation in as concise and practical a manner as possible.

The first part is devoted to the surgical branch of the art, the principal operations being briefly considered and explained.

Under the head of mechanical dentistry, descriptions of the most improved methods of manufacturing artificial dentures will be found, together with notes in dental metallurgy.

Pharmacists practising dentistry will find the work especially suitable to their requirements.

PRACTICAL DENTISTRY:

SURGICAL AND MECHANICAL.

Introduction

The art of Dentistry may be said to be composed of two distinct branches, viz., the operative or surgical and the mechanical.

The former embraces the general treatment of th6 teeth and their diseases, together with their preservation, regulation, and extraction, &c., while the latter consists of the several processes in dental mechanics and metallurgy necessary to the making and fitting of artificial dentures in as perfect a manner as possible.

To achieve success in both branches requires constant practice and experience. A man may be a skilful operator and yet an indifferent mechanic, or vice versa. Sometimes one branch is studied to the neglect of the other, yet he who aims at becoming a successful dental practitioner must acquire an intimate and practical knowledge of both if he would claim to be a master of his art.

To become a smart operator he must possess tact, nerve, and confidence in himself, combined with a thorough knowledge of the anatomy and physiology of the teeth ; while, as a mechanic, he should be practically acquainted with the several and best methods of making dental plates and fixing artificial teeth, and be able to complete them in a finished and workmanlike manner.

Dental science lias made rapid strides during the past few years, and the dentist of to-day, in bis capacity as a specialist of the teeth and mouth, should merit the confidence bestowed in him. He is expected to have a thorough scientific knowledge of the art of dentistry, and as the oculist, or other specialist of the healing art, be competent to apply it in the treatment of such diseases that may come within his domain. To advise on the care of the teeth, and when operation is necessary be able to bring to his aid the proper curative remedies, a certain knowledge of some drugs and their properties is necessary. An intimate acquaintance with the anatomy of the mouth, together with the growth and structure of the teeth is also of the greatest importance to the dentist.

With the development of dental surgery there has arisen the desire to mitigate the pain attending its operations, and the use of amesthetics has become an every-day occurrence in dental practice.

In the following chapters it is proposed to deal in as practical and concise a manner as possible with the principal operations, surgical and mechanical, the dentist may be called upon to perform, with the object of aiding those who have not had the opportunity of a large practical experience of the art, and also to assist the student in gaining an insight into some of its elementary principles.

In the dental, as in other practical arts, actual practice in the operating room and the workshop is of the greatest importance and absolutely necessary, and we can here but barely outline some of the methods employed in the most important operations.

Part I. Surgical Dentistry

THE TEETH AND THEIR DEVELOPMENT —FIRST DENTITION— SECOND DENTITION.

In the human being two sets of teeth make their appearance during the ordinary course of life, the first being termed the temporary or milk teeth, and the second the permanent teeth. The former usually remain until the seventh or eighth year of childhood, when they are replaced by the later, or permanent set.

The temporary teeth are twenty in number, ten in the upper and ten in the lower jaw, and arranged as follows : —

Canine.

Incisors.

Canine.

I ^

UPPER.

LOWER.

Incisors.

Canine.

The first stages in the development of the teeth, according to Arnold and Goodsir, consist of certain changes in the mucous membrane covering the borders of the maxillae. This occurs about the sixth week of embryonic life, and appears like a depression or groove of horse-shoe form along the edge of the jaw in the mucous membrane of the gum, and is called the primitive dental groove.

From this arises a series of ten papilla in regular succession, which are the germs and rudimentary pulps of the milk teeth. After this papillary stage is complete, the margins of the dental groove become thickened and prominent, and the bottom becomes converted into a series of follicles, each containing one of the papillae. This is known as the follicular stage.

The follicles soon become deeper, and gradually shape themselves similar to the crowns of the future teeth. With future development the groove becomes obliterated, the follicles becoming converted into closed sacs. This saccular stage is completed about the fifteenth week. The papillae, now the dental pulps, acquire an exact likeness to the crowns of the future teeth, and then the formation of the hard substance begins. This commences by a cap of dentine forming on the pulp of the milk tooth, which generally increases until the crown is complete, and soon after, part of the tooth appears through the gum.

The period at which the temporary teeth make their appearance above the gum varies, but the usual time is about six or seven months after birth, although infants are sometimes born with one or two teeth fully cut. Children frequently suffer much pain during thisperiod ofteething, through theslow growth of the teeth, which cause the gums to become swollen and inflamed. This is often attended with feverish symptoms, and may even induce convulsions. Immediate relief may be given in such cases by making a small iucision in the gum with a lancet above the tooth. Each milk tooth is developed from its germ, and in the process of development separates a portion of itself to be the germ of its successor in the permanent eruption still living though not growing. As the new tootli comes the crown of the temporary tooth dies, and is eventually pushed out to give place to its permanent successor. Thus, almost directly the temporary set are fully developed the process commences for their removal. The formation of the permanent teeth is exactly the same as that of the temporary set. The pulp is derived from the temporary teeth, the connection being intimate, as both are formed in the one socket, but when separation ensues the permanent teeth become fixed in distinct bony cells or partitions.

Thus separated from the socket of the milk tooth by this partition, against which as against the root of the milk tooth above it pressure is caused, these parts gradually become absorbed.

This destruction commences at the root of the tooth, which is bit by bit absorbed, until nothing but the crown remains, which falls or is taken out, and the permanent tooth takes its place. The subsequent development of the permanent teeth takes place in the same manner as the former set, but now the number is increased and the order different, The order in which the permanent teeth make their appearance in the lower jaw is as follows, the corresponding teeth of the upper jaw being developed a little later :

Molars — first at the age of six years.

Incisors — central, at the age of seven years.

,, lateral, at the age of eight years.

Bicuspids — anterior, at the age of nine years.

„ posterior, at the age of ten years.

Canines, at the age of eleven to twelve years.

Molars — second, at the age of twelve to thirteen years.

„ third or wisdom, at the age of seventeen to twentyone.

During tlie growth, of the teeth the jaw increases in depth and length, changing somewhat in form, and so provides for the extra teeth.

The full complement of the permanent teeth is thirtytwo, sixteen in the upper jaw and the same number in the lower, though frequently a less number may be developed. They are arranged as shown in the diagram :

Canine 1 Bicuspids 2

Incisors.

2 Bicuspids

UPPER.

LOWER.

Bicuspids 2

Incisors.

2 Bicuspids 1 Canine

Each tooth consists of three portions, viz., the crown, or the part which projects above the gum ; the fan/j, or root which occupies the alveolus or socket ; and the neck, or constricted part that comes between the two, The roots of the teeth are implanted in the alveoli of the jaws, the lining of which is called the periosteum or periodontal membrane, being blended with the tissue of the gums which surrounds the necks of the teeth. The form of each tooth is adapted for a special purpose. Thus we have the incisors, or front teeth, with chisel-shaped crowns for cutting and dividing soft food. They have a long single fang slightly compressed at the sides. The canines, or cuspidati, have conical and thick crowns, convex in front and hollowed behind; their fangs are also single, conical, and com-

Crown.

Neck.

Fangs.

I

IV. V. V.

Fig. I. Molar tooth showing crown, neck and fangs.

Fig. IT. Upper and lower incisors. Fig. III. Upper canine.

Fig. IV. Bicuspids, front and lateral views. Fig. V. Molars.

pressed at tlie sides, and are the longest of any of the teeth. The upper canines are commonly called the eye teeth, and are larger than those in the lower jaw. The form of these teeth make them adapted for such work as disintegrating hard food. The bicuspids have a compressed crown, broader than the teeth described, which is surmounted by two pointed tubercles or cusps. The fang sIioavs a tendency to become doubled, the apex being usually cleft, but the form varies. The molars haAre the largest crowns of all, and graduate in size. The last molar teeth are called the dens sapiential, or Avisdom teeth, owing to their late appearance. The fangs of the molar teeth are multiple. The tAvo anterior molars of the upper jaw have three, the corresponding teeth of the lower jaw having but two each, and are broad and compressed. The bicuspids and molar teeth, owing to their breadth of crown, are specially adapted for crushing and grinding the food in the process of mastication. Coming to the structure of the tooth, we shall find on making a section that it is composed of a hard substance, and holloAV in the centre. The shape of the caA'ity is similar to that of the tooth, occupying the interior of the crown and extending down each fang at the point of which it leaves a small aperture. This holloAV portion is called the pulp cavity, and is filled by a soft, sensitive substance called the dental pulp, which consists of areolar filaments, &c., andis well supplied with vessels and nerves Avliich are derived from the internal maxillary artery and the fifth pair, and enter through the small aperture at the apex of each fang. It is through this nerve connection the pain sometimes felt in one tooth is communicated to another. Through the minute orifice in the tooth fang there also passes a ATein and artery, by which the vital fluid is received into and returned from the tooth, the blood passing in tAvo currents, first through the artery into the tooth and then returned by the vein.

The solid portion of the tooth is composed of three substances, viz., the ivory or dentine, the enamel, and the cement or Crusta Petrosa. A fourth variety of tissue is formed within the dentine as age advances.

The dentine forms the bulk of the tooth, and gives to it its general form. In structure it is similar to compact bone, and under the microscope appears to consist of a large number of very fine tubes embedded closely together in a compact substance.

The enamel is the hard, white covering which protects the exposed portion of the tooth, and is the hardest of all the dental tissues. It is thickest on the grinding surface of the teeth, and ceases at the neck. It is also the hardest substance in the human frame, and capable of producing sparks when struck with steel. In composition it is made up of minute, hard, and dense fibres of earthy matter packed closely together, of which 96.5 per cent, are earthy constituents. The enamel is soluble in dilute acids.

The Crusta Petrosa, or cement, is a layer of thin bone that covers that part of the dentine which is not protected by the enamel. It extends over the whole fang, fixing it in the socket, and as age advances becomes thicker, especially near the apex of the fang, and, as a rule, eventually blocks up the aperture leading to the pulp cavity. Its chemical composition resembles bone, and contains 80 per cent, of animal matter. It is the seat of the bony growths, or exostosis, sometimes found in the teeth. Osteo-dentine, or secondary dentine, appears to be produced by a slow conversion of the pulp, and is a hard substance which becomes deposited on the surface of the dentine after the age of twenty, gradually making the cavity of the tooth smaller in size.

THE CARE OF THE TEETH.

A large amount of our comfort and health depends on the teeth ; and especially on the amount of care that is bestowed on the mouth during the period of youth. They should be thoroughly cleaned twice daily by means of a brush of medium bristle, an antiseptic tooth-powder and warm water. Brushes with hard bristles are undoubtedly injurious to the enamel of the teeth if used for any length of time. A well-blended tooth powder is preferable to paste or liquid dentifrice, for obvious reasons. Care must be taken to remove any particles of food that get lodged between the teeth after eating, and for this purpose the quill is preferable to a metal toothpick ; a strand of floss silk being also very useful for this purpose.

Mastication. — As the primary and chief use of the teeth are for the mastication of food, it follows that if they are imperfect, loose, or diseased that important process cannot be performed as it should be, with the result that dyspepsia is often induced with its attendant evils. In the process of mastication the food is blended with a bland alkaline liquid, secreted by the parotid submaxillary and sublingual glands, and conveyed by their ducts into the mouth. Its use is to keep the tongue and mouth moist, and thus assist mastication, the first process of digestion.

IRREGULARITIES OF THE TEETH AND THEIR TREATMENT.

Irregularities that may occur in the growth and position of the permanent teeth, and the best treatment to employ in such cases, are matters of important consideration.

To begin with, the most frequent cause of this is at the time when the milk teeth are being shed. Sometimes, if not removed, they occasion a sufficient obstruction to prevent the permanent tooth appearing in its proper place, and causing it to grow out of its course. This is a common occurrence, and renders a frequent examination of the mouth during that period a necessity, when most irregularities may be easily prevented by the removal of the obstructions. Sometimes the teeth on appearing through the gums are in an objectionable position, such as being turned inwards ; if not very irregular, mechanical treatment is unnecessary, and they will gradually assume their proper position. A very slight amount of force, if applied constantly, is sufficient to alter the position of a tooth. The treatment usually adopted in cases where the teeth are growing in an inward direction is by the wearing of a vulcanite plate, fitted to the palate and extended over the molar teeth. The plate is fitted to the necks of the teeth to be operated on, between which and the plate, small pegs of compressed wood are placed in cavities cut in the vulcanite for receiving them. When the plate is being worn, and as soon as the wood commences to absorb moisture it will expand, and exerting a gradual pressure on the tooth in front of it, force it outwards. From time to time the wedges must bo removed and replaced with new one3, until the tooth has acquired the proper position. In case of a tooth growing out of position and partly behind another, a ligature or elastic band should be adapted to it, exerting pressure in the opposite direction, and worn constantly for some time. It will be well to bear in mind that a piece of india-rubber compressed between two teeth will force them apart in the course of a couple of hours, the teeth becoming tender to the touch and slightly loose, although on removal of the rubber the teeth will gradually resume their former position. For permanent results nine or ten months is necessary in most cases to rectify such an irregularity as the inward growth of the teeth. When two incisors are growing too far apart this may be remedied by wearing the ligature or elastic band. Another irregularity is when the lateral incisors are affected by the growth of the canines through their growing in such a position as to cover the root of the former. It is necessary in such cases to give the canine room to pass backwards, and the temporary canine in this instance should be extracted to allow the incisor to regain its proper place. Otherwise temporary teeth should not be extracted without some good reason for so doing.

Another method employed to regulate the teeth consists in attaching to the tooth to be moved a belt of gold, secured by a thread and nut. Some prefer the use of piano wire springs as being more easy of control. The jack screw is another instrument which may be used when greater force is needed, such as the expansion of the whole arch or the bending outwards of a single tooth. It may be used either with or without a plate. Dr. Coffin recommends the use of expansion plates for the correction of irregularities.

The plate is made of very tliin vulcanite, and is cleft, with a wire spring connecting, by means of which the plates may be easily shaped to suit the necessity of the case.

Torsion, or twistingof the central incisor, is sometimes met with, when the tooth is growing up edge outwards. This may be treated by the plate and springs, or the tooth may be rotated by means of a ring of platinum foil made to fit round its neck to which a piece of wire is soldered, bent to the outline of the palate, so as to form a lever, and traction made on the end of it by means of an elastic ring tied to one of the back teeth. It may also be treated in some instances by forcibly twisting the tooth with the forceps, and is often done successfully when the patient is young. The instrument used should be a pair of straight forceps. The canine teeth are very liable to grow irregularly, either standing in or outside the regular line. In such cases, as the canine is an important tooth, it is sometimes necessary to sacrifice one of the neighbouring teeth, either the first molar or one of the bicuspids. The first molar is nearly always the first tooth to become diseased, and would therefore be least missed. In regulating, no fixed rules can be laid down, and a great deal must depend upon personal judgment on the best method of dealing with the case. Irregularity of the bicuspids often necessitates the wearing of the jack screws or an expansion plate, for which either metal or vulcanite may be employed.

FRACTURE AND OTHER INJURIES.

A fracture may occasionally happen to a tooth through a sharp blow or fall. It may be trifling, such as the edge of the o tootli being cbippecl, which a few touches of the file will rectify, or it may be split from crown to root, in which case special effort should be made to save the tooth. The incisors, owing to their prominent position, are most liable to accident. Should the fracture extend through the pulp cavity it is seldom possible to save the tooth, and extraction is the best treatment. If the upper part or crown of the tooth be broken off above the gum, a new crown may often be put on by pivoting. The tooth is thus rendered serviceable, and may last for a dozen years. Pivoting, as a rule, can only be carried out successfully on teeth with a single root. A fracture may occasionally be successfully treated by making a collar of thin gold to embrace the root, just below the edge of the gum; this is adjusted, the new portion fitted to the root, then backed and soldered.

PIVOTING.

The operation known as pivoting, by means of which new crowns may be fixed on the roots of old teeth, cannot be successfully carried out unless the latter are free from disease. It is best performed on the incisors or

canines. The root is cut down to a good flat sur-

face with the aid of the dental engine, and the apex having been closed by foil, the pulp canal is drilled to the size of pin wire. An impression of the surface of the tooth is then taken with compo or plaster, and a tooth having been adjusted to it, the side of the pin is scraped, a shred or two of floss silk wound round it dipped in a solution of copal ; this is placed in the drilled hole and pressed home. Another method employed is by using a flat tooth with a pin soldered to it, and a small metal plate fixed to the back. This may be well fixed by taking a piece of platinum foil and making a hole in the centre, the pin being slightly attached to it with solder. The surface of the root having been prepared and thoroughly dried, it should be coated several times with copal solution before the pin is pressed into the root and fixed. The foil may be burnished into contact with the tooth as a finish. I* roots of a large size the hole may be drilled of a larger size, and a thin metal tube inserted, into which the pin can be secured. In such cases a small cavity should be formed near the surface of the root, and filled with gold or amalgam, which will protect the surface before inserting the pivot tooth. Another method is by fixing a cap of thin gold, carefully made to fit over the top of the root, and clipping it in at the neck of the tooth. It may be fixed by filling the hollow crown with hot gutta percha and pressing it firmly on.

CARIES.

Many and varied are the theories that have been advanced from time to time as to the primary cause of caries, or decay of the teeth. Usually it first attacks the enamel and dentine, and then causes the destruction of the crown of the tooth.

It is held by some to be due to the result of chemical change in the dental tissues arising from constitutional causes alone, and not a disease. Decay may also be induced by accidental causes, such as a fracture to a tooth. Caries makes itself first visible in the enamel, either in the form of a small dark spot or an opaqueness which gradually becomes a brown colour. Bell states that he believes this to be due to an inflammatory action set up in the dental tissue, which, occurring in a dense, hard substance, ends in the death of the tooth. It has also been suggested that caries may be caused by the mouth secretions becoming acid owing to some disordered condition of the system, which attacks the enamel of the teeth. Certain micro-organisms are also present in carious enamel, but whether their presence is productive of decay or not, it has not at present been proved. Early predisposition to caries is thought by some to be hereditary, and it has often been noted that decay frequently begins in the teeth of women during pregnancy. Acids of any kind, vegetable or mineral, immediately attack the enamel of the teeth, it is therefore more than probable that the generation of such in the mouth, through the decomposition and fermentation of small particles of food, and the presence of destructive organisms, is the most probable theory of the origin of the caries. As decay advances the dentine becomes soft and crumbles away, leaving bare the pulp cavity. It spreads, as a rule, in the shape of a cone, which gradually enlarges at the base. Tomes states he believes it rarely happens that the presence of caries in its earlier stages is altogether unattended by some uneasiness in the affected tooth. This form of toothache must be distinguished from that due to inflammation of the pulp, the result of exposure ; there is an absence of throbbing, and contact with hot and cold fluids does not produce unpleasant effects. In support of the theory that caries is due entirely to external causes, it is possible for human teeth which have been fixed and worn in artificial dentures to become decayed, the structure undergoing exactly the same process of destruction as occurs in the ordinary natural teeth. The fermentation products from sugar and milk, also malic and citric acids from fruits, act in a deleterious manner on the dental tissues.

Cryptogamous growths have also been detected in carious dentine, notably leptotlirix, which was noted by Ficinus ; also the Mycelium of Oidium albicans, and the Protococcus dental is of Schrott, may often be detected in microscopical examination. The presence of these organisms is also supposed to be productive of decay. The teeth of women are more liable to decay than those of men. The time that decay is likely to commence varies largely, but, as a rule, if it does not attack the teeth before the age of 24 or 25 the teeth may remain sound until the age of 50 years. A protracted and serious illness may induce the teeth to decay, and also the action of certain medicines, such as iron and mercury, is injurious to the teeth. Preparations of iron or acids should always be taken through a tube, or the mouth well rinsed with water afterwards.

FILLING DECAYED TEETH.

The process of decay in the tooth may be treated by filing or filling. In cases where it has only proceeded to a small extent the diseased tissue may be got rid of by filing. Files of various patterns and sizes are made, also of varying degrees of roughness. The shape used must depend on the form of the tooth. After the filing the part must be polished with fine pumice power, and finally with chalk. Enamel cutters and chisels are also used for excising the diseased portions of the tooth, and if used carefully the results are very satisfactory. Corundum d’sks used in the dental engine are also very useful in the removal of diseased bone and polishing the teeth ; also disks of sand paper and emery, and a mixture of corundum and vulcanite are very useful. Another method of arresting caries, suggested by Tomes, is the free application of powdered nitrate of silver, in such cases where the necks of the teeth are softening along the edge of the gum. From the effects of the nitrate of silver the softened tissue becomes black, wears away, leaving a polished brown surface which is not again attacked by decay.

The chief method of arresting caries is by filling, in which operation the diseased part of the tooth is removed, the deficiency supplied, and it is again made serviceable and useful for mastication.

A great deal of the success in filling depends on the care bestowed in preparing the tooth for the plug. All diseased tissue must be excised and carefully scraped out until a suitable cavity is made. Overhanging edges and sharp corners should be cut away. If the walls of the tooth will stand it, one or two grooves run around will add to the permanency of the plug. The enamel is removed by special chisels designed for scraping, while the dentine is excised by excavators of various forms. Softened dentine is better removed by cutting than scraping, and it also gives less pain to the patient. The enamel may also be excavated by the rose-liead burr, used by hand or with the engine, the latter removing it quickly and effectively.

Should the tooth be sensitive, a small portion of arsenic or arsenical paste placed in the cavity, covered -with a plug of absorbent wool and retained for a few hours in the tooth will destroy the nerve. Arsenic should not be used if the cavity is deep, or else deatli of the pulp may follow. Some degree of pain may be felt in the tooth for several hours afterwards. A small piece of chloride of zinc applied to the tooth will also make it less sensitive. Ethylate of sodium, a solution of tannin in spirits of camphor, and carbolic acid, or a strong tincture of Indian hemp are also useful for the same purpose, and may be employed with more or less success.