ENDODONTICS
DENTAL PULP DISEASE
The dental pulp is a living tissue that can become ill and lose its vitality. The most frequent cause of this is dental caries which, in its progression of excavation inside the tooth, can reach the pulp, damaging it up to necrosis. But tooth decay isn't the only factor causing pulp problems - there are various other possibilities. The tooth can be placed in an unfavorable chewing situation, and undergo traumas from contact with the other teeth, sometimes in such an intense way as to initially cause a modest inflammation, which can however degenerate into a non-reversible pathology. Even an uncovering of the tooth neck (the part near the gum) can give thermal hypersensitivity which in the most severe form leads to irreversible pulpitis.
a) SYMPTOMS
When for any reason the pulp of a tooth enters the stage of inflammation, exactly what happens in other parts of the body happens: more blood flows into the tissue. The peculiarity of the dental pulp, however, is that this greater amount of blood does not cause an increase in tissue volume, as this is not possible. The dental pulp is in fact enclosed within a rigid structure (the walls of the tooth) and has no possibility of expanding, so it swells inside and compresses the nerve very heavily. This fact makes the inflammation of the pulp (= pulpits) extremely painful: the characteristic toothache is in fact one of the strongest pains that can be experienced!
b) PULPITIS
Compression of the nerve inside the tooth is the cause of pain and is symptom of an internal problem. Within certain limits, this pathology can show mild forms, and manifest itself as a high thermal sensitivity of the tooth itself. In a sense, the dental pulp is able to compensate for the effects of irritation, but of course within limits. Beyond a certain threshold, the pulp is no longer able to compensate and becomes irreversibly ill.
The pulp begins to be continuously painful, generates very intense twinges and an unbearable throbbing pain. At this point, the pulp has no more chance of recovery and must be removed: the tooth will be devitalized.
c) PULP NECROSIS
The next stage of the pathology is the cellular death of the pulp and the ceasing of its vital functions. At this point the tooth becomes a sort of bacterial reservoir: they colonize the inside and develop dangerous toxins, progressing towards the exit of the root through the apex.
d) ABSCESS, FISTULA, GRANULOMA, CYST
The escape of the bacteria from the apex of the root causes a resorption of a bony area around the apex of the root, a cavity in the bone itself. Depending on the virulence of the infection, the bone can reabsorb up to its surface, perforating outwards and causing the gum to swell in the classic abscess. This acute form is accompanied by pain, and occasionally fever, but can also be limited to swelling alone. In some cases, the perforation stabilizes and becomes an open channel that connects the abscess with the mouth. This structure is the fistula. The tooth can stabilize in this way even for years, without the bone cavity enlarging, and even without the patient being aware of its presence. In fact, the fistula often appears as a small bubble that does not give any symptoms and drains the contents of the bone cavity outside mixing with saliva and food.
However, the abscess is an all in all rare event: more frequent is the case of the formation of a stable and chronic bone cavity: granuloma. Although the granuloma may flare up into an abscess at times, it is generally stationary. Sometimes the patient becomes aware of it due to the fact that the tooth that generated it becomes sensitive to chewing and pressure. Pain is characteristic because it can be easily localized.
Particularly stable granulomas, if long-standing in particular physical conditions can evolve into cysts. The cyst is distinguished from the granuloma because it has a peripheral epithelium that delimits it, and for the radiographic image with very sharp edges. It is sometimes said that the inside of a cyst does not contain bacteria, however it is a relatively minor problem. The truly remarkable fact is that unfortunately a cyst often does not regress with the removal of the bacterial load from the tooth (root canal treatment) and must be surgically removed.
DEVITALIZATION
It is a procedure (often performed urgently while the tooth is in acute pulpitis), aiming at medicating the tooth in order to free the patient from painful symptoms. In its various versions, it undoubtedly includes a temporary restoration of the volume of the tooth (if the cause of the problem is a caries) with a more or less permanent filling, and the removal of more dental pulp as possible. The tooth is left as it were "empty" in the sense that there is no more vital tissue in the internal space.
CANALS
Each tooth has canals within its roots that normally contain the pulp. The number of canals varies according to the tooth, and is anatomically related to the number of roots. You can find from a minimum of 1 canal to a maximum of 4, but even 5 canals are rarely observed, or less numerous canals with complex shapes.
An important feature is that the canals often end in numerous lateral branches near the root apex, such as a river delta. This particular configuration is sometimes the cause of problems due to the scarce possibility of cleaning in these areas.
ROOT CANAL TREATMENT
Root canal treatment aims at the complete removal of the dental pulp from the entire internal system of its canals. This removal ensures that the ever present bacterial load is totally removed or so drastically reduced as to be ultimately harmless. To perform this operation, an access cavity is made through the crown of the tooth and, having reached the entrance of the canals, thin rods are introduced inside, which are nothing more than scrapers, suitable for removing the tissue and for simultaneously enlarging the inner diameter.
a) ENDODONTIC INSTRUMENTS
There are hand-held and rotating instruments (in steel or nickel-titanium). They are used (depending on the preferred technique) alone or alternating together. There are various designs for these tools, each thought to have certain cutting characteristics to suit different situations. Every professional applies the tool system with which he has the most experience or whose characteristics he knows best.
b) APICAL LOCATOR
It is an electronic instrument used by the dentist to measure the length of a canal from a reference point on the crown to the apex. This is achieved by inserting a thin instrument into the canal at the beginning of the preparation and connecting it with the sensor. The device gives a reading of the electrical resistance along the canal and warns the operator when the instrument reaches the outlet (apex). The measure will be held as working length to perform the root canal treatment. During processing, the dentist may sometimes want to repeat the measurement to better check it again, also because in curved canals, the widening of diameter shortens the working lenght, due to the straightening of the curvature.
The measurement found with this instrument is valid in most cases, but certain localizers are more influenced, for example, by the presence of fluids in the canals. This data is therefore continuously crossed with others, for example drying with paper cones.
c) APICAL PREPARATION
Aside from the tool used to clean and widen (= prepare) the canal, the theory currently accepted is that the final shape to be obtained must match a sort of inverted cone with open apex. This means that the smaller instrument is used to clean the canal exit (apex), the larger ones are gradually used. moving away from the apex towards the crown of the tooth. The instruments always work in a bathing in a liquid dissolving organic remains: the most frequently used is sodium hypochlorite.
d) CANAL FILLING
The conical shape of the preparation is intended to allow its filling. The canal is in fact closed with heated sticks of gutta-percha. This is a thermoplastic substance, meaning it can be deformed when it's heated, and it keeps its shape when it cools. It behaves roughly like a wax, even though chemically it is not.
This material is packaged in conical or cylindrical rods, suitable to match the shape of the root canal preparation. To seal the canal itself, the gutta cones are heated and pushed into the canal until they reach the apex, where they are blocked and cooled, obtaining the root seal. This technique is called vertical condensation, and can be performed with hand instruments or, more recently, with special devices that heat and push at the same time.
In any way the canal filling is performed, the aim is to obtain the seal of the last 3-4. A possible root canal obturation that appears shorter on the X-ray does not indicate a failure as often the exit from the canal (anatomical apex) is not coincident with the tip of the root (radiological apex).
Furthermore, a possible leakage of the cone from the canal (provided it is modest) does not generally imply a disturbance to healing, due to the inertia of the materials used.
HEALING
Whatever the reason that led to root canal treatment, the result will be in 95% of cases the healing of the tooth, and the resorption of the granuloma, in addition to the closure of the fistulas. Substantially, what happens is that by eliminating the bacteria that cause the problems, the body is put in a position to be able to restore health.
In a small number of cases, however, root canal treatment may be not successful. This may be due to the anatomical variability of the internal canals. Quite often they have "delta" branches, with lateral microchannels that can retain a certain amount of bacteria and delay or prevent healing.
APICECTOMY
If root canal treatment maneuvers do not have the desired effects, and provided that they have been performed correctly, it follows that the particular anatomy of that given tooth, or that particular canal, does not allow sufficient cleaning or sealing. Therefore, in some microscopic apical root area, there is a bacterial load enough to keep an illness going. The cause can be identified in the invisible presence of small lateral canals or internal connections between canals of the same root, etc. If root canal treatment has been performed at the highest possible level, but the lesion does not heal, an alternative technique can be applied: endodontic surgery or apicoectomy.
It basically consists in surgically reaching the root apex through a small gum incision, allowing to cut it off the root, with simultaneous cleaning of the infection body. In this way, all possible and potential bacterial loads still present in that part of the root, are eliminated.
Once the root has been cut, a retrograde obturation is carried out: a filling performed in the opposite direction to root canal treatment. In other words, the new apex of the root gets sealed permanently.
Once the operation has been performed, the progressive healing of the lesion follows, with the simultaneous formation of the bone. The complete disappearance of each lesion at radiographic check, occurs in a period of time spanning from a few months to a year in particularly difficult cases.