Definitions and Descriptions

The dental pulp is a tissue that can suffer, up to the point of loosing vitality. The most frequent cause is the caries which, during its progression inside the tooth, may reach the pulp and damage it causing necrosis. But the caries is not the only factor causing pulpal trouble: there are other various possibilities. The tooth could find itself in an unfavourable biting situation, and suffer from traumatic contacts with other teeth, sometimes in a way so intense to cause an inflammation of modest entity that can degenerate in a non reversible pathology. Also the uncovering of the dental neck (the part next to the gum) may result in a thermic hypersensibility which, in its most severe form, leads to irreversible pulpitis.

a) Symptoms

Whatever the cause, when a dental pulp enters an inflammation phase, the same as in any other part of the body happens: a greater quantity of blood rushes into the tissue. The peculiarity of the dental pulp, however is that this increased blood quantity does not cause the tissue to swell, because this is impossible. The pulp, as a matter of facts is situated inside a rigid structure (the dental walls) and has thus no possibility to expand, so that it swells towards its inner side and compresses the nerve in a very heavy way. As a result the inflammations of the pulp (=pulpitis) are extremely painful: the classic tooth aching is one of the worst pains that can be experienced!

b) Pulpitis

The compression of the nerve inside the tooth causes a status of pain and signals an inner issue. Within certain limits, this pathology can show up in a low intensity and show itself as a high sensitivity to thermic stimuli. In a sense, the pulp is able to compensate irritation effects, but of course only within certain limits. Once trespassed a given boundary, the pulp is no more able to compensate and gets ill in an irreversible way.

The pulp begins to be continuosly aching, it generates intense twinges and a pulsating pain which is unbearable. At this point, the pulp has no more recovering possibilities and must be removed: the tooth has to be devitalized.

c) Pulpal necrosis

The next phase in the pathology is the cellular death of the pulp and ceasing of its vital functions. At this point the tooth becomes a sort of bacterial tank, being colonized in its inner part by microorganisms producing dangerous toxines, progressing to the roots' exit, through the apex.

d) Abscess, fistula, granuloma, cyst

The flux of bacteria out of the dental apex causes a reabsorption of an osseous area around the apex, or a cavity in the bone itself. Basing on the infection's virulence, the bone can be reabsorbed up to its surface, perforating to the outside and having the gingiva swell in a classic abscess. This acute form is accompanied by pain and, occasionaly, by fever, but can also be limited to the swelling only. in some cases the perforation stabilizes and becomes an open canal linking the abscess to the mouth environment. this structure is a fistula. The tooth can stay in stand by this way even for years, without the osseous cavity getting larger, and even with the patient having no conscience of its existence. The fistula indeed, often appears like a small bubble giving no symptoms and draining to the outside the contept of the osseous cavity mixing it with saliva and food.

The abscess however is all in all a rather rare event: more frequent is the formation of a stable osseous cavity of chronic nature: the granuloma.

Even if from time to time the granuloma may provoke acute abscess episodes, it generally stays still. Sometimes the patient becomes conscious of its presence because the tooth giving it birth, becomes sensitive to chewing and to pressure.

The pain is typical because it can be easily located.

In specific phisical conditions, granulomas of older age may evolve into cysts. The cyst distinguishes itself from the granuloma because it has a periferic epithelium encircling the cavity and because it has a very defined radiological appearance. It can be assessed that a cyst does not hold bacteria, however this is a relatively unimportant feature. The most important fact is that a cyst very often does not receed with the mere removal of the bacterial charge from the tooth (root canal treatment) and has to be treated surgically.

This is a procedure (often executed in urgency, while the tooth is in acute pulpitis), by which our aim is to medicate the tooth in a way to free the patient from pain. in its various version, it always comprehends a build up and restoring of the lost tooth's volume (if it is a caries causing the problem) by means of a more or less permanent restoration, and the most deep removal of the dental pulp. The tooth is then left "empty" in the sense that in its inner space there's no vital tissue anymore.

The canals

Every tooth has canals inside its roots, normally containing the pulp. The number of canals is variable according to the tooth and is anatomically bound to the number of roots. From a minimum of 1 up to 4 canals can be found, but also 5 canals can be observed, or a lower number of canals with more complex shapes.

Another important characteristic of the canals is that they often branch in many tiny smaller canals in proximity to the root's apex, like a river's delta. This peculiarity is the cause for the low cleaning procedures effectiveness in that segment.

The root canal treatment has the aim of completely removing the dental pulp from all the internal canal system. This removal is a guarantee for the bacterial charge, always present, to be removed or so drastically reduced to result in complete harmlessness. To execute this task, an access cavity is cut through the tooth and, having reached the canal's entrance, tiny metal tools are introduced which act like scrapers, designed for tissue removal and contemporary canal diameter enlargement.

a) Endodontic instruments

Hand driven or rotating instruments, called files (made of steel or Nickel-Titanium) are employed. According to the preferred technique used, they're alternated or used alone. There are various designs for these instruments, each one studied to have certain cutting capabilities, adapting to different situations. Every professional applies the instrumet system he knows better or which has the best known characteristics.

b) Apex locator

This is an electronic appliance used by the dentist to measure the lenght of the tooth starting from a reference point on its crown, down to the apex. This is obtained by inserting a thin instrument into the canal, at the beginning of the work and connecting it to the sensor. The tool gives back a reading of the electric resistance along the canal and warns the operator when the file reaches the apex, or canal exit. The measure found will be taken as the workout measure to execute the canal treatment. While doing the job, from time to time, the dentist may have the need to repeat the measurement to better check it, also because in curved canals, the enlargenment of the same, causes the shortening of the working distance, because of the straightening of the curve.

The measure found with this appliance is valid in most of the cases, but some machines are more influenced by -for example- the presence of fluids in the canals. This piece of information is therefore continuosly cross checked with others, like the paper cone drying test.

c) Canal preparation

Besides the instrument used to clean and enlarge (= prepare) the canal, it's nowadays accepted that the workout form we wish to obtain, is a sort of inverted cone with open apex. This means that the thinner file will be assigned to the cleaning of the root's canal exit (apex), the thicker ones are being used stepping back from the apex, more and more towards the tooth's crown. The files always work while bathing in a liquid solution thought to dissolve organic residuals: the most used is sodium hypoclorite (bleach).

d) Canal obturation

The conic shape of the canal has the aim to facilitate its obturation. The canal is sealed with small sticks of Guttapercha. This is a thermoplastic substance: it has the characteristic of getting deformed when being warmed, and of holding the given shape when it cools down. It practically acts like a wax, even if chemically it is not.

This material is manifactured in small sticks of conical or cylindrical form, but anway fit for the given canal preparation. To seal the canal itself, the Gutta cones are heated and pushed down into the canal until they reach the apex, where they are stopped and cooled down, obtaining the root's sealing. This technique is called vertical condensation, and can be performed with hand instruments or, more recently with specific appliances that heat and compress at the same time.

However it is performed, the canal obturation has the aim to obtain the sealing of the last 3-4 mm of the canal. A canal obturation looking shorter than the root in the X-ray control, does not indicate a failure inso much as the canal's exit (anatomical apex), often is not coincident with the root's tip (radiological apex).

Also, an eventual modest cone excess out of the canal does not imply a healing disturbance, because of the biological neutrality of the materials being used.

Whatever the reason that lead to canal treatment, the result will be the healing of the tooth in 95% of the cases, with the reabsorption of the granuloma, along with the healing of the fistulas. Practically what happens is that the elimination of the bacteria causing the problem, will put the body in the best condition to restore health.

In a small percentage of the cases though, the canal treatment may not reach the hoped result. This may depend from the anatomical variabilty of the inner canals. Not rarely they have "delta" shaped diramations that may hold a certain bacterial quota and slow down or prevent the healing.

In those cases in which the normal canal tratment procedures did not reach the hoped effects, and at the condition they have been done correctly, those are the cases in which the peculiar anatomy of that tooth or of that specific canal, do not consent a reasonable canal cleaning or sealing. Some bacterial charge is left in some microscopic part of the apex, enough to maintain the illness. The cause may reside in the invisible presence of small lateral canals or inner connections between canals in the same root and so on. If the cure has been performed with the highest level possible but the lesion does not receed, there's one alternative left: endodontic surgery or apicectomy.

It substantially consists in reaching the root's apex through surgical path, by means of a small incision through the gum, and the cutting of the root with subsequent removal of the apex itself. This way, all eventual bacterial charges potentially present in that root segment, those that could not be cleared with the canal treatment, are eliminated.

Once having the apex cutting done, a retrograde obturation of the root is performed, in the opposite direction of the canal treatment, that is. In other words, the new apex of the root is sealed permanently.

Once executed the surgery, progressive healing of the lesion follows, together with the bone growth. The complete radiological disappearing of the lesion, can span from a few months up to one year in the most severe cases.