The Advantages of a Room Temperature Obturation Technique

From a practical point of view, a big advantage of room temperature obturation techniques is saving a lot of money. Those thermoplastic systems including injecting flowable gutta percha, softening a gutta percha point already placed, or carrier based are all expensive including the heating unit, and the heated gutta percha in the case of carrier based systems. The premium one pays should bestow benefits that obturate the canals better, conclusions not reached by a large body of research. On the contrary, as common sense might guide us, all thermoplastic systems lead to shrinkage after the placement of what was flowable gutta percha cools to body temperature. Shrinkage is synonymous with leakage and should not be part of any endodontic techniques we are employing. Furthermore, thermoplastic systems can easily generate excess heat that damages the periodontial ligament if applied for longer than 3 seconds, narrow confines within which to operate.?

?So, if you are using a room temperature technique that I suspect most dentists employ you should already feel better. Once we think in terms of room temperature obturation techniques life becomes a lot simpler. No fancy heating devices and no expensive carrier based points. The key to successful room temperature obturations is first based on a canal preparation that has removed at least enough pulp tissue and bacteria to tilt the repair process to one of resolution. Given what is at times the highly oval nature of canals with a completed cleansing process that maintains that original anatomy in larger form, we can expect a fitted gutta percha point determined by noticeable tugback to come from an intimate mesio-distal fit with what may be a good deal of space being present buccally and lingually. That is not a problem.?

Once we have a point fitted accurately in the mesio-distal plane, we set it aside and flood the canal with sealer using the bidirectional spiral, an application tool where the coronal spirals drive the cement apically while the most apical spirals drive the cement coronally preventing it from extruding beyond the apex. This instrument is applied no closer than 3 mm from the apex preventing any chance of binding and separating as it rotates within the confines of the canal. The canal is now well coated with sealer along its length save the last couple of mms. The prefitted gutta percha point is now generously coated with cement and placed to length and seared off at the level of the orifice.

What have you accomplished? Between the application of the cement within the canal and that applied to the gutta percha point, plus the gutta percha point itself, we are introducing a volume of material greater than the volume of the canal space. Obviously, excess gutta percha is not going to extrude coronally, but the excess represented by the highly flowable cement will, but not before it is directed apically in three-dimensions into an intimate fit with the canal walls. By employing this method a single gutta percha point combined with the highly flowable cement produces three-dimensional obturation.?

In years past, anything but the thinnest layer of cement as an interface between the gutta percha and the canal walls was unacceptable because the cements used at the time were what we call particulate in nature, highly susceptible to dissolution by any fluids that might be present. Dissolution is a vicious cycle leading to increasing amounts of dissolution over time and calls for preventative steps which is where lateral condensation comes in. By laterally and perhaps vertically condensing the gutta percha point, it was reasoned that the cement interface would be thinner leaving a smaller gap if and when dissolution occurred and that would be an advantage. In reality, lateral condensation actually produces voids by placing pressure on the gutta percha, deforming it in the process and producing pressures that lead to the extrusion of more cement coronally. The gutta percha being rubber like in its properties rebounds once the pressure from condensation is removed??leaving a void that was not there prior to lateral condensation. In short, a well fitted single point placed in a canal completely flooded with cement represents an excellent seal that need not be further tampered with.

?Now obviously, what is critical is the use of a cement that is highly resistant to??dissolution along with a bunch of other favorable properties. I personally like epoxy resins, a sealer that is highly resistant to dissolution, bonds to dentin and gutta percha both physically and chemically, is dimensionally stable, highly antibacterial, very flowable effectively penetrating the dentinal tubules and most important has a 75 year history of successful clinical usage. There are no surprises when using this material.

This simplified room temperature system in contrast to thermoplastic techniques is quite inexpensive, unlikely to be misapplied giving the dentist consistent results. Most important, it is a room temperature system. Shrinkage will not occur. In fact, as the cement and gutta percha warm to body temperature, they expand slightly producing a superior seal that is the exact opposite of the shrinkage that occurs when employing thermoplastic techniques. I prefer systems that subject the tooth to the least amount of stresses. This is so when we apply the oscillating reamers to the canal walls limited to a 30o arc of motion. It is also so, when we need not apply lateral and vertical condensation that can measurably impact the walls of the tooth. I’m all for simplification as long it does not become simplistic, a way to dumb things down, but at the expense of the tooth.

I’ll be talking a bit about obturation at the lectures at the GNYDM, hopefully in person and not on Zoom. I’m most looking forward to the feedback from the attendees.

Regards, Barry