Dentistry: From Ancient Years to Modern Era Dentistry is itself a branch of medicine, but it has its own branches that had emerged through many years of research and technological advancements, thus providing a better and more professional approach on the issues regarding the oral cavity. There is the official division of specialties, those that are recognized by many national dental organizations, and also there are some specialties that are internationally (4) (15).
2.1 Caries and Conservative dentistry Since the beginning of time, the oral cavity has been an issue concerning a healthy lifestyle. As archaeologists over the years, by their various methods of bone and teeth assessment, found that decay and other kinds of dentistry related diseases were an everyday life problem. We can also see the healing efforts they’ve tried even though they had no knowledge or the proper means we have today. More about dental caries will be mentioned on a later chapter (4) (16). As the people advanced within the years, they started using a technique similar to what we do for cementing, materials and methods use for cementing today will be discussed later on, although they were limited to using only naturally occurring products that did not necessarily address the problem. What was used mostly was a mixture of henbane and bees wax, both heated, directing the mixtures smoke towards the decaying teeth and the cementing the tooth with mastic. That’s all that was found regarding the Egyptians and toothache, and it calculated to take time in 2600 B.C.E (16). The Chinese however started using a mixture in the 7th century, which consisted of silver tin and mercury. Basis of this mixture is used until recent days with a slightly different formula. Today it is called amalgam and further information about it will be mentioned in later topics. Furthermore, somewhat around the 16th century, the Chinese used arsenic on decayed or decaying teeth, a material that was used in recent days too, to devitalize the pulp of the tooth, but it was banned because of its high toxicity. The Chinese however, are thought to have discovered pressure points in the human body, that when punctured skillfully, the patient was relieved from any dental related pain. It is believed that there are almost over 30 pressure points that can momentarily provide such a relief (16).
To this day, conservative dentistry is the a division of dentistry that deals with the restoration of hard dental tissues, and it is divided to cariology and endodontics. Cariology, as the name suggests, deal with the etiology, prevention, extend and treatment of dental caries, where endodontics deal mostly with the inflammation in the inner part of the tooth, specifically the root canals, a structure that will be discussed, along with the whole anatomy of the tooth, later on (4).
2.2 Prosthetic Dentistry Evidence suggest that treatments were tried in the past, that relate to what we call nowadays prosthetic dentistry, in the land of what is now Italy around the time of 1000 to 400 B.C. The material was gold, rings of it were place between natural teeth. All that was done at those ancient times, is the lead for todays’ prosthetic treatments, especially gold which is still the most desirable metal to be used in restoring teeth due to the properties it has that make it nearly indestructible when placed into the harsh environment of the oral cavity. Furthermoreit retains its full integrity, thus providing a perfect seal. After a short time of regression, the same civilization use animal teeth and human teeth in the prosthetic denture. The big disadvantage was that these teeth were deteriorating quickly, but on the other hand they were very easy to be produced and remained as treatment of choice until the 19th century (17). The Japanese, in a more recent period, were constructing wooden dentures, made from the tree Buxus Microphylla, a tree found only in Japan and Taiwan, aroung the year 1530 and lasted for another 300 years. These dentures were first created by NakaokaTei, who created them with an identical shape as the natural dentition and also it was shaped to fit in any condition of missing teeth (17).
A modern era of prosthetics was launched by the first denture made of porcelain, in 1978 in France by Alexis Duchateau (17), and by manipulating porcelain and adding other coloring
material, a denture that resembled natural teeth was manufactured. A few years later, a goldsmith named John Lenon was manufacturing dentures made of porcelain with 18-carat gold teeth mounted on it (17). In the modern prosthetic practice, there is a great list of materials and methods that can be used to assess every individual problem. Many procedures that were used in the past are as well used today, and even more were adjusted and modified to improve the characteristics and results. A prosthodontist, in coorperation with a dental technician, can create a and individual artificial tooth or a part of it, fill spaces within natural teeth with either a fixed or a removable denture and even recreate dentures when a patient has no natural teeth remaining. It is very important to fulfill the gaps between the teeth in order to prevent upcoming complications that will lead to further destruction of the dentition.
Figure 1BuxusMicrophylla (Source: Wikipedia)
Figure 2 A modern restoration of a common problems in prosthetic dentistry, a bilaterally shortened arch (Source: NSDentalStudio)
2.3 Surgery In most cases, when a tooth was extensively damaged or caused a lot of pain, it was extracted. But do not consider the tooth extractions as we know them. At first, a chisel-shaped piece of wood was placed near the tooth and was hammered by a mallet, to force the tooth out of the oral cavity. Then the Chinese surgeons used their own fingers to pull the teeth out, until the Greeks and Romans had develop something similar to what we use today as forceps.. Furthermore, in middle ages, extractions of teeth were performed by barbers. At the time of 1505 they were considered as medical personnel and were also part of the medical faculty in the University of Paris (18) (19).
Figure 4 A dental surgeon, a dental assiistant and a patient at the time of dentoalveolar surgery (Source: Bordia Dental Associates)
Figure 3 Impacted third molars, a very common case of dentoalveolar surgery (Source: Tara Dental)
Today, surgery in dentistry is divided into maxillofacial and dentoalveolar. Dentoalveolar surgery focuses on lesions confined within the oral cavity or in a very close proximity to it. It specifically deals with extraction or cutting parts of teeth, treatment of infections and preserving the infected teeth by surgical means. Maxillofacial surgery is more elaborate, as it deals with the oral cavity and its proximity, but also it extends to facial structures, jaws and the temporomandibular joint. More specifically it deals tumors, infections, developmental and accidental deformities (4).
2.4 Anesthesia The centuries to the modern era have passed, and as people suffered more than enough, the need to alleviate pain had intensified. This is where people sought to find a variety of ways of anesthesia to carry out all those painful treatment methods. The first to be used was nitrous oxide gas, used in 1844 and a few years’ later ether and chloroform were used, as well as cocaine. Only a bit more than half a century later, in 1905, a German chemist named Alfred Einhorncreated Novocain, a local anesthetic made of procaine. It was introduced to surgery by Heinrich Braun.
Figure 5 Dental anesthesia for the inferior alveolar nerve block, a technique that anesthetizes all teeth of the lower quadrant in the same side where the anesthetic was injected (Source: Junior Dentist)
Novacain was soon replaced by alternative substances such as lidocaine, because of the allergic
reactions it causes. Further pharmacological and pharmaceutical knowledge, provided a variety of anesthetics with differences in effectiveness time and quality, each suited for all needs. Principles for administering anesthesia, usually require a great knowledge of the anatomical topography of the oral cavity, as the targeted site are the nerves, or their endings that supply the tooth or teeth of interest. It is a dangerous procedure if it is not done carefully, because permanent damage may be caused on nerves or other important structures of the oral cavity (20).
2.5 Dental Chair With the electricity in the arsenal of technology, every idea could be utilized. From
Figure 6 An old dental chair with the manual footpedal that makes the drill rotatae (Source: Dental Chairs Through History)
electric drills, to being able to see under ones skin without cutting it. Chemistry plays a significant role, into the development of materials used, as they become better and easier for dental practitioners and patients to handle, as well as more efficient.
In an effort to modernize dentistry, the idea of drilling came to an Italian surgeon, Giovanni de Vigo, who introduced his theory of drilling the carious tooth structure. The teeth were filed and manually drilled and it has little relation to what we’ve all experienced, in our more modern approach. The rapid developments in technology allow us to have a completely different day when visiting the dental clinic. The first drill supported dental chair was developed in the 1790s, by John Greenwood, an American pioneer of dentistry (21) (22). The drill was moving by a spinning wheel that got the motion from a rod that was attached to a foot pedal. However this went obsolete by the creation of the electric dental chair 80 years later by George F.
Figure 7 A modern complete dental chair (Source: Trade Get)
Through a series of developments, a list of companies has been created, which produce and distribute the dental chairs worldwide. This brought us to the point where the dental chair is equipped with hydraulics for various positions ranging from normal, upright, sitting position to
supine and even Trendeleburg position, providing comfort to the patient and also to the dental staff, as they are able to maneuver the chair to fit any case that may occur. Since the chair is electric, it must be connected to a power source. It is modified to the standards of voltage according to the current in ones country. Besides using electricity for patient positioning, it is needed for powering up the turbine, micromotor, ultrasonic scaler. Air and water are important components of the chair too as air and water are pressurized through the triple syringe, where pressure usually ranges from 500 Pa – 800 Pa and water pressure from 200 Pa – 400 Pa (23). In most cases, the patient must not or is unable to swallow. From cases like these, the need for suction and a spittoon has emerged. In most dental clinics, two types of suction tubes are used: one which is placed and over the lips of the patient and the other which is need for instruments, usually held in the oral cavity of the patient by the dental assistant (23).
2.6 X-rays and Radiography In 1890s, physicists were experimenting with electromagnetic waves, many have observed the effect, but the one who studied them extensively and was able to explain fully was Wilhelm Roentgen. X-rays get the letter X for being unknown at that time, even though many refer to them as Roentgen rays. The wavelength of this electromagnetic wave ranges from 0.1 – 10 nm and what was observed at the experiment days was that this wave could pass through solid objects and produce an image of their interior (24) (25). X-rays are classified as a carcinogen) thus extensive radiation is dangerous for the human body, so it must be monitored and regulated not to exceed certain levels of radiation according various factors concerning the person under exposure all according to radiological protection centers that a country has. Over the years, the new capabilities of this type of radiation were introduce to many aspects of medicine. Therefore, dedicated x-ray units and their related equipment for dental purposes have been in the market for quite a long time now.
Figure 8 A digital x-ray apparatus for the dental office (source: The Mathews Dental)
These devices can be mobile or fixed in place usually according to the degree of theiremittion and their size. In a standard dental x-ray machine, which is in the same room as the personnel, there is a film that contains light receiving components, which will be exposed to the x-rays after they passed through structures, we have a tubeheadthat contains an anode and a cathode, which allow the current to flow, a copper block and oil used for removing generated heat, a focusing device that aids in targeting and lead, surrounding all structures, which facilitates in absorbing radiation emitted in unwanted directions. The tubehead is placed in position with arms of various designs, and the whole process is controlled by the control panel with the different buttons it contains, to optimize the procedure according to the patient needs (24).
The x-ray unit is generally used for a segment of the oral cavity, as opposed to the orthopantomogram that is used for the whole oral cavity. Most typical methods of imaging, intraorally, are the periapical radiography and bite-wing radiography. The periapical radiography shows up to 4 neighboring teeth, both their crowns and roots, and also the surrounding tissue such as the alveolar bone. The bite-wing technique is used for projecting crowns of upper and lower premolars molars, on either the left or the right side of the dentition. Extraorally, imaging methods are generally used for projecting the jaws and parts of the skull (26). The orthopantomogram is an x-ray device used extraorally, for projection of all the teeth and many adjacent structures, such as the jaws and lower parts of the skull. Through a combination of two or three moving centers of rotation, or one stationary center, the device moves into elliptical movements while projecting x-rays. In some cases the image is segmented into points of interest only, in other cases it is full image. For a successful orthopantomograph, it is important that the patient is positioned well and remain still, so the jaws will remain in the focal trough, the field in which the beam provides maximum imaging quality (26). After a film has been exposed, its processing takes place, in order to produce the picture. The parts of the film that became exposed to x-rays are converted to black metallic silver, during emulsion and will produce the black and grey parts of the image, which will represent nothing such as air, or the softer tissues such as mucosa. Those that didn’t become exposed will be removed, leaving a white- transparent part, which will represent the more solid tissues such as teeth or bones. The final picture is viewed when placed on a negatoscope, a machine that produces abundant fluorescent light (26).
Figure 9 An orthopantomogram (Source: BJr Journals)
2.7 Filling materials There is a great variety of filling materials in the 21st century, which from being extremely hard and time consuming to use, due to the fact that they required a mixing, a few minutes to set, or were unreliable, have evolved and improved greatly and now a denal practisioner is able to target each occasion more specifically, For a filling material to be favored, wether it is a crown filling material of or root filling material, there are some requirements that it should fulfill in order to help both the patient and the dentist. Requirement like being easy to use, being tooth colored and preferably adhesive to the tooth’s substance . An ideal filling material should also be strong and have minimal dimensional changes on setting as it may fracture the tooth or may create a gap between the tooth and filling and bacteria may easily colonize that gap, and also resist to formation of dental plaque. An ideal feeling shouldn’t be toxic or irritant to pulp and gingival tissues and it should be insoluble and non corrodible in mouth and ideally, it should absorb water, as there is high humidity in the mouth. Asides being easy to use, It must
also be easily shaped and polished.ow water absorption. Finally it must be radiopaque, to be easily differentiated on x-rays and cheap.
2.7.1 Amalgam Amalgan is a type of feeling material that does not adhere to the tooth’s structure the tooth should prepared further for the amalgam to retain. It is not tooth colored so it will not be esthetic on the anterior teeth. But amalgam is the strongest filling material, when the ingridients of it are proportioned correctly, so it is generally used in the posterior teeth, which they undergo the great force of mastication. It is also used in cases where the filling close to the pulp, as it is not toxic to it, but it is not the only option. Amalgam should not be used when a restoration made of gold is near the tooth to be filled, as amalgam reacts with gold (4) (27). The main ingredients of the amalgam filling are mercury, silver, tin, copper and zinc and
Figure 10 A Black Class 2 amalgam filling on an artificial dentition, with the use of a matrix and a matrix retainer (Source: Columbia Edu)
their proportions are different according to their manufacturer and needs, as different compositions changes the filling’s properties. In the old days, the mercury was supplied in a bottle of liquid and the rest of the ingredients, as powder and they were mixed just before the filling application. Nowadays, there is a machine called amalgamator and it is responsible for mixing the amalgam, which is supplied in a capsule that contains all the ingredients inside. Before the application of this specific material, the dentist should not only remove the lesion on the tooth, but he should prepare a cavity suitable for amalgam, this cavity ideally is box- shaped, therefore all the walls and the floor have a ninety degree angle between them, making them parallel. After the filling has been applied, polishing is necessary in order to make the filling smooth and reduce plaque accumulation and also it helps the material to give the maximum of its capabilities (4) (27). Because of the fact that an ideal filling material is supposed to be non toxic, there is a huge controversy over this filling material and whether or not it should be used, because it contains mercury. No solid evidence exist though, that prove that this filling material is dangerous to the patients, but even like this some countries have banned the usage of this filling material, and in all countries whether the material is banned or not, they follow very strict laws, in correct use and dispossal of mercury (27).
2.7.2 Composite Composites are modern, esthetic dental restorative materials, which by themselves are unable to adhere to the dental hard tissue and therefore they are added after separate adhesion. A composite filling consists of filler particles distributed within a continuous phase of resin matrix, and also various other substances which are responsible for preserving the material, for example initiation of setting, increasing of shelf life, radiopacity. This material is better than other material on the fact the they have the highest creep resistance, as well as wear resistance. Once cured, it matures, therefore polished immediately (28).
Figure 11 A composite resin kit with various shades, and adhesives (Source: Top Dental Composite Resin Kit)
2.7.3 Glass ionomer cement Glass ionomer cements are tooth colored permanent or temporary filling materials which consist of ion crossed linked polymer matrices, which surround glass reinforced filler particles. They are divided into water based and non water based, non water based are acida based. Water based cements consist of an aluminosilicate glass with a high fluoride content which acts as reservoir of fluoride release, something very helpull agains demineraisation. Glass ionomer cements are divided into light- cured cements, those that set with uv light and auto cured cements, those that set after a series of chemical reactions. Cements with both curing methods exist also, the dual cured. When a glass ionomer cement cures it needs approximately seventy two hours to final maturation, therefore the polishing is not done after the filling application (29).
The glass ionomer cement is able to adhere to dental hard tissues, but it is not a durable as other filling materials, therefore it is preferred when the preparation of the tooth to be filled is
very small and it is not under heavy functional occlusal load. Also the glass ionomer cement it is not toxic or irritating to the pulp after it has set, but during application and setting it might be a bit irritating something which will heal very fast (29).
2.7.4 Gutta-percha Gutta-percha is one of the many root canal filling and it is the one used more commonly. A root canal filling in general has to have the same requirements as a crown filling, but what is more tricky in this situation, is that it must be able to adapt any curvature a root canal might have and gutta-percha has been the best at this for a very long time, something nearly impossible for metal fillings. It is until today although many practitioners tend to prefer root canal filling materials which are less solid, and thus easier to deploy in the root canal system (30).
Figure 12 A two bottle – power and liquid glass ionomer cemnt (Source: Ksenchi Blogspot)
Figure 13 Gutta – percha points in different sizes (Source: SybronEndo)
2.8 Typical filling procedure First the caries lesion must be removed, this is done with big round burs on micromotors with very slow rotating speed. If the selected filling material is an amalgam, then the appropriate measures described earlier, must be taken in order for the filling to retain. The working field should be dry and after mixing of the materials which require mixing, adhesives are applied to the surface if necessary and then the filling material is placed (31).
Figure 14 Atypical filling procedure with its stages (Source: Know About health)
2.9 Typical endodontic procedure
An endodontic procedure, involves entering the pulp chamber and removing the dental pulp. The root canal is continuously disinfected and the canal cavity expands incrementally, in respect to the canals curvature. After the canal cavity is expanded to the desired diameter, a root filling is fixed and it is critical that it does not exceed the apical foramen on the apex of the root. After successful root canal therapy, the crown is being restored either by an ordinary filling or another restoration (32).
Figure 15 A typical endodontic procedure, when diagnosis is made, trapantion to he pulp chamber, removal of the damaged dental pulp and expansion of the root canal cavity and root canal filling (Source: Wikipedia)