CONSERVATIVE DENTISTRY
DENTAL CARIES
Caries is probably the most common disease in humans, so much so that the people who are affected (at least in Western society) are the majority of the population. The mechanism of caries formation is relatively simple.
Plaque bacteria, particularly some species, metabolize sugars and release a by-product: lactic acid. The action of lactic acid on the enamel causes a corrosion of the surface, which first decalcifies (white spot or white spot) taking on a chalky appearance, and then crumbles causing the formation of a small notch in the surface of the tooth. Plaque proliferates within this notch and thus begins to make its way into the enamel.
In its progression inside the crown of the teeth, the caries digs a cavity of ever greater dimensions, getting closer and closer to the dental pulp, that is to the vital part of the tooth. At the same time, the tooth structure is also weakened and partial crown breaks can occur. Most cavities aren't actually bad at all. This statement may seem surprising, but it is actually the result of a slow evolution: those species (and those individuals within a species) that have a certain adaptability of their pain threshold are certainly favored: man too. has developed this particular ability, so that many cavities can be present at the same time without actually having any symptoms. In fact, a tooth that hurts probably has cavities, but a tooth that doesn't hurt could still be hiding one. For this reason, a periodic check-up by your trusted dentist becomes important.
One thing to note is that tooth decay is a multifactorial disease, meaning it doesn't actually have a single cause. We now give a summary of the causes and factors that favor it.
a) BACTERIAL PLATE
Bacterial plaque is a conglomeration of carbohydrates (sugars) and proteins that come directly from nutrition and that mix with the bacterial flora of the mouth. Plaque is not present in the fetus, so it is acquired from the environment after birth. It has been shown that in the absence of bacteria a plaque from food residues develops, which however does not cause tooth decay: consequently, without bacterial plaque there is no disease. (see also "hygiene and prevention")
b) SALIVA
The characteristics of viscosity, acidity and consistency of saliva are hereditary and certainly have their influence in the so-called self-cleansing of plaque, but they cannot be influenced in any way.
c) ENAMEL AND DENTINE
The resistance of the enamel and dentin of a tooth are also herditary characteristics, but they can be improved by the action of fluorine taken in general with the fluoroprophylaxis of childhood. However, there are basic teeth that undoubtedly have a greater resistance to the action of caries than others.
d) POWER SUPPLY
Since plaque bacteria feed on sugars and carbohydrates, a diet excessively rich in these substances favors the formation of cavities. The intake of fibers (in particular vegetable fibers) can, on the contrary, help cleanse the teeth by rubbing the tooth surfaces. The type of diet recommended for prevention is therefore balanced and rich in fiber - which, among other things, is true in many other medical situations, but in general as a rule of good health.
DENTAL FILLING
Conservative dentistry deals with repairing the damage caused by caries, removing the caries itself and replacing the part of the lost tooth with a material called "filling".
In a certain sense, therefore, from caries it is not "healed" because the lost enamel and dentin cannot be regenerated and the tooth never returns to the way it was before.
the materials and modern filling techniques, however, allow a reliable repair and a restoration of function practically perfect original.
Anesthesia
First, the most suitable anesthesia for the specific case is applied to the patient. (see dedicated section for details)
Dam assembly
In all cases of obturation, the use of the dam is mandatory, but in an even more rigid way if it is a question of making a filling with aesthetic material (composite resin or composite): this is for the reason that these materials are very affected by humidity. , losing most of their adhesive capacity if not applied in a dry field. (see dedicated section for details)
THE RUBBER DAM
It is a latex sheet (or vinyl for allergy sufferers) on which small holes are made. The tooth to be treated, often together with the neighboring teeth, is so to speak "jacketed" by passing it through these holes. The fixing to the teeth takes place through a metal hook which, by embracing the tooth near the collar, prevents the dam from rising. The latex sheet is then held taut by a frame of various shapes. In this way, the sector of teeth on which it is necessary to operate is isolated from the internal environment of the mouth: this allows greater visibility to the operator, a slight compression on the gum so as not to interfere with the work, the absence of humidity in the field surgery, the advantage of not having to continuously rinse the patient.
The rubber dam is strictly applied in all cases of obturation (conservative dentistry), in root canal treatments (endodontics) and in any case in all cases in which it is possible to apply it.
It should also be emphasized that the adhesive procedures (gluing) that are widely used in dentistry now absolutely require the use of the dam, otherwise the adhesion power of the fillings is considerably reduced, partially compromising their success over time.
In the scientific and clinical environment, the failure to use the dam in all cases where it is not only possible but necessary, is now considered a technical deficiency!
PREPARATION OF THE CAVITY
Removal of caries
Caries is removed from the tooth by means of rotary cutters mounted on turbines or micromotors, or with hand tools called excavators. Carious tissue should be removed until it can be distinctly separated from healthy dentin. Some types of very sharp excavators are roughly calibrated to healthy dentin, meaning that they cannot remove it, thus allowing the dentist to stop the operation at the right point.
Finishing the cavity
The cavity that was produced with the eradication of caries, needs a shaping, which can always be performed with rotary instruments or by hand. The aim is to give the enamel walls a clear and homogeneous surface more suitable to accommodate the filling material. Depending on whether the filling is performed with composite resin or amalgam, the type of finishing and shaping of the cavity can vary greatly.
COMPOSITE FILLING
The composite resin is a paste of plastic material that has aesthetic characteristics, and is able to physically stick to the tooth. The bonding procedure involves the application of a series of chemicals that serve to prepare the surface of the cavity to receive the filling.
The choice of shade obviously takes place by observing the tooth and trying to harmonize the composite with the remaining structure. This is not always an easy task, because the composite has different light refraction and reflectance characteristics than the tooth, however a dentist with a fair amount of experience and with a good knowledge of the product he uses, can obtain satisfactory results.
a) ETCHING
The first substance that comes into contact with the finished dentin and enamel is an acid which serves as a conditioner (usually 37% orthophosphoric acid): it has the function of roughening the surfaces and allowing subsequent substances to cling. It is removed after its action with a short jet of water.
b) MEMBERSHIP
Depending on the product used, you will then have a Primer, which is a substance in charge of creating a connecting layer between the tooth and the resin: in fact it is a substance capable of microscopically infiltrating the prepared surface and binding to the layer. following. Finally, Bonding is used, which is nothing more than a transparent fluid resin: it could also be considered as the glue of the filling.
It should be noted, however, that some brands of filling materials offer all these steps in one vial: they are so-called "one step" adhesives. The individual dentist chooses the best product based on published studies and his experience.
c) FILLING
The actual (composite) filling material can be contained in tubes called syringes, or in capsules mounted on special guns. In any case, it is brought into the cavity in a progressive quantity: that is, it is stratified. This occurs above all to minimize a particular undesirable effect that all composites exhibit, namely polymerization shrinkage.
In essence, it is the fact that while the material hardens, it undergoes a contraction in volume: if this is excessive, it can cause a micro detachment from the cavity walls, too small to be noticed immediately but large enough to infiltrate a new caries.
d) POLYMERIZATION
The hardening of the composite takes place by subjecting it to the light of a particular lamp that emits a light beam at a certain precise intensity. The minimum intensity is considered to be 550 mW / cmq: below this power it cannot be guaranteed that the composite hardens appropriately.
e) FINISHING
The final stage of filling involves removing the wedge, matrix and dam. At this point the so-called occlusal check is carried out: that is, the chewing dimensions are checked, that is, if the patient, closing his mouth and making his teeth match, first "touches" the reconstructed tooth. With the cutters, the necessary retouching is carried out and the polishing phase is carried out, which can be carried out with pastes, brushes or rubber pads. At this point, the filling is complete.
AMALGAM FILLING
Dental amalgam is a filling material made from a metal alloy that has existed for over 100 years and has excellent durability and stability characteristics.
Its high mechanical characteristics make it possible to carry out extremely extensive dental reconstructions (see figure), but certainly its use requires particularly careful manual skills.
We will not discuss its alleged toxicity here, however it is in fact a perfectly usable material, as far as is said. A massive media campaign against amalgam has developed in recent years, blaming it for the most disparate general diseases.
However, from a medical and statistical point of view, nothing has been proved.
The enormous quantity of amalgam present in the world population, if anything, proves the absolute safety of the material.
However, one of its peculiar characteristics is that it does not adhere to the tooth cavity in a chemical / physical way like the composite. It is therefore only a filler, even if the seal is probably almost perfect.
It was abandoned mostly due to its poor aesthetic qualities and the greater reliability of modern composites.