Warm carrier-based obturation: The great divide

Jan. 1, 2007
In 1993, Dr. Gordon Christensen said, “Introduced a few years ago as the product Thermafil, this concept has achieved more rapid and wide acceptance than any new endodontic technique for decades.

In 1993, Dr. Gordon Christensen said, “Introduced a few years ago as the product Thermafil, this concept has achieved more rapid and wide acceptance than any new endodontic technique for decades.... For difficult curved canals and other peculiar endodontic situations performed by general practitioners, this concept probably provides better patient service than traditional endodontic treatment.”

Warm carrier-based, thermosoftened endodontic obturation products exist in the form of ProSystem GT Obturators (Dentsply, Tulsa Dental, Tulsa, Okla.), Soft Core (Axis Dental, Coppell, Texas), Densfil (Dentsply, Maillefer N.A., Tulsa, Okla.), and Thermafil (Dentsply, Tulsa Dental). Because of its position in the marketplace, this column will just reference Thermafil. Are these valid and acceptable methods for root canal obturation? Can excellent results be provided with these methods? The answer to both questions is “yes.” But is this the whole story? Is Dr. Christensen’s statement valid in 2006?

A comprehensive review of endodontic literature does not demonstrate a clear and statistically significant superiority of any method of obturation. In much the same way, no single rotary nickel titanium file has been unequivocally demonstrated to be superior to another. As a result, there are two ways to proceed: 1) clinicians can continue research to ascertain features, functions, and clinical outcomes of available obturation methods, and 2) with their clinical experiences, clinicians can - individually and collectively - make judgments regarding what the state of the art is and should be.

I am sure it is possible to find an endodontist who might advocate warm carrier-based products of various types or who uses these products. But I do not know any personally. I have never met any full-time private practice endodontists who use these products, although I am sure there are some. If so, what percentage of the global population of specialists do they represent? In addition, do these endodontists actually make their living from performing endodontic procedures full time, or are they merely advocates with commercial interests?

There is a tremendous divide in the endodontic world between those who use Thermafil and those who do not. As a general rule, endodontists do not use it, although some percentage of the general dental population in North America and elsewhere do.

There are many ways to look at this. If endodontists educate general dentists about their specialty, then they may not be doing the job. Another view might be that there is something inherently appealing to the general practitioner about warm carrier-based products that is not appealing to the endodontist.

With all due respect to Dr. Christensen, I disagree with his claim that Thermafil provides a “better service.” Based on the number of specialists who use the material, I believe they would disagree with him as well. If it were a “better service,” the vast majority of endodontists - myself included - would be using it. In my opinion, it is expensive relative to the alternatives, is consistent with extrusion from a patent foramen, can be challenging to remove, and cannot be bonded into canals as Resilon (Pentron, Wallingford, Conn.) and RealSeal (SybronEndo, Orange, Calif.). With current options available, I believe carrier-based methods are not - despite their validity - the best choice for endodontic obturation. For the reasons given, I think Thermafil most likely has made few inroads into specialty practice.

In my years as a specialist, I have had to re-treat this product too often to want to use it clinically. My greatest reservation has been the necessity to leave a carrier. In more than a few cases, I have observed an under-prepared canal with a carrier that is tightly wedged and occupies almost the entire canal (especially coronally).

Despite the recommended methods of removal, when this happens, it becomes necessary to literally grind into the plastic of the carrier to create a pathway alongside it. In my view, this is not a valid exchange in placing carriers to length considering the time needed to remove them if a difficulty arises. I think that many of the clinicians who place Thermafil might never have attempted removal. This might account for the differences in clinical viewpoint between the general dentist and the specialist on this subject. SystemB obturation of a master cone and the aforementioned bonded obturation with a unit like the Elements obturation unit (SybronEndo), can go a long way toward avoiding the issues that arise from warm carrier-based products.

I welcome your feedback and questions.

Dr. Richard Mounce lectures globally and is widely published. He is in private practice in endodontics in Portland, Ore. Among other appointments, he is the endodontic consultant for the Belau National Hospital Dental Clinic in the Republic of Palau, Korror, Palau (Micronesia). He can be reached at [email protected].

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