dentalblogs.com

There are three basic steps associated with root canal treatment. These include 1) debridment (reamers and filers), 2) sterilization (NaOCl and EDTA) and 3) obturation (gutta percha). Each of these three distinct phases of this specialty have been given considerable attention in terms of research and practice.

The use of gutta-percha as an obturation material has been around a long time. In fact gutta percha was first used as early as 1833 as an agent wrapped around gold wires. The first clinical reports on the use of the material occurred in 1847 centered around the efforts of Dr. Hill who described his device simply as Hill’s stopping. Finally, the first major company marketed gutta-percha as an obturation material in 1877, nearly a century and a half ago. Over the course of the years some minor modifications in the composition of this naturally occurring material have been made. At the present time however, the basic composition of the gutta-percha obturation material is as follows: Gutta-Percha, white wax, zinc oxide , metal slats and some anti-microbial agents.

Although gutta-percha has been the material of choice for many years, it is not an ideal material. In fact one of its most important deficiencies is its potential for leakage, particularly microbial leakage. And this negative characteristic of gutta-percha represents the single most significant reason why root canal treatment must be redone. Incidentally, the values offered in the literature for remake percentages depend upon what group of clinicians performed the original treatment. These figures suggest that the remake rate is about 20% higher when done by a general practitioner as compared to those completed by an endodontist specialist. Finally, the source of microbial leakage and failure has now shifted for some reason from an apical site to one that is more coronal.

In an effort to resolve the problems of microbial leakage and clinical failure, a new type of obturating agent has been developed and introduced to the dental profession. Rather than consisting of a natural rubber, this new and innovative system is a polymer with the entire characteristic of gutta-percha except that it can be readily bonded to the sealer which in turn can be bonded to the walls of the instrumented chamber. Although all of the handling features resemble that of gutta-percha, its radiopacity is superior. Identified as Resilon, this obturating material is polyester.

Another great feature of the Resilon system is that it can be readily impregnated into and through the dentinal tubules of the root which in turn produces a strengthening effect. A number of studies have demonstrated that the impregnation of the radicular tubules will increase the fracture resistance of the root by at least 30%. In fact one Italian study (Ferrari, 2004) has reported a near 80% increase in fracture resistance. One the face of the advantages offered by Resilon the following statements can be made:

1) Enhanced root fracture
2) Better radiopacity than GP
3) Dual cure capabilities for immediate coronal seal
4) Causes less irritation than epoxy or ZOE sealers
5) No learning curve beyond the traditional GP approach
6) Elimination or considerable reduction in microbial leakage
The Resilon obturation systems consists of three major components which includes 1) the primer, 2) the sealer and 3) the obturator.

Each of these components is described as follows:

Primer
The primer is a self-etching system that is cured by the sealer. The primer penetrates all the dentinal tubules to the cemental surface. This process increases fracture resistance of the root by at east 30%. The bonding procedure is preceded by irrigating first with a 17% solution of EDTA. This last process is necessary for removing oxide radicals from the NaOCl and peroxides. Failure to do so will cause an interference with the curing potential of the dentin bonding agent.

Sealer
The sealer bonds to the primer thereby eliminating potential for microleakage. The sealer used in this system is dual-curable, contains calcium hydroxide and a rdiopaque barium glass. As already indicated it contains the catalyst that sets up the self-etching primer in the dentinal tubules. In the possible presence of microbes (decreased pH), calcium hydroxide increases its pH to 11.0 automatically.

Obturator
The Resilon obturator is a thermoplastic polyester and contains the following components: 1) bioactive glass, 2) barium sulfate and 3) bismuth oxychloride. The bioglass is a unique component that forms calcium/phosphate when in contact with body fluid. It does not dissolve in fluid but instead it releases ions to stimulate the formulation of osseous tissue. And as already mentioned, its radiopacity is better than GP, condenses laterally and vertically as GP and softens at around 70 to 85 C. Finally, the Resilon obturator bonds to the surface of the sealer which in turns bonds to the primer which has hybridized with the tubular surfaces.

Retreatment: Should such a procedure be necessary, the Resilon can be softened by heating and/or chloroform. The entire retreatment process can be accomplished in as little as 15 minutes.

The introduction of Resilon as an obturating device with excellent bonding abilities has certainly stimulated much of the dental profession. Presently the only group that seemingly is opposed to the concept of this exciting new system is a competing company (Dentsply/Tulsa) who stands to lose significant monies if/when this new kid on the block takes total control. And so far they are generating a considerable amount of noise in an effort to derail this fantastic system of obturation which seals extremely well against microbial transfer and infection.